Si IV Resonance Line Emission During Solar Flares: Non-LTE, Non-equilibrium, Radiation Transfer Simulations

The Interface Region Imaging Spectrograph (IRIS) routinely observes the Si IV resonance lines. When analyzing observations of these lines it has typically been assumed they form under optically thin conditions. This is likely valid for the quiescent Sun, but this assumption has also been applied to the more extreme flaring scenario. We used 36 electron beam driven radiation hydrodynamic solar flare simulations, computed using the RADYN code, to probe the validity of this assumption. Using these simulated atmospheres we solved the radiation transfer equations to obtain the non-LTE, non-equilibrium populations, line profiles, and opacities for a model Silicon atom, including charge exchange processes. This was achieved using the `minority species' version of RADYN. The inclusion of charge exchange resulted in a substantial fraction of Si IV at cooler temperatures than those predicted by ionisation equilibrium. All simulations with an injected energy flux $F>5\times10^{10}$ erg cm$^{-2}$ s$^{-1}$ resulted in optical depth effects on the Si IV emission, with differences in both intensity and line shape compared to the optically thin calculation. Weaker flares (down to $F\approx5\times10^{9}$ erg cm$^{-2}$ s$^{-1}$) also resulted in Si IV emission forming under optically thick conditions, depending on the other beam parameters. When opacity was significant, the atmospheres generally had column masses in excess of $5\times10^{-6}$ g cm$^{-2}$ over the temperature range $40$ to $100$ kK, and the Si IV formation temperatures were between $30$ and $60$ kK. We urge caution when analyzing Si IV flare observations, or when computing synthetic emission without performing a full radiation transfer calculation.Comment: Accepted in the Astrophysical Journal, 23 pages (3 appendices, 15 figures

Electron doped Ca10(Pt3As8)(Fe2As2)5 and Ca10(Pt4As8)(Fe2As2)5 - High Tc superconductors with skutterudite intermediary layers

It has been argued that the very high transition temperatures of the highest Tc cuprate superconductors are facilitated by enhanced CuO2 plane coupling through the (Bi,Tl,Hg)-O intermediary layers. Whether enhanced coupling through intermediary layers can also influence Tc in the iron arsenide superconductors has never been tested due the lack of appropriate systems for study. Here we report the crystal structures and properties of two iron arsenide superconductors, Ca10(Pt3As8)(Fe2As2)5 (the 10-3-8 phase) and Ca10(Pt4As8)(Fe2As2)5 (the 10-4-8 phase). Based on -Ca-(PtnAs8)-Ca-Fe2As2- layer stacking, the most important difference in the structures lies in the structural and electronic characters of the intermediary platinum arsenide layers. Electron doping through partial substitution of Pt for Fe in the Fe2As2 layers leads to Tc of 11 K in the 10-3-8 phase and 25 K in the 10-4-8 phase. Using the chemical concepts of Zintl ion electron counting and the stability of Pt in the 5d8 configuration we argue that the dramatic difference in Tc arises because the intermediary layer is semiconducting in the 10-3-8 phase but metallic in the 10-4-8 phase, leading to enhanced interlayer coupling in the 10-4-8 phase. The results suggest that metallic intermediary layers may offer a new road to higher Tc in iron arsenide superconductors

Elevated protein concentrations in newborn blood and the risks of autism spectrum disorder, and of social impairment, at age 10 years among infants born before the 28th week of gestation

Among the 1 of 10 children who are born preterm annually in the United States, 6% are born before the third trimester. Among children who survive birth before the 28th week of gestation, the risks of autism spectrum disorder (ASD) and non-autistic social impairment are severalfold higher than in the general population. We examined the relationship between top quartile inflammation-related protein concentrations among children born extremely preterm and ASD or, separately, a high score on the Social Responsiveness Scale (SRS total score ≥65) among those who did not meet ASD criteria, using information only from the subset of children whose DAS-II verbal or non-verbal IQ was ≥70, who were assessed for ASD, and who had proteins measured in blood collected on ≥2 days (N = 763). ASD (N = 36) assessed at age 10 years is associated with recurrent top quartile concentrations of inflammation-related proteins during the first post-natal month (e.g., SAA odds ratio (OR); 95% confidence interval (CI): 2.5; 1.2–5.3) and IL-6 (OR; 95% CI: 2.6; 1.03–6.4)). Top quartile concentrations of neurotrophic proteins appear to moderate the increased risk of ASD associated with repeated top quartile concentrations of inflammation-related proteins. High (top quartile) concentrations of SAA are associated with elevated risk of ASD (2.8; 1.2–6.7) when Ang-1 concentrations are below the top quartile, but not when Ang-1 concentrations are high (1.3; 0.3–5.8). Similarly, high concentrations of TNF-α are associated with heightened risk of SRS-defined social impairment (N = 130) (2.0; 1.1–3.8) when ANG-1 concentrations are not high, but not when ANG-1 concentrations are elevated (0.5; 0.1–4.2)

Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe (Fe1+dSe)

The recently discovered iron arsenide superconductors, which display superconducting transition temperatures as high as 55 K, appear to share a number of general features with high-Tc cuprates, including proximity to a magnetically ordered state and robustness of the superconductivity in the presence of disorder. Here we show that superconductivity in Fe1+dSe, the parent compound of the superconducting arsenide family, is destroyed by very small changes in stoichiometry. Further, we show that non-superconducting Fe1+dSe is not magnetically ordered down to low temperatures. These results suggest that robust superconductivity and immediate instability against an ordered magnetic state should not be considered as intrinsic characteristics of iron-based superconducting systems, and that Fe1+dSe may present a unique opportunity for determining which materials characteristics are critical to the existence of superconductivity in high Tc iron arsenide superconductors and which are not.Comment: Updated to reflect final version and include journal referenc

Behavioural dysfunctions of 10-year-old children born extremely preterm associated with corticotropin-releasing hormone expression in the placenta

AIM: To evaluate the relationship between corticotropin-releasing hormone (CRH) expression in the placenta and the risk of school-related dysfunctions at the age of 10 years among children born extremely preterm (EP). METHODS: Corticotropin-releasing hormone expression was measured in the placenta of 761 EP children, who had the following assessments at the age of 10 years: Differential Ability Scales, Oral and Written Language Scales, the Wechsler Individual Achievement Test-III, NEPSY-II and the Child Symptom Inventory-4. We evaluated whether lowest and highest quartiles of CRH mRNA were associated with undesirable scores on these assessments. With 272 evaluations, we would expect 14 to be significant at p < 0.05. RESULTS: Only 16 associations were statistically significant. On the other hand, seven of these were social limitations among girls whose placenta CRH mRNA was in the top quartile. Adjusting for delivery indication or restricting the sample to one delivery indication group resulted in few differences. CONCLUSION: Overall, placenta CRH mRNA concentrations in the top or bottom quartiles were not associated with increased risks of dysfunctions 10 years later. Girls whose placenta CRH expression was in the top quartile, however, were at increased risk of seven indicators/correlates of social limitations

Descriptive Analysis of a Baseline Concussion Battery Among U.S. Service Academy Members: Results from the Concussion Assessment, Research, and Education (CARE) Consortium

Introduction The prevalence and possible long-term consequences of concussion remain an increasing concern to the U.S. military, particularly as it pertains to maintaining a medically ready force. Baseline testing is being used both in the civilian and military domains to assess concussion injury and recovery. Accurate interpretation of these baseline assessments requires one to consider other influencing factors not related to concussion. To date, there is limited understanding, especially within the military, of what factors influence normative test performance. Given the significant physical and mental demands placed on service academy members (SAM), and their relatively high risk for concussion, it is important to describe demographics and normative profile of SAMs. Furthermore, the absence of available baseline normative data on female and non-varsity SAMs makes interpretation of post-injury assessments challenging. Understanding how individuals perform at baseline, given their unique individual characteristics (e.g., concussion history, sex, competition level), will inform post-concussion assessment and management. Thus, the primary aim of this manuscript is to characterize the SAM population and determine normative values on a concussion baseline testing battery. Materials and Methods All data were collected as part of the Concussion Assessment, Research and Education (CARE) Consortium. The baseline test battery included a post-concussion symptom checklist (Sport Concussion Assessment Tool (SCAT), psychological health screening inventory (Brief Symptom Inventory (BSI-18) and neurocognitive evaluation (ImPACT), Balance Error Scoring System (BESS), and Standardized Assessment of Concussion (SAC). Linear regression models were used to examine differences across sexes, competition levels, and varsity contact levels while controlling for academy, freshman status, race, and previous concussion. Zero inflated negative binomial models estimated symptom scores due to the high frequency of zero scores. Results Significant, but small, sex effects were observed on the ImPACT visual memory task. While, females performed worse than males (p < 0.0001, pη2 = 0.01), these differences were small and not larger than the effects of the covariates. A similar pattern was observed for competition level on the SAC. There was a small, but significant difference across competition level. SAMs participating in varsity athletics did significantly worse on the SAC compared to SAMs participating in club or intramural athletics (all p’s < 0.001, η2 = 0.01). When examining symptom reporting, males were more than two times as likely to report zero symptoms on the SCAT or BSI-18. Intramural SAMs had the highest number of symptoms and severity compared to varsity SAMs (p < 0.0001, Cohen’s d < 0.2). Contact level was not associated with SCAT or BSI-18 symptoms among varsity SAMs. Notably, the significant differences across competition level on SCAT and BSI-18 were sub-clinical and had small effect sizes. Conclusion The current analyses provide the first baseline concussion battery normative data among SAMs. While statistically significant differences may be observed on baseline tests, the effect sizes for competition and contact levels are very small, indicating that differences are likely not clinically meaningful at baseline. Identifying baseline differences and significant covariates is important for future concussion-related analyses to inform concussion evaluations for all athlete levels

Neurocognitive function of 10-year-old multiples born less than 28 weeks of gestational age

Introduction Few studies have examined the relationship between birth plurality and neurocognitive function among children born extremely preterm. Study design We compared rates of Z-scores ≤−2 on 18 tests of neurocognitive function and academic achievement at age 10 years in 245 children arising from twin pregnancies, 55 from triplet pregnancies, and 6 from a septuplet pregnancy to that of 568 singletons, all of whom were born before the 28th week of gestation. Results In total, 874 children were evaluated at the age of 10 years. After adjusting for confounders, children of multifetal pregnancies performed significantly better on one of six subtests of executive function than their singleton peers. Performance was similar on all other assessments of intelligence, language, academic achievement, processing speed, visual perception, and fine motor skills. Conclusion We found no evidence that children born of multifetal pregnancies had worse scores than their singleton peers on assessments of neurocognitive and academic function

Hand Preference and Cognitive, Motor, and Behavioral Functioning in 10-Year-Old Extremely Preterm Children

The association of hand preference (left, mixed, and right) with cognitive, academic, motor, and behavioral function was evaluated in 864 extremely preterm children at 10 years of age. Left-handed and right-handed children performed similarly but mixed-handed children had greater odds of functional deficits across domains than right-handed children

Antecedents of epilepsy and seizures among children born at extremely low gestational age

ObjectiveTo identify specific risk factors for epilepsy for individuals born extremely preterm.Study DesignIn a prospective cohort study, at 10-year follow-up, children were classified as having epilepsy or seizures not associated with epilepsy. We evaluated for association of perinatal factors using time-oriented, multinomial logistic regression models.ResultsOf the 888 children included in the study, 66 had epilepsy and 39 had seizures not associated with epilepsy. Epilepsy was associated with an indicator of low socioeconomic status, maternal gestational fever, early physiologic instability, postnatal exposure to hydrocortisone, cerebral white matter disease and severe bronchopulmonary dysplasia. Seizure without epilepsy was associated with indicators of placental infection and inflammation, and hypoxemia during the first 24 postnatal hours.ConclusionsIn children born extremely preterm, epilepsy and seizures not associated with epilepsy have different risk profiles. Though both profiles included indicators of infection and inflammation, the profile of risk factors for epilepsy included multiple indicators of endogenous vulnerability

The role of traditional livelihood practices and local ethnobotanical knowledge in mitigating chestnut disease and pest severity in Turkey

The European chestnut population is enduring multiple compounding exotic pest and disease outbreaks across Turkey. The deeply held value of the chestnut species for the Turkish public is reflected in substantial government conservation programming. Chestnut is predominantly found on state land managed by Turkey’s General Directorate of Forestry (GDF), which generally upholds restrictive policies for chestnut-related livelihood practices other than nut collection and beehive placement. Such policies are justified by a government position that human activities and presence is likely to worsen disease dynamics. Conversely, a growing body of research findings testify that small-scale livelihood practices maintain biological diversity and, furthermore, that this traditional maintenance of diversity has been correlated with decreased pathogen pressure within agroecosystems. However, few studies have investigated this phenomenon in the context of agroforestry systems. At a global ecological moment of increasingly pervasive and severe exotic forest pathogen impact, this paper investigates the influence of diverse small-scale livelihood practices and knowledge on chestnut tree health across the highly heterogenous geography of Turkey. We conducted ethnobotanical questionnaires with 96 chestnut-utilizing households, and chestnut tree health evaluations in georeferenced forest areas they identified, throughout Turkey’s Black Sea, Marmara, and Aegean regions. Using data from 1500 trees, we characterized the effects of subsequently recorded environmental, physiological, and anthropogenic factors on tree health using multiple correspondence analysis (MCA), multiple factor analysis (MFA), and mixed models. Our results show that the traditional human management of tree physiology and ecology has a significant positive effect on tree health, especially through the acts of grafting and culling as well as the maintenance of diversity. We argue that conceptualizing such livelihood systems as human niche construction and maintenance can help forest management agencies to better understand and conserve valuable landscapes, even in increasingly common periods of severe pathogenic pressure