A measurement of the spectrum of cosmic ray electrons between 20 MeV and 4 BeV in 1968 - Further evidence for extensive time variations of this component

Cosmic ray electron intensity and spectrum measurements between 20 MeV and 4 BeV - 196

An embedding technique for the solution of reaction-fiffusion equations on algebraic surfaces with isolated singularities

In this paper we construct a parametrization-free embedding technique for numerically evolving reaction-diffusion PDEs defined on algebraic curves that possess an isolated singularity. In our approach, we first desingularize the curve by appealing to techniques from algebraic geometry.\ud We create a family of smooth curves in higher dimensional space that correspond to the original curve by projection. Following this, we pose the analogous reaction-diffusion PDE on each member of this family and show that the solutions (their projection onto the original domain) approximate the solution of the original problem. Finally, we compute these approximants numerically by applying the Closest Point Method which is an embedding technique for solving PDEs on smooth surfaces of arbitrary dimension or codimension, and is thus suitable for our situation. In addition, we discuss the potential to generalize the techniques presented for higher-dimensional surfaces with multiple singularities

An investigation into the effects of early propping removal on the deflection of reinforced concrete beams

In today’s fast paced construction industry, there is an ever present need to increase productivity and to complete projects as quickly as possible. Reinforced concrete is a popular and widely used construction material. However it has the unfortunate drawback in that the concrete requires time to set and gain sufficient strength before loads may be applied and the formwork and props can be removed. It is therefore desirable to keep propping times to a minimum. If the propping is removed too early, there is a risk of the member deflecting excessively and exceeding the maximum allowable limits, or in severe cases it could even lead to a structural failure or collapse. The SANS 2001 code provides recommended propping times for beams and slabs, which can be used as a guideline by building contractors and structural designers. These propping times present a universal approach, which does not consider all the factors that affect deflection. This simplified approach may be considered to be conservative as shorter propping durations could be possible without a loss in performance. The aim of this dissertation is to look into the effects of early propping removal on the longterm deflections of concrete members. This was done by modelling the deflection of a typical reinforced concrete beam at different ages of loading, using three code-based deflection calculation methods. The codes that were used are the South African National Standard (SANS), Eurocode (EC2) and American Concrete Institute code (ACI 318). A detailed literature-based investigation was conducted to determine the factors which affect deflection in reinforced concrete members, as well as the theory behind the code-based deflection calculation procedures. This was followed by the modelling of deflections using the abovementioned methods. Three case studies were performed to determine the effects of early propping removal under different scenarios. The first case study only deals with the effects of early age loading on long-term deflection. As an added point of interest, two different concrete mixes were used, made with two different types of cement. The second case study compares the effect that different levels of relative humidity have on the long term deflection at early ages of loading. Lastly, the effects of concrete strength on long-term deflections at early ages of loading was modelled. The results of the first case study indicated that a reduction in propping time is possible without causing excessive deflections. In the second and third case study is was observed that both the relative humidity and concrete strength respectively have an effect on the long term deflection and therefore also influence the propping time. The study concluded that based on the obtained estimated deflection values using the codebased methods, the propping times provided in the SANS 2001 code may in certain applications be conservative. According to the results obtained from the code-based deflection calculation procedures, it is possible to reduce the propping duration. It was suggested that an alternative method should be developed which would allow structural designers to determine the required propping time more accurately

Teacher Characteristics on Student Achievement: An Examination of High Schools in Ohio

Teachers are the most important school-based factor in affecting student achievement levels. Knowing what teacher characteristics influence student achievement and whether or not schools in different locations have dissimilar student achievement levels will help administrators prioritize who to hire, retain, and assign to classes. The purpose of this paper is to answer two questions. The first question is whether teacher characteristics are related to student achievement; the second is whether there are differences in student achievement based on school location. A review of teacher quality, teacher incentives, teacher background, the ability of a school to attract teachers, and differences in school location provides some background of the relationship between teacher characteristics and student achievement. I use data from the Ohio Department of Education (ODE) and the Census Bureau. All data is collected at the school level. From this I develop two models. The first is a fixed effects model that allows me to examine the relationship between teacher characteristics and student achievement with a county fixed effect. The second model is similar to the first except I substitute the country fixed effect variable for school location as an explanatory variable. The location variable is sorted into three categories by county population, and defined as large, medium and small. In both models the dependent variable is student achievement, which is measured by the high school’s percentage-passing rate on the Ohio Graduation Test (OGT), a standardized test administered to all potential graduates. I estimate each model five times, once for each section of the OGT. I use data from the Ohio Department of Education (ODE) and the Census Bureau. All data is collected at the school level. From this I develop two models. The first is a fixed effects model that allows me to examine the relationship between teacher characteristics and student achievement with a county fixed effect. The second model is similar to the first except I substitute the country fixed effect variable for school location as an explanatory variable. The location variable is sorted into three categories by county population, and defined as large, medium and small. In both models the dependent variable is student achievement, which is measured by the high school’s percentage-passing rate on the Ohio Graduation Test (OGT), a standardized test administered to all potential graduates. I estimate each model five times, once for each section of the OGT

The Course of Self-Injury in Help-Seeking Adolescents: Treatment, Trajectory, and Prediction of a Transdiagnostic Phenomenon

Nonsuicidal (NSSI) and suicidal self-injurious behaviors (SB) are common in adolescence. They occur in the general public but are particularly prevalent in psychiatric populations. The recognition of NSSI and SB as clinically relevant transdiagnostic phenomena has led to significant growth in scientific literature. However, profound knowledge regarding the courses and specific predictors is still scarce. The aim of the present dissertation is to address critical research questions with a focus on longitudinal analyses in a high-risk population of help-seeking adolescents. In the first study, the long-term effects of a brief intervention for adolescents with NSSI were examined. In a period of two to four years after the initial treatment phase, incidents of NSSI and SB reduced further, as did depression and borderline personality disorder criteria. Many patients received additional psychotherapy during the follow-up period which further decreased the frequency of NSSI. The focus of the second study was on the trajectory of NSSI over one year. An individualized analytical approach revealed that 75% of participants reduced the frequency of NSSI by at least half and 25% stopped NSSI completely. One in ten adolescents deteriorated over time and relapses were common. Predictors of change included depression, baseline NSSI frequency and the duration of inpatient treatment. The third publication analyzed the predictive value of self-rated risk for suicide attempts. Out of several clinically feasible variables, self-rated risk was the best predictor of actual suicide attempts. Depressive symptoms moderated the effect such that higher depression severity was linked to less accurate self-ratings. Suicidal and nonsuicidal self-injurious behaviors are complex and highly heterogeneous phenomena. Overall, the results reported in this dissertation provide important insight into the trajectory, treatment, and prediction of NSSI and SB in at-risk youth. Sophisticated longitudinal analyses with a focus on individual paths and alternative data sources have the potential to improve the current understanding of NSSI and SB and provide crucial knowledge for clinicians

Recombinant Envelope-Proteins with Mutations in the Conserved Fusion Loop Allow Specific Serological Diagnosis of Dengue-Infections

Dengue virus (DENV) is a mosquito-borne flavivirus and a major international public health concern in many tropical and sub-tropical areas worldwide. DENV is divided into four major serotypes, and infection with one serotype leads to immunity against the same, but not the other serotypes. The specific diagnosis of DENV-infections via antibody-detection is problematic due to the high degree of cross-reactivity displayed by antibodies against related flaviviruses, such as West Nile virus (WNV), Yellow Fever virus (YFV) or Tick-borne encephalitis virus (TBEV). Especially in areas where several flaviviruses co-circulate or in the context of vaccination e.g. against YFV or TBEV, this severely complicates diagnosis and surveillance. Most flavivirus cross-reactive antibodies are produced against the highly conserved fusion loop (FL) domain in the viral envelope (E) protein. We generated insect-cell derived recombinant E-proteins of the four DENV-serotypes which contain point mutations in the FL domain. By using specific mixtures of these mutant antigens, cross-reactivity against heterologous flaviviruses was strongly reduced, enabling sensitive and specific diagnosis of the DENV-infected serum samples in IgG and IgM-measurements. These results have indications for the development of serological DENV-tests with improved specificity

Adolescent mental health problems in early stages of the COVID-19 pandemic were masked by lockdown measures and restrictions.

In the BJPsych Open Wong et al examined the influence of lockdown stringency during early stages of the COVID-19 pandemic on psychiatric emergency presentations among children and adolescents from ten countries. Data from March and April 2019 were compared with the same time frame in 2020, with particular focus on self-harm admissions. In this editorial, the publication is summarised and potential implications for the field and future studies are discussed