Constraining supersymmetry from the satellite experiments

In this paper we study the detectability of $\gamma$-rays from dark matter annihilation in the subhalos of the Milky Way by the satellite-based experiments, EGRET and GLAST. We work in the frame of supersymmetric extension of the standard model and assume the lightest neutralino being the dark matter particles. Based on the N-body simulation of the evolution of dark matter subhalos we first calculate the average intensity distribution of this new class of $\gamma$-ray sources by neutralino annihilation. It is possible to detect these $\gamma$-ray sources by EGRET and GLAST. Conversely, if these sources are not detected the nature of the dark matter particls will be constrained by these experiments, which, however, depending on the uncertainties of the subhalo profile.Comment: 19 pages, 5 gigures; references added, more discussions adde

Difference of optical conductivity between one- and two-dimensional doped nickelates

We study the optical conductivity in doped nickelates, and find the dramatic difference of the spectrum in the gap ($\omega$\alt4 eV) between one- (1D) and two-dimensional (2D) nickelates. The difference is shown to be caused by the dependence of hopping integral on dimensionality. The theoretical results explain consistently the experimental data in 1D and 2D nickelates, Y$_{2-x}$Ca$_x$BaNiO$_5$ and La$_{2-x}$Sr$_x$NiO$_4$, respectively. The relation between the spectrum in the X-ray aborption experiments and the optical conductivity in La$_{2-x}$Sr$_x$NiO$_4$ is discussed.Comment: RevTeX, 4 pages, 4 figure

Anti Microbial Resistance Profile of E. coli isolates From Tropical Free Range Chickens

Normal intestinal flora of humans and animals constitute enormous reservoir of resistance genes for potentially pathogenic bacteria and may serve as major indictors of selection pressure exerted by anti-microbial use in a given population. A study was conducted in September 2003 at 3 purposively selected peri-urban sites spread across 3 senatorial zones of Imo state, Nigeria to determines the anti-microbial resistance profile of commensal E. coli isolated from free range chickens. The isolates were screened for anti-microbial resistance profile against 10 antibiotics using the disc diffusion method. E. coli strains from local fowls, recorded 100 and 78.9% resistances against ampicillin and cotrimoxazole respectively, while resistance rates against ciprofloxacin, gentamycin and norfloxacin were 0.0, 5.3 and 5.3% respectively. Isolates from free-range cockerels recorded 100% resistance against norfloxacin, cotrimoxazole and ampicillin and 83.3% against nitrofurantoin. Similarly, isolates from old layers, recorded 100% resistance against nitrofurantoin, cotrimoxazole, tetracycline, chloramphenicol and ampicillin and 80% against nalidixic acid. Similar resistance trends were observed in E. coli isolates from free-range turkeys and broiler roosters against the inexpensive broad-spectrum first line antibiotics (ampicillin, nalidixic acid, cotrimoxazole, nitrofurantoin and chloramphenicol), although values varied slightly across poultry types. Resistances against gentamycin were consistently low in isolates from the different types of poultry. Twenty-nine resistance patterns were observed in the E. coli isolates with predominant patterns being distributed widely across poultry types indicating a striking diversity of resistance patterns in the areas

Split Two-Higgs-Doublet Model and Neutrino Condensation

We split the two-Higgs-doublet model by assuming very different vevs for the two doublets: the vev is at weak scale (174 GeV) for the doublet \Phi_1 and at neutrino-mass scale (10^{-2} \sim 10^{-3} eV) for the doublet \Phi_2. \Phi_1 is responsible for giving masses to all fermions except neutrinos; while \Phi_2 is responsible for giving neutrino masses through its tiny vev without introducing see-saw mechanism. Among the predicted five physical scalars H, h, A^0 and H^{\pm}, the CP-even scalar h is as light as 10^{-2} \sim 10^{-3}eV while others are at weak scale. We identify h as the cosmic dark energy field and the other CP-even scalar H as the Standard Model Higgs boson; while the CP-odd A^0 and the charged H^{\pm} are the exotic scalars to be discovered at future colliders. Also we demonstrate a possible dynamical origin for the doublet \Phi_2 from neutrino condensation caused by some unknown dynamics.Comment: version in Europhys. Lett. (discussions added

Modified pedicle screw-rod fixation versus anterior pelvic external fixation for the management of anterior pelvic ring fractures: a comparative study

Background Anterior pelvic ring fracture, as high-energy trauma, needs to be effectively treated. The purpose of the current study was to evaluate the clinical applications of modified pedicle screw-rod fixation and anterior pelvic external fixation for the treatment of anterior pelvic ring fracture. Methods Either modified pedicle screw-rod fixation (modified PSRF group, N = 21) or anterior pelvic external fixation (APEF group, N = 22) was performed to 43 patients, with or without fixation of posterior ring. Clinical outcomes were evaluated via Majeed scores. Relevant clinical evaluation indicators including operation time, intraoperative blood loss, hospitalization duration, and complications were compared between these two groups. Results The operation time in APEF group was significantly less than that in modified PSRF group (P < 0.0001). No significant difference with respect to intraoperative blood loss and hospitalization duration between the two groups was shown (P = 0.51 and P = 0.33, respectively). Six patients developed surgical site infection in APEF group. Three patients experienced loss of fixation, and two patients experienced loosening of fixator in APEF group. Temporary lateral femoral cutaneous nerve irritation occurred in three patients in modified PSRF group while two patients in APEF group. One patient experienced femoral nerve palsy in modified PSRF group. Fractures of all patients healed well eventually. No statistical difference regarding Majeed evaluation scores was found between two groups. Conclusions Application of both modified PSRF and APEF could provide similar satisfactory clinical outcomes for anterior pelvic ring fracture. Modified PSRF, a minimally invasive technique with the advantages of internal fixation, could be performed as an alternative method for instable pelvic fractures

Thermocatalytic syntheses of highly defective hybrid nano-catalysts for photocatalytic hydrogen evolution

Defects play important roles in many catalytic processes, particularly for photocatalytic processes in semiconductors as they can alter the band structures and affect the excited electron–hole recombination pathways/lifetimes of semiconductors. In this report, we described the development of a facile route to the production of highly defective photocatalysts. Firstly, organic species were bound onto the surface of a metal oxide semiconductor catalyst, followed by a relatively low temperature ageing in N2, to remove the organics and to attract oxygen molecules from the surface, generating oxygen vacancies. In particular, we introduced a co-catalyst during the syntheses, which acted as a thermocatalyst to promote full oxidation of the organics, leaving more oxygen vacancies at the surface and to form intimate heterojunctions with host-catalysts to further drive the photocatalytic hydrogen evolution. The hydrogen evolution rate for our developed NiO–TiO2 defective heterojunctions in a sacrificial system was measured at ca. 1.41 mmol g−1 h−1, which was much higher than those of comparable catalysts reported in the literature (that generally display hydrogen evolution rates <0.4 mmol g−1 h−1). Computational simulation, together with other analytical techniques, suggested that the generated surface oxygen vacancies could induce a series of impurity energy levels within the VBM and CBM of TiO2 that narrowed the electron transmission gap in the TiO2 and acted as active sites for the reaction between adsorbed H2O and photoinduced trapped electrons to produce H2