1,564 research outputs found
Dutch disease scare in Kazakhstan: Is it real?
In this paper we explore the evidence that would establish that Dutch disease is at work in, or poses a threat to, the Kazakh economy. Assessing the mechanism by which fluctuations in the price of oil can damage non-oil manufacturing—and thus long-term growth prospects in an economy that relies heavily on oil production—we find that non-oil manufacturing has so far been spared the perverse effects of oil price increases from 1996 to 2005. The real exchange rate in the open sector has ap-preciated over the last couple of years, largely due to the appreciation of the nominal exchange rate. We analyze to what extent this appreciation is linked to movements in oil prices and oil revenues. Econometric evidence from the monetary model of the exchange rate and a variety of real exchange rate models show that the rise in the price of oil and in oil revenues might be linked to an appreciation of the U.S. dollar exchange rate of the oil and non-oil sectors. But appreciation is mainly limited to the real effective exchange rate for oil sector and is statistically insignificant for non-oil manufacturing.price level; inflation; Balassa-Samuelson; tradables; house prices; regulated prices; Europe; transition
Local density of states and Friedel oscillations around a non-magnetic impurity in unconventional density wave
We present a mean-field theoretical study on the effect of a single
non-magnetic impurity in quasi-one dimensional unconventional density wave. The
local scattering potential is treated within the self-consistent -matrix
approximation. The local density of states around the impurity shows the
presence of resonant states in the vicinity of the Fermi level, much the same
way as in -density waves or unconventional superconductors. The assumption
for different forward and backscattering, characteristic to quasi-one
dimensional systems in general, leads to a resonance state that is double
peaked in the pseudogap. The Friedel oscillations around the impurity are also
explored in great detail, both within and beyond the density wave coherence
length . Beyond we find power law behavior as opposed to the
exponential decay of conventional density wave. The entropy and specific heat
contribution of the impurity are also calculated for arbitrary scattering
strengths.Comment: 13 pages, 4 figure
Rabi Oscillations in Landau-Quantized Graphene
We investigate the relation between the canonical model of quantum optics,
the Jaynes-Cummings Hamiltonian and Dirac fermions in quantizing magnetic
field. We demonstrate that Rabi oscillations are observable in the optical
response of graphene, providing us with a transparent picture about the
structure of optical transitions. While the longitudinal conductivity reveals
chaotic Rabi oscillations, the Hall component measures coherent ones. This
opens up the possibility of investigating a microscopic model of a few quantum
objects in a macroscopic experiment with tunable parameters.Comment: 5 pages, 4 figure
Recurrent Neural Networks with Top-k Gains for Session-based Recommendations
RNNs have been shown to be excellent models for sequential data and in
particular for data that is generated by users in an session-based manner. The
use of RNNs provides impressive performance benefits over classical methods in
session-based recommendations. In this work we introduce novel ranking loss
functions tailored to RNNs in the recommendation setting. The improved
performance of these losses over alternatives, along with further tricks and
refinements described in this work, allow for an overall improvement of up to
35% in terms of MRR and Recall@20 over previous session-based RNN solutions and
up to 53% over classical collaborative filtering approaches. Unlike data
augmentation-based improvements, our method does not increase training times
significantly. We further demonstrate the performance gain of the RNN over
baselines in an online A/B test.Comment: CIKM'18, authors' versio
Quantum Monte Carlo Algorithm Based on Two-Body Density Functional Theory for Fermionic Many-Body Systems: Application to 3He
We construct a quantum Monte Carlo algorithm for interacting fermions using
the two-body density as the fundamental quantity. The central idea is mapping
the interacting fermionic system onto an auxiliary system of interacting
bosons. The correction term is approximated using correlated wave functions for
the interacting system, resulting in an effective potential that represents the
nodal surface. We calculate the properties of 3He and find good agreement with
experiment and with other theoretical work. In particular, our results for the
total energy agree well with other calculations where the same approximations
were implemented but the standard quantum Monte Carlo algorithm was usedComment: 4 pages, 3 figures, 1 tabl
Unconventional density wave in CeCoIn_5?
Very recently large Nernst effect and Seebeck effect were observed above the
superconducting transition temperature 2.3K in a heavy fermion superconductor
CeCoIn_5. We shall interpret this large Nernst effect in terms of
unconventional density wave (UDW), which appears around T=18K. Also the
temperature dependence of the Seebeck coefficient below T=18K is described in
terms of UDW. Another hallmark for UDW is the angular dependent
magnetoresistance, which should be readily accessible experimentally.Comment: 4 pages, 7 figure
Sensitivity of the Cherenkov Telescope Array to the detection of a dark matter signal in comparison to direct detection and collider experiments
Imaging atmospheric Cherenkov telescopes (IACTs) that are sensitive to
potential -ray signals from dark matter (DM) annihilation above
GeV will soon be superseded by the Cherenkov Telescope Array (CTA).
CTA will have a point source sensitivity an order of magnitude better than
currently operating IACTs and will cover a broad energy range between 20 GeV
and 300 TeV. Using effective field theory and simplified models to calculate
-ray spectra resulting from DM annihilation, we compare the prospects
to constrain such models with CTA observations of the Galactic center with
current and near-future measurements at the Large Hadron Collider (LHC) and
direct detection experiments. For DM annihilations via vector or pseudoscalar
couplings, CTA observations will be able to probe DM models out of reach of the
LHC, and, if DM is coupled to standard fermions by a pseudoscalar particle,
beyond the limits of current direct detection experiments.Comment: Accepted for publication in PRD. 20 pages, 11 figure
Pseudogap enhancement due to magnetic impurities in d-density waves
We study the effect of quantum magnetic impurities on d-wave spin density
waves (d-SDW). The impurity spins are aligned coherently according to the spin
space anisotropy of the condensate. Both the order parameter and transition
temperature increases due to the coherent interplay between magnetic scatterers
and d-SDW. This can explain the recent experimental data on the pseudogap
enhancement of Ni substituted NdBa_2{Cu_{1-y}Ni_y}O_6.8 from Pimenov et al.
(Phys. Rev. Lett. 94, 227003 (2005)).Comment: 4 pages, 3 figure
Non-perturbative effects and the resummed Higgs transverse momentum distribution at the LHC
We investigate the form of the non-perturbative parameterization in both the
impact parameter (b) space and transverse momentum (p_T) space resummation
formalisms for the transverse momentum distribution of single massive bosons
produced at hadron colliders. We propose to analyse data on Upsilon
hadroproduction as a means of studying the non-perturbative contribution in
processes with two gluons in the initial state. We also discuss the theoretical
errors on the resummed Higgs transverse momentum distribution at the LHC
arising from the non-perturbative contribution.Comment: 22 pages, 10 figure
- …