The Role of Ions in Irradiated Astrophysical O\u3csub\u3e2\u3c/sub\u3e Ice

Cosmic ices contain ions produced by irradiation from cosmic rays and UVphotons, yet solid-phase ion-ice reactions are currently ignored in all astrochemical models, even though gas-phase ion-molecule reactions are arguably the single-most important class of reactions in astrochemistry. Thus, developing a model that includes solid-phase ion-ice reactions is essential to accurately model interstellar ice chemistry, especially given the recent launch of the James Webb Space Telescope. To fill this gap, we have compiled a solid-phase chemical network for use in a rate-based irradiated ice astrochemical model which, for the first time, includes ionic species produced via the photoionization of the ice. Using this network, we simulated the photo-irradiation of a pure O2 ice and constrained the photolysis rates through direct comparison with experimental data. The fit of the model is in qualitative agreement with the experimental findings to give a general idea of what ionic chemistry occurs in irradiated ices. Our preliminary results indicate that ion-neutral chemistry contributes significantly more to solid phase reactivity than previously assumed. As in the gas-phase, solid-phase ion-ice reactions are very efficient and, indeed, become the dominant formation routes for the neutral species in our network

Design and performance of an adaptive MFSK HF terminal.

The paper describes the implementation of a real-time integrated modem/codec system for long-range radio communications, e.g. HF. The system has been developed by the Hull-Lancaster Communication Research Group. The system has been implemented using a proprietary DSP-based architecture which uses the AT&T DSP32C digital signal processor and the transmission format comprises MFSK modulation combined with RS coding. The main features of the system are described and results from on-air HF trials over both static and aeromobile channels are presente

Folding and insertion thermodynamics of the transmembrane WALP peptide

The anchor of most integral membrane proteins consists of one or several helices spanning the lipid bilayer. The WALP peptide, GWW(LA)$_n$(L)WWA, is a common model helix to study the fundamentals of protein insertion and folding, as well as helix-helix association in the membrane. Its structural properties have been illuminated in a large number of experimental and simulation studies. In this combined coarse-grained and atomistic simulation study, we probe the thermodynamics of a single WALP peptide, focusing on both the insertion across the water-membrane interface, as well as folding in both water and a membrane. The potential of mean force characterizing the peptide's insertion into the membrane shows qualitatively similar behavior across peptides and three force fields. However, the Martini force field exhibits a pronounced secondary minimum for an adsorbed interfacial state, which may even become the global minimum---in contrast to both atomistic simulations and the alternative PLUM force field. Even though the two coarse-grained models reproduce the free energy of insertion of individual amino acids side chains, they both underestimate its corresponding value for the full peptide (as compared with atomistic simulations), hinting at cooperative physics beyond the residue level. Folding of WALP in the two environments indicates the helix as the most stable structure, though with different relative stabilities and chain-length dependence.Comment: 12 pages, 5 figure

Economic Stress and the Safety Net: A Health Center Update

Federally funded health centers provided care to 11.3 million patients in 2002, the vast majority of whom were either uninsured (39%) or covered by Medicaid (34%). This paper provides new information on the demographic profile of health center patients and the revenue sources available for financing their care, including recent increases in federal discretionary funding. It examines the impact of the recent economic downturn on health centers in selected communities, exploring the effect of elevated unemployment levels among lower wage workers, declining private health insurance coverage, and widespread state cutbacks in Medicaid – the single most important source of health center financing

A tool for assessing error in digital elevation models from a user’s perspective

A Digital Elevation Model (DEM) is a representation of geographic reality. The elevations recorded within DEMs have been shown to contain errors pertaining to sampling, measurement and interpolation (Fisher, 1998). Even a small amount of elevation error can greatly affect derivative products (Holmes et al., 2000). This can potentially have a significant impact on the application of DEMs in Geographical Information Systems (GIS) where first and second order derivatives are considered

Financial health indicators: an analysis of financial statement information to determine the financial health of DoD contractors

MBA Professional ReportPrior to awarding a contract, government contracting officers must be able to determine the financial health of prospective contractors. In fact, according to the Federal Acquisition Regulation (FAR) 9.104- 1(a), the very first general requirement to being considered a responsible prospective contractor is to show adequate financial resources to perform the contract or the ability to obtain financing. The purpose of this research is to identify a financial assessment framework that could assist DOD contracting officers with determining the financial health of potential DOD contractors. This research study may help DOD contracting officers determine the financial health of potential contractors prior to awarding a contract. The findings of this study provide a recommended framework that a contracting officer could follow in order to assess the financial health of a prospective contractor. The framework includes a ratio analysis using selected ratios compiled by this study, as well as a comparative analysis using industry average driven data. The framework also incorporates horizontal and vertical analyses, as well as bankruptcy and fraud analyses. The financial assessment framework created in this study is a comprehensive financial health assessment tool that can be utilized by DOD contracting officers.http://archive.org/details/financialhealthi1094551703Lieutenant Commander, United States NavyLieutenant, United States NavyLieutenant, United States NavyApproved for public release; distribution is unlimited

Sarpa salpa herbivory on shallow reaches of Posidonia oceanica beds

El herbivorismo de Sarpa salpa en los tramos someros de los lechos de Posidonia oceanica En el presente artículo analizamos la variabilidad temporal y espacial en pequeña escala de la actividad de alimentación del pez herbívoro Sarpa salpa en los lechos someros de la pradera submarina de clima templado Posidonia oceanica. La intensidad del herbivorismo expresada como el porcentaje de superficie foliar mordida por el pez fue superior en septiembre de 2006 que en febrero de 2007, y a una profundidad de 0,5 m que de 1,5 m durante los dos períodos de muestreo. Todos los individuos de S. salpa que se alimentaban en las zonas someras estudiadas eran juveniles y el tamaño de mordedura se situaba entre 0,03 y 0,62 cm2. Los juveniles que se alimentaban a 1,5 m de profundidad fueron más grandes en febrero de 2007 que en septiembre de 2006, tal como ponen de relieve las diferencias significativas existentes en el tamaño medio de mordedura por haz. No obstante, los juveniles más grandes que se alimentaban a 1,5 m de profundidad en febrero de 2007 no parecían alimentarse con tanta frecuencia como los juveniles comparativamente más pequeños, que lo hacían a la misma profundidad en septiembre de 2006, tal como sugieren las diferencias significativas halladas en el número de mordeduras por haz. Asimismo, el número de mordeduras por haz fue inferior a 1,5 m de profundidad que a 0,5 m en febrero de 2007, si bien el tamaño medio de las mordeduras no difería en medida significativa entre las dos profundidades en aquel período de muestreo. En general, los juveniles de S. salpa no elegían un intervalo de edad concreto de las hojas a la hora de alimentarse en los lugares del estudio, a pesar de que los juveniles que se alimentaban a 1,5 m de profundidad en septiembre de 2006 parecían elegir hojas de edad mediana. Los peces no mostraron preferencia por las hojas con mayor cobertura de epífitos. Estos resultados muestran que la actividad de alimentación de los juveniles de S. salpa en los tramos someros de las praderas de P. oceanica puede variar con el tiempo y con pequeños cambios de profundidad, lo que a su vez puede afectar a la intensidad general del herbivorismo sobre las praderas submarinas.Here, we examined the temporal and small–scale spatial variability of grazing by the herbivorous fish Sarpa salpa on shallow beds of the temperate seagrass Posidonia oceanica. Herbivory intensity expressed as the percent of leaf area taken by fish bites was higher in September 2006 than in February 2007, and at 0.5 m than at 1.5 m during both sampling times. All S. salpa feeding at the shallow locations studied were juveniles, with bite sizes ranging from 0.03 to 0.62 cm2. Juveniles feeding at 1.5 m were larger in February 2007 than in September 2006, as evidenced by significant differences in mean bite size per shoot. However, the larger juveniles feeding at 1.5 m in February 2007 did not appear to feed as frequently as the comparatively smaller juveniles feeding at the same depth in September 2006, as suggested by significant differences in number of bites per shoot. The number of bites per shoot was also lower at 1.5 m than at 0.5 m in February 2007, although mean bite size did not differ significantly between the two depths at that sampling time. In general S. salpa juveniles did not select a particular range of leaf ages when feeding in the study locations, although the juveniles feeding at 1.5 m in September 2006 appeared to select mid–aged leaves. Fish did not show a preference for more epiphytized leaves. These results show that grazing activity by S. salpa juveniles in shallow reaches of P. oceanica meadows may vary temporally and across small changes in depth, which in turn may affect the overall intensity of herbivory on the seagrass.El herbivorismo de Sarpa salpa en los tramos someros de los lechos de Posidonia oceanica En el presente artículo analizamos la variabilidad temporal y espacial en pequeña escala de la actividad de alimentación del pez herbívoro Sarpa salpa en los lechos someros de la pradera submarina de clima templado Posidonia oceanica. La intensidad del herbivorismo expresada como el porcentaje de superficie foliar mordida por el pez fue superior en septiembre de 2006 que en febrero de 2007, y a una profundidad de 0,5 m que de 1,5 m durante los dos períodos de muestreo. Todos los individuos de S. salpa que se alimentaban en las zonas someras estudiadas eran juveniles y el tamaño de mordedura se situaba entre 0,03 y 0,62 cm2. Los juveniles que se alimentaban a 1,5 m de profundidad fueron más grandes en febrero de 2007 que en septiembre de 2006, tal como ponen de relieve las diferencias significativas existentes en el tamaño medio de mordedura por haz. No obstante, los juveniles más grandes que se alimentaban a 1,5 m de profundidad en febrero de 2007 no parecían alimentarse con tanta frecuencia como los juveniles comparativamente más pequeños, que lo hacían a la misma profundidad en septiembre de 2006, tal como sugieren las diferencias significativas halladas en el número de mordeduras por haz. Asimismo, el número de mordeduras por haz fue inferior a 1,5 m de profundidad que a 0,5 m en febrero de 2007, si bien el tamaño medio de las mordeduras no difería en medida significativa entre las dos profundidades en aquel período de muestreo. En general, los juveniles de S. salpa no elegían un intervalo de edad concreto de las hojas a la hora de alimentarse en los lugares del estudio, a pesar de que los juveniles que se alimentaban a 1,5 m de profundidad en septiembre de 2006 parecían elegir hojas de edad mediana. Los peces no mostraron preferencia por las hojas con mayor cobertura de epífitos. Estos resultados muestran que la actividad de alimentación de los juveniles de S. salpa en los tramos someros de las praderas de P. oceanica puede variar con el tiempo y con pequeños cambios de profundidad, lo que a su vez puede afectar a la intensidad general del herbivorismo sobre las praderas submarinas

Role of Vascular Endothelial Growth Factor in Bone Marrow Stromal Cell Modulation of Endothelial Cells

One of the fundamental principles that underlies tissue-engineering strategies using cell transplantation is that a newly formed tissue must acquire and maintain sufficient vascularization in order to support its growth. Enhancing angiogenesis through delivery of growth factors is one approach to establishing a vascular network to these tissues. In this study, we tested the potential of bone marrow stromal cells (BMSCs) to modulate the growth and differentiation activities of blood vessel precursors, endothelial cells (ECs), by their secretion of soluble angiogenic factors. The growth and differentiation of cultured ECs were enhanced in response to exposure to BMSC conditioned medium (CM). Enzyme-linked immunosorbent assays demonstrated that both mouse and human BMSCs secreted significant quantities of vascular endothelial growth factor (VEGF) (2.4-3.1 ng/106 cells per day). Furthermore, eliminating the activity of BMSC-secreted VEGF with blocking antibodies completely blocked the CM effects on cultured ECs. These data demonstrate that human BMSCs secrete sufficient quantities of VEGF to enhance survival and differentiation of endothelial cells in vitro, and suggest they may be capable of directly orchestrating angiogenesis in vivo.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63256/1/107632703762687573.pd

Subcutaneous : the life experience of African American transsexual college students

Includes bibliographical references (pages [77]-86).The purpose of this study is to explore the experiences of African American transgender college students. The study proceeds within the context of discussing external factors that might define these students’ experiences, such as the church and/or religious affiliation and the family. The impact of the family and the church, which are to a great extent highly important in the African American community, helps to begin to reveal the transsexual experience from an African American perspective. Also discussed are masculinity and gender-role issues and the influence of those two constructs on the gender identity development of African American men.Ed.D. (Doctor of Education