42 research outputs found
Neutrino emission from dense matter, and neutron star thermal evolution
A brief review is given of neutrino emission processes in dense matter, with particular emphasis on recent developments. These include direct Urca processes for nucleons and hyperons, which can give rise to rapid energy loss from the stellar core without exotic matter, and the effect of band structure on neutrino bremsstrahlung from electrons in the crust, which results in much lower energy losses by this process than had previously been estimated
The Phylogenetics and Ecology of the Orthopoxviruses Endemic to North America
The data presented herein support the North American orthopoxviruses (NA OPXV) in a sister relationship to all other currently described Orthopoxvirus (OPXV) species. This phylogenetic analysis reaffirms the identification of the NA OPXV as close relatives of “Old World” (Eurasian and African) OPXV and presents high support for deeper nodes within the Chordopoxvirinae family. The natural reservoir host(s) for many of the described OPXV species remains unknown although a clear virus-host association exists between the genus OPXV and several mammalian taxa. The hypothesized host associations and the deep divergence of the OPXV/NA OPXV clades depicted in this study may reflect the divergence patterns of the mammalian faunas of the Old and New World and reflect a more ancient presence of OPXV on what are now the American continents. Genes from the central region of the poxvirus genome are generally more conserved than genes from either end of the linear genome due to functional constraints imposed on viral replication abilities. The relatively slower evolution of these genes may more accurately reflect the deeper history among the poxvirus group, allowing for robust placement of the NA OPXV within Chordopoxvirinae. Sequence data for nine genes were compiled from three NA OPXV strains plus an additional 50 genomes collected from Genbank. The current, gene sequence based phylogenetic analysis reaffirms the identification of the NA OPXV as the nearest relatives of “Old World” OPXV and presents high support for deeper nodes within the Chordopoxvirinae family. Additionally, the substantial genetic distances that separate the currently described NA OPXV species indicate that it is likely that many more undescribed OPXV/NA OPXV species may be circulating among wild animals in North America
Mutualism and Adaptive Divergence: Co-Invasion of a Heterogeneous Grassland by an Exotic Legume-Rhizobium Symbiosis
Species interactions play a critical role in biological invasions. For example, exotic plant and microbe mutualists can facilitate each other's spread as they co-invade novel ranges. Environmental context may influence the effect of mutualisms on invasions in heterogeneous environments, however these effects are poorly understood. We examined the mutualism between the legume, Medicago polymorpha, and the rhizobium, Ensifer medicae, which have both invaded California grasslands. Many of these invaded grasslands are composed of a patchwork of harsh serpentine and relatively benign non-serpentine soils. We grew legume genotypes collected from serpentine or non-serpentine soil in both types of soil in combination with rhizobium genotypes from serpentine or non-serpentine soils and in the absence of rhizobia. Legumes invested more strongly in the mutualism in the home soil type and trends in fitness suggested that this ecotypic divergence was adaptive. Serpentine legumes had greater allocation to symbiotic root nodules in serpentine soil than did non-serpentine legumes and non-serpentine legumes had greater allocation to nodules in non-serpentine soil than did serpentine legumes. Therefore, this invasive legume has undergone the rapid evolution of divergence for soil-specific investment in the mutualism. Contrary to theoretical expectations, the mutualism was less beneficial for legumes grown on the stressful serpentine soil than on the non-serpentine soil, possibly due to the inhibitory effects of serpentine on the benefits derived from the interaction. The soil-specific ability to allocate to a robust microbial mutualism may be a critical, and previously overlooked, adaptation for plants adapting to heterogeneous environments during invasion
Diversity, Loss, and Gain of Malaria Parasites in a Globally Invasive Bird
Invasive species can displace natives, and thus identifying the traits that make aliens successful is crucial for predicting and preventing biodiversity loss. Pathogens may play an important role in the invasive process, facilitating colonization of their hosts in new continents and islands. According to the Novel Weapon Hypothesis, colonizers may out-compete local native species by bringing with them novel pathogens to which native species are not adapted. In contrast, the Enemy Release Hypothesis suggests that flourishing colonizers are successful because they have left their pathogens behind. To assess the role of avian malaria and related haemosporidian parasites in the global spread of a common invasive bird, we examined the prevalence and genetic diversity of haemosporidian parasites (order Haemosporida, genera Plasmodium and Haemoproteus) infecting house sparrows (Passer domesticus). We sampled house sparrows (N = 1820) from 58 locations on 6 continents. All the samples were tested using PCR-based methods; blood films from the PCR-positive birds were examined microscopically to identify parasite species. The results show that haemosporidian parasites in the house sparrows' native range are replaced by species from local host-generalist parasite fauna in the alien environments of North and South America. Furthermore, sparrows in colonized regions displayed a lower diversity and prevalence of parasite infections. Because the house sparrow lost its native parasites when colonizing the American continents, the release from these natural enemies may have facilitated its invasion in the last two centuries. Our findings therefore reject the Novel Weapon Hypothesis and are concordant with the Enemy Release Hypothesis
European COMPARative Effectiveness research on blended Depression treatment versus treatment-as-usual (E-COMPARED): study protocol for a randomized controlled, non-inferiority trial in eight European countries
Implementing training and support, financial reimbursement, and referral to an internet-based brief advice program to improve the early identification of hazardous and harmful alcohol consumption in primary care (ODHIN): study protocol for a cluster randomized factorial trial
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118617.pdf (publisher's version ) (Open Access)BACKGROUND: The European level of alcohol consumption, and the subsequent burden of disease, is high compared to the rest of the world. While screening and brief interventions in primary healthcare are cost-effective, in most countries they have hardly been implemented in routine primary healthcare. In this study, we aim to examine the effectiveness and efficiency of three implementation interventions that have been chosen to address key barriers for improvement: training and support to address lack of knowledge and motivation in healthcare providers; financial reimbursement to compensate the time investment; and internet-based counselling to reduce workload for primary care providers. METHODS/DESIGN: In a cluster randomized factorial trial, data from Catalan, English, Netherlands, Polish, and Swedish primary healthcare units will be collected on screening and brief advice rates for hazardous and harmful alcohol consumption. The three implementation strategies will be provided separately and in combination in a total of seven intervention groups and compared with a treatment as usual control group. Screening and brief intervention activities will be measured at baseline, during 12 weeks and after six months. Process measures include health professionals' role security and therapeutic commitment of the participating providers (SAAPPQ questionnaire). A total of 120 primary healthcare units will be included, equally distributed over the five countries. Both intention to treat and per protocol analyses are planned to determine intervention effectiveness, using random coefficient regression modelling. DISCUSSION: Effective interventions to implement screening and brief interventions for hazardous alcohol use are urgently required. This international multi-centre trial will provide evidence to guide decision makers
The effectiveness of a web-based brief alcohol intervention in reducing heavy drinking among adolescents aged 15 to 20 years with a low educational background: Study protocol for a randomized controlled trial
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102984.pdf (publisher's version ) (Open Access)Background: The serious negative health consequences of heavy drinking among adolescents is cause for concern, especially among adolescents aged 15 to 20 years with a low educational background. In the Netherlands, there is a lack of alcohol prevention programs directed to the drinking patterns of this specific target group. The study described in this protocol will test the effectiveness of a web-based brief alcohol intervention that aims to reduce alcohol use among heavy drinking adolescents aged 15 to 20 years with a low educational background. Methods/design: The effectiveness of the What Do You Drink (WDYD) web-based brief alcohol intervention will be tested among 750 low-educated, heavy drinking adolescents. It will use a two-arm parallel group cluster randomized controlled trial. Classes of adolescents from educational institutions will be randomly assigned to either the experimental (n = 375: web-based brief alcohol intervention) or control condition (n = 375: no intervention). Primary outcomes measures will be: 1) the percentage of participants who drink within the normative limits of the Dutch National Health Council for low-risk drinking, 2) reductions in mean weekly alcohol consumption, and 3) frequency of binge drinking. The secondary outcome measures include the alcohol-related cognitions, attitudes, self-efficacy, and subjective norms, which will be measured at baseline and at one and six months after the intervention. Discussion: This study protocol presents the study design of a two-arm parallel-group randomized controlled trial to evaluate the effectiveness of the WDYD web-based brief alcohol intervention. We hypothesized a reduction in mean weekly alcohol consumption and in the frequency of binge drinking in the experimental condition, resulting from the web-based brief alcohol intervention, compared to the control condition.7 p