201 research outputs found
Computational Design Optimization of a Smart Material Shape Changing Building Skin Tile
The development and evaluation of a computational approach for optimal design of a smart material shape changing building skin is presented and numerically evaluated. Specifically, a unique shape-based approach is utilized to create an optimization approach to identify the activation and actuation mechanisms to minimize the difference between a desired shape and the estimated morphed shape. Three potential metrics of shape difference are considered and their capability to facilitate an efficient optimization process leading to accurate shape matching is evaluated. Details of the optimal design framework are presented, particularly focusing on the shape difference metrics as well as the strategy to parameterize the activation of the smart material. In particular, the parameterization strategy is a unique approach to easily integrate controllable localized activation within a smart material structure in a generally applicable way that does not limit the design search space. A series of numerical design examples are presented based on the concept of a smart material (e.g., shape memory polymer) shape changing tile that can be activated and actuated in a variety of ways to achieve desirable surface wrinkle patterns. These numerical design examples are applied to both 2D and 3D problems and consider a variety of parameterizations and target shapes. Results indicate that the shape-based approach can consistently determine the mechanisms of morphing needed to accurately match a target shape. Furthermore, it is shown that localized material activation can lead to not only a more accurate shape but also requires less energy and actuation devices to do so
Assessment of the adaptability of non-fastidious pathogenic bacteria to the Martian environment.
Understanding the extent to which non-fastidious pathogenic bacteria can survive in extraterrestrial conditions will help to improve astronaut safety. Despite stringent decontamination protocols, terrestrial microorganisms were previously found to travel on the bodies of astronauts, on spaceships and equipment. This might enable the microorganisms to adapt, grow and evolve in the new environment. In this study, we assessed the adaptability of clinically relevant bacteria species, which are able to grow on carbon-containing compounds identified in carbonaceous meteorites (Klebsiella pneumoniae, Burkholderia cepacia, Serratia marcescens and Pseudomonas aeruginosa), to the simulated Martian environment. Previous work has shown that bacterial survival and growth under these conditions led to the modification of their cell envelope, thereby altering their pathogenic potential. We continued with this line of research and explored the survival of these bacterial species to a range of simulated Martian conditions i.e., desiccation, UVC (254 nm) and polychromatic UV (200 - 400 nm) irradiation, growth in the presence of perchlorates, growth on Martian simulant and exposure to Martian atmospheric composition and pressure. Preliminary results showed that growth was enhanced by the addition of Mars Global simulant (mimicking Martian regolith) to the incubation media. Furthermore, these initial results showed that only two of the strains, K. pneumoniae and S. marcescens are tolerant to desiccation, up to 16 days. The UVC irradiation experiments have shown that the bacteria with the highest degree of survival are P. aeruginosa and S. marcescens. Likewise, the same two strains have shown higher survival rates compared to K. pneumoniae and B. cepacia when exposed to polychromatic UV irradiation. To investigate the consequences of survival and growth under simulated Martian conditions, on virulence and immune recognition, a follow-up study will analyze the response of immune cells placed in contact with bacteria exposed to the Martian environment. In addition, gene expression of the adapted bacteria will be further studied. This collaborative study between the DLR (German Aerospace Center) and the Radboud UMC, in the Netherlands has provided a starting point to the investigation into the adaptability of pathogenic bacteria to Martian conditions. Further studies are required in order to improve our insight on the effects of virulence and immune recognition of the exposed pathogens. This could enable us to potentially anticipate the risks of infection and inflammation during space-travel and exploration
Interleukin-6 gene (IL-6): a possible role in brain morphology in the healthy adult brain
Background: Cytokines such as interleukin 6 (IL-6) have been implicated in dual functions in neuropsychiatric disorders. Little is known about the genetic predisposition to neurodegenerative and neuroproliferative properties of cytokine genes. In this study the potential dual role of several IL-6 polymorphisms in brain morphology is investigated. Methodology: In a large sample of healthy individuals (N = 303), associations between genetic variants of IL-6 (rs1800795; rs1800796, rs2069833, rs2069840) and brain volume (gray matter volume) were analyzed using voxel-based morphometry (VBM). Selection of single nucleotide polymorphisms (SNPs) followed a tagging SNP approach (e.g., Stampa algorigthm), yielding a capture 97.08% of the variation in the IL-6 gene using four tagging SNPs. Principal findings/results: In a whole-brain analysis, the polymorphism rs1800795 (−174 C/G) showed a strong main effect of genotype (43 CC vs. 150 CG vs. 100 GG; x = 24, y = −10, z = −15; F(2,286) = 8.54, puncorrected = 0.0002; pAlphaSim-corrected = 0.002; cluster size k = 577) within the right hippocampus head. Homozygous carriers of the G-allele had significantly larger hippocampus gray matter volumes compared to heterozygous subjects. None of the other investigated SNPs showed a significant association with grey matter volume in whole-brain analyses. Conclusions/significance: These findings suggest a possible neuroprotective role of the G-allele of the SNP rs1800795 on hippocampal volumes. Studies on the role of this SNP in psychiatric populations and especially in those with an affected hippocampus (e.g., by maltreatment, stress) are warranted.Bernhard T Baune, Carsten Konrad, Dominik Grotegerd, Thomas Suslow, Eva Birosova, Patricia Ohrmann, Jochen Bauer, Volker Arolt, Walter Heindel, Katharina Domschke, Sonja Schöning, Astrid V Rauch, Christina Uhlmann, Harald Kugel and Udo Dannlowsk
PKU dietary handbook to accompany PKU guidelines
Background: Phenylketonuria (PKU) is an autosomal recessive inborn error of phenylalanine metabolism caused by deficiency in the enzyme phenylalanine hydroxylase that converts phenylalanine into tyrosine. Main body: In 2017 the first European PKU Guidelines were published. These guidelines contained evidence based and/or expert opinion recommendations regarding diagnosis, treatment and care for patients with PKU of all ages. This manuscript is a supplement containing the practical application of the dietary treatment. Conclusion: This handbook can support dietitians, nutritionists and physicians in starting, adjusting and maintaining dietary treatment
Peripheral blood and neuropsychological markers for the onset of action of antidepressant drugs in patients with Major Depressive Disorder
<p>Abstract</p> <p>Background</p> <p>In Major Depressive Disorder (MDD), treatment outcomes with currently available strategies are often disappointing. Therefore, it is sensible to develop new strategies to increase remission rates in acutely depressed patients. Many studies reported that true drug response can be observed within 14 days (early improvement) of antidepressant treatment. The identical time course of symptom amelioration after early improvement in patients treated with antidepressants of all classes or with placebo strongly suggests a common biological mechanism, which is not specific for a particular antidepressant medication. However, the biology underlying early improvement and final treatment response is not understood and there is no established biological marker as yet, which can predict treatment response for the individual patient before initiation or during the course of antidepressant treatment. Peripheral blood markers and executive functions are particularly promising candidates as markers for the onset of action and thus the prediction of final treatment outcome in MDD.</p> <p>Methods/Design</p> <p>The present paper presents the rationales, objectives and methods of a multi-centre study applying close-meshed repetitive measurements of peripheral blood and neuropsychological parameters in patients with MDD and healthy controls during a study period of eight weeks for the identification of biomarkers for the onset of antidepressants' action in patients with MDD. Peripheral blood parameters and depression severity are assessed in weekly intervals from baseline to week 8, executive performance in bi-weekly intervals. Patients are participating in a randomized controlled multi-level clinical trial, healthy controls are matched according to mean age, sex and general intelligence.</p> <p>Discussion</p> <p>This investigation will help to identify a biomarker or a set of biomarkers with decision-making quality in the treatment of MDD in order to increase the currently disappointing remission rates of antidepressant treatment.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00974155">NCT00974155</a></p
Market Work, Home Production, Consumer Demand and Unemployment among the Unskilled
We develop a general equilibrium model in which longer working time and higher labor force participation lead to a fall in unemployment. Longer working hours and higher labor force participation have two direct effects: People have higher incomes and less (leisure) time. This has implications for the composition of consumer demand, since people spend less time on home production. Instead, they outsource more domestic tasks to the market. Consumer demand shifts toward unskill-intensive goods. The relative demand for unskilled labor rises and unemployment falls. We provide empirical evidence for our theoretical predictions in several ways: We study the link between labor market participation, home production and the demand for household and similar services using the German time use survey conducted in 1991/92. In addition, we use panel data for 23 OECD countries between 1980 and 2003 to directly examine the link between labor force participation and the unemployment rate. The empirical results corroborate the predictions from the theoretical model
Cross-sectional observational study of 208 patients with non-classical urea cycle disorders.
Urea cycle disorders (UCDs) are inherited disorders of ammonia detoxification often regarded as mainly of relevance to pediatricians. Based on an increasing number of case studies it has become obvious that a significant number of UCD patients are affected by their disease in a non-classical way: presenting outside the newborn period, following a mild course, presenting with unusual clinical features, or asymptomatic patients with only biochemical signs of a UCD. These patients are surviving into adolescence and adulthood, rendering this group of diseases clinically relevant to adult physicians as well as pediatricians. In preparation for an international workshop we collected data on all patients with non-classical UCDs treated by the participants in 20 European metabolic centres. Information was collected on a cohort of 208 patients 50% of which were ≥ 16 years old. The largest subgroup (121 patients) had X-linked ornithine transcarbamylase deficiency (OTCD) of whom 83 were female and 29% of these were asymptomatic. In index patients, there was a mean delay from first symptoms to diagnosis of 1.6 years. Cognitive impairment was present in 36% of all patients including female OTCD patients (in 31%) and those 41 patients identified presymptomatically following positive newborn screening (in 12%). In conclusion, UCD patients with non-classical clinical presentations require the interest and care of adult physicians and have a high risk of neurological complications. To improve the outcome of UCDs, a greater awareness by health professionals of the importance of hyperammonemia and UCDs, and ultimately avoidance of the still long delay to correctly diagnose the patients, is crucial
Does It Pay To Be a Woman? Labour Demand Effects of Maternity-Related Job Protection and Replacement Incomes
In countries with strong employment protection laws it is often considered to be unwise to hire a woman in childbearing age because she might get pregnant. However, such labour demand e ects of job protection measures related to maternity leave are often rather anecdotal. To provide analytical evidence, this paper studies the impact of changes in maternity-related job protection in Germany on employment opportunities for women in childbearing age without children for whom the observed e ects should be largely demand-related. Exogenous, discrete policy changes in the German labour market of the 1980s and 1990s constitute the setting for a difference-in-differences analysis of the transition into employment as well as wages. The data for this study are taken from the German Socio-Economic Panel and from the German Microcensus. Doubling the job-protected leave period from 6 months to 12 months between 1986 and 1988 led to an approximately 6% lower probability of being hired for women in childbearing age without a university degree.In addition, I nd a 5-10% increase in wages for women in childbearing age associated with the latter reform. Since this effect disappears when controlling for having a child in the future, this may indicate an increased need to signal commitment by increased effort after the reform
Seismic imaging of the shallow crust beneath the Krafla central volcano, NE Iceland
We studied the seismic velocity structure beneath the Krafla central volcano, NE Iceland, by performing 3-D tomographic inversions of 1453 earthquakes recorded by a temporary local seismic network between 2009 and 2012. The seismicity is concentrated primarily around the Leirhnjúkur geothermal field near the center of the Krafla caldera. To obtain robust velocity models, we incorporated active seismic data from previous surveys. The Krafla central volcano has a relatively complex velocity structure with higher P wave velocities (V_p) underneath regions of higher topographic relief and two distinct low-V_p anomalies beneath the Leirhnjúkur geothermal field. The latter match well with two attenuating bodies inferred from S wave shadows during the Krafla rifting episode of 1974–1985. Within the Leirhnjúkur geothermalreservoir, we resolved a shallow (−0.5 to 0.5 km below sea level; bsl) region with low-V_p/V_s values and a deeper (0.5–1.5 km bsl) high-V_p/V_s zone. We interpret the difference in the velocity ratios of the two zones to be caused by higher rock porosities and crack densities in the shallow region and lower porosities and crack densities in the deeper region. A strong low-V_p/V_s anomaly underlies these zones, where a superheated steam zone within felsic rock overlies rhyolitic melt
Leisure and Housing Consumption after Retirement: New Evidence on the Life-Cycle Hypothesis
We revisit the alleged retirement consumption puzzle. According to the life-cycle theory, foreseeable income reductions such as those around retirement should not affect consumption. However, we first recall that given higher leisure endowments after retirement, the theory does predict a fall of total market consumption expenditures. In order not to mistake this predicted drop for a puzzle we focus on housing consumption which can be plausibly regarded as complementary to leisure, and we control for the leisure change in our empirical specifications, using micro data for Germany (SOEP), where housing expenditures are observable as rents for the majority (60%), as well as dwelling relocations. We still find significant negative impacts of the retirement status on housing consumption, which is hard to reconcile with the life-cycle theory. For retirees we also find significant effects of the income reduction at retirement on housing. However, the effects are small in quantitative terms, given the lock-in nature of past housing decisions
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