746 research outputs found

    Three-dimensional reconstruction and visualization of the cerebral cortex in primates

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    We present a prototype interactive application for the direct analysis in three dimensions of the cerebral cortex in primates. The paper provides an overview of the current prototype system and presents the techniques used for reconstructing the cortex shape from data derived from histological sections as well as for rendering it at interactive rates. Results are evaluated by discussing the analysis of the right hemisphere of the brain of a macaque monkey used for neuroanatomical tract-tracing experiments.147-15

    Physiological Costs of Repetitive Courtship Displays in Cockroaches Handicap Locomotor Performance

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    Courtship displays are typically thought to have evolved via female choice, whereby females select mates based on the characteristics of a display that is expected to honestly reflect some aspect of the male’s quality. Honesty is typically enforced by mechanistic costs and constraints that limit the level at which a display can be performed. It is becoming increasingly apparent that these costs may be energetic costs involved in the production of dynamic, often repetitive displays. A female attending to such a display may thus be assessing the physical fitness of a male as an index of his quality. Such assessment would provide information on his current physical quality as well as his ability to carry out other demanding activities, qualities with which a choosy female should want to provision her offspring. In the current study we use courtship interactions in the Cuban burrowing cockroach, Byrsotria fumigata to directly test whether courtship is associated with a signaler’s performance capacity. Males that had produced courtship displays achieved significantly lower speeds and distances in locomotor trials than non-courting control males. We also found that females mated more readily with males that produced a more vigorous display. Thus, males of this species have developed a strategy where they produce a demanding courtship display, while females choose males based on their ability to produce this display. Courtship displays in many taxa often involve dynamic repetitive actions and as such, signals of stamina in courtship may be more widespread than previously thought

    Galactic and Extragalactic Samples of Supernova Remnants: How They Are Identified and What They Tell Us

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    Supernova remnants (SNRs) arise from the interaction between the ejecta of a supernova (SN) explosion and the surrounding circumstellar and interstellar medium. Some SNRs, mostly nearby SNRs, can be studied in great detail. However, to understand SNRs as a whole, large samples of SNRs must be assembled and studied. Here, we describe the radio, optical, and X-ray techniques which have been used to identify and characterize almost 300 Galactic SNRs and more than 1200 extragalactic SNRs. We then discuss which types of SNRs are being found and which are not. We examine the degree to which the luminosity functions, surface-brightness distributions and multi-wavelength comparisons of the samples can be interpreted to determine the class properties of SNRs and describe efforts to establish the type of SN explosion associated with a SNR. We conclude that in order to better understand the class properties of SNRs, it is more important to study (and obtain additional data on) the SNRs in galaxies with extant samples at multiple wavelength bands than it is to obtain samples of SNRs in other galaxiesComment: Final 2016 draft of a chapter in "Handbook of Supernovae" edited by Athem W. Alsabti and Paul Murdin. Final version available at https://doi.org/10.1007/978-3-319-20794-0_90-

    Consumer perceptions of co-branding alliances: Organizational dissimilarity signals and brand fit

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    This study explores how consumers evaluate co-branding alliances between dissimilar partner firms. Customers are well aware that different firms are behind a co-branded product and observe the partner firms’ characteristics. Drawing on signaling theory, we assert that consumers use organizational characteristics as signals in their assessment of brand fit and for their purchasing decisions. Some organizational signals are beyond the control of the co-branding partners or at least they cannot alter them on short notice. We use a quasi-experimental design and test how co-branding partner dissimilarity affects brand fit perception. The results show that co-branding partner dissimilarity in terms of firm size, industry scope, and country-of-origin image negatively affects brand fit perception. Firm age dissimilarity does not exert significant influence. Because brand fit generally fosters a benevolent consumer attitude towards a co-branding alliance, the findings suggest that high partner dissimilarity may reduce overall co-branding alliance performance

    Evaluation of three PCR-based diagnostic assays for detecting mixed Plasmodium infection

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    <p>Abstract</p> <p>Background</p> <p>One of the most commonly used molecular test for malaria diagnosis is the polymerase chain reaction (PCR)-based amplification of the 18S ribosomal DNA (rDNA) gene. Published diagnostic assays based on the 18S gene include the "gold standard" nested assay, semi-nested multiplex assay, and one tube multiplex assay. To our knowledge, no one has reported whether the two multiplex methods are better at detecting mixed <it>Plasmodium </it>infections compared to the nested assay using known quantities of DNA in experimentally mixed cocktails.</p> <p>Findings</p> <p>Here we evaluated three PCR assays (nested, semi-nested multiplex, and one-tube multiplex) for the simultaneous detection of human malaria parasites using experimentally mixed cocktails of known quantities of laboratory derived DNA. All three assays detected individual species with high sensitivity and specificity when DNA was from any one single species; however, experimentally mixed DNA cocktails with all four species present were correctly identified most consistently with the nested method. The other two methods failed to consistently identify all four species correctly, especially at lower concentrations of DNA -subclinical levels of malaria (DNA equivalent to or less than 10 parasites per microliter).</p> <p>Conclusions</p> <p>The nested PCR method remains the method of choice for the detection of mixed malaria infections and especially of sub-clinical infections. Further optimization and/or new molecular gene targets may improve the success rate of detecting multiple parasite species simultaneously using traditional PCR assays.</p

    Systematic review of mass media interventions designed to improve public recognition of stroke symptoms, emergency response and early treatment

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    <p>Abstract</p> <p>Background</p> <p>Mass media interventions have been implemented to improve emergency response to stroke given the emergence of effective acute treatments, but their impact is unclear.</p> <p>Methods</p> <p>Systematic review of mass media interventions aimed at improving emergency response to stroke, with narrative synthesis and review of intervention development.</p> <p>Results</p> <p>Ten studies were included (six targeted the public, four both public and professionals) published between 1992 and 2010. Only three were controlled before and after studies, and only one had reported how the intervention was developed. Campaigns aimed only at the public reported significant increase in awareness of symptoms/signs, but little impact on awareness of need for emergency response. Of the two controlled before and after studies, one reported no impact on those over 65 years, the age group at increased risk of stroke and most likely to witness a stroke, and the other found a significant increase in awareness of two or more warning signs of stroke in the same group post-intervention. One campaign targeted at public and professionals did not reduce time to presentation at hospital to within two hours, but increased and sustained thrombolysis rates. This suggests the campaign had a primary impact on professionals and improved the way that services for stroke were organised.</p> <p>Conclusions</p> <p>Campaigns aimed at the public may raise awareness of symptoms/signs of stroke, but have limited impact on behaviour. Campaigns aimed at both public and professionals may have more impact on professionals than the public. New campaigns should follow the principles of good design and be robustly evaluated.</p

    Establishment of the 1st World Health Organization International Standard for Plasmodium falciparum DNA for nucleic acid amplification technique (NAT)-based assays

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    BACKGROUND: In order to harmonize results for the detection and quantification of Plasmodium falciparum DNA by nucleic acid amplification technique (NAT)-based assays, a World Health Organization (WHO) collaborative study was performed, evaluating a series of candidate standard preparations. METHODS: Fourteen laboratories from 10 different countries participated in the collaborative study. Four candidate preparations based upon blood samples parasitaemic for P. falciparum were evaluated in the study. Sample AA was lyophilized, whilst samples BB, CC and DD were liquid/frozen preparations. The candidate standards were tested by each laboratory at a range of dilutions in four independent assays, using both qualitative and quantitative NAT-based assays. The results were collated and analysed statistically. RESULTS: Twenty sets of data were returned from the participating laboratories and used to determine the mean P. falciparum DNA content for each sample. The mean log10 "equivalents"/ml were 8.51 for sample AA, 8.45 for sample BB, 8.35 for sample CC, and 5.51 for sample DD. The freeze-dried preparation AA, was examined by accelerated thermal degradation studies and found to be highly stable. CONCLUSION: On the basis of the collaborative study, the freeze-dried material, AA (NIBSC code No. 04/176) was established as the 1st WHO International Standard for P. falciparum DNA NAT-based assays and has been assigned a potency of 10(9) International Units (IU) per ml. Each vial contains 5 x 10(8) IU, equivalent to 0.5 ml of material after reconstitution

    Improving Knowledge and Attitudes towards Depression: a controlled trial among Chinese medical students

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    <p>Abstract</p> <p>Background</p> <p>Establishing an evidence-based method of improving knowledge and attitudes concerning depression has been identified as a priority in Chinese medical education. The purpose of this study was to determine whether a self-directed learning strategy as a part of student-centred education improved knowledge of and attitudes towards depression among Chinese medical students.</p> <p>Methods</p> <p>A controlled trial in which 205 medical students were allocated to one of two groups: didactic teaching (DT) group or a combined didactic teaching and self-directed learning (DT/SDL) group. The DT/SDL group continued having a series of learning activities after both groups had a lecture on depression together. Student's knowledge and attitudes were assessed immediately after the activities, one month and six months later.</p> <p>Results</p> <p>The intervention (DT/SDL) group showed substantially greater improvements in recognition of depression as a major health issue and identifying helpful treatments than the DT group. Only the DT/SDL group demonstrated any improvement in attitudes. This improvement was sustained over six months.</p> <p>Conclusions</p> <p>Self-directed learning is an effective education strategy in improving medical students' knowledge of and attitudes towards depression.</p

    Longitudinal in vivo MRI in a Huntington’s disease mouse model: global atrophy in the absence of white matter microstructural damage

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    Huntington’s disease (HD) is a genetically-determined neurodegenerative disease. Characterising neuropathology in mouse models of HD is commonly restricted to cross-sectional ex vivo analyses, beset by tissue fixation issues. In vivo longitudinal magnetic resonance imaging (MRI) allows for disease progression to be probed non-invasively. In the HdhQ150 mouse model of HD, in vivo MRI was employed at two time points, before and after the onset of motor signs, to assess brain macrostructure and white matter microstructure. Ex vivo MRI, immunohistochemistry, transmission electron microscopy and behavioural testing were also conducted. Global brain atrophy was found in HdhQ150 mice at both time points, with no neuropathological progression across time and an elective sparing of the cerebellum. In contrast, no white matter abnormalities were detected from the MRI images or electron microscopy images alike. The relationship between motor function and MR-based structural measurements was different for the HdhQ150 and wild-type mice, although there was no relationship between motor deficits and histopathology. Widespread neuropathology prior to symptom onset is consistent with patient studies, whereas the absence of white matter abnormalities conflicts with patient data. The myriad reasons for this inconsistency require further attention to improve the translatability from mouse models of disease
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