391 research outputs found

    Method and means for damping nutation in a satellite Patent

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    Flexible turnstile antenna system for reducing nutation in spin-oriented satellite

    Leukocyte margination in alveolar capillaries: Interrelationship with functional capillary geometry and microhemodynamics

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    The pulmonary capillary microvasculature harbors a large pool of intravascularly marginated leukocytes. In this study, we investigated the interrelationship of leukocyte margination with characteristics of functional capillary geometry and microhemodynamics in alveolar capillary networks. In 22 anesthetized rabbits we assessed functional capillary density, average capillary length, red blood cell velocity and leukocyte kinetics in alveolar capillary networks in vivo by intravital fluorescence microscopy. In alveolar wall areas of 12,800 +/- 1,800 mu m(2), we detected 3.6 +/- 0.5 sticking leukocytes and 21.0 +/- 1.9 functional capillary segments with an average capillary length of 35.7 +/- 2.1 mu m. We calculated that approximately 15% of functional capillary segments are blocked by marginated leukocytes. Leukocyte margination was predominantly observed in capillary networks characterized by a high functional capillary density, short capillary segments and low red blood cell velocities. The multitude of interconnected capillary channels in these networks may allow alveolar blood flow to bypass marginated leukocytes. Hence, this interrelationship may be relevant for maintenance of adequate alveolar perfusion and low capillary network resistance despite excessive leukocyte margination in the pulmonary microvasculature. Local microhemodynamic factors may play a regulatory role in the spatial distribution of leukocyte margination

    Leukocyte sequestration in pulmonary microvessels and lung injury following systemic complement activation in rabbits

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    Inflammatory reactions are associated with sequestration of leukocytes in the lung. Complement activation leads to accumulation of leukocytes in alveolar septa and alveoli, to lung edema and hemorrhage. Although in organs other than the lung leukocytes interact with the vascular endothelium only in postcapillary venules, alveolar capillaries are considered to be the site of leukocyte sequestration in the lung. However, pulmonary venules and arterioles have not been investigated systematically after complement activation so far, A closed thoracic window was implanted in anesthetized rabbits; leukocytes and red blood cells were stained, and the movement of these cells was measured in superficial pulmonary arterioles, venules and alveolar capillaries using fluorescence video microscopy before and 30 and 60 min after infusion of cobra venom factor (CVF). Erythrocyte velocity and macrohemodynamic conditions did not change after CVF infusion and were not different from the sham-treated controls. The number of sticking leukocytes increased significantly compared to baseline and control: by 150% in arterioles and in venules and by 740% in alveolar capillaries within 60 min after CVF infusion. The width of alveolar septa in vivo was significantly enlarged after CVF infusion, indicating interstitial pulmonary edema. At the end of the experiments, myeloperoxidase activity was higher in the CVF group, showing leukocyte sequestration in the whole organ. It is concluded that complement activation by CVF induces leukocyte sequestration in lung arterioles, venules and alveolar capillaries and leads to mild lung injury

    Effect of refractive index mismatch on multi-photon direct laser writing

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    This work reports how the process of three-dimensional multi-photon direct laser writing (mpDLW) is affected when there is a small mismatch in refractive index between the material being patterned and the medium in which the focusing objective is immersed. Suspended-line microstructures were fabricated by mpDLW in the cross-linkable epoxide SU-8 as a function of focus depth and average incident power. It is found that even a small refractive index contrast of Delta n = +0.08 causes significant variation in feature width and height throughout the depth of the material. In particular, both the width and height of features can either increase or decrease with depth, depending upon how much the average incident laser power exceeds the threshold for writing. Vectorial diffraction theory is used to obtain insight into the origin of the effect and how to compensate for it. We demonstrate that varying the average focused power is a practical means for controlling the variation in feature size with focal depth

    The Ursinus Weekly, November 2, 1953

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    Quartets to hold program Friday, Nov. 6 • Wagner to speak on Founders Day • Juniors to sponsor dance, Penthouse serenade, Nov. 7 • Model S.C. held at Penn State • Fraternities continue rushing week activity • Group production will be given Tuesday night • Thirty-eight accept bids from sororities, Saturday • Dramatic play to be enacted by thespians • Bloodmobile will be at Ursinus, Nov. 3 • Big-little sister party to be held in rec center • SWC visits Salvation Army; Many attend vespers, Sunday • Executive committee elected by frosh to plan for class • Editorials: Rushing can be improved • Needed: Cash! • Letters to the editor • New preceptresses at South, Fircroft, Clamer • Dr. Phillips reads story by O. Wilde • Cornstalk capers is theme of dance presented by sophs • Junior preceptress tells woes and worries of job • Campus landmark views all Ursinus • Fraternities at Ursinus have interesting history • Eleanor Marcon is golf champion • Spirit, skill aid soccer; Team holds .750 record • JVs win 1-0 on Lewis goal • Stadler, Dawkins score as Belles top Swarthmore 4-1 • Merrifield, Price make first All-College • Bears in fourth victory topple strong Wagner, 14-6 • U.C. leads in tourney games • Temple cops four first team slots • Belles win three; Beat Beaver, 4-0 • Bakermen lose to Swarthmore, 6-1https://digitalcommons.ursinus.edu/weekly/1481/thumbnail.jp

    The Ursinus Weekly, October 12, 1953

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    Women\u27s AA plan reception for freshmen • Student teachers discuss problems at doggie roast • Leaders elected by women of Day Study • Academic freedom topic of chats • Deedes to open Forum season with British foreign policy talk • Draft exams scheduled for Nov. 19, Apr. 22 • Pre-med group hears Dr. Benjamin Souders • Student council activity reviewed by reporters: MSGA announces report concerning Student Union; WSGA holds first meeting, social calendar arranged • String quartet to play this Sunday • Tryouts are held for All my sons • IRC will discuss aims of U.S. and Great Britain, Oct. 19 • Fraternities plan receptions as Old Timers\u27 Day highlight • Editorials: Perseverance brings progress; Your ideas in the Weekly ; Observations unlimited • When Ursinus played Penn • Spirit Committee sparks U campus; Outstanding year of \u2753-\u2754 predicted • Ursinus coed receives reply to letter mailed in ocean • Spencer Hand added to staff of Library • About the Belles: Marge Merrifield captains promising hockey team; Numerous veterans, one freshman named to line-up • Danny back at Ursinus • Varsity hockey opens Friday • Bears win opener, 32-14; Lose to Drexel • Soccer team ties Drexel • Gurzynski sees excellent year • Touch football season openshttps://digitalcommons.ursinus.edu/weekly/1478/thumbnail.jp

    Auto-validation of fluorescent primer extension genotyping assay using signal clustering and neural networks

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    BACKGROUND: SNP genotyping typically incorporates a review step to ensure that the genotype calls for a particular SNP are correct. For high-throughput genotyping, such as that provided by the GenomeLab SNPstream(® )instrument from Beckman Coulter, Inc., the manual review used for low-volume genotyping becomes a major bottleneck. The work reported here describes the application of a neural network to automate the review of results. RESULTS: We describe an approach to reviewing the quality of primer extension 2-color fluorescent reactions by clustering optical signals obtained from multiple samples and a single reaction set-up. The method evaluates the quality of the signal clusters from the genotyping results. We developed 64 scores to measure the geometry and position of the signal clusters. The expected signal distribution was represented by a distribution of a 64-component parametric vector obtained by training the two-layer neural network onto a set of 10,968 manually reviewed 2D plots containing the signal clusters. CONCLUSION: The neural network approach described in this paper may be used with results from the GenomeLab SNPstream instrument for high-throughput SNP genotyping. The overall correlation with manual revision was 0.844. The approach can be applied to a quality review of results from other high-throughput fluorescent-based biochemical assays in a high-throughput mode

    Transient receptor potential vanilloid 4 channel deficiency aggravates tubular damage after acute renal ischaemia reperfusion

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    Transient receptor potential vanilloid 4 (TRPV4) cation channels are functional in all renal vascular segments and mediate endothelium-dependent vasorelaxation. Moreover, they are expressed in distinct parts of the tubular system and activated by cell swelling. Ischaemia/reperfusion injury (IRI) is characterized by tubular injury and endothelial dysfunction. Therefore, we hypothesised a putative organ protective role of TRPV4 in acute renal IRI. IRI was induced in TRPV4 deficient (Trpv4 KO) and wild-type (WT) control mice by clipping the left renal pedicle after right-sided nephrectomy. Serum creatinine level was higher in Trpv4 KO mice 6 and 24 hours after ischaemia compared to WT mice. Detailed histological analysis revealed that IRI caused aggravated renal tubular damage in Trpv4 KO mice, especially in the renal cortex. Immunohistological and functional assessment confirmed TRPV4 expression in proximal tubular cells. Furthermore, the tubular damage could be attributed to enhanced necrosis rather than apoptosis. Surprisingly, the percentage of infiltrating granulocytes and macrophages were comparable in IRI-damaged kidneys of Trpv4 KO and WT mice. The present results suggest a renoprotective role of TRPV4 during acute renal IRI. Further studies using cell-specific TRPV4 deficient mice are needed to clarify cellular mechanisms of TRPV4 in IRI

    Pattern and process in Amazon tree turnover, 1976-2001

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    Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests
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