6,951 research outputs found
A temperature-dependent phase-field model for phase separation and damage
In this paper we study a model for phase separation and damage in
thermoviscoelastic materials. The main novelty of the paper consists in the
fact that, in contrast with previous works in the literature (cf., e.g., [C.
Heinemann, C. Kraus: Existence results of weak solutions for Cahn-Hilliard
systems coupled with elasticity and damage. Adv. Math. Sci. Appl. 21 (2011),
321--359] and [C. Heinemann, C. Kraus: Existence results for diffuse interface
models describing phase separation and damage. European J. Appl. Math. 24
(2013), 179--211]), we encompass in the model thermal processes, nonlinearly
coupled with the damage, concentration and displacement evolutions. More in
particular, we prove the existence of "entropic weak solutions", resorting to a
solvability concept first introduced in [E. Feireisl: Mathematical theory of
compressible, viscous, and heat conducting fluids. Comput. Math. Appl. 53
(2007), 461--490] in the framework of Fourier-Navier-Stokes systems and then
recently employed in [E. Feireisl, H. Petzeltov\'a, E. Rocca: Existence of
solutions to a phase transition model with microscopic movements. Math. Methods
Appl. Sci. 32 (2009), 1345--1369], [E. Rocca, R. Rossi: "Entropic" solutions to
a thermodynamically consistent PDE system for phase transitions and damage.
SIAM J. Math. Anal., 47 (2015), 2519--2586] for the study of PDE systems for
phase transition and damage. Our global-in-time existence result is obtained by
passing to the limit in a carefully devised time-discretization scheme
Study of the Hofmann reaction between sodium hypochlorite and succinamide. Preparation of isopropylidene bis-phenylen oxydiacetic acid. Preparation of polyamides
In the Hofmann reaction between succinamide and potassium hypobromite, small yields of dihydrouracil have been obtained. From the reaction of succinamide and sodium hypochlorite it was hoped that larger yields of the dihydrouracil could be obtained and through spectrophotometry identify the compound further
DPP-PMRF: Rethinking Optimization for a Probabilistic Graphical Model Using Data-Parallel Primitives
We present a new parallel algorithm for probabilistic graphical model
optimization. The algorithm relies on data-parallel primitives (DPPs), which
provide portable performance over hardware architecture. We evaluate results on
CPUs and GPUs for an image segmentation problem. Compared to a serial baseline,
we observe runtime speedups of up to 13X (CPU) and 44X (GPU). We also compare
our performance to a reference, OpenMP-based algorithm, and find speedups of up
to 7X (CPU).Comment: LDAV 2018, October 201
Development of macroscopic waveguide and waveguide components for optical systems Final report, 28 Jan. - 28 Nov. 1964
Macroscopic waveguide and waveguide components for optical systems - laser
How bacteria recognise and respond to surface contact
Bacterial biofilms can cause medical problems and issues in technical systems. While a large body of knowledge exists on the phenotypes of planktonic and of sessile cells in mature biofilms, our understanding of what happens when bacteria change from the planktonic to the sessile state is still very incomplete. Fundamental questions are unanswered: for instance, how do bacteria sense that they are in contact with a surface, and what are the very initial cellular responses to surface contact. Here, we review the current knowledge on the signals that bacteria could perceive once they attach to a surface, the signal transduction systems that could be involved in sensing the surface contact and the cellular responses that are triggered as a consequence to surface contact ultimately leading to biofilm formation. Finally, as the main obstacle in investigating the initial responses to surface contact has been the difficulty to experimentally study the dynamic response of single cells upon surface attachment, we also review recent experimental approaches that could be employed to study bacterial surface sensing, which ultimately could lead to an improved understanding of how biofilm formation could be prevented
Hidden quantum phase transition in MnFeGe: evidence brought by small-angle neutron scattering
The magnetic system of the MnFeGe solid solution is ordered in
a spiral spin structure in the whole concentration range of .
The close inspection of the small-angle neutron scattering data reveals the
quantum phase transition from the long-range ordered (LRO) to short range
ordered (SRO) helical structure upon increase of Fe-concentration at . The SRO of the helical structure is identified as a
Lorentzian contribution, while LRO is associated with the Gaussian contribution
into the scattering profile function. The scenario of the quantum phase
transition with as a driving parameter is similar to the thermal phase
transition in pure MnGe. The quantum nature of the SRO is proved by the
temperature independent correlation length of the helical structure at low and
intermediate temperature ranges with remarkable decrease above certain
temperature . We suggest the -dependent modification of the effective
Ruderman-Kittel-Kasuya-Yosida exchange interaction within the Heisenberg model
of magnetism to explain the quantum critical regime in MnFeGe.Comment: 6 pages, 4 figure
Can a Postmodern Philosopher Teach Modern Philosophy?
This paper considers the following question: how can those whose thought is informed by poststructuralist values, arguments, and training legitimately teach the history of philosophy? In answering this question, three pedagogical approaches to courses in the history of philosophy are considered and criticized: the representational, the phenomenological, and the conversational. Although these three approaches are seemingly exhaustive, each is problematic because the question they attempt to answer rests on the false assumption that there is one, universally right way to teach philosophy and many wrong ways. In rejecting this assumption, the author considers a new, more concrete, and contextualized question concerning teaching philosophy from a postmodern perspective
Orbital stability in static axisymmetric fields
We investigate the stability of test-particle equilibrium orbits in
axisymmetric, but otherwise arbitrary, gravitational and electromagnetic
fields. We extend previous studies of this problem to include a toroidal
magnetic field. We find that, even though the toroidal magnetic field does not
alter the location of the circular orbits, it enters the problem as a
gyroscopic force with the potential to provide gyroscopic stability. This is in
essence similar to the situation encountered in the reduced three-body problem
where rotation enables stability around the local maxima of the effective
potential. Nevertheless, we show that gyroscopic stabilization by a toroidal
magnetic field is impossible for axisymmetric force fields in source-free
regions because in this case the effective potential does not possess any local
maxima. As an example of an axisymmetric force field with sources, we consider
the classical problem of a rotating, aligned magnetosphere. By analyzing the
dynamics of halo and equatorial particle orbits we conclude that axisymmetric
toroidal fields that are antisymmetric about the equator are unable to provide
gyroscopic stabilization. On the other hand, a toroidal magnetic field that
does not vanish at the equator can provide gyroscopic stabilization for
positively charged particles in prograde equatorial orbits.Comment: 11 pages, 3 figures, submitted to Celestial Mechanics and Dynamical
Astronom
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