134 research outputs found

    On Pure Spinor Superfield Formalism

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    We show that a certain superfield formalism can be used to find an off-shell supersymmetric description for some supersymmetric field theories where conventional superfield formalism does not work. This "new" formalism contains even auxiliary variables in addition to conventional odd super-coordinates. The idea of this construction is similar to the pure spinor formalism developed by N.Berkovits. It is demonstrated that using this formalism it is possible to prove that the certain Chern-Simons-like (Witten's OSFT-like) theory can be considered as an off-shell version for some on-shell supersymmetric field theories. We use the simplest non-trivial model found in [2] to illustrate the power of this pure spinor superfield formalism. Then we redo all the calculations for the case of 10-dimensional Super-Yang-Mills theory. The construction of off-shell description for this theory is more subtle in comparison with the model of [2] and requires additional Z_2 projection. We discover experimentally (through a direct explicit calculation) a non-trivial Z_2 duality at the level of Feynman diagrams. The nature of this duality requires a better investigation

    A manual for large-scale sample collection, preservation, tracking, DNA extraction, and variety identification analysis

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    Several alternative options have been used for varietal identification. However most of the traditional methods have inherent uncertainty levels and estimates often have wide confidence intervals. In an attempt to circumvent traditional survey-based measurement errors in varietal identification, DNA-based varietal identification has been implemented in the Cassava Monitoring Survey (CMS) of Nigeria — a large adoption study involving 2500 cassava farming households. The DNA fingerprinting technique offers a reliable method to accurately identify varieties grown by farmers and increases accuracy and credibility in the interpretation of adoption rates and associated economic and policy analyses. Unlike phenotype-based methods, DNA is not affected by environmental conditions or plant growth stage and is more abundant than morphological descriptors. However, undertaking a credible DNA-based varietal identification is not a trivial matter because of the logistical challenges involving sample collection and tracking by a large team of field enumerators. This manual presents the detailed steps required for undertaking reliable DNA-fingerprinting-based identification of cassava varieties. In particular, the manual gives detailed information on the establishment of a sample tracking system, preparation of a readily available and cheap sample collection kit, field sample collection methodology, preparation of samples for DNA isolation, and development of a pipeline for variety identification analysis. This manual is part of the outputs of the CMS project funded by the CGIAR Research Program on Roots, Tubers and Bananas (RTB), the Bill & Melinda Gates Foundation, and the International Institute of Tropical Agriculture (IITA)

    Electronic transport through domain walls in ferromagnetic nanowires: Co-existence of adiabatic and non-adiabatic spin dynamics

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    We study the effect of a domain wall on the electronic transport in ferromagnetic quantum wires. Due to the transverse confinement, conduction channels arise. In the presence of a domain wall, spin up and spin down electrons in these channels become coupled. For very short domain walls or at high longitudinal kinetic energy, this coupling is weak, leads to very few spin flips, and a perturbative treatment is possible. For very long domain wall structures, the spin follows adiabatically the local magnetization orientation, suppressing the effect of the domain wall on the total transmission, but reversing the spin of the electrons. In the intermediate regime, we numerically investigate the spin-dependent transport behavior for different shapes of the domain wall. We find that the knowledge of the precise shape of the domain wall is not crucial for determining the qualitative behavior. For parameters appropriate for experiments, electrons with low longitudinal energy are transmitted adiabatically while the electrons at high longitudinal energy are essentially unaffected by the domain wall. Taking this co-existence of different regimes into account is important for the understanding of recent experiments.Comment: 10 pages, 6 figure

    Het managen van incidenten in het onderwijs. Praktische governance-lessen op basis van een vergelijkende case analyse

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    Bij iedere onderwijsorganisatie doen zich incidenten voor. Deze incidenten lopen soms ernstig uit de hand. Er zijn echter ook incidenten die tijdig en effectief worden aangepakt en niet uitgroeien tot echte ongelukken of zelfs misstanden. Aan de hand van zes concrete incidenten binnen het onderwijsdomein is onderzocht hoe dankzij adequaat optreden ongelukken zijn voorkomen en welke mechanismen daarbij een rol spelen

    Cassava farmers' preferences for varieties and seed dissemination system in Nigeria: gender and regional perspectives

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    The Cassava Monitoring Survey (CMS) project was funded by the CGIAR-RTB Program and the Bill & Melinda Gates Foundation. The main goal was to carry out a study on cassava adoption and diffusion patterns in Nigeria. This includes explaining why farmers are adopting certain varieties and describing preference differences across regions and gender. This specific study and report is part of Component IV of the broader CMS Project, and it covered gender-differentiated, end-user surveys on varietal and trait preferences. The objective of this component was to use qualitative methods to probe deeper into some of the information that was obtained in the quantitative survey on gender-based trait preferences and seed dissemination pathways

    The clustering instability of inertial particles spatial distribution in turbulent flows

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    A theory of clustering of inertial particles advected by a turbulent velocity field caused by an instability of their spatial distribution is suggested. The reason for the clustering instability is a combined effect of the particles inertia and a finite correlation time of the velocity field. The crucial parameter for the clustering instability is a size of the particles. The critical size is estimated for a strong clustering (with a finite fraction of particles in clusters) associated with the growth of the mean absolute value of the particles number density and for a weak clustering associated with the growth of the second and higher moments. A new concept of compressibility of the turbulent diffusion tensor caused by a finite correlation time of an incompressible velocity field is introduced. In this model of the velocity field, the field of Lagrangian trajectories is not divergence-free. A mechanism of saturation of the clustering instability associated with the particles collisions in the clusters is suggested. Applications of the analyzed effects to the dynamics of droplets in the turbulent atmosphere are discussed. An estimated nonlinear level of the saturation of the droplets number density in clouds exceeds by the orders of magnitude their mean number density. The critical size of cloud droplets required for clusters formation is more than 20μ20 \mum.Comment: REVTeX 4, 15 pages, 2 figures(included), PRE submitte

    Behoorlijk Bestuur van Onderwijsinstellingen

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    Het doel van dit onderzoek luidt: - Het conceptualiseren van behoorlijk bestuur als een levende en lerende bestuurspraktijk die verder gaat dan alleen maar een set van principes die verwoord zijn in een governance code. - Het beschrijven van praktijken van duurzaam behoorlijk bestuur op het niveau van gedrag en cultuur in onderwijsinstellingen waar corrigerende mechanismen aantoonbaar hebben gewerkt; - het analyseren van de condities waaronder deze mechanismen werken; en - het formuleren van uitgangspunten voor de versterking van het corrigerende vermoge

    Cohort profile of BIOMArCS: The BIOMarker study to identify the Acute risk of a Coronary Syndrome-a prospective multicentre biomarker study conducted in the Netherlands

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    __Purpose:__ Progression of stable coronary artery disease (CAD) towards acute coronary syndrome (ACS) is a dynamic and heterogeneous process with many intertwined constituents, in which a plaque destabilising sequence could lead to ACS within short time frames. Current CAD risk assessment models, however, are not designed to identify increased vulnerability for the occurrence of coronary events within a precise, short time frame at the individual patient level. The BIOMarker study to identify the Acute risk of a Coronary Syndrome (BIOMArCS) was designed to evaluate whether repeated measurements of multiple biomarkers can predict such 'vulnerable periods'. __Participants:__ BIOMArCS is a multicentre, prospective, observational study of 844 patients presenting with ACS, either with or without ST-elevation and at least one additional cardiovascular risk factor. __Methods and analysis:__ We hypothesised that patterns of circulating biomarkers that reflect the various pathophysiological components of CAD, such as distorted lipid metabolism, vascular inflammation, endothelial dysfunction, increased thrombogenicity and ischaemia, diverge in the days to weeks before a coronary event. Divergent biomarker patterns, identified by serial biomarker measurements during 1-year follow-up might then indicate 'vulnerable periods' during which patients with CAD are at high short-Term risk of developing an ACS. Venepuncture was performed every fortnight during the first half-year and monthly thereafter. As prespecified, patient enrolment was terminated after the primary end point of cardiovascular death or hospital admission for nonfatal ACS had occurred in 50 patients. A case-cohort design will explore differences in temporal patterns of circulating biomarkers prior to the repeat ACS

    High prevalence of non-accidental trauma among deceased children presenting at Level I trauma centers in the Netherlands

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    PURPOSE: Between 0.1—3% of injured children who present at a hospital emergency department ultimately die as a result of their injuries. These events are typically reported as unnatural causes of death and may result from either accidental or non-accidental trauma (NAT). Examples of the latter include trauma that is inflicted directly or resulting from neglect. Although consultation with a forensic physician is mandatory for all deceased children, the prevalence of fatal inflicted trauma or neglect among children is currently unclear. METHODS: This is a retrospective study that included children (0–18 years) who presented and died at one of the 11 Level I trauma centers in the Netherlands between January 1, 2014, and January 1, 2019. Outcomes were classified based on the conclusions of the Child Abuse and Neglect team or those of forensic pathologists and/or the court in cases referred for legally mandated autopsies. Cases in which conclusions were unavailable and there was no clear accidental cause of death were reviewed by an expert panel. RESULTS: The study included 175 cases of childhood death. Seventeen (9.7%) of these children died due to inflicted trauma (9.7%), 18 (10.3%) due to neglect, and 140 (80%) due to accidents. Preschool children (< 5 years old) were significantly more likely to present with injuries due to inflicted trauma and neglect compared to older children (44% versus 6%, p < 0.001, odds ratio [OR] 5.80, 95% confidence interval [CI] 2.66–12.65). Drowning accounted for 14 of the 18 (78%) pediatric deaths due to neglect, representing 8% of the total cases. Postmortem radiological studies and autopsies were performed on 37 (21%) of all cases of childhood death. CONCLUSION: One of every five pediatric deaths in our nationwide Level I trauma center study was attributed to NAT; 44% of these deaths were the result of trauma experienced by preschool-aged children. A remarkable number of fatal drownings were due to neglect. Postmortem radiological studies and autopsies were performed in only one-fifth of all deceased children. The limited use of postmortem investigations may have resulted in missed cases of NAT, which will result in an overall underestimation of fatal NAT experienced by children. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12024-021-00416-7

    Study protocol for the multicentre cohorts of Zika virus infection in pregnant women, infants, and acute clinical cases in Latin America and the Caribbean: The ZIKAlliance consortium

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    Background: The European Commission (EC) Horizon 2020 (H2020)-funded ZIKAlliance Consortium designed a multicentre study including pregnant women (PW), children (CH) and natural history (NH) cohorts. Clinical sites were selected over a wide geographic range within Latin America and the Caribbean, taking into account the dynamic course of the ZIKV epidemic. Methods: Recruitment to the PW cohort will take place in antenatal care clinics. PW will be enrolled regardless of symptoms and followed over the course of pregnancy, approximately every 4 weeks. PW will be revisited at delivery (or after miscarriage/abortion) to assess birth outcomes, including microcephaly and other congenital abnormalities according to the evolving definition of congenital Zika syndrome (CZS). After birth, children will be followed for 2 years in the CH cohort. Follow-up visits are scheduled at ages 1-3, 4-6, 12, and 24 months to assess neurocognitive and developmental milestones. In addition, a NH cohort for the characterization of symptomatic rash/fever illness was designed, including follow-up to capture persisting health problems. Blood, urine, and other biological materials will be collected, and tested for ZIKV and other relevant arboviral diseases (dengue, chikungunya, yellow fever) using RT-PCR or serological methods. A virtual, decentralized biobank will be created. Reciprocal clinical monitoring has been established between partner sites. Substudies of ZIKV seroprevalence, transmissio
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