Flight Test Investigation of Propeller Effects on the Static Longitudinal Stability of the E-2C Airplane

A flight test investigation of the E-2C airplane fitted with two different propeller designs – the Hamilton-Sundstrand model 54460-1 and model NP2000 – was conducted to study propeller effects on airplane static longitudinal stability. Test measurements were recorded at predetermined, mission-representative flight conditions for each propeller model while maintaining the remaining component contributions to longitudinal stability constant. Results were compared at similar test conditions to isolate changes in static stability resulting from a change in propeller contribution. Static elevator position neutral points were determined for those test conditions that indicated a definitive change in airplane static stability as a result of changing propeller design. The results of this work indicated that replacing the model 54460-1 with the model NP2000 propeller reduced the stick-fixed static longitudinal stability of the E-2C in the landing approach configuration, causing an approximate 3x change in the slope of elevator deflection versus airspeed and a 2% forward shift of the static neutral point at landing approach airspeeds

A Helly theorem for convexity in graphs

AbstractIt is shown that for chordless path convexity in any graph, the Helly number equals the size of a maximum clique

Transbasin water transfers

Presented at the 2001 USCID water management conference, Transbasin water transfers on June 27-30, 2001 in Denver, Colorado.To view the abstract, please see the full text of the document

Comparing the utilization and cost of health services between veterans experiencing brief and ongoing episodes of housing instability

Housing instability is associated with costly patterns of health and behavioral health service use. However, little prior research has examined patterns of service use associated with higher costs among those experiencing ongoing housing instability. To address this gap, we compared inpatient and outpatient medical and behavioral health service utilization and costs between veterans experiencing brief and ongoing episodes of housing instability. We used data from a brief screening instrument for homelessness and housing instability that has been implemented throughout the US Department of Veterans Affairs (VA) health care system to identify a national sample of veterans experiencing housing instability. Veterans were classified as experiencing either brief or ongoing housing instability, based on two consecutive responses to the instrument, and we used a series of two-part regression models to conduct adjusted comparisons of costs between veterans experiencing brief and ongoing episodes of housing instability. Among 5794 veterans screening positive for housing instability, 4934 (85%) were experiencing brief and 860 (15%) ongoing instability. The average total annual incremental cost associated with ongoing versus brief episodes of housing instability was estimated at $7573, with the bulk of this difference found in inpatient services. Cost differences resulted more from a higher probability of service use among those experiencing ongoing episodes of housing instability than from higher costs among service users. Our findings suggest that VA programmatic efforts aimed at preventing extended episodes of housing instability could potentially result in substantial cost offsets for the VA health care system.This study was supported by funding from the Department of Veterans Affairs (VA) Health Services Research & Development (HSR&D) grant IIR 13-334-3 and from the VA National Center on Homelessness Among Veterans

Cell-matrix interaction in tissue patterning

Abstract only availableIn vivo pattern formation during morphogenesis is dependent upon the migration of cells. Cell movements are directed by the local structure of the surrounding extracellular matrix. It has been shown experimentally that ligament-like straps form in collagen gel due to the local tension created in the matrix by tissue explants [1]. For a comprehensive understanding of this phenomenon, the sprouting behavior of these aggregates was qualitatively studied in six different configurations embedded in a collagen gel. The biological motivation for this study was to observe how the interplay between the collagen matrix, simulating the extracellular matrix, and the cells affect pattern formation in tissues. The understanding of tissue patterning as a result of cell-matrix interaction has important implications for tissue engineering. Spherical aggregates were prepared from Chinese Hamster Ovary Cells as described previously [2]. The six configurations (triangular, square, hexagonal, bulls eye, dodecagon, and two adjacent aggregates) were built by manually placing spherical aggregates into collagen gels. Photographs of the evolving patterns were taken at regular time intervals for one hundred and eighty hours under a phase contrast microscope. Sprouting was delayed until a critical tension was reached in the collagen matrix. Once sprouting began, a clear bias was shown for migration of cells toward other aggregates creating a cellular bridge between aggregates in close proximity. Sprouting occurred toward each aggregate in a specific pattern exhibiting anisotropy due to the depletion of local collagen fibers in areas adjacent to the cellular bridges. In most aggregates, a void in cell sprouting was apparent on either side of the cellular bridge. The large-scale patterns exhibited in this experiment were found to be linked to local cell-matrix interactions. [1] Sawhney, R.K, Howard, J, Slow local movements of collagen fibers by fibroblasts drive the rapid global self-organization of collagen gels. Journal of Cell Biology. Vol 157, 6, 2002, pp. 1083-1091. [2] K. Jakab, A. Neagu, V. Mironov, R.R. Markwald and G. Forgacs. Engineering biological structures of prescribed shape using self-assembling multicellular systems. PNAS, vol. 101, 9, pp. 2864-2869, 2004.NSF-REU Biosystems Modelin

Rurality or distance to care and the risk of homelessness among Afghanistan and Iraq veterans

INTRODUCTION: To date, no studies have examined the relationship of rurality and distance to nearest VA facility to risk of homelessness. METHODS: We examined differences in the rate of homelessness within a year of a Veteran's first encounter with the VA following last military separation based on rurality and distance to the nearest VA facility using multivariable log-binomial regressions. RESULTS: In our cohort of 708,120 Veterans, 73% were determined to have a forwarding address in urban areas, 59.2% and 86.7% lived within 40 miles of the nearest VA medical center (VAMC), respectively. Veterans living in a rural area and those living between 20+ miles away from the nearest VAMC were at a lower risk for homelessness. CONCLUSIONS: Our unique dataset allowed us to explore the relationship between geography and homelessness. These results are important to policy makers in understanding the risk factors for homelessness among Veterans and planning interventions

Role of Physical Mechanisms in Biological Self-Organization

URL:http://link.aps.org/doi/10.1103/PhysRevLett.95.178104 DOI:10.1103/PhysRevLett.95.178104Organs form during morphogenesis, the process that gives rise to specialized biological structures of specific shape and function in early embryonic development. Morphogenesis is under strict genetic control, but shape evolution itself is a physical process. Here we report the results of experimental and modeling biophysical studies on in vitro biological structure formation. Experimentally, by controlling the interaction between cells and their embedding matrices, we were able to build living structures of definite geometry. The experimentally observed shape evolution was reproduced by Monte Carlo simulations, which also shed light on the biophysical basis of the process. Our work suggests a novel way to engineer biological structures of controlled shape.This work was supported by NSF (IBN-0083653; FIBR-0526854) and NASA (NAG2-1611)

The Grizzly, March 4, 1988

Pot of Gold at End of Goal • Variety of Plans Announced by Board • Class of 1988 Works Toward Graduation • Letters: Trashed Campus Disgusts Zimmer; Jamison Brings Stew to Boil; Student Steamed at Noise; Shooting STAR Sends Sparks • Matters Grab Sixth Place Finish • Men Swim to an Impressive Finish • \u27Mer Chicks End on Upbeat Note • Women\u27s Lacrosse Takes Aim at Regaining National Title • Gymnasts ECAC Bound • German Wrestlers to Visit Ursinus College in Tourhttps://digitalcommons.ursinus.edu/grizzlynews/1207/thumbnail.jp