Investigation of the effects of topography on Colorado Front Range winter storms, An

Fall, 1991.Includes bibliographical references.Sponsored by ARO DAAL03-86-K-0175.Sponsored by NSF ATM-9017849

CAUSES OF SIMULTANEOUS LEE AND UPWIND RECORD SNOWFALL AND EXTRAORDINARY SNOWFALL VARIATION IN A ROCKY MOUNTAIN BLIZZARD

We describe our investigation of an extreme snowfall event in the Colorado Rocky Mountains during Mar 2003. This event was characterized by extraordinary micro-scale snowfall variability and record snowfall both upwind and in the lee of the 3000 m north-south oriented barrier. We utilize observational analysis and numerical sensitivity tests with the MM5 mesoscale model to test our hypotheses. Stunning micro-scale snowfall variability observed in-situ and visualized by satellite is found to be a consequence of local terrain-induced warming and reduced microphysical efficiency and the amplified influence of this effect due to the relatively warm temperatures accompanying this storm. Record snowfall (2 m) downwind of the barrier simultaneous with record snowfall (2.2 m) upwind is very rare climatologically, and is found to be caused, in effect, by the exceptional synoptic dimensions of this storm. A rare combination of, 1) moist, deep inflow, 2) a reversal of the mid-latitude westerlies to the tropopause overlying a well-developed barrier jet for an extended period and, 3) static stability favoring cross-barrier microphysical production and hydrometeor transport rather than drying, are implicated

Spatial Grain Size Sorting in Eolian Ripples and Estimation of Wind Conditions on Planetary Surfaces: Application to Meridiani Planum, Mars

The landscape seen by the Mars Exploration Rover (MER) Opportunity at Meridiani Planum is dominated by eolian (wind-blown) ripples with concentrated surface lags of hematitic spherules and fragments. These ripples exhibit profound spatial grain size sorting, with well-sorted coarse-grained crests and poorly sorted, generally finer-grained troughs. These ripples were the most common bed form encountered by Opportunity in its traverse from Eagle Crater to Endurance Crater. Field measurements from White Sands National Monument, New Mexico, show that such coarse-grained ripples form by the different transport modes of coarse- and fine-grain fractions. On the basis of our field study, and simple theoretical and experimental considerations, we show how surface deposits of coarse-grained ripples can be used to place tight constraints on formative wind conditions on planetary surfaces. Activation of Meridiani Planum coarse-grained ripples requires a wind velocity of 70 m/s (at a reference elevation of 1 m above the bed). From images by the Mars Orbiter Camera (MOC) of reversing dust streaks, we estimate that modern surface winds reach a velocity of at least 40 m/s and hence may occasionally activate these ripples. The presence of hematite at Meridiani Planum is ultimately related to formation of concretions during aqueous diagenesis in groundwater environments; however, the eolian concentration of these durable particles may have led to the recognition from orbit of this environmentally significant landing site

CAUSES OF SIMULTANEOUS LEE AND UPWIND RECORD SNOWFALL AND EXTRAORDINARY SNOWFALL VARIATION IN A ROCKY MOUNTAIN BLIZZARD

We describe our investigation of an extreme snowfall event in the Colorado Rocky Mountains during Mar 2003. This event was characterized by extraordinary micro-scale snowfall variability and record snowfall both upwind and in the lee of the 3000 m north-south oriented barrier. We utilize observational analysis and numerical sensitivity tests with the MM5 mesoscale model to test our hypotheses. Stunning micro-scale snowfall variability observed in-situ and visualized by satellite is found to be a consequence of local terrain-induced warming and reduced microphysical efficiency and the amplified influence of this effect due to the relatively warm temperatures accompanying this storm. Record snowfall (2 m) downwind of the barrier simultaneous with record snowfall (2.2 m) upwind is very rare climatologically, and is found to be caused, in effect, by the exceptional synoptic dimensions of this storm. A rare combination of, 1) moist, deep inflow, 2) a reversal of the mid-latitude westerlies to the tropopause overlying a well-developed barrier jet for an extended period and, 3) static stability favoring cross-barrier microphysical production and hydrometeor transport rather than drying, are implicated

Vertical integration and firm boundaries : the evidence

Since Ronald H. Coase's (1937) seminal paper, a rich set of theories has been developed that deal with firm boundaries in vertical or input–output structures. In the last twenty-five years, empirical evidence that can shed light on those theories also has been accumulating. We review the findings of empirical studies that have addressed two main interrelated questions: First, what types of transactions are best brought within the firm and, second, what are the consequences of vertical integration decisions for economic outcomes such as prices, quantities, investment, and profits. Throughout, we highlight areas of potential cross-fertilization and promising areas for future work

Simple cosmological de Sitter solutions on dS4×Y6_4 \times Y_6 spaces

Explicit time-dependent solutions of the 10D vacuum Einstein equations are found for which spacetime is compactified on six-dimensional warped spaces. We explicitly work out an example where the internal manifold is a six-dimensional generalized space having positive, negative or zero scalar curvature, whose base can be a five-sphere $S^5$ or an Einstein space $T^{1,1}=(S^2\times S^2)\rtimes S^1$. In this paper, inflationary de Sitter solutions are found just by solving the 10D vacuum Einstein equations. Our results further show that the limitation with warped models studied to date has arisen partly from an oversimplification of the 10D metric ansatz. We also give some explicit examples of a non-singular warped compactification on de Sitter space dS$_4$.Comment: 15 pages, no figures; matches published versio

ACCF/AHA 2011 Expert Consensus Document on Hypertension in the Elderly: A Report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents

This document was written with the intent to be a complete reference at the time of publication on the topic of managing hypertension in the elderly. This document has been developed as an expert consensus document by the American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA), in collaboration with the American Academy of Neurology (AAN), the American College of Physicians (ACP), the American Geriatrics Society (AGS), the American Society of Hypertension (ASH), the American Society of Nephrology (ASN), the American Society for Preventive Cardiology (ASPC), the Association of Black Cardiologists (ABC), and the European Society of Hypertension (ESH). Expert consensus documents are intended to inform practitioners, payers, and other interested parties of the opinion of ACCF and document cosponsors concerning evolving areas of clinical practice and/or technologies that are widely available or new to the practice community

ACCF/AHA 2011 Expert Consensus Document on Hypertension in the Elderly: A Report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents

This document was written with the intent to be a complete reference at the time of publication on the topic of managing hypertension in the elderly. This document has been developed as an expert consensus document by the American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA), in collaboration with the American Academy of Neurology (AAN), the American College of Physicians (ACP), the American Geriatrics Society (AGS), the American Society of Hypertension (ASH), the American Society of Nephrology (ASN), the American Society for Preventive Cardiology (ASPC), the Association of Black Cardiologists (ABC), and the European Society of Hypertension (ESH). Expert consensus documents are intended to inform practitioners, payers, and other interested parties of the opinion of ACCF and document cosponsors concerning evolving areas of clinical practice and/or technologies that are widely available or new to the practice community

Early High-Dose Vitamin D3 for Critically Ill, Vitamin D-Deficient Patients

BACKGROUND: Vitamin D deficiency is a common, potentially reversible contributor to morbidity and mortality among critically ill patients. The potential benefits of vitamin D supplementation in acute critical illness require further study. METHODS: We conducted a randomized, double-blind, placebo-controlled, phase 3 trial of early vitamin D3 supplementation in critically ill, vitamin D-deficient patients who were at high risk for death. Randomization occurred within 12 hours after the decision to admit the patient to an intensive care unit. Eligible patients received a single enteral dose of 540,000 IU of vitamin D3 or matched placebo. The primary end point was 90-day all-cause, all-location mortality. RESULTS: A total of 1360 patients were found to be vitamin D-deficient during point-of-care screening and underwent randomization. Of these patients, 1078 had baseline vitamin D deficiency (25-hydroxyvitamin D level,[50 nmol per liter]) confirmed by subsequent testing and were included in the primary analysis population. The mean day 3 level of 25-hydroxyvitamin D was 46.9±23.2 ng per milliliter (117±58 nmol per liter) in the vitamin D group and 11.4±5.6 ng per milliliter (28±14 nmol per liter) in the placebo group (difference, 35.5 ng per milliliter; 95% confidence interval [CI], 31.5 to 39.6). The 90-day mortality was 23.5% in the vitamin D group (125 of 531 patients) and 20.6% in the placebo group (109 of 528 patients) (difference, 2.9 percentage points; 95% CI, -2.1 to 7.9; P = 0.26). There were no clinically important differences between the groups with respect to secondary clinical, physiological, or safety end points. The severity of vitamin D deficiency at baseline did not affect the association between the treatment assignment and mortality. CONCLUSIONS: Early administration of high-dose enteral vitamin D3 did not provide an advantage over placebo with respect to 90-day mortality or other, nonfatal outcomes among critically ill, vitamin D-deficient patients. METHODS: We conducted a randomized, double-blind, placebo-controlled, phase 3 trial of early vitamin D3 supplementation in critically ill, vitamin D-deficient patients who were at high risk for death. Randomization occurred within 12 hours after the decision to admit the patient to an intensive care unit. Eligible patients received a single enteral dose of 540,000 IU of vitamin D3 or matched placebo. The primary end point was 90-day all-cause, all-location mortality

The genomic landscape of rapid repeated evolutionary adaptation to toxic pollution in wild fish

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Science 354 (2016): 1305-1308, doi:10.1126/science.aah4993.Atlantic killifish populations have rapidly adapted to normally lethal levels of pollution in four urban estuaries. Through analysis of 384 whole killifish genome sequences and comparative transcriptomics in four pairs of sensitive and tolerant populations, we identify the aryl hydrocarbon receptor-based signaling pathway as a shared target of selection. This suggests evolutionary constraint on adaptive solutions to complex toxicant mixtures at each site. However, distinct molecular variants apparently contribute to adaptive pathway modification among tolerant populations. Selection also targets other toxicity-mediating genes, and genes of connected signaling pathways, indicating complex tolerance phenotypes and potentially compensatory adaptations. Molecular changes are consistent with selection on standing genetic variation. In killifish high nucleotide diversity has likely been a crucial substrate for selective sweeps to propel rapid adaptation.Primary support was from the United States National Science Foundation (collaborative research grants DEB-1265282, DEB-1120512, DEB- 1120013, DEB-1120263, DEB-1120333, DEB-1120398 to JKC, DLC, MEH, SIK, MFO, JRS, WW, and AW). Further support was provided by the National Institutes of Environmental Health Sciences (1R01ES021934-01 to AW; P42ES007381 to MEH; R01ES019324 to JRS), and the National Science Foundation (OCE-1314567 to AW). BC was supported by the Postdoctoral Research Program at the US EPA administered by the Oak Ridge Institute for Science and Education (Agreement DW92429801)