Exchange Rate Models Are Not as Bad as You Think

Standard models of exchange rates, based on macroeconomic variables such as prices, interest rates, output, etc., are thought by many researchers to have failed empirically. We present evidence to the contrary. First, we emphasize the point that "beating a random walk" in forecasting is too strong a criterion for accepting an exchange rate model. Typically models should have low forecasting power of this type. We then propose a number of alternative ways to evaluate models. We examine in-sample fit, but emphasize the importance of the monetary policy rule, and its effects on expectations, in determining exchange rates. Next we present evidence that exchange rates incorporate news about future macroeconomic fundamentals, as the models imply. We demonstrate that the models might well be able to account for observed exchange-rate volatility. We discuss studies that examine the response of exchange rates to announcements of economic data. Then we present estimates of exchange-rate models in which expected present values of fundamentals are calculated from survey forecasts. Finally, we show that out-of-sample forecasting power of models can be increased by focusing on panel estimation and long-horizon forecasts.

A study of determinants and prevalence of Rheumatic Heart Disease in Cape Town

Includes abstract.Includes bibliographical references.Rheumatic Heart Disease (RHD) is a post-infectious immune disease ascribed to an interaction between a rheumatogenic strain of group A streptococcus, a susceptible host who lives in poor social conditions with limited access to medical facilities. The disease process begins with repeated group A streptococcal (GAS) infections, which, subsequently result in acute rheumatic fever (ARF). In the absence of intervention, repeated bouts of ARF in turn, may result in progression to RHD, particularly in those ARF patients with cardiac involvement. The prevalence of ARF and RHD in developed countries has shown considerable decline during the last century, largely attributed to improved living conditions and access to healthcare. Epidemiological data from developing countries, while scant, indicate a continued high prevalence of GAS-positive pharyngitis and RHD. Furthermore, while much is known about the social factors and the microbial agent that predispose individuals to ARF, little progress has been made in elucidating genetic susceptibility factors that are reproducible in different populations. This thesis aimed to establish determinants of RHD as well as to document the prevalence of RHD in South African school children. The specific objectives of each study component were as follows: To derive quantitative estimates of the size of the genetic contribution to the risk of developing ARF/RHD. To determine the prevalence of GAS carriage and emm strains of GAS isolates among asymptomatic children enrolled in primary and secondary school. To describe the epidemiology of GAS among 3- to 15-year old children with pharyngitis attending primary health care facilities. To develop a clinical prediction rule for diagnosis of GAS throat infection that is valid for children aged 5-15 years in the primary care setting within the South African context. To determine the prevalence of echocardiographically-proven rheumatic heart disease in school children

Steroids for tuberculous pleurisy : a systematic review and meta-analysis of clinical trials

Includes bibliographical references.Corticosteroids used in addition to anti-tuberculous therapy have been reported to benefit people with tuberculous pleurisy. However, research findings are not consistent, raising doubt as to whether such treatment is worthwhile. Concem also exists regarding the potential adverse effects of steroids, especially in HIV positive patients. An earlier Cochrane review summarized the existing evidence on the effects of steroids in people with tuberculous pleurisy. This review updates the evidence and, for the first time sheds light on the effects of steroids in patients with tuberculous pleurisy co-infected with HIV

Which fundamentals drive exchange rates? A cross-sectional perspective

Standard present-value models suggest that exchange rates are driven by expected future fundamentals, implying that exchange rates contain information about future fundamentals. We test this key empirical prediction of present-value models in a sample of 35 currency pairs ranging from 1900 to 2009. Employing a variety of tests, we find that exchange rates have strong and significant predictive power for nominal fundamentals (inflation, money balances, nominal GDP), whereas predictability of real fundamentals and risk premia is much weaker and largely confined to the post-Bretton Woods era. Overall, we uncover ample evidence that future macro fundamentals drive current exchange rates

Trispectrum versus Bispectrum in Single-Field Inflation

In the standard slow-roll inflationary cosmology, quantum fluctuations in a single field, the inflaton, generate approximately Gaussian primordial density perturbations. At present, the bispectrum and trispectrum of the density perturbations have not been observed and the probability distribution for these perturbations is consistent with Gaussianity. However, Planck satellite data will bring a new level of precision to bear on this issue, and it is possible that evidence for non-Gaussian effects in the primordial distribution will be discovered. One possibility is that a trispectrum will be observed without evidence for a non-zero bispectrum. It is not difficult for this to occur in inflationary models where quantum fluctuations in a field other than the inflaton contribute to the density perturbations. A natural question to ask is whether such an observation would rule out the standard scenarios. We explore this issue and find that it is possible to construct single-field models in which inflaton-generated primordial density perturbations have an observable trispectrum, but a bispectrum that is too small to be observed by the Planck satellite. However, an awkward fine tuning seems to be unavoidable.Comment: 15 pages, 3 figures; journal versio

The Importance of Awareness and Education in Prevention and Control of RHD

AbstractAcute rheumatic fever and rheumatic heart disease are diseases of poverty, low socioeconomic status, and inadequate access to health care. These preventable diseases remain largely ignored by the developed world while they continue to cause significant mortality and morbidity in the developing world. In the face of no existing cure, we need to focus on prevention and control methods. To this end, creating awareness of the disease and its effects on millions of people in the world is critically important. In this review, we will outline the importance of these efforts, discuss the barriers to awareness and education, and highlight some important models in this arena. We strongly support awareness-raising and health promotion strategies as an integral part of a rheumatic heart disease prevention and control program

Rationale and design of the African group A streptococcal infection registry: the AFROStrep study

Introduction: Group A β-haemolytic Streptococcus (GAS), a Gram-positive bacterium, also known as Streptococcus pyogenes, causes pyoderma, pharyngitis and invasive disease. Repeated GAS infections may lead to autoimmune diseases such as acute post-streptococcal glomerulonephritis, acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Invasive GAS (iGAS) disease is an important cause of mortality and morbidity worldwide. The burden of GAS infections is, however, unknown in Africa because of lack of surveillance systems. Methods and analysis: The African group A streptococcal infection registry (the AFROStrep study) is a collaborative multicentre study of clinical, microbiological, epidemiological and molecular characteristics for GAS infection in Africa. The AFROStrep registry comprises two components: (1) active surveillance of GAS pharyngitis cases from sentinel primary care centres (non-iGAS) and (2) passive surveillance of iGAS disease from microbiology laboratories. Isolates will also be subjected to DNA isolation to allow for characterisation by molecular methods and cryopreservation for long-term storage. The AFROStrep study seeks to collect comprehensive data on GAS isolates in Africa. The biorepository will serve as a platform for vaccine development in Africa. Ethics and dissemination: Ethics approval for the AFROStrep registry has been obtained from the Human Research Ethics Committee at the University of Cape Town (HREC/REF: R006/2015). Each recruiting site will seek ethics approval from their local ethics’ committee. All participants will be required to provide consent for inclusion into the registry as well as for the storage of isolates and molecular investigations to be conducted thereon. Strict confidentiality will be applied throughout. Findings and updates will be disseminated to collaborators, researchers, health planners and colleagues through peer-reviewed journal articles, conference publications and proceedings

Clinical and epidemiological aspects of streptococcus pyogenes pharyngitis and carriage in Africa

Infection with Group A β-haemolytic Streptococcus, also known as Streptococcus pyogenes, results in various mucosal and skin diseases including pharyngitis. An exaggerated immune response to a single or repeated group A streptococcal (GAS) infection subsequently results in acute rheumatic fever (ARF) and, in the absence of intervention, repeated bouts of ARF may in turn result in progression to RHD, particularly in those ARF patients with cardiac involvement. Addressing GAS pharyngitis through appropriate primary prevention measures and treating all symptomatic GAS sore throats with a course of oral or parenteral penicillin presents an opportunity for the primary intervention of RHD. Failure to eradicate streptococci from the pharynx occurs in about one third of non-treated cases, giving rise to carrier status in those individuals harbouring intracellular GAS and thus representing a potential source of the acquisition of infections for other children and adults. Improved living conditions and access to healthcare during the last century are credited for the considerable decline in the prevalence of ARF and RHD in developed countries. However, a few studies have been reported from within Africa, and in these GAS carriage ranged around 9.0%. In South African studies GAS carriage isolation rates, which range from 1.62% to16.8%, were reported. As regards the prevalence of GAS pharyngitis, it is generally higher in developing countries and impoverished communities withinindustrialised nations. The most-up-to-date data from South Africa was collected more than 30 years ago with rates then ranging from 23.2% to 45.5%. There are no incidence data on GAS pharyngitis in Africa. This review found that there is a need to document the epidemiology of GAS carriage and GAS pharyngitis in school children of all ages within Africa. Molecular characterisation of strains harboured in the pharynx of carriers and of those isolated during bouts of pharyngitis, will help to identify risk factors associated with carriage in school-aged children and infl uence the planning and evaluation of management programmes in the screening of pharyngeal carriers and treatment of GAS pharyngitis

Time to end Rheumatic Heart Disease: Lessons and opportunities from observational registries

The fight against Rheumatic Heart Disease (RHD) is at a critical juncture. Despite the adoption of a global resolution by the World Health Assembly against RHD in May 2018, practitioners working in countries where RHD is endemic continue to be faced with an overwhelming clinical burden, lack of surgical and interventional resources, and insufficient opportunities and funding for research. Recent years have seen the publication of several observational registries, most of which were investigator-initiated, not supported by larger research funders, and coordinated by small teams using paper-based infrastructure. This commentary reflects on the lessons and opportunities that these registries have afforded the field and suggests some areas for further investigation