2,895 research outputs found
Superconducting Dome from Holography
We find a regime in which a strongly coupled striped superconductor features
a superconducting dome. This regime is signified by i) a modulating chemical
potential that averages to zero, and ii) a superconducting order parameter that
has a scaling dimension larger than 3/2 but less than or equal to 3. We also
find that in this regime, the order parameter exhibits a mild dependence on the
modulation wavelength of the stripe.Comment: 5 pages, 4 figure
Enhancement of Critical Temperature of a Striped Holographic Superconductor
We study the interplay between the stripe order and the superconducting order
in a strongly coupled striped superconductor using gauge/gravity duality. In
particular, we study the effects of inhomogeneity introduced by the stripe
order on the superconducting transition temperature beyond the mean field level
by including the effects of backreaction onto the spacetime geometry in the
dual gravitational picture. We find that inhomogeneity \emph{enhances} the
critical temperature relative to its value for the uniform system.Comment: 8 pages, 7 figure
Deep Unsupervised Learning using Nonequilibrium Thermodynamics
A central problem in machine learning involves modeling complex data-sets
using highly flexible families of probability distributions in which learning,
sampling, inference, and evaluation are still analytically or computationally
tractable. Here, we develop an approach that simultaneously achieves both
flexibility and tractability. The essential idea, inspired by non-equilibrium
statistical physics, is to systematically and slowly destroy structure in a
data distribution through an iterative forward diffusion process. We then learn
a reverse diffusion process that restores structure in data, yielding a highly
flexible and tractable generative model of the data. This approach allows us to
rapidly learn, sample from, and evaluate probabilities in deep generative
models with thousands of layers or time steps, as well as to compute
conditional and posterior probabilities under the learned model. We
additionally release an open source reference implementation of the algorithm
Universal interactive preferences
We prove that a universal preference type space exists under much more general conditions than those postulated by Epstein and Wang (1996). To wit, it is enough that preferences can be encoded by a countable collection of continuous functionals, while the preferences themselves need not necessarily be continuous or regular, like, e.g., in the case of lexicographic preferences. The proof relies on a far-reaching generalization of a method developed by Heifetz and Samet (1998)
Resonance production in central pp collisions at the CERN Omega Spectrometer
A study of resonance production in central pp collisions is presented as a
function of several kinematical variables. In particular the difference in the
transverse momentum (dPT) of the exchanged particles shows that undisputed
qqbar mesons are suppressed at small dPT whereas glueball candidates are
enhanced and in addition, the azimuthal angle phi gives information on the
nature of the Pomeron.Comment: 14 pages, Latex, 5 Figure
Phase analysis and dielectric properties of ceramics in PbO-MgO-ZnO-Nb<SUB>2</SUB>O<SUB>5</SUB> system: a comparative study of materials obtained by ceramic and molten salt synthesis routes
Compositions of the type 3PbO-MgO/ZnO-Nb2O5 were synthesized by the ceramic route at 1000°C and sintered at 1200°C. Powder X-ray diffraction studies of the 1000°C heated products show the presence of the cubic pyrochlore and the columbite (Mg/ZnNb2O6) type phase in the ratio of 3 : 1 for all possible combinations of MgO and ZnO. Further heating at 1200°C led to a decrease in the cubic pyrochlore phase and an increase in the columbite phase by around 10%. Compacted pellets sintered further showed the appearance of the perovskite phase. Similar compositions synthesized using the KCl-NaCl molten salt method at 900°C for 6 h gave a significant amount of the cubic perovskite related phase of the type Pb(Mg/Zn)1/3Nb2/3O3 for all compositions containing MgO. The amount of the perovskite phase was nearly 55% for the Mg rich compositions and decreased with increase in Zn content, the pure Zn composition yielding mainly the cubic pyrochlore phase. On sintering these phases at 1000°C the perovskite phase content decreased. The dielectric constant of the composite materials formed by the ceramic route was in the region of 14 to 20 and varied little with frequency. The composites obtained by the molten salt method, however, showed much larger dielectric constants in the region 40-150 at 500 kHz for various compositions. The dielectric loss tangent of these composites were lower by an order (0.005-0.03 at 500 kHz) compared to the ceramic route
Study of Ni and Zn doped CeOFeAs: Effect on the structural transition and specific heat capacity
We have systematically studied the substitution of nonmagnetic Zn and
magnetic Ni at iron sites in Ce based oxypnictide. The parent compound
(CeOFeAs) shows an anomaly in resistivity around 150 K due to structural
transition from tetragonal (space group: P4/nmm) to orthorhombic structure
(space group: Cmma). Substitution of Zn suppresses this anomaly to lower
temperature (~130 K) but Ni substitution does not show any anomaly around this
temperature and the compound behaves like a metal. Further, we find that non
magnetic (Zn) doping leads to higher impurity scattering as compared to
magnetic Ni doping. Similar to the resistivity measurement, the specific heat
shows another jump near 4 K for CeOFeAs. This is attributed to the ordering of
Ce3+ moments. This peak shifts to 3.8 K for Zn substituted compound and there
is no change in the ordering temperature in the Ni substituted CeOFeAs. These
peaks are broadened in applied magnetic field (5 T) and the calculated magnetic
entropy tends to saturate at the same value for 0 T and 5 T external magnetic
field.Comment: 16 pages Text+Fig
The Impact of Mergers and Acquisitions on Financial Performance of Banks in the Kingdom of Bahrain during 2004-15
Following the 2007 global financial crisis, more than 15 M&A transactions took place among financial institutions in the kingdom of Bahrain. This paper evaluates the impact of M&As on the financial performance of four such deals between banks in Bahrain. Data was collected from financial statements of the banks and the Bankscope database during 2004–2015. 15 accounting ratios were applied to CAMEL Rating Model approach. Financial modelling with Excel has been applied to test for the significance of changes in the financial performance of the banks three years before and three years after mergers. No significant difference in the financial performance of the local banks between pre and post M&As in the kingdom of Bahrain was observed. No significant difference in the financial performance of the acquirer bank or the target bank was observed except Bahraini Saudi Bank (target bank) which showed significant improvement in the financial performance after the merger with acquirer bank namely Al Salaam Bank. No significant change in the overall CAMEL ratios was observed for all banks involved in the M&As in Bahrain during 2004-15. The study provides an empirical analysis of the M&As before and after the mergers which can serve as a basis for further evaluation of future strategy of the banking sector in the kingdom of Bahrain
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