130 GeV gamma-ray line and enhancement of h→γγh\to\gamma\gamma in the Higgs triplet model plus a scalar dark matter

With a discrete $Z_2$ symmetry being imposed, we introduce a real singlet scalar $S$ to the Higgs triplet model with the motivation of explaining the tentative evidence for a spectral feature at $E_\gamma$ = 130 GeV in the Fermi LAT data. The model can naturally satisfy the experimental constraints of the dark matter relic density and direct detection data from Xenon100. The doubly charged and one charged scalars can enhance the annihilation cross section of $SS\to\gamma\gamma$ via the one-loop contributions, and give the negligible contributions to the relic density. $_{SS\to\gamma\gamma}$ for $m_{S}=130$ GeV can reach \ord(1)\times10^{-27} cm^3 s^{-1} for the small charged scalar masses and the coupling constant of larger than 1. Besides, this model also predict a second photon peak at 114 GeV from the annihilation $SS\to\gamma Z$, and the cross section is approximately 0.76 times that of $SS\to\gamma \gamma$, which is below the upper limit reported by Fermi LAT. Finally, the light charged scalars can enhance LHC diphoton Higgs rate, and make it to be consistent with the experimental data reported by ATLAS and CMS.Comment: 15 pages, 4 figure

International Diversification at Home and Abroad

It is an established fact that investors favor the familiar%u2014be it domestic securities or, within a country, the securities of nearby firms%u2014and avoid investments that would provide the greatest diversification benefits. While we do not rule out familiarity as an important driver of portfolio allocations, we provide new evidence of investors%u2019 international diversification motive. In particular, our analysis of the security-level U.S. equity holdings of foreign and domestic institutional investors indicates that institutional investors reveal a preference for domestic multinationals (MNCs), even after controlling for familiarity factors. We attribute this revealed preference to the desire to obtain %u201Csafe%u201D international diversification. We then show that holdings of domestic MNCs are substantial and, after accounting for this home-grown foreign exposure, that the share of %u201Cforeign%u201D equities in investors%u2019 portfolios roughly doubles, reducing (but not eliminating) the observed home bias.

International diversification at home and abroad

We analyze foreigners' and domestic institutional investors' positions in U.S. equities. Controlling for many factors, we uncover a common preference for large firms and firms that are diversified internationally. The domestic preference for internationally diversified firms implies that investors might obtain substantial international diversification by investing at home. Using an international factor model, we show that exposure to foreign equity markets is indeed greater for domestic firms that are more diversified internationally, suggesting that at least some of the home-grown foreign exposure translates into international diversification benefits. After accounting for home-grown foreign exposure, the share of "foreign" equities in investors' portfolios nearly doubles, reducing (but not eliminating) the observed home bias. --home bias,international portfolio allocation,foreign exposure

Stability of diluted adenosine solutions in polyvinyl chloride infusion bags

Purpose The stability of diluted adenosine solutions in polyvinyl chloride infusion bags was studied. Methods Adenosine 50-, 100-, and 220-μg/mL solutions were prepared in 50-mL polyvinyl chloride (PVC) infusion bags containing 0.9% sodium chloride injection or 5% dextrose injection and stored at room temperature (23–25 °C) or under refrigeration (2–8 °C). Each sample of every combination of concentration, diluent, and storage temperature was prepared in triplicate, yielding 36 samples. The samples were assayed using a stability-indicating, reverse-phase high-performance liquid chromatographic method immediately after preparation (time zero) and at 24 hours, 48 hours, 7 days, and 14 days. pH was measured at time zero, 48 hours, 7 days, and 14 days. Time zero concentrations were calculated from the equation produced from a calibration curve of standards ranging from 10 to 500 μg/mL. Samples were also visually inspected against a light background for clarity, color, and the presence of crystalline particulate matter. Stability was defined as retaining at least 90% of the initial adenosine concentration. Results After 14 days, all samples retained greater than 98% of the initial adenosine concentration, with no evidence of adsorption, visible precipitation, or considerable change in pH, suggesting minimal to no loss of product due to degradation or adsorption. Conclusion Adenosine 50-, 100-, and 220-μg/mL solutions in 50-mL PVC infusion bags containing 0.9% sodium chloride injection or 5% dextrose injection stored at room temperature and refrigerated conditions were stable for at least 14 days

Scattering of plasmons at the intersection of two metallic nanotubes: Implications for tunnelling

We study theoretically the plasmon scattering at the intersection of two metallic carbon nanotubes. We demonstrate that for a small angle of crossing, $\theta \ll 1$, the transmission coefficient is an oscillatory function of $\lambda/\theta$, where $\lambda$ is the interaction parameter of the Luttinger liquid in an individual nanotube. We calculate the tunnel density of states, $\nu(\omega,x)$, as a function of energy, $\omega$, and distance, $x$, from the intersection. In contrast to a single nanotube, we find that, in the geometry of crossed nanotubes, conventional "rapid" oscillations in $\nu(\omega,x)$ due to the plasmon scattering acquire an aperiodic "slow-breathing" envelope which has $\lambda/\theta$ nodes.Comment: 4 pages, 2 figures (revised version

Incentives for Developers’ Contributions and Product Performance Metrics in Open Source Development: An Empirical Exploration

In open source software development, users rather than paid developers engage in innovation and development without the direct involvement of manufacturers. This paradigm cannot be explained by the two traditional models of innovation, the private investment model and the collective action model. Neither model in itself can explain the phenomenon of the open source model or its success. In order to bridge the gap between existing models and the open source phenomenon, we analyze data from a web survey of 160 open source developers. First, we investigate the motives affecting the individual developer’s contributions by comparing and contrasting the incentives from both the traditional private investment and collective action models. Second, we demonstrate that there is a common ground between the private and collective models where private returns and social considerations can coexist. Third, we explore the effect of incentives on the output of innovation—final product performance. The results show that the motivations for individual developer’s contributions are quite different from the incentives that affect product performance.

Bifurcation Boundary Conditions for Switching DC-DC Converters Under Constant On-Time Control

Sampled-data analysis and harmonic balance analysis are applied to analyze switching DC-DC converters under constant on-time control. Design-oriented boundary conditions for the period-doubling bifurcation and the saddle-node bifurcation are derived. The required ramp slope to avoid the bifurcations and the assigned pole locations associated with the ramp are also derived. The derived boundary conditions are more general and accurate than those recently obtained. Those recently obtained boundary conditions become special cases under the general modeling approach presented in this paper. Different analyses give different perspectives on the system dynamics and complement each other. Under the sampled-data analysis, the boundary conditions are expressed in terms of signal slopes and the ramp slope. Under the harmonic balance analysis, the boundary conditions are expressed in terms of signal harmonics. The derived boundary conditions are useful for a designer to design a converter to avoid the occurrence of the period-doubling bifurcation and the saddle-node bifurcation.Comment: Submitted to International Journal of Circuit Theory and Applications on August 10, 2011; Manuscript ID: CTA-11-016