33 research outputs found

    Out-of-equilibrium quantum fields with conserved charge

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    We study the out-of-equilibrium evolution of an O(2)-invariant scalar field in which a conserved charge is stored. We apply a loop expansion of the 2-particle irreducible effective action to 3-loop order. Equations of motion are derived which conserve both total charge and total energy yet allow for the effects of scattering whereby charge and energy can transfer between modes. Working in (1+1)-dimensions we solve the equations of motion numerically for a system knocked out of equilibrium by a sudden temperature quench. We examine the initial stages of the charge and energy redistribution. This provides a basis from which we can understand the formation of Bose-Einstein condensates from first principles.Comment: 11 pages, 5 figures, replacement with improved presentatio

    Effect of Key2Teach on Dutch teachers' relationships with students with externalizing problem behavior:A randomized controlled trial

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    The teacher-student relationship plays an important role in the academic and behavioral development of primary school children with externalizing problem behavior. However, such problem behavior often threatens the quality of the teacher-student relationship. Teacher-focused coaching intervention Key2Teach aims to improve elements of the relationship between teachers and students with externalizing problem behavior and consists of two phases and four building blocks. This intervention provides primary school teachers with insight into their mental representation of the relationship and opportunities to practice functional interaction skills. In a randomized controlled trial (RCT), effects of Key2Teach on different aspects of the relationship between teachers and students with externalizing problem behavior were examined. In two cohorts, 103 dyads consisting of a teacher and a student with externalizing problem behavior in grades 3-6 were assessed three times during a school year. Fifty-three dyads received the intervention (intervention group), whereas 50 dyads received no intervention (control group). Data were collected on teacher-reported teacher-student closeness and conflict, and on teacher interaction skills in various domains. Results show a significant increase in closeness and a decrease in conflict as a result of Key2Teach, with substantial effect sizes. No effects on teacher interaction skills were found. This study indicates that Key2Teach may help teachers to improve elements of the relationship they have with students with externalizing problem behavior. Implications for practice and future research are discussed

    Effective Finite Temperature Partition Function for Fields on Non-Commutative Flat Manifolds

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    The first quantum correction to the finite temperature partition function for a self-interacting massless scalar field on a D−D-dimensional flat manifold with pp non-commutative extra dimensions is evaluated by means of dimensional regularization, suplemented with zeta-function techniques. It is found that the zeta function associated with the effective one-loop operator may be nonregular at the origin. The important issue of the determination of the regularized vacuum energy, namely the first quantum correction to the energy in such case is discussed.Comment: amslatex, 14 pages, to appear in Phys. Rev.

    Experimental progress in positronium laser physics

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    New genetic loci implicated in fasting glucose homeostasis and their impact on type 2 diabetes risk

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    Levels of circulating glucose are tightly regulated. To identify new loci influencing glycemic traits, we performed meta-analyses of 21 genome-wide association studies informative for fasting glucose, fasting insulin and indices of beta-cell function (HOMA-B) and insulin resistance (HOMA-IR) in up to 46,186 nondiabetic participants. Follow-up of 25 loci in up to 76,558 additional subjects identified 16 loci associated with fasting glucose and HOMA-B and two loci associated with fasting insulin and HOMA-IR. These include nine loci newly associated with fasting glucose (in or near ADCY5, MADD, ADRA2A, CRY2, FADS1, GLIS3, SLC2A2, PROX1 and C2CD4B) and one influencing fasting insulin and HOMA-IR (near IGF1). We also demonstrated association of ADCY5, PROX1, GCK, GCKR and DGKB-TMEM195 with type 2 diabetes. Within these loci, likely biological candidate genes influence signal transduction, cell proliferation, development, glucose-sensing and circadian regulation. Our results demonstrate that genetic studies of glycemic traits can identify type 2 diabetes risk loci, as well as loci containing gene variants that are associated with a modest elevation in glucose levels but are not associated with overt diabetes

    NeRF for 3D Reconstruction from X-ray Angiography:Possibilities and Limitations

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    Neural Radiance Field (NeRF) is a promising deep learning technique based on neural rendering for three-dimensional (3D) reconstruction. This technique has overcome several limitations of 3D reconstruction techniques, such as removing the need for 3D ground truth or two-dimensional (2D) segmentations. In the medical context, the 3D reconstruction of vessels from 2D X-ray angiography is a relevant problem. For example, the treatment of coronary arteries could still benefit from 3D reconstruction solutions, as common solutions do not suffice. Challenging areas in the 3D reconstruction from X-ray angiography are the vessel morphology characteristics, such as sparsity, overlap, and the distinction between foreground and background. Moreover, sparse view and limited angle X-ray projections restrict the information available for the 3D reconstructions. Many traditional and machine learning methods have been proposed, but they rely on demanding user interactions or require large amounts of training data. NeRF could solve these limitations, given that promising results have been shown for medical (X-ray) applications. However, to the best of our knowledge, no results have been shown with X-ray angiography projections or consider the vessel morphology characteristics. This paper explores the possibilities and limitations of using NeRF for 3D reconstruction from X-ray angiography. An extensive experimental analysis is conducted to quantitatively and qualitatively evaluate the effects of the X-ray angiographic challenges on the reconstruction quality. We demonstrate that NeRF has the potential for 3D X-ray angiography reconstruction (e.g., reconstruction with sparse and limited angle X-ray projections) but also identify explicit limitations (e.g., the overlap of background structures) that must be addressed in future works.</p

    Effect of Key2Teach on Dutch teachers’ relationships with students with externalizing problem behavior: a randomized controlled trial

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    The teacher-student relationship plays an important role in the academic and behavioral development of primary school children with externalizing problem behavior. However, such problem behavior often threatens the quality of the teacher-student relationship. Teacher-focused coaching intervention Key2Teach aims to improve elements of the relationship between teachers and students with externalizing problem behavior and consists of two phases and four building blocks. This intervention provides primary school teachers with insight into their mental representation of the relationship and opportunities to practice functional interaction skills. In a randomized controlled trial (RCT), effects of Key2Teach on different aspects of the relationship between teachers and students with externalizing problem behavior were examined. In two cohorts, 103 dyads consisting of a teacher and a student with externalizing problem behavior in grades 3–6 were assessed three times during a school year. Fifty-three dyads received the intervention (intervention group), whereas 50 dyads received no intervention (control group). Data were collected on teacher-reported teacher-student closeness and conflict, and on teacher interaction skills in various domains. Results show a significant increase in closeness and a decrease in conflict as a result of Key2Teach, with substantial effect sizes. No effects on teacher interaction skills were found. This study indicates that Key2Teach may help teachers to improve elements of the relationship they have with students with externalizing problem behavior. Implications for practice and future research are discussed
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