1,216 research outputs found
Kinetic pathways of the Nematic-Isotropic phase transition as studied by confocal microscopy on rod-like viruses
We investigate the kinetics of phase separation for a mixture of rodlike
viruses (fd) and polymer (dextran), which effectively constitutes a system of
attractive rods. This dispersion is quenched from a flow-induced fully nematic
state into the region where the nematic and the isotropic phase coexist. We
show experimental evidence that the kinetic pathway depends on the overall
concentration. When the quench is made at high concentrations, the system is
meta-stable and we observe typical nucleation-and-growth. For quenches at low
concentration the system is unstable and the system undergoes a spinodal
decomposition. At intermediate concentrations we see the transition between
both demixing processes, where we locate the spinodal point.Comment: 11 pages, 6 figures, accepted in J. Phys.: Condens. Matter as
symposium paper for the 6th Liquid Matter Conference in Utrech
Job crafting and its relationships with person-job fit and meaningfulness: A three-wave study
Although scholars imply that job crafting contributes to person-job fit and meaningful work, to date, no study examined the relationships between these variables. The present three-wave weekbook study was designed to gain more knowledge about the influence of job crafting on person-job fit and meaningfulness. We collected data among a heterogeneous group of employees (N = 114) during three consecutive weeks (N = 430 occasions). At the end of their working week, employees reported their job crafting behaviors, their person-job fit (demands-abilities fit and needs-supplies fit), and the meaningfulness of their work that week. Results indicated that individuals who crafted their job by increasing their job resources (e.g., support, autonomy) and challenging job demands (e.g., participate in new projects), and by decreasing their hindering job demands (e.g., less emotional job demands) reported higher levels of person-job fit the next week. In turn, demands-abilities fit related to more meaningfulness in the final week. No support was found for alternative causal models. These findings suggest that by crafting their job demands and job resources, individuals can proactively optimize their person-job fit and as a consequence experience their work as meaningful
In silico predictions of variant deleteriousness in the genomes of pig species
Predicting the deleteriousness of observed genomic variants has taken a step forward with the development of the Combined Annotation Dependent Depletion (CADD) [1] methodology, as it allows for comparable evaluations of variants on a genome-wide scale for coding and non-coding variants respectively. ..
Chloroplast ultrastructure of sugar beet (Beta vulgaris L.) cultivated in normal and elevated CO2 concentrations with two contrasted nitrogen supplies
Cavitation-induced force transition in confined viscous liquids under traction
We perform traction experiments on simple liquids highly confined between
parallel plates. At small separation rates, we observe a simple response
corresponding to a convergent Poiseuille flow. Dramatic changes in the force
response occur at high separation rates, with the appearance of a force plateau
followed by an abrupt drop. By direct observation in the course of the
experiment, we show that cavitation accounts for these features which are
reminiscent of the utmost complex behavior of adhesive films under traction.
Surprisingly enough, this is observed here in purely viscous fluids.Comment: Submitted to Physical Review Letters on May 31, 2002. Related
informations on http://www.crpp.u-bordeaux.fr/tack.htm
Effective temperatures from the fluctuation-dissipation measurements in soft glassy materials
We have investigated the validity of the fluctuation-dissipation theorem (FDT) and the applicability of the concept of effective temperature in a number of non-equilibrium soft glassy materials. Using a combination of passive and active microrheology to measure displacement fluctuations and the mechanical response function of probe particles embedded in the materials, we have directly tested the validity of the FDT. Our results show no violation of the FDT over several decades in frequency (1–104 Hz) for hard-sphere colloidal glasses and colloidal glasses and gels of Laponite. We further extended the bandwidth of our measurements to lower frequencies (down to 0.1 Hz) using video microscopy to measure the displacement fluctuations, again without finding any deviations from the FDT
Integration through transients for Brownian particles under steady shear
Starting from the microscopic Smoluchowski equation for interacting Brownian
particles under stationary shearing, exact expressions for shear-dependent
steady-state averages, correlation and structure functions, and
susceptibilities are obtained, which take the form of generalized Green-Kubo
relations. They require integration of transient dynamics. Equations of motion
with memory effects for transient density fluctuation functions are derived
from the same microscopic starting point. We argue that the derived formal
expressions provide useful starting points for approximations in order to
describe the stationary non-equilibrium state of steadily sheared dense
colloidal dispersions.Comment: 17 pages, Submitted to J. Phys.: Condens. Matter; revised version
with minor correction
Printed elastic membranes for multimodal pacing and recording of human stem-cell-derived cardiomyocytes
Bioelectronic interfaces employing arrays of sensors and bioactuators are promising tools for the study, repair and engineering of cardiac tissues. They are typically constructed from rigid and brittle materials processed in a cleanroom environment. An outstanding technological challenge is the integration of soft materials enabling a closer match to the mechanical properties of biological cells and tissues. Here we present an algorithm for direct writing of elastic membranes with embedded electrodes, optical waveguides and microfluidics using a commercial 3D printing system and a palette of silicone elastomers. As proof of principle, we demonstrate interfacing of cardiomyocytes derived from human induced pluripotent stem cells (hiPSCs), which are engineered to express Channelrhodopsin-2. We demonstrate electrical recording of cardiomyocyte field potentials and their concomitant modulation by optical and pharmacological stimulation delivered via the membrane. Our work contributes a simple prototyping strategy with potential applications in organ-on-chip or implantable systems that are multi-modal and mechanically soft
Predicting tyrosinaemia: a mathematical model of 4-hydroxyphenylpyruvate dioxygenase inhibition by nitisinone in rats
Nitisinone or 2-(2-nitro-4-trifluoromethylbenzoyl)cyclohexane-1,3-dione, is a reversible inhibitor of 4-
hydroxyphenylpyruvate dioxygenase (HPPD), an enzyme important in tyrosine catabolism. Today, nitisinone is successfully used to treat Hereditary Tyrosinaemia type 1, although its original expected role was
as a herbicide. In laboratory animals, treatment with nitisinone leads to the elevation of plasma tyrosine (tyrosinaemia). In rats and Beagle dogs, repeat low-dose exposure to nitisinone leads to corneal opacities whilst similar studies in the mouse and Rhesus monkey showed no comparable toxicities or other treatment related findings. The differences in toxicological sensitivities have been related to the upper limit of the concentration of tyrosine that accumulates in plasma, which is driven by the amount/activity of tyrosine aminotransferase. A physiologically based, pharmacodynamics ordinary differential equation model of HPPD inhibition to bolus exposure of nitisinone in vivo is presented. Going beyond traditional approaches, asymptotic analysis is used to separate the different timescales of events involved in HPPD inhibition and tyrosinaemia. This analysis elucidates, in terms of the model parameters, a critical inhibitor concentration (at which tyrosine concentration starts to rise) and highlights the contribution of in vitro measured parameters to events in an in vivo system. Furthermore, using parameter-fitting methods, a systematically derived reduced model is shown to fit well to rat data, making explicit how the parameters are informed by such data. This model in combination with in vitro descriptors has potential as a surrogate for animal experimentation to predict tyrosinaemia, and further development can extend its application to other related medical scenarios
Adapting to an emerging social media landscape:The rise of informalization of company communication in tourism
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