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Population Characteristics (population + characteristic)
Selected AbstractsPopulation characteristics of Oreochromis esculentus in the Victoria and Kyoga lake basins.AFRICAN JOURNAL OF ECOLOGY, Issue 4 2006Implications for conservation, improvement of the stocks First page of article [source] Relationship Between Glycosylated Hemoglobin and Arterial ElasticityPREVENTIVE CARDIOLOGY, Issue 3 2006L. Michael Prisant MD Arterial elasticity is decreased in diabetes, but it is unclear whether there is a relationship between glycosylated hemoglobin (HbA1c) and arterial elasticity. To evaluate this question, 111 subjects with diabetes mellitus had HbA1c and arterial elasticity determined in an academic outpatient setting. Three measurements of arterial elasticity indices were obtained supine using the HDI/PulseWave CR-2000 Research Cardiovascular Profiling System (Hypertension Diagnostics Inc., Eagan, MN). The study population was 49% black and 51% women. Population characteristics included age, 49.2 years; duration of diabetes, 12.1 years; HbA1c, 8.9%; large artery elasticity, 11.8 mL/mm Hg × 10; and small artery elasticity, 4.7 mL/mm Hg × 100. Age correlated with diminished large artery elasticity. Women had a lower large artery elasticity than men (10.6 vs. 13.3 mL/mm Hg × 10; p=0.0002). Decreasing small artery elasticity was associated with increasing age (p=0.0001), HbA1c (p=0.0184), and African-American ethnicity (p=0.0306). Women had less small artery elasticity than men (3.8 vs. mL/mm Hg × 100; p=0.0001). Black diabetic patients had a reduced arterial elasticity compared with whites. Increasing HbA1c is associated with decreasing small artery elasticity, but not large artery elasticity. In diabetic patients, small artery elasticity is reduced to a greater extent in women than men and in blacks than whites. [source] An introduction to medical statistics for health care professionals: Hypothesis tests and estimationMUSCULOSKELETAL CARE, Issue 2 2005Elaine Thomas PhD MSc BSc Lecturer in Biostatistics Abstract This article is the second in a series of three that will give health care professionals (HCPs) a sound introduction to medical statistics (Thomas, 2004). The objective of research is to find out about the population at large. However, it is generally not possible to study the whole of the population and research questions are addressed in an appropriate study sample. The next crucial step is then to use the information from the sample of individuals to make statements about the wider population of like individuals. This procedure of drawing conclusions about the population, based on study data, is known as inferential statistics. The findings from the study give us the best estimate of what is true for the relevant population, given the sample is representative of the population. It is important to consider how accurate this best estimate is, based on a single sample, when compared to the unknown population figure. Any difference between the observed sample result and the population characteristic is termed the sampling error. This article will cover the two main forms of statistical inference (hypothesis tests and estimation) along with issues that need to be addressed when considering the implications of the study results. Copyright © 2005 Whurr Publishers Ltd. [source] ESTIMATING INTERVENTION EFFECTS IN VARYING RISK SETTINGS: DO POLICE RAIDS REDUCE ILLEGAL DRUG DEALING AT NUISANCE BARS?,CRIMINOLOGY, Issue 2 2003JACQUELINE COHEN This paper investigates the effectiveness of police raids in reducing drug dealing in and around nuisance bars. We examine effects of both dosage (number of raids) and duration (months) of the intervention, as well as the conditioning effects of land use and population characteristics in shaping the underlying risk levels of drug dealing in the target and surrounding areas. Results indicate that the police intervention suppresses levels of drug dealing during periods of active enforcement, but the effects largely disappear when the intervention is withdrawn. Also, the effects of the intervention are mediated by risk characteristics in target and surrounding areas. Target areas characterized by higher levels of risk are more resistant to intervention effects than those with lower levels of risk. Risk factors in nearby areas are also significant. Bars with high levels of risk arising from land uses in surrounding areas are easier to treat, while bars with high levels of population-based risk in surrounding areas are harder to treat. [source] The metabolic syndrome and changing relationship between blood pressure and insulin with age, as observed in Aboriginal and Torres Strait Islander peoplesDIABETIC MEDICINE, Issue 11 2005A. E. Schutte Abstract Aims To determine the prevalence of the metabolic syndrome (MS) among Aboriginal and Torres Strait Islander peoples. A further objective was to investigate the relationships between fasting insulin and blood pressure (BP) within these groups with increasing age. Methods A cross-sectional population-based study included 369 Torres Strait Islanders (residing in Torres Strait and Far North Queensland), and 675 Aborigines from central Australia. Data necessary for classification of MS was collected, including fasting and 2-h glucose and insulin, urinary albumin and creatinine, anthropometric measurements, BP, serum lipids. Results The ATPIII criteria classified 43% of Torres Strait Islanders and 44% of Aborigines with MS, whereas 32 and 28%, respectively, had the MS according to WHO criteria. Agreement between the two criteria was only modest (kappa coefficient from 0.28 to 0.57). Factor analyses indicated no cluster including both insulin and BP in either population. Significant correlations (P < 0.05) [adjusted for gender, body mass index (BMI) and waist circumference] were observed between BP and fasting insulin: a positive correlation for Torres Strait Islanders aged 15,29 years, and an inverse correlation for Aborigines aged 40 years and older. Conclusion Torres Strait Islanders and Aborigines had very high prevalences of the MS. Specific population characteristics (high prevalences of central obesity, dyslipidaemia, renal disease) may make the WHO definition preferable to the ATPIII definition in these population groups. The poor agreement between criteria suggests a more precise definition of the metabolic syndrome that is applicable across populations is required. This study showed an inverse relationship with age for the correlation of BP and fasting insulin. [source] Effects of crowding on populations of Aedes albifasciatus larvae under laboratory conditionsENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2000Raquel M. Gleiser Abstract Aedes (Ochlerotatus) albifasciatus (Macquart 1838) (Diptera: Culicidae) is a neotropical flood water mosquito, incriminated as the main vector of the western equine encephalitis virus, and which affects beef and milk production in central Argentina. The short time required to hatch and develop from egg to adult, usually in temporary pools, suggests a strategy which allows for exploitation of transient pools, thus evading predation and interspecific competition. Under these conditions intra specific competition could represent a major density-dependent source of larval mortality, but the relative importance of density-dependent regulation of mosquito populations has generated controversy. Therefore we examined the effects of larval density on basic population characteristics of Ae. albifasciatus in the laboratory. Larvae were obtained by synchronous hatching of eggs laid by field-trapped females. Emerging larvae (L1) were used to build cohorts of different initial densities, kept in plastic trays with 400 ml of distilled water, and food supplied daily during the first 10 days (0.1 g per larvae day,1). Age-specific development time and specific and relative mortality were estimated, and their relation to initial larval density was assessed through linear and non-linear regressions and correlation analysis. First hatching was registered 3 h after flooding the eggs. Higher levels of pre-adult mortality were detected in groups with higher densities. Specific mortality and average time to enter a stage of L1 to L3 could directly be related to initial larval density, but no significant relations were found for L4 and pupae. Results suggest that crowding could be a factor capable of regulating the density of natural populations of Ae. albifasciatus. [source] Seed supply for broadscale restoration: maximizing evolutionary potentialEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 4 2008Linda M. Broadhurst Abstract Restoring degraded land to combat environmental degradation requires the collection of vast quantities of germplasm (seed). Sourcing this material raises questions related to provenance selection, seed quality and harvest sustainability. Restoration guidelines strongly recommend using local sources to maximize local adaptation and prevent outbreeding depression, but in highly modified landscapes this restricts collection to small remnants where limited, poor quality seed is available, and where harvesting impacts may be high. We review three principles guiding the sourcing of restoration germplasm: (i) the appropriateness of using ,local' seed, (ii) sample sizes and population characteristics required to capture sufficient genetic diversity to establish self-sustaining populations and (iii) the impact of over-harvesting source populations. We review these topics by examining current collection guidelines and the evidence supporting these, then we consider if the guidelines can be improved and the consequences of not doing so. We find that the emphasis on local seed sourcing will, in many cases, lead to poor restoration outcomes, particularly at broad geographic scales. We suggest that seed sourcing should concentrate less on local collection and more on capturing high quality and genetically diverse seed to maximize the adaptive potential of restoration efforts to current and future environmental change. [source] Global Family Concerns and the Role of Family Life Education: An Ecosystemic AnalysisFAMILY RELATIONS, Issue 1 2009Carol A. Darling We surveyed colleagues from 4 international professional organizations involved with families in order to examine global family concerns and the role of family life education from an ecosystemic perspective. Our sample represented 6 continents and 50 countries. Survey results indicated that family education and related coursework were available in all continents along with considerable public interest in family education. International public concern about family issues was related to population characteristics, values related to parenting and childrearing, interest in family and health legislation/regulations, and public interest in family, parent, and marriage education. [source] A National Study of Efficiency for Dialysis Centers: An Examination of Market Competition and Facility Characteristics for Production of Multiple Dialysis OutputsHEALTH SERVICES RESEARCH, Issue 3 2002Hacer Ozgen Objective. To examine market competition and facility characteristics that can be related to technical efficiency in the production of multiple dialysis outputs from the perspective of the industrial organization model. Study Setting. Freestanding dialysis facilities that operated in 1997 submitted cost report forms to the Health Care Financing Administration (HCFA), and offered all three outputs,outpatient dialysis, dialysis training, and home program dialysis. Data Sources. The Independent Renal Facility Cost Report Data file (IRFCRD) from HCFA was utilized to obtain information on output and input variables and market and facility features for 791 multiple-output facilities. Information regarding population characteristics was obtained from the Area Resources File. Study Design. Cross-sectional data for the year 1997 were utilized to obtain facility-specific technical efficiency scores estimated through Data Envelopment Analysis (DEA). A binary variable of efficiency status was then regressed against its market and facility characteristics and control factors in a multivariate logistic regression analysis. Principal Findings. The majority of the facilities in the sample are functioning technically inefficiently. Neither the intensity of market competition nor a policy of dialyzer reuse has a significant effect on the facilities' efficiency. Technical efficiency is significantly associated, however, with type of ownership, with the interaction between the market concentration of for-profits and ownership type, and with affiliations with chains of different sizes. Nonprofit and government-owned facilities are more likely than their for-profit counterparts to become inefficient producers of renal dialysis outputs. On the other hand, that relationship between ownership form and efficiency is reversed as the market concentration of for-profits in a given market increases. Facilities that are members of large chains are more likely to be technically inefficient. Conclusions. Facilities do not appear to benefit from joint production of a variety of dialysis outputs, which may explain the ongoing tendency toward single-output production. Ownership form does make a positive difference in production efficiency, but only in local markets where competition exists between nonprofit and for-profit facilities. The increasing inefficiency associated with membership in large chains suggests that the growing consolidation in the dialysis industry may not, in fact, be the strategy for attaining more technical efficiency in the production of multiple dialysis outputs. [source] Systematic review of randomized controlled trials of pharmacological interventions to reduce ischaemia-reperfusion injury in elective liver resection with vascular occlusionHPB, Issue 1 2010Mahmoud Abu-Amara Abstract Background:, Vascular occlusion during liver resection results in ischaemia-reperfusion (IR) injury, which can lead to liver dysfunction. We performed a systematic review and meta-analysis to assess the benefits and harms of using various pharmacological agents to decrease IR injury during liver resection with vascular occlusion. Methods:, Randomized clinical trials (RCTs) evaluating pharmacological agents in liver resections conducted under vascular occlusion were identified. Two independent reviewers extracted data on population characteristics and risk of bias in the trials, and on outcomes such as postoperative morbidity, hospital stay and liver function. Results:, A total of 18 RCTs evaluating 17 different pharmacological interventions were identified. There was no significant difference in perioperative mortality, liver failure or postoperative morbidity between the intervention and control groups in any of the comparisons. A significant improvement in liver function was seen with methylprednisolone use. Hospital and intensive therapy unit stay were significantly shortened with trimetazidine and vitamin E use, respectively. Markers of liver parenchymal injury were significantly lower in the methylprednisolone, trimetazidine, dextrose and ulinastatin groups compared with their respective controls (placebo or no intervention). Discussion:, Methylprednisolone, trimetazidine, dextrose and ulinastatin may have protective roles against IR injury in liver resection. However, based on the current evidence, they cannot be recommended for routine use and their application should be restricted to RCTs. [source] How you count counts: the importance of methods research in applied ecologyJOURNAL OF APPLIED ECOLOGY, Issue 5 2008Chris S. Elphick Summary 1Methods papers play a crucial role in advancing applied ecology. Counting organisms, in particular, has a rich history of methods development with many key advances both in field sampling and the treatment of resulting data. 2Most counts, however, have associated errors due to portions of the population of interest being unavailable for detection (e.g. target population not fully sampled; individuals present but not detectable), detection mistakes (e.g. detectable individuals missed; non-existent individuals recorded), or erroneous counts (e.g. large groups miscounted; individuals misidentified). 3Developments in field methods focus on reducing biases in the actual counts. Simultaneously, statisticians have developed many methods for improving inference by quantifying and correcting for biases retrospectively. Prominent examples of methods used to account for detection errors include distance sampling and multiple-observer methods. 4Simulations, in which population characteristics are set by the investigator, provide an efficient means of testing methods. With good estimates of sampling biases, computer simulations can be used to evaluate how much a given counting problem affects estimates of parameters such as population size and decline, thereby allowing applied ecologists to test the efficacy of sampling designs. Combined with cost estimates for each field method, such models would allow the cost-effectiveness of alternative protocols to be assessed. 5Synthesis and applications. Major advances are likely to come from research that looks for systematic patterns, across studies, in the effects of different types of bias and assumption violation on the ecological conclusions drawn. Specifically, determining how often, and under what circumstances, errors contribute to poor management and policy would greatly enhance future application of ecological knowledge. [source] Impact of the black rhinoceros (Diceros bicornis minor) on a local population of Euphorbia bothae in the Great Fish River Reserve, South AfricaAFRICAN JOURNAL OF ECOLOGY, Issue 4 2009Bodina L. Luske Abstract In the Great Fish River Reserve, South Africa, black rhinoceros (Diceros bicornis minor) feed extensively on a local population of Euphorbia bothae. Maintaining the endangered black rhinoceros and the protected E. bothae population are both conservation priorities of the reserve. Therefore, the sustainability of this plant,animal interaction was investigated by comparing population characteristics, browsing incidence and intensity within the reserve and in an adjacent exclosure without access to rhino. Fixed-point photographs showed that over a 2-month period 36.6% of 213 monitored plants were browsed, with an average biomass loss of 13%, and 1% were destroyed. Of 26 plants re-photographed after approximately 3 years, 70% showed a decrease in biomass, averaging 37.8% over this period. In this time span, 19% of the monitored plants died. Small plants (<45 cm) were over-represented in the rhino-browsed area, whereas the fraction of reproductively active plants and overall plant density were found to be lower than in the adjacent exclosure. No evidence of short-term compensatory growth in response to browsing was found for E. bothae. This study indicates that, with the current population size, rhinos are overexploiting the E. bothae population and special measures should be taken to prevent local extinction. Résumé Dans la Great Fish River Reserve, en Afrique du Sud, le rhinocéros noir (Diceros bicornis minor) se nourrit en très grande partie d'une population locale d'Euphorbia bothae. Le maintien du rhino noir en danger et de la population protégée d'E. bothae sont deux priorités de la réserve en matière de conservation. C'est pourquoi on a investigué la durabilité de cette interaction plante-animal en comparant les caractéristiques des populations, l'incidence et l'intensité de la consommation du rhino dans la réserve et dans un enclos adjacent d'où les rhinos sont exclus. Des photographies prises d'un point fixe ont montré que, sur une période de deux mois, 36.6% des 213 plantes suivies avaient été broutées, avec une perte moyenne de biomasse de 13%, et un pour cent avait été détruit. Des 26 plantes qui avaient été rephotographiées après environ trois ans, 70% montraient une diminution de la biomasse, qui était de 37.8% en moyenne pour cette période. Pendant ce laps de temps, 19% des plantes suivies sont mortes. Les petites plantes (<45 cm) étaient surreprésentées dans la zone broutée par les rhinos, alors que la fraction des plantes actives au point de vue reproduction et la densité générale des plantes se sont avérées plus faibles que dans l'enclos adjacent. On n'a pu mettre en évidence aucune croissance compensatoire d'E. bothaeà court terme en réponse au broutage des rhinos. Cette étude indique que, vu la taille actuelle de leur population, les rhinos surexploitent la population d'E. bothae et qu'il faut prendre des mesures spéciales pour empêcher l'extinction locale de cette dernière. [source] Spatio-temporal variation in fruit production and seed predation in a perennial herb influenced by habitat quality and population sizeJOURNAL OF ECOLOGY, Issue 2 2008Jon Ågren Summary 1In patchily distributed plant species, seed production is likely to be influenced both by local abiotic factors affecting plant size and conditions for fruit maturation, and by population characteristics affecting the intensity of interactions with mutualists and antagonists. However, the relative importance of these effects is poorly known. 2We used multiple regression and path models to examine the importance of abiotic factors (sun exposure, soil depth) and population characteristics (size, density and connectivity) for variation in flower and fruit production and intensity of seed predation among 39 populations of the long-lived herb Vincetoxicum hirundinaria in three consecutive years. In addition, we manipulated water availability in a field experiment and recorded short-term and long-term effects on fruit output, and conducted a supplemental hand-pollination experiment. 3Flower production varied little, while fruit initiation, fruit abortion and fruit predation varied considerably among years. Sun exposure and soil depth affected fruit production per plant indirectly and positively through their effects on flower number. Population density affected fruit production negatively through its effect on flower number. Both fruit initiation and the proportion of fruits attacked by the tephritid fly Euphranta connexa were related positively to population size. 4The number of full-size fruits per plant was related positively to sun exposure and population size in two years each, and related negatively to population density in one year. However, because of seed predation, the number of intact mature fruits was related significantly to population characteristics in only one of three years. 5The field experiments showed that both shortage of water and insufficient pollination may limit fruit set in V. hirundinaria. 6Synthesis. These results demonstrate that the relative importance of local abiotic conditions and population characteristics may vary considerably along the chain of events from flower formation to intact fruit, and also among years. They further show that, at least in species with a naturally patchy distribution, connectivity may be relatively unimportant for variation in reproductive output compared to effects of habitat quality, population size and density. [source] An explanatory model of medical practice variation: a physician resource demand perspectiveJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 2 2002Michael J. Long MA PhD Abstract Practice style variation, or variation in the manner in which physicians treat patients with a similar disease condition, has been the focus of attention for many years. The research agenda is further intensified by the unrealistic assumption that by reducing variation, quality will be improved, costs will be reduced, or both. There is a wealth of literature that identifies differences in health care use of many kinds, in apparently similar communities. Attempts have been made by many scholars to identify the determinants of variation in terms of differences in the population characteristics (e.g. age, sex, insurance, etc.) and geographical characteristics (e.g. distance to provider, number of physicians, number of hospital beds, etc.). When significant differences in use rates prevail after controlling for differences in population characteristics, it is often attributed to ,uncertainty', or the fact that there is no consensus on what constitutes the optimum treatment process. It is suggested by this literature that the greatest variation can be found in the circumstances where there is the most ,uncertainty'. In this work, a physician resource demand model is proposed in which it is suggested that, during the diagnosis and treatment process, physicians demand resources consistent with the clinical needs of the patients, modified by the intervening forces under which they practice. These intervening forces, or constraints, are categorized as patient agency constraints, organizational constraints and environmental constraints, which are characterized as ,induced variation'. It is suggested that when all of the variables that constitute these constraints are identified, the remaining variance represents ,innate variance', or practice style differences. It is further suggested that the more completely this model is specified, the more likely area differences will be attenuated and the smaller will be the residual variance. [source] Suicide and Alcohol: Do Outlets Play a Role?ALCOHOLISM, Issue 12 2009Fred W. Johnson Background:, The purpose of this study was to determine whether the number of alcohol outlets in local and adjacent areas, in particular bars, was related over time to completed suicide and suicide attempts. There is evidence both from studies of individuals and time series aggregate studies, mostly at the national level, of substantial alcohol involvement in suicide, but no small-area, longitudinal studies have been carried out. The present study is the first that is both longitudinal and based on a large number of small spatial units, California zip codes, a level of resolution permitting analysis of the relationship between local alcohol access and suicide rates over time. Method:, Longitudinal data were obtained from 581 consistently defined zip code areas over 6 years (1995,2000) using data from the California Index Locations Database, a geographic information system that contains both population and place information with spatial attributes for the entire state. Measures obtained from each zip code included population characteristics (e.g., median age) and place characteristics (e.g., numbers of retail and alcohol outlets) which were related in separate analyses to (i) suicide mortality and (ii) the number of hospitalizations for injuries caused by suicide attempts. The effect of place characteristics in zip code areas adjacent to each of the 581 local zip codes (spatial lags) was also assessed. Analysis methods were random effects models corrected for spatial autocorrelation. Results:, Completed suicide rates were higher in zip code areas with greater local and lagged bar densities; and higher in areas with greater local but not lagged off-premise outlet densities. Whereas completed suicide rates were lower among blacks and Hispanics, completed suicide rates were higher among low income, older whites living in less densely populated areas, that is, rural areas. Rates of suicide attempts were higher in zip code areas with greater local but not lagged bar densities, and higher among low income younger whites living in smaller households and in rural areas. Rates of attempted suicide were also higher among blacks. Completed suicide and suicide attempt rates were lower in zip code areas with greater local restaurant densities; there were no lagged effects for restaurants. Conclusions:, Bar densities in particular appear related to suicide, meaning, because this is an aggregate-level spatial analysis, that suicides, both attempted and completed, occur at greater rates in rural community areas with greater bar densities. Because the suicide rate is highest in rural areas, this study suggests that although the number of completed and attempted suicides is no doubt greater in absolute numbers in urban areas, the suicide rate, both completed and attempted, is greater in rural areas, which draws attention, perhaps much needed, to the problems of rural America. [source] Severe blunt trauma in dogs: 235 cases (1997,2003)JOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 6 2009Stephen A. Simpson DVM Abstract Objective , To evaluate population characteristics, injuries, emergency diagnostic testing, and outcome of dogs with blunt trauma requiring intensive care in an urban hospital. Design , Retrospective study 1997,2003. Setting , All data obtained from the University of Pennsylvania , Matthew J. Ryan Veterinary Hospital. Animals , Dogs admitted to the intensive care unit for treatment following blunt trauma. Interventions , None. Measurements and Main results , Of the 235 dogs that met inclusion criteria, 206 (88%) survived and 29 (12%) did not survive. Blunt vehicular trauma accounted for 91.1% of cases. Mild hyperglycemia and hyperlactatemia was common in both survivors and nonsurvivors. The chest was the most common region traumatized and the prevalence of polytrauma was 72.3%. Initial weight, vital signs, PCV, total plasma protein, BUN, glucose, lactate, acid-base status, and electrolytes did not differ between survivors and nonsurvivors. Nonsurvivors were significantly more likely to have had head trauma (P=0.008), cranium fractures (P<0.001), recumbency at admission (P<0.001), development of hematochezia (P<0.001), clinical suspicion of acute respiratory distress syndrome (P<0.001), disseminated intravascular coagulation (P<0.001), multiorgan dysfunction syndrome (P<0.001), development of pneumonia (P<0.001), positive-pressure ventilation (P<0.001), vasopressor use (P<0.001), and cardiopulmonary arrest (P<0.001). Conclusions , Outcome of severe blunt trauma in dogs treated with intensive care is very good. Despite the high survival rate, several features associated with poor outcome were identified. Neither admission lactate nor glucose was able to predict outcome. [source] Populating the Galaxy with pulsars , I. Stellar and binary evolutionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008Paul D. Kiel ABSTRACT The computation of theoretical pulsar populations has been a major component of pulsar studies since the 1970s. However, the majority of pulsar population synthesis has only regarded isolated pulsar evolution. Those that have examined pulsar evolution within binary systems tend to either treat binary evolution poorly or evolve the pulsar population in an ad hoc manner. Thus, no complete and direct comparison with observations of the pulsar population within the Galactic disc has been possible to date. Described here is the first component of what will be a complete synthetic pulsar population survey code. This component is used to evolve both isolated and binary pulsars. Synthetic observational surveys can then be performed on this population for a variety of radio telescopes. The final tool used for completing this work will be a code comprised of three components: stellar/binary evolution, Galactic kinematics and survey selection effects. Results provided here support the need for further (apparent) pulsar magnetic field decay during accretion, while they conversely suggest the need for a re-evaluation of the assumed typical millisecond pulsar formation process. Results also focus on reproducing the observed diagram for Galactic pulsars and how this precludes short time-scales for standard pulsar exponential magnetic field decay. Finally, comparisons of bulk pulsar population characteristics are made to observations displaying the predictive power of this code, while we also show that under standard binary evolutionary assumption binary pulsars may accrete much mass. [source] Do differences in maternal age, parity and multiple births explain variations in fetal and neonatal mortality rates in Europe?PAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 4 2009Results from the EURO-PERISTAT project Summary Perinatal mortality rates differ markedly between countries in Europe. If population characteristics, such as maternal age, parity or multiple births, contribute to these differences, standardised rates may be useful for international comparisons of health status and especially quality of care. This analysis used aggregated population-based data on fetal and neonatal mortality stratified by maternal age, parity and multiple birth from 12 countries participating in the EURO-PERISTAT project to explore this question. Adjusted odds ratios were computed for fetal and neonatal mortality and tested for inter-country heterogeneity; standardised mortality rates were calculated using a direct standardisation method. There were wide variations in fetal and neonatal mortality rates, from 3.3 to 7.1 and 2.0 to 6.0 per 1000 total and livebirths, respectively, and in the prevalence of mothers over 35 (7,22%), primiparae (41,50%) and multiple births (2,4%). These population characteristics had a significant association with mortality, although results were less consistent for primiparity. Odds ratios for older mothers and primiparae showed significant inter-country heterogeneity. The association between maternal age and fetal mortality declined as the prevalence of older mothers in the population increased. Standardised rates did not substantially change inter-country rankings and demographic characteristics did not explain the higher mortality observed in some countries. Our results do not support the use of mortality rates standardised for age, parity and multiple births for international comparisons of quality of care. Further research should explore why the negative effects of older maternal age decrease as delayed childbearing becomes more common and, in particular, whether this is due to changes in the social characteristics of older mothers or in health care provision. [source] The Kalgoorlie Otitis Media Research Project: rationale, methods, population characteristics and ethical considerationsPAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 1 2008Deborah Lehmann Summary Otitis media (OM) is one of the most common paediatric illnesses for which medical advice is sought in developed countries. Australian Aboriginal children suffer high rates of OM from early infancy. The resultant hearing loss can affect education and quality of life. As numerous factors contribute to the burden of OM, interventions aimed at reducing the impact of single risk factors are likely to fail. To identify key risk factors and understand how they interact in complex causal pathways, we followed 100 Aboriginal and 180 non-Aboriginal children from birth to age 2 years in a semi-arid zone of Western Australia. We collected demographic, obstetric, socio-economic and environmental data, breast milk once, and nasopharyngeal samples and saliva on seven occasions. Ear health was assessed by clinical examination, tympanometry, transient evoked otoacoustic emissions and audiometry. We considered the conduct of our study in relation to national ethical guidelines for research in Aboriginal and Torres Strait Islander health. After 1 year of community consultation, the study was endorsed by local committees and ethical approval granted. Fieldwork was tailored to minimise disruption to people's lives and we provided regular feedback to the community. We saw 81% of non-Aboriginal and 65% of Aboriginal children at age 12 months. OM was diagnosed on 55% and 26% of routine clinical examinations in Aboriginal and non-Aboriginal children respectively. Aboriginal mothers were younger and less educated, fewer were employed and they lived in more crowded conditions than non-Aboriginal mothers. Sixty-four per cent of Aboriginal and 40% of non-Aboriginal babies were exposed to environmental tobacco smoke. Early consultation, provision of a service while undertaking research, inclusion of Aboriginal people as active members of a research team and appropriate acknowledgement will assist in ensuring successful completion of the research. [source] A public health collaboration for the surveillance of autism spectrum disordersPAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 2 2007Catherine E. Rice Summary Autism spectrum disorders (ASDs) represent a range of behavioural phenotypes defined by impaired development in social interaction, communication, imagination, and range of interests or behaviours. The aetiology and epidemiology of these serious developmental disabilities (DDs) are poorly understood. Estimates of the population prevalence of ASDs have varied widely within the US and abroad, with increasing estimates in most of the recent studies. In an effort to improve our understanding of the prevalence, population characteristics and public health impact of these conditions, the Centers for Disease Control and Prevention has funded a multi-site surveillance network for ASDs and other DDs that consists of programmes known as the Autism and Developmental Disabilities Monitoring (ADDM) network which conducts surveillance activities and the Centers for Autism and Developmental Disabilities Research and Epidemiology (CADDRE) which also conducts surveillance in addition to special research studies related to the ASDs. This collaboration will be referred to hereafter as the ADDM Network. The ADDM Network is implementing a multiple-source surveillance programme to determine population prevalence and characteristics of ASDs and other DDs. This paper describes the collaborative efforts and explains the methods in developing this coordinated public health surveillance network to provide an ongoing source of high-quality data on ASDs. [source] National addictions vigilance intervention and prevention program (NAVIPPROÔ): a real-time, product-specific, public health surveillance system for monitoring prescription drug abuse,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 12 2008Stephen F. Butler PhD Abstract Purpose The National Addictions Vigilance Intervention and Prevention Program (NAVIPPROÔ) is a scientific, comprehensive risk management program for scheduled therapeutics. NAVIPPROÔ provides post-marketing surveillance, signal detection, signal verification and prevention and intervention programs. Here we focus on one component of NAVIPPROÔ surveillance, the Addiction Severity Index-Multimedia Version® (ASI-MV®) Connect, a continuous, real-time, national data stream that assesses pharmaceutical abuse by patients entering substance abuse treatment by collecting product-specific, geographically-detailed information. Methods We evaluate population characteristics for data collected through the ASI-MV® Connect in 2007 and 2008 and assess the representativeness, geographic coverage, and timeliness of report of the data. Analyses based on 41,923 admissions to 265 treatment centers in 29 states were conducted on product-specific opioid abuse rates, source of drug, and route of administration. Results ASI-MV® Connect data revealed that 11.5% of patients reported abuse of at least one opioid analgesic product in the 30 days prior to entering substance abuse treatment; differences were observed among sub-populations of prescription opioid abusers, among products, and also within various geographic locations. Conclusions The ASI-MV® Connect component of NAVIPPROÔ represents a potentially valuable data stream for post-marketing surveillance of prescription drugs. Analyses conducted with data obtained from the ASI-MV® Connect allow for the characterization of product-specific and geospatial differences for drug abuse and can serve as a tool to monitor responses of the abuse population to newly developed "abuse deterrent" drug formulations. Additional data, evaluation, and comparison to other systems are important next steps in establishing NAVIPPROÔ as a comprehensive, post-marketing surveillance system for prescription drugs. Copyright © 2008 John Wiley & Sons, Ltd. [source] On the Use of Allelic Transmission Rates for Assessing Gene-by-Environment Interaction in Case-Parent TriosANNALS OF HUMAN GENETICS, Issue 5 2010Ji-Hyung Shin Summary Allelic transmission rates from parents to cases are frequently stratified by an environmental risk factor E and compared, with heterogeneity interpreted as gene-environment interaction or G×E. Though generally invalid, such analyses continue to appear. We revisit why heterogeneity is not equivalent to G×E in a range of settings not considered previously. The objective is a fuller understanding of the bias in transmission rates and what is driving it. Extending previously published findings, we derive parental mating-type probabilities in cases and use them to obtain transmission rates, which we then compare to G×E. Through simulation, we investigate the practical implications of the bias for a transmission-based test of G×E. We find that general population characteristics distort the picture of G×E obtained from transmission rates: the stratum-specific mating-type probabilities under G , E dependence and the allele frequency under independence. Furthermore, the transmission-based test has inflated error rates relative to a likelihood-based test. Our investigation provides further insight into how and why transmission-based tests and descriptive summaries can mislead about G×E. For exploring G×E, we suggest graphical displays of the transmission rates within parental mating types, as they are robust to population stratification and the penetrance model. [source] A continuum of structure and stellar content from Virgo cluster earlytype dwarfs to giants?ASTRONOMISCHE NACHRICHTEN, Issue 9-10 2009J. Janz Abstract Based on the wealth of multiwavelength imaging data from the SDSS, we investigate whether dwarf and giant early-type galaxies in the Virgo cluster follow a continuum in their structural parameters and their stellar population characteristics. More specifically we study the relation between size and brightness for the galaxies and their color magnitude relation. In both cases, we find noticeable deviations from a simple joint behavior of dwarfs and giants. We discuss these findings in the light of the different formation mechanisms commonly assumed for dwarf and giant early types, thereby taking into account the existence of several distinct early-type dwarf subclasses. By comparing our results to a semianalytic model of galaxy formation, we argue that the analyzed relations might be reproduced by processes that form dwarfs and giants altogether. The work presented here is based on Janz & Lisker (2008, 2009) (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A pooled analysis of adjunctive topiramate in refractory partial epilepsyACTA NEUROLOGICA SCANDINAVICA, Issue 1 2003K. Peeters Objectives , To evaluate the impact of different dosages of topiramate (TPM) add-on to stable antiepileptic therapy for refractory partial epilepsy in adults. Material and methods , Pooled intention-to-treat analysis of six similarly designed double-blind, placebo-controlled trials, including 481 patients treated with doses of TPM 200, 400, 600 and 800 mg/day, and 265 patients receiving placebo. Results , Seizures were reduced by ,50% from baseline in 41% of TPM-treated patients and 15% of placebo-treated patients (P < 0.001); 5 and 0.8%, respectively, were seizure-free (P < 0.003). TPM was significantly better than placebo regardless of gender, age, baseline seizure rate as well as number and type of concomitant antiepileptic drugs. Efficacy was statistically significant in favour of TPM at all dose levels: at least 50% seizure reduction was achieved in 40% of patients with 200 mg, 41% with 400 mg, 44% with 600 mg and 41% with 800 mg TPM when compared with 15% with placebo (P , 0.001 for each dosage arm vs placebo). The median reduction in monthly seizure frequency was 38%, 42%, 45% and 38% vs 8%, respectively (P , 0.001). Moreover, response to TPM was significantly superior to placebo at each of the dose levels tested for most of the baseline variables. The total percentage of withdrawals increased with the dosage, and the withdrawals caused by adverse events increased from 3% with placebo to 7% with 200 mg TPM (not significant vs placebo), 15% with 400 mg TPM (P = 0.08), 16% with 600 mg TPM (P = 0.002) and 15% with 800 mg TPM (P = 0.003). Conclusion , The efficacy of TPM add-on in partial epilepsy is consistent across efficacy endpoints and independent of study population characteristics. The response at 200 mg TPM is similar to the response at higher doses, but as drop-outs caused by adverse events are more frequent above the 200 mg dose, this pooled analysis supports that 200 mg daily is a good target dose for add-on therapy in most patients with partial epilepsy, showing an excellent balance between efficacy and tolerability. [source] Systematic Bias Introduced by the Informed Consent Process in a Diagnostic Research StudyACADEMIC EMERGENCY MEDICINE, Issue 3 2008Alice M. Mitchell MD Abstract Objectives:, To determine population characteristics, outcomes, and reasons for unsuccessful enrollment among potential study subjects approached for written, informed consent in a minimal-risk emergency department (ED) study. The authors hypothesized that the prevalence of venous thromboembolism (VTE) would be lower among study participants and that medical acuity and refusal to provide a blood sample would be the most common reasons for nonparticipation. Methods:, The authors requested prospective, written, informed consent for a blood sample and follow-up from consecutive ED patients undergoing evaluation for pulmonary embolism (PE) and recorded spontaneously stated reasons for refusal. VTE was diagnosed or excluded using a combination of D-dimer testing and selective computed tomography (CT) angiography of the chest with venography of the lower extremities. The primary outcome was defined by the number of CT scans positive for VTE among ED patients evaluated for PE. Results:, Over 16 weeks, 260 of 287 (91%, 95% confidence interval [CI] = 87 to 94%) eligible patients were approached and consent was obtained from 183 patients (64%, 95% CI = 58% to 69%). The prevalence of VTE was 6% among participants and 13% among nonparticipants (95% CI [of the difference] = 1% to 15%). The proportions of African Americans, uninsured, and Medicaid patients were significantly higher among nonparticipants. No significant differences were found in the proportions of nonparticipants who disliked or distrusted research or desired financial reimbursement, compared to those not enrolled due to medical acuity or refused a blood sample. Conclusions:, These data implicate the written, informed consent process as a significant source of bias on estimated disease prevalence. [source] Frequency of renal impairment, advanced age, obesity and cancer in venous thromboembolism patients in clinical practiceJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 5 2007L. M. COOK Summary.,Background:,Low-molecular-weight heparin (LMWH) dosed by weight is recommended as first-line therapy for the initial treatment of venous thromboembolism (VTE) and as monotherapy for long-term treatment of cancer-related VTE. In ,special populations' such as those with renal impairment or the elderly, weight-based dosing may be excessive, and capping the dose in obese patients may lead to inadequate dosing. Objectives:,We determined the frequency of ,special population' characteristics (renal impairment, advanced age, obesity) and cancer among VTE patients in clinical practice, and assessed whether these characteristics appeared to influence the type and dose of anticoagulants prescribed. Methods:,During 2004,2005, among consecutive patients with VTE at two large Canadian hospitals, the proportions with the above characteristics were calculated and treatments prescribed were determined. Results:,Of 524 VTE patients, 31% were aged > 75 years. Moderate renal impairment [creatinine clearance (CrCl) 30,59 mL min,1] was present in 20% of patients, and severe renal impairment (CrCl < 30 mL min,1) in 5% of patients. LMWH was prescribed to 67% of patients with severe renal impairment and to 83% of patients with moderate renal impairment. Body weight was > 100 kg in 15% of patients. Underdosing of LMWH by > 10% was documented in 36% of such patients compared with 8% of patients < 100 kg (P < 0.001). Among 26% of patients with active cancer, only one-third were prescribed LMWH monotherapy. Conclusions:,In clinical practice, renal impairment, advanced age, obesity and cancer are frequently present in patients with VTE. A considerable proportion of these patients may not receive the optimal type or dose of medication to treat VTE. [source] | |||||||||||||||||||