8,299 research outputs found
A Formal Model for Trust in Dynamic Networks
We propose a formal model of trust informed by the Global Computing scenario and focusing on the aspects of trust formation, evolution, and propagation. The model is based on a novel notion of trust structures which, building on concepts from trust management and domain theory, feature at the same time a trust and an information partial order
Alignment transition in a nematic liquid crystal due to field-induced breaking of anchoring
We report on the alignment transition of a nematic liquid crystal from
initially homeotropic to quasi-planar due to field-induced anchoring breaking.
The initial homeotropic alignment is achieved by Langmuir-Blodgett monolayers.
In this geometry the anchoring strength can be evaluated by the Frederiks
transition technique. Applying an electric field above a certain threshold
provokes turbulent states denoted DSM1 and DSM2. While DSM1 does not affect the
anchoring, DSM2 breaks the coupling between the surface and the liquid crystal:
switching off the field from a DSM2 state does not immediately restore the
homeotropic alignment. Instead, we obtain a quasi-planar metastable alignment.
The cell thickness dependence for the transition is related to theComment: 7 pages, LaTeX2e article, 4 figures, 7 EPS files, added references,
accepted for publication in Europhysics Letter
A Calculus of Trust Management
We discuss a formal model for trust in Global Computing scenarios, focusing on the aspects of trust formation, evolution, and propagation. We focus on a particular abstract model, and illustrate its applicability on a simple example. We also discuss a possible operational model for trust based systems
Early amniotomy after cervical ripening for induction of labor: a systematic review and meta-analysis of randomized controlled trials
OBJECTIVE DATA:
Timing of artificial rupture of membranes (ie, amniotomy) in induction of labor is controversial, because it has been associated not only with shorter labors, but also with fetal nonreassuring testing, at times necessitating cesarean delivery. The aim of this systematic review and metaanalysis of randomized trials was to evaluate the effectiveness of early amniotomy vs late amniotomy or spontaneous rupture of membranes after cervical ripening.
STUDY:
The search was conducted with the use of electronic databases from inception of each database through February 2019. Review of articles included the abstracts of all references that were retrieved from the search.
STUDY APPRAISAL AND SYNTHESIS METHODS:
Selection criteria included randomized clinical trials that compared early amniotomy vs control (ie, late amniotomy or spontaneous rupture of membranes) after cervical ripening with either Foley catheter or prostaglandins at any dose. The primary outcome was the incidence of cesarean delivery. The summary measures were reported as summary relative risk with 95% of confidence interval with the use of the random effects model of DerSimonian and Laird.
RESULTS:
Four trials that included 1273 women who underwent cervical ripening with either Foley catheter or prostaglandins and then were assigned randomly to either early amniotomy, late amniotomy, or spontaneous rupture of membranes (control subjects) were included in the review. Women who were assigned randomly to early amniotomy had a similar risk of cesarean delivery (31.1% vs 30.9%; relative risk, 1.05; 95% confidence interval, 0.71-1.56) compared with control subjects and had a shorter interval from induction to delivery of approximately 5 hours (mean difference, -4.95 hours; 95% confidence interval, -8.12 to -1.78). Spontaneous vaginal delivery was also reduced in the early amniotomy group, but only 1 of the included trials reported this outcome (67.5% vs 69.1%; relative risk, 0.78; 95% confidence interval, 0.66-0.93). No between-group differences were reported in the other obstetrics or perinatal outcomes.
CONCLUSION:
After cervical ripening, routine early amniotomy does not increase the risk of cesarean delivery and reduces the interval from induction to delivery
Multiple Interactions between Peroxisome Proliferators-Activated Receptors and the Ubiquitin-Proteasome System and Implications for Cancer Pathogenesis
The peroxisome proliferator-activated receptors (PPAR) α, β/δ, and γ are ligand-activated nuclear receptors involved in a number of physiological processes, including lipid and glucose homeostasis, inflammation, cell growth, differentiation, and death. PPAR agonists are used in the treatment of human diseases, like type 2 diabetes and dyslipidemia, and PPARs appear as promising therapeutic targets in other conditions, including cancer. A better understanding of the functions and regulation of PPARs in normal and pathological processes is of primary importance to devise appropriate therapeutic strategies. The ubiquitin-proteasome system (UPS) plays an important role in controlling level and activity of many nuclear receptors and transcription factors. PPARs are subjected to UPS-dependent regulation. Interestingly, the three PPAR isotypes are differentially regulated by the UPS in response to ligand-dependent activation, a phenomenon that may be intrinsically connected to their distinct cellular functions and behaviors. In addition to their effects ongene expression, PPARs appear to affect protein levels and downstream pathways also by modulating the activity of the UPS in target-specific manners. Here we review the current knowledge of the interactions between the UPS and PPARs in light of the potential implications for their effects on cell fate and tumorigenesis
Photon correlations for colloidal nanocrystals and their clusters
Images of semiconductor `dot in rods' and their small clusters are studied by
measuring the second-order correlation function with a spatially resolving ICCD
camera. This measurement allows one to distinguish between a single dot and a
cluster and, to a certain extent, to estimate the number of dots in a cluster.
A more advanced measurement is proposed, based on higher-order correlations,
enabling more accurate determination of the number of dots in a small cluster.
Nonclassical features of the light emitted by such a cluster are analyzed.Comment: 4 pages, 4 figure
Exact Results for the Roughness of a Finite Size Random Walk
We consider the role of finite size effects on the value of the effective
Hurst exponent H. This problem is motivated by the properties of the high
frequency daily stock-prices. For a finite size random walk we derive some
exact results based on Spitzer's identity. The conclusion is that finite size
effects strongly enhance the value of H and the convergency to the asymptotic
value (H=1/2) is rather slow. This result has a series of conceptual and
practical implication which we discuss.Comment: 5 pages, 3 figure
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