249 research outputs found
Summary and analysis of performance and stability characteristics of the refan JT8D-109 engine
The refan JT8D-109 performance and stability characteristics are reported as determined from sea level testing, altitude testing, and DC-9 flight testing. The test results are summarized as follows: (1) TSFC at SLS achieved design goal of 12.66 percent reduction. (2) TSFC at altitude average cruise power 0.5 percent higher than design goal, (3) TSFC at altitude maximum cruise power 1.7-3.7 percent higher than design goal, (4) ground starting consistent with JT8D-9 base engine, (5) successful flight starts without starter assist, (6) transient surge margin equivalent to JT8D-9, (7) stable engine operation with inlet distortion, and (8) stable engine operation during snap acceleration and deceleration. A flight idle setting is required for acceptable aborted-landing go-around acceleration time due to increase in low-rotor moment of inertia, and a performance improvement program should be conducted as part of any future certification program
An Evaluation of the Possible Protective Effects of Neonatal Striatal Transplants Against Kainic Acid-Induced Lesions
The present study examined the recent report
that transplantation of neonatal striatal tissue
into kainic acid (KA) lesioned striatum protected
the contralateral striatum from a subsequent KA
lesion. We did not find a significant difference in
the survival rate of animals that received
neonatal striatal transplants into a KA lesioned
striatum followed by a subsequent lesion of the
contralateral striatum compared to those
animals that received bilateral KA-induced
striatal lesions alone. The tissue transplants did
not protect against the degeneration of striatal
neurons induced by KA. Indeed, the survival
rate was very low (25%) in the transplant groups.
A second experiment was also performed to
examine whether a neonatal striatal transplant
might reduce the severe syndrome of aphagia
and adipsia associated with KA lesions of the
striatum. Animals that received the neonatal
striatal transplants showed increased aphagia
and adipsia compared to animals only receiving
the KA lesion. Again, the transplant group had a
very low survival rate (10%). The present study
was unable to confirm that neonatal striatal
transplants protect against KA lesions either by
themselves or in conjunction with a recent KA
lesion
Peripheral injection of human umbilical cord blood stimulates neurogenesis in the aged rat brain
<p>Abstract</p> <p>Background</p> <p>Neurogenesis continues to occur throughout life but dramatically decreases with increasing age. This decrease is mostly related to a decline in proliferative activity as a result of an impoverishment of the microenvironment of the aged brain, including a reduction in trophic factors and increased inflammation.</p> <p>Results</p> <p>We determined that human umbilical cord blood mononuclear cells (UCBMC) given peripherally, by an intravenous injection, could rejuvenate the proliferative activity of the aged neural stem/progenitor cells. This increase in proliferation lasted for at least 15 days after the delivery of the UCBMC. Along with the increase in proliferation following UCBMC treatment, an increase in neurogenesis was also found in the aged animals. The increase in neurogenesis as a result of UCBMC treatment seemed to be due to a decrease in inflammation, as a decrease in the number of activated microglia was found and this decrease correlated with the increase in neurogenesis.</p> <p>Conclusion</p> <p>The results demonstrate that a single intravenous injection of UCBMC in aged rats can significantly improve the microenvironment of the aged hippocampus and rejuvenate the aged neural stem/progenitor cells. Our results raise the possibility of a peripherally administered cell therapy as an effective approach to improve the microenvironment of the aged brain.</p
Human Umbilical Cord Blood Treatment in a Mouse Model of ALS: Optimization of Cell Dose
Amyotrophic Lateral Sclerosis (ALS) is a multicausal disease characterized by motor neuron degeneration in the spinal cord and brain. Cell therapy may be a promising new treatment for this devastating disorder. We recently showed that a single low dose (10(6) cells) of mononuclear human umbilical cord blood (MNC hUCB) cells administered intravenously to G93A mice delayed symptom progression and modestly prolonged lifespan. The aim of this pre-clinical translation study is to optimize the dose of MNC hUCB cells to retard disease progression in G93A mice. Three different doses of MNC hUCB cells, 10x10(6), 25x10(6) and 50x10(6), were administered intravenously into pre-symptomatic G93A mice. Motor function tests and various assays to determine cell effects were performed on these mice.Our results showed that a cell dose of 25x10(6) cells significantly increased lifespan of mice by 20-25% and delayed disease progression by 15%. The most beneficial effect on decreasing pro-inflammatory cytokines in the brain and spinal cord was found in this group of mice. Human Th2 cytokines were found in plasma of mice receiving 25x10(6) cells, although prevalent human Th1 cytokines were indicated in mice with 50x10(6) cells. High response of splenic cells to mitogen (PHA) was indicated in mice receiving 25x10(6) (mainly) and 10x10(6) cells. Significantly increased lymphocytes and decreased neutrophils in the peripheral blood were found only in animals receiving 25x10(6) cells. Stable reduction in microglia density in both cervical and lumbar spinal cords was also noted in mice administered with 25x10(6) cells.These results demonstrate that treatment for ALS with an appropriate dose of MNC hUCB cells may provide a neuroprotective effect for motor neurons through active involvement of these cells in modulating the host immune inflammatory system response
Parametric amplification with weak-link nonlinearity in superconducting microresonators
Nonlinear kinetic inductance in a high Q superconducting coplanar waveguide
microresonator can cause a bifurcation of the resonance curve. Near the
critical pumping power and frequency for bifurcation, large parametric gain is
observed for signals in the frequency band near resonance. We show experimental
results on signal and intermodulation gain which are well described by a theory
of the parametric amplification based on a Kerr nonlinearity. Phase dependent
gain, or signal squeezing, is verified with a homodyne detection scheme.Comment: Submitted to Physica Scripta, topical issue: Nobel Symposium on
Quantum Bits, 2009. 10 pages, 5 figures. Version 2 contains a few new
sentences about the current-phase relation of weak link
Aspectos Socioambientais da Produção PecuĂĄria e AgrĂcola nas Bacias dos Rios do Peixe, Canoas e Pelotas - Santa Catarina.
Este trabalho busca caracterizar as principais formas de uso da terra nos 61 municĂpios compreendidos
pelas Bacias do Rio do Peixe, Canoas e Pelotas/SC. Este diagnĂłstico teve como finalidade subsidiar
um plano de gestĂŁo dos recursos hĂdricos superficiais das referidas bacias. A metodologia envolveu
além da revisão bibliogråfica, a utilização de imagens produto de sensoriamento remoto Landsat
TM_05 e CBERS_2 e trabalhos de campo. Também foram resgatados dados sobre a população,
produção pecuĂĄria, de suĂnos, bovinos e aves e, principais lavouras (permanentes e temporĂĄrias). Os
resultados indicam para uso da terra, 34,80% de matas, 31,53% de campos e pastagens, 19,35% de
cultivos, 12,53% de silvicultura, 1,15% de corpos dâĂĄgua e 0,64% de ĂĄreas urbanas. A dispersĂŁo
espacial da criação de suĂnos e aves concentra-se na Bacia do Rio do Peixe e a de bovinos estĂĄ
dispersa nas 3 bacias. Considerando a agricultura temporĂĄria, a cultura do milho acumula maior
produção na bacia do Rio do Peixe e estĂĄ associado Ă criação de suĂnos e aves. Com relação Ă
agricultura permanente, destaca-se a produção de uva na Bacia do Rio do Peixe e de maçã nas Bacias
dos Rios Canoas e Pelotas. Principalmente nestas, registrou-se um aumento da silvicultura do Pinus
entre 1990 e 2010, quando a ĂĄrea total passou de 184.073 para 370.035 hectares. A gestĂŁo dos recursos
hĂdricos superficiais e subterrĂąneos das bacias deverĂĄ considerar as ĂĄreas de ocorrĂȘncia das respectivas
produçÔes
Cortactin and phagocytosis in isolated Sertoli cells
BACKGROUND: Cortactin, an actin binding protein, has been associated with Sertoli cell ectoplasmic specializations in vivo, based on its immunolocalization around the heads of elongated spermatids, but not previously identified in isolated Sertoli cells. In an in vitro model of Sertoli cell-spermatid binding, cortactin was identified around debris and dead germ cells. Based on this observation, we hypothesized that this actin binding protein may be associated with a non-junction-related physiological function, such as phagocytosis. The purpose of this study was to identify the presence and distribution of cortactin in isolated rat Sertoli cells active in phagocytic activity following the addition of 0.8 ÎŒm latex beads. RESULTS: Sertoli cell monocultures were incubated with or without follicle stimulating hormone (FSH; 0.1 ÎŒg/ml) in the presence or absence of cytochalasin D (2 ÎŒM), as an actin disrupter. Cortactin was identified by standard immunostaining with anti-cortactin, clone 4F11 (Upstate) after incubation times of 15 min, 2 hr, and 24 hr with or without beads. Cells exposed to no hormone and no beads appeared to have a ubiquitous distribution of cortactin throughout the cytoplasm. In the presence of cytochalasin D, cortactin immunostaining was punctate and distributed in a pattern similar to that reported for actin in cells exposed to cytochalasin D. Sertoli cells not exposed to FSH, but activated with beads, did not show cortactin immunostaining around the phagocytized beads at any of the time periods. FSH exposure did not alter the distribution of cortactin within Sertoli cells, even when phagocytic activity was upregulated by the presence of beads. CONCLUSION: Results of this study suggest cortactin is not associated with peripheralized actin at junctional or phagocytic sites. Further studies are necessary to clarify the role of cortactin in Sertoli cells
Determinants of abstract acceptance for the Digestive Diseases Week â a cross sectional study
BACKGROUND: The Digestive Diseases Week (DDW) is the major meeting for presentation of research in gastroenterology. The acceptance of an abstract for presentation at this meeting is the most important determinant of subsequent full publication. We wished to examine the determinants of abstract acceptance for this meeting. METHODS: A cross-sectional study was performed, based on abstracts submitted to the DDW. All 17,205 abstracts submitted from 1992 to 1995 were reviewed for acceptance, country of origin and research type (controlled clinical trials (CCT), other clinical research (OCR), basic science (BSS)). A random sub-sample (n = 1,000) was further evaluated for formal abstract quality, statistical significance of study results and sample size. RESULTS: 326 CCT, 455 OCR and 219 BSS abstracts were evaluated in detail. Abstracts from N/W Europe (OR 0.4, 95% CI 0.3â0.6), S/E Europe (OR 0.4, 95% CI 0.2â0.6) and non-Western countries (OR 0.3, 95% CI 0.2â0.5) were less likely to be accepted than North-American contributions when controlling for research type. In addition, the OR for the acceptance for studies with negative results as compared to those with positive results was 0.4 (95% CI 0.3â0.7). A high abstract quality score was also weakly associated with acceptance rates (OR 1.4, 95% CI 1.0â2.0). CONCLUSIONS: North-American contributions and reports with statistically positive results have higher acceptance rates at the AGA. Formal abstract quality was also predictive for acceptance
Proliferative Hypothalamic Neurospheres Express NPY, AGRP, POMC, CART and Orexin-A and Differentiate to Functional Neurons
Some pathological conditions with feeding pattern alterations, including obesity and Huntington disease (HD) are associated with hypothalamic dysfunction and neuronal cell death. Additionally, the hypothalamus is a neurogenic region with the constitutive capacity to generate new cells of neuronal lineage, in adult rodents
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