Mechanism for deep crustal seismicity: Insight from modeling of deformation process at the Main Ethiopian Rift

We combine numerical modeling of lithospheric extension with analysis of seismic moment release and earthquake b-value in order to elucidate the mechanism for deep crustal seismicity and seismic swarms in the Main Ethiopian Rift (MER). We run 2-D numerical simulations of lithospheric deformation calibrated by appropriate rheology and extensional history of the MER to simulate migration of deformation from mid-Miocene border faults to ∼30 km wide zone of Pliocene to recent rift floor faults. While currently the highest strain rate is localized in a narrow zone within the rift axis, brittle strain has been accumulated in a wide region of the rift. The magnitude of deviatoric stress shows strong variation with depth. The uppermost crust deforms with maximum stress of 80 MPa, at 8–14 km depth stress sharply decreases to 10 MPa and then increases to a maximum of 160 MPa at ∼18 km depth. These two peaks at which the crust deforms with maximum stress of 80 MPa or above correspond to peaks in the seismic moment release. Correspondingly, the drop in stress at 8–14 km correlates to a low in seismic moment release. At this depth range, the crust is weaker and deformation is mainly accommodated in a ductile manner. We therefore see a good correlation between depths at which the crust is strong and elevated seismic deformation, while regions where the crust is weaker deform more aseismically. Overall, the bimodal depth distribution of seismic moment release is best explained by the rheology of the deforming crust

Correlation of X-ray diffraction signatures of breast tissue and their histopathological classification

This pilot study examines the correlation of X-ray diffraction (XRD) measurements with the histopathological analysis of breast tissue. Eight breast cancer samples were investigated. Each sample contained a mixture of normal and cancerous tissues. In total, 522 separate XRD measurements were made at different locations across the samples (8 in total). The resulting XRD spectra were subjected to principal component analysis (PCA) in order to determine if there were any distinguishing features that could be used to identify different tissue components. 99.0% of the variation between the spectra were described by the first two principal components (PC). Comparing the location of points in PC space with the classification determined by histopathology indicated correlation between the shape/magnitude of the XRD spectra and the tissue type. These results are encouraging and suggest that XRD could be used for the intraoperative or postoperative classification of bulk tissue samples

Structural Analysis of the Western Afar Margin, East Africa: Evidence for Multiphase Rotational Rifting

The Afar region in East Africa represents a key location to study continental breakup. We present an integrated structural analysis of the Western Afar Margin (WAM) aiming to better understand rifted margin development and the role of plate rotation during rifting. New structural information from remote sensing, fieldwork, and earthquake data sets reveals that the N-S striking WAM is still actively deforming and is characterized by NNW-SSE normal faulting as well as a series of marginal grabens. Seismicity distribution analysis and the first-ever borehole-calibrated sections of this developing passive margin show recent slip concentrated along antithetic faults. Tectonic stress parameters derived from earthquake focal mechanisms reveal different extension directions along the WAM (82°N), in Afar (66°N) and in the Main Ethiopian Rift (108°N). Fault slip analysis along the WAM yields the same extension direction. Combined with GPS data, this shows that current tectonics in Afar is dominated by the local rotation of the Danakil Block, considered to have occurred since 11 Ma. Earlier stages of Afar development (since 31–25 Ma) were most likely related to the large-scale rotation of the Arabian plate. Various authors have proposed scenarios for the evolution of the WAM. Any complete model should consider, among other factors, the multiphase tectonic history and antithetic fault activity of the margin. The findings of this study are not only relevant for a better understanding of the WAM but also provide insights into the role of multiphase rotational extension during rifting and passive margin formation in general.</p

Towards Machine Wald

The past century has seen a steady increase in the need of estimating and predicting complex systems and making (possibly critical) decisions with limited information. Although computers have made possible the numerical evaluation of sophisticated statistical models, these models are still designed \emph{by humans} because there is currently no known recipe or algorithm for dividing the design of a statistical model into a sequence of arithmetic operations. Indeed enabling computers to \emph{think} as \emph{humans} have the ability to do when faced with uncertainty is challenging in several major ways: (1) Finding optimal statistical models remains to be formulated as a well posed problem when information on the system of interest is incomplete and comes in the form of a complex combination of sample data, partial knowledge of constitutive relations and a limited description of the distribution of input random variables. (2) The space of admissible scenarios along with the space of relevant information, assumptions, and/or beliefs, tend to be infinite dimensional, whereas calculus on a computer is necessarily discrete and finite. With this purpose, this paper explores the foundations of a rigorous framework for the scientific computation of optimal statistical estimators/models and reviews their connections with Decision Theory, Machine Learning, Bayesian Inference, Stochastic Optimization, Robust Optimization, Optimal Uncertainty Quantification and Information Based Complexity.Comment: 37 page

Knowledge of cervical tuberculosis lymphadenitis and its treatment in pastoral communities of the Afar region, Ethiopia

<p>Abstract</p> <p>Background</p> <p>Infection with <it>Mycobacterium bovis </it>(Mb) predominantly causes cervical TB lymphadenitis (TBL). Raw milk is considered the main source of Mb infection and raw milk is a major food source for Afar pastoralists. The aim of this study was to assess Afar pastoralists' knowledge concerning cervical TBL and its treatment.</p> <p>Methods</p> <p>A community-based cross-sectional survey involving 818 interviewees was conducted in two districts of the Afar Region, Ethiopia. In addition, two focus group discussions (FGDs) were conducted in each of the study areas, one with men and the other with women.</p> <p>Results</p> <p>Of the 818 interviewees [357 (43.6%) females and 461 (56.4%) males], 742 (90.7%) reported that they had knowledge of cervical TBL, mentioning that swelling(s) on the neck resulting in a lesion and scar are common symptoms. However, only 11 (1.5%) individuals mentioned that bacteria or germs are the causative agents of TBL. Three interviewees and a male discussant mentioned drinking raw milk as the cause of TBL. A considerable proportion (34.2%) of the interviewees and almost all the discussants suggested herbal medicine as an effective treatment. Male study participants were 1.82 times more likely to have overall knowledge of TBL than female study participants (adjusted OR, 1.82; 95% CI, 1.32 to 2.51, p < 0.001).</p> <p>Conclusion</p> <p>The pastoral community members in the study areas had little biomedical knowledge of the cause, the source of infection and the transmission route of cervical TBL. Furthermore, most community members believed that herbal medicines are the most effective treatment for TBL. Therefore, TB control programs in the Afar Region require the incorporation of public health education introducing current biomedical knowledge of the disease. In addition, further studies are important to elucidate which medicinal plants are used by Afar pastoralists to treat TBL.</p

Using mid-level cadres as substitutes for internationally mobile health professionals in Africa. A desk review

BACKGROUND: Substitute health workers are cadres who take on some of the functions and roles normally reserved for internationally recognized health professionals such as doctors, pharmacists and nurses but who usually receive shorter pre-service training and possess lower qualifications. METHODS: A desk review is conducted on the education, regulation, scopes of practice, specialization, nomenclature, retention and cost-effectiveness of substitute health workers in terms of their utilization in countries such as Tanzania, Malawi, Mozambique, Zambia, Ghana etc., using curricula, evaluations and key-informant questionnaires. RESULTS: The cost-effectiveness of using substitutes and their relative retention within countries and in rural communities underlies their advantages to African health systems. Some studies comparing clinical officers and doctors show minimal differences in outcomes to patients. Specialized substitutes provide services in disciplines such as surgery, ophthalmology, orthopedics, radiology, dermatology, anesthesiology and dentistry, demonstrating a general bias of use for clinical services. CONCLUSIONS: The findings raise interest in expanding the use of substitute cadres, as the demands of expanding access to services such as antiretroviral treatment requires substantial human resources capacity. Understanding the roles and conditions under which such cadres best function, and managing the skepticism and professional turf protection that restricts their potential, will assist in effective utilization of substitutes

Phenotypic Variation and Bistable Switching in Bacteria

Microbial research generally focuses on clonal populations. However, bacterial cells with identical genotypes frequently display different phenotypes under identical conditions. This microbial cell individuality is receiving increasing attention in the literature because of its impact on cellular differentiation, survival under selective conditions, and the interaction of pathogens with their hosts. It is becoming clear that stochasticity in gene expression in conjunction with the architecture of the gene network that underlies the cellular processes can generate phenotypic variation. An important regulatory mechanism is the so-called positive feedback, in which a system reinforces its own response, for instance by stimulating the production of an activator. Bistability is an interesting and relevant phenomenon, in which two distinct subpopulations of cells showing discrete levels of gene expression coexist in a single culture. In this chapter, we address techniques and approaches used to establish phenotypic variation, and relate three well-characterized examples of bistability to the molecular mechanisms that govern these processes, with a focus on positive feedback.

A Trial of the Efficacy, Safety and Impact on Drug Resistance of Four Drug Regimens for Seasonal Intermittent Preventive Treatment for Malaria in Senegalese Children

UNLABELLED: In the Sahel, most malaria deaths occur among children 1-4 years old during a short transmission season. A trial of seasonal intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine (SP) and a single dose of artesunate (AS) showed an 86% reduction in the incidence of malaria in Senegal but this may not be the optimum regimen. We compared this regimen with three alternatives. METHODS: 2102 children aged 6-59 months received either one dose of SP plus one dose of AS (SP+1AS) (the previous regimen), one dose of SP plus 3 daily doses of AS (SP+3AS), one dose of SP plus three daily doses of amodiaquine (AQ) (SP+3AQ) or 3 daily doses of AQ and AS (3AQ+3AS). Treatments were given once a month on three occasions during the malaria transmission season. The primary end point was incidence of clinical malaria. Secondary end-points were incidence of adverse events, mean haemoglobin concentration and prevalence of parasites carrying markers of resistance to SP. FINDINGS: The incidence of malaria, and the prevalence of parasitaemia at the end of the transmission season, were lowest in the group that received SP+3AQ: 10% of children in the group that received SP+1AS had malaria, compared to 9% in the SP+3AS group (hazard ratio HR 0.90, 95%CI 0.60, 1.36); 11% in the 3AQ+3AS group, HR 1.1 (0.76-1.7); and 5% in the SP+3AQ group, HR 0.50 (0.30-0.81). Mutations associated with resistance to SP were present in almost all parasites detected at the end of the transmission season, but the prevalence of Plasmodium falciparum was very low in the SP+3AQ group. CONCLUSIONS: Monthly treatment with SP+3AQ is a highly effective regimen for seasonal IPT. Choice of this regimen would minimise the spread of drug resistance and allow artemisinins to be reserved for the treatment of acute clinical malaria

Low referral completion of rapid diagnostic test-negative patients in community-based treatment of malaria in Sierra Leone

ABSTRACT

Urban malaria and associated risk factors in Jimma town, south-west Ethiopia

<p>Abstract</p> <p>Background</p> <p>Malaria kills millions around the world. Until recently it was believed to be a disease of rural areas, since the <it>Anopheles </it>mosquito, which transmits <it>Plasmodium </it>species breeds in rural areas. Urban malaria is emerging as a potential, but "avertable" crisis, in Africa. In view of the rapidly growing number of small and medium-sized towns in Ethiopia there is a pressing need to improve the understanding of the epidemiology of malaria. Therefore, the aim of this study was to determine malaria prevalence and associated risk factors in Jimma town.</p> <p>Methods</p> <p>A cross-sectional study was carried out in Jimma town from April 1 to May 28, 2010. 804 study participants were included from 291 households for microscopic examination of malaria parasites. Socio-demography data and risk factors were collected using structured questionnaires. Logistic regression analysis was done using SPSS 15.0 statistical software.</p> <p>Results</p> <p>From a total of 804 study participants in current survey only 42 (5.2%) were positive for malaria parasites. <it>Plasmodium vivax, Plasmodium falciparum </it>and mixed infection accounted 71.4%, 26.2% and 2.4%, respectively. Higher malaria prevalence rate was observed among under-five children (11%). Those who do not use insecticide-treated bed nets (ITN) were more likely to be infected with malaria (OR = 13.6; 95% CI 4.9-37.2, p < 0.001) compared with those who use the ITN. Living in areas where stagnant water existed (OR = 2.1; 95% CI 1.00-4.2, p = 0.047) and its distance of existence <1 km from the house(OR = 2.1; 95% CI 2.0-15.8, p = 0.001) were more likely to be infected with malaria parasite compared with those who live away from stagnant at a distance greater than 1 km.</p> <p>Conclusion</p> <p>Malaria is a major health problem with <it>P. vivax </it>becoming a predominant species in the town. The prevalence was strongly associated with proximity of residence to potential mosquito breeding sites. Malaria is affecting significant proportions of the urban settlers and human activities nevertheless play an important role in bringing the mosquito breeding sites closer to residences.</p