15,012 research outputs found

    Gulf War Syndrome: A role for organophosphate induced plasticity of locus coeruleus neurons

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    Gulf War syndrome is a chronic multi-symptom illness that has affected about a quarter of the deployed veterans of the 1991 Gulf War. Exposure to prolonged low-level organophosphate insecticides and other toxic chemicals is now thought to be responsible. Chlorpyrifos was one commonly used insecticide. The metabolite of chlorpyrifos, chlorpyrifos oxon, is a potent irreversible inhibitor of acetylcholinesterase, much like the nerve agent Sarin. To date, the target brain region(s) most susceptible to the neuroactive effects of chlorpyrifos oxon have yet to be identified. To address this we tested ability of chlorpyrifos oxon to influence neuronal excitability and induce lasting changes in the locus coeruleus, a brain region implicated in anxiety, substance use, attention and emotional response to stress. Here we used an ex vivo rodent model to identify a dramatic effect of chlorpyrifos oxon on locus coeruleus noradrenergic neuronal activity. Prolonged exposure to chlorpyrifos oxon caused acute inhibition and a lasting rebound excitatory state expressed after days of exposure and subsequent withdrawal. Our findings indicate that the locus coeruleus is a brain region vulnerable to chlorpyrifos oxon-induced neuroplastic changes possibly leading to the neurological symptoms affecting veterans of the Gulf War

    Next-to-leading order QCD corrections to a heavy resonance production and decay into top quark pair at the LHC

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    We present a complete next-to-leading order (NLO) QCD calculation to a heavy resonance production and decay into a top quark pair at the LHC, where the resonance could be either a Randall-Sundrum (RS) Kaluza-Klein (KK) graviton GG or an extra gauge boson ZZ'. The complete NLO QCD corrections can enhance the total cross sections by about 80%100%80\%- 100\% and 20%40%20\%- 40\% for the GG and the ZZ', respectively, depending on the resonance mass. We also explore in detail the NLO corrections to the polar angle distributions of the top quark, and our results show that the shapes of the NLO distributions can be different from the leading order (LO) ones for the KK graviton. Moreover, we study the NLO corrections to the spin correlations of the top quark pair production via the above process, and find that the corrections are small.Comment: Published version in PR

    Supernova Constraints on Models of Neutrino Dark Energy

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    In this paper we use the recently released Type Ia Supernova (SNIa) data to constrain the interactions between the neutrinos and the dark energy scalar fields. In the analysis we take the dark energy scalars to be either Quintessence-like or Phantom-like. Our results show the data mildly favor a model where the neutrinos couple to a phantom-like dark energy scalar, which implies the equation of state of the coupled system behaves like Quintom scenario in the sense of parameter degeneracy. We find future observations like SNAP are potentially promising to measure the couplings between neutrino and dark energy.Comment: Typos fixed and references updated. Version pressed in PR

    B\to X_s\gamma, X_s l^+ l^- decays and constraints on the mass insertion parameters in the MSSM

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    In this paper, we study the upper bounds on the mass insertion parameters (δABq)ij(\delta^{q}_{AB})_{ij} in the minimal supersymmetric standard model (MSSM). We found that the information from the measured branching ratio of BXsl+lB \to X_s l^+ l^- decay can help us to improve the upper bounds on the mass insertions parameters \left (\delta^{u,d}_{AB})_{3j,i3}. Some regions allowed by the data of Br(BXsγ)Br(B \to X_s \gamma) are excluded by the requirement of a SM-like C7γ(mb)C_{7\gamma}(m_b) imposed by the data of Br(BXsl+l)Br(B \to X_s l^+ l^-).Comment: 16 pages, 5 eps figure files, typos remove

    Next-to-leading order QCD corrections to the top quark decay via the Flavor-Changing Neutral-Current operators with mixing effects

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    In this paper detailed calculations of the complete O(αs)\mathcal{O}(\alpha_s) corrections to top quark decay widths Γ(tq+V)\Gamma(t\to q+V) are presented (V=g,γ,ZV=g,\gamma,Z). Besides describing in detail the calculations in our previous paper (arXiv:0810.3889), we also include the mixing effects of the Flavor-Changing Neutral-Current (FCNC) operators for tq+γt\to q+\gamma and tq+Zt\to q+Z, which were not considered in our previous paper. The results for tq+gt\to q+g are the same as in our previous paper. But the mixing effects can either be large or small, and increase or decrease the branching ratios for tq+γt\to q+\gamma and tq+Zt\to q+Z, depending on the values of the anomalous couplings (κtqg,γ,Z/Λ\kappa^{g,\gamma,Z}_{\mathrm{tq}}/\Lambda, ftqg,γ,Zf^{g,\gamma,Z}_{\mathrm{tq}} and htqg,γ,Zh^{g,\gamma,Z}_{\mathrm{tq}}).Comment: 21 pages, 12 figure

    Next-to-leading order QCD predictions for graviton and photon associated production in the Large Extra Dimensions model at the LHC

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    We present the calculations of the complete next-to-leading order(NLO) QCD corrections to the inclusive total cross sections for the Kaluza-Klein(KK) graviton and photon associated production process ppγGKK+Xpp \to \gamma G_{KK} + X in the large extra dimensions(LED) model at the LHC. We show that the NLO QCD corrections in general enhance the total cross sections and reduce the dependence of the total cross sections on the factorization and renormalization scales. When jet veto is considered, the NLO corrections reduce the total cross sections. We also calculate some important differential cross sections for this process at NLO: the missing transverse momentum distribution, the transverse momentum distribution and the pseudorapidity distribution of photon.Comment: 28 pages, 14 figures; minor changes, version published in Phys.Rev.

    Melatonin Alters Age-Related Changes in Transcription Factors and Kinase Activation

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    Male mice were fed 40 ppm melatonin for 2 months prior to sacrifice at age 26 months, and compared with both 26 and 4 month-old untreated controls. The nuclear translocation of NF-κB increased with age in both brain and spleen and this was reversed by melatonin only in brain. Another transcription factor, AP-1 was increased with age in the spleen and not in brain and this could be blocked by melatonin treatment. The fraction of the active relative to the inactive form of several enabling kinases was compared. The proportion of activated ERK was elevated with age in brain and spleen but this change was unresponsive to melatonin. A similar age-related increase in glial fibrillary acidic protein (GFAP) was also refractory to melatonin treatment. The cerebral melatonin M1 receptor decreased with age in brain but increased in spleen. The potentially beneficial nature of melatonin for the preservation of brain function with aging was suggested by the finding that an age-related decline in cortical synaptophysin levels was prevented by dietary melatonin
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