875 research outputs found

    The genetic contribution of single male immigrants to small, inbred populations: A laboratory study using drosophila melanogaster

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    This study examined the genetic contribution of single male immigrants to small, inbred laboratory populations of Drosophila melanogaster. Genetic contribution was assessed by measuring the relative frequency of immigrant marker alleles in the first and second generations after immigration, while controlling for any selection effects at the marker locus, and for the experience of male immigrants. When immigrants were outbred, the mean frequency of the immigrant allele was significantly higher than its initial frequency, in both the first and second generations after immigration. There was no significant change in allele frequency for populations receiving inbred immigrants. The increase in allele frequency for outbred immigrants was attributed to an initial outbred vigour fitness advantage of immigrant males over resident males experiencing inbreeding depression. Hybrid vigour of immigrant progeny and the rare-male effect did not have a statistically significant role in the fitness advantage of the immigrant allele. The results suggest that inbreeding may have a considerable impact on the contribution of immigrants to the genetic diversity of populations

    A Systematic Review of Online Sex Addiction and Clinical Treatments Using CONSORT Evaluation

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    Researchers have suggested that the advances of the Internet over the past two decades have gradually eliminated traditional offline methods of obtaining sexual material. Additionally, research on cybersex and/or online sex addictions has increased alongside the development of online technology. The present study extended the findings from Griffiths’ (2012) systematic empirical review of online sex addiction by additionally investigating empirical studies that implemented and/or documented clinical treatments for online sex addiction in adults. A total of nine studies were identified and then each underwent a CONSORT evaluation. The main findings of the present review provide some evidence to suggest that some treatments (both psychological and/or pharmacological) provide positive outcomes among those experiencing difficulties with online sex addiction. Similar to Griffiths’ original review, this study recommends that further research is warranted to establish the efficacy of empirically driven treatments for online sex addiction

    Serologic testing for symptomatic coccidioidomycosis in immunocompetent and immunosuppressed hosts

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    Serologic studies are an important diagnostic tool in the clinical evaluation and follow-up of persons with coccidioidomycosis. Numerous types of serologic tests are available, including immunodiffusion, enzyme immunoassay, and complement fixation. We conducted a retrospective review of the results of 1,797 serologic tests spanning 12 months from the onset of coccidioidomycosis in 298 immunocompetent and 62 immunosuppressed persons with symptomatic infection. Using the onset of symptoms as a reference point, we plotted the positive or negative serologic results over time for both groups. Compared with the immunocompetent group, immunosuppressed persons had lower rates of seropositivity for every type of test during the first year after onset of symptoms for coccidioidomycosis, although many results did not achieve statistical significance. Combining the results of these tests increased the sensitivity of the serologic evaluation in immunocompromised patients. Immunosuppressed persons have the ability to mount a serologic response to coccidioidomycosis, but in some circumstances, multiple methods may be required to improve detection

    Parity-Violating Electron Scattering from 4He and the Strange Electric Form Factor of the Nucleon

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    We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from ^4He at an average scattering angle = 5.7 degrees and a four-momentum transfer Q^2 = 0.091 GeV^2. From these data, for the first time, the strange electric form factor of the nucleon G^s_E can be isolated. The measured asymmetry of A_PV = (6.72 +/- 0.84 (stat) +/- 0.21 (syst) parts per million yields a value of G^s_E = -0.038 +/- 0.042 (stat) +/- 0.010 (syst), consistent with zero

    What can we learn from facilitator and student perceptions of facilitation skills and roles in the first year of a problem-based learning curriculum?

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    BACKGROUND: The small group tutorial is a cornerstone of problem-based learning. By implication, the role of the facilitator is of pivotal importance. The present investigation canvassed perceptions of facilitators with differing levels of experience regarding their roles and duties in the tutorial. METHODS: In January 2002, one year after problem-based learning implementation at the Nelson R. Mandela School of Medicine, facilitators with the following experience were canvassed: trained and about to facilitate, facilitated once only and facilitated more than one six-week theme. Student comments regarding facilitator skills were obtained from a 2001 course survey. RESULTS: While facilitators generally agreed that the three-day training workshop provided sufficient insight into the facilitation process, they become more comfortable with increasing experience. Many facilitators experienced difficulty not providing content expertise. Again, this improved with increasing experience. Most facilitators saw students as colleagues. They agreed that they should be role models, but were less enthusiastic about being mentors. Students were critical of facilitators who were not up to date with curriculum implementation or who appeared disinterested. While facilitator responses suggest that there was considerable intrinsic motivation, this might in fact not be the case. CONCLUSIONS: Even if they had facilitated on all six themes, facilitators could still be considered as novices. Faculty support is therefore critical for the first few years of problem-based learning, particularly for those who had facilitated once only. Since student and facilitator expectations in the small group tutorial may differ, roles and duties of facilitators must be explicit for both parties from the outset

    Haptic subitizing across the fingers

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    Numerosity judgments of small sets of items (≤ 3) are generally fast and errorfree, while response times and error rates increase rapidly for larger numbers of items. We investigated an efficient process used for judging small numbers of items (known as subitizing) in active touch. We hypothesized that this efficient process for numerosity judgment might be related to stimulus properties that allow for efficient (parallel) search. Our results showed that subitizing was not possible forraised lines among flat surfaces, whereas this type of stimulus could be detected in parallel over the fingers. However, subitizing was possible when the number of fingers touching a surface had to be judged while the other fingers were lowered in mid-air. In the latter case, the lack of tactile input is essential, since subitizing was not enabled by differences in proprioceptive information from the fingers. Our results show that subitizing using haptic information from the fingers is possible only whensome fingers receive tactile information while other fingers do not

    Commonality Preserving Multiple Instance Clustering Based on Diverse Density

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    Abstract. Image-set clustering is a problem decomposing a given im-age set into disjoint subsets satisfying specied criteria. For single vector image representations, proximity or similarity criterion is widely applied, i.e., proximal or similar images form a cluster. Recent trend of the im-age description, however, is the local feature based, i.e., an image is described by multiple local features, e.g., SIFT, SURF, and so on. In this description, which criterion should be employed for the clustering? As an answer to this question, this paper presents an image-set clus-tering method based on commonality, that is, images preserving strong commonality (coherent local features) form a cluster. In this criterion, image variations that do not affect common features are harmless. In the case of face images, hair-style changes and partial occlusions by glasses may not affect the cluster formation. We dened four commonality mea-sures based on Diverse Density, that are used in agglomerative clustering. Through comparative experiments, we conrmed that two of our meth-ods perform better than other methods examined in the experiments.
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