The Strength of Partially Stiffened Stainless Steel Compression Members

In this study the effect of the non-linear behaviour of stainless steels on the local buckling strength of partially stiffened compression elements is studied. The steel under investigation is a Type 304 stainless steel. Doubly symmetric hat section columns were manufactured by a press braking process and tested as stub columns to exclude overall buckling interaction. The different plasticity reduction factors\u27 suggested in the ASCE stainless steel design specification for stiffened and unstiffened compression elements are used to compare experimental results with theoretical predictions. It is concluded that the ASCE and South African stainless steel design specifications overestimate the local buckling stress as well as the ultimate strength of partially stiffened stainless steel compression elements. The experimental results compare well with the theoretical predictions when the two plasticity reduction factors are used

Patient versus general population health state valuations:a case study of non-specific low back pain

PURPOSE: The purpose of this study was twofold: (1) to compare non-specific low back pain (LBP) patients' health state valuations with those of the general population, and (2) to explore how aspects of health-related quality of life as measured by the EQ-5D-3L impact non-specific LBP patient valuations. METHODS: Data were used of a randomized controlled trial, including 483 non-specific LBP patients. Outcomes included the EQ-VAS and the EQ-5D-3L. Patient valuations were derived from the EQ-VAS. Population valuations were derived from the EQ-5D-3L using a Dutch VAS-based tariff. The difference between patient and population valuations was assessed using t tests. An OLS linear regression model was constructed to explore how various aspects of health-related quality of life as measured by the ED-5D-3L impact non-specific LBP patient valuations. RESULTS: Non-specific LBP patients valued their health states 0.098 (95% CI 0.082-0.115) points higher than the general population. Only 22.2% of the variance in patient valuations was explained by the patients' EQ-5D-3L health states (R (2) = 0.222). Non-specific LBP patients gave the most weight to the anxiety/depression dimension. CONCLUSIONS: This study demonstrated that non-specific LBP patients value their health states higher than members of the general population and that the choice of valuation method could have important implications for cost-effectiveness analyses and thus for clinical practice

Effects of plant pathogens on population dynamics and community composition in grassland ecosystems: two case studies

Grassland ecosystems comprise a major portion of the earth’s terrestrial surface, ranging from high-input cultivated monocultures or simple species mixtures to relatively unmanaged but dynamic systems. Plant pathogens are a component of these systems with their impact dependent on many interacting factors, including grassland species population dynamics and community composition, the topics covered in this paper. Plant pathogens are affected by these interactions and also act reciprocally by modifying their nature. We review these features of disease in grasslands and then introduce the 150-year long-term Park Grass Experiment (PGE) at Rothamsted Research in the UK. We then consider in detail two plant-pathogen systems present in the PGE, Tragopogon pratensis-Puccinia hysterium and Holcus lanata-Puccinia coronata. These two systems have very different life history characteristics: the first, a biennial member of the Asteraceae infected by its host-specific, systemic rust; the second, a perennial grass infected by a host-non-specific rust. We illustrate how observational, experimental and modelling studies can contribute to a better understanding of population dynamics, competitive interactions and evolutionary outcomes. With Tragopogon pratensis-Puccinia hysterium, characterised as an “outbreak” species in the PGE, we show that pathogen-induced mortality is unlikely to be involved in host population regulation; and that the presence of even a short-lived seed-bank can affect the qualitative outcomes of the host-pathogen dynamics. With Holcus lanata-Puccinia coronata, we show how nutrient conditions can affect adaptation in terms of host defence mechanisms, and that co-existence of competing species affected by a common generalist pathogen is unlikely

Suppression of Zeeman gradients by nuclear polarization in double quantum dots

We use electric dipole spin resonance to measure dynamic nuclear polarization in InAs nanowire quantum dots. The resonance shifts in frequency when the system transitions between metastable high and low current states, indicating the presence of nuclear polarization. We propose that the low and the high current states correspond to different total Zeeman energy gradients between the two quantum dots. In the low current state, dynamic nuclear polarization efficiently compensates the Zeeman gradient due to the $g$-factor mismatch, resulting in a suppressed total Zeeman gradient. We present a theoretical model of electron-nuclear feedback that demonstrates a fixed point in nuclear polarization for nearly equal Zeeman splittings in the two dots and predicts a narrowed hyperfine gradient distribution

Evolutionary bi-stability in pathogen transmission mode

Many pathogens transmit to new hosts by both infection (horizontal transmission) and transfer to the infected host's offspring (vertical transmission). These two transmission modes require speci®c adap- tations of the pathogen that can be mutually exclusive, resulting in a trade-off between horizontal and vertical transmission. We show that in mathematical models such trade-offs can lead to the simultaneous existence of two evolutionary stable states (evolutionary bi-stability) of allocation of resources to the two modes of transmission. We also show that jumping between evolutionary stable states can be induced by gradual environmental changes. Using quantitative PCR-based estimates of abundance in seed and vege- tative parts, we show that the pathogen of wheat, Phaeosphaeria nodorum, has jumped between two distinct states of transmission mode twice in the past 160 years, which, based on published evidence, we interpret as adaptation to environmental change. The ®nding of evolutionary bi-stability has impli- cations for human, animal and other plant diseases. An ill-judged change in a disease control programme could cause the pathogen to evolve a new, and possibly more damaging, combination of transmission modes. Similarly, environmental changes can shift the balance between transmission modes, with adverse effects on human, animal and plant health

Soil nitrogen supply of peat grasslands estimated by degree days and soil organic matter content

Accurate estimates of the quantity and rate of soil nitrogen supply (SNS) are essential to increase soil and farm N use efficiencies, in particular for soils high in organic matter. The objective of this work was to enhance the empirical understanding of the SNS of dairy grasslands on peat soils, using soil properties and weather variables. Data were collected from studies on herbage N uptake carried out between 1992 and 2017 in the western peat district of the Netherlands. For the period between March to mid October, SNS was estimated from the sum of mean growing season daily temperatures, soil organic matter (SOM) and applied calcium ammonium nitrate (CAN) N with a residual standard error of 25–27 kg ha−1. Each °C growing season temperature sum affected SNS by 78–90 g ha−1 and each g SOM per 100 g dry soil affected SNS by 3.6–3.9 kg ha−1, respectively. SNS was equally estimated for conditions with and without CAN fertilisation. Validation with data from independent field trials showed similar impacts of SOM and growing season temperature sum on SNS. The error of prediction of the presented models, however, was still too large for direct on-farm application and led to underestimations for a specific site. Nevertheless, the obtained models allow for an increased understanding of soil and farm N balances. The models can therefore be used for improved temporal and spatial SNS-adapted farming practice advice, which can potentially lead to reduced soil and farm N surpluses.</p

On-line Excited-State Laser Spectroscopy of Trapped Short-Lived Ra+^+ Ions

As an important step towards an atomic parity violation experiment in one single trapped Ra$^+$ ion, laser spectroscopy experiments were performed with on-line produced short-lived $^{212,213,214}$Ra$^+$ ions. The isotope shift of the 6\,^2D$_{3/2}$\,-\,7\,^2P$_{1/2}$ and 6\,^2D$_{3/2}$\,-\,7\,^2P$_{3/2}$ transitions and the hyperfine structure constant of the 7\,^2S$_{1/2}$ and 6\,^2D$_{3/2}$ states in $^{213}$Ra$^+$ were measured. These values provide a benchmark for the required atomic theory. A lower limit of $232(4)$ ms for the lifetime of the metastable 6\,^2D$_{5/2}$ state was measured by optical shelving.Comment: 4.2 pages, 6 figures, 2 tables

Drug Registries and Approval of Drugs:Promises, Placebo, or a Real Success?

Purpose: As part of the approval process, regulatory authorities often require postauthorization studies that involve patient registries; it is unknown, however, whether such registry studies are adequately completed. We investigated whether registry studies for new drugs were performed as agreed at time of approval. Methods: This study reviewed protocols and follow-up reports for 73 registry studies that were proposed for 43 drugs approved by the Committee for Medicinal Products for Human Use in Europe in the period 2007 to 2010. Results: The data lock point of January 1, 2016, was taken to allow a 5-year follow-up period for each drug after approval. At that time, 2 studies (3%) in registries had been finalized, 19 registries (26%) had not enrolled any patients, and 52 studies (71%) were ongoing. The median enrollment was 31% (interquartile range [IQR], 6–104) of the required number of patients for 41 registry studies that had a predefined sample size, 30% (IQR, 2–101) for nonimposed registries, and 61% (IQR, 18–144) for imposed registries. Implications: Enrollment of patients into postapproval registries is poor, although the results for imposed registries seem better. Currently, registries only have a limited impact on resolving gaps in the knowledge of a drug's benefits and risks at time of marketing authorization