6,127 research outputs found
Realistic Type IIB Supersymmetric Minkowski Flux Vacua
We show that there exist supersymmetric Minkowski vacua on Type IIB toroidal
orientifold with general flux compactifications where the RR tadpole
cancellation conditions can be relaxed elegantly. Then we present a realistic
Pati-Salam like model. At the string scale, the gauge symmetry can be broken
down to the Standard Model (SM) gauge symmetry, the gauge coupling unification
can be achieved naturally, and all the extra chiral exotic particles can be
decoupled so that we have the supersymmetric SMs with/without SM singlet(s)
below the string scale. The observed SM fermion masses and mixings can also be
obtained. In addition, the unified gauge coupling, the dilaton, the complex
structure moduli, the real parts of the K\"ahler moduli and the sum of the
imaginary parts of the K\"ahler moduli can be determined as functions of the
four-dimensional dilaton and fluxes, and can be estimated as well.Comment: RevTex4, 4 pages, 3 table
A Synthetical Approach for Blog Recommendation Mechanism: Trust, Social Relation, and Semantic Analysis
Weblog is a good paradigm of online social network which constitutes web-based regularly updated journals with reverse chronological sequences of dated entries, usually with blogrolls on the sidebars, allowing bloggers link to favorite site which they are frequently visited. In this study we propose an elaborate blog recommendation mechanism that combines trust model, social relation and semantic analysis and illustrate how it can be applied to a prestigious online blogging system – Wretch in Taiwan. By preliminary results of experimental study, we found some implications and empirically prove some theories in domain of social networking, and the example reveals that the proposed recommendation mechanism is quite feasible and promising
Yukawa Corrections from Four-Point Functions in Intersecting D6-Brane Models
We discuss corrections to the Yukawa matrices of the Standard Model (SM)
fermions in intersecting D-brane models due to four-point interactions.
Recently, an intersecting D-brane model has been found where it is possible to
obtain correct masses and mixings for all quarks as well as the tau lepton.
However, the masses for the first two charged leptons come close to the right
values but are not quite correct. Since the electron and muon are quite light,
it is likely that there are additional corrections to their masses which cannot
be neglected. With this in mind, we consider contributions to the SM fermion
mass matrices from four-point interactions. In an explicit model, we show that
it is indeed possible to obtain the SM fermion masses and mixings which are a
better match to those resulting from experimental data extrapolated at the
unification scale when these corrections are included. These corrections may
have broader application to other models.Comment: 24 pages, 4 figure
An Economy-wide Analysis of Impacts of WTO Tiered Formula for Tariff Reduction on Taiwan
In this study we use Taiwan as a case study to provide an economy-wide analysis of impacts on Taiwan of WTO tariff reduction schemes with different combinations of thresholds and reduction rates. The model we utilized in this study is Taiwan General Equilibrium Model with a WTO module (TAIGEM-WTO, hereafter) that is a multi-sectoral computable general equilibrium (CGE) model of the Taiwan's economy derived from Australian ORANI model (Dixon, Parmenter, Sutton and Vincent, 1982). Simulation results show that results are more sensitive to the scheme of tariff-reduction (i.e., Category 1, 2, and 3) than the tiered levels (i.e., A, B, C, and D) and as a strategy we should pay more attention to the arguments related to the amounts of tariff-reduction. Moreover, changes in nominal average tariff rates are more sensitive and shocks to the economy are more severe when we change the tariff reduction categories rather than the tiered levels. This conclusion also applies to the tiered reduction case when only sensitive products are considered. Finally, simulations with sector's bound rate calculated using arithmetic means have bigger effects than those using import values as weights. Therefore, sector's bound rate using import values as weights would be preferred.International Relations/Trade,
Substance P scavenger enhances antioxidant defenses and prevents prothrombotic effects on the rat lung after acute exposure to oil smoke
<p>Abstract</p> <p>Background</p> <p>Airborne particulate matter, from cooking oil, smoking, engine exhaust and other sources, is associated with the development of atherosclerosis and myocardial infarction. In order to explore the cellular and molecular events following exposure of rats to lard oil smoke, we measured the generation of reactive oxygen species (ROS), substance P, cellular adhesion molecules, and thrombosis in relation to inhibitors of substance P, the NK-1 receptor, and antioxidants.</p> <p>Methods</p> <p>Rats were exposed to oil smoke for 120 min with or without 20 min pretreatment with lovastatin (substance P scavenger), L733060 (NK-1 receptor antagonist), vitamin E (antioxidant) or catechins (antioxidant). The levels of substance P and ROS were measured. Histological studies observed ROS damage in the form of HEL adducts. The prothrombotic effects of oil smoke exposure were measured by experimental induction of thrombosis in vivo.</p> <p>Results</p> <p>Oil smoke exposure significantly increased substance P levels, ROS levels, ROS damage (HEL adduct levels), and the size of experimentally induced thrombi. The pretreatments reduced all of these effects of oil smoke exposure; at many time points the reductions were statistically significant.</p> <p>Conclusion</p> <p>We established a connection between oil smoke exposure and thrombosis which involves substance P and its receptor, the NK-1 receptor, and ROS. This study helps establish a mechanistic explanation of how airborne particulate matter can increase the risk of cardiovascular illness.</p
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