Characteristics of 20th century drought in the United States at multiple time scales

Includes bibliographical references (pages 152-155).May 1997.Characteristics of drought and wet periods were analyzed in terms of areal coverage, intensity, duration, frequency, and variability at different space and time scales. This provided insight not only into the historical perspective of anomalously dry and wet conditions, but also into the long-term variation of climate in the United States. The Standardized Precipitation Index (SPI) provided the means to analyze drought and wet periods at different time scales, a perspective that is not achieved with typical drought indices. The National Climatic Data Center and the Carbon Dioxide Information Analysis Center compiled the U.S. Historical Climatology Network (USHCN) for the purpose of analyzing climate in the United States. The USHCN includes monthly precipitation data for 1,221 stations in the contiguous United States. The distribution of stations provided the means to examine the areal coverage of drought and wet events both nationally and regionally, and the climate record of the USHCN provided the means to analyze the frequency and variability of drought and wet events for the years 1911 through 1995. The contiguous United States as a whole has become wetter over the period 1911- 1995. Additionally, all nine major regions studied for the United States have also become wetter over the period. As a result, there has been a lower frequency of both short- and long-term droughts and a higher frequency of both short- and long-term wet periods during the last 25 years of the period of record. Also, for the country as a whole, the areal coverage and intensity of long-term droughts between 1911 and 1970 are unmatched by the long-term droughts of the last 25 years of the period. On the other hand, the short-term droughts of the last 25 years of the period do compare in intensity and areal coverage to short-term droughts of the first 60 years of the period. For the country as a whole, the average duration and frequency of short-term wet periods have increased at a magnitude opposite to the decreasing average duration and frequency of short-term droughts over this period. Moreover, the percentages of stations experiencing drought at all time scales have decreased at rates nearly opposite to the increasing percentages of stations experiencing anomalously wet conditions at all time scales. Nevertheless, the contiguous United States was never entirely in or out of drought at any time scale during this period. Additionally, the contiguous United States was never entirely experiencing or entirely without anomalously wet conditions. Regionally, the most dramatic increase in the frequency of long-term wet anomalies over the last 25 years of the period has occurred in regions along the Mississippi and Ohio river valleys. Despite the occurrence of a few intense short-term droughts, these regions have all experienced long-term wet periods in the 1970s, the 1980s, and again in the early 1990s. Furthermore, from 1970 through 1995, the most consistent seasonal wet anomalies for these regions have occurred in the autumn

Effect of the lung allocation score on lung transplantation in the United States

BACKGROUND: On May 4, 2005, the system for allocation of deceased donor lungs for transplant in the United States changed from allocation based on waiting time to allocation based on the lung allocation score (LAS). We sought to determine the effect of the LAS on lung transplantation in the United States. METHODS: Organ Procurement and Transplantation Network data on listed and transplanted patients were analyzed for 5 calendar years before implementation of the LAS (2000-2004), and compared with data from 6 calendar years after implementation (2006-2011). Counts were compared between eras using the Wilcoxon rank sum test. The rates of transplant increase within each era were compared using an F-test. Survival rates computed using the Kaplan-Meier method were compared using the log-rank test. RESULTS: After introduction of the LAS, waitlist deaths decreased significantly, from 500/year to 300/year; the number of lung transplants increased, with double the annual increase in rate of lung transplants, despite no increase in donors; the distribution of recipient diagnoses changed dramatically, with significantly more patients with fibrotic lung disease receiving transplants; age of recipients increased significantly; and 1-year survival had a small but significant increase. CONCLUSIONS: Allocating lungs for transplant based on urgency and benefit instead of waiting time was associated with fewer waitlist deaths, more transplants performed, and a change in distribution of recipient diagnoses to patients more likely to die on the waiting list

Anomalous diffusion in polymers: long-time behaviour

We study the Dirichlet boundary value problem for viscoelastic diffusion in polymers. We show that its weak solutions generate a dissipative semiflow. We construct the minimal trajectory attractor and the global attractor for this problem.Comment: 13 page

Physical Nucleon Properties from Lattice QCD

We demonstrate that the extremely accurate lattice QCD data for the mass of the nucleon recently obtained by CP-PACS, combined with modern chiral extrapolation techniques, leads to a value for the mass of the physical nucleon which has a systematic error of less than one percent.Comment: 4 pages, 2 figure

Is There a General Motor Program for Right Versus Left Hand Throwing in Children?

The purpose of this study was to determine if a general motor program controlled some or all aspects of overhand throwing. Using a 12 camera Vicon motion analysis system to record data from body markers, a group of 30 Australian Aboriginal children 6-10 years of age threw with maximal effort into a large target area. Data were reduced and analysed for numerous variables and correlations were calculated between dominant and non-dominant side variables that were deemed reliable. Results indicated that five variables showed significant dominant to non-dominant correlations. However, only two of the five were entered into both multiple regressions to predict horizontal ball velocity for the dominant vs. non-dominant sides. The variables entered suggested that more gross aspects of the movement (stride distance and pelvis flexion) were both correlated from dominant to non-dominant sides and predicted horizontal ball velocity. Thus, the general motor program does not appear to control the more complex and coordinated parts of the throwing motion

Evaluation of SRAT Sampling Data in Support of a Six Sigma Yellow Belt Process Improvement Project

As part of the Six Sigma continuous improvement initiatives at the Defense Waste Processing Facility (DWPF), a Yellow Belt team was formed to evaluate the frequency and types of samples required for the Sludge Receipt and Adjustment Tank (SRAT) receipt in the DWPF. The team asked, via a technical task request, that the Statistical Consulting Section (SCS), in concert with the Immobilization Technology Section (ITS) (both groups within the Savannah River National Laboratory (SRNL)), conduct a statistical review of recent SRAT receipt results to determine if there is enough consistency in these measurements to allow for less frequent sampling. As part of this review process, key decisions made by DWPF Process Engineering that are based upon the SRAT sample measurements are outlined in this report. For a reduction in SRAT sampling to be viable, these decisions must not be overly sensitive to the additional variation that will be introduced as a result of such a reduction. Measurements from samples of SRAT receipt batches 314 through 323 were reviewed as part of this investigation into the frequency of SRAT sampling. The associated acid calculations for these batches were also studied as part of this effort. The results from this investigation showed no indication of a statistically significant relationship between the tank solids and the acid additions for these batches. One would expect that as the tank solids increase there would be a corresponding increase in acid requirements. There was, however, an indication that the predicted reduction/oxidation (REDOX) ratio (the ratio of Fe{sup 2+} to the total Fe in the glass product) that was targeted by the acid calculations based on the SRAT receipt samples for these batches was on average 0.0253 larger than the predicted REDOX based upon Slurry Mix Evaporator (SME) measurements. This is a statistically significant difference (at the 5% significance level), and the study also suggested that the difference was due to predictions of the formate and Mn concentrations in the SME product that were made at the time of the acid addition in the SRAT. For each of these analytes, the SRAT version was statistically different from the SME version (units are moles/kg SME product slurry): the SRAT values were, on average, 0.0914 larger than the SME values for formate and 0.0089 smaller than the SME values for Mn. A look at the signs of the terms corresponding to these two analytes in equation (2) indicates that both of these differences contribute to the calculated REDOX differences between the SRAT and SME product

Characterizing the Hydrology of Shallow Floodplain Lakes in the Slave River Delta, NWT, Canada, Using Water Isotope Tracers

The relative importance of major hydrological processes on thaw season 2003 lakewater balances in the Slave River Delta, NWT, Canada, is characterized using water isotope tracers and total suspended sediment (TSS) analyses. A suite of 41 lakes from three previously recognized biogeographical zones—outer delta, mid-delta, and apex—were sampled immediately following the spring melt, during summer, and in the fall of 2003. Oxygen and hydrogen isotope compositions were evaluated in the context of an isotopic framework calculated from 2003 hydroclimatic data. Our analysis reveals that flooding from the Slave River and Great Slave Lake dominated early spring lakewater balances in outer and most mid-delta lakes, as also indicated by elevated TSS concentrations (\u3e0.01 g L-1). In contrast, the input of snowmelt was strongest on all apex and some mid-delta lakes. After the spring melt, all delta lakes underwent heavy-isotope enrichment due to evaporation, although lakes flooded by the Slave River and Great Slave Lake during the spring freshet continued to be more depleted isotopically than those dominated by snowmelt input. The isotopic signatures of lakes with direct connections to the Slave River or Great Slave Lake varied throughout the season in response to the nature of the connection. Our findings provide the basis for identifying three groups of lakes based on the major factors that control their water balances: (1) flood-dominated (n=10), (2) evaporation-dominated (n=25), and (3) exchange-dominated (n=6) lakes. Differentiation of the hydrological processes that influence Slave River Delta lakewater balances is essential for ongoing hydroecological and paleohydrological studies, and ultimately, for teasing apart the relative influences of variations in local climate and Slave River hydrology

Exotic and excited-state radiative transitions in charmonium from lattice QCD

We compute, for the first time using lattice QCD methods, radiative transition rates involving excited charmonium states, states of high spin and exotics. Utilizing a large basis of interpolating fields we are able to project out various excited state contributions to three-point correlators computed on quenched anisotropic lattices. In the first lattice QCD calculation of the exotic 1-+ eta_c1 radiative decay, we find a large partial width Gamma(eta_c1 -> J/psi gamma) ~ 100 keV. We find clear signals for electric dipole and magnetic quadrupole transition form factors in chi_c2 -> J/psi gamma, calculated for the first time in this framework, and study transitions involving excited psi and chi_c1,2 states. We calculate hindered magnetic dipole transition widths without the sensitivity to assumptions made in model studies and find statistically significant signals, including a non-exotic vector hybrid candidate Y_hyb? -> eta_c gamma. As well as comparison to experimental data, we discuss in some detail the phenomenology suggested by our results and the extent to which it mirrors that of quark potential models and make suggestions for the interpretation of our results involving exotic quantum numbered states

Climate-driven Shifts in Quantity and Seasonality of River Discharge over the past 1000 Years from the Hydrographic Apex of North America

Runoff generated from high elevations is the primary source of freshwater for western North America, yet this critical resource is managed on the basis of short instrumental records that capture an insufficient range of climatic conditions. Here we probe the effects of climate change over the past ~1000 years on river discharge in the upper Mackenzie River system based on paleoenvironmental information from the Peace-Athabasca Delta. The delta landscape responds to hydroclimatic changes with marked variability, while Lake Athabasca level appears to directly monitor overall water availability. The latter fluctuated systematically over the past millennium, with the highest levels occurring in concert with maximum glacier extent during the Little Ice Age, and the lowest during the 11th century, prior to medieval glacier expansion. Recent climate-driven hydrological change appears to be on a trajectory to even lower levels as high-elevation snow and glacier meltwater contributions both continue to decline