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TY - JOUR. T1 - Proteolytic processing of Escherichia coli twin-arginine signal peptides by LepB. AU - Luke,Iris. AU - Handford,Jennifer I.. AU - Palmer,Tracy. AU - Sargent,Frank. PY - 2009/12. Y1 - 2009/12. N2 - The twin-arginine translocation (Tat) apparatus is a protein targeting system found in the cytoplasmic membranes of many prokaryotes. Substrate proteins of the Tat pathway are synthesised with signal peptides bearing SRRxFLK twin-arginine amino acid motifs. All Tat signal peptides have a common tripartite structure comprising a polar N-terminal region, followed by a hydrophobic region of variable length and a polar C-terminal region. In Escherichia coli, Tat signal peptides are proteolytically cleaved after translocation. The signal peptide C-terminal regions contain conserved AxA motifs, which are possible recognition sequences for leader peptidase I (LepB). In this work, the role of LepB in Tat signal peptide processing was addressed directly. Deliberate repression of lepB ...
The signal peptide of the outer membrane lipoprotein (OMLP) of Escherichia coli was shown to be capable of promoting protein translocation across mammalian microsomal membranes in vitro. We assayed translocation of a fusion protein containing the OMLP signal peptide and nine amino acids of OMLP fused in frame to beta-lactamase. The efficiency with which the mammalian translocation machinery recognizes and accepts the OMLP signal peptide as substrate is indistinguishable from that of mammalian secretory proteins. Upon translocation mammalian signal peptidase processes the pre-OMLP-beta-lactamase protein at different sites than are utilized in vivo by E. coli OMLP signal peptidase (signal peptidase II) but that can be predicted as mammalian signal peptidase cleavage sites. Mutants in the OMLP signal peptide were tested for their ability to promote translocation of the fusion protein in this assay system. It has been shown previously that mutants in the positively charged amino acids at the amino ...
Signal sequences are the addresses of proteins destined for secretion. In eukaryotic cells, they mediate targeting to the endoplasmic reticulum membrane and insertion into the translocon. Thereafter, signal sequences are cleaved from the pre-protein and liberated into the endoplasmic reticulum membrane. We have recently reported that some liberated signal peptides are further processed by the intramembrane-cleaving aspartic protease signal peptide peptidase. Cleavage in the membrane-spanning portion of the signal peptide promotes the release of signal peptide fragments from the lipid bilayer. Typical processes that include intramembrane proteolysis is the regulatory or signalling function of cleavage products. Likewise, signal peptide fragments liberated upon intramembrane cleavage may promote such post-targeting functions in the cell.. ...
The Tat system is a protein export system dedicated to the transport of folded proteins across the prokaryotic cytoplasmic membrane and the thylakoid membrane of plant chloroplasts. Proteins are targeted for export by the Tat system via N-terminal signal peptides harbouring an S-R-R-x-F-L-K twin-arginine motif. In this chapter qualitative and quantitative assays for native Tat substrates in the model organism Escherichia coli are described. Genetic screening methods designed to allow the rapid positive selection of Tat signal peptide activity and the first positive selection for mutations that inactivate the Tat pathway are also presented. Finally isothermal titration calorimetry (ITC) methods for measuring the affinity of twin-arginine signal peptide-chaperone interactions are discussed.
Plastids are considered promising bioreactors for the production of recombinant proteins, but the knowledge of the mechanisms regulating foreign protein folding, targeting, and accumulation in these organelles is still incomplete. Here we demonstrate that a plant secretory signal peptide is able to target a plastome-encoded recombinant protein to the thylakoid membrane. The fusion protein zeolin with its native signal peptide expressed by tobacco (Nicotiana tabacum) transplastomic plants was directed into the chloroplast thylakoid membranes, whereas the zeolin mutant devoid of the signal peptide, Dzeolin, is instead accumulated in the stroma. We also show that zeolin folds in the thylakoid membrane where it accumulates as trimers able to form disulphide bonds. Disulphide bonds contribute to protein accumulation since zeolin shows a higher accumulation level with respect to stromal Dzeolin, whose folding is hampered as the protein accumulates at low amounts in a monomeric form and it is not ...
N-terminal signal sequences mediate targeting of nascent secretory and membrane proteins to the endoplasmic reticulum (ER) in a signal recognition particle (SRP)-dependent manner. Signal sequences have a tripartite structure, consisting of a hydrophobic core region (h-region) flanked by an n- and c-region. The latter contains the signal peptidase (SPase) consensus cleavage site. Usually, signal sequences are cleaved off co-translationally so that signal peptides and mature proteins are generated. Signal sequences are extremely variable in length and amino acid composition. This variability suggests that ER targeting and the steps beyond like protein insertion and SPase cleavage are affected by the signal sequence ...
New prediction server avaliable: Sigfind - Signal Peptide Prediction Server (Human) at http://www.stepc.gr/~synaptic/sigfind.html (C)opyright 2001 by Martin Reczko (martin at stepc.gr) This software (SIGFIND) predicts signal peptides at the start of protein sequences. A novel neural network learning algorithm is used for prediction. It is trained on the human protein data used for the SIGNALP system described in H.Nielsen, J.Engelbrecht, S.Brunak, and G.von Heijne: Identification of prokaryotic and eukaryotic signal peptides and prediction of their cleavage sites Protein Engineering, vol. 10 no. 1 pp. 1-6, 1997 The SIGNALP data is derived from A.Bairoch and B.Boeckmann: The SWISS-PROT protein sequence data bank: current status, Nucleic Acids Res. 22:3578-3580 (1994). Using the same fivefold crossvalidation as SIGNALP, the 5 networks of SIGFIND (avgerage Mathews correlation coefficiant 0.98) perform better than SIGNALP (avgerage Mathews correlation coefficiant 0.96). It should be noted that ...
To achieve synthetic control over how a cell responds to other cells or the extracellular environment, it is important to reliably engineer proteins that can traffic and span the plasma membrane. Using a modular approach to assemble proteins, we identified the minimum necessary components required to engineer such membrane-spanning proteins with predictable orientation in mammalian cells. While a transmembrane domain (TM) fused to the N-terminus of a protein is sufficient to traffic it to the endoplasmic reticulum (ER), an additional signal peptidase cleavage site downstream of this TM enhanced sorting out of the ER. Next, a second TM in the synthetic protein helped anchor and accumulate the membrane-spanning protein on the plasma membrane. The orientation of the components of the synthetic protein were determined through measuring intracellular Ca2+ signaling using the R-GECO biosensor and through measuring extracellular quenching of yellow fluorescent protein variants by saturating acidic and salt
Background and aims: Signal peptides are central to biological processes in that they direct proteins to their proper destination after synthesis. If the signal sequence in a nascent was changed, the protein could end up in a wrong cellular location. Some proteins known to be secreted have had their signal peptides unpredicted by existing signal peptide prediction tools. The aim of this study is to pre-process these proteins in order to optimize their start sites and apply a combined set of tools to finding their signal peptides ...
PelB Leader Sequence Cleavage - posted in Protein and Proteomics: I have designed a fusion peptide that is being inserted into pET22b at the MscI restriction site. It would appear that the PelB signal peptide cleavage site has been removed in my design process. What is the consequence of not removing the leader sequence in protein expression? If it is to be a problem then I would like to know as soon as possible so I can by a new primer and add the necessary sequence bac...
Exported prokaryotic proteins typically contain an amino-terminal extension called the signal peptide. Although signal sequences display little primary sequence homology, they share features which promote secretion through the same pathway. These characteristics include a net positive charge in the amino-teminus, a hydrophobic core with $\alpha$-helical propensity, and a cleavage region which contains small side chain residues in the $-$1 and $-$3 positions. The goals of this research are to further analyze the requirement for each property, to determine whether the different features operate at concurrent steps and, ultimately, to correlate the physical features with their functional role(s).^ The alkaline phosphatase signal sequence represents a typical signal peptide and serves as a prototype for designing mutants with simplified sequences that facilitate the delineation of the required physical features. A series of signal sequences varying in amino terminal charge and core region hydrophobicity
... predicts the presence and location of Twin-arginine signal peptide cleavage sites in bacteria. The method incorporates a prediction of cleavage sites and a signal peptide/non-signal peptide prediction based on a combination of two artificial neural networks. A postfiltering of the output based on regular expressions is possible. View the version history of this server. All the previous versions are available on line, for comparison and reference ...
Translocation of a nascent protein from the cytosol into the ER mediated by its signal peptide is a critical step in protein secretion. The aim of this work was to develop a platform technology to optimize the signal peptides for high level production of therapeutic antibodies in CHO cells. A database of signal peptides from a large number of human immunoglobulin (Ig) heavy chain (HC) and kappa light chain (LC) was generated. Most of the HC signal peptides contain 19 amino acids which can be divided into three domains and the LC signal peptides contain 22 amino acids. The signal peptides were then clustered according to sequence similarity. Based on the clustering, 8 HC and 2 LC signal peptides were analyzed for their impacts on the production of 5-top selling antibody therapeutics, namely, Herceptin, Avastin, Remicade, Rituxan, and Humira. The best HC and LC signal peptides for producing these 5 antibodies were identified. The optimized signal peptides for Rituxan is 2-fold better compared to its
The cleavage site of a signal peptide located in the C-region can be recognized by the signal peptidase in eukaryotic and prokaryotic cells, and the signal peptides are typically cleaved off during or after the translocation of the target protein. The identification of cleavage sites remains challenging because of
PPIA-like Cyps with signal peptide. Domain architecture and genomic organization of Cyps with signal peptide are shown. Species are abbreviated as in Fig. 1. Cy
SET OF SEQUENCES FOR TARGETING EXPRESSION AND CONTROL OF THE POST-TRANSLATIONAL MODIFICATION OF A RECOMBINANT POLYPEPTIDE - The present invention provides new tools useful for controlling the post-translational modifications of recombinant polypeptides. These tools are particular signal peptides allowing the targeting of recombinant polypeptides during their synthesis in a host cell to specific sub-cellular compartments and a specific designing of said recombinant polypeptides within said sub-cellular compartments. These signal peptides are SEQ ID no 1 to SEQ ID no 31 disclosed herein. The present invention relates therefore also to a process for producing a recombinant polypeptide, in particular to a post-translationally modified polypeptide comprising the steps of transfecting or transforming a cell with at least one numleic acid vector encoding a recombinant protein which is the polypeptide before being post-translationally modified or a recombinant protein different to said polypeptide, said ...
Optical mapping of the internal signal is a unique method of studying the brain and makes it possible to investigate the functional anatomy of the cerebral cortex with high spatial resolution. Modern modifications of this method make it possible to shorten the time to obtain individual functional maps, and this opens up new prospects of using the given approach in neurophysiological experiments. It is shown to be possible in principle to use optical mapping of the internal signal to objectively test the visual function: As the contrast of the visual stimulus changes, changes have been observed in both the amplitude of the metabolic response in the cortex and in the structure of the functional maps.. © 2011 OSA. PDF Article ...
A chimeric mammalian globular cytochrome b(5) fused to Escherichia coil alkaline phosphatase signal sequence (SS) was used as a model probe to investigate the influence of substituting each one of the standard 20 amino ...
0024] (12) According to an aspect of the embodiments, a medium includes a computer-readable recording medium storing a signal processing program for causing, in a signal processing apparatus for predicting a value of an input time series signal after predetermined time, a computer to implement a prediction function is recorded, the signal processing program causing the computer to implement a cycle fluctuation analysis function for assuming a certain component of an input time series signal as a time series signal whose cycle varies with respect to time to carry out a correlation analysis between part of the input time series signal and the input time series signal, estimating a cycle fluctuation of the input time series signal and reliability of the cycle fluctuation using a result of the correlation analysis, predicting a cycle of the input time series signal after predetermined time using the cycle fluctuation and the reliability of the cycle fluctuation and calculating, using the result of ...
A method for classifying a signal is disclosed. The method can be used by a station or stations within a network to classify the signal as non-cooperative (NC) or a target signal. The method performs classification over channels within a frequency spectrum. The percentage of power above a first threshold is computed for a channel. Based on the percentage, a signal is classified as a narrowband signal. If the percentage indicates the absence of a narrowband signal, then a lower second threshold is applied to confirm the absence according to the percentage of power above the second threshold. The signal is classified as a narrowband signal or pre-classified as a wideband signal based on the percentage. Pre-classified wideband signals are classified as a wideband NC signal or target signal using spectrum masks.
Find Periodicity Using Frequency Analysis. Spectral analysis helps characterize oscillatory behavior in data and measure the different cycles.. Detect a Distorted Signal in Noise. Use frequency analysis to characterize a signal embedded in noise.. Measure the Power of a Signal. Estimate the width of the frequency band that contains most of the power of a signal. For distorted signals, determine the power stored in the fundamental and the harmonics.. Compare the Frequency Content of Two Signals. Identify similarity between signals in the frequency domain.. Detect Periodicity in a Signal with Missing Samples. Use the Lomb-Scargle periodogram to study the periodicity of an irregularly sampled signal.. ...
NT3 Protein, 5 µg. Neurotrophin-3 (NT-3), also known as nerve growth factor-2 (NGF2) or hippocampus-derived neurotrophic factor (HDNF), is a 257 amino acid precursor protein with a secretory signal sequence of 16 amino acids, a pro-peptide of 122 amino
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A system of coding moving image signals produces a predictive error signal by a predictive coding based on inter-frame correlation and quantizing the predictive error signal for each block of a picture frame constituted by N lines of M pixels. The system includes a block coding/non-coding decision unit for calculating a first evaluation value Sm of the predictive error signal for each block of the picture frame. This unit decides that block non-coding is applicable when the first evaluation value Sm is less than a first threshold value T.sub.1 and that block coding is applicable when the first evaluation value Sm is greater than the first threshold value T.sub.1. The predictive error signal is not transmitted when the result of the decision is for block non-coding, and the predictive error signal is quantized and transmitted when the result of the decision is for block coding.
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Ive been fighting with this for a while, too. However, its not as simple as using sigaction (or sigvec) in place of signal where possible. Some systems dont return EINTR from select even when a signal is set with the SA_RESTART (or SA_INTERRUPT) flag set in these two calls. The issue is that some systems set the signal, and the first thread to notice the signal will service it. If the thread that has called select is not the thread to pick up the signal, the select call will not return with EINTR ...
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Signal weights corresponding to an initial system of equations with a block coefficient matrix T|sub|0 |/sub|can be obtained from the solution to a system of equations with a block coefficient matrix
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signal = zeros(size(LCOClose)); signal(Lead , Lag) = 1; % Buy (long) signal(Lead , Lag) = -1; % Sell (short) trades = [0; 0; diff(signal(1:end-1))]; % shift trading by 1 period cash = cumsum(-trades.*LCOClose); pandl = [0; signal(1:end-1)].*LCOClose + cash; returns = diff(pandl); annualScaling = sqrt(250); sharpeRatio = annualScaling*sharpe(returns,0); % Annual Sharpe ratio ...
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Oriel Instruments offers a wide choice of detectors and detection systems. The systems can be selected based on the types of signals, namely continous wave (CW) signal, modulated signal, and pused ...
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We investigated the metabolic stability of four cell penetrating peptides (CPPs), namely SAP, hCT(9-32)-br, [Palpha] and [Pbeta], when in contact with either subconfluent HeLa, confluent MDCK or Calu-3 epithelial cell cultures. Additionally, through analysis of their cellular translocation efficiency, we evaluated possible relations between metabolic stability and translocation efficiency. Metabolic degradation kinetics and resulting metabolites were assessed using RP-HPLC and MALDI-TOF mass spectrometry. Translocation efficiencies were determined using fluorescence-activated cell sorting (FACS) and confocal laser scanning microscopy (CLSM). Between HeLa, MDCK and Calu-3 we found the levels of proteolytic activities to be highly variable. However, for each peptide, the individual degradation patterns were quite similar. The metabolic stability of the investigated CPPs was in the order of CF-SAP = CF-hCT(9-32)-br , [Pbeta]-IAF , [Palpha] and we identified specific cleavage sites for each of the ...
In the process of protein secretion, amino-terminal signal sequences are key recognition elements; however, the relation between the primary sequence of an amino-terminal peptide and its ability to function as an export signal remains obscure. The limits of variation permitted for functional signal sequences were determined by replacement of the normal signal sequence of Saccharomyces cerevisiae invertase with essentially random peptide sequences. Since about one-fifth of these sequences can function as an export signal the specificity with which signal sequences are recognized must be very low.. ...
The signal recognition particle (SRP) recognizes and binds the signal sequence of nascent proteins as they emerge from the ribosome. We present here the 3.0-Å structure of a signal sequence bound to the Methanococcus jannaschii SRP core. Structural comparison with the free SRP core shows that signal-sequence binding induces formation of the GM-linker helix and a 180° flip of the NG domain-structural changes that ensure a hierarchical succession of events during protein targeting.. ...
To generate a simplified signal sequence, we substituted a part of the yGLuc hydrophobic core with repeats of a single amino acid. The VLFALICI sequence was initially substituted to contain an eight residue repeat of a single amino acid (Figure 3). L8, M8, W8, and F8 increased secreted protein activity but repeats containing other residues (I, T, S, Q, Y, A, V, and C) did not. This result indicated that a complex amino acid sequence such as VLFALICI can be substituted with a repeat of select, single amino acids. Furthermore, although eight residue repeats of the residues I, T, S, Q, Y, A, V, and C, appeared not to be suitable, or too weak for a hydrophobic core; in fact, a hydrophobic core consisting of I12 and I13 was able to function as a signal sequence (Figure 5a). Therefore, the hydrophobic core in a signal sequence can be determined by the number of hydrophobic amino acids without including charged amino acids such as E, D, R, and K. Moreover, the efficiency of secretory production can be ...
The utilization of highly heterologous secreted lactoprotein signal peptides to guide the recombinant proteins to translocation and secretion in mammary gland bioreactors has rarely been reported. The first step in the synthesis of secretory proteins is generation of a signal peptide containing 15-30 hydrophobic amino acid residues in the cell matrix. When the polypeptide chain extends to approximately 80 amino acids, the signal peptide directs the synthesizing polypeptide chain into the lumen of the ER. The signal peptidase on the endoplasmic reticulum (ER) then cleaves the signal peptide and continues to extend the polypeptide chain until synthesis of the entire polypeptide chain is completed [33-35]. The translocation of secretory proteins into the lumen of the ER constitutes the limiting step within the classical secretory pathway [36]. The secretion of t-PA from vascular endothelial cells to blood is mediated by its native signal peptide at a low yield [37,38]. However, we report here the ...
The service provides predictions of genetic structures based on neural network algorithms and Markov statistical models. It analyzes data about the frequency of amino acid sequences for various organisms and generates likely existence and locations of signal peptide cleavage sites to be expected in their genetic structures. Organism groups covered include gram-positive and gram-negative prokaryotes as well as eukaryotes. The same provider maintains an [[http://www.cbs.dtu.dk/ws/ws.php?entry=SignalP4 alternative service]], as well. API methods support submission of the amino acid sequence to be analyzed along with an organism type, preferred prediction method, and desired statistical prediction certainty threshold. Methods also support monitoring the service processing queue and retrieving the completed analytical result ...
Intramembrane proteases cleave peptide bonds within cellular membranes and thereby control important processes ranging from transcription regulation to growth factor secretion (Lemberg, 2011). The largest and most diverse group of these unusual enzymes is formed by the GxGD aspartyl proteases including presenilin/γ‐secretase as well as signal peptide peptidase (SPP) (Wolfe, 2009; Lichtenthaler et al, 2011). SPP localizes to the endoplasmic reticulum (ER) where it cleaves signal peptides that have been removed from precursors of secretory and membrane proteins (Weihofen et al, 2002). Like for most characterized intramembrane proteases, this release is part of a two‐step mechanism: First signal peptidase cleaves off the substrate proteins ectodomains, which enables the subsequent SPP‐catalyzed intramembrane cut (Lemberg & Martoglio, 2002). So far, known functions of SPP include generation of signal peptide‐derived bioactive peptides in immune surveillance and proteolytic maturation of ...
Signal recognition particle (SRP) consists of a 7SL RNA molecule and 6 protein subunits. We have isolated and characterized cDNA clones from human liver which encode the 19kDa protein subunit (SRP19). This subunit binds to the RNA directly and mediates binding of a second polypeptide, the 54kDa subunit which is involved in signal sequence recognition. Amino acid sequences deduced from the human cDNA sequence were identical to amino acid sequences of tryptic peptides from canine pancreatic SRP19. In vitro transcription and translation of the human cDNA resulted in a protein product the same size as canine SRP19 which could be immunoprecipitated by an antiserum raised against canine SRP19. SRP19 synthesized in a cell-free system specifically bound to 7SL RNA. The sequence of SRP19 is discussed with respect to its binding to 7SL RNA.. ...
Cells need powerhouses known as mitochondria to utilize the energy stored in our food. Most of the proteins required for this powerhouse function are encoded in the nucleus and transported into the mitochondria after they have been synthesized in the cytosol. Signal sequences are needed to allow the protein to enter the mitochondria. Once the protein has arrived there, the signal sequences are, however, removed. Up until now, researchers did not fully understand the importance of this removal of signal sequences. It was also unclear why flawed removal leads to a number of illnesses, such as diseases of the heart or brain. Together with her working group, Dr. Nora Vögtle of the Institute of Biochemistry and Molecular Biology of the University of Freiburg has discovered that errors in the removal of signal sequences lead to an aggregation of these proteins so that they clump together inside the mitochondria. They have presented their findings in the current issue of the scientific journal ...
Sigma-Aldrich offers abstracts and full-text articles by [John M Harrington, Tuiumkan Nishanova, Savannah Rose Pena, Matthew Hess, Chris L Scelsi, Justin Widener, Stephen L Hajduk].
The ER-resident MHC class I PLC forms a key target for viral immune evasion. When analyzing the subcellular distribution of BNLF2a, we observed strict membrane association and colocalization with TAP and the ER markers calnexin and PDI (Figs. 1⇑, 2⇑, 6⇑D, and 7B), reminiscent of two other TAP inhibitors, HCMV US6 (35, 36) and BHV-1 UL49.5 (33). The latter two represent integral type I membrane proteins with cleavable signal sequences at their N termini for cotranslational membrane insertion, as well as transmembrane domains toward their C termini. In contrast, BNLF2a lacks an obvious N-terminal signal sequence (Fig. 1⇑A). Still, the EBV-encoded TAP inhibitor is membrane associated and, even in the absence of TAP, localizes to the ER (Fig. 6⇑D). In this respect, BNLF2a differs from HSV ICP47, which also lacks a signal sequence but has been detected primarily as a cytosolic protein with small amounts associating with membranes (26, 31). ICP47 is unstructured in aqueous solutions but ...
In eukaryotic cells, most mRNAs are exported from the nucleus by the transcription export (TREX) complex, which is loaded onto mRNAs after their splicing and capping. We have studied in mammalian cells the nuclear export of mRNAs that code for secretory proteins, which are targeted to the endoplasmic reticulum membrane by hydrophobic signal sequences. The mRNAs were injected into the nucleus or synthesized from injected or transfected DNA, and their export was followed by fluorescent in situ hybridization. We made the surprising observation that the signal sequence coding region (SSCR) can serve as a nuclear export signal of an mRNA that lacks an intron or functional cap. Even the export of an intron-containing natural mRNA was enhanced by its SSCR. Like conventional export, the SSCR-dependent pathway required the factor TAP, but depletion of the TREX components had only moderate effects. The SSCR export signal appears to be characterized in vertebrates by a low content of adenines, as ...
A multi-speed jittered signal generator (216, 400) that generates a full-speed jittered signal (404) by scaling a low-speed jittered signal (420) using a frequency scaler (428). The low-speed jittered signal is created by injecting a modulation signal (416) into a reference signal (412) using a jitter injector (432). Injecting jitter into a low-speed reference signal allows the full-speed jittered signal to be of higher quality than conventional jitter signals created by injecting jitter information into a full-speed reference signal. The multi-speed jittered signal generator may be used as part of a testing system (208) for testing various circuitry, such as high-speed serializer/deserializer circuitry (220).
Bacterial secretory signal peptide expression plasmid with the T7 promoter upstream to drive gene expression (Frame 1 - NcoI site aligned).
Fang P et al. (2006) A mutant signal transducer and activator of transcription 5b, associated with growth hormone insensitivity and insulin-like growth factor-I deficiency, cannot function as a signal transducer or transcription factor.. [^] ...
A method for designing an integrated circuit such as a VLSI circuit, in particular optimizing delay of a signal transmitting through signal lines connecting a signal supplying source to each of elements, whereby skew can be decreased. The method can include determining whether the signal source satisfies a fan-out restriction if the signal source supplies a signal to all of the driven elements which are directly connected to the signal source, dividing the elements into groups so that the fan-out restriction is satisfied in each of the groups and each of the groups has the same or substantially same load capacity, when the signal source does not satisfy the fan-out restriction, and inserting into each group, a buffer having a size which makes the groups of elements satisfy the fan-out restriction. The dividing and the buffer inserting are repeated until a positive determination is delivered on the fan-out restriction.
This disclosure describes methods and systems for encoding and decoding signals from a host signal such as audio, video or imagery. One claim recites a method comprising: receiving a host signal carrying an auxiliary signal; extracting data representing at least some features of the host signal, said extracting utilizes one or more processors; using the data representing at least some features of the host signal to determine a key; and detecting the auxiliary signal in a transform domain associated with the key, the detecting utilizes one or more processors. Other claims and combinations are provided as well.
A low cost, high frequency isolation amplifier includes a first voltage-to-frequency converter producing a first pair of complementary pulses in response to an analog input signal and applying them to a pair of low capacitance capacitors constituting the isolation barrier. The isolation barrier differentiates edges of the first pair of pulse signals and applies the resulting signals to inputs of a sense amplifier including a differential amplifier, a pair of comparators, and a flip-flop to precisely reconstruct the first pair of complementary pulse signals, which then are fed into a decoder circuit including a phase locked loop. The phase locked loop includes a phase detector receiving the reconstructed pair of complementary pulse signals and a second pair of complementary pulse signals produced by a second voltage-to-frequency converter. The output of the phase detector is integrated by a filter circuit, the output of which produces a voltage that
Genetic information processingProtein fateProtein and peptide secretion and traffickingTat (twin-arginine translocation) pathway signal sequence (TIGR01409; HMM-score: 25.5) ...
Sometimes a component wants to send notifications via DCOP to other components but does not know which components will be interested in these notifications. One could use a broadcast in such a case but this is a very crude method. For a more sophisticated method DCOP signals have been invented. DCOP signals are very similair to Qt signals, there are some differences though. A DCOP signal can be connected to a DCOP function. Whenever the DCOP signal gets emitted, the DCOP functions to which the signal is connected are being called. DCOP signals are, just like Qt signals, one way. They do not provide a return value. A DCOP signal originates from a DCOP Object/DCOP Client combination (sender). It can be connected to a function of another DCOP Object/DCOP Client combination (receiver). There are two major differences between connections of Qt signals and connections of DCOP signals. In DCOP, unlike Qt, a signal connections can have an anonymous sender and, unlike Qt, a DCOP signal connection can be ...
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9780815345343: Cellular Signal Processing: An Introduction to the Molecular Mechanisms of Signal Transduction, Friedrich Marks, Ursula Klingmüller, Karin Müller-Decker - Cellular Signal Processing offers a unifying view of cell signaling based on the conc
Bilinear synthesis of nonstationary signals impinging on a multiantenna receiver has been recently introduced. The distinction in the spatial signatures of the sources provides a vehicle to reduce noise and source signal interactions in the time-frequency domain, and hence improves signal synthesis..... Full description. ...
Signal transduction is any process by which a cell converts one kind of signal or stimulus into another. Processes referred to as signal transduction often involve a sequence of biochemical reactions inside the cell, which are carried out by enzymes and linked through second messengers. ...
A method for processing a multichannel audio signal may be configured to control the amplitude of one channel of the signal relative to another based on the levels of the two channels. One such example uses a bias factor, which is based on a standard orientation of an audio sensing device relative to a directional acoustic information source, for amplitude control of information segments of the signal.
Emergent CAS agents can use the ability to respond differently to different signal strengths to create models of their local environments. In effect when the signals vary with range across the local environment they provide the coordinates of a map. This can be used to coordinate the responses of neighboring cells, via the schematic models that associate particular cascades with the local environmental state ...
Histogram of log2 average C3B signal. Histogram of log2 average C3B signal for the Stratagene Total Human RNA using the 1,288 genes in common among the three pl
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Standard compressive sensing results state that to exactly recover an s sparse signal in R^p, one requires O(s\cdotlog p) measurements. While this bound is extremely useful in practice, often real world signals are not only sparse, but also exhibit structure in the sparsity pattern. We focus on group-structured patterns in this paper. Under this model, groups of signal coefficients are active (or inactive) together. The groups are predefined, but the particular set of groups that are active (i.e., in the signal support) must be learned from measurements. We show that exploiting knowledge of groups can further reduce the number of measurements required for exact signal recovery, and derive near optimal bounds for the same. The number of measurements needed only depends on the number of groups under consideration, and not the particulars of the groups (e.g., compositions, sizes, extents, overlaps, etc.). The results are also shown to predict experimental performance quite well ...
The biochemical events that conduct the signal of a hormone or growth factor from the cell exterior, through the cell membrane, and into the cytoplasm. This involves a number of molecules, including receptors, proteins, and messengers ...
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IARC has been embroiled in controversy, most recently over its assessment of glyphosate. Does the Agencys plan to update its Preamble signal a change of heart? There are grounds for skepticism.
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Many researchers over the years have worked towards increasing data speeds, something that has had breakthroughs in various ways over the years. The latest one involves a method the creators say is a simple concept, but one that - for whatever reason - was never done. By creating mirrored beams of light that cancel out
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Signal transductionRegulatory functionsDNA interactionsGTP-sensing transcriptional pleiotropic repressor CodY (TIGR02787; HMM-score: 351.8) ...
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Brown adipose tissue has long been known for its heat-producing capacity, but less is known about its possible effects as a secretory organ. This thesis summarizes information about presently known factors secreted from brown adipose tissue and about their actions. We were able to add factors to the list by the use of a signal-sequence trap method. Results from the signal-sequence trap generated a list of suggested brown adipocyte secreted proteins; gene expression of these proteins was then further studied with microarray technique.. One of the genes further analyzed was the adipokine chemerin. Gene expression of chemerin in brown adipose tissue was decreased in cold acclimation but increased with a high-caloric diet. This indicates that factors other than norepinephrine influence chemerin gene expression. The effects on chemerin gene expression were not be reflected in serum levels; therefore, chemerin secreted from brown adipose tissue is ascribed an autocrine/paracrine role.. Signal-sequence ...
In molecular biology, the Signal Peptide Peptidase (SPP) is a type of protein that specifically cleaves parts of other proteins. It is an intramembrane aspartyl protease with the conserved active site motifs YD and GxGD in adjacent transmembrane domains (TMDs). Its sequences is highly conserved in different vertebrate species. SPP cleaves remnant signal peptides left behind in membrane by the action of signal peptidase and also plays key roles in immune surveillance and the maturation of certain viral proteins. Physiologically SPP processes signal peptides of classical MHC class I preproteins. A nine amino acid-long cleavage fragment is then presented on HLA-E receptors and modulates the activity of natural killer cells. SPP also plays a pathophysiological role; it cleaves the structural nucleocapsid protein (also known as core protein) of the Hepatitis C virus and thus influences viral reproduction rate. In mice, a nonamer peptide originating from the SPP protein serves as minor ...
We have previously shown that intracoronary delivery of recombinant adenoviruses encoding angiogenic proteins that contain signal peptides (fibroblast growth factor-4 and fibroblast growth factor-5) ameliorate myocardial ischemia. In the present paper, we test the hypothesis that the presence of the signal peptide is an important element in the favorable effects that transgene expression has on regional flow and function in an animal model of myocardial ischemia. We performed intracoronary delivery of two different recombinant adenoviruses encoding a fibroblast growth factor-2 variant, one with a signal peptide, FGF-2LI(+sp), and one without a signal peptide, FGF-2LI(-sp). In a model of stress-induced myocardial ischemia, intracoronary injection of these recombinants resulted in mRNA and protein expression of the transferred gene. Two weeks after gene transfer, regional abnormalities in stress-induced function and blood flow were improved after delivery of FGF-2LI containing the signal peptide. ...
I would classify the latter paper as bioinformatics and for some reason the Acta Cryst. A paper didnt show up, so lets add "dept chem" to the search instead of restricting the search by subject. One of the co-authors on the Acta Cryst. A paper is from the Department of Chemistry at the University of Aarhus, so thats the top one. The next one is "Identification of prokaryotic and eukaryotic signal peptides and prediction of their cleavage sites" published in Protein Engineering in 1997 with 4,368 citations ...
... 1 http://reasonandscience.heavenforum.org/t2651-signal-recognition-particle-an-essential-pro
The protein export is the active transport of proteins from the cytoplasm to the exterior of the cell, or to the periplasmic compartment in Gram-negative bacteria. The sec dependent pathway is the general protein export system that transports newly synthesized proteins into or across the cell membrane. The translocation channel is formed from a conserved trimeric membrane protein complex, called the Sec61/SecY complex. The twin-arginine translocation (Tat) pathway is another protein transport system that transports folded proteins in bacteria, archaea, and chloroplasts. Many Tat systems comprise three functionally different membrane proteins, TatA, TatB, and TatC, but TatA and TatE seem to have overlapping functions, with TatA having by far the more important role ...
We develop a two-stage spatial point process model that introduces new characterizations of activation patterns in multisubject functional Magnetic Resonance Imaging (fMRI) studies. Conventionally multisubject fMRI methods rely on combining information across subjects one voxel at a time in order to identify locations of peak activation in the brain. The two-stage model that we develop here addresses shortcomings of standard methods by explicitly modeling the spatial structure of functional signals and recognizing that corresponding cross-subject functional signals can be spatially misaligned. In our first stage analysis, we introduce a marked spatial point process model that captures the spatial features of the functional response and identifies a configuration of activation units for each subject. The locations of these activation units are used as input for the second stage model. The point process model of the second stage analysis is developed to characterize multisubject activation patterns by
Signal 1 Poor radio signal Signal 2 Good radio signal Signal 9 Service ambulance (fuel) Signal 12 Out at hospital Signal 13 Possible hazardous situation Signal 16 Intoxicated patient (person) Signal 18 Call by telephone Signal 20 Police needed-non-urgent Signal 21 Police needed-urgent Signal 22 J.P. needed Signal 23 On scene Signal 26 Mentally deranged/demented person Signal 27 Dead body Signal 29 Patient condition-minor Signal 30 Patient condition-moderate Signal 31 Patient condition-serious Signal 32 Patient condition-critical Signal 33 Patient condition-cardiac/respiratory arrest Signal 50 Out for meal Signal 66 Ending tour of duty Signal 211 One additional ambulance needed Signal 311 Two additional ambulances needed Signal 411 Three additional ambulances needed Signal 511 Four additional ambulances needed ...
The signal peptides prediction algorithm SignalP v3.0, subcellular protein location prediction algorithm TargetP.v1.1, potential GPI-anchor sites prediction algorithm big-PI predictor, trans-membrane domains prediction algorithm TMHMM v2.0 and bioinformatics algorithm MEME were used to analyze 16446 protein sequences ofBotrytis cinerea. The results showed that there were 579 deduced secretary proteins. Among these proteins, the minimum and maximum of open read frame were 102 bp and 4848 bps respectively and mean score was 1271 bps. The signal peptides length was concentrated to 16~39 amino acids and the average length was 21. 122 of these proteins contain the highly conserved host-targeting-motif RxLx within 100 residues adjacent to the signal peptide cleavage site. According to PEDNAT and COG of GenBank database, this motifs functions include metabolism modification and cell secretion etc. We blast those putative secretary proteins with RxLx motif in GenBenk and found 47.54% of them have highly
Our goal in this work was to determine if signal peptide peptidase is necessary for normal animal development. We present data showing that Drosophila Spp encodes the fly ortholog of human signal peptide peptidase and show that Drosophila Spp provides an essential function required during the larval stages. We also show that SPP is strongly expressed in only a limited set of cells and that the mutant phenotype is consistent with a need for its function in these tissues. Further work will be needed to establish whether the role of Drosophila SPP is a general one that cleanses membranes of signal peptides or if it has specific targets and generates essential products through its action.. Human SPP is an intramembrane aspartyl protease whose active site is predicted to be buried within the lipid bilayer. It belongs to a family of enzymes conserved among animals, plants, and fungi (Ponting et al. 2002; Weihofen et al. 2002). The Drosophila and human SPPs have strong sequence similarity, with the ...
Background The Protease-Activated Receptor 1 (PAR1) is activated by the proteolytic release of the N-terminal 41 amino acids. Exogenously administered PAR1(1- 41) peptides protect against myocardial ischemia and reperfusion injury in the rat. In the present study, we determined whether PAR1(1-26), the putative signal peptide of PAR1 contains the functional domain of PAR1(1- 41).. Methods and Results We assessed the protective role of a synthesized PAR1(1-26) peptide in an in vivo rat model of myocardial regional ischemia and reperfusion injury (n=6/group). PAR1(1-26) (0.01-10 μg/kg) treatment immediately before ischemia reduced infarct size from 58±1% to 13±1% area at risk (p,0.01) at an optimal dose of 10 μg/kg. Treatment with PAR1(1-26) after the onset of reperfusion decreased infarct size to 22±1% area at risk (p,0.01). We then explored the survival pathways known to be up-regulated by pharmacologic cardioprotectants. Inhibition of Gi proteins (pertussis toxin), PI3K/Akt (Wortmannin), ...
Salt-alkaline stress generally leads to soil compaction and fertility decline. It also restricts rice growth and phosphorus acquisition. In this pot experiment, two relatively salt-alkaline tolerant (Dongdao-4 and Changbai-9) and sensitive (Changbai-25 and Tongyu-315) rice genotypes were planted in sandy (control) and salt-alkaline soil to evaluate the characteristics of dry matter and phosphorus assimilation and translocation in rice. The results showed that dry matter and phosphorus assimilation in rice greatly decreased under salt-alkaline stress as the plants grew. The translocation and contribution of dry matter and phosphorus to the grains also increased markedly; different performances were observed between genotypes under salt-alkaline stress. D4 and C9 showed higher dry matter translocation, translocation efficiency and contribution of dry matter assimilation to panicles than those of C25 and T315. These changes in D4 and C9 indexes occurred at low levels of salt-alkaline treatment. Higher
Fig. 2. Assignment of proteolytic fragments from LCMS fraction 77 (77-78 min).A, MALDI-TOF spectrum of CNBr fragments. To accommodate the mass range of interest the spectrum was collected in the linear mode; thus the 13C isotopes of the peptide are not resolved, and average instead of monoisotopic masses were recorded. Identified peaks are labeled with letters, and unassigned peaks are labeled with their respective mass. The sample was spiked with an insulin standard for internal calibration. Underlined peak labels indicate carboxyl-terminal peptides, and boxed labels indicate amino-terminal peptides. The identified peaks are as follows: Peak A (measured mass (meas. mass) = 3885.8 Da, calculated mass (calc. mass) = 3885.4 Da, assignment (assgn.) = Lhca2III peptide 222-257 (peptides numbered from Meti)), Peak B (meas. mass = 3946.5 Da, calc. mass = 3945.4 Da, assgn. = Peak L2+), Peak C (meas. mass = 4161.7 Da, calc. mass = 4158.7 Da, assgn. = Lhcb4V peptide 251-290), Peak D (meas. mass = 4186.1 ...
Peptide drugs have been difficult to translate into effective therapies due to their low in vivo stability. Here, we report a strategy to develop peptide-based therapeutic nanoparticles by screening a peptide library differing by single-site amino acid mutations of lysine-modified cholesterol. Certain choles
Chimeras of pediocin PA-1 (PedA-1), a bacteriocin produced by Pediococcus acidilactici PLBH9, fused to the signal peptide of enterocin P (EntP), a sec-dependent bacteriocin produced by Enterococcus faecium P13, permitted the production of PedA-1 in Lactococcus lactis. Chimeric genes encoding the EntP signal peptide (SP(entP)) fused to mature PedA-1 (pedA), with or without its immunity gene (pedB), were cloned into the expression vector pMG36c to generate the recombinant plasmids pMPP9 (SP(entP):pedA) and pMPP14i (SP(entP):pedA + pedB). Transformation of competent L. lactis subsp. lactis IL1403, L. lactis subsp. cremoris NZ9000, and L. lactis subsp. lactis DPC5598 with the recombinant plasmids has permitted the detection and quantitation of PedA-1 and the coproduction of nisin A and PedA-1 in supernatants of producer cells with specific anti-PedA-1 antibodies and a noncompetitive indirect enzyme-linked immunosorbent assay. Recombinant L. lactis hosts carrying pMPP9 or pMPP14i displayed ...


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Sorry, but the currently accepted answer is not precise enough. In the situation you discussed, there is no applied force acting on the object, but there is still the normal force $N$, which prevents the object from "falling through" the surface due to gravity. The most common model of kinetic friction is $F_k = \mu N$, where $\mu$ is the coefficient of ...

1

Friction comes into play whenever there is relative motion between the surfaces in contact or a tendency of motion between the same.There need not necessarily be an externally applied force on either of the bodies,that is,there need not necessarily be a relative acceleration initially,merely relative motion or a tendency for the same. It is the frictional ...

1

When neglecting air drag, the vertical and horizontal motions decouple and we have the equations \begin{align} \ddot{x} &= 0,\\ \ddot{y} &=-g. \end{align} The initial conditions (at $t=0$) are $x=x_0$, $y=y_0$, $\dot{x}=v_0\cos\alpha$, and $\dot{y}=v_0\sin\alpha$ with $v_0$ the initial speed and $\alpha$ the angle of projection. This gives the ...

2

$|\frac{d\vec{v}}{dt}|$ = magnitude of rate of change of $\vec{v}$ = |$\vec{a}$| while $\frac{d|\vec{v}|}{dt}$= rate of change of |$\vec{v}$| = rate of change of speed. If you consider any situation where speed of object is not changing and object is not moving in straight line , i.e. , moving in any curved path , both these conditions will be true. This ...

0

You may assume the origin to be at the the starting point of train A. Then find the time after which the two trains meet. Finally you can find the displacement of train A using the equation of motion $$S= vt + \frac{1}{2}at^2$$.

0

What is $a(t)$? It is the instantaneous time rate "change" of velocity & not velocity at time $t$! What it does tell you is how fast the velocity changes in an infinitesimal time period centered at $t$ i.e. $t \underset{-}+ dt$. You can write $\dot{v}(t) = \dfrac{dv}{dt} = a(t)$. Then you want to find what change has occured to the velocity after ...

0

Active motion sensors emit any one of three types of energy: (1) Infrared light, (2) microwaves, (3) sound waves. If your motion detector does not emit any energy but infrared, and if it has no passive capabilities, it will not be activated by sound waves. Are you certain that your motion detector employs only active infrared technology? Some motion ...

1

A particle moving along a curved path has its motion decomposed as $$\vec{v} = v \hat{e} \\ \vec{a} = \dot{v} \hat{e} + \frac{v^2}{\rho} \hat{n}$$ where $\hat{e}$ is the unit tangent vector, and $\hat{n}$ the unit normal vector pointing towards the inside of the curve. $v$ is the scalar speed and $\rho$ is the radius of curvature at that moment. 1) You ...

0

$\newcommand{\dv}[2]{\frac{\mathrm{d} #1}{\mathrm{d}#2}}$Velocity is the derivative of $s$ with respect to time $$v = \dv{s}t$$ Take the integral of both sides Integral is the area under the curve $$\int v(t) \text d t = s$$ Acceleration is the derivative of velocity with respect to time $$a = \dv v t$$ Take the integral of both sides So the ...

1

There are 4 standard kinematic equations from Newtonian mechanics, and you need what is usually considered to be the fourth equation. $\mathrm{(final\ velocity)^2 = (initial\ velocity)^2 + 2 \times acceleration \times distance}$ You know the initial velocity, final velocity, and distance. Solve for acceleration.

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part i) answer is just $\int \int \frac{d^3p_1}{2E_1}\frac{d^3p_2}{2E_2} = \int\int \frac{E_1 dE_1 dcos(\theta_1) d\phi_1}{2}\frac{E_2 dE_2 dcos(\theta_2) d\phi_2}{2}$. Given that we have in our integrand a piece that only depends on relative angle between $\vec{p_1}$ and $\vec{p_2}$, if we orient our axes in the direction of $\vec{p_1}$ and integrate ...

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I think an easier way would be to do $$\frac{u \left(\sin(53^\circ) - \sin(33.7^\circ)\right)}{2g}$$

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Use the trigonometric table for finding the values ( if you want an easy way out) or try doing a bit of adjustments here or there to suit your needs.

3

Some dimensions I was able to dig up (mostly from Wikipedia). Draft of the Allure of the Seas: 31 ft (10 m) Length: 1181 ft (360 m) Beam at waterline: 47 m Height: 72 m above waterline Let's just draw the section based on these simple numbers: Now if the center of gravity were in the middle of the ship (31 m above the water line), it would indeed not be ...

0

You have $x$ and $y$ (the displacements along those axes) represented as functions of some variable. Velocity is defined the instantaneous rate of change of the displacement, with respect to time. (i.e. its time derivative) The velocity in the $x$ and $y$ directions therefore, would be $\frac{dx}{dt}$ and $\frac{dy}{dt}$ respectively. (Because projection ...

2

I doubt it is all fluid dynamics. The have to stay upright even with dead engines. If the integral of the lever below the water line is bigger than above then it should stay upright. Ballast at the bottom goes a long way as it has a long lever. Stuff like engines below deck tends to be heavy anyway. Weight is not a big deal as they are not going up ...

0

Isn't a physical frame of reference useless for calculating speed? There aren't really any physical frames of reference. You can't step outside and point up to the clear night sky and say "Look, there's a reference frame". You can point to the Moon and the stars, but they are what they are. You can use them in your reference frame, but that reference ...

0

Velocity and speed of a body are measured with respect to another body (see other answer). This is the only possible definition. The "actual" speed respect to the "empty space" is not well defined instead. And this is because we are not moving inside an "empty space" or an "aether" which fills the universe. To grasp the concept think about how you will ...

2

When physicists use the word velocity it has a precise definition that is meaningful and unambiguous. If I measure the displacement from me to you then the result is a vector i.e. it tells me how far apart we are and in what direction you are. The velocity tells me how this vector is changing in time. The point is that I can do this for any pair of objects: ...

1

I find that sometimes intuition works better with more extreme examples. Let's change the problem up a bit. Instead of some itty-bitty difference in acceleration (a vs 2a), lets choose a big acceleration for a short period of time. In this modified example, both A and B are going to be fired out of a cannon. The firing is going to take just 0.1s, but ...

0

I'm assuming you used the following kinematic equation in your solution: $$d = x_0 + v_{0}t + \frac{1}{2}a_{0}t^{2}$$ Remember that after the initial acceleration, the particles will have covered some distance and gained some velocity. Hence, in the second step where you have a new acceleration, you no longer have a zero initial position and velocity. I got ...

14

Let's draw a graph of velocity against time for the two particles $A$ and $B$. For convenience I've made the total time $2t$: The red line shows the velocity for particle $A$ while the green line shows the velocity for particle $B$. When we draw a velocity:time graph the distance travelled is the area under the line. More precisely it is the integral of ...

0

I think your answer is incorrect. First the intuitive argument: Assume you had stopped both particles after half of the time. It is obvious that in this case they had covered the same distance. At first B is first, but in the second half A would catch up. If you don't stop the particles before they continue with a different acceleration also the velocity ...

0

The same reasoning that goes for racing cars: Acceleration is important if you are slow, because then the relative change in velocity over time will be high edit: (also the velocity is the accumulated acceleration, meaning that the earlier you have high accelaration the better because you will "keep" that to the end)

2

There are 3 ways for a molecule to store energy, excluding electronic energy. Those three ways are translation (the molecule just moving), rotation, and vibration. All molecules can translate in each of the three Cartesian planes. You can also imagine that a non-linear molecule, could rotate in all the planes (xy plane, xz plane, yz plane). A linear molecule ...

0

With given vectors for acceleration and velocity, is there a way to determine if a body accelerates or decelerates at a certain time-interval? Given the velocity vectors of a (specific) body (with respect to specific members of a suitable reference system) throughout a trial, in particular the velocity vectors $\mathbf v_{\text{initial}}$ at the ...

0

Assuming you are asking undergraduate mechanics book. I found the one used by Caltech is unbelievably awesome. The Mechanical Universe: Mechanics and Heat, Advanced Edition by Steven C. Frautschi, Richard P. Olenick, Tom M. Apostol, David L. Goodstein (pick the advanced edition intead of introduction edition) The good parts of this book: It teaches ...

3

I am not too certain of what you are asking. If you are asking why do we not look at a molecule and then just identify the number of independent modes of vibration the answer is that it would be too hard. Real oscillations are a linear superposition of these normal modes, even undergrad spectra are often complicated. Only very simple diatomic give nice Raman ...

0

You asked two simple questions - I will give two simple answers. I don't know if I can use uniform circular motion equation since v is not constant At the very instant that the curve starts, the velocity is given by $\sqrt{2gh}$ - and for that first instance it is constant. So yes, you can use uniform circular motion Where is the g-force directed ...

0

Let's say Bob is standing still while a one light second long photon formation flies past him. How long does the passing of the photon formation and Bob take according to us? Answer: It takes one second. 1 light seconds / c = 1 seconds. Let's say Jim is moving forwards at speed 0.1 while a one light second long photon formation moving to the opposite ...

0

I don't know if I can use uniform circular motion equation since v is not constant The equation for centripetal force is independent of whether the motion is uniformly circular or not. However, irrespective of the radius of the track, the velocity at that point, and the weight of the roller-coaster, or whether the equation for centripetal force is ...

1

What happens if you first drive on a road at speed 0.99 c, and then accelerate to speed 0.999 c? You will pass milestones at much faster rate. That happens mostly because of length contraction, not because of larger speed, as the speed increase was only 0.009 c. Roughly the same contraction as above will happen to a line of photons approaching you, if you ...

0

You're good. Yeah, you can pretty much assume that it's a constant velocity, as long as $h \gg r.$ As I recall, the expressions involved are extremely simple as long as you don't try to figure out exactly what's happening in time: actually solving the Euler-Lagrange equations gives you some sort of $\int d\theta / \sqrt{a + b \sin\theta} = t$ equation for ...

2

There are two accelerations involved: The gravitational acceleration $g$ that points down, and the centripetal acceleration $a_r = \frac{v^2}{r}$ that points along the radius vector of the curve. The component of the gravitational acceleration that is tangential to the curve does not contribute to the g-force as it accelerates the cart and us in this ...

1

This is one of those questions that can drive you crazy, since there is a great deal assumed and not stated. Let me try an alternate possibility. Conceivably, the problem wants you to assume that, when moving, the overall speed of the raindrop remains fixed at 5 m/sec, but it travels in a straight line at an angle due to horizontal wind forces, and this may ...

2

If the raindrop's vertical velocity is constant as the train is both stationary and moving, the time taken for the raindrop to travel down the window would be: $$t = \frac{1\ \text{m}}{5\ \text{m}/\text{s}} = 0.2\ \text{s}$$ Remember, the time $t$ would not depend on the speed of the train. The exercise also specifically states that the raindrop's vertical ...

0

Another way of looking at this: The vertical component of the raindrop's velocity vector is 5 m/sec downward, and the horizontal component is 30 m/sec across. By the Pythagorean method, the resultant velocity vector is 30.41 m/sec diagonal. The vertical component of the raindrop's displacement vector is 1 meter, and as the raindrop is pushed horizontally ...

11

You are right in that the speed of light doesn't change. It is a completely different effect to the rain drop analogy. If you had only light hitting you directly from the front and directly form the back, you would observe the same intensity in the moving frame (only blue/red shifted). But for light coming at you from an angle $\theta_s$ in the rest frame, ...

0

This time, you got the right answer using your intuitive reasoning because all the velocities are equal in magnitude. However, you will not be so lucky most of the time, in more complicated situations. Yes, definitely, concepts can be used here. Consider the four directions(north,south,east,west) as the ends of two dimensional co-ordinate axes: Now, I ...

2

SECTION A : Free fall of roller coaster into circular motion (kinetics) Suppose that the roller coaster, called from now on "particle", is at rest at point A ($\:\upsilon_{A}=0\:$) and starts free falling till point B where it starts its circular motion. Well-known is that at B the speed is $\:\upsilon_{B}=\sqrt{2gh}\:$ under the assumption of no energy ...

2

The roller coaster falls a height $h$ before entering the loop (the path of the RC will look like a J. The straight bit of the J is of length $h$), and I assume it started with zero velocity. Within the loop it's total kinetic energy will equal the total potential energy lost, which is $$E_\text{kin}=mg(h+r\sin\theta).$$ Here $\theta$ is defined such that ...

1

$v$ isn't referring to either $v_1$ or $v_2$, necessarily; $v_1$ is representing the vector before it moves, and $v_2$ is the vector after this movement. If we are working in polar coordinates (the reason he is using $v_\perp$ and $v_\parallel$), then let's suppose this small movement isn't changing the magnitude of the vector, it is just changing the ...

0

Inertia is what we simply called 'quantity of material'. The word material has been used here to specify the matter of body. For example, a plastic chair, a wood chair and an iron chair. Among them, a plastic chair will have less inertia because it will apply less reaction force, so it is easy to lift it. And the word quantitative is used to define the ...

2

Define the origin of your coordinate system at the top of the hill with the vehicle travelling in the $+x$ direction with initial velocity $v$ and initial position $s=(0,0)$. The road then "falls away" from the vehicle at a rate of $v \tan(\theta)$, so the altitude $h$ of the vehicle above the downward sloping road can then be written as a function of time ...

-1

It just oblique projectile motion U= speed of truck h= height of hill If you want to calculate how far from hill the truck land after flight use U multiply by the whole root of 2H/g g is gravitational acceleration =10m/s2

2

First I will make a few assumptions: the hill is flat at the its top (so its surface is perpendicular to gravity); the side of the hill is flat and makes an angle $\theta$ relative to the top; the end of the hill is sufficiently far away such that it will never be reached during the "jump" sideways of the top of the hill; the tradition from the top to the ...

3

The car becomes "weightless" when the curvature of the road is sufficient that the car does not stay connected to the road. Angles don't really matter - what matters is a change in the direction of the road. As you know, an object going around in a circle needs a force $F = \frac{mv^2}{r}$ to stay in the orbit at radius $r$. Normally, when you drive over a ...

1

For a right angle triangle you can use SOH CAH TOA to find the relations between the angles and the lengths of the sides. If you want to find the relation between the horizontal and vertical components of the velocity you need to use the tangens and $\tan(45^\circ)=1$, thus the ratio between the horizontal and vertical components of the velocity is one.

0

Is this true for all horizontally-thrown, free falling objects then i.e. that at the 45 degree point the x and y components are equal?! It's true for all vectors, whether they represent velocity, position, acceleration, or whatever. If a vector has a direction at 45 degrees to the x-axis, then the x and y components of the vector will have equal ...

1

The introductory quote defines $\tau$ and $\nu$ to be unit vectors. That means that their magnitude is 1. $\mathbb{i}$ and $\mathbb{j}$ are unit vectors along $x$ and $y$ axes. That's a standard notation. Some of the comments are stressing the fact that the basic understanding of vectors is missing. I have a feeling that you've jumped into a 'complicated' ...

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# Question about multipole expansion of electrostatic potential?

If I take a certain dipole and by dipole I mean that two charges of opposite sign differentiated by very small distance. And if I take the formula of multipole expansion of potential then I see no other term except the dipole moment exists because everything except the dipole becomes zero. Now if I have a sphere whose charge density is not quite uniform (ie $$\rho(r,\theta)= krcos\theta$$, where $$r$$ and $$\theta$$ are spherical polar coordinates) but I know that it's two sides have same but opposite amount of charges then should I treat it as a dipole and by the expansion only the survives or do I have to make precise calculations as the result is unpredictable?

• What do you mean by “I see movement”? And can you please break your second very long sentence down into multiple sentences that are easier to understand? – G. Smith Mar 23 at 21:35
• @G.Smith i am sorry I was voice typing that came out wrong so I edited it. – Nobody recognizeable Mar 23 at 21:37
• @G.Smith is it ok now? – Nobody recognizeable Mar 23 at 21:41
• No charge distribution can truly have only a dipole moment term in its multipole expansion--the higher moment terms might get as small as you want but one cannot have a charge distribution with only a dipole moment term. – Feynmans Out for Grumpy Cat Mar 23 at 22:01
• @DvijMankad are you sure an exact dipole has higher order terms. Can you give reference to me as i know to compute till quadrupole moment. – Nobody recognizeable Mar 23 at 22:06

This distribution has no net charge, but it has a dipole moment, a quadrupole moment, an octupole moment, etc. If you are approximating the potential, you can keep as few or as many of these as you need for the accuracy you desire. If you want an exact result, don’t use the multipole expansion.

The result is not “unpredictable”. The dipole term will decrease as $$1/r^2$$, the quadrupole as $$1/r^3$$, etc. Far away, the terms get smaller and smaller. But close in, they are all important.

If you take oppositely charged point particles and bring them together while letting the product of the charge and the separation stay constant, you get a pure dipole with no other moments. But your spherical distribution is not a pure dipole. It is dipole + higher moments.

• If we have a dipole then quadrupole and monopole moments have zero values ; dipole moment exists but does that say octupole moment and so on all are zero? – Nobody recognizeable Mar 23 at 21:49
• If you take oppositely charged point particles and bring them together while letting the product of the charge and the separation stay constant, you get a pure dipole with no other moments. But your spherical distribution is not a pure dipole. It is dipole + higher moments. – G. Smith Mar 23 at 21:53
• great ! You should add that in the answer – Nobody recognizeable Mar 23 at 21:54
• You asked, you got. Perhaps you would consider marking the answer as accepted? – G. Smith Mar 23 at 21:55
• thanks for all the help. – Nobody recognizeable Mar 23 at 21:58


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# Learn the Relativistic Work-Kinetic Energy Theorem

I was bothered for a long time by the reasons for the relativistic validity of the work-kinetic energy relation ##\Delta E=Fd##, which holds without any need for corrections. We’ve discussed this before here on PF,  but I think at this point I understand it better, so I thought I’d post a summary of my present understanding.

## Einstein’s treatment

At one time I somehow got the idea that Einstein had never given any logical justification for the fact that ##\Delta E=Fd## was valid and exact relativistically. I think this was because I hadn’t carefully thought through section 10 of “On the electrodynamics…,” where he actually gives a rigorous treatment. He starts with two assumptions:

(1) We have ##ma=eE## for the motion of an electron in any instantaneously comoving frame, in an electric field E. (He explicitly uses two such frames.). There’s no way this can be subject to a correction factor such as ##\gamma##, since the electron is at rest.

(2) The electrical potential energy of an electron is given by ##eV##. This is firmly established by experiment, and it doesn’t involve motion, so there is no reasonable way that we could imagine that it would need a correction factor like ##\gamma##. In the example of a small spherical shell of charge between two capacitor plates, it’s derivable from the equation for the energy density of the field

He’s also worked out the transformations of the fields (E,B) and the coordinates, so starting from assumption 1 he’s able to find the dynamical laws in a frame where the electron is moving. He uses these dynamical laws, along with assumption 2, to find the kinetic energy of the electron at relativistic speeds.

Along the way, he also does the following. His dynamical laws give, in the parallel direction, ##eE=m\gamma^3a##, and he calls this the force (in the parallel direction), which is equivalent to the common modern definition of the three-force as ##dp/dt##. Because of assumption 2, it follows that ##\Delta E=Fd## holds exactly; he is *not* assuming ##\Delta E=Fd##, he’s proving it (for this definition of force).

## Using the relativistic energy-momentum four-vector

A more modern approach is as follows. Suppose that we’ve already determined the properties of the energy-momentum four-vector. This includes the relativistic definition of mass, ##m^2=E^2-p^2##, and also the identity ##p/E=v##. Then is becomes pretty straightforward to show that ##W=Fd## is relativistically exact. Consider one-dimensional motion, and let ##p## be the momentum component along our one spatial dimension. Define ##F=dp/dt##. Then

## \frac{d E}{d x} = \frac{d E}{dp}\frac{d p}{d t} \frac{d t}{d x} = \frac{d E}{d p} \frac{F}{v} ##

By implicit differentiation of the definition of mass, we find that ##dE/dp=p/E##, and this in turn equals ##v## by the identity above. This leads to the claimed result, which is valid for both massless and material particles.

## Using simple machines

I always felt that there should be some way of getting at the problem this way, but I don’t think it ends up working. Suppose we have a simple machine with mechanical advantage ##A##. At least some simple machines (such as a lever) are capable of operating rigidly (based on the definition of Born-rigidity) for arbitrary relativistic motion. (Many others are not, because rigid motion would violate the Herglotz-Noether theorem. For example, a screw undergoing accelerated motion through a set of threads at relativistic speeds would bind.) For a machine that does work relativistically, the ratio of the input and output displacements is fixed to the exact value ##1/A##, without relativistic correction.

The proportionality of work to ##F## and to ##d## follows from elementary considerations, independent of relativity. See the Feynman lectures, section I-4-2.

What seems more problematic in these arguments is the following. Suppose we have two things that could be called “force,” ##F## and ##G##, and let them differ by ##G=F h(v)##, where ##h## is some function and ##v## is the velocity of an object being acted upon. These could be, e.g., ##F=dp/dt## and ##G=dp/d\tau## (the spacelike component of the force four-vector). In this example, it turns out that the forces at the input and output of the machine are related by ##F_1/F_2=A##, while ##G_1/G_2\ne A##, but how do you show this? I don’t think you can show it without some other argument, as in the two sections above.

Tags:
20 replies
1. bcrowell says:

[USER=260864]@vanhees71[/USER]: Again, this is not at all on topic for this thread.

2. vanhees71 says:

Sure, ray optics is all you need for this purpose. For things like the redshift-distance relation in cosmology you need its proper definition via the eikonal approximation of the Maxwell equations in a given background spacetime (here the FLRW pseudometric), usually for spherical waves.

It’s also historically interesting that in the 1930ies there was a debate about the correct interpretation of the Hubble redshift, where distinguished physicists like von Laue were involved. There they also had the debate, whether the already then favored derivation in the naive photon picture is correct. Finally Robertson showed, how to derive the relation within classical electromagnetics. It’s downloadable from NASA (I think not behind a paywall):

Robertson, H. The apparent luminosity of a receding nebula Zeitschrift für Astrophysik 15, 1938, 69

Concerning massless particles I’ll think about simple examples for motion of massless particles in a static electric or magnetic field. If trouble occurs, which I don’t expect, I’ll open a posting. Otherwise it will immediately go in my SRT writeup :-).

3. bcrowell says:

[QUOTE=”vanhees71, post: 5211935, member: 260864″]Ok, so that’s well understood by classical electromagnetism. No naive-photon picture is needed.[/QUOTE]

I would put it the other way around. Ray optics is all you need for the application I mentioned, so there is no need for classical electromagnetism or quantum mechanics. Ray optics is not a “naive-photon picture.” In any case, I think this is of little or no relevance to the topic of this thread. If you want to start a separate thread on the status of massless particles in classical relativity, that might be more appropriate IMO.

4. vanhees71 says:

Ok, so that’s well understood by classical electromagnetism. No naive-photon picture is needed. What’s usually done is just the eikonal approximation to classical electromagnetism (i.e., ray optics derived from wave optics). Photons in a curved background spacetime are a quite tricky business!

5. bcrowell says:

[QUOTE=”vanhees71, post: 5211167, member: 260864″]In which sense has gravitational lensing to do with the motion of massless particles? Well, you might interpret ray optics (i.e., the eikonal approximation for classical electromagnetic waves) as massless-particle motion.[/QUOTE]

Yes.

6. vanhees71 says:

In which sense has gravitational lensing to do with the motion of massless particles? Well, you might interpret ray optics (i.e., the eikonal approximation for classical electromagnetic waves) as massless-particle motion. In this sense the naive photon picture is not completely wrong…

7. bcrowell says:

[QUOTE=”vanhees71, post: 5211097, member: 260864″]Can you give an example where one does this? Anyway, there’s of course nothing wrong with it from a theoretical point of view. You can have perfectly valid equations of motion for massless particles.[/QUOTE]

Gravitational lensing would be a good example.

8. vanhees71 says:

Can you give an example where one does this? Anyway, there’s of course nothing wrong with it from a theoretical point of view. You can have perfectly valid equations of motion for massless particles.

9. bcrowell says:

I don’t think #12 is the same as saying that massless particles don’t “make sense” classically. In any case, we deal with massless particles constantly in classical relativity, and we do it in practical contexts that relate directly to observation.

10. vanhees71 says:

Very simple: There are no classical massless particles, at least I’ve never heard that one has observed them yet. This makes much sense from the point of view of quantum field theory. The only candidate that comes to mind within the standard model would be a photon, but this is the quantum (one-particle Fock state) of the electromagnetic field, which is a massless spin-1 field and thus necessarily a gauge field, and you cannot define a position observable in the strict sense. So it is hard to imagine, how to get a classical particle limit. The classical limit is that of classical electromagnetic fields, i.e., coherent states with a large average photon number rather than classical point particles.

The other massless fields in the Standard Model are the gluon fields, but the corresponding quanta, the gluons, are confined, so one cannot expect to find them as particles in the sense of a classical limit.

The very last possibility would be that one of the neutrinos is in fact massless. It’s hard to say at the present empirical status. If it would exist, it may be a candidate for something that could make sense as a classical approximation in the sense of a massless particle.

11. bcrowell says:

[QUOTE=”vanhees71, post: 5210133, member: 260864″]”massless particles” (which don’t make too much sense in classical (i.e., non-quantum) relativistic physics anyway)[/QUOTE]

Why?

12. vanhees71 says:

Inspired by this thread and bcrowells remark in #8 on “massless particles” (which don’t make too much sense in classical (i.e., non-quantum) relativistic physics anyway), I’ve extended the section on “naive dynamics” (i.e., dynamics not employing Hamilton’s principle of least action) in my SRT writeup by giving a derivation of the work-energy theorem and also a formulation of the dynamics of massless particles:

[URL]http://fias.uni-frankfurt.de/~hees/pf-faq/srt.pdf[/URL]

13. bcrowell says:

[QUOTE=”Jano L., post: 5207538, member: 193673″]I do not know what Einstein was getting at there. I am not sure proving the relation ##E=gamma mc^2## makes sense. I think this is just a definition of energy, same as ##frac{1}{2}mv^2## is definition of kinetic energy in classical mechanics.[/QUOTE]

Definitions are like babies. They have to come from somewhere. Einstein is proving that this equation is the only one for a massive particle that is consistent with Maxwell’s equations. In any case, this is not a definition of energy, since it doesn’t apply to massless particles.

14. bcrowell says:

[QUOTE=”pervect, post: 5207389, member: 14402″]I’m not too sure my thoughts will be helpful for the intended purpose (which I assume ultimately involves a simple presentation of special relativity), but perhaps they’ll provide some insight. And they can be expressed pretty briefly. As long as special relativity has a non-trivial Hamiltonian, we can write Hamilton’s equations:

$$frac{partial H}{partial q} = dot {p}$$

Now, if we can also identify H with energy, q with position, and ##dot{p}## with force, then we have the work-energy theorem, the rate of change of the energy with position must be equal to the force.[/QUOTE]

This is an interesting approach, but if we examine it carefully I think it’s not quite as much of a slam-dunk as it might seem. And it does have the disadvantage that it won’t work as a presentation at the undergraduate level, since a physics major might not be exposed to Hamiltonian mechanics until after taking their upper-division SR course.

Spelling out the steps in more detail, I think we would have the following:

(1) The action has to be Lorentz-invariant and additive, and the only possibility that seems to present itself is ##S=(ldots)mint_{t_1}^{t_2} dtau##, where … represents a constant.

(2) Working backward from this, infer that the Lagrangian for a free relativistic particle in one dimension is ##L=(ldots)m/gamma##.

(3) Find the conjugate momentum, which is ##p=(ldots)mgamma v##.

(4) Interpret ##dp/dt## as a force.

(5) Calculate the Hamiltonian.

(6) Identify the Hamiltonian with the energy.

(7) Use Hamilton’s equations to associate ##partial H/partial x## with minus the force.

The first thing to note is that this is much, much longer than the simple derivation I gave (the second of the three sections in my original post).

The next problem is that we have foundational issues in steps 1 and 4. Maybe there’s an explicit uniqueness theorem one could give at step 1? Otherwise it’s just a plausibility argument, with no a priori guarantee, for example, that the final result will come out consistent with Maxwell’s equations in the case of a charge moving in a field. In step 4, we have to decide what is the best definition of force. One could argue that this definition is good, because by the time we get to step 7 we will have shown that it preserves the form of the work-energy theorem without correction. But this is a weak justification if we aren’t at step 7 yet, and in fact we have a different definition of force, the four-force, which a priori would be preferable because it’s tensorial.

At step 6, we have to check some technical criteria.

A general philosophical objection to the whole thing is that Hamiltonian mechanics lacks manifest Lorentz invariance at every step of the way. In particular, time is treated as a parameter rather than a coordinate.

15. Jano L. says:

[QUOTE=”bcrowell, post: 5207518, member: 211768″]
There are two disadvantages to your method. (1) In the 1905 paper, Einstein uses ##Delta E=Fd## to prove ##E=mgamma c^2##, so he can’t use the latter to prove the former. (2) Your method doesn’t work for massless particles.[/QUOTE]

I do not know what Einstein was getting at there. I am not sure proving the relation ##E=gamma mc^2## makes sense. I think this is just a definition of energy, same as ##frac{1}{2}mv^2## is definition of kinetic energy in classical mechanics.

16. bcrowell says:

[QUOTE=”Jano L., post: 5207326, member: 193673″]I see the ## way of writing formulae does not work well, so here’s my comment in plaintext:
I have trouble seeing what is the problem you’re trying to solve. The relation W=Fd is definition of work, not the work-energy theorem.[/QUOTE]

Right, I should have notated this as ##Delta E=Fd##.

[QUOTE=”Jano L., post: 5207326, member: 193673″] The work-energy theorem says work equals change in kinetic energy of the particle. This follows mathematically from the equation of motion md(γv)/dt=F and Einstein’s definition of energy E=γmc^2.[/QUOTE]

There are two disadvantages to your method. (1) In the 1905 paper, Einstein uses ##Delta E=Fd## to prove ##E=mgamma c^2##, so he can’t use the latter to prove the former. (2) Your method doesn’t work for massless particles.

17. pervect says:

I’m not too sure my thoughts will be helpful for the intended purpose (which I assume ultimately involves a simple presentation of special relativity), but perhaps they’ll provide some insight. And they can be expressed pretty briefly. As long as special relativity has a non-trivial Hamiltonian, we can write Hamilton’s equations:

$$frac{partial H}{partial q} = dot {p}$$

Now, if we can also identify H with energy, q with position, and ##dot{p}## with force, then we have the work-energy theorem, the rate of change of the energy with position must be equal to the force.

18. Jano L. says:

I see the ## way of writing formulae does not work well, so here's my comment in plaintext:I have trouble seeing what is the problem you're trying to solve. The relation W=Fd is definition of work, not the work-energy theorem. The work-energy theorem says work equals change in kinetic energy of the particle. This follows mathematically from the equation of motion md(γv)/dt=F and Einstein's definition of energy E=γmc^2.

19. Jano L. says:

I have trouble seeing what is the problem you're trying to solve. The relation ##W=Fd## is definition of work, not the work-energy theorem. The work-energy theorem says work equals change in kinetic energy of the particle. This follows mathematically from the equation of motion ##md(\gamma v)/dt = F## and Einstein's definition of energy ##E=\gamma mc^2##.


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November  2009, 8(6): 1957-1974. doi: 10.3934/cpaa.2009.8.1957

## Multiple solutions for nonlinear coercive Neumann problems

 1 Department of Mathematics, Hellenic Naval Academy, Piraeus 18539, Greece 2 Department of Mathematics, National Technical University, Zografou Campus, Athens 15780

Received  June 2008 Revised  February 2009 Published  August 2009

In this paper we deal with a nonlinear Neumann problem driven by the $p$--Laplacian and with a potential function which asymptotically at infinity is $p$--linear. Using variational methods based on critical point theory coupled with suitable truncation techniques, we prove a theorem establishing the existence of at least three nontrivial smooth solutions for the Neumann problem. For the semilinear case (i.e., $p=2$) using Morse theory, we produce one more nontrivial smooth solution.
Citation: Sophia Th. Kyritsi, Nikolaos S. Papageorgiou. Multiple solutions for nonlinear coercive Neumann problems. Communications on Pure & Applied Analysis, 2009, 8 (6) : 1957-1974. doi: 10.3934/cpaa.2009.8.1957
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