Isolated oxygen defects in 3C- and 4H-SiC: A theoretical study

Ab initio calculations in the local-density approximation have been carried out in SiC to determine the possible configurations of the isolated oxygen impurity. Equilibrium geometry and occupation levels were calculated. Substitutional oxygen in 3C-SiC is a relatively shallow effective mass like double donor on the carbon site (O-C) and a hyperdeep double donor on the Si site (O-Si). In 4H-SiC O-C is still a double donor but with a more localized electron state. In 3C-SiC O-C is substantially more stable under any condition than O-Si or interstitial oxygen (O-i). In 4H-SiC O-C is also the most stable one except for heavy n-type doping. We propose that O-C is at the core of the electrically active oxygen-related defect family found by deep level transient spectroscopy in 4H-SiC. The consequences of the site preference of oxygen on the SiC/SiO2 interface are discussed

Terahertz Excitation of a Coherent -Type Three-Level System of Exciton-Polariton Modes in a Quantum-Well Microcavity

Interactions of few-cycle terahertz pulses with the induced optical polarization in a quantum-well microcavity reveal that the lower and higher exciton-polariton modes together with the optically forbidden 2p-exciton state form a unique Lambda-type three-level system. Pronounced nonlinearities are observed via time-resolved strong-terahertz and weak-optical excitation spectroscopy and explained with a fully microscopic theory. The results show that the terahertz pulses strongly couple the exciton-polariton states to the 2p-exciton state while no resonant transition between the two polariton levels is observed.Keywords: Semiconductor microcavities, Bose Einstein condensation, CotKeywords: Semiconductor microcavities, Bose Einstein condensation, Co

LINC-NIRVANA Commissioning at the Large Binocular Telescope - Lessons Learned

LINC-NIRVANA (LN) is one of the instruments on-board the Large Binocular Telescope (LBT). LN is a high- resolution, near-infrared imager equipped with an advanced adaptive optics module. LN implements layer- oriented Multi-Conjugate Adaptive Optics (MCAO) approach using two independent wavefront sensors per side of the binocular telescope measuring the turbulence volume above the telescope. The capability of acquiring up to 20 Natural Guide Stars simultaneously from two distinct fields of view, and using them for wavefront sensing with 20 separate pyramids per side of the telescope makes the LN MCAO system one of a kind. Commissioning of the left MCAO channel is almost complete, while that of the right arm is on-going. The Science Verification on the left side is expected to start soon after the MCAO performance is optimised for faint guide stars. In this article, we put together the lessons learned during the commissioning of the LN MCAO module. We hope and believe that this article will help the future MCAO instrument commissioning teams

Anaphylaxis in Elderly Patients-Data From the European Anaphylaxis Registry

Background: Elicitors and symptoms of anaphylaxis are age dependent. However, little is known about typical features of anaphylaxis in patients aged 65 years or more. Methods: The data from the Network for Online Registration of Anaphylaxis (NORA) considering patients aged ≥65 (elderly) in comparison to data from adults (18–64 years) regarding elicitors, symptoms, comorbidities, and treatment measures were analyzed. Results: We identified 1,123 elderly anaphylactic patients. Insect venoms were the most frequent elicitor in this group (p < 0.001), followed by drugs like analgesics and antibiotics. Food allergens elicited less frequently anaphylaxis (p < 0.001). Skin symptoms occurred less frequently in elderly patients (77%, p < 0.001). The clinical symptoms were more severe in the elderly (51% experiencing grade III/IV reactions), in particular when skin symptoms (p < 0.001) were absent. Most strikingly, a loss of consciousness (33%, p < 0.001) and preexisting cardiovascular comorbidity (59%, p < 0.001) were more prevalent in the elderly. Finally, adrenaline was used in 30% of the elderly (vs. 26% in the comparator group, p < 0.001) and hospitalization was more often required (60 vs. 50%, p < 0.001). Discussion and Conclusion: Anaphylaxis in the elderly is often caused by insect venoms and drugs. These patients suffer more often from cardiovascular symptoms, receive more frequently adrenaline and require more often hospitalization. The data indicate that anaphylaxis in the elderly tends to be more frequently life threatening and patients require intensified medical intervention. The data support the need to recognize anaphylaxis in this patient group, which is prone to be at a higher risk for a fatal outcome

Infidelity-Revealing Snapchat Messages Arouse Different Levels of Jealousy Depending on Sex, Type of Message and Identity of the Opposite Sex Rival

Research highlighting sex-differentiated jealousy resulting from imagined scenarios has now been reaffirmed when the infidelity-revealing message is discovered on a social media platform. Participants in the current study were presented with both sexually and emotionally charged infidelity-revealing scenarios featuring a same-sex sibling, a friend and a stranger in the format of a ‘Snapchat’ message. Men indicated significantly higher jealousy to sexual as opposed to emotional messages with the reverse pattern evident in women. Sex differences were also evident in the extent of jealousy elicited by ‘third-party’ identity. Women were significantly more jealous when the imagined infidelity occurred between their sister compared to both a best friend and a stranger with males showing significantly lower jealousy directed towards their brother compared to a stranger. These findings are supportive not only of a parental investment (PI) interpretation of sex differences in jealousy but also an interpretation consistent with aspects of inclusive fitness theory

Sexting, Mental Health, and Victimization Among Adolescents: A Literature Review

The practice of creating and sharing sexual images via technological devices, known as sexting, has received crescent attention in the past years, especially due to the increase of adolescent engagement in this behavior. Although consensual sexting is not prima facie a crime, as some research has shown, it has the potential to be a risky behavior, and a threshold to get exposure to dangerous kinds of victimization as sextortion, online grooming or cyberbullying. In this context, teenagers represent a vulnerable group due to their limited ability of self-regulation, their high susceptibility to peer pressure, their technophilia, and their growing sexual curiosity. The present paper aims to review the scientific literature to analyze the relationship between mental health and sexting as a potentially risky behavior and its association with online victimization. The results and implications will be discussed