Explaining Africa's Growth Tragedy: A Theoretical Model of Dictatorship and Kleptocracy

In this paper, we construct a dynamic model of a kleptocratic dictatorship to explain sub-Saharan Africa’s dismal economic performance between the early 1970s and the mid-1990s. The dictator’s objective is to maximize a discounted stream of revenue generated through theft of the economy’s output by choosing the optimal expropriation rate and the size of the security force employed to enforce his rule. The model is used to evaluate alternative intervention options open to developed countries such as unconditional, conditional and selective foreign aid, financial and military assistance to rebel groups, as well as medical relief to combat the HIV/AIDs pandemic.Economic performance, dictatorship, foreign aid, Africa

Bit Error Rates for Ultrafast APD Based Optical Receivers: Exact and Large Deviation Based Asymptotic Approaches

Exact analysis as well as asymptotic analysis, based on large-deviation theory (LDT), are developed to compute the bit-error rate (BER) for ultrafast avalanche-photodiode (APD) based optical receivers assuming on-off keying and direct detection. The effects of intersymbol interference (ISI), resulting from the APD\u27s stochastic avalanche buildup time, as well as the APD\u27s dead space are both included in the analysis. ISI becomes a limiting factor as the transmission rate approaches the detector\u27s bandwidth, in which case the bit duration becomes comparable to APD\u27s avalanche buildup time. Further, the effect of dead space becomes significant in high-speed APDs that employ thin avalanche multiplication regions. While the exact BER analysis at the generality considered here has not been reported heretofore, the asymptotic analysis is a major generalization of that developed by Letaief and Sadowsky [IEEE Trans. Inform. Theory, vol. 38, 1992], in which the LDT was used to estimate the BER assuming APDs with an instantaneous response (negligible avalanche buildup time) and no dead space. These results are compared with those obtained using the common Gaussian approximation approach showing the inadequacy of the Guassian approximation when ISI noise has strong presence

OBSERVATIONS ON LERNAEID PARASITES OF CATLA CATLA FROM A FISH HATCHERY IN MUZAFFARGARH, PAKISTAN

During the present study, 120 fishes (Catla catla) maintained at a fish hatchery in Muzafargarh, Pakistan were examined for lernaeid parasites over a 12 months period from February 2000 to January 2001. Out of 120 C. catla fishes, 96 were infested, showing an overall prevalence of 80%. Six species of Lernaea recovered were: L. cyprinacea, L. polymorpha, L. ctenopharyngodonis, L. arcuata, L. lophiara and L. oryzophila. L. cyprinacea showed the highest parasitic burden (3.61 parasites per fish), while L. lophiara had the lowest parasitic burden (1.00 parasite per fish). The infestation was lowest in fishes with body length of 23.00-25.75 cm and maximum in 25.76-31.25 cm long fishes. Similarly, the parasitic infestation increased with body weight range of 160-258 gm to 456-553 gm, while almost no parasites were seen in heavier fishes (>553 gm)

Determination of pesticide residues in blood samples of villagers involved in pesticide application at District Vehari (Punjab), Pakistan

Blood samples were collected from field workers involved in pesticide spraying activities at three different farms in Tahsil Mailsi, District Vehari (Punjab), Pakistan. Twenty seven villagers (including three controls), ranging from 16 to 50 years of age and one to nine years of pesticide application experience were tested. The blood samples were analyzed for 383 different pesticides using Gas Chromatograph Mass Spectrometer (GC-MS) multi residue analytical technique. Only chlorpyrifos (0.009 mg/l) and pyributicarb (0.001 mg/l) were detected in the blood samples.Key words: Multi-pesticide residues, blood sample, GC-MS

All-metal wideband metasurface for near-field transformation of medium-to-high gain electromagnetic sources

Electromagnetic (EM) metasurfaces are essential in a wide range of EM engineering applications, from incorporated into antenna designs to separate devices like radome. Near-field manipulators are a class of metasurfaces engineered to tailor an EM source's radiation patterns by manipulating its near-field components. They can be made of all-dielectric, hybrid, or all-metal materials; however, simultaneously delivering a set of desired specifications by an all-metal structure is more challenging due to limitations of a substrate-less configuration. The existing near-field phase manipulators have at least one of the following limitations; expensive dielectric-based prototyping, subject to ray tracing approximation and conditions, narrowband performance, costly manufacturing, and polarization dependence. In contrast, we propose an all-metal wideband phase correcting structure (AWPCS) with none of these limitations and is designed based on the relative phase error extracted by post-processing the actual near-field distributions of any EM sources. Hence, it is applicable to any antennas, including those that cannot be accurately analyzed with ray-tracing, particularly for near-field analysis. To experimentally verify the wideband performance of the AWPCS, a shortened horn antenna with a large apex angle and a non-uniform near-field phase distribution is used as an EM source for the AWPCS. The measured results verify a significant improvement in the antenna's aperture phase distribution in a large frequency band of 25%

Factors Associated With Unplanned Hospitalizations Among Patients With Nonmetastatic Colorectal Cancers Intended for Treatment in the Ambulatory Setting

Chemotherapy administration and supportive management for solid tumors is intended to take place in the ambulatory setting, but little is known about why some patients experience treatment-related, adverse events so severe as to require acute inpatient care

Analytical study of radiative casson nanoliquid flow with heat absorption

The divergence of thermally radiative MHD flow of a Casson nanofluid over a stretching paper alongside heat absorption. The governing non linear equations are remodeled into a nonlinear ODE’s. The HAM is adopted to find the series solution. The changes of pertinent parameters are analyzed with diagrams and tables. The fluid velocity is controlled by suction and it develops with injection. The local Nusselt number rapidly suppresses with increasing the magnetic field parameter in heat generation case

Energy transfer between a biological labelling dye and gold nanorods

We have demonstrated energy transfer between a biological labelling dye (Alexa Fluor 405) and gold nanorods experimentally and theoretically. The fluorescence lifetime imaging microscopy and density matrix method are used to study a hybrid system of dye and nanorods under one- and two-photon excitations. Energy transfer between dye and nanorods via the dipole–dipole interaction is found to cause a decrease in the fluorescence lifetime change. Enhanced energy transfer from dye to nanorods is measured in the presence of an increased density of nanorods. This study has potential applications in fluorescence lifetime-based intra-cellular sensing of bio-analytes as well as nuclear targeting cancer therap

Obstructive sleep apnea in heart failure: Review of prevalence, treatment with continuous positive airway pressure, and prognosis

Obstructive sleep apnea is a sleep-related breathing disorder that has a major impact on cardiovascular function. It has been associated with hypertension, coronary artery disease, cardiac arrhythmias, sudden cardiac death, and heart failure. This review focuses on the relationship between obstructive sleep apnea and heart failure with either reduced or preserved ejection fraction. We discuss the pathophysiology of obstructive sleep apnea, as well as its prevalence, treatment outcomes with continuous positive airway pressure, and prognosis in these 2 distinct types of heart failure. We also identify areas in which further work is needed to improve our understanding of this association in heart failure patients