312 research outputs found
Optimization of a charge-state analyzer for ECRIS beams
A detailed experimental and simulation study of the extraction of a 24 keV
He-ion beam from an ECR ion source and the subsequent beam transport through an
analyzing magnet is presented. We find that such a slow ion beam is very
sensitive to space-charge forces, but also that the neutralization of the
beam's space charge by secondary electrons is virtually complete for beam
currents up to at least 0.5 mA. The beam emittance directly behind the
extraction system is 65 pi mm mrad and is determined by the fact that the ion
beam is extracted in the strong magnetic fringe field of the ion source. The
relatively large emittance of the beam and its non-paraxiality lead, in
combination with a relatively small magnet gap, to significant beam losses and
a five-fold increase of the effective beam emittance during its transport
through the analyzing magnet. The calculated beam profile and phase-space
distributions in the image plane of the analyzing magnet agree well with
measurements. The kinematic and magnet aberrations have been studied using the
calculated second-order transfer map of the analyzing magnet, with which we can
reproduce the phase-space distributions of the ion beam behind the analyzing
magnet. Using the transfer map and trajectory calculations we have worked out
an aberration compensation scheme based on the addition of compensating
hexapole components to the main dipole field by modifying the shape of the
poles. The simulations predict that by compensating the kinematic and geometric
aberrations in this way and enlarging the pole gap the overall beam transport
efficiency can be increased from 16 to 45%
Radiocarbon in food: a non-problem of health effects
Recently it has come to our attention that a paper was published in this journal entitled “recycling greenhouse gas fossil fuel emissions into low radiocarbon food products to reduce human genetic damage” (Williams in Environ Chem Lett 5:197–202, 2007). In this article, it is argued that food grown in a greenhouse is healthier for people, when the greenhouse is fertilised with CO2 prepared from fossil fuels. In this comment, however, we argue that the effect on human health is completely negligible
Identity experiences of black people in the Netherlands
Abstract: In this study, we used the tri-dimensional model of identity and acculturation strategies to explore how black people living in the Netherlands define themselves We used a qualitative survey design in which 14 participants (females = 8; age range 21 to 58) completed open-ended questions about their experiences of being black in the Netherlands Data was analysed using hermeneutic phenomenology in three steps: naive understanding, structural analysis, and comprehensive understanding We derived several main themes: Acceptance; Inclusion; Stereotypes; Social membership; Personspecific characteristics; Separation (Contributors); and Social Status We associated the themes Acceptance, Inclusion, and Separation (Contributors) with acculturation and acculturative strategies The other themes can be connected to the tri-dimensional identity model Social membership and Social status are related to the social and relational aspects of identity, while Person-specific characteristics can be linked to personal identity Lastly, the theme Stereotypes can be related to both acculturation and racism, but also personal identity as it shows how the participants perceive their self-concept to contradict the beliefs that mainstream Dutch society holds about them We conclude that identity construction among the black respondents was reliant on both their ethnic community membership and their membership of the mainstream Dutch community
Quasi-experimental evaluation of near repeat patrolling: the Amstelveen experiment
In three neighborhoods in the city of Amstelveen, the Netherlands, an experiment with near repeat patrolling after a burglary was implemented, during the 4th quarter of 2011. After a burglary had been reported to the police, two uniformed police officers were patrolling in a radius of 250 meter during two days from 7 am-11 pm. Though the near repeat patrols did influence the near repeat pattern of burglary in the experimental areas, crime rates in the experimental areas did not become more favorable, compared to those in a control area in the same city. It is suggested that the experiment, though asking for a considerable amount of officers' time, was not large enough to be able to demonstrate positive effects, which then implies that effects are at best small, if not absent. The report is a short resumé in English of an earlier publication in Dutch.Criminal Justice: Legitimacy, accountability, and effectivit
Gender Differences in Developing Biomarker-Based Major Depressive Disorder Diagnostics
The identification of biomarkers associated with major depressive disorder (MDD) holds great promise to develop an objective laboratory test. However, current biomarkers lack discriminative power due to the complex biological background, and not much is known about the influence of potential modifiers such as gender. We first performed a cross-sectional study on the discriminative power of biomarkers for MDD by investigating gender differences in biomarker levels. Out of 28 biomarkers, 21 biomarkers were significantly different between genders. Second, a novel statistical approach was applied to investigate the effect of gender on MDD disease classification using a panel of biomarkers. Eleven biomarkers were identified in men and eight in women, three of which were active in both genders. Gender stratification caused a (non-significant) increase of Area Under Curve (AUC) for men (AUC=0.806) and women (AUC=0.807) compared to non-stratification (AUC=0.739). In conclusion, we have shown that there are differences in biomarker levels between men and women which may impact accurate disease classification of MDD when gender is not taken into account
Resveratrol and metabolic health in COPD:A proof-of-concept randomized controlled trial
Background: Patients with COPD are often characterized by disturbed metabolic health which is reflected in altered body composition. Current studies in healthy subjects suggest that resveratrol improves metabolic health by enhancing muscle mitochondrial function and adipose tissue morphology. The primary objective was to investigate the effect of four weeks resveratrol supplementation on muscle mitochondrial function in patients with COPD. Secondary objectives were to investigate the effect of resveratrol on adipose tissue inflammatory and metabolic gene expression, systemic inflammation and body composition in patients with COPD. Methods: In a double-blind randomized placebo-controlled proof-of-concept study, 21 COPD patients (FEVi: 53 +/- 15% predicted; age: 67 +/- 9 years and BMI: 24.5 +/- 3.3 kg/m(2)) received resveratrol (150 mg/day) or placebo for four weeks. Before and after intervention, blood samples, quadriceps muscle and subcutaneous abdominal fat biopsies were obtained for metabolic and inflammatory profiling. Body composition was assessed by dual energy X-ray absorptiometry. Results: Muscle mitochondrial biogenesis regulators AMPK, SIRT1 and PGC-1 alpha as well as mitochondrial respiration, Oxphos complexes, oxidative enzyme activities and kynurenine aminotransferases were not improved by resveratrol. Plasma high-sensitive C-reactive protein and kynurenine did not change after resveratrol supplementation. Adipose tissue inflammatory markers were unaffected by resveratrol, while markers of glycolysis and lipolysis were significantly increased compared to placebo supplementation. Body weight decreased after resveratrol supplementation (resveratrol -0.95 +/- 1.01 kg vs placebo -0.16 +/- 0.66 kg, p = 0.049) due to a reduction in lean mass (resveratrol -1.79 +/- 1.67 kg vs 0.37 +/- 0.86 kg, p = 0.026). Conclusion: We do not confirm previously reported positive effects of resveratrol on skeletal muscle mitochondrial function in patients with COPD, but show an unexpected decline in lean mass. (C) 2020 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved
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