Magnetic behavior of current-carrying Type-II superconducting cylinders

The theoretical magnetic behavior of current-carrying superconducting cylinders in the presence of applied axial fields is investigated. An attempt is made to systematize the complex behavior by carefully accounting for critical current, surface pinning, and surface pitch angle, and by stressing the importance of the magnetic history of the sample. A differential equation is developed relating the thermodynamic field H(B) to the cylinder radius rho. This equation, is readily integrated numerically using a Runge-Kutta technique. The resultant flux profiles are further integrated numerically to obtain the mean magnetization of the cylinder. Careful distinction is maintained between the magnetic flux density B and the magnetic field H inside the cylinder. Results are displayed using a phase-diagrammatic technique, which shows the relative amounts of axial and azimuthal field needed to produce a given field within the cylinder, as a function of the bulk pinning strength and the surface pitch angle. In order to incorporate the magnetic history of a sample, a pair of simultaneous differential equations is developed, relating the field H and time, and the radius rho and the time, in a quasistatic manner. When simultaneously integrated, these equations yield a flux profile H(rho) which accounts for any arbitrary variations in the current and axial field experienced by the sample in progressing from the virgin state to the final flux configuration, provided the surface magnetic field increases with time. This should enable certain laboratory sequences in the application of current and field to be modeled analytically

The spectrum of acute and subacute myelopathy

Acute and subacute diseases causing intrinsic spinal cord damage are confusing and poorly defined clinically and pathologically. of this study is: The purpose 1. To analyse the spectrum of conditions responsible for acute and subacute myelopathy in South Africa. 2. To categorise the clinical presentations and prognosis of the illnesses and to correlate these with aetiology. 3. To assess the validity of diagnostic criteria for acute and subacute myelopathy in general and for the different aetiological groups. 4. To review the literature and to correlate previous studies with the present one. Thirty-four patients fulfilling strict criteria nave been identified over a seven-and-a-half-year period using the Groote Schuur Hospital computer retrieval system. Although the study was essentially retrospective, 11 of these patients were seen personally during their acute illnesses. All these patients have suffered from illnesses causing spinal cord dysfunction in the absence of trauma, physical agents or any extrinsic pressure such as might be caused by tumours or spondylosis. Maximum disability was reached in less than 8 weeks. In 17 patients no cause was identified. The clinical features, laboratory findings and courses have been analysed. Among the results, a high percentage of patients with Brown-Sequard Syndromes were found with possible significance for the pathogenesis of the illness. Seven patients with meningovascular syphilis were analysed as well as 2 additional patients with spinal cord syphilis not fulfilling the strict criteria of the study. Although well known before the penicillin era, this entity is not well described in modern neurological literature. Four patients had myelopathy associated with pulmonary tuberculosis in the absence of tuberculous meningitis or spinal disease. Three of these 4 patients also developed optic neuropathy. The association of these conditions has previously been described in only a very few patients. Two patients had Epstein-Barr virus infections and 1 had an infection with Mycoplasma pneumoniae. Two had systemic lupus erythematosus and 1 had an acute cord infarct following an aortic aneurysm repair. The literature is reviewed and the findings of this study correlated with previous ones. Conclusions regarding terminology, criteria for diagnosis, investigations, course and prognosis are discussed

How Does a Student-Centered Course on Communication and Professional Skills Impact Students in the Long Run?

This Full Paper in the Research-To-Practice Category presents a long-term study about the effects of a student-centered course on communication and professional skills on students’ thoughts, attitudes, and behavior. The course is offered at a European university as part of a computer science master's program. This paper shares the design and challenges of a longitudinal study that reaches ten years behind and employs a mixed-methods approach. Besides presenting and interpreting the findings, we shed light on which features tend to stay on students’ minds and impact their way of being and acting in society. Moreover, we suggest implications for the design and practice in comparable courses to maximize constructive, sustainable effects, such as improved active listening, presentation skills, and openness to other perspectives. These are essential (not only) for computer science professionals. Our findings suggest that the course provided significant learning for the vast majority of respondents, including aspects such as presenting while keeping the other side in mind, managing one’s stress, and becoming less shy to speak up. All in all, we aim to contribute an evidence-based source of motivation for instructors in technically focused curricula who hold a student-centered stance

A Meta-Analysis of How Country-Level Factors Affect Web Survey Response Rates

A major challenge in web-based cross-cultural data collection is varying response rates, which can result in low data quality and non-response bias. Country-specific factors such as the political and demographic, economic, and technological factors as well as the socio-cultural environment may have an effect on the response rates to web surveys. This study evaluates web survey response rates using meta-analytical methods based on 110 experimental studies from seven countries. Three dependent variables, so-called effect sizes, are used: the web response rate, the response rate to the comparison survey mode, and the difference between the two response rates. The meta-analysis indicates that four country-specific factors (political and demographic, economic, technological, and socio-cultural) impact the magnitude of web survey response rates. Specifically, web surveys achieve high response rates in countries with high population growth, high internet coverage, and a high survey participation propensity. On the other hand, web surveys are at a disadvantage in countries with a high population age and high cell phone coverage. This study concludes that web surveys can be a reliable alternative to other survey modes due to their consistent response rates and are expected to be used more frequently in national and international settings

A General Interviewer Training Curriculum for Computer-Assisted Personal Interviews (GIT-CAPI) (Version 1.0)

Interviewer training is essential to ensure high-quality data in interviewer-administered surveys. Basically, interviewer training can be divided into general interviewer training which provides interviewers with fundamental knowledge about their role in the data collection process as well as succinct practical advice and project-specific interviewer training which provides additional project-specific qualifications. This survey guideline consists of two parts (I) the introductory and explanatory text and (II) the General Interviewer Training for Computer-Assisted Personal Interviews (GIT-CAPI) Curriculum. The GIT-CAPI aims at offering guidance on how to design, structure, and implement general interview training for Computer-Assisted Personal Interviews (CAPI). It includes seven training modules addressing the following topics: (1) procedural view on surveys, (2) quality perspective on surveys, (3) gaining respondents’ cooperation, (4) survey administration and survey instruments, (5) interviewing techniques and fieldwork, (6) professional standards and ethics, data protection and privacy, and (7) a technical tutorial. The GIT-CAPI is written primarily for survey research institutes and large survey projects, but they are also aimed at individual researchers and university research projects to provide them with information on relevant basic interviewer qualifications and allow them to incorporate some modules of the GIT-CAPI into their own interviewer training program. This GIT-CAPI will be revised regularly

Open science and public trust in science: Results from two studies

In two studies, we examined whether open science practices, such as making materials, data, and code of a study openly accessible, positively affect public trust in science. Furthermore, we investigated whether the potential trust-damaging effects of research being funded privately (e.g. by a commercial enterprise) may be buffered by such practices. After preregistering six hypotheses, we conducted a survey study (Study 1; N = 504) and an experimental study (Study 2; N = 588) in two German general population samples. In both studies, we found evidence for the positive effects of open science practices on trust, though it should be noted that in Study 2, results were more inconsistent. We did not however find evidence for the aforementioned buffering effect. We conclude that while open science practices may contribute to increasing trust in science, the importance of making use of open science practices visible should not be underestimated

Changes in the prevalence, treatment and control of hypertension in Germany? : a clinical-epidemiological study of 50.000 primary care patients

INTRODUCTION: Medical societies have developed guidelines for the detection, treatment and control of hypertension (HTN). Our analysis assessed the extent to which such guidelines were implemented in Germany in 2003 and 2001. METHODS: Using standardized clinical diagnostic and treatment appraisal forms, blood pressure levels and patient questionnaires for 55,518 participants from the cross-sectional Targets and Essential Data for Commitment of Treatment (DETECT) study (2003) were analyzed. Physician's diagnosis of hypertension (HTN(doc)) was defined as coding hypertension in the clinical appraisal questionnaire. Alternative definitions used were physician's diagnosis or the patient's self-reported diagnosis of hypertension (HTN(doc,pat)), physician's or patient's self-reported diagnosis or a BP measurement with a systolic BP≥140 mmHg and/or a diastolic BP≥90 (HTN(doc,pat,bp)) and diagnosis according to the National Health and Nutrition Examination Survey (HTN(NHANES)). The results were compared with the similar German HYDRA study to examine whether changes had occurred in diagnosis, treatment and adequate blood pressure control (BP below 140/90 mmHg) since 2001. Factors associated with pharmacotherapy and control were determined. RESULTS: The overall prevalence rate for hypertension was 35.5% according to HTN(doc) and 56.0% according to NHANES criteria. Among those defined by NHANES criteria, treatment and control rates were 56.0% and 20.3% in 2003, and these rates had improved from 55.3% and 18.0% in 2001. Significant predictors of receiving antihypertensive medication were: increasing age, female sex, obesity, previous myocardial infarction and the prevalence of comorbid conditions such as coronary heart disease (CHD), hyperlipidemia and diabetes mellitus (DM). Significant positive predictors of adequate blood pressure control were CHD and antihypertensive medication. Inadequate control was associated with increasing age, male sex and obesity. CONCLUSIONS: Rates of treated and controlled hypertension according to NHANES criteria in DETECT remained low between 2001 and 2003, although there was some minor improvement

Nonlinear Competition Between Small and Large Hexagonal Patterns

Recent experiments by Kudrolli, Pier and Gollub on surface waves, parametrically excited by two-frequency forcing, show a transition from a small hexagonal standing wave pattern to a triangular ``superlattice'' pattern. We show that generically the hexagons and the superlattice wave patterns bifurcate simultaneously from the flat surface state as the forcing amplitude is increased, and that the experimentally-observed transition can be described by considering a low-dimensional bifurcation problem. A number of predictions come out of this general analysis.Comment: 4 pages, RevTex, revised, to appear in Phys. Rev. Let