On polyhedral projection and parametric programming

Submitted versio

A lattice study of the exclusive B→K∗γB \to K^* \gamma decay amplitude, using the Clover action at β=6.0\beta=6.0

We present the results of a numerical calculation of the $B\to K^* \gamma$ form factors. The results have been obtained by studying the relevant correlation functions at $\beta=6.0$, on an $18^3 \times 64$ lattice, using the ${\rm O(a)}$-improved fermion action, in the quenched approximation. From the study of the matrix element $$ we have obtained the form factor $T_1(0)$ which controls the exclusive decay rate. The results are compared with the recent results from CLEO. We also discuss the compatibility between the scaling laws predicted by the Heavy Quark Effective Theory (HQET) and pole dominance, by studying the mass- and $q^2$-dependence of the form factors. From our analysis, it appears that the form factors follow a mass behaviour compatible with the predictions of the HQET and that the $q^2$-dependence of $T_2$ is weaker than would be predicted by pole dominance.Comment: 17 pages, LaTeX + epsf.sty. Uuencoded, compressed, tar archive including the text and one postscript figur

Longitudinal changes in cerebral white matter microstructure in newly diagnosed systemic lupus erythematosus patients

Objectives. To evaluate longitudinal variations in diffusion tensor imaging (DTI) metrics of different white matter (WM) tracts of newly diagnosed SLE patients, and to assess whether DTI changes relate to changes in clinical characteristics over time.Methods. A total of 17 newly diagnosed SLE patients (19-55 years) were assessed within 24 months from diagnosis with brain MRI (1.5 T Philips Achieva) at baseline, and after at least 12 months. Fractional anisotropy, mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity values were calculated in several normal-appearing WM tracts. Longitudinal variations in DTI metrics were analysed by repeated measures analysis of variance. DTI changes were separately assessed for 21 WM tracts. Associations between longitudinal alterations of DTI metrics and clinical variables (SLEDAI-2K, complement levels, glucocorticoid dosage) were evaluated using adjusted Spearman correlation analysis.Results. Mean MD and RD values from the normal-appearing WM significantly increased over time (P = 0.019 and P = 0.021, respectively). A significant increase in RD (P = 0.005) and MD (P = 0.012) was found in the left posterior limb of the internal capsule; RD significantly increased in the left retro-lenticular part of the internal capsule (P = 0.013), and fractional anisotropy significantly decreased in the left corticospinal tract (P = 0.029). No significant correlation was found between the longitudinal change in DTI metrics and the change in clinical measures.Conclusion. Increase in diffusivity, reflecting a compromised WM tissue microstructure, starts in initial phases of the SLE disease course, even in the absence of overt neuropsychiatric (NP) symptoms. These results indicate the importance of monitoring NP involvement in SLE, even shortly after diagnosis.Neuro Imaging Researc

A High Statistics Lattice Calculation of fBstaticf^{static}_B at β=6.2\beta=6.2 Using the Clover Action

We present a calculation of $f_B$ in the static limit, obtained by numerical simulation of quenched QCD, at $\beta=6.2$ on a $18^3 \times 64$ lattice, using the SW-Clover quark action. The decay constant has been extracted by studying heavy(static)-light correlation functions of different smeared operators, on a sample of 220 gauge field configurations. We have obtained $f_B^{static}=(290 \pm 15 \pm 45)$ MeV, where the first error comes from the uncertainty in the determination of the matrix element and the second comes from the uncertainty in the lattice spacing. We also obtain $M_{B_s}-M_{B_d}= (70 \pm 10)$ MeV and $f^{stat}_{B_s}/f^{stat}_{B_d}=1.11(3)$. A comparison of our results with other calculations of the same quantity is made.Comment: 12 pages, LaTex, 3 figs. (figures not included; available upon request from [email protected]) ROME prep. 94/981, 18 February 199

Stay green trait-antioxidant status interrelationship in durum wheat (Triticum durum) flag leaf during post-flowering

Three independent durum wheat mutant lines that show delayed leaf senescence or stay-green (SG) phenotype, SG196, SG310 and SG504, were compared to the parental genotype, cv. Trinakria, with respect to the photosynthetic parameters and the cellular redox state of the flag leaf in the period from flowering to senescence. The SG mutants maintained their chlorophyll content and net photosynthetic rate for longer than Trinakria, thus revealing a functional SG phenotype. They also showed a better redox state as demonstrated by: (1) a lower rate of superoxide anion production due to generally higher activity of the antioxidant enzymes superoxide dismutase and catalase in all of the SG mutants and also of the total peroxidase in SG196; (2) a higher thiol content that can be ascribed to a higher activity of the NADPH-providing enzyme glucose-6-phosphate dehydrogenase in all of the SG mutants and also of the NADP?-dependent malic enzyme in SG196; (3) a lower pro-oxidant activity of lipoxygenase that characterises SG196 and SG504 mutants close to leaf senescence. Overall, these results show a general relationship in durum wheat between the SG phenotype and a better redox state. This relationship differs across the different SG mutants, probably as a consequence of the different set of altered genes underlying the SG trait in these independent mutant lines

Novel durum wheat genes up-regulated in response to a combination of heat and drought stress

We report the effect of heat, drought and combined stress on the expression of a group of genes that are up-regulated under these conditions in durum wheat (Triticum turgidum subsp. durum) plants. Modulation of gene expression was studied by cDNA-AFLP performed on RNAs extracted from flag leaves. By this approach, we identified several novel durum wheat genes whose expression is modulated under different stress conditions. We focused on a group of hitherto undescribed up-regulated genes in durum wheat, among these, 7 are up-regulated by heat, 8 by drought stress, 15 by combined heat and drought stress, 4 are up-regulated by both heat and combined stress, and 3 by both drought and combined stress. The functional characterization of these genes will provide new data that could help the developing of strategies aimed at improving durum wheat tolerance to field stress