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Additional Evidence (additional + evidence)
Selected AbstractsAcross-sample Incomparability of R2s and Additional Evidence on Value Relevance Changes Over TimeJOURNAL OF BUSINESS FINANCE & ACCOUNTING, Issue 7-8 2007Zhaoyang GuArticle first published online: 9 OCT 200 Abstract:, Given the increasing popularity of across-sample R2 comparisons in accounting research, this paper illustrates why the regression R2s are incomparable across samples and the general nature of this problem. The regression residual dispersion with proper control for scale is proposed as the alternative measure of explanatory power for across-sample comparisons. In market-on-accounting variable regressions, this measure can be conveniently interpreted as the degree of accounting-based pricing errors and be used as a measure of value relevance of accounting information. As an application, the issue of over-time value relevance changes is re-visited. In contrast to prior mixed findings based on the R2 measure, a decline of value relevance since the early 1970s is robustly detected using the alternative measure. [source] Hydrologic response of the Greenland ice sheet: the role of oceanographic warmingHYDROLOGICAL PROCESSES, Issue 1 2009E. Hanna Abstract The response of the Greenland ice sheet to ongoing climate change remains an area of great uncertainty, with most previous studies having concentrated on the contribution of the atmosphere to the ice mass-balance signature. Here we systematically assess for the first time the influence of oceanographic changes on the ice sheet. The first part of this assessment involves a statistical analysis and interpretation of the relative changes and variations in sea-surface temperatures (SSTs) and air temperatures around Greenland for the period 1870,2007. This analysis is based on HadISST1 and Reynolds OI.v2 SST analyses, in situ SST and deeper ocean temperature series, surface-air-temperature records for key points located around the Greenland coast, and examination of atmospheric pressure and geopotential height from NCEP/NCAR reanalysis. Second, we carried out a novel sensitivity experiment in which SSTs were perturbed as input to a regional climate model, and document the resulting effects on simulated Greenland climate and surface mass balance. We conclude that sea-surface/ocean temperature forcing is not sufficient to strongly influence precipitation/snow accumulation and melt/runoff of the ice sheet. Additional evidence from meteorological reanalysis suggests that high Greenland melt anomalies of summer 2007 are likely to have been primarily forced by anomalous advection of warm air masses over the ice sheet and to have therefore had a more remote atmospheric origin. However, there is a striking correspondence between ocean warming and dramatic accelerations and retreats of key Greenland outlet glaciers in both southeast and southwest Greenland during the late 1990s and early 2000s. Copyright © 2008 John Wiley & Sons, Ltd. [source] Top Management Teams in Family-Controlled Companies: ,Familiness', ,Faultlines', and Their Impact on Financial PerformanceJOURNAL OF MANAGEMENT STUDIES, Issue 2 2010Alessandro Minichilli abstract This article examines the affect of family management on performance of the company. We examine how familiness can provide further insights beyond the classical demographic measures of top management teams (TMTs) in explaining variations in firms' financial performance. We combine arguments on the ,bright' and ,dark' side of family involvement in the firm; we complement positive predictions on family involvement with negative predictions and develop family firm-specific measures of TMTs' familiness. Results indicate that while the presence of a family CEO is beneficial for firm performance, the coexistence of ,factions' in family and non-family managers within the TMT has the potential to create schisms among the subgroups and consequently hurt firm performance. We find support for a hypothesized U-shaped relationship between the ratio of family members in the TMT and firm performance. Additional evidence related to interactions between firm listing and CEO type on firm performance is then presented and discussed. [source] Synthesis and characterization of multiblock copolymers composed of poly(5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one) outer blocks and poly(L -lactide) inner blocksJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2006Jamie M. Messman Abstract Ethylene glycol (EG) initiated, hydroxyl-telechelic poly(L -lactide) (PLLA) was employed as a macroinitiator in the presence of a stannous octoate catalyst in the ring-opening polymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with the goal of creating A,B,A-type block copolymers having polycarbonate outer blocks and a polyester center block. Because of transesterification reactions involving the PLLA block, multiblock copolymers of the A,(B,A)n,B,A type were actually obtained, where A is poly(5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one), B is PLLA, and n is greater than 0. 1H and 13C NMR spectroscopy of the product copolymers yielded evidence of the multiblock structure and provided the lactide sequence length. For a PLLA macroinitiator with a number-average molecular weight of 2500 g/mol, the product block copolymer had an n value of 0.8 and an average lactide sequence length (consecutive C6H8O4 units uninterrupted by either an EG or MBC unit) of 6.1. For a PLLA macroinitiator with a number-average molecular weight of 14,400 g/mol, n was 18, and the average lactide sequence length was 5.0. Additional evidence of the block copolymer architecture was revealed through the retention of PLLA crystallinity as measured by differential scanning calorimetry and wide-angle X-ray diffraction. Multiblock copolymers with PLLA crystallinity could be achieved only with isolated PLLA macroinitiators; sequential addition of MBC to high-conversion L -lactide polymerizations resulted in excessive randomization, presumably because of residual L -lactide monomer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6817,6835, 2006 [source] On Spectral Relaxation in Proteins,,§PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2000Joseph R. Lakowicz ABSTRACT During the past several years there has been debate about the origins of nonexponential intensity decays of intrinsic tryptophan (trp) fluorescence of proteins, especially for single tryptophan proteins (STP). In this review we summarize the data from diverse sources suggesting that time-dependent spectral relaxation is a ubiquitous feature of protein fluorescence. For most proteins, the observations from numerous laboratories have shown that for trp residues in proteins (1) the mean decay times increase with increasing observation wavelength; (2) decay associated spectra generally show longer decay times for the longer wavelength components; and (3) collisional quenching of proteins usually results in emission spectral shifts to shorter wavelengths. Additional evidence for spectral relaxation comes from the time-resolved emission spectra that usually shows time-dependent shifts to longer wavelengths. These overall observations are consistent with spectral relaxation in proteins occurring on a subnanosecond timescale. These results suggest that spectral relaxation is a significant if not dominant source of nonexponential decay in STP, and should be considered in any interpretation of nonexponential decay of intrinsic protein fluorescence. [source] Parental exposure to lead and small for gestational age birthsAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 6 2006Pau-Chung Chen MD Abstract Background Previous studies about the effect of lead exposure on adverse birth outcomes are still inconsistent and few studies estimate the relationship between parental lead exposure and small for gestational age (SGA) infants. An occupational cohort study to assess whether parental lead exposure would be related to decreased birth weight and shortened gestational ages of their offspring was conducted. Whether higher lead exposure doses would increase risks of low birth weight (LBW), preterm delivery, and SGA births was also investigated. Methods A Program to Reduce Exposure by Surveillance System,Blood Lead Levels (Press-BLLS) was established in Taiwan in July 1993. The names of workers exposed to lead was collected from this occupational blood-lead notification database. The birth outcomes of their offspring were determined by linking to the Taiwan birth registration database from 1993 to 1997. Only singleton births whose parental blood-lead concentrations were tested during pregnancy or prior to conception, or within a 1-year span before these two periods were included. Results Among 1,611 eligible births, 72 births were LBW, 74 were preterm deliveries, and 135 were SGA. Maternal blood-lead concentrations (PbBs) equal to or more than 20 µg/dl had a higher risk of mothering a SGA child (risk ratio (RR),=,2.15; 95% confidence interval (CI), 1.15,3.83). Conclusions Additional evidence of the effects of lead on adverse birth outcomes, especially for SGA births is reported. Maternal exposure to lead plays a more important role in the adverse effect on birth outcome than does paternal exposure. Am. J. Ind. Med. 2006. © 2006 Wiley-Liss, Inc. [source] Early Holocene human remains from the Argentinean Pampas: Additional evidence for distinctive cranial morphology of early South AmericansAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Héctor M. Pucciarelli Abstract The cranial morphology of Early Holocene American human samples is characterized by a long and narrow cranial vault, whereas more recent samples exhibit a shorter and wider cranial vault. Two hypotheses have been proposed to account for the morphological differences between early and late-American samples: (a) the migratory hypothesis that suggests that the morphological variation between early and late American samples was the result of a variable number of migratory waves; and (b) the local diversification hypothesis, that is, the morphological differences between early and late American samples were mainly generated by local, random (genetic drift), and nonrandom factors (selection and phenotypic plasticity). We present the first craniometric study of three early skulls from the Argentinean Pampas, dated ,8,000 cal. years BP (Arroyo Seco 2, Chocorí, and La Tigra), and one associated with mega-faunal remains (Fontezuelas skull). In addition, we studied several Late Holocene samples. We show that the skulls from the Argentinean Pampas are morphologically similar to other Early Holocene American skulls (i.e., Lagoa Santa from Brazil, Tequendama, Checua, and Aguazuque from Colombia, Lauricocha from Peru, and early Mexicans) that exhibit long and narrow cranial vaults. These samples differ from the Late Holocene American samples that exhibit a shorter and wider cranial vault. Our results underscore the important differences in cranial morphology between early and late-American samples. However, we emphasize the need for further studies to discuss alternative hypotheses regarding such differences. Am J Phys Anthropol 143:298,305, 2010. © 2010 Wiley-Liss, Inc. [source] The shape of the early hominin proximal femurAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Elizabeth H. Harmon Abstract Postcranial skeletal variation among Plio-Pleistocene hominins has implications for taxonomy and locomotor adaptation. Although sample size constraints make interspecific comparisons difficult, postcranial differences between Australopithecus afarensis and Australopithecus africanus have been reported (McHenry and Berger: J Hum Evol 35 1998 1,22; Richmond et al.: J Hum Evol 43 [2002] 529,548; Green et al.: J Hum Evol 52 2007 187,200). Additional evidence indicates that the early members of the genus Homo show morphology like recent humans (e.g., Walker and Leakey: The Nariokotome Homo erectus skeleton. Cambridge: Harvard, 1993). Using a larger fossil sample than previous studies and novel methods, the early hominin proximal femur is newly examined to determine whether new data alter the current view of femoral evolution and inform the issue of interspecific morphological variation among australopiths. Two- and three-dimensional data are collected from large samples of recent humans, Pan, Gorilla, and Pongo and original fossil femora of Australopithecus, Paranthropus, and femora of African fossil Homo. The size-adjusted shape data are analyzed using principal components, thin plate spline analysis, and canonical variate analysis to assess shape variation. The results indicate that femora of fossil Homo are most similar to modern humans but share a low neck-shaft angle (NSA) with australopiths. Australopiths as a group have ape-like greater trochanter morphology. A. afarensis differs from P. robustus and A. africanus in attributes of the neck and NSA. However, interspecific femoral variation is low and australopiths are generally morphologically similar. Although the differences are not dramatic, when considered in combination with other postcranial evidence, the adaptive differences among australopiths in craniodental morphology may have parallels in the postcranium. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] Additional evidence for the affective dimension of dyspnea in patients with COPD,RESEARCH IN NURSING & HEALTH, Issue 1 2010Virginia Carrieri-Kohlman Abstract The primary purpose of this secondary analysis was to determine whether 103 participants with chronic obstructive pulmonary disease rated the affective dimension of dyspnea (dyspnea-related anxiety and dyspnea-related distress) separately from the sensory dimension (intensity) during baseline exercise testing conducted as part of a randomized clinical trial. A secondary purpose was to determine if dyspnea-related anxiety and distress were rated distinctly different from other measurements of anxiety. At the end of a 6-minute walk and an incremental treadmill test, participant ratings of the magnitude of dyspnea-related anxiety and distress on the Modified Borg Scale were significantly different from their ratings of the intensity of dyspnea. Dyspnea-related anxiety and distress also appeared to be concepts independent from measures of state anxiety, negative affect, and anxiety before a treadmill test. © 2009 Wiley Periodicals, Inc. Res Nurs Health 33:4,19, 2010 [source] New evidence on expiration-day effects using realized volatility: An intraday analysis for the Spanish stock exchangeTHE JOURNAL OF FUTURES MARKETS, Issue 9 2006M. Illueca Additional evidence is provided on expiration effects in the Ibex 35 stock index futures market using realized volatility as proposed by T. G. Andersen, T. Bollerslev, F. X. Diebold, and P. Labys (2003). Findings reveal not only a significant increase in spot trading activity, but also the existence of a significant jump in spot volatility at index futures expiration. Moreover, the importance of the data frequency considered is analyzed. Our research reveals that the use of GARCH methodology from daily data does not have the ability to statistically assess such expiration-day effect. Additional empirical evidence is provided for the S&P 500 stock index futures market. Neither unconditional nor conditional realized volatility has a significant increase at expiration for the U.S. market, suggesting that this effect is specific for the Spanish market, at least for the period analyzed. © 2006 Wiley Periodicals, Inc. Jrl Fut Mark 26:923,938, 2006 [source] Increased prevalence of M694V in patients with ankylosing spondylitis: Additional evidence for a link with familial mediterranean feverARTHRITIS & RHEUMATISM, Issue 10 2010Nurullah Akkoc Objective To assess whether there is a statistically significant difference in the frequency of common MEFV allele variants in patients with ankylosing spondylitis (AS) as compared with control patients with rheumatoid arthritis (RA) and with healthy control subjects. Methods Sixty-two patients with AS, 50 healthy control subjects, and 46 patients with RA were assessed for the presence of MEFV variants. Exon 10 was analyzed by direct sequencing. E148Q was analyzed by restriction endonuclease enzyme digestion (REED) or by direct sequencing when REED analysis failed. Results The allele frequency of all MEFV variants in the AS group was significantly higher than that in the pooled control group of healthy subjects plus RA patients (15.3% versus 6.8%; P = 0.021). M694V was the only variant that was significantly more common in the AS group than in the combined or individual control groups (P = 0.026 for AS patients versus healthy controls, P = 0.046 for AS patients versus RA patient controls, and P = 0.008 for AS patients versus healthy and RA patient control groups). The carriage rate of M694V was also significantly higher in the AS patient group than in the combined control group (odds ratio 7.0, P = 0.014). Neither M694V nor any other MEFV variant showed a correlation with most of the disease-related measures examined. Conclusion We found an increased frequency of MEFV variants in AS patients as compared with healthy controls and with RA patient controls. This was primarily due to the presence of M694V. The roles of other exon 10 variants, as well as the relationship between the variant status and the severity and clinical course of the disease, need to be explored in further studies that include sufficiently large sample sizes. [source] Is CEO Duality Always Negative?CORPORATE GOVERNANCE, Issue 2 2009An Exploration of CEO Duality, Ownership Structure in the Arab IPO Context ABSTRACT Manuscript type: Empirical Research Question/Issue: This paper examines the relationships between initial public offering (IPO) underpricing, CEO duality, and strategic ownership in 12 Arab countries of the Middle East and North Africa (MENA) region. Research Findings/Results: Using all IPOs from January 2000 until the end of July 2007, we document an average IPO underpricing of 184.1 per cent. Underpricing is higher in IPO firms that have CEO duality. However, strategic shareholders, such as corporations and other industry-related investors, are likely to play a monitoring role whereas underpricing is found to be lower in firms with both CEO duality and strategic shareholder ownership. Moreover, the negative relation between underpricing and strategic blockholding is greater for foreign strategic ownership than it is for domestic strategic ownership. Theoretical Implications: This paper examines the level and determinants of IPO underpricing in the MENA region. It provides evidence on the role played by foreign strategic owners in reducing agency conflicts and information asymmetries within an environment where firms may be affected by the cultural issues related to political ties and family involvement. Practical Implications: Our results contribute to the existing debate on the appropriate regulations for an effective and stable financial system in Arab countries. They offer policy-makers additional evidence on the positive impact of market openness to foreign shareholders. [source] An Investigation of Localization as an Element of Cognitive Fit in Accounting Model RepresentationsDECISION SCIENCES, Issue 1 2001Cheryl Dunn Abstract Cognitive fit, a correspondence between task and data representation format, has been demonstrated to lead to superior task performance by individual users and has been posited as an explanation for performance differences among users of various problem representations such as tables, graphs, maps, and schematic faces. The current study extends cognitive fit to accounting models and integrates cognitive fit theory with the concept of localization to provide additional evidence for how cognitive fit works. Two accounting model representations are compared in this study, the traditional DCA (Debit-Credit-Account) accounting model and the REA (Resources-Events-Agents) accounting model. Results indicate that the localization of relevant objects or linkages is important in establishing cognitive fit. [source] Fetal valproate syndrome and autism: additional evidence of an associationDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 3 2001Gail Williams MD Autism has been described in association with a variety of medical and genetic conditions. We previously reported on a patient whose clinical phenotype was compatible with both fetal valproate syndrome (FVS) and autism. Here we present five additional patients with FVS and autism. In all five of our patients, there was evidence of cognitive deficits, manifestations of autism, and typical phenotypic characteristics of FVS. The association between this known teratogen and autism has both clinical and research implications. [source] Gender differences in unipolar depression: an update of epidemiological findings and possible explanationsACTA PSYCHIATRICA SCANDINAVICA, Issue 3 2003C. Kuehner Objective: To give an update on epidemiological findings on sex differences in the prevalence of unipolar depression and putative risk factors. Material and methods: Systematic review of the literature. Results: Recent epidemiological research yields additional evidence for a female preponderance in unipolar depression, holding true across different cultural settings. Current explanations include artefacts, genetic, hormonal, psychological and psychosocial risk factors. Rather consistently, intrapsychic and psychosocial gender role related risk factors have been identified which may contribute to the higher depression risk in women. Gender role aspects are also reflected in endocrine stress reactions and possibly influence associated neuropsychological processes. Conclusion: There is a need for more integrative models taking into account psychological, psychosocial, and macrosocial risk factors as well as their interactions, which also connect these factors with physiological and endocrine responses. Furthermore, it is conceivable that across the life span, as well as across cultural settings, individual risk factors will add with varying emphasis to the higher prevalence of depression in women. [source] Voltage-Dependent Block of N -Methyl- d -Aspartate Receptors by the Novel Anticonvulsant Dibenzylamine, a Bioactive Constituent of l -(+)-,-HydroxybutyrateEPILEPSIA, Issue 10 2003Sean D. Donevan Summary:,Purpose: Previously we demonstrated that l -(+)-,-hydroxybutyrate (L-BHB), acetoacetate (ACA), acetone, and dibenzylamine (DBA) were anticonvulsant in an audiogenic seizure,susceptible model, and that DBA was a bioactive contaminant identified in commercial lots of L-BHB. In the present study, we asked whether these effects could be mediated by ionotropic glutamate or ,-aminobutyric acidA (GABAA) receptors. Methods: We studied the effects of both stereoisomers of BHB (as well as the racemate), ACA, and DBA on N -methyl- d -aspartate (NMDA), ,-amino-3-hydroxy-5methyl-4-isoxazole-proprionic acid (AMPA), and GABAA receptors in cultured rodent neocortical neurons by using whole-cell voltage-clamp recording techniques. Results: Only L-BHB and DBA exerted a concentration- and voltage-dependent block of NMDA-evoked currents, whereas none of the tested substrates affected AMPA- or GABA-activated currents. The kinetics of whole-cell block by L-BHB and DBA were similar, providing additional evidence that DBA is responsible for the anticonvulsant activity of L-BHB. Conclusions: BHB and ACA do not exert direct actions on GABAA or ionotropic glutamate receptors in cultured neocortical neurons. In addition, we provide additional evidence that DBA is responsible for the anticonvulsant activity of L-BHB, and that this action may be mediated in part by voltage-dependent blockade of NMDA receptors. [source] Involvement of Gln937 of Streptococcus downei GTF-I glucansucrase in transition-state stabilizationFEBS JOURNAL, Issue 13 2000Vincent Monchois Multiple alignment of deduced amino-acid sequences of glucansucrases (glucosyltransferases and dextransucrases) from oral streptococci and Leuconostoc mesenteroides has shown them to share a well-conserved catalytic domain. A portion of this domain displays homology to members of the ,-amylase family (glycoside hydrolase family 13), which all have a (,/,)8 barrel structure. In the glucansucrases, however, the ,-helix and ,-strand elements are circularly permuted with respect to the order in family 13. Previous work has shown that amino-acid residues contributing to the active site of glucansucrases are situated in structural elements that align with those of family 13. In ,-amylase and cyclodextrin glucanotransferase, a histidine residue has been identified that acts to stabilize the transition state, and a histidine is conserved at the corresponding position in all other members of family 13. In all the glucansucrases, however, the aligned position is occupied by glutamine. Mutants of glucosyltransferase I were constructed in which this glutamine, Gln937, was changed to histidine, glutamic acid, aspartic acid, asparagine or alanine. The effects on specific activity, ability to form glucan and ability to transfer glucose to a maltose acceptor were examined. Only histidine could substitute for glutamine and maintain Michaelis,Menten kinetics, albeit at a greatly reduced kcat, showing that Gln937 plays a functionally equivalent role to the histidine in family 13. This provides additional evidence in support of the proposed alignment of the (,/,)8 barrel structures. Mutation at position 937 altered the acceptor reaction with maltose, and resulted in the synthesis of novel gluco-oligosaccharides in which ,1,3-linked glucosyl units are joined sequentially to maltose. [source] From Ag Nanoprisms to Triangular AuAg NanoboxesADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Damian Aherne Abstract In recent years, galvanic replacement reactions have been successfully employed to produce hollow bimetallic nanostructures of a range of shapes, yet to date there has been no example of the formation of hollow triangular AuAg nanostructures from a Ag nanoprism template. In this manuscript the first example of the synthesis of enclosed triangular AuAg nanostructures (triangular nanoboxes) via galvanic replacement reactions from Ag nanoprisms is reported. These triangular nanoboxes are studied by TEM and HAADF-STEM imaging to elucidate their structure. These studies show that the nanostructures are hollow and do not consist of a Ag core surrounded by a Au shell. Discrete dipole approximation calculations for the extinction spectra are carried out and provide additional evidence that the nanostructures are hollow. These new triangular nanoboxes are very attractive candidates for encapsulation and transport of materials of interest such as drugs, radioisotopes, or magnetic materials. [source] Early Versus Late Start in Foreign Language Education: Documenting AchievementsFOREIGN LANGUAGE ANNALS, Issue 4 2005Rocío Domínguez Abstract: This study compares 27 sixth grade students who have been learning Spanish since kindergarten with 5 who have had Spanish for only 1 year using a battery of Spanish oral and written tests. The students who started early outperformed the new students in listening, speaking, and writing Spanish. Those who started early also displayed a positive attitude toward speaking Spanish in the classroom, a high level of confidence in their Spanish oral and literacy skills, and the use of sophisticated language structures in writing. These findings provide additional evidence supporting the case for early foreign language learning. [source] The relative importance of local conditions and regional processes in structuring aquatic plant communitiesFRESHWATER BIOLOGY, Issue 5 2010ROBERT S. CAPERS Summary 1. The structure of biological communities reflects the influence of both local environmental conditions and processes such as dispersal that create patterns in species' distribution across a region. 2. We extend explicit tests of the relative importance of local environmental conditions and regional spatial processes to aquatic plants, a group traditionally thought to be little limited by dispersal. We used partial canonical correspondence analysis and partial Mantel tests to analyse data from 98 lakes and ponds across Connecticut (northeastern United States). 3. We found that aquatic plant community structure reflects the influence of local conditions (pH, conductivity, water clarity, lake area, maximum depth) as well as regional processes. 4. Only 27% of variation in a presence/absence matrix was explained by environmental conditions and spatial processes such as dispersal. Of the total explained, 45% was related to environmental conditions and 40% to spatial processes. 5. Jaccard similarity declined with Euclidean distance between lakes, even after accounting for the increasing difference in environmental conditions, suggesting that dispersal limitation may influence community composition in the region. 6. The distribution of distances among lakes where species occurred was associated with dispersal-related functional traits, providing additional evidence that dispersal ability varies among species in ways that affect community composition. 7. Although environmental and spatial variables explained a significant amount of variation in community structure, a substantial amount of stochasticity also affects these communities, probably associated with unpredictable colonisation and persistence of the plants. [source] Reduced aggression in AMPA-type glutamate receptor GluR-A subunit-deficient miceGENES, BRAIN AND BEHAVIOR, Issue 5 2004O. Y. Vekovischeva The importance of AMPA-type glutamate receptors has been demonstrated in neuronal plasticity and in adaptation to drugs of abuse. We studied the involvement of AMPA receptors in social interaction and anxiety and found that in several paradigms of agonistic behavior naïve male mice deficient for the GluR-A subunit- containing AMPA receptors are less aggressive than wild-type littermates. GluR-A deficient mice and wild-type littermates exhibited similar basic behavior and reflexes as monitored by observational Irwin's test, but they tended to be less anxious in elevated plus-maze and light-dark tests. Maternal aggression or male-female encounters were not affected which suggests that male hormones are involved in the expression of suppressed aggressiveness. However, testosterone levels and brain monoamines can be excluded and found to be similar between GluR-A deficient and wild-type littermates. The reduced AMPA receptor levels caused by the lack of the GluR-A subunit, and measured by a 30% reduction in hippocampal [3H]-S-AMPA binding, seem to be the reason for suppressed male aggressiveness. When we analyzed mice with reduced number of functional AMPA receptors mediated by the genomic introduced GluR-A(Q582R) channel mutation, we observed again male-specific suppressed aggression, providing additional evidence for GluR-A subunit-containing AMPA receptor involvement in aggression. [source] Localization of a putative low-penetrance ependymoma susceptibility locus to 22q11 using a chromosome 22 tiling-path genomic microarrayGENES, CHROMOSOMES AND CANCER, Issue 4 2005Anneke C. J. Ammerlaan Ependymomas frequently display allelic loss of chromosome 22 in the absence of mutations in the known tumor-suppressor genes on chromosome 22, suggesting the role of an alternative predisposing gene or genes from this chromosome. In an effort to localize these genes, 37 ependymomas derived from 33 patients were analyzed for the presence of copy number changes by use of a high-resolution chromosome 22 genomic microarray. Eighteen ependymomas (49%) displayed an array-CGH profile consistent with monosomy of chromosome 22. However, in 10 of these tumors, the fluorescence ratios for 22q clones scored as deleted were different from those at the single gene copy level. This suggests either analysis of mixed populations of tumor and normal stromal cells or analysis of mixed tumor cell populations with different genetic profiles. Four ependymomas derived from two patients showed overlapping interstitial deletions of 2.2 Mb and ,510 kb. Further analyses revealed that these deletions were present in the constitutional DNA of these two patients as well as in some of their unaffected relatives. Detailed microsatellite analysis of these families refined the commonly deleted segment to a region of 320 kb between markers RH13801 and D22S419. Our results provide additional evidence for the involvement of genes on chromosome 22 in the development of ependymoma and suggest the presence of a low-penetrance ependymoma susceptibility locus at 22q11. © 2005 Wiley-Liss, Inc. [source] A simulation of the hydrothermal response to the Chesapeake Bay bolide impactGEOFLUIDS (ELECTRONIC), Issue 3 2005W. E. SANFORD Abstract Groundwater more saline than seawater has been discovered in the tsunami breccia of the Chesapeake Bay Impact Crater. One hypothesis for the origin of this brine is that it may be a liquid residual following steam separation in a hydrothermal system that evolved following the impact. Initial scoping calculations have demonstrated that it is feasible such a residual brine could have remained in the crater for the 35 million years since impact. Numerical simulations have been conducted using the code HYDROTHERM to test whether or not conditions were suitable in the millennia following the impact for the development of a steam phase in the hydrothermal system. Hydraulic and thermal parameters were estimated for the bedrock underlying the crater and the tsunami breccia that fills the crater. Simulations at three different breccia permeabilities suggest that the type of hydrothermal system that might have developed would have been very sensitive to the permeability. A relatively low breccia permeability (1 × 10,16 m2) results in a system partitioned into a shallow water phase and a deeper superheated steam phase. A moderate breccia permeability (1 × 10,15 m2) results in a system with regionally extensive multiphase conditions. A relatively high breccia permeability (1 × 10,14 m2) results in a system dominated by warm-water convection cells. The permeability of the crater breccia could have had any of these values at given depths and times during the hydrothermal system evolution as the sediments compacted. The simulations were not able to take into account transient permeability conditions, or equations of state that account for the salt content of seawater. Results suggest, however, that it is likely that steam conditions existed at some time in the system following impact, providing additional evidence that is consistent with a hydrothermal origin for the crater brine. [source] The 1933 Ms= 7.3 Baffin Bay earthquake: strike-slip faulting along the northeastern Canadian passive marginGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2002Allison L. Bent Summary The 1933 November 20 (Ms= 7.3) Baffin Bay earthquake is one of the largest instrumentally recorded passive margin earthquakes. Analysis of seismograms of this earthquake shows strong evidence for strike-slip faulting, which contrasts with the generally accepted belief that Baffin Bay is dominated by thrust faulting. The best-fitting solution consists of a large strike-slip subevent (strike 172°, dip 82°, rake 6°) followed by two smaller oblique-thrust subevents (strike 190°, dip 30°, rake 62°). All subevents occur at a depth of about 10 km. An instrumental moment magnitude of 7.4 was determined. Preliminary analysis of subsequent large (magnitude , 6.0) earthquakes in Baffin Bay finds additional evidence for strike-slip faulting in the region. The results for Baffin Bay, together with those for other passive margin earthquakes, suggest strike-slip faulting may be more prevalent in these regions than was previously believed. [source] Common birds facing global changes: what makes a species at risk?GLOBAL CHANGE BIOLOGY, Issue 1 2004Romain Julliard Abstract Climate change, habitat degradation, and direct exploitation are thought to threaten biodiversity. But what makes some species more sensitive to global change than others? Approaches to this question have relied on comparing the fate of contrasting groups of species. However, if some ecological parameter affects the fate of species faced with global change, species response should vary smoothly along the parameter gradient. Thus, grouping species into few, often two, discrete classes weakens the approach. Using data from the common breeding bird survey in France , a large set of species with much variability with respect to the variables considered , we show that a quantitative measure of habitat specialization and of latitudinal distribution both predict recent 13 year trends of population abundance among 77 terrestrial species: the more northerly distributed and the more specialized a species is, the sharper its decline. On the other hand, neither hunting status, migrating strategy nor body mass predicted population growth rate variation among common bird species. Overall, these results are qualitatively very similar to the equivalent relationships found among the British butterfly populations. This constitutes additional evidence that biodiversity in Western Europe is under the double negative influence of climate change and land use change. [source] Pliocene forest dynamics as a primary driver of African bird speciationGLOBAL ECOLOGY, Issue 1 2010Gary Voelker ABSTRACT Aim, Montane tropics are areas of high endemism, and mechanisms driving this endemism have been receiving increasing attention at a global scale. A general trend is that climatic factors do not explain the species richness of species with small to medium-sized geographic ranges, suggesting that geological and evolutionary processes must be considered. On the African continent, several hypotheses including both refugial and geographic uplift models have been advanced to explain avian speciation and diversity in the lowland forest and montane regions of central and eastern Africa; montane regions in particular are recognized as hotspots of vertebrate endemism. Here, we examine the possible role of these models in driving speciation in a clade of African forest robins. Location, Africa. Methods, We constructed the first robustly supported molecular phylogenetic hypothesis of forest robins. On this phylogeny, we reconstructed habitat-based distributions and geographic distributions relative to the Albertine Rift. We also estimated the timing of lineage divergences via a molecular clock. Results, Robust estimates of phylogenetic relationships and clock-based divergences reject Miocene tectonic uplift and Pleistocene forest refugia as primary drivers of speciation in forest robins. Instead, our data suggest that most forest robin speciation took place in the Late Pliocene, from 3.2 to 2.2 Ma. Distributional patterns are complex, with the Albertine Rift region serving as a general east,west break across the group. Montane distributions are inferred to have evolved four times. Main conclusions, Phylogenetic divergence dates coincide with a single period of lowland forest retraction in the late Pliocene, suggesting that most montane speciation resulted from the rapid isolation of populations in montane areas, rather than montane areas themselves being drivers of speciation. This conclusion provides additional evidence that Pliocene climate change was a major driver of speciation in broadly distributed African animal lineages. We further show that lowland forest robins are no older than their montane relatives, suggesting that lowland areas are not museums which house ,ancient' taxa; rather, for forest robins, montane areas should be viewed as living museums of a late Pliocene diversification event. A forest refugial pattern is operating in Africa, but it is not constrained to the Pleistocene. [source] Gastric Stasis Occurs in Spontaneous, Visually Induced, and Interictal MigraineHEADACHE, Issue 10 2007Sheena Aurora MD Objective., To evaluate and compare gastric motility and emptying during spontaneous migraine to previous observations from induced migraine. Blackground., We have previously demonstrated a delay in gastric emptying both during the interictal period and during an induced migraine. A limitation noted in these studies was whether there are differences gastrointestinally during a visually induced migraine compared to spontaneous migraines. To address this, 9 additional studies have been performed to ascertain if there is a similar delay during spontaneous migraine Methods., Gastric scintigraphy using a standard meal was performed in 3 subjects during 3 periods: spontaneous migraine, induced migraine, and interictal period. Results., On average, the time to half emptying was delayed during spontaneous migraine (124 minutes), during induced migraine (182 minutes), and during the interictal period migraine (243 minutes) compared to normative values established at our center (112 minutes). On average, similar gastric slowing was seen in all 3 groups when the percentage of nuclear material remaining in the stomach at 2 hours was measured. Conclusions., This study provides additional evidence of gastric stasis in migraineurs interictally during induced and spontaneous migraine. [source] Expression of CD30 (Ber-H2) in nasopharyngeal carcinoma, undifferentiated type and lymphoepithelioma-like carcinoma.HISTOPATHOLOGY, Issue 7 2006A comparison study with anaplastic large cell lymphoma Aims :,Undifferentiated nasopharyngeal non-keratinizing carcinoma (UNPC), formerly known as lymphoepithelioma, frequently metastasizes at an early stage to regional lymph nodes and, thus, may be difficult to distinguish from Hodgkin's lymphoma (HL) or anaplastic large cell lymphoma (ALCL). CD30 expression is a useful diagnostic stain in both HL and ALCL, but its expression in UNPC deserves clarification. The aim of this study was to evaluate CD30 expression in UNPC and lymphoepithelioma-like carcinoma (LELC) from other anatomic locations and compare it with ALCL and squamous cell carcinoma (SCC). Methods and results :,CD30 immunoreactivity was examined in 38 cases of primary or metastatic UNPC, six cases of LELC, 10 cases of SCC and seven cases of ALCL. CD30 immunoreactivity was observed in four of 38 (10.5%) cases of UNPC. CD30 staining was absent in all cases of LELC (0/6) and SCC (0/10). All cases of ALCL (7/7) were strongly positive for CD30. Conclusions :,The majority of cases of UNPC are immunohistochemically negative for CD30; however, a small subset of cases expresses CD30 antigen. These findings provide additional evidence that CD30 expression is not restricted to neoplasms of lymphoid origin. This should be taken into consideration when interpreting CD30 immunohistology and the possibility of UNPC. [source] Using time-domain reflectometry to characterize shallow solute transport in an oak woodland hillslope in northern California, USAHYDROLOGICAL PROCESSES, Issue 15 2002Chris G. Campbell Abstract The natural heterogeneity of water and solute movement in hillslope soils makes it difficult to accurately characterize the transport of surface-applied pollutants without first gathering spatially distributed hydrological data. This study examined the application of time-domain reflectometry (TDR) to measure solute transport in hillslopes. Three different plot designs were used to examine the transport of a conservative tracer in the first 50 cm of a moderately sloping soil. In the first plot, which was designed to examine spatial variability in vertical transport in a 1·2 m2 plot, a single probe per meter was found to adequately characterize vertical solute travel times. In addition, a dye and excavation study in this plot revealed lateral preferential flow in small macropores and a transport pattern where solute is focused vertically into preferential flow pathways. The bypass flow delivers solute deeper in the soil, where lateral flow occurs. The second plot, designed to capture both vertical and lateral flow, provided additional evidence confirming the flow patterns identified in the excavation of the first plot. The third plot was designed to examine lateral flow and once again preferential flow of the tracer was observed. In one instance rapid solute transport in this plot was estimated to occur in as little as 3% of the available pore space. Finally, it was demonstrated that the soil anisotropy, although partially responsible for lateral subsurface transport, may also homogenize the transport response across the hillslope by decreasing vertical solute spreading. Copyright © 2002 John Wiley & Sons, Ltd. [source] The rapid spread of invasive Eurasian Collared Doves Streptopelia decaocto in the continental USA follows human-altered habitatsIBIS, Issue 3 2010IKUKO FUJISAKI Understanding factors related to the range expansion trajectory of a successful invasive species may provide insights into environmental variables that favour additional expansion or guide monitoring and survey efforts for this and other invasive species. We examined the relationship of presence and abundance of Eurasian Collared Doves Streptopelia decaocto to environmental factors using recent data from the North American Breeding Bird Survey to understand factors influencing its expansion into the continental USA. A zero-inflated Poisson (ZIP) model was used to account for excess zero observations because this species was not observed on the majority of survey routes, despite its large geographical range. Model fit was improved when we included environmental covariates as compared with the null model, which only included distance from the route where this species was first observed. Probability of zero count was positively related to the distance from the first route and road density and was inversely related to minimum temperature and distance to coast. Abundance of the species was positively related to road density and was inversely related to annual precipitation and distance to coast. Random intercept by land-cover type also improved model fit. Model fit was improved with the ZIP model over the standard Poisson model, suggesting that presence and abundance of this species are characterized by different environmental factors. However, overall low accuracy of model-predicted presence/absence and abundance with the independent validation dataset may indicate either that there are other explanatory factors or that there is great uncertainty in the species' colonization process. Our large-scale study provides additional evidence that the range expansion of this species tends to follow human-altered landscapes such as road and agricultural areas as well as responding to general geographical features such as coastlines or thermal clines. Such patterns may hold true for other invasive species and may provide guidelines for monitoring and assessment activities in other invasive taxa. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||