Current Rates (current + rate)

Distribution by Scientific Domains

Selected Abstracts

An Epidemiologic Study of Aboriginal Adolescent Risk in Canada: The Meaning of Suicide

Melanie S. MacNeil RN
BACKGROUND:,Current rates of Aboriginal youth suicide suggest that an epidemiologic review is needed to understand the impact of culture, community, and environment specific to suicide within this population. PURPOSE:,This paper aims to (a) examine the literature on the incidence of suicide with special attention to that of adolescents in Aboriginal communities in Canada, (b) review factors hypothesized to place Aboriginals at risk, and (c) explore research directions that would contribute to our understanding of an Aboriginal perspective of suicide. CONCLUSION:,A clear description of the meaning of adolescent Aboriginal suicide and an understanding of the factors that create risk is needed. [source]

Climate change and freshwater biodiversity: detected patterns, future trends and adaptations in northern regions

Jani Heino
Abstract Current rates of climate change are unprecedented, and biological responses to these changes have also been rapid at the levels of ecosystems, communities, and species. Most research on climate change effects on biodiversity has concentrated on the terrestrial realm, and considerable changes in terrestrial biodiversity and species' distributions have already been detected in response to climate change. The studies that have considered organisms in the freshwater realm have also shown that freshwater biodiversity is highly vulnerable to climate change, with extinction rates and extirpations of freshwater species matching or exceeding those suggested for better-known terrestrial taxa. There is some evidence that freshwater species have exhibited range shifts in response to climate change in the last millennia, centuries, and decades. However, the effects are typically species-specific, with cold-water organisms being generally negatively affected and warm-water organisms positively affected. However, detected range shifts are based on findings from a relatively low number of taxonomic groups, samples from few freshwater ecosystems, and few regions. The lack of a wider knowledge hinders predictions of the responses of much of freshwater biodiversity to climate change and other major anthropogenic stressors. Due to the lack of detailed distributional information for most freshwater taxonomic groups and the absence of distribution-climate models, future studies should aim at furthering our knowledge about these aspects of the ecology of freshwater organisms. Such information is not only important with regard to the basic ecological issue of predicting the responses of freshwater species to climate variables, but also when assessing the applied issue of the capacity of protected areas to accommodate future changes in the distributions of freshwater species. This is a huge challenge, because most current protected areas have not been delineated based on the requirements of freshwater organisms. Thus, the requirements of freshwater organisms should be taken into account in the future delineation of protected areas and in the estimation of the degree to which protected areas accommodate freshwater biodiversity in the changing climate and associated environmental changes. [source]

Association of a single nucleotide polymorphism in neuronal acetylcholine receptor subunit alpha 5 (CHRNA5) with smoking status and with ,pleasurable buzz' during early experimentation with smoking

ADDICTION, Issue 9 2008
Richard Sherva
ABSTRACT Aims To extend the previously identified association between a single nucleotide polymorphism (SNP) in neuronal acetylcholine receptor subunit alpha-5 (CHRNA5) and nicotine dependence to current smoking and initial smoking-experience phenotypes. Design, setting, participants Case,control association study with a community-based sample, comprising 363 Caucasians and 72 African Americans (203 cases, 232 controls). Measurements Cases had smoked , five cigarettes/day for , 5 years and had smoked at their current rate for the past 6 months. Controls had smoked between one and 100 cigarettes in their life-time, but never regularly. Participants also rated, retrospectively, pleasurable and displeasurable sensations experienced when they first smoked. We tested for associations between smoking phenotypes and the top 25 SNPs tested for association with nicotine dependence in a previous study. Findings A non-synonymous coding SNP in CHRNA5, rs16969968, was associated with case status [odds ratio (OR) = 1.5, P = 0.01] and, in Caucasians, with experiencing a pleasurable rush or buzz during the first cigarette (OR = 1.6, P = 0.01); these sensations were associated highly with current smoking (OR = 8.2, P = 0.0001). Conclusions We replicated the observation that the minor allele of rs16969968 affects smoking behavior, and extended these findings to sensitivity to smoking effects upon experimentation. While the ability to test genetic associations was limited by sample size, the polymorphism in the CHRNA5 subunit was shown to be associated significantly with enhanced pleasurable responses to initial cigarettes in regular smokers in an a priori test. The findings suggest that phenotypes related to subjective experiences upon smoking experimentation may mediate the development of nicotine dependence. [source]

Long-Cycle Electrochemical Behavior of Multiwall Carbon Nanotubes Synthesized on Stainless Steel in Li Ion Batteries

Charan Masarapu
Abstract Carbon nanotubes (CNTs) are considered to be excellent candidates for high performance electrode materials in Li ion batteries. The nanometer-sized pore structures of CNTs can provide the hosting sites for storing large numbers of Li ions. A short diffusion distance for the Li ions may bring about a high discharge rate. The long-cycle performance of aligned multiwalled carbon nanotubes (MWNTs) directly synthesized on stainless-steel foil as an anode material in lithium battery is demonstrated. An increase in the specific capacity with an increase in the cycle number is observed. Starting at a value of 132,mA hg,1 in the first cycle at a current rate of 1,C, the specific capacity increased about 250% to a value of 460,mA hg,1 after 1,200 cycles. This is an unusual but a welcoming behavior for battery applications. It is found that the morphology of the MWNTs with structural and surface defects and the stainless-steel substrate play an important role in enhancing the capacity during the cycling process. [source]

Announcement effects on exchange rates

Mikael Bask
Abstract An asset pricing model for exchange rate determination is presented, where technical analysis in currency trade is incorporated in the form of a moving average technique. As a result, the model has jmax+1 rational expectations equilibria (REE), where jmax is large, since jmax past exchange rates affect the current rate due to technical analysis. There is, however, a unique REE that is economically relevant, and focusing on this REE, it is shown that the exchange rate is much more sensitive to a change in money supply than when technical analysis is absent in currency trade. This result is important since it sheds light on the so-called exchange rate disconnect puzzle in international finance. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Fabrication and properties of crosslinked poly(propylene carbonate maleate) gel polymer electrolyte for lithium-ion battery

Xiaoyuan Yu
Abstract The poly(propylene carbonate maleate) (PPCMA) was synthesized by the terpolymerization of carbon dioxide, propylene oxide, and maleic anhydride. The PPCMA polymer can be readily crosslinked using dicumyl peroxide (DCP) as crosslinking agent and then actived by absorbing liquid electrolyte to fabricate a novel PPCMA gel polymer electrolyte for lithium-ion battery. The thermal performance, electrolyte uptake, swelling ratio, ionic conductivity, and lithium ion transference number of the crosslinked PPCMA were then investigated. The results show that the Tg and the thermal stability increase, but the absorbing and swelling rates decrease with increasing DCP amount. The ionic conductivity of the PPCMA gel polymer electrolyte firstly increases and then decreases with increasing DCP ratio. The ionic conductivity of the PPCMA gel polymer electrolyte with 1.2 wt % of DCP reaches the maximum value of 8.43 × 10,3 S cm,1 at room temperature and 1.42 × 10,2 S cm,1 at 50°C. The lithium ion transference number of PPCMA gel polymer electrolyte is 0.42. The charge/discharge tests of the Li/PPCMA GPE/LiNi1/3Co1/3Mn1/3O2 cell were evaluated at a current rate of 0.1C and in voltage range of 2.8,4.2 V at room temperature. The results show that the initial discharge capacity of Li/PPCMA GPE/LiNi1/3Co1/3Mn1/3 O2 cell is 115.3 mAh g,1. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Prevalence of Occult Bacteremia in Children Aged 3 to 36 Months Presenting to the Emergency Department with Fever in the Postpneumococcal Conjugate Vaccine Era

Matthew Wilkinson MD
Abstract Objectives:, The goal of this study was to identify the prevalence of occult bacteremia (OB) in well-appearing, previously healthy children aged 3 to 36 months who present to the emergency department (ED) with fever without source in the post,pneumococcal conjugate vaccine (PCV) era. Methods:, This was a retrospective cohort study of children presenting to an urban pediatric ED between July 1, 2004, and June 30, 2007. Children were included if they were aged 3 to 36 months, febrile, and previously healthy; had no source of infection on examination; had a blood culture drawn; and were discharged from the ED. Outcome measures were rates of OB and contaminant rates. Results:, A total of 8,408 children met all inclusion criteria. There were 21 true-positives, yielding an OB rate of 0.25% (95% confidence interval [CI] = 0.16% to 0.37%). There were 159 contaminant cultures yielding a contaminant rate of 1.89% (95% CI = 1.61% to 2.19%), or a ratio of 7.6 contaminants for each true-positive. There were 14 included patients who grew Streptococcus pneumoniae from the blood, for a rate of 0.17% (95% CI = 0.09% to 0.27%). Conclusions:, Given the current rate of OB in the post-PCV era, it may no longer be cost-effective to send blood cultures on well-appearing, previously healthy children aged 3 to 36 months who have fever without source. [source]

Habitat Loss and Extinction in the Hotspots of Biodiversity

Thomas M. Brooks
None of these hotspots have more than one-third of their pristine habitat remaining. Historically, they covered 12% of the land's surface, but today their intact habitat covers only 1.4% of the land. As a result of this habitat loss, we expect many of the hotspot endemics to have either become extinct or,because much of the habitat loss is recent,to be threatened with extinction. We used World Conservation Union [ IUCN ] Red Lists to test this expectation. Overall, between one-half and two-thirds of all threatened plants and 57% of all threatened terrestrial vertebrates are hotspot endemics. For birds and mammals, in general, predictions of extinction in the hotspots based on habitat loss match numbers of species independently judged extinct or threatened. In two classes of hotspots the match is not as close. On oceanic islands, habitat loss underestimates extinction because introduced species have driven extinctions beyond those caused by habitat loss on these islands. In large hotspots, conversely, habitat loss overestimates extinction, suggesting scale dependence (this effect is also apparent for plants). For reptiles, amphibians, and plants, many fewer hotspot endemics are considered threatened or extinct than we would expect based on habitat loss. This mismatch is small in temperate hotspots, however, suggesting that many threatened endemic species in the poorly known tropical hotspots have yet to be included on the IUCN Red Lists. We then asked in which hotspots the consequences of further habitat loss (either absolute or given current rates of deforestation) would be most serious. Our results suggest that the Eastern Arc and Coastal Forests of Tanzania-Kenya, Philippines, and Polynesia-Micronesia can least afford to lose more habitat and that, if current deforestation rates continue, the Caribbean, Tropical Andes, Philippines, Mesoamerica, Sundaland, Indo-Burma, Madagascar, and Chocó,Darién,Western Ecuador will lose the most species in the near future. Without urgent conservation intervention, we face mass extinctions in the hotspots. Resumen: Casi la mitad del total de plantas vasculares del mundo y un tercio de los vertebrados terrestres son endémicos en 25 "áreas críticas" para la biodiversidad, cada una de las cuales tiene por lo menos 1500 especies de plantas endémicas. En ninguno de estos sitios permanece más de un tercio de su hábitat prístino. Históricamente, cubrían 12% de la superficie terrestre, pero en la actualidad su hábitat intacto cubre solo 1.4% del terreno. Como resultado de esta pérdida de hábitat esperamos que muchas de las especies endémicas a estos sitios estén extintas o , porque la pérdida de hábitat es reciente , se encuentren amenazadas de extinción. Utilizamos Listas Rojas de UICN para comprobar esta predicción. En general, entre la mitad y dos tercios de las plantas amenazadas y el 57% de los vertebrados terrestres amenazados son endémicos de áreas críticas para la biodiversidad. Para aves y mamíferos en general, las predicciones de extinción en las áreas críticas para la biodiversidad, basadas en la pérdida de hábitat, coinciden con el número de especies consideradas extintas o amenazadas independientemente. En dos clases de áreas críticas para la biodiversidad la coincidencia no es muy grande. En islas oceánicas, la pérdida de hábitat subestima la extinción porque las especies introducidas han causado más extinciones que las producidas por la reducción del hábitat. Por lo contrario, la pérdida de hábitat sobrestima la extinción en áreas críticas para la biodiversidad extensas, lo que sugiere una dependencia de escala (este efecto también es aparente para plantas). Para reptiles, anfibios y plantas mucho menos especies endémicas son consideradas amenazadas o extintas por pérdida de hábitat. Sin embargo, esta discordancia es pequeña en áreas críticas para la biodiversidad en zonas templadas templadas, lo que sugiere que muchas especies endémicas amenazadas en las poco conocidas áreas críticas para la biodiversidad en zonas tropicales aun están por incluirse en las Listas Rojas. Posteriormente nos preguntamos en que áreas críticas para la biodiversidad serían más serias las consecuencias de una mayor pérdida de hábitat (absoluta o con las tasas actuales de deforestación). Nuestros resultados sugieren que el Arco Oriental y los Bosques Costeros de Tanzania/Kenia, Filipinas, Polinesia/Micronesia no pueden soportar mayores pérdidas y que, si continúan las tasas de deforestación actuales, el Caribe, Andes Tropicales, Filipinas, Mesoamérica, Sundaland, Indo-Burma, Madagascar y Chocó/Darién/Ecuador Occidental perderán más especies en el futuro. Sin acciones urgentes de conservación, habrá extinciones masivas en las áreas críticas para la biodiversidad. [source]

Prospects and Challenges for Growth and Poverty Reduction in Asia

John Humphrey
The extent of poverty reduction in Asia by 2015 will depend upon two linked issues: sustaining the current rates of economic growth and avoiding increases in income inequality. Rapid growth over the past 15 years has itself created three challenges for its continuation: inadequate infrastructure; energy shortages and insecurity; and depletion of natural resources and environmental degradation. The ways in which these problems are addressed will have impacts not only on growth but also on inequality, requiring policy interventions at multiple levels, having implications for governance at multiple levels, and involving the development of new partnerships within the region and beyond. [source]

Applying climatically associated species pools to the modelling of compositional change in tropical montane forests

GLOBAL ECOLOGY, Issue 2 2008
Duncan J. Golicher
ABSTRACT Aim, Predictive species distribution modelling is a useful tool for extracting the maximum amount of information from biological collections and floristic inventories. However, in many tropical regions records are only available from a small number of sites. This can limit the application of predictive modelling, particularly in the case of rare and endangered species. We aim to address this problem by developing a methodology for defining and mapping species pools associated with climatic variables in order to investigate potential species turnover and regional species loss under climate change scenarios combined with anthropogenic disturbance. Location, The study covered an area of 6800 km2 in the highlands of Chiapas, southern Mexico. Methods, We derived climatically associated species pools from floristic inventory data using multivariate analysis combined with spatially explicit discriminant analysis. We then produced predictive maps of the distribution of tree species pools using data derived from 451 inventory plots. After validating the predictive power of potential distributions against an independent historical data set consisting of 3105 botanical collections, we investigated potential changes in the distribution of tree species resulting from forest disturbance and climate change. Results, Two species pools, associated with moist and cool climatic conditions, were identified as being particularly threatened by both climate change and ongoing anthropogenic disturbance. A change in climate consistent with low-emission scenarios of general circulation models was shown to be sufficient to cause major changes in equilibrium forest composition within 50 years. The same species pools were also found to be suffering the fastest current rates of deforestation and internal forest disturbance. Disturbance and deforestation, in combination with climate change, threaten the regional distributions of five tree species listed as endangered by the IUCN. These include the endemic species Magnolia sharpii Miranda and Wimmeria montana Lundell. Eleven vulnerable species and 34 species requiring late successional conditions for their regeneration could also be threatened. Main conclusions, Climatically associated species pools can be derived from floristic inventory data available for tropical regions using methods based on multivariate analysis even when data limitations prevent effective application of individual species modelling. Potential consequences of climate change and anthropogenic disturbance on the species diversity of montane tropical forests in our study region are clearly demonstrated by the method. [source]

Source Zone Natural Attenuation at Petroleum Hydrocarbon Spill Sites,I: Site-Specific Assessment Approach

Paul Johnson
This work focuses on the site-specific assessment of source zone natural attenuation (SZNA) at petroleum spill sites, including the confirmation that SZNA is occurring, estimation of current SZNA rates, and anticipation of SZNA impact on future ground water quality. The approach anticipates that decision makers will be interested in answers to the following questions: (1) Is SZNA occurring and what processes are contributing to SZNA? (2) What are the current rates of mass removal associated with SZNA? (3) What are the longer-term implications of SZNA for ground water impacts? and (4) Are the SZNA processes and rates sustainable? This approach is a data-driven, macroscopic, multiple-lines-of-evidence approach and is therefore consistent with the 2000 National Research Council's recommendations and complementary to existing dissolved plume natural attenuation protocols and recent modeling work published by others. While this work is easily generalized, the discussion emphasizes SZNA assessment at petroleum hydrocarbon spill sites. The approach includes three basic levels of data collection and data reduction (Group I, Group II, and Group III). Group I measurements provide evidence that SZNA is occurring. Group II measurements include additional information necessary to estimate current SZNA rates, and group III measurements are focused on evaluating the long-term implications of SZNA for source zone characteristics and ground water quality. This paper presents the generalized site-specific SZNA assessment approach and then focuses on the interpretation of Group II data. Companion papers illustrate its application to source zones at a former oil field in California. [source]

Application of Markov chain Monte Carlo methods to projecting cancer incidence and mortality

Isabelle Bray
Summary. Projections based on incidence and mortality data collected by cancer registries are important for estimating current rates in the short term, and public health planning in the longer term. Classical approaches are dependent on questionable parametric assumptions. We implement a Bayesian age,period,cohort model, allowing the inclusion of prior belief concerning the smoothness of the parameters. The model is described by a directed acyclic graph. Computations are carried out by using Markov chain Monte Carlo methods (implemented in BUGS) in which the degree of smoothing is learnt from the data. Results and convergence diagnostics are discussed for an exemplary data set. We then compare the Bayesian projections with other methods in a range of situations to demonstrate its flexibility and robustness. [source]

Seizures in children after kidney transplantation: Has the risk changed and can we predict who is at greatest risk?

Lorie D. Hamiwka
Abstract:, Children undergoing kidney transplantation are at increased risk for symptomatic seizures with a previously reported incidence of approximately 20%. Little data exist to help predict which children may be at risk. We retrospectively reviewed all children who underwent kidney transplantation evaluation at our center between October 1993 and August 2007 and identified 41 children who had an EEG prior to transplant. Demographic data as well as the following were collected: immunosuppressive medications, developmental status, history of seizures, family history of seizures, post-transplant seizures and EEG results. EEGs were classified as normal or abnormal. Prior to transplantation, one child had a history of febrile seizures and six experienced afebrile seizures. Nine (22%) children identified had an abnormal EEG prior to transplant. In eight cases the EEG was non-epileptiform and in one case was epileptiform. Abnormal EEGs did not correlate with a family history of seizures. Delayed development was noted in seven children and was not associated with an epileptiform EEG. Following kidney transplantation, no child experienced a seizure. Our single center study suggests that current rates of seizures following kidney transplantation are lower than previously reported and that routine EEG as part of the pretransplant evaluation in these children is of limited use to predict those at risk. [source]

Sexual Health Among U.S. Black and Hispanic Men and Women: A Nationally Representative Study

Brian Dodge PhD
ABSTRACT Introduction., Little is known about the prevalence of sexual behaviors among the black and Hispanic populations in the United States outside the context of sexual risk and disease transmission in "high-risk" samples. Aim., This study sought to establish current rates of sexual behaviors, sexual health care practices (i.e., experiences with testing and diagnosis of sexually transmitted infections [STIs]), and condom use in a probability sample of black and Hispanic adult men and women in the United States. Main Outcome Measures., Sexual behaviors including solo masturbation, partnered masturbation, receiving oral sex and giving oral sex, vaginal intercourse, and anal intercourse were assessed. Self-reported rates of HIV and other STI testing, and self-reported history of STI diagnosis were examined. Also assessed were rates of condom use during most recent and past 10 vaginal intercourse events. Methods., Data from a probability sample of 1246 black and Hispanic adults were analyzed to explore sexual behaviors, condom use, and STI testing and diagnosis trends. Results., Masturbation, oral sex, and vaginal intercourse were prevalent among black and Hispanic men and women throughout the life course. Anal intercourse and same-gender sexual activities were less common. Self-reported rates of HIV testing were relatively high but varied by gender across age groups. Similarly, rates of testing for other STI were high and differed by gender across age groups. Overall rates of condom use among black and Hispanic men and women were relatively high and did not appear to be related to a variety of situational factors including location of sexual encounter, relationship status, other contraceptive use, and substance use during sexual activity. Conclusion., These data provide a foundation for understanding diverse sexual behaviors, sexual health-care practices, and condom use among the general population of black and Hispanic men and women in the United States. Dodge B, Reece M, Herbenick D, Schick V, Sanders SA, and Fortenberry JD. Sexual health among U.S. black and Hispanic men and women: a nationally representative study. J Sex Med 2010;7(suppl 5):330,345. [source]