1,987 research outputs found

    The Principled Case for Employing Private Military and Security Companies in Humanitarian Interventions and Peacekeeping

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    The possibility of using private military and security companies to bolster the capacity to undertake humanitarian intervention has been increasingly debated. The focus of such discussions has, however, largely been on practical issues and the contingent problems posed by private force. By contrast, this paper considers the principled case for privatising humanitarian intervention. It focuses on two central issues. First, is there a case for preferring these firms to other, state-based agents of humanitarian intervention? In particular, given a state’s duties to their own military personnel, should the use of private military and security contractors be preferred to regular soldiers for humanitarian intervention? Second, on the other hand, does outsourcing humanitarian intervention to private military and security companies pose some fundamental, deeper problems in this context, such as an abdication of a state’s duties? © Deane-Peter Baker and James Pattison. All rights reserved. This paper may be freely circulated in electronic or hard copy provided it is not modified in any way, the rights of the author not infringed, and the paper is not quoted or cited without express permission of the author. The editors cannot guarantee a stable URL for any paper posted here, nor will they be responsible for notifying others if the URL is changed or the paper is taken off the site. Electronic copies of this paper may not be posted on any other website without express permission of the author

    Polymerization of Peptide Polymers for Biomaterial Applications

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    Position Resolution in LaBr3 and LaCl3 Scintillators Using Position-Sensitive Photomultiplier Tubes

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    Advanced scintillator materials such as LaBr3:Ce and LaCl3:Ce hold great promise for future hard X-ray and gamma-ray astrophysics missions due to their high density, high light output, good linearity, and fast decay times. Of particular importance for future space-based imaging instruments, such as coded-aperture telescopes, is the precise spatial location of individual gamma-ray interactions. We have investigated the position and energy resolution achievable within monolithic (5 cm × 5 cm × 1 cm) LaBr3:Ce and LaCl3:Ce crystals using position-sensitive light readout devices, including a position-sensitive photomultiplier tube and a multi-anode photomultiplier tube. We present the results of these tests and discuss the applicability of such advanced scintillators to future high-energy imaging astrophysics missions

    Nitrification Inhibitor and Nitrogen Application Timing Effects on Yields and Nitrate-Nitrogen Concentrations in Subsurface Drainage from a Corn-Soybean Rotation

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    Excess precipitation in Iowa and many other agricultural production areas is removed artificially via subsurface drainage systems that intercept and usually divert it to surface waters. Nitrogen, either applied as fertilizer or manure and derived from soil organic matter, can be carried as nitrate with the excess water in quantities that can cause deleterious effects downstream. A four-year, five-replication, field study was initiated in the fall of 1999 in Pocahontas County, Iowa on 0.05 ha plots that are predominantly Nicollet, Webster, and Canisteo clay loams with 3-5% organic matter. The objective was to determine the influence of seasonal N application and the use of nitrapyrin [inhibitor; 2-chloro-6 (trichloromethyl) pyridine] on flow-weighted nitrate-nitrogen concentrations and yields in a corn-soybean rotation, combined on single plots. Six aqua-ammonia nitrogen treatments (168 and 252 kg/ha at planting and in late fall, and 168 kg/ha at planting and late fall with nitrapyrin) were imposed on subsurface drained, continuous-flow-monitored plots. Combined fall 1999 and spring 2000 precipitation was 42% of normal average. Subsequently, normal precipitation was recorded for both fall and spring periods (after fall application, and before spring application) until spring and fall 2002 (51% and 73% of normal, respectively). Spring 2003 precipitation was again only 51% of normal average. Four-year average, flow-weighted nitrate-nitrogen concentrations ranked in highest to lowest order: spring-252(22.9 mg/L;a) \u3e fall-252(18.1 mg/L;b) \u3e spring-168 w/inhibitor(17.7 mg/L;bc) \u3e fall-168 w/inhibitor(16.0 mg/L;bcd) \u3e spring-168(14.8 mg/L;cd) \u3e fall-168(14.2 mg/L;cd). Spring application plots had significantly greater soybean yield the following season compared to fall applications. Greatest corn yields were observed for the spring-252 and fall-168 rates, but were only significantly different than the spring-168 rate for yield. Therefore, under slightly dry to normal precipitation conditions, corn yields and nitrate-nitrogen concentrations in subsurface drainage were not significantly different between seasonal timing or inhibitor use treatments at the 168 kg/ha nitrogen rate

    Reframing outcome measures for thrombolytics in acute ischemic stroke

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    An informed consent conversation examining relevant research and discussing the potential benefits and harms of thrombolytic therapy in acute stroke

    Minimal structural requirements of alkyl γ-lactones capable of antagonizing the cocaine-induced motility decrease in planarians

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    We recently reported that the natural cyclic lactone, parthenolide, and related analogs prevent the expression of behavioral effects induced by cocaine in planarians and that parthenolide’s γ-lactone ring is required for this effect. In the present work, we tested a series of alkyl γ-lactones with varying chain length (1–8 carbons) to determine their ability to antagonize the planarian motility decrease induced by 200 μM cocaine. Alkyl lactones with up to a 4-carbon alkyl chain did not affect planarian motility or antagonized the cocaine-induced motility decrease; only the compound γ-nonalactone (a γ-lactone with a 5-carbon chain) was able to prevent the cocaine-induced behavioral patterns, while alkyl lactones with longer carbon chains failed to prevent the cocaineinduced effects. Thus, we conclude that the optimal structural features of this family of compounds to antagonize cocaine’s effect in this experimental system is a γ-lactone ring with at a 5-carbon long functional group

    Nitrogen Application Rate Effect on Nitrate-Nitrogen Concentration and Loss in Subsurface Drainage for a Corn-Soybean Rotation

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    Excess precipitation in Midwest agricultural production areas is often removed artificially via subsurface drainage systems that intercept and divert it to surface waters. Nitrogen (N), either applied as fertilizer or manure or derived from soil organic matter, can be carried as nitrate with the excess water in quantities that may have deleterious effects downstream. A field study was initiated in 1989 in Pocahontas County, Iowa, on 0.05 ha plots of glacially derived clay loams. The objective of this three-phase study was to determine the effect of N application rate on NO3-N concentration and loss in a corn-soybean rotation over a wide range of weather conditions. Nitrogen-rate treatment phases with five seasons each (six for phase II) were imposed on subsurface-drained, continuous-flow-monitored plots over a 16-year period. Phase I N rates ranged from 0 to 168 kg N ha-1 in 56 kg N ha-1 increments. Separate plots were used for each crop in phase I, and significant NO3-N concentration differences were not observed between corn or soybean plots; this led to combining both crops in a split-plot configuration for phases II and III to study system effects. Phase II N rates ranged from 45 to 179 kg N ha-1 in 45 kg N ha-1 increments. Phase III was limited to two rates, 168 and 252 kg N ha-1. Average yearly flow-weighted NO3-N concentrations ranged from 3.9 mg L-1 (45 kg N ha-1, 1995) to 28.7 mg L-1 (252 kg N ha-1, 2001). Average flow-weighted NO3-N concentrations (in mg L-1) ranked by N rate were: 23.4 (252), 13.2 (179), 15.5 (168), 11.9 (134), 11.7 (112), 8.1 (90), 9.5 (56), 5.7 (45), and 8.9 (0). Losses were precipitation dependent and were reflective of individual seasons and rates imposed. Average flow-weighted NO3-N losses (kg ha-1) ranked by N rate and by phase were: 58 (168), 68 (112), 48 (56), 50 (no N) for phase I; 8 (179), 15 (134), 19 (90), 7 (45) for phase II; and 49 (252), 32 (168) for phase III. Results indicate that concentrations generally increased with rate; the effect on losses was variable due to disparity in drainage volumes among years. Corn yield during all periods showed a strong correlation between N rate and yield. As N rate increased, yield increased. It should be noted that at least 50% of the years showed limited yield response to N application above the next to the highest rates. To achieve average NO3-N concentrations less than 10 mg L-1 (USEPA drinking water standard) in subsurface drainage at this site, N application rates would need to be less than 112 kg N ha-1. Rates currently recommended for this area range from 112 to 168 kg N ha-1. Results from this study have significant implications for N fertilizer management and subsurface drainage NO3-N loss to surface waters in the state, the Mississippi River, and the Gulf of Mexico

    Comparison of Liquid Swine Manure and Aqua-Ammonia Nitrogen Application Timing on Subsurface Drainage Water Quality in Iowa

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    In Iowa and many other Midwestern states, excess water is removed artificially through subsurface drainage systems. While these drainage systems are vital for crop production, nitrogen (N), added as manure or commercial fertilizer, or derived from soil organic matter, can be carried as nitrate-nitrogen (NO3-N) to downstream water bodies. A five-year, five-replication, field study was initiated in the fall of 1999 in Pocahontas County, Iowa, on 0.05 ha plots that are predominantly Nicollet, Webster, and Canisteo clay loams with 3% to 5% organic matter located on glacial till within the Des Moines Lobe. The objective was to determine the influence of seasonal N application as ammonia or liquid swine manure on flow-weighted NO3-N concentrations and losses in subsurface drainage water and crop yields in a corn-soybean rotation. Four aqua-ammonia N treatments (168 or 252 kg N ha-1 applied for corn in late fall or as an early season side-dress) and three manure treatments (218 kg N ha-1 for corn in late fall or spring or 168 kg N ha-1 in the fall for both corn and soybean) were imposed on subsurface-drained, continuous flow-monitored plots. Precipitation during the drainage season (March to November) was slightly below the long-term norm (722 mm) for all four years in the study period and ranged from 615 mm in 2001 (85% of normal) to 707 mm (98% of normal) in 2004. Monthly rainfall was highly variable, and subsurface drainage, or the lack thereof, usually mimicked the precipitation patterns. On average, 69% of subsurface drainage occurred in May and June of each year, with lower amounts in April and July. Four-year average flow-weighted NO3-N concentrations measured in drainage water were ranked: spring aqua-ammonia 252 (23 mg L-1) = fall manure 168 every year (23 mg L-1) \u3e fall aqua-ammonia 252 (19 mg L-1) = spring manure 218 (18 mg L-1) = fall manure 218 (17 mg L-1) \u3e spring aqua-ammonia 168 (15 mg L-1) = fall aqua-ammonia 168 (14 mg L-1). Corn yields were significantly greater (p = 0.05) for the spring and fall manure 218 rates than for non-manure treatments. Soybean yields were significantly greater (p = 0.05) for the treatments with a spring nitrogen application to the previous corn crop. Overall, under the slightly dry to normal precipitation conditions of this study, corn yields and NO3-N concentrations in subsurface drainage were not significantly different (p = 0.05) between fall and spring treatments at the 168 aqua-ammonia or 218 kg ha-1 N manure N rates

    Temporal Subsurface Flow Patterns from Fifteen Years in North-Central Iowa

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    Subsurface drainage in the Upper Midwest is of importance to agricultural production. However, proper management of these systems through in-field management, drainage management, or edge of field practices is needed to limit negative environmental impacts particularly from nitrate-nitrogen leaching losses. One management practice being considered is drainage management where the outflow of subsurface drainage is managed to conserve water and decrease the overall outflow of subsurface drainage. To understand how and when drainage management may be utilized in the upper Midwest it is important to review long-term drainage data to understand the timing, duration, and volumes of subsurface drainage in these climates. An on-going drainage study from north-central Iowa allows for reviewing fifteen years of subsurface drainage which encompasses a range of climatic conditions. This information has been reviewed with the objective of understanding the timing, duration, and drainage volumes considering temporal drainage flow patterns. In particular, the monthly and seasonal flow patterns have been investigated using this long-term drainage record. On this site with a relatively narrow drain spacing of 7.6 m, drainage volume was approximately 40% of the precipitation. The time period from April through June had approximately 50% of the average annual precipitation and approximately 70% of the average annual drainage. In addition, the percent of annual drainage occurring after August 1 was only approximately 7%. The timing of subsurface flow in these areas specifically during the spring coincides with time of planting, crop germination, and early crop development has implications when considering drainage management practices and the effectiveness of these practices to limit flow and therefore nitrate-nitrogen leaching losses. To minimize outflow of drainage water, these drainage management systems would need to allow for adequate flexibility to ensure crop production while effectively managing subsurface drainage flow to potentially minimize the outflow of water
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