794 research outputs found

    Balloon launched Viking decelerator test program

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    Four BLDT flights were conducted during the summer of 1972. The purpose of these tests was to qualify the Viking parachute system behind the full-scale Viking entry vehicle over the maximum range of entry conditions anticipated in the Viking '75 soft landing on Mars. A summary of the test series is presented. Test conditions ranged from a Mach number of 2.0 to 0.5 and dynamic pressure from 11.7 to 4.4 psf. This range of conditions covers the uncertainty in entry conditions at Mars due to atmospheric and entry performance uncertainties. Emphasis is placed on parachute performance and simulated Mars entry vehicle motions as influenced by the parachute performance. Conclusions are presented regarding the ability of the parachute to perform within the operational parameters required for a successful soft Martian landing. A list of references which covers all reports in the qualification test program is included

    Integration of Cattle and Improved Pastures under Coconuts in Southern Luzon, Philippines

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    Results of two studies involving 1) grazing of Signalgrass (Brachiaria decumbens) pastures at different stocking and 2) cut-and-carry forages in smallholder farms for cattle under coconuts are presented. Grazing at 3 AU/ha and 2 AU/ha gave significantly higher LWG/ha (P 0.05) over 1 AU/ha but highest financial return was obtained from 2 AU/ha. Productivity of cattle on cut-and-carry forages in small farms varies among farmers with better animal performance directly related to quantity and quality of feeds offered and industriousness of individual farmers. Both studies showed the benefits derived from integration of cattle with improved pastures under coconuts

    Disturbance decoupling for nonlinear systems: A unified approach

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    Initiation and Polymer Density of Conjugated Polymer Brushes

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    The growth mechanism and polymer density in conjugated polymer brush (CPB) films composed of poly(3-methylthiophene) (P3MT) are characterized. X-ray photoelectron spectroscopy experiments show that the initiation of aryl halide monolayers by Pd(PtBu3)2 produces disproportionated monolayer initiators. Unlike disproportionated species formed during the solution-phase initiation of aryl halides, which cannot mediate polymerization, the surface-bound initiators catalyze polymerization to form CPB films with a high grafting density (1.2 nm-2). Rutherford backscattering spectrometry (RBS) experiments show that P3MT CPB films have a characteristic monomer volume density (3.7 nm-3) that is indistinguishable from the volume density of spuncast poly(3-hexylthiophene) films. Using these RBS and XPS results, characteristics of P3MT CPB growth are obtained, including the turnover frequency (7.5 h-1) and polymer molecular weight (300 g/mol·nm)

    Women for science and science for women: Gaps, challenges and opportunities towards optimizing pre-exposure prophylaxis for HIV-1 prevention

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    Preventing new HIV infections remains a global challenge. Young women continue to bear a disproportionate burden of infection. Oral pre-exposure prophylaxis (PrEP), offers a novel women-initiated prevention technology and PrEP trials completed to date underscore the importance of their inclusion early in trials evaluating new HIV PrEP technologies. Data from completed topical and systemic PrEP trials highlight the role of gender specific physiological and social factors that impact PrEP uptake, adherence and efficacy. Here we review the past and current developments of HIV-1 prevention options for women with special focus on PrEP considering the diverse factors that can impact PrEP efficacy. Furthermore, we highlight the importance of inclusion of female scientists, clinicians, and community advocates in scientific efforts to further improve HIV prevention strategies

    Cyclopia with shoulder dystocia leading to an obstetric catastrophe: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Cyclopia is a rare fetal malformation characterized by a single palpebral fissure and a proboscis associated with severe brain malformations. Approximately 1.05 in 100,000 births including stillbirths are identified as cyclopean. The prevalence is about one in 11,000 to 20,000 in live births and one in 250 during embryogenesis.</p> <p>Case presentation</p> <p>A 30-year-old Indian woman of Asian origin, sixth gravida, was referred to the labor room of our hospital. There were no ultrasound examinations performed during this pregnancy as our patient had not received regular antenatal care. We found out that the head of her baby was already outside the vulva but the remaining parts of the baby were not yet delivered. Further examination was carried out and a diagnosis of shoulder dystocia with intrauterine fetal demise was made. A stillborn baby boy of 3.5 kg was delivered using McRoberts' maneuver. The baby was suspected of having features of cyclopia and this was later confirmed by autopsy and anatomic correlation. The mother had a cervical tear which extended into the lower segment of her uterus, thus leading to the rupture of her uterus. There was a massive broad ligament hematoma on the left side of her uterus. A total abdominal hysterectomy was carried out.</p> <p>Conclusion</p> <p>Prenatal diagnosis by ultrasound examination might help in detecting cyclopia and preventing complications associated with this condition. However, in developing countries where women do not receive regular antenatal care and do not undergo prenatal diagnosis, such cases will go undetected. In our case report, the occurrence of shoulder dystocia could be coincidental, as no risk factors were previously noted.</p
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