Astrometric Detection of Double Gravitational Microlensing Events

If a gravitational microlensing event is caused by a widely separated binary lens and the source approaches both lens components, the source flux is successively magnified by the individual lenses: double microlensing events. If events are observed astrometrically, double lensing events are expected to occur with an increased frequency due to the long range astrometric effect of the companion. We find that although the trajectory of the source star image centroid shifts of an astrometric double lensing event has a distorted shape from both of the elliptical ones induced by the individual single lens components, event duplication can be readily identified by the characteristic loop in the trajectory formed during the source's passage close to the companion. We determine and compare the probabilities of detecting double lensing events from both photometric and astrometric lensing observations by deriving analytic expressions for the relations between binary lensing parameters to become double lensing events. From this determination, we find that for a given set of the binary separation and the mass ratio the astrometric probability is roughly an order higher than the photometric probability. Therefore, we predict that a significant fraction of events that will be followed up by using future high precision interferometeric instruments will be identified as double lensing events.Comment: total 6 pages, including 4 figures and no table, ApJ, submitte

Value Discount of Business Groups Surrounding the Asia Financial Crisis: Evidence from Korean Chaebols

Asian Financial Crisis, Business Group, Chaebol, Diversification, Firm Value

A Study on Thermal Modeling and Heat Load Mitigation for Satellite Electronic Components

Since most of the satellite components are using various EEE (Electrical, Electronic and Electromechanical) parts, the reliability of EEE parts acts very important in the satellite system. There are many factors that influence the reliability of EEE parts in the satellite system. Excessively dissipated heat can cause the failure of EEE parts and consequently, leading to a failure of total satellite system. In this paper, the thermal modeling using nodal network was compared with that using plate modeling to find out which one is the most suitable methodology. For a comparison, KOMPSAT- 1 SAR was modeled by two different modeling and the result was discussed. There was almost no difference in the numerical results between the two modeling methods. However, while it took much more time to perform thermal analysis using the nodal network modeling method, and the debugging was more difficult in the plate modeling method when the error is occurred. The computation time was considerably reduced by developing and implementing the input file format transfer code when using nodal network modeling method. It was found that the nodal network modeling method is suitable for the complicated components, such as SAR or transponder, because of its simple debugging ability. Excessive heat load was expected on some EEE parts of SAR such as high heat-dissipated diodes, transistors, and inductors due to increased power requirements of KOMPSAT-2 satellite system. The methods for the mitigation of heat load were studied through the design change of housing or the layout change of high power parts

A candidate LiBH4 for hydrogen storage: Crystal structures and reaction mechanisms of intermediate phases

First-principles calculation and x-ray diffraction simulation methods have been used to explore crystal structures and reaction mechanisms of the intermediate phases involved in dehydriding of LiBH4. LiBH4 was found to dehydride via two sequential steps: first dehydriding through LiBH, followed by the dehydriding of LiBH through LiB. The first step, which releases 13.1 wt. % hydrogen, was calculated to have an activation barrier of 2.33 eV per formula unit and was endothermic by 1.28 eV per formula unit, while the second step was endothermic by 0.23 eV per formula unit. On the other hand, if LiBH4 and LiBH each donated one electron, possibly to the catalyst doped on their surfaces, it was found that the barrier for the first step was reduced to 1.50 eV. This implies that the development of the catalyst to induce charge migration from the bulk to the surface is essential to make LiBH4 usable as a hydrogen storage material in a moderate temperature range, which is also important to stabilize the low-temperature structure of Pnma (no. 62) LiBH on dehydrogenation. Consequently, the high 13.1 wt. % hydrogen available from the dehydriding of LiBH4 and LiBH and their phase stability on Pnma when specific catalysts were used suggest that LiBH4 has good potential to be developed as the hydrogen storage medium capable of releasing the Department of Energy target of 6.5 wt. % for a hydrogen fuel cell car in a moderate temperature range

Perfect Basis Theory for Quantum Borcherds-Bozec Algebras

In this paper, we develop the perfect basis theory for quantum Borcherds-Bozec algebras $U_{q}(\mathfrak g)$ and their irreducible highest weight modules $V(\lambda)$. We show that the perfect graph (resp. dual perfect graph) of every perfect basis (resp. dual perfect basis) of $U_{q}^{-}(\mathfrak g)$ (resp. $V(\lambda)$) is isomorphic to $B(\infty)$ (resp. $B(\lambda)$). For this purpose, we define a new class of Kashiwara operators which is different from the one given by Bozec and prove all the interlocking inductive statements in Kashiwara's grand loop argument, which shows the existence and the uniqueness of crystal bases for quantum Borcherds-Bozec algebras

Blockade of Airway Inflammation by Kaempferol via Disturbing Tyk-STAT Signaling in Airway Epithelial Cells and in Asthmatic Mice

Asthma is characterized by bronchial inflammation causing increased airway hyperresponsiveness and eosinophilia. The interaction between airway epithelium and inflammatory mediators plays a key role in the asthmatic pathogenesis. The in vitro study elucidated inhibitory effects of kaempferol, a flavonoid found in apples and many berries, on inflammation in human airway epithelial BEAS-2B cells. Nontoxic kaempferol at ≤20 μM suppressed the LPS-induced IL-8 production through the TLR4 activation, inhibiting eotaxin-1 induction. The in vivo study explored the demoting effects of kaempferol on asthmatic inflammation in BALB/c mice sensitized with ovalbumin (OVA). Mouse macrophage inflammatory protein-2 production and CXCR2 expression were upregulated in OVA-challenged mice, which was attenuated by oral administration of ≥10 mg/kg kaempferol. Kaempferol allayed the airway tissue levels of eotaxin-1 and eotaxin receptor CCR3 enhanced by OVA challenge. This study further explored the blockade of Tyk-STAT signaling by kaempferol in both LPS-stimulated BEAS-2B cells and OVA-challenged mice. LPS activated Tyk2 responsible for eotaxin-1 induction, while kaempferol dose-dependently inhibited LPS- or IL-8-inflamed Tyk2 activation. Similar inhibition of Tyk2 activation by kaempferol was observed in OVA-induced mice. Additionally, LPS stimulated the activation of STAT1/3 signaling concomitant with downregulated expression of Tyk-inhibiting SOCS3. In contrast, kaempferol encumbered STAT1/3 signaling with restoration of SOCS3 expression. Consistently, oral administration of kaempferol blocked STAT3 transactivation elevated by OVA challenge. These results demonstrate that kaempferol alleviated airway inflammation through modulating Tyk2-STAT1/3 signaling responsive to IL-8 in endotoxin-exposed airway epithelium and in asthmatic mice. Therefore, kaempferol may be a therapeutic agent targeting asthmatic diseases

Polarization Effects on the e+e−→W+W−e+e- \to W^+W^- process with Large Extra Dimensions

We study large extra dimension effects on the polarizations of the $W$ pair and electron beam at the $e^+ e^-\to W^+ W^-$ process. It is shown that the measurements of the cross section for transversely polarized $W$ pair with the right-handed electron beam remarkably enhance the possibilities to see the low scale quantum gravity effects. Higher Linear Collider bounds on the string scale in this model can be obtained by using the left-handed electron beam.Comment: Final version to appear in Phys.Lett.B. More references are adde

Echo Path Transfer Function Estimation for Spectral Subtraction-based Acoustic Echo Suppression

In this study, we propose a novel technique for spectral subtraction (SS)-based acoustic echo suppression (AES). Conventional AES methods based on SS apply fixed weights to the estimated echo path transfer function (EPTF) at the current signal segment and to the EPTF estimated until the previous time interval. We propose a new EPTF estimation approach that adaptively updates the weight parameters in response to abrupt changes in the acoustic environment. From the experiments, we conclude that the developed techniques can be successfully used for the SS-based AES systems

GW Calculations on post-transition-metal oxides

In order to establish the reliable GW scheme that can be consistently applied to post-transition-metal oxides (post-TMOs), we carry out comprehensive GW calculations on electronic structures of ZnO, Ga2O3, In2O3, and SnO2, the four representative post-TMOs. Various levels of self-consistency (G0W0, GW0, and QPGW0) and different starting functionals (GGA, GGA + U, and hybrid functional) are tested and their influence on the resulting electronic structure is closely analyzed. It is found that the GW0 scheme with GGA + U as the initial functional turns out to give the best agreement with experiment, implying that describing the position of metal-d level precisely in the ground state plays a critical role for the accurate dielectric property and quasiparticle band gap. Nevertheless, the computation on ZnO still suffers from the shallow Zn-d level and we propose a modified approach (GW0+Ud) that additionally considers an effective Hubbard U term during GW0 iterations and thereby significantly improves the band gap. It is also shown that a GGA + U-based GW0(+Ud) scheme produces an accurate energy gap of crystalline InGaZnO4, implying that this can serve as a standard scheme that can be applied to general structures of post-TMOs. © 2014 American Physical Society.1991sciescopu