213 research outputs found

    A compact magnetic bearing for gimballed momentum wheel

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    A three axis controlled magnetic bearing and its application to a momentum wheel are described. The four divided stators provide a momentum wheel with high reliability, low weight, large angular momentum storage capacity, and gimbal control. Those characteristics are desirable for spacecraft attitude control

    Domestication of Terminalia brownii Among Smallholder Farmers in Eastern Kenya: A Double Hurdle Approach.

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    The research is financed by National Research Fund, Kenya Abstract Evidence has shown that the population of Terminalia brownii continue to dwindle in its native range due to drought, agricultural expansion and settlement and over exploitation for charcoal, beehives, carvings and timber. High levels of exploitation accompanied by awareness creation on value addition remains an exit strategy towards poverty alleviation for improved rural livelihoods, hence, the need to support its domestication. Scientists and researchers have prioritized promotion of this species in Eastern Kenya. However, information on intensity of domestication of the species remained scanty. A sample of 346 T. brownii producers were selected using a multi-stage sampling procedure in Embu, Machakos, Kitui and Makueni Counties in Kenya. Primary data was collected using a pretested structured questionnaire while secondary data was acquired from the Kenya Forest Service offices in the study area. A double hurdle econometric model was used to analyse the determinants of decision and intensity of use of T. brownii. Results revealed that five variables that significantly influence the decision to domesticate T. brownii include; education level of household head, importance of farm to the household income, access to credit, dependency ratio and intercropping. On the other hand, education of the household head, size of the farm and total income from livestock sales influenced intensity of domestication of T. brownii. Therefore, there is need to develop programs to sensitize farmers on the importance of the species on their farms. Lastly, we need to promote structures for commercialization of the agroforestry products from this tree species to reduce unemployment. Keywords: Terminalia brownii, Domestication, Agroforestry, Dryland, Double Hurdle DOI: 10.7176/JESD/10-16-07 Publication date: August 31st 201

    PEMBUATAN KARBON AKTIF DARI KULIT SALAK (Salacca Zalacca) DENGAN PROSES FISIKA MENGGUNAKAN UAP DENGAN PEMANAS MICROWAVE

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    This study aimed to determine the best adsorption capacity, compounds contained in activated carbon and burn off that produced. In this study, activated carbon have been prepared from the bark of Salacca zalacca by physically activating using a microwave. The 70 gram  bark of Salacca zalaccawas pyrolised in a furnace with flowing gas N2 with temperature 500 oC for 120 minutes followed by microwave activation at 2450 MHz with power 600 W, 800 W and 1000 W for 20 minutes, 40 minutes and 60 minutes. The results showed the best burn off on microwave power 1000 W with 60 minutes activation time of 90,25%. The best activated carbon adsorption capacity at 800 W microwave power for 20 minutes is 19,96 mg/g. The best allowanced percentage at 800 W microwave power with 20 minutes activation time is 99,82%. Characterization of Fourier Transform Infra-Red (FITR) showed the presence of C=O (carbonyl) bonds indicating the presence of carbon-active substances. After pyrolysis forms a C≡C (Alkuna) bond which indicated more carbon was produced. This is supported by the characterization of Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) showing the surface morphology of rough and irregular activated carbon and the amount of carbon and oxide content on activated carbon of 44,44% and 28,54% sequentially

    Long-Term Effects of Polychlorinated Biphenyls and Dioxins on Pregnancy Outcomes in Women Affected by the Yusho Incident

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    Background: Maternal exposure to polychlorinated biphenyls (PCBs) is associated with increased proportions of spontaneous abortion and stillbirth in animal studies. In Japan in 1968, accidental human exposure to rice oil contaminated with PCBs and other dioxin-related compounds, such as polychlorinated dibenzofurans (PCDFs), led to the development of what was later referred to as Yusho oil disease. Objective: The aim of this study was to investigated the association of maternal PCB and dioxin exposure with adverse pregnancy outcomes in Yusho women. Methods: In 2004, we interviewed 214 Yusho women (512 pregnancies) about their pregnancy outcomes over the past 36 years. Pregnancy outcomes included induced abortion, spontaneous abortion, preterm delivery, and pregnancy loss. Results: In pregnancy years 1968-1977 (within the first 10 years after exposure), the proportions of induced abortion [adds ration adjusted for age at delivery (ORadj) = 5.93; 95% confidence interval (CI), 2.21-15.91; two-tailed p < 0.001) and preterm delivery (ORadj = 5.70; 95% CI, 1.17-27.79; p = 0.03) were significantly increased compared with the proportions in pregnancy years 1958-1967 (10 years before the incident). Spontaneous abortion (ORadj = 2.09; 95% CI, 0.84-5.18), and pregnancy loss (ORadj = 2.11; 95% CI, 0.92-4.87) were more frequent (OR = 2.18; 95% CI, 1.02-4.66), but these were not significant (p = 0.11 and p = 0.08, respectively) in pregnancy years 1968-1977. We found no significant increases in the proportions of these adverse pregnancy outcomes in pregnancies occurring during 1978-1987 or 1988-2003 compared with those in pregnancies before 1968. Conclusion: High levels of PCB/PCDF exposure had some adverse effects on pregnancy outcome in Yusho women

    The Mitochondrial Ca(2+) Uniporter: Structure, Function, and Pharmacology.

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    Mitochondrial Ca(2+) uptake is crucial for an array of cellular functions while an imbalance can elicit cell death. In this chapter, we briefly reviewed the various modes of mitochondrial Ca(2+) uptake and our current understanding of mitochondrial Ca(2+) homeostasis in regards to cell physiology and pathophysiology. Further, this chapter focuses on the molecular identities, intracellular regulators as well as the pharmacology of mitochondrial Ca(2+) uniporter complex

    Impaired Distal Thermoregulation in Diabetes and Diabetic Polyneuropathy

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    Objective: To determine how thermoregulation of the feet is affected by diabetes and diabetic polyneuropathy in both wakefulness and sleep. Research Design and Methods: Normal subjects, diabetic subjects without neuropathy, diabetic subjects with small-fiber diabetic polyneuropathy, and those with advanced diabetic polyneuropathy were categorized based on neurological examination, nerve conduction studies, and quantitative sensory testing. Subjects underwent foot temperature monitoring using an iButton device attached to the foot and a second iButton for recording of ambient temperature. Socks and footwear were standardized, and subjects maintained an activity diary. Data were collected over a 32-h period and analyzed. Results: A total of 39 normal subjects, 28 patients with diabetes but without diabetic polyneuropathy, 14 patients with isolated small-fiber diabetic polyneuropathy, and 27 patients with more advanced diabetic polyneuropathy participated. No consistent differences in foot temperature regulation between the four groups were identified during wakefulness. During sleep, however, multiple metrics revealed significant abnormalities in the diabetic patients. These included reduced mean foot temperature (P < 0.001), reduced maximal temperature (P < 0.001), increased rate of cooling (P < 0.001), as well as increased frequency of variation (P = 0.005), supporting that patients with diabetic polyneuropathy and even those with only diabetes but no diabetic polyneuropathy have impaired nocturnal thermoregulation. Conclusions: Nocturnal foot thermoregulation is impaired in patients with diabetes and diabetic polyneuropathy. Because neurons are highly temperature sensitive and because foot warming is part of the normal biology of sleep onset and maintenance, these findings suggest new potentially treatable mechanisms of diabetes-associated nocturnal pain and sleep disturbance

    Agent based modelling helps in understanding the rules by which fibroblasts support keratinocyte colony formation

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    Background: Autologous keratincoytes are routinely expanded using irradiated mouse fibroblasts and bovine serum for clinical use. With growing concerns about the safety of these xenobiotic materials, it is desirable to culture keratinocytes in media without animal derived products. An improved understanding of epithelial/mesenchymal interactions could assist in this. Methodology/Principal Findings: A keratincyte/fibroblast o-culture model was developed by extending an agent-based keratinocyte colony formation model to include the response of keratinocytes to both fibroblasts and serum. The model was validated by comparison of the in virtuo and in vitro multicellular behaviour of keratinocytes and fibroblasts in single and co-culture in Greens medium. To test the robustness of the model, several properties of the fibroblasts were changed to investigate their influence on the multicellular morphogenesis of keratinocyes and fibroblasts. The model was then used to generate hypotheses to explore the interactions of both proliferative and growth arrested fibroblasts with keratinocytes. The key predictions arising from the model which were confirmed by in vitro experiments were that 1) the ratio of fibroblasts to keratinocytes would critically influence keratinocyte colony expansion, 2) this ratio needed to be optimum at the beginning of the co-culture, 3) proliferative fibroblasts would be more effective than irradiated cells in expanding keratinocytes and 4) in the presence of an adequate number of fibroblasts, keratinocyte expansion would be independent of serum. Conclusions: A closely associated computational and biological approach is a powerful tool for understanding complex biological systems such as the interactions between keratinocytes and fibroblasts. The key outcome of this study is the finding that the early addition of a critical ratio of proliferative fibroblasts can give rapid keratinocyte expansion without the use of irradiated mouse fibroblasts and bovine serum

    Polymorphisms in the CD28/CTLA4/ICOS genes: Role in malignant melanoma susceptibility and prognosis?

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    The appearance of vitiligo and spontaneous regression of the primary lesion in melanoma patients illustrate a relationship between tumor immunity and autoimmunity. T lymphocytes play a major role both in tumor immunity and autoimmunity. CD28, Cytotoxic T lymphocyte antigen 4 (CTLA4) and inducible costimulator (ICOS) molecules are important secondary signal molecules in the T lymphocyte activation. Single nucleotide polymorphisms (SNPs) in the CD28/CTLA4/ICOS gene region were reported to be associated with several autoimmune diseases including, type-1 diabetes, SLE, autoimmune thyroid diseases and celiac disease. In this study, we investigated the association of SNPs in the CD28, CTLA4 and ICOS genes with the risk of melanoma. We also assessed the prognostic effect of the different polymorphisms in melanoma patients. Twenty-four tagging SNPs across the three genes and four additional SNPs were genotyped in a cohort of 763 German melanoma patients and 734 healthy German controls. Influence on prognosis was determined in 587 melanoma cases belonging to stage I or II of the disease. In general, no differences in genotype or allele frequencies were detected between melanoma patients and controls. However, the variant alleles for two polymorphisms in the CD28 gene were differentially distributed in cases and controls. Similarly no association of any polymorphism with prognosis, except for the rs3181098 polymorphism in the CD28 gene, was observed. In addition, individuals with AA genotype for rs11571323 polymorphism in the ICOS gene showed reduced overall survival. However, keeping in view the correction for multiple hypothesis testing our results suggest that the polymorphisms in the CD28, CTLA4 and ICOS genes at least do not modulate risk of melanoma and nor do those influence the disease prognosis in the investigated population
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