404 research outputs found
Force balance in canonical ensembles of static granular packings
We investigate the role of local force balance in the transition from a
microcanonical ensemble of static granular packings, characterized by an
invariant stress, to a canonical ensemble. Packings in two dimensions admit a
reciprocal tiling, and a collective effect of force balance is that the area of
this tiling is also invariant in a microcanonical ensemble. We present
analytical relations between stress, tiling area and tiling area fluctuations,
and show that a canonical ensemble can be characterized by an intensive
thermodynamic parameter conjugate to one or the other. We test the equivalence
of different ensembles through the first canonical simulations of the force
network ensemble, a model system.Comment: 9 pages, 9 figures, submitted to JSTA
Heat conduction in the disordered harmonic chain revisited
A general formulation is developed to study heat conduction in disordered
harmonic chains with arbitrary heat baths that satisfy the
fluctuation-dissipation theorem. A simple formal expression for the heat
current J is obtained, from which its asymptotic system-size (N) dependence is
extracted. It is shown that the ``thermal conductivity'' depends not just on
the system itself but also on the spectral properties of the fluctuation and
noise used to model the heat baths. As special cases of our heat baths we
recover earlier results which reported that for fixed boundaries , while for free boundaries . For other choices we
find that one can get other power laws including the ``Fourier behaviour'' .Comment: 5 pages, 3 figures, accepted for publication in Phys. Rev. Let
Playing for Data: Ground Truth from Computer Games
Recent progress in computer vision has been driven by high-capacity models
trained on large datasets. Unfortunately, creating large datasets with
pixel-level labels has been extremely costly due to the amount of human effort
required. In this paper, we present an approach to rapidly creating
pixel-accurate semantic label maps for images extracted from modern computer
games. Although the source code and the internal operation of commercial games
are inaccessible, we show that associations between image patches can be
reconstructed from the communication between the game and the graphics
hardware. This enables rapid propagation of semantic labels within and across
images synthesized by the game, with no access to the source code or the
content. We validate the presented approach by producing dense pixel-level
semantic annotations for 25 thousand images synthesized by a photorealistic
open-world computer game. Experiments on semantic segmentation datasets show
that using the acquired data to supplement real-world images significantly
increases accuracy and that the acquired data enables reducing the amount of
hand-labeled real-world data: models trained with game data and just 1/3 of the
CamVid training set outperform models trained on the complete CamVid training
set.Comment: Accepted to the 14th European Conference on Computer Vision (ECCV
2016
Angoricity and compactivity describe the jamming transition in soft particulate matter
The application of concepts from equilibrium statistical mechanics to
out-of-equilibrium systems has a long history of describing diverse systems
ranging from glasses to granular materials. For dissipative jammed systems--
particulate grains or droplets-- a key concept is to replace the energy
ensemble describing conservative systems by the volume-stress ensemble. Here,
we test the applicability of the volume-stress ensemble to describe the jamming
transition by comparing the jammed configurations obtained by dynamics with
those averaged over the ensemble as a probe of ergodicity. Agreement between
both methods suggests the idea of "thermalization" at a given angoricity and
compactivity. We elucidate the thermodynamic order of the jamming transition by
showing the absence of critical fluctuations in static observables like
pressure and volume. The approach allows to calculate observables such as the
entropy, volume, pressure, coordination number and distribution of forces to
characterize the scaling laws near the jamming transition from a statistical
mechanics viewpoint.Comment: 27 pages, 13 figure
Parity Effect and Charge Binding Transition in Submicron Josephson Junction Arrays
We reconsider the issue of Berezinskii-Kosterlitz-Thouless (BKT) transition
into an insulating state in the Coulomb-dominated Josephson junction arrays. We
show that previously predicted picture of the Cooper-pair BKT transtion at T =
T_2 is valid only under the condition that T_2 is considerably below the
parity-effect temperature (which is usually almost 10 times below the value of
superconductive transition temperature), and even in this case it is not a
rigorous phase transition but only a crossover, whereas the real phase
transition takes place at T_1 = T_2/4. Our theory is in agreement with
available experimental data on Coulomb-dominated Josephson arrays and also
sheds some light on the origin of unusual reentrant temperature dependence of
resistivity in the array with nearly-criticial ratio of Coulomb to Josephson
energies.Comment: 4 pages, Revtex, to be published in JETP Letters, April 9
Future aspects of renal transplantation
New and exciting advances in renal transplantation are continuously being made, and the horizons for organ transplantation are bright and open. This article reviews only a few of the newer advances that will allow renal transplantation to become even more widespread and successful. The important and exciting implications for extrarenal organ transplantation are immediately evident. © 1988 Springer-Verlag
Full capacitance-matrix effects in driven Josephson-junction arrays
We study the dynamic response to external currents of periodic arrays of
Josephson junctions, in a resistively capacitively shunted junction (RCSJ)
model, including full capacitance-matrix effects}. We define and study three
different models of the capacitance matrix : Model A
includes only mutual capacitances; Model B includes mutual and self
capacitances, leading to exponential screening of the electrostatic fields;
Model C includes a dense matrix that is constructed
approximately from superposition of an exact analytic solution for the
capacitance between two disks of finite radius and thickness. In the latter
case the electrostatic fields decay algebraically. For comparison, we have also
evaluated the full capacitance matrix using the MIT fastcap algorithm, good for
small lattices, as well as a corresponding continuum effective-medium analytic
evaluation of a finite voltage disk inside a zero-potential plane. In all cases
the effective decays algebraically with distance, with
different powers. We have then calculated current voltage characteristics for
DC+AC currents for all models. We find that there are novel giant capacitive
fractional steps in the I-V's for Models B and C, strongly dependent on the
amount of screening involved. We find that these fractional steps are quantized
in units inversely proportional to the lattice sizes and depend on the
properties of . We also show that the capacitive steps
are not related to vortex oscillations but to localized screened phase-locking
of a few rows in the lattice. The possible experimental relevance of these
results is also discussed.Comment: 12 pages 18 Postscript figures, REVTEX style. Paper to appear in July
1, Vol. 58, Phys. Rev. B 1998 All PS figures include
Quantum interference and Coulomb interaction in arrays of tunnel junctions
We study the electronic properties of an array of small metallic grains
connected by tunnel junctions. Such an array serves as a model for a granular
metal. Previous theoretical studies of junction arrays were based on models of
quantum dissipation which did not take into account the diffusive motion of
electrons within the grains. We demonstrate that these models break down at
sufficiently low temperatures: for a correct description of the screening
properties of a granular metal at low energies the diffusive nature of the
electronic motion within the grains is crucial. We present both a diagrammatic
and a functional integral approach to analyse the properties of junction
arrays. In particular, a new effective action is obtained which enables us to
describe the array at arbitrary temperature. In the low temperature limit, our
theory yields the correct, dynamically screened Coulomb interaction of a normal
metal, whereas at high temperatures the standard description in terms of
quantum dissipation is recovered.Comment: 14 pages, 7 figure
What are the mechanisms that support healthcare professionals to adopt assisted decision-making practice? A rapid realist review
Background
The United Nations Convention on the Rights of Persons with Disabilities (UNCRPD) establishes a right to legal capacity for all people, including those with support needs. People with disabilities have a legal right to be given the appropriate supports to make informed decisions in all aspects of their lives, including health. In Ireland, the Assisted Decision-Making (Capacity) Act (2015) ratifies the Convention and has established a legal framework for Assisted Decision Making (ADM). The main provisions of the Act are not yet implemented. Codes of Practice to guide health and social care professionals are currently being developed. Internationally, concerns are expressed that ADM implementation is poorly understood. Using realist synthesis, this study aims to identify Programme Theory (PT) that will inform ADM implementation in healthcare.
Methods
A Rapid Realist Review using collaborative methods was chosen to appraise relevant literature and engage knowledge users from Irish health and social care. The review was led by an expert panel of relevant stakeholders that developed the research question which asks, ‘what mechanisms enable healthcare professionals to adopt ADM into practice?’
To ensure the PT was inclusive of local contextual influences, five reference panels were conducted with healthcare professionals, family carers and people with dementia. PT was refined and tested iteratively through knowledge synthesis informed by forty-seven primary studies, reference panel discussions and expert panel refinement and consensus.
Results
The review has developed an explanatory PT on ADM implementation in healthcare practice. The review identified four implementation domains as significant. These are Personalisation of Health & ADM Service Provision, Culture & Leadership, Environmental & Social Re-structuring and Education, Training & Enablement. Each domain is presented as an explanatory PT statement using realist convention that identifies context, mechanism and outcome configurations.
Conclusions
This realist review makes a unique contribution to this field. The PT can be applied by policymakers to inform intervention development and implementation strategy. It informs the imminent policy and practice developments in Ireland and has relevance for other worldwide healthcare systems dealing with similar legislative changes in line with UNCRPD
Reclassification of the polyphyletic genus Prosthecomicrobium to form two novel genera, Vasilyevaea gen. nov. and Bauldia gen. nov. with four new combinations: Vasilyevaea enhydra comb. nov., Vasilyevaea mishustinii comb. nov., Bauldia consociata comb. nov. and Bauldia litoralis comb. nov.
Species of the genus Prosthecomicrobium are noted for their numerous cellular appendages or prosthecae that extend from the cells. This investigation confirms that the genus is polyphyletic based on an extensive analysis of the 16S rRNA gene sequences of several named species of the genus. The analyses indicate that some Prosthecomicrobium species are more closely related to non-prosthecate genera, including Devosia, Labrenzia, Blastochloris, Methylosinus, Mesorhizobium and Kaistia, than they are to other species of the genus Prosthecomicrobium. For this reason, two of the Prosthecomicrobium clades which are polyphyletic with the type species, Prosthecomicrobium pneumaticum, are renamed as new genera. The currently named species Prosthecomicrobium enhydrum, Prosthecomicrobium mishustinii, Prosthecomicrobium consociatum and Prosthecomicrobium litoralum are reclassified in two new genera, Vasilyevaea gen. nov. and Bauldia gen. nov. with four new combinations: Vasilyevaea enhydra comb. nov. (the type species) and Vasilyevaea mishustinii comb. nov., and Bauldia consociata comb. nov. and Bauldia litoralis comb. nov. (the type species). The type strain of Vasilyevaea enhydra is strain 9bT (=ATCC 23634T =VKM B-1376T). The type strain of the other species in this genus is Vasilyevaea mishustinii strain 17T (=VKM B-2499T =CCM 7569T). The type strain of Bauldia litoralis is strain 524-16T (= NCIB 2233T =ATCC 35022T). The type strain of the other species in this genus is Bauldia consociata strain 11T (=VKM B-2498T =CCM 7594T)
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