Search for hadronic decays of a light Higgs boson in the radiative decay Υ→γA0

We search for hadronic decays of a light Higgs boson (A(0)) produced in radiative decays of an Υ(2S) or Υ(3S) meson, Υ→γA(0). The data have been recorded by the BABAR experiment at the Υ(3S) and Υ(2S) center-of-mass energies and include (121.3±1.2)×10(6) Υ(3S) and (98.3±0.9)×10(6) Υ(2S) mesons. No significant signal is observed. We set 90% confidence level upper limits on the product branching fractions B(Υ(nS)→γA(0))B(A(0)→hadrons) (n=2 or 3) that range from 1×10(-6) for an A(0) mass of 0.3 GeV/c(2) to 8×10(-5) at 7 GeV/c(2).     

Antenna length and polarization response of antenna-coupled MOM diode infrared detectors

This work focuses on the fabrication and response of dipole antenna-coupled metal–oxide–metal diode detectors to long-wave infrared radiation. The detectors are fabricated using a single electron beam lithography step and a shadow evaporation technique. The detector’s characteristics are presented, which include response as a function of incident infrared power and polarization angle. In addition, the effect of dipole antenna length on detection characteristics for 10.6 μm radiation has been measured to determine resonant lengths. The response of the detector shows a first resonance at a dipole length of 3.1 μm, a second resonance at 9.3 μm, and third at 15.5 μm. The zeros intermediate to the resonances are also evident.     

Search for f(J)(2220) in radiative J/ψ decays

We present a search for f(J)(2220) production in radiative J/ψ→γf(J)(2220) decays using 460 fb?1 of data collected with the BABAR detector at the SLAC PEP-II e(+)e? collider. The f(J)(2220) is searched for in the decays to K(+)K? and K(S)?K(S)?. No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/ψ→γf(J)(2220) and f(J)(2220)→K(+)K?(K(S)?K(S)?) as a function of spin and helicity are set at the level of 10??, below the central values reported by the Mark III experiment.     

Evaluation of recombinant invasive, non-pathogenic Eschericia coli as a vaccine vector against the intracellular pathogen, Brucella

Background  

There is no safe, effective human vaccine against brucellosis. Live attenuated Brucella strains are widely used to vaccinate animals. However these live Brucella vaccines can cause disease and are unsafe for humans. Killed Brucella or subunit vaccines are not effective in eliciting long term protection. In this study, we evaluate an approach using a live, non-pathogenic bacteria (E. coli) genetically engineered to mimic the brucellae pathway of infection and present antigens for an appropriate cytolitic T cell response.     

Generic cosmic-censorship violation in anti-de Sitter space

We consider (four-dimensional) gravity coupled to a scalar field with potential V(phi). The potential satisfies the positive energy theorem for solutions that asymptotically tend to a negative local minimum. We show that for a large class of such potentials, there is an open set of smooth initial data that evolve to naked singularities. Hence cosmic censorship does not hold for certain reasonable matter theories in asymptotically anti-de Sitter spacetimes. The asymptotically flat case is more subtle. We suspect that potentials with a local Minkowski minimum may similarly lead to violations of cosmic censorship in asymptotically flat spacetimes, but we do not have definite results.     

Designer gravity and field theory effective potentials

Motivated by the anti-de Sitter conformal field theory correspondence, we show that there is remarkable agreement between static supergravity solutions and extrema of a field theory potential. For essentially any function V(alpha) there are boundary conditions in anti-de Sitter space so that gravitational solitons exist precisely at the extrema of V and have masses given by the value of V at these extrema. Based on this, we propose new positive energy conjectures. On the field theory side, each function V can be interpreted as the effective potential for a certain operator in the dual field theory.     

A realization of digital wireless transmission for MRI signals based on 802.11b

In this paper, a digital wireless transmission system based on 802.11b standard for magnetic resonance imaging (MRI) application is designed and built for the first time to eliminate the interference aroused by coil array cables. The analysis shows that the wireless receiver has a very high sensitivity to detect MRI signals. The modulation technique of differential quadrature phase shift keyed (DQPSK) can be applied to MRI data transmission with rate of 2 Mbps and bandwidth of 2 MHz. The bench test verifies that this wireless link has a dynamic range over 86 dB supporting up to 3 T MRI system data transmission. The 2D spin echo imaging of phantom is performed and the SNR of the image obtained by the wireless transmission can be comparable with that got by the coaxial cables.     

Monitoring chemotherapeutic response in RIF-1 tumors by single-quantum and triple-quantum-filtered (23)Na MRI, (1)H diffusion-weighted MRI and PET imaging

The effects of 5-fluorouracil (5FU, 150 mg/kg, ip) on subcutaneously implanted radiation-induced fibrosarcoma (RIF-1) tumors were monitored by in vivo (1)H MRI to evaluate the water apparent diffusion coefficient (ADC), by single-quantum (SQ) and triple-quantum-filtered (TQF) (23)Na MRI to evaluate compartmental Na(+) content and by positron emission tomography (PET) to evaluate 2-[(18)F]fluoro-2-deoxy-d-glucose (FDG) uptake in the tumor. The MRI experiments were performed on untreated control and treated mice once before and then daily for 3 days after treatment. The PET experiments were performed on separate groups of age- and tumor-volume-matched animals once before and then 3 days after treatment. Tumor volumes significantly decreased in treated animals 2 and 3 days posttreatment. At the same time points, in vivo MRI measurements showed an increase in both total tissue SQ (23)Na signal intensity (SI) and water ADC in treated tumors while control tumors showed no change in these parameters. TQF (23)Na SI and FDG uptake were significantly lower in treated tumors compared with control tumors 3 days after 5FU treatment. The correlated increases in total tissue (23)Na SI and water ADC following chemotherapy reflect an increase in extracellular space, while the lower TQF (23)Na SI and FDG uptake in treated tumors compared with control tumors suggest a shift in tumor metabolism from glycolysis to oxidation and/or a decrease in cell density.     

TEM characterization of chemically synthesized copper–gold nanoparticles

Dodecanethiol-capped Cu–Au nanoparticles, synthesized via a successive two-phase (water/toluene) and galvanic-exchange procedure, were characterized using transmission electron microscopy (TEM). The size range of the particles is around 1–7 nm. Electron-induced morphological evolution was observed under high resolution (HR) TEM. Cuboctahedral morphology was found to be thermodynamically stable. Electron-induced aggregation of two particles was also observed. Chemical ordering of cuboctahedral particles was studied by atomic-resolution high angle annular dark field (HAADF) imaging in scanning TEM (STEM) mode and energy dispersive X-ray (EDX) element mapping using a silicon drift detector (SDD). The particles were found to be Cu–Au mixed, and to be stable in air. Surface plasmon resonance (SPR), which is dependent on local structure and morphology, was investigated by electron energy loss spectroscopy (EELS).     

Diffusion of 111Cd probes in Ga7Pt3 studied via nuclear quadrupole relaxation

Diffusion of ¹¹¹In/Cd impurity atoms was studied in Ga₇Pt₃ at the atomic level using the method of perturbed angular correlation of gamma rays (PAC). As in previous measurements on Ga₇Pd₃, probes were observed to occupy two inequivalent Ga-sublattices. Quadrupole interaction perturbation functions for each site exhibited damping at elevated temperatures that is attributed to nuclear relaxation caused by stochastic jumps of the probe atoms accompanied by reorientation of axes of the electric field gradient tensor. Fitted relaxation frequencies, proportional to mean jump frequencies of the probe, were thermally activated. Arrhenius plots revealed jump-frequency activation enthalpies of 0.94 (8) and 0.67 (4) eV for the two sites and frequency prefactors close to 1 THz. Results were similar to those found previously for Ga₇Pd₃, although jump frequencies are about 100 times lower in Ga₇Pt₃.