Excavation of Regolith by Impinging Jets of Gas

There are many situations in nature and technology where particulate matter is excavated by a fluid jet. Such a process is often used to excavate soil or to dig wells. Air jets are often used to transport particulate matter such as powders in various industrial processes. Similar situations occur in nature, as when waterfalls scour holes in sand. In other cases, the excavation is unwanted such as when a rocket lands on the sandy or dusty surface of a planet or moon. Recent research into regolith excavation by gas jets has obtained new insights into the physical processes of that excavation, and these may lead to new advances in technology for more efficient fluid-jet excavation processes and for better control of the unwanted excavation effects of landing rockets. This talk will explain the new insights and point to future work supporting lunar exploration

A test of basin-scale acoustic thermometry using a large-aperture vertical array at 3250-km range in the eastern North Pacific Ocean

Author Posting. © Acoustical Society of America, 1999. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 105 (1999): 3185, doi:10.1121/1.424649.Broadband acoustic signals were transmitted during November 1994 from a 75-Hz source suspended near the depth of the sound-channel axis to a 700-m long vertical receiving array approximately 3250 km distant in the eastern North Pacific Ocean. The early part of the arrival pattern consists of raylike wave fronts that are resolvable, identifiable, and stable. The later part of the arrival pattern does not contain identifiable raylike arrivals, due to scattering from internal-wave-induced sound-speed fluctuations. The observed ray travel times differ from ray predictions based on the sound-speed field constructed using nearly concurrent temperature and salinity measurements by more than a priori variability estimates, suggesting that the equation used to compute sound speed requires refinement. The range-averaged oceansound speed can be determined with an uncertainty of about 0.05 m/s from the observed ray travel times together with the time at which the near-axial acoustic reception ends, used as a surrogate for the group delay of adiabatic mode 1. The change in temperature over six days can be estimated with an uncertainty of about 0.006 °C. The sensitivity of the travel times to ocean variability is concentrated near the ocean surface and at the corresponding conjugate depths, because all of the resolved ray arrivals have upper turning depths within a few hundred meters of the surface.This work was supported largely by the Strategic Environmental Research and Development Program through Defense Advanced Research Projects Agency ~DARPA! Grant No. MDA972-93- 1-0003. Additional support was provided at SIO by the Office of Naval Research ~ONR! through Grant No. N00014- 97-1-0258. J. Colosi wishes to acknowledge support from an ONR Young Investigator Award, from the J. Lamar Worzel Assistant Scientist Fund, and from the Penzance Endowed Fund in support of scientific staff at WHOI

Gestational diabetes and pregnancy outcomes - a systematic review of the World Health Organization (WHO) and the International Association of Diabetes in Pregnancy Study Groups (IADPSG) diagnostic criteria

<p>Abstract</p> <p>Background</p> <p>Two criteria based on a 2 h 75 g OGTT are being used for the diagnosis of gestational diabetes (GDM), those recommended over the years by the World Health Organization (WHO), and those recently recommended by the International Association for Diabetes in Pregnancy Study Group (IADPSG), the latter generated in the HAPO study and based on pregnancy outcomes. Our aim is to systematically review the evidence for the associations between GDM (according to these criteria) and adverse outcomes.</p> <p>Methods</p> <p>We searched relevant studies in MEDLINE, EMBASE, LILACS, the Cochrane Library, CINHAL, WHO-Afro library, IMSEAR, EMCAT, IMEMR and WPRIM. We included cohort studies permitting the evaluation of GDM diagnosed by WHO and or IADPSG criteria against adverse maternal and perinatal outcomes in untreated women. Only studies with universal application of a 75 g OGTT were included. Relative risks (RRs) and their 95% confidence intervals (CI) were obtained for each study. We combined study results using a random-effects model. Inconsistency across studies was defined by an inconsistency index (I²) > 50%.</p> <p>Results</p> <p>Data were extracted from eight studies, totaling 44,829 women. Greater risk of adverse outcomes was observed for both diagnostic criteria. When using the WHO criteria, consistent associations were seen for macrosomia (RR = 1.81; 95%CI 1.47-2.22; p < 0.001); large for gestational age (RR = 1.53; 95%CI 1.39-1.69; p < 0.001); perinatal mortality (RR = 1.55; 95% CI 0.88-2.73; p = 0.13); preeclampsia (RR = 1.69; 95%CI 1.31-2.18; p < 0.001); and cesarean delivery (RR = 1.37;95%CI 1.24-1.51; p < 0.001). Less data were available for the IADPSG criteria, and associations were inconsistent across studies (I²≥ 73%). Magnitudes of RRs and their 95%CIs were 1.73 (1.28-2.35; p = 0.001) for large for gestational age; 1.71 (1.38-2.13; p < 0.001) for preeclampsia; and 1.23 (1.01-1.51; p = 0.04) for cesarean delivery. Excluding either the HAPO or the EBDG studies minimally altered these associations, but the RRs seen for the IADPSG criteria were reduced after excluding HAPO.</p> <p>Conclusions</p> <p>The WHO and the IADPSG criteria for GDM identified women at a small increased risk for adverse pregnancy outcomes. Associations were of similar magnitude for both criteria. However, high inconsistency was seen for those with the IADPSG criteria. Full evaluation of the latter in settings other than HAPO requires additional studies.</p

Jet-induced cratering of a granular surface with application to lunar spaceports

The erosion of lunar soil by rocket exhaust plumes is investigated experimentally. This has identified the diffusion-driven flow in the bulk of the sand as an important but previously unrecognized mechanism for erosion dynamics. It has also shown that slow regime cratering is governed by the recirculation of sand in the widening geometry of the crater. Scaling relationships and erosion mechanisms have been characterized in detail for the slow regime. The diffusion-driven flow occurs in both slow and fast regime cratering. Because diffusion-driven flow had been omitted from the lunar erosion theory and from the pressure cratering theory of the Apollo and Viking era, those theories cannot be entirely correct.Comment: 13 pages, link to published version: http://cedb.asce.org/cgi/WWWdisplay.cgi?090000

VAST: An ASKAP Survey for Variables and Slow Transients

The Australian Square Kilometre Array Pathfinder (ASKAP) will give us an unprecedented opportunity to investigate the transient sky at radio wavelengths. In this paper we present VAST, an ASKAP survey for Variables and Slow Transients. VAST will exploit the wide-field survey capabilities of ASKAP to enable the discovery and investigation of variable and transient phenomena from the local to the cosmological, including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, interstellar scintillation, radio supernovae and orphan afterglows of gamma ray bursts. In addition, it will allow us to probe unexplored regions of parameter space where new classes of transient sources may be detected. In this paper we review the known radio transient and variable populations and the current results from blind radio surveys. We outline a comprehensive program based on a multi-tiered survey strategy to characterise the radio transient sky through detection and monitoring of transient and variable sources on the ASKAP imaging timescales of five seconds and greater. We also present an analysis of the expected source populations that we will be able to detect with VAST.Comment: 29 pages, 8 figures. Submitted for publication in Pub. Astron. Soc. Australi

Detection, Estimation, and Modulation Theory

Contains research objectives and summary of research on four research projects.Joint Services Electronics Program (Contract DAAB07-75-C-1346)Woods Hole Oceanographic Institution Purchase Order 455

FGF Signaling Pathway in the Developing Chick Lung: Expression and Inhibition Studies

Background: Fibroblast growth factors (FGF) are essential key players during embryonic development. Through their specific cognate receptors (FGFR) they activate intracellular cascades, finely regulated by modulators such as Sprouty. Several FGF ligands (FGF1, 2, 7, 9, 10 and 18) signaling through the four known FGFRs, have been implicated in lung morphogenesis. Although much is known about mammalian lung, so far, the avian model has not been explored for lung studies. Methodology/Principal Findings: In this study we provide the first description of fgf10, fgfr1-4 and spry2 expression patterns in early stages of chick lung development by in situ hybridization and observe that they are expressed similarly to their mammalian counterparts. Furthermore, aiming to determine a role for FGF signaling in chick lung development, in vitro FGFR inhibition studies were performed. Lung explants treated with an FGF receptor antagonist (SU5402) presented an impairment of secondary branch formation after 48 h of culture; moreover, abnormal lung growth with a cystic appearance of secondary bronchi and reduction of the mesenchymal tissue was observed. Branching and morphometric analysis of lung explants confirmed that FGFR inhibition impaired branching morphogenesis and induced a significant reduction of the mesenchyme. Conclusions/Significance: This work demonstrates that FGFRs are essential for the epithelial-mesenchymal interactions tha

Localized Fetomaternal Hyperglycemia: Spatial and Kinetic Definition by Positron Emission Tomography

to isolated hyperglycemia in the pregnant rat. mg/dL) localized to the left uterine artery was sustained for at least 48 hours while maternal euglycemia was maintained. fetal effects of isolated hyperglycemia. Broadly, this approach can be extended to study a variety of maternal-sided perturbations suspected to directly affect fetal health

B7-H4 Treatment of T Cells Inhibits ERK, JNK, p38, and AKT Activation

B7-H4 is a newly identified B7 homolog that plays an important role in maintaining T-cell homeostasis by inhibiting T-cell proliferation and lymphokine-secretion. In this study, we investigated the signal transduction pathways inhibited by B7-H4 engagement in mouse T cells. We found that treatment of CD3+ T cells with a B7-H4.Ig fusion protein inhibits anti-CD3 elicited T-cell receptor (TCR)/CD28 signaling events, including phosphorylation of the MAP kinases, ERK, p38, and JNK. B7-H4.Ig treatment also inhibited the phosphorylation of AKT kinase and impaired its kinase activity as assessed by the phosphorylation of its endogenous substrate GSK-3. Expression of IL-2 is also reduced by B7-H4. In contrast, the phosphorylation state of the TCR proximal tyrosine kinases ZAP70 and lymphocyte-specific protein tyrosine kinase (LCK) are not affected by B7-H4 ligation. These results indicate that B7-H4 inhibits T-cell proliferation and IL-2 production through interfering with activation of ERK, JNK, and AKT, but not of ZAP70 or LCK