Model-based tool design for the manufacturing of hypocycloidal internal profiles by polygon turning

Polygon turning is a machining process for manufacturing internal and external hypocycloidal profiles, which are becoming increasingly important for shaft-hub-connections. The highly productive process can be integrated on lathe machines. Existing analytical models are not sufficient to address the main challenge when designing tools for manufacturing internal profiles. In this work a dexel-based numerical approach is presented to calculate the limits of tool design. The findings are made usable for tool design with an analogy model and are finally validated experimentally using an alternative drive system for bone screws as an example

Optogenetics and electron microscopy reveal an ultrafast mode of synaptic vesicle recycling, adding a new twist to a 40-year-old controversy

Optogenetics and electron microscopy reveal an ultrafast mode of synaptic vesicle recycling, adding a new twist to a 40-year-old controversy. - See more at: http://elifesciences.org/content/2/e01233#sthash.K8kQedyo.dpu

Tool wear development in gear skiving process of quenched and tempered internal gears = Entwicklung des Werkzeugverschleißes beim Wälzschälen von vergüteten Innenverzahnungen

Das Wälzschälen ist ein hochproduktives Bearbeitungsverfahren, insbesondere für die Herstellung von hochfesten Innenverzahnungen, wie sie für elektrische Hochleistungsantriebe benötigt werden. Die komplexe Prozesskinematik verursacht jedoch starke Schwankungen der lokal wirksamen Prozesskenngrößen während des Werkzeugeingriffs, sodass insbesondere an das Werkzeug hohe Anforderungen gestellt werden, um eine hohe Standzeit bei geforderter Werkstückqualität zu erreichen. Diese Anforderungen werden bei der Zerspanung von vergüteten Werkstoffen aus dem Vollen noch weiter verstärkt. In der vorliegenden Studie wird der Einfluss verschiedener Schlüsselfaktoren auf die Entwicklung des Werkzeugverschleißes beim Wälzschälen quantifiziert. In mehreren Versuchen werden die Schnittgeschwindigkeit, die Werkstückzugfestigkeit, die Kühlschmierstrategie und die Schnittstrategie variiert, um die Werkzeugstandzeit zu optimieren. Dazu werden Einzelzahnversuche an vergüteten Innenverzahnungen aus 31CrMoV9 (AISI 4340) durchgeführt und die Entwicklung der Verschleißmarkenbreite der Werkzeuge untersucht. Zudem wird das Werkstück hinsichtlich der gefertigten Oberflächenqualität bewertet. Die Ergebnisse zeigen, dass verschiedene Faktorenkombinationen unterschiedliche Auswirkungen auf das Verschleißverhalten der Werkzeuge und damit auf die Standzeit haben können. Die vorgestellten Korrelationen geben Empfehlungen für die praktische Anwendung und tragen zu einem tieferen Prozessverständnis bei

Smoking and γ-Glutamyltransferase: Opposite Interactions with Alcohol Consumption and Body Mass Index

BACKGROUND: Smoking has recently been suggested to synergistically interact with alcohol intake as a determinant of serum gamma-glutamyltransferase (γ-GT), an emergent powerful predictor of disease and mortality. This study investigated whether this also applies to higher smoking and alcohol exposure ranges and to body mass index (BMI), which likewise is strongly associated with γ-GT. METHODOLOGY/PRINCIPAL FINDINGS: Analyses were based on occupational health examinations of more than 15,000 German male workers aged 16-64 years, predominantly from the construction industry. Sociodemographics and other health-related information were collected during the exam. Joint associations of smoking and alcohol consumption or BMI with elevated or log-transformed γ-GT were examined by tabulation and multiple adjusted regression models. Cigarette smoking exerted no effect on γ-GT in teetotalers, but there was a statistically significant effect of smoking among participants with higher alcohol consumption intensity, odds of elevated γ-GT being increased by 24% and 27% per additional 10 cigarettes smoked per day in subjects drinking 61-90 and >90 gram alcohol per day, respectively (P for interaction = 0.039). The interaction was opposite for BMI, where no association was seen in obese subjects, whereas odds of elevated γ-GT were increased by 24% per 10 cigarettes below 25 kg/m(2) (P for interaction = 0.040). This novel interaction was replicable in an independent cohort. CONCLUSION: The evidence for opposite interactions of smoking with alcohol and BMI as determinants of serum γ-GT suggests that different physiological pathways are responsible for the associations between these factors

Quality of life and physical activity in long-term (≥5 years post-diagnosis) colorectal cancer survivors - systematic review

Background: Due to the increasing number of long-term (≥5 years post diagnosis) colorectal cancer survivors, long-term quality of life of these patients is highly relevant. Several studies have reported a positive association between physical activity and quality of life in colorectal cancer survivors, however, so far no systematic review has been published which focuses on long-term colorectal cancer survivors. Material and methods: A systematic review was conducted using the databases PubMed, Web of Science, PsychINFO, and CINAHL. Studies which investigated associations between physical activity and quality of life in long-term colorectal cancer survivors were included. Results and conclusion: Ten articles based on seven studies were identified. Long-term colorectal cancer survivors who were physically active reported better quality of life than long-term survivors who were not physically active. Both, moderate to vigorous physical activity and lower levels like light physical activity were associated with higher quality of life. Most studies assessed the association between physical activity and quality of life cross-sectionally but one prospective study which measured physical activity and quality of life at three different points in time also found associations between physical activity and quality of life. The association between physical activity and quality of life seemed to be stronger among women than among men. The findings of this systematic review support an association between physical activity and quality of life in long-term colorectal cancer survivors. However, the evidence is limited as most studies were based on cross-sectional and observational design

Potentiale und Herausforderungen der Materialflusskostenrechnung

The article gives a description of the method of material flow cost accounting. Secondly general obstacles and capabilities are described. The gathering of the necessary data is a serious problem for applying companies. A series of software requirements, with the potential to reduce the problem, were determined through a usability study and are presented in the last part. The implementation of these requirements can help to diminish the obstacles and help with the diffusion of the method