4,404 research outputs found

    Comment on "The Jones-Hore theory of radical-ion-pair reactions is not self-consistent" (arXiv:1010.3888v3)

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    A short comment on "The Jones-Hore theory of radical-ion-pair reactions is not self-consistent" (arXiv:1010.3888v3) is presented. In the comment, it is pointed out that the paper includes a misconception about the Jones-Hore approach in Chem. Phys. Lett. 488 (2010) 90-93. The re-formulation is presented and it is demonstrated that the Jones-Hore theory is consistent at least on the point claimed by I. K. Kominis in the paper

    Blood donation and human immunodeficiency virus infection: do new and regular donors present different risks?

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    This paper examines some problems inherent in assessing the risk of trans­mitting infection through blood transfusion. Blood from a recently infected donor may transmit infection which may not be detected at the time of transfusion. Inferences about the degree of risk must be made from the in­cidence and prevalence of infection in the community at large, and from the number of donated units of blood in which evidence of infection is found. We address the particular problem of comparing the relative risk in two donor populations, the repeat donors who give blood on several occasions, and the single donors who give blood only once

    Intercultural Sensitivity, Intercultural Competence & Intercultural Intelligence: A Review of the Literature and a Proposition of a Linear Relationship

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    The ideas, terms and concepts surrounding intercultural competence are robust and offer varying degrees, phases and precursors. Working off of the definitions, models and stages of previous works, this review starts by providing working definitions of culture, intercultural sensitivity, intercultural competence and intercultural intelligence. This presentation of literature is sequenced in a way to give insight into how and why each of these terms lead into and overlap each other and how a causal relationship is manifested in each step. This review is approached through the lens of education and how these concepts can and are applied in a classroom environment. Conclusions are made regarding the linear, yet not prescriptive relationship among these steps

    STELLA Facilitates Differentiation of Germ Cell and Endodermal Lineages of Human Embryonic Stem Cells

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    Stella is a developmentally regulated gene highly expressed in mouse embryonic stem (ES) cells and in primordial germ cells (PGCs). In human, the gene encoding the STELLA homologue lies on chromosome 12p, which is frequently amplified in long-term cultured human ES cells. However, the role played by STELLA in human ES cells has not been reported. In the present study, we show that during retinoic acid (RA)-induced differentiation of human ES cells, expression of STELLA follows that of VASA, a marker of germline differentiation. By contrast, human embryonal carcinoma cells express STELLA at a higher level compared with both karyotypically normal and abnormal human ES cell lines. We found that over-expression of STELLA does not interfere with maintenance of the stem cell state of human ES cells, but following retinoic acid induction it leads to up-regulation of germline- and endodermal-associated genes, whereas neural markers PAX6 and NEUROD1 are down-regulated. Further, STELLA over-expression facilitates the differentiation of human ES cells into BE12-positive cells, in which the expression of germline- and endodermal-associated genes is enriched, and suppresses differentiation of the neural lineage. Taken together, this finding suggests a role for STELLA in facilitating germline and endodermal differentiation of human ES cells

    Understanding the impact of failure modes of cables for the design of turbo-electric distributed propulsion electrical power systems.

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    The turbo-electric distributed propulsion (TeDP) concept has been proposed to enable future aircraft to meet ambitious, environmental targets as demand for air travel increases. In order to maximize the benefits of TeDP, the use of high temperature superconductors (HTS) has been proposed. Despite being an enabling technology for many future concepts, the use of superconductors in electrical power systems is still in the early stages of development. Hence their impact on system performance, in particular system transients, such as electrical faults or load changes, is poorly understood. Such an understanding is critical for the development of an appropriate electrical protection system for TeDP. Therefore, in order to enable appropriate protection strategies to be developed for TeDP electrical networks an understanding of how electrical faults will propagate in superconducting materials is required. An understanding of how technologies that utilize these materials may experience failure modes in ways that are uncharacteristic of their conventional counterparts is also needed. This paper presents a dynamic electrical – thermal model of a superconducting cable, at an appropriate level of fidelity for electrical power system studies, which enables the investigation of failure modes of cables. This includes the impact of designing fault tolerant cables on the electrical power system as a whole to be considered

    Effectiveness of Community Forest Management at reducing deforestation in Madagascar

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    AbstractCommunity Forest Management (CFM) is a widespread conservation approach in the tropics. It is also promoted as a means by which payment for ecosystem services schemes can be implemented. However, evidence on its performance is weak. We investigated the effectiveness of CFM at reducing deforestation from 2000 to 2010 in Madagascar. To control for factors confounding impact estimates, we used statistical matching. We also contrasted the effects of CFM by whether commercial use of forest resources is allowed or not. We cannot detect an effect, on average, of CFM compared to no CFM, even when we restricted the sample to only where information suggests effective CFM implementation on the ground. Likewise, we cannot detect an effect of CFM where commercial use of natural resources is allowed. However, we can detect a reduction in deforestation in CFM that does not permit commercial uses, compared to no CFM or CFM allowing commercial uses. Our findings suggest that CFM and commercial use of forest resources are not guarantees of forest conservation and that differentiating among types of CFM is important

    Enhancement of deep epileptiform activity in the EEG via 3-D adaptive spatial filtering,

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    The detection of epileptiform discharges (ED’s) in the electroencephalogram (EEG) is an important component in the diagnosis of epilepsy. However, when the epileptogenic source is located deep in the brain, the ED’s at the scalp are often masked by more superficial, higher-amplitude EEG activity. A noninvasive technique which uses an adaptive “beamformer” spatial filter has been investigated for the enhancement of signals from deep sources in the brain suspected of containing ED’s. A forward three-layer spherical model was used to relate a dipolar source to recorded signals to determine the beamformer’s spatial response constraints. The beamformer adapts, using the least-mean-squares (LMS) algorithm, to reduce signals from sources distant to some arbitrarily defined location in the brain. The beamformer produces three outputs, being the orthogonal components of the signal estimated to have arisen at or near the assumed location. Simulations were performed by using the same forward model to superimpose realistic ED’s on normal EEG recordings. The simulations show the beamformer’s ability to enhance signals emanating from deep foci by way of an enhancement ratio (ER), being the improvement in signal-to-noise ratio (SNR) to that observed at any of the scalp electrodes. The performance of the beamformer has been evaluated for 1) the number of scalp electrodes, 2) the recording montage, 3) dependence on the background EEG, 4) dependence on magnitude, depth, and orientation of epileptogenic focus, and 5) sensitivity to inaccuracies in the estimated location of the focus. Results from the simulations show the beamformer’s performance to be dependent on the number of electrodes and moderately sensitive to variations in the EEG background. Conversely, its performance appears to be largely independent of the amplitude and morphology of the ED. The dependence studies indicated that the beamformer’s performance was moderately dependent on eccentricity with the ER increasing as the dipolar source and the beamformer were moved from the center to the surface of the brain (1.51–2.26 for radial dipoles and 1.17–2.69 for tangential dipoles). The beamformer was also moderately dependent on variations in polar or azimuthal angle for radial and tangential dipoles. Higher ER’s tended to be seen for locations between electrode sites. The beamformer was more sensitive to inaccuracies in both polar and azimuthal location than depth of the dipolar source. For polar locations, an ER > 1.0 was achieved when the beamformer was located within 25 of a radial dipole and 35 of a tangential dipole. Similarly, angular ranges of 37.5 and 45 , respectively, for inaccuracies in azimuthal locations. Preliminary results from real EEG records, comprising 12 definite or questionable epileptiform events, from four patients, demonstrated the beamformer’s ability to enhance these events by a mean 100% (52%–215%) for referential data and a mean 104% (50%–145%) for bipolar data

    Fault management strategies and architecture design for turboelectric distributed propulsion

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    The TeDP concept has been presented as a possible solution to reduce aircraft emissions despite the continuing trend for increased air traffic. However, much of the benefit of this concept hinges on the reliable transfer of electrical power from the generators to the electrical motor driven propulsors. Protection and fault management of the electrical transmission and distribution network is crucial to ensure flight safety and to maintain the integrity of the electrical components on board. Therefore a robust fault management strategy is required. With consideration of the aerospace-specific application, the fault management strategy must be efficient, of minimal weight and be capable of a quick response to off-nominal conditions. This paper investigates how the TeDP architecture designs are likely to be driven by the development of appropriate fault management strategies

    Finding co-solvers on Twitter, with a little help from Linked Data

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    In this paper we propose a method for suggesting potential collaborators for solving innovation challenges online, based on their competence, similarity of interests and social proximity with the user. We rely on Linked Data to derive a measure of semantic relatedness that we use to enrich both user profiles and innovation problems with additional relevant topics, thereby improving the performance of co-solver recommendation. We evaluate this approach against state of the art methods for query enrichment based on the distribution of topics in user profiles, and demonstrate its usefulness in recommending collaborators that are both complementary in competence and compatible with the user. Our experiments are grounded using data from the social networking service Twitter.com
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