2,301 research outputs found
Heterogeneous shear in hard sphere glasses
There is growing evidence that the flow of driven amorphous solids is not
homogeneous, even if the macroscopic stress is constant across the system. Via
event driven molecular dynamics simulations of a hard sphere glass, we provide
the first direct evidence for a correlation between the fluctuations of the
local volume-fraction and the fluctuations of the local shear rate. Higher
shear rates do preferentially occur at regions of lower density and vice versa.
The temporal behavior of fluctuations is governed by a characteristic time
scale, which, when measured in units of strain, is independent of shear rate in
the investigated range. Interestingly, the correlation volume is also roughly
constant for the same range of shear rates. A possible connection between these
two observations is discussed.Comment: 5 pages, 4 figures, accepted at Phys. Rev. Let
Differential regulation of non-protein coding RNAs from Prader-Willi Syndrome locus
Prader-Willi Syndrome (PWS) is a neurogenetic disorder caused by the deletion of imprinted genes on the paternally inherited human chromosome 15q11-q13. This locus harbours a long non-protein-coding RNA (U-UBE3A-ATS) that contains six intron-encoded snoRNAs, including the SNORD116 and SNORD115 repetitive clusters. The 3′-region of U-UBE3A-ATS is transcribed in the cis-antisense direction to the ubiquitin-protein ligase E3A (UBE3A) gene. Deletion of the SNORD116 region causes key characteristics of PWS. There are few indications that SNORD115 might regulate serotonin receptor (5HT2C) pre-mRNA processing. Here we performed quantitative real-time expression analyses of RNAs from the PWS locus across 20 human tissues and combined it with deep-sequencing data derived from Cap Analysis of Gene Expression (CAGE-seq) libraries. We found that the expression profiles of SNORD64, SNORD107, SNORD108 and SNORD116 are similar across analyzed tissues and correlate well with SNORD116 embedded U-UBE3A-ATS exons (IPW116). Notable differences in expressions between the aforementioned RNAs and SNORD115 together with the host IPW115 and UBE3A cis-antisense exons were observed. CAGE-seq analysis revealed the presence of potential transcriptional start sites originated from the U-UBE3A-ATS spanning region. Our findings indicate novel aspects for the expression regulation in the PWS locus
Viscous coalescence of droplets: a Lattice Boltzmann study
The coalescence of two resting liquid droplets in a saturated vapor phase is
investigated by Lattice Boltzmann simulations in two and three dimensions. We
find that, in the viscous regime, the bridge radius obeys a t^{1/2}-scaling law
in time with the characteristic time scale given by the viscous time. Our
results differ significantly from the predictions of existing analytical
theories of viscous coalescence as well as from experimental observations.
While the underlying reason for these deviations is presently unknown, a simple
scaling argument is given that describes our results well.Comment: 12 pages, 10 figures; as published in Phys. Fluid
A Model-Based Framework for Simplified Collaboration of Legal and Software Experts in Data Protection Assessments
The protection of personal data has become an increasingly important issue. Legal norms focused on data protection, such as the GDPR, provide legally binding requirements for systems that process personal data. Article 25 of the GDPR refers to the obligation to Data Protection by Design and Default. This can be achieved by conducting DPLA of the system in the early stages of development and implementing data protection concepts where necessary. This ties in with Article 35, which refers to an obligation to conduct DPLA before the actual processing of data. To aid in conducting continuous DPLA during the design time of software systems, we propose a model-based collaboration framework. This framework not only aids in providing consistent views of the software system for legal experts and software architects but also simplifies communication between both parties. We discuss the overall goals and benefits of such a framework and go into detail about the processes that interact as part of the framework. We also try to align legal concepts with the processes and describe the continuous iterative development using the collaboration framework
Prediction of spiralling in BTA deep-Âhole drilling - estimating the system's eigenfrequencies
One serious problem in deepÂhole drilling is the formation of a dynamic disturbance called spiralling which causes holes with several lobes. Since such lobes are a severe impairment of the bore hole quality the formaÂtion of spiralling has to be prevented. Gessesse et al. [2] explain spiralling by the coincidence of bending modes and multiples of the rotation frequency. They derive this from an elaborate finite elements model of the process. In online measurements we detected slowly changing frequency patterns simÂilar to those calculated by Gessesse et al. We therefore propose a method
to estimate the parameters determining the change of frequencies over time from spectrogram data. This significantly simplifies the explanation of spiÂralling for practical applications compared to finite elements models which have to be correctly modified for each machine and tool assembly. It turns out that this simpler model achieves to explain the observed frequency patÂterns quite well.
We use this for estimating the variation of the frequencies as good as posÂsible. This opens up the opportunity to prevent spiralling by e.g. changing the rotary frequency
Local Models in Register Classification by Timbre
Investigating a data set containing different sounds of several instruments suggests that local modelling may be a promising approach to take into account different timbre characteristics of different instruments. For this reason, some basic ideas towards a local modelling are realized in this report yielding a framework for further studies
Shear-induced anisotropic decay of correlations in hard-sphere colloidal glasses
Spatial correlations of microscopic fluctuations are investigated via
real-space experiments and computer simulations of colloidal glasses under
steady shear. It is shown that while the distribution of one-particle
fluctuations is always isotropic regardless of the relative importance of shear
as compared to thermal fluctuations, their spatial correlations show a marked
sensitivity to the competition between shear-induced and thermally activated
relaxation. Correlations are isotropic in the thermally dominated regime, but
develop strong anisotropy as shear dominates the dynamics of microscopic
fluctuations. We discuss the relevance of this observation for a better
understanding of flow heterogeneity in sheared amorphous solids.Comment: 6 pages, 4 figure
Complexion-mediated martensitic phase transformation in Titanium
The most efficient way to tune microstructures and mechanical properties of metallic alloys lies in designing and using athermal phase transformations. Examples are shape memory alloys and high strength steels, which together stand for 1,500 million tons annual production. In these materials, martensite formation and mechanical twinning are tuned via composition adjustment for realizing complex microstructures and beneficial mechanical properties. Here we report a new phase transformation that has the potential to widen the application window of Ti alloys, the most important structural material in aerospace design, by nanostructuring them via complexion-mediated transformation. This is a reversible martensitic transformation mechanism that leads to a final nanolaminate structure of α″ (orthorhombic) martensite bounded with planar complexions of athermal ω (a–ω, hexagonal). Both phases are crystallographically related to the parent β (BCC) matrix. As expected from a planar complexion, the a–ω is stable only at the hetero-interface
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