Integrated source and channel encoded digital communication system design study

The particular Ku-band carrier, PN despreading, and symbol synchronization strategies, which were selected for implementation in the Ku-band transponder aboard the orbiter, were assessed and evaluated from a systems performance viewpoint, verifying that system specifications were met. A study was performed of the design and implementation of tracking techniques which are suitable for incorporation into the Orbiter Ku-band communication system. Emphasis was placed on maximizing tracking accuracy and communication system flexibility while minimizing cost, weight, and system complexity of Orbiter and ground systems hardware. The payload communication study assessed the design and performance of the forward link and return link bent-pipe relay modes for attached and detached payloads. As part of this study, a design for a forward link bent-pipe was proposed which employs a residual carrier but which is tracked by the existing Costas loop

Non-invasive detection of animal nerve impulses with an atomic magnetometer operating near quantum limited sensitivity

Magnetic fields generated by human and animal organs, such as the heart, brain and nervous system carry information useful for biological and medical purposes. These magnetic fields are most commonly detected using cryogenically-cooled superconducting magnetometers. Here we present the frst detection of action potentials from an animal nerve using an optical atomic magnetometer. Using an optimal design we are able to achieve the sensitivity dominated by the quantum shot noise of light and quantum projection noise of atomic spins. Such sensitivity allows us to measure the nerve impulse with a miniature room-temperature sensor which is a critical advantage for biomedical applications. Positioning the sensor at a distance of a few millimeters from the nerve, corresponding to the distance between the skin and nerves in biological studies, we detect the magnetic field generated by an action potential of a frog sciatic nerve. From the magnetic field measurements we determine the activity of the nerve and the temporal shape of the nerve impulse. This work opens new ways towards implementing optical magnetometers as practical devices for medical diagnostics.Comment: Main text with figures, and methods and supplementary informatio

Unprotected sex, sexually transmitted infections and problem drinking among female sex workers in Ethiopia

Background: A description of the pattern of use of alcohol and other substances among female sex workers (FSWs) is particularly important because of the high prevalence of HIV in this particular group and their potential for transmitting HIV infection to other groups. However, there is currently lack of systematic studies from developing countries like Ethiopia regarding alcohol use visa vis unprotected sex and STIs. Objective: To describe the association of risky sexual behaviour with alcohol use and problem drinking among female sex workers in Ethiopia. Methods: A total of 2,487 female sex workers aged between of 15 and 49 years were randomly sampled from seven urban centres in Ethiopia and interviewed regarding their sexual behavior and substance use. Results: About 12% of FSWs included in this study reported having unprotected sex during the 12 months prior to the interview. A history of vaginal ulcer or discharge experienced by the FSWs was reported by 5% of the study subjects. Those who reported occasional use of alcohol were found to have a two-fold increase in the odds of havingunprotected sex compared to non-users: adjusted OR (95% CI) = 2.06 (1.28, 3.33). Those who responded positively to at least one question from the four - item questionnaire known as CAGE, and which is used as an indicator for problem drinking, had a 50% increased odds of unprotected sex compared with zero scorers: adj. OR (95% CI) = 1.48 (1.07, 2.05). Those who reported alcohol use on a daily basis were found to have a two-fold increased odds of having sexually transmitted infections (STIs) compared to the non-users of alcohol: adj. OR (95% CI) = 2.50 (1.35, 4.64). Compared to those who were not literate, educational attainment was associated with a lower odds of reporting vaginal discharge or ulcers in those that have attended elementary education: adj. Or (95% CI) = 0.56 (0.35, 0.89.), and secondary education: adj. OR (95% CI) = 0.59 (0.37, 0.93). Conclusion: Unprotected sex and symptoms of STIs were associated with alcohol use, problem drinking and lower educational attainment. The Ethiopian Journal of Health Development Vol. 20 (2) 2006: 93-9

Prunier d'Afrique (Sclerocarya birrea)

Conservation and sustainable use of genetic resources of priority food tree species in sub-Saharan AfricaConservation et utilisation durable des ressources génétiques des espèces ligneuses alimentaires prioritaires de l'Afrique subsaharienneLa publicación de esta hoja divulgativa ha sido financiada con la acción complementaria nº AC-2008-00050-00-00, titulada "Publicación de hojas divulgativas: Uso y gestión sostenible y conservación de especies forestales para la alimentación (ELA) en Africa Subsahariana" solicitada por el Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), investigador responsable: Eduardo Notivo

Hepatotoxicity and Associated Risk Factors in Hiv-Infected Patients Receiving Antiretroviral Therapy at Felege Hiwot Referral Hospital, Bahirdar, Ethiopia

Background: In Human Immunodeficiency Virus (HIV) infected patients on antiretroviral treatment (ART), hepatotoxicity is life threatening. Its outcome may lead to liver failure and death. This study was conducted to determine the rate and determinants of elevated alanine amino transferase (ALT) (referred as >40IU/L for both males and females).Methods: A cross sectional study was conducted on HIV infected individuals who are on ART and suspected of drug resistance at Felege Hiwot Referral Hospital, Bahir Dar from July to December 2012. Venous bloods were collected from each patient and processed parallely to determine ALT, number of HIV RNAs, CD4 and CD8 T cells count, anti hepatitis C virus (HCV) and hepatitis B surface antigen.Results: Out of 269 HIV infected patients receiving ART, 32% were confirmed of grades 1-4 levels of elevated ALT. The rate of severe hepatotoxicity (grade 3 and 4) was 1.84%. Patients with increased CD8 T cell counts (P=0.011; AOR=1.82; CI: 1.12 - 2.54), alcohol over use (P=0.014; AOR = 1.23; CI: 1.36- 3.29) and detectable HIV-1 RNA copies (P=0.015; AOR=2.07; CI: 1.15-3.74) independently predicts the elevation of ALT.Conclusions: In HIV infected patients on ART, extreme elevations of ALT were infrequent but minor elevations were common so that patient-linked variables such as use of alcohol intake must be taken in to account for better clinical management of ART patients. The role of active HCV co-infection on the treatment outcome of ART should be further studied.Key words: ALT, HIV, ART, Bahir Dar, Ethiopi

Distributional Preferences in Adolescent Peer Networks

We study distributional ("social") preferences in adolescent peer networks. Using incentivized choices between allocations for themselves and a passive agent, children are classified into efficiency-loving, inequality-loving, inequality-averse, and spiteful types. We find that pairs of students who report a friendship link are more likely to exhibit the same preference type than other students that attend the same school. The relation between types is almost completely driven by inequality-loving and spiteful types. Further analyses suggest that preference peer networks are mainly formed by selection into the network and, to a smaller degree, by preference transmission. The role of peer networks in explaining distributional preferences goes beyond network composition effects. A low rank in academic performance and a central position within the network relate positively to a higher likelihood of being classified as spiteful. Hence, social hierarchies seem to be correlated with distributional preference types

Mechanical properties of nanotubes of polyelectrolyte multilayers

The elastic properties of nanotubes fabricated by layer-by-layer (LbL) assembly of polyelectrolytes in the nanopores of polycarbonate track-etched membranes have been investigated by resonant contact Atomic Force Microscopy (AFM), for nanotube diameters in the range of 100 to 200 nm. The elastic modulus of the nanotubes was computed from the resonance frequencies of a cantilever resting on freely suspended LbL nanotubes. An average value of 115MPa was found in air for Young's modulus of these nanostructures, well below the values reported for dry, flat multilayers, but in the range of values reported for water-swollen flat multilayers. These low values are most probably due to the lower degree of ionic cross-linking of LbL nanotubes and their consequently higher water content in air, resulting from the peculiar mode of growth of nanoconfined polyelectrolyte multilayers

Challenges and opportunities for implementing integrated mental health care: a district level situation analysis from five low- and middle-income countries.

BACKGROUND: Little is known about how to tailor implementation of mental health services in low- and middle-income countries (LMICs) to the diverse settings encountered within and between countries. In this paper we compare the baseline context, challenges and opportunities in districts in five LMICs (Ethiopia, India, Nepal, South Africa and Uganda) participating in the PRogramme for Improving Mental health carE (PRIME). The purpose was to inform development and implementation of a comprehensive district plan to integrate mental health into primary care. METHODS: A situation analysis tool was developed for the study, drawing on existing tools and expert consensus. Cross-sectional information obtained was largely in the public domain in all five districts. RESULTS: The PRIME study districts face substantial contextual and health system challenges many of which are common across sites. Reliable information on existing treatment coverage for mental disorders was unavailable. Particularly in the low-income countries, many health service organisational requirements for mental health care were absent, including specialist mental health professionals to support the service and reliable supplies of medication. Across all sites, community mental health literacy was low and there were no models of multi-sectoral working or collaborations with traditional or religious healers. Nonetheless health system opportunities were apparent. In each district there was potential to apply existing models of care for tuberculosis and HIV or non-communicable disorders, which have established mechanisms for detection of drop-out from care, outreach and adherence support. The extensive networks of community-based health workers and volunteers in most districts provide further opportunities to expand mental health care. CONCLUSIONS: The low level of baseline health system preparedness across sites underlines that interventions at the levels of health care organisation, health facility and community will all be essential for sustainable delivery of quality mental health care integrated into primary care