Kjeldsen, Frank; Hørning, Ole B; Jensen, Søren S;
2008-01-01
in large-scale peptide characterization strategies. We successfully increased the EDD fragmentation efficiency (up to 9%), and demonstrate for the first time the utility of EDD-MS/MS in liquid chromatography time-scale experiments. Peptides and phosphopeptides were analyzed in both positive- and negative...
Optimization of reversed-phase chromatography methods for peptide analytics.
Khalaf, Rushd; Baur, Daniel; Pfister, David
2015-12-18
The analytical description and quantification of peptide solutions is an essential part in the quality control of peptide production processes and in peptide mapping techniques. Traditionally, an important tool is analytical reversed phase liquid chromatography. In this work, we develop a model-based tool to find optimal analytical conditions in a clear, efficient and robust manner. The model, based on the Van't Hoff equation, the linear solvent strength correlation, and an analytical solution of the mass balance on a chromatographic column describing peptide retention in gradient conditions is used to optimize the analytical scale separation between components in a peptide mixture. The proposed tool is then applied in the design of analytical reversed phase liquid chromatography methods of five different peptide mixtures. PMID:26620597
Affinity Purification of Insulin by Peptide-Ligand Affinity Chromatography
无
2007-01-01
The affinity heptapeptide (HWWWPAS) for insulin, selected from phage display library,was coupled to EAH Sepharose 4B gel and packed to a 1-mL column. The column was used for the affinity purification of insulin from protein mixture and commercial insulin preparation. It was observed that the minor impurity in the commercial insulin was removed by the affinity chromatography. Nearly 40 mg of insulin could be purified with the 1-mL affinity column. The results revealed the high specificity and capacity of the affinity column for insulin purification. Moreover, based on the analysis of the amino acids in the peptide sequence, shorter peptides were designed and synthesized for insulin chromatography. As a result, HWWPS was found to be a good alternative to HWWWPAS, while the other two peptides with three or four amino acids showed weak affinity for insulin. The results indicated that the peptide sequence of HWWWPAS was quite conservative for specific binding of insulin.
Stereo-separations of Peptides by Capillary Electrophoresis and Chromatography
sprotocols
2014-01-01
Authors: Afzal Hussain, Iqbal Hussain, Mohamed F. Al-Ajmi & Imran Ali ### Abstract Small peptides (di-, tri-, tetra- penta- hexa etc. and peptides) control many chemical and biological processes. The biological importance of stereomers of peptides is of great value. The stereo-separations of peptides are gaining importance in biological and medicinal sciences and pharmaceutical industries. There is a great need of experimental protocols of stereo-separations of peptides. The vario...
Occupational Cohort Time Scales
Deubner, David C.; Roth, H. Daniel
2015-01-01
Purpose: This study explores how highly correlated time variables (occupational cohort time scales) contribute to confounding and ambiguity of interpretation. Methods: Occupational cohort time scales were identified and organized through simple equations of three time scales (relational triads) and the connections between these triads (time scale web). The behavior of the time scales was examined when constraints were imposed on variable ranges and interrelationships. Results: Constraints on ...
LUO Jia; HUANG YanYan; XIONG ShaoXiang; LIU GuoQuan; ZHAO Rui
2007-01-01
The specific interaction between sense and antisense peptides was studied by high-performance affinity chromatography (HPAC) and quartz crystal microbalance (QCM) biosensor. Fragment 1-14 of human interferon-β (hlFN-β) was chosen as sense peptide and its three antisense peptides (AS-IFN 1,AS-IFN 2, and AS-IFN 3) were designed according to the degeneracy of genetic codes. The affinity column was prepared with sense peptide as ligand and the affinity chromatographic behavior was evaluated. Glu-substituted antisense peptide (AS-IFN 3) showed the strongest binding to immobilized sense peptide at pH 7.5. A quartz crystal microbalance-flow injection analysis (QCM-FIA) system was introduced to investigate the recognition process in real-time. The equilibrium dissociation constants between sense peptide and AS-IFN 1, AS-IFN 2 and AS-IFN 3 measured 2.08×10-4, 1.31×10-4 and 2.22×10-5 mol/L, respectively. The mechanism study indicated that the specific recognition between sense peptide and AS-IFN 3 was due to sequence-dependent and multi-modal affinity interaction.
Jerzy Dziuba
2011-06-01
Full Text Available Background. Peptides are important components of foods mainly due to their biological activity. The basic method of their identification is reversed phase high-performance liquid chromatography coupled with electrospray-ionization mass spectrometry (RP-HPLC-ESI-MS. Retention time (tR prediction in silico is very helpful in analysis of multicomponent peptide mixtures. One of problems associated with RP-HPLC-ESI-MS is deterioration of mass spectra quality by trifluoroacetic acid (TFA. This problem can be avoided through the use of chromatographic columns designed for work with low TFA concentrations in mobile phase. The objective of this study was to determine the correlations between peptide retention times predicted with the use of a program available on-line and experimental retention times obtained using the column working with low TFA concentrations. Material and methods. The set of synthetic peptides and bovine α-lactalbumin fragments (18 peptides was used in the experiment. Theoretical retention times were calculated using Sequence Specific Retention Calculator (SSRC program. The experimental retention times were measured via RP-HPLC-ESI-MS method using column working with low TFA content. The dependence between theoretical and experimental tR was expressed via empirical equations. Results. The best correlation between theoretical and experimental retention times of peptides containing at least four amino acid residues has been obtained when third order polynomial (R² = 0.9536. Prediction quality for di- and tripeptides was significantly lower. The method described can be applied for cysteine-containing peptides although our sample preparation procedure did not include modification of this amino acid, taken into attention by SSRC program. Conclusions. The results of this study validate the usefulness of a third degree polynomial as a simple function describing the correlation between peptide retention times predicted by an on
Young Chon Choi; Ki Rok, Kwon; Suk Ho, Choi
2006-01-01
Objectives : This study was conducted to carry out Purification of Melittin and other peptide components from Bee Venom using gel filtration chromatography and propionic acid/urea polyacrylamide gel electrophoresis Methods : Melittin and other peptide components were separated from bee venom by using gel filtration chromatography on Sephadex G-50 column in 0.05M ammonium acetate buffer. Results : Melittin and other peptide components were separated from bee venom by using gel filtration...
Xie, Boer; Sharp, Joshua S.
2016-08-01
One difficult problem in the analysis of peptide modifications is quantifying isomeric modifications that differ by the position of the amino acid modified. HPLC separation using C18 reverse phase chromatography coupled with electron transfer dissociation (ETD) in tandem mass spectrometry has recently been shown to be able to relatively quantify how much of a given modification occurs at each amino acid position for isomeric mixtures; however, the resolution of reverse phase chromatography greatly complicates quantification of isomeric modifications by ETD because of the chromatographic separation of peptides with identical modifications at different sequence positions. Using peptide oxidation as a model system, we investigated the use of size exclusion chromatography coupled with ETD fragmentation to separate peptide sequences. This approach allows for the benefits of chromatographic separation of peptide sequences while ensuring co-elution of modification isomers for accurate relative quantification of modifications using standard data-dependent acquisitions. Using this method, the relative amount of modification at each amino acid can be accurately measured from single ETD MS/MS spectra in a standard data-dependent acquisition experiment.
Xie, Boer; Sharp, Joshua S
2016-08-01
One difficult problem in the analysis of peptide modifications is quantifying isomeric modifications that differ by the position of the amino acid modified. HPLC separation using C18 reverse phase chromatography coupled with electron transfer dissociation (ETD) in tandem mass spectrometry has recently been shown to be able to relatively quantify how much of a given modification occurs at each amino acid position for isomeric mixtures; however, the resolution of reverse phase chromatography greatly complicates quantification of isomeric modifications by ETD because of the chromatographic separation of peptides with identical modifications at different sequence positions. Using peptide oxidation as a model system, we investigated the use of size exclusion chromatography coupled with ETD fragmentation to separate peptide sequences. This approach allows for the benefits of chromatographic separation of peptide sequences while ensuring co-elution of modification isomers for accurate relative quantification of modifications using standard data-dependent acquisitions. Using this method, the relative amount of modification at each amino acid can be accurately measured from single ETD MS/MS spectra in a standard data-dependent acquisition experiment. Graphical Abstract ᅟ. PMID:27075875
Hao, Piliang; Qian, Jingru; Dutta, Bamaprasad; Cheow, Esther Sok Hwee; Sim, Kae Hwan; Meng, Wei; Adav, Sunil S; Alpert, Andrew; Sze, Siu Kwan
2012-03-01
Deamidation of asparaginyl residues in proteins produces a mixture of asparaginyl, n-aspartyl, and isoaspartyl residues, which affects the proteins' structure, function, and stability. Thus, it is important to identify and quantify the products to evaluate the effects in biological systems. It is still a challenging task to distinguish between the n-Asp and isoAsp deamidation products in a proteome-wide analysis because of their similar physicochemical properties. The quantification of the isomeric deamidated peptides is also rather difficult because of their coelution/poor separation in reverse-phase liquid chromatography (RPLC). We here propose a RP-ERLIC-MS/MS approach for separating and quantifying on a proteome-wide scale the three products related to deamidation of the same peptide. The key to the method is the use of RPLC in the first dimensional separation and ERLIC (electrostatic repulsion-hydrophilic interaction chromatography) in the second, with direct online coupling to tandem MS. The coelution of the three deamidation-related peptides in RPLC is then an asset, as they are collected in the same fraction. They are then separated and identified in the second dimension with ERLIC, which separates peptides on the basis of both pI and GRAVY values. The coelution of the three products in RPLC and their efficient separation in ERLIC were validated using synthetic peptides, and the performance of ERLIC-MS/MS was tested using peptide mixtures from two proteins. Applying this sequence to rat liver tissue, we identified 302 unique N-deamidated peptides, of which 20 were identified via all three deamidation-related products and 70 of which were identified via two of them. PMID:22239700
Lesur, Antoine; Varesio, Emmanuel; Domon, Bruno; Hopfgartner, Gérard
2012-01-01
We present a novel analytical platform for peptides quantitative assays in biological matrices based on microscale liquid chromatography fractionation and matrix-assisted laser desorption/ionization mass spectrometric detection using the selected reaction monitoring (SRM) mode. The MALDI source was equipped with a high frequency Nd:YAG laser (1000 Hz) and mounted on a triple quadrupole / linear ion trap mass spectrometer (MALDI-QqQLIT). Compared to conventional LC-ESI-SRM/MS, the separated an...
Statistical inference across time scales
Duval, Céline
2011-01-01
We investigate statistical inference across time scales. We take as toy model the estimation of the intensity of a discretely observed compound Poisson process with symmetric Bernoulli jumps. We have data at different time scales: microscopic, intermediate and macroscopic. We quantify the smooth statistical transition from a microscopic Poissonian regime to a macroscopic Gaussian regime. The classical quadratic variation estimator is efficient in both microscopic and macroscopic scales but surprisingly shows a substantial loss of information in the intermediate scale that can be explicitly related to the sampling rate. We discuss the implications of these findings beyond this idealised framework.
Zhang, Qiu-Xiang; Wu, Hui; Ling, Yu-Fang; Lu, Rong-Rong
2013-08-01
To isolate and identify antioxidant peptides from enzymatically hydrolysed whey protein, whey protein isolate was hydrolysed by different protease (trypsin, pepsin, alcalase 2·4L, promatex, flavourzyme, protease N). The hydrolysate generated by alcalase 2·4L had the highest antioxidant activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, superoxide radicals and in a linoleic acid peroxidation system induced by Fe2+. The IC50 values of DPPH and superoxide radical scavenging activities of the hydrolysate decreased significantly (6·89 and 38·88%, respectively) after treatment with macroporous adsorption resin. Seven different peptides showing strong antioxidant activities were isolated from the hydrolysate using consecutive chromatographic methods including gel filtration chromatography and high-performance liquid chromatography. The molecular mass and amino acids sequences of the purified peptides were determined using a Quadrupole time-of-flight mass spectrometer (Q-TOF MS). One of the antioxidative peptides, Trp-Tyr-Ser-Leu, displayed the highest DPPH radical scavenging activity (IC50=273·63 μm) and superoxide radical scavenging activity (IC50=558·42 μm). These results suggest that hydrolysates from whey proteins are good potential source of natural antioxidants. PMID:23876604
Symmetric Differentiation on Time Scales
da Cruz, Artur M. C. Brito; Martins, Natalia; Delfim F. M. Torres
2012-01-01
We define a symmetric derivative on an arbitrary nonempty closed subset of the real numbers and derive some of its properties. It is shown that real-valued functions defined on time scales that are neither delta nor nabla differentiable can be symmetric differentiable.
Parker, Benjamin L; Gupta, Pankaj; Cordwell, Stuart;
2011-01-01
-containing peptides were enriched using titanium dioxide chromatography. Modified peptides were analyzed using a combination of higher energy collision dissociation for identification and electron transfer dissociation to localize the site of O-GlcNAc attachment. The enrichment method was developed and...
Reversed-phase liquid chromatography of radiolabeled peptides using a C18 guard-PAK precolumn system
In order to avoid radioactive contamination of high-performance liquid chromatography columns and injectors, we have investigated the use of a Guard-PAK precolumn system for the chromatography of [125I] labeled peptides. Two gonadotropin-releasing hormone analogs: (1) [D-Ala6-des-Gly10]-GnRH (GnRH-[Ala6]) and (2) [D-Ser(TBu)6-des-Gly10]-GnRH (GnRH-[Ser6]) and rat prolactin (r-PRL) were radiolabeled with 125I and subjected to reversed-phase liquid chromatography using a C18 Guard-PAK precolumn system. Major peak fractions of purified [125I]GnRH-[Ala6], [125I]GnRH-[Ser6], and [125I]r-PRL eluted at 24%, 28%, and 55% acetonitrile, respectively. Purified [125I]GnRH analogs showed specific high affinity binding to rat anterior pituitary gland membranes (specific activity: 1500-1700 Ci/mmol). Purified [125I]r-PRL showed high affinity binding to r-PRL antibody by RIA (specific activity: 70-75 microCi/micrograms). This rapid and efficient chromatographic method should be useful in the separation of a wide range of radiolabeled protein and peptide molecules
Time Scales in Spectator Fragmentation
Schwarz, C; Bassini, R; Begemann-Blaich, M L; Gaff-Ejakov, S J; Gourio, D; Gross, C; Imme, G; Iori, I; Kleinevoss, U; Kunde, G J; Kunze, W D; Lynen, U; Maddalena, V; Mahi, M; Möhlenkamp, T; Moroni, A; Müller, W F J; Nociforo, C; Ocker, B; Odeh, T; Petruzzelli, F; Pochodzalla, J; Raciti, G; Riccobene, G; Romano, F; Saija, A; Schnittker, M; Schüttauf, A; Seidel, W; Serfling, V; Sfienti, C; Trautmann, W; Trzcinski, A; Verde, G; Wörner, A; Hong Fei Xi; Zwieglinski, B
2001-01-01
Proton-proton correlations and correlations of p-alpha, d-alpha, and t-alpha from spectator decays following Au + Au collisions at 1000 AMeV have been measured with an highly efficient detector hodoscope. The constructed correlation functions indicate a moderate expansion and low breakup densities similar to assumptions made in statistical multifragmentation models. In agreement with a volume breakup rather short time scales were deduced employing directional cuts in proton-proton correlations. PACS numbers: 25.70.Pq, 21.65.+f, 25.70.Mn
Graham, Mark E. [Molecular Structure and Detection Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308 (Australia); Dickson, Phillip W. [School of Biomedical Science, University of Newcastle, Callaghan, NSW 2308 (Australia); Dunkley, Peter R. [School of Biomedical Science, University of Newcastle, Callaghan, NSW 2308 (Australia); Nagy-Felsobuki, Ellak I. von [Molecular Structure and Detection Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308 (Australia)]. E-mail: ellak@newcastle.edu.au
2005-03-01
Tyrosine hydroxylase (TH) is involved in the biosynthesis of catecholamines and is activated by phosphorylation. Phosphorylated TH was analysed using high-pressure liquid chromatography combined with electrospray mass spectrometry (HPLC ESI-MS). Two mass scanning methods were used to detect tryptic cleavage products of TH. In the positive electrospray ionisation mode (ESI+), the peptides that contain the phosphorylation sites of TH were identified. In the alternative method, a phosphopeptide was detected in the negative electrospray ionisation mode (ESI-) using single ion monitoring in combination with a sequential ESI+ switching experiment. A raised baseline interfered with detection of hydrophilic peptides in ESI-, with the signal-to-noise ratio indicating that the method was operating near the limit of detection for a conventional electrospray source. The switching method improved the certainty of identification of phosphopeptides.
Tyrosine hydroxylase (TH) is involved in the biosynthesis of catecholamines and is activated by phosphorylation. Phosphorylated TH was analysed using high-pressure liquid chromatography combined with electrospray mass spectrometry (HPLC ESI-MS). Two mass scanning methods were used to detect tryptic cleavage products of TH. In the positive electrospray ionisation mode (ESI+), the peptides that contain the phosphorylation sites of TH were identified. In the alternative method, a phosphopeptide was detected in the negative electrospray ionisation mode (ESI-) using single ion monitoring in combination with a sequential ESI+ switching experiment. A raised baseline interfered with detection of hydrophilic peptides in ESI-, with the signal-to-noise ratio indicating that the method was operating near the limit of detection for a conventional electrospray source. The switching method improved the certainty of identification of phosphopeptides
Young Chon Choi
2006-06-01
Full Text Available Objectives : This study was conducted to carry out Purification of Melittin and other peptide components from Bee Venom using gel filtration chromatography and propionic acid/urea polyacrylamide gel electrophoresis Methods : Melittin and other peptide components were separated from bee venom by using gel filtration chromatography on Sephadex G-50 column in 0.05M ammonium acetate buffer. Results : Melittin and other peptide components were separated from bee venom by using gel filtration chromatography on Sephadex G-50 column in 0.05M ammonium acetate buffer. The fractions obtained from gel filtration chromatography was analyzed by using SDS-PAGE and propionic acid/urea polyacrylamide gel electrophoresis. The melittin obtained from the gel filtration contained residual amount of phospholipase A2 and a protein with molecular weight of 6,000. The contaminating proteins were removed by the second gel filtration chromatography. Conclusion : Gel filtration chromatography and propionic acid/urea polyacrylamide gel electrophoresis are useful to separate peptide components including melittin from bee venom.
Zenezini Chiozzi, Riccardo; Capriotti, Anna Laura; Cavaliere, Chiara; La Barbera, Giorgia; Piovesana, Susy; Samperi, Roberto; Laganà, Aldo
2016-08-01
Donkey milk is a valuable product for the food industry due to its nutraceutical, nutritional, and functional properties. In this work, the endogenous peptides from donkey milk were investigated for their antioxidant and ACE-inhibitory activities, combining a two-dimensional peptide fractionation strategy with high-resolution mass spectrometry, bioinformatics analysis, and in vitro assays. After extraction, the endogenous peptides were fractionated twice, first by polymeric reversed phase and then by hydrophilic interaction chromatography. Fractions were screened for the investigated bioactivities and only the most active ones were finally analyzed by nanoRP-HPLC-MS/MS; this approach allowed to reduce the total number of possible bioactive sequences. Results were further mined by in silico analysis using PeptideRanker, BioPep, and PepBank, which provided a bioactivity score to the identified peptides and matched sequences to known bioactive peptides, in order to select candidates for chemical synthesis. Thus, five peptides were prepared and then compared to the natural occurring ones, checking their retention times and fragmentation patterns in donkey milk alone and in spiked donkey milk samples. Pure peptide standards were finally in vitro tested for the specific bioactivity. In this way, two novel endogenous antioxidant peptides, namely EWFTFLKEAGQGAKDMWR and GQGAKDMWR, and two ACE-inhibitory peptides, namely REWFTFLK and MPFLKSPIVPF, were successfully validated from donkey milk. Graphical Abstract Analytical workflow for purification and identification of bioactive peptides from donkey milk sample. PMID:27325462
Holste, Angela Sarah
2014-01-01
This PhD thesis was a Cotutelle between the Université de Pau et des Pays de l’Adour (UPPA) in Pau, France and the Christian-Albrechts University (CAU) in Kiel, Germany. In the course of this international collaboration, bio-analytical methods for the quantitative and qualitative analysis of labelled peptides and proteins were developed, which were based on the hyphenation of chromatography with mass spectrometry. Peptides and protein digests were lanthanide labelled using DOTA-based comp...
Almost Periodic Time Scales and Almost Periodic Functions on Time Scales
Yongkun Li; Bing Li
2015-01-01
We propose some new concepts of almost periodic time scales and almost periodic functions on time scales and give some basic properties of these new types of almost periodic time scales and almost periodic functions on time scales. We also give some comments on a recent paper by Wang and Agarwal (2014) concerning a new almost periodic time scale.
Kjeldsen, Frank; Giessing, Anders; Ingrell, Christian R; Jensen, Ole N
2007-01-01
We have tested the effect of m-nitrobenzyl alcohol (m-NBA) as a method to increase the average charge state of protonated gas-phase molecular ions generated by ESI from tryptic peptides and phosphopeptides. Various concentrations of m-NBA were added to the mobile phases of a liquid chromatography...... Mascot score (24 units) than doubly charged peptides. m-NBA also increased the average charge state of phosphopeptides by up to 0.5 charge unit. The ease of implementation and the analytical benefits of charge enhancement of tryptic peptides by addition of m-NBA to the LC solvents suggest the general...
Sheng, Qianying; Yang, Kaiya; Xue, Xingya; Li, Xiuling; Guo, Zhimou; Shen, Aijin; Ke, Yanxiong; Lan, Minbo; Liang, Xinmiao
2015-09-25
An interesting and novel method for the selective and sequential enrichment of singly- and multiply-phosphorylated peptides with a zwitterionic material "Click TE-Cys" is presented. Retention mechanisms between phosphopeptides and Click TE-Cys are systematically investigated by checking the influence of acetonitrile content, pH value, and buffer concentration on the retention of phosphopeptides. Both hydrophilic interaction and electrostatic interaction are involved in retention between phosphopeptides and Click TE-Cys. Based on these results, an optimized method is established for selective enrichment of phosphopeptides using Click TE-Cys. This method not only exhibits high selectivity for phosphopeptides, but also fractionates singly- and multiply-phosphorylated peptides into two fractions. This method was evaluated using relatively complex samples, including peptide mixtures of α-casein and bovine serum albumin (BSA) at a molar ratio of 1:10 and skim milk. This efficient and optimized protocol has great potential for enriching multiply-phosphorylated peptides and could be a valuable tool for specific enrichment of phosphopeptides in phosphoproteome analysis. PMID:26298604
Lesur, Antoine; Varesio, Emmanuel; Domon, Bruno; Hopfgartner, Gérard
2012-10-01
We present a novel analytical platform for peptides quantitative assays in biological matrices based on microscale liquid chromatography fractionation and matrix-assisted laser desorption/ionization mass spectrometric detection using the selected reaction monitoring (SRM) mode. The MALDI source was equipped with a high frequency Nd:YAG laser (1000 Hz) and mounted on a triple quadrupole/linear ion trap mass spectrometer (MALDI-QqQ(LIT)). Compared to conventional LC-ESI-SRM/MS, the separated analytes are "time-frozen" onto the MALDI plate in fractions, and navigation through the LC chromatogram makes it possible to perform SRM experiments as well as enhanced product ion spectra acquisition for confirmatory analyses without time constraints. The LC spots were analyzed using different rastering speeds ranging from 0.25 to 4 mm/sec with the shortest analysis time of 425 ms/spot. Since the LC runs can be multiplexed and do not need a comprehensive investigation, the present platform offers a valuable alternative to LC-ESI-SRM/MS for high throughput proteomic analyses. In addition, the derivatization of the N-terminal α-amino group by sulfonation was found to be key for the fragmentation of singly charged peptides under low collision energy regime. Under such conditions, y-ion series were observed in the MS/MS spectra, and thus the design of SRM experiments was greatly simplified. The quantitative performance of the platform was compared to that of LC-ESI-SRM/MS by spiking yeast tryptic peptides in human plasma digests. Both platforms exhibited similar sensitivities, accuracy (within ±20%) and precision (under 20%) in the relative quantification mode. As a proof of principle, the relative and absolute quantification of proteins associated with glycolysis, glyoxylate and tricarboxylic acid (TCA) cycles over a growth time course of Saccharomyces cerevisiae on glucose media was successfully performed using isotopic dilution. PMID:22897511
Ying, Wantao; Perlman, David H.; Li, Lei(Beijing Institute of Petrochemical Technology, Beijing, 102617, People's Republic of China); Théberge, Roger; Costello, Catherine E; McComb, Mark E.
2009-01-01
The selective capture of target peptides poses a great challenge to modern chemists and biologists, especially when enriching them from proteome samples possessing extremes in concentration dynamic range and sequence diversity. While approaches based on traditional techniques such as biotin-avidin pairing offer versatile tools to design strategies for selective enrichment, problems are still encountered due to sample loss or poor selectivity of enrichment. Here we show that the recently intro...
The resolution potential of reverse-phase high-performance liquid chromatography (HPLC) for peptide analysis of hydrophobic viral membranes has been investigated, using as a model the membrane (M) protein of influenza virus. Proteolytic digests of 125I-labelled M protein CNBr fragments, extracted from radioiodinated whole virus, have been separated on a uBondapak C18 column with an isopropanol or acetonitrile solvent system. Peptide mapping of trypsin digests of M protein from A/PR/8/34 (H1N1) and A/chicken/Germany/N/49 (H10N7) viruses was identical, whereas Staphylococcus aureus V8 protease digests showed minor differences in at least two peptides. The results also show that HPLC is a powerful tool for the separation of proteolytic digests of viral proteins, since the peptide maps are highly reproducible and recovery was always greater than 85%. (Auth.)
Stochastic dynamic equations on general time scales
Martin Bohner; Olexandr M. Stanzhytskyi; Anastasiia O. Bratochkina
2013-01-01
In this article, we construct stochastic integral and stochastic differential equations on general time scales. We call these equations stochastic dynamic equations. We provide the existence and uniqueness theorem for solutions of stochastic dynamic equations. The crucial tool of our construction is a result about a connection between the time scales Lebesgue integral and the Lebesgue integral in the common sense.
Kalman plus weights: a time scale algorithm
Greenhall, C. A.
2001-01-01
KPW is a time scale algorithm that combines Kalman filtering with the basic time scale equation (BTSE). A single Kalman filter that estimates all clocks simultaneously is used to generate the BTSE frequency estimates, while the BTSE weights are inversely proportional to the white FM variances of the clocks. Results from simulated clock ensembles are compared to previous simulation results from other algorithms.
Du, Yan; Wu, Dapeng; Guan, Yafeng
2016-06-01
Mobil Composition of Matter No. 41 (MCM-41) was the most frequently used mesoporous silica material to extract peptides from complex biological samples. However, there were confusing extraction conditions and large extraction efficiency variance among related reports, which resulted from unclear understanding about the interaction between the material and peptides. In this study, the extraction mechanism was investigated with one set of tryptic peptides by using high-performance liquid chromatography coupled with triple quadrupole mass spectrometry. Generally, hydrophobic interaction and electrostatic attraction were two major driving forces for extraction of peptides, while electrostatic repulsion greatly weakened the interaction between the material and peptides with isoelectric points below the pH. With most peptides positively charged and MCM-41 slightly negatively charged, most efficient extraction was obtained at pH 3, and it was proved that electrostatic and hydrophobic interaction acted in synergy for extraction of all the peptides. A mixed solution of acetonitrile with buffers of high pH or ion strength was demonstrated to be favorable for elution, which performed much better than the commonly used eluate (mixture of acetonitrile with 0.1% trifluoroacetic acid). Finally, under optimum conditions, it was found that extraction efficiency of MCM-41 for protein digest and human serum was greatly improved. PMID:27059091
Shibue, M.; Mant, C.T.; Hodges, R.S.
2005-01-01
The addition of salts, specifically sodium perchlorate (NaClO4), to mobile phases at acidic pH as ion-pairing reagents for reversed-phase high-performance liquid chromatography (RP-HPLC) has been generally overlooked. To demonstrate the potential of NaClO4 as an effective anionic ion-pairing reagent, we applied RP-HPLC in the presence of 0–100 mM sodium chloride (NaCl), sodium trifluoroacetate (NaTFA) or NaClO4 to two mixtures of synthetic 18-residue peptides: a mixture of peptides with the s...
Dou, Lin; Krull, I.S. (Northeastern Univ., Boston, MA (USA))
1990-12-01
Aromatic amino acids, sulfur-containing amino acids, peptides containing such constituents, and proteins can now be detected in high-performance liquid chromatography by the use of on-line, postcolumn, continuous photolytic derivatization with electrochemical (HPLC-h{nu}-EC) detection. The overall approach is a very simple, reproducible, rapid, and fully automatable approach for the determination of certain amino acids, peptides, and proteins with excellent selectivity, sensitivity, and linearities of response. Dual-electrode response ratios, lamp-on/lamp-off behavior, and chromatographic capacity factors all contribute to the enhanced selectivity of the overall HPLC-h{nu}-EC determination for these particular classes of bioorganics and biopolymers. The analytical figures of merit, chromatography detection, and method validation approaches have all be optimally derived and demonstrated reproducible. Applications of the basic methodology to real-world samples are demonstrated and validated.
Wu, Xu; Si, Nan; Bo, Gao; Hu, Hao; Yang, Jian; Bian, Baolin; Zhao, Hai Yu; Wang, Hongjie
2015-01-01
Cinobufacini injection that comes from the water extract of Bufo bufo gargarizans Cantor skin is widely used for cancer treatment in China. Peptide is one of its major types of constituents, however the biological effects and content of this injection are little reported. In present study, the analgesic effect of peptides was determined and evaluated by in-vivo models. To characterize and quantitatively analyze these peptides, a reliable and efficient method combining size exclusion chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with amino acid analysis was developed. The peptides presented as a series of analogs with similar molecular weights mostly ranging from 2 to 8 kDa. The amino acid analysis by gas chromatography mass spectrometry (GC-MS) was developed to determine both free and combined amino acids (FAA and CAA) in cinobufacini injection. This method achieved good linearity (R(2) , 0.9909-0.9999) and low limit of detection and quantification. FAA and CAA samples were efficiently analyzed by modified Phenomenex EZ: faast procedure. For the sample analysis, the method showed good repeatability (relative standard deviation, RSD ≤ 10%). For most FAA and CAA the mean recoveries were >80% with RSD <10%. The GC-MS based method is useful for quality assurance of both FAA and CAA in cinobufacini injection. PMID:24924921
Chi Wang; Hui He; Jiu-liang Zhang; Xing Li; Zhi-li Ma
2016-01-01
Corn peptides (CPs) are reported to have many biological functions, such as facilitating alcohol metabolism, antioxidation, antitumor, antihypertension, and hepatoprotection. To develop a method for quality control, the high-performance liquid chromatography (HPLC) system was applied. Twenty-eight common peaks were found in all the CPs of corn samples from Enshi, China, based on which, a fingerprinting chromatogram was established for use in quality control in future research. Subsequently, t...
Ling Xiao
2015-01-01
Full Text Available Background: Hirudo nipponica Whitman and Poecilobdella manillensis Lesson fall into the family of Hirudinidae Whitman, both of them are sanguinovorous leeches and used a anticoagulant medicines in China. Their medicinal parts are the dried bodies. However, the peptides in the dried body of the two leeches have not been very clear up to now. Objective: To analyze the peptides from two sanguinovorous leeches, H. nipponica and P. manillensis. Materials and Methods: In this article it is reported that the peptides were obtained from anticoagulant active extracted parts of dried bodies of the two leeches and their molecular weights were analyzed by ultra-performance liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry mass spectrometric detector online. Results: Three peptide components were identified from H. nipponica with their molecular weight separately 14998, 15988, and 15956, six peptide components were identified from P. manillensis with molecular weight 9590, 13642, 14998, 17631, 15988, and 16567. Two of peptides from P. manillensis have the same molecular weight 14998 and 15988 as that in H. nipponica. Conclusion: And the two peptides are the main peaks in the base peak ion chromatogram because they occupied a large ratio of total base peak area. Hence the composition of the extracted active part of the two leeches are very close, difference is in that the extract of P. manillensis has more small peptide peaks, but the extract of H. nipponica has not. Furthermore, the tryptic digestion hydrolysates of the extracted active part of each sample were analyzed and the results showed that there were four peaks which only exist in P. manillensis, but not in Hirudo nipponia. They may be the identified peak between the two leeches. This work support the viewpoint that P. manillensis can be used as a medicinal leech as H. nipponia and these peptide components of dried bodies of the two species leeches are a
Gevaert, Bert; D'Hondt, Matthias; Bracke, Nathalie; Yao, Han; Wynendaele, Evelien; Vissers, Johannes Petrus Cornelis; De Cecco, Martin; Claereboudt, Jan; De Spiegeleer, Bart
2015-09-01
Cerebrolysin, a parenteral peptide preparation produced by controlled digestion of porcine brain proteins, is an approved nootropic medicine in some countries. However, it is also easily and globally available on the Internet. Nevertheless, until now, its exact chemical composition was unknown. Using high performance liquid chromatography (HPLC) coupled to ion trap and ultra high performance liquid chromatography (UHPLC) coupled to quadrupole-ion mobility-time-of-flight mass spectrometry (Q-IM-TOF MS), combined with UniProt pig protein database search and PEAKS de novo sequencing, we identified 638 unique peptides in an Internet-obtained Cerebrolysin sample. The main components in this sample originate from tubulin alpha- and beta-chain, actin, and myelin basic protein. No fragments of known neurotrophic factors like glial cell-derived neurotrophic factor (GDNF), neurotrophin nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and ciliary neurotrophic factor (CNTF) were found, suggesting that the activities reported in the literature are likely the result of new, hitherto unknown cryptic peptides with nootropic properties. PMID:26017115
无
2009-01-01
Peptidomics has emerged as a new discipline in recent years. Mass spectrometry (MS) is the most universal and efficient tool for structure identification of proteins and peptides. However,there is a limitation for the identification of peptides with the same amino acid composition but different se-quences because these peptides have identical mass spectra of molecular ions. This paper presents a high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method for the separation of small molecular peptides with the same amino acid composition but dif-ferent sequences. Two tripeptides of Gly-Ser-Phe and Gly-Phe-Ser were used as a model sample. The separation behavior has been investigated and the separation conditions have been optimized. Under the optimum conditions,good repeatability was achieved. The developed method could provide a helpful reference for the separation of other peptides with the same amino acid composition but different sequences in the study of proteomics and peptidomics.
Miriam Sanz
2015-06-01
Full Text Available Cyanobacteria from underexplored and extreme habitats are attracting increasing attention in the search for new bioactive substances. However, cyanobacterial communities from tropical and subtropical regions are still largely unknown, especially with respect to metabolite production. Among the structurally diverse secondary metabolites produced by these organisms, peptides are by far the most frequently described structures. In this work, liquid chromatography/electrospray ionization coupled to high resolution quadrupole time-of-flight tandem mass spectrometry with positive ion detection was applied to study the peptide profile of a group of cyanobacteria isolated from the Southeastern Brazilian coastal forest. A total of 38 peptides belonging to three different families (anabaenopeptins, aeruginosins, and cyanopeptolins were detected in the extracts. Of the 38 peptides, 37 were detected here for the first time. New structural features were proposed based on mass accuracy data and isotopic patterns derived from full scan and MS/MS spectra. Interestingly, of the 40 surveyed strains only nine were confirmed to be peptide producers; all of these strains belonged to the order Nostocales (three Nostoc sp., two Desmonostoc sp. and four Brasilonema sp..
Some Nonlinear Dynamic Inequalities on Time Scales
Wei Nian Li; Weihong Sheng
2007-11-01
The aim of this paper is to investigate some nonlinear dynamic inequalities on time scales, which provide explicit bounds on unknown functions. The inequalities given here unify and extend some inequalities in (B G Pachpatte, On some new inequalities related to a certain inequality arising in the theory of differential equation, J. Math. Anal. Appl. 251 (2000) 736--751).
Some Nonlinear Integral Inequalities on Time Scales
Li Wei Nian; Sheng Weihong
2007-01-01
The purpose of this paper is to investigate some nonlinear integral inequalities on time scales. Our results unify and extend some continuous inequalities and their corresponding discrete analogues. The theoretical results are illustrated by a simple example at the end of this paper.
Some Nonlinear Integral Inequalities on Time Scales
Li Wei Nian
2007-01-01
Full Text Available The purpose of this paper is to investigate some nonlinear integral inequalities on time scales. Our results unify and extend some continuous inequalities and their corresponding discrete analogues. The theoretical results are illustrated by a simple example at the end of this paper.
Multiple time scales is well named.
Gibbon, J.
1999-01-01
Staddon and Higa's article is a critique of scalar expectancy theory, and a proposed alternative, multiple time scales. The critique is generally flawed, both factually and logically. The alternative is bewildering in its flexibility, opaque in its quantitative description, and never addressed to real data.
Cruz-Huerta, Elvia; Martínez Maqueda, Daniel; de la Hoz, Lucia; da Silva, Vera S Nunes; Pacheco, Maria Teresa Bertoldo; Amigo, Lourdes; Recio, Isidra
2016-01-01
Peptides with iron-binding capacity obtained by hydrolysis of whey protein with Alcalase (Novozymes, Araucaria, PR, Brazil), pancreatin, and Flavourzyme (Novozymes) were identified. Hydrolysates were subjected to iron (III)-immobilized metal ion affinity chromatography, and the bound peptides were sequenced by mass spectrometry. Regardless of the enzyme used, the domains f(42-59) and f(125-137) from β-lactoglobulin enclosed most of identified peptides. This trend was less pronounced in the case of peptides derived from α-lactalbumin, with sequences deriving from diverse regions. Iron-bound peptides exhibited common structural characteristics, such as an abundance of Asp, Glu, and Pro, as revealed by mass spectrometry and AA analysis. In conclusion, this characterization of iron-binding peptides helps clarify the relationship between peptide structure and iron-chelating activity and supports the promising role of whey protein hydrolysates as functional ingredients in iron supplementation treatments. PMID:26601589
K Conceição
2009-01-01
Full Text Available Amphibian skin secretions are a source of potential new drugs with medical and biotechnological applications. Rich in peptides produced by holocrine-type serous glands in the integument, these secretions play different roles, either in the regulation of physiological skin functions or in the defense against predators or microorganisms. The aim of the present work was to identify novel peptides with bradykinin-like structure and/or activity present in the skin of Phyllomedusa nordestina. In order to achieve this goal, the crude skin secretion of this frog was pre-fractionated by solid phase extraction and separated by reversed-phase chromatography. The fractions were screened for low-molecular-mass peptides and sequenced by mass spectrometry. It was possible to identify three novel bradykinin-related peptides, namely: KPLWRL-NH2 (Pnor 3, RPLSWLPK (Pnor 5 and VPPKGVSM (Pnor 7 presenting vascular activities as assessed by intravital microscopy. Pnor 3 and Pnor 7 were able to induce vasodilation. On the other hand, Pnor 5 was a potent vasoconstrictor. These effects were reproduced by their synthetic analogues.
De Boni, Silvia; Oberthür, Christine; Hamburger, Matthias; Scriba, Gerhard K E
2004-01-01
A reversed-phase HPLC method for the analysis of degradation products of the model aspartyl tripeptides Phe-Asp-GlyNH2 and Gly-Asp-PheNH2 after incubation at pH 2 and 10 was developed. Most of the compounds could be separated with a gradient of acetonitrile in water containing 0.1% trifluoroacetic acid. Resolution of the isomeric pairs L-Phe-alpha-L-Asp-GlyNH2/L-Phe-beta-L-Asp-GlyNH2 and L-Phe-alpha-D-Asp-GlyOH/L-Phe-beta-D-Asp-GlyOH was achieved with a gradient of acetonitrile in phosphate buffer, pH 5.0. Under acidic conditions the major degradation pathway was cleavage of the peptide backbone amide bonds yielding dipeptides and amino acids, C-terminal deamidation as well as formation of succidinimyl peptides. At alkaline pH both deamidation of the C-terminal amide as well as isomerization and concomitant enantiomerization of Asp were observed. The peaks were identified both by reference substances and by online electrospray mass spectrometry. The results were compared to a previous developed capillary electrophoresis method. Diastereomeric pairs ofpeptides that could not be separated by capillary electrophoresis were resolved by HPLC while the separation of corresponding pairs of alpha- and beta-Asp peptides was not always achieved by HPLC in contrast to capillary electrophoresis illustrating that both techniques can be complimentary in peptide analysis. PMID:14753775
Time scales and structures of wave interaction
Kartashova, Elena
2013-01-01
In this paper we give a general account of Wave Interaction Theory which by now consists of two parts: kinetic wave turbulence theory (WTT), using a statistical description of wave interactions, and the D-model recently introduced in \\emph{Kartashova, PRE \\textbf{86}: 041129 (2012)} describing interactions of distinct modes. Applying time scale analysis to weakly nonlinear wave systems modeled by the focusing nonlinear Sch\\"{o}dinger equation, we give an overview of the structures appearing in Wave Interaction Theory, their time scales and characteristic times. We demonstrate that kinetic cascade and D-cascade are not competing processes but rather two processes taking place at different time scales, at different characteristic levels of nonlinearity and due to different physical mechanisms. Taking surface water waves as an example we show that energy cascades in this system occur at much faster characteristic times than those required by the kinetic WTT but can be described as D-cascades. As D-model has no s...
Liquidity crises on different time scales
Corradi, Francesco; Zaccaria, Andrea; Pietronero, Luciano
2015-12-01
We present an empirical analysis of the microstructure of financial markets and, in particular, of the static and dynamic properties of liquidity. We find that on relatively large time scales (15 min) large price fluctuations are connected to the failure of the subtle mechanism of compensation between the flows of market and limit orders: in other words, the missed revelation of the latent order book breaks the dynamical equilibrium between the flows, triggering the large price jumps. On smaller time scales (30 s), instead, the static depletion of the limit order book is an indicator of an intrinsic fragility of the system, which is related to a strongly nonlinear enhancement of the response. In order to quantify this phenomenon we introduce a measure of the liquidity imbalance present in the book and we show that it is correlated to both the sign and the magnitude of the next price movement. These findings provide a quantitative definition of the effective liquidity, which proves to be strongly dependent on the considered time scales.
Delporte, Cédric; Noyon, Caroline; Raynal, Pierre; Dufour, Damien; Nève, Jean; Abts, Frederic; Haex, Martin; Zouaoui Boudjeltia, Karim; Van Antwerpen, Pierre
2015-03-13
In the last decades, proteomics has largely progressed. Mass spectrometry and liquid chromatography (LC) are generally used in proteomics. These techniques enable proper separation of peptides and good identification and/or quantification of them. Later, nano-scaled liquid chromatography, improvements of mass spectrometry resolution and sensitivity brought huge advancements. Enhancements in chemistry of chromatographic columns also brought interesting results. In the present work, the potency of identification of proteins by different nano-chip columns was studied and compared with classical LC column. The present study was applied to cardiovascular field where proteomics has shown to be highly helpful in research of new biomarkers. Protein extracts from atheroma plaques were used and proteomics data were compared. Results show that fewer spectra were acquired by the mass spectrometer when nano-chip columns were used instead of the classical ones. However, approximately 40% more unique peptides were identified by the recently optimized chip named Polaris-HR-chip-3C18 column, and 20% more proteins were identified. This fact leads to the identification of more low-abundance proteins. Many of them are involved in atheroma plaque development such as apolipoproteins, ceruloplasmin, etc. In conclusion, present data shows that recent developments of nanoLC column chemistry and dimensions enabled the improved detection and identification of low-abundance proteins in atheroma plaques. Several of them are of major interest in the field of cardiovascular disease. PMID:25680550
Short-time scale behavior modeling within long-time scale fuel cycle evaluations
Johnson, M.; Tsvetkov, P. [Dept. of Nuclear Engineering, Texas A and M Univ., 3133 TAMU, College Station, TX 77843 (United States); Lucas, S. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 (United States)
2012-07-01
Typically, short-time and long-time scales in nuclear energy system behavior are accounted for with entirely separate models. However, long-term changes in system characteristics do affect short-term transients through material variations. This paper presents an approach to consistently account for short-time scales within a nuclear system lifespan. The reported findings and developments are of significant importance for small modular reactors and other nuclear energy systems operating in autonomous modes. It is necessary to simulate the short time-scale kinetic behavior of the reactor as well as the long time-scale dynamics that occur with fuel burnup. The former is modeled using the point kinetics equations, while the latter is modeled by the Bateman equations. (authors)
Deciphering Time Scale Hierarchy in Reaction Networks.
Nagahata, Yutaka; Maeda, Satoshi; Teramoto, Hiroshi; Horiyama, Takashi; Taketsugu, Tetsuya; Komatsuzaki, Tamiki
2016-03-01
Markovian dynamics on complex reaction networks are one of the most intriguing subjects in a wide range of research fields including chemical reactions, biological physics, and ecology. To represent the global kinetics from one node (corresponding to a basin on an energy landscape) to another requires information on multiple pathways that directly or indirectly connect these two nodes through the entire network. In this paper we present a scheme to extract a hierarchical set of global transition states (TSs) over a discrete-time Markov chain derived from first-order rate equations. The TSs can naturally take into account the multiple pathways connecting any pair of nodes. We also propose a new type of disconnectivity graph (DG) to capture the hierarchical organization of different time scales of reactions that can capture changes in the network due to changes in the time scale of observation. The crux is the introduction of the minimum conductance cut (MCC) in graph clustering, corresponding to the dividing surface across the network having the "smallest" transition probability between two disjoint subnetworks (superbasins on the energy landscape) in the network. We present a new combinatorial search algorithm for finding this MCC. We apply our method to a reaction network of Claisen rearrangement of allyl vinyl ether that consists of 23 nodes and 66 links (saddles on the energy landscape) connecting them. We compare the kinetic properties of our DG to those of the transition matrix of the rate equations and show that our graph can properly reveal the hierarchical organization of time scales in a network. PMID:26641663
Quantum time scales in alpha tunneling
Kelkar, N G; Nowakowski, M
2008-01-01
The theoretical treatment of alpha decay by Gamow is revisited by investigating the quantum time scales in tunneling. The time spent by an alpha particle in front of the barrier and traversing it before escape is evaluated using microscopic alpha nucleus potentials. The half-life of a nucleus is shown to correspond to the time spent by the alpha knocking in front of the barrier. Calculations for medium and super heavy nuclei show that from a multitude of available tunneling time definitions, the transmission dwell time gives the bulk of the lifetime of the decaying state, in most cases.
Hernandez-Hernandez, Oswaldo; Quintanilla-Lopez, Jesus Eduardo; Lebron-Aguilar, Rosa; Sanz, Maria Luz; Moreno, F Javier
2016-01-01
This work explores the use of both hydrophilic interaction liquid chromatography (HILIC) and reverse phase liquid chromatography (RPLC) for the separation and subsequent characterization of bovine caseinomacropeptide (CMP) phosphopeptides and O-glycopeptides using a quadrupole-time-of-flight (QTOF) mass spectrometer with electrospray ionization. Two neutral, ethylene bridged hybrid (BEH) amide and polyhydroxyethyl aspartamide (PHEA), and a zwitterionic, sulfobetaine (ZIC), stationary phases were used for the HILIC mode, whilst an octadecylsilane (C18) stationary phase was employed for the RPLC separation. Overall, developed HILIC-QTOF method using the ZIC or BEH amide stationary phases resulted to be the most efficient methods to separate and characterize post-translationally modified (PTM) peptides without the need of any previous fractionation or derivatization step. The separation of phosphopeptides and differently sialylated O-glycopeptides in the ZIC stationary phase was dominated by an electrostatic repulsion interaction mechanism between the negatively charged phosphate groups or sialic acid moieties and the negatively charged terminal sulfonate group of the stationary phase, whereas the separation of either non-modified peptides or neutral O-glycopeptides both free of basic amino acids was based on a partitioning mechanism. In neutral amide columns, the separation was mainly dominated by hydrophilic partitioning, leading to a higher retention of the post-translationally modified peptides than the unmodified counterparts due to the hydrophilicity provided by the phosphate groups and/or O-glycans. As a consequence, HILIC-ESI-QTOF MS operating in the positive ion mode is a powerful tool for the characterization of underivatized O-glycopeptides and phosphopeptides. PMID:26278355
Various Time-Scales of Relaxation
Ali-Akbari, M; Ebrahim, H; Shahkarami, L
2016-01-01
Via gauge-gravity duality, relaxation of far-from-equilibrium initial states in a strongly coupled gauge theory has been investigated. In the system we consider in this paper there are two ways where the state under study can deviate from its equilibrium: anisotropic pressure and time-dependent expectation value of a scalar operator with \\Delta=2. In the gravity theory, this system corresponds to Einstein's general relativity with a non-trivial metric, including the anisotropy function, coupled to a massive scalar matter field. We study the effect of different initial configurations for scalar field and anisotropy function on physical processes such as thermalization, i.e. time evolution of event horizon, equilibration of the expectation value of scalar operator and isotropization. We also discuss time ordering of these time-scales.
Time-scaling properties of city fires
Highlights: → AnShan city fire sequence is featured by mono- and multi-fractal dynamics. → The monofractal scaling exponent α ∼ 1.0 indicates high degree of time-clusterization, decreasing with the loss. → The city-fire process is highly heterogeneous. → The appearance of the daily oscillation could be connected with the daily cycle of the anthropic activity. - Abstract: Time-scaling scale-invariant approaches have been used to feature the temporal distribution of city fire sequences recorded in the city of AnShan (China). Our findings reveal that the point process of the city fires is a fractal process with a high degree of time-clusterization of the events. The time-clustering phenomenon is visible for timescales larger than few hours. Furthermore, the fire process tends to be less time-clusterized with the increase of the loss. The application of multifractal detrended fluctuation analysis to the series of city-fires has revealed that the sequence is dynamically heterogeneous due to the different long-range time correlation properties for small and large interevent fluctuations.
Pröfrock, Daniel; Prange, Andreas
2009-09-25
The application of reversed phase liquid chromatography (RP-LC) hyphenated to inductively coupled plasma mass spectrometry (ICP-MS) for the accurate quantification of bio-molecules via covalently bound hetero atoms such as phosphorus is restricted, due to the known effects of increasing amounts of organic solvents on the ionization behavior of certain elements. An approach for the compensation of variations in the elemental response, due to changes in the solvent composition during the RP gradient separation of phosphorylated peptides is described, which includes the application of a second, matched reversed gradient, that is mixed post-column with the RP column outflow before entering the LC-ICP-MS interface. The experimental design allows the application of gradient separations, while the element-specific detection is carried out under isocratic conditions with a constant organic solvent intake into the plasma. A constant elemental response is a general pre-requisite for the application of ICP-MS for the absolute quantification of peptides via their hetero atom content, especially when no corresponding high purity standards are available or natural mono-isotopic hetero element tags are utilized. As complementary technique LC-electrospray ionization linear ion trap mass spectrometry (ESI-QTRAP-MS) has been used for peptide identification and to elucidate their phosphorus stoichiometry. Highly reproducible separations have been obtained with retention time and peak area RSDs of 0.05% and 7.6% (n=6), respectively. Detection limits for phosphorus of 6 microg L(-1) (6 pg absolute), have been realized, which corresponds to approximately 200 fmol of an average molecular weight, singly phosphorylated peptide. In addition an automatic routine for flow injection analysis (FIA) at the end of each chromatographic separation has been developed, to calibrate each chromatographic separation, which allows absolute quantification of the separated species, whenever their tag
Yan, Long; Chen, Jia; Xu, Bin; Guo, Lei; Xie, Yan; Tang, Jijun; Xie, Jianwei
2016-06-10
The terroristic availability of highly toxic nerve agents (NAs) highlights the necessity for a deep understanding of their toxicities and effective medical treatments. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method for a characterization of the NAs poisoning and an evaluation on the efficacy of reactivators in in vitro was developed for the first time. After exposure to sarin or VX and pepsin digestion, the specific peptides of acetylcholinesterase (AChE) in a purified status, i.e. undecapeptide "GESAGAASVGM" in free, unaged, or aged status was identified and quantified. A key termination procedure is focused to make the reaction system "frozen" and precisely "capture" the poisoning, aging and spontaneous reactivation status of AChE, and the abundance of such specific peptides can thus be simultaneously measured. In our established method, as low as 0.72% and 0.84% inhibition level of AChE induced by 0.5nM sarin and VX can be detected from the measurement of peptide adducts, which benefits a confirmation of NAs exposure, especially at extremely low levels. Comparing with conventional colorimetric Ellman assays, our method provides not only enzyme activity and inhibition rate, but also the precise poisoning status of NAs exposed AChE. Based on the full information provided by this method, the efficacy of reactivators, such as HI-6, obidoxime and pralidoxime, in the typical treatment of NAs poisoned AChE in in vitro was further evaluated. Our results showed that this method is a promising tool for the characterization of NAs poisoning and the evaluation of reactivator efficacy. PMID:27179675
Wu, Jianbin; An, Guanghui; Lin, Siqi; Xie, Jianbo; Zhou, Wei; Sun, Hao; Pan, Yi; Li, Guigen
2014-01-01
The solution phase synthesis of N-protected amino acids and peptides has been achieved through the Group-Assisted Purification (GAP) chemistry by avoiding disadvantages of other methods in regard to the difficult scale-up, expenses of solid and soluble polymers, etc. The GAP synthesis can reduce the use of solvents, silica gels, energy and manpower. In addition, the GAP auxiliary can be conveniently recovered for re-use and is of environmentally friendly benign by substantially reducing waste...
Homoclinical Structure of Dynamic Equations on Time Scales
Fen, Mehmet Onur
2016-01-01
Homoclinic and heteroclinic motions in dynamics equations on time scales is investigated. The utilized time scale is a specific one such that it is a union of disjoint compact intervals. A numerical example that supports the theoretical results is presented.
Wu, Jianbin; An, Guanghui; Lin, Siqi; Xie, Jianbo; Zhou, Wei; Sun, Hao; Pan, Yi; Li, Guigen
2014-02-01
The solution phase synthesis of N-protected amino acids and peptides has been achieved through the Group-Assisted Purification (GAP) chemistry by avoiding disadvantages of other methods in regard to the difficult scale-up, expenses of solid and soluble polymers, etc. The GAP synthesis can reduce the use of solvents, silica gels, energy and manpower. In addition, the GAP auxiliary can be conveniently recovered for re-use and is environmentally friendly and benign, and substantially reduces waste production in academic labs and industry. PMID:24336500
Ippoushi, Katsunari; Sasanuma, Motoe; Oike, Hideaki; Kobori, Masuko; Maeda-Yamamoto, Mari
2016-08-01
Pru av 2, a pathogenesis-related (PR) protein present in the sweet cherry (Prunus avium L.) fruit, is the principal allergen of cherry and one of the chief causes of pollen food syndrome (oral allergy syndrome). In this study, a quantitative assay for this protein was developed with the use of the protein absolute quantification (AQUA) method, which consists of liquid chromatography/tandem mass spectrometry (LC/MS/MS) employing TGC[CAM]STDASGK[(13)C6,(15)N2], a stable isotope-labelled internal standard (SIIS) peptide. This assay gave a linear relationship (r(2)>0.99) in a concentration range (2.3-600fmol/μL), and the overall coefficient of variation (CV) for multiple tests was 14.6%. Thus, the contents of this allergenic protein in sweet cherry products could be determined using this assay. This assay should be valuable for allergological investigations of Pru av 2 in sweet cherry and detection of protein contamination in foods. PMID:26988485
Percy, Andrew J; Yang, Juncong; Chambers, Andrew G; Borchers, Christoph H
2016-01-01
Absolute quantitative strategies are emerging as a powerful and preferable means of deriving concentrations in biological samples for systems biology applications. Method development is driven by the need to establish new-and validate current-protein biomarkers of high-to-low abundance for clinical utility. In this chapter, we describe a methodology involving two-dimensional (2D) reversed-phase liquid chromatography (RPLC), operated under alkaline and acidic pH conditions, combined with multiple reaction monitoring (MRM)-mass spectrometry (MS) (also called selected reaction monitoring (SRM)-MS) and a complex mixture of stable isotope-labeled standard (SIS) peptides, to quantify a broad and diverse panel of 253 proteins in human blood plasma. The quantitation range spans 8 orders of magnitude-from 15 mg/mL (for vitamin D-binding protein) to 450 pg/mL (for protein S100-B)-and includes 31 low-abundance proteins (defined as being application of our recently developed software tool-Qualis-SIS-for protein quantitation (via regression analysis of standard curves) and quality assessment of the resulting data. Overall, this chapter provides the blueprint for the replication of this quantitative proteomic method by proteomic scientists of all skill levels. PMID:26867735
Multiple Time Scales and Longitudinal Measurements in Event History Analysis
Danardono,
2005-01-01
A general time-to-event data analysis known as event history analysis is considered. The focus is on the analysis of time-to-event data using Cox's regression model when the time to the event may be measured from different origins giving several observable time scales and when longitudinal measurements are involved. For the multiple time scales problem, procedures to choose a basic time scale in Cox's regression model are proposed. The connections between piecewise constant hazards, time-depe...
Synchronization in complex systems with multiple time scales
Bergner, André
2011-01-01
In the present work synchronization phenomena in complex dynamical systems exhibiting multiple time scales have been analyzed. Multiple time scales can be active in different manners. Three different systems have been analyzed with different methods from data analysis. The first system studied is a large heterogenous network of bursting neurons, that is a system with two predominant time scales, the fast firing of action potentials (spikes) and the burst of repetitive spikes followed by a qui...
Time scales in Galveston Bay: An unsteady estuary
Rayson, Matthew D.; Gross, Edward S.; Hetland, Robert D.; Fringer, Oliver B.
2016-04-01
Estuarine time scales including the turnover, particle e-folding time, the age (calculated with a passive tracer), and residence time (calculated with Lagrangian particles) were computed using a three-dimensional hydrodynamic model of Galveston Bay, a low-flow, partially stratified estuary. Time scales were computed during a time period when river flow varied by several orders of magnitude and all time scales therefore exhibited significant temporal variability because of the unsteadiness of the system. The spatial distributions of age and residence time were qualitatively similar and increased from 15 days in a shipping channel to >45 days in the upper estuary. Volume-averaged age and residence time decreased during high-flow conditions. Bulk time scales, including the freshwater and salinity turnover times, were far more variable due to the changing river discharge and salt flux through the estuary mouth. A criterion for calculating a suitable averaging time is discussed to satisfy a steady state assumption and to estimate a more representative bulk time scale. When scaled with a freshwater advective time, all time scales were approximately equal to the advective time scale during high-flow conditions and many times higher during low-flow conditions. The mean age, Lagrangian residence, and flushing times exhibited a relationship that was weakly dependent on the freshwater advective time scale demonstrating predictability even in an unsteady, realistic estuary.
A new generalization of Ostrowski type inequality on time scales
Liu, Wenjun
2008-01-01
In this paper we first extend a generalization of Ostrowski type inequality on time scales for functions whose derivatives are bounded and then unify corresponding continuous and discrete versions. We also point out some particular integral type inequalities on time scales as special cases.
Time scales of supercooled water and implications for reversible polyamorphism
Limmer, David T.; Chandler, David
2015-09-01
Deeply supercooled water exhibits complex dynamics with large density fluctuations, ice coarsening and characteristic time scales extending from picoseconds to milliseconds. Here, we discuss implications of these time scales as they pertain to two-phase coexistence and to molecular simulations of supercooled water. Specifically, we argue that it is possible to discount liquid-liquid criticality because the time scales imply that correlation lengths for such behavior would be bounded by no more than a few nanometers. Similarly, it is possible to discount two-liquid coexistence because the time scales imply a bounded interfacial free energy that cannot grow in proportion to a macroscopic surface area. From time scales alone, therefore, we see that coexisting domains of differing density in supercooled water can be no more than nano-scale transient fluctuations.
Temperature dependence of fluctuation time scales in spin glasses
Kenning, Gregory G.; Bowen, J.; Sibani, Paolo;
2010-01-01
Using a series of fast cooling protocols we have probed aging effects in the spin glass state as a function of temperature. Analyzing the logarithmic decay found at very long time scales within a simple phenomenological barrier model, leads to the extraction of the fluctuation time scale of the s......-aging behavior in scaling aged TRM decay curves, as recently discussed theoretically~\\cite{Sibani09}.......Using a series of fast cooling protocols we have probed aging effects in the spin glass state as a function of temperature. Analyzing the logarithmic decay found at very long time scales within a simple phenomenological barrier model, leads to the extraction of the fluctuation time scale of the...... system at a particular temperature. This is the smallest dynamical time-scale, defining a lower-cut off in a hierarchical description of the dynamics. We find that this fluctuation time scale, which is approximately equal to atomic spin fluctuation time scales near the transition temperature, follows a...
AGN variability time scales and the discrete-event model
Favre, P; Courvoisier, T. J. -L.; Paltani, S.
2005-01-01
We analyse the ultraviolet variability time scales in a sample of 15 Type 1 Active Galactic Nuclei (AGN) observed by IUE. Using a structure function analysis, we demonstrate the existence in most objects of a maximum variability time scale of the order of 0.02-1.00 year. We do not find any significant dependence of these maximum variability time scales on the wavelength, but we observe a weak correlation with the average luminosity of the objects. We also observe in several objects the existe...
Phase synchronization of coupled chaotic multiple time scales systems
The brushless dc motor (BLDCM) with multi-time scales is an electric machine. By coupled BLDCM, it is discovered that chaotic routes of the uncoupled systems influence synchronous result of coupled identical and nonidentical chaotic systems. Another multi-time scales form, Hindmarsh-Rose (HR) neurons, when the chaotic parameter is selected only in the range of the period-doubling route to chaos, phase synchronization can be predicted via Laypunov exponent. Finally, Laypunov exponent however cannot be used as a criterion for phase synchronization of coupled chaotic systems with either single or multi-time scales in our study
Lyapunov functions for linear nonautonomous dynamical equations on time scales
Zmorzynska Alexandra
2006-01-01
Full Text Available The existence of a Lyapunov function is established following a method of Yoshizawa for the uniform exponential asymptotic stability of the zero solution of a nonautonomous linear dynamical equation on a time scale with uniformly bounded graininess.
A remark for dynamic equations on time scales
Akhmet, Marat; TURAN, Mehmet
2010-01-01
We give a proposal to generalize the concept of the differential equations on time scales, such that they can be more appropriate for the analysis of real world problems, and give more opportunities to increase the theoretical depth of investigation.
BOUNDARY VALUE PROBLEM TO DYNAMIC EQUATION ON TIME SCALE
无
2011-01-01
In this paper we consider a nonlinear first-order boundary value problem on a time scale. The existence results of three positive solutions are obtained using fixed point theorems. Finally,examples are presented to illustrate the main results.
Hydrodynamic Time Scales and Temporal Structure in GRBs
Sari, Re'em; Piran, Tsvi
1995-01-01
We calculate the hydrodynamic time scales for a spherical ultra-relativistic shell that is decelerated by the ISM and discuss the possible relations between these time scales and the observed temporal structure in $\\gamma$-ray bursts. We suggest that the bursts' duration is related to the deceleration time, the variability is related to the ISM inhomogeneities and precursors are related to internal shocks within the shell. Good agreement can be achieved for these quantities with reasonable, n...
Enhanced sampling development for accessing long time scale protein dynamics
Pierce, Levi C. T.
2012-01-01
Computational modeling has played a great role in solving many questions in biochemical and biomedical research. However, many biologically relevant processes occur on long time scales, which are inaccessible to conventional modeling techniques. Accessing these long time scales has been a great challenge for computational scientists, which has led to the development of numerous methods for enhanced sampling. In this work the well established accelerated molecular dynamics (aMD) method is impl...
Puchalska, Patrycja; García, M Concepción; Marina, M Luisa
2014-04-18
Soybean peptide VLIVP presents a very high antihypertensive activity (IC50 value 1.69μM), even higher than extensively studied IPP and VPP peptides from milk. Nevertheless, no much attention has been paid to this peptide and there is no method enabling its determination in soybeans. The aim of this work was the development of an analytical methodology for this purpose. A methodology consisting of the extraction of soybean proteins, their digestion with Protease P enzyme, their chromatographic separation using capillary-HPLC, and IT-MS detection was optimized. Protein extraction was performed by the use of high intensity focused ultrasounds to obtain a reduced extraction time. Optimization of chromatographic and mass spectrometry parameters enabled the separation of VLIVP peptide within just 7min and its sensitive detection. The analytical characteristics of the capillary-HPLC-IT-MS method were evaluated through the study of linearity, LOD, LOQ, study of the presence of matrix interferences, precision, and recovery. The method enabled to detect as low as 3.6ng of peptide and to determine as low as 12ng of peptide in 1g of soybean (as dry basis). Finally, the developed method was applied to the determination of the antihypertensive peptide VLIVP in different soybean varieties. The results showed the highest yield of VLIVP peptide in variety Mazowiecka II from Poland. PMID:24630980
Time scales and species coexistence in chaotic flows
Galla, Tobias
2016-01-01
Empirical observations in marine ecosystems have suggested a balance of biological and advection time scales as a possible explanation of species coexistence. To characterise this scenario, we measure the time to fixation in neutrally evolving populations in chaotic flows. Contrary to intuition the variation of time scales does not interpolate straightforwardly between the no-flow and well-mixed limits; instead we find that fixation is the slowest at intermediate Damk\\"ohler numbers, indicating long-lasting coexistence of species. Our analysis shows that this slowdown is due to spatial organisation on an increasingly modularised network. We also find that diffusion can either slow down or speed up fixation, depending on the relative time scales of flow and evolution.
Wind power impacts and electricity storage - a time scale perspective
Hedegaard, Karsten; Meibom, Peter
2012-01-01
Integrating large amounts of wind power in energy systems poses balancing challenges due to the variable and only partly predictable nature of wind. The challenges cover different time scales from intra-hour, intra-day/day-ahead to several days and seasonal level. Along with flexible electricity...... technologies – batteries, flow batteries, compressed air energy storage, electrolysis combined with fuel cells, and electric vehicles – are moreover categorised with respect to the time scales at which they are suited to support wind power integration. While all of these technologies are assessed suitable for...... demand options, various electricity storage technologies are being discussed as candidates for contributing to large-scale wind power integration and these also differ in terms of the time scales at which they can operate. In this paper, using the case of Western Denmark in 2025 with an expected 57% wind...
Multiple time scales of fluvial processes—theory and applications
无
2011-01-01
Fluvial processes comprise water flow,sediment transport and bed evolution,which normally feature distinct time scales.The time scales of sediment transport and bed deformation relative to the flow essentially measure how fast sediment transport adapts to capacity region in line with local flow scenario and the bed deforms in comparison with the flow,which literally dictates if a capacity based and/or decoupled model is justified.This paper synthesizes the recently developed multiscale theory for sediment-l...
Short—Time Scaling of Variable Ordering of OBDDs
龙望宁; 闵应骅; 等
1997-01-01
A short-time scaling criterion of variable ordering of OBDDs is proposed.By this criterion it is easy and fast to determine which one is better when several variable orders are given,especially when they differ 10% or more in resulted BDD size from each other.An adaptive variable order selection method,based on the short-time scaling criterion,is also presented.The experimental results show that this method is efficient and it makes the heuristic variable ordering methods more practical.
Xu, Feifei; Yang, Ting; Chen, Yun
2016-01-01
The distorted and unique expression of microRNAs (miRNAs) in cancer makes them an attractive source of biomarkers. However, one of prerequisites for the application of miRNAs in clinical practice is to accurately profile their expression. Currently available assays normally require pre-enrichment, amplification, and labeling steps, and most of them are semiquantitative. In this study, we converted the signal of target miR-21 into reporter peptide by a DNA-peptide probe and the reporter peptide was ultimately quantified using LC-MS/MS-based targeted proteomics. Specifically, substrate peptide GDKAVLGVDPFR containing reporter peptide AVLGVDPFR and tryptic cleavage site (lysine at position 3) was first designed, followed by the conjugation with DNA sequence that was complementary to miR-21. The newly formed DNA-peptide probe was then hybridized with miR-21, which was biotinylated and attached to streptavidin agarose in advance. After trypsin digestion, the reporter peptide was released and monitored by a targeted proteomics assay. The obtained limit of quantification (LOQ) was 1 pM, and the detection dynamic range spanned ∼5 orders of magnitude. Using this assay, the developed quasi-targeted proteomics approach was applied to determine miR-21 level in breast cells and tissue samples. Finally, qRT-PCR was also performed for a comparison. This report grafted the strategy of targeted proteomics into miRNA quantification. PMID:26641144
Single-molecule binding experiments on long time scales
Elenko, Mark P.; Szostak, Jack W.; van Oijen, Antoine M.
2010-01-01
We describe an approach for performing single-molecule binding experiments on time scales from hours to days, allowing for the observation of slower kinetics than have been previously investigated by single-molecule techniques. Total internal reflection fluorescence microscopy is used to image the b
Exponential stability of dynamic equations on time scales
Raffoul Youssef N
2005-01-01
Full Text Available We investigate the exponential stability of the zero solution to a system of dynamic equations on time scales. We do this by defining appropriate Lyapunov-type functions and then formulate certain inequalities on these functions. Several examples are given.
Holographic Brownian motion and time scales in strongly coupled plasmas
A. Nata Atmaja; J. de Boer; M. Shigemori
2010-01-01
We study Brownian motion of a heavy quark in field theory plasma in the AdS/CFT setup and discuss the time scales characterizing the interaction between the Brownian particle and plasma constituents. In particular, the mean-free-path time is related to the connected 4-point function of the random fo
Multiple time scales in the microwave ionization of Rydberg atoms
Buchleitner, A.; Delande, D.; Zakrzewski, J.; Mantegna, R.N.; Arndt, M.; Walther, H. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany)]|[Laboratoire Kastler Brossel, 4 place Jussieu, Tour 12, 1 etage, F-75252 Paris Cedex 05 (France)]|[Instytut Fizyki Uniwersytetu Jagiellonskiego, ul. Reymonta 4, PL-30-059 Krakow (Poland)]|[Dipartimento di Energetica ed Applicazioni di Fisica, Universita di Palermo, Viale delle Scienze, I-90128 Palermo (Italy)]|[Sektion Physik der Universitaet Muenchen, Am Coulombwall 1, D-85748 Garching (Germany)
1995-11-20
We investigate the time dependence of the ionization probability of Rydberg atoms driven by microwave fields, both numerically and experimentally. Our exact quantum results provide evidence for an algebraic decay law on suitably chosen time scales, a phenomenon that is considered to be the signature of nonhyperbolic scattering in unbounded classically chaotic motion. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.
Geissman, J. W.; Walker, J. D.
2012-12-01
Geologic time scales, of one form or another, are used in most undergraduate geosciences courses, even including introductory physical geology or equivalent. However, satisfactory discussions of how geologic time scales originated, and how they have evolved to modern versions, are far too often conveniently or inconveniently left out of classroom discussions. Yet it is these kinds of discussions that have the potential of solidifying student appreciation of deep time and rates of geologic processes. We use the history and development of the Geological Society of America Geologic Time Scale, which reflects major developments in the fields of stratigraphy, geochronology, magnetic polarity stratigraphy, astrochronology, and chemostratigraphy, as a focus of how specific details of time scales can be used to teach about time. Advances in all of these fields have allowed many parts of the time scale to be calibrated to precisions approaching less than 0.05 %. Notable time intervals for which collaborative, multifaceted efforts have led to dramatic improvements in our understanding of the character and temporal resolution of key evolutionary events, in both marine and terrestrial environments, include the Triassic-Jurassic, Permo-Triassic, and Neoproterozoic-Phanerozoic boundaries (or transitions). Many of the details, but certainly not all, can be incorporated in discussions of how we know about geologic time in the classroom. For example, we presently understand that both the end-Permian ecological crisis and the biostratigraphic Permian-Triassic boundary, as calibrated by conodonts, lie within a ca. 700 ka long normal polarity chron. The reverse to normal polarity transition at the beginning of this chron is ca. 100 ka earlier than the ecological crisis and thus slightly older than the current estimate, based on high precision U-Pb zircon age determinations, of ca. 252.4 Ma for the Permian-Triassic boundary. This polarity transition occurred during the early part of
K Conceição; FM Bruni; JM Sciani; Konno, K; RL Melo; MM Antoniazzi; C Jared; M Lopes-Ferreira; DC Pimenta
2009-01-01
Amphibian skin secretions are a source of potential new drugs with medical and biotechnological applications. Rich in peptides produced by holocrine-type serous glands in the integument, these secretions play different roles, either in the regulation of physiological skin functions or in the defense against predators or microorganisms. The aim of the present work was to identify novel peptides with bradykinin-like structure and/or activity present in the skin of Phyllomedusa nordestina. In or...
Ulmschneider, Martin B.; Doux, Jacques P F; Killian, J. Antoinette; Smith, Jeremy C.; Ulmschneider, Jakob P.
2010-01-01
Partitioning properties of transmembrane (TM) polypeptide segments directly determine membrane protein folding, stability, and function, and their understanding is vital for rational design of membrane active peptides. However, direct determination of water-to-bilayer transfer of TM peptides has proved difficult. Experimentally, sufficiently hydrophobic peptides tend to aggregate, while atomistic computer simulations at physiological temperatures cannot yet reach the long time scales required...
HMC algorithm with multiple time scale integration and mass preconditioning
We present a variant of the HMC algorithm with mass preconditioning (Hasenbusch acceleration) and multiple time scale integration. We have tested this variant for standard Wilson fermions at β = 5.6 and at pion masses ranging from 380 MeV to 680 MeV. We show that in this situation its performance is comparable to the recently proposed HMC variant with domain decomposition as preconditioner. We give an update of the ''Berlin Wall'' figure, comparing the performance of our variant of the HMC algorithm to other published performance data. Advantages of the HMC algorithm with mass preconditioning and multiple time scale integration are that it is straightforward to implement and can be used in combination with a wide variety of lattice Dirac operators. (orig.)
A time scale for electrical screening in pulsed gas discharges
Teunissen, Jannis; Ebert, Ute
2014-01-01
The Maxwell time is a typical time scale for the screening of an electric field in a medium with a given conductivity. We introduce a generalization of the Maxwell time that is valid for gas discharges: the \\emph{ionization screening time}, that takes the growth of the conductivity due to impact ionization into account. We present an analytic estimate for this time scale, assuming a planar geometry, and evaluate its accuracy by comparing with numerical simulations in 1D and 3D. We investigate the minimum plasma density required to prevent the growth of streamers with local field enhancement, and we discuss the effects of photoionization and electron detachment on ionization screening. Our results are especially relevant for the description of nanosecond pulsed discharges.
Realization of a time-scale with an optical clock
Grebing, C; Dörscher, S; Häfner, S; Gerginov, V; Weyers, S; Lipphardt, B; Riehle, F; Sterr, U; Lisdat, C
2015-01-01
Optical clocks are not only powerful tools for prime fundamental research, but are also deemed for the re-definition of the SI base unit second as they surpass the performance of caesium atomic clocks in both accuracy and stability by more than an order of magnitude. However, an important obstacle in this transition has so far been the limited reliability of the optical clocks that made a continuous realization of a time-scale impractical. In this paper, we demonstrate how this dilemma can be resolved and that a time-scale based on an optical clock can be established that is superior to one based on even the best caesium fountain clocks. The paper also gives further proof of the international consistency of strontium lattice clocks on the $10^{-16}$ accuracy level, which is another prerequisite for a change in the definition of the second.
Human learning: Power laws or multiple characteristic time scales?
Gottfried Mayer-Kress
2006-09-01
Full Text Available The central proposal of A. Newell and Rosenbloom (1981 was that the power law is the ubiquitous law of learning. This proposition is discussed in the context of the key factors that led to the acceptance of the power law as the function of learning. We then outline the principles of an epigenetic landscape framework for considering the role of the characteristic time scales of learning and an approach to system identification of the processes of performance dynamics. In this view, the change of performance over time is the product of a superposition of characteristic exponential time scales that reflect the influence of different processes. This theoretical approach can reproduce the traditional power law of practice within the experimental resolution of performance data sets - but we hypothesize that this function may prove to be a special and perhaps idealized case of learning.
Terrestrial waters and sea level variations on interannual time scale
Llovel, W.; Becker, M.; Cazenave, A.; Jevrejeva, S.; R. Alkama; Decharme, B.; Douville, H.; Ablain, M.; Beckley, B
2011-01-01
On decadal to multidecadal time scales, thermal expansion of sea waters and land ice loss are the main contributors to sea level variations. However, modification of the terrestrial water cycle due to climate variability and direct anthropogenic forcing may also affect sea level. For the past decades, variations in land water storage and corresponding effects on sea level cannot be directly estimated from observations because these are almost unexistent at global continental scale. However, g...
Isoperimetric problems on time scales with nabla derivatives
Almeida, Ricardo; Torres, Delfim F. M.
2008-01-01
We prove a necessary optimality condition for isoperimetric problems under nabla-differentiable curves. As a consequence, the recent results of [M.R. Caputo, A unified view of ostensibly disparate isoperimetric variational problems, Appl. Math. Lett. (2008), doi:10.1016/j.aml.2008.04.004], that put together seemingly dissimilar optimal control problems in economics and physics, are extended to a generic time scale. We end with an illustrative example of application of our main result to a dyn...
Time-Scale Feature Extractions for Emotional Speech Characterization
Chetouani, Mohamed; Ammar, Mahdhaoui; Ringeval, Fabien
2009-01-01
Emotional speech characterization is an important issue for the understanding of interaction. This article discusses the time-scale analysis problem in feature extraction for emotional speech processing. We describe a computational framework for combining segmental and supra-segmental features for emotional speech detection. The statistical fusion is based on the estimation of local a posteriori class probabilities and the overall decision employs weighting factors directly related to the dur...
MULTISCALE HOMOGENIZATION OF NONLINEAR HYPERBOLIC EQUATIONS WITH SEVERAL TIME SCALES
Jean Louis Woukeng; David Dongo
2011-01-01
We study the multiscale homogenization of a nonlinear hyperbolic equation in a periodic setting. We obtain an accurate homogenization result. We also show that as the nonlinear term depends on the microscopic time variable, the global homogenized problem thus obtained is a system consisting of two hyperbolic equations. It is also shown that in spite of the presence of several time scales, the global homogenized problem is not a reiterated one.
Variability Time Scales of Long and Short GRBs
Bhat, P N
2013-01-01
Gamma-ray bursts (GRB) are extremely energetic events and produce highly diverse light curves. Light curves are believed to be resulting from internal shocks reflecting the activities of the GRB central engine. Hence their temporal studies can potentially lead to an understanding of the GRB central engine and its evolution. The light curve variability time scale is an interesting parameter which most models attribute to a physical origin e.g., central engine activity, clumpy circum-burst medium, or relativistic turbulence. We develop a statistical method to estimate the GRB minimum variability time scale (MVT) for long and short GRBs detected by GBM. We find that the MVT of short bursts is distinctly shorter than that of long GRBs supporting the possibility of a more compact central engine of the former. We also find that MVT estimated by this method is consistent with the shortest rise time of the fitted pulses. Hence we use the fitted pulse rise times to study the evolution of burst variability time scale. ...
Time scale interactions and the coevolution of humans and water
Sivapalan, Murugesu; Blöschl, Günter
2015-09-01
We present a coevolutionary view of hydrologic systems, revolving around feedbacks between environmental and social processes operating across different time scales. This brings to the fore an emphasis on emergent phenomena in changing water systems, such as the levee effect, adaptation to change, system lock-in, and system collapse due to resource depletion. Changing human values play a key role in the emergence of these phenomena and should therefore be considered as internal to the system. Guidance is provided for the framing and modeling of these phenomena to test alternative hypotheses about how they arose. A plurality of coevolutionary models, from stylized to comprehensive system-of-system models, may assist strategic water management for long time scales through facilitating stakeholder participation, exploring the possibility space of alternative futures, and helping to synthesize the observed dynamics in a wide range of case studies. Future research opportunities lie in exploring emergent phenomena arising from time scale interactions through historical, comparative, and process studies of human-water feedbacks.
Backpropagation and ordered derivatives in the time scales calculus.
Seiffertt, John; Wunsch, Donald C
2010-08-01
Backpropagation is the most widely used neural network learning technique. It is based on the mathematical notion of an ordered derivative. In this paper, we present a formulation of ordered derivatives and the backpropagation training algorithm using the important emerging area of mathematics known as the time scales calculus. This calculus, with its potential for application to a wide variety of inter-disciplinary problems, is becoming a key area of mathematics. It is capable of unifying continuous and discrete analysis within one coherent theoretical framework. Using this calculus, we present here a generalization of backpropagation which is appropriate for cases beyond the specifically continuous or discrete. We develop a new multivariate chain rule of this calculus, define ordered derivatives on time scales, prove a key theorem about them, and derive the backpropagation weight update equations for a feedforward multilayer neural network architecture. By drawing together the time scales calculus and the area of neural network learning, we present the first connection of two major fields of research. PMID:20615808
Surface charge measurements in barrier discharges on different time scales
Wild, Robert; Volkhausen, Christian; Benduhn, Johannes; Stollenwerk, Lars
2015-09-01
The deposition of surface charge in barrier discharges is a process that influences the ongoing discharge significantly. This contribution presents the measurement of absolute surface charge densities and their dynamics in a laterally extended setup. An electro-optic BSO crystal is used as dielectric. The absolute charge density on its surface is deduced from the change of polarisation of light passing the crystal. Using different temporal resolutions, the behavior of charge is investigated on three different time scales. The highest temporal resolution of the technique is in the order of hundreds of nanoseconds. Therefore it is possible for the first time to observe the charge deposition process during an active discharge. On the time scale of the applied voltage period (several microseconds), the conservation mechanisms of a lateral discharge pattern is investigated. For this, the influence of surface charge and metastable species in the volume is estimated. Further, the behavior of the surface charge spots on a variation of the external voltage and gas pressure is studied. Measurements on a time scale in the magnitude of seconds reveal charge decay and transport phenomena. This work was funded by the Deutsche Forschungsgemeinschaft.
Improving the Geologic Time Scale (Jean Baptiste Lamarck Medal Lecture)
Gradstein, Felix M.
2010-05-01
The Geologic Time Scale (GTS) provides the framework for the physical, chemical and biological processes on Earth. The time scale is the tool "par excellence" of the geological trade, and insight in its construction, strength, and limitations enhances its function and its utility. Earth scientists should understand how time scales are constructed and its myriad of physical and abstract data are calibrated, rather than merely using ages plucked from a convenient chart or card. Calibration to linear time of the succession of events recorded in the rocks on Earth has three components: (1) the standard stratigraphic divisions and their correlation in the global rock record, (2) the means of measuring linear time or elapsed durations from the rock record, and (3) the methods of effectively joining the two scales, the stratigraphic one and the linear one. Under the auspices of the International Commission on Stratigraphy (ICS), the international stratigraphic divisions and their correlative events are now largely standardized, especially using the GSSP (Global Stratigraphic Section and Point) concept. The means of measuring linear time or elapsed durations from the rock record are objectives in the EARTH TIME and GTS NEXT projects, that also are educating a new generation of GTS dedicated scientists. The U/Pb, Ar/Ar and orbital tuning methods are intercalibrated, and external error analysis improved. Existing Ar/Ar ages become almost 0.5% older, and U/Pb ages stratigraphically more realistic. The new Os/Re method has potential for directly dating more GSSP's and its correlative events. Such may reduce scaling uncertainty between the sedimentary levels of an age date and that of a stage boundary. Since 1981, six successive Phanerozoic GTS have been published, each new one achieving higher resolution and more users. The next GTS is scheduled for 2011/2012, with over 50 specialists taking part. New chapters include an expanded planetary time scale, sequence stratigraphy
The Role of Time-Scales in Socio-hydrology
Blöschl, Günter; Sivapalan, Murugesu
2016-04-01
Much of the interest in hydrological modeling in the past decades revolved around resolving spatial variability. With the rapid changes brought about by human impacts on the hydrologic cycle, there is now an increasing need to refocus on time dependency. We present a co-evolutionary view of hydrologic systems, in which every part of the system including human systems, co-evolve, albeit at different rates. The resulting coupled human-nature system is framed as a dynamical system, characterized by interactions of fast and slow time scales and feedbacks between environmental and social processes. This gives rise to emergent phenomena such as the levee effect, adaptation to change and system collapse due to resource depletion. Changing human values play a key role in the emergence of these phenomena and should therefore be considered as internal to the system in a dynamic way. The co-evolutionary approach differs from the traditional view of water resource systems analysis as it allows for path dependence, multiple equilibria, lock-in situations and emergent phenomena. The approach may assist strategic water management for long time scales through facilitating stakeholder participation, exploring the possibility space of alternative futures, and helping to synthesise the observed dynamics of different case studies. Future research opportunities include the study of how changes in human values are connected to human-water interactions, historical analyses of trajectories of system co-evolution in individual places and comparative analyses of contrasting human-water systems in different climate and socio-economic settings. Reference Sivapalan, M. and G. Blöschl (2015) Time scale interactions and the coevolution of humans and water. Water Resour. Res., 51, 6988-7022, doi:10.1002/2015WR017896.
李迎楠; 刘文营; 张顺亮; 成晓瑜
2016-01-01
以牛骨为研究对象，通过中空纤维超滤装置、Sephadex G-25凝胶色谱柱对相对分子质量小于5000的酶解产物进行初步分离，选用制备型及分析型高效液相色谱分析仪对咸味肽进行纯化、收集及分析。结果表明：收集得到牛骨源咸味肽为单一组分；用基质辅助激光解析电离-飞行时间质谱仪对咸味肽进行分析，得到其为相对分子质量均小于1000的短肽，其呈现咸味的物质质荷比值可能为679.5109。%The enzymatic hydrolysate of bovine bone with relative molecular weight < 5 000 was separated by hollow fiber ultrafiltration and Sephadex G-25 column chromatography. Two salty peptide fractions from the hydrolysate were purified by preparative high performance liquid chromatography (HPLC) and the pooled samples were analyzed by HPLC. The two fractions were found to consist of a single homogenous component. As analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS), both peptide fractions had a relative molecular weight less than 1000, the salty taste compound of which was m/z 679.510 9.
The MOND limit from space-time scale invariance
Milgrom, Mordehai
2008-01-01
The MOND limit is shown to follow from a requirement of space-time scale invariance of the equations of motion for nonrelativistic, purely gravitational systems; i.e., invariance of the equations of motion under (t,r) goes to (qt,qr), in the limit a0 goes to infinity. It is suggested that this should replace the definition of the MOND limit based on the low-acceleration behavior of a Newtonian-MOND interpolating function. In this way, the salient, deep-MOND results--asymptotically flat rotati...
Brownian motion at fast time scales and thermal noise imaging
Huang, Rongxin
This dissertation presents experimental studies on Brownian motion at fast time scales, as well as our recent developments in Thermal Noise Imaging which uses thermal motions of microscopic particles for spatial imaging. As thermal motions become increasingly important in the studies of soft condensed matters, the study of Brownian motion is not only of fundamental scientific interest but also has practical applications. Optical tweezers with a fast position-sensitive detector provide high spatial and temporal resolution to study Brownian motion at fast time scales. A novel high bandwidth detector was developed with a temporal resolution of 30 ns and a spatial resolution of 1 A. With this high bandwidth detector, Brownian motion of a single particle confined in an optical trap was observed at the time scale of the ballistic regime. The hydrodynamic memory effect was fully studied with polystyrene particles of different sizes. We found that the mean square displacements of different sized polystyrene particles collapse into one master curve which is determined by the characteristic time scale of the fluid inertia effect. The particle's inertia effect was shown for particles of the same size but different densities. For the first time the velocity autocorrelation function for a single particle was shown. We found excellent agreement between our experiments and the hydrodynamic theories that take into account the fluid inertia effect. Brownian motion of a colloidal particle can be used to probe three-dimensional nano structures. This so-called thermal noise imaging (TNI) has been very successful in imaging polymer networks with a resolution of 10 nm. However, TNI is not efficient at micrometer scale scanning since a great portion of image acquisition time is wasted on large vacant volume within polymer networks. Therefore, we invented a method to improve the efficiency of large scale scanning by combining traditional point-to-point scanning to explore large vacant
Units of relativistic time scales and associated quantities
Klioner, S.; Capitaine, N.; Folkner, W.; Guinot, B.; Huang, T.-Y.; Kopeikin, S.; Pitjeva, E.; Seidelmann, P. K.; Soffel, M.
2009-01-01
This note suggests nomenclature for dealing with the units of various astronomical quantities that are used with the relativistic time scales TT, TDB, TCB and TCG. It is suggested to avoid wordings like "TDB units" and "TT units" and avoid contrasting them to "SI units". The quantities intended for use with TCG, TCB, TT or TDB should be called "TCG-compatible", "TCB-compatible", "TT-compatible" or "TDB-compatible", respectively. The names of the units second and meter for numerical values of ...
Units of relativistic time scales and associated quantities
Klioner, S; Folkner, W; Guinot, B; Huang, T -Y; Kopeikin, S; Pitjeva, E; Seidelmann, P K; Soffel, M
2009-01-01
This note suggests nomenclature for dealing with the units of various astronomical quantities that are used with the relativistic time scales TT, TDB, TCB and TCG. It is suggested to avoid wordings like "TDB units" and "TT units" and avoid contrasting them to "SI units". The quantities intended for use with TCG, TCB, TT or TDB should be called "TCG-compatible", "TCB-compatible", "TT-compatible" or "TDB-compatible", respectively. The names of the units second and meter for numerical values of all these quantities should be used with out any adjectives. This suggestion comes from a special discussion forum created within IAU Commission 52 "Relativity in Fundamental Astronomy".
Short time-scale variability in bright Seyfert galaxies
High-quality, long-slit CCD spectroscopic data were obtained to search for short time-scale (hour-day) variability in a sample of five Seyfert galaxies. The equivalent widths of all of the emission lines and the relative intensities of the Balmer lines were measured for each galaxy. No significant profile or flux variations were observed for any galaxy within errors, except for NGC 4151. The broad-line flux variation in NGC 4151 is attributed to continuum fluctuations. 21 refs
Short time-scale variability in bright Seyfert galaxies
Xanthopoulos, E.; De robertis, M.M. (York University, Toronto (Canada))
1991-04-01
High-quality, long-slit CCD spectroscopic data were obtained to search for short time-scale (hour-day) variability in a sample of five Seyfert galaxies. The equivalent widths of all of the emission lines and the relative intensities of the Balmer lines were measured for each galaxy. No significant profile or flux variations were observed for any galaxy within errors, except for NGC 4151. The broad-line flux variation in NGC 4151 is attributed to continuum fluctuations. 21 refs.
Isoperimetric problems on time scales with nabla derivatives
Almeida, Ricardo
2008-01-01
We prove a necessary optimality condition for isoperimetric problems under nabla-differentiable curves. As a consequence, the recent results of [M.R. Caputo, A unified view of ostensibly disparate isoperimetric variational problems, Appl. Math. Lett. (2008), doi:10.1016/j.aml.2008.04.004], that put together seemingly dissimilar optimal control problems in economics and physics, are extended to a generic time scale. We end with an illustrative example of application of our main result to a dynamic optimization problem from economics.
A Convergent Online Single Time Scale Actor Critic Algorithm
Di Castro, D
2009-01-01
Actor-Critic based approaches were among the first to address reinforcement learning in a general setting. Recently, these algorithms have gained renewed interest due to their generality, good convergence properties, and possible biological relevance. In this paper, we introduce an online temporal difference based actor-critic algorithm which is proved to converge to a neighborhood of a local maximum of the average reward. Linear function approximation is used by the critic in order estimate the value function, and the temporal difference signal, which is passed from the critic to the actor. The main distinguishing feature of the present convergence proof is that both the actor and the critic operate on a similar time scale, while in most current convergence proofs they are required to have very different time scales in order to converge. Moreover, the same temporal difference signal is used to update the parameters of both the actor and the critic. A limitation of the proposed approach, compared to results a...
The spur in pico-second time scales
The spur diffusion model of aqueous radiation chemistry, proposed in 1953, had run into difficulties with the development of pico-second pulse radiolysis in the late 1960s and early seventies. Using the same values for spur parameters, it was impossible to get good agreement with e-sub(aq) and OH decay in pico and nano second time scales as well as the steady state molecular product yield measurements. This inconsistency was removed by us by assuming that for a given number of dissociations, a number of radii values for the spur are possible, these radii values being related in a gaussian manner. This new approach proved highly successful in getting agreement between the predictions of the spur diffusion model and the pulse radiolysis results as well as the steady state molecular product yield measurements. Our computations have been extended to cover the entire range of spurs from a single dissociation spur to a thirty dissociation spur. Here again agreement with experimental results is good. This approach also gives interesting insights about the spur formation processes in pico and possibly femto second time scales. We have calculated rate constants for the reactions involving the 'precursor' of the hydrated electron with a number of ions. (author)
Careri, M; Costa, A; Elviri, L; Lagos, J-B; Mangia, A; Terenghi, M; Cereti, A; Garoffo, L Perono
2007-11-01
A liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS-MS) method based on the detection of biomarker peptides from allergenic proteins was devised for confirming and quantifying peanut allergens in foods. Peptides obtained from tryptic digestion of Ara h 2 and Ara h 3/4 proteins were identified and characterized by LC-MS and LC-MS-MS with a quadrupole-time of flight mass analyzer. Four peptides were chosen and investigated as biomarkers taking into account their selectivity, the absence of missed cleavages, the uniform distribution in the Ara h 2 and Ara h 3/4 protein isoforms together with their spectral features under ESI-MS-MS conditions, and good repeatability of LC retention time. Because of the different expression levels, the selection of two different allergenic proteins was proved to be useful in the identification and univocal confirmation of the presence of peanuts in foodstuffs. Using rice crisp and chocolate-based snacks as model food matrix, an LC-MS-MS method with triple quadrupole mass analyzer allowed good detection limits to be obtained for Ara h 2 (5 microg protein g(-1) matrix) and Ara h 3/4 (1 microg protein g(-1) matrix). Linearity of the method was established in the 10-200 microg g(-1) range of peanut proteins in the food matrix investigated. Method selectivity was demonstrated by analyzing tree nuts (almonds, pecan nuts, hazelnuts, walnuts) and food ingredients such as milk, soy beans, chocolate, cornflakes, and rice crisp. PMID:17899033
Optimal Control Modification for Time-Scale Separated Systems
Nguyen, Nhan T.
2012-01-01
Recently a new optimal control modification has been introduced that can achieve robust adaptation with a large adaptive gain without incurring high-frequency oscillations as with the standard model-reference adaptive control. This modification is based on an optimal control formulation to minimize the L2 norm of the tracking error. The optimal control modification adaptive law results in a stable adaptation in the presence of a large adaptive gain. This study examines the optimal control modification adaptive law in the context of a system with a time scale separation resulting from a fast plant with a slow actuator. A singular perturbation analysis is performed to derive a modification to the adaptive law by transforming the original system into a reduced-order system in slow time. A model matching conditions in the transformed time coordinate results in an increase in the actuator command that effectively compensate for the slow actuator dynamics. Simulations demonstrate effectiveness of the method.
Variation of atmospheric depth profile on different time scales
Wilczynska, B; Homola, P; Pekala, J; Risse, M; Wilczynski, H
2006-01-01
The vertical profile of atmospheric depth is an important element in extensive air shower studies. The depth of shower maximum is one of the most important characteristics of the shower. In the fluorescence technique of shower detection, the geometrical reconstruction provides the altitude of shower maximum, so that an accurate profile of atmospheric depth is needed to convert this altitude to the depth of shower maximum. In this paper the temporal variation of experimentally measured profiles of atmospheric depth at different sites is studied and implications for shower reconstruction are shown. The atmospheric profiles vary on time scales from hours to years. It is shown that the daily variation of the profile is as important as its seasonal variation and should be accounted for in air shower studies. For precise shower reconstruction, the daily profiles determined locally at the site of the air shower detector are recommended.
Units of relativistic time scales and associated quantities
Klioner, S. A.; Capitaine, N.; Folkner, W. M.; Guinot, B.; Huang, T.-Y.; Kopeikin, S. M.; Pitjeva, E. V.; Seidelmann, P. K.; Soffel, M. H.
2010-01-01
This note suggests nomenclature for dealing with the units of various astronomical quantities that are used with the relativistic time scales TT, TDB, TCB and TCG. It is suggested to avoid wordings like “TDB units” and “TT units” and avoid contrasting them to “SI units”. The quantities intended for use with TCG, TCB, TT or TDB should be called “TCG-compatible”, “TCB-compatible”, “TT-compatible” or “TDB-compatible”, respectively. The names of the units second and meter for numerical values of all these quantities should be used without any adjectives. This suggestion comes from a special discussion forum created within IAU Commission 52 “Relativity in Fundamental Astronomy”.
Shock response of iron on nanosecond time scales
Experiments were performed using direct laser irradiation to induce shock waves in pure Fe foils tens of microns thick, using surface velocimetry to measure the response. Compared with experiments on much thicker samples, relatively strong elastic precursors were observed, though these could be caused by the strong texture of the foils rather than the shorter time scale. There was also evidence for the onset of the bcc to hcp phase transition, starting close to the static phase boundary. Radiation hydrodynamics and continuum mechanical simulations were performed to interpret the velocity data, comparing several equations of state with polymorphism and strength. The data were consistent with a phase change rate of the order of 109/s, driven by superpressurization of about 5 GPa. The rate may also depend on texture
Levkin, Pavel A.; Eeltink, Sebastiaan; Stratton, Thomas R.; Brennen, Reid; Robotti, Karla; Yin, Hongfeng; Killeen, Kevin; Svec, Frantisek; Fréchet, Jean M.J.
2008-01-01
Poly(lauryl methacrylate-co-ethylene dimethacrylate) and poly(styrene-co-divinylbenzene) stationary phases in monolithic format have been prepared by thermally initiated free radical polymerization within polyimide chips featuring channels having a cross-section of 200×200 μm and a length of 6.8 cm. These chips were then used for the separation of a mixture of proteins including ribonuclease A, myoglobin, cytochrome c, and ovalbumin, as well as peptides. The separations were monitored by UV a...
Role of relaxation time scale in noisy signal transduction.
Maity, Alok Kumar; Chaudhury, Pinaki; Banik, Suman K
2015-01-01
Intra-cellular fluctuations, mainly triggered by gene expression, are an inevitable phenomenon observed in living cells. It influences generation of phenotypic diversity in genetically identical cells. Such variation of cellular components is beneficial in some contexts but detrimental in others. To quantify the fluctuations in a gene product, we undertake an analytical scheme for studying few naturally abundant linear as well as branched chain network motifs. We solve the Langevin equations associated with each motif under the purview of linear noise approximation and derive the expressions for Fano factor and mutual information in close analytical form. Both quantifiable expressions exclusively depend on the relaxation time (decay rate constant) and steady state population of the network components. We investigate the effect of relaxation time constraints on Fano factor and mutual information to indentify a time scale domain where a network can recognize the fluctuations associated with the input signal more reliably. We also show how input population affects both quantities. We extend our calculation to long chain linear motif and show that with increasing chain length, the Fano factor value increases but the mutual information processing capability decreases. In this type of motif, the intermediate components act as a noise filter that tune up input fluctuations and maintain optimum fluctuations in the output. For branched chain motifs, both quantities vary within a large scale due to their network architecture and facilitate survival of living system in diverse environmental conditions. PMID:25955500
Role of relaxation time scale in noisy signal transduction.
Alok Kumar Maity
Full Text Available Intra-cellular fluctuations, mainly triggered by gene expression, are an inevitable phenomenon observed in living cells. It influences generation of phenotypic diversity in genetically identical cells. Such variation of cellular components is beneficial in some contexts but detrimental in others. To quantify the fluctuations in a gene product, we undertake an analytical scheme for studying few naturally abundant linear as well as branched chain network motifs. We solve the Langevin equations associated with each motif under the purview of linear noise approximation and derive the expressions for Fano factor and mutual information in close analytical form. Both quantifiable expressions exclusively depend on the relaxation time (decay rate constant and steady state population of the network components. We investigate the effect of relaxation time constraints on Fano factor and mutual information to indentify a time scale domain where a network can recognize the fluctuations associated with the input signal more reliably. We also show how input population affects both quantities. We extend our calculation to long chain linear motif and show that with increasing chain length, the Fano factor value increases but the mutual information processing capability decreases. In this type of motif, the intermediate components act as a noise filter that tune up input fluctuations and maintain optimum fluctuations in the output. For branched chain motifs, both quantities vary within a large scale due to their network architecture and facilitate survival of living system in diverse environmental conditions.
The quenching time scale and quenching rate of galaxies
Lian, Jianhui; Zhang, Kai; Kong, Xu
2016-01-01
The average star formation rate (SFR) in galaxies has been declining since redshift of 2. A fraction of galaxies quench and become quiescent. We constrain two key properties of the quenching process: the quenching time scale and the quenching rate among galaxies. We achieve this by analyzing the galaxy number density profile in NUV-u color space and the distribution in NUV-u v.s. u-i color-color diagram with a simple toy-model framework. We focus on galaxies in three mass bins between 10 to 10 and 10 to 10.6 solar mass. In the NUV-u v.s. u-i color-color diagram, the red u-i galaxies exhibit a different slope from the slope traced by the star-forming galaxies. This angled distribution and the number density profile of galaxies in NUV-u space strongly suggest that the decline of the SFR in galaxies has to accelerate before they turn quiescent. We model this color-color distribution with a two-phase exponential decline star formation history. The models with an e-folding time in the second phase (the quenching p...
Forecasting decadal and shorter time-scale solar cycle features
Dikpati, Mausumi
2016-07-01
Solar energetic particles and magnetic fields reach the Earth through the interplanetary medium and affect it in various ways, producing beautiful aurorae, but also electrical blackouts and damage to our technology-dependent economy. The root of energetic solar outputs is the solar activity cycle, which is most likely caused by dynamo processes inside the Sun. It is a formidable task to accurately predict the amplitude, onset and peak timings of a solar cycle. After reviewing all solar cycle prediction methods, including empirical as well as physical model-based schemes, I will describe what we have learned from both validation and nonvalidation of cycle 24 forecasts, and how to refine the model-based schemes for upcoming cycle 25 forecasts. Recent observations indicate that within a solar cycle there are shorter time-scale 'space weather' features, such as bursts of various forms of activity with approximately one year periodicity. I will demonstrate how global tachocline dynamics could play a crucial role in producing such space weather. The National Center for Atmospheric Research is sponsored by the National Science Foundation.
Radionuclide time-scales and recent environmental changes
North America and European lakes have been used to monitor environmental changes such as land-use activities, acidification and chemical pollution specially heavy metals, halogenated organic substances and radioactive waste. In such studies radioactive dating using various combinations of low-level counting and spectrometry allows reconstruction of high resolution chronologies of recent sediments. Modelling recent environmental changes due to natural processes and man-made activities on regional and global scales and related consequences on the quality of aquatic life could be followed through systematic studies of lakes from different geographic and climatic regions. Isotope dilution alpha spectrometry using PIPS detectors, radon emanation using ionization chambers and sensitive Ge-gamma spectrometers are utilized to measure Pb-210,Ra-226, Cs-137,Cs-134, K-40 as well as other radionuclides. The mentioned nuclides are used to determine accumulation rates in protected lakes and to evaluate erosion from soils in connection with land-use activities. In such studies Pb-210 and Cs-137 fluxes give additional information on atmospheric and non-atmospheric inputs to lakes. The constructed time-scales (0 - 150 Yrs) allowed us to monitor the evolution of anthropogenic pollution and related loads in various regions. 1 tab.; 12 refs. (author)
Thermopeaking in alpine streams: event characterization and time scales
Zolezzi, Guido; Siviglia, Annunziato; Toffolon, Marco; Maiolini, Bruno
2010-05-01
The present study provides a detailed quantification of the "thermopeaking" phenomenon, which consists of sharp intermittent alterations of stream thermal regime associated with hydropeaking releases from hydroelectricity plants. The study refers to the Noce River (Northern Italy), a typical hydropower-regulated Alpine stream, where water stored in highaltitude reservoirs often has a different temperature compared to the receiving bodies. The analysis is based on a river water temperature dataset that has been continuously collected for one year at 30' intervals in four different sections along the Noce River. A suitable threshold-based procedure is developed to quantify the main characteristics of thermopeaking, which is responsible for thermal alterations at different scales. The application of Wavelet Transform allows to separately investigate thermal regime alterations at sub-daily, daily and weekly scales. Moreover, at a seasonal scale, patterns of "warm" and "cold" thermopeaking can be clearly detected and quantified. The study highlights the relevance of investigating a variety of short-term alterations at multiple time scales for a better quantitative understanding of the complexity that characterises the river thermal regime. The outcomes of the analysis raise important interdisciplinary research questions concerning the effects of thermopeaking and of the related short- and medium-term effects on biological communities, which have been rather poorly investigated in ecological studies.
Peptide Profile of Low-Fat Edam Cheese
Erdoğan KÜÇÜKÖNER
1998-01-01
Low-fat Edam cheese was manufactured using conventional cheese-making procedures using low-fat milk (1.5% fat). The cheese samples were aged for six months at 5 to 6°C. The cheese was analyzed for biochemical characteristics and peptide content. The peptide contents were determined with reverse phase chromatography. The association property of proteins and peptides in the soluble fraction of the cheese was determined using hydrophobic interaction chromatography. The overall peptide quantit...
Time scale of diffusion in molecular and cellular biology
Holcman, D.; Schuss, Z.
2014-05-01
Diffusion is the driver of critical biological processes in cellular and molecular biology. The diverse temporal scales of cellular function are determined by vastly diverse spatial scales in most biophysical processes. The latter are due, among others, to small binding sites inside or on the cell membrane or to narrow passages between large cellular compartments. The great disparity in scales is at the root of the difficulty in quantifying cell function from molecular dynamics and from simulations. The coarse-grained time scale of cellular function is determined from molecular diffusion by the mean first passage time of molecular Brownian motion to a small targets or through narrow passages. The narrow escape theory (NET) concerns this issue. The NET is ubiquitous in molecular and cellular biology and is manifested, among others, in chemical reactions, in the calculation of the effective diffusion coefficient of receptors diffusing on a neuronal cell membrane strewn with obstacles, in the quantification of the early steps of viral trafficking, in the regulation of diffusion between the mother and daughter cells during cell division, and many other cases. Brownian trajectories can represent the motion of a molecule, a protein, an ion in solution, a receptor in a cell or on its membrane, and many other biochemical processes. The small target can represent a binding site or an ionic channel, a hidden active site embedded in a complex protein structure, a receptor for a neurotransmitter on the membrane of a neuron, and so on. The mean time to attach to a receptor or activator determines diffusion fluxes that are key regulators of cell function. This review describes physical models of various subcellular microdomains, in which the NET coarse-grains the molecular scale to a higher cellular-level, thus clarifying the role of cell geometry in determining subcellular function.
Nonequilibrium Physics at Short Time Scales: Formation of Correlations
It is a happy situation when similar concepts and theoretical techniques can be applied to widely different physical systems because of a deep similarity in the situations being studied. The book illustrates this well; it focuses on the description of correlations in quantum systems out of equilibrium at very short time scales, prompted by experiments with short laser pulses in semiconductors, and in complex reactions in heavy nuclei. In both cases the experiments are characterized by nonlinear dynamics and by strong correlations out of equilibrium. In some systems there are also important finite-size effects. The book comprises several independent contributions of moderate length, and I sometimes felt that a more intensive effort in cross-coordination of the different contributions could have been of help. It is divided almost equally between theory and experiment. In the theoretical part, there is a thorough discussion both of the kinematic aspects (description of correlations) and the dynamical ones (evaluation of correlations). The experimental part is naturally divided according to the nature of the system: the interaction of pulsed lasers with matter on the one hand, and the correlations in finite-size systems (nanoparticles and nuclei) on the other. There is also a discussion on the dynamics of superconductors, a subject currently of great interest. Although an effort has been made to keep each contribution self-contained, I must admit that reading level is uneven. However, there are a number of thorough and stimulating contributions that make this book a useful introduction to the topic at the level of graduate students or researchers acquainted with quantum statistical mechanics. (book review)
Science at the Time-scale of the Electron
Murnane, Margaret
2010-03-01
Replace this text with your abstract Ever since the invention of the laser 50 years ago and its application in nonlinear optics, scientists have been striving to extend coherent laser beams into the x-ray region of the spectrum. Very recently however, the prospects for tabletop coherent sources, with attosecond pulse durations, at very short wavelengths even in the hard x-ray region of the spectrum at wavelengths advances are possible by taking nonlinear optics techniques to an extreme, and are the direct result of a new ability to manipulate electrons on the fastest, attosecond, time-scales of our natural world. My talk will discuss new experimental data that demonstrates high harmonic generation of laser-like, fully coherent, 10 attosecond duration, soft x-ray beams at photon energies around 0.5keV. Several applications will also be discussed, including making a movie of how electron orbitals in a molecule change shape as a molecule breaks apart, following how fast a magnetic material can flip orientation, understanding how fast heat flows in a nanocircuit, or building a microscope without lenses. [4pt] [1] T. Popmintchev et al., ``Phase matched upconversion of coherent ultrafast laser light into the soft and hard x-ray regions of the spectrum'', PNAS 106, 10516 (2009). [0pt] [2] C. LaOVorakiat et al., ``Ultrafast Soft X-Ray Magneto-Optics at the M-edge Using a Tabletop High-Harmonic Source'', Physical Review Letters 103, 257402 (2009). [0pt] [3] M. Siemens et al. ``Measurement of quasi-ballistic heat transport across nanoscale interfaces using ultrafast coherent soft x-ray beams'', Nature Materials 9, 26 (2010). [0pt] [4] K. Raines et al., ``Three-dimensional structure determination from a single view,'' Nature 463, 214 (2010). [0pt] [5] W. Li et al., ``Time-resolved Probing of Dynamics in Polyatomic Molecules using High Harmonic Generation'', Science 322, 1207 (2008).
The Time Scale of Recombination Rate Evolution in Great Apes.
Stevison, Laurie S; Woerner, August E; Kidd, Jeffrey M; Kelley, Joanna L; Veeramah, Krishna R; McManus, Kimberly F; Bustamante, Carlos D; Hammer, Michael F; Wall, Jeffrey D
2016-04-01
We present three linkage-disequilibrium (LD)-based recombination maps generated using whole-genome sequence data from 10 Nigerian chimpanzees, 13 bonobos, and 15 western gorillas, collected as part of the Great Ape Genome Project (Prado-Martinez J, et al. 2013. Great ape genetic diversity and population history. Nature 499:471-475). We also identified species-specific recombination hotspots in each group using a modified LDhot framework, which greatly improves statistical power to detect hotspots at varying strengths. We show that fewer hotspots are shared among chimpanzee subspecies than within human populations, further narrowing the time scale of complete hotspot turnover. Further, using species-specific PRDM9 sequences to predict potential binding sites (PBS), we show higher predicted PRDM9 binding in recombination hotspots as compared to matched cold spot regions in multiple great ape species, including at least one chimpanzee subspecies. We found that correlations between broad-scale recombination rates decline more rapidly than nucleotide divergence between species. We also compared the skew of recombination rates at centromeres and telomeres between species and show a skew from chromosome means extending as far as 10-15 Mb from chromosome ends. Further, we examined broad-scale recombination rate changes near a translocation in gorillas and found minimal differences as compared to other great ape species perhaps because the coordinates relative to the chromosome ends were unaffected. Finally, on the basis of multiple linear regression analysis, we found that various correlates of recombination rate persist throughout the African great apes including repeats, diversity, and divergence. Our study is the first to analyze within- and between-species genome-wide recombination rate variation in several close relatives. PMID:26671457
Two-phase micro- and macro-time scales in particle-laden turbulent channel flows
Bing Wang; Michael Manhart
2012-01-01
The micro- and macro-time scales in two-phase turbulent channel flows are investigated using the direct numerical simulation and the Lagrangian particle trajectory methods for the fluid- and the particle-phases,respectively.Lagrangian and Eulerian time scales of both phases are calculated using velocity correlation functions.Due to flow anisotropy,micro-time scales are not the same with the theoretical estimations in large Reynolds number (isotropic) turbulence.Lagrangian macro-time scales of particle-phase and of fluid-phase seen by particles are both dependent on particle Stokes number.The fluid-phase Lagrangian integral time scales increase with distance from the wall,longer than those time scales seen by particles.The Eulerian integral macro-time scales increase in near-wall regions but decrease in out-layer regions.The moving Eulerian time scales are also investigated and compared with Lagrangian integral time scales,and in good agreement with previous measurements and numerical predictions.For the fluid particles the micro Eulerian time scales are longer than the Lagrangian ones in the near wall regions,while away from the walls the micro Lagrangian time scales are longer.The Lagrangian integral time scales are longer than the Eulerian ones.The results are useful for further understanding two-phase flow physics and especially for constructing accurate prediction models of inertial particle dispersion.
Geissman, J. W.
2013-12-01
We celebrate the 50th anniversary of the publication of the Vine-Matthews/Morley-Larochelle hypothesis (Vine and Matthews, Nature, 1963, v. 199, #4897, p. 947-949), which integrated marine magnetic anomaly data with a rapidly evolving terrestrial-based geomagnetic polarity time scale (GPTS). The five decades of research since 1963 have witnessed the expansion and refinement of the GPTS, to the point where ages of magnetochron boundaries, in particular in the Cenozoic, can be estimated with uncertainties better than 0.1%. This has come about by integrating high precision geochronology, cyclostratigraphy at different time scales, and magnetic polarity data of increased quality, allowing extension of the GPTS back into the Paleozoic. The definition of a high resolution GPTS across time intervals of major events in Earth history has been of particular interest, as a specific magnetochron boundary correlated across several localities represents a singular global datum. A prime example is the end Permian, when some 80 percent of genus-level extinctions and a range of 75 to 96 percent species- level extinctions took place in the marine environment, depending upon clade. Much our understanding of the Permian-Triassic boundary (PTB) is based on relatively slowly deposited marine sequences in Europe and Asia, yet a growing body of observations from continental sequences demonstrates a similar extinction event and new polarity data from some of these sequences are critical to refining the GPTS across the PTB and testing synchronicity of marine and terrestrial events. The data show that the end-Permian ecological crisis and the conodont calibrated biostratigraphic PTB both followed a key polarity reversal between a short interval (subchron) of reverse polarity to a considerably longer (chron) of normal polarity. Central European Basin strata (continental Permian and epicontinental Triassic) yield high-quality magnetic polarity stratigraphic records (Szurlies et al., 2003
Input-output description of linear systems with multiple time-scales
Madriz, R. S.; Sastry, S. S.
1984-01-01
It is pointed out that the study of systems evolving at multiple time-scales is simplified by studying reduced-order models of these systems valid at specific time-scales. The present investigation is concerned with an extension of results on the time-scale decomposition of autonomous systems to that of input-output systems. The results are employed to study conditions under which positive realness of a transfer function is preserved under singular perturbation. Attention is given to the perturbation theory for linear operators, the multiple time-scale structure of autonomous linear systems, the input-output description of two time-scale linear systems, the positive realness of two time-scale systems, and multiple time-scale linear systems.
Mistarz, Ulrik H; Brown, Jeffery M; Haselmann, Kim F; Rand, Kasper D
2014-12-01
Gas-phase hydrogen/deuterium exchange (HDX) is a fast and sensitive, yet unharnessed analytical approach for providing information on the structural properties of biomolecules, in a complementary manner to mass analysis. Here, we describe a simple setup for ND3-mediated millisecond gas-phase HDX inside a mass spectrometer immediately after ESI (gas-phase HDX-MS) and show utility for studying the primary and higher-order structure of peptides and proteins. HDX was achieved by passing N2-gas through a container filled with aqueous deuterated ammonia reagent (ND3/D2O) and admitting the saturated gas immediately upstream or downstream of the primary skimmer cone. The approach was implemented on three commercially available mass spectrometers and required no or minor fully reversible reconfiguration of gas-inlets of the ion source. Results from gas-phase HDX-MS of peptides using the aqueous ND3/D2O as HDX reagent indicate that labeling is facilitated exclusively through gaseous ND3, yielding similar results to the infusion of purified ND3-gas, while circumventing the complications associated with the use of hazardous purified gases. Comparison of the solution-phase- and gas-phase deuterium uptake of Leu-Enkephalin and Glu-Fibrinopeptide B, confirmed that this gas-phase HDX-MS approach allows for labeling of sites (heteroatom-bound non-amide hydrogens located on side-chains, N-terminus and C-terminus) not accessed by classical solution-phase HDX-MS. The simple setup is compatible with liquid chromatography and a chip-based automated nanoESI interface, allowing for online gas-phase HDX-MS analysis of peptides and proteins separated on a liquid chromatographic time scale at increased throughput. Furthermore, online gas-phase HDX-MS could be performed in tandem with ion mobility separation or electron transfer dissociation, thus enabling multiple orthogonal analyses of the structural properties of peptides and proteins in a single automated LC-MS workflow. PMID:25375223
Wohlmuth, Johannes; Andersen, Jørgen Vitting
2006-05-01
We use agent-based models to study the competition among investors who use trading strategies with different amount of information and with different time scales. We find that mixing agents that trade on the same time scale but with different amount of information has a stabilizing impact on the large and extreme fluctuations of the market. Traders with the most information are found to be more likely to arbitrage traders who use less information in the decision making. On the other hand, introducing investors who act on two different time scales has a destabilizing effect on the large and extreme price movements, increasing the volatility of the market. Closeness in time scale used in the decision making is found to facilitate the creation of local trends. The larger the overlap in commonly shared information the more the traders in a mixed system with different time scales are found to profit from the presence of traders acting at another time scale than themselves.
Structure and dating errors in the geologic time scale and periodicity in mass extinctions
Stothers, Richard B.
1989-01-01
Structure in the geologic time scale reflects a partly paleontological origin. As a result, ages of Cenozoic and Mesozoic stage boundaries exhibit a weak 28-Myr periodicity that is similar to the strong 26-Myr periodicity detected in mass extinctions of marine life by Raup and Sepkoski. Radiometric dating errors in the geologic time scale, to which the mass extinctions are stratigraphically tied, do not necessarily lessen the likelihood of a significant periodicity in mass extinctions, but do spread the acceptable values of the period over the range 25-27 Myr for the Harland et al. time scale or 25-30 Myr for the DNAG time scale. If the Odin time scale is adopted, acceptable periods fall between 24 and 33 Myr, but are not robust against dating errors. Some indirect evidence from independently-dated flood-basalt volcanic horizons tends to favor the Odin time scale.
Almost Periodic Solutions for Neutral-Type BAM Neural Networks with Delays on Time Scales
Yongkun Li; Li Yang
2013-01-01
Using the existence of the exponential dichotomy of linear dynamic equations on time scales, a fixed point theorem and the theory of calculus on time scales, we obtain some sufficient conditions for the existence and exponential stability of almost periodic solutions for a class of neutral-type BAM neural networks with delays on time scales. Finally, a numerical example illustrates the feasibility of our results and also shows that the continuous-time neural network and its dis...
Hamilton-Jacobi-Bellman equations and approximate dynamic programming on time scales.
Seiffertt, John; Sanyal, Suman; Wunsch, Donald C
2008-08-01
The time scales calculus is a key emerging area of mathematics due to its potential use in a wide variety of multidisciplinary applications. We extend this calculus to approximate dynamic programming (ADP). The core backward induction algorithm of dynamic programming is extended from its traditional discrete case to all isolated time scales. Hamilton-Jacobi-Bellman equations, the solution of which is the fundamental problem in the field of dynamic programming, are motivated and proven on time scales. By drawing together the calculus of time scales and the applied area of stochastic control via ADP, we have connected two major fields of research. PMID:18632378
Implementation of Time-Scale Transformation Based on Continuous Wavelet Theory
无
2000-01-01
The basic objective of time-scale transformation is to compress or expand the signal in time field while keeping the same spectral properties.This paper presents two methods to derive time-scale transformation formula based on continuous wavelet transform.For an arbitrary given square-integrable function f(t),g(t) = f(t/λ) is derived by continuous wavelet transform and its inverse transform.The result shows that time-scale transformation may be obtained through the modification of the time-scale of wavelet function filter using equivalent substitution. The paper demonstrates the result by theoretic derivations and experimental simulation.
Pseudospherical surfaces on time scales: a geometric definition and the spectral approach
Cieslinski, Jan L [Uniwersytet w Bialymstoku, Wydzial Fizyki, ul Lipowa 41, 15-424 Bialystok (Poland)
2007-10-19
We define and discuss the notion of pseudospherical surfaces in asymptotic coordinates on time scales. Thus we extend well-known notions of discrete pseudospherical surfaces and smooth pseudosperical surfaces on more exotic domains (e.g., the Cantor set). In particular, we present a new expression for the discrete Gaussian curvature which turns out to be valid for asymptotic nets on any time scale. We show that asymptotic Chebyshev nets on an arbitrary time scale have constant negative Gaussian curvature. We present also the quaternion-valued spectral problem (the Lax pair) and the Darboux-Baecklund transformation for pseudospherical surfaces (in asymptotic coordinates) on arbitrary time scales.
Karasek, Francis W.; And Others
1984-01-01
This review covers fundamental developments in gas chromatography during 1982 and 1983. Literature is considered under these headings: columns; liguid phases; solid supports; sorption processes and solvents; open tubular column gas chromatography; instrumentation; high-resolution columns and applications; other techniques; qualitative and…
Quantifying the uncertainty of the annular mode time scale and the role of the stratosphere
Kim, Junsu; Reichler, Thomas
2015-10-01
The proper simulation of the annular mode time scale may be regarded as an important benchmark for climate models. Previous research demonstrated that this time scale is systematically overestimated by climate models. As suggested by the fluctuation-dissipation theorem, this may imply that climate models are overly sensitive to external forcings. Previous research also made it clear that calculating the AM time scale is a slowly converging process, necessitating relatively long time series and casting doubts on the usefulness of the historical reanalysis record to constrain climate models in terms of the annular mode time scale. Here, we use long control simulations with the coupled and uncoupled version of the GFDL climate model, CM2.1 and AM2.1, respectively, to study the effects of internal atmospheric variability and forcing from the lower boundary on the stability of the annular mode time scale. In particular, we ask whether a model's annular mode time scale and dynamical sensitivity can be constrained from the 50-year-long reanalysis record. We find that internal variability attaches large uncertainty to the annular mode time scale when diagnosed from decadal records. Even under the fixed forcing conditions of our long control run at least 100 years of data are required in order to keep the uncertainty in the annular mode time scale of the Northern Hemisphere to 10 %; over the Southern Hemisphere, the required length increases to 200 years. If nature's annular mode time scale over the Northern Hemisphere is similarly variable, there is no guarantee that the historical reanalysis record is a fully representative target for model evaluation. Over the Southern Hemisphere, however, the discrepancies between model and reanalysis are sufficiently large to conclude that the model is unable to reproduce the observed time scale structure correctly. The effects of ocean coupling lead to a considerable increase in time scale and uncertainty in time scale, effects which
Error estimates for asymptotic solutions of dynamic equations on time scales
Gro Hovhannisyan
2007-02-01
Full Text Available We establish error estimates for first-order linear systems of equations and linear second-order dynamic equations on time scales by using calculus on a time scales [1,4,5] and Birkhoff-Levinson's method of asymptotic solutions [3,6,8,9].
Necessary optimality conditions for the calculus of variations on time scales
Ferreira, Rui A. C.; Torres, Delfim F. M.
2007-01-01
We study more general variational problems on time scales. Previous results are generalized by proving necessary optimality conditions for (i) variational problems involving delta derivatives of more than the first order, and (ii) problems of the calculus of variations with delta-differential side conditions (Lagrange problem of the calculus of variations on time scales).
Some inequalities of Ostrowski and Grüss type for triple integrals on time scales
Nazir Ahmad Mir
2011-12-01
Full Text Available In this paper, we establish some inequalities of Ostrowski and Grüss type for triple integrals on arbitrary time scales involving three functions and their partial derivatives. We also discuss the discrete Ostrowski and Grüss type inequalities for triple sumon time scale.
Some inequalities of Ostrowski and Grüss type for triple integrals on time scales
Nazir Ahmad Mir; Roman Ullah
2011-01-01
In this paper, we establish some inequalities of Ostrowski and Grüss type for triple integrals on arbitrary time scales involving three functions and their partial derivatives. We also discuss the discrete Ostrowski and Grüss type inequalities for triple sumon time scale.
The Delta-nabla Calculus of Variations for Composition Functionals on Time Scales
Dryl, Monika; Torres, Delfim F. M.
2012-01-01
We develop the calculus of variations on time scales for a functional that is the composition of a certain scalar function with the delta and nabla integrals of a vector valued field. Euler-Lagrange equations, transversality conditions, and necessary optimality conditions for isoperimetric problems, on an arbitrary time scale, are proved. Interesting corollaries and examples are presented.
Time scales of spike-train correlation for neural oscillators with common drive
We examine the effect of the phase-resetting curve on the transfer of correlated input signals into correlated output spikes in a class of neural models receiving noisy superthreshold stimulation. We use linear-response theory to approximate the spike correlation coefficient in terms of moments of the associated exit time problem and contrast the results for type I vs type II models and across the different time scales over which spike correlations can be assessed. We find that, on long time scales, type I oscillators transfer correlations much more efficiently than type II oscillators. On short time scales this trend reverses, with the relative efficiency switching at a time scale that depends on the mean and standard deviation of input currents. This switch occurs over time scales that could be exploited by downstream circuits.
Global and Local Color Time Scales to Encode Timeline Events in Ion Trajectories for Glassies
J. M. Sharif
2015-02-01
Full Text Available Glassy compounds lead directly to high ionic conductivity. Ionic conductivity generates ion trajectories. However, these trajectories have been represented by two-dimensional graph in order to visualize the timeline events in ion trajectories. This study addresses this problem by encoding the timeline events in ion trajectories with global and local color scales. Two time scales have been introduced namely Global Color Time Scale and Local Color Time Scale. The rainbow color has been chosen to represent global time scale meanwhile solid color has been used to generate local time scale. Based on evaluation, these techniques are successful in representing timeline events in ion trajectories for understanding the complicated heterogeneous movement of ion trajectories.
Niederhafner, Petr; Šebestík, Jaroslav; Ježek, Jan
2005-01-01
Roč. 11, - (2005), 757-788. ISSN 1075-2617 R&D Projects: GA ČR(CZ) GA203/03/1362 Institutional research plan: CEZ:AV0Z40550506 Keywords : multiple antigen peptides * peptide dendrimers * synthetic vaccine * multipleantigenic peptides Subject RIV: CC - Organic Chemistry Impact factor: 1.803, year: 2005
Fei Yu
2009-01-01
Full Text Available Based on the theory of calculus on time scales, the homeomorphism theory, Lyapunov functional method, and some analysis techniques, sufficient conditions are obtained for the existence, uniqueness, and global exponential stability of the equilibrium point of Cohen-Grossberg bidirectional associative memory (BAM neural networks with distributed delays and impulses on time scales. This is the first time applying the time-scale calculus theory to unify the discrete-time and continuous-time Cohen-Grossberg BAM neural network with impulses under the same framework.
Invited Review Article: The statistical modeling of atomic clocks and the design of time scales
I will show how the statistical models that are used to describe the performance of atomic clocks are derived from their internal design. These statistical models form the basis for time scales, which are used to define international time scales such as International Atomic Time and Coordinated Universal Time. These international time scales are realized by ensembles of clocks at national laboratories such as the National Institute of Standards and Technology, and I will describe how ensembles of atomic clocks are characterized and managed.
A wavelet based approach to measure and manage contagion at different time scales
Berger, Theo
2015-10-01
We decompose financial return series of US stocks into different time scales with respect to different market regimes. First, we examine dependence structure of decomposed financial return series and analyze the impact of the current financial crisis on contagion and changing interdependencies as well as upper and lower tail dependence for different time scales. Second, we demonstrate to which extent the information of different time scales can be used in the context of portfolio management. As a result, minimizing the variance of short-run noise outperforms a portfolio that minimizes the variance of the return series.
Multi-time scale analysis of precipitation variation in Guyuan,China:1957-2005
无
2008-01-01
Morlet wavelet transformation is used in this paper to analyze the multi-time scale characteristics of precipitation data series from 1957 to 2005 in Guyuan region.The results showed that (1) the annual precipitation evolution process had obvious multi-time scale variation characteristics of 15-25 years,7-12 years and 3-6 years,and different time scales had different oscillation energy densities;(2) the periods at smaller time scales changed more frequently,which often nested in a biggish quasi periodic oscillations,so the concrete time domain should be analyzed if necessary;(3) the precipitation had three main periods (22-year,9-year and 4-year) and the 22-year period was especially outstanding,and the analysis of this main period reveals that the precipitation would be in a relative high water period until about 2012.
无
2006-01-01
In this paper, using the theory of topological degree and Liapunov functional methods, the authors study the competitive neural networks with time delays and different time scales and present some criteria of global robust stability for this neural network model.
OSCILLATION CRITERIA FOR A FOURTH ORDER SUBLINEAR DYNAMIC EQUATION ON TIME SCALE
无
2011-01-01
Some new criteria for the oscillation of a fourth order sublinear and/or linear dynamic equation on time scale are established. Our results are new for the corresponding fourth order differential equations as well as difference equations.
The actor-critic algorithm as multi-time-scale stochastic approximation
Borkar, Vivek S.; Konda, Vijaymohan R
1997-01-01
The actor-critic algorithm of Barto and others for simulation-based optimization of Markov decision processes is cast as a two time Scale stochastic approximation. Convergence analysis, approximation issues and an example are studied.
Existence Results for Higher-Order Boundary Value Problems on Time Scales
Sang Yanbin; Liu Jian
2009-01-01
By using the fixed-point index theorem, we consider the existence of positive solutions for the following nonlinear higher-order four-point singular boundary value problem on time scales , ; , ; , ; , , where , , , , , , , and is rd-continuous.
Zhao Ya-Hong
2010-01-01
Full Text Available We investigate the following nonlinear first-order periodic boundary value problem on time scales: , , . Some new existence criteria of positive solutions are established by using the monotone iterative technique.
Monotone Iterative Technique for Partial Dynamic Equations of First Order on Time Scales
Peiguang Wang
2008-01-01
Full Text Available This work is concerned with the monotone iterative technique for partial dynamic equations of first order on time scales and for this purpose, the existence, uniqueness, and comparison results are also established.
Y. Kawada
2007-10-01
Full Text Available We investigate the time-scale invariant changes in electromagnetic and mechanical energy releases prior to a rock failure or a large earthquake. The energy release processes are caused by damage evolutions such as crack propagation, motion of charged dislocation, area-enlargement of sheared asperities and repetitive creep-rate changes. Damage mechanics can be used to represent the time-scale invariant evolutions of both brittle and plastic damages. Irreversible thermodynamics applied to the damage mechanics reveals that the damage evolution produces the variations in charge, dipole and electromagnetic signals in addition to mechanical energy release, and yields the time-scale invariant patterns of Benioff electromagnetic radiation and cumulative Benioff strain-release. The irreversible thermodynamic framework of damage mechanics is also applicable to the seismo-magnetic effect, and the time-scale invariance is recognized in the remanent magnetization change associated with damage evolution prior to a rock failure.
LI Hong; L(U) Shu; ZHONG Shou-ming
2005-01-01
The global uniform asymptotic stability of competitive neural networks with different time scales and delay is investigated. By the method of variation of parameters and the method of inequality analysis, the condition for global uniformly asymptotically stable are given. A strict Lyapunov function for the flow of a competitive neural system with different time scales and delay is presented. Based on the function, the global uniform asymptotic stability of the equilibrium point can be proved.
Chaos control of single time-scale brushless DC motor with sliding mode control method
Uyaroğlu, Yılmaz; CEVHER, Barış
2013-01-01
In this paper, the sliding mode control (SMC) scheme of single time-scale brushless DC motor (BLDCM) is investigated. The SMC method consists of 2 sections. To simplify the directive of the stability of the controlled single time-scale BLDCM in the sliding mode, first a special type of PI switching surface is adopted. Second, the SMC controller is obtained to guarantee the occurrence of the PI switching surface. The effectiveness of the theoretical analysis is evaluated by numerical...
Interplay between multiple length and time scales in complex chemical systems
Bagchi, Biman; Chakravarty, Charusita
2010-01-01
Processes in complex chemical systems, such as macromolecules, electrolytes, interfaces, micelles and enzymes, can span several orders of magnitude in length and time scales. The length and time scales of processes occurring over this broad time and space window are frequently coupled to give rise to the control necessary to ensure specificity and the uniqueness of the chemical phenomena. A combination of experimental, theoretical and computational techniques that can address a multiplicity o...
Mulik, James D.; Sawicki, Eugene
1979-01-01
Accurate for the analysis of ions in solution, this form of analysis enables the analyst to directly assay many compounds that previously were difficult or impossible to analyze. The method is a combination of the methodologies of ion exchange, liquid chromatography, and conductimetric determination with eluant suppression. (Author/RE)
Increasing temperature forcing reduces the Greenland Ice Sheet's response time scale
Applegate, Patrick J.; Parizek, Byron R.; Nicholas, Robert E.; Alley, Richard B.; Keller, Klaus
2015-10-01
Damages from sea level rise, as well as strategies to manage the associated risk, hinge critically on the time scale and eventual magnitude of sea level rise. Satellite observations and paleo-data suggest that the Greenland Ice Sheet (GIS) loses mass in response to increased temperatures, and may thus contribute substantially to sea level rise as anthropogenic climate change progresses. The time scale of GIS mass loss and sea level rise are deeply uncertain, and are often assumed to be constant. However, previous ice sheet modeling studies have shown that the time scale of GIS response likely decreases strongly with increasing temperature anomaly. Here, we map the relationship between temperature anomaly and the time scale of GIS response, by perturbing a calibrated, three-dimensional model of GIS behavior. Additional simulations with a profile, higher-order, ice sheet model yield time scales that are broadly consistent with those obtained using the three-dimensional model, and shed light on the feedbacks in the ice sheet system that cause the time scale shortening. Semi-empirical modeling studies that assume a constant time scale of sea level adjustment, and are calibrated to small preanthropogenic temperature and sea level changes, may underestimate future sea level rise. Our analysis suggests that the benefits of reducing greenhouse gas emissions, in terms of avoided sea level rise from the GIS, may be greatest if emissions reductions begin before large temperature increases have been realized. Reducing anthropogenic climate change may also allow more time for design and deployment of risk management strategies by slowing sea level contributions from the GIS.
Time-scales of close-in exoplanet radio emission variability
See, V; Fares, R; Donati, J -F; Moutou, C
2015-01-01
We investigate the variability of exoplanetary radio emission using stellar magnetic maps and 3D field extrapolation techniques. We use a sample of hot Jupiter hosting stars, focusing on the HD 179949, HD 189733 and tau Boo systems. Our results indicate two time-scales over which radio emission variability may occur at magnetised hot Jupiters. The first is the synodic period of the star-planet system. The origin of variability on this time-scale is the relative motion between the planet and the interplanetary plasma that is co-rotating with the host star. The second time-scale is the length of the magnetic cycle. Variability on this time-scale is caused by evolution of the stellar field. At these systems, the magnitude of planetary radio emission is anticorrelated with the angular separation between the subplanetary point and the nearest magnetic pole. For the special case of tau Boo b, whose orbital period is tidally locked to the rotation period of its host star, variability only occurs on the time-scale of...
A Study on Time-Scales Ratio and Turbulent Prandtl Number in Ducts of Industrial Applications
Rokni, Masoud
2006-01-01
This investigation concerns numerical time-scales ratio and turbulent Prandtl number in fully developed turbulent ﬂows in ducts of various cross-sections. The low Reynolds number version of a non-linear eddy viscosity model is proposed to predict the Reynolds stresses and the temperature ﬁeld is...... solved using a two-equation heat ﬂux model. The computed results compare satisfactory with the available experimental data. The time-scale ratio R is deﬁned as the ratio between the dynamic time-scale (k/ε) and the scalar time-scale(0.5θθ/εθ). Based on existing DNS data and calculations in this work the...... ratio between the time-scales is found to be approximately 0.7. In light of this assumption an expression for the turbulent diffusivity is considered and the turbulent Prandtl number variation across the duct is studied. This study can also be regarded as engineering calculation methodic for ducts of...
Multi-Wavelength Study of Sgr A*: The Short Time Scale Variability
Yusef-Zadeh, F; Roberts, D; Wardle, M; Reid, M; Dodds-Eden, K; Porquet, D; Grosso, N
2010-01-01
To understand the correlation and the radiation mechanism of flare emission in different wavelength bands, we have coordinated a number of telescopes to observe SgrA* simultaneously. We focus only on one aspect of the preliminary results of our multi-wavelength observing campaigns, namely, the short time scale variability of emission from SgrA* in near-IR, X-ray and radio wavelengths. The structure function analysis indicate most of the power spectral density is detected on hourly time scales in all wavelength bands. We also report minute time scale variability at 7 and 13mm placing a strong constraint on the nature of the variable emission. The hourly time scale variability can be explained in the context of a model in which the peak frequency of emission shifts toward lower frequencies as a self-absorbed synchrotron source expands adiabatically near the acceleration site. The short time scale variability, on the other hand, places a strong constraint on the size of the emitting region. Assuming that rapid m...
New time-scale criteria for model simplification of bio-reaction systems
Lee Sang
2008-08-01
Full Text Available Abstract Background Quasi-steady state approximation (QSSA based on time-scale analysis is known to be an effective method for simplifying metabolic reaction system, but the conventional analysis becomes time-consuming and tedious when the system is large. Although there are automatic methods, they are based on eigenvalue calculations of the Jacobian matrix and on linear transformations, which have a high computation cost. A more efficient estimation approach is necessary for complex systems. Results This work derived new time-scale factor by focusing on the problem structure. By mathematically reasoning the balancing behavior of fast species, new time-scale criteria were derived with a simple expression that uses the Jacobian matrix directly. The algorithm requires no linear transformation or decomposition of the Jacobian matrix, which has been an essential part for previous automatic time-scaling methods. Furthermore, the proposed scale factor is estimated locally. Therefore, an iterative procedure was also developed to find the possible multiple boundary layers and to derive an appropriate reduced model. Conclusion By successive calculation of the newly derived time-scale criteria, it was possible to detect multiple boundary layers of full ordinary differential equation (ODE models. Besides, the iterative procedure could derive the appropriate reduced differential algebraic equation (DAE model with consistent initial values, which was tested with simple examples and a practical example.
Interplay between multiple length and time scales in complex chemical systems
Biman Bagchi; Charusita Chakravarty
2010-07-01
Processes in complex chemical systems, such as macromolecules, electrolytes, interfaces, micelles and enzymes, can span several orders of magnitude in length and time scales. The length and time scales of processes occurring over this broad time and space window are frequently coupled to give rise to the control necessary to ensure specificity and the uniqueness of the chemical phenomena. A combination of experimental, theoretical and computational techniques that can address a multiplicity of length and time scales is required in order to understand and predict structure and dynamics in such complex systems. This review highlights recent experimental developments that allow one to probe structure and dynamics at increasingly smaller length and time scales. The key theoretical approaches and computational strategies for integrating information across time-scales are discussed. The application of these ideas to understand phenomena in various areas, ranging from materials science to biology, is illustrated in the context of current developments in the areas of liquids and solvation, protein folding and aggregation and phase transitions, nucleation and self-assembly.
Micro- and nanosecond time scale, high power electrical wire explosion in water
Full Text: Experimental and magneto-hydro-dynamic simulation results of micro- and nanosecond time scale underwater electrical Al, Cu and W wires explosions are presented. A capacitor bank with stored energy up to 6 kJ was used in microsecond time scale experiments and water forming line generator with current amplitude up to 100 k A and pulse duration of 100 ns were used in nanosecond time scale experiments. Extremely high energy deposition of up to 60 times the atomization enthalpy was registered in nanosecond time scale explosions. A discharge channel evolution and surface temperature were analyzed by streak shadow imaging and using fast photo-diode with a set of interference filters, respectively. Microsecond time scale electrical explosion of cylindrical wire array showed extremely high pressure of converging shock waves at the axis, up to 0.2 Mbar. A 1D and 2D magneto hydro- dynamic simulation demonstrated good agreement with such experimental parameters as discharge channel current, voltage, radius, and temperature
Micro- and nano- second time scale, high power electrical wire explosions in water.
Grinenko, Alon; Efimov, Sergey; Sayapin, Arkadii; Fedotov, Alexander; Gurovich, Viktor; Krasik, Yakov
2006-10-01
Experimental and magneto-hydro-dynamic simulation results of micro- and nanosecond time scale underwater electrical Al, Cu and W wires explosions are presented. A capacitor bank with stored energy up to 6 kJ (discharge current up to 80 kA with 2.5 μs quarter period) was used in microsecond time scale experiments and water forming line generator with current amplitude up to 100 kA and pulse duration of 100 ns were used in nanosecond time scale experiments. Extremely high energy deposition of up to 60 times the atomization enthalpy was registered in nanosecond time scale explosions. A discharge channel evolution and surface temperature were analyzed by streak shadow imaging and using fast photo-diode with a set of interference filters, respectively. Microsecond time scale electrical explosion of cylindrical wire array showed extremely high pressure of converging shock waves at the axis, up to 0.2 MBar. A 1D and 2D magneto-hydro-dynamic simulation demonstrated good agreement with such experimental parameters as discharge channel current, voltage, radius, and temperature.
Woutersen, Sander; Mu, Yuguang; Stock, Gerhard; Hamm, Peter
2001-09-01
The observation of subpicosecond fluctuations in the conformation of a small peptide in water is demonstrated. We use an experimental method that is specifically sensitive to conformational dynamics taking place on an ultrafast time scale. Complementary molecular-dynamics simulations confirm that the conformational fluctuations exhibit a subpicosecond component, the time scale and amplitude of which agree well with those derived from the experiment.
Phosphopeptide elution times in reversed-phase liquid chromatography
Kim, Jeongkwon; Petritis, Konstantinos; Shen, Yufeng; Camp, David G.; Moore, Ronald J.; Smith, Richard D.
2007-01-01
Elution time shifts between 33 different peptides and their corresponding phosphopeptides ranging from 4 amino acid residues to 35 amino acids in length were systematically investigated using high-resolution reversed-phase liquid chromatography (RPLC)-tandem mass spectrometry (MS/MS) analysis with trifluoroacetic acid as the ion pairing agent. Observed peptide elution time shifts for a single phosphorylation ranged from −5.28 min (for pYVPML) to +0.59 min (for HRDpSGLLDSLGR). Peptides contain...
Analytical biotechnology: Capillary electrophoresis and chromatography
The papers describe the separation, characterization, and equipment required for the electrophoresis or chromatography of cyclic nucleotides, pharmaceuticals, therapeutic proteins, recombinant DNA products, pheromones, peptides, and other biological materials. One paper, On-column radioisotope detection for capillary electrophoresis, has been indexed separately for inclusion on the data base
Tarter, J.G.
1987-01-01
Similar in many ways to other liquid chromatographic techniques, ion chromatography (IC) is an invaluable method that is used all too rarely in chemical analysis. Its application is particularly promising in the analysis of inorganic anions, an area where more information is needed. Ion Chromatogrphy identifies the merits of this technique. Serving as a review and reference for experienced ion chromatographers and as a teaching aid for individuals new to the field, it provides the information necessary for determining the potential usefulness of IC for a given situation. Among the areas treated, this volume focuses on eluant-suppressed IC, especially for anion and cation analysis, single-column IC, plus ancillary techniques and applications, electrochemical, spectroscopic, and other detecting methods, ion chromatography exclusion (ICE), including its limits and applications.
Characterization of foot-and-mouth disease virus's viral peptides with LC-ESI-MS
Peptides and proteins play a central role in numerous biological and physiological processes in living organisms. Viral capsid peptides are part of the viruses' outer shell of genetic materials. Viruses are recognized by immune system via capsid peptides. Depending on this property of capsid peptides, prototypes synthetic peptide-based vaccine can be developed. In this work, we synthesized three different viral peptide sequences of foot-and-mouth disease virus with microwave enhanced solid phase synthesis method. These peptides were characterized by using liquid chromatography electro spray interface mass spectrometry (LC-ESI-MS) with electro spray ionization. We briefly describe the essential facts for peptide characterization. (author)
Time-scale and noise optimality in self-organized critical adaptive networks.
Kuehn, Christian
2012-02-01
Recent studies have shown that adaptive networks driven by simple local rules can organize into "critical" global steady states, providing another framework for self-organized criticality (SOC). We focus on the important convergence to criticality and show that noise and time-scale optimality are reached at finite values. This is in sharp contrast to the previously believed optimal zero noise and infinite time-scale separation case. Furthermore, we discover a noise-induced phase transition for the breakdown of SOC. We also investigate each of these three effects separately by developing models that reveal three generically low-dimensional dynamical behaviors: time-scale resonance, a simplified version of stochastic resonance, which we call steady-state stochastic resonance, and noise-induced phase transitions. PMID:22463275
Predicting Regional Drought on Sub-Seasonal to Decadal Time Scales
Schubert, Siegfried; Wang, Hailan; Suarez, Max; Koster, Randal
2011-01-01
Drought occurs on a wide range of time scales, and within a variety of different types of regional climates. It is driven foremost by an extended period of reduced precipitation, but it is the impacts on such quantities as soil moisture, streamflow and crop yields that are often most important from a users perspective. While recognizing that different users have different needs for drought information, it is nevertheless important to understand that progress in predicting drought and satisfying such user needs, largely hinges on our ability to improve predictions of precipitation. This talk reviews our current understanding of the physical mechanisms that drive precipitation variations on subseasonal to decadal time scales, and the implications for predictability and prediction skill. Examples are given highlighting the phenomena and mechanisms controlling precipitation on monthly (e.g., stationary Rossby waves, soil moisture), seasonal (ENSO) and decadal time scales (PD and AMO).
New definitions of exponential, hyperbolic and trigonometric functions on time scales
Cieslinski, Jan L
2010-01-01
We propose two new definitions of the exponential function on time scales. The first definition is based on the Cayley transformation while the second one is a natural extension of exact discretizations. Our eponential functions map the imaginary axis into the unit circle. Therefore, it is possible to define hyperbolic and trigonometric functions on time scales in a standard way. The resulting functions preserve most of the qualitative properties of the corresponding continuous functions. In particular, Pythagorean trigonometric identities hold exactly on any time scale. Dynamic equations satisfied by Cayley-motivated functions have a natural similarity to the corresponding diferential equations. The exact discretization is less convenient as far as dynamic equations and differentiation is concerned.
Zhao, Zhuoli; Yang, Ping; Guerrero, Josep M.; Xu, Zhirong; C. Green, Timothy
2016-01-01
by microgrid energy management system (MEMS) within Zone A. Furthermore, based on the developed complete small-signal state-space model, sensitivity analysis of the eigenvalues is conducted in order to reveal the dynamic stability margin of the MV microgrid, and to identify the proper range of the......, it is more complex to control and manage. Thus in order to maintain the frequency stability in multiple-time-scales, a hierarchical control strategy is proposed. The proposed control architecture divides the system frequency in three zones: (A) stable zone, (B) precautionary zone and (C) emergency...... zone. In this way, dynamic stability control that cope with disturbances in short-time scale is implemented by microgrid central controller (MGCC) within Zone B and Zone C. Meanwhile, steady-state stability control to solve the peaks and valleys problem of loads and DGs in long-time scale is executed...
Analytical expression for gas-particle equilibration time scale and its numerical evaluation
Anttila, Tatu; Lehtinen, Kari E. J.; Dal Maso, Miikka
2016-05-01
We have derived a time scale τeq that describes the characteristic time for a single compound i with a saturation vapour concentration Ceff,i to reach thermodynamic equilibrium between the gas and particle phases. The equilibration process was assumed to take place via gas-phase diffusion and absorption into a liquid-like phase present in the particles. It was further shown that τeq combines two previously derived and often applied time scales τa and τs that account for the changes in the gas and particle phase concentrations of i resulting from the equilibration, respectively. The validity of τeq was tested by comparing its predictions against results from a numerical model that explicitly simulates the transfer of i between the gas and particle phases. By conducting a large number of simulations where the values of the key input parameters were varied randomly, it was found out that τeq yields highly accurate results when i is a semi-volatile compound in the sense that the ratio of total (gas and particle phases) concentration of i to the saturation vapour concentration of i, μ, is below unity. On the other hand, the comparison of analytical and numerical time scales revealed that using τa or τs alone to calculate the equilibration time scale may lead to considerable errors. It was further shown that τeq tends to overpredict the equilibration time when i behaves as a non-volatile compound in a sense that μ > 1. Despite its simplicity, the time scale derived here has useful applications. First, it can be used to assess if semi-volatile compounds reach thermodynamic equilibrium during dynamic experiments that involve changes in the compound volatility. Second, the time scale can be used in modeling of secondary organic aerosol (SOA) to check whether SOA forming compounds equilibrate over a certain time interval.
Controls on the Time Scale of Carbonate Neutralization of Carbon Dioxide Released to the Atmosphere
Caldeira, K.; Cao, L.
2007-12-01
Once released to the atmosphere, carbon dioxide is removed on a range of time scales. On the time scale of years to centuries, carbon dioxide removal from the atmosphere is dominated by transport processes within the ocean. On the time scale of hundreds of thousands of years, carbon dioxide removal from the atmosphere is dominated by processes related to the weathering of silicate rocks on land. Between these time scales, carbon dioxide removal is dominated by interactions involving carbonate minerals both on land and in the sea. Net dissolution of carbonate minerals (on land or in the sea) increases ocean alkalinity to an extent that exceeds the amount of carbon addition; the result is a transfer of carbon from the atmosphere to the ocean and moderation of the effects of added carbon on ocean chemical parameters such as pH and carbonate mineral saturation. There has been some controversy over how fast equilibration with carbonate minerals can neutralize carbon acidity, with claims ranging from the extreme and untenable claim that this process is essentially instantaneous to more plausible claims that the equilibration time scale may approach 10 kyr. Even within the domain of informed discourse, estimates of the carbonate neutralization timescale can vary by an order-of-magnitude. Here, in an effort to understand the sources of the lack of consensus on this issue, we examine how various processes (e.g., ocean transport, sediment pore water diffusion, carbonate-mineral dissolution, and carbonate weathering on land) influence the time scale for carbonate neutralization of carbon dioxide releases to the atmosphere.
de Lima, Isabel; Lovejoy, Shaun
2016-04-01
The characterization of precipitation scaling regimes represents a key contribution to the improved understanding of space-time precipitation variability, which is the focus here. We conduct space-time scaling analyses of spectra and Haar fluctuations in precipitation, using three global scale precipitation products (one instrument based, one reanalysis based, one satellite and gauge based), from monthly to centennial scales and planetary down to several hundred kilometers in spatial scale. Results show the presence - similarly to other atmospheric fields - of an intermediate "macroweather" regime between the familiar weather and climate regimes: we characterize systematically the macroweather precipitation temporal and spatial, and joint space-time statistics and variability, and the outer scale limit of temporal scaling. These regimes qualitatively and quantitatively alternate in the way fluctuations vary with scale. In the macroweather regime, the fluctuations diminish with time scale (this is important for seasonal, annual, and decadal forecasts) while anthropogenic effects increase with time scale. Our approach determines the time scale at which the anthropogenic signal can be detected above the natural variability noise: the critical scale is about 20 - 40 yrs (depending on the product, on the spatial scale). This explains for example why studies that use data covering only a few decades do not easily give evidence of anthropogenic changes in precipitation, as a consequence of warming: the period is too short. Overall, while showing that precipitation can be modeled with space-time scaling processes, our results clarify the different precipitation scaling regimes and further allow us to quantify the agreement (and lack of agreement) of the precipitation products as a function of space and time scales. Moreover, this work contributes to clarify a basic problem in hydro-climatology, which is to measure precipitation trends at decadal and longer scales and to
Valuation of Credit Derivatives with Multiple Time Scales in the Intensity Model
Beom Jin Kim
2014-01-01
Full Text Available We propose approximate solutions for pricing zero-coupon defaultable bonds, credit default swap rates, and bond options based on the averaging principle of stochastic differential equations. We consider the intensity-based defaultable bond, where the volatility of the default intensity is driven by multiple time scales. Small corrections are computed using regular and singular perturbations to the intensity of default. The effectiveness of these corrections is tested on the bond price and yield curve by investigating the behavior of the time scales with respect to the relevant parameters.
Separation of time-scales and reparametrization invariance for aging systems
We show that the generating functional describing the slow dynamics of spin glass systems is invariant under reparametrizations of the time. This result is general and applies for both infinite and short range models. It follows simply from the assumption that a separation between short time-scales and long time-scales exists in the system, and the constraints of causality and unitarity. Global time reparametrization invariance suggests that the low action excitations in a spin glass may be smoothly spatially varying time reparametrizations. These Goldstone modes may provide the basis for an analytic dynamical theory of short range spin glasses. (author)
Can inertial electrostatic confinement work beyond the ion-ion collisional time scale?
Inertial electrostatic confinement systems are predicated on a non-equilibrium ion distribution function. Coulomb collisions between ions cause this distribution to relax to a Maxwellian on the ion-ion collisional time-scale. The power required to prevent this relaxation and maintain the IEC configuration for times beyond the ion-ion collisional time scale is shown to be at least an order of magnitude greater than the fusion power produced. It is concluded that IEC systems show little promise as a basis for the development of commercial electric power plants
SHAO Li-wei; LIAO Xiao-zhong; ZHANG Yu-he
2007-01-01
Active disturbance rejection controller (ADRC) has good performance in induction motor (IM) control system, but controller parameter is difficult to tune. A method of tuning ADRC parameter by time scale is analyzed. The IM time scale is obtained by theoretical analysis. Combining the relations between scale time and ADRC parameters, ADRC parameter tuning in IM vector control based stator flux oriented is obtained. This parameter tuning method is validated by simulations and it provides a new technique for tuning of ADRC parameters of IM.
Time-Scales for Non-Inductive Current Buildup in Low-Aspect-Ratio Toroidal Geometry
The fundamental differences between inductive and non-inductive current buildup are clarified and the associated time-scales and other implications are discussed. A simulation is presented whereby the plasma current in a low-aspect-ratio torus is increased primarily by the self-generated bootstrap current with only 10% coming from external current drive. The maximum obtainable plasma current by this process is shown to scale with the toroidal field strength. The basic physics setting the time-scales can be obtained from a 1D analysis. Comparisons are made between the timescales found here and those reported in the experimental literature
A new Geologic Time Scale, with special reference to Precambrian and Neogene
FelixM.Gradstein; JamesG.Ogg; AlanG.Smith; WouterBleeker; LucasJ.Lourens
2004-01-01
A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. Key features of the new scale are outlined, how it was constructed, and how it can be further improved. The accompanying International Stratigraphic Chart, issued under auspices of the International Commission on Stratigraphy (ICS), shows the current chronostratigraphic scale and ages with estimates of uncertainty for all stage boundaries. Special reference is made to the Precambrian part of the time scale, which is coming of age in terms of detail, and to the Neogene portion, which has attained an ultra-high-precision absolute-age calibration.
On Qualitative Analysis of Delay Systems and $x^ = f (t, x, x^)$ on Time Scales
Yajun Ma; Yu Zhang; Jitao Sun
2010-04-01
Here we solve two problems presented in paper [9] (C C Tisdell and A Zaidi, Basic qualitative and quantitative results for solutions to nonlinear, dynamic equations on time scales with an application to economic modelling, Nonlinear Anal. 68 (2008) 3504–3524). We study existence and uniqueness of solutions for delay systems and first-order dynamic equations of the form $x^=f(t,x,x^)$ on time scales by using the Banach’s fixed-point theorem. Some examples are presented to illustrate the efficiency of the proposed results.
Screening of TACE Peptide Inhibitors from Phage Display Peptide Library
无
2005-01-01
To obtain the recombinant tumor necrosis factor-α converting enzyme (TACE) ectodomain and use it as a selective molecule for the screening of TACE peptide inhibitors, the cDNA coding catalytic domain (T800) and full-length ectodomain (T1300) of TACE were amplified by RTPCR, and the expression plasmids were constructed by inserting T800 and T1300 into plasmid pET28a and pET-28c respectively. The recombinant T800 and T1300 were induced by IPTG, and SDSPAGE and Western blotting analysis results revealed that T800 and T1300 were highly expressed in the form of inclusion body. After Ni2+-NTA resin affinity chromatography, the recombinant proteins were used in the screening of TACE-binding peptides from phage display peptide library respectively. After 4 rounds of biopanning, the positive phage clones were analyzed by ELISA, competitive inhibition assay and DNA sequencing. A common amino acid sequence (TRWLVYFSRPYLVAT) was found and synthesized. The synthetic peptide could inhibit the TNF-α release from LPS-stimulated human peripheral blood mononuclear cells (PBMC) up to 60.3 %. FACS analysis revealed that the peptide mediated the accumulation of TNF-α on the cell surface. These results demonstrate that the TACE-binding peptide is an effective antagonist of TACE.
Atomic Force Microscope Mediated Chromatography
Anderson, Mark S.
2013-01-01
The atomic force microscope (AFM) is used to inject a sample, provide shear-driven liquid flow over a functionalized substrate, and detect separated components. This is demonstrated using lipophilic dyes and normal phase chromatography. A significant reduction in both size and separation time scales is achieved with a 25-micron-length column scale, and one-second separation times. The approach has general applications to trace chemical and microfluidic analysis. The AFM is now a common tool for ultra-microscopy and nanotechnology. It has also been demonstrated to provide a number of microfluidic functions necessary for miniaturized chromatography. These include injection of sub-femtoliter samples, fluidic switching, and sheardriven pumping. The AFM probe tip can be used to selectively remove surface layers for subsequent microchemical analysis using infrared and tip-enhanced Raman spectroscopy. With its ability to image individual atoms, the AFM is a remarkably sensitive detector that can be used to detect separated components. These diverse functional components of microfluidic manipulation have been combined in this work to demonstrate AFM mediated chromatography. AFM mediated chromatography uses channel-less, shear-driven pumping. This is demonstrated with a thin, aluminum oxide substrate and a non-polar solvent system to separate a mixture of lipophilic dyes. In conventional chromatographic terms, this is analogous to thin-layer chromatography using normal phase alumina substrate with sheardriven pumping provided by the AFM tip-cantilever mechanism. The AFM detection of separated components is accomplished by exploiting the variation in the localized friction of the separated components. The AFM tip-cantilever provides the mechanism for producing shear-induced flows and rapid pumping. Shear-driven chromatography (SDC) is a relatively new concept that overcomes the speed and miniaturization limitations of conventional liquid chromatography. SDC is based on a
A multiple-time-scale approach to the control of ITBs on JET
Laborde, L.; Mazon, D.; Moreau, D. [EURATOM-CEA Association (DSM-DRFC), CEA Cadarache, 13 - Saint Paul lez Durance (France); Moreau, D. [Culham Science Centre, EFDA-JET, Abingdon, OX (United Kingdom); Ariola, M. [EURATOM/ENEA/CREATE Association, Univ. Napoli Federico II, Napoli (Italy); Cordoliani, V. [Ecole Polytechnique, 91 - Palaiseau (France); Tala, T. [EURATOM-Tekes Association, VTT Processes (Finland)
2005-07-01
The simultaneous real-time control of the current and temperature gradient profiles could lead to the steady state sustainment of an internal transport barrier (ITB) and so to a stationary optimized plasma regime. Recent experiments in JET have demonstrated significant progress in achieving such a control: different current and temperature gradient target profiles have been reached and sustained for several seconds using a controller based on a static linear model. It's worth noting that the inverse safety factor profile evolves on a slow time scale (resistive time) while the normalized electron temperature gradient reacts on a faster one (confinement time). Moreover these experiments have shown that the controller was sensitive to rapid plasma events such as transient ITBs during the safety factor profile evolution or MHD instabilities which modify the pressure profiles on the confinement time scale. In order to take into account the different dynamics of the controlled profiles and to better react to rapid plasma events the control technique is being improved by using a multiple-time-scale approximation. The paper describes the theoretical analysis and closed-loop simulations using a control algorithm based on two-time-scale state-space model. These closed-loop simulations using the full dynamic but linear model used for the controller design to simulate the plasma response have demonstrated that this new controller allows the normalized electron temperature gradient target profile to be reached faster than the one used in previous experiments. (A.C.)
A multiple-time-scale approach to the control of ITBs on JET
The simultaneous real-time control of the current and temperature gradient profiles could lead to the steady state sustainment of an internal transport barrier (ITB) and so to a stationary optimized plasma regime. Recent experiments in JET have demonstrated significant progress in achieving such a control: different current and temperature gradient target profiles have been reached and sustained for several seconds using a controller based on a static linear model. It's worth noting that the inverse safety factor profile evolves on a slow time scale (resistive time) while the normalized electron temperature gradient reacts on a faster one (confinement time). Moreover these experiments have shown that the controller was sensitive to rapid plasma events such as transient ITBs during the safety factor profile evolution or MHD instabilities which modify the pressure profiles on the confinement time scale. In order to take into account the different dynamics of the controlled profiles and to better react to rapid plasma events the control technique is being improved by using a multiple-time-scale approximation. The paper describes the theoretical analysis and closed-loop simulations using a control algorithm based on two-time-scale state-space model. These closed-loop simulations using the full dynamic but linear model used for the controller design to simulate the plasma response have demonstrated that this new controller allows the normalized electron temperature gradient target profile to be reached faster than the one used in previous experiments. (A.C.)
QUALITATIVE BEHAVIORS OF LINEAR TIME-INVARIANT DYNAMIC EQUATIONS ON TIME SCALES
无
2010-01-01
We investigate the type of singularity and qualitative structure of solutions to a time-invariant linear dynamic system on time scales. The results truly unify the qualitative behaviors of the system on the continuous and discrete times with any step size.
Existence of Solutions for Nonlinear Four-Point -Laplacian Boundary Value Problems on Time Scales
Topal SGulsan
2009-01-01
Full Text Available We are concerned with proving the existence of positive solutions of a nonlinear second-order four-point boundary value problem with a -Laplacian operator on time scales. The proofs are based on the fixed point theorems concerning cones in a Banach space. Existence result for -Laplacian boundary value problem is also given by the monotone method.
Anti-control of chaos of single time-scale brushless DC motor.
Ge, Zheng-Ming; Chang, Ching-Ming; Chen, Yen-Sheng
2006-09-15
Anti-control of chaos of single time-scale brushless DC motors is studied in this paper. In order to analyse a variety of periodic and chaotic phenomena, we employ several numerical techniques such as phase portraits, bifurcation diagrams and Lyapunov exponents. Anti-control of chaos can be achieved by adding an external constant term or an external periodic term. PMID:16893797
Hardy inequality on time scales and its application to half-linear dynamic equations
Řehák Pavel
2005-01-01
Full Text Available A time-scale version of the Hardy inequality is presented, which unifies and extends well-known Hardy inequalities in the continuous and in the discrete setting. An application in the oscillation theory of half-linear dynamic equations is given.
How the constants in Hille-Nehari theorems depend on time scales
Řehák, Pavel
2006-01-01
Roč. 2006, - (2006), s. 1-15. ISSN 1687-1839 R&D Projects: GA ČR(CZ) GA201/01/0079; GA ČR(CZ) GP201/01/P041 Institutional research plan: CEZ:AV0Z10190503 Keywords : dynamic equation * time scales * oscillation criteria Subject RIV: BA - General Mathematics
OSCILLATION FOR NONLINEAR SECOND-ORDER DYNAMIC EQUATIONS ON TIME SCALES
无
2008-01-01
Through the use of generalized Riccati transformation techniques, we establish some oscillation criteria for one type of nonlinear dynamic equation on time scales. Several examples, including a semilinear dynamic equation and a nonlinear Emden-Fowler dynamic equation, are also given to illustrate these criteria and to improve the results obtained in some references.
The Available Time Scale: Measuring Foster Parents' Available Time to Foster
Cherry, Donna J.; Orme, John G.; Rhodes, Kathryn W.
2009-01-01
This article presents a new measure of available time specific to fostering, the Available Time Scale (ATS). It was tested with a national sample of 304 foster mothers and is designed to measure the amount of time foster parents are able to devote to fostering activities. The ATS has excellent reliability, and good support exists for its validity.…
Time scale of scour around a pile in combined waves and current
Petersen, Thor Ugelvig; Sumer, B. Mutlu; Fredsøe, Jørgen
The time scale of the scour process around a circular vertical pile is studied in combined waves and current. A series of tests were carried out in a flume with pile diameters 40 mm and 75 mm, in both steady current, waves and combined waves and current. In the combined wave and current flow regime...
Space-time scaling invariant traveling wave solutions of some nonlinear fractional equations
HE, Tianlan; Fang, Hui
2012-01-01
In this paper, a homogeneous principle is proposed to seek the space-time scaling invariant traveling wave solutions expressed by power functions for some fractional differential equations. Applying this principle to generalized fractional Benjamin-Ono equations and generalized fractional ZakharovKuznetsov equations, the traveling wave solutions expressed by power functions have been obtained under some parameter conditions.
Mass action realizations of reaction kinetic system models on various time scales
Hangos, K M; Szederkenyi, G, E-mail: hangos@scl.sztaki.hu, E-mail: szeder@scl.sztaki.hu [Process Control Research Group, Computer and Automation Reseach Institute, Kende u. 13-17, H-1111 Budapest (Hungary)
2011-01-01
Complex chemical reaction networks often exhibit different dynamic behaviour on different time scales. A combined approach is proposed in this work for determining physically meaningful mass action realizations of complex chemical reaction networks that describe its dynamic behaviour on different time scales. This is achieved by appropriately reducing the detailed overall mass action kinetic scheme using quasi steady state assumptions fit to the particular time scale, and then searching for an optimal realization using mixed integer linear programing. Furthermore, the relationship between the properties (reversibility, deficiency, stability) of the obtained realizations of the same system on different time scales are also investigated and related to the same properties of the detailed overall model. It is shown that the reduced models obtained by quasi steady state assumptions may show exotic nonlinear behaviour, such as oscillations, when the original detailed is globally asymptotically stable. The proposed methods are illustrated by using a simple Michaelis-Menten type reaction kinetic example. The simplified versions of the well known Brusselator model have also been investigated and presented as a case study.
Extension of the astronomically calibrated (polarity) time scale to the Miocene/Pliocene boundary
Hilgen, F.J.
1991-01-01
The early Pleistocene to late Pliocene astronormcally calibrated time scale of Shackleton et al. [1] and Hllgen [2] is extended to the Mlocene/Pllocene boundary This is done by correlating the detailed record of CaCO 3 cycles in the Trubl and the lower part of the overlying Narbone Formation (Rossel
Pelletier, Jon D
2002-02-19
The majority of numerical models in climatology and geomagnetism rely on deterministic finite-difference techniques and attempt to include as many empirical constraints on the many processes and boundary conditions applicable to their very complex systems. Despite their sophistication, many of these models are unable to reproduce basic aspects of climatic or geomagnetic dynamics. We show that a simple stochastic model, which treats the flux of heat energy in the atmosphere by convective instabilities with random advection and diffusive mixing, does a remarkable job at matching the observed power spectrum of historical and proxy records for atmospheric temperatures from time scales of one day to one million years (Myr). With this approach distinct changes in the power-spectral form can be associated with characteristic time scales of ocean mixing and radiative damping. Similarly, a simple model of the diffusion of magnetic intensity in Earth's core coupled with amplification and destruction of the local intensity can reproduce the observed 1/f noise behavior of Earth's geomagnetic intensity from time scales of 1 (Myr) to 100 yr. In addition, the statistics of the fluctuations in the polarity reversal rate from time scales of 1 Myr to 100 Myr are consistent with the hypothesis that reversals are the result of variations in 1/f noise geomagnetic intensity above a certain threshold, suggesting that reversals may be associated with internal fluctuations rather than changes in mantle thermal or magnetic boundary conditions. PMID:11875208
Mixing and flushing time scales in the Azhikode Estuary, southwest coast of India
Revichandran, C.; Pylee, A.
Flushing time scales of the Azhikode Estuary, Kerala, India showed pronounced dry season and wet season signals as well as large inter-annual variation. Cumulative flushing time of the estuary varies from 4.8 tide cycles in April to 1.22 tide cycles...
Fission time-scale from the measurement of pre-scission light particles and -ray multiplicities
K Ramachandran; A Chatterjee; A Navin; K Mahata; A Shrivastava; V Tripathi; S Kailas; V Nanal; R G Pillay; A Saxena; R G Thomas; D R Chakrabarty; V M Datar; Suresh Kumar; P K Sahu
2015-08-01
An overview of the experimental result on simultaneous measurement of pre-scission neutron, proton, -particle and GDR -ray multiplicities for the reaction 28Si+175Lu at 159 MeV using the BARC–TIFR Pelletron–LINAC accelerator facility is given. The data were analysed using deformation-dependent particle transmission coefficients, binding energies and level densities which are incorporated in the code JOANNE2 to extract fission time-scales and mean deformation of the saddle-to-scission emitter. The neutron, light charged particle and GDR -ray multiplicity data could be explained consistently. The emission of neutrons seems to be favoured towards larger deformation as compared to charged particles. The pre-saddle time-scale is deduced as (0–2) × 10−21 s whereas the saddle-to-scission time-scale is (36–39) × 10−21 s. The total fission time-scale is deduced as (36–41) × 10−21 s.
A limit set trichotomy for order-preserving systems on time scales
Christian Poetzsche
2004-04-01
Full Text Available In this paper we derive a limit set trichotomy for abstract order-preserving 2-parameter semiflows in normal cones of strongly ordered Banach spaces. Additionally, to provide an example, Muller's theorem is generalized to dynamic equations on arbitrary time scales and applied to a model from population dynamics.
Time scales: from Nabla calculus to Delta calculus and vice versa via duality
Caputo, M. Cristina
2009-01-01
In this note we show how one can obtain results from the nabla calculus from results on the delta calculus and vice versa via a duality argument. We provide applications of the main results to the calculus of variations on time scales.
An Inverse Problem of the Calculus of Variations on Arbitrary Time Scales
Dryl, Monika; Malinowska, Agnieszka B.; Torres, Delfim F. M.
2014-01-01
We consider an inverse extremal problem for variational functionals on arbitrary time scales. Using the Euler-Lagrange equation and the strengthened Legendre condition, we derive a general form for a variational functional that attains a local minimum at a given point of the vector space.
Durand, P.; Paidarová, Ivana
2011-01-01
Roč. 111, č. 2 (2011), s. 225-236. ISSN 0020-7608 R&D Projects: GA AV ČR IAA100400501; GA AV ČR IAA401870702 Institutional research plan: CEZ:AV0Z40400503 Keywords : Liouville equation * time scales * chemical kinetics and dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.357, year: 2011
POSITIVE SOLUTIONS TO A SECOND-ORDER m-POINT BOUNDARY VALUE PROBLEM ON TIME SCALES
Liu Yang; Chunfang Shen
2009-01-01
By a fixed point theorem in a cone,the existence of at least three positive solutions to a class of second-order multi-point boundary value problem for dynamic equation on time scales with the nonlinear term depends on the first order derivative is studied.
DIRECTIONAL DERIVATIVE OF VECTOR FIELD AND REGULAR CURVES ON TIME SCALES
Emin (O)zyilmaz
2006-01-01
The general idea in this paper is to study curves of the parametric equations where the parameter varies in a so-called time scale, which may be an arbitrary closed subset of the set of all real numbers. We introduce the directional derivative according to the vector fields.
Yepeng Xing; Qiong Wang; Valery G. Romanovski
2009-01-01
We prove several new comparison results and develop the monotone iterative tech-nique to show the existence of extremal solutions to a kind of periodic boundary value problem (PBVP) for nonlinear integro-differential equation of mixed type on time scales.
郭静; 晏嘉泽; 郭明; 靳艳
2014-01-01
Based on the shotgun proteomic method,rape bee pollen protein was prepared with ultrasonic extraction and digested by trypsin,then separated and sequenced by reversed-phase liquid chromatography-tandem mass spectrometry( RPLC-MS / MS),followed by protein data-base searching. After the above analysis,353 peptides were identified and the molecular biolog-ical functions of 239 proteins have been known. The identified molecular biological functions of these proteins mainly included binding activity,enzyme activity,transporter activity,inhibitor activity and so on. Five peptides were obtained after the screening and appropriate amino acid modification among the identified 353 peptides,according to the relationship between the sequence structure of the bioactivity peptide and angiotensin converting enzyme( ACE)inhibi-tor activity. The five peptides were speculated to have ACE inhibitor activity and synthesized to detect ACE inhibitor activity. The results showed that all of the five peptides had good ACE inhibitor activity. The peptides of AELDIVLALF and LAVNLIPFP among the five peptides dis-played especially good ACE inhibition with half maximal inhibitory concentration( IC 50 ) of (10. 65±0. 50)μmol / L and(23. 66±1. 08)μmol / L,respectively. This method is rapid,low-cost and achieves the goal of high-throughput screening of bioactivity peptides that greatly shorten the period of identification compared with traditional methods.%基于鸟枪法蛋白质组学分析方法，使用反相液相色谱-串联质谱（RPLC-MS / MS）系统分析油菜蜂花粉蛋白质的胰蛋白酶酶解产物，结合数据库检索，共鉴定到353条肽段。鉴定到的肽段所归属的蛋白质中有239个蛋白质可检索到其分子生物学功能，主要功能为结合活性、酶活性、运输活性、抑制活性等。根据血管紧张素转化酶（ ACE）抑制肽活性与多肽构效之间的关系，从鉴定到的肽段中筛选并适当修饰后得到5
A hybrid procedure for MSW generation forecasting at multiple time scales in Xiamen City, China
Xu, Lilai, E-mail: llxu@iue.ac.cn [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021 (China); Xiamen Key Lab of Urban Metabolism, Xiamen 361021 (China); Gao, Peiqing, E-mail: peiqing15@yahoo.com.cn [Xiamen City Appearance and Environmental Sanitation Management Office, 51 Hexiangxi Road, Xiamen 361004 (China); Cui, Shenghui, E-mail: shcui@iue.ac.cn [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021 (China); Xiamen Key Lab of Urban Metabolism, Xiamen 361021 (China); Liu, Chun, E-mail: xmhwlc@yahoo.com.cn [Xiamen City Appearance and Environmental Sanitation Management Office, 51 Hexiangxi Road, Xiamen 361004 (China)
2013-06-15
Highlights: ► We propose a hybrid model that combines seasonal SARIMA model and grey system theory. ► The model is robust at multiple time scales with the anticipated accuracy. ► At month-scale, the SARIMA model shows good representation for monthly MSW generation. ► At medium-term time scale, grey relational analysis could yield the MSW generation. ► At long-term time scale, GM (1, 1) provides a basic scenario of MSW generation. - Abstract: Accurate forecasting of municipal solid waste (MSW) generation is crucial and fundamental for the planning, operation and optimization of any MSW management system. Comprehensive information on waste generation for month-scale, medium-term and long-term time scales is especially needed, considering the necessity of MSW management upgrade facing many developing countries. Several existing models are available but of little use in forecasting MSW generation at multiple time scales. The goal of this study is to propose a hybrid model that combines the seasonal autoregressive integrated moving average (SARIMA) model and grey system theory to forecast MSW generation at multiple time scales without needing to consider other variables such as demographics and socioeconomic factors. To demonstrate its applicability, a case study of Xiamen City, China was performed. Results show that the model is robust enough to fit and forecast seasonal and annual dynamics of MSW generation at month-scale, medium- and long-term time scales with the desired accuracy. In the month-scale, MSW generation in Xiamen City will peak at 132.2 thousand tonnes in July 2015 – 1.5 times the volume in July 2010. In the medium term, annual MSW generation will increase to 1518.1 thousand tonnes by 2015 at an average growth rate of 10%. In the long term, a large volume of MSW will be output annually and will increase to 2486.3 thousand tonnes by 2020 – 2.5 times the value for 2010. The hybrid model proposed in this paper can enable decision makers to
A hybrid procedure for MSW generation forecasting at multiple time scales in Xiamen City, China
Highlights: ► We propose a hybrid model that combines seasonal SARIMA model and grey system theory. ► The model is robust at multiple time scales with the anticipated accuracy. ► At month-scale, the SARIMA model shows good representation for monthly MSW generation. ► At medium-term time scale, grey relational analysis could yield the MSW generation. ► At long-term time scale, GM (1, 1) provides a basic scenario of MSW generation. - Abstract: Accurate forecasting of municipal solid waste (MSW) generation is crucial and fundamental for the planning, operation and optimization of any MSW management system. Comprehensive information on waste generation for month-scale, medium-term and long-term time scales is especially needed, considering the necessity of MSW management upgrade facing many developing countries. Several existing models are available but of little use in forecasting MSW generation at multiple time scales. The goal of this study is to propose a hybrid model that combines the seasonal autoregressive integrated moving average (SARIMA) model and grey system theory to forecast MSW generation at multiple time scales without needing to consider other variables such as demographics and socioeconomic factors. To demonstrate its applicability, a case study of Xiamen City, China was performed. Results show that the model is robust enough to fit and forecast seasonal and annual dynamics of MSW generation at month-scale, medium- and long-term time scales with the desired accuracy. In the month-scale, MSW generation in Xiamen City will peak at 132.2 thousand tonnes in July 2015 – 1.5 times the volume in July 2010. In the medium term, annual MSW generation will increase to 1518.1 thousand tonnes by 2015 at an average growth rate of 10%. In the long term, a large volume of MSW will be output annually and will increase to 2486.3 thousand tonnes by 2020 – 2.5 times the value for 2010. The hybrid model proposed in this paper can enable decision makers to
Chen, Qi; Zhang, Jingshun; Ke, Xing; Lai, Shiyun; Li, Duo; Yang, Jinchuan; Mo, Weimin; Ren, Yiping
2016-09-01
In recent years, there is an increasing need to measure the concentration of individual proteins in human milk, instead of total human milk proteins. Due to lack of human milk protein standards, there are only few quantification methods established. The objective of the present work was to develop a simple and rapid quantification method for simultaneous determination of α-lactalbumin and β-casein in human milk using signature peptides according to a modified quantitative proteomics strategy. The internal standards containing the signature peptide sequences were synthesized with isotope-labeled amino acids. The purity of synthesized peptides as standards was determined by amino acid analysis method and area normalization method. The contents of α-lactalbumin and β-casein in human milk were measured according to the equimolar relationship between the two proteins and their corresponding signature peptides. The method validation results showed a satisfied linearity (R(2)>0.99) and recoveries (97.2-102.5% for α-lactalbumin and 99.5-100.3% for β-casein). The limit of quantification for α-lactalbumin and β-casein was 8.0mg/100g and 1.2mg/100g, respectively. CVs for α-lactalbumin and β-casein in human milk were 5.2% and 3.0%. The contents of α-lactalbumin and β-casein in 147 human milk samples were successfully determined by the established method and their contents were 205.5-578.2mg/100g and 116.4-467.4mg/100g at different lactation stages. The developed method allows simultaneously determination of α-lactalbumin and β-casein in human milk. The quantitative strategy based on signature peptide should be applicable to other endogenous proteins in breast milk and other body fluids. PMID:27295510
The Global Monsoon across Time Scales: is there coherent variability of regional monsoons?
Wang, P. X.; Wang, B.; Cheng, H.; Fasullo, J.; Guo, Z. T.; Kiefer, T.; Liu, Z. Y.
2014-05-01
Monsoon has earned increasing attention from the climate community since the last century, yet only recently regional monsoons have been recognized as a global system. It remains a debated issue, however, as to what extent and at which time scales the global monsoon can be viewed as a major mode of climate variability. For this purpose a PAGES Working Group (WG) was set up to investigate the concept of the global monsoon and its future research directions. The WG's synthesis is presented here. On the basis of observation and proxy data, the WG found that the regional monsoons can vary coherently, although not perfectly, at various time scales, ranging from interannual, interdecadal, centennial and millennial, up to orbital and tectonics time scales, conforming the global monsoon concept across time scales. Within the global monsoon system each subsystem has its own features depending on its geographic and topographic conditions. Discrimination of global and regional components in the monsoon system is a key to reveal the driving factors of monsoon variations, hence the global monsoon concept helps to enhance our understanding and to improve future projection of the regional monsoons. This paper starts with a historical review of the global monsoon concept in both modern and paleo-climatology, and an assessment of monsoon proxies used in regional and global scales. The main body of the paper is devoted to a summary of observation data at various time scales, providing evidence for the coherent global monsoon system. The paper concludes with a projection of future monsoon shifts into a warming world. The synthesis will be followed by a companying paper to discuss driving mechanisms and outstanding issues in the global monsoon studies.
Time Scale Optimization and the Hunt for Astronomical Cycles in Deep Time Strata
Meyers, Stephen R.
2016-04-01
A valuable attribute of astrochronology is the direct link between chronometer and climate change, providing a remarkable opportunity to constrain the evolution of the surficial Earth System. Consequently, the hunt for astronomical cycles in strata has spurred the development of a rich conceptual framework for climatic/oceanographic change, and has allowed exploration of the geologic record with unprecedented temporal resolution. Accompanying these successes, however, has been a persistent skepticism about appropriate astrochronologic testing and circular reasoning: how does one reliably test for astronomical cycles in stratigraphic data, especially when time is poorly constrained? From this perspective, it would seem that the merits and promise of astrochronology (e.g., a geologic time scale measured in ≤400 kyr increments) also serves as its Achilles heel, if the confirmation of such short rhythms defies rigorous statistical testing. To address these statistical challenges in astrochronologic testing, a new approach has been developed that (1) explicitly evaluates time scale uncertainty, (2) is resilient to common problems associated with spectrum confidence level assessment and 'multiple testing', and (3) achieves high statistical power under a wide range of conditions (it can identify astronomical cycles when present in data). Designated TimeOpt (for "time scale optimization"; Meyers 2015), the method employs a probabilistic linear regression model framework to investigate amplitude modulation and frequency ratios (bundling) in stratigraphic data, while simultaneously determining the optimal time scale. This presentation will review the TimeOpt method, and demonstrate how the flexible statistical framework can be further extended to evaluate (and optimize upon) complex sedimentation rate models, enhancing the statistical power of the approach, and addressing the challenge of unsteady sedimentation. Meyers, S. R. (2015), The evaluation of eccentricity
A cardioactive peptide from the southern armyworm, Spodoptera eridania.
Furuya, K; Hackett, M; Cirelli, M A; Schegg, K M; Wang, H; Shabanowitz, J; Hunt, D F; Schooley, D A
1999-01-01
A cardioactive peptide was isolated from extracts of whole heads of the southern armyworm, Spodoptera eridania. This peptide has the sequence ENFAVGCTPGYQRTADGRCKPTF (Mr = 2516.8), determined from both Edman sequencing and tandem mass spectrometry in combination with off-line micropreparative capillary liquid chromatography. This peptide, termed Spoer-CAP23, has excitatory effects on a semi-isolated heart from larval Manduca sexta, causing an inotropic effect at low concentrations of peptide and chronotropic and inotropic effects at high doses. The threshold concentration for stimulatory effects of the synthetic peptide on the semi-isolated heart was about 1 nM, suggesting a physiological role as a neuropeptide. PMID:10098624
Wang, Qiqin; Sánchez-López, Elena; Han, Hai; Wu, Huihui; Zhu, Peijie; Crommen, Jacques; Marina, Maria Luisa; Jiang, Zhengjin
2016-01-01
In the present study, a new analytical methodology was developed enabling the enantiomeric determination of N-derivatized di- and tri-peptides in dietary supplements using chiral micro-LC on a monolithic column consisting of poly(O-9-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine-co-2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) (poly(MQD-co-HEMA-co-EDMA)). After optimization of the mobile phase conditions, a baseline resolution of the stereoisomers of 24 out of 53 N-derivatized di- and tri-peptides was obtained. 3,5-Dinitrobenzoyl- and 3,5-dichlorobenzoyl-peptide stereoisomers were separated with exceptionally high selectivity and resolution. The monolithic column was then applied to the quantitative analysis of l-carnosine and its enantiomeric impurity in three different commercial dietary supplements. Method validation demonstrated satisfactory results in terms of linearity, precision, selectivity, accuracy and limits of detection and quantification. The determined amounts of l-carnosine in commercial formulations were in agreement with the labeled content for all analyzed samples, and the enantiomeric impurity was found to be below the limit of detection (LOD), showing the potential of the poly(MQD-co-HEMA-co-EDMA) monolithic column as a reliable tool for the quality control of l-carnosine in dietary supplements by micro-LC. PMID:26410182
Enrichment of Phosphopeptides via Immobilized Metal Affinity Chromatography.
Swaney, Danielle L; Villén, Judit
2016-01-01
Immobilized metal affinity chromatography (IMAC) is a frequently used method for the enrichment of phosphorylated peptides from complex, cellular lysate-derived peptide mixtures. Here we outline an IMAC protocol that uses iron-chelated magnetic beads to selectively isolate phosphorylated peptides for mass spectrometry-based proteomic analysis. Under acidic conditions, negatively charged phosphoryl modifications preferentially bind to positively charged metal ions (e.g., Fe(3+), Ga(3+)) on the beads. After washing away nonphosphorylated peptides, a pH shift to basic conditions causes the elution of bound phosphopeptides from the metal ion. Under optimal conditions, very high specificity for phosphopeptides can be achieved. PMID:26933247
Chaos anticontrol and synchronization of three time scales brushless DC motor system
Ge Zhengming E-mail: zmg@cc.nctu.edu.tw; Cheng Juiwen; Chen Yensheng
2004-12-01
Chaos anticontrol of three time scale brushless dc motors and chaos synchronization of different order systems are studied. Nondimensional dynamic equations of three time scale brushless DC motor system are presented. Using numerical results, such as phase diagram, bifurcation diagram, and Lyapunov exponent, periodic and chaotic motions can be observed. By adding constant term, periodic square wave, the periodic triangle wave, the periodic sawtooth wave, and kx vertical bar x vertical bar term, to achieve anticontrol of chaotic or periodic systems, it is found that more chaotic phenomena of the system can be observed. Then, by coupled terms and linearization of error dynamics, we obtain the partial synchronization of two different order systems, i.e. brushless DC motor system and rate gyroscope system.
Klioner, S A
2005-01-01
The paper is devoted to a detailed explanation of relativistic scaling of astronomical quantities induced by times scales \\TDB and \\TT. It is argued that scaled time scales, scaled spatial coordinates and scaled masses should be considered as distinct quantities which themselves can be expressed in any units (rather then numerical values expressed in some non-SI units ("TDB units" and "TT units") as can be sometimes found in the literature). The system of astronomical units in the relativistic framework is discussed. The whole freedom in the definitions of the systems of astronomical units for TCB and TDB is demonstrated. A number of possible ways to freeze the freedom are shown and discussed. It is argued that in the near future one should probably think about converting AU into a defined quantity (by fixing its value in SI meters).
Chaos anticontrol and synchronization of three time scales brushless DC motor system
Chaos anticontrol of three time scale brushless dc motors and chaos synchronization of different order systems are studied. Nondimensional dynamic equations of three time scale brushless DC motor system are presented. Using numerical results, such as phase diagram, bifurcation diagram, and Lyapunov exponent, periodic and chaotic motions can be observed. By adding constant term, periodic square wave, the periodic triangle wave, the periodic sawtooth wave, and kx vertical bar x vertical bar term, to achieve anticontrol of chaotic or periodic systems, it is found that more chaotic phenomena of the system can be observed. Then, by coupled terms and linearization of error dynamics, we obtain the partial synchronization of two different order systems, i.e. brushless DC motor system and rate gyroscope system
Modelling solar irradiance variability on time scales from minutes to months
Seleznyov, Andrey D; Krivova, Natalie A; 10.1051/0004-6361/200811138
2013-01-01
We analyze and model total solar irradiance variability on time scales from minutes to months, excluding variations due to p-mode oscillations, using a combination of convective and magnetic components. These include granulation, the magnetic network, faculae and sunspots. Analysis of VIRGO data shows that on periods of a day or longer solar variability depends on magnetic activity, but is nearly independent at shorter periods. We assume that only granulation affects the solar irradiance variability on time scales from minutes to hours. Granulation is described as a large sample of bright cells and dark lanes that evolve according to rules deduced from observations and radiation hydrodynamic simulations. Comparison of this model combined with a high time resolution magnetic-field based irradiance reconstruction, with solar data reveals a good correspondence except at periods of 10 to 30 hours. This suggests that the model is missing some power at these periods, which may be due to the absence of supergranulat...
Multiple dynamical time-scales in networks with hierarchically nested modular organization
Sitabhra Sinha; Swarup Poria
2011-11-01
Many natural and engineered complex networks have intricate mesoscopic organization, e.g., the clustering of the constituent nodes into several communities or modules. Often, such modularity is manifested at several different hierarchical levels, where the clusters deﬁned at one level appear as elementary entities at the next higher level. Using a simple model of a hierarchical modular network, we show that such a topological structure gives rise to characteristic time-scale separation between dynamics occurring at different levels of the hierarchy. This generalizes our earlier result for simple modular networks, where fast intramodular and slow intermodular processes were clearly distinguished. Investigating the process of synchronization of oscillators in a hierarchical modular network, we show the existence of as many distinct time-scales as there are hierarchical levels in the system. This suggests a possible functional role of such mesoscopic organization principle in natural systems, viz., in the dynamical separation of events occurring at different spatial scales.
Forced bursting and transition mechanism in CO oxidation with three time scales
Li Xiang-Hong; Bi Qin-Sheng
2013-01-01
The mathematical model of CO oxidation with three time scales on platinum group metals is investigated,in which order gaps between the time scales related to external perturbation and the rates associated with different chemical reaction steps exist.Forced bursters,such as point-point type forced bursting and point-cycle type forced bursting,are presented.The bifurcation mechanism of forced bursting is novel,and the phenomenon where two different kinds of spiking states coexist in point-cycle type forced bursting has not been reported in previous work.A double-parameter bifurcation set of the fast subsystem is explored to reveal the transition mechanisms of different forced bursters with parameter variation.
Forced bursting and transition mechanism in CO oxidation with three time scales
The mathematical model of CO oxidation with three time scales on platinum group metals is investigated, in which order gaps between the time scales related to external perturbation and the rates associated with different chemical reaction steps exist. Forced bursters, such as point—point type forced bursting and point—cycle type forced bursting, are presented. The bifurcation mechanism of forced bursting is novel, and the phenomenon where two different kinds of spiking states coexist in point—cycle type forced bursting has not been reported in previous work. A double-parameter bifurcation set of the fast subsystem is explored to reveal the transition mechanisms of different forced bursters with parameter variation. (general)
Small-time scale network traffic prediction based on a local support vector machine regression model
Meng Qing-Fang; Chen Yue-Hui; Peng Yu-Hua
2009-01-01
In this paper we apply the nonlinear time series analysis method to small-time scale traffic measurement data. The prediction-based method is used to determine the embedding dimension of the traffic data. Based on the reconstructed phase space, the local support vector machine prediction method is used to predict the traffic measurement data, and the BIC-based neighbouring point selection method is used to choose the number of the nearest neighbouring points for the local support vector machine regression model. The experimental results show that the local support vector machine prediction method whose neighbouring points are optimized can effectively predict the small-time scale traffic measurement data and can reproduce the statistical features of real traffic measurements.
AN IMPROVED ALGORITHM OF GMM VOICE CONVERSION SYSTEM BASED ON CHANGING THE TIME-SCALE
Zhou Ying; Zhang Linghua
2011-01-01
This paper improves and presents an advanced method of the voice conversion system based on Gaussian Mixture Models (GMM) models by changing the time-scale of speech.The Speech Transformation and Representation using Adaptive Interpolation of weiGHTed spectrum (STRAIGHT) model is adopted to extract the spectrum features,and the GMM models are trained to generate the conversion function.The spectrum features of a source speech will be converted by the conversion function.The time-scale of speech is changed by extracting the converted features and adding to the spectrum.The conversion voice was evaluated by subjective and objective measurements.The results confirm that the transformed speech not only approximates the characteristics of the target speaker,but also more natural and more intelligible.
Najet Rhaiem
2007-01-01
Full Text Available In this research focus is on the estimation of the Capital Asset Pricing Model (CAPM at different time scales for French’s stock market. The proposed methods makes possible to quantify the correlation between the return of a stock and its beta at different time scales. Our sample is composed of twenty six stocks that were actively traded over 2002-2005. The empirical results show that the relationship between the return of a stock and its beta becomes stronger as the scale increase, but the test of the linearity between the tow variables show that there is an important ambiguity. Therefore, the predictions of the CAPM are more relevant at a medium-term horizon in a multi-scale framework as compared to short time horizons.
Time scales of epidemic spread and risk perception on adaptive networks
Zhong, Li-Xin; Ren, Fei; Li, Ping-Ping; Chen, Bi-Hui
2010-01-01
Incorporating dynamic contact networks and delayed awareness into a contagion model with memory, we study the spreading patterns of infectious diseases in connected populations. It is found that the spread of an infectious disease is not only related to the past exposures of an individual to the infected but also to the time scales of risk perception reflected in the social network adaptation. The epidemic threshold $p_{c}$ is found to decrease with the rise of the time scale parameter s and the memory length T, they satisfy the equation $p_{c} =\\frac{1}{T}+ \\frac{\\omega T}{a^s(1-e^{-\\omega T^2/a^s})}$. Both the lifetime of the epidemic and the topological property of the evolved network are considered. The standard deviation $\\sigma_{d}$ of the degree distribution increases with the rise of the absorbing time $t_{c}$, a power-law relation $\\sigma_{d}=mt_{c}^\\gamma$ is found.
A Visual Method of Time Scale Determination using a PC for Radio Sources
Yong Huang; Jun-Hui Fan; Jing Pan
2011-03-01
Variability is one of the extremely observational properties. In the radio bands, variability is caused by the shock in the jet. In this case, emissions increase rapidly following an exponential curve, and then decrease rapidly also in an exponential curve. The variability time scale is important with regard to the physics carrying on in the jet. However, it is not easy to fit the light curve. In this paper, we proposed a method of light curve fitting on a PC machine, in which the theoretical exponential light curve is adopted to the observations using the least regression method. Using this method, anybody can fit the light curve and get the time scale by moving and clicking themouse.We also used this method to some light curves obtained from the archive and compared our results with those in the literature.
On balanced approximations for time integration of multiple time scale systems
Knoll, D A; Margolin, L G; Mousseau, V A
2003-01-01
The effect of various numerical approximations used to solve linear and nonlinear problems with multiple time scales is studied in the framework of modified equation analysis (MEA). First, MEA is used to study the effect of linearization and splitting in a simple nonlinear ordinary differential equation (ODE), and in a linear partial differential equation (PDE). Several time discretizations of the ODE and PDE are considered, and the resulting truncation terms are compared analytically and numerically. It is demonstrated quantitatively that both linearization and splitting can result in accuracy degradation when a computational time step larger than any of the competing (fast) time scales is employed. Many of the issues uncovered on the simple problems are shown to persist in more realistic applications. Specifically, several differencing schemes using linearization and/or time splitting are applied to problems in nonequilibrium radiation-diffusion, magnetohydrodynamics, and shallow water flow, and their solut...
Stability analysis of nonlinear systems by multiple time scaling. [using perturbation methods
Morino, L.
1974-01-01
The asymptotic solution for the transient analysis of a general nonlinear system in the neighborhood of the stability boundary was obtained by using the multiple-time-scaling asymptotic-expansion method. The nonlinearities are assumed to be of algebraic nature. Terms of order epsilon to the 3rd power (where epsilon is the order of amplitude of the unknown) are included in the solution. The solution indicates that there is always a limit cycle which is stable (unstable) and exists above (below) the stability boundary if the nonlinear terms are stabilizing (destabilizing). Extension of the solution to include fifth order nonlinear terms is also presented. Comparisons with harmonic balance and with multiple-time-scaling solution of panel flutter equations are also included.
Modes of correlated angular motion in live cells across three distinct time scales
Particle tracking experiments with high speed digital microscopy yield the positions and trajectories of lipid droplets inside living cells. Angular correlation analysis shows that the lipid droplets have uncorrelated motion at short time scales (τ 10 ms, becomes persistent, indicating directed movement. The motion at all time scales is associated with the lipid droplets being tethered to and driven along the microtubule network. The point at which the angular correlation changes from anti-persistent to persistent motion corresponds to the cross over between sub-diffusive and super diffusive motion, as observed by mean square displacement analysis. Correct analysis of the angular correlations of the detector noise is found to be crucial in modelling the observed phenomena. (paper)
Time-scale effects on the gain-loss asymmetry in stock indices
Sándor, Bulcsú
2016-01-01
The gain-loss asymmetry, observed in the inverse statistics of stock indices is present for logarithmic return levels that are over $2\\%$, and it is the result of the non-Pearson type auto-correlations in the index. These non-Pearson type correlations can be viewed also as functionally dependent daily volatilities, extending for a finite time interval. A generalized time-window shuffling method is used to show the existence of such auto-correlations. Their characteristic time-scale proves to be smaller (less than $25$ trading days) than what was previously believed. It is also found that this characteristic time-scale has decreased with the appearance of program trading in the stock market transactions. Connections with the leverage effect are also established.
Virtual Testing of Large Composite Structures: A Multiple Length/Time-Scale Framework
Gigliotti, Luigi; Pinho, Silvestre T.
2015-12-01
This paper illustrates a multiple length/time-scale framework for the virtual testing of large composite structures. Such framework hinges upon a Mesh Superposition Technique (MST) for the coupling between areas of the structure modelled at different length-scales and upon an efficient solid-to-shell numerical homogenization which exploits the internal symmetries of Unit Cells (UCs). Using this framework, it is possible to minimize the areas of the structure modelled at the lowest- (and computationally demanding) scales and the computational cost required to calculate the homogenised to be used in the higher-scales subdomains of multiscale FE models, as well as to simulate the mechanical response of different parts of the structure using different solvers, depending on where they are expected to provide the most computationally efficient solution. The relevance and key-aspects of the multiple length/time-scale framework are demonstrated through the analysis of a real-sized aeronautical composite component.
Goswami, Prashant; Nishad, Shiv Narayan
2015-01-01
Assessment and policy design for sustainability in primary resources like arable land and water need to adopt long-term perspective; even small but persistent effects like net export of water may influence sustainability through irreversible losses. With growing consumption, this virtual water trade has become an important element in the water sustainability of a nation. We estimate and contrast the virtual (embedded) water trades of two populous nations, India and China, to present certain quantitative measures and time scales. Estimates show that export of embedded water alone can lead to loss of water sustainability. With the current rate of net export of water (embedded) in the end products, India is poised to lose its entire available water in less than 1000 years; much shorter time scales are implied in terms of water for production. The two cases contrast and exemplify sustainable and non-sustainable virtual water trade in long term perspective. PMID:25790964
Murray, Lee Thomas
2013-01-01
This thesis explores the natural forces controlling variability of the tropospheric oxidants on interannual to glacial-interglacial time scales. The oxidants (primarily OH and ozone) determine the lifetime of many trace gases of human interest, including air pollutants and long-lived greenhouse gases such as methane. The oxidants respond to meteorological conditions, precursor emissions (natural and anthropogenic), and surface and overhead stratospheric boundary conditions, all of which have ...
Chaos synchronization and parameter identification of three time scales brushless DC motor system
Ge, Z.-M. [Department of Mechanical Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 300, Taiwan (China)]. E-mail: zmg@cc.nctu.edu.tw; Cheng, J.-W. [Department of Mechanical Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 300, Taiwan (China)
2005-04-01
Chaotic anticontrol and chaos synchronization of brushless DC motor system are studied in this paper. Nondimensional dynamic equations of three time scale brushless DC motor system are presented. Using numerical results, such as phase diagram, bifurcation diagram, and Lyapunov exponent, periodic and chaotic motions can be observed. Then, chaos synchronization of two identical systems via additional inputs and Lyapunov stability theory are studied. And further, the parameter of the system is traced via adaptive control and random optimization method.
Mixed-mode oscillations in a multiple time scale phantom bursting system
Krupa, Maciej; Vidal, Alexandre; Desroches, Mathieu; Clément, Frédérique
2012-01-01
38 pages, 16 figures. International audience In this work we study mixed mode oscillations in a model of secretion of GnRH (Gonadotropin Releasing Hormone). The model is a phantom burster consisting of two feedforward coupled FitzHugh-Nagumo systems, with three time scales. The forcing system (Regulator) evolves on the slowest scale and acts by moving the slow nullcline of the forced system (Secretor). There are three modes of dynamics: pulsatility (transient relaxation oscillation), su...
New Insights on the Variability of Ecosystem Functioning Across Time Scales
Pappas, C.; Mahecha, M. D.; Frank, D. C.; Koutsoyiannis, D.
2015-12-01
Ecosystem functioning is monitored worldwide over several decades. However, a comparative in-depth characterization of the temporal variability of essential ecosystem processes, such as for example carbon assimilation and respiration is still lacking. The intra-annual (sub-diurnal, diurnal, and seasonal) variability of these processes can be well described by basic mechanisms such as the plant response to light. In contrast, the inter-annual variability and its origins and magnitude, remain highly uncertain. To date, there have only been a few attempts to investigate these issues across sites, ecosystems variables, and time scales, yet a general and comprehensive overview is outstanding. Here, we present a synthesis of a wide range of observations over Europe, namely: (i) eddy covariance measurements of carbon, energy, and water fluxes, (ii) satellite data of leaf area index and photosynthetically active radiation absorbed by plants, (iii) tree-ring widths, and (iv) dendrometer measurements of tree stem radius changes, and we analyze their variability from the half-hourly to the decadal time scale. Our analysis shows that all ecosystems can be characterized by three distinct regimes of variability (sub-daily, daily-seasonal, and seasonal-annual) confined within the ranges of the available resources, i.e., water (precipitation) and energy (radiation and temperature). We find a convergence of the range of variability of hydrometeorological drivers. Surprisingly, such convergence is not reflected in the variability of the ecosystem responses across sites. Although the magnitude of variability of ecosystem functioning varies across sites, the temporal dependences present the same characteristics over time scales spanning five orders of magnitude. We show that this behaviour can be well simulated by combining simple stochastic models with deterministic harmonics (diurnal and annual cycles). This allows us to statistically characterize the short- and long
Diffusion Time-Scale Invariance, Markovization Processes and Memory Effects in Lennard-Jones Liquids
Yulmetyev, Renat M.; Mokshin, Anatolii V.; Hänggi, Peter
2004-01-01
We report the results of calculation of diffusion coefficients for Lennard-Jones liquids, based on the idea of time-scale invariance of relaxation processes in liquids. The results were compared with the molecular dynamics data for Lennard-Jones system and a good agreement of our theory with these data over a wide range of densities and temperatures was obtained. By calculations of the non-Markovity parameter we have estimated numerically statistical memory effects of diffusion in detail.
Chaos synchronization and parameter identification of three time scales brushless DC motor system
Chaotic anticontrol and chaos synchronization of brushless DC motor system are studied in this paper. Nondimensional dynamic equations of three time scale brushless DC motor system are presented. Using numerical results, such as phase diagram, bifurcation diagram, and Lyapunov exponent, periodic and chaotic motions can be observed. Then, chaos synchronization of two identical systems via additional inputs and Lyapunov stability theory are studied. And further, the parameter of the system is traced via adaptive control and random optimization method