Space Shuttle Proximity Operation Sensor Study

The performance of the Kuband radar was analyzed in detail, and the performance was updated and summarized. In so doing, two different radar design philosophies were described, and the corresponding differences in losses were enumerated. The resulting design margins were determined for both design philosophies and for both the designated and nondesignated range modes of operation. In some cases, the design margin was about zero, and in other cases it was significantly less than zero. With the point of view described above, the recommended solution is to allow more scan time but at the present scan rate. With no other changes in the present configuration, the radar met design detection specifications for all design philosophies at a range of 11.3 nautical miles

Study to investigate and evaluate means of optimizing the Ku-band combined radar/communication functions for the space shuttle

The performance of the space shuttle orbiter's Ku-Band integrated radar and communications equipment is analyzed for the radar mode of operation. The block diagram of the rendezvous radar subsystem is described. Power budgets for passive target detection are calculated, based on the estimated values of system losses. Requirements for processing of radar signals in the search and track modes are examined. Time multiplexed, single-channel, angle tracking of passive scintillating targets is analyzed. Radar performance in the presence of main lobe ground clutter is considered and candidate techniques for clutter suppression are discussed. Principal system parameter drivers are examined for the case of stationkeeping at ranges comparable to target dimension. Candidate ranging waveforms for short range operation are analyzed and compared. The logarithmic error discriminant utilized for range, range rate and angle tracking is formulated and applied to the quantitative analysis of radar subsystem tracking loops

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

Study to investigate and evaluate means of optimizing the Ku-band combined radar/communication functions for the space shuttle

The Ku band radar system on the shuttle orbiter operates in both a search and a tracking mode, and its transmitter and antennas share time with the communication mode in the integrated system. The power allocation properties and the Costa subloop subcarrier tracking performance associated with the baseline digital phase shift implementation of the three channel orbiter Ku band modulator are discussed

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

A machine learning-based framework for forecasting sales of new products with short life cycles using deep neural networks

Demand forecasting is becoming increasingly important as firms launch new products with short life cycles more frequently. This paper provides a framework based on state-of-the-art techniques that enables firms to use quantitative methods to forecast sales of newly launched, short-lived products that are similar to previous products when there is limited availability of historical sales data for the new product. In addition to exploiting historical data using time-series clustering, we perform data augmentation to generate sufficient sales data and consider two quantitative cluster assignment methods. We apply one traditional statistical (ARIMAX) and three machine learning methods based on deep neural networks (DNNs) – long short-term memory, gated recurrent units, and convolutional neural networks. Using two large data sets, we investigate the forecasting methods’ comparative performance and, for the larger data set, show that clustering generally results in substantially lower forecast errors. Our key empirical finding is that simple ARIMAX considerably outperforms the more advanced DNNs, with mean absolute errors up to 21%–24% lower. However, when adding Gaussian white noise in our robustness analysis, we find that ARIMAX's performance deteriorates dramatically, whereas the considered DNNs display robust performance. Our results provide insights for practitioners on when to use advanced deep learning methods and when to use traditional methods

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

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

Adherence to the management of type i diabetes among Palestinian patients in Nablus city: a cross-sectional study

The purpose of this study is to investigate the adherence to the management of Type I Diabetes and to investigate factors associated with non-adherence among Palestinian Type 1 Diabetes patients. One hundred and twenty-six patients diagnosed with Type 1 Diabetes were enrolled in an observational cross-sectional study. Diabetes self-care adherence was measured using the Self Care Inventory (SCI). The patients were recruited from a diabetes clinic in Nablus city in Palestine. One-way ANOVA test and simple linear regressions were used in the statistical analysis. Participants age ranged from 3-43 years; 56% of them were females. The mean age at diagnosis for them was 10 years (+/-6.25). The mean glycosylated hemoglobin (A1C) was 9 +/-2.32. 66% of patients reported significant non-adherence to glucose testing, 89% reported non-adherence to diet recommendations, 79% reported non-adherence to exercise, and 21% reported non-adherence to administering insulin on time. Age (r = 0.29, P < 0.05), A1C (r = 0.21, P < 0.05), sex (P < 0.05), and patient educational level (P< 0.05) were significantly related to adherence score. Adherence to treatment among patients with Type 1 Diabetes is poor and is associated with age, sex, A1C, and patient educational level. Designed education programs should be implemented among patients with Type 1 Diabetes, which address the importance of adherence to the management of the diseases. More strategies should focus on monitoring the diet and insulin administration. © 2022, An-Najah National University. All rights reserved

Moving towards universal health coverage for mental disorders in Ethiopia

Background: People with mental disorders in low-income countries are at risk of being left behind during efforts to expand universal health coverage. Aims: To propose context-relevant strategies for moving towards universal health coverage for people with mental disorders in Ethiopia. Methods: We conducted a situational analysis to inform a SWOT analysis of coverage of mental health services and financial risk protection, health system characteristics and the macroeconomic and fiscal environment. In-depth interviews were conducted with five national experts on health financing and equity and analysed using a thematic approach. Findings from the situation analysis and qualitative study were used to develop recommended strategies for adequate, fair and sustainable financing of mental health care in Ethiopia. Results: Opportunities for improved financing of mental health care identified from the situation analysis included: a significant mental health burden with evidence from strong local epidemiological data; political commitment to address that burden; a health system with mechanisms for integrating mental health into primary care; and a favourable macro-fiscal environment for investment in human capabilities. Balanced against this were constraints of low current general government health expenditure, low numbers of mental health specialists, weak capacity to plan and implement mental health programmes and low population demand for mental health care. All key informants referred to the under-investment in mental health care in Ethiopia. Respondents emphasised opportunities afforded by positive rates of economic growth in the country and the expansion of community-based health insurance, as well as the need to ensure full implementation of existing task-sharing programmes for mental health care, integrate mental health into other priority programmes and strengthen advocacy to ensure mental health is given due attention. Conclusion: Expansion of public health insurance, leveraging resources from high-priority SDG-related programmes and implementing existing plans to support task-shared mental health care are key steps towards universal health coverage for mental disorders in Ethiopia. However, external donors also need to deliver on commitments to include mental health within development funding. Future researchers and planners can apply this approach to other countries of sub-Saharan Africa and identify common strategies for sustainable and equitable financing of mental health care