12,107 research outputs found
Greene Gardens
The case describes the 2006 E. coli outbreak in the California spinach industry. The case unfolds over a period of about one month, with four separate eventful days described in detail. At the end of the narrative for each day, the reader is asked to decide how he or she would respond to the events and justify his or her decision.business ethics, communication, crisis management, spinach, Food Consumption/Nutrition/Food Safety, Health Economics and Policy, Teaching/Communication/Extension/Profession, Q10, Q13,
Excitons in Electrostatic Traps
We consider in-plane electrostatic traps for indirect excitons in coupled
quantum wells, where the traps are formed by a laterally modulated gate
voltage. An intrinsic obstacle for exciton confinement in electrostatic traps
is an in-plane electric field that can lead to exciton dissociation. We propose
a design to suppress the in-plane electric field and, at the same time, to
effectively confine excitons in the electrostatic traps. We present
calculations for various classes of electrostatic traps and experimental proof
of principle for trapping of indirect excitons in electrostatic traps.Comment: 4 pages, 3 figure
Multimodal Integration: fMRI, MRI, EEG, MEG
This chapter provides a comprehensive survey of the motivations, assumptions and pitfalls associated with combining signals such as fMRI with EEG or MEG. Our initial focus in the chapter concerns mathematical approaches
for solving the localization problem in EEG and MEG. Next we document the most recent and promising ways in which these signals can be combined with fMRI. Specically, we look at correlative analysis, decomposition techniques, equivalent dipole tting, distributed sources modeling, beamforming, and Bayesian methods. Due to difculties in assessing ground truth of a combined signal in any realistic experiment difculty further confounded by lack of accurate biophysical models of BOLD signal we are cautious to be optimistic about multimodal integration. Nonetheless, as we highlight and explore the technical and methodological difculties of fusing heterogeneous signals, it seems likely that correct fusion of multimodal data will allow previously inaccessible spatiotemporal structures to be visualized and formalized and thus eventually become a useful tool in brain imaging research
Path Integral Approach to Residual Gauge Fixing
In this paper we study the question of residual gauge fixing in the path
integral approach for a general class of axial-type gauges including the
light-cone gauge. We show that the two cases -- axial-type gauges and the
light-cone gauge -- lead to very different structures for the explicit forms of
the propagator. In the case of the axial-type gauges, fixing the residual
symmetry determines the propagator of the theory completely. On the other hand,
in the light-cone gauge there is still a prescription dependence even after
fixing the residual gauge symmetry, which is related to the existence of an
underlying global symmetry.Comment: revtex 13pages, slightly expanded discussion, version to be published
in Physical Review
Fusion of functional brain imaging modalities via linear programming.
Proposed method makes a number of simplifying assumptions which convert the EEG/FMRI integration problem into optimization of a convex function, of a form amenable to efficient solution as a very sparse linear programming (LP) problem. The assumptions made in doing this are, surprisingly, in general somewhat more robust than those generally used to cast EEG/FMRI integration as optimization of a non-convex function not amenable to efficient global optimization. This is because the L1 norm used here corresponds to a more robust statistical estimator than the L2 normal generally used For this reason, even though this technique results in a tractable global optimization, it is more robust to non-Gaussian noise and outliers than approaches that make the Gaussian noise assumption [1]. Current poster presents formulation of the problem together with results obtained on artificial data
Correction to the Moliere's formula for multiple scattering
The quasiclassical correction to the Moliere's formula for multiple
scattering is derived. The consideration is based on the scattering amplitude,
obtained with the first quasiclassical correction taken into account for
arbitrary localized but not spherically symmetric potential. Unlike the leading
term, the correction to the Moliere's formula contains the target density
and thickness not only in the combination (areal density). Therefore,
this correction can be reffered to as the bulk density correction. It turns out
that the bulk density correction is small even for high density. This result
explains the wide region of applicability of the Moliere's formula.Comment: 6 pages, RevTe
Low-temperature laser-stimulated controllable generation of micro-bubbles in a water suspension of absorptive colloid particles
Covariant Equilibrium Statistical Mechanics
A manifest covariant equilibrium statistical mechanics is constructed
starting with a 8N dimensional extended phase space which is reduced to the 6N
physical degrees of freedom using the Poincare-invariant constrained
Hamiltonian dynamics describing the micro-dynamics of the system. The reduction
of the extended phase space is initiated forcing the particles on energy shell
and fixing their individual time coordinates with help of invariant time
constraints. The Liouville equation and the equilibrium condition are
formulated in respect to the scalar global evolution parameter which is
introduced by the time fixation conditions. The applicability of the developed
approach is shown for both, the perfect gas as well as the real gas. As a
simple application the canonical partition integral of the monatomic perfect
gas is calculated and compared with other approaches. Furthermore,
thermodynamical quantities are derived. All considerations are shrinked on the
classical Boltzmann gas composed of massive particles and hence quantum effects
are discarded.Comment: 22 pages, 1 figur
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