663 research outputs found
Meaningful Toxicology
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
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
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
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 and
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 mixing angle and on the
mass scale of the corresponding physical new neutral gauge boson , and
establish a lower bound on the mass of the additional new neutral gauge boson
. 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
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
mixing angle to a very small value of O(0.001), and the lower bounds on
and on 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
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
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
The T-odd leptons predicted by the littlest model with T-parity can
be pair produced via the subprocesses ,
, and (= or
) at the Large Hadron Collider . 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
process can reach .Comment: 12 pages, 2 figure
Lepton flavor violation decays in the topcolor-assisted technicolor model and the littlest Higgs model with parity
The new particles predicted by the topcolor-assisted technicolor ()
model and the littlest Higgs model with T-parity (called model) can
induce the lepton flavor violation () couplings at tree level or one loop
level, which might generate large contributions to some processes. Taking
into account the constraints of the experimental data on the relevant free
parameters, we calculate the branching ratios of the decay processes
with = , and
in the context of these two kinds of new physics models. We find
that the model and the model can indeed produce significant
contributions to some of these decay processes.Comment: 24 pages, 7 figure
The production of the new gauge boson via collision in the littlest Higgs model
The new lightest gauge boson with mass of a few hundred GeV is
predicted in the littlest Higgs model. should be accessible in the planed
ILC and the observation of such particle can strongly support the littlest
Higgs model. The realization of and collision will
open a wider window to probe . In this paper, we study the new gauge boson
production processes and
at the ILC. Our results show that the production
cross section of the process is less than one fb
in the most parameter spaces while the production cross section of the process
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 . Because the
final electron and photon beams can be easily identified and the signal can be
easily distinguished from the background produced by and decaying,
should be detectable via collision at the ILC. Therefore, the
processes and
provide a useful way to detect 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
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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