658 research outputs found

    Meaningful Toxicology

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    The scope of toxicology, therefore, may extend from the study of a single element such as lead to a complex, chemically uncharacterized substance such as snake venom; from an overdose of heroin to the effects of long-term exposure to low levels of pesticides on anticonvulsant therapy. For the purpose of this discussion, we shall narrow the limits of the broad field of toxicology considerably, but it is important to be aware of the breadth and depth to which toxicology may at times extend

    Adaptive Observer for Nonlinearly Parameterised Hammerstein System with Sensor Delay – Applied to Ship Emissions Reduction

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    Taking offspring in a problem of ship emission reduction by exhaust gas recirculation control for large diesel engines, an underlying generic estimation challenge is formulated as a problem of joint state and parameter estimation for a class of multiple-input single-output Hammerstein systems with first order dynamics, sensor delay and a bounded time-varying parameter in the nonlinear part. The paper suggests a novel scheme for this estimation problem that guarantees exponential convergence to an interval that depends on the sensitivity of the system. The system is allowed to be nonlinear parameterized and time dependent, which are characteristics of the industrial problem we study. The approach requires the input nonlinearity to be a sector nonlinearity in the time-varying parameter. Salient features of the approach include simplicity of design and implementation. The efficacy of the adaptive observer is shown on simulated cases, on tests with a large diesel engine on test bed and on tests with a container vessel

    The Impact of a 4th Generation on Mixing and CP Violation in the Charm System

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    We study D0-D0 mixing in the presence of a fourth generation of quarks. In particular, we calculate the size of the allowed CP violation which is found at the observable level well beyond anything possible with CKM dynamics. We calculate the semileptonic asymmetry a_SL and the mixing induced CP asymmetry eta_fS_f which are correlated with each other. We also investigate the correlation of eta_fS_f with a number of prominent observables in other mesonic systems like epsilon'/epsilon, Br(K_L -> pi0 nu nu), Br(K+ -> pi+ nu nu), Br(B_s ->mu+ mu-), Br(B_d -> mu+ mu-) and finally S_psi phi in the B_s system. We identify a clear pattern of flavour and CP violation predicted by the SM4 model: While simultaneous large 4G effects in the K and D systems are possible, accompanying large NP effects in the B_d system are disfavoured. However this behaviour is not as pronounced as found for the LHT and RSc models. In contrast to this, sizeable CP violating effects in the B_s system are possible unless extreme effects in eta_fS_f are found, and Br(B_s ->mu+ mu-) can be strongly enhanced regardless of the situation in the D system. We find that, on the other hand, S_psi phi > 0.2 combined with the measured epsilon'/epsilon significantly diminishes 4G effects within the D system.Comment: 22 pages, 23 figures, v2 (references added

    Phenomenology of a three-family model with gauge symmetry SU(3)_c X SU(4)_L X U(1)_X

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    We study an extension of the gauge group SU(3)_c X SU(2)_L X U(1)_Y of the standard model to the symmetry group SU(3)_c X SU(4)_L X U(1)_X (3-4-1 for short). This extension provides an interesting attempt to answer the question of family replication in the sense that models for the electroweak interaction can be constructed so that anomaly cancellation is achieved by an interplay between generations, all of them under the condition that the number of families must be divisible by the number of colours of SU(3)_c. This method of anomaly cancellation requires a family of quarks transforming differently from the other two, thus leading to tree-level flavour changing neutral currents (FCNC) transmitted by the two extra neutral gauge bosons Z′Z' and Z′′Z'' predicted by the model. In a version of the 3-4-1 extension, which does not contain particles with exotic electric charges, we study the fermion mass spectrum and some aspects of the phenomenology of the neutral gauge boson sector. In particular, we impose limits on the Z−Z′Z-Z' mixing angle and on the mass scale of the corresponding physical new neutral gauge boson Z2Z_2, and establish a lower bound on the mass of the additional new neutral gauge boson Z′′≡Z3Z'' \equiv Z_3. For the analysis we use updated precision electroweak data at the Z-pole from the CERN LEP and SLAC Linear Collider, and atomic parity violation data. The mass scale of the additional new neutral gauge boson Z3Z_3 is constrained by using updated experimental inputs from neutral meson mixing in the analysis of the sources of FCNC in the model. The data constrain the Z−Z′Z-Z' mixing angle to a very small value of O(0.001), and the lower bounds on MZ2M_{Z_2} and on MZ3M_{Z_3} are found to be of O(1 TeV) and of O(7 TeV), repectively.Comment: 22 pages, 6 tables, 1 figure. To appear in J. Phys. G: Nuclear and Particle Physic

    Clinical neuroimaging in epileptic patients with autoscopic hallucinations and out-of-body experiences

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    Autoscopic phenomena are complex illusory perceptions of one's body during which human subjects experience a second own body or double in their environment. Autoscopic phenomena most commonly refer tovisual doubles, although doubles may also be felt or heard and consist of autoscopic hallucinations, out-ofbody experiences, and heautoscopy. Recently, many neurological reports have focussed on out-of-body experiences. Here we review neurological data on autoscopic hallucinations and present a case during complex partial seizures due to neurocysticercosi

    Waiting for Precise Measurements of K^+->pi^+ nu nu and K_L->pi^0 nu nu

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    In view of future plans for accurate measurements of the theoretically clean branching ratios Br(K+ -> pi+ nu nu) and Br(KL -> pi0 nu nu), that should take place in the next decade, we collect the relevant formulae for quantities of interest and analyze their theoretical and parametric uncertainties. We point out that in addition to the angle beta in the unitarity triangle (UT) also the angle gamma can in principle be determined from these decays with respectable precision and emphasize in this context the importance of the recent NNLO QCD calculation of the charm contribution to K+ -> pi+ nu nu and of the improved estimate of the long distance contribution by means of chiral perturbation theory. In addition to known expressions we present several new ones that should allow transparent tests of the Standard Model (SM) and of its extensions. While our presentation is centered around the SM, we also discuss models with minimal flavour violation and scenarios with new complex phases in decay amplitudes and meson mixing. We give a brief review of existing results within specific extensions of the SM, in particular the Littlest Higgs Model with T-parity, Z' models, the MSSM and a model with one universal extra dimension. We derive a new "golden" relation between B and K systems that involves (beta,gamma) and Br(KL -> pi0 nu nu) and investigate the virtues of (R_t,beta), (R_b,gamma), (beta,gamma) and (etabar,gamma) strategies for the UT in the context of K -> pi nu nu decays with the goal of testing the SM and its extensions.Comment: 56 pages, 18 figures, Section on Long Distance Contributions, 2 Figures and few References added, Uses Rev Mod Phys Style; Includes new results of NNLO calculation as well as matrix elements, extended and modified sections on new physic

    Pair production of the T-odd leptons at the LHC

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    The T-odd leptons predicted by the littlest HiggsHiggs model with T-parity can be pair produced via the subprocesses gg→ℓH+ℓH−gg\to \ell^{+}_{H}\ell^{-}_{H}, qqˉ→ℓH+ℓH−q\bar{q}\to \ell^{+}_{H}\ell^{-}_{H}, γγ→ℓH+ℓH−\gamma\gamma\to \ell^{+}_{H}\ell^{-}_{H} and VV→ℓH+ℓH− VV \to \ell^{+}_{H}\ell^{-}_{H} (VV=WW or ZZ) at the CERNCERN Large Hadron Collider (LHC)(LHC). We estimate the hadronic production cross sections for all of these processes and give a simply phenomenology analysis. We find that the cross sections for most of the above processes are very small. However, the value of the cross section for the Drell−YanDrell-Yan process qqˉ→ℓH+ℓH−q\bar{q}\to \ell^{+}_{H}\ell^{-}_{H} can reach 270fb270fb.Comment: 12 pages, 2 figure

    Lepton flavor violation decays τ−→μ−P1P2\tau^-\to \mu^- P_1 P_2 in the topcolor-assisted technicolor model and the littlest Higgs model with TT parity

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    The new particles predicted by the topcolor-assisted technicolor (TC2TC2) model and the littlest Higgs model with T-parity (called LHTLHT model) can induce the lepton flavor violation (LFVLFV) couplings at tree level or one loop level, which might generate large contributions to some LFVLFV processes. Taking into account the constraints of the experimental data on the relevant free parameters, we calculate the branching ratios of the LFVLFV decay processes τ−→μ−P1P2\tau^-\to\mu^- P_1 P_2 with P1P2P_1 P_2 = π+π−\pi^+\pi^-, K+K−K^+K^- and K0K0ˉK^0\bar{K^0} in the context of these two kinds of new physics models. We find that the TC2TC2 model and the LHTLHT model can indeed produce significant contributions to some of these LFVLFV decay processes.Comment: 24 pages, 7 figure

    The production of the new gauge boson BHB_{H} via e−γe^{-}\gamma collision in the littlest Higgs model

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    The new lightest gauge boson BHB_H with mass of a few hundred GeV is predicted in the littlest Higgs model. BHB_H should be accessible in the planed ILC and the observation of such particle can strongly support the littlest Higgs model. The realization of γγ\gamma\gamma and eγe\gamma collision will open a wider window to probe BHB_H. In this paper, we study the new gauge boson BHB_{H} production processes e−γ→e−γBHe^{-}\gamma\to e^{-}\gamma B_{H} and e−γ→e−ZBHe^{-}\gamma\to e^{-}Z B_{H} at the ILC. Our results show that the production cross section of the process e−γ→e−ZBHe^{-}\gamma\to e^{-}Z B_{H} is less than one fb in the most parameter spaces while the production cross section of the process e−γ→e−γBHe^{-}\gamma\to e^{-}\gamma B_{H} can reach the level of tens fb and even hundreds of fb in the sizable parameter spaces allowed by the electroweak precision data. With the high luminosity, the sufficient typical signals could be produced, specially via e−γ→e−γBHe^{-}\gamma\to e^{-}\gamma B_{H}. Because the final electron and photon beams can be easily identified and the signal can be easily distinguished from the background produced by ZZ and HH decaying, BHB_H should be detectable via eγe\gamma collision at the ILC. Therefore, the processes e−γ→e−γBHe^{-}\gamma\to e^{-}\gamma B_{H} and e−γ→e−ZBHe^{-}\gamma\to e^{-}Z B_{H} provide a useful way to detect BHB_{H} and test the littlest Higgs model.Comment: 15 pages, 3 figures. Some typos have been corrected, we have added some new references, and there are also some changes in equation 1

    Dog phobia in a motion-blind patient

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    INTRODUCTION: A prominent neurophysiological model of phobia generation holds that specific phobia might result from the uncoupling of unaware subcortical fear responses from aware cortical fear responses. Former responses are thought to be automatic and fast, providing approximate information about the external stimulus, whereas the latter responses are more controlled and allow comparison with previous experience. Since only the cortical pathway carries information available to awareness, this model also accounts for the striking irrationality of specific phobia in humans. METHODS: Here, we report neuropsychological and neuro-ophthalmological findings in a 41-year-old patient who developed severe dog phobia following bilateral parietal lobe damage. RESULTS: The examinations showed a severe deficit in visual motion perception (visual motion blindness or akinetopsia) as well as spatial vision. Importantly, the patient was largely unaware of his visual deficits. CONCLUSION: Based on the present observation it is argued that irrational fear, as found in specific phobia, might not only result from a general uncoupling of aware cortical from unaware subcortical fear responses, but also from a functionally similar dissociation at the cortical level
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