19,288 research outputs found

    Analysing Personal Characteristics of Lone-Actor Terrorists: Research Findings and Recommendations

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    This Research Note presents the outcome of a project that looked at the personal characteristics of lone-actor terrorists. It is part of the larger Countering Lone-Actor Terrorism (CLAT) project. The project described here aimed to improve understanding of, and responses to, the phenomenon of (potentially) violent lone-actors based on an analysis of 120 cases from across Europe. The Research Note focuses on the personal characteristics of lone-actor terrorists. First of all, it presents the main findings of the general analysis of the study into personal variables of lone-actor terrorists. Subsequently, the authors outline a set of recommendations based on the key findings. In the beginning, we present the main research questions of the CLAT project and the working definition of lone-actor terroris

    Highly efficient room temperature spin injection in a metal-insulator-semiconductor light emitting diode

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    We demonstrate highly efficient spin injection at low and room temperature in an AlGaAs/GaAs semiconductor heterostructure from a CoFe/AlOx tunnel spin injector. We use a double-step oxide deposition for the fabrication of a pinhole-free AlOx tunnel barrier. The measurements of the circular polarization of the electroluminescence in the Oblique Hanle Effect geometry reveal injected spin polarizations of at least 24% at 80K and 12% at room temperature

    Tailor-Made Nanostructured Ion Selective MCM-48 Membranes

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    Mesoporous templated MCM-48 silica was prepared using a C16 surfactant as template. The MCM-48 powders and thin films were characterized by different techniques. Two types of porous supports were used, namely macroporous ¿-alumina and silicon microsieves. The supported MCM-48 layers were applied as liquid permeable membranes in pressure-driven nanofiltration and electric field-mediated ion transport experiments

    A multi-gene phylogeny of Lactifluus (Basidiomycota, Russulales) translated into a new infrageneric classification of the genus

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    Infrageneric relations of the genetically diverse milkcap genus Lactifluus (Russulales, Basidiomycota) are poorly known. Currently used classification systems still largely reflect the traditional, mainly morphological, characters used for infrageneric delimitations of milkcaps. Increased sampling, combined with small-scale molecular studies, show that this genus is underexplored and in need of revision. For this study, we assembled an extensive dataset of the genus Lactifluus, comprising 80 % of all known species and 30 % of the type collections. To unravel the infrageneric relationships within this genus, we combined a multi-gene molecular phylogeny, based on nuclear ITS, LSU, RPB2 and RPB1, with a morphological study, focussing on five important characteristics (fruit body type, presence of a secondary velum, colour reaction of the latex/context, pileipellis type and presence of true cystidia). Lactifluus comprises four supported subgenera, each containing several supported clades. With extensive sampling, ten new clades and at least 17 new species were discovered, which highlight the high diversity in this genus. The traditional infrageneric classification is only partly maintained and nomenclatural changes are proposed. Our morphological study shows that the five featured characteristics are important at different evolutionary levels, but further characteristics need to be studied to find morphological support for each clade. This study paves the way for a more detailed investigation of biogeographical history and character evolution within Lactifluus

    GP trainees’ perceptions on learning EBM using conversations in the workplace : a video-stimulated interview study

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    Background To be able to practice evidence-based medicine (EBM) when making decisions for individual patients, it is important to learn how to combine the best available evidence with the patient's preferences and the physician's clinical expertise. In general practice training, these skills can be learned at the workplace using learning conversations: meetings between the supervising general practitioner (GP) and GP trainee to discuss medical practice, selected topics or professional performance. This study aimed to give insight into the perceptions of GP trainees on their EBM learning processes during learning conversations. Methods We held semi-structured video-stimulated elicitation interviews (n = 22) with GP trainees affiliated to GP training institutes in the Netherlands and Belgium. GP trainees were shown fragments of their learning conversations, enabling reflection during the interview. Taking an inductive approach, interview recordings were transcribed verbatim and analysed with NVivo software. Results GP trainees perceived learning conversations as useful for learning and discussing EBM. Multiple EBM learning activities were identified, such as discussing evidence together, relating evidence to cases in daily practice and discussing the supervisor's experience and the specific local context in the light of what the evidence recommends. However, for learning to occur, trainees need and expect specific behaviour, both from their supervisors and themselves. Supervisors should supply well-substantiated answers that are applicable in practice and give the trainee confirmation. In turn, the trainee needs to prepare well in order to ask focused, in-depth questions. A safe space allowing equal and open discussion between trainee and supervisor is perceived as an essential context for optimal EBM learning. Conclusions Our findings show that trainees find learning conversations useful for EBM learning in general practice. To bring EBM learning to its full potential, attention should be paid to optimising the behavioural and contextual factors found relevant to enhancing EBM learning

    Voltage controlled spin injection in a (Ga,Mn)As/(Al,Ga)As Zener diode

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    The spin polarization of the electron current in a p-(Ga,Mn)As-n-(Al,Ga)As-Zener tunnel diode, which is embedded in a light-emitting diode, has been studied theoretically. A series of self-consistent simulations determines the charge distribution, the band bending, and the current-voltage characteristics for the entire structure. An empirical tight-binding model, together with the Landauer- Buttiker theory of coherent transport has been developed to study the current spin polarization. This dual approach allows to explain the experimentally observed high magnitude and strong bias dependence of the current spin polarization.Comment: Submitted to Phys. Rev. B Rapid Communication

    Color-Octet Fragmentation and the psi' Surplus at the Tevatron

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    The production rate of prompt ψ\psi''s at large transverse momentum at the Tevatron is larger than theoretical expectations by about a factor of 30. As a solution to this puzzle, we suggest that the dominant ψ\psi' production mechanism is the fragmentation of a gluon into a ccˉc \bar c pair in a pointlike color-octet S-wave state, which subsequently evolves nonperturbatively into a ψ\psi' plus light hadrons. The contribution to the fragmentation function from this process is enhanced by a short-distance factor of 1/αs21/\alpha_s^2 relative to the conventional color-singlet contribution. This may compensate for the suppression by v4v^4, where vv is the relative momentum of the charm quark in the ψ\psi'. If this is indeed the dominant production mechanism at large pTp_T, then the prompt ψ\psi''s that are observed at the Tevatron should almost always be associated with a jet of light hadrons.Comment: 9 pages, LaTe

    Electrical Spin Injection in a Ferromagnetic / Tunnel Barrier/ Semiconductor Heterostructure

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    We demonstrate experimentally the electrical ballistic electron spin injection from a ferromagnetic metal / tunnel barrier contact into a semiconductor III-V heterostructure. We introduce the Oblique Hanle Effect technique for reliable optical measurement of the degree of injected spin polarization. In a CoFe / Al2O3 / GaAs / (Al,Ga)As heterostructure we observed injected spin polarization in excess of 8 % at 80K.Comment: 5 pages, 4 figure

    Entrepreneurial Exit in Real and Imagined Markets

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    Entrepreneurs exit their business due to selection mechanisms experienced in the market place. Next to this well known ex-post decision to exit, entrepreneurs select ex-ante whether they are willing to pursue an entrepreneurial career at all, or to give up these entrepreneurial intentions. This paper compares the role of personal and ecological factors as determinants of these two types of selection: exit in real and in imagined markets. Entrepreneurs in imagined markets are more likely to exit in strong welfare state regimes, while real entrepreneurs are more likely to exit when they have low levels of human capital and when they are located in metropolitan areas

    Thermomagnetic history effects in SmMn2_2Ge2_2

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    The intermetallic compound SmMn2_2Ge2_2, displaying multiple magnetic phase transitions, is being investigated in detail for its magnetization behavior near the 145 K first order ferromagnetic to antiferromagnetic transition occuring on cooling, in particular for thermomagnetic history effects in the magnetization data. The most unusual finding is that the thermomagnetic irreversibility, [= MFCW^{FCW}(T)-MZFC^{ZFC}(T)] at 135 K is higher in intermediate magnetic field strengths. By studying the response of the sample (i.e., thermomagnetic irreversibility and thermal hysteresis) to different histories of application of magnetic field and temperature, we demonstrate how the supercooling and superheating of the metastable magnetic phases across the first order transition at 145 K contribute to overall thermomagnetic irreversibility.Comment: 15 pages, 5 figures, to appear in Physical Review
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