Space shuttle: Aerodynamic characteristics of the NASA-MSC S-4 orbiter in cruise and landing

Low speed wind tunnel test to define space shuttle model cruise and landing aerodynamic characteristic

Spatiotemporal profiles of ultrafine particles differ from other traffic-related air pollutants : lessons from long-term measurements at fixed sites and mobile monitoring

Peer reviewe

Stubble Height Effects on Limpograss Pasture Characteristics and Performance of Beef Heifers

Limpograss (Hemarthria altissima [Poir.] Stapf. & C.E. Hubb.) is a C4 species used in Florida beef production systems because of its cool-season growth, persistence on poorly drained soils, and high yield and digestibility. Animal performance on limpograss pastures, however, has been limited by low herbage crude protein (CP). This study evaluated the effect of canopy height of limpograss pastures and N supplementation of grazing cattle on sward characteristics and weight gain and blood urea N (BUN) concentration of yearling beef heifers. Under continuous stocking, six treatments were imposed that included all combinations of three stubble heights (20, 40, and 60 cm) and two N-supplement levels (S, supplemented; NS, unsupplemented). During 1998 and 1999, treatments were replicated twice and arranged in a completely randomized design. Seasonal (84 d) daily gains from heifers grazing limpograss pastures were not different (p= 0.25) between the two years and averaged 522 g. For the intermediate stubble, 40-cm, there was no effect of supplementation on daily gains (P= 0.1), but daily gain increased 40 and 70% due to supplementation (P \u3c 0.01) of heifers on pastures grazed to 20 and 60 cm, respectively. These data show that limpograss stubble height has an impact on pasture nutritive value affecting daily gains. Stubble height of approximately 40 cm seems to provide optimum gains of animals receiving no N supplement on continuously stocked pastures

Estrogen signaling in the cardiovascular system

Estrogen exerts complex biological effects through the two isoforms of estrogen receptors (ERs): ERα and ERβ. Whether through alteration of gene expression or rapid, plasma membrane-localized signaling to non-transcriptional actions, estrogen-activated ERs have significant implications in cardiovascular physiology. 17-β-estradiol (E2) generally has a protective property on the vasculature. Estrogen treatment is anti-atherogenic, protecting injured endothelial surfaces and lowering LDL oxidation in animal models. Increased NO production stimulated by E2 results in vasodilation of the coronary vascular bed, and involves rapid activation of phosphotidylinositol-3 kinase (PI3K)/Akt signaling to eNOS in carotid and femoral arteries. Both isoforms of ERs impact various vascular functions, modulating ion channel integrity, mitigating the response to arterial injury, inducing vasodilation, and preventing development of hypertension in animal models. In addition to reducing afterload by vasodilation, ERs have a direct antihypertrophic effect on the myocardium. E2-activated ERs (E2/ER) antagonize the hypertrophic pathway induced by vasoactive peptides such as angiotensin II by activating PI3K, subsequent MICIP gene expression, leading to the inhibition of calcineurin activity and the induction of hypertrophic genes. In models of ischemia-reperfusion, E2/ER is antiapoptotic for cardiomyocytes, exerting the protective actions via PI3K and p38 MAP kinases and suppressing the generation of reactive oxygen species. In sum, E2-activated ERs consistently and positively modulate multiple aspects of the cardiovascular system

Carbon Nanotubes and Graphene as Additives in 3D Printing

3D printing is a revolutionary technology for the consumer and industrial markets. As the technology for 3D printing has expanded, the need for multi-materials that support fused deposition modeling and other forms of additive manufacturing is increasing. 3D printing filaments infused with carbon nanotubes and graphene are now commercially available, with the promise of producing conductive composites. This chapter explores some of the research, products, and challenges involved in bringing the next generation of functional printing materials to the consumer market

Effect of Storage Time and Temperature on Recovery of \u3ci\u3eSynergistes jonesii\u3c/i\u3e from Rumen Fluid and Feces

Synergistes jonesii is a rumen bacterium that degrades 3,4-dihydroxypyridine (3,4 DHP), the toxic breakdown product of mimosine in leucaena (Leucaena leucocephala). Fecal culture is the most practical way to determine S. jonesii presence in zoological ruminants, particularly if feces can be collected from night penning facilities. Fresh rumen fluid and fecal or fecal slurry (sheep [Ovis spp.] only, 1:4 wt to vol. feces and culture media) from cattle (Bos spp.) and sheep, known to be colonized by S. jonesii, were subjected various storage times (0, 6, 12, and 24 h) and temperatures (5, 23, and 38 oC). Samples were inoculated into a culture medium that contained 3,4 DHP. In general, storage temperature had no affect on detection frequency. Regardless of animal species, detection of S. jonesii was higher (P=0.001) in rumen (97%) than in fecal (40%) samples and level of detection in rumen samples was relatively unaffected by storage time. Detection frequency was similar for both fecal sample types regardless of time (34% fecal vs. 29% fecal slurry). For all fecal samples, detection frequency generally exhibited a linear decline (P=0.01) with time. This study showed that it will be important to collect fresh fecal samples (\u3c 6-h old) from night penning facilities, and because detection levels were low in fecal material, fecal assay would be most accurate on a whole herd rather than an individual animal basis

Estimating source-attributable health impacts of ambient fine particulate matter exposure: global premature mortality from surface transportation emissions in 2005

Exposure to ambient fine particular matter (PM2.5) was responsible for 3.2 million premature deaths in 2010 and is among the top ten leading risk factors for early death. Surface transportation is a significant global source of PM2.5 emissions and a target for new actions. The objective of this study is to estimate the global and national health burden of ambient PM2.5 exposure attributable to surface transportation emissions. This share of health burden is called the transportation attributable fraction (TAF), and is assumed equal to the proportional decrease in modeled ambient particulate matter concentrations when surface transportation emissions are removed. National population-weighted TAFs for 190 countries are modeled for 2005 using the MOZART-4 global chemical transport model. Changes in annual average concentration of PM2.5 at 0.5 × 0.67 degree horizontal resolution are based on a global emissions inventory and removal of all surface transportation emissions. Global population-weighted average TAF was 8.5 percent or 1.75 μg m−3 in 2005. Approximately 242 000 annual premature deaths were attributable to surface transportation emissions, dominated by China, the United States, the European Union and India. This application of TAF allows future Global Burden of Disease studies to estimate the sector-specific burden of ambient PM2.5 exposure. Additional research is needed to capture intraurban variations in emissions and exposure, and to broaden the range of health effects considered, including the effects of other pollutants

SR-B1 drives endothelial cell LDL transcytosis via DOCK4 to promote atherosclerosis

© 2019, The Author(s), under exclusive licence to Springer Nature Limited. Atherosclerosis, which underlies life-threatening cardiovascular disorders such as myocardial infarction and stroke1, is initiated by passage of low-density lipoprotein (LDL) cholesterol into the artery wall and its engulfment by macrophages, which leads to foam cell formation and lesion development2,3. It is unclear how circulating LDL enters the artery wall to instigate atherosclerosis. Here we show in mice that scavenger receptor class B type 1 (SR-B1) in endothelial cells mediates the delivery of LDL into arteries and its accumulation by artery wall macrophages, thereby promoting atherosclerosis. LDL particles are colocalized with SR-B1 in endothelial cell intracellular vesicles in vivo, and transcytosis of LDL across endothelial monolayers requires its direct binding to SR-B1 and an eight-amino-acid cytoplasmic domain of the receptor that recruits the guanine nucleotide exchange factor dedicator of cytokinesis 4 (DOCK4)4. DOCK4 promotes internalization of SR-B1 and transport of LDL by coupling the binding of LDL to SR-B1 with activation of RAC1. The expression of SR-B1 and DOCK4 is increased in atherosclerosis-prone regions of the mouse aorta before lesion formation, and in human atherosclerotic arteries when compared with normal arteries. These findings challenge the long-held concept that atherogenesis involves passive movement of LDL across a compromised endothelial barrier. Interventions that inhibit the endothelial delivery of LDL into artery walls may represent a new therapeutic category in the battle against cardiovascular disease

Effects of anharmonic strain on phase stability of epitaxial films and superlattices: applications to noble metals

Epitaxial strain energies of epitaxial films and bulk superlattices are studied via first-principles total energy calculations using the local-density approximation. Anharmonic effects due to large lattice mismatch, beyond the reach of the harmonic elasticity theory, are found to be very important in Cu/Au (lattice mismatch 12%), Cu/Ag (12%) and Ni/Au (15%). We find that is the elastically soft direction for biaxial expansion of Cu and Ni, but it is for large biaxial compression of Cu, Ag, and Au. The stability of superlattices is discussed in terms of the coherency strain and interfacial energies. We find that in phase-separating systems such as Cu-Ag the superlattice formation energies decrease with superlattice period, and the interfacial energy is positive. Superlattices are formed easiest on (001) and hardest on (111) substrates. For ordering systems, such as Cu-Au and Ag-Au, the formation energy of superlattices increases with period, and interfacial energies are negative. These superlattices are formed easiest on (001) or (110) and hardest on (111) substrates. For Ni-Au we find a hybrid behavior: superlattices along and like in phase-separating systems, while for they behave like in ordering systems. Finally, recent experimental results on epitaxial stabilization of disordered Ni-Au and Cu-Ag alloys, immiscible in the bulk form, are explained in terms of destabilization of the phase separated state due to lattice mismatch between the substrate and constituents.Comment: RevTeX galley format, 16 pages, includes 9 EPS figures, to appear in Physical Review