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Prior Work (prior + work)
Selected AbstractsHierarchical Image-Space Radiosity for Interactive Global IlluminationCOMPUTER GRAPHICS FORUM, Issue 4 2009Greg Nichols Abstract We introduce image-space radiosity and a hierarchical variant as a method for interactively approximating diffuse indirect illumination in fully dynamic scenes. As oft observed, diffuse indirect illumination contains mainly low-frequency details that do not require independent computations at every pixel. Prior work leverages this to reduce computation costs by clustering and caching samples in world or object space. This often involves scene preprocessing, complex data structures for caching, or wasted computations outside the view frustum. We instead propose clustering computations in image space, allowing the use of cheap hardware mipmapping and implicit quadtrees to allow coarser illumination computations. We build on a recently introduced multiresolution splatting technique combined with an image-space lightcut algorithm to intelligently choose virtual point lights for an interactive, one-bounce instant radiosity solution. Intelligently selecting point lights from our reflective shadow map enables temporally coherent illumination similar to results using more than 4096 regularly-sampled VPLs. [source] Modeling Goodwill for Banks: A Residual Income Approach with Empirical Tests,CONTEMPORARY ACCOUNTING RESEARCH, Issue 1 2006Joy Begley Abstract This paper uses the residual income valuation technique outlined in Feltham and Ohlson 1996 to examine the relation between stock valuations and accounting numbers for a prototypical banking firm. Prior work of this nature typically assumes a manufacturing setting. This paper contributes to the prior research by clarifying how the approach can be extended to settings where value is created from financial assets and liabilities. Key elements of our model include allowing banks to generate positive net present value from either lending or borrowing activities, and allowing for accounting policy to affect valuation through the loan loss allowance. We validate our model using archival data analysis, and interpret coefficients in light of our modeling assumptions. These results suggest that banks create value more from deposit-taking activities than from lending activities. Vuong tests confirm that our model outperforms adaptations of the unbiased accounting model of Ohlson 1995 and adaptations of the base model proposed by Beaver, Eger, Ryan, and Wolfson 1989. However, our model is outperformed by the popular net income-book value model used in many empirical studies, and we can formally reject one of our key modeling assumptions. These tests of our model suggest future avenues for improving upon the theoretical analysis. [source] Children use categories to maximize accuracy in estimationDEVELOPMENTAL SCIENCE, Issue 6 2006Sean Duffy The present study tests a model of category effects upon stimulus estimation in children. Prior work with adults suggests that people inductively generalize distributional information about a category of stimuli and use this information to adjust their estimates of individual stimuli in a way that maximizes average accuracy in estimation (see Huttenlocher, Hedges & Vevea, 2000). However, little is known about the developmental origin of this cognitive process. In the present study, 5- and 7-year-old children viewed stimuli that varied in size and reproduced each from memory. Consistent with the predictions of a Bayesian model of category effects on estimation, responses were adjusted toward the central value of the stimulus distribution. Additionally, the dispersion of the stimulus distribution affected the pattern of bias and variability of responses in a way that is predicted by the model. The results suggest that, like adults, children use categories for increasing average accuracy in estimating inexact stimuli. [source] Inter- and intraspecific variation of stemflow production from Fagus grandifolia Ehrh. (American beech) and Liriodendron tulipifera L. (yellow poplar) in relation to bark microrelief in the eastern United States,ECOHYDROLOGY, Issue 1 2010J. Toland Van Stan II Abstract Stemflow is a spatially concentrated hydrologic input at the tree base. Prior work has documented the differential effects of stemflow from a wide range of plant species on ecohydrological processes, such as the alteration of soil pH and spatial patterning of understory vegetation. No known work has coupled stemflow yield with high resolution measurements of bark microrelief that definitively ascribe differential stemflow yield to bark microrelief. As such, our research objectives were to: (1) correlate inter- and intraspecific variation in stemflow yield to a quantitative bark microrelief scale and (2) compare and contrast stemflow for two co-occurring deciduous species,Fagus grandifolia Ehrh. (American beech) and Liriodendron tulipifera L. (yellow poplar). Using a newly developed instrument to measure bark microrelief, namely the LaserBarkÔ automated tree measurement system, in combination with an 11-month stemflow database for a broadleaved deciduous forest in eastern North America, it was found that bark microrelief values significantly differed between the two species [P = 0·000, F (1,19) = 49·32]. Funneling ratios [P = 0·000, H (1, 990) = 339·20] and stemflow generation [P = 0·000, H (1, 990) = 146·75] also significantly differed between the two species. Our results indicate that bark microrelief exerts a considerable effect on stemflow yield from F. grandifolia and L. tulipifera, possibly affecting water and solute flux to the forest floor. Copyright © 2009 John Wiley & Sons, Ltd. [source] Variation among individual butterflies along a generalist,specialist axis: no support for the ,neural constraint' hypothesisECOLOGICAL ENTOMOLOGY, Issue 3 2007BRIAN WEE Abstract 1.,Degree of host specialisation was a continuous variable in a population of Edith's checkerspot butterfly (Euphydryas editha). A novel host, Collinsia torreyi, had been added to the diet in response to anthropogenic disturbance, and then abandoned prior to the current study. Butterflies either showed no preference or preferred their traditional host, Pedicularis semibarbata. 2.,Strength of preference for Pedicularis over Collinsia was measured in the field and used to estimate host specialisation of individual butterflies. Efficiency was estimated from the times taken by each insect to perform two tasks: (i) identification of a Pedicularis plant as a host, and (ii) successful initiation of oviposition after the decision to do so had been made. 3.,There was no clear trend for association between host specialisation and either measure of efficiency. Generalists were not slower than specialists at identifying Pedicularis as a host or at handling it after deciding to oviposit. 4.,Prior work indicated that generalists paid no detectable cost in terms of reduced discrimination among individuals of their preferred host species. 5.,In contrast to other species, generalist E. editha paid in neither time nor accuracy. Why then does the diet not expand? Behavioural adaptations to the traditional host caused maladaptations to the novel host and generated short-term constraints to evolutionary expansion of diet breadth. To date, however, no long-term constraints have been found in this system. In those traits investigated to date, increased adaptation to the novel host has not caused reduced adaptation to the traditional host. [source] Functional demonstration of surface carbonic anhydrase IV activity on rat astrocytesGLIA, Issue 3 2006Nataliya Svichar Abstract Buffering of the brain extracellular fluid is catalyzed by carbonic anhydrase (CA) activity. Whereas the extracellular isoform CA XIV has been localized exclusively to neurons in the brain, and to glial cells in the retina, there has been uncertainty regarding the form or forms of CA on the surface of brain astrocytes. We addressed this issue using physiological methods on cultured and acutely dissociated rat astrocytes. Prior work showed that the intracellular lactate-induced acidification (LIA) of astrocytes is diminished by benzolamide, a poorly permeant, nonspecific CA inhibitor. We demonstrate that pretreatment of astrocytes with phosphatidylinositol-specific phospholipase C (PI-PLC) results in a similar inhibition of the mean LIA (by 66 ± 3%), suggesting that the glycosylphosphatidylinositol-anchored CA IV was responsible. Pretreatment of astrocytes with CA IV inhibitory antisera also markedly reduced the mean LIA in both cultured cortical (by 46 ± 4%) and acutely dissociated hippocampal astrocytes (by 54 ± 8%). Pre-immune sera had no effect. The inhibition produced by PIPLC or CA IV antisera was not significantly less than that by benzolamide, suggesting that the majority of detectable surface CA activity was attributable to CA IV. Thus, our data collectively document the presence of CAIV on the surface of brain astrocytes, and suggest that this is the predominant CA isoform on these cells. © 2005 Wiley-Liss, Inc. [source] Cortical efferents of the perirhinal, postrhinal, and entorhinal cortices of the ratHIPPOCAMPUS, Issue 12 2009Kara L. Agster Abstract We investigated the cortical efferents of the parahippocampal region by placing injections of the anterograde tracers, Phaseolus vulgaris -leuccoagglutinin, and biotinylated dextran amine, throughout the perirhinal (PER), postrhinal (POR), and entorhinal cortices of the rat brain. The resulting density of labeled fibers was evaluated in 25 subregions of the piriform, frontal, insular, temporal, cingulate, parietal, and occipital areas. The locations of labeled terminal fibers differed substantially depending on whether the location of the injection site was in PER area 35, PER area 36, POR, or the lateral or the medial entorhinal (LEA and MEA). The differences were greater for sensory regions. For example, the POR efferents preferentially target visual and spatial regions, whereas the PER efferents target all sensory modalities. The cortical efferents of each region largely reciprocate the cortical afferents, though the degree of reciprocity varied across originating and target regions. The laminar pattern of terminal fibers was consistent with the notion that the efferents are feedback projections. The density and amount of labeled fibers also differed substantially depending on the regional location of injection sites. PER area 36 and POR give rise to a greater number of heavy projections, followed by PER area 35. LEA also gives rise to widespread cortical efferents, arising mainly from a narrow band of cortex adjacent to the PER. In contrast, the remainder of the LEA and the MEA provides only weak efferents to cortical regions. Prior work has shown that nonspatial and spatial information is transmitted to the hippocampus via the PER-LEA and POR-MEA pathways, respectively. Our findings suggest that the return projections follow the same pathways, though perhaps with less segregration. © 2009 Wiley-Liss, Inc. [source] Efficient probabilistic reasoning in BNs with mutual exclusion and context-specific independenceINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 8 2004Carmel Domshlak Prior work has shown that context-specific independence (CSI) in Bayes networks can be exploited to speed up belief updating. We examine how networks with variables exhibiting mutual exclusion (e.g., "selector variables"), as well as CSI, can be efficiently updated. In particular, directed-path singly connected and polytree networks that have an additional common selector variable can be updated in linear time (given null and general conjunctive evidence, respectively), where quadratic time would be needed without the mutual exclusion requirement. The above results have direct applications, as such network topologies can be used in predicting the ramifications of user selection in some multimedia data browsing systems. © 2004 Wiley Periodicals, Inc. Int J Int Syst 19: 703,725, 2004. [source] Effects of axotomy on telomere length, telomerase activity, and protein in activated microgliaJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2005Barry E. Flanary Abstract The adult central nervous system (CNS) is generally thought of as a postmitotic organ. However, DNA labeling studies have shown that one major population of nonneuronal cells, called microglia, retain significant mitotic potential. Microglial cell division is prominent during acute CNS injury involving neuronal damage or death. Prior work from this laboratory has shown that purified microglia maintained in vitro with continual mitogenic stimulation exhibit telomere shortening before entering senescence. In the current study, we sought to investigate whether telomere shortening occurs in dividing microglia in vivo. For this purpose, we used a nerve injury model that is known to trigger localized microglial proliferation in a well-defined CNS region, the facial motor nucleus. Adult Sprague-Dawley rats underwent facial nerve axotomy, and facial motor nuclei were microdissected after 1, 4, 7, and 10 days. Whole tissue samples were subjected to measurements of telomere length, telomerase activity, and telomerase protein. Results revealed a tendency for all of these parameters to be increased in lesioned samples. In addition, microglial cells isolated directly from axotomized facial nuclei with fluorescence-activated cell sorting (FACS) showed increased telomerase activity relative to unoperated controls, suggesting that microglia are the primary cell type responsible for the increases observed in whole tissue samples. Overall, the results show that microglia activated by injury are capable of maintaining telomere length via telomerase during periods of high proliferation in vivo. We conclude that molecular mechanisms pertaining to telomere maintenance are active in the injured CNS. © 2005 Wiley-Liss, Inc. [source] Acquisition of apoptotic resistance in cadmium-induced malignant transformation: Specific perturbation of JNK signal transduction pathway and associated metallothionein overexpression,MOLECULAR CARCINOGENESIS, Issue 8 2006Wei Qu Abstract Prior work has shown that chronic cadmium exposed rat liver epithelial cells (CCE-LE) become malignantly transformed after protracted low level cadmium exposure. Acquisition of apoptotic resistance is common in oncogenesis and the present work explores this possibility in CCE-LE cells. CCE-LE cells were resistant to apoptosis induced by etoposide or an acute high concentration of cadmium as assessed by flow cytometry with annexin/FITC. Three key mitogen-activated protein kinases (MAPKs), namely ERK1/2, JNK1/2, and p38, were phosphorylated in CCE-LE cells after acute cadmium exposure. However, the levels of phosphorylated JNK1/2 were markedly decreased in CCE-LE cells compared to control. JNK kinase activity was also suppressed in CCE-LE cells exposed to cadmium. Epidermal growth factor (EGF), used as a positive control for stimulating JNK phosphorylation, was much less effective in CCE-LE cells than control cells. Ro318220 (Ro), a strong activator of JNK, increased phosphorylated JNK1/2 to levels similar to the cadmium-treated control cells and also enhanced apoptosis in response to cadmium in CCE-LE cells. Metallothionein (MT), which is thought to potentially inhibit apoptosis, was strongly overexpressed in CCE-LE cells. Further, in MT knockout (MT,/,) fibroblasts, JNK1/2 phosphorylation was markedly increased after cadmium exposure compared with similarly treated wild-type (MT+/+) cells. These results indicate cadmium-transformed cells acquired apoptotic resistance, which may be linked to the specific suppression of the JNK pathway and is associated with MT overexpression, which, in turn, may impact this signal transduction pathway. The acquisition of apoptotic resistance may play an important role in cadmium carcinogenesis by contributing to both tumor initiation and malignant progression. Published 2006 Wiley-Liss, Inc. [source] Mixed matrix membrane materials with glassy polymers.POLYMER ENGINEERING & SCIENCE, Issue 7 2002Part Mixed matrix materials comprising molecular sieve entities embedded in a polymer matrix can economically increase membrane permselectivity, thereby addressing a key challenge hindering the widespread use of membrane-based gas separations. Prior work has clarified the importance of proper selection of the dispersed sieve phase and the continuous matrix phase based on their intrinsic transport properties. Proper material selection for the two components, while necessary, is not sufficient since the interfacial contact zone appears to be equally important to achieve optimum transport properties. Specifically, it was found that chemical coupling of the sieve to the polymer can lead to better macroscopic adhesion but to even poorer transport properties than in the absence of the adhesion promoter. This counterintuitive behavior may be attributed to a nanometric region of disturbed packing at the polymer sieve interphase. The poor properties are believed to result from "leakage" of gas molecules along this nanometric interface. The Maxwell model was modified to take into account these complexities and to provide a first order quantification of the nanometric interphase. The analysis indicates that optimization of the transport properties of the interfacial region is key to the formation of ideal mixed matrix materials. This approach is used in the second part of this paper to form successful mixed matrix membrane materials. [source] Psychosocial and sociodemographic correlates of benefit-finding in men treated for localized prostate cancerPSYCHO-ONCOLOGY, Issue 11 2006David P. Kinsinger Abstract Background: Prostate cancer (PCa) treatment involves decrements in quality of life such as decreased sexual functioning and urinary/bowel incontinence. Prior work in other cancers has identified positive consequences (e.g. personal growth) following diagnosis and treatment, a phenomenon that has been referred to as benefit-finding (BF) and positively related to quality of life. Method: The present study evaluated demographic and psychosocial correlates of BF in men treated for localized PCa. Participants were 250 men who were 6,18 months post treatment, who completed measures of coping strategies, perceived social support, and BF. Results: In regression models both coping and social support were positively related to BF scores, even after controlling for income, education and ethnic identification. Conclusion: Active coping strategies and greater perceived social support are important correlates of greater BF following localized PCa treatment. Copyright © 2006 John Wiley & Sons, Ltd. [source] Are All Trauma Centers Created Equally?ACADEMIC EMERGENCY MEDICINE, Issue 7 2010A Statewide Analysis ACADEMIC EMERGENCY MEDICINE 2010; 17:701,708 © 2010 by the Society for Academic Emergency Medicine Abstract Objectives:, Prior work has shown differences in mortality at different levels of trauma centers (TCs). There are limited data comparing mortality of equivalently verified TCs. This study sought to assess the potential differences in mortality as well as discharge destination (discharge to home vs. to a rehabilitation center or skilled nursing facility) across Level I TCs in the state of Ohio. Methods:, This was a retrospective, multicenter, statewide analysis of a state trauma registry of American College of Surgeons (ACS)-verified Level I TCs from 2003 to 2006. All adult (>15 years) patients transferred from the scene to one of the 10 Level I TCs throughout the state were included (n = 16,849). Multivariable logistic regression models were developed to assess for differences in mortality, keeping each TC as a fixed-effect term and adjusting for patient demographics, injury severity, mechanism of injury, and emergency medical services and emergency department procedures. Outcomes included in-hospital mortality and discharge destination (home vs. rehabilitation center or skilled nursing facility). Adjusted odds ratios (ORs) for each TC were also calculated. Results:, Considerable variability existed in unadjusted mortality between the centers, from 3.8% (95% confidence interval [CI] = 3.7% to 3.9%) to 24.2% (95% CI = 24.1% to 24.3%), despite similar patient characteristics and injury severity. Adjusted mortality had similar variability as well, ranging from an OR of 0.93 (95% CI = 0.47 to 1.84) to an OR of 6.02 (95% CI= 3.70 to 9.79). Similar results were seen with the secondary outcomes (discharge destination). Conclusions:, There is considerable variability in the mortality of injured patients at Level I TCs in the state of Ohio. The patient differences or care processes responsible for this variation should be explored. [source] Lithium isotopes: differential effects on renal function and histologyBIPOLAR DISORDERS, Issue 4 2001Peter M Stoll Objectives: Reduction in renal concentrating ability has been reported in patients undergoing chronic lithium treatment. Prior work has demonstrated differences in physiological effects of the stable lithium isotopes, 6Li and 7Li. Here, we measured the degree of polyuria, polydipsia and kidney histological changes induced in rats by equimolar amounts of 6LiCl, 7LiCl and the commercially available mixture of both isotopes. Methods: Rats were given 1.0 mEq/kg of either 6LiCl, 7LiCl or ,nLiCl' (isotope mixture, 93% 7LiCl) by subcutaneous injection twice daily for up to 49 days. Twenty-four-hour urine volume and water intake were measured daily. Kidneys from rats treated for 7 days with 1.5 mEq/kg 6LiCl, 7LiCl and vehicle were examined under light microscopy and histopathologic changes graded on a 4-point scale of severity. Results: All rats showed loss in renal concentrating ability manifested by increasing urine volume and water intake. Peak effects occurred after 9,13 days treatment, then declined to stable levels at two to three times pre-treatment level. Mean peak effect was significantly greater for 6LiCl than for 7LiCl. Chronic effects of 6LiCl (weeks 3,7 of treatment) on polyuria and polydipsia were persistently higher than that of 7LiCl. nLiCl effect was intermediate. Kidneys from rats treated for 7 days with 6LiCl showed more frequently severe lesions in renal tubules than did 7LiCl-treated rats. Conclusions: Our current data and prior studies suggest that elimination or reduction of 6Li from pharmaceutical preparations may merit further evaluation as a possibly less potentially nephrotoxic form of lithium treatment. [source] THE CONTEXT OF MARRIAGE AND CRIME: GENDER, THE PROPENSITY TO MARRY, AND OFFENDING IN EARLY ADULTHOOD,CRIMINOLOGY, Issue 1 2007RYAN D. KING Marriage is central to theoretical debates over stability and change in criminal offending over the life course. Yet, unlike other social ties such as employment, marriage is distinct in that it cannot be randomly assigned in survey research to more definitively assess causal effects of marriage on offending. As a result, key questions remain as to whether different individual propensities toward marriage shape its salience as a deterrent institution. Building on these issues, the current research has three objectives. First, we use a propensity score matching approach to estimate causal effects of marriage on crime in early adulthood. Second, we assess sex differences in the effects of marriage on offending. Although both marriage and offending are highly gendered phenomena, prior work typically focuses on males. Third, we examine whether one's propensity to marry conditions the deterrent capacity of marriage. Results show that marriage suppresses offending for males, even when accounting for their likelihood to marry. Furthermore, males who are least likely to marry seem to benefit most from this institution. The influence of marriage on crime is less robust for females, where marriage reduces crime only for those with moderate propensities to marry. We discuss these findings in the context of recent debates concerning gender, criminal offending, and the life course. [source] AFRICAN, RUSSIAN, AND UKRAINIAN REFUGEE RESETTLEMENT IN PORTLAND, OREGONGEOGRAPHICAL REVIEW, Issue 2 2005SUSAN E. HUME ABSTRACT. The residential patterns, adaptation experiences, and impacts of immigrants on North American cities have been well documented in the geographical literature. In this article, we build on prior work by testing the theories of Gaim Kibreab, who identified three factors that shape the experiences of recent refugees: attitudes of the receiving society; current policy environments; and employment opportunities in local communities. We analyze some of the ways in which these factors operate as interrelated systems for two comparative groups of foreign-born migrants in Portland, Oregon: sub-Saharan Africans; and Russians and Ukrainians. Using a mixed-methods approach, we triangulate data from a blend of in-depth interviews, participant observation in the community and at refugee and immigrant social service agencies, census and other statistical records, and cartographic analyses to report on the findings of our work. Data suggest that the residential, economic, and social spaces of new refugees are constructed as a complex multiplicity of networks and relationships that link time and place [source] The Experimental Appraisal Instrument: A brief overviewHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 3 2008Ash M. Genaidy Background Recently, there has been a great influx in experimental research to assess the health effects of nanoparticles/materials/fibers. Currently, there is no structured methodology to assess the methodological quality of the reported studies. Objective This article reports an experimental appraisal instrument with the goal to critically assess experimental studies. Methods A search of electronic databases was conducted to examine prior work on the subject and to extract the components of such an instrument. Results The electronic search revealed no major instrument designed to evaluate experimental strategies on health effects of nanoparticles/materials/fibers. An experimental appraisal instrument was developed and was patterned after the Epidemiological Appraisal Instrument reported by Genaidy and LeMasters (2006). Conclusions The validity and reliability of such an instrument will be reported in future work. © 2008 Wiley Periodicals, Inc. [source] The impact of organizational climate and strategic fit on firm performanceHUMAN RESOURCE MANAGEMENT, Issue 1 2004Richard M. Burton A firm's organizational climate,its degree of trust, morale, conflict, rewards equity, leader credibility, resistance to change, and scapegoating,helps determine its success. Likewise, organizational strategy,the firm's commitment to capital investment, innovation, quality, and the like,has also been found to be an important determinant of firm performance. However, prior work has most often explored the impact of climate and strategy separately, and not in tandem. In our study, we develop a measure of organizational climate comprised of tension, resistance to change, and conflict, and go on to show that at least for some pairings of a firm's climate and its strategy, there is a negative effect on return on assets (ROA). © 2004 Wiley Periodicals, Inc. [source] Towards a distinctive body of knowledge for Information Systems experts: coding ISD process knowledge in two IS journalsINFORMATION SYSTEMS JOURNAL, Issue 4 2004Juhani Iivari Abstract., This paper introduces the idea of coding a practically relevant body of knowledge (BoK) in Information Systems (IS) that could have major benefits for the field. In its main part, the paper focuses on the question if and how an underlying body of action-oriented knowledge for IS experts could be distilled from the IS research literature. For this purpose the paper identifies five knowledge areas as the most important parts for an IS expert's BoK. Two of these are claimed as distinct areas of competence for IS experts: IS application knowledge and IS development (ISD) process knowledge. The paper focuses particularly on ISD process knowledge because it allows the organizing of practically relevant IS knowledge in an action-oriented way. The paper presents some evidence for the claim that a considerable body of practically relevant IS process knowledge might, indeed, exist, but also notes that it is highly dispersed in the IS literature. It then argues that the IS research community should take stock of this knowledge and organize it in an action-oriented way. Based on results from prior work it proposes a four-level hierarchical coding scheme for this purpose. In order to test the idea of coding action-oriented knowledge for IS experts, the paper reports the results of a coded literature analysis of ISD research articles published from 1996 to 2000 in two leading IS journals , Information Systems Journal and MIS Quarterly. The results suggest that ISD approaches form a useful framework for organizing practically relevant IS knowledge. [source] Molecular phylogeny of Diabrotica beetles (Coleoptera: Chrysomelidae) inferred from analysis of combined mitochondrial and nuclear DNA sequencesINSECT MOLECULAR BIOLOGY, Issue 4 2001T. L. Clark Abstract The phylogenetic relationships of thirteen Diabrotica (representing virgifera and fucata species groups) and two outgroup Acalymma beetle species (Coleoptera: Chrysomelidae) were inferred from the phylogenetic analysis of a combined data set of 1323 bp of mitochondrial DNA (mtDNA) cytochrome oxidase subunit 1 (COI) and the entire second internal transcribed spacer region (ITS-2) of nuclear ribosomal DNA of 362 characters. Species investigated were D. adelpha, D. balteata, D. barberi, D. cristata, D. lemniscata, D. longicornis, D. porracea, D. speciosa, D. undecimpunctata howardi, D. u. undecimpunctata, D. virgifera virgifera, D. v. zeae, D. viridula, and outgroup A. blandulum and A. vittatum. Maximum parsimony (MP), minimum evolution (ME), and maximum likelihood (ML) analyses of combined COI and ITS-2 sequences clearly place species into their traditional morphological species groups with MP and ME analyses resulting in identical topologies. Results generally confer with a prior work based on allozyme data, but within the virgifera species group, D. barberi and D. longicornis strongly resolve as sister taxa as well as monophyletic with the neotropical species, D. viridula, D. cristata and D. lemniscata also resolve as sister taxa. Both relationships are not in congruence with the prior allozyme-based hypothesis. Within the fucata species group, D. speciosa and D. balteata resolve as sister taxa. Results also strongly supported the D. virgifera and D. undecimpunctata subspecies complexes. Our proposed phylogeny provides some insight into current hypotheses regarding distribution status and evolution of various life history traits for Diabrotica. [source] Mechanisms of cardioprotection by lysophospholipidsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2004Joel S. Karliner Abstract The lysophospholipids sphingosine 1-phosphate (S1P) and lysophosphosphatidic acid (LPA) reduce mortality in hypoxic cardiac myocytes. S1P is also cardioprotective in both mouse and rat models of cardiac ischemia/reperfusion (I/R) injury. Although these results are consistent with prior work in other cell types, it is not known what signaling events are critical to cardioprotection, particularly with respect to ceramide and the preservation of mitochondrial function, which is essential for cardiac cell survival. Neither receptor regulation nor signaling has been studied during I/R in the heart with or without the application of S1P or LPA. The role of sphingosine kinase in I/R and in ischemic preconditioning (IPC) has not been defined, nor has the fate or function of S1P generated by this enzyme, particularly during preconditioning or I/R, been elucidated. Whether S1P infused systemically in animal models of myocardial infarction in which survival is an end-point will be hemodynamically tolerated has not been determined. If not, the substitution of agents such as the monosialoganglioside GM-1, which activates sphingosine kinase, or the development of alternative ligands for S1P receptors will be necessary. © 2004 Wiley-Liss, Inc. [source] Controller design for natural and robotic systems with transmission delaysJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2002Abhay Kataria Robust stability and two-dimensional trajectory following problems are considered for n -link robotic systems with transmission delays. Such problems appear in telerobotics, where the controller is physically far from the robot, and in neural control of musculo-skeletal (biological) systems, where muscle actuation and neural sensing are subject to time delays. A typical second-order nonlinear dynamical model is taken with input and output time delays. In a prior work by the authors, a control strategy was developed for stable movement of the planar linkage system, using the standard Q -parameterization and solving an H, control problem to determine the free parameter. In this article, a new control scheme is proposed to eliminate the steady-state errors seen in the tracking performance of the controller derived in the earlier work. Simulation examples are shown to demonstrate the effectiveness of the proposed control methodology. © 2002 Wiley Periodicals, Inc. [source] P/E changes: some new resultsJOURNAL OF FORECASTING, Issue 4 2009Thomas Zorn Abstract The P/E ratio is often used as a metric to compare individual stocks and the market as a whole relative to historical valuations. We examine the factors that affect changes in the inverse of the P/E ratio (E/P) over time in the broad market (S&P 500 Index). Our model includes variables that measure investor beliefs and changes in tax rates and shows that these variables are important factors affecting the P/E ratio. We extend prior work by correcting for the presence of a long-run relation between variables included in the model. As frequently conjectured, changes in the P/E ratio have predictive power. Our model explains a large portion of the variation in E/P and accurately predicts the future direction of E/P, particularly when predicted changes in E/P are large or provide a consistent signal over more than one quarter. Copyright © 2008 John Wiley & Sons, Ltd. [source] 7 Tesla MR imaging of the human eye in vivoJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2009Kathryn Richdale OD Abstract Purpose: To develop a protocol which optimizes contrast, resolution and scan time for three-dimensional (3D) imaging of the human eye in vivo using a 7 Tesla (T) scanner and custom radio frequency (RF) coil. Materials and Methods: Initial testing was conducted to reduce motion and susceptibility artifacts. Three-dimensional FFE and IR-TFE images were obtained with variable flip angles and TI times. T1 measurements were made and numerical simulations were performed to determine the ideal contrast of certain ocular structures. Studies were performed to optimize resolution and signal-to-noise ratio (SNR) with scan times from 20 s to 5 min. Results: Motion and susceptibility artifacts were reduced through careful subject preparation. T1 values of the ocular structures are in line with previous work at 1.5T. A voxel size of 0.15 × 0.25 × 1.0 mm3 was obtained with a scan time of approximately 35 s for both 3D FFE and IR-TFE sequences. Multiple images were registered in 3D to produce final SNRs over 40. Conclusion: Optimization of pulse sequences and avoidance of susceptibility and motion artifacts led to high quality images with spatial resolution and SNR exceeding prior work. Ocular imaging at 7T with a dedicated coil improves the ability to make measurements of the fine structures of the eye. J. Magn. Reson. Imaging 2009;30:924,932. © 2009 Wiley-Liss, Inc. [source] Metaphor and the Dynamics of Knowledge in Organization Theory: A Case Study of the Organizational Identity Metaphor*JOURNAL OF MANAGEMENT STUDIES, Issue 4 2006Joep P. Cornelissen abstract Despite the increased salience of metaphor in organization theory, there is still very little conceptual machinery for capturing and explaining how metaphor creates and/or reorders knowledge within organization theory. Moreover, prior work on metaphor has insufficiently accounted for the context of interpreting a metaphor. Many metaphors in organization theory, including the ,organizational identity' metaphor, have often been treated in singular and monolithic terms; seen to offer a similar or largely synonymous interpretation to theorists and researchers working along the entire spectrum of disciplines (e.g. organizational behaviour, organizational psychology) in organization theory. We argue in this paper that contextual variation however exists in the interpretation of metaphors in organization theory. This argument is developed by proposing and elaborating on a so-called image-schematic model of metaphor, which suggests that the image-schemata (abstract imaginative structures) that are triggered by the metaphorical comparison of concepts may vary among individuals. Accordingly, once different schemata are triggered the completion and interpretation of a metaphor may equally vary among different individuals or, indeed, research communities. These points associated with the image-schematic model of metaphor are illustrated with a case study of the ,organizational identity' metaphor. The case study shows that this particular metaphor has spiralled out into different research communities and has been comprehended in very different ways as different communities work from very different conceptions, or image-schemata, of ,organization' and ,identity', and use different theoretical frameworks and constructs as a result. The implications of the image-schematic view of metaphor for knowledge development and theoretical progress in organization theory are discussed. [source] Trafficking and potential assembly patterns of ,-containing GABAA receptorsJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Brian L. Jones Abstract Incorporation of the , subunit into the GABAA receptor has been suggested to confer unusual, but variable, biophysical and pharmacological characteristics to both recombinant and native receptors. Due to their structural similarity with the , subunits, , subunits have been assumed to substitute at the single position of the , subunit in assembled receptors. However, prior work suggests that functional variability in ,-containing receptors may reflect alternative sites of incorporation and of not just one, but possibly multiple , subunits in the pentameric receptor complex. Here we present data indicating that increased expression of ,, in conjunction with ,2 and ,3 subunits, results in expression of GABAA receptors with correspondingly altered rectification, deactivation and levels of spontaneous openings, but not increased total current density. We also provide data that the , subunit, like the ,3 subunit, can self-export and data from chimeric receptors suggesting that similarities between the assembly domains of the ,3 and the , subunits may allow the , subunit to replace the ,, as well as the ,, subunit. The substitution of an , for a ,, as well as the , subunit and formation of receptors with alternative patterns of assembly with respect to , incorporation may underlie the observed variability in both biophysical and pharmacological properties noted not only in recombinant, but also in native receptors. [source] Microstructural Corpus Callosum Anomalies in Children With Prenatal Alcohol Exposure: An Extension of Previous Diffusion Tensor Imaging FindingsALCOHOLISM, Issue 10 2009Jeffrey R. Wozniak Background:, Several studies have now shown corpus callosum abnormalities using diffusion tensor imaging (DTI) in children with fetal alcohol spectrum disorders (FASD) in comparison with nonexposed controls. The data suggest that posterior regions of the callosum may be disproportionately affected. The current study builds on previous efforts, including our own work, and moves beyond midline corpus callosum to probe major inter-hemispheric white matter pathways with an improved DTI tractographic method. This study also expands on our prior work by evaluating a larger sample and by incorporating children with a broader range of clinical effects including full-criteria fetal alcohol syndrome (FAS). Methods:, Participants included 33 children with FASD (8 FAS, 23 partial FAS, 2 static encephalopathy) and 19 nonexposed controls between the ages of 10 and 17 years. Participants underwent DTI scans and intelligence testing. Groups (FASD vs. controls) were compared on fractional anisotropy (FA) and mean diffusivity (MD) in 6 white matter tracts projected through the corpus callosum. Exploratory analyses were also conducted examining the relationships between DTI measures in the corpus callosum and measures of intellectual functioning and facial dysmorphology. Results:, In comparison with the control group, the FASD group had significantly lower FA in 3 posterior tracts of the corpus callosum: the posterior mid-body, the isthmus, and the splenium. A trend-level finding also suggested lower FA in the genu. Measures of white matter integrity and cognition were correlated and suggest some regional specificity, in that only posterior regions of the corpus callosum were associated with visual-perceptual skills. Correlations between measures of facial dysmorphology and posterior regions of the corpus callosum were nonsignificant. Conclusions:, Consistent with previous DTI studies, these results suggest that microstructural posterior corpus callosum abnormalities are present in children with prenatal alcohol exposure and cognitive impairment. These abnormalities are clinically relevant because they are associated with cognitive deficits and appear to provide evidence of abnormalities associated with prenatal alcohol exposure independent of dysmorphic features. As such, they may yield important diagnostic and prognostic information not provided by the traditional facial characteristics. [source] Spouse Abuse and Alcohol Problems Among White, African American, and Hispanic U.S. Army SoldiersALCOHOLISM, Issue 10 2006Nicole S. Bell Background: Prior studies suggest racial/ethnic differences in the associations between alcohol misuse and spouse abuse. Some studies indicate that drinking patterns are a stronger predictor of spouse abuse for African Americans but not whites or Hispanics, while others report that drinking patterns are a stronger predictor for whites than African Americans or Hispanics. This study extends prior work by exploring associations between heavy drinking, alcohol-related problems, and risk for spouse abuse within racial/ethnic groups as well as variations associated with whether the perpetrator is drinking during the spouse abuse incident. Methods: Cases (N=7,996) were all active-duty male, enlisted Army spouse abusers identified in the Army's Central Registry (ACR) who had also completed an Army Health Risk Appraisal (HRA) Survey between 1991 and 1998. Controls (N=17,821) were matched on gender, rank, and marital and HRA status. Results: We found 3 different patterns of association between alcohol use and domestic violence depending upon both the race/ethnicity of the perpetrator and whether or not alcohol was involved in the spouse abuse event. First, after adjusting for demographic and psychosocial factors, weekly heavy drinking (>14 drinks per week) and alcohol-related problems (yes to 2 or more of 6 alcohol-related problem questions, including the CAGE) were significant predictors of domestic violence among whites and Hispanics only. Also for the white soldiers, the presence of family problems mediated the effect of alcohol-related problems on spouse abuse. Second, alcohol-related problems predicted drinking during a spouse abuse incident for all 3 race groups, but this relation was moderated by typical alcohol consumption patterns in Hispanics and whites only. Finally, alcohol-related problems predicted drinking during a spouse abuse incident, but this was a complex association moderated by different psychosocial or behavioral variables within each race/ethnic group. Conclusion: These findings suggest important cultural/social influences that interact with drinking patterns. [source] Predictive toxicogenomics approaches reveal underlying molecular mechanisms of nongenotoxic carcinogenicityMOLECULAR CARCINOGENESIS, Issue 12 2006Alex Y. Nie Toxicogenomics technology defines toxicity gene expression signatures for early predictions and hypotheses generation for mechanistic studies, which are important approaches for evaluating toxicity of drug candidate compounds. A large gene expression database built using cDNA microarrays and liver samples treated with over one hundred paradigm compounds was mined to determine gene expression signatures for nongenotoxic carcinogens (NGTCs). Data were obtained from male rats treated for 24 h. Training/testing sets of 24 NGTCs and 28 noncarcinogens were used to select genes. A semiexhaustive, nonredundant gene selection algorithm yielded six genes (nuclear transport factor 2, NUTF2; progesterone receptor membrane component 1, Pgrmc1; liver uridine diphosphate glucuronyltransferase, phenobarbital-inducible form, UDPGTr2; metallothionein 1A, MT1A; suppressor of lin-12 homolog, Sel1h; and methionine adenosyltransferase 1, alpha, Mat1a), which identified NGTCs with 88.5% prediction accuracy estimated by cross-validation. This six genes signature set also predicted NGTCs with 84% accuracy when samples were hybridized to commercially available CodeLink oligo-based microarrays. To unveil molecular mechanisms of nongenotoxic carcinogenesis, 125 differentially expressed genes (P,<,0.01) were selected by Student's t -test. These genes appear biologically relevant, of 71 well-annotated genes from these 125 genes, 62 were overrepresented in five biochemical pathway networks (most linked to cancer), and all of these networks were linked by one gene, c - myc. Gene expression profiling at early time points accurately predicts NGTC potential of compounds, and the same data can be mined effectively for other toxicity signatures. Predictive genes confirm prior work and suggest pathways critical for early stages of carcinogenesis. © 2006 Wiley-Liss, Inc. [source] Dissecting components of population-level variation in seed production and the evolution of masting behaviorOIKOS, Issue 3 2003Walter D. Koenig Mast-fruiting or masting behavior is the cumulative result of the reproductive patterns of individuals within a population and thus involves components of individual variability, between-individual synchrony, and endogenous cycles of temporal autocorrelation. Extending prior work by Herrera, we explore the interrelationships of these components using data on individual seed production in 59 populations of plants from 24 species spanning a large range of annual variability, from species exhibiting strong masting to others with little annual variability in seed production. Estimates of population and individual variability were not biased by sample size or average overall seed production when based on untransformed seed production values, but these values declined as log-transformed seed production increased. Population variability was more strongly correlated with individual variability (r=0.86) than individual synchrony (r=0.73). These latter two components were also significantly correlated (r=0.45), but randomizations confirm that they need not covary closely. Thus, selection can act separately on inter-annual variability and between-individual synchrony. We illustrate the potential for such fine-tuned selection on seed production patterns by discussing several examples and by demonstrating significant differences in components of population-level variation in seed production among species related to their life-history. [source] | |||||||||||||||||||||||||||||||