Optimizing the Post Sandvik Nanoflex material model using inverse optimization and the finite element method

This article describes an inverse optimization method for the Sandvik Nanoflex steel in cold forming\ud processes. The optimization revolves around measured samples and calculations using the Finite Element\ud Method. Sandvik Nanoflex is part of the group of meta-stable stainless steels. These materials are characterized\ud by a good corrosion resistance, high strength, good formability and crack resistance. In addition, Sandvik\ud Nanoflex has a strain-induced transformation and, depending on austenising conditions and chemical composition,\ud a stress-assisted transformation can occur. The martensite phase of this material shows a substantial aging\ud response. The inverse optimization is a sub-category of the optimization techniques. The inverse optimization\ud method uses a top down approach, as the name implies. The starting point is a prototype state where the current\ud state is to converge on. In our experiment the test specimen is used as prototype and a calculation result as\ud current state. The calculation is then adapted so that the result converges towards the test example. An iterative\ud numerical optimization algorithm controls the adaptation. For the inverse optimization method two parameters\ud are defined: shape of the product and martensite profile. These parameters are extracted from both calculation\ud and test specimen, using Fourier analysis and integrals. An optimization parameter is then formulated from\ud the extracted parameters. The method uses this optimization parameter to increase the accuracy of ”The Post”\ud material model for Sandvik Nanoflex. [1] The article will describe a method to optimize material models, using\ud a combination practical experiments, Finite Element Method and parameter extraction

Probing dynamics of an electron-spin ensemble via a superconducting resonator

We study spin relaxation and diffusion in an electron-spin ensemble of nitrogen impurities in diamond at low temperature (0.25-1.2 K) and polarizing magnetic field (80-300 mT). Measurements exploit mode- and temperature-dependent coupling of hyperfine-split sub-ensembles to the resonator. Temperature-independent spin linewidth and relaxation time suggest that spin diffusion limits spin relaxation. Depolarization of one sub-ensemble by resonant pumping of another indicates fast cross-relaxation compared to spin diffusion, with implications on use of sub-ensembles as independent quantum memories.Comment: 5 pages, 5 figures, and Supplementary Information (2 figures

Isotope effects in underdoped cuprate superconductors: a quantum phenomenon

We show that the unusual doping dependence of the isotope effects on transition temperature and zero temperature in - plane penetration depth naturally follows from the doping driven 3D-2D crossover, the 2D quantum superconductor to insulator transition (QSI) in the underdoped limit and the change of the relative doping concentration upon isotope substitution. Close to the QSI transition both, the isotope coefficient of transition temperature and penetration depth approach the coefficient of the relative dopant concentration, and its divergence sets the scale. These predictions are fully consistent with the experimental data and imply that close to the underdoped limit the unusual isotope effect on transition temperature and penetration depth uncovers critical phenomena associated with the quantum superconductor to insulator transition in two dimensions.Comment: 6 pages, 3 figure

Impaired trophoblast invasion and increased numbers of immune cells at day 18 of pregnancy in the mesometrial triangle of type 1 diabetic rats

AbstractIntroductionType 1 diabetes (T1D) is associated with adverse pregnancy outcome, usually attributed to hyperglycemia. Recently, we showed that pregnancy outcome in normoglycemic T1D rats was characterized by decreased fetal and placental weight, suggesting impaired placental development. In the present study, we tested the hypothesis that trophoblast invasion and spiral artery (SA) remodeling is impaired in T1D rats ant that this is associated with aberrant local presence of NK cells and macrophages in the mesometrial triangle (MT).MethodsPlacentae with MT from pregnant biobreeding diabetes-prone (BBDP; T1D model) rats, control biobreeding diabetes-resistant (BBDR) and Wistar-rats were dissected at day 18 of gestation and stained for trophoblast invasion, SA remodeling, uNK cells and macrophages.ResultsInterstitial trophoblast invasion and SA remodeling was impaired in BBDP-rats vs. control rats, coinciding with increased presence of NK cells and an increased iNOS+/CD206+ ratio of macrophages.DiscussionDecreased fetal and placental weight in BBDP-rats was associated with diminished interstitial trophoblast invasion and less optimal SA remodeling, increased numbers of NK cells and increased iNOS+/CD206+ macrophage ratio in the MT of BBDP-rats.ConclusionsThe impaired trophoblast invasion and SA remodeling may be due to an aberrant local immune-response and may result in damage to the fetal placenta and insufficient supply of nutrients towards the fetus with eventually decreased fetal weight as a consequence

The Mathematics Problem and Mastery Learning for First-Year, Undergraduate STEM Students

In the 2014 academic year Mastery Learning was implemented in four first-year mathematics subjects in an effort to address a lack of preparedness and poor outcomes of increasing numbers of undergraduate students in science, engineering and mathematics programs. This followed partial success in the use of diagnostic testing and pre-teaching, active learning, and a greater emphasis on problem solving in context - under-prepared students were still more likely to fail the pre-teaching subject and to struggle with subsequent mathematics subjects. Also, failure rates overall were higher than benchmarks required. This paper describes the learning design used, and the outcomes achieved, with implementing Mastery Learning – the positive: improved academic success, time management, and attitudes towards learning and Mathematics, an increased sense of independence, confidence and retention of content, and reduced stress and anxiety; and the negative: students having a sense of being taught how to pass a test rather than having a deeper understanding of the content. It will be seen that this negative is a consequence of a small but important difference in implementation

Prognostic factors and patterns of recurrence in esophageal cancer assert arguments for extended two-field transthoracic esophagectomy

BACKGROUND: High recurrence rates determine the dismal outcome in esophageal cancer. We reviewed our experiences and defined prognostic factors and patterns of recurrences after curatively, intended transthoracic esophagectomy. METHODS: Between January 1991 and December 2005, 212 consecutive patients underwent a radical transthoracic esophagectomy with extended 2-field lymphadenectomy. Recurrence rates, survival, and prognostic factors were analyzed (minimal follow-up period, 2 y). RESULTS: Radicality was obtained in 85.6%. The median follow-up period was 26.6 months. The overall recurrence rate at I, 3, and 5 years was 28%, 44%, and 64%, respectively, and locoregional recurrence rate was 17%, 27%, and 43%, respectively. Overall survival rates, including postoperative deaths, were 45% and 34% at 3 and 5 years, respectively. pT stage and lymph node (LN) ratio greater than .20 were independent prognostic factors for survival and recurrences. Radicality was most prognostic for survival, and for N+ greater than 4 positive LN for recurrences. CONCLUSIONS: Radicality and LN ratio are strong prognostic factors. High radicality and adequate nodal assessment are guaranteed by an extended transthoracic approach. (C) 2010 Elsevier Inc. All rights reserved

Degregatie van broedvogelgegevens van atlasblok naar kilometercel

VakpublicatieInstitute of Environmental Science

The role of PCOS in mental health and sexual function in women with obesity and a history of infertility

STUDY QUESTION: Do mental health and sexual function differ between women with or without polycystic ovary syndrome (PCOS) with comparable BMI and fertility characteristics? SUMMARY ANSWER: Women with PCOS have a poorer mental quality of life than women without PCOS, but there were no differences in symptoms of depression, anxiety, physical quality of life or sexual function. WHAT IS KNOWN ALREADY: Various studies suggest that women with PCOS have poorer mental health, such as higher symptoms of anxiety and depression with a lower quality of life, and have an impaired sexual function compared to women without PCOS. However, in most studies, BMI and infertility status differ between women with and without PCOS, which may hamper comparability. STUDY DESIGN, SIZE, DURATION: This study is a cross-sectional analysis of a 5-year follow-up of a randomized controlled trial (RCT) among women with obesity and a history of infertility. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants in this follow-up study of an RCT were women with obesity and infertility randomized to a lifestyle intervention followed by infertility treatment or prompt infertility treatment (control), stratified by ovulatory status and trial centre. In total, 173 (30.0%) women of the 577 women randomized in the initial trial participated in this follow-up study, with a mean follow-up of 5.5 years (range 3.7–7.0 years); of these women 73 had been diagnosed with PCOS and 100 did not have PCOS. Participants completed questionnaires on symptoms of anxiety and depression (Hospital Anxiety and Depression scale (HADS)), quality of life (36-item Short Form Health Survey (SF-36)) and sexual function (McCoy Female Sexuality Questionnaire (MFSQ)). We also compared quality of life subscale scores in women with and without PCOS and compared them to an age-matched Dutch reference population with average BMI. Effect sizes were calculated to assess the differences. MAIN RESULTS AND THE ROLE OF CHANCE: Symptoms of anxiety and depression, physical quality of life and sexual function did not differ significantly between obese women with and without PCOS. However, women with PCOS had a worse mental quality of life summary component score (−3.60 [95% CI −6.72 to −0.56]), mainly due to a lower score on the subscale ‘role limitations due to emotional problems’ (−12.41 [95% CI −22.78 to −2.28]), compared to women without PCOS. However, compared to an age-matched Dutch reference population, the obese infertile women with and without PCOS both scored lower on almost all physical and mental quality of life subscales. LIMITATIONS, REASONS FOR CAUTION: These are secondary analyses of the follow-up study of the RCT. No power analysis was performed for the outcomes included in this analysis and, as our study had a relatively small sample size, the null findings could be based on insufficient power to detect small differences between the groups. Our study population had a high mean BMI (average total group 34.5 [SD ± 5.1]); therefore, our results may only be generalizable to women with obesity. WIDER IMPLICATIONS OF THE FINDINGS: Our results indicate that PCOS status is associated with impaired mental quality of life. Anxiety and depression, physical quality of life and sexual function in obese infertile women with PCOS seem more related to the obesity than the PCOS status. STUDY FUNDING/COMPETING INTEREST(S): The initial study and follow-up were supported by grants from: ZonMw (50-50110-96-518), the Dutch Heart Foundation (2013T085) and the European Commission (633595). The Department of Obstetrics and Gynaecology of the UMCG received an unrestricted educational grant from Ferring pharmaceuticals BV, The Netherlands, outside the submitted work. A.H. reports consultancy for Ferring pharmaceuticals. B.W.J.M. is supported by an NHMRC Practitioner Fellowship (GNT1082548). B.W.J.M. reports consultancy for ObsEva, Merck Merck KGaA, iGenomix and Guerbet. All other authors declare no competing interests. TRIAL REGISTRATION NUMBER: The initial trial was registered on 16 November 2008 in the Dutch trial register; clinical trial registry number NTR1530

De milieukwaliteit van de ecodistricten het laagveengebied en de kalkrijke duinen

VakpublicatieInstitute of Environmental Science