Showing papers by "Ahmed Ali published in 2007"

Charmless nonleptonic B s decays to P P , P V , and V V final states in the perturbative QCD approach

Abstract: We calculate the $CP$-averaged branching ratios and $CP$-violating asymmetries of a number of two-body charmless hadronic decays ${\overline{B}}_{s}^{0}\ensuremath{\rightarrow}PP$, $PV$, $VV$ in the perturbative QCD (pQCD) approach to leading order in ${\ensuremath{\alpha}}_{s}$ (here $P$ and $V$ denote light pseudoscalar and vector mesons, respectively). The mixing-induced $CP$ violation parameters are also calculated for these decays. We also predict the polarization fractions of ${B}_{s}\ensuremath{\rightarrow}VV$ decays and find that the transverse polarizations are enhanced in some penguin-dominated decays such as ${\overline{B}}_{s}^{0}\ensuremath{\rightarrow}{K}^{*}{\overline{K}}^{*}$, ${K}^{*}\ensuremath{\rho}$. Some of the predictions worked out here can already be confronted with the recently available data from the CDF Collaboration on the branching ratios for the decays ${\overline{B}}_{s}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, ${\overline{B}}_{s}^{0}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$ and the $CP$ asymmetry in the decay ${\overline{B}}_{s}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and are found to be in agreement within the current errors. A large number of predictions for the branching ratios, $CP$ asymmetries, and vector-meson polarizations in ${\overline{B}}_{s}^{0}$ decays, presented in this paper and compared with the already existing results in other theoretical frameworks, will be put to stringent experimental tests in forthcoming experiments at Fermilab, CERN LHC, and Super $B$ factories.

Towards $B \to V \gamma$ Decays at NNLO in SCET

Abstract: We compute NNLO (${\cal O}(\alpha_s^2)$) corrections to the hard-scattering kernels entering the QCD factorization formula for $B\to V\gamma$ decays, where $V$ is a light vector meson We give complete NNLO results for the dipole operators $Q_7$ and $Q_8$, and partial results for $Q_1$ valid in the large-$\beta_0$ limit and neglecting the NNLO correction from hard spectator scattering Large perturbative logarithms in the hard-scattering kernels are identified and resummed using soft-collinear effective theory We use our results to estimate the branching fractions for $B\to K^*\gamma$ and $B_s\to \phi\gamma$ decays at NNLO and compare them with the current experimental data

Synthesis and three-dimensional qualitative structure selectivity relationship of 3,5-disubstituted-2,4-thiazolidinedione derivatives as COX2 inhibitors.

Abstract: In our effort for synthesis of selective COX2 inhibitors, certain new 2,4-thiazolidinedione derivatives were synthesized. It necessitates preparation of potassium salt of 2,4-thiazolidinedione 2, which condensed with intermediate 4a. The resulting 3-[2-(4-methylphenyl)-2-oxo-l-phenylethyl]-2,4-thiazolidinedione 8 was condensed with appropriate aldehyde to afford compounds 10a, 10i-l, 10o and 10p. Compounds (9a-l, 10a-n, 10p, 11 and 12) were obtained through the preparation of 5-arylmethylidene-2,4-thiazolidinediones 6a-p and reaction of its potassium salt 7a-p with compounds 4a, 4b, and 5. Some compounds displayed significant analgesic activity as compared to reference standards. The anti-inflammatory activity of the synthesized compounds revealed that intermediate 8 and compounds 9c, 10c and 10d showed good results. Compound 10c produced no significant mucosal injury. HipHop methodology of Catalyst program was used to build up hypothetical model of selective COX2 inhibitors followed by fitting the synthesized compounds to this model. Compounds 10c and 10d were suspected to be promising selective COX2 inhibitors. Also, compounds (6c, 8, 9a,c,d,k, 10a,c,d,k, 11 and 12) were docked into COX1 and COX2 X-ray structures, using DOCK6 program. Docking results suggested that several of these derivatives are active COX inhibitors with a significant preference for COX2.

Structural, magnetic, and electric properties of Dy1−xSrxCoO3−δ (0.65≤x≤0.90)

Abstract: The structural, magnetic, and electric properties of Dy1−xSrxCoO3−δ perovskite have been investigated systematically over the range of doping, 0.65≤x≤0.90. The Rietveld refinements of x-ray powder diffraction patterns at room temperature indicate that the samples with 0.65≤x≤0.75 show a tetragonal structure with I4/mmm group symmetry, while the compounds with 0.80≤x≤0.90 are cubic with pm3m group symmetry. Zero field-cooled magnetization, M(T), of 0.65≤x≤0.85 samples reveals a cusp at around room temperature. For all samples, M(T) increases rapidly below 50 K due to the paramagnetism of Dy sublattice. The inverse magnetic susceptibility, χ−1(T), was described by using Curie–Weiss law. The resistivity (ρ) data can be explained according to a three-dimensional variable range hopping model in a certain temperature range. The density of states at the vicinity of Fermi level is roughly estimated.

A possible CD1a Langerhans cell-mast cell interaction in chronic hyperplastic candidosis.

Abstract: AIMS: T lymphocyte-antigen-presenting cell (APC) interaction plays a central role in T lymphocyte activation and APC maturation. We therefore studied the CD1a-positive Langerhans cells with respect to receptor activator of nuclear factor kappa B ligand (RANKL)-positive cells in chronic hyperplastic candidosis (CHC). MATERIALS AND METHODS: Tissue sections of CHC were compared with leukoplakia and healthy oral mucosa using RANKL and CD1a monoclonal antibodies in an avidin-biotin peroxidase complex protocol. Two different antigen-retrieval protocols, pepsin preincubation and Tris-EDTA heat treatment, were used. RESULTS: CD1a-positive Langerhans cells were in healthy and leukoplakia epithelium found in the middle layer, but in CHC in all layers of the epithelium, at the basement membrane and as mononuclear round cells in the lamina propria. Use of pepsin digestion enabled studies of mast cells and their activation in the form of degranulation of RANKL. CONCLUSIONS: The numerical, morphological and topographical versatility of the CD1a-positive Langerhans cells in CHC can be clarified by dendritic cell (DC) recruitment into the epithelium. RANK-positive and RANKL-sensitive DCs have ample opportunity to interact with local T lymphocytes. Use of an optimized antigen-retrieval protocol enabled demonstration of an active engagement (degranulation) of mast cells, which represent a rapidly available source of soluble RANKL.

Rare meson decay in supersymmetric theory with nonconservation of R-parity

Abstract: The decay of mesons K + → π − l + l′+ and D + → K − l + l′+ (l, l′ = e, μ) involving a change of lepton number ΔL = 2 is considered in a supersymmetric extension of the standard model in which R-parity is not conserved due to trilinear Yukawa interactions. The obtained estimates for the probabilities of these decays are significantly lower than the direct experimental upper limits.

Theoretical Interest in B-Meson Physics at the B factories, Tevatron and the LHC

Abstract: We review the salient features of $B$-meson physics, with particular emphasis on the measurements carried out at the $B$-factories and Tevatron, theoretical progress in understanding these measurements in the context of the standard model, and anticipation at the LHC. Topics discussed specifically are the current status of the Cabibbo-Kobayashi-Maskawa matrix, the CP-violating phases, rare radiative and semileptonic decays, and some selected non-leptonic two-body decays of the $B$ mesons.

On the Wiener Polynomials of Some Trees

Abstract: 69 On the Wiener Polynomials of Some Trees Ali A. Ali Ahmed M. Ali aliazizali1933@yahoo.com ahmedgraph@uomosul.edu.iq College of Computer Sciences and Mathematics University of Mosul, Iraq Received on: 02/05/2006 Accepted on: 16/08/2006 ABSTRACT The Wiener index is a graphical invariant which has found many applications in chemistry. The Wiener Polynomial of a connected graph G is the generating function of the sequence (C(G,k)) whose derivative at x=1 is the Wiener index W(G) of G, in which C(G,k) is the number of pairs of vertices distance k apart. The Wiener Polynomials of star-like trees and other special trees are found in this paper; and hence a formula of the Wiener index for each such trees is obtained .

Wiener Polynomials for Multi-Rings Paraffin Structures

Abstract: Ahmed M. Ali ahmedgraph@uomosul.edu.iq College of Computer Sciences and Mathematics University of Mosul, Iraq Received on: 03/09/2006 Accepted on: 24/12/2006 ABSTRACT The distance between any two vertices u and v in a connected graph G is defined as the length of the shortest path between them, and it is denoted by d(u,v).The sum of distances for all unordered pairs of distinct vertices in G represents Wiener index. The number of pairs of vertices G which are distance k apart is denoted by d(G,k), it is clear that the number of d(G,k) is graphical invariant, and the Wiener polynomial of graph G is a generating function of the sequence d(G,k). In this paper, we find the Wiener polynomial of multi-circles of paraffin structural, and this formula which we obtained is better than the formula prove in [5] , because we are able to evaluate coefficients for any limited power of x without depending on the number of circles , and we find the Wiener index and average distance for this structural. Lastly, we contracted a MATLAB program to evaluate the Wiener polynomial coefficient ,Wiener index and average distance.