Effects of Defects in Laser Additive Manufactured Ti-6Al-4V on Fatigue Properties

AbstractLaser Additive Manufacturing (LAM) enables economical production of complex lightweight structures as well as patient individual implants. Due to these possibilities the additive manufacturing technology gains increasing importance in the aircraft and the medical industry. Yet these industries obtain high quality standards and demand predictability of material properties for static and dynamic load cases. However, especially fatigue and crack propagation properties are not sufficiently determined. Therefore this paper presents an analysis and simulation of crack propagation behavior considering Laser Additive Manufacturing specific defects, such as porosity and surface roughness.For the mechanical characterization of laser additive manufactured titanium alloy Ti-6Al-4V, crack propagation rates are experimentally determined and used for an analytical modeling and simulation of fatigue. Using experimental results from HCF tests and simulated data, the fatigue and crack resistance performance is analyzed considering material specific defects and surface roughness. The accumulated results enable the reliable prediction of the defects influence on fatigue life of laser additive manufactured titanium components

Praxisbericht: Fachwissenschaft und Berufspraxis verbunden durch kollaboratives Peer Teaching im Studium des Lehramts an Beruflichen Schulen

Die Fachsystematik der beruflichen Fachrichtungen im Studium des Lehramts an Beruflichen Schulen steht in einem anhaltenden Widerspruch zu der Handlungsorientierung an den Schulen. Jedoch ist es aufgrund der Anforderungen an einzelne Fachrichtungen nicht immer einfach, diesen aufzulösen. In dieser Studie wird ein didaktisches Konzept vorgestellt, welches mittels eines Peer-Teaching-Ansatzes die Fachsystematik der fachwissenschaftlichen Lehrinhalte durch auf den späteren Lehrerberuf bezogene Lehrmethoden ergänzt. Das Konzept wurde in zwei Lehrveranstaltungen der beruflichen Fachrichtung Metalltechnik in Hamburg zur Anwendung gebracht und evaluiert. Es hat zu einer erhöhten Motivation und Selbstständigkeit der Studierenden bei gleichbleibender akademischer Leistung geführt

Responsible and Regulatory Conform Machine Learning for Medicine: A Survey of Challenges and Solutions

Machine learning is expected to fuel significant improvements in medical care. To ensure that fundamental principles such as beneficence, respect for human autonomy, prevention of harm, justice, privacy, and transparency are respected, medical machine learning systems must be developed responsibly. Many high-level declarations of ethical principles have been put forth for this purpose, but there is a severe lack of technical guidelines explicating the practical consequences for medical machine learning. Similarly, there is currently considerable uncertainty regarding the exact regulatory requirements placed upon medical machine learning systems. This survey provides an overview of the technical and procedural challenges involved in creating medical machine learning systems responsibly and in conformity with existing regulations, as well as possible solutions to address these challenges. First, a brief review of existing regulations affecting medical machine learning is provided, showing that properties such as safety, robustness, reliability, privacy, security, transparency, explainability, and nondiscrimination are all demanded already by existing law and regulations - albeit, in many cases, to an uncertain degree. Next, the key technical obstacles to achieving these desirable properties are discussed, as well as important techniques to overcome these obstacles in the medical context. We notice that distribution shift, spurious correlations, model underspecification, uncertainty quantification, and data scarcity represent severe challenges in the medical context. Promising solution approaches include the use of large and representative datasets and federated learning as a means to that end, the careful exploitation of domain knowledge, the use of inherently transparent models, comprehensive out-of-distribution model testing and verification, as well as algorithmic impact assessments

Pathogenesis of Avian Bornavirus in Experimentally Infected Cockatiels

Inoculation induced persistent infection, clinical signs, and seroconversion

Magnetic Resonance Imaging-Guided Focused Ultrasound Treatment of Symptomatic Uterine Fibroids Impact of Technology Advancement on Ablation Volumes in 115 Patients

Objectives: The aim of this study was to assess the impact of the advanced technology of the new ExAblate 2100 system (Insightec Ltd, Haifa, Israel) for magnetic resonance imaging (MRI)-guided focused ultrasound surgery on treatment outcomes in patients with symptomatic uterine fibroids, as measured by the nonperfused volume ratio. Materials and Methods: This is a retrospective analysis of 115 women (mean age, 42 years; range, 27-54 years) with symptomatic fibroids who consecutively underwent MRI-guided focused ultrasound treatment in a single center with the new generation ExAblate 2100 system from November 2010 to June 2011. Mean +/- SD total volume and number of treated fibroids (per patient) were 89 +/- 94 cm(3) and 2.2 +/- 1.7, respectively. Patient baseline characteristics were analyzed regarding their impact on the resulting nonperfused volume ratio. Results: Magnetic resonance imaging-guided focused ultrasound treatment was technically successful in 115 of 123 patients (93.5%). In 8 patients, treatment was not possible because of bowel loops in the beam pathway that could not be mitigated (n = 6), patient movement (n = 1), and system malfunction (n = 1). Mean nonperfused volume ratio was 88% +/- 15% (range, 38%-100%). Mean applied energy level was 5400 +/- 1200 J, and mean number of sonications was 74 +/- 27. No major complications occurred. Two cases of first-degree skin burn resolved within 1 week after the intervention. Of the baseline characteristics analyzed, only the planned treatment volume had a statistically significant impact on nonperfused volume ratio. Conclusions: With technological advancement, the outcome of MRI-guided focused ultrasound treatment in terms of the nonperfused volume ratio can be enhanced with a high safety profile, markedly exceeding results reported in previous clinical trials

Ultra low temperature microturbine for magic angle spinning system

We investigate the fluid dynamics of a microturbine system that is applied in a device for chemical and biological analysis—a so-called magic angle spinning (MAS) nuclear magnetic resonance (NMR) probe. The present system is utilized in a wide temperature range from 45K to 293 K. Pressurized air, nitrogen, or helium are used to drive a Pelton type microturbine. This turbine is mounted on a MAS rotor with a diameter between 0.7mm and 3.2 mm. The rotor system is equipped with a pressurized gas bearing that is operated by the same gas species as the turbine. Computational fluid dynamics (CFD) simulations have been performed and compared with fluid dynamics measurements of the MAS system for different diameters, temperatures, and spinning rates between 23 kHz and 120 kHz. To our knowledge, this work is the first comprehensive CFD and experimental study of such a wide temperature range that has been carried out for microturbines with pressurized gas bearings. The results show good agreement between measurements and CFD simulations with appropriate (real) gas models, i.e., the ideal gas model for air at room temperature, Peng–Robinson model for nitrogen at 105 K, and ideal gas model for helium at 45 K

Lack of association of genetic variants in genes of the endocannabinoid system with anorexia nervosa

<p>Abstract</p> <p>Background</p> <p>Several lines of evidence indicate that the central cannabinoid receptor 1 (CNR1) as well as the major endocannabinoid degrading enzymes fatty acid amide hydrolase (FAAH), N-acylethanolamine-hydrolyzing acid amidase (NAAA) and monoglyceride lipase (MGLL) are implicated in mediating the orexigenic effects of cannabinoids. The aim of this study was to analyse whether nucleotide sequence variations in the <it>CNR1</it>, <it>FAAH</it>, <it>NAAA </it>and <it>MGLL </it>genes are associated with anorexia nervosa (AN).</p> <p>Methods</p> <p>We analysed the association of a previously described (AAT)n repeat in the 3' flanking region of CNR1 as well as a total of 15 single nucleotide polymorphisms (SNPs) representative of regions with restricted haplotype diversity in <it>CNR1</it>, <it>FAAH</it>, <it>NAAA </it>or <it>MGLL </it>in up to 91 German AN trios (patient with AN and both biological parents) using the transmission-disequilibrium-test (TDT). One SNP was additionally analysed in an independent case-control study comprising 113 patients with AN and 178 normal weight controls. Genotyping was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, ARMS-PCR or using 3730xl capillary sequencers.</p> <p>Results</p> <p>The TDT revealed no evidence for association for any of the SNPs or the (AAT)n repeat with AN (all two-sided uncorrected p-values > 0.05). The lowest p-value of 0.11 was detected for the A-allele of the <it>CNR1 </it>SNP rs1049353 for which the transmission rate was 59% (95% confidence interval 47%...70%). Further genotyping of rs1049353 in 113 additional independent patients with AN and 178 normal weight controls could not substantiate the initial trend for association (p = 1.00).</p> <p>Conclusion</p> <p>As we found no evidence for an association of genetic variation in <it>CNR1</it>, <it>FAAH, NAAA and MGLL </it>with AN, we conclude that genetic variations in these genes do not play a major role in the etiology of AN in our study groups.</p

Plant and animal endemism in the eastern Andean slope: challenges to conservation

Andean slope: challenges to conservatio

Agroforestry creates carbon sinks whilst enhancing the environment in agricultural landscapes in Europe

Agroforestry, relative to conventional agriculture, contributes significantly to carbon sequestration, increases a range of regulating ecosystem services, and enhances biodiversity. Using a transdisciplinary approach, we combined scientific and technical knowledge to evaluate nine environmental pressures in terms of ecosystem services in European farmland and assessed the carbon storage potential of suitable agroforestry systems, proposed by regional experts. First, regions with potential environmental pressures were identified with respect to soil health (soil erosion by water and wind, low soil organic carbon), water quality (water pollution by nitrates, salinization by irrigation), areas affected by climate change (rising temperature), and by underprovision in biodiversity (pollination and pest control pressures, loss of soil biodiversity). The maps were overlaid to identify areas where several pressures accumulate. In total, 94.4% of farmlands suffer from at least one environmental pressure, pastures being less affected than arable lands. Regional hotspots were located in north-western France, Denmark, Central Spain, north and south-western Italy, Greece, and eastern Romania. The 10% of the area with the highest number of accumulated pressures were defined as Priority Areas, where the implementation of agroforestry could be particularly effective. In a second step, European agroforestry experts were asked to propose agroforestry practices suitable for the Priority Areas they were familiar with, and identified 64 different systems covering a wide range of practices. These ranged from hedgerows on field boundaries to fast growing coppices or scattered single tree systems. Third, for each proposed system, the carbon storage potential was assessed based on data from the literature and the results were scaled-up to the Priority Areas. As expected, given the wide range of agroforestry practices identified, the carbon sequestration potentials ranged between 0.09 and 7.29 t C ha−1 a−1. Implementing agroforestry on the Priority Areas could lead to a sequestration of 2.1 to 63.9 million t C a−1 (7.78 and 234.85

Mutations in GDP-mannose pyrophosphorylase b cause congenital and limb-girdle muscular dystrophies associated with hypoglycosylation of α-dystroglycan

Congenital muscular dystrophies with hypoglycosylation of α-dystroglycan (α-DG) are a heterogeneous group of disorders often associated with brain and eye defects in addition to muscular dystrophy. Causative variants in 14 genes thought to be involved in the glycosylation of α-DG have been identified thus far. Allelic mutations in these genes might also cause milder limb-girdle muscular dystrophy phenotypes. Using a combination of exome and Sanger sequencing in eight unrelated individuals, we present evidence that mutations in guanosine diphosphate mannose (GDP-mannose) pyrophosphorylase B (GMPPB) can result in muscular dystrophy variants with hypoglycosylated α-DG. GMPPB catalyzes the formation of GDP-mannose from GTP and mannose-1-phosphate. GDP-mannose is required for O-mannosylation of proteins, including α-DG, and it is the substrate of cytosolic mannosyltransferases. We found reduced α-DG glycosylation in the muscle biopsies of affected individuals and in available fibroblasts. Overexpression of wild-type GMPPB in fibroblasts from an affected individual partially restored glycosylation of α-DG. Whereas wild-type GMPPB localized to the cytoplasm, five of the identified missense mutations caused formation of aggregates in the cytoplasm or near membrane protrusions. Additionally, knockdown of the GMPPB ortholog in zebrafish caused structural muscle defects with decreased motility, eye abnormalities, and reduced glycosylation of α-DG. Together, these data indicate that GMPPB mutations are responsible for congenital and limb-girdle muscular dystrophies with hypoglycosylation of α-DG. © 2013 The American Society of Human Genetics.Funding for UK10K was provided by the Wellcome Trust under award WT091310