726 research outputs found
Evidence of a glass transition in a 10-state non-mean-field Potts glass
Potts glasses are prototype models that have been used to understand the
structural glass transition. However, in finite space dimensions a glass
transition remains to be detected in the 10-state Potts glass. Using a
one-dimensional model with long-range power-law interactions we present
evidence that a glass transition below the upper critical dimension can exist
for short-range systems at low enough temperatures. Gaining insights into the
structural glass transition for short-range systems using spin models is thus
potentially possible, yet difficult.Comment: 4 pages, 1 table, 2 figure
Numerical studies of a one-dimensional 3-spin spin-glass model with long-range interactions
We study a p-spin spin-glass model to understand if the finite-temperature
glass transition found in the mean-field regime of p-spin models, and used to
model the behavior of structural glasses, persists in the non-mean-field
regime. By using a 3-spin spin-glass model with long-range power-law diluted
interactions we are able to continuously tune the (effective) space dimension
via the exponent of the interactions. Monte Carlo simulations of the spin-glass
susceptibility and the two-point finite-size correlation length show that deep
in the non-mean-field regime the finite-temperature transition is lost, whereas
this is not the case in the mean-field regime, in agreement with the prediction
of Moore and Drossel [Phys. Rev. Lett. 89, 217202 (2002)] that 3-spin models
are in the same universality class as an Ising spin glass in a magnetic field.
However, slightly in the non-mean-field region, we find an apparent transition
in the 3-spin model, in contrast to results for the Ising spin glass in a
field. This may indicate that even larger sizes are needed to probe the
asymptotic behavior in this region.Comment: 8 pages, 9 figures, 1 tabl
Study of the de Almeida-Thouless line using power-law diluted one-dimensional Ising spin glasses
We test for the existence of a spin-glass phase transition, the de
Almeida-Thouless line, in an externally-applied (random) magnetic field by
performing Monte Carlo simulations on a power-law diluted one-dimensional Ising
spin glass for very large system sizes. We find that an Almeida-Thouless line
only occurs in the mean field regime, which corresponds, for a short-range spin
glass, to dimension d larger than 6.Comment: 4 pages, 2 figures, 1 tabl
Finite-size critical scaling in Ising spin glasses in the mean-field regime
We study in Ising spin glasses the finite-size effects near the spin-glass
transition in zero field and at the de Almeida-Thouless transition in a field
by Monte Carlo methods and by analytical approximations. In zero field, the
finite-size scaling function associated with the spin-glass susceptibility of
the Sherrington-Kirkpatrick mean-field spin-glass model is of the same form as
that of one-dimensional spin-glass models with power-law long-range
interactions in the regime where they can be a proxy for the Edwards-Anderson
short-range spin-glass model above the upper critical dimension. We also
calculate a simple analytical approximation for the spin-glass susceptibility
crossover function. The behavior of the spin-glass susceptibility near the de
Almeida-Thouless transition line has also been studied, but here we have only
been able to obtain analytically its behavior in the asymptotic limit above and
below the transition. We have also simulated the one-dimensional system in a
field in the non-mean-field regime to illustrate that when the Imry-Ma droplet
length scale exceeds the system size one can then be erroneously lead to
conclude that there is a de Almeida-Thouless transition even though it is
absent.Comment: 10 pages, 7 figure
Microvesicles and exosomes: new players in metabolic and cardiovascular disease
The past decade has witnessed an exponential increase in the number of publications referring to extracellular vesicles (EVs). For many years considered to be extracellular debris, EVs are now seen as novel mediators of endocrine signalling via cell-to-cell communication. With the capability of transferring proteins and nucleic acids from one cell to another, they have become an attractive focus of research for different pathological settings and are now regarded as both mediators and biomarkers of disease including cardio-metabolic disease. They also offer therapeutic potential as signalling agents capable of targeting tissues or cells with specific peptides or miRNAs. In this review, we focus on the role that microvesicles (MVs) and exosomes, the two most studied classes of EV, have in diabetes, cardiovascular disease, endothelial dysfunction, coagulopathies, and polycystic ovary syndrome. We also provide an overview of current developments in MV/exosome isolation techniques from plasma and other fluids, comparing different available commercial and non-commercial methods. We describe different techniques for their optical/biochemical characterization and quantitation. We also review the signalling pathways that exosomes and MVs activate in target cells and provide some insight into their use as biomarkers or potential therapeutic agents. In summary, we give an updated focus on the role that these exciting novel nanoparticles offer for the endocrine community
A case report of adrenocorticotropic hormone to treat recurrent focal segmental glomerular sclerosis post-transplantation and biomarker monitoring
Background: Recurrent focal segmental glomerular sclerosis (rFSGS) in renal transplant recipients (RTR) is difficult to predict and treat. Early rFSGS is likely from circulating factors and preformed antibodies. Methods: We present the case of a 23-year-old white man who presented with rFSGS and acute renal failure requiring dialysis 9-months after a 1-haplotype matched living-related transplant. We retrospectively analyzed serum samples from various clinical stages for rFSGS biomarkers: serum glomerular albumin permeability (Palb), soluble urokinase-type plasminogen activator receptor (suPAR) serum level with suPAR-β3 integrin signaling on human podocytes, and angiotensin II type I receptor-antibody (AT1R-Ab) titer. Results: All biomarkers were abnormal at 1-year pre-transplant prior to initiation of dialysis and at the time of transplant. After initiation of hemodialysis, β3 integrin activity on human podocytes, in response to patient serum, as well as AT1R-Ab were further elevated. At the time of biopsy-proven recurrence, all biomarkers were abnormally high. One week after therapy with aborted plasmapheresis (secondary to intolerance), and high dose steroids, the Palb and suPAR- β3 integrin activity remained significantly positive. After 12-weeks of treatment with high-dose steroids, rituximab, and galactose, the patient remained hemodialysis-dependent. Three-months after his initial presentation we commenced adrenocorticotropic hormone (ACTH, Acthar® Gel), 80 units subcutaneously twice weekly. Four-weeks later he was able to discontinue dialysis. After 8-months of maintenance ACTH therapy, his serum creatinine stabilized at 1.79 mg/dL with less than 1 gram of proteinuria. Conclusion: ACTH therapy was associated with improvement in renal function within 4 weeks. The use of rFSGS biomarkers may aid in predicting development of rFSGS
Lame Ducks and the Antiquities Act: How (most) Presidents Use a 1906 Law to Ensure Their Environmental Legacies
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