Energy-based modelling of adhesive wear in the mixed lubrication regime

Adhesive wear in dry contacts is often described using the Archard or Fleischer model. Both provide equations for the determination of a wear volume, taking the load, the sliding path and a set of material parameters into account. While the Fleischer model is based on energetic approaches, the Archard formulation uses an empirical factor-the wear coefficient-describing the intensity of wear. Today, a numerical determination of the wear coefficient is already possible and both approaches can be deduced to a local accumulation of friction energy. The aim of this work is to enhance existing energy-based wear models into the mixed lubrication regime. Therefore, the pressure distribution within the contact area will be determined numerically taking real surface topographies into account. The emerging contact area will be divided into one part of solid and a second part of elastohydrodynamically lubricated (EHL) contacts. Based on the resulting pressure and shear stress distribution, the formation of micro cracks within the loaded volume will be described. Determining a critical number of load cycles for each asperity, a locally resolved wear coefficient will be derived and the local wear depth calculated

A mechanosensory receptor required for food texture detection in Drosophila.

Textural properties provide information on the ingestibility, digestibility and state of ripeness or decay of sources of nutrition. Compared with our understanding of the chemosensory assessment of food, little is known about the mechanisms of texture detection. Here we show that Drosophila melanogaster can discriminate food texture, avoiding substrates that are either too hard or too soft. Manipulations of food substrate properties and flies' chemosensory inputs indicate that texture preferences are revealed only in the presence of an appetitive stimulus, but are not because of changes in nutrient accessibility, suggesting that animals discriminate the substrates' mechanical characteristics. We show that texture preference requires NOMPC, a TRP-family mechanosensory channel. NOMPC localizes to the sensory dendrites of neurons housed within gustatory sensilla, and is essential for their mechanosensory-evoked responses. Our results identify a sensory pathway for texture detection and reveal the behavioural integration of chemical and physical qualities of food

A Comparison of Time-Memory Trade-Off Attacks on Stream Ciphers

Contains fulltext : 117176.pdf (preprint version ) (Open Access

The impact of participation in online cancer communities on patient reported outcomes:Systematic review

Background: In recent years, the question of how patients’ participating in online communities affects various patient reported outcomes (PROs) has been investigated in several ways. Objectives: This study aimed to systematically review all relevant literature identified using key search terms, with regard to, first, changes in PROs for cancer patients who participate in online communities and, second, the characteristics of patients who report such effects. Methods: A computerized search of the literature via PubMed (MEDLINE), PsycINFO (5 and 4 stars), Cochrane Central Register of Controlled Trials, and ScienceDirect was performed. Last search was conducted in June 2017. Studies with the following terms were included: (cancer patient) and (support group or health communities) and (online or Internet). A total of 21 studies were included and independently assessed by 2 investigators using an 11-item quality checklist. Results: The methodological quality of the selected studies varied: 12 were of high quality, eight were of adequate quality, and only one was of low quality. Most of the respondents were women (about 80%), most with breast cancer; their mean age was 50 years. The patients who were active in online support groups were mostly younger and more highly educated than the nonusers. The investigated PROs included general well-being (ie, mood and health), anxiety, depression, quality of life, posttraumatic growth, and cancer-related concerns. Only marginal effects—that is, PRO improvements—were found; in most cases they were insignificant, and in some cases they were contradictory. Conclusions: The main shortcoming of this kind of study is the lack of methodological instruments for reliable measurements. Furthermore, some patients who participate in online communities or interact with peers via Internet do not expect to measure changes in their PROs. If cancer survivors want to meet other survivors and share information or get support, online communities can be a trustworthy and reliable platform to facilitate opportunities or possibilities to make this happen. Keywords: cancer; survivors; patient reported outcomes; Internet; support group

Function and central projections of gustatory receptor neurons on the antenna of the noctuid moth Spodoptera littoralis

Chemosensory information is crucial for most insects to feed and reproduce. Olfactory signals are mainly used at a distance, whereas gustatory stimuli play an important role when insects directly contact chemical substrates. In noctuid moths, although the antennae are the main olfactory organ, they also bear taste sensilla. These taste sensilla detect sugars and hence are involved in appetitive learning but could also play an important role in food evaluation by detecting salts and bitter substances. To investigate this, we measured the responses of individual taste sensilla on the antennae of Spodoptera littoralis to sugars and salts using tip recordings. We also traced the projections of their neuronal axons into the brain. In each sensillum, we found one or two neurons responding to sugars: one NaCl-responsive and one water-sensitive neuron. Responses of these neurons were dose-dependent and similar across different locations on the antenna. Responses were dependent on the sex for sucrose and on both sex and location for glucose and fructose. We did not observe a spatial map for the projections from specific regions of the antennae to the deutocerebrum or the tritocerebrum/suboesophageal ganglion complex. In accordance with physiological recordings, back-fills from individual sensilla revealed up to four axons, in most cases targeting different projection zones

Simulative Investigations of the Influence of Surface Indentations on Residual Stresses on Inner Raceways for Roller Element Bearings

Resource-efficient machine elements are in the focus of current research. One of the most widely used machine elements are roller bearings. Thus, the optimization of bearings and their tribological properties promises to result in significant resource savings. Special focus is set on the bearing fatigue life, which may be significantly reduced by indentations on the raceways. The reduction in fatigue life can be caused by processes such as rolling over particles or by brinelling. These processes induce local stress peaks and lead to elastic-plastic deformations of the raceways. During the subsequent operation, the pile up of material around the indentations is flattened and hence the residual stresses change. Inside these so called shoulders stress pealcs, residual stresses and hardening effects occur possibly resulting in crack initiation, crack growth under cyclic loading, and eventually spalling of material. For deeper and more sharp-edged indentations the bearing fatigue life is reduced more. To quantify the influence of an indentation on the bearing rating life a calculation model was developed based on the approach of IOANNIDES, BERGLING and GABELLI. For this, a 3D-FE model is used to calculate the three dimensional stress fields by superposition of residual and load stresses