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Signatures
Kinds of Signatures Terms modified by Signatures Selected AbstractsRIVER CAPTURE, RANGE EXPANSION, AND CLADOGENESIS: THE GENETIC SIGNATURE OF FRESHWATER VICARIANCEEVOLUTION, Issue 5 2006C. P. Burridge Abstract River capture is potentially a key geomorphological driver of range expansion and cladogenesis in freshwater-limited taxa. While previous studies of freshwater fish, in particular, have indicated strong relationships between historical river connections and phylogeographic pattern, their analyses have been restricted to single taxa and geological hypotheses were typically constructed a posteriori. Here we assess the broader significance of river capture among taxa by testing multiple species for the genetic signature of a recent river capture event in New Zealand. During the Quaternary an upper tributary of the Clarence River system was diverted into the headwaters of the Wairau River catchment. Mitochondrial DNA (control region and cytochrome b) sequencing of two native galaxiid fishes (Galaxias vulgaris and Galaxias divergens) supports headwater exchange: populations from the Clarence and Wairau Rivers are closely related sister-groups, whereas samples from the geographically intermediate Awatere River are genetically divergent. The upland bully Gobiomorphus breviceps (Eleotridae), in contrast, lacks a genetic signature of the capture event. We hypothesize that there is an increased likelihood of observing genetic signatures from river capture events when they facilitate range expansion, as is inferred for the two galaxiid taxa studied here. When river capture merely translocates genetic lineages among established populations, by contrast, we suggest that the genetic signature of capture is less likely to be retained, as might be inferred for G. breviceps. Rates of molecular evolution calibrated against this recent event were elevated relative to traditional estimates, consistent with the contribution of polymorphisms to branch lengths at shallow phylogenetic levels prior to fixation by purifying selection and drift. [source] DETECTING THE HISTORICAL SIGNATURE OF KEY INNOVATIONS USING STOCHASTIC MODELS OF CHARACTER EVOLUTION AND CLADOGENESISEVOLUTION, Issue 2 2005Richard H. Ree Abstract Phylogenetic evidence for biological traits that increase the net diversification rate of lineages (key innovations) is most commonly drawn from comparisons of clade size. This can work well for ancient, unreversed traits and for correlating multiple trait origins with higher diversification rates, but it is less suitable for unique events, recently evolved innovations, and that exhibit homoplasy. Here I present a new method for detecting the phylogenetic signature of key innovations that tests whethere the evolutionary history of the candidate trait is associated with shorter waiting times between cladogenesis events. The method employs stochastic models of character evolution and cladogenesis and integrates well into a Bayesian framework in which uncertainty in historical inferences (such as phylogenetic relationships) is allowed. Applied to a well-known example in plants, nectar spurs in columbines, the method gives much stronger support to the key innovation hypothesis than previous tests. [source] CLIMATIC VARIABILITY ALONG A NORTH,SOUTH TRANSECT OF FINLAND OVER THE LAST 500 YEARS: SIGNATURE OF SOLAR INFLUENCE OR INTERNAL CLIMATE OSCILLATIONS?GEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2 2008MAXIM G. OGURTSOV ABSTRACT. Statistical analysis of a multi-centennial dendrochronological proxy dataset of regional climate, constructed across the latitudinal gradient of 1000 km, was performed. It was shown that centennial (c. 100 year), tri-decadal (27-32 year), bi-decadal (17-23 year) and decadal (9-13 year) periodicities governed the climate variability in Finland over the last five centuries. Despite the fact that many of the climatic periodicities bore great resemblance to periodicities of solar cycles, little evidence of actual solar influence on Finnish climate was found when the climate proxy records were subjected to linear correlation analysis with sunspot numbers. Highly non-linear response of Northern Fennoscandian climate to solar forcing might be a cause of this result, as well as influence of terrestrial climatic processes (e.g. effect of other forcing factors and internal dynamics of regional climate). Our results show that the presence of internal climate variability at time-scales of solar activity might distort the solar signature in climatic data and complicate its detection. [source] PSYCHOPHYSIOLOGICAL SIGNATURES OF APPRAISALPSYCHOPHYSIOLOGY, Issue S1 2005Article first published online: 15 AUG 200 No abstract is available for this article. [source] THE POTENTIAL OF CARBONIZED GRAIN TO PRESERVE BIOGENIC 87SR/86SR SIGNATURES WITHIN THE BURIAL ENVIRONMENT*ARCHAEOMETRY, Issue 2 2009A. HEIER Carbonized grains survive for millennia in many archaeological contexts. Their stable structure raises the possibility that they preserve biogenic strontium isotope signatures. This hypothesis was investigated using short-term, laboratory experiments with modern grain immersed in Chalk solution. HCl leaching removed > 95% of secondary alteration from charred grain, and isotope ratios close to the starting value were recovered. This could not be achieved with uncharred grains. HCl leaching of archaeological carbonized grains produced comparable levels of decontamination. Although preliminary, these results suggest that strontium isotope analysis of archaeological carbonized grains from calcareous burial contexts could be used to investigate ancient trade and agriculture. [source] SIGNPOSTS OF INVENTION: ARTISTS' SIGNATURES IN ITALIAN RENAISSANCE ARTART HISTORY, Issue 4 2006PATRICIA RUBIN The opening lines of Dante Alighieri's Divine Comedy provide the starting point for a consideration of the ways that artists inscribed themselves within their works during the Renaissance. This is a matter both of signatures and of authorial complicity. This article examines how signatures were defined in the period and how they were used in a process of artistic definition. Conventions of inscription are outlined, and four particularly inventive instances (Fra Filippo Lippi, Donatello, Michelangelo and Titian) are considered in greater detail to show how artists' names could be used to direct the viewer's experience of their works and appreciation of their authorship. [source] Echocardiographic Signature of the On-X ValveECHOCARDIOGRAPHY, Issue 9 2008Aaron B. Yezbick M.D. No abstract is available for this article. [source] Wilson's Storm Petrels Oceanites oceanicus Recognise the Olfactory Signature of Their MateETHOLOGY, Issue 12 2007Pierre Jouventin Chemical signals in birds have rarely been considered as recognition cues. Nevertheless, recent experiments showed that several petrel species are able to recognize their nest by smell, and in at least one species even their mate. But the use of smell may be different across the petrel species and olfactory nest recognition appears to be dependent on species' breeding biology. To increase our knowledge of individual olfactory recognition in petrels and the relationships between breeding biology and use of smell, we tested Wilson's storm petrels Oceanites oceanicus in Antarctica. In previous experiments, these birds failed to home if rendered anosmic, but the method employed to obtain anosmia (potentially stressing birds) and the fact that they breed in 24-h daylight suggest that they might use visual, rather than olfactory, cues to recognize their nest. Our birds were tested in T-maze experiments where nest odours or partner odours were presented. Wilson's storm petrels preferred odours of their own nest and mate. Results on olfactory nest recognition confirm and complete previous results, viz. anosmic Wilson's storm petrels do not home. Storm petrels olfactory mate recognition suggests that this ability may be widespread in burrowing petrels and implements olfactory nest recognition. [source] Virtual path signature: An approach for flexible searching in object-oriented databasesINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 1-2 2004Pichayotai Mahatthanapiwat Signature technique that is proposed for multikey indexing is used for flexible searching in the area of databases. In this article, we present a new signature technique called Virtual Path Signature for supporting query processing of aggregation hierarchy as a tree in object-oriented databases (OODBs). We derive cost formulas for its storage overhead as well as the retrieval cost. Comparing with the Tree Signature Scheme, the Virtual Path Signature shows significant improvement in the retrieval operation, especially when the target distance between the target class and the predicate class is high. © 2004 Wiley Periodicals, Inc. [source] Validation of a bedside activated clotting time test (Hemochron® Jr II Signature) with low dose heparin therapyANAESTHESIA, Issue 4 2009L. Racioppi Summary The purpose of this study was to validate a device designed to measure activated clotting time in low-range heparin plasma concentrations (ACT-LR) prospectively during the post-operative period of vascular surgery. Measurement of ACT-LR and activated partial thromboplastin time (APTT) were performed before heparinisation (T0) and at the end of surgery (T1). ACT-LR(T1) and ,ACT-LR (defined as ACT-LR(T1) , ACT-LR(T0)) were evaluated as diagnostic tests for excessive anticoagulation, defined by APTT more than twice the laboratory's normal, by Bland-Altman method and receiver operating characteristic (ROC) curves. In 103 patients, mean (SD) ACT-LR was 137 (33) s at T0 and 176 (39) s at T1. Bland-Altman graph did not show a good agreement between APTT and ACT-LR. Areas under ROC curves were 0.82 (95% CI: 0.75,0.89) and 0.87 (95% CI: 0.80,0.93) for ACT-LR(T1) and ,ACT-LR, respectively. Using a threshold of 32 s for ,ACT-LR, test sensitivity was 87% (95% CI: 81,93%), specificity was 85% (95% CI: 78,92%), positive predictive value was 90% (95% CI: 84,96%) and negative predictive value was 81% (95% CI: 73,86%). While ,ACT-LR may have some potential in evaluating excessive anticoagulation in vascular surgery, the poor correlation between ACT-LR and APTT does not support its routine use. [source] Signature of the Baltic Ice Stream on Funen Island, Denmark during the Weichselian glaciationBOREAS, Issue 1 2003FLEMMING JØRGENSEN Ice streams are major dynamic elements of modern ice sheets, and are believed to have significantly influenced the behaviour of past ice sheets. Funen Island exhibits a number of geomorphological and geological features indicative of a Late Weichselian ice stream, a land-based, terminal branch of the major Baltic Ice Stream that drained the Scandinavian Ice Sheet along the Baltic Sea depression. The ice stream in the study area operated during the Young Baltic Advance. Its track on Funen is characterized by a prominent drumlin field with long, attenuated drumlins consisting of till. The field has an arcuate shape indicating ice-flow deflection around the island's interior. Beneath the drumlin-forming till is a major erosional surface with a boulder pavement, the stones of which have heavily faceted and striated upper surfaces. Ploughing marks are found around the boulders. Exact correspondence of striations, till fabric and drumlin orientation indicates a remarkably consistent flow direction during ice streaming. We infer that fast ice flow was facilitated by basal water pressure elevated to the vicinity of the flotation point. The ice movement was by basal sliding and bed deformation under water pressure at the flotation level or slightly below it, respectively. Subglacial channels and eskers post-dating the drumlins mark a drainage phase that terminated the ice-stream activity close to the deglaciation. Identification of other ice streams in the Peribaltic area is essential for better understanding the dynamics of the land-based part of the Scandinavian Ice Sheet during the last glaciation. [source] A Stem Cell Molecular Signature: Are There Hallmark Properties That are Shared by all Stem Cells?CHEMBIOCHEM, Issue 8 2003Ute Schepers Dr. Where does the problem stem from? A major breakthrough was made toward the identification of genes (see figure) that give stem cells their unique properties. This "stem cell molecular signature" or the "genetic blueprint" will certainly offer a powerful resource for understanding some of the stem-cell-related diseases and will become a basis for new experiments on the therapeutic application of stem cells. [source] Diversity of the Vocal Signals of Concave-Eared Torrent Frogs (Odorrana tormota): Evidence for Individual SignaturesETHOLOGY, Issue 11 2009Albert S. Feng Male concave-eared torrent frogs (Odorrana tormota) have an unusually large call repertoire and have been shown to communicate ultrasonically. We investigated the individual specificity of male advertisement calls in order to explore the acoustic bases of individual recognition, which was demonstrated in an accompanying study. Vocalizations of 15 marked males were recorded in the field. A quantitative analysis of the signals revealed eight basic call-types. Two of them (the single- and multi-note long-calls) were investigated in more detail. Long-calls were characterized by pronounced and varying frequency modulation patterns, and abundant occurrence of nonlinear phenomena (NLP), i.e., frequency jumps, subharmonics, biphonations and deterministic chaos. The occurrence of NLP was predictable from the contour of the fundamental frequency in the harmonic segment preceding the onset of the NLP, and this prediction showed individual-specific patterns. Fifteen acoustic variables of the long calls were measured, all of which were significantly different among individuals, except biphonic segment duration. Discriminant function analysis (DFA) showed that 54.6% of the calls could be correctly assigned to individual frogs. The correct classification was above chance level, suggesting that individual specificity of calls underlie the ability of males to behaviorally discriminate the vocal signals of their neighbors from those of strangers, a remarkable feat for a frog species with a diverse vocal repertoire. The DFA classification results were lower than those for other anurans, however. We hypothesize that there is a tradeoff between an increase in the fundamental frequency of vocalizations to avoid masking by low-frequency ambient background noise, and a decrease in individual-specific vocal tract information extractable from the signal. [source] "Grab the Signatures and Run": Federal Unity Strategy in Canada from the Referendum to PatriationINTERNATIONAL POLITICAL SOCIOLOGY, Issue 2 2009Neal Carter Whether as a traumatic event or great accomplishment, the legacy of the First Ministers' Conference of 1981 lives on in Canadian politics. Constitutional negotiations among the prime minister and provincial premiers in 1981 produced the only "packaged" agreement since Confederation to achieve even the minimal support necessary to achieve ratification. The resulting Constitution Act of 1982, which included the Charter of Rights and Freedoms, remains in place and is the principal manifestation of intergovernmental bargaining from over two decades ago. This study reevaluates the strategic interaction and conflict processes that took place between Ottawa and the provinces in negotiations leading up to that fateful November 1981 conference. We apply the sociological framework for assessment of the dynamics of identity contention adopted from McAdam, Tarrow, and Tilly (2001) and find tentative support for its propositions. After an overview of the article's agenda, we present an analytic framework for the study of conflict processes. Second, the background to the constitutional crisis of 1980-81 is summarized. Using the analytic framework, the third section focuses on the federal strategy in the crisis as suggested by minutes from cabinet meetings, and the fourth section examines key events of the First Ministers Conference of November 1981. Fifth, and finally, the contributions of the preceding sections are summed up and ideas are put forward for further research. [source] An Insight into Forensic Document Examiner Expertise for Discriminating Between Forged and Disguised SignaturesJOURNAL OF FORENSIC SCIENCES, Issue 5 2008Adrian G. Dyer Ph.D. Abstract:, It has previously been shown that forensic document examiners (FDEs) have expertise in providing opinions about whether questioned signatures are genuine or simulated. This study extends the exploration of FDE expertise by evaluating the performance of eight FDEs and 12 control subjects at identifying signatures as either forgeries or the disguised writing of a specimen provider. Subject eye movements and response times were recorded with a Tobii 1750 eye tracker during the signature evaluations. Using a penalty scoring system, FDEs performed significantly better than control subjects (t = 2.465, p = 0.024), with one FDE able to correctly call 13 of the 16 test stimuli (and three inconclusive calls). An analysis of eye movement search patterns by the subjects indicated that a very similar search strategy was employed by both groups, suggesting that visual inspection of signatures is mediated by a bottom up search strategy. However, FDEs spent greater than 50% longer to make a decision than the control group. The findings are suggestive that for some stimuli FDEs can discriminate between forgeries and disguises, and that this ability is due to a careful inspection and consideration of multiple features within a signature. [source] Dynamical model for coherent optical manipulation of a single spin state in a charged quantum dotPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2009Gabriela Slavcheva Abstract The optically-induced coherent spin dynamics of a single spin confined in a charged quantum dot (QD) is theoretically studied employing coupled vector Maxwell-pseudospin formalism. Generalized pseudospin master equation is derived for description of the time evolution of spin coherences and spin populations including spin population transfer and dissipation in the system through spin relaxation processes. The equation is solved in the time domain self-consistently with the vector Maxwell equations for the optical wave propagation coupled to it via macroscopic medium polarisation. Using the model the long-lived electron spin coherence left behind a single resonant ultrashort optical excitation of the electron-trion transition in a charged QD is simulated in the low- and high-intensity Rabi oscillations regime. Signatures of the polarised photoluminescence (PL), predicted by the model, such as the appearance of a second echo pulse after the excitation and characteristic PL trace shape, are discussed for realization of high-fidelity schemes for coherent readout of a single spin polarisation state. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Gene duplications and the time thereafter , examples from plant secondary metabolismPLANT BIOLOGY, Issue 4 2010D. Ober Abstract Gene duplications are regarded as one of the central mechanisms for the origin of new genes. Recent studies in plant secondary metabolism have provided several examples of genes that originated by duplication with successive diversification. In this review, the mechanisms of gene duplication are explained and several models discussed that suggest the way that gene duplicates develop into genes with new functions. Signatures of gene duplication and diversification processes are discussed using the biosynthesis of benzoxazinones and of pyrrolizidine alkaloids as examples. [source] Automatic generation and evaluation of sparse protein signatures for families of protein structural domainsPROTEIN SCIENCE, Issue 1 2005Matthew J. Blades Abstract We identified key residues from the structural alignment of families of protein domains from SCOP which we represented in the form of sparse protein signatures. A signature-generating algorithm (SigGen) was developed and used to automatically identify key residues based on several structural and sequence-based criteria. The capacity of the signatures to detect related sequences from the SWISSPROT database was assessed by receiver operator characteristic (ROC) analysis and jack-knife testing. Test signatures for families from each of the main SCOP classes are described in relation to the quality of the structural alignments, the SigGen parameters used, and their diagnostic performance. We show that automatically generated signatures are potently diagnostic for their family (ROC50 scores typically >0.8), consistently outperform random signatures, and can identify sequence relationships in the "twilight zone" of protein sequence similarity (<40%). Signatures based on 15%,30% of alignment positions occurred most frequently among the best-performing signatures. When alignment quality is poor, sparser signatures perform better, whereas signatures generated from higher-quality alignments of fewer structures require more positions to be diagnostic. Our validation of signatures from the Globin family shows that when sequences from the structural alignment are removed and new signatures generated, the omitted sequences are still detected. The positions highlighted by the signature often correspond (alignment specificity >0.7) to the key positions in the original (non-jack-knifed) alignment. We discuss potential applications of sparse signatures in sequence annotation and homology modeling. [source] Rotational Spectral Signatures of Four Tautomers of Guanine,ANGEWANDTE CHEMIE, Issue 33 2009Ultraschnell: Das Rotationsspektrum von Guanin wurde mithilfe der Laserabtragungs-Molekularstrahl-Fourier-Transformations-Mikrowellen(LA-MB-FTMW)-Spektroskopie untersucht. Die N7H-Keto-, N9H-Keto-, N9H-Enol- trans - und N9H-Enol- cis -Formen (siehe Strukturen) wurden zweifelsfrei in der Überschallexpansion anhand der experimentellen Werte der Rotationskonstanten identifiziert. [source] Gene expression profiling in autoantibody-positive patients with arthralgia predicts development of arthritis,ARTHRITIS & RHEUMATISM, Issue 3 2010Lisa G. M. van Baarsen Objective To identify molecular features associated with the development of rheumatoid arthritis (RA), to understand the pathophysiology of preclinical development of RA, and to assign predictive biomarkers. Methods The study group comprised 109 anti,citrullinated protein antibody (ACPA), and/or rheumatoid factor,positive patients with arthralgia who did not have arthritis but were at risk of RA, and 25 patients with RA. The gene expression profiles of blood samples obtained from these patients were determined by DNA microarray analysis and quantitative polymerase chain reaction. Results In 20 of the 109 patients with arthralgia who were at risk of RA, arthritis developed after a median of 7 months. Gene expression profiling of blood cells revealed heterogeneity among the at-risk patients, based on differential expression of immune-related genes. This report is the first to describe gene signatures relevant to the development of arthritis. Signatures significantly associated with arthritis development were involved in interferon (IFN),mediated immunity, hematopoiesis, and chemokine/cytokine activity. Logistic regression analysis revealed that the odds ratio (OR) for developing arthritis within 12 months was 21.0 (95% confidence interval [95% CI] 2.8,156.1 [P = 0.003]) for the subgroup characterized by increased expression of genes involved in IFN-mediated immunity and/or cytokine/chemokine-activity. Genes involved in B cell immunology were associated with protection against progression to arthritis (OR 0.38, 95% CI 0.21,0.70 [P = 0.002]). These processes were reminiscent of those in patients with RA, implying that the preclinical phase of disease is associated with features of established disease. Conclusion The results of this study indicate that IFN-mediated immunity, hematopoiesis, and cell trafficking specify processes relevant to the progression of arthritis independent of ACPA positivity. These findings strongly suggest that certain gene signatures have value for predicting the progression to arthritis, which will pave the way to preventive medicine. [source] Windows to cell function and dysfunction: Signatures written in the boundary layersBIOESSAYS, Issue 6 2010Peter J. S. Smith Abstract The medium surrounding cells either in culture or in tissues contains a chemical mix varying with cell state. As solutes move in and out of the cytoplasmic compartment they set up characteristic signatures in the cellular boundary layers. These layers are complex physical and chemical environments the profiles of which reflect cell physiology and provide conduits for intercellular messaging. Here we review some of the most relevant characteristics of the extracellular/intercellular space. Our initial focus is primarily on cultured cells but we extend our consideration to the far more complex environment of tissues, and discuss how chemical signatures in the boundary layer can or may affect cell function. Critical to the entire essay are the methods used, or being developed, to monitor chemical profiles in the boundary layers. We review recent developments in ultramicro electrochemical sensors and tailored optical reporters suitable for the task in hand. [source] Bayesian Variable Selection in Multinomial Probit Models to Identify Molecular Signatures of Disease StageBIOMETRICS, Issue 3 2004Naijun Sha Summary Here we focus on discrimination problems where the number of predictors substantially exceeds the sample size and we propose a Bayesian variable selection approach to multinomial probit models. Our method makes use of mixture priors and Markov chain Monte Carlo techniques to select sets of variables that differ among the classes. We apply our methodology to a problem in functional genomics using gene expression profiling data. The aim of the analysis is to identify molecular signatures that characterize two different stages of rheumatoid arthritis. [source] Geochemical Signatures of Early Paleogene Source Rocks in the Sanshui Basin, South ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010Chunlian LIU Abstract: The Honggang member of the early Paleogene Buxin Formation is the main source rock in the Sanshui Basin, characterized by organic-rich black shales with the cyclic recurrence of organic-poor sediments. The geochemical characteristics of the Honggang member have been documented to determine the organic matter types and depositional environments in this paper. The organic matter of the black shales mainly consists of a mixture of land plant-derived and phytoplankton-derived organic matter. Total organic carbon content (TOC)-sulfur-iron (Fe) relationships suggest that the organic-rich black shales were deposited under dysoxic-to-euxinic water conditions. The time that iron minerals remained in contact with H2S in anoxic waters possibly influenced the formation of syngenetic pyrite, and organic carbon controlled the formation of diagenetic pyrite. Organic-poor intervals usually show pyrite sulfur enrichment and higher degree of pyritization values relative to low organic carbon contents. This resulted from HS, diffusing downward from overlying organic-rich sediments and formed Fe sulfides through reactions with sufficient Fe. Trace elements generally exhibit low concentrations and little TOC dependence, suggesting some degree of depletion in these elements in the early Paleogene sediments of the Sanshui Basin. This probably resulted from cyclic recurrences of oxic benthic conditions, which promoted the remobilization of trace elements and caused the low concentration of trace elements. [source] ChemInform Abstract: Modeling of the Phase Evolution in Mg1-xAlxB2 (0 < x < 0.5) and Its Experimental Signatures.CHEMINFORM, Issue 44 2009David A. Andersson Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Spectral Signatures of the Pentagonal Water Cluster in BacteriorhodopsinCHEMPHYSCHEM, Issue 18 2008Marcel Baer Computed QM/MM IR spectra of the water molecules in the Schiff base region of bacteriorhodopsin (see figure) confirm a dangling bond at about 3600 cm,1. A broad experimental IR absorption band at 2800 cm,1 is assigned to a coupling of the Schiff base NH and the OH stretch of a ligand water molecule. [source] Calculated Raman Optical Activity Signatures of Tryptophan Side ChainsCHEMPHYSCHEM, Issue 15 2008Christoph R. Jacob Dr. Raman optical activity: The different local chirality of an adjacent group can cause a different sign of the ROA intensity of an amino-acid side chain (here tryptophan, see picture centre), even though the normal mode is unchanged. Calculated spectra clearly confirm that ROA spectroscopy can be utilized to determine the absolute conformation of tryptophan side chains in proteins (see figure, left and right). [source] Theoretical Determination of the Vibrational Raman Optical Activity Signatures of Helical Polypropylene ChainsCHEMPHYSCHEM, Issue 11 2006Ewa Lamparska Abstract Raman and vibrational Raman optical activity (VROA) spectra of helical conformers of polypropylene chains are simulated using ab initio methods to unravel the relationships between the vibrational signatures and the primary and secondary structures of the chains. For a polypropylene chain containing three units, conformational effects are shown to lead to more acute signatures for VROA than for Raman spectra. In addition to regular polypropylene chains, which can display right and left helicities with the same probability, chirality and therefore helicity are enforced by substituting one chain end with a phenyl group. The simulations predict that the threefold helical structures, which correspond to (TG)N conformations of the backbone, have a specific VROA backward signature in the form of an intense couplet around 1100 cm,1. This couplet is associated with collective wagging and twisting motions, while most of its intensity comes from the anisotropic invariants combining normal coordinate derivatives of the electric dipole,electric dipole polarizability and of the electric dipole,magnetic dipole polarizability. A similar signature has already been found in model helical polyethylene chains, whereas it is very weak in forward VROA. [source] The Flavobacterium psychrophilum OmpA, an outer membrane glycoprotein, induces a humoral response in rainbow troutJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2007F. Dumetz Abstract Aims:, The purpose of this study was to characterize OmpA, a major glycoprotein isolated from the membrane fraction of Flavobacterium psychrophilum, and to evaluate its potential as antigenic unit in a possible vaccine. Methods and Results:, The expression product of ompA is a 465-amino-acid protein precursor that contains a 21-amino acid signal peptide and has overall homology (up to 60% identity) with similarly sized proteins of some bacteria belonging to the Flavobacteriaceae family. The carboxy-terminal region contains the ,OmpA/MotB' domain/signature and five putative ,Thrombospondin type 3 repeats' domains have been identified in the central region. OmpA was clearly detected in the outer membrane fraction and its surface exposure was demonstrated. OmpA is one of the immunodominant antigens and binding of specific anti-OmpA antibodies lead to cell lysis in the presence of complement. Fish immunized with OmpA emulsified with Freund's adjuvant developed a high antibody titter. Conclusions:, Collectively, the data obtained here indicate that OmpA may be involved in Fl. psychrophilum/host cell interactions and appears to be a potential immunogen for a vaccine. Significance and Impact of the Study:, This study is one step in the direction of understanding pathogenesis of Fl. psychrophilum and development of future vaccine. [source] Sparse points matching by combining 3D mesh saliency with statistical descriptorsCOMPUTER GRAPHICS FORUM, Issue 2 2008U. Castellani Abstract This paper proposes new methodology for the detection and matching of salient points over several views of an object. The process is composed by three main phases. In the first step, detection is carried out by adopting a new perceptually-inspired 3D saliency measure. Such measure allows the detection of few sparse salient points that characterize distinctive portions of the surface. In the second step, a statistical learning approach is considered to describe salient points across different views. Each salient point is modelled by a Hidden Markov Model (HMM), which is trained in an unsupervised way by using contextual 3D neighborhood information, thus providing a robust and invariant point signature. Finally, in the third step, matching among points of different views is performed by evaluating a pairwise similarity measure among HMMs. An extensive and comparative experimental session has been carried out, considering real objects acquired by a 3D scanner from different points of view, where objects come from standard 3D databases. Results are promising, as the detection of salient points is reliable, and the matching is robust and accurate. [source] Optical studies on ZnO films prepared by sol-gel methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2009T. Ghosh Abstract A standard sol-gel method was used to deposit ZnO thin films of suitable thickness on glass substrate. The optical characteristics of the visible to infrared range on thermal stress were critically observed. Morphological signature of the films was detected by X-ray diffraction (XRD) and the crystallite size determined by Scherrer method from XRD data were consistent with grain size estimated from spectroscopic data through Meulenkamp equation. The optical band gap value from the transmission spectrum was found to corroborate with the existing works. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||||||||||||||||||||||||||||||||