780 research outputs found
Nutrient Management Approaches and Tools for Dairy Farms in Australia and the U.S.
Nutrient surpluses in industrialized nations like the U.S. and Australia are causing problems on dairy farms and posing a threat to the rest of the environment. This paper discusses tools that dairy farmers can use to manage the excess nutrients while continuing to meet demands and profit. The authors suggest improvements in these tools that will not only quantify the amount of nutrient balances on dairy farms, but also identify opportunities for enhanced nutrient use and reduced nutrient losses.Nutrient Management Tools, Australian Dairy Farms, U.S. Dairy Farms, Confinement-based Dairy Operations, Grazing-based Diary Operations, Environmental Economics and Policy, Farm Management, Land Economics/Use,
Measuring the effects of extreme weather events on yields
AbstractExtreme weather events are expected to increase worldwide, therefore, anticipating and calculating their effects on crop yields is important for topics ranging from food security to the economic viability of biomass products. Given the local nature of weather, particularly precipitation, effects are best measured at a local level. This paper analyzes weather events at the level of the farm for a specific crop, winter wheat. Once it has been established that extreme events are expected to continue occurring at historically high levels for farming locations throughout the Netherlands, the effects of those events on wheat yields are estimated while controlling for the other major input factors affecting yields. Econometric techniques are applied to an unbalanced panel data set of 334 farms for a period of up to 12 years. Analyzes show that the number of days with extreme high temperatures in Dutch wheat growing regions has significantly increased since the early 1900s, while the number of extreme low temperature events has fallen over that same period. The effects of weather events on wheat yields were found to be time specific in that the week in which an event occurred determined its effect on yields. High temperature events and precipitation events were found to significantly decrease yields
Linking catchability and fisher behaviour under effort management
Catchability is crucial for the economic performance of fisheries and their management. However, in many bio-economic simulation models it is assumed to be either constant or it is largely ignored, despite the fact that it is known to vary due to technical, environmental and behavioral factors. Such variation can cause the relationship between effort and fishing mortality to be nonlinear. This paper provides evidence for the possibility of nonlinear optimizing behavior from the Dutch beam trawl fishery, provides a methodology for estimating the curvature of the resulting relation, and a simple way of implementing these processes within a bio-economic model. Moreover, it shows the influence of a nonlinear relationship between effort and fishing mortality in a model of effort management (EU long-term flatfish management plan)
The acceptability of counter-terrorism measures on urban mass transit in the UK
The security and safety of urban mass transit systems continues to draw a great deal of government, media and public attention.
The bombings in Madrid, London and Mumbai, suggest that new and “acceptable” approaches to counterterrorism may become important components of how urban mass transit systems are designed and operated in the future.
Technical developments in security and counter-terrorism can provide a wide range of non-intrusive or overt design solutions to counter-terrorism.
However, in implementing these design solutions the whole system performance needs to be considered.
Undertaking qualitative research with a wide range of stakeholders (including the public, transit system designers and operators) the potential acceptability of certain technological approaches is assessed.
Analysis of the findings suggests five broad acceptability factors governed by five influence variables.
The acceptability factors include that counter-terrorism measures are more acceptable to transit designers and operators if they are tied in with complementary personal security and safety features, and are more acceptable to transit operators and the general public if they do not restrict the free flow of passengers through the transit network.
These perspectives are dependent upon influence variables including whether there was a recent attack on a UK transit system and the Government’s present ‘level of threat’ from terrorist attack.
The impact of these findings is discussed along with suggestions for future research into acceptable counter-terrorism measures for transport
Meta-analysis of individual-patient data from EVAR-1, DREAM, OVER and ACE trials comparing outcomes of endovascular or open repair for abdominal aortic aneurysm over 5 years
Background: The erosion of the early mortality advantage of elective endovascular aneurysm repair (EVAR) compared with open repair of abdominal aortic aneurysm remains without a satisfactory explanation. Methods: An individual-patient data meta-analysis of four multicentre randomized trials of EVAR versus open repair was conducted to a prespecified analysis plan, reporting on mortality, aneurysm-related mortality and reintervention. Results: The analysis included 2783 patients, with 14 245 person-years of follow-up (median 5·5 years). Early (0–6 months after randomization) mortality was lower in the EVAR groups (46 of 1393 versus 73 of 1390 deaths; pooled hazard ratio 0·61, 95 per cent c.i. 0·42 to 0·89; P = 0·010), primarily because 30-day operative mortality was lower in the EVAR groups (16 deaths versus 40 for open repair; pooled odds ratio 0·40, 95 per cent c.i. 0·22 to 0·74). Later (within 3 years) the survival curves converged, remaining converged to 8 years. Beyond 3 years, aneurysm-related mortality was significantly higher in the EVAR groups (19 deaths versus 3 for open repair; pooled hazard ratio 5·16, 1·49 to 17·89; P = 0·010). Patients with moderate renal dysfunction or previous coronary artery disease had no early survival advantage under EVAR. Those with peripheral artery disease had lower mortality under open repair (39 deaths versus 62 for EVAR; P = 0·022) in the period from 6 months to 4 years after randomization. Conclusion: The early survival advantage in the EVAR group, and its subsequent erosion, were confirmed. Over 5 years, patients of marginal fitness had no early survival advantage from EVAR compared with open repair. Aneurysm-related mortality and patients with low ankle : brachial pressure index contributed to the erosion of the early survival advantage for the EVAR group. Trial registration numbers: EVAR-1, ISRCTN55703451; DREAM (Dutch Randomized Endovascular Aneurysm Management), NCT00421330; ACE (Anévrysme de l'aorte abdominale, Chirurgie versus Endoprothèse), NCT00224718; OVER (Open Versus Endovascular Repair Trial for Abdominal Aortic Aneurysms), NCT00094575.</p
Meta-analysis of individual-patient data from EVAR-1, DREAM, OVER and ACE trials comparing outcomes of endovascular or open repair for abdominal aortic aneurysm over 5 years
Background: The erosion of the early mortality advantage of elective endovascular aneurysm repair (EVAR) compared with open repair of abdominal aortic aneurysm remains without a satisfactory explanation. Methods: An individual-patient data meta-analysis of four multicentre randomized trials of EVAR versus open repair was conducted to a prespecified analysis plan, reporting on mortality, aneurysm-related mortality and reintervention. Results: The analysis included 2783 patients, with 14 245 person-years of follow-up (median 5·5 years). Early (0–6 months after randomization) mortality was lower in the EVAR groups (46 of 1393 versus 73 of 1390 deaths; pooled hazard ratio 0·61, 95 per cent c.i. 0·42 to 0·89; P = 0·010), primarily because 30-day operative mortality was lower in the EVAR groups (16 deaths versus 40 for open repair; pooled odds ratio 0·40, 95 per cent c.i. 0·22 to 0·74). Later (within 3 years) the survival curves converged, remaining converged to 8 years. Beyond 3 years, aneurysm-related mortality was significantly higher in the EVAR groups (19 deaths versus 3 for open repair; pooled hazard ratio 5·16, 1·49 to 17·89; P = 0·010). Patients with moderate renal dysfunction or previous coronary artery disease had no early survival advantage under EVAR. Those with peripheral artery disease had lower mortality under open repair (39 deaths versus 62 for EVAR; P = 0·022) in the period from 6 months to 4 years after randomization. Conclusion: The early survival advantage in the EVAR group, and its subsequent erosion, were confirmed. Over 5 years, patients of marginal fitness had no early survival advantage from EVAR compared with open repair. Aneurysm-related mortality and patients with low ankle : brachial pressure index contributed to the erosion of the early survival advantage for the EVAR group. Trial registration numbers: EVAR-1, ISRCTN55703451; DREAM (Dutch Randomized Endovascular Aneurysm Management), NCT00421330; ACE (Anévrysme de l'aorte abdominale, Chirurgie versus Endoprothèse), NCT00224718; OVER (Open Versus Endovascular Repair Trial for Abdominal Aortic Aneurysms), NCT00094575.</p
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Low-Chrome/Chrome Free Refractories for Slagging Gasifiers
Gasifiers are containment vessels used to react carbon-containing materials with oxygen and water, producing syngas (CO and H2) that is used in chemical and power production. It is also a potential source of H2 in a future hydrogen economy. Air cooled slagging gasifiers are one type of gasifier, operating at temperatures from 1275-1575º C and at pressures of 400 psi or higher. They typically use coal or petroleum coke as the carbon source, materials which contain ash impurities that liquefy at the gasification temperatures, producing liquid slag in quantities of 100 or more tons/day, depending on the carbon fed rate and the percent ash present in the feedstock. The molten slag is corrosive to refractory linings, causing chemical dissolution and spalling. The refractory lining is composed of chrome oxide, alumina, and zirconia; and is replaced every 3-24 months. Gasifier users would like greater on-line availability and reliability of gasifier liners, something that has impacted gasifier acceptance by industry. Research is underway at NETL to improve refractory service life and to develop a no-chrome or low-chrome oxide alternative refractory liner. Over 250 samples of no- or low-chrome oxide compositions have been evaluated for slag interactions by cup testing; with potential candidates for further studies including those with ZrO2, Al2O3, and MgO materials. The development of improved liner materials is necessary if technologies such as IGCC and DOE’s Near Zero Emissions Advanced Fossil Fuel Power Plant are to be successful and move forward in the marketplace
Macro-economic Impact Study for Bio-based Malaysia
This Macro-economic Impact Study (MES) provides quantitative insights into the macro-economic effects of introducing green, palmbased alternatives for electricity, fuels, chemicals and materials industries in Malaysia between now and 2030
Complex angular structure of three elliptical galaxies from high-resolution ALMA observations of strong gravitational lenses
The large-scale mass distributions of galaxy-scale strong lenses have long been assumed to be well described by a singular ellipsoidal
power-law density profile with external shear. However, the inflexibility of this model could lead to systematic errors in astrophysical
parameters inferred with gravitational lensing observables. Here, we present observations with the Atacama Large (sub-)Millimetre
Array (ALMA) of three strongly lensed dusty star-forming galaxies at '30 mas angular resolution and investigate the sensitivity of
these data to angular structure in the lensing galaxies. We jointly infer the lensing mass distribution and the full surface brightness of
the lensed sources with multipole expansions of the power-law density profile up to the fourth order using a technique developed for
interferometric data. All three datasets strongly favour third and fourth-order multipole amplitudes of ≈1 percent of the convergence.
While the infrared stellar isophotes and isodensity shapes agree for one lens system, for the other two the isophotes disagree to varying
extents, suggesting contributions to the angular structure from dark matter intrinsic or extrinsic to the lensing galaxy.http://www.hanspub.org/Journal/AAS.htmlPhysicsNon
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