Integrating a QPSK Quantum Key Distribution Link

We present the integration of the optical and electronic subsystems of a BB84-QKD fiber link. A highspeed FPGA MODEM generates the random QPSK sequences for a fiber-optic delayed self-homodyne scheme using APD detectors.Comment: 2 pages, 4 figures, European Conference on Optical Communication 200

Recoil Order Chiral Corrections to Baryon Octet Axial Currents

We calculate chiral corrections to the octet axial currents through ${\cal O}(p^3)$ using baryon chiral perturbation theory (BCPT). The relativistic BCPT framework allows one to sum an infinite series of recoil corrections at a given order in the chiral expansion. We also include SU(3)-breaking operators occuring at ${\cal O}(p^2)$ not previously considered. We determine the corresponding low-energy constants (LEC's) from hyperon semileptonic decay data using a variety of infrared regularization schemes. We find that the chiral expansion of the axial currents does not display the proper convergence behavior, regardless of which scheme is chosen. We explore the implications of our analysis for determinations of the strange quark contribution to the nucleon spin, $\Delta s$.Comment: RevTex, 19 pages + 2 PS figure

Determination of the Kobayashi-Maskawa-Cabibbo matrix element V_{us} under various flavor-symmetry-breaking models in hyperon semileptonic decays

We study the success to describe hyperon semileptonic decays of four models that incorporate second-order SU(3) symmetry breaking corrections. The criteria to assess their success is by determining V_{us} in each of the three relevant hyperon semileptonic decays and comparing the values obtained with one another and also with the one that comes from K_{l3} decays. A strong dependence on the particular symmetry breaking model is observed. Values of V_{us} which do not agree with the one of K_{l3} are generally obtained. However, in the context of chiral perturbation theory, only the model whose corrections are O(m_s) and O(m_s^{3/2}) is successful. Using its predictions for the f_1 form factors one can quote a value of V_{us} from this model, namely, V_{us}=0.2176\pm 0.0026, which is in excellent agreement with the K_{l3} one.Comment: Final versio

Contributions of order O(mquark2){\cal O}(m_{\rm quark}^2) to Kℓ3K_{\ell 3} form factors and unitarity of the CKM matrix

The form factors for the $K_{\ell 3}$ semileptonic decay are computed to order $O(p^4)$ in generalized chiral perturbation theory. The main difference with the standard $O(p^4)$ expressions consists in contributions quadratic in quark masses, which are described by a single divergence-free low-energy constant, $A_3$. A new simultaneous analysis is presented for the CKM matrix element $V_{us}$, the ratio $F_K/F_{\pi}$, $K_{\ell 3}$ decay rates and the scalar form factor slope $\lambda_0$. This framework easily accommodates the precise value for $V_{ud}$ deduced from superallowed nuclear $\beta$-decays

SU(3) symmetry breaking in hyperon semileptonic decays

Flavor SU(3) symmetry breaking in the hyperon semileptonic decay form-factors is analyzed using the 1/N expansion. A detailed comparison with experimental data shows that corrections to f_1 are approximately 10%, which agrees with theoretical expectations. Corrections to g_1 are compatible with first-order symmetry breaking. A fit to the experimental data allows one to predict the g_1 form factor for Xi^0 -> Sigma^+ decay. The proton matrix element of the T^8 component of the axial current (which is equal to 3F-D in the SU(3) symmetry limit) is found to be approximately 0.34.Comment: 18 pages (revtex). Discussion of theory errors added. Two redundant parameters for symmetry breaking in f1 deleted. Central values for the fits remain unchanged, but some of the errors are modifie

Large N_c, Constituent Quarks, and N, Delta Charge Radii

We show how one may define baryon constituent quarks in a rigorous manner, given physical assumptions that hold in the large-N_c limit of QCD. This constituent picture gives rise to an operator expansion that has been used to study large-N_c baryon observables; here we apply it to the case of charge radii of the N and Delta states, using minimal dynamical assumptions. For example, one finds the relation r_p^2 - r_{Delta^+}^2 = r_n^2 - r_{Delta^0}^2 to be broken only by three-body, O(1/N_c^2) effects for any N_c.Comment: 15 pages, 1 eps figure. Version to appear in Phys. Rev.

Current Advances in the Biochemical and Physiological Aspects of the Treatment of Type 2 Diabetes Mellitus with Thiazolidinediones

The present review summarizes the current advances in the biochemical and physiological aspects in the treatment of type 2 diabetes mellitus (DM2) with thiazolidinediones (TZDs). DM2 is a metabolic disorder characterized by hyperglycemia, triggering the abnormal activation of physiological pathways such as glucose autooxidation, polyol’s pathway, formation of advance glycation end (AGE) products, and glycolysis, leading to the overproduction of reactive oxygen species (ROS) and proinflammatory cytokines, which are responsible for the micro- and macrovascular complications of the disease. The treatment of DM2 has been directed toward the reduction of hyperglycemia using different drugs such as insulin sensitizers, as the case of TZDs, which are able to lower blood glucose levels and circulating triglycerides by binding to the nuclear peroxisome proliferator-activated receptor gamma (PPARγ) as full agonists. When TZDs interact with PPARγ, the receptor regulates the transcription of different genes involved in glucose homeostasis, insulin resistance, and adipogenesis. However, TZDs exhibit some adverse effects such as fluid retention, weight gain, hepatotoxicity, plasma-volume expansion, hemodilution, edema, bone fractures, and congestive heart failure, which limits their use in DM2 patients