7,144 research outputs found
Currency Crises and Monetary Policy in an Economy with Credit Constraints: The No Interest Parity Case
This paper revisits the currency crises model of Aghion, Bacchetta and Banerjee (2000, 2001, 2004), who show that if there exist nominal price rigidities and private sector credit constraints, and the credit multiplier depends on real interest rates, then the optimal monetary policy response to the threat of a currency crisis is restrictive. We demonstrate that this result is primarily due to the uncovered interest parity assumption. Assuming that the exchange rate is a martingale restores the case for expansionary reaction - even with foreign-currency debt in firms' balance sheets. The effect of lower interest rates on output can help restore the value of the currency due to increased money demand.currency crises; foreignâcurrency debt; balance sheets; interest parity; monetary policy
Wireless Health Monitoring using Passive WiFi Sensing
This paper presents a two-dimensional phase extraction system using passive
WiFi sensing to monitor three basic elderly care activities including breathing
rate, essential tremor and falls. Specifically, a WiFi signal is acquired
through two channels where the first channel is the reference one, whereas the
other signal is acquired by a passive receiver after reflection from the human
target. Using signal processing of cross-ambiguity function, various features
in the signal are extracted. The entire implementations are performed using
software defined radios having directional antennas. We report the accuracy of
our system in different conditions and environments and show that breathing
rate can be measured with an accuracy of 87% when there are no obstacles. We
also show a 98% accuracy in detecting falls and 93% accuracy in classifying
tremor. The results indicate that passive WiFi systems show great promise in
replacing typical invasive health devices as standard tools for health care.Comment: 6 pages, 8 figures, conference pape
Statistical PT-symmetric lasing in an optical fiber network
PT-symmetry in optics is a condition whereby the real and imaginary parts of
the refractive index across a photonic structure are deliberately balanced.
This balance can lead to a host of novel optical phenomena, such as
unidirectional invisibility, loss-induced lasing, single-mode lasing from
multimode resonators, and non-reciprocal effects in conjunction with
nonlinearities. Because PT-symmetry has been thought of as fragile,
experimental realizations to date have been usually restricted to on-chip
micro-devices. Here, we demonstrate that certain features of PT-symmetry are
sufficiently robust to survive the statistical fluctuations associated with a
macroscopic optical cavity. We construct optical-fiber-based coupled-cavities
in excess of a kilometer in length (the free spectral range is less than 0.8
fm) with balanced gain and loss in two sub-cavities and examine the lasing
dynamics. In such a macroscopic system, fluctuations can lead to a
cavity-detuning exceeding the free spectral range. Nevertheless, by varying the
gain-loss contrast, we observe that both the lasing threshold and the growth of
the laser power follow the predicted behavior of a stable PT-symmetric
structure. Furthermore, a statistical symmetry-breaking point is observed upon
varying the cavity loss. These findings indicate that PT-symmetry is a more
robust optical phenomenon than previously expected, and points to potential
applications in optical fiber networks and fiber lasers.Comment: Submitted to Nature Communications, Pages 1-19: Main manuscript;
Pages 20-38: Supplementary material
Proposed business plan for pilot farmer organizations: Extended project on Farmer Managed Irrigated Agriculture in LBOD Project Area of Sindh Province
Farmers' associations / Farmer managed irrigation systems / Irrigation programs / Irrigation management / Drainage / Economic aspects / Income / Operating costs / Maintenance costs / Conflict
Nonlinear reversal of PT symmetric phase transition in a system of coupled semiconductor micro-ring resonators
A system of two coupled semiconductor-based resonators is studied when lasing
around an exceptional point. We show that the presence of nonlinear saturation
effects can have important ramifications on the transition behavior of this
system. In sharp contrast with linear PT-symmetric configurations, nonlinear
processes are capable of reversing the order in which the symmetry breaking
occurs. Yet, even in the nonlinear regime, the resulting non-Hermitian states
still retain the structural form of the corresponding linear eigenvectors
expected above and below the phase transition point. The conclusions of our
analysis are in agreement with experimental data.Comment: 9 pages, 8 figure
Integrable nonlinear parity-time symmetric optical oscillator
The nonlinear dynamics of a balanced parity-time symmetric optical microring
arrangement are analytically investigated. By considering gain and loss
saturation effects, the pertinent conservation laws are explicitly obtained in
the Stokes domain-thus establishing integrability. Our analysis indicates the
existence of two regimes of oscillatory dynamics and frequency locking, both of
which are analogous to those expected in linear parity-time symmetric systems.
Unlike other saturable parity time symmetric systems considered before, the
model studied in this work first operates in the symmetric regime and then
enters the broken parity-time phase.Comment: 6 pages, 5 figures, accepted for publicatio
Congenital neck masses: embryological and anatomical perspectives
Neck masses are a common problem in paediatric age group. They tend to occur frequently and pose a diagnostic dilemma to the ENT surgeons. Although the midline and lateral neck masses differ considerably in their texture and presentation but the embryological perspective of these masses is not mostly understood along with the fundamental anatomical knowledge. The article tries to correlate the embryological, anatomical and clinical perspectives for the same
A histological study of prostate
The work of anatomists and pathologists in the role of study of prostate has been significant. Starting from earlier times till modern time, the study of prostate has been a dynamic one and the basic anatomical knowledge of the prostate has undergone much change apart from the new techniques, micro invasive procedures and the chemotherapeutic approach for various disorders of the gland. The present study was based on the microscopic examination of Prostatic tissue of individuals with individual tissues of different age groups. The present study involved 40 cases which were further subdivided into various age groups and characteristic histological changes were noted. The study presents an assessment of age changes in prostate in elderly in Kashmiri population with pathological significance. Besides the histological study is of great importance in staging of diseases of prostate and especially in modern era where the incidence and prevalence of prostatic diseases is on rise
The Semi-Chiral Quotient, Hyperkahler Manifolds and T-duality
We study the construction of generalized Kahler manifolds, described purely
in terms of N=(2,2) semichiral superfields, by a quotient using the semichiral
vector multiplet. Despite the presence of a b-field in these models, we show
that the quotient of a hyperkahler manifold is hyperkahler, as in the usual
hyperkahler quotient. Thus, quotient manifolds with torsion cannot be
constructed by this method. Nonetheless, this method does give a new
description of hyperkahler manifolds in terms of two-dimensional N=(2,2) gauged
non-linear sigma models involving semichiral superfields and the semichiral
vector multiplet. We give two examples: Eguchi-Hanson and Taub-NUT. By
T-duality, this gives new gauged linear sigma models describing the T-dual of
Eguchi-Hanson and NS5-branes. We also clarify some aspects of T-duality
relating these models to N=(4,4) models for chiral/twisted-chiral fields and
comment briefly on more general quotients that can give rise to torsion and
give an example.Comment: 31 page
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