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Selected AbstractsIMF Gold and the World Bank's Unfunded HIPC DeficitDEVELOPMENT POLICY REVIEW, Issue 1 2004Jonathan E. Sanford The World Bank is to forgive $12.24 billion in IDA debt payments from HIPC borrowers. It has received $1 billion from the HIPC Trust Fund to help offset these losses, but still has a $11.6 billion unfunded liability. The IMF has gold worth $38 billion on hand for which it has no actual use. This article proposes that a small portion of IMF gold be sold annually, just enough to offset IDA's annual HIPC deficit, over the next twenty years. The new money would be additional and predictable, and would eliminate the prospect that IDA would have to cut back its future flow of aid because the HIPC programme had drained its resources. [source] Genetic and pharmacological studies of GluR5 modulation of inhibitory synaptic transmission in the anterior cingulate cortex of adult miceDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2007Long-Jun Wu Abstract In the anterior cingulate cortex (ACC), GluR5-containing kainate receptor mediated the small portion of excitatory postsynaptic current. However, little is known about its role in modulation of neurotransmitter release in this brain region. In the present study, we address this question by using selective GluR5 agonist and antagonist, as well as GluR5,/, mice. Our results showed that activation of GluR5 induced action potential-dependent GABA release, which is also required for the activation of voltage-dependent calcium channel and Ca2+ influx. The effect of GluR5 activation is selective to the GABAergic, but not glutamatergic synaptic transmission. Endogenous activation of GluR5 also enhanced GABA release to ACC pyramidal neurons and the corresponding postsynaptic tonic GABA current. Our results suggest the somatodendritic, but not presynaptic GluR5, in modulation of GABA release. The endogenous GluR5 activation and the subsequent tonic GABA current may play an inhibitory role in ACC-related brain functions. © 2006 Wiley Periodicals, Inc. Develop Neurobiol 67: 146,157, 2007. [source] Palpable Cardiac Impulse Predicts Adequate Acoustic WindowsECHOCARDIOGRAPHY, Issue 1 2000F.A.C.C., JAMES P. EICHELBERGER M.D. In this study, we sought to determine the usefulness of palpating an apical cardiac impulse on physical examination in predicting adequate echocardiographic images for stress echocardiography. A variety of stress tests using either echocardiographic imaging or nuclear imaging are available to referring physicians. Deciding which test is best for a given patient is often dificult. In the case of stress echocardiography, the most significant limitation is poor image quality i n a small portion of patients. We enrolled 136 consecutive outpatients referred for echocardiography. The presence or absence of a palpable cardiac apex on physical examination was recorded by two independent and blinded examiners. Data, including age, sex, weight, prior chest surgery, and smoking, were also collected. Echocardiographic imaging of the left ventricle was scored according to the number of adequately visualized wall segments in a standard 16-segment model. One hundred eleven patients (82%) had adequate visualization of at least 14 of 16 wall segments. Ninety-eight patients (72%) had a palpable cardiac impulse, of whom 90 (92%) also had adequate acoustic image quality versus only 21 (55%) of the 38patients in whom an apex was not palpable (P < 0.0001). Other variables that were measured were not significantly related to image quality, with the exception of weight; patients with adequate images weighed a mean of 75 kg versus 91 kg i n those with inadequate images (P < 0.0006). However, multivariate analysis showed a palpable apex to be the only independent predictor after controlling for other variables. A physical examination assessment for a palpable apical impulse is useful to predict adequate echocardiographic image quality for stress echocardiography. When used in conjunction with other parameters, this may lead to more appropriate referral to augmented stress testing. (ECHOCARDIOGRAPm, Volume 17, January 2000) [source] Functional role of human NK cell receptor 2B4 (CD244) isoformsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2009Stephen O. Mathew Abstract 2B4 (CD244), a member of the signaling lymphocyte-activation molecule (SLAM/CD150), is expressed on all NK cells, a subpopulation of T cells, monocytes and basophils. Human NK cells express two isoforms of 2B4, h2B4-A and h2B4-B that differ in a small portion of the extracellular domain. In the present investigation, we have studied the functions of h2B4-A and h2B4-B. Our study demonstrated that these two isoforms differ in their binding affinity for CD48, which results in differential cytotoxic activity as well as intracellular calcium release by NK cells upon target cell recognition. Analysis of the predicted 3-D structure of the two isoforms showed conformational differences that could account for their differences in binding affinity to CD48. h2B4-A was able to mediate natural cytotoxicity against CD48-expressing K562 target cells and induce intracellular calcium release, whereas h2B4-B showed no effects. NK-92MI, U937, THP-1, KU812, primary monocytes, basophils and NK cells showed expression of both h2B4-A and h2B4-B whereas YT and IL-2-activated NK cells did not show any h2B4-B expression. Stimulation of NK cells through 2B4 resulted in decreased mRNA levels of both h2B4-A and h2B4-B indicating that down-regulation of 2B4 isoforms may be an important factor in controlling NK cell activation during immune responses. [source] Connecting Atmosphere and Wetland: Energy and Water Vapour ExchangeGEOGRAPHY COMPASS (ELECTRONIC), Issue 4 2008Peter M. Lafleur Wetlands are ubiquitous over the globe, comprise a vast array of ecosystem types and are of great ecological and social importance. Their functioning is intimately tied to the atmosphere by the energy and mass exchanges that take place across the wetland,atmosphere boundary. This article examines recent research into these exchanges, with an emphasis on the water vapour exchange. Although broad classes of wetland type, such as fen, bog and marsh, can be defined using ecological or hydrologic metrics, distinct difference in energy exchanges between the classes cannot be found. This arises because there are many factors that control the energy exchanges and interplay of these factors is unique to every wetland ecosystem. Wetlands are more similar in their radiation balances than in the partitioning of this energy into conductive and turbulent heat fluxes. This is especially true of evapotranspiration (ET) rates, which vary considerably among and within wetland classes. A global survey of wetland ET studies shows that location has little to do with ET rates and that variation in rates is largely determined by local climate and wetland characteristics. Recent modelling studies suggest that although wetlands occupy a small portion of the global land surface, their water and energy exchanges may be important in regional and global climates. Although the number of studies of wetland,atmosphere interactions has increased in recent years more research is needed. Five key areas of study are identified: (i) the importance of moss covers, (ii) lack of study in tropical systems, (iii) inclusion of wetlands in global climate models, (iv) importance of microforms in wetlands and their scaling to the whole ecosystem, and (v) the paucity of annual ET measurements. [source] Finding an Adequate Job: Employment and Income of Recent Immigrants to IsraelINTERNATIONAL MIGRATION, Issue 2 2003Haya Stier Summary The study examines the early market experience of recent immigrants to Israel from the former Soviet Union (FSU) and their mobility patterns a few years after migration. The Labour Utilization Framework, proposed by Clogg and Sullivan (1983), was analysed to identify the employment difficulties immigrants experienced upon arrival, their short-term mobility in the labour market, and the income consequences of their disadvantaged position in the market. Using a panel study of immigrants who arrived in Israel during 1990, we found that although most of them found employment, only a minority did not experience employment hardships. Four years after their arrival, most immigrants were still employed in occupations for which they were over-qualified, and only a small portion of the group managed to find adequate employment. Women had more severe employment hardships and a lower rate of mobility into the better positions. For men and women alike, almost any deviation from a stable adequate employment entailed wage penalties. [source] Ethical Considerations for a Child's Participation in ResearchJOURNAL FOR SPECIALISTS IN PEDIATRIC NURSING, Issue 1 2004Sheri Kanner MSN ISSUES AND PURPOSE To analyze ethical considerations for a child's involvement in research. CONCLUSIONS Pediatric research can proceed only when the welfare of children is protected. Although research with children as research subjects constitutes only a small portion of research efforts, its continual growth requires nurses be aware of the rights of pediatric subjects. PRACTICE IMPLICATIONS As nursing research increases in sophistication, the nurse should include an assessment of the informed consent process in the care of the patient, including the child's comprehension, the age and development of the child, and the child's perception of the research. [source] Setting Eligibility Criteria for a Care-Coordination BenefitJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 12 2005Christine T. Cigolle MD Objectives: To examine different clinically relevant eligibility criteria sets to determine how they differ in numbers and characteristics of individuals served. Design: Cross-sectional analysis of the 2000 wave of the Health and Retirement Study (HRS), a nationally representative longitudinal health interview survey of adults aged 50 and older. Setting: Population-based cohort of community-dwelling older adults, subset of an ongoing longitudinal health interview survey. Participants: Adults aged 65 and older who were respondents in the 2000 wave of the HRS (n=10,640, representing approximately 33.6 million Medicare beneficiaries). Measurements: Three clinical criteria sets were examined that included different combinations of medical conditions, cognitive impairment, and activity of daily living/instrumental activity of daily living (ADL/IADL) dependency. Results: A small portion of Medicare beneficiaries (1.3,5.8%) would be eligible for care coordination, depending on the criteria set chosen. A criteria set recently proposed by Congress (at least four severe complex medical conditions and one ADL or IADL dependency) would apply to 427,000 adults aged 65 and older in the United States. Criteria emphasizing cognitive impairment would serve an older population. Conclusion: Several criteria sets for a Medicare care-coordination benefit are clinically reasonable, but different definitions of eligibility would serve different numbers and population groups of older adults. [source] Patterns of species richness on very small islands: the plants of the Aegean archipelagoJOURNAL OF BIOGEOGRAPHY, Issue 7 2006Maria Panitsa Abstract Aim, To investigate the species,area relationship (SAR) of plants on very small islands, to examine the effect of other factors on species richness, and to check for a possible Small Island Effect (SIE). Location, The study used data on the floral composition of 86 very small islands (all < 0.050 km2) of the Aegean archipelago (Greece). Methods, We used standard techniques for linear and nonlinear regression in order to check several models of the SAR, and stepwise multiple regression to check for the effects of factors other than area on species richness (,habitat diversity', elevation, and distance from nearest large island), as well as the performance of the Choros model. We also checked for the SAR of certain taxonomic and ecological plant groups that are of special importance in eastern Mediterranean islands, such as halophytes, therophytes, Leguminosae and Gramineae. We used one-way anova to check for differences in richness between grazed and non-grazed islands, and we explored possible effects of nesting seabirds on the islands' flora. Results, Area explained a small percentage of total species richness variance in all cases. The linearized power model of the SAR provided the best fit for the total species list and several subgroups of species, while the semi-log model provided better fits for grazed islands, grasses and therophytes. None of the nonlinear models explained more variance. The slope of the SAR was very high, mainly due to the contribution of non-grazed islands. No significant SIE could be detected. The Choros model explained more variance than all SARs, although a large amount of variance of species richness still remained unexplained. Elevation was found to be the only important factor, other than area, to influence species richness. Habitat diversity did not seem important, although there were serious methodological problems in properly defining it, especially for plants. Grazing was an important factor influencing the flora of small islands. Grazed islands were richer than non-grazed, but the response of their species richness to area was particularly low, indicating decreased floral heterogeneity among islands. We did not detect any important effects of the presence of nesting seabird colonies. Main conclusions, Species richness on small islands may behave idiosyncratically, but this does not always lead to a typical SIE. Plants of Aegean islets conform to the classical Arrhenius model of the SAR, a result mainly due to the contribution of non-grazed islands. At the same time, the factors examined explain a small portion of total variance in species richness, indicating the possible contribution of other, non-standard factors, or even of stochastic effects. The proper definition of habitat diversity as pertaining to the taxon examined in each case is a recurrent problem in such studies. Nevertheless, the combined effect of area and a proxy for environmental heterogeneity is once again superior to area alone in explaining species richness. [source] Application of the frozen atom approximation to the GB/SA continuum model for solvation free energyJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2002Olgun Guvench Abstract The generalized Born/surface area (GB/SA) continuum model for solvation free energy is a fast and accurate alternative to using discrete water molecules in molecular simulations of solvated systems. However, computational studies of large solvated molecular systems such as enzyme,ligand complexes can still be computationally expensive even with continuum solvation methods simply because of the large number of atoms in the solute molecules. Because in such systems often only a relatively small portion of the system such as the ligand binding site is under study, it becomes less attractive to calculate energies and derivatives for all atoms in the system. To curtail computation while still maintaining high energetic accuracy, atoms distant from the site of interest are often frozen; that is, their coordinates are made invariant. Such frozen atoms do not require energetic and derivative updates during the course of a simulation. Herein we describe methodology and results for applying the frozen atom approach to both the generalized Born (GB) and the solvent accessible surface area (SASA) parts of the GB/SA continuum model for solvation free energy. For strictly pairwise energetic terms, such as the Coulombic and van-der-Waals energies, contributions from pairs of frozen atoms can be ignored. This leaves energetic differences unaffected for conformations that vary only in the positions of nonfrozen atoms. Due to the nonlocal nature of the GB analytical form, however, excluding such pairs from a GB calculation leads to unacceptable inaccuracies. To apply a frozen-atom scheme to GB calculations, a buffer region within the frozen-atom zone is generated based on a user-definable cutoff distance from the nonfrozen atoms. Certain pairwise interactions between frozen atoms in the buffer region are retained in the GB computation. This allows high accuracy in conformational GB comparisons to be maintained while achieving significant savings in computational time compared to the full (nonfrozen) calculation. A similar approach for using a buffer region of frozen atoms is taken for the SASA calculation. The SASA calculation is local in nature, and thus exact SASA energies are maintained. With a buffer region of 8 Ĺ for the frozen-atom cases, excellent agreement in differences in energies for three different conformations of cytochrome P450 with a bound camphor ligand are obtained with respect to the nonfrozen cases. For various minimization protocols, simulations run 2 to 10.5 times faster and memory usage is reduced by a factor of 1.5 to 5. Application of the frozen atom method for GB/SA calculations thus can render computationally tractable biologically and medically important simulations such as those used to study ligand,receptor binding conformations and energies in a solvated environment. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 214,221, 2002 [source] A convenient purification and preconcentration of peptides with ,-cyano-4-hydroxycinnamic acid matrix crystals in a pipette tip for matrix-assisted laser desorption/ionization mass spectrometry,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2010Helena, ehulková Abstract Peptide samples derived from enzymatic in-gel digestion of proteins resolved by gel electrophoresis often contain high amount of salts originating from reaction and separation buffers. Different methods are used for desalting prior to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), e.g. reversed-phase pipette tip purification, on-target washing, adding co-matrices, etc. As a suitable matrix for MALDI MS of peptides, ,-cyano-4-hydroxycinnamic acid (CHCA) is frequently used. Crystalline CHCA shows the ability to bind peptides on its surface and because it is almost insoluble in acidic water solutions, the on-target washing of peptide samples can significantly improve MALDI MS signals. Although the common on-target washing represents a simple, cheap and fast procedure, only a small portion of the available peptide solution is efficiently used for the subsequent MS analysis. The present approach is a combination of the on-target washing principle carried out in a narrow-end pipette tip (e.g. GELoader tip) and preconcentration of peptides from acidified solution by passing it through small CHCA crystals captured inside the tip on a glass microfiber frit. The results of MALDI MS analysis using CHCA-tip peptide preconcentration are comparable with the use of homemade POROS R2 pipette tip microcolumns. Advantages and limitations of this approach are discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Numerical analysis of thermal and electrochemical phenomena for anode supported microtubular SOFCAICHE JOURNAL, Issue 3 2009Daan Cui Abstract A 2D model considering momentum, heat/species transport and electrochemical phenomena, has been proposed for tubular solid oxide fuel cell. The model was validated using experimental polarization curves and the good agreement with the experimental data was attained. The temperature distributions show that temperature varies severely at the tube inlet than at the tube outlet. The heat generation and transfer mechanisms in electrodes, electrolyte and electrochemical reaction interface were investigated. The results show that the overall electrochemical reaction heat is produced at cathode/electrolyte interface, and a small portion of the heat is consumed at anode/electrolyte interface. The heat produced at cathode/electrolyte interface is about five times as much as that consumed at anode/electrolyte interface. Overwhelming part of the heat transfer between cell and outside occurs at cathode external surface. Most current flow goes into anode from a very small area where the current collectors locates. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Mechanisms of glutamate release elicited in rat cerebrocortical nerve endings by ,pathologically' elevated extraterminal K+ concentrationsJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Luca Raiteri Abstract Extracellular [K+] can increase during some pathological conditions, resulting into excessive glutamate release through multiple mechanisms. We here investigate the overflow of [3H]d -aspartate ([3H] d -ASP) and of endogenous glutamate elicited by increasing [K+] from purified rat cerebrocortical synaptosomes. Depolarization with [K+] , 15 mmol/L provoked [3H] d -ASP and glutamate overflows almost totally dependent on external Ca2+. Consistent with release by exocytosis, the overflow of [3H] d -ASP evoked by 12 mmol/L K+ was sensitive to clostridial toxins. The overflows evoked by 35/50 mmol/L K+ remained external Ca2+ -dependent by more than 50%. The Ca2+ -independent components of the [3H] d -ASP overflows evoked by [K+] > 15 mmol/L were prevented by the glutamate transporter inhibitors dl - threo -beta-benzyloxyaspartate (dl -TBOA) and dihydrokainate. Differently, the overflows of endogenous glutamate provoked by [K+] > 15 mmol/L were insensitive to both inhibitors; the external Ca2+ -independent glutamate overflow caused by 50 mmol/L KCl was prevented by bafilomycin, by chelating intraterminal Ca2+, by blocking the mitochondrial Na+/Ca2+ exchanger and, for a small portion, by blocking anion channels. In contrast to purified synaptosomes, the 50 mmol/L K+ -evoked release of endogenous glutamate or [3H]D-ASP was inhibited by dl -TBOA in crude synaptosomes; moreover, it was external Ca2+ -insensitive and blocked by dl -TBOA in purified gliosomes, suggesting that carrier-mediated release of endogenous glutamate provoked by excessive [K+] in CNS tissues largely originates from glia. [source] Cytotoxic effects of dental resin liquids on primary gingival fibroblasts and periodontal ligament cells in vitroJOURNAL OF ORAL REHABILITATION, Issue 12 2004Y.-L. Lai summary, Cytotoxic effects of resin liquids of three in situ relining dental polymers, AlikeTM, Kooliner, and Tokuso Rebase, and their major components, methyl methacrylate (MMA), isobutyl methacrylate (IBMA), and 1,6-hexanediol dimethacrylate (1,6-HDMA) were investigated. The concentrations of major monomers in these resin liquids were determined by high-performance liquid chromatography. Cellular viability of human gingival fibroblasts (GF) and periodontal ligament (PDL) cells were evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide assay. Moreover, patterns of cell death were analysed using annexin V/propidium iodide staining with flow cytometry. The results indicated that AlikeTM liquid contained 91·3% MMA, Kooliner liquid contained 94·5% IBMA, and Tokuso Rebase liquid contained 65·8% 1,6-HDMA. All materials examined had cytotoxic effects on GF and PDL cells in dose-dependent manners. Tokuso Rebase liquid appeared to be the most cytotoxic among the various resin liquids examined. The effects of Kooliner and Tokuso Rebase liquids may have resulted from IBMA and 1,6-HDMA, respectively. Furthermore, the majority of treated cells died from necrosis; whereas a small portion of cells died from apoptosis. In conclusion, the results demonstrated that these liquid forms of dental polymers and their major monomers cause cytotoxic reactions. The direct relining procedure that cures these materials in situ should be used cautiously. [source] Resin comparison and fast automated stepwise conventional synthesis of human SDF-1,JOURNAL OF PEPTIDE SCIENCE, Issue 12 2008Hirendra Patel Abstract Human SDF-1, contains 68 amino acids and is a member of the chemokine family of peptides. This long peptide was synthesized stepwise using classical conditions in 101 h. The reaction times were then reduced to deprotection times of 2 × 2 min and coupling times of 2 × 2.5 min, resulting in a total synthesis time of 22 h. The effect of different resins, resin substitutions and deprotection reagents on the crude peptide purities was compared. A small portion of crude peptide was purified using an RP-HPLC column and the mass of the final product was confirmed with MALDI-TOF mass spectrometry. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd. [source] GLOBAL SYSTEMATIC AND PHYLOGENETIC ANALYSIS OF SARGASSUM IN THE GULF OF MEXICO, CARIBBEAN AND PACIFIC BASINJOURNAL OF PHYCOLOGY, Issue 2000N. Phillips Sargassum is one of the most species-rich genera in the brown algae with over 400 described species worldwide. The bulk of these species occurs in Pacific-Indian ocean waters with only a small portion found on the Atlantic side of the Isthmus of Panama. Sargassum also has one of the most subdivided and complex taxonomic systems used within the algae. Systematic distinctions within the genus are further complicated by high rates of phenotypic variability in several key morphological characters. Molecular analyses in such systems should allow testing of systematic concepts while providing insights into speciation and evolutionary patterns. Global molecular phylogenetic analyses using both conserved and variable regions of the Rubisco operon (rbcL and rbcL-IGS-rbcS) were performed with species from the Gulf of Mexico, Caribbean, and Pacific basin. Results confirm earlier analyses based on rbcL-IGS- rbcS from Pacific species at the subgeneric and sectional level while providing additional insights into the systematics and phylogenetics on a global scale. For example, species east of the Isthmus of Panama form a distinct well-resolved clade within the tropical subgenus. This result in sharp contrast to traditional systematic treatments but provides a window into the evolutionary history of this genus in the Pacific and Atlantic Ocean basins and a possible means to time speciation events. [source] Finding nuggets in documents: A machine learning approachJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 6 2006Yi-fang Brook Wu Document keyphrases provide a concise summary of a document's content, offering semantic metadata summarizing a document. They can be used in many applications related to knowledge management and text mining, such as automatic text summarization, development of search engines, document clustering, document classification, thesaurus construction, and browsing interfaces. Because only a small portion of documents have keyphrases assigned by authors, and it is time-consuming and costly to manually assign keyphrases to documents, it is necessary to develop an algorithm to automatically generate keyphrases for documents. This paper describes a Keyphrase Identification Program (KIP), which extracts document keyphrases by using prior positive samples of human identified phrases to assign weights to the candidate keyphrases. The logic of our algorithm is: The more keywords a candidate keyphrase contains and the more significant these keywords are, the more likely this candidate phrase is a keyphrase. KIP's learning function can enrich the glossary database by automatically adding new identified keyphrases to the database. KIP's personalization feature will let the user build a glossary database specifically suitable for the area of his/her interest. The evaluation results show that KIP's performance is better than the systems we compared to and that the learning function is effective. [source] INFLUENCES OF WATERSHED URBANIZATION AND INSTREAM HABITAT ON MACROINVERTEBRATES IN COLD WATER STREAMS,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2003Lizhu Wang ABSTRACT: We analyzed data from riffle and snag habitats for 39 small cold water streams with different levels of watershed urbanization in Wisconsin and Minnesota to evaluate the influences of urban land use and instream habitat on macroinvertebrate communities. Multivariate analysis indicated that stream temperature and amount of urban land use in the watersheds were the most influential factors determining macroinvertebrate assemblages. The amount of watershed urbanization was nonlinearly and negatively correlated with percentages of Ephemeroptera-Plecoptera-Trichoptera (EPT) abundance, EPT taxa, filterers, and scrapers and positively correlated with Hilsenhoff biotic index. High quality macroinvertebrate index values were possible if effective imperviousness was less than 7 percent of the watershed area. Beyond this level of imperviousness, index values tended to be consistently poor. Land uses in the riparian area were equal or more influential relative to land use elsewhere in the watershed, although riparian area consisted of only a small portion of the entire watershed area. Our study implies that it is extremely important to restrict watershed impervious land use and protect stream riparian areas for reducing human degradation on stream quality in low level urbanizing watersheds. Stream temperature may be one of the major factors through which human activities degrade cold-water streams, and management efforts that can maintain a natural thermal regime will help preserve stream quality. [source] Silk feeding as an alternative foraging tactic in a kleptoparasitic spider under seasonally changing environmentsJOURNAL OF ZOOLOGY, Issue 3 2004Tadashi Miyashita Abstract Spiders of the genus Argyrodes are kleptoparasites that steal prey from other web spiders. Recent studies have shown that in addition to stealing prey, they occasionally eat the silk of the host spider webs. How Argyrodes alters the two foraging tactics in the field is still unknown. The foraging behaviour of Argyrodes flavescens was observed in the south-western part of Japan where prey availability changes greatly with season. Silk-eating behaviour was commonly observed when insect prey availability on host webs was low, but when prey was abundant, only prey-stealing behaviour was observed. Spiders spent more time feeding on silk than on prey when prey was scarce. Moreover, in the season when most individuals fed on silk, only a small portion of individuals consumed prey. These results suggest that silk eating is an important alternative foraging tactic under seasonally changing environments. [source] Potential selection in native grass populations by exotic invasionMOLECULAR ECOLOGY, Issue 8 2006BRIAN A. MEALOR Abstract Ecological impacts of invasive plant species are well documented, but the genetic response of native species to invasive dominance has been often overlooked. Invasive plants can drastically alter site conditions where they reach dominance, potentially exerting novel selective pressures on persistent native plant populations. Do native plant populations in old exotic invasions show evidence of selection when compared to conspecific populations in adjacent, noninvaded areas? We employ amplified fragment length polymorphism (AFLP) analysis to screen a large number of loci from two native grass species (Hesperostipa comata (Trin. & Rupr.) Barkworth and Sporobolus airoides Torr.) that occur in old infestations of the invasive forb Acroptilon repens. We then compare observed locus by locus FST values with distributions of FST estimated from simulation models under expectation of neutrality. We also compare the proportion of loci possibly linked to selection and those not linked to selection which exhibit parallel trends in divergence between two community types (invaded, noninvaded). Few loci (H. comata, 2.6%; S. airoides, 8.7%) in the two native grasses may be linked to genes under the influence of selection. Also, loci linked to selection showed a greater portion of parallel trends in divergence than neutral loci. Genetic similarities between community types were less than genetic similarity within community types suggesting differentiation in response to community alteration. These results indicate that a small portion of scored AFLP loci may be linked to genes undergoing selection tied to community dominance by an invasive species. We propose that native plants in communities dominated by exotic invasives may be undergoing natural selection. [source] Motor neuron disease group accompanied by inclusions of unidentified protein signaled by ubiquitinNEUROPATHOLOGY, Issue 2 2004Kenji Ikeda Peculiar tau-negative, ubiquitin-positive inclusions appear in dementia with ALS (ALS-D), the majority of lobar atrophy (Pick's disease) without Pick body and a small portion of ALS. Another common neuropathological lesion in these diseases is the motor neuron involvement with the degenerative processes. The lower motor neuron is predominantly involved in ALS and ALS-D while the upper motor neuron is predominantly involved, but in varying degrees in a considerable number of patients with lobar atrophy that lack Pick bodies. There are, however, some points that have yet to be elucidated. The boundary between these diseases is not always clear and a significant number of cases are considered to be the transitional form. Lobar atrophy without Pick body seems to be a heterogeneous disease group. The nature of ubiquitin inclusions also needs to be clarified. Nevertheless, we postulate that these diseases are grouped with the concept of motor neuron disease-inclusion dementia. [source] Sarcomatoid hepatocellular carcinoma with hepatoblastoma-like features in an adultPATHOLOGY INTERNATIONAL, Issue 6 2004Min-Sun Cho A mixed epithelial and mesenchymal tumor of the liver arising in an adult is rare and is mostly classified as sarcomatoid hepatocellular carcinoma (HCC). In this study, a case of sarcomatoid HCC in an adult with hepatoblastoma (HB)-like features, which produced difficulty in the differential diagnosis between sarcomatoid HCC and mixed HB, is presented. The epithelial component of the tumor composed of poorly differentiated HCC, Edmondson's grade III, and more primitive components, which were embryonal and small cell undifferentiated components of HB-like areas. The small undifferentiated cells surrounded HCC and the embryonal component of HB-like area, and revealed transition partly to areas of rhabdomyosarcoma. A small portion of chondrosarcoma was also noted. Immunohistochemical analysis showed that HCC and the embryonal component of HB-like areas expressed alpha-fetoprotein (AFP) and cytokeratin 8. The small undifferentiated cells were negative for AFP but stained with cytokeratin 8 as well as CD56, which is a marker of primitive cells in many sarcoma and HB. It is not certain whether small undifferentiated cells belong to hepatic progenitor cells or primitive mesenchymal cells. Polymerase chain reaction,single-strand conformation polymorphism analysis for beta-catenin mutation using microdissection revealed no mutation of any components. A review was undertaken of the cases previously reported as adult hepatoblastoma without detailed immunohistochemical study and consider many of them may be sarcomatoid HCC. These primitive and sarcomatoid components would be arising from the dedifferentiation process of HCC. [source] Association of maturation, sex, and body fat in cardiorespiratory fitnessAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 6 2002Jorge Mota The aims of this cross-sectional study were 1) to estimate changes in body composition and cardiorespiratory fitness across stages of pubertal maturation, and 2) to describe the relationship between maturity status and body fatness, regional fat distribution, and cardiorespiratory fitness. The sample consisted of 494 children (254 males, 240 females), 8,16 years of age. Height and weight were measured with standard anthropometric methods. Percentage of fat (%F) was estimated from two skinfold thicknesses and regional fat distribution was estimated by the ratio of the subscapular to the triceps skinfold (S/T ratio). Biological maturity was based on self-assessment of breast stages in females and pubic hair stages in males. A maximal multistage 20-m shuttle run was used to predict maximal aerobic capacity from maximal aerobic speed. Both VO2max and 20SRT-time were used as indicators of cardiorespiratory fitness. ANCOVA with age as the covariate was used. There were significant differences among girls across pubertal stages. Among boys, only weight and height differed significantly by stage of maturity. When adjusted for maturity status, cardiorespiratory fitness expressed either as VO2/kg body mass or 20SRT-time was inversely associated with %F in both sexes. This suggests that sexual maturity status alone accounts for a small portion of the variance in aerobic fitness. Height, %F and the S/T ratio were also significantly associated with VO2/kg body mass and 20SRT-time. Am. J. Hum. Biol. 14:707,712, 2002. © 2002 Wiley-Liss, Inc. [source] Geographic variation in opioid prescribing for acute, work-related, low back pain and associated factors: A multilevel analysisAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2009Barbara S. Webster BSPT, PA-C Abstract Background Given reports about variation in opioid prescribing, concerns about increasing opioid use and its associated negative consequences make understanding the sources of variability important. The aims of the study were to assess the extent of and factors associated with geographic variation in early opioid prescribing for acute, work-related, low back pain (LBP). Methods Cases were selected from workers compensation administrative data filed between January 1, 2002 and December 31, 2003 and included claims from states with more than 40 cases. Early opioid prescribing (one or more prescriptions within first 15 days) was the outcome. Weighted coefficient of variation (wCOV) estimated geographic variation, and multilevel models measured variability controlling for individual and contextual factors. Results Of the 8,262 claimants, 21.3% received at least one early opioid prescription. Significant between-state variation was found (wCOV,=,53%), from 5.7% (Massachusetts) to 52.9% (South Carolina). Seventy-nine percent of the between-state variation was explained by three contextual factors: state household income inequality (prevalence ratio [PR] 1.06, 95% confidence interval [CI],=,1.01, 1.12), number of physicians per capita (PR 0.99, 95% CI,=,0.98, 0.99), and workers compensation cost containment effort score (PR 1.12, 95% CI,=,1.02, 1.24). Individual-level factors, including severity, explained only a small portion of the geographic variability. Conclusion Geographic variation of early opioid prescribing for acute LBP is important and almost fully explained by state-level contextual factors. The study suggests that clinician and patient interaction and the subsequent decision to use opioids are substantially framed by social conditions and control systems. Am. J. Ind. Med. 52:162,171, 2009. © 2008 Wiley-Liss, Inc. [source] Stepwise disassembly and apparent nonstepwise reassembly for the oligomeric RbsD proteinPROTEIN SCIENCE, Issue 6 2006Yongjun Feng Abstract Many cellular proteins exist as homo-oligomers. The mechanism of the assembly process of such proteins is still poorly understood. We have previously observed that Hsp16.3, a protein exhibiting chaperone-like activity, undergoes stepwise disassembly and nonstepwise reassembly. Here, the disassembly and reassembly of a nonchaperone protein RbsD, from Escherichia coli, was studied in vitro. The protein was found to mainly exist as decamers with a small portion of apparently larger oligomeric forms, both of which are able to refold/reassemble effectively in a spontaneous way after being completely unfolded. Disassembly RbsD intermediates including pentamers, tetramers, trimers, dimers, and monomers were detected by using urea-containing pore gradient polyacrylamide gel electrophoresis, while only pentamers were detected for its reassembly. The observation of stepwise disassembly and apparent nonstepwise reassembly for both a chaperone protein (Hsp16.3) and a nonchaperone protein (RbsD) strongly suggests that such a feature is most likely general for homo-oligomeric proteins. [source] Haplotype Trees and Modern Human OriginsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue S41 2005Alan R. Templeton Abstract A haplotype is a multisite haploid genotype at two or more polymorphic sites on the same chromosome in a defined DNA region. An evolutionary tree of the haplotypes can be estimated if the DNA region had little to no recombination. Haplotype trees can be used to reconstruct past human gene-flow patterns and historical events, but any single tree captures only a small portion of evolutionary history, and is subject to error. A fuller view of human evolution requires multiple DNA regions, and errors can be minimized by cross-validating inferences across loci. An analysis of 25 DNA regions reveals an out-of-Africa expansion event at 1.9 million years ago. Gene flow with isolation by distance was established between African and Eurasian populations by about 1.5 million years ago, with no detectable interruptions since. A second out-of-Africa expansion occurred about 700,000 years ago, and involved interbreeding with at least some Eurasian populations. A third out-of-Africa event occurred around 100,000 years ago, and was also characterized by interbreeding, with the hypothesis of a total Eurasian replacement strongly rejected (P < 10,17). This does not preclude the possibility that some Eurasian populations could have been replaced, and the status of Neanderthals is indecisive. Demographic inferences from haplotype trees have been inconsistent, so few definitive conclusions can be made at this time. Haplotype trees from human parasites offer additional insights into human evolution and raise the possibility of an Asian isolate of humanity, but once again not in a definitive fashion. Haplotype trees can also indicate which genes were subject to positive selection in the lineage leading to modern humans. Genetics provides many insights into human evolution, but those insights need to be integrated with fossil and archaeological data to yield a fuller picture of the origin of modern humans. Yrbk Phys Anthropol 48:33,59, 2005. © 2005 Wiley-Liss, Inc. [source] Welfare Reform and the Labour Supply of Lone Parents in Australia: A Natural Experiment ApproachTHE ECONOMIC RECORD, Issue 249 2004Denise J. Doiron Large shifts in the labour supply of lone parents in Australia were observed between 1986 and 1990. Changes in the observed characteristics of lone parents explain only a small portion of these shifts. Propensity score matching and difference-in-differences are used to estimate the effects of the substantial policy shifts implemented in 1987. Control groups are constructed from the sample of married mothers. Results suggest that the policy reforms caused a substantial increase in the employment of lone parents while causing a reduction in the hours of work among the workers. [source] Adaptive thinning of atmospheric observations in data assimilation with vector quantization and filtering methodsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 613 2005T. Ochotta Abstract In data assimilation for numerical weather prediction, measurements of various observation systems are combined with background data to define initial states for the forecasts. Current and future observation systems, in particular satellite instruments, produce large numbers of measurements with high spatial and temporal density. Such datasets significantly increase the computational costs of the assimilation and, moreover, can violate the assumption of spatially independent observation errors. To ameliorate these problems, we propose two greedy thinning algorithms, which reduce the number of assimilated observations while retaining the essential information content of the data. In the first method, the number of points in the output set is increased iteratively. We use a clustering method with a distance metric that combines spatial distance with difference in observation values. In a second scheme, we iteratively estimate the redundancy of the current observation set and remove the most redundant data points. We evaluate the proposed methods with respect to a geometric error measure and compare them with a uniform sampling scheme. We obtain good representations of the original data with thinnings retaining only a small portion of observations. We also evaluate our thinnings of ATOVS satellite data using the assimilation system of the Deutscher Wetterdienst. Impact of the thinning on the analysed fields and on the subsequent forecasts is discussed. Copyright © 2005 Royal Meteorological Society [source] Optimizing the Circuit of a Pulsatile Extracorporeal Life Support System in Terms of Energy Equivalent Pressure and Surplus Hemodynamic EnergyARTIFICIAL ORGANS, Issue 11 2009Choon Hak Lim Abstract:, The nonpulsatile blood flow obtained using standard cardiopulmonary bypass (CPB) circuits is still generally considered an acceptable, nonphysiologic compromise with few disadvantages. However, numerous reports have concluded that pulsatile perfusion during CPB achieves better multiorgan response postoperatively. Furthermore, pulsatile flow during CPB has been consistently recommended in pediatric and high-risk patients. However, most (80%) of the total hemodynamic energy generated by a pulsatile pump is absorbed by the components of the extracorporeal circuit and only a small portion of the pulsatile energy is delivered to the patient. Therefore, we considered that optimizations of CPB unit and extracorporeal life support (ECLS) system circuit components were needed to deliver sufficient pulsatile flow. In addition, energy equivalent pressure, surplus hemodynamic energy, and total hemodynamic energy, calculated using pressure and flow waveforms, were used to evaluate the pulsatilities of pulsatile CPB and ECLS systems. [source] What Do We Know About Long,run Equilibrium Real Exchange Rates?AUSTRALIAN ECONOMIC PAPERS, Issue 4 2002PPPs vs Macroeconomic Approaches Despite the fact that the presence of non tradable goods is one of the most frequently advanced reasons for the failure of PPP, the empirical analysis conducted in this paper shows that it explains only a very small portion of the long run behaviour of real exchange rates (RERs) in developed countries: in most cases, there appears to be a very strong long run relationship between RERs calculated on price indexes for tradables and non tradables. As a consequence, deviations from PPP usually appear to be as large for both kinds of goods. To a certain extent, this stylised fact is also verified in the case of the yen/dollar RER, yet formerly known as a typical illustration of the so,called Balassa,Samuelson effect. In this context, so,called macroeconomic approaches of ERERs may be viewed as an alternative to all versions of PPP. We develop a model which combines the contributions of the most fruitful dynamic approaches, namely the NATREX and the BEER. An estimate of this model shows that the main long run determinants of the dollar/euro RER are the rate of consumption and the level of technical progress of the euro area relative to the US. [source] | |||||||||||||||||||||||||