761 research outputs found
Melting curve and phase diagram of vanadium under high-pressure and high-temperature conditions
We report a combined experimental and theoretical study of the melting curve
and the structural behavior of vanadium under extreme pressure and temperature. We
performed powder x-ray diffraction experiments up to 120 GPa and 4000 K, determining
the phase boundary of the bcc-to-rhombohedral transition and melting temperatures at
different pressures. Melting temperatures have also been established from the observation
of temperature plateaus during laser heating, and the results from the density-functional
theory calculations. Results obtained from our experiments and calculations are fully
consistent and lead to an accurate determination of the melting curve of vanadium. These
results are discussed in comparison with previous studies. The melting temperatures
determined in this study are higher than those previously obtained using the speckle
method, but also considerably lower than those obtained from shock-wave experiments and
linear muffin-tin orbital calculations. Finally, a high-pressure high-temperature equation of
state up to 120 GPa and 2800 K has also been determined
Influenza nucleoprotein delivered with aluminium salts protects mice from an influenza virus that expresses an altered nucleoprotein sequence
Influenza virus poses a difficult challenge for protective immunity. This virus is adept at altering its surface proteins, the proteins that are the targets of neutralizing antibody. Consequently, each year a new vaccine must be developed to combat the current recirculating strains. A universal influenza vaccine that primes specific memory cells that recognise conserved parts of the virus could prove to be effective against both annual influenza variants and newly emergent potentially pandemic strains. Such a vaccine will have to contain a safe and effective adjuvant that can be used in individuals of all ages. We examine protection from viral challenge in mice vaccinated with the nucleoprotein from the PR8 strain of influenza A, a protein that is highly conserved across viral subtypes. Vaccination with nucleoprotein delivered with a universally used and safe adjuvant, composed of insoluble aluminium salts, provides protection against viruses that either express the same or an altered version of nucleoprotein. This protection correlated with the presence of nucleoprotein specific CD8 T cells in the lungs of infected animals at early time points after infection. In contrast, immunization with NP delivered with alum and the detoxified LPS adjuvant, monophosphoryl lipid A, provided some protection to the homologous viral strain but no protection against infection by influenza expressing a variant nucleoprotein. Together, these data point towards a vaccine solution for all influenza A subtypes
Equation of state and high-pressure/high-temperature phase diagram of magnesium
The phase diagram of magnesium has been investigated to 211 GPa at 300 K, and to 105 GPa at 4500 K, by using a combination of x-ray diffraction and resistive and laser heating. The ambient pressure hcp structure is found to start transforming to the bcc structure at โผ45 GPa, with a large region of phase-coexistence that becomes smaller at higher temperatures. The bcc phase is stable to the highest pressures reached. The hcp-bcc phase boundary has been studied on both compression and decompression, and its slope is found to be negative and steeper than calculations have previously predicted. The laser-heating studies extend the melting curve of magnesium to 105 GPa and suggest that, at the highest pressures, the melting temperature increases more rapidly with pressure than previously reported. Finally, we observe some evidence of a new phase in the region of 10 GPa and 1200 K, where previous studies have reported a double-hexagonal-close-packed (dhcp) phase. However, the additional diffraction peaks we observe cannot be accounted for by the dhcp phase alone
Lack of basic and luxury goods and health-related dysfunction in older persons; Findings from the longitudinal SMILE study
<p>Abstract</p> <p>Background</p> <p>More so than the traditional socioeconomic indicators, such as education and income, wealth reflects the accumulation of resources and makes socioeconomic ranking manifest and explicitly visible to the outside world. While the lack of basic goods, such as a refrigerator, may affect health directly, via biological pathways, the lack of luxury goods, such as an LCD television, may affect health indirectly through psychosocial mechanisms. We set out to examine, firstly, the relevance of both basic and luxury goods in explaining health-related dysfunction in older persons, and, secondly, the extent to which these associations are independent of traditional socioeconomic indicators.</p> <p>Methods</p> <p>Cross-sectional and longitudinal data from 2067 men and women aged 55 years and older who participated in the Study on Medical Information and Lifestyles Eindhoven (SMILE) were gathered. Logistic regression analyses were used to study the relation between a lack of basic and luxury goods and health-related function, assessed with two sub-domains of the SF-36.</p> <p>Results</p> <p>The lack of basic goods was closely related to incident physical (OR = 2.32) and mental (OR = 2.12) dysfunction, even when the traditional measures of socioeconomic status, i.e. education or income, were taken into account. Cross-sectional analyses, in which basic and luxury goods were compared, showed that the lack of basic goods was strongly associated with mental dysfunction. Lack of luxury goods was, however, not related to dysfunction.</p> <p>Conclusion</p> <p>Even in a relatively wealthy country like the Netherlands, the lack of certain basic goods is not uncommon. More importantly, lack of basic goods, as an indicator of wealth, was strongly related to health-related dysfunction also when traditional measures of socioeconomic status were taken into account. In contrast, no effects of luxury goods on physical or mental dysfunction were found. Future longitudinal research is necessary to clarify the precise mechanisms underlying these effects.</p
Capturing egocentric biases in reference reuse during collaborative dialogue
Words that are produced aloudโand especially self-produced onesโare remembered better than words that are not, a phenomenon labeled the production effect in the field of memory research. Two experiments were conducted to determine whether this effect can be generalized to dialogue, and how it might affect dialogue management. Triads (Exp. 1) or dyads (Exp. 2) of participants interacted to perform a collaborative task. Analyzing reference reuse during the interaction revealed that the participants were more likely to reuse the references that they had presented themselves, on the one hand, and those that had been accepted through verbatim repetition, on the other. Analyzing reference recall suggested that the greater accessibility of self-presented references was only transient. Moreover, among partner-presented references, those discussed while the participant had actively taken part in the conversation were more likely to be recalled than those discussed while the participant had been inactive. These results contribute to a better understanding of how individual memory processes might contribute to collaborative dialogue
Community based needs assessment in an urban area; A participatory action research project
<p>Abstract</p> <p>Background</p> <p>Community assessment is a core function of public health. In such assessments, a commitment to community participation and empowerment is at the heart of the WHO European Healthy Cities Network, reflecting its origins in health for all and the Ottawa Charter for Health Promotion. This study employs a participation and empowerment plan in order to conduct community assessment.</p> <p>Methods</p> <p>The method of participatory action research (PAR) was used. The study was carried out in an area of high socio-economic deprivation in Ardabil, a city in the northwest of Iran, which is currently served by a branch of the Social Development Center (SDC). The steering committee of the project was formed by some university faculty members, health officials and delegates form Farhikhteh non-governmental organization and representatives from twelve blocks or districts of the community. Then, the representatives were trained and then conducted focus groups in their block. The focus group findings informed the development of the questionnaire. About six hundred households were surveyed and study questionnaires were completed either during face-to-face interviews by the research team (in case of illiteracy) or via self-completion. The primary question for the residents was: 'what is the most important health problem in your community? Each health problem identified by the community was weighted based on the frequency it was selected on the survey, and steering committee perception of the problem's seriousness, urgency, solvability, and financial load.</p> <p>Results</p> <p>The main problems of the area appeared to be <it>the asphalt problem</it>, <it>lack of easy access to medical centers</it>, <it>addiction among relatives </it>and <it>unemployment of youth</it>. High participation rates of community members in the steering committee and survey suggest that the PAR approach was greatly appreciated by the community and that problems identified through this research truly reflect community opinion.</p> <p>Conclusions</p> <p>Participatory action research is an effective method for community assessments. However, researchers must rigorously embrace principles of mutual cooperation, respect for public ideas, and a robust belief in community empowerment in order to pave the way for responsible and active citizen participation in the various stages of research.</p
The genome sequence of <i>Trypanosoma brucei gambiense</i>, causative agent of chronic Human African Trypanosomiasis
<p><b>Background:</b> <i>Trypanosoma brucei gambiense</i> is the causative agent of chronic Human African Trypanosomiasis or sleeping sickness, a disease endemic across often poor and rural areas of Western and Central Africa. We have previously published the genome sequence of a <i>T. b. brucei</i> isolate, and have now employed a comparative genomics approach to understand the scale of genomic variation between <i>T. b. gambiense</i> and the reference genome. We sought to identify features that were uniquely associated with <i>T. b. gambiense</i> and its ability to infect humans.</p>
<p><b>Methods and findings:</b> An improved high-quality draft genome sequence for the group 1 <i>T. b. gambiense</i> DAL 972 isolate was produced using a whole-genome shotgun strategy. Comparison with <i>T. b. brucei</i> showed that sequence identity averages 99.2% in coding regions, and gene order is largely collinear. However, variation associated with segmental duplications and tandem gene arrays suggests some reduction of functional repertoire in <i>T. b. gambiense</i> DAL 972. A comparison of the variant surface glycoproteins (VSG) in <i>T. b. brucei</i> with all <i>T. b. gambiense</i> sequence reads showed that the essential structural repertoire of VSG domains is conserved across <i>T. brucei</i>.</p>
<p><b>Conclusions:</b> This study provides the first estimate of intraspecific genomic variation within <i>T. brucei</i>, and so has important consequences for future population genomics studies. We have shown that the <i>T. b. gambiense</i> genome corresponds closely with the reference, which should therefore be an effective scaffold for any <i>T. brucei</i> genome sequence data. As VSG repertoire is also well conserved, it may be feasible to describe the total diversity of variant antigens. While we describe several as yet uncharacterized gene families with predicted cell surface roles that were expanded in number in <i>T. b. brucei</i>, no <i>T. b. gambiense</i>-specific gene was identified outside of the subtelomeres that could explain the ability to infect humans.</p>
QRTEngine: An easy solution for running online reaction time experiments using Qualtrics
Performing online behavioral research is gaining increased popularity among researchers in psychological and cognitive science. However, the currently available methods for conducting online reaction time experiments are often complicated and typically require advanced technical skills. In this article, we introduce the Qualtrics Reaction Time Engine (QRTEngine), an open-source JavaScript engine that can be embedded in the online survey development environment Qualtrics. The QRTEngine can be used to easily develop browser-based online reaction time experiments with accurate timing within current browser capabilities, and it requires only minimal programming skills. After introducing the QRTEngine, we briefly discuss how to create and distribute a Stroop task. Next, we describe a study in which we investigated the timing accuracy of the engine under different processor loads using external chronometry. Finally, we show that the QRTEngine can be used to reproduce classic behavioral effects in three reaction time paradigms: a Stroop task, an attentional blink task, and a masked-priming task. These findings demonstrate that QRTEngine can be used as a tool for conducting online behavioral research even when this requires accurate stimulus presentation times
Cisplatin-induced emesis: systematic review and meta-analysis of the ferret model and the effects of 5-HT3 receptor antagonists
PURPOSE: The ferret cisplatin emesis model has been used for ~30ย years and enabled identification of clinically used anti-emetics. We provide an objective assessment of this model including efficacy of 5-HT(3) receptor antagonists to assess its translational validity. METHODS: A systematic review identified available evidence and was used to perform meta-analyses. RESULTS: Of 182 potentially relevant publications, 115 reported cisplatin-induced emesis in ferrets and 68 were included in the analysis. The majority (nย =ย 53) used a 10ย mgย kg(โ1) dose to induce acute emesis, which peaked after 2ย h. More recent studies (nย =ย 11) also used 5ย mgย kg(โ1), which induced a biphasic response peaking at 12ย h and 48ย h. Overall, 5-HT(3) receptor antagonists reduced cisplatin (5ย mgย kg(โ1)) emesis by 68% (45โ91%) during the acute phase (day 1) and by 67% (48โ86%) and 53% (38โ68%, all Pย <ย 0.001), during the delayed phase (days 2, 3). In an analysis focused on the acute phase, the efficacy of ondansetron was dependent on the dosage and observation period but not on the dose of cisplatin. CONCLUSION: Our analysis enabled novel findings to be extracted from the literature including factors which may impact on the applicability of preclinical results to humans. It reveals that the efficacy of ondansetron is similar against low and high doses of cisplatin. Additionally, we showed that 5-HT(3) receptor antagonists have a similar efficacy during acute and delayed emesis, which provides a novel insight into the pharmacology of delayed emesis in the ferret
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