Theoretical study of the synthesis of superheavy nuclei with Z= 119 and 120 in heavy-ion reactions with trans-uranium targets

By using a newly developed di-nuclear system model with a dynamical potential energy surface---the DNS-DyPES model, hot fusion reactions for synthesizing superheavy nuclei (SHN) with the charge number Z = 112-120 are studied. The calculated evaporation residue cross sections are in good agreement with available data. In the reaction 50Ti+249Bk -> (299-x)119 + xn, the maximal evaporation residue (ER) cross section is found to be about 0.11 pb for the 4n-emission channel. For projectile-target combinations producing SHN with Z=120, the ER cross section increases with the mass asymmetry in the incident channel increasing. The maximal ER cross sections for 58Fe+244Pu and 54Cr + 248Cm are relatively small (less than 0.01 pb) and those for 50Ti+249Cf and 50Ti+251Cf are about 0.05 and 0.25 pb, respectively.Comment: 6 pages, 5 figures; Phys. Rev. C, in pres

A comprehensive analysis of Swift/XRT data: I. Apparent spectral evolution of GRB X-ray tails

An early steep decay component following the prompt GRBs is commonly observed in {\em Swift} XRT light curves, which is regarded as the tail emission of the prompt gamma-rays. Prompted by the observed strong spectral evolution in the tails of GRBs 060218 and 060614, we present a systematic time-resolved spectral analysis for the {\em Swift} GRB tails detected between 2005 February and 2007 January. We select a sample of 44 tails that are bright enough to perform time-resolved spectral analyses. Among them 11 tails are smooth and without superimposing significant flares, and their spectra have no significant temporal evolution. We suggest that these tails are dominated by the curvature effect of the prompt gamma-rays due to delay of propagation of photons from large angles with respect to the line of sight . More interestingly, 33 tails show clear hard-to-soft spectral evolution, with 16 of them being smooth tails directly following the prompt GRBs,while the others being superimposed with large flares. We focus on the 16 clean, smooth tails and consider three toy models to interpret the spectral evolution. The curvature effect of a structured jet and a model invoking superposition of the curvature effect tail and a putative underlying soft emission component cannot explain all the data. The third model, which invokes an evolving exponential spectrum, seems to reproduce both the lightcurve and the spectral evolution of all the bursts, including GRBs 060218 and 060614. More detailed physical models are called for to understand the apparent evolution effect.Comment: 13 pages in emulateapj style,6 figures, 1 table, expanded version, matched to published version, ApJ, 2007, in press. This is the first paper of a series. Paper II see arXiv:0705.1373 (ApJ,2007, in press

RHF and DFT study of the molecular properties of the malaria drug proguanil in different environments

The molecular geometries of the common malaria drug Proguanil in gas phase, water and Ethanol have been studied using ab- initio Quantum Chemical calculations at the Restricted Hartree-Fock (RHF) level of theory by employing 6-31+G basis set. Density functional calculation at the Becke3LYP (B3LYP) have been carried out by employing 6-31+G basis set for inclusion of electron correlation. The molecular structure, dipole moment, charge transfer, polarizability and energy were calculated. The shortest bonds were found to be H10-N20, H11-N17, H12-N16, N18-H22 with bond lengths less than 1 Å . The dipole moments, thermal energies and polarizabilities were found to be higher in water compared to gas phase and ethanol at both levels of theory.Keywords: Proguanil, Molecular Dynamics, ab initio, DFT Calculations

Efficient path-based computations on pedigree graphs with compact encodings

A pedigree is a diagram of family relationships, and it is often used to determine the mode of inheritance (dominant, recessive, etc.) of genetic diseases. Along with rapidly growing knowledge of genetics and accumulation of genealogy information, pedigree data is becoming increasingly important. In large pedigree graphs, path-based methods for efficiently computing genealogical measurements, such as inbreeding and kinship coefficients of individuals, depend on efficient identification and processing of paths. In this paper, we propose a new compact path encoding scheme on large pedigrees, accompanied by an efficient algorithm for identifying paths. We demonstrate the utilization of our proposed method by applying it to the inbreeding coefficient computation. We present time and space complexity analysis, and also manifest the efficiency of our method for evaluating inbreeding coefficients as compared to previous methods by experimental results using pedigree graphs with real and synthetic data. Both theoretical and experimental results demonstrate that our method is more scalable and efficient than previous methods in terms of time and space requirements

Temporal Profiles and Spectral Lags of XRF 060218

The spectral and temporal properties of the non-thermal emission ofthe nearby XRF 060218 in 0.3-150 keV band are studied. We show that both the spectral energy distribution and the light curve properties suggest the same origin of the non-thermal emission detected by {\em Swift} BAT and XRT. This event has the longest pulse duration and spectral lag observed to date among the known GRBs. The pulse structure and its energy dependence are analogous to typical GRBs. By extrapolating the observed spectral lag to the {\em CGRO/BATSE} bands we find that the hypothesis that this event complies with the same luminosity-lag relation with bright GRBs cannot be ruled out at $2\sigma$ significance level. These intriguing facts, along with its compliance with the Amati-relation, indicate that XRF 060218 shares the similar radiation physics as typical GRBs.Comment: 9 pages in emulateapj format, including 4 figures and 1 table, accepted for publication in ApJ Letter

A Qualified Kolmogorovian Account of Probabilistic Contextuality

We describe a mathematical language for determining all possible patterns of contextuality in the dependence of stochastic outputs of a system on its deterministic inputs. The central notion is that of all possible couplings for stochastically unrelated outputs indexed by mutually incompatible values of inputs. A system is characterized by a pattern of which outputs can be "directly influenced" by which inputs (a primitive relation, hypothetical or normative), and by certain constraints imposed on the outputs (such as Bell-type inequalities or their quantum analogues). The set of couplings compatible with these constraints represents a form of contextuality in the dependence of outputs on inputs with respect to the declared pattern of direct influences.Comment: Lecture Notes in Computer Science 8369, 201-212 (2014

Troubleshooting Arterial-Phase MR Images of Gadoxetate Disodium-Enhanced Liver.

Gadoxetate disodium is a widely used magnetic resonance (MR) contrast agent for liver MR imaging, and it provides both dynamic and hepatobiliary phase images. However, acquiring optimal arterial phase images at liver MR using gadoxetate disodium is more challenging than using conventional extracellular MR contrast agent because of the small volume administered, the gadolinium content of the agent, and the common occurrence of transient severe motion. In this article, we identify the challenges in obtaining high-quality arterial-phase images of gadoxetate disodium-enhanced liver MR imaging and present strategies for optimizing arterial-phase imaging based on the thorough review of recent research in this field

A Comprehensive Analysis of Swift/XRT Data: III. Jet Break Candidates in X-ray and Optical Afterglow Lightcurves

The Swift/XRT data of 179 GRBs (from 050124 to 070129) and the optical afterglow data of 57 pre- and post-Swift GRBs are analyzed, in order to systematically investigate the jet-like breaks in the X-ray and optical afterglow lightcurves. We find that not a single burst can be included in the ``Platinum'' sample, in which the data satisfy all the criteria of a jet break. By releasing one or more requirements to define a jet break, some candidates of various degrees could be identified. In the X-ray band, 42 out of the 103 well-sampled X-ray lightcurves have a decay slope of the post-break segment >1.5 (``Bronze'' sample), and 27 of them also satisfy the closure relations of the forward models (``Silver'' sample). The numbers of the ``Bronze'' and ``Silver'' candidates in the optical lightcurves are 27 and 23, respectively. Thirteen bursts have well-sampled optical and X-ray lightcurves, but only seven cases are consistent with an achromatic break, but even in these cases only one band satisfies the closure relations (``Gold'' sample). The observed break time in the XRT lightcurves is systematically earlier than that in the optical bands. All these raise great concerns in interpreting the jet-like breaks as jet breaks and further inferring GRB energetics from these breaks. By assuming that these breaks are jet breaks, we perform a similar analysis as previous work to calculate the jet opening angle (theta_j) and energetics (E_k) with the ``Silver'' and ``Gold'' jet break candidates. The derived E_K distribution reveals a much larger scatter than the pre-Swift sample. A tentative anti-correlation between theta_j and E_{K,iso} is found for both the pre-Swift and Swift GRBs, indicating that the E_K could still be quasi-universal, if the breaks in discussion are indeed jet breaks(abridge).Comment: 48 pages, including 5 tables and 8 figures. Accepted for publication in ApJ. This is the third paper of a series. Paper I and II see astro-ph/0612246 (ApJ, 2007, 666,1002) and arXiv:0705.1373 (ApJ, 2007, 669, n2,in press

Path-Counting Formulas for Generalized Kinship Coefficients and Condensed Identity Coefficients

An important computation on pedigree data is the calculation of condensed identity coefficients, which provide a complete description of the degree of relatedness of two individuals. The applications of condensed identity coefficients range from genetic counseling to disease tracking. Condensed identity coefficients can be computed using linear combinations of generalized kinship coefficients for two, three, four individuals, and two pairs of individuals and there are recursive formulas for computing those generalized kinship coefficients (Karigl, 1981). Path-counting formulas have been proposed for the (generalized) kinship coefficients for two (three) individuals but there have been no path-counting formulas for the other generalized kinship coefficients. It has also been shown that the computation of the (generalized) kinship coefficients for two (three) individuals using path-counting formulas is efficient for large pedigrees, together with path encoding schemes tailored for pedigree graphs. In this paper, we propose a framework for deriving path-counting formulas for generalized kinship coefficients. Then, we present the path-counting formulas for all generalized kinship coefficients for which there are recursive formulas and which are sufficient for computing condensed identity coefficients. We also perform experiments to compare the efficiency of our method with the recursive method for computing condensed identity coefficients on large pedigrees

Space-like (vs. time-like) collinear limits in QCD: is factorization violated?

We consider the singular behaviour of QCD scattering amplitudes in kinematical configurations where two or more momenta of the external partons become collinear. At the tree level, this behaviour is known to be controlled by factorization formulae in which the singular collinear factor is universal (process independent). We show that this strict (process-independent) factorization is not valid at one-loop and higher-loop orders in the case of the collinear limit in space-like regions (e.g., collinear radiation from initial-state partons). We introduce a generalized version of all-order collinear factorization, in which the space-like singular factors retain some dependence on the momentum and colour charge of the non-collinear partons. We present explicit results on one-loop and two-loop amplitudes for both the two-parton and multiparton collinear limits. At the level of square amplitudes and, more generally, cross sections in hadron--hadron collisions, the violation of strict collinear factorization has implications on the non-abelian structure of logarithmically-enhanced terms in perturbative calculations (starting from the next-to-next-to-leading order) and on various factorization issues of mass singularities (starting from the next-to-next-to-next-to-leading order).Comment: 81 pages, 5 figures, typos corrected in the text, few comments added and inclusion of NOTE ADDED on recent development