A common tool in Casimir physics (and many other areas) is the asymptotic (high-frequency) expansion of eigenvalue densities, employed as either input or output of calculations of the asymptotic behavior of various Green functions. Here we clarify so
me fine points and potentially confusing aspects of the subject. In particular, we show how recent observations of Kolomeisky et al. [Phys. Rev. A 87 (2013) 042519] fit into the established framework of the distributional asymptotics of spectral functions.
Pulsar nulling is a phenomenon of sudden cessation of pulse emission for a number of periods. The nulling fraction was often used to characterize the phenomenon. We propose a new method to analyse pulsar nulling phenomenon, by involving two key param
eters, the nulling degree, $chi$, which is defined as the angle in a rectangular coordinates for the numbers of nulling periods and bursting periods, and the nulling scale, $ N $, which is defined as the effective length of the consecutive nulling periods and bursting periods. The nulling degree $chi$ can be calculated by $tan chi = N_{rm nulling} / N_{rm bursting} $ and the mean is related to the nulling fraction, while the nulling scale, $ N $, is also a newly defined fundamental parameter which indicates how often the nulling occurs. We determined the distributions of $chi$ and $ N $ for 10 pulsars by using the data in literature. We found that the nulling degree $chi$ indicates the relative length of nulling to that of bursting, and the nulling scale $ N $ is found to be related to the derivative of rotation frequency and hence the loss rate of rotational energy of pulsars. Their deviations reflect the randomness of the nulling process.
This case study tests the possibility of prediction for success (or winner) components of four stock & shares market indices in a time period of three years from 02-Jul-2009 to 29-Jun-2012.We compare their performance ain two time frames: initial fra
me three months at the beginning (02/06/2009-30/09/2009) and the final three month frame (02/04/2012-29/06/2012). To label the components, average price ratio between two time frames in descending order is computed. The average price ratio is defined as the ratio between the mean prices of the beginning and final time period. The winner components are referred to the top one third of total components in the same order as average price ratio it means the mean price of final time period is relatively higher than the beginning time period. The loser components are referred to the last one third of total components in the same order as they have higher mean prices of beginning time period. We analyse, is there any information about the winner-looser separation in the initial fragments of the daily closing prices log-returns time series. The Leave-One-Out Cross-Validation with k-NN algorithm is applied on the daily log-return of components using a distance and proximity in the experiment. By looking at the error analysis, it shows that for HANGSENG and DAX index, there are clear signs of possibility to evaluate the probability of long-term success. The correlation distance matrix histograms and 2-D/3-D elastic maps generated from ViDaExpert show that the winner components are closer to each other and winner/loser components are separable on elastic maps for HANGSENG and DAX index while for the negative possibility indices, there is no sign of separation.
In conventional and high transition temperature copper oxide and iron pnictide superconductors, the Cooper pairs all have even parity. As a rare exception, Sr$_2$RuO$_4$ is the first prime candidate for topological chiral p-wave superconductivity, wh
ich has time-reversal breaking odd-parity Cooper pairs known to exist before only in the neutral superfluid $^3$He. However, there are several key unresolved issues hampering the microscopic description of the unconventional superconductivity. Spin fluctuations at both large and small wavevectors are present in experiments, but how they arise and drive superconductivity is not yet clear. Spontaneous edge current is expected but not observed conclusively. Specific experiments point to highly band- and/or momentum-dependent energy gaps for quasiparticle excitations in the superconducting state. Here, by comprehensive functional renormalization group calculations with all relevant bands, we disentangle the various competing possibilities. In particular we show the small wavevector spin fluctuations, driven by a single two-dimensional band, trigger p-wave superconductivity with quasi-nodal energy gaps.
We report on the first systematic study of spin transport in bilayer graphene (BLG) as a function of mobility, minimum conductivity, charge density and temperature. The spin relaxation time $tau_s$ scales inversely with the mobility $mu$ of BLG sampl
es both at room temperature and at low temperature. This indicates the importance of Dyakonov - Perel spin scattering in BLG. Spin relaxation times of up to 2 ns are observed in samples with the lowest mobility. These times are an order of magnitude longer than any values previously reported for single layer graphene (SLG). We discuss the role of intrinsic and extrinsic factors that could lead to the dominance of Dyakonov-Perel spin scattering in BLG. In comparison to SLG, significant changes in the density dependence of $tau_s$ are observed as a function of temperature.
Using a hydrodynamics plus N-body simulation of galaxy cluster formation within a large volume and mock Chandra X-ray observations, we study the form and evolution of the intrinsic scatter about the best-fit X-ray temperature-mass relation for cluste
rs. We investigate the physical origin of the scatter by correlating it with quantities that are closely related to clusters formation and merging histories. We also examine the distribution of the scatter for merging and nonmerging populations, identified using halo merger trees derived from the simulation as well as X-ray substructure measures. We find a strong correlation between the scatter in the M-T_X relation and the halo concentration, in the sense that more concentrated clusters tend to be cooler than clusters with similar masses. No bias is found between the merging and relaxed clusters, but merging clusters generally have greater scatter, which is related to the properties of the distribution of halo concentrations. We also detect a signature of non-lognormality in the distribution of scatter for our simulated clusters both at z=0 and at z=1. A detailed comparison of merging clusters identified by substructure measures and by halo merger trees is given in the discussion. We conclude that, when cooling-related effects are neglected, the variation in halo concentrations is a more important factor for driving the intrinsic scatter in the M-T_X relation, while departures from hydrostatic equilibrium due to cluster mergers have a minor effect.
Spiral galaxies dominate the local galaxy population. Disks are known to be fragile with respect to collisions. Thus it is worthwhile to probe under which conditions a disk can possibly survive such interactions. We present a detailed morpho-kinemati
cs study of a massive galaxy with two nuclei, J033210.76--274234.6, at z=0.4. The morphological analysis reveals that the object consists of two bulges and a massive disk, as well as a faint blue ring. Combining the kinematics with morphology we propose a near-center collision model to interpret the object. We find that the massive disk is likely to have survived the collision of galaxies with an initial mass ratio of ~4:1. The N-body/SPH simulations show that the collision possibly is a single-shot polar collision with a very small pericentric distance of ~1 kpc and that the remnant of the main galaxy will be dominated by a disk. The results support the disk survival hypothesis. The survival of the disk is related to the polar collision with an extremely small pericentric distance. With the help of N-body/SPH simulations we find the probability of disk survival is quite large regardless whether the two galaxies merge or not.
We demonstrate an efficient scheme for continuous trap loading based upon spatially selective optical pumping. We discuss the case of $^{1}$S$_{0}$ calcium atoms in an optical dipole trap (ODT), however, similar strategies should be applicable to a w
ide range of atomic species. Our starting point is a reservoir of moderately cold ($approx 300 mu$K) metastable $^{3}$P$_{2}$-atoms prepared by means of a magneto-optic trap (triplet-MOT). A focused 532 nm laser beam produces a strongly elongated optical potential for $^{1}$S$_{0}$-atoms with up to 350 $mu$K well depth. A weak focused laser beam at 430 nm, carefully superimposed upon the ODT beam, selectively pumps the $^{3}$P$_{2}$-atoms inside the capture volume to the singlet state, where they are confined by the ODT. The triplet-MOT perpetually refills the capture volume with $^{3}$P$_{2}$-atoms thus providing a continuous stream of cold atoms into the ODT at a rate of $10^7 $s$^{-1}$. Limited by evaporation loss, in 200 ms we typically load $5 times 10^5$ atoms with an initial radial temperature of 85 $mu$K. After terminating the loading we observe evaporation during 50 ms leaving us with $10^5$ atoms at radial temperatures close to 40 $mu$K and a peak phase space density of $6.8 times 10^{-5}$. We point out that a comparable scheme could be employed to load a dipole trap with $^{3}$P$_{0}$-atoms.
