Onset of implant-related recombination in self-ion implanted and annealed crystalline silicon

The impact of residual recombination centers after low-energy self-implantation of crystalline silicon wafers and annealing at 900 °C has been determined by bulk carrier lifetime measurements as a function of implant dose. Doses below 10¹³cm⁻² resulted in no measurable increase in recombination, while higher doses caused a linear increase in the recombination center density. This threshold value corresponds to the known critical dose required for the formation of relatively stable dislocation loops during high temperature annealing.Deep level transient spectroscopy revealed a decrease in the vacancy-related defect concentration in the high-dose samples, which we interpret as reflecting an increase in the siliconinterstitial concentration. This suggests that siliconinterstitials, arising from the slowly dissolving dislocation loops, may be responsible for the increased recombination deep within the samples.This work has been supported by the Australian Research Council

Enhanced pre-frontal functional-structural networks to support postural control deficits after traumatic brain injury in a pediatric population

Traumatic brain injury (TBI) affects the structural connectivity, triggering the re-organization of structural-functional circuits in a manner that remains poorly understood. We focus here on brain networks re-organization in relation to postural control deficits after TBI. We enrolled young participants who had suffered moderate to severeTBI, comparing them to young typically developing control participants. In comparison to control participants, TBI patients (but not controls) recruited prefrontal regions to interact with two separated networks: 1) a subcortical network including part of the motor network, basal ganglia, cerebellum, hippocampus, amygdala, posterior cingulum and precuneus; and 2) a task-positive network, involving regions of the dorsal attention system together with the dorsolateral and ventrolateral prefrontal regions

Machine Learning for RANS Turbulence Modelling of Variable Property Flows

This paper presents a machine learning methodology to improve the predictions of traditional RANS turbulence models in channel flows subject to strong variations in their thermophysical properties. The developed formulation contains several improvements over the existing Field Inversion Machine Learning (FIML) frameworks described in the literature, as well as the derivation of a new modelling technique. We first showcase the use of efficient optimization routines to automatize the process of field inversion in the context of CFD, combined with the use of symbolic algebra solvers to generate sparse-efficient algebraic formulas to comply with the discrete adjoint method. The proposed neural network architecture is characterized by the use of an initial layer of logarithmic neurons followed by hyperbolic tangent neurons, which proves numerically stable. The machine learning predictions are then corrected using a novel weighted relaxation factor methodology, that recovers valuable information from otherwise spurious predictions. The study uses the K-fold cross-validation technique, which is beneficial for small datasets. The results show that the machine learning model acts as an excellent non-linear interpolator for DNS cases well-represented in the training set, and that moderate improvement margins are obtained for sparser DNS cases. It is concluded that the developed machine learning methodology corresponds to a valid alternative to improve RANS turbulence models in flows with strong variations in their thermophysical properties without introducing prior modeling assumptions into the system

Minimized extracorporeal circulation is improving outcome of coronary artery bypass surgery in the elderly

Advanced age is a known risk factor for morbidity and mortality after coronary artery bypass grafting (CABG). Minimized extracorporeal circulation (MECC) has been shown to reduce the negative effects associated with conventional extracorporeal circulation (CECC). This trial assesses the impact of MECC on the outcome of elderly patients undergoing CABG. Eight hundred and seventy-five patients (mean age 78.35 years) underwent isolated CABG using CECC (n=345) or MECC (n=530). The MECC group had a significantly shorter extracorporeal circulation time (ECCT), cross-clamp time and reperfusion time and lower transfusion needs. Postoperatively, these patients required significantly less inotropic support, fewer blood transfusions, less postoperative hemodialysis and developed less delirium compared to CECC patients. In the MECC group, intensive care unit (ICU) stay was significantly shorter and 30-day mortality was significantly reduced [2.6% versus 7.8%; p<0.001]. In conclusion, MECC improves outcome in elderly patients undergoing CABG surgery

Mutation of vsx genes in zebrafish highlights the robustness of the retinal specification network

Genetic studies in human and mice have established a dual role for Vsx genes in retina development: an early function in progenitors' specification, and a later requirement for bipolar-cells fate determination. Despite their conserved expression patterns, it is currently unclear to which extent Vsx functions are also conserved across vertebrates, as mutant models are available only in mammals. To gain insight into vsx function in teleosts, we have generated vsx1 and vsx2 CRISPR/Cas9 double knockouts (vsxKO) in zebrafish. Our electrophysiological and histological analyses indicate severe visual impairment and bipolar cells depletion in vsxKO larvae, with retinal precursors being rerouted toward photoreceptor or Müller glia fates. Surprisingly, neural retina is properly specified and maintained in mutant embryos, which do not display microphthalmia. We show that although important cis-regulatory remodelling occurs in vsxKO retinas during early specification, this has little impact at a transcriptomic level. Our observations point to genetic redundancy as an important mechanism sustaining the integrity of the retinal specification network, and to Vsx genes regulatory weight varying substantially among vertebrate species

High critical current density and enhanced pinning in superconducting films of YBa2Cu3O7-δ nanocomposites with embedded BaZrO3, BaHfO3, BaTiO3, and SrZrO3 nanocrystals

Chemical solution deposition (CSD) of YBa2Cu3O7−δ (YBCO) nanocomposites from colloidal precursor solutions containing double metal oxide preformed nanocrystals is a promising, cost effective and reproducible approach to produce superconducting films with high critical current density (Jc) and enhanced pinning. Here, the influence of the preformed nanocrystal composition on the microstructure and superconducting properties of the YBCO nanocomposite films is studied, with a focus on establishing a simple and scalable process to grow nanocomposites that can be transferred to grow nano-added coated conductors. Colloidal stable BaZrO3, BaHfO3, BaTiO3 and SrZrO3 nanocrystals (3-6 nm in diameter) were synthesized and added to an environment-friendly low-fluorine YBCO precursor solution. High-quality superconducting layers were grown on LaAlO3 single-crystal substrates from these four nanocomposite precursor solutions in a single deposition process, without the need of a seed layer, yielding Jc of 4-5 MA/cm² at 77 K in self-field. The different YBCO microstructures produced by the four types of nanocrystals and the resulting microstrain of the films are compared and related with the magnetic-field and angular dependence of Jc. We demonstrate the BaHfO3-containing nanocomposite as the best-performing with a homogeneous distribution of nanoparticles with 7 nm in average diameter and a high density of stacking faults, which leads to some of the best superconducting properties ever achieved via low-fluorine CSD. The Jc exhibits a much smoother decay in applied magnetic fields and a much more isotropic behaviour for non-parallel magnetic fields, and the pinning force is increased by a factor of 3.5 at 77 K and 1 T with respect to the pristine film

Development, psychometric validation, and cross-cultural comparison of the “Instagram Motives Questionnaire” (IMQ) and the “Instagram Uses and Patterns Questionnaire” (IUPQ)

Background and aims Social network use is widespread, and the study of Instagram seems to have captured more attention in recent years. However, scale development and validation in the field has fallen short of providing sound scales of Instagram motives and usage patterns that consider the uniqueness of Instagram-related behavior. This paper describes the development, psychometric and cross-cultural validation of two new measurement instruments: the “Instagram Motives Questionnaire” (IMQ) and the “Instagram Uses and Patterns Questionnaire” (IUPQ). Methods and results A preliminary set of items was developed for each questionnaire based on a previous qualitative interview study on Instagram motives, uses, and consequences. In the first study, the questionnaires were distributed to a sample of 312 participants aged 18–35 years (M = 23.81; SD = 4.49), and an exploratory factor analysis was performed. A parsimonious and interpretable 6-factor solution that displayed adequate factor loadings and adequate Omega coefficients for both instruments were found. In a second study, the two instruments and other measures of known social network usage correlates and mental health consequences were administered online to 1,418 English-speaking participants aged 18–34 years (M = 21.35; SD = 3.89). Both scales showed good psychometric properties and the factor structure identified in study 1 was reproduced through confirmatory factor analysis. Omega reliability coefficients were adequate. Finally, when performing multi-group CFA along with a French (n = 1,826) and a Spanish (n = 3,040) sample, language and gender invariance were supported. Correlations with other relevant measures indicate good convergent validity of both scales. Conclusions The present research provides psychometrically sound instruments for further investigations on Instagram use behaviors

Naive tumor-specific CD4+ T cells differentiated in vivo eradicate established melanoma

In vitro differentiated CD8+ T cells have been the primary focus of immunotherapy of cancer with little focus on CD4+ T cells. Immunotherapy involving in vitro differentiated T cells given after lymphodepleting regimens significantly augments antitumor immunity in animals and human patients with cancer. However, the mechanisms by which lymphopenia augments adoptive cell therapy and the means of properly differentiating T cells in vitro are still emerging. We demonstrate that naive tumor/self-specific CD4+ T cells naturally differentiated into T helper type 1 cytotoxic T cells in vivo and caused the regression of established tumors and depigmentation in lymphopenic hosts. Therapy was independent of vaccination, exogenous cytokine support, CD8+, B, natural killer (NK), and NKT cells. Proper activation of CD4+ T cells in vivo was important for tumor clearance, as naive tumor-specific CD4+ T cells could not completely treat tumor in lymphopenic common gamma chain (γc)–deficient hosts. γc signaling in the tumor-bearing host was important for survival and proper differentiation of adoptively transferred tumor-specific CD4+ T cells. Thus, these data provide a platform for designing immunotherapies that incorporate tumor/self-reactive CD4+ T cells