3,003 research outputs found
A general interpolation scheme for thermal fluctuations in superconductors
We present a general interpolation theory for the phenomenological effects of
thermal fluctuations in superconductors. Fluctuations are described by a simple
gauge invariant extension of the gaussian effective potential for the
Ginzburg-Landau static model. The approach is shown to be a genuine variational
method, and to be stationary for infinitesimal gauge variations around the
Landau gauge. Correlation and penetration lengths are shown to depart from the
mean field behaviour in a more or less wide range of temperature below the
critical regime, depending on the class of material considered. The method is
quite general and yields a very good interpolation of the experimental data for
very different materials.Comment: some misprints have been corrected in Eq.(15),(19); more references
and comments have been adde
Efficacy of a novel neem oil formulation (RP03™) to control the poultry red mite Dermanyssus gallinae
Dermanyssus gallinae (Mesostigmata: Dermanyssidae) is the most harmful ectoparasite of laying hens, represents an occupational hazard for poultry workers, and a growing threat to medical science per se. There is increasing demand for alternative products, including plant-derived acaricides, with which to control the mite. The present study investigated the efficacy of neem oil against D. gallinae on a heavily infested commercial laying hen farm. A novel formulation of 20% neem oil, diluted from a 2400-p.p.m. azadirachtin-concentrated stock (RP03â ¢), was administered by nebulization three times in 1week. Using corrugated cardboard traps, mite density was monitored before, during and after treatment and results were statistically analysed. Mite populations in the treated block showed 94.65%, 99.64% and 99.80% reductions after the first, second and third product administrations, respectively. The rate of reduction of the mite population was significantly higher in the treated block (P<0.001) compared with the control and buffer blocks. The results suggest the strong bioactivity of neem, and specifically of the patented neem-based formulation RP03â ¢, against D. gallinae. The treatment was most effective in the 10days following the first application and its effects persisted for over 2months. Further studies will aim to overcome observed side effects of treatment represented by an oily layer on equipment and eggs
Efficacy of λ-cyhalothrin, amitraz, and phoxim against the poultry red mite Dermanyssus gallinae De Geer, 1778 (Mesostigmata: Dermanyssidae): an eight-year survey
Dermanyssus gallinae (De Geer, 1778) is a major problem for the poultry industry worldwide, as it negatively affects virtually all kinds of rearing systems. Therefore, the control of infestation has become a routine process, and its economic cost is constantly increasing. Until now, most of the control strategies have relied on the use of synthetic chemical drugs, but their efficacy is often questioned by the emergence and diffusion of resistant mite populations. With this in mind, the efficacy of λ-cyhalothrin, amitraz, and phoxim has been verified by testing them against 86 mite populations collected from the same number of poultry farms in Italy from 2008 to 2015. Assays were performed according to the filter paper method using the recommended, half, quarter, double and quadruple doses. The results showed that phoxim and amitraz were the most effective acaricides (median efficacies 80.35% and 80.83%, respectively), but amitraz exhibited a sharp fall in its efficacy during 2011 and 2012, while phoxim maintained its high effectiveness up to 2015, when it dropped. The overall median efficacy of λ-cyhalothrin was 58.33%. The data also highlighted the importance of the use of the right concentration, as an increase in dosage was not always useful against resistant populations, while its reduction also diminished efficacy, simultaneously increasing the risk for the development of resistance
Characteristic extraction in numerical relativity: binary black hole merger waveforms at null infinity
The accurate modeling of gravitational radiation is a key issue for
gravitational wave astronomy. As simulation codes reach higher accuracy,
systematic errors inherent in current numerical relativity wave-extraction
methods become evident, and may lead to a wrong astrophysical interpretation of
the data. In this paper, we give a detailed description of the
Cauchy-characteristic extraction technique applied to binary black hole
inspiral and merger evolutions to obtain gravitational waveforms that are
defined unambiguously, that is, at future null infinity. By this method we
remove finite-radius approximations and the need to extrapolate data from the
near zone. Further, we demonstrate that the method is free of gauge effects and
thus is affected only by numerical error. Various consistency checks reveal
that energy and angular momentum are conserved to high precision and agree very
well with extrapolated data. In addition, we revisit the computation of the
gravitational recoil and find that finite radius extrapolation very well
approximates the result at \scri. However, the (non-convergent) systematic
differences to extrapolated data are of the same order of magnitude as the
(convergent) discretisation error of the Cauchy evolution hence highlighting
the need for correct wave-extraction.Comment: 41 pages, 8 figures, 2 tables, added references, fixed typos. Version
matches published version
Finding Apparent Horizons in Dynamic 3D Numerical Spacetimes
We have developed a general method for finding apparent horizons in 3D
numerical relativity. Instead of solving for the partial differential equation
describing the location of the apparent horizons, we expand the closed 2D
surfaces in terms of symmetric trace--free tensors and solve for the expansion
coefficients using a minimization procedure. Our method is applied to a number
of different spacetimes, including numerically constructed spacetimes
containing highly distorted axisymmetric black holes in spherical coordinates,
and 3D rotating, and colliding black holes in Cartesian coordinates.Comment: 19 pages, 13 figures, LaTex, to appear in Phys. Rev. D. Minor changes
mad
Statistics of electromagnetic transitions as a signature of chaos in many-electron atoms
Using a configuration interaction approach we study statistics of the dipole
matrix elements (E1 amplitudes) between the 14 lower odd states with J=4 and
21st to 100th even states with J=4 in the Ce atom (1120 lines). We show that
the distribution of the matrix elements is close to Gaussian, although the
width of the Gaussian distribution, i.e. the root-mean-square matrix element,
changes with the excitation energy. The corresponding line strengths are
distributed according to the Porter-Thomas law which describes statistics of
transition strengths between chaotic states in compound nuclei. We also show
how to use a statistical theory to calculate mean squared values of the matrix
elements or transition amplitudes between chaotic many-body states. We draw
some support for our conclusions from the analysis of the 228 experimental line
strengths in Ce [J. Opt. Soc. Am. v. 8, p. 1545 (1991)], although direct
comparison with the calculations is impeded by incompleteness of the
experimental data. Nevertheless, the statistics observed evidence that highly
excited many-electron states in atoms are indeed chaotic.Comment: 16 pages, REVTEX, 4 PostScript figures (submitted to Phys Rev A
Kinome rewiring reveals AURKA limits PI3K-pathway inhibitor efficacy in breast cancer.
Dysregulation of the PI3K-AKT-mTOR signaling network is a prominent feature of breast cancers. However, clinical responses to drugs targeting this pathway have been modest, possibly because of dynamic changes in cellular signaling that drive resistance and limit drug efficacy. Using a quantitative chemoproteomics approach, we mapped kinome dynamics in response to inhibitors of this pathway and identified signaling changes that correlate with drug sensitivity. Maintenance of AURKA after drug treatment was associated with resistance in breast cancer models. Incomplete inhibition of AURKA was a common source of therapy failure, and combinations of PI3K, AKT or mTOR inhibitors with the AURKA inhibitor MLN8237 were highly synergistic and durably suppressed mTOR signaling, resulting in apoptosis and tumor regression in vivo. This signaling map identifies survival factors whose presence limits the efficacy of targeted therapies and reveals new drug combinations that may unlock the full potential of PI3K-AKT-mTOR pathway inhibitors in breast cancer
Statistical properties of power-law random banded unitary matrices in the delocalization-localization transition regime
Power-law random banded unitary matrices (PRBUM), whose matrix elements decay
in a power-law fashion, were recently proposed to model the critical statistics
of the Floquet eigenstates of periodically driven quantum systems. In this
work, we numerically study in detail the statistical properties of PRBUM
ensembles in the delocalization-localization transition regime. In particular,
implications of the delocalization-localization transition for the fractal
dimension of the eigenvectors, for the distribution function of the eigenvector
components, and for the nearest neighbor spacing statistics of the eigenphases
are examined. On the one hand, our results further indicate that a PRBUM
ensemble can serve as a unitary analog of the power-law random Hermitian matrix
model for Anderson transition. On the other hand, some statistical features
unseen before are found from PRBUM. For example, the dependence of the fractal
dimension of the eigenvectors of PRBUM upon one ensemble parameter displays
features that are quite different from that for the power-law random Hermitian
matrix model. Furthermore, in the time-reversal symmetric case the nearest
neighbor spacing distribution of PRBUM eigenphases is found to obey a
semi-Poisson distribution for a broad range, but display an anomalous level
repulsion in the absence of time-reversal symmetry.Comment: 10 pages + 13 fig
Stable characteristic evolution of generic 3-dimensional single-black-hole spacetimes
We report new results which establish that the accurate 3-dimensional
numerical simulation of generic single-black-hole spacetimes has been achieved
by characteristic evolution with unlimited long term stability. Our results
cover a selection of distorted, moving and spinning single black holes, with
evolution times up to 60,000M.Comment: 4 pages, 3 figure
Variation of electric shielding on virtual Frisch-grid detectors
Because of the low mobility of holes, CdZnTe (CZT) detectors operate as electron-transport-only type devices whose particular geometrical parameters and contacts configurations are specially chosen to minimize the contribution of uncollected holes into the output signal amplitudes (induction effect). Several detector configurations have been proposed to address this problem. One of them employs a large geometrical aspect ratio, parallelepiped-shaped crystal with two planar contacts on the top and bottom surfaces (anode and cathode) and an additional shielding electrode placed on a crystal\u27s side to create the virtual Frisch-grid effect. We studied the effect of the shielding electrode length, as well as its location, on the responses of 6 x 6 x 15 mm(3) virtual Frisch-grid detectors. We found that the length of the shielding electrode placed next to the anode can be reduced to 5 mm with no adverse effects on the device performance. Meanwhile, this allows for charge loss correction by reading the cathode signal
- …