7,659 research outputs found

    Icosahedron designs

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    It is known from the work of Adams and Bryant that icosahedron designs of order v exist for v ≡ 1 (mod 60) as well as for v = 16. Here we prove that icosahedron designs exist if and only if v ≡ 1, 16, 21 or 36 (mod 60), wit

    The rapid response of ovarian and uterine veins of mice to sex hormones.

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    Subcutaneous injections in sesame oil of testosterone and estradiol-17 beta into ovariectomized and ovariectomized-hysterectomized young adult mice were followed in six hours or less by significant increases in the diameters of the ovarian and uterine veins as compared to the same vessels in sesame oil-injected controls. The circumflex iliac, femoral, and superior mesenteric veins and inferior vena cava failed to respond. The results demonstrate the specificity and speed of response of ovarian and uterine veins of mice and the control of the response by sex hormones

    Mirror Map as Generating Function of Intersection Numbers: Toric Manifolds with Two K\"ahler Forms

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    In this paper, we extend our geometrical derivation of expansion coefficients of mirror maps by localization computation to the case of toric manifolds with two K\"ahler forms. Especially, we take Hirzebruch surfaces F_{0}, F_{3} and Calabi-Yau hypersurface in weighted projective space P(1,1,2,2,2) as examples. We expect that our results can be easily generalized to arbitrary toric manifold.Comment: 45 pages, 2 figures, minor errors are corrected, English is refined. Section 1 and Section 2 are enlarged. Especially in Section 2, confusion between the notion of resolution and the notion of compactification is resolved. Computation under non-zero equivariant parameters are added in Section

    Public availability and adherence to prespecified statistical analysis approaches was low in published randomized trials

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    BACKGROUND AND OBJECTIVE: Prespecification of statistical methods in clinical trial protocols and statistical analysis plans can help to deter bias from p-hacking but is only effective if the prespecified approach is made available. STUDY DESIGN AND SETTING: For 100 randomized trials published in 2018 and indexed in PubMed, we evaluated how often a prespecified statistical analysis approach for the trial's primary outcome was publicly available. For each trial with an available prespecified analysis, we compared this with the trial publication to identify whether there were unexplained discrepancies. RESULTS: Only 12 of 100 trials (12%) had a publicly available prespecified analysis approach for their primary outcome; this document was dated before recruitment began for only two trials. Of the 12 trials with an available prespecified analysis approach, 11 (92%) had one or more unexplained discrepancies. Only 4 of 100 trials (4%) stated that the statistician was blinded until the SAP was signed off, and only 10 of 100 (10%) stated the statistician was blinded until the database was locked. CONCLUSION: For most published trials, there is insufficient information available to determine whether the results may be subject to p-hacking. Where information was available, there were often unexplained discrepancies between the prespecified and final analysis methods

    Signal Strength, Media Attention, and Resource Mobilization: Evidence from New Private Equity Firms

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    This is the author accepted manuscript. The final version is available from the Academy of Management via the DOI in this recordPast research has shown that new firms can facilitate resource mobilization by signaling their unobservable quality to prospective resource providers. However, we know less about situations in which firms convey multiple signals of different strengths—i.e., signals that are more or less correlated with unobservable firm quality. Building on a sociocognitive perspective, we propose that prospective resource providers respond differently to signals of different strengths and that the effectiveness of signals, especially weak signals, will be contingent on the media attention new firms receive. Empirically, we conduct a longitudinal analysis examining the ability of new private equity (PE) firms to raise a follow-on fund. Consistent with our theory, we find that unrealized performance, a relatively weak signal, positively influences fundraising. But we fail to find statistical evidence that its effect is weaker than that of realized performance, a relatively strong signal. Further, media attention strengthens the relationship between unrealized performance and fundraising, but media attention exerts less impact on the relationship between realized performance and fundraising. Taken together, our findings deepen our understanding of how new firms can mobilize resources with signals of different strengths and of how the media—as a key information intermediary—differently impacts their effectiveness.Richard M. Schulze Family Foundatio

    Distinguishing Solar Flare Types by Differences in Reconnection Regions

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    Observations show that magnetic reconnection and its slow shocks occur in solar flares. The basic magnetic structures are similar for long duration event (LDE) flares and faster compact impulsive (CI) flares, but the former require less non-thermal electrons than the latter. Slow shocks can produce the required non-thermal electron spectrum for CI flares by Fermi acceleration if electrons are injected with large enough energies to resonate with scattering waves. The dissipation region may provide the injection electrons, so the overall number of non-thermal electrons reaching the footpoints would depend on the size of the dissipation region and its distance from the chromosphere. In this picture, the LDE flares have converging inflows toward a dissipation region that spans a smaller overall length fraction than for CI flares. Bright loop-top X-ray spots in some CI flares can be attributed to particle trapping at fast shocks in the downstream flow, the presence of which is determined by the angle of the inflow field and velocity to the slow shocks.Comment: 15 pages TeX and 2 .eps figures, accepted to Ap.J.Let

    Structure of the low latitude boundary layer

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    Observations at high temporal resolution of the frontside magnetopause and plasma boundary layer, made with the LASL/MPE fast plasma analyzer onboard the ISEE 1 and 2 spacecraft, revealed a complex quasiperiodic structure of some of the observed boundary layers. A cool tailward streaming boundary layer plasma was seen intermittently, with intervening periods of hot tenuous plasma which has properties similar to the magnetospheric population. While individual encounters with the boundary layer plasma last only a few minutes, the total observation time may extend over one hour or more
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