837 research outputs found
A KLUYVERA-CRYOCRESCENS STRAIN FROM A GALLBLADDER INFECTION
The isolation and the identification of a pure-culture Kluyvera cryocrescens
strain in a gall.bladder pus specimen from a 76-year-old woman vcith acute cholecystitis
is described. This is the first Teported recovery of a K. cryocrescens
strain from such a sample
Effects of carbon dioxide on trapped electrolyte hydrogen-oxygen, alkaline fuel cells
Effects of carbon dioxide on trapped electrolyte hydrogen-oxygen alkaline fuel cell
Some new results concerning the vacuum in Dirac Hole Theory
In Dirac's hole theory the vacuum state is generally believed to be the state
of minimum energy. It will be shown that this is not, in fact, the case and
that there must exist states in hole theory with less energy than the vacuum
state. It will be shown that energy can be extracted from the hole theory
vacuum state through the application of an electric field.Comment: Accepted by Physica Scripta, 19 page
Klein tunneling and Dirac potentials in trapped ions
We propose the quantum simulation of the Dirac equation with potentials,
allowing the study of relativistic scaterring and the Klein tunneling. This
quantum relativistic effect permits a positive-energy Dirac particle to
propagate through a repulsive potential via the population transfer to
negative-energy components. We show how to engineer scalar, pseudoscalar, and
other potentials in the 1+1 Dirac equation by manipulating two trapped ions.
The Dirac spinor is represented by the internal states of one ion, while its
position and momentum are described by those of a collective motional mode. The
second ion is used to build the desired potentials with high spatial
resolution.Comment: 4 pages, 3 figures, minor change
Is patient acceptance of the diagnosis of psychogenic nonepileptic seizures linked to symptomatology?
peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=ncen2
Zitterbewegung of relativistic electrons in a magnetic field and its simulation by trapped ions
One-electron 3+1 and 2+1 Dirac equations are used to calculate the motion of
a relativistic electron in a vacuum in the presence of an external magnetic
field. First, calculations are carried on an operator level and exact
analytical results are obtained for the electron trajectories which contain
both intraband frequency components, identified as the cyclotron motion, as
well as interband frequency components, identified as the trembling motion
(Zitterbewegung, ZB). Next, time-dependent Heisenberg operators are used for
the same problem to compute average values of electron position and velocity
employing Gaussian wave packets. It is shown that the presence of a magnetic
field and the resulting quantization of the energy spectrum has pronounced
effects on the electron Zitterbewegung: it introduces intraband frequency
components into the motion, influences all the frequencies and makes the motion
stationary (not decaying in time) in case of the 2+1 Dirac equation. Finally,
simulations of the 2+1 Dirac equation and the resulting electron ZB in the
presence of a magnetic field are proposed and described employing trapped ions
and laser excitations. Using simulation parameters achieved in recent
experiments of Gerritsma and coworkers we show that the effects of the
simulated magnetic field on ZB are considerable and can certainly be observed.Comment: 19 pages, 9 figures, published versio
T-MOD PATHWAY, A REDUCED SEQUENCE FOR IDENTIFICATION OF GRAM-NEGATIVE URINARY-TRACT PATHOGENS
In this paper, we describe a reduced sequence of identification that includes T-mod medium, a selective and
differential isolation medium which allows accurate presumptive identification of the most common gramnegative
bacteria encountered in urine samples. The present study, performed on bacteria isolated from 1,762
independent urine samples, has shown that a few selected tests (lysine and ornithine decarboxylase, urease and
trehalose fermentation tests) improve the identification accuracy of T-mod, making it possible both to identify
the less frequent species and to prevent some misidentifications of Klebsiella pneumoniae and Proteus mirabilis.
The proposed work flow agreed with conventional identification protocols to a 99.3% extent and allowed
identification of 87.4% of the isolates directly from the primary plate, 11.4% after 1 to 3 additional tests, and
1.2% after an identification gallery
Pedestrian index theorem a la Aharonov-Casher for bulk threshold modes in corrugated multilayer graphene
Zero-modes, their topological degeneracy and relation to index theorems have
attracted attention in the study of single- and bilayer graphene. For
negligible scalar potentials, index theorems explain why the degeneracy of the
zero-energy Landau level of a Dirac hamiltonian is not lifted by gauge field
disorder, for example due to ripples, whereas other Landau levels become
broadened by the inhomogenous effective magnetic field. That also the bilayer
hamiltonian supports such protected bulk zero-modes was proved formally by
Katsnelson and Prokhorova to hold on a compact manifold by using the
Atiyah-Singer index theorem. Here we complement and generalize this result in a
pedestrian way by pointing out that the simple argument by Aharonov and Casher
for degenerate zero-modes of a Dirac hamiltonian in the infinite plane extends
naturally to the multilayer case. The degeneracy remains, though at nonzero
energy, also in the presence of a gap. These threshold modes make the spectrum
asymmetric. The rest of the spectrum, however, remains symmetric even in
arbitrary gauge fields, a fact related to supersymmetry. Possible benefits of
this connection are discussed.Comment: 6 pages, 2 figures. The second version states now also in words that
the conjugation symmetry that in the massive case gets replaced by
supersymmetry is the chiral symmetry. Changes in figure
NEW PLATE MEDIUM FOR SCREENING AND PRESUMPTIVE IDENTIFICATION OF GRAM-NEGATIVE URINARY-TRACT PATHOGENS
A new selective, differential plating medium to screen the common gram-negative urinary tract pathogens is
described. The medium combines adonitol fermentation, phenylalanine deaminase, and P-glucuronidase tests
and allows the indole and cytochrome oxidase tests to be performed directly from the plates. High-level
agreement with individual conventional tests was recorded in comparative studies with 504 cultures of
gram-negative rods. There was 100% agreement, except for the Providencia spp. indole spot test (61.6%
agreement). Adonitol fermentation by Providencia species could not be determined. Escherichia coli, Klebsiella
pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa were identified with a high efficiency (100, 85.7,
83.5, and 100% agreement, respectively) without further testing. There was 96% overall agreement for the 267
infected urine samples tested
Stability of Impurities with Coulomb Potential in Graphene with Homogeneous Magnetic Field
Given a 2-dimensional no-pair Weyl operator with a point nucleus of charge Z,
we show that a homogeneous magnetic field does not lower the critical charge
beyond which it collapses.Comment: J. Math. Phys. (in press
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