Effect of annealing on the depth profile of hole concentration in (Ga,Mn)As

The effect of annealing at 250 C on the carrier depth profile, Mn distribution, electrical conductivity, and Curie temperature of (Ga,Mn)As layers with thicknesses > 200 nm, grown by molecular-beam epitaxy at low temperatures, is studied by a variety of analytical methods. The vertical gradient in hole concentration, revealed by electrochemical capacitance-voltage profiling, is shown to play a key role in the understanding of conductivity and magnetization data. The gradient, basically already present in as-grown samples, is strongly influenced by post-growth annealing. From secondary ion mass spectroscopy it can be concluded that, at least in thick layers, the change in carrier depth profile and thus in conductivity is not primarily due to out-diffusion of Mn interstitials during annealing. Two alternative possible models are discussed.Comment: 8 pages, 8 figures, to appear in Phys. Rev.

Calibration Of The Johnson–Cook Model At High Temperatures For An Ultra-High Strength CrNiMoV Steel

This paper presents a study on the thermo-mechanical behavior of an ultra-high strength CrNiMoV steel at high temperatures and medium strain rates through hot tensile tests. The material was examined in two conditions: as-cast/heat-treated (AC/HT) and as-rolled (AR). Tensile tests were conducted at temperatures of 800,900,1000,1100, and 1200°C, and strain rates of 0.1,1, and 10s−1. Inclusion and porosity analysis was also performed on the tensile specimens. The results revealed that the flow stress decreased by approximately 70% on average from 800°C to 1200°C, while increasing by approximately 32% on average from 0.1s−1 to 10s−1 in strain rate. The elongation exhibited an increase from 16.5% at 800°C to 33% at 1200°C. However, the ductility transition was slower than expected, particularly for the AC/HT conditions. The AC/HT samples exhibited higher levels of inclusions and porosity compared to the AR samples, with porosity significantly affecting the elongation to failure and ultimate tensile strength (UTS) at a strain rate of 1s−1. Furthermore, calibrated Johnson–Cook parameters were reported and compared, demonstrating excellent agreement between predicted and experimental values with less than 20% variation. The calibrated Johnson–Cook model can be effectively employed for modeling purposes within the studied temperature range, and its application can even be extrapolated for higher strain rates

Advanced resistivity model for arbitrary magnetization orientation applied to a series of compressive- to tensile-strained (Ga,Mn)As layers

The longitudinal and transverse resistivities of differently strained (Ga,Mn)As layers are theoretically and experimentally studied as a function of the magnetization orientation. The strain in the series of (Ga,Mn)As layers is gradually varied from compressive to tensile using (In,Ga)As templates with different In concentrations. Analytical expressions for the resistivities are derived from a series expansion of the resistivity tensor with respect to the direction cosines of the magnetization. In order to quantitatively model the experimental data, terms up to the fourth order have to be included. The expressions derived are generally valid for any single-crystalline cubic and tetragonal ferromagnet and apply to arbitrary surface orientations and current directions. The model phenomenologically incorporates the longitudinal and transverse anisotropic magnetoresistance as well as the anomalous Hall effect. The resistivity parameters obtained from a comparison between experiment and theory are found to systematically vary with the strain in the layer.Comment: 14 pages, 11 figures, submitted to Phys. Rev.

The electric double layer has a life of its own

Using molecular dynamics simulations with recently developed importance sampling methods, we show that the differential capacitance of a model ionic liquid based double-layer capacitor exhibits an anomalous dependence on the applied electrical potential. Such behavior is qualitatively incompatible with standard mean-field theories of the electrical double layer, but is consistent with observations made in experiment. The anomalous response results from structural changes induced in the interfacial region of the ionic liquid as it develops a charge density to screen the charge induced on the electrode surface. These structural changes are strongly influenced by the out-of-plane layering of the electrolyte and are multifaceted, including an abrupt local ordering of the ions adsorbed in the plane of the electrode surface, reorientation of molecular ions, and the spontaneous exchange of ions between different layers of the electrolyte close to the electrode surface. The local ordering exhibits signatures of a first-order phase transition, which would indicate a singular charge-density transition in a macroscopic limit

Assessing the Feasibility of a Peer Education Project to Improve Mental Health Literacy in Adolescents in the UK

This is the final version. Available on open access from Springer via the DOI in this recordMany mental health problems begin in adolescence and occur on a spectrum of severity: early recognition and intervention is important. This study is a quantitative feasibility study of the Mental Health Foundation’s Peer Education Project (PEP). Attrition, psychometric properties of questionnaires, indications of improvement on a range of outcomes, and sample size required for a powered trial of effectiveness were assessed. 203 students completed the survey both pre and post-intervention. It was found that existing previously-validated measures had good psychometric properties, with two new questionnaires demonstrating reasonable reliability (self-help confidence alpha = 0.78, mental health knowledge alpha = 0.59). There were indications of improvement in help-seeking intentions, the number of sources likely to seek help from, and mental health knowledge from pre- to post-intervention. A future trial of PEP with a sample of approximately 36 schools, researcher-led data collections, and help-seeking intentions or sources as a primary outcome appears to be feasible.National Institute for Health Research (NIHR

Parental transfer of the antimicrobial protein LBP/BPI protects Biomphalaria glabrata eggs against oomycete infections

Copyright: © 2013 Baron et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was funded by ANR (ANR-07-BLAN-0214 and ANR-12-EMMA-00O7-01), CNRS and INRA. PvW was financially supported by the BBSRC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Thermodynamic analysis of 5′ and 3′ single- and 3′ double-nucleotide overhangs neighboring wobble terminal base pairs

Thermodynamic parameters are reported for duplex formation of 40 self-complementary RNA duplexes containing wobble terminal base pairs with all possible 3′ single and double-nucleotide overhangs, mimicking the structures of short interfering RNAs (siRNA) and microRNAs (miRNA). Based on nearest neighbor analysis, the addition of a single 3′ dangling nucleotide increases the stability of duplex formation up to 1 kcal/mol in a sequence-dependent manner. The addition of a second dangling nucleotide increases the stability of duplexes closed with wobble base pairs in an idiosyncratic manner. The results allow for the development of a nearest neighbor model, which improves the predication of free energy and melting temperature for duplexes closed by wobble base pairs with 3′ single or double-nucleotide overhangs. Phylogenetic analysis of naturally occurring miRNAs was performed. Selection of the effector miR strand of the mature miRNA duplex appears to be dependent on the orientation of the GU closing base pair rather than the identity of the 3′ double-nucleotide overhang. Thermodynamic parameters for the 5′ single terminal overhangs adjacent to wobble closing base pairs are also presented

Key dimensions of women’s and their partners’ experiences of childbirth: A systematic review of reviews of qualitative studies

Background The World Health Organization 2018 intrapartum guideline for a positive birth experience emphasized the importance of maternal emotional and psychological well-being during pregnancy and the need for safe childbirth. Today, in many countries birth is safe, yet many women report negative and traumatic birth experiences, with adverse effects on their and their families’ well-being. Many reviews have attempted to understand the complexity of women’s and their partners’ birth experience; however, it remains unclear what the key dimensions of the birth experience are. Objective To synthesize the information from reviews of qualitative studies on the experience of childbirth in order to identify key dimensions of women’s and their partners’ childbirth experience. Methods Systematic database searches yielded 40 reviews, focusing either on general samples or on specific modes of birth or populations, altogether covering primary studies from over 35,000 women (and >1000 partners) in 81 countries. We appraised the reviews’ quality, extracted data and analysed it using thematic analysis. Findings Four key dimensions of women’s and partners’ birth experience (covering ten subthemes), were identified: 1) Perceptions, including attitudes and beliefs; 2) Physical aspects, including birth environment and pain; 3) Emotional challenges; and 4) Relationships, with birth companions and interactions with healthcare professionals. In contrast with the comprehensive picture that arises from our synthesis, most reviews attended to only one or two of these dimensions. Conclusions The identified key dimensions bring to light the complexity and multidimensionality of the birth experience. Within each dimension, pathways leading towards negative and traumatic birth experiences as well as pathways leading to positive experiences become tangible. Identifying key dimensions of the birth experience may help inform education and research in the field of birth experiences and gives guidance to practitioners and policy makers on how to promote positive birth experiences for women and their partners

Watson–Crick and Sugar-Edge Base Pairing of Cytosine in the Gas Phase: UV and Infrared Spectra of Cytosine·2-Pyridone

While keto-amino cytosine is the dominant species in aqueous solution, spectroscopic studies in molecular beams and in noble gas matrices show that other cytosine tautomers prevail in apolar environments. Each of these offers two or three H-bonding sites (Watson–Crick, wobble, sugar-edge). The mass- and isomer-specific S1 ← S0 vibronic spectra of cytosine·2-pyridone (Cyt·2PY) and 1-methylcytosine·2PY are measured using UV laser resonant two-photon ionization (R2PI), UV/UV depletion, and IR depletion spectroscopy. The UV spectra of the Watson–Crick and sugar-edge isomers of Cyt·2PY are separated using UV/UV spectral hole-burning. Five different isomers of Cyt·2PY are observed in a supersonic beam. We show that the Watson–Crick and sugar-edge dimers of keto-amino cytosine with 2PY are the most abundant in the beam, although keto-amino-cytosine is only the third most abundant tautomer in the gas phase. We identify the different isomers by combining three different diagnostic tools: (1) methylation of the cytosine N1–H group prevents formation of both the sugar-edge and wobble isomers and gives the Watson–Crick isomer exclusively. (2) The calculated ground state binding and dissociation energies, relative gas-phase abundances, excitation and the ionization energies are in agreement with the assignment of the dominant Cyt·2PY isomers to the Watson–Crick and sugar-edge complexes of keto-amino cytosine. (3) The comparison of calculated ground state vibrational frequencies to the experimental IR spectra in the carbonyl stretch and NH/OH/CH stretch ranges strengthen this identification