1,762 research outputs found
From Taub Numbers to the Bondi Mass
Taub numbers are studied on asymptotically flat backgrounds with Killing
symmetries. When the field equations are solved for a background spacetime and
higher order functional derivatives (higher order variational derivatives of
the Hilbert Lagrangean) are solved for perturbations from the background, such
perturbed space-times admit zeroth, first, and second order Taub numbers.
Zeroth order Taub numbers are Komar constants (upto numerical factors) or
Penrose-Goldberg constants of the background. For a Killing symmetry of the
background, first order Taub numbers give the contribution of the linearized
perturbation to the associated backgound quantity, such as the perturbing mass.
Second order Taub numbers give the contribution of second order perturbations
to the background quantity. The Bondi mass is a sum of first and second order
Taubs numbers on a Minkowski background.Comment: To appear in the proceedings of the 8th Marcel Grossmann Conferenc
Recommended from our members
Effect of Different Media on the Bactericidal Activity of Colistin and on the Synergistic Combination With Azidothymidine Against mcr-1-Positive Colistin-Resistant Escherichia coli
Antimicrobial susceptibility testing (AST) performed according to defined guidelines is important to identify resistance and to predict the clinical success or failure of specific antibiotic therapy. However, these guidelines do not cover all physiological conditions that can have a tremendous impact on in vivo resistance. In this study, we tested the susceptibility of thirteen mcr-1-positive Escherichia coli strains against colistin, one of the last resort antibiotics for treating multi-drug resistant pathogens, in media recommended for ASTs as well as – physiologically more relevant – in human serum and artificial urine (AU). Minimal inhibitory concentration (MIC) values in heat-inactivated human serum were similar to those in cation-adjusted Mueller-Hinton broth (CAMHB), but reduced in native serum for almost all strains that could grow in this media. In AU MIC values for mcr-1 positive E. coli were increased significantly up to 16-fold compared to that in CAMBH, which did not apply to the colistin-susceptible E. coli strains tested. Although different growth media could affect the MIC of colistin alone, their impact on the synergistic effect of the combination with the antiviral drug azidothymidine was minimal. The higher divalent cation concentration combined with acidic pH values is most likely responsible for the increased MIC values of the mcr-1 harboring E. coli strains tested against colistin in AU compared to that in CAMHB. Antimicrobial susceptibility screening procedures for colistin using CAMHB only could lead to an underestimation of resistance under different physiological conditions. Therefore, not only pharmacokinetic but also pharmacodynamic studies in urine are as important as in serum or plasma
Time fractional Schrodinger equation
The Schrodinger equation is considered with the first order time derivative
changed to a Caputo fractional derivative, the time fractional Schrodinger
equation. The resulting Hamiltonian is found to be non-Hermitian and non-local
in time. The resulting wave functions are thus not invariant under time
reversal. The time fractional Schrodinger equation is solved for a free
particle and for a potential well. Probability and the resulting energy levels
are found to increase over time to a limiting value depending on the order of
the time derivative. New identities for the Mittag-Leffler function are also
found and presented in an appendix.Comment: 23 page
Type-II Bose-Mott insulators
The Mott insulating state formed from bosons is ubiquitous in solid He-4,
cold atom systems, Josephson junction networks and perhaps underdoped high-Tc
superconductors. We predict that close to the quantum phase transition to the
superconducting state the Mott insulator is not at all as featureless as is
commonly believed. In three dimensions there is a phase transition to a low
temperature state where, under influence of an external current, a
superconducting state consisting of a regular array of 'wires' that each carry
a quantized flux of supercurrent is realized. This prediction of the "type-II
Mott insulator" follows from a field theoretical weak-strong duality, showing
that this 'current lattice' is the dual of the famous Abrikosov lattice of
magnetic fluxes in normal superconductors. We argue that this can be exploited
to investigate experimentally whether preformed Cooper pairs exist in high-Tc
superconductors.Comment: RevTeX, 17 pages, 6 figures, published versio
Mandatory HIV Testing Issues in State Newborn Screening Programs
The newborn screening model is fairly straightforward. Typically, before the infant is discharged from the hospital (around 24 to 36 hours of age), heel stick blood is placed on special filter paper, dried, and mailed to the state health department for testing. Medical and laboratory research has led to the discovery that other diseases could also be screened in newborns using these dried blood specimens. Currently, all states and the District of Columbia test all newborns for at least PKU and congenital hypothyroidism. There are generally five criteria to satisfy before a disease is considered appropriate for newborn screening: 1. The disease must be well defined and serious enough to justify mass screening; 2. There must be an accurate testing method available; 3. The cost of the test must be reasonable; 4. There must be available treatment for the disorder; and 5. There must be adequate medical management facilities to refer infants for confirmatory diagnosis and treatment. Although newborn screening is often classified as genetic screening, these criteria do not require that the screened disorder have a genetic origin. In fact, congenital hypothyroidism, which is part of every newborn screening program in this country, is usually not a genetic disease
Mandatory HIV Testing Issues in State Newborn Screening Programs
The newborn screening model is fairly straightforward. Typically, before the infant is discharged from the hospital (around 24 to 36 hours of age), heel stick blood is placed on special filter paper, dried, and mailed to the state health department for testing. Medical and laboratory research has led to the discovery that other diseases could also be screened in newborns using these dried blood specimens. Currently, all states and the District of Columbia test all newborns for at least PKU and congenital hypothyroidism. There are generally five criteria to satisfy before a disease is considered appropriate for newborn screening: 1. The disease must be well defined and serious enough to justify mass screening; 2. There must be an accurate testing method available; 3. The cost of the test must be reasonable; 4. There must be available treatment for the disorder; and 5. There must be adequate medical management facilities to refer infants for confirmatory diagnosis and treatment. Although newborn screening is often classified as genetic screening, these criteria do not require that the screened disorder have a genetic origin. In fact, congenital hypothyroidism, which is part of every newborn screening program in this country, is usually not a genetic disease
Stationary Wavelet Processing and Data Imputing in Myoelectric Pattern Recognition on a Low-Cost Embedded System
Pattern recognition-based decoding of surface electromyography allows for intuitive and flexible control of prostheses but comes at the cost of sensitivity to in-band noise and sensor faults. System robustness can be improved with wavelet-based signal processing and data imputing, but no attempt has been made to implement such algorithms on real-time, portable systems. The aim of this work was to investigate the feasibility of low-latency, wavelet-based processing and data imputing on an embedded device capable of controlling upper-arm prostheses. Nine able-bodied subjects performed Motion Tests while inducing transient disturbances. Additional investigation was performed on pre-recorded Motion Tests from 15 able-bodied subjects with simulated disturbances. Results from real-time tests were inconclusive, likely due to the low number of disturbance episodes, but simulated tests showed significant improvements in most metrics for both algorithms. However, both algorithms also showed reduced responsiveness during disturbance episodes. These results suggest wavelet-based processing and data imputing can be implemented in portable, real-time systems to potentially improve robustness to signal distortion in prosthetic devices with the caveat of reduced responsiveness for the typically short duration of signal disturbances. The trade-off between large-scale signal corruption robustness and system responsiveness warrants further studies in daily life activities
Trapping of Rydberg Atoms in Tight Magnetic Microtraps
We explore the possibility to trap Rydberg atoms in tightly confining
magnetic microtraps. The trapping frequencies for Rydberg atoms are expected to
be influenced strongly by magnetic field gradients. We show that there are
regimes where Rydberg atoms can be trapped. Moreover, we show that so-called
magic trapping conditions can be found for certain states of rubidium, where
both Rydberg atoms and ground state atoms have the same trapping frequencies.
Magic trapping is highly beneficial for implementing quantum gate operations
that require long operation times
- …