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Current Patterns (current + pattern)
Selected AbstractsHistory in the interpretation of the pattern of p49a,f TaqI RFLP Y-chromosome variation in Egypt: A consideration of multiple lines of evidenceAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2005S.O.Y. Keita The possible factors involved in the generation of p49a,f TaqI Y-chromosome spatial diversity in Egypt were explored. The object was to consider explanations beyond those that emphasize gene flow mediated via military campaigns within the Nile corridor during the dynastic period. Current patterns of the most common variants (V, XI, and IV) have been suggested to be primarily related to Middle Kingdom and New Kingdom political actions in Nubia, including occasional settler colonization, and the conquest of Egypt by Kush (in upper Nubia, northern Sudan), thus initiating the Twenty-Fifth Dynasty. However, a synthesis of evidence from archaeology, historical linguistics, texts, distribution of haplotypes outside Egypt, and some demographic considerations lends greater support to the establishment, before the Middle Kingdom, of the observed distributions of the most prevalent haplotypes V, XI, and IV. It is suggested that the pattern of diversity for these variants in the Egyptian Nile Valley was largely the product of population events that occurred in the late Pleistocene to mid-Holocene through the First Dynasty, and was sustained by continuous smaller-scale bidirectional migrations/interactions. The higher frequency of V in Ethiopia than in Nubia or upper (southern) Egypt has to be taken into account in any discussion of variation in the Nile Valley. Am. J. Hum. Biol. 17: 559,567, 2005. © 2005 Wiley-Liss, Inc. [source] Invasive species of Heracleum in Europe: an insight into genetic relationships and invasion historyDIVERSITY AND DISTRIBUTIONS, Issue 1 2007árka Jahodová ABSTRACT Several species of the genus Heracleum (Umbelliferae) were introduced into Europe from south-west Asia in the 19th century and are now widespread in many countries. At least three invasive taxa with unresolved relationships to one another are thought to occur in Europe: Heracleum mantegazzianum Sommier & Levier, H. sosnowskyi Manden, and H. persicum Desf. ex Fischer. They are tall plants forming extensive stands with a high cover. To elucidate genetic relationships between the species, and gain insight into their invasion history, samples were collected from native ranges in Asia and invaded ranges of the three species in Europe and analysed using amplified fragment length polymorphism. Five other Heracleum species were also studied and in total, 189 samples from 72 populations were analysed. The results confirmed that there are three distinct tall Heracleum species invading in Europe. Within each of the three species, plants collected in the invaded range are genetically close to those from their native ranges. A close genetic relationship between the three invasive Heracleum species in Europe was also found. A high overall genetic variability detected in the invaded range suggests that the majority of invading populations were not affected by a genetic bottleneck and that rapid evolution, drift, or hybridization played a role in genetic structuring of invading populations. For H. mantegazzianum, genetic distance of populations in the native range significantly decreased with geographical distance, but not in the invaded range. It is likely that the current pattern of genetic diversity in Europe resulted from multiple introductions of all three species. [source] Other people, other drugs: the policy response to petrol sniffing among Indigenous AustraliansDRUG AND ALCOHOL REVIEW, Issue 3 2004Dr PETER H. D'ABBS Abstract This paper examines the policy response of Australian governments to petrol sniffing in Indigenous communities from the 1980s until the present. During this period, despite the formation of numerous inquiries, working parties and intergovernmental committees, there has been little accumulation of knowledge about the nature and causes of sniffing, or about the effectiveness of interventions. Policies are fragmentary; programmes are rarely evaluated, and most rely on short-term funding. The paper sets out to explain why this should be so. It draws upon a conceptual framework known as ,analytics of government' to examine the ways in which petrol sniffing comes to the attention of government agencies and is perceived as an issue; the mechanisms deployed by governments to address petrol sniffing; ways in which knowledge about sniffing is generated; and the underlying assumptions about people that inform policy-making. Drawing upon case studies of policy responses, the paper argues that a number of structural factors combine to marginalize petrol sniffing as an issue, and to encourage reliance on short-term, one-off interventions in place of a sustained policy commitment. Four recommendations are advanced to help overcome these factors: (1) agreements should be reached within and between levels of government on steps to be taken to reduce risk factors before the eruption of petrol-sniffing crises; (2) the evidence base relevant to petrol sniffing (and other inhalants) should be improved by funding and directing one or more existing national drug research centres to collate data on inhalant-caused mortality and morbidity, and to conduct or commission research into prevalence patterns, effectiveness of interventions and other gaps in knowledge; (3) the current pattern of short-term, pilot and project funding should be replaced with longer-term, evidence-based interventions that address the multiple risk and protective factors present in communities; and (4) insistence by governments that communities must take ,ownership' of the problem should be replaced by a commitment to genuine partnerships involving governments, non-government and community sectors. [source] Astrocytes in the hippocampus of patients with temporal lobe epilepsy display changes in potassium conductancesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2000Stefan Hinterkeuser Abstract Functional properties of astrocytes were investigated with the patch-clamp technique in acute hippocampal brain slices obtained from surgical specimens of patients suffering from pharmaco-resistant temporal lobe epilepsy (TLE). In patients with significant neuronal cell loss, i.e. Ammon's horn sclerosis, the glial current patterns resembled properties characteristic of immature astrocytes in the murine or rat hippocampus. Depolarizing voltage steps activated delayed rectifier and transient K+ currents as well as tetrodotoxin-sensitive Na+ currents in all astrocytes analysed in the sclerotic human tissue. Hyperpolarizing voltages elicited inward rectifier currents that inactivated at membrane potentials negative to -130 mV. Comparative recordings were performed in astrocytes from patients with lesion-associated TLE that lacked significant histopathological hippocampal alterations. These cells displayed stronger inward rectification. To obtain a quantitative measure, current densities were calculated and the ratio of inward to outward K+ conductances was determined. Both values were significantly smaller in astrocytes from the sclerotic group compared with lesion-associated TLE. During normal development of rodent brain, astroglial inward rectification gradually increases. It thus appears reasonable to suggest that astrocytes in human sclerotic tissue return to an immature current pattern. Reduced astroglial inward rectification in conjunction with seizure-induced shrinkage of the extracellular space may lead to impaired spatial K+ buffering. This will result in stronger and prolonged depolarization of glial cells and neurons in response to activity-dependent K+ release, and may thus contribute to seizure generation in this particular condition of human TLE. [source] Population fragmentation leads to spatial and temporal genetic structure in the endangered Spanish imperial eagleMOLECULAR ECOLOGY, Issue 3 2007B. MARTÍNEZ-CRUZ Abstract The fragmentation of a population may have important consequences for population genetic diversity and structure due to the effects of genetic drift and reduced gene flow. We studied the genetic consequences of the fragmentation of the Spanish imperial eagle (Aquila adalberti) population into small patches through a temporal analysis. Thirty-four museum individuals representing the population predating the fragmentation were analysed for a 345-bp segment of the mitochondrial control region and a set of 10 nuclear microsatellite loci. Data from a previous study on the current population (N = 79) were re-analysed for this subset of 10 microsatellite markers and results compared to those obtained from the historical sample. Three shared mitochondrial haplotypes were found in both populations, although fluctuations in haplotype frequencies and the occurrence of a fourth haplotype in the historical population resulted in lower current levels of haplotype and nucleotide diversity. However, microsatellite markers revealed undiminished levels of nuclear diversity. No evidence for genetic structure was observed for the historical Spanish imperial eagle population, suggesting that the current pattern of structure is the direct consequence of population fragmentation. Temporal fluctuations in mitochondrial and microsatellite allelic frequencies were found between the historical and the current population as well as for each pairwise comparison between historical and current Centro and historical and current Parque Nacional de Dońana nuclei. Our results indicate an ancestral panmictic situation for the species that management policies should aim to restore. A historical analysis like the one taken here provides the baseline upon which the relative role of recent drift in shaping current genetic patterns in endangered species can be evaluated and this knowledge is used to guide conservation actions. [source] Phylogenetic beta diversity: linking ecological and evolutionary processes across space in timeECOLOGY LETTERS, Issue 12 2008Catherine H. Graham Abstract A key challenge in ecological research is to integrate data from different scales to evaluate the ecological and evolutionary mechanisms that influence current patterns of biological diversity. We build on recent attempts to incorporate phylogenetic information into traditional diversity analyses and on existing research on beta diversity and phylogenetic community ecology. Phylogenetic beta diversity (phylobetadiversity) measures the phylogenetic distance among communities and as such allows us to connect local processes, such as biotic interactions and environmental filtering, with more regional processes including trait evolution and speciation. When combined with traditional measures of beta diversity, environmental gradient analyses or ecological niche modelling, phylobetadiversity can provide significant and novel insights into the mechanisms underlying current patterns of biological diversity. [source] Biogeography of bacteria associated with the marine sponge Cymbastela concentricaENVIRONMENTAL MICROBIOLOGY, Issue 3 2005Michael W. Taylor Summary Recent debate regarding microbial biogeography has focused largely on free-living microbes, yet those microbes associated with host organisms are also of interest from a biogeographical perspective. Marine eukaryotes and associated bacteria should provide ideal systems in which to consider microbial biogeography, as (i) bacteria in seawater should be able to disperse among individuals of the same host species, yet (ii) potential for adaptation to particular hosts (and thus speciation) also exists. We used 16S rDNA-DGGE (denaturing gradient gel electrophoresis) to examine geographic variability in bacterial community composition in the marine sponge Cymbastela concentrica. Denaturing gradient gel electrophoresis banding patterns (and phylogenetic analysis of excised DGGE bands) indicated different communities in Cymbastela concentrica from tropical versus temperate Australia. In contrast, communities were very similar over a 500-km portion of the sponge's temperate range. Variation in bacterial community composition was also considered with respect to ocean current patterns. We speculate that the divergent communities in different parts of the sponge's range provide evidence of endemism attributed to host association, although variation in environmental factors such as light and temperature could also explain the observed results. Interestingly, bacterial communities in seawater varied much less between tropical and temperate locations than did those in C. concentrica, supporting the concept of widespread dispersal among these free-living microbes. [source] Astrocytes in the hippocampus of patients with temporal lobe epilepsy display changes in potassium conductancesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2000Stefan Hinterkeuser Abstract Functional properties of astrocytes were investigated with the patch-clamp technique in acute hippocampal brain slices obtained from surgical specimens of patients suffering from pharmaco-resistant temporal lobe epilepsy (TLE). In patients with significant neuronal cell loss, i.e. Ammon's horn sclerosis, the glial current patterns resembled properties characteristic of immature astrocytes in the murine or rat hippocampus. Depolarizing voltage steps activated delayed rectifier and transient K+ currents as well as tetrodotoxin-sensitive Na+ currents in all astrocytes analysed in the sclerotic human tissue. Hyperpolarizing voltages elicited inward rectifier currents that inactivated at membrane potentials negative to -130 mV. Comparative recordings were performed in astrocytes from patients with lesion-associated TLE that lacked significant histopathological hippocampal alterations. These cells displayed stronger inward rectification. To obtain a quantitative measure, current densities were calculated and the ratio of inward to outward K+ conductances was determined. Both values were significantly smaller in astrocytes from the sclerotic group compared with lesion-associated TLE. During normal development of rodent brain, astroglial inward rectification gradually increases. It thus appears reasonable to suggest that astrocytes in human sclerotic tissue return to an immature current pattern. Reduced astroglial inward rectification in conjunction with seizure-induced shrinkage of the extracellular space may lead to impaired spatial K+ buffering. This will result in stronger and prolonged depolarization of glial cells and neurons in response to activity-dependent K+ release, and may thus contribute to seizure generation in this particular condition of human TLE. [source] Moving up, moving down: Political careers across territorial levelsEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 2 2003Klaus Stolz In the sparse literature on political careers in federal systems, regional positions are often seen as mere stepping stones on the way to federal office. But are they really? The recent professionalization of state politics in federal systems and the regionalization of former unitary states point to the strengthening of the regional level as a career arena in its own right. Could this lead to the emergence of a regional political class with a set of career interests distinct from those of national politicians? This article takes a first, comparative look at current patterns of career movements between regional and national parliaments in a wide range of federal and newly regionalized systems. The study shows that, contrary to general belief, the number of deputies actually moving from the regional to federal level is generally relatively low. While some cases show fairly integrated career structures, others exhibit a pattern of career development in which state or regional office functions as the main focus of political careers. The territorial structure of the political class is dependent upon a whole range of social, cultural and institutional factors. At the same time, it is also an important factor in the mechanics and institutional development of each federal system in question. [source] Comparison of phenology trends by land cover class: a case study in the Great Basin, USAGLOBAL CHANGE BIOLOGY, Issue 2 2008BETHANY A. BRADLEY Abstract Direct impacts of human land use and indirect impacts of anthropogenic climate change may alter land cover and associated ecosystem function, affecting ecological goods and services. Considerable work has been done to identify long-term global trends in vegetation greenness, which is associated with primary productivity, using remote sensing. Trend analysis of satellite observations is subject to error, and ecosystem change can be confused with interannual variability. However, the relative trends of land cover classes may hold clues about differential ecosystem response to environmental forcing. Our aim was to identify phenological variability and 10-year trends for the major land cover classes in the Great Basin. This case study involved two steps: a regional, phenology-based land cover classification and an identification of phenological variability and 10-year trends stratified by land cover class. The analysis used a 10-year time series of Advanced Very High Resolution Radiometer satellite data to assess regional scale land cover variability and identify change. The phenology-based regional classification was more detailed and accurate than national or global products. Phenological variability over the 10-year period was high, with substantial shifts in timing of start of season of up to 9 weeks. The mean long-term trends of montane land cover classes were significantly different from valley land cover classes due to a poor response of montane shrubland and pinyon-juniper woodland to the early 1990s drought. The differential response during the 1990s suggests that valley ecosystems may be more resilient and montane ecosystems more susceptible to prolonged drought. This type of regional-scale land cover analysis is necessary to characterize current patterns of land cover phenology, distinguish between anthropogenically driven land cover change and interannual variability, and identify ecosystems potentially susceptible to regional and global change. [source] On models of fractal networksINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 5 2009Walter Arrighetti Abstract A couple of iterative models for the theoretical study of fractal networks whose topologies are generated via iterated function systems is presented: a lumped-parameter impedor-oriented one and a two-port-network-oriented one. With the former, the voltage and current patterns give a detailed understanding of the electromagnetic fields' self-similar distribution throughout the network; on the other hand, model complexity exponentially increases with the prefractal iteration order. The latter ,black-box' model only controls port-oriented global parameters that are the ones commonly used in the integration of different electronic systems, and its complexity is independent of prefractal order. Sierpinski gasket and carpet topologies are reported as examples. Copyright © 2008 John Wiley & Sons, Ltd. [source] Differing Patterns of Antiresorptive Pharmacotherapy in Nursing Facility Residents and Community DwellersJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 8 2005Carolyn M. Jachna MD Objectives: Little is known about differences between current patterns of antiresorptive therapy (ART) use in nursing facility (NF) residents and by community-dwelling older adults (CDs). ART use was compared in older NF residents and CDs. Design: Cross-sectional analysis. Setting: Kansas Medicaid files from May 2000 through April 2001. Participants: Women aged 65 and older having at least 9 months of data as a CD or NF resident. Measurements: Pharmacy claims were used to identify any ART prescription, including hormone replacement therapy (HRT), a bisphosphonate, raloxifene, or calcitonin. Demographic and clinical variables were identified from the claims files. Factors associated with ART use in bivariate analyses were entered into logistic regression models. Similar analyses were performed for bisphosphonate use among non-estrogen replacement therapy (non-ERT) ARTs (excluding HRT). Results: The final study sample (N=2,289) included 898 NF (mean age 85.2) residents and 1,391 CDs (mean age 76.6). CDs were more likely to receive any ART (24.5%) than NF residents (19.6%). After adjustment for potential confounders, NF residents aged 65 to 84 were less likely (odds ratio (OR)=0.61, 95% confidence interval (CI)=0.44,0.85) to receive ART than CDs of the same age. Conversely, of those aged 85 and older, NF residents were more likely than CDs to receive ART (OR=1.96, 95% CI=1.18,3.25). Calcitonin was the most common non-ERT ART prescribed for NF residents, whereas bisphosphonates were more often prescribed for CDs. Conclusion: Underusage of ART is common in NF and CD cohorts. NF residents are less likely to receive bisphosphonates and more likely to receive calcitonin, for which efficacy is less clear. Further research is needed to identify factors influencing ART prescribing and selection of specific ARTs in different settings. [source] Biogeography of Iberian freshwater fishes revisited: the roles of historical versus contemporary constraintsJOURNAL OF BIOGEOGRAPHY, Issue 11 2009Ana F. Filipe Abstract Aim, The question of how much of the shared geographical distribution of biota is due to environmental vs. historical constraints remains unanswered. The aim of this paper is to disentangle the contribution of historical vs. contemporary factors to the distribution of freshwater fish species. In addition, it illustrates how quantifying the contribution of each type of factor improves the classification of biogeographical provinces. Location, Iberian Peninsula, south-western Europe (c. 581,000 km2). Methods, We used the most comprehensive data on native fish distributions for the Iberian Peninsula, compiled from Portuguese and Spanish sources on a 20-km grid-cell resolution. Overall, 58 species were analysed after being categorized into three groups according to their ability to disperse through saltwater: (1) species strictly intolerant of saltwater (primary species); (2) species partially tolerant of saltwater, making limited incursions into saltwaters (secondary species); and (3) saltwater-tolerant species that migrate back and forth from sea to freshwaters or have invaded freshwaters recently (peripheral species). Distance-based multivariate analyses were used to test the role of historical (basin formation) vs. contemporary environmental (climate) conditions in explaining current patterns of native fish assemblage composition. Cluster analyses were performed to explore species co-occurrence patterns and redefine biogeographical provinces based on the distributions of fishes. Results, River basin boundaries were better at segregating species composition for all species groups than contemporary climate variables. This historical signal was especially evident for primary and secondary freshwater fishes. Eleven biogeographical provinces were delineated. Basins flowing to the Atlantic Ocean north of the Tagus Basin and those flowing to the Mediterranean Sea north of the Mijares Basin were the most dissimilar group. Primary and secondary freshwater species had higher province fidelity than peripheral species. Main conclusions, The results support the hypothesis that historical factors exert greater constraints on native freshwater fish assemblages in the Iberian Peninsula than do current environmental factors. After examining patterns of assemblage variation across space, as evidenced by the biogeographical provinces, we discuss the likely dispersal and speciation events that underlie these patterns. [source] Nuclear and chloroplast microsatellites reveal extreme population differentiation and limited gene flow in the Aegean endemic Brassica cretica (Brassicaceae)MOLECULAR ECOLOGY, Issue 23 2007KRISTINA EDH Abstract Nuclear and chloroplast microsatellite markers were used to study population structure and gene flow among seven Cretan populations of the Aegean endemic plant species Brassica cretica (Brassicaceae). Both nuclear and chloroplast markers revealed exceptionally high levels of population differentiation (overall FST = 0.628 and 1.000, respectively) and relatively little within-population diversity (overall HS = 0.211 and 0.000, respectively). Maximum-likelihood estimates of directional migration rates were low among all pairs of populations (average Nm = 0.286). There was no evidence that differences in flower colour between populations had any influence on historical levels of gene flow. In addition, a haplotype network showed that all five chloroplast haplotypes found in the sample were closely related. Together, these results suggest that current patterns of diversification in B. cretica are mainly a result of genetic drift during the last half million years. The main conclusions from the present study are consistent with the prevailing hypothesis that plant diversification in the Aegean region is driven by random rather than adaptive differentiation among isolated populations. [source] Consistency and crossbreeding in French speaking regional science: An epistemological investigation,PAPERS IN REGIONAL SCIENCE, Issue 4 2003Claude Lacour Regional science; epistemology; semantic fields; crossbreeding phenomenon Abstract. This article assesses the output of French-speaking regional scientists based on published works in Revue d'Economie Régionale et Urbaine (1978,1999). We explore quantitative and qualitative aspects of regional science and make comparisons with Anglo-Saxon research. We focus on the topics, style and concepts studied and used over time. Our analysis scrutinises changes in the current patterns of thought used in French speaking regional science. We also demonstrate narrow and broad semantic fields according to regional science issues and explore the phenomenon of crossbreeding between fields of studies. [source] Sexual Behavior in China: Trends and ComparisonsPOPULATION AND DEVELOPMENT REVIEW, Issue 4 2007William L. Parish Dramatic political, economic, and social changes in China over the past several decades have been accompanied by much discussion in popular media and among academics of a fundamental transformation in Chinese sexual behavior. Several studies have examined current Chinese sexual behavior but have been limited to particular provinces or cities and have been based on non-random samples. The potential threat of a generalized HIV epidemic in China highlights the dearth of population-based information on current patterns of sexual behavior that could help design better intervention strategies and prevent misguided ones. This article uses data from the first national probability survey of adult sexual behavior in China completed during 1999,2000, along with a historical and literature review, to address three key questions: 1) Has there been a revolution in sexual behavior in China? 2) Is China unique compared to other countries in these transformations? 3) What are the implications of these findings for China's risk of a generalized HIV epidemic? [source] Zonation Patterns of Belizean Offshore Mangrove Forests 41 Years After a Catastrophic Hurricane,BIOTROPICA, Issue 3 2006Cyril Piou ABSTRACT Mangroves are prone to bearing frequently the full brunt of hurricanes and tropical storms. The extent of destruction and early regeneration are widely studied. The purpose of this study was to add a long-term view of mangrove regeneration and assess the potential effects on mangrove horizontal zonation patterns of catastrophic destruction. Hattie, a category five hurricane, hit the Belizean coast in 1961. It passed directly over the Turneffe Atoll where our study area, Calabash Cay, is located. At four sites on this island, we analyzed mangrove forest structure along transects parallel to the shoreline within zones delineated by species dominance and tree height. We propose an index based on the Simpson index of diversity to express changes in the heterogeneity of the species dominance. Physical,chemical parameters and nutrient availability were also measured. The destruction levels were estimated by analysis of the distribution of diameter at breast heights of the bigger trees in the inland zones. Variations in species dominance among sites and zones could be explained by interactions of various factors. Further, different levels of destruction between the two sides of the island had a significant effect on current patterns of species and structural zonation at Calabash. We conclude that disturbance regime in general should be considered as a factor potentially influencing mangrove horizontal zonation patterns. [source] Women's perceptions of decision-making about hysterectomyBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 2 2004Z. Skea Objective To explore women's views of decision-making relating to hysterectomy. Design Structured questionnaire and in-depth interview surveys. Setting A teaching hospital and a district general hospital in northeast Scotland. Sample Women scheduled for hysterectomy for benign menstrual problems. Methods Pre-operative questionnaires were sent to a consecutive sample of women booked for hysterectomy. A purposive sample was interviewed post-operatively. Main outcome measures Women's experiences of, and satisfaction with, information provision, communication and decision-making processes; the relationship between views of decision-making processes and decisions made. Results One hundred and four women (66%) returned questionnaires. Most responded positively to structured questions about the process by which the decision to have a hysterectomy was reached. Almost all (97%) reported satisfaction with the decision made. Twenty women were interviewed post-operatively. A number, including some who had responded positively on the questionnaire, described aspects of the decision-making process that were suboptimal. Women's perceptions of the decision-making process, including the way their doctors communicated with them, did impinge on their views of the course of action selected. Some women had residual doubts about the appropriateness of hysterectomy. Conclusions In a significant minority of women, there are important shortcomings in current patterns of information provision and communication relating to decision-making. These are unlikely to be picked up by conventional structured patient feedback surveys. Further efforts are required to ensure that women are adequately informed and involved in decisions about gynaecological treatments. [source] | ||||||||||||||||||||||||||||