1,064 research outputs found
DdcA antagonizes a bacterial DNA damage checkpoint
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147820/1/mmi14151.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147820/2/mmi14151_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147820/3/mmi14151-sup-0001-Supinfo.pd
General solution of an exact correlation function factorization in conformal field theory
We discuss a correlation function factorization, which relates a three-point
function to the square root of three two-point functions. This factorization is
known to hold for certain scaling operators at the two-dimensional percolation
point and in a few other cases. The correlation functions are evaluated in the
upper half-plane (or any conformally equivalent region) with operators at two
arbitrary points on the real axis, and a third arbitrary point on either the
real axis or in the interior. This type of result is of interest because it is
both exact and universal, relates higher-order correlation functions to
lower-order ones, and has a simple interpretation in terms of cluster or loop
probabilities in several statistical models. This motivated us to use the
techniques of conformal field theory to determine the general conditions for
its validity.
Here, we discover a correlation function which factorizes in this way for any
central charge c, generalizing previous results. In particular, the
factorization holds for either FK (Fortuin-Kasteleyn) or spin clusters in the
Q-state Potts models; it also applies to either the dense or dilute phases of
the O(n) loop models. Further, only one other non-trivial set of highest-weight
operators (in an irreducible Verma module) factorizes in this way. In this case
the operators have negative dimension (for c < 1) and do not seem to have a
physical realization.Comment: 7 pages, 1 figure, v2 minor revision
Factorization of correlations in two-dimensional percolation on the plane and torus
Recently, Delfino and Viti have examined the factorization of the three-point
density correlation function P_3 at the percolation point in terms of the
two-point density correlation functions P_2. According to conformal invariance,
this factorization is exact on the infinite plane, such that the ratio R(z_1,
z_2, z_3) = P_3(z_1, z_2, z_3) [P_2(z_1, z_2) P_2(z_1, z_3) P_2(z_2,
z_3)]^{1/2} is not only universal but also a constant, independent of the z_i,
and in fact an operator product expansion (OPE) coefficient. Delfino and Viti
analytically calculate its value (1.022013...) for percolation, in agreement
with the numerical value 1.022 found previously in a study of R on the
conformally equivalent cylinder. In this paper we confirm the factorization on
the plane numerically using periodic lattices (tori) of very large size, which
locally approximate a plane. We also investigate the general behavior of R on
the torus, and find a minimum value of R approx. 1.0132 when the three points
are maximally separated. In addition, we present a simplified expression for R
on the plane as a function of the SLE parameter kappa.Comment: Small corrections (final version). In press, J. Phys.
Exact factorization of correlation functions in 2-D critical percolation
By use of conformal field theory, we discover several exact factorizations of
higher-order density correlation functions in critical two-dimensional
percolation. Our formulas are valid in the upper half-plane, or any conformally
equivalent region. We find excellent agreement of our results with
high-precision computer simulations. There are indications that our formulas
hold more generally.Comment: 6 pages, 3 figures. Oral presentation given at STATPHYS 23. V2: Minor
additions and corrections, figures improve
Distraction Effects of Phone Use During a Crucial Driving Maneuver
Forty-two licensed drivers were tested in an experiment that required them to react to an invehicle phone at precisely the same time as they were faced with making a crucial driving decision. Using test track facilities, we extended a previous evaluation of this form to include examination of the influence of driver gender and driver age. Specifically, each driver was given task practice and then performed two blocks of twenty-four trials each, where one trial represented a circuit of the test track. Half of the trials were control conditions in which neither the stop-light was activated or the in-vehicle phone triggered. Four trials required only stopping and a further four only phone response. The remaining four trials required the driver to complete each task simultaneously. The order of presentation of specific trials was randomized. The invehicle phone response task also contained an embedded memory task that was evaluated at the end of each trial. Results confirmed previous observations of slower task response followed by increased braking and that these patterns varied by driver age and gender. Most importantly, we recorded a critical 15% increase in non-response to the stop-light in the presence of the phone distraction task which represents stop light violations on the open road. Further, results showed that age had a much large effect on response than gender, especially on task components that required speed of response. Since driving represents a highly complex and interactive environment, it is not possible to specify a simplistic relationship between these distraction effects and outcome accident patterns. However, we can conclude that such technologies erode performance safety margin and distract drivers from their critical primary task of vehicle control. As such there is expectedly a causal relation in accident outcome that is a crucial concern for invehicle device designers and for all others seeking to ameliorate the adverse impact of vehicle accidents
America For Sale? Foreign Investments in the U.S., a German Perspective
The University of Georgia School of Law’s Dean Rusk Center and UGA’s German-American Law Society sponsored a panel discussion on the potential impacts of foreign investments in the United States. The lecture, titled America For Sale? Foreign Investments in the U.S., a German Perspective, took place on Feb. 16, 2010 at 12:30 p.m. in the Larry Walker Room of Dean Rusk Hall
Electron transport in the dye sensitized nanocrystalline cell
Dye sensitised nanocrystalline solar cells (Gr\"{a}tzel cells) have achieved
solar-to-electrical energy conversion efficiencies of 12% in diffuse daylight.
The cell is based on a thin film of dye-sensitised nanocrystalline TiO
interpenetrated by a redox electrolyte. The high surface area of the TiO
and the spectral characteristics of the dye allow the device to harvest 46% of
the solar energy flux. One of the puzzling features of dye-sensitised
nano-crystalline solar cells is the slow electron transport in the titanium
dioxide phase. The available experimental evidence as well as theoretical
considerations suggest that the driving force for electron collection at the
substrate contact arises primarily from the concentration gradient, ie the
contribution of drift is negligible. The transport of electrons has been
characterised by small amplitude pulse or intensity modulated illumination.
Here, we show how the transport of electrons in the Gr\"{a}tzel cell can be
described quantitatively using trap distributions obtained from a novel charge
extraction method with a one-dimensional model based on solving the continuity
equation for the electron density. For the first time in such a model, a back
reaction with the I ions in the electrolyte that is second order in the
electron density has been included.Comment: 6 pages, 5 figures, invited talk at the workshop 'Nanostructures in
Photovoltaics' to appear in Physica
Percolation Crossing Formulas and Conformal Field Theory
Using conformal field theory, we derive several new crossing formulas at the
two-dimensional percolation point. High-precision simulation confirms these
results. Integrating them gives a unified derivation of Cardy's formula for the
horizontal crossing probability , Watts' formula for the
horizontal-vertical crossing probability , and Cardy's formula for
the expected number of clusters crossing horizontally . The
main step in our approach implies the identification of the derivative of one
primary operator with another. We present operator identities that support this
idea and suggest the presence of additional symmetry in conformal field
theories.Comment: 12 pages, 5 figures. Numerics improved; minor correction
Polarimetry of the Type Ia Supernova SN 1996X
We present broad-band and spectropolarimetry of the Type Ia SN 1996X obtained
on April 14, 1996 (UT), and broad-band polarimetry of SN 1996X on May 22,1996,
when the supernova was about a week before and 4 weeks after optical maximum,
respectively. The Stokes parameters derived from the broad-band polarimetry are
consistent with zero polarization. The spectropolarimetry, however, shows broad
spectral features which are due intrinsically to an asymmetric SN atmosphere.
The spectral features in the flux spectrum and the polarization spectrum show
correlations in the wavelength range from 4900 AA up to 5500 AA. The degree of
this intrinsic component is low (<0.3 %). Theoretical polarization spectra have
been calculated. It is shown that the polarization spectra are governed by line
blending. Consequently, for similar geometrical distortions, the residual
polarization is smaller by about a factor of 2 to 3 compared to the less
blended Type II atmosphere, making it intrinsically harder to detect
asphericities in SNIa. Comparison with theoretical model polarization spectra
shows a resemblance to the observations. Taken literally, this implies an
asphericity of about 11 % in the chemical distribution in the region of partial
burning. This may not imperil the use of Type Ia supernovae as standard candles
for distance determination, but nontheless poses a source of uncertainty. SN
1996X is the first Type Ia supernova for which spectropolarimetry revealed a
polarized component intrinsic to the supernova and the first Type Ia with
spectropolarimetry well prior to optical maximum.Comment: 7 pages, 5 figures, macros 'aas2pp4.sty,psfig.tex'. LaTeX Style.
Astrophysical Journal Letters, submitted September 199
Role of carnitine in disease
Carnitine is a conditionally essential nutrient that plays a vital role in energy production and fatty acid metabolism. Vegetarians possess a greater bioavailability than meat eaters. Distinct deficiencies arise either from genetic mutation of carnitine transporters or in association with other disorders such as liver or kidney disease. Carnitine deficiency occurs in aberrations of carnitine regulation in disorders such as diabetes, sepsis, cardiomyopathy, malnutrition, cirrhosis, endocrine disorders and with aging. Nutritional supplementation of L-carnitine, the biologically active form of carnitine, is ameliorative for uremic patients, and can improve nerve conduction, neuropathic pain and immune function in diabetes patients while it is life-saving for patients suffering primary carnitine deficiency. Clinical application of carnitine holds much promise in a range of neural disorders such as Alzheimer's disease, hepatic encephalopathy and other painful neuropathies. Topical application in dry eye offers osmoprotection and modulates immune and inflammatory responses. Carnitine has been recognized as a nutritional supplement in cardiovascular disease and there is increasing evidence that carnitine supplementation may be beneficial in treating obesity, improving glucose intolerance and total energy expenditure
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