Powder compaction with polygonal particles built from radially extending one-dimensional frictional devices

Powder compaction is a major ingredient in a wide range of production techniques for objects of every day importance. Diverse applications – from pharmaceutical tablets to metallic and ceramic parts, where compaction is usually a part in the sintering process – are covered by current technology. The aim of cold compaction is to increase the relative density of the part. Due to the granular nature of the powder material compaction is random process which requires careful mastering and comprehensive understanding. The experimental access to compaction processes, even as simple ones as uniaxial compaction, are limited. Therefore simulation of compaction processes offers the opportunity to improve understanding of powder compaction. The Direct Element Method (DEM) simulates the powder as individual particles. These particles are distinct from each other and the forces applied to the entire powder are equilibrated by the contacting force between the particles. Usually, an explicit time integration, with or without considering dynamic effects, allows the particles to move and the powder to be compacted. Especially for metallic powders the plastic deformation of individual particles plays an important role and has a perceptible influence up to the macroscopic scale of the whole part. This leads to efforts to formulate a DE method in which individual particles are discretized as distinct FE models. Yet, such approach is deemed too costly for the simulation entire parts. Therefore a new approach for plastic particle deformation has been devised. The particles are simulated as ’hedgehogs’ of one-dimensional frictional devices. The frictional devices form spikes that extend in a radial way from the center of the particle. The tips of the spikes are connected and the connections form the edges of the polygonal particles. The contacts between the particles are found by geometric means as intersections of the spikes of one particle with the edges of the particle’s contact partner. This indents the spike and its frictional device generates forces that act on the two particles. Multiple contacts between two particles are allowed and concave particles can be treated intrinsically. Preliminary results indicate that this new approach to model plastic particles might bridge the gap between sufficiently realistic behaviour of the plastic particles and low computational effort. However, for now, the results are based on two-dimensional proofof-concept simulations and, for the sake of simplicity, the springs in the spikes are linear and the friction is rate-independent and perfectly plastic. These model assumption already offer considerable liberties to tune the plastic behaviour of the particles to experimental results

Does musical training improve school performance?

In a retrospective study, we compared school performance of 53 children practicing music (group1) with 67 controls not practicing music (group2). Overall average marks as well as average marks of all school subjects except sports were significantly higher in children who do (group1) than in those who do not practice music (group2). In a multiple regression analysis, musical training, parent's income, and educational level (grades) correlated significantly with overall average marks. A slight decrease of overall average marks over 4years from grades3 to 6 was found in the control group only. Musical training evidently correlates with children's better performance at school, but is obviously part of a multifactorial dependence. Continuous musical training appears to help achieve and maintain school performance at a high level over tim

Semi-Automatic, Inline and Collaborative Web Page Code Curations

Software developers spend about a quarter of their workday using the web to fulfill various information needs. Searching for relevant information online can be time-consuming, yet acquired information is rarely systematically persisted for later reference. In this work, we introduce SALI, an approach for semi-automated linking web pages to source code locations inline with the source code. SALI helps developers naturally capture high-quality, explicit links between web pages and specific source code locations by suggesting links for curation within the IDE. Through two laboratory studies, we examined the developer’s ability to both curate and consume links between web pages and specific source code locations while performing software development tasks. The studies were performed with 20 subjects working on realistic software change tasks from widely-used open-source projects. Results showed that developers continuously and concisely curate web pages at meaningful locations in the code with little effort. Additionally, we showed that other developers could use these curations while performing new and different change tasks to speed up relevant information gathering within unfamiliar codebases by a factor of 2.4

Investigating Speaker Embedding Disentanglement on Natural Read Speech

Disentanglement is the task of learning representations that identify and separate factors that explain the variation observed in data. Disentangled representations are useful to increase the generalizability, explainability, and fairness of data-driven models. Only little is known about how well such disentanglement works for speech representations. A major challenge when tackling disentanglement for speech representations are the unknown generative factors underlying the speech signal. In this work, we investigate to what degree speech representations encoding speaker identity can be disentangled. To quantify disentanglement, we identify acoustic features that are highly speaker-variant and can serve as proxies for the factors of variation underlying speech. We find that disentanglement of the speaker embedding is limited when trained with standard objectives promoting disentanglement but can be improved over vanilla representation learning to some extent.Comment: To be published at 15th ITG conference on speech communicatio

Spiders can be recognized by counting their legs

Spiders are arthropods that can be distinguished from their closest relatives, the insects, by counting their legs. Spiders have 8, insects just 6. Spider graphs are a very restricted class of graphs that naturally appear in the context of cograph editing. The vertex set of a spider (or its complement) is naturally partitioned into a clique (the body), an independent set (the legs), and a rest (serving as the head). Here we show that spiders can be recognized directly from their degree sequences through the number of their legs (vertices with degree 1). Furthermore, we completely characterize the degree sequences of spiders

A Single‐Step Hot Embossing Process for Integration of Microlens Arrays in Biodegradable Substrates for Improved Light Extraction of Light‐Emitting Devices

Integration of light management solutions relying on biodegradable materials in organic light‐emitting devices could assist the development of sustainable light sources or conformable and wearable display technology. Using industrially relevant processing techniques, it is shown that microlens arrays can be seamlessly integrated into flexible and biodegradable cellulose diacetate substrates to facilitate extraction of the trapped substrate modes in light‐emitting electrochemical cells. The substrates are patterned for light extraction and optimized for scalable printing processes in a single step by thermally embossing microlenses with polydimethylsiloxane molds on one substrate surface and simultaneous flattening of the other. Furthermore, by implementing the biopolymer substrate with microlens arrays, the total volume fraction of biodegradable materials in the microlense equipped device is 99.94%. The embossed microstructures on the biopolymer substrates are investigated by means of scanning electron microscopy and the angular light extraction profile of the devices is measured and compared to ray tracing simulations. Light‐emitting electrochemical cells with integrated microlens array substrates achieve an efficiency enhancement factor of 1.45, exceeding conventional organic light‐emitting diodes on glass substrates with laminated microlens arrays (enhancement factor of 1.23)

Delineation of Source Protection Zones Using Statistical Methods

Source protection zones are increasingly important for securing the long-term viability of drinking water derived from groundwater resources. These may be either time-related capture zones or catchments related to the activity of a pumping well or spring. The establishment of such zones is an indispensable measure for the proper assessment of groundwater resource vulnerability and reduction of risk, which may be induced by human activities. The delineation of these protection zones is usually performed with the aid of models, which are in turn based on site-specific information of the aquifer's geometry, hydraulic parameters and boundary conditions. Owing to the imperfect knowledge of such information, predicting the location of these zones is inherently uncertain. It is possible to quantify this uncertainty in a statistical manner through the development of probability maps, which shows the probability that a particular surface location belongs to the aquifer's capture zone (or catchment area). This publication aims at the investigation of the requirements for the establishment of probabilistic source protection zones, the practical use of stochastic methods in their delineation, and the use of data-assimilation for uncertainty reduction. It also provides a methodology for the implementation of these methods by modelling practitioner

Loss of LKB1-NUAK1 signalling enhances NF-κB activity in a spheroid model of high-grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) is an aggressive malignancy often diagnosed at an advanced stage. Although most HGSOC patients respond initially to debulking surgery combined with cytotoxic chemotherapy, many ultimately relapse with platinum-resistant disease. Thus, improving outcomes requires new ways of limiting metastasis and eradicating residual disease. We identified previously that Liver kinase B1 (LKB1) and its substrate NUAK1 are implicated in EOC spheroid cell viability and are required for efficient metastasis in orthotopic mouse models. Here, we sought to identify additional signalling pathways altered in EOC cells due to LKB1 or NUAK1 loss-of-function. Transcriptome analysis revealed that inflammatory signalling mediated by NF-κB transcription factors is hyperactive due to LKB1-NUAK1 loss in HGSOC cells and spheroids. Upregulated NF-κB signalling due to NUAK1 loss suppresses reactive oxygen species (ROS) production and sustains cell survival in spheroids. NF-κB signalling is also activated in HGSOC precursor fallopian tube secretory epithelial cell spheroids, and is further enhanced by NUAK1 loss. Finally, immunohistochemical analysis of OVCAR8 xenograft tumors lacking NUAK1 displayed increased RelB expression and nuclear staining. Our results support the idea that NUAK1 and NF-κB signalling pathways together regulate ROS and inflammatory signalling, supporting cell survival during each step of HGSOC pathogenesis. We propose that their combined inhibition may be efficacious as a novel therapeutic strategy for advanced HGSOC

Mood and neural responses to social rejection do not seem to be altered in resilient adolescents with a history of adversity.

Childhood adversity (CA) increases the risk of subsequent mental health problems. Adolescent social support (from family and/or friends) reduces the risk of mental health problems after CA. However, the mechanisms of this effect remain unclear, and we speculate that they are manifested on neurodevelopmental levels. Therefore, we investigated whether family and/or friendship support at ages 14 and 17 function as intermediate variables for the relationship between CA before age 11 and affective or neural responses to social rejection feedback at age 18. We studied 55 adolescents with normative mental health at age 18 (26 with CA and therefore considered "resilient"), from a longitudinal cohort. Participants underwent a Social Feedback Task in the magnetic resonance imaging scanner. Social rejection feedback activated the dorsal anterior cingulate cortex and the left anterior insula. CA did not predict affective or neural responses to social rejection at age 18. Yet, CA predicted better friendships at age 14 and age 18, when adolescents with and without CA had comparable mood levels. Thus, adolescents with CA and normative mood levels have more adolescent friendship support and seem to have normal mood and neural responses to social rejection.This work was supported by grants from Friends of Peterhouse Medical Fund Cambridge (RG 51114), the Wellcome Trust (RG 074296), and the UK Medical Research Council (MC US A060 0019). JF is supported by the Medical Research Council Doctoral Training/Sackler Fund and the Pinsent Darwin Fund. JS is supported by the UK Medical Research Council (MC US A060 0019). ADA is supported by the Aker Scholarship. SS is supported by the Wellcome Trust (209127/Z/17/Z). IMG is funded by a Wellcome Trust Strategic Award and declares consulting to Lundbeck. ALvH is supported by the Royal Society (DH15017 & RGF\EA\180029 & RGF\RI\180064), and MQ (MQBFC/2). Funders of the authors played no role in the study conduction, analysis performance, or the reporting of the study