Random billiards with wall temperature and associated Markov chains

By a random billiard we mean a billiard system in which the standard specular reflection rule is replaced with a Markov transition probabilities operator P that, at each collision of the billiard particle with the boundary of the billiard domain, gives the probability distribution of the post-collision velocity for a given pre-collision velocity. A random billiard with microstructure (RBM) is a random billiard for which P is derived from a choice of geometric/mechanical structure on the boundary of the billiard domain. RBMs provide simple and explicit mechanical models of particle-surface interaction that can incorporate thermal effects and permit a detailed study of thermostatic action from the perspective of the standard theory of Markov chains on general state spaces. We focus on the operator P itself and how it relates to the mechanical/geometric features of the microstructure, such as mass ratios, curvatures, and potentials. The main results are as follows: (1) we characterize the stationary probabilities (equilibrium states) of P and show how standard equilibrium distributions studied in classical statistical mechanics, such as the Maxwell-Boltzmann distribution and the Knudsen cosine law, arise naturally as generalized invariant billiard measures; (2) we obtain some basic functional theoretic properties of P. Under very general conditions, we show that P is a self-adjoint operator of norm 1 on an appropriate Hilbert space. In a simple but illustrative example, we show that P is a compact (Hilbert-Schmidt) operator. This leads to the issue of relating the spectrum of eigenvalues of P to the features of the microstructure;(3) we explore the latter issue both analytically and numerically in a few representative examples;(4) we present a general algorithm for simulating these Markov chains based on a geometric description of the invariant volumes of classical statistical mechanics

Revised structural phase diagram of (Ba0.7Ca0.3TiO3)-(BaZr0.2Ti0.8O3)

The temperature-composition phase diagram of barium calcium titanate zirconate (x(Ba0.7Ca0.3TiO3)(1-x)(BaZr0.2Ti0.8O3); BCTZ) has been reinvestigated using high-resolution synchrotron x-ray powder diffraction. Contrary to previous reports of an unusual rhombohedral-tetragonal phase transition in this system, we have observed an intermediate orthorhombic phase, isostructural to that present in the parent phase, BaTiO3, and we identify the previously assigned T-R transition as a T-O transition. We also observe the O-R transition coalescing with the previously observed triple point, forming a phase convergence region. The implication of the orthorhombic phase in reconciling the exceptional piezoelectric properties with the surrounding phase diagram is discussed

Immune Response to Cytolethal Distending Toxin of Aggregatibacter Actinomycetemcomitans in Periodontitis Patients

Background and Objective Cytolethal distending toxin (CDT) is a genotoxin produced by Aggregatibacter actinomycetemcomitans. In spite of its association with pathogenesis, little is known about the humoral immune response against the CDT. This study aimed to test whether subgingival colonization and humoral response to A. actinomycetemcomitans would lead to a response against CDT. Material and Methods Sera from periodontally healthy, localized and generalized aggressive periodontitis and chronic periodontitis subjects (n = 80) were assessed for immunoglobulin G titers to A. actinomycetemcomitans serotypes a/b/c and to each CDT subunit (CdtA, CdtB and CdtC) by ELISA. A. actinomycetemcomitans subgingival levels and neutralization of CDT activity were also analyzed. Results Sera from 75.0% localized and 81.8% generalized aggressive periodontitis patients reacted to A. actinomycetemcomitans. A response to serotype b was detected in localized (66.7%) and generalized aggressive periodontitis (54.5%). Reactivity to A. actinomycetemcomitans correlated with subgingival colonization (R = 0.75, p \u3c 0.05). There was no correlation between A. actinomycetemcomitans colonization or response to serotypes and the immunoglobulin G response to CDT subunits. Titers of immunoglobulin G to CdtA and CdtB did not differ among groups; however, sera of all generalized aggressive periodontitis patients reacted to CdtC. Neutralization of CDT was not correlated with levels of antibodies to CDT subunits. Conclusion Response to CdtA and CdtB did not correlate with the periodontal status of the subject in the context of an A. actinomycetemcomitans infection. However, a response to CdtC was found in sera of generalized but not of localized aggressive periodontitis subjects. Differences in response to CdtC between generalized and localized aggressive periodontitis subjects indicate that CDT could be expressed differently by the infecting strains. Alternatively, the antibody response to CdtC could require the colonization of multiple sites

Impact of Side Branch Predilation on Percutaneous Coronary Intervention in Complex Coronary Bifurcation Lesions

ABSTRACTBackgroundThe treatment of coronary bifurcation lesions with single stenting in the main vessel and provisional side branch stenting may be limited by the degree of anatomical/morphological complexity. Side branch predilation, a procedural step that is typically avoided, may be required to maintain side branch patency. The impact of side branch predilation on the immediate results of percutaneous coronary intervention in complex coronary bifurcation lesions was investigated.MethodsBetween May, 2008 and August, 2009, 59 patients with single coronary bifurcation lesions and significant involvement of the main and side branches were included in the study. The main exclusion criteria were the involvement of the left main coronary artery, ST-elevation acute myocardial infarction (< 72 hours) and in-stent restenosis.ResultsThe mean age of patients was 61.2±11 years, 25.4% were female, and 30.1% had diabetes mellitus. Lesions were most prevalent in the left anterior descending artery/diagonal branch (86.4%). During the procedure, 8.5% (5/59) of lesions had unsuccessful side branch predilation, and four of these bifurcations were treated with two stents. In the multivariate model, side branch stenosis at baseline was the only significant predictor of unsuccessful side branch predilation (odds ratio 1.15, 95%CI: 1.01–1.30; P=0.04), and side branch stenosis > 87.6% was identified as the most accurate cut-off value to predict failure in the receiver operating characteristic (ROC) curve.ConclusionsSide branch predilation was associated with immediate side branch failure in < 10% of cases, and the only significant predictor in the multivariate model was side branch stenosis severity (> 85%) at baseline

Rationing tests for drug-resistant tuberculosis - who are we prepared to miss?

BACKGROUND: Early identification of patients with drug-resistant tuberculosis (DR-TB) increases the likelihood of treatment success and interrupts transmission. Resource-constrained settings use risk profiling to ration the use of drug susceptibility testing (DST). Nevertheless, no studies have yet quantified how many patients with DR-TB this strategy will miss. METHODS: A total of 1,545 subjects, who presented to Lima health centres with possible TB symptoms, completed a clinic-epidemiological questionnaire and provided sputum samples for TB culture and DST. The proportion of drug resistance in this population was calculated and the data was analysed to demonstrate the effect of rationing tests to patients with multidrug-resistant TB (MDR-TB) risk factors on the number of tests needed and corresponding proportion of missed patients with DR-TB. RESULTS: Overall, 147/1,545 (9.5%) subjects had culture-positive TB, of which 32 (21.8%) had DR-TB (MDR, 13.6%; isoniazid mono-resistant, 7.5%; rifampicin mono-resistant, 0.7%). A total of 553 subjects (35.8%) reported one or more MDR-TB risk factors; of these, 506 (91.5%; 95% CI, 88.9-93.7%) did not have TB, 32/553 (5.8%; 95% CI, 3.4-8.1%) had drug-susceptible TB, and only 15/553 (2.7%; 95% CI, 1.5-4.4%) had DR-TB. Rationing DST to those with an MDR-TB risk factor would have missed more than half of the DR-TB population (17/32, 53.2%; 95% CI, 34.7-70.9). CONCLUSIONS: Rationing DST based on known MDR-TB risk factors misses an unacceptable proportion of patients with drug-resistance in settings with ongoing DR-TB transmission. Investment in diagnostic services to allow universal DST for people with presumptive TB should be a high priority

Pregnancy losses after transfer of bovine embryos produced by assisted reproductive technologies.

Edição dos resumos da Annual Conference of the International Embryo Technology Society, New Orleans, Louisiana, 2019

Vascular response after implantation of biolimus A9-eluting stent with bioabsorbable polymer and everolimus-eluting stents with durable polymer. Results of the optical coherence tomography analysis of the BIOACTIVE randomized trial

AbstractBackgroundIn BIOACTIVE study, we evaluated vascular responses after the implant of biolimus A9-eluting stent (BES; BioMatrixTM) and the everolimus-eluting stent (EES; XIENCE VTM). In this study, we present the optical coherence tomography analysis (OCT) 6 months post-intervention.MethodsPatients were randomized to treatment with BES (n = 22) or EES (n = 18). The primary outcome was the frequency of non-covered, poorly positioned struts by OCT.ResultsOCT was performed in 26 patients (BES: n = 15; EES: n = 11) and 749 tomographic images and 7,725 stent struts were analyzed. BES and EES showed similar luminal and stent areas. Neointimal hyperplasia area, neointimal thickness and the percentage of in-stent obstruction (8.44 ± 5.10% vs. 9.21 ± 6.36%; p = 0.74) were similar. The rates of not covered struts (BES: 2.10 ± 3.60% vs. ESS: 2.46 ± 2.15%, p = 0.77) and poorly positioned struts (BES: 0.48 ± 1.48% vs. EES 0.44 ± 1.05%, p = 0.94) were similarly low. The frequency of frames with signs consistent with peri-strut inflammatory infiltrate was low and similar between BES (15.53 ± 20.77%) and EES (11.70 ± 27.51%; p = 0.68).ConclusionsThe second-generation drug-eluting stents BES and EES were equally effective at suppressing the neointimal formation after 6 months, with favorable vascular responses. The frequency of frames with peri-strut infiltrate signals per patient was low, and lower than that observed historically with first-generation drug-eluting stents