4,060 research outputs found

    Exogenous Shocks and Exchange Rate Management in Developing Countries

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    Even though globalization benefits less developed countries (LDCs), it also makes them more vulnerable to the exogenous shocks to the economies. Many LDCs rely on imported technologies and intermediate inputs to compete in the international export markets with better quality and cost efficient products. In this regard, exchange rate policies in respective countries have a direct bearing on the cost of production. This paper examines alternative exchange rate regimes to suggest an appropriate exchange rate policy in the context of developing countries. The paper utilizes a small open economy model involving direct supply-side effects of exchange rate and expectations of key economic variables and considers four possible exchange rate policies, e.g., fixed exchange rate, perfectly flexible exchange rate, leaning against the wind, and leaning with the wind. Contrary to the conventional wisdom, the paper finds that in the event of a shock, leaning against the wind is likely to be the most appropriate exchange rate policy. Moreover, in the event of rigid wages, a fixed exchange rate policy is advisable.globalization, exchange rate regimes, exchange rate policy

    Current-voltage characteristics in donor-acceptor systems: Implications of a spatially varying electric field

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    We have studied the transport properties of a molecular device composed of donor and acceptor moieties between two electrodes on either side. The device is considered to be one-dimensional with different on-site energies and the non-equilibrium properties are calculated using Landauer's formalism. The current-voltage characteristics is found to be asymmetric with a sharp Negative Differential Resistance at a critical bias on one side and very small current on the other side. The NDR arises primarily due to the bias driven electronic structure change from one kind of insulating phase to another through a highly delocalized conducting phase. Our model can be considered to be the simplest to explain the experimental current-voltage characteristics observed in many molecular devices.Comment: 5 pages, 4 figures (accepted for publication in Physical Review B

    Thermoelectric properties of Bi2Te3 atomic quintuple thin films

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    Motivated by recent experimental realizations of quintuple atomic layer films of Bi2Te3,the thermoelectric figure of merit, ZT, of the quintuple layer is calculated and found to increase by a factor of 10 (ZT = 7.2) compared to that of the bulk at room temperature. The large enhancement in ZT results from the change in the distribution of the valence band density of modes brought about by the quantum confinement in the thin film. The theoretical model uses ab initio electronic structure calculations (VASP) with full quantum-mechanical structure relaxation combined with a Landauer formalism for the linear-response transport coefficients.Comment: 4 figures, submitted to AP

    Higher Dimensional Inhomogeneous Perfect Fluid Collapse in \emph{f(R)} Gravity

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    This paper is about the n+2n+2-dimensional gravitational contraction of inhomogeneous fluid without heat flux in the framework of f(R)f(R) metric theory of gravity. Matching conditions for two regions of a star has been derived by using the Darmois junction conditions. For the analytic solution of equations of motion in modified f(R)f(R) theory of gravity, we have taken scalar curvature as constant. Hence final result of gravitational collapse in this frame work is the existence of black hole and cosmological horizons, both of these form earlier than singularity. It has been shown that constant curvature term f(R0)f(R_{0}) (R0R_0 is constant scalar curvature) slows down the collapsing process.Comment: 17 Pages, to appear in European Physical Journal

    Charging induced asymmetry in molecular conductors

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    We investigate the origin of asymmetry in various measured current-voltage (I-V) characteristics of molecules with no inherent spatial asymmetry, with particular focus on a recent break junction measurement. We argue that such asymmetry arises due to unequal coupling with the contacts and a consequent difference in charging effects, which can only be captured in a self-consistent model for molecular conduction. The direction of the asymmetry depends on the sign of the majority carriers in the molecule. For conduction through highest occupied molecular orbitals (i.e. HOMO or p-type conduction), the current is smaller for positive voltage on the stronger contact, while for conduction through lowest unoccupied molecular orbitals (i.e. LUMO or n-type conduction), the sense of the asymmetry is reversed. Within an extended Huckel description of the molecular chemistry and the contact microstructure (with two adjustable parameters, the position of the Fermi energy and the sulphur-gold bond length), an appropriate description of Poisson's equation, and a self-consistently coupled non-equilibrium Green's function (NEGF) description of transport, we achieve good agreement between theoretical and experimental I-V characteristics, both in shape as well as overall magnitude.Comment: length of the paper has been extended (4 pages to 6 pages), two new figures have been added (3 figures to 5 figures), has been accepted for PR

    Emerging of Yokenella regensburgei as Uropathogen: First Report

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    The study aimed to evaluate  the prevalence of Yokenella regensburgei and to determine the phenotypic resistance patterns of this bacterium.A total of  300 urine  samples were collected during a period  intervals from February till July of the year 2013 from patients complained from urinary tract infections visited An- Najaf  province  Hospitals. The samples in all had been cultured on MacConkey agar where the results revealed that there were 250 of isolates  lactose  fermentative  versus to  50 were lactose non fermentative .The lactose non fementative isolates then  subjected  to further identification and  the  phenotypic resistance  patterns   by Vitek-2 system had been conducted. The results  revealed  as first  report  identification of Yokenella regensburgei as agent of urinary tract infection with occurrence rate of 0.33% which might indicated the risk of related underlying diseases . the results of antibiotic  susceptibility showed that the bacterium was  sensitive to most screened  antibiotics beside nitrofurantoin, tetracycline and trimethoprim/sulfamethoxazole  shown activity against the  bacterium. Keywords: Yokenella regensburgei , Vitek 2, antibiotic susceptibilit

    Evaluation of Records of Oral and Maxillofacial Surgery Cases Reported at Abbasi Shaheed Hospital and Karachi Medical and Dental College, Pakistan

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    Background: Oral and Maxillofacial Surgery department is a diverse field in dentistry. Record maintenance has been established as one of the key factors in the success and integrity of health care institutes.Objective: The objective of the study was to evaluate the records of oral and maxillofacial surgery casesreported to oral and maxillofacial surgery department, Abbasi Shaheed Hospital and oral surgery OPD ofKarachi Medical and Dental College.Methods: Cross sectional study was conducted in at ASH and KMDC from July 2019 to September 2019.The data from January 2017 to July 2019 was retrospectively noted through electronic surgical recordof ASH and records of the Oral Surgery OPD of KMDC. Inclusion criteria was patients records of bothgenders of 5–70 years age, having complaint of any oral or dental pathology or pathologies, trauma andimpactions. Data was calculated manually by calculating frequencies and percentages for the trauma,impaction and pathology cases of patients.Results: In 2017, 239 cases were treated under general anesthesia from which trauma 11. 45% (n=11),followed by 48. 11% (n=115) cases of oral pathologies, total 11.7% (n=28) cases of complicated exodontias. In2018, among 211, 51.1% (n=108) cases were trauma followed by 39.3% (n=83) cases of oral pathologies,whereas, total 9.4% (n=20) complicated exodontias cases were observed. During 2019 (January to July),168 cases 36.2% (n=62) cases were diagnosed as trauma, in oral pathology, overall 36.2% (n=62) caseswere surgically excised. Total 23.2% (n=39) complicated exodontias. In 2017, 25122 cases were reported in Surgery OPD of Karachi Medical and Dental College. Total 36.2% (n=9097) teeth were extracted from which 1.93% (n=486) cases were surgical impaction. On the other hand, 1.65% (n=416) patients were treated through minor oral surgeries. In 2018, 29008 cases were reported in Surgery OPD. Total 42.7% (n=12377) teeth were extracted from which 0.92% (n=268) cases were surgical impaction. On the other hand, 0.71% (n=208) patients were treated through minor surgeries. In 2019, January till July 13028 cases were reported in Surgery OPD. Total42.6% (n=5559) teeth were extracted from which 0.66% (n=87) cases were surgical impaction. On the other hand, 0.68% (n=89) patients were treated through minor surgeries.Conclusion: It has been concluded that evaluation of the records of oral and maxillofacial surgery casesreported to oral and maxillofacial surgery department, Abbasi Shaheed Hospital and oral surgery OPD ofKarachi Medical and Dental College were high and appropriate measures should be taken in order tomanage these problems timely and effectively
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