1,819 research outputs found

    VSCE technology definition study

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    Refined design definition of the variable stream control engine (VSCE) concept for advanced supersonic transports is presented. Operating and performance features of the VSCE are discussed, including the engine components, thrust specific fuel consumption, weight, noise, and emission system. A preliminary engine design is presented

    Reflections in abstract Coxeter groups

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    Let WW be a Coxeter group and rWr\in W a reflection. If the group of order 2 generated by rr is the intersection of all the maximal finite subgroups of WW that contain it, then any isomorphism from WW to a Coxeter group WW' must take rr to a reflection in WW'. The aim of this paper is to show how to determine, by inspection of the Coxeter graph, the intersection of the maximal finite sugroups containing rr. In particular we show that the condition above is satisfied whenever WW is infinite and irreducible, and has the property that all rank two parabolic subgroups are finite. So in this case all isomorphisms map reflections to reflections.Comment: 25 pages, 0 figure

    On the direct indecomposability of infinite irreducible Coxeter groups and the Isomorphism Problem of Coxeter groups

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    In this paper we prove, without the finite rank assumption, that any irreducible Coxeter group of infinite order is directly indecomposable as an abstract group. The key ingredient of the proof is that we can determine, for an irreducible Coxeter group, the centralizers of the normal subgroups that are generated by involutions. As a consequence, we show that the problem of deciding whether two general Coxeter groups are isomorphic, as abstract groups, is reduced to the case of irreducible Coxeter groups, without assuming the finiteness of the number of the irreducible components or their ranks. We also give a description of the automorphism group of a general Coxeter group in terms of those of its irreducible components.Comment: 30 page

    Exploring corruption in fisheries

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    This paper explores corruption in global fisheries. While reducing corruption is critical for the effective management of the fisheries sector and the fulfilment of the UN’s sustainable development goals (SDGs, and SDGs14 and 16 in particular), to do so, it is necessary to first have a systematic and comprehensive understanding of what corruption is and how it is manifested in the sector. There is literature on illegal, unregulated and unreported (IUU) fishing, but not much on corruption. The paper proposes an analytical framework and applies it with six revelatory cases to improve the conceptual clarity of corruption in fisheries. Specific corruption problems found in licensing, negotiating access agreements, lax enforcement, extortion, political corruption, money laundering and tax manipulation, human trafficking etc. can therefore be better identified through this analysis, which lays a base for systematic responses to tackling corruption in fisheries and accordingly furthering the sustainable development of the sector

    Using legume-based mixtures to enhance the nitrogen use efficiency and economic viability of cropping systems - Final report (LK09106/HGCA3447)

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    As costs for mineral fertilisers rise, legume-based leys are recognised as a potential alternative nitrogen source for crops. Here we demonstrate that including species-rich legume-based leys in rotations helps to maximise synergies between agricultural productivity and other ecosystem services. By using functionally diverse plant species mixtures, these services can be optimised and fine-tuned to regional and farm-specific needs. Replicated field experiments were conducted over three years at multiple locations, testing the performance of 12 legume species and 4 grass species sown in monocultures, as well as in a mixture of 10 of the legumes and all 4 grasses (called the All Species Mix, ASM). In addition, we compared this complex mixture to farmer-chosen ley mixtures on 34 sites across the UK. The trials showed that there is a large degree of functional complementarity among the legume species. No single species scored high on all evaluation criteria. In particular, the currently most frequently used species, white clover, is outscored by other legume species on a number of parameters such as early development and resistance to decomposition. Further complementarity emerged from the different responses of legume species to environmental variables, with soil pH and grazing or cutting regime being among the more important factors. For example, while large birdsfoot trefoil showed better performance on more acidic soils, the opposite was true for sainfoin, lucerne and black medic. In comparison with the monocultures, the ASM showed increased ground cover, increased above-ground biomass and reduced weed biomass. Benefits of mixing species with regard to productivity increased over time. In addition, the stability of biomass production across sites was greater in the ASM than in the legume monocultures. Within the on-farm trials, we further found that on soils low in organic matter the biomass advantage of the ASM over the Control ley was more marked than on the soils with higher organic matter content. Ecological modelling revealed that the three best multifunctional mixtures all contained black medic, lucerne and red clover. Within the long term New Farming Systems (NFS) rotational study, the use of a clover bi-crop showed improvement to soil characteristics compared to current practice (e.g. bulk density and water infiltration rate). Improvements in wheat yield were also noted with respect to the inclusion of a clover bi-crop in 2010, but there was evidence of a decline in response as the N dose was increased. Cumulatively, over both the wheat crop and the spring oilseed rape crop, the clover bi-crop improved margin over N. The highest average yield response (~9%) was associated with the ASM legume species mix cover cropping approach

    Attention Deficit Hyperactivity Disorder and Risk of Posttraumatic Stress and Related Disorders: A Prospective Longitudinal Evaluation in U.S. Army Soldiers

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    Crossâ sectional associations between attention deficit hyperactivity disorder (ADHD) and posttraumatic stress disorder (PTSD) have been observed, but longitudinal studies assessing this association are lacking. This prospective study evaluated the association between predeployment ADHD and postdeployment PTSD among U.S. Army soldiers. Soldiers who deployed to Afghanistan were surveyed before deployment (T0) and approximately 1 month (T1), 3 months (T2), and 9 months (T3) after their return. Logistic regression was performed to estimate the association between predeployment ADHD and postdeployment (T2 or T3) PTSD among 4,612 soldiers with data at all waves and no record of stimulant medication treatment during the study. To evaluate specificity of the ADHDâ PTSD association, we examined associations among predeployment ADHD, postdeployment major depressive episode (MDE), generalized anxiety disorder (GAD), and suicidal ideation. Weighted prevalence of ADHD predeployment was 6.1% (SE = 0.4%). Adjusting for other risk factors, predeployment ADHD was associated with risk of postdeployment PTSD, adjusted odds ratio (AOR) = 2.13, 95% CI [1.51, 3.00], p < .001, including incidence among soldiers with no predeployment history of PTSD, AOR = 2.50, 95% CI [1.69, 3.69], p < .001. ADHD was associated with postdeployment MDE, AOR = 2.80, 95% CI [2.01, 3.91], p < .001, and GAD, AOR = 3.04, 95% CI [2.10, 4.42], p < .001, but not suicidal ideation. Recognition of associations between predeployment ADHD and postdeployment PTSD, MDE, and GAD may inform targeted prevention efforts. Future research should examine whether treatment of ADHD is protective against PTSD and related disorders in traumaâ exposed individuals.ResumenSpanish Abstracts by Asociación Chilena de Estrés Traumático (ACET)El trastorno de déficit atencional con hiperactividad y el riesgo del trastorno de estrés postraumático y trastornos relacionados: Una evaluación longitudinal prospectiva en soldados del ejército estadounidenseTDAH Y RIESGO DE TEPT EN SOLDADOS DEL EJà RCITO DE EE.UU.Se han observado asociaciones transversales entre el trastorno por déficit de atención con hiperactividad (TDAH) y el trastorno por estrés postraumático (TEPT), pero faltan estudios longitudinales que evalúen esta asociación. Este estudio prospectivo evaluó la asociación entre el TDAH previo al despliegue y el TEPT posterior al despliegue entre los soldados del Ejército de Estados Unidos. Los soldados desplegados en Afganistán fueron encuestados antes del despliegue (T0) y aproximadamente 1 mes (T1), 3 meses (T2), y 9 meses (T3) después de su regreso del despliegue. Se realizó una regresión logística para estimar la asociación entre el TDAH previo al despliegue y el TEPT posterior al despliegue (T2 o T3) en 4.612 soldados con datos en todas las etapas y sin registro de tratamiento con medicamentos estimulantes durante el estudio. Para evaluar la especificidad de la asociación TDAHâ TEPT, examinamos las asociaciones entre el TDAH previo al despliegue, el episodio depresivo mayor posterior al despliegue (EDM), el trastorno de ansiedad generalizada (TAG), y la ideación suicida. La prevalencia ponderada del TDAH previo al despliegue fue de 6.1% (SE = 0.4%). Al controlar los otros factores de riesgo, el TDAH previo al despliegue se asoció con el riesgo de TEPT posterior al despliegue, odds ratio ajustado (AOR en su sigla en inglés) = 2.13, IC del 95% [1.51, 3.00], p <.001, incluida la incidencia entre soldados sin historial previo al despliegue de TEPT, AOR = 2.50, IC del 95% [1.69, 3.69], p <.001. El TDAH se asoció con el EDM posterior al despliegue, AOR = 2.80, IC del 95% [2.01, 3.91], p <.001, y TAG, AOR = 3.04, IC del 95% [2.10, 4.42], p <.001, pero no con ideación suicida. El reconocimiento de las asociaciones entre el TDAH previo al despliegue y el TEPT, el EDM, y el TAG posterior al despliegue puede informar los esfuerzos de prevención específicos. Las investigaciones futuras deberían examinar si el tratamiento del TDAH protege contra el TEPT y los trastornos relacionados en personas expuestas a trauma.æ ½è±¡Traditional and Simplified Chinese Abstracts by the Asian Society for Traumatic Stress Studies (AsianSTSS)ç°¡é« å ç¹ é« ä¸­æ æ ®è¦ ç ±äº æ´²å µå ·å¿ ç ç  ç©¶å­¸æ 翻譯Attention Deficit Hyperactivity Disorder and Risk of Posttraumatic Stress and Related Disorders: A Prospective Longitudinal Evaluation in US Army SoldiersTraditional Chineseæ¨ é¡ : å° æ³¨å ä¸ è¶³æ é åº¦æ´»èº ç è æ £å µå ·å¾ å£ å ç å ç ¸é ç ¾ç ç é¢¨é ª:å° ç¾ å è» äººé ²è¡ ç å ç »ç¸±è²«ç  ç©¶æ ®è¦ : é å¾ ä¸ ç ´æ ç  ç©¶æª¢è¦ å° æ³¨å ä¸ è¶³æ é åº¦æ´»èº ç (ADHD)è å µå ·å¾ å£ å ç (PTSD)ä¹ é ç æ©«æ ·æ §é é £, å ¯æ ¯, æ å ä» æ¬ ç¼ºæª¢è¦ å ©è é é £ç ç¸±è²«ç  ç©¶ã æ ¬å ç »ç  ç©¶æ ¨å ¨é é ç¾ è» æ¨£æ ¬, è© ä¼°æ å½¹å ADHDè· æ å½¹å¾ PTSDç é é £ã æ¨£æ ¬ç ºå å¾ é ¿å¯ æ± æ å½¹ç è» äºº, å ¨æ å½¹å (T0)å å® æ æ å½¹å¾ ç´ 1å æ (T1)ã 3å æ (T2)å 9å æ (T3)æ ¥å èª¿æ ¥ã æ å 以é 輯迴歸å æ å æ æ 波段ç æ ¸æ , ä¼°è¨ 4,612å è» äººæ å½¹å ADHDè· æ å½¹å¾ (T2 æ T3)PTSDç é é £ã ç  ç©¶ä¸­, æ¨£æ ¬ä¸¦ç ¡æ ç ¨è å¥®è ¥ç ©ã ç ºäº è§£ADHDâ PTSDç ç ¹æ® é é £, æ å æª¢è¦ ä»¥ä¸ é  ç ®ä¹ é ç é é £:æ å½¹å ADHDã å® æ æ å½¹å¾ ç å ´é æ é¬±ç¯ æ®µ(MDE)ã å»£æ³ æ §ç ¦æ ®ç (GAD)ã è ªæ®ºæ 念ã æ å½¹å ADHDæ ®é åº¦ç º6.1% (SE = 0.4%)ã å° å ¶ä» é¢¨é ªå  ç´ ä½ èª¿ç¯ å¾ , æ å½¹å ADHDè· æ å½¹å¾ æ £PTSDç é¢¨é ªæ æ é é £(å·²èª¿ç¯ å ç® æ¯ (AOR) = 2.13, 95% CI [1.51, 3.00], p < .001), ç ¶ä¸­å æ ¬æ å½¹å ä¸¦ç ¡PTSDç è» äºº(AOR = 2.50, 95% CI [1.69, 3.69], p < .001)ã ADHDè· å® æ æ å½¹å¾ æ £MDEç (AOR = 2.80, 95% CI [2.01, 3.91], p < .001)å GAD(AOR = 3.04, 95% CI [2.10, 4.42] p < .001)é ½æ é , ä½ è· è ªæ®ºæ å¿µç ¡é ã äº è§£æ å½¹å ADHDè· æ å½¹å¾ PTSDã MDEå GADç é é £, å ¯è ½æ å ©ç ¼å± é å° æ §ç é  é ²å·¥ä½ ã æ ªä¾ ç  ç©¶æ æª¢è¦ å° å å µäººå£«æ ä¾ ADHDæ²»ç , æ ¯å ¦å° å ¶PTSDå ç ¸é ç ¾ç æ ä¿ è­·æ æ ã Simplified Chineseæ  é¢ : ä¸ æ³¨å ä¸ è¶³æ è¿ åº¦æ´»è· ç ä¸ æ £å 伤å å å ç å ç ¸å ³ç ¾ç ç é£ é ©:å¯¹ç¾ å ½å äººè¿ è¡ ç å ç »çºµè´¯ç  ç©¶æ ®è¦ : è¿ å¾ ä¸ ç ´æ ç  ç©¶æ£ è§ ä¸ æ³¨å ä¸ è¶³æ è¿ åº¦æ´»è· ç (ADHD)ä¸ å 伤å å å ç (PTSD)ä¹ é ´ç æ¨ªæ ­æ §å ³è¿ , å ¯æ ¯, æ ä»¬ä» æ¬ ç¼ºæ£ è§ ä¸¤è å ³è¿ ç çºµè´¯ç  ç©¶ã æ ¬å ç »ç  ç©¶æ ¨å ¨é è¿ ç¾ å æ ·æ ¬, è¯ ä¼°æ å½¹å ADHDè· æ å½¹å PTSDç å ³è¿ ã æ ·æ ¬ä¸ºå å¾ é ¿å¯ æ± æ å½¹ç å 人, å ¨æ å½¹å (T0)å å® æ æ å½¹å 约1个æ (T1)ã 3个æ (T2)å 9个æ (T3)æ ¥å è° æ ¥ã æ ä»¬ä»¥é »è¾ å å½ å æ å æ æ 波段ç æ °æ ®, 估计4,612å å 人æ å½¹å ADHDè· æ å½¹å (T2 æ T3)PTSDç å ³è¿ ã ç  ç©¶ä¸­, æ ·æ ¬å¹¶æ  æ ç ¨å ´å¥ è ¯ç ©ã ä¸ºäº è§£ADHDâ PTSDç ç ¹æ® å ³è¿ , æ ä»¬æ£ è§ ä»¥ä¸ é¡¹ç ®ä¹ é ´ç å ³è¿ :æ å½¹å ADHDã å® æ æ å½¹å ç 严é æ é è 段(MDE)ã å¹¿æ³ æ §ç ¦è ç (GAD)ã è ªæ æ 念ã æ å½¹å ADHDæ ®é 度为6.1% (SE = 0.4%)ã å¯¹å ¶ä» é£ é ©å  ç´ ä½ è° è å , æ å½¹å ADHDè· æ å½¹å æ £PTSDç é£ é ©æ æ å ³è¿ (å·²è° è è ç® æ¯ (AOR) = 2.13, 95% CI [1.51, 3.00], p < .001), å½ ä¸­å æ ¬æ å½¹å å¹¶æ  PTSDç å 人(AOR = 2.50, 95% CI [1.69, 3.69], p < .001)ã ADHDè· å® æ æ å½¹å æ £MDEç (AOR = 2.80, 95% CI [2.01, 3.91], p < .001)å GAD(AOR = 3.04, 95% CI [2.10, 4.42] p < .001)é ½æ å ³, ä½ è· è ªæ æ å¿µæ  å ³ã äº è§£æ å½¹å ADHDè· æ å½¹å PTSDã MDEå GADç å ³è¿ , å ¯è ½æ å ©å å± é å¯¹æ §ç é¢ é ²å·¥ä½ ã æ ªæ ¥ç  ç©¶åº æ£ è§ å¯¹å å 人士æ ä¾ ADHDæ²»ç , æ ¯å ¦å¯¹å ¶PTSDå ç ¸å ³ç ¾ç æ ä¿ æ ¤æ åº ãPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146971/1/jts22347_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146971/2/jts22347.pd

    The Diversity and Abundance of Small Arthropods in Onion, Allium cepa, Seed Crops, and their Potential Role in Pollination

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    Onion, Allium cepa L. (Asparagales: Amaryllidaceae), crop fields grown for seed production require arthropod pollination for adequate seed yield. Although many arthropod species visit A. cepa flowers, for most there is little information on their role as pollinators. Small flower visiting arthropods (body width < 3 mm) in particular are rarely assessed. A survey of eight flowering commercial A. cepa seed fields in the North and South Islands of New Zealand using window traps revealed that small arthropods were highly abundant among all except one field. Insects belonging to the orders Diptera and Thysanoptera were the most abundant and Hymenoptera, Collembola, Psocoptera, Hemiptera, and Coleoptera were also present. To test whether small arthropods might contribute to pollination, seed sets from umbels caged within 3 mm diameter mesh cages were compared with similarly caged, hand-pollinated umbels and uncaged umbels. Caged umbels that were not hand-pollinated set significantly fewer seeds (average eight seeds/umbel, n = 10) than caged hand-pollinated umbels (average 146 seeds/umbel) and uncaged umbels (average 481 seeds/umbel). Moreover, sticky traps placed on umbels within cages captured similar numbers of small arthropods as sticky traps placed on uncaged umbels, suggesting cages did not inhibit the movement of small arthropods to umbels. Therefore, despite the high abundance of small arthropods within fields, evidence to support their role as significant pollinators of commercial A. cepa seed crops was not found
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