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131.
Safrai E Ishai PB Caduff A Puzenko A Polsman A Agranat AJ Feldman Y 《Bioelectromagnetics》2012,33(5):375-382
Recent work has demonstrated that the reflection coefficient of human skin in the frequency range from 95 to 110 GHz (W band) mirrors the temporal relaxation of stress induced by physical exercise. In this work, we extend these findings to show that in the event of a subtle trigger to stress, such as mental activity, a similar picture of response emerges. Furthermore, the findings are extended to cover not only the W band (75-110 GHz), but also the frequency band from 110 to 170 GHz (D band). We demonstrate that mental stress, induced by the Stroop effect and recorded by the galvanic skin response (GSR), can be correlated to the reflection coefficient in the aforementioned frequency bands. Intriguingly, a light physical stress caused by repeated hand gripping clearly showed an elevated stress level in the GSR signal, but was largely unnoted in the reflection coefficient in the D band. The implication of this observation requires further validation. 相似文献
132.
Lucia Rubio Fernandez Guy Vandenbussche Nancy Roosens Cédric Govaerts Erik Goormaghtigh Nathalie Verbruggen 《Biochimica et Biophysica Acta - Proteins and Proteomics》2012,1824(9):1016-1023
Metallothioneins (MT) are low molecular weight proteins with cysteine-rich sequences that bind heavy metals with remarkably high affinities. Plant MTs differ from animal ones by a peculiar amino acid sequence organization consisting of two short Cys-rich terminal domains (containing from 4 to 8 Cys each) linked by a Cys free region of about 30 residues. In contrast with the current knowledge on the 3D structure of animal MTs, there is a striking lack of structural data on plant MTs. We have expressed and purified a type III MT from Noccaea caerulescens (previously Thlaspi caerulescens). This protein is able to bind a variety of cations including Cd2+, Cu2+, Zn2+ and Pb2+, with different stoichiometries as shown by mass spectrometry. The protein displays a complete absence of periodic secondary structures as measured by far-UV circular dichroism, infrared spectroscopy and hydrogen/deuterium exchange kinetics. When attached onto a BIA-ATR biosensor, no significant structural change was observed upon removing the metal ions. 相似文献
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134.
Local reflection coefficients (R) provide important insights into the influence of wave reflection on vascular haemodynamics. Using the relatively new time-domain method of wave intensity analysis, R has been calculated as the ratio of the peak intensities (RPI) or areas (RCI) of incident and reflected waves, or as the ratio of the changes in pressure caused by these waves (RΔP). While these methods have not yet been compared, it is likely that elastic non-linearities present in large arteries will lead to changes in the size of waves as they propagate and thus errors in the calculation of RPI and RCI. To test this proposition, RPI, RCI and RΔP were calculated in a non-linear computer model of a single vessel with various degrees of elastic non-linearity, determined by wave speed and pulse amplitude (ΔP+), and a terminal admittance to produce reflections. Results obtained from this model demonstrated that under linear flow conditions (i.e. as ΔP+→0), RΔP is equivalent to the square-root of RPI and RCI (denoted by RPIp and RCIp). However for non-linear flow, pressure-increasing (compression) waves undergo amplification while pressure-reducing (expansion) waves undergo attenuation as they propagate. Consequently, significant errors related to the degree of elastic non-linearity arise in RPI and RCI, and also RPIp and RCIp, with greater errors associated with larger reflections. Conversely, RΔP is unaffected by the degree of non-linearity and is thus more accurate than RPI and RCI. 相似文献
135.
The quantification of arterial wave reflection is an important area of interest in arterial pulse wave analysis. It can be achieved by wave separation analysis (WSA) if both the aortic pressure waveform and the aortic flow waveform are known. For better applicability, several mathematical models have been established to estimate aortic flow solely based on pressure waveforms. The aim of this study is to investigate and verify the model-based wave separation of the ARCSolver method on virtual pulse wave measurements.The study is based on an open access virtual database generated via simulations. Seven cardiac and arterial parameters were varied within physiological healthy ranges, leading to a total of 3325 virtual healthy subjects. For assessing the model-based ARCSolver method computationally, this method was used to perform WSA based on the aortic root pressure waveforms of the virtual patients. As a reference, the values of WSA using both the pressure and flow waveforms provided by the virtual database were taken.The investigated parameters showed a good overall agreement between the model-based method and the reference. Mean differences and standard deviations were −0.05 ± 0.02 AU for characteristic impedance, −3.93 ± 1.79 mmHg for forward pressure amplitude, 1.37 ± 1.56 mmHg for backward pressure amplitude and 12.42 ± 4.88% for reflection magnitude.The results indicate that the mathematical blood flow model of the ARCSolver method is a feasible surrogate for a measured flow waveform and provides a reasonable way to assess arterial wave reflection non-invasively in healthy subjects. 相似文献
136.
Nine hundred and sixty-eight bird species, covering all orders, were studied in search of distinctive ultraviolet reflections. All species in the following orders were completely surveyed: Struthioniformes, Tinamiformes, Craciformes, Turniciformes, Galbuliformes, Upupiformes, Coliiformes, Apodiformes and Musophagiformes. The coloured plumage regions in particular exhibited high proportions of UV-reflecting feathers. Bird orders with species which are believed to possess VS (violet-sensitive) cone types mostly had their UV maxima between 380 and 399 nm while orders with species which are assumed to have UVS (ultraviolet-sensitive) cone types contained significantly species which had their UV maxima between 300 and 379 nm. With an emphasis on non-passerine birds the present study provides evidence that birds of many more groups may see UV light than have been studied to date. Ecological aspects related to UV reflection and perception, as well as sexual dimorphism visible only in the UV, are discussed. 相似文献
137.
Lecithin retinol acyltransferase (LRAT) is a 230 amino acids membrane-associated protein which catalyzes the esterification of all-trans-retinol into all-trans-retinyl ester. The enzymatic activity of a truncated form of LRAT (tLRAT) which contains the residues required for catalysis but which is lacking N- and C-terminal hydrophobic segments has been shown to depend on the detergent used for its solubilization. Moreover, it is unknown whether tLRAT can bind membranes in the absence of these hydrophobic segments. The present study has allowed to measure the membrane binding and hydrolytic action of tLRAT in lipid monolayers by use of polarization modulation infrared reflection absorption spectroscopy and Brewster angle microscopy. Moreover, the proportion of the secondary structure components of tLRAT was determined in three different detergents by infrared absorption spectroscopy, vibrational circular dichroism and electronic circular dichroism which allowed to explain its detergent dependent activity. In addition, the secondary structure of tLRAT in the absence of detergent was very similar to that in Triton X-100 thus suggesting that, compared to the other detergents assayed, the secondary structure of this protein is very little perturbed by this detergent. 相似文献
138.
Synthesis and matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry study of phosphopeptide 总被引:1,自引:0,他引:1
Shi-Zhong Luo Yan-Mei Li Zhong-Zhou Chen Hiroshi Abe Li-Ping Cui Hiroshi Nakanishi Xu-Rong Qin Yu-Fen Zhao 《Letters in Peptide Science》2003,10(1):57-62
The symmetry phosphoramidite reagents were synthesized via atwo-step route and used for the `one pot' synthesis of thephosphoserine building block Fmoc-Ser(PO(OBzl)OH)-OH. Theprocedure is simple and rapid, and product is obtained in highyield. When using this building block, the phosphopeptide(RKGS(PO3H2)SSNEPSSDSLSSPTLLAL) related to theC-terminal of c-Fos protein was synthesized manually byFmoc/t-Bu procedure and characterized by matrix assisted laserdesorption/ionization time of flight (MALDI-TOF) massspectrometry. In the fragment ion of phosphopeptide in theMALDI-TOF mass spectrometry with a curved field reflection, theacquired information can be used to identify the sequences andthe phosphorylation sites of the peptide. 相似文献
139.
140.
Left,right or both? Estimating and improving accuracy of one‐side‐only geometric morphometric analyses of cranial variation 下载免费PDF全文
Procrustes‐based geometric morphometric analyses of bilaterally symmetric structures are often performed using only one side. This is particularly common in studies of cranial variation in mammals and other vertebrates. When one is not interested in quantifying asymmetry, landmarking one side, instead of both, reduces the number of variables as well as the time and costs of data collection. It is assumed that the loss of information in the other half, on which landmarks are not digitized, is negligible, but this has seldom been tested. Using 10 samples of mammalian crania and a total of more than 500 specimens, and five different landmark configurations, I demonstrate that this assumption is indeed easily met for size. For shape, in contrast, one‐side landmarking has potentially more severe consequences on the estimates of similarity relationships in a sample. In this respect, microevolutionary analyses of small differences are particularly affected, whereas macroevolutionary studies are fairly robust. In almost all instances, however, a simple preliminary operation improves accuracy by making one‐side‐only shape data more similar to those obtained by landmarking both sides. The same operation also makes estimates of allometry more accurate and improves the visualization. This operation consists in estimating the missing side by a mirror reflection of bilateral landmarks. In the Supporting Information, I exemplify how this can be easily done using free user‐friendly software. I also provide an example data set for readers to repeat and learn the steps of this simple procedure. 相似文献