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Varying Number (varying + number)
Selected AbstractsAllee effect in larval resource exploitation in Drosophila: an interaction among density of adults, larvae, and micro-organismsECOLOGICAL ENTOMOLOGY, Issue 5 2002Bregje Wertheim Abstract 1. Aggregation pheromones can evolve when individuals benefit from clustering. Such a situation can arise with an Allee effect, i.e. a positive relationship between individual fitness and density of conspecifics. Aggregation pheromone in Drosophila induces aggregated oviposition. The aim of the work reported here was to identify an Allee effect in the larval resource exploitation by Drosophila melanogaster, which could explain the evolution of aggregation pheromone in this species. 2. It is hypothesised that an Allee effect in D. melanogaster larvae arises from an increased efficiency of a group of larvae to temper fungal growth on their feeding substrate. To test this hypothesis, standard apple substrates were infested with specified numbers of larvae, and their survival and development were monitored. A potential beneficial effect of the presence of adult flies was also investigated by incubating a varying number of adults on the substrate before introducing the larvae. Adults inoculate substrates with yeast, on which the larvae feed. 3. Fungal growth was related negatively to larval survival and the size of the emerging flies. Although the fungal growth on the substrate was largely reduced at increased larval densities, the measurements of fitness components indicated no Allee effect between larval densities and larval fitness, but rather indicated larval competition. 4. In contrast, increased adult densities on the substrates prior to larval development yielded higher survival of the larvae, larger emerging flies, and also reduced fungal growth on the substrates. Hence, adults enhanced the quality of the larval substrate and significant benefits of aggregated oviposition in fruit flies were shown. Experiments with synthetic pheromone indicated that the aggregation pheromone itself did not contribute directly to the quality of the larval resource. 5. The interaction among adults, micro-organisms, and larval growth is discussed in relation to the consequences for total fitness. [source] Relation of apical dendritic spikes to output decision in CA1 pyramidal cells during synchronous activation: a computational studyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2006José M. Ibarz Abstract Recent studies on the initiation and propagation of dendritic spikes have modified the classical view of postsynaptic integration. Earlier we reported that subthreshold currents and spikes recruited by synaptic currents play a critical role in defining outputs following synchronous activation. Experimental factors strongly condition these currents due to their nonlinear behaviour. Hence, we have performed a detailed parametric study in a CA1 pyramidal cell model to explore how different variables interact and initiate dendritic spiking, and how they influence cell output. The input pattern, the relative excitability of axon and dendrites, the presence/modulation of voltage-dependent channels, and inhibition were cross analysed. Subthreshold currents and spikes on synaptically excited branches fired spikes in other branches to jointly produce different modalities of apical shaft spiking with a variable impact on cell output. Synchronous activation initiated a varying number and temporal scatter of firing branches that produced in the apical shaft-soma axis nonpropagating spikes, pseudosaltatory or continuous forward conduction, or backpropagation. As few as 6,10 local spikes within a time window of 2 ms ensure cell output. However, the activation mode varied extremely when two or more variables were cross-analysed, becoming rather unpredictable when all the variables were considered. Spatially clustered inputs and upper modulation of dendritic Na+ or Ca2+ electrogenesis favour apical decision. In contrast, inhibition biased the output decision toward the axon and switched between dendritic firing modes. We propose that dendrites can discriminate input patterns and decide immediate cell output depending on the particular state of a variety of endogenous parameters. [source] When more observations are better than less: a connectionist account of the acquisition of causal strengthEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 2 2001Frank Van Overwalle The statistical law of large numbers prescribes that estimates are more reliable and accurate when based on a larger sample of observations. This effect of sample size was investigated on causal attributions. Subjects received fixed levels of consensus and distinctiveness covariation, and attributions were measured after a varying number of trials. Whereas prominent statistical models of causality (e.g. Cheng & Novick, 1990; Försterling, 1992) predict no effect of sample size, adaptive connectionist models (McClelland & Rumelhart, 1988) predict that subjects will incrementally adjust causal ratings in the direction of the true covariation the more observations are made. In three experiments, sample size effects were found consistent with the connectionist prediction. Possible extensions of statistical models were considered and simulated, but none of them accommodated the data as well as connectionist models. Copyright © 2001 John Wiley & Sons, Ltd. [source] Multi-user detection in OFDM systems using CDMA and multiple antennasEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2003Christoph Degen This paper deals with linear multi-user detection in orthogonal frequency division multiplexing (OFDM) systems. The separation of concurrently transmitted signals is based on space division and code division multiple access (SD/CDMA). The examined OFDM schemes are compared against frequency domain equalization for single-carrier transmission schemes (SC/FDE). Both show strong similarities. Therefore in this paper, we focus on a unified treatment of multi-user detection systems based on OFDM or SC/FDE. The trade-off between exploitation of diversity and user separation is analyzed for different spreading techniques and a varying number of receive antennas. The performance is evaluated in terms of both uncoded and coded bit error ratio (BER). Furthermore, a novel time domain spreading technique for OFDM systems is proposed for which the peak-to-average transmitter power ratio (PAPR) is independent of the applied spreading code. Copyright © 2004 AEI [source] Fly ash concrete subjected to thermal cyclic loadsFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2010M. S. KHAN ABSTRACT The present study describes the behaviour of concrete as well as fly ash concrete when subjected to varying number of high temperature heating cycles. A Concrete mix (1:2.37:2.98) with 340 kg/m3 cement and,w/cm,ratio 0.45 was prepared. Cement was replaced by varying percentages (0%, 20%, 40%, 50% and 60%) of fly ash by weight of cement. The concrete was subjected to a constant temperature of 200°C for 7, 14, 21 and 28 heating cycles. One heating cycle corresponds to 8 h heating and subsequent cooling in 24 h. Subsequently the effect of temperature on the properties of the concrete was investigated and compared with that of the properties of unheated concrete. The compressive strength of plain as well as fly ash concrete increased when it was subjected to thermal cyclic loads. Moreover, the compressive strength increased with an increase in number of heating cycles. Thermal conductivity of concrete was found to decrease with an increase in the fly ash content. [source] Thin Films of Insoluble Poly(Oligothienylene vinylenes) Prepared by Chemical Vapor Deposition Polymerization,ADVANCED FUNCTIONAL MATERIALS, Issue 13 2007S.-H. Joo Abstract A series of poly(oligothienylene vinylenes) (PTmVs, m,=,2,4) with a varying number of consecutively bound thienylene rings are successfully prepared in thin films by chemical vapor deposition polymerization (CVDP) using the corresponding bis(halomethyl)thiophenes as starting materials. The chemical and electronic structures are studied spectroscopically and also by cyclic voltammetry. Top-gate field-effect transistors are fabricated by two consecutive CVDP cycles of PTmV and poly(p -xylylene) followed by the deposition of a Au gate electrode. In the case of a PT3V active layer, a field-effect mobility value of 0.5,×,10,4,cm2,V,1,s,1 is obtained. [source] A Characterization Study of a Nanowire-Network Transistor with Various Channel LayersADVANCED MATERIALS, Issue 41 2009Jae Eun Jang The performance of a ZnO network transistor is studied by means of the change in threshold slope with varying number of nanowire channel layers. The threshold slope broadens as the number of layers in the channel increases and, in the case of a two-layer channel, a double turn-on effect can be observed. The gate-field simulation shows gate-field distortion by the surface of the nanowire. [source] Growing Sovereignty: Modeling the Shift from Indirect to Direct RuleINTERNATIONAL STUDIES QUARTERLY, Issue 1 2010Lars-Erik Cederman Drawing on theories of historical sociology, we model the emergence of the territorial state in early modern Europe. Our modeling effort focuses on systems change with respect to the shift from indirect to direct rule. We first introduce a one-dimensional model that captures the tradeoff between organizational and geographic distances. In a second step, we present an agent-based model that features states with a varying number of organizational levels. This model explicitly represents causal mechanisms of conquest and internal state-building through organizational bypass processes. The computational findings confirm our hypothesis that technological change is sufficient to trigger the emergence of modern, direct-state hierarchies. Our theoretical findings indicate that the historical transformation from indirect to direct rule presupposes a logistical, rather than the commonly assumed exponential, form of the loss-of-strength gradient. [source] Effect of dexamethasone withdrawal on osteoblastic differentiation of bone marrow stromal cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2003Ryan M. Porter Abstract Dexamethasone is capable of directing osteoblastic differentiation of bone marrow stromal cells (BMSCs) in vitro, but its effects are not lineage-specific, and sustained exposure has been shown to down-regulate collagen synthesis and induce maturation of an adipocyte subpopulation within BMSC cultures. Such side effects might be reduced if dexamethasone is applied in a regimented manner, but the discrete steps in osteoblastic maturation that are stimulated by dexamethasone are not known. To examine this, dexamethasone was added to medium to initiate differentiation of rat BMSCs cultures and then removed after a varying number of days. Cell layers were analyzed for cell number, rate of collagen synthesis, expression of osteocalcin (OC), bone sialoprotein (BSP) and lipoprotein lipase (LpL), and matrix mineralization. Withdrawal of dexamethasone at 3 and 10 days was found to enhance cell number relative to continuous exposure, but did not affect to decrease collagen synthesis slightly. Late markers of osteoblastic differentiation, BSP expression and matrix mineralization, were also sensitive to dexamethasone and increased systematically with exposure while LpL systematically decreased. These results indicate that dexamethasone acts at both early and late stages to direct proliferative osteoprogenitor cells toward terminal maturation. J. Cell. Biochem. 90: 13,22, 2003. © 2003 Wiley-Liss, Inc. [source] Factors related to the resting tongue position among partially and completely edentulous subjectsJOURNAL OF ORAL REHABILITATION, Issue 6 2005E. KOTSIOMITI summary, The prevalence of abnormal (retracted) position of the tongue at rest was examined in subjects with varying number of natural lower teeth. The aim of the study was to explore the relationship between tongue retraction and state of dentition and to identify potentially related parameters. The resting tongue positions were recorded in subjects partially edentulous in the lower jaw (n = 164) and compared with those met in dentate (n = 57) and completely edentulous participants (n = 84). Potentially related parameters, such as age, sex, duration of edentulism, palate vault and signs of temporomandibular disorders were also recorded. Tongue retraction was observed in a small percentage (12·3%) of the dentate, almost half (45·7%) of the partially edentulous and in the majority (67·8%) of the completely edentulous participants. The number of natural lower teeth correlated with the resting tongue position in the partially edentulous group. The tongue position at rest was also found weakly related to signs of temporomandibular disorders in the dentate group and to the sex and duration of edentulism in the partially edentulous group. It was concluded that the abnormal positioning of the resting tongue is increasingly observed with decreasing number of natural teeth, possibly in accordance with the morphological and functional alterations that result from teeth loss. The presence of a retracted tongue affects the complete denture construction; however, its effect on denture function remains questionable. [source] Abrasive wear mechanisms of VPS- and HVOF-sprayed TiC-Ni based nanocrystalline coatingsMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 10-11 2004X. Qi Verschleißmechanismen; nanokristalline Schichten; TiC-Ni; thermisches Spritzen Abstract Nanocrystalline coatings have a high potential for various engineering applications, e.g. against wear of rolls in the paper fabrication and as corrosion protection. Using vacuum plasma spray (VPS) and high velocity oxy-fuel (HVOF) spray techniques, coating materials are exposed to high flame temperatures only for less than a millisecond. Therefore, high-energy milled powders can be used as feedstock material without losing its nanocrystalline microstructure during the thermal spray process. In this way, homogeneous, dense nanocrystalline coatings can be produced, which show enhanced hardness, thus obtaining promising superior wear resistance. In the present study, (Ti,Mo)(C,N)-45vol.%NiCo nanocrystalline coatings were prepared by VPS- and HVOF-spraying of high-energy milled powders. Abrasive wear tests JIS H 8615 with varying number of strokes and scratch tests with a Vickers indenter were applied to produce wear traces on the polished surfaces of the nanocrystalline coatings. Abrasive wear behaviour was analyzed by investigating the surface morphologies with optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Experimental results indicate that the VPS-coating has higher abrasive wear resistance than the HVOF-coating according to the JIS H8615 test. The abrasive wear mechanism of VPS-sprayed nanocrystalline coatings can be delineated as cutting plus ploughing. For HVOF-sprayed nanocrystalline coatings the abrasive wear mechanism can be described as cutting plus material delamination. Abrasive Verschleißmechanismen von VPS- und HVOF-gespritzten nanokristallinen TiC-Ni-Schichten Nanokristalline Schichten haben ein hohes technisches Anwendungspotenzial, z.,B. für Papierwalzen zum Schutz gegen Verschleiß und Korrosion. Während des thermischen Spritzens mit der Vakuumplasmaspritz (VPS)- und der hochgeschwindigkeits-Flammspritz (HVOF)-Technik werden die Beschichtungsmaterialien nur für weniger als eine Millisekunde den hohen Temperaturen ausgesetzt. Daher können hochenenergiegemahlene Pulver als Beschichtungswerkstoff genutzt werden, ohne dass diese während des Spritzprozesses ihre nanokristalline Mikrostruktur verlieren. Dadurch können homogene, dichte nanokristalline Schichten produziert werden, die hohe Härte aufweisen und damit auch eine hohe Verschleißfestigkeit zeigen sollten. In der vorliegenden Arbeit werden nanokristalline Schichten auf der Basis von (Ti, Mo)(C, N)-45Vol.%NiCo durch die VPS- und HVOF-Technik hergestellt. Verschleißtests nach JIS H 8615 mit unterschiedlicher Hubzahl und Ritztests mit dem Vickers-Indenter werden durchgeführt, um Verschleißspuren auf den polierten Oberflächen der nanokristallinen Schichten zu erzeugen. Die Verschleißmechanismen werden aufgrund der Oberflächenmorphologien von verschleißbeanspruchten Schichten durch optische Mikroskopie (OM), Raster-Elektronenmikroskopie (REM) und Rasterkraftmikroskopie (AFM) analysiert. Die experimentellen Ergebnisse zeigen, dass die VPS-gespritzte Schicht eine höhere Verschleißfestigkeit aufweist als die HVOF-gespritzte Schicht. Der Verschleißmechanismus der VPS-gespritzten nanokristallinen Schicht kann als Kombination von Spanen und Pflügen charakterisiert werden. Für HVOF-gespritzte nanokristalline Schichten stellt sich der Verschleißmechanismus dagegen als Spanen mit partiellen Schichtablösungen dar. [source] Azimuthal anisotropy of light extraction from photonic crystal light-emitting diodesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Chun-Feng Lai Abstract Photonic crystal (PhC) light-emitting diodes (LEDs) exhibiting anisotropic light extraction have been investigated experimentally and theoretically. It is found that the anisotropic light extraction strongly depends on the lattice constant and orientation. Optical images of the anisotropy in the azimuthal direction are obtained using annular structure with triangular lattice. 6-fold symmetric light extraction patterns with varying number of petals are observed. More petals in multiple of 6 appear in the observed image with lattice constant increasing. This anisotropic behavior suggests a new means to optimize the PhC design of GaN LED for light extraction. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Epstein-Barr virus-related lymph node lesion resembling autoimmune disease-like clinicopathological findings in elderly patients Report of three casesAPMIS, Issue 12 2003MASARU KOJIMA Three cases of Epstein-Barr virus (EBV)-related lymphoproliferative disorders in elderly patients showing autoimmune disease-associated lymphadenopathy-like clinicopathological findings have been reported. Clinically, they were characterized by systemic lymphadenopathy, "B" symptoms, polyclonal hypergammaglobulinemia, elevated serum LDH and transient presence of various autoantibodies, and absence of atypical lymphocytosis in peripheral blood. One case was associated with idiopathic thrombocytopenic purpura. The clinical course was self-limiting. Histologically, they exhibited numerous lymphoid follicles with hyperplastic germinal centers and atypical interfollicular widening with prominent vascular proliferation. In the paracortical area, there was a mixed infiltrate comprising small to medium-sized lymphocytes and plasma cells, and variable numbers of eosinophils and T- and B-immunoblasts. In situ hybridization demonstrated a varying number of EBV-infected lymphocytes in the germinal center as well as in the interfollicular area. Polymerase chain reaction demonstrated that neither clonal rearrangement of T-cell receptor ,-gene nor immunoglobulin heavy-chain rearrangement was detected in two of the cases examined. Although acute EBV infection rarely occurs in older adults, EBV related to reactive lymphoproliferative disorder should be added to the differential diagnosis of autoimmune disease-associated lymphadenopathy and node-based peripheral T-cell lymphoma in elderly patients. [source] Beanspruchungsanalyse von Holzbauteilen durch 2D-PhotogrammetrieBAUTECHNIK, Issue 2 2005Bettina Franke Dipl.-Ing. Für die Bewertung der Tragsicherheit von Bauteilen aus Voll- und Brettschichtholz in Lasteinleitungs- und Störbereichen mittels der Bruchmechanik ist die Kenntnis von kritischen Bruchkennwerten Voraussetzung. Realitätsnahe Kennwerte können aus der Kombination experimenteller Untersuchungen zur Bestimmung der Rißaufweitung und der Rißlänge mit daran anschließender FE-Simulation gewonnen werden. Aufgrund der, bisher bei konventionellen Meßverfahren, nicht ausreichenden Zuordnung der Meßwerte taktil applizierter Meßaufnehmer lag es nahe das Rißwachstum mit Hilfe der Photogrammetrie zu untersuchen. Mit dem entwickelten Meßsystem ist nunmehr die Möglichkeit der exakten Vermessung der Rißgeometrie zur Bestimmung von bruchmechanischen Kennwerten gegeben. Zusätzlich ermöglicht der Einsatz der Photogrammetrie die Verdichtung der Anzahl variierender diskreter Meßpunkte, so daß ein deutlich vollständigeres Bild der örtlichen Verformungen gewonnen, und damit die Aussagekraft eines Versuchs wesentlich verbessert werden kann. Strain analysis of solid wood and glued laminated timber members by close range photogrammetry. The assumption of critical fracture mechanics parameters for the evaluation of the load-bearing safety of structural units of full and board laminated timber in loaded areas and disturbance ranges the use of fracture mechanics is required. Realistic parameters can be gained only from experimental investigations that are transferred to the determination of the crack opening and the crack length with subsequent FE-simulation. Due to the insufficient appropriation of measured data gained by tactile position encoders in conventional measuring procedures it is advisable to investigate crack growth with the help of the photogrammetry. Using the developed measuring system it is now possible to measure the crack geometry exactly for the determination of fracture mechanics parameters. Additionally a complete picture of the local deformations and the validity of a test can be improved considerably by the possibility of the varying number of discrete measuring points. [source] Langerhans cell histiocytosis in lymph nodes , cytomorphological diagnosis and pitfallsCYTOPATHOLOGY, Issue 6 2000S. Kakkar Background Langerhans cell histiocytosis (LCH) is a rare disorder of unknown aetiology that may present as a multisystem or unisystem disease. The Lymph nodes can be involved as part of disseminated disease, as a metastatic site draining a focus of LCH or may be a unisystem involvement. Paucity of literature on the cytomorphology of LCH in lymph nodes led us to undertake this study. Materials and methods Nine cases with a confirmed histological diagnosis of LCH and a prior lymph node aspirate were retrieved over a 12 year period (1988,1999). Five more cases were reviewed where the cytological diagnosis of LCH was rendered on a background of clinical and radiological findings. Papanicolaou and May Grunwald,Giemsa-stained smears were examined. S-100 protein staining was available in four cases. Results and conclusions Nine cases had multisystem involvement, while in five cases only lymph nodes were involved. There were eleven males and three females; age ranged from five months to 27 years. The cytological diagnosis of LCH had been rendered in six, suspected in four and missed in four. Of the latter, two were reclassified as LCH on review, one as reactive lymphadenitis and in one a necrotising lesion was suspected. The pathognomonic ,LCH cell' was identified in 12 of 14 cases along with varying numbers of eosinophils, polymorphs and lymphocytes. Giant cells were seen in only six cases. In conclusion lymph node involvement by LCH can be identified on aspirates. However, LCH must be differentiated from dermatopathic lymphadenitis, sinus histiocytosis with massive lymphadenopathy and Hodgkin's disease. [source] Interpretation of biological activity data of bacterial endotoxins by simple molecular models of mechanism of actionFEBS JOURNAL, Issue 3 2000Vladimir Frecer Lipid A moiety has been identified as the bioactive component of bacterial endotoxins (lipopolysaccharides). However, the molecular mechanism of biological activity of lipid A is still not fully understood. This paper contributes to understanding of the molecular mechanism of action of bacterial endotoxins by comparing molecular modelling results for two possible mechanisms with the underlying experimental data. Mechanisms of action involving specific binding of lipid A to a protein receptor as well as nonspecific intercalation into phospholipid membrane of a host cell were modelled and analysed. As the cellular receptor for endotoxin has not been identified, a model of a peptidic pseudoreceptor was proposed, based on molecular structure, symmetry of the lipid A moiety and the observed character of endotoxin-binding sites in proteins. We have studied the monomeric form of lipid A from Escherichia coli and its seven synthetic analogues with varying numbers of phosphate groups and correlated them with known biological activities determined by the Limulus assay. Gibbs free energies associated with the interaction of lipid A with the pseudoreceptor model and intercalation into phospholipid membrane calculated by molecular mechanics and molecular dynamics methods were used to compare the two possible mechanisms of action. The results suggest that specific binding of lipid A analogues to the peptidic pseudoreceptor carrying an amphipathic cationic binding pattern BHPHB (B, basic; H, hydrophobic; P, polar residue, respectively) is energetically more favourable than intercalation into the phospholipid membrane. In addition, binding affinities of lipid A analogues to the best minimum binding sequence KFSFK of the pseudoreceptor correlated with the experimental Limulus activity parameter. This correlation enabled us to rationalize the observed relationship between the number and position of the phosphate groups in the lipid A moiety and its biological activity in terms of specific ligand,receptor interactions. If lipid A,receptor interaction involves formation of phosphate-ammonium ion-pair(s) with cationic amino-acid residues, the specific mechanism of action was fully consistent with the underlying experimental data. As a consequence, recognition of lipid A variants by an amphipathic binding sequence BHPHB of a host-cell protein receptor might represent the initial and/or rate-determining molecular event of the mechanism of action of lipid A (or endotoxin). The insight into the molecular mechanism of action and the structure of the lipid A-binding pattern have potential implications for rational drug design strategies of endotoxin-neutralizing agents or binding factors. [source] A common variant in MTHFD1L is associated with neural tube defects and mRNA splicing efficiency,HUMAN MUTATION, Issue 12 2009Anne Parle-McDermott Abstract Polymorphisms in folate-related genes have emerged as important risk factors in a range of diseases including neural tube defects (NTDs), cancer, and coronary artery disease (CAD). Having previously identified a polymorphism within the cytoplasmic folate enzyme, MTHFD1, as a maternal risk factor for NTDs, we considered the more recently identified mitochondrial paralogue, MTHFD1L, as a candidate gene for NTD association. We identified a common deletion/insertion polymorphism, rs3832406, c.781-6823ATT(7,9), which influences splicing efficiency and is strongly associated with NTD risk. Three alleles of rs3832406 were detected in the Irish population with varying numbers of ATT repeats: Allele 1 consists of ATT7, whereas Alleles 2 and 3 consist of ATT8 and ATT9, respectively. Allele 2 of this triallelic polymorphism showed a decreased case risk as demonstrated by case,control logistic regression (P=0.002) and by transmission disequilibrium test (TDT) (P=0.001), whereas Allele 1 showed an increased case risk. Allele 3 showed no influence on NTD risk and represents the lowest frequency allele (0.15). Additional single nucleotide polymorphism (SNP) genotyping in the same genomic region provides additional supportive evidence of an association. We demonstrate that two of the three alleles of rs3832406 are functionally different and influence the splicing efficiency of the alternate MTHFD1L mRNA transcripts. Hum Mutat 30:1,7, 2009. © 2009 Wiley-Liss, Inc. [source] X-Cell: a novel indexing algorithm for routine tasks and difficult casesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2003Marcus A. Neumann X-Cell is a novel indexing algorithm that makes explicit use of systematic absences to search for possible indexing solutions from cells with low numbers of calculated reflections to cells with high numbers of reflections. Space groups with the same pattern of systematic absences are grouped together in powder extinction classes, and for a given peak number range an independent search is carried out in each powder extinction class. The method has the advantage that the correct cell is likely to be found before the rapid increase of possible solutions slows down the search significantly. A successive dichotomy approach is used to establish a complete list of all possible indexing solutions. The dichotomy procedure is combined with a search for the zero-point shift of the diffraction pattern, and impurity peaks can be dealt with by allowing for a user-defined portion of unindexed reflections. To rank indexing solutions with varying numbers of unindexed reflections, a new figure of merit is introduced that takes into account the highest level of agreement typically obtained for completely incorrect unit cells. The indexing of long and flat unit cells is facilitated by the possibility to search for rows or zones in reciprocal space first and then to use the lattice parameters of the dominant row or zone in the unit-cell search. The main advantages of X-Cell are robustness and completeness, as demonstrated by a validation study on a variety of compounds. The dominant phase of phase mixtures can be indexed in the presence of up to 50% of impurity peaks if high-quality synchrotron data are available. [source] Non-parametric statistical methods for multivariate calibration model selection and comparison,JOURNAL OF CHEMOMETRICS, Issue 12 2003Edward V. Thomas Abstract Model selection is an important issue when constructing multivariate calibration models using methods based on latent variables (e.g. partial least squares regression and principal component regression). It is important to select an appropriate number of latent variables to build an accurate and precise calibration model. Inclusion of too few latent variables can result in a model that is inaccurate over the complete space of interest. Inclusion of too many latent variables can result in a model that produces noisy predictions through incorporation of low-order latent variables that have little or no predictive value. Commonly used metrics for selecting the number of latent variables are based on the predicted error sum of squares (PRESS) obtained via cross-validation. In this paper a new approach for selecting the number of latent variables is proposed. In this new approach the prediction errors of individual observations (obtained from cross-validation) are compared across models incorporating varying numbers of latent variables. Based on these comparisons, non-parametric statistical methods are used to select the simplest model (least number of latent variables) that provides prediction quality that is indistinguishable from that provided by more complex models. Unlike methods based on PRESS, this new approach is robust to the effects of anomalous observations. More generally, the same approach can be used to compare the performance of any models that are applied to the same data set where reference values are available. The proposed methodology is illustrated with an industrial example involving the prediction of gasoline octane numbers from near-infrared spectra. Published in 2004 by John Wiley & Sons, Ltd. [source] Gender acts as a context for interpreting diagnostic criteriaJOURNAL OF CLINICAL PSYCHOLOGY, Issue 12 2005Elizabeth H. Flanagan This study used a unique methodology to determine the aspects of case vignettes that elicited an effect of case gender on diagnosis. A total of 99 psychiatrists and psychologists were shown cases representing a man or a woman that contained varying numbers of histrionic and antisocial criteria. The cases were presented by computer a few sentences at a time. Clinicians were asked to offer a diagnosis for the case after each group of sentences was presented. Results indicated that case gender tended to affect clinicians' diagnostic decisions when criteria related to that diagnosis were shown, suggesting that case gender was acting as a context in which diagnostic criteria were interpreted. © 2005 Wiley Periodicals, Inc. J Clin Psychol 61: 1485,1498, 2005. [source] Outcomes-based trial of an inpatient nurse practitioner service for general medical patientsJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 1 2001Mathilde H. Pioro MD Abstract Although teaching hospitals are increasingly using nurse practitioners (NPs) to provide inpatient care, few studies have compared care delivered by NPs and housestaff or the ability of NPs to admit and manage unselected general medical patients. In a Midwest academic teaching hospital 381 patients were randomized to general medical wards staffed either by NPs and a medical director or medical housestaff. Data were obtained from medical records, interviews and hospital databases. Outcomes were compared on both an intention to treat (i.e. wards to which patients were randomized) and actual treatment (i.e. wards to which patients were admitted) basis. At admission, patients assigned randomly to NP-based care (n = 193) and housestaff care (n = 188) were similar with respect to demographics, comorbidity, severity of illness and functional parameters. Outcomes at discharge and at 6 weeks after discharge were similar (P > 0.10) in the two groups, including: length of stay; charges; costs; consultations; complications; transfers to intensive care; 30-day mortality; patient assessments of care; and changes in activities of daily living, SF-36 scores and symptom severity. However, after randomization, 90 of 193 patients (47%) assigned to the NP ward were actually admitted to housestaff wards, largely because of attending physicians and NP requests. None the less, outcomes of patients admitted to NP and housestaff wards were similar (P > 0.1). NP-based care can be implemented successfully in teaching hospitals and, compared to housestaff care, may be associated with similar costs and clinical and functional outcomes. However, there may be important obstacles to increasing the number of patients cared for by NPs, including physician concerns about NPs' capabilities and NPs' limited flexibility in managing varying numbers of patients and accepting off-hours admissions. [source] Vaccine-associated granulomatous inflammation and melanin accumulation in Atlantic salmon, Salmo salar L., white muscleJOURNAL OF FISH DISEASES, Issue 1 2005E O Koppang Abstract The purpose of this study was to investigate the nature of variably sized pigmented foci encountered in fillets of farmed Atlantic salmon, Salmo salar L. The material was sampled on the fillet production line and on salmon farms from fish with an average size of 3 kg from various producers. The fish had been routinely vaccinated by injection. Gross pathology, histology, immunohistochemistry using antisera against major histocompatibility complex (MHC) class II , chain and transmission electron microscopy (TEM) were used to characterize the changes. Macroscopically, melanized foci were seen penetrating from the peritoneum deep into the abdominal wall, sometimes right through to the skin, and also embedded in the caudal musculature. Histological investigation revealed muscle degeneration and necrosis, fibrosis and granulomatous inflammation containing varying numbers of melano-macrophages. Vacuoles, either empty or containing heterogeneous material, were frequently seen. The presence of abundant MHC class II+ cells indicated an active inflammatory condition. TEM showed large extracellular vacuoles and leucocytes containing homogeneous material of lipid-like appearance. The results showed that the melanized foci in Atlantic salmon fillet resulted from an inflammatory condition probably induced by vaccination. The described condition is not known in wild salmon and in farmed salmon where injection vaccination is not applied. [source] Proton T2 relaxation of cerebral metabolites of normal human brain over large TE rangeNMR IN BIOMEDICINE, Issue 1 2005E. E. Brief Abstract T2 of NAA, creatine and choline-containing compounds were measured in posterior frontal white matter and occipital grey matter in 10 healthy human volunteers. Decay curves comprised signals from eight TE times ranging from 30 to 800,ms with TR 2000,ms acquired with a PRESS sequence on a 1.5,T clinical scanner. Simulations were conducted to assess the precision of T2 estimates from decay curves comprising varying numbers and ranges of TE points. Mean and standard errors for T2s of NAA, creatine and choline-containing compounds were 300(8), 169(3) and 239(4) ms in posterior frontal white matter and 256(6), 159(8) and 249(8) ms in occipital grey matter. In vivoT2s found for choline and NAA were shorter than the T2s in the literature. The elevation of literature T2s is accounted for by the simulation results, which demonstrated that there is a bias towards lengthened T2s when T2 is measured with a maximum TE , T2. Concentration estimates are at risk of being underestimated if previously reported T2 corrections are used. Copyright © 2004 John Wiley & Sons, Ltd. [source] Can 4D-Var use dynamical information from targeted observations of a baroclinic structure?THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 651 2010E. A. Irvine Abstract Targeted observations are generally taken in regions of high baroclinicity, but often show little impact. One plausible explanation is that important dynamical information, such as upshear tilt, is not extracted from the targeted observations by the data assimilation scheme and used to correct initial condition error. This is investigated by generating pseudo targeted observations which contain a singular vector (SV) structure that is not present in the background field or routine observations, i.e. assuming that the background has an initial condition error with tilted growing structure. Experiments were performed for a single case-study with varying numbers of pseudo targeted observations. These were assimilated by the Met Office four-dimensional variational (4D-Var) data assimilation scheme, which uses a 6 h window for observations and background-error covariances calculated using the National Meteorological Centre (NMC) method. The forecasts were run using the operational Met Office Unified Model on a 24 km grid. The results presented clearly demonstrate that a 6 h window 4D-Var system is capable of extracting baroclinic information from a limited set of observations and using it to correct initial condition error. To capture the SV structure well (projection of 0.72 in total energy), 50 sondes over an area of 1×106 km2 were required. When the SV was represented by only eight sondes along an example targeting flight track covering a smaller area, the projection onto the SV structure was lower; the resulting forecast perturbations showed an SV structure with increased tilt and reduced initial energy. The total energy contained in the perturbations decreased as the SV structure was less well described by the set of observations (i.e. as fewer pseudo observations were assimilated). The assimilated perturbation had lower energy than the SV unless the pseudo observations were assimilated with the dropsonde observation errors halved from operational values. Copyright © 2010 Royal Meteorological Society [source] | ||||||||||||||||||||||||||||