1,413 research outputs found
A modified flood severity assessment for enhanced decision support: application to the Boscastle flash flood of 2004
A modified flash flood severity assessment is presented, based on scoring a set of factors according to their potential for generating extreme catchment-scale flooding. Improvements are made to the index through incorporation of parameter uncertainties, managing data absence, and clearer graphical communication. The motive for proposing these changes is to better inform flood managers during the development of a flash flood that may require an emergency response. This modified decision-support system is demonstrated for the Boscastle flood of 2004 and other historical floods in the United Kingdom. For Boscastle, the extreme nature of the flood is underestimated, which is likely to be due to the lack of sophistication in weighting flood parameters. However, the proposed amendments are able to rapidly reflect the reliability of a catchment severity rating, which may further enhance this technique as a decision-support tool alongside radar observations of localized storms
New tool gauges impact of exchange rates on states
States with relatively more employment tied to international trade are increasingly likely to be sensitive to exchange rate movements, and face sharply different effective exchange rate shifts, often provoked by economic or financial crises. ; Analysts need a tool to more effectively gauge the sometimes varied impact of exchange rate movements on states. In this article, we introduce a measure that compares the value of the dollar against the currencies of countries with which each of the 50 states trade--the real trade-weighted value of the dollar (RTWVD) index. ; To assess the impact of exchange rates on states, the RTWVD weights the U.S. dollar exchange rate with various countries based on a state's share of exports. It is a "real" measure because it adjusts the exchange rate for different rates of inflation. The index will allow analysts to more precisely identify the exchange rates that most affect a state's economy.International trade ; Foreign exchange rates ; Exports
Yield Reserve Program Costs in the Virginia Coastal Plain
A proposed Yield Reserve Program designed to compensate farmers for any reduced yields resulting from nitrogen (N) application rates reduced to below recommended rates is evaluated. Assuming that farmers currently follow Extension recommendations for applying N, Yield Reserve Program participation reduces expected net revenue by 13/ha. The Yield Reserve Program reduces expected net revenue by 20/ha for farmers who apply N to maximize expected net revenue. Farmers’ costs of participation increase with lower probabilities of inadequate rainfall and higher corn prices and decline with higher N prices. The Yield Reserve Program can significantly reduce N applications to cropland, which may reduce N content of surface waters, but the costs to taxpayers and farmers will depend on how the program is implemented.compliance cost, nitrogen fertilizer, nonpoint source pollution, policy, yield response function, Agricultural and Food Policy, Crop Production/Industries,
Patient-Specific Fetal Dose Determination for Multi-Target Gamma Knife Radiosurgery: Computational Model and Case Report.
A 42-year-old woman at 29 weeks gestation via in vitro fertilization who presented with eight metastatic brain lesions received Gamma Knife stereotactic radiosurgery (GKSRS) at our institution. In this study, we report our clinical experience and a general procedure of determining the fetal dose from patient-specific treatment plans and we describe quality assurance measurements to guide the safe practice of multi-target GKSRS of pregnant patients. To estimate fetal dose pre-treatment, peripheral dose-to-focal dose ratios (PFRs) were measured in a phantom at the distance approximating the fundus of uterus. Post-treatment, fetal dose was calculated from the actual patient treatment plan. Quality assurance measurements were carried out via the extrapolation dosimetry method in a head phantom at increasing distances along the longitudinal axis. The measurements were then empirically fitted and the fetal dose was extracted from the curve. The computed and measured fetal dose values were compared with each other and associated radiation risk was estimated. Based on low estimated fetal dose from preliminary phantom measurements, the patient was accepted for GKSRS. Eight brain metastases were treated with prescription doses of 15-19 Gy over 143 min involving all collimator sizes as well as composite sector mixed shots. Direct fetal dose computation based on the actual patient's treatment plan estimated a maximum fetal dose of 0.253 cGy, which was in agreement with surface dose measurements at the level of the patient's uterine fundus during the actual treatment. Later phantom measurements also estimated fetal dose to be in the range of 0.21-0.28 cGy (dose extrapolation curve R2 = 0.998). Using the National Council on Radiation Protection and Measurements (NCRP) population-based model, we estimate the fetal risk of secondary malignancy, which is the primary toxicity after 25 weeks gestation, to be less than 0.01%. Of note, the patient delivered the baby via scheduled cesarean section at 36 weeks without complications attributable to the GKSRS procedure. GKSRS of multiple brain metastases was demonstrated to be safe and feasible during pregnancy. The applicability of a general patient-specific fetal dose determination method was also demonstrated for the first time for such a treatment
Interannual, seasonal, and diel variation in soil respiration relative to ecosystem respiration at a wetland to upland slope at Harvard Forest
Soil carbon dioxide efflux (soil respiration, SR) was measured with eight autochambers at two locations along a wetland to upland slope at Harvard Forest over a 4 year period, 2003–2007. SR was consistently higher in the upland plots than at the wetland margin during the late summer/early fall. Seasonal and diel hystereses with respect to soil temperatures were of sufficient magnitude to prevent quantification of the influence of soil moisture, although apparent short‐term responses of SR to precipitation occurred. Calculations of annual cumulative SR illustrated a decreasing trend in SR over the 5 year period, which were correlated with decreasing springtime mean soil temperatures. Spring soil temperatures decreased despite rising air temperatures over the same period, possibly as an effect of earlier leaf expansion and shading. The synchronous decrease in spring soil temperatures and SR during regional warming of air temperatures may represent a negative feedback on a warming climate by reducing CO2 production from soils. SR reached a maximum later in the year than total ecosystem respiration (ER) measured at a nearby eddy covariance flux tower, and the seasonality of their temperature response patterns were roughly opposite. SR, particularly in the upland, exceeded ER in the late summer/early fall in each year, suggesting that areas of lower efflux such as the wetland may be significant in the flux tower footprint or that long‐term bias in either estimate may create a mismatch. Annual estimates of ER decreased over the same period and were highly correlated with SR
Structural characterization of an α-1, 6-linked galactomannan from natural Cordyceps 2 sinensis
An α-1, 6-linked galactomannan was isolated and purified from natural Cordyceps sinensis. The fine structure analysis of this polysaccharide was elucidated based on partial acid hydrolysis, monosaccharide composition, methylation and 1D/2D nuclear magnetic resonance (NMR) spectroscopy. Monosaccharide composition analysis revealed that this polysaccharide was mainly composed of galactose (68.65%), glucose (6.65%) and mannose (24.02%). However, after partial acid hydrolysis the percentages of galactose, glucose and mannose were changed to 3.96%, 13.82% and 82.22%, respectively. The molecular weight of this polysaccharide was 7207. Methylation and NMR analysis revealed that this galactomannan had a highly branched structure, mainly consisted of a mannan skeleton and galactofuranosyl chains. The structure of galactofuranosyl part was formed by alternating (1 → 5)-lined β-Galf and (1 → 6)-liked β-Galf or a single (1 → 6)-liked β-Galf, attaching to the O-2 and O-4 of the mannose chain, and terminated at β-T-Galf. The mannan core was revealed by analyzing the partial acid hydrolysate of the galactomannan and the structure was composed of (1 → 6)-linked α-Manp backbone, with substituted at C-2 by short chains of 2-substituted Manp or Galf branches
A 96-Channel FPGA-based Time-to-Digital Converter
We describe an FPGA-based, 96-channel, time-to-digital converter (TDC)
intended for use with the Central Outer Tracker (COT) in the CDF Experiment at
the Fermilab Tevatron. The COT system is digitized and read out by 315 TDC
cards, each serving 96 wires of the chamber. The TDC is physically configured
as a 9U VME card. The functionality is almost entirely programmed in firmware
in two Altera Stratix FPGA's. The special capabilities of this device are the
availability of 840 MHz LVDS inputs, multiple phase-locked clock modules, and
abundant memory. The TDC system operates with an input resolution of 1.2 ns.
Each input can accept up to 7 hits per collision. The time-to-digital
conversion is done by first sampling each of the 96 inputs in 1.2-ns bins and
filling a circular memory; the memory addresses of logical transitions (edges)
in the input data are then translated into the time of arrival and width of the
COT pulses. Memory pipelines with a depth of 5.5 s allow deadtime-less
operation in the first-level trigger. The TDC VME interface allows a 64-bit
Chain Block Transfer of multiple boards in a crate with transfer-rates up to 47
Mbytes/sec. The TDC also contains a separately-programmed data path that
produces prompt trigger data every Tevatron crossing. The full TDC design and
multi-card test results are described. The physical simplicity ensures
low-maintenance; the functionality being in firmware allows reprogramming for
other applications.Comment: 32 pages, 13 figure
Understanding the structure-emulsification relationship of gum ghatti – a review of recent advances
This paper is based on a series of physical and chemical investigations to understand the structure-function properties of gum ghatti. After elucidating the detailed molecular structure of two gum ghatti fractions, the structure of its component glycoprotein was investigated whereby, the protein sequence and hydrophobicity were identified, followed by the conformational analysis of the gum and its fractions. Many techniques were used for the elucidation of the fine structures, which included methylation analysis-GC-MS, Maldi-TOF MS and 2D NMR spectroscopy, homonuclear ¹H/¹H correlations spectroscopy (COSY, TOCSY), heteronuclear ¹³C/¹H multiple-quantum coherence spectroscopy (HMQC) and heteronuclear multiple bond correlation (HMBC). Conformational properties were studied using a modelling system (Insight II) to relate the hydrophobicity of the protein moieties with the complex structures of the carbohydrates. These studies now provide an explanation for the excellent emulsification properties of gum ghatti in oil-in-water emulsions, which enable its application in the food, cosmetic and/or pharmaceutical industries
Alcohol Screening and Brief Interventions for Offenders in the Probation Setting (SIPS Trial): a Pragmatic Multicentre Cluster Randomized Controlled Trial
Aim - To evaluate the effectiveness of different brief intervention strategies at reducing hazardous or harmful drinking in the probation setting. Offender managers were randomized to three interventions, each of which built on the previous one: feedback on screening outcome and a client information leaflet control group, 5 min of structured brief advice and 20 min of brief lifestyle counselling.
Methods - A pragmatic multicentre factorial cluster randomized controlled trial. The primary outcome was self-reported hazardous or harmful drinking status measured by Alcohol Use Disorders Identification Test (AUDIT) at 6 months (negative status was a score of <8). Secondary outcomes were AUDIT status at 12 months, experience of alcohol-related problems, health utility, service utilization, readiness to change and reduction in conviction rates.
Results - Follow-up rates were 68% at 6 months and 60% at 12 months. At both time points, there was no significant advantage of more intensive interventions compared with the control group in terms of AUDIT status. Those in the brief advice and brief lifestyle counselling intervention groups were statistically significantly less likely to reoffend (36 and 38%, respectively) than those in the client information leaflet group (50%) in the year following intervention.
Conclusion - Brief advice or brief lifestyle counselling provided no additional benefit in reducing hazardous or harmful drinking compared with feedback on screening outcome and a client information leaflet. The impact of more intensive brief intervention on reoffending warrants further research
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