Semileptonic Decays of Heavy Mesons: A Status Report

We present intermediate results on our ongoing investigation concerning semileptonic decays of heavy pseudoscalar mesons into pseudoscalar and vector mesons. The corresponding formfactors are evaluated at several momenta and appropriate combinations of four light and four heavy quarks, which are chosen to allow for an extrapolation into the B Meson region. In order to obtain clear groundstate signals we apply gauge invariant ``Wuppertal'' smearing to the quarks. The analysis is based on 32 quenched gauge configurations of size $24^3 \times 64$ at $\beta=6.3$, with Wilson fermions.Comment: 3 pages, uuencoded, contribution to Lat 9

Nanoscale quantum dot infrared sensors with photonic crystal cavity

We report high performance infrared sensors that are based on intersubband transitions in nanoscale self-assembled quantum dots combined with a microcavity resonator made with a high-index-contrast two-dimensional photonic crystal. The addition of the photonic crystal cavity increases the photocurrent, conversion efficiency, and the signal to noise ratio (represented by the specific detectivity D*) by more than an order of magnitude. The conversion efficiency of the detector at Vb=–2.6 V increased from 7.5% for the control sample to 95% in the PhC detector. In principle, these photonic crystal resonators are technology agnostic and can be directly integrated into the manufacturing of present day infrared sensors using existing lithographic tools in the fabrication facility

Ischemic preconditioning of the muscle reduces the metaboreflex response of the knee extensors

Purpose: This study investigated the effect of ischemic preconditioning (IP) on metaboreflex activation following dynamic leg extension exercise in a group of healthy participants. Method: Seventeen healthy participants were recruited. IP and SHAM treatments (3 × 5 min cuff occlusion at 220 mmHg or 20 mmHg, respectively) were administered in a randomized order to the upper part of exercising leg’s thigh only. Muscle pain intensity (MP) and pain pressure threshold (PPT) were monitored while administrating IP and SHAM treatments. After 3 min of leg extension exercise at 70% of the maximal workload, a post-exercise muscle ischemia (PEMI) was performed to monitor the discharge group III/IV muscle afferents via metaboreflex activation. Hemodynamics were continuously recorded. MP was monitored during exercise and PEMI. Results: IP significantly reduced mean arterial pressure compared to SHAM during metaboreflex activation (mean ± SD, 109.52 ± 7.25 vs. 102.36 ± 7.89 mmHg) which was probably the consequence of a reduced end diastolic volume (mean ± SD, 113.09 ± 14.25 vs. 102.42 ± 9.38 ml). MP was significantly higher during the IP compared to SHAM treatment, while no significant differences in PPT were found. MP did not change during exercise, but it was significantly lower during the PEMI following IP (5.10 ± 1.29 vs. 4.00 ± 1.54). Conclusion: Our study demonstrated that IP reduces hemodynamic response during metaboreflex activation, while no effect on MP and PPT were found. The reduction in hemodynamic response was likely the consequence of a blunted venous return

One-loop renormalization of heavy-light currents

We calculate the mass dependent renormalization factors of heavy-light bilinears at one-loop order of perturbation theory, when the heavy quark is treated with the Fermilab formalism. We present numerical results for the Wilson and Sheikholeslami-Wohlert actions, with and without tree-level rotation. We find that in both cases our results smoothly interpolate from the static limit to the massless limit. We also calculate the mass dependent Brodsky-Lepage-Mackenzie scale $q^*$, with and without tadpole-improvement.Comment: Lattice2001(improvement), 3 pages, 4 figure

Ecologia e distribuzione di Chamaerops humilis L. (Arecaceae) nella Sicilia nord-orientale

I settori costieri e collinari della Sicilia nord-orientale e delle Eolie sono stati esplorati ai fini della raccolta di informazioni aggiornate sulla distribuzione dei popolamenti di palma nana e sulle caratteristiche ecologiche delle stazioni che li ospitano. I risultati delle indagini di campo sono stati integrati dalla verifica dei toponimi locali legati ai nomi dialettali della specie. Si con- ferma la totale assenza della palma nana lungo l’intero settore costiero dei Nebrodi. Dei nove popolamenti accertati, quattro si trovano alle Eolie, due sul versante ionico e tre sul versante tir- renico dei Peloritani; uno di questi ultimi, localizzato su Capo Calavà, risulta inedito. La conco- mitanza di diversi fattori di stress e l’impatto plurisecolare dell’uomo è probabilmente responsa- bile del carattere relittuale di gran parte dei popolamenti considerati, che danno vita a consorzi molto discontinui, e sono rappresentati da piccoli nuclei che formano aggruppamenti semplifi- cati sotto un profilo fisionomico e poveri in termini floristici, perlopiù confinati in contesti roc- ciosi costieri. Di contro, la recente espansione della palma nana registrata a Lipari sembra dipen- dere dalla cessazione delle attività agricole. Infine, i casi di naturalizzazione registrati a Milazzo, Tindari, Panarea, Scaletta Zanclea e Taormina derivano dal suo uso come pianta ornamentale e pongono in risalto l’urgente necessità di regolamentare la sua introduzione per evitare l’inquina- mento genetico dei nuclei autoctoni.The coastal and hilly sectors of NE Sicily and the Aeolian Archipelago have been explored, in order to obtain up-to-date information on the distribution of the populations of Chamaerops humilis and on their site conditions. In addition to the field surveys, any local toponym possibly related to the Sicilian vernacular names of the dwarf palm was checked and verified throughout the investigat- ed area. The total absence of the species along the coasts of Nebrodi Massif is confirmed. Of the 9 extant populations, 4 are located on the Aeolian Islands, 2 along the Ionian coast and 3 along the Tyrrhenian coast of Peloritani Mountains: among them, the one of Capo Calavà represents a new record. The co-occurrence of centuries-long human disturbance and several forms of envi- ronmental stresses could be the reason for the relict connotation of most of the considered popu- lations, which also are very discontinuous and consisting of small patches formed by a few indi- viduals, in simplified and species-poor assemblages, mostly found on sea-facing rocky cliffs. On the other hand, the recent spread of Chamaerops humilis in Lipari could be related to the aban- donment of agricultural practices. Finally, the naturalisation cases recorded in Milazzo, Tindari, Panarea, Scaletta Zanclea and Taormina, where the dwarf palm escaped from public and private gardens, point out the urgent need of regulating its introduction, in order to avoid the genetic pol- lution of the autochthonous populations

The Kaon B-parameter with the Wilson Quark Action using Chiral Ward Identities

We present a detailed description of the method and results of our calculation of the kaon B parameter using the Wilson quark action in quenched QCD at $\beta=5.9-6.5$. The mixing problem of the $\Delta s=2$ four-quark operators is solved non-perturbatively with full use of chiral Ward identities. We find $B_K(NDR, 2 GeV)=0.562(64)$ in the continuum limit, which agrees with the value obtained with the Kogut-Susskind quark action.Comment: 10 pages, latex source-file, 10 figures as epsf-file, uses espcrc2.sty. Talk given at International Workshop on Lattice QCD on Parallel Computers, 10-15 Mar 1997, Tsukuba, Japa

QCD chiral Lagrangian on the lattice, strong coupling expansion and Ward identities with Wilson fermions

We discuss a general strategy to compute the coefficients of the QCD chiral Lagrangian using lattice QCD with Wilson fermions. This procedure requires the introduction of a lattice chiral Lagrangian as an intermediate step in the calculation. The QCD chiral Lagrangian is then obtained by expanding the lattice effective theory in increasing powers of the lattice spacing and the external momenta. In order to investigate the consequences of the chiral symmetry breaking induced by the Wilson term, we study the lattice chiral Lagrangian at the leading order of the strong coupling and large $N$ expansion. We show that the effects of the Wilson term can be conveniently taken into account, in the lattice effective theory, by a suitable renormalization procedure. In particular, we show that, at the leading order of the strong coupling and large N expansion, the chiral symmetry is exactly recovered on the lattice provided that the bare quark mass and the lattice operators are properly renormalized.Comment: 45 pages, no figures. Latex fil

Renormalization Constants of Quark Operators for the Non-Perturbatively Improved Wilson Action

We present the results of an extensive lattice calculation of the renormalization constants of bilinear and four-quark operators for the non-perturbatively O(a)-improved Wilson action. The results are obtained in the quenched approximation at four values of the lattice coupling by using the non-perturbative RI/MOM renormalization method. Several sources of systematic uncertainties, including discretization errors and final volume effects, are examined. The contribution of the Goldstone pole, which in some cases may affect the extrapolation of the renormalization constants to the chiral limit, is non-perturbatively subtracted. The scale independent renormalization constants of bilinear quark operators have been also computed by using the lattice chiral Ward identities approach and compared with those obtained with the RI-MOM method. For those renormalization constants the non-perturbative estimates of which have been already presented in the literature we find an agreement which is typically at the level of 1%.Comment: 36 pages, 13 figures. Minor changes in the text and in one figure. Accepted for publication on JHE