Optical monitoring of gamma-ray source fields

The three gamma-ray burst source fields GBS1028+46, GBS1205+24, and GBS2252-03 have been monitored for transient optical emission for a combined total of 52 hours. No optical events were seen. The limiting magnitude for the search was M sub V = 15.8 longer and M sub V = 17.0 for 6.0 s or longer

Discrete solvent effects on the effective interaction between charged colloids

Using computer simulations of two charged colloidal spheres with their counterions in a hard sphere solvent, we show that the granular nature of the solvent significantly influences the effective colloidal interaction. For divalent counterions, the total effective force can become attractive generated by counterion hydration, while for monovalent counterions the forces are repulsive and well-described by a solvent-induced colloidal charge renormalization. Both effects are not contained in the traditional "primitive" approaches but can be accounted for in a solvent-averaged primitive model.Comment: 4 pages, 3 figure

Identification and characterisation of resistance to the take-all fungus in wheat. PhD thesis, University of Exeter

Take-all disease, caused by the soil-borne fungus Gaeumannomyces graminis var. tritici, is the most devastating root disease of wheat around the world. Typical take-all symptoms show as black necrotic lesions on the roots and when severe can cause premature ripening and stunting of the wheat crop, resulting in poor grain quality and yield loss. Both cultural and chemical control methods are moderately successful at controlling take-all but plant material that would be useful for take-all control via a genetic approach has not been identified in the UK or elsewhere. The main aim of this project was to identify resistance to take-all within wheat (Triticum spp.);This study explored a new phenomenon in hexaploid wheat (Triticum aestivum) which restricts take-all inoculum build-up (TAB) in the soil during a first wheat crop and also explored tissue based resistance to take-all in hexaploid wheat and a related diploid wheat species, Triticum monococcum. Forty-nine elite wheat varieties were evaluated for their ability to build-up take-all inoculum in first wheat field trials using a soil core bioassay method, and pedigree and molecular marker analyses were carried out to investigate the genetic sources of the TAB trait. The effect of a low or high TAB first wheat variety on take-all disease and yield in a following second wheat crop was evaluated in crop rotation field trials. This work demonstrated that there are significant differences between current elite wheat varieties screened for the TAB trait and that there are probably multiple genetic sources of the trait. Take-all disease was lower and yields generally higher in a second wheat crop after a low TAB first wheat;The susceptibility of fifty elite hexaploid wheat varieties and thirty-four T. monococcum accessions to take-all was evaluated in third wheat field trials. Both T. aestivum (variety Hereford) and T. monococcum (MDR031 and MDR046) genotypes with some partial resistance to take-all were identified. A seedling pot test method as a screen for resistance was also explored but the results were found not to be closely related to the susceptibility of adult plants in field trials. The implications of these new findings for the control of take-all and further research are discussed

Identification and characterisation of resistance to take-all fungus in wheat (HGCA Student Report No. 31)

Take-all disease, caused by the soil-borne fungus Gaeumannomyces graminis var. tritici, is the most devastating root disease of wheat around the world. Typical take-all symptoms show as black necrotic lesions on the roots and when severe can cause premature ripening and stunting of the wheat crop, resulting in poor grain quality and yield loss. Both cultural and chemical control methods are moderately successful at controlling take-all. Identifying plant material that would be useful for take-all control via a genetic approach has not been successful in the UK or elsewhere. The main aim of this project was to identify resistance to take-all within wheat (Triticum spp.). This study explored a new phenomenon in hexaploid wheat (Triticum aestivum) which restricts take-all inoculum build-up (TAB) in the soil during a first wheat crop and also explored tissue-based resistance to take-all. Forty-nine elite wheat varieties were evaluated for their ability to build-up take-all inoculum in first wheat field trials using a soil core bioassay method. The effect of a low or high TAB first wheat variety on takeall disease and yield in a following second wheat crop was evaluated in crop rotation field trials. This work demonstrated that there are significant differences between current elite wheat varieties screened for the TAB trait and that there are probably multiple genetic sources of the trait. Take-all disease was lower and yields generally higher in a second wheat crop after a low TAB first wheat. The susceptibility of the hexaploid wheat varieties to take-all was evaluated in third wheat field trials. No variety was highly resistant but the variety Hereford displayed some potential partial resistance to take-all. The ability of wheat varieties to build-up take all inoculum in the soil during a first wheat crop was not related to their susceptibility to take-all root infection in the third wheat field trials. The implications of these new findings for the control of take-all via two distinct plant genetic approaches are discussed

Preoperative systemic inflammation predicts postoperative infectious complications in patients undergoing curative resection for colorectal cancer

The presence of systemic inflammation before surgery, as evidenced by the glasgow prognostic score (mGPS), predicts poor long-term survival in colorectal cancer. The aim was to examine the relationship between the preoperative mGPS and the development of postoperative complications in patients undergoing potentially curative resection for colorectal cancer. Patients (n=455) who underwent potentially curative resections between 2003 and 2007 were assessed consecutively, and details were recorded in a database. The majority of patients presented for elective surgery (85%) were over the age of 65 years (70%), were male (58%), were deprived (53%), and had TNM stage I/II disease (61%), had preoperative haemoglobin (56%), white cell count (87%) and mGPS 0 (58%) in the normal range. After surgery, 86 (19%) patients developed a postoperative complication; 70 (81%) of which were infectious complications. On multivariate analysis, peritoneal soiling (P<0.01), elevated preoperative white cell count (P<0.05) and mGPS (P<0.01) were independently associated with increased risk of developing a postoperative infection. In elective patients, only the mGPS (OR=1.75, 95% CI=1.17-2.63, P=0.007) was significantly associated with increased risk of developing a postoperative infection. Preoperative elevated mGPS predicts increased postoperative infectious complications in patients undergoing potentially curative resection for colorectal cancer

Strong Enhancement of Superconducting Correlation in a Two-Component Fermion Gas

We study high-density electron-hole (e-h) systems with the electron density slightly larger than the hole density. We find a new superconducting phase, in which the excess electrons form Cooper pairs moving in an e-h BCS phase. The coexistence of the e-h and e-e orders is possible because e and h have opposite charges, whereas analogous phases are impossible in the case of two fermion species that have the same charge or are neutral. Most strikingly, the e-h order enhances the superconducting e-h order parameter by more than one order of magnitude as compared with that given by the BCS formula, for the same value of the effective e-e attractive potential \lambda^{ee}. This new phase should be observable in an e-h system created by photoexcitation in doped semiconductors at low temperatures.Comment: 5 pages including 5 PostScript figure

Neighborhood sampling: how many streets must an auditor walk?

This study tested the representativeness of four street segment sampling protocols using the Pedestrian Environment Data Scan (PEDS) in eleven neighborhoods surrounding public housing developments in Houston, TX. The following four street segment sampling protocols were used (1) all segments, both residential and arterial, contained within the 400 meter radius buffer from the center point of the housing development (the core) were compared with all segments contained between the 400 meter radius buffer and the 800 meter radius buffer (the ring); all residential segments in the core were compared with (2) 75% (3) 50% and (4) 25% samples of randomly selected residential street segments in the core. Analyses were conducted on five key variables: sidewalk presence; ratings of attractiveness and safety for walking; connectivity; and number of traffic lanes. Some differences were found when comparing all street segments, both residential and arterial, in the core to the ring. Findings suggested that sampling 25% of residential street segments within the 400 m radius of a residence sufficiently represents the pedestrian built environment. Conclusions support more cost effective environmental data collection for physical activity research

Properties of the superconducting state in a two-band model

Eliashberg theory is used to investigate the range of thermodynamic properties possible within a two-band model for s-wave superconductivity and to identify signatures of its two-band nature. We emphasize dimensionless BCS ratios (those for the energy gaps, the specific heat jump and the negative of its slope near Tc, the thermodynamic critical field Hc(0), and the normalized slopes of the critical field and the penetration depth near Tc), which are no longer universal even in weak coupling. We also give results for temperature-dependent quantities, such as the penetration depth and the energy gap. Results are presented both for microscopic parameters appropriate to MgB2 and for variations away from these. Strong coupling corrections are identified and found to be significant. Analytic formulas are provided which show the role played by the anisotropy in coupling in some special limits. Particular emphasis is placed on small interband coupling and on the opposite limit of no diagonal coupling. The effect of impurity scattering is considered, particularly for the interband case.Comment: 20 pages, 14 figures, final version accepted in PR

Electronic Structure of New Multiple Band Pt-Pnictide Superconductors APt3P

We report LDA calculated band structure, densities of states and Fermi surfaces for recently discovered Pt-pnictide superconductors APt3P (A=Ca,Sr,La), confirming their multiple band nature. Electronic structure is essentially three dimensional, in contrast to Fe pnictides and chalcogenides. LDA calculated Sommerfeld coefficient agrees rather well with experimental data, leaving little space for very strong coupling superconductivity, suggested by experimental data on specific heat of SrPt3P. Elementary estimates show, that the values of critical temperature can be explained by rather weak or moderately strong coupling, while the decrease of superconducting transition temperature Tc from Sr to La compound can be explained by corresponding decrease of total density of states at the Fermi level N(E_F). The shape of the density of states near the Fermi level suggests that in SrPt3P electron doping (such as replacement Sr by La) decreases N(E_F) and Tc, while hole doping (e.g. partial replacement of Sr with K, Rb or Cs, if possible) would increase N(E_F) and possibly Tc.Comment: 5 pages, 5 figure

Generating Non-Linear Interpolants by Semidefinite Programming

Interpolation-based techniques have been widely and successfully applied in the verification of hardware and software, e.g., in bounded-model check- ing, CEGAR, SMT, etc., whose hardest part is how to synthesize interpolants. Various work for discovering interpolants for propositional logic, quantifier-free fragments of first-order theories and their combinations have been proposed. However, little work focuses on discovering polynomial interpolants in the literature. In this paper, we provide an approach for constructing non-linear interpolants based on semidefinite programming, and show how to apply such results to the verification of programs by examples.Comment: 22 pages, 4 figure