Absence of spin superradiance in resonatorless magnets

A spin system is considered with a Hamiltonian typical of molecular magnets, having dipole-dipole interactions and a single-site magnetic anisotropy. In addition, spin interactions through the common radiation field are included. A fully quantum-mechanical derivation of the collective radiation rate is presented. An effective narrowing of the dipole-dipole attenuation, due to high spin polarization is taken into account. The influence of the radiation rate on spin dynamics is carefully analysed. It is shown that this influence is completely negligible. No noticeable collective effects, such as superradiance, can appear in molecular magnets, being caused by electromagnetic spin radiation. Spin superradiance can arise in molecular magnets only when these are coupled to a resonant electric circuit, as has been suggested earlier by one of the authors in Laser Phys. {\bf 12}, 1089 (2002).Comment: Latex file, 14 pages, 5 figure

Epithelial coxsackievirus adenovirus receptor promotes house dust mite-induced lung inflammation

Airway inflammation and remodelling are important pathophysiologic features in asthma and other respiratory conditions. An intact epithelial cell layer is crucial to maintain lung homoeostasis, and this depends on intercellular adhesion, whilst damaged respiratory epithelium is the primary instigator of airway inflammation. The Coxsackievirus Adenovirus Receptor (CAR) is highly expressed in the epithelium where it modulates cell-cell adhesion stability and facilitates immune cell transepithelial migration. However, the contribution of CAR to lung inflammation remains unclear. Here we investigate the mechanistic contribution of CAR in mediating responses to the common aeroallergen, House Dust Mite (HDM). We demonstrate that administration of HDM in mice lacking CAR in the respiratory epithelium leads to loss of peri-bronchial inflammatory cell infiltration, fewer goblet-cells and decreased pro-inflammatory cytokine release. In vitro analysis in human lung epithelial cells confirms that loss of CAR leads to reduced HDM-dependent inflammatory cytokine release and neutrophil migration. Epithelial CAR depletion also promoted smooth muscle cell proliferation mediated by GSK3β and TGF-β, basal matrix production and airway hyperresponsiveness. Our data demonstrate that CAR coordinates lung inflammation through a dual function in leucocyte recruitment and tissue remodelling and may represent an important target for future therapeutic development in inflammatory lung diseases

Search for W' bosons decaying to an electron and a neutrino with the D0 detector

This Letter describes the search for a new heavy charged gauge boson W' decaying into an electron and a neutrino. The data were collected with the D0 detector at the Fermilab Tevatron proton-antiproton Collider at a center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity of about 1 inverse femtobarn. Lacking any significant excess in the data in comparison with known processes, an upper limit is set on the production cross section times branching fraction, and a W' boson with mass below 1.00 TeV can be excluded at the 95% C.L., assuming standard-model-like couplings to fermions. This result significantly improves upon previous limits, and is the most stringent to date.Comment: submitted to Phys. Rev. Let

Search for the associated production of a b quark and a neutral supersymmetric Higgs boson which decays to tau pairs

We report results from a search for production of a neutral Higgs boson in association with a $b$ quark. We search for Higgs decays to $\tau$ pairs with one $\tau$ subsequently decaying to a muon and the other to hadrons. The data correspond to 2.7fb$^{-1}$ of \ppbar collisions recorded by the D0 detector at $\sqrt{s} = 1.96$TeV. The data are found to be consistent with background predictions. The result allows us to exclude a significant region of parameter space of the minimal supersymmetric model.Comment: Submitted to Phys. Rev. Letter

Biology, Fishery, Conservation and Management of Indian Ocean Tuna Fisheries

The focus of the study is to explore the recent trend of the world tuna fishery with special reference to the Indian Ocean tuna fisheries and its conservation and sustainable management. In the Indian Ocean, tuna catches have increased rapidly from about 179959 t in 1980 to about 832246 t in 1995. They have continued to increase up to 2005; the catch that year was 1201465 t, forming about 26% of the world catch. Since 2006 onwards there has been a decline in the volume of catches and in 2008 the catch was only 913625 t. The Principal species caught in the Indian Ocean are skipjack and yellowfin. Western Indian Ocean contributed 78.2% and eastern Indian Ocean 21.8% of the total tuna production from the Indian Ocean. The Indian Ocean stock is currently overfished and IOTC has made some recommendations for management regulations aimed at sustaining the tuna stock. Fishing operations can cause ecological impacts of different types: by catches, damage of the habitat, mortalities caused by lost or discarded gear, pollution, generation of marine debris, etc. Periodic reassessment of the tuna potential is also required with adequate inputs from exploratory surveys as well as commercial landings and this may prevent any unsustainable trends in the development of the tuna fishing industry in the Indian Ocean

A measurement of the ratio of inclusive cross sections σ(ppˉ→Z+b jet)/σ(ppˉ→Z+jet)\sigma(p\bar{p}\rightarrow Z+b{\rm\, jet})/ \sigma(p\bar{p}\rightarrow Z+{\rm jet}) at s=1.96\sqrt{s}=1.96 TeV

The ratio of the cross section for $p\bar{p}$ interactions producing a $Z$ boson and at least one $b$ quark jet to the inclusive $Z+{\rm jet}$ cross section is measured using $4.2\ {\rm fb}^{-1}$ of $p\bar{p}$ collisions collected with the \dzero\ detector at the Fermilab Tevatron collider at $\sqrt{s}=1.96$ TeV. The $Z\rightarrow\ell^+\ell^-$ candidate events with at least one $b$ jet are discriminated from $Z+$ charm and light jet(s) events by a novel technique that exploits the properties of the tracks associated to the jet. The measured ratio is $0.0193\pm0.0027$ for events having a jet with transverse momentum \pt > 20 \GeV and pseudorapidity $|\eta| \leq 2.5$, which is the most precise to date and is consistent with theoretical predictions.Comment: Submitted to Phys. Rev. Let

Measurement of the Lambda^0_b lifetime in the decay Lambda^0_b -> J/psi Lambda^0 with the D0 Detector

We present measurements of the Lambda^0_b lifetime in the exclusive decay channel Lambda^0_{b}->J/psi Lambda^0, with J/psi to mu+ mu- and Lambda^0 to p pi-, the B^0 lifetime in the decay B^0 -> J/psi K^0_S with J/psi to mu+ mu- and K^0_S to pi+ pi-, and the ratio of these lifetimes. The analysis is based on approximately 250 pb^{-1} of data recorded with the D0 detector in pp(bar) collisions at sqrt{s}=1.96 TeV. The Lambda^0_b lifetime is determined to be tau(Lambda^0_b) = 1.22 +0.22/-0.18 (stat) +/- 0.04 (syst) ps, the B^0 lifetime tau(B^0) = 1.40 +0.11/-0.10 (stat) +/- 0.03 (syst) ps, and the ratio tau(Lambda^0_b)/tau(B^0) = 0.87 +0.17/-0.14 (stat) +/- 0.03 (syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Lambda^0_b lifetime based on a fully reconstructed decay channel.Comment: 7 pages, 4 figures, Submitted to Physical Review Letters, v2: Added FNAL Pub-numbe

Measurement of the WW production cross section in p anti-p collisions at s**(1/2) = 1.96 TeV

We present a measurement of the W boson pair-production cross section in p anti-p collisions at a center-of-mass energy of sqrt{s}=1.96 TeV. The data, collected with the Run II DO detector, correspond to an integrated luminosity of 224-252 pb^-1 depending on the final state (ee, emu or mumu). We observe 25 candidates with a background expectation of 8.1+/-0.6(stat)+/-0.6(syst)+/-0.5(lum) events. The probability for an upward fluctuation of the background to produce the observed signal is 2.3x10^-7, equivalent to 5.2 standard deviations.The measurement yields a cross section of 13.8+4.3/-3.8(stat)+1.2/-0.9(syst)+/-0.9(lum) pb, in agreement with predictions from the standard model.Comment: submitted to PR

Erratum to Measurement of σ(ppˉ→Z)⋅Br(Z→ττ)\sigma (p \bar p \to Z) \cdot Br(Z \to \tau\tau) at s=\bm{\sqrt{s}=}1.96 TeV, published in Phys. Rev. D {71}, 072004 (2005)

A change in estimated integrated luminosity (from 226 pb$^{-1} to 257 pb$^{-1}$leads to a corrected value for${\sigma (p \bar p \to Z) \cdot}$Br${(Z \to \tau \tau)}$of$209\pm13(stat.)\pm16(syst.)\pm13(lum) pb

Search for the Standard Model Higgs Boson in the ZH --> neutrino-neutrino-b-b channel

We report a search for the standard model (SM) Higgs boson based on data collected by the D0 experiment at the Fermilab Tevatron Collider, corresponding to an integrated luminosity of 260 pb^-1. We study events with missing transverse energy and two acoplanar b-jets, which provide sensitivity to the ZH production cross section in the neutrino-neutrino-b-b channel and to WH production, when the lepton from the W -> lepton+neutrino decay is undetected. The data are consistent with the SM background expectation, and we set 95% C.L. upper limits on sigma(p p-bar -> ZH/WH) x B(H -> b b-bar) from 3.4/8.3 to 2.5/6.3 pb, for Higgs masses between 105 and 135 GeV.Comment: submitted to Phys. Rev. Letter