Gluon Fragmentation into Heavy Quarkonium

The dominant production mechanism for heavy quark-antiquark bound states in very high energy processes is fragmentation, the splitting of a high energy parton into a quarkonium state and other partons. We show that the fragmentation functions $D(z,\mu)$ describing these processes can be calculated using perturbative QCD. We calculate the fragmentation functions for a gluon to split into S-wave quarkonium states to leading order in the QCD coupling constant. The leading logarithms of $\mu/m_Q$, where $\mu$ is the factorization scale and $m_Q$ is the heavy quark mass, are summed up using Altarelli-Parisi evolution equations.Comment: LateX 11 pages (3 figures available upon request). NUHEP-TH-92-2

Line-integral representations of the displacement and stress fields due to an arbitrary Volterra dislocation loop in a transversely isotropic elastic full space

AbstractTransversely isotropic materials or hexagonal crystals are commonly utilized in various engineering fields; however, dislocation solutions for such special materials have not been fully developed. In this paper, we present a comprehensive study on this important topic, where only Volterra dislocations of the translational type are considered. Based on the potential theory of linear elasticity, we extend the well-known Burgers displacement equation for an arbitrarily shaped dislocation loop in an isotropic elastic full space to the transversely isotropic case. Both the induced displacements and stresses are expressed uniformly in terms of simple and explicit line integrals along the dislocation loop. We introduce three quasi solid angles to describe the displacement discontinuities over the dislocation surface and extract a simple step function out of these angles to characterize the dependence of the displacements on the configuration of the dislocation surface. We also give a new explicit formula for calculating accurately and efficiently the traditional solid angle of an arbitrary polygonal dislocation loop. From the present line-integral representations, exact closed-form solutions in terms of elementary functions are further obtained in a unified way for the displacement and stress fields due to a straight dislocation segment of arbitrary orientation. The non-uniqueness of the elastic field solution due to an open dislocation segment is rigorously discussed and demonstrated. For a circular dislocation loop parallel to the plane of isotropy, a new explicit expression of the induced elastic field is presented in terms of complete elliptic integrals. Several numerical examples are also provided as illustration and verification of the derived dislocation solutions, which further show the importance of material anisotropy on the dislocation-induced elastic field, and reveal the non-uniqueness feature of the elastic field due to a straight dislocation segment

Line-integral representations for the elastic displacements, stresses and interaction energy of arbitrary dislocation loops in transversely isotropic bimaterials

AbstractThe elastic displacements, stresses and interaction energy of arbitrarily shaped dislocation loops with general Burgers vectors in transversely isotropic bimaterials (i.e. joined half-spaces) are expressed in terms of simple line integrals for the first time. These expressions are very similar to their isotropic full-space counterparts in the literature and can be easily incorporated into three-dimensional (3D) dislocation dynamics (DD) simulations for hexagonal crystals with interfaces/surfaces. All possible degenerate cases, e.g. isotropic bimaterials and isotropic half-space, are considered in detail. The singularities intrinsic to the classical continuum theory of dislocations are removed by spreading the Burgers vector anisotropically around every point on the dislocation line according to three particular spreading functions. This non-singular treatment guarantees the equivalence among different versions of the energy formulae and their consistency with the stress formula presented in this paper. Several numerical examples are provided as verification of the derived dislocation solutions, which further show significant influence of material anisotropy and bimaterial interface on the elastic fields and interaction energy of dislocation loops

P-Wave Charmonium Production in B-Meson Decays

We calculate the decay rates of $B$ mesons into P-wave charmonium states using new factorization formulas that are valid to leading order in the relative velocity of the charmed quark and antiquark and to all orders in the running coupling constant of QCD. We express the production rates for all four P states in terms of two nonperturbative parameters, the derivative of the wavefunction at the origin and another parameter related to the probability for a charmed-quark-antiquark pair in a color-octet S-wave state to radiate a soft gluon and form a P-wave bound state. Using existing data on $B$ meson decays into $\chi_{c1}$ to estimate the color-octet parameter, we find that the color-octet mechanism may account for a significant fraction of the $\chi_{c1}$ production rate and that $B$ mesons should decay into $\chi_{c2}$ at a similar rate.Comment: 14 page

Inferring Multiple Graphical Structures

Gaussian Graphical Models provide a convenient framework for representing dependencies between variables. Recently, this tool has received a high interest for the discovery of biological networks. The literature focuses on the case where a single network is inferred from a set of measurements, but, as wetlab data is typically scarce, several assays, where the experimental conditions affect interactions, are usually merged to infer a single network. In this paper, we propose two approaches for estimating multiple related graphs, by rendering the closeness assumption into an empirical prior or group penalties. We provide quantitative results demonstrating the benefits of the proposed approaches. The methods presented in this paper are embeded in the R package 'simone' from version 1.0-0 and later

Sodium aluminate activated waste glass:Reduced efflorescence behavior by C(N)−A−S−H transformation

Waste glass has been highly used in alkali activated materials, but the efflorescence behavior remains an intractable issue. This study investigates the effect of sodium aluminate as an activator to activate waste glass with the aim to mitigate the efflorescence behavior, and blast furnace slag is used as calcium source as well as to promote the early age strength. The gel structure (reaction product) was characterized by 29Si and 27Al NMR, subsequently the efflorescence behavior was investigated. Results show that sodium aluminate provides more AlOH4−, which acts as cross-linking agents, linking silicate tetrahedra to form a three-dimensional gel network. A longer mean chain length of gels increases hydrogen sites at end-chain Q1 silicate species, which can be replaced by cations along the silicate chain. The promoted formation of C(N)−A−S−H gel captures more Na+ in the pore solution, contributing to a limited Na+ leaching and higher resistance towards efflorescence.</p

Adsorption properties of several materials for solar adsorption cooling system

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.It is important for an adsorption refrigeration system to use an appropriate adsorption material and the matched refrigerant. In the present study, the adsorption characteristic of the allochroic silica gel and three kinds of zeolite material to water-vapor have been investigated experimentally. Upon analyzing the variation of the material adsorption capacity exposed in moist air atmosphere of controlled temperature and humidity, the adsorption characteristic to water-vapor is verified, and the influence of the temperature and the pressure are correlated. The results show that the dynamic adsorption characteristic and the adsorption isotherm of the tested material is closely related to its microstructure such as the BET surface area, the distribution of the pore diameter, the porosity, and the bulk density, etc. In view of the application in the solar adsorption air conditioning, 5A-II and 13X-II zeolite shows relatively fast adsorption rate and their time to adsorption saturation state is short. The allochroic silica gel, 5A-II and 13X-II zeolite is of higher adsorption capacity, while the dynamic adsorption characteristic of 5A-I and ZSM-5 zeolite is more sensitive to the change of pressure. The adsorption isotherm of allochroic silica gel follows an exponential function and ZSM-5 and 5A-I zeolites shows a “S" curve, The latter may be more suitable for the solar adsorption cooling system in summer.cf201

Exact Master Equation and Non-Markovian Decoherence for Quantum Dot Quantum Computing

In this article, we report the recent progress on decoherence dynamics of electrons in quantum dot quantum computing systems using the exact master equation we derived recently based on the Feynman-Vernon influence functional approach. The exact master equation is valid for general nanostructure systems coupled to multi-reservoirs with arbitrary spectral densities, temperatures and biases. We take the double quantum dot charge qubit system as a specific example, and discuss in details the decoherence dynamics of the charge qubit under coherence controls. The decoherence dynamics risen from the entanglement between the system and the environment is mainly non-Markovian. We further discuss the decoherence of the double-dot charge qubit induced by quantum point contact (QPC) measurement where the master equation is re-derived using the Keldysh non-equilibrium Green function technique due to the non-linear coupling between the charge qubit and the QPC. The non-Markovian decoherence dynamics in the measurement processes is extensively discussed as well.Comment: 15 pages, Invited article for the special issue "Quantum Decoherence and Entanglement" in Quantum Inf. Proces

Leaf Extracts of Calocedrus formosana (Florin) Induce G2/M Cell Cycle Arrest and Apoptosis in Human Bladder Cancer Cells

Calocedrus formosana (Florin) bark acetone/ethylacetate extracts are known to exert an antitumor effect on some human cancer cell lines, but the mechanism is yet to be defined. The aim of this study was to determine the effects of Florin leaf methanol extracts on the growth and apoptosis of human bladder cancer cell lines. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay showed that the growth of these bladder cancer cells was potently inhibited by the Florin leaf extracts. The cell cycle of these extract-treated cells (TCCSUP cells) was arrested at the G2/M phase as determined by flow cytometry. Western blot analysis revealed the increases of cyclin B1 and Cdc2 kinase levels, alone with the decrease of phosphorylated Cdc2 kinase, after treating these cells with the extracts. An immunofluorescence assessment of β-tubulin showed decreased levels of polymerized tubulin in treated cells. However, the proteolytic cleavage of poly ADP-ribose polymerase and the activation of caspase-3/-8/-9 were all increased upon treatments of extracts. The concurrent increase of Bax and decrease of Bcl-2 levels indicated that the extracts could induce apoptosis in these treated cells. Taken together, these results suggest that the Florin leaf extracts may be an effective antibladder cancer agent

Gastric cancer and Helicobacter pylori: a combined analysis of 12 case control studies nested within prospective cohorts

BACKGROUND: The magnitude of the association between Helicobacter pylori and incidence of gastric cancer is unclear. H pylori infection and the circulating antibody response can be lost with development of cancer; thus retrospective studies are subject to bias resulting from classifi- cation of cases as H pylori negative when they were infected in the past. AIMS: To combine data from all case control studies nested within prospective cohorts to assess more reliably the relative risk of gastric cancer associated with H pylori infection.To investigate variation in relative risk by age, sex, cancer type and subsite, and interval between blood sampling and cancer diagnosis. METHODS: Studies were eligible if blood samples for H pylori serology were collected before diagnosis of gastric cancer in cases. Identified published studies and two unpublished studies were included. Individual subject data were obtained for each. Matched odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated for the association between H pylori and gastric cancer. RESULTS: Twelve studies with 1228 gastric cancer cases were considered. The association with H pylori was restricted to noncardia cancers (OR 3.0; 95% CI 2.3–3.8) and was stronger when blood samples for H pylori serology were collected 10+ years before cancer diagnosis (5.9; 3.4–10.3). H pylori infection was not associated with an altered overall risk of cardia cancer (1.0; 0.7–1.4). CONCLUSIONS: These results suggest that 5.9 is the best estimate of the relative risk of non-cardia cancer associated with H pylori infection and that H pylori does not increase the risk of cardia cancer. They also support the idea that when H pylori status is assessed close to cancer diagnosis, the magnitude of the non-cardia association may be underestimated