Counting the negative eigenvalues of the thermalon in three dimensions

Some years ago it was shown that the cosmological constant may be reduced by thermal production of membranes that, after nucleation, collapse into a black hole. The probability of the process was calculated in the leading semiclassical approximation by studying an associated Euclidean configuration called the thermalon. Here we investigate the thermalon in three spacetime dimensions, describing the nucleation of closed strings that collapse into point particle singularities. In this context we may analyze the one-loop structure without the well known problems brought in by the propagating gravitational degrees of freedom. We found that the coupling to gravity may increase the number of negative eigenvalues of the operator

Microtensile bond strength of adhesive layer contaminated with blood on human sound enamel

Indexación: Web of Science; Scielo.Objetivo: Evaluar la influencia de la contaminación con sangre en una capa de adhesivo formada sobre esmalte humano y su posterior descontaminación con NaOCl (2.5%) y etanol (70°) en la resistencia microtraccional. Métodos: La superficie vestibular de 80 premolares humanos fue fresada para obtener superficies planas sobre las que se aplicó un adhesivo de grabado y lavado siguiendo las indicaciones del fabricante (Adper Single Bond 2, 3M ESPE). Los premolares fueron distribuidos aleatoriamente en cuatro grupos: Grupo 1 (control), Grupo 2 (contaminación con sangre), Grupo 3 (descontaminación con NaOCl 2.5%) y Grupo 4 (descontaminación con etanol 70°). Luego, sobre cada premolar se confeccionó una corona de resina compuesta (Filtek Z350, 3M ESPE) y fueron cortados para obtener cuerpos de prueba de 1mm2 de sección transversal, los cuales fueron termociclados (5500 ciclos, 5-55°C) y traccionados hasta su límite de ruptura (Micro Tensile Tester, Bisco). Los resultados fueron analizados estadísticamente (ANOVA, Scheffe, p0.05). Conclusión: La contaminación con sangre de la capa de adhesivo interfiere significativamente en la resistencia microtraccional. La descontaminación con NaOCl o etanol no logró una recuperación de la resistencia microtraccional.Aim: To evaluate the influence of blood contamination of the adhesive layer and posterior decontamination with NaOCl (2.5%) and ethanol (70º) on microtensile bond strength on human enamel. Methods: Vestibular surfaces of eighty human premolars were grounded to obtain flat surfaces. An etch-and-rinse adhesive was applied according to the manufacturer’s instructions (Adper Single bond 2, 3M ESPE). Teeth were randomly assigned into 4 groups: Group 1 (control), Group 2 (blood contamination), Group 3 (decontamination with NaOCl 2.5%) and Group 4 (decontamination with ethanol 70º). Then, a 4mm composite crown (Filtek Z350) was made and the teeth were vertically sectioned to obtain 1mm cross-section stick shape specimens. Specimens were thermocycled (5500 cycles, 5-55ºC) and pulled under tension until failure (Micro Tensile Tester, Bisco). Results were statistically analyzed (ANOVA, Scheffe’s test, p0.05). Conclusion: Blood contamination significantly interferes in microtensile bond strength. Decontaminating the blood residues with NaOCl or ethanol did not show a recovery of bond strength.http://ref.scielo.org/3zrh4

Multivoicedness as a tool for expanding school leaders’ understandings and practices for school-based professional development

This article presents findings from the implementation of a pilot study of a professional development model, Schools Inquiring and Learning with Peers (SILP) in Chile. SILP includes a network learning setting involving a cluster of three schools supported by university partners that conduct peer reviews and a school learning setting involving school teams in conversations to mobilise new leadership for learning practices. The notions of joint practice development and multivoicedness in professional conversations are the essence of these processes. Data produced through the review process, understood as voices, enabled participants to incorporate the perspectives, conceptual horizon, and intentions of administrators, students, and teachers who need to collaborate for teaching to produce learning. Across schools we observed common learning as well as important differences. These differences show that by taking an active role in making sense of their participation in a professional development programme, learners achieve outcomes that may be much more meaningful than what program designers prescribed. As facilitators we learned with participants about their specific contexts, expanding the affordances they and we envisioned for the use of new tools that became available through their participation in SILP

A note on a gauge-gravity relation and functional determinants

We present a refinement of a recently found gauge-gravity relation between one-loop effective actions: on the gauge side, for a massive charged scalar in 2d dimensions in a constant maximally symmetric electromagnetic field; on the gravity side, for a massive spinor in d-dimensional (Euclidean) anti-de Sitter space. The inclusion of the dimensionally regularized volume of AdS leads to complete mapping within dimensional regularization. In even-dimensional AdS, we get a small correction to the original proposal; whereas in odd-dimensional AdS, the mapping is totally new and subtle, with the `holographic trace anomaly' playing a crucial role.Comment: 6 pages, io

Corrosion behavior of a β CuAlBe shape memory alloy containing stress induced martensite

The corrosion behavior of a β CuAlBe shape memory alloy containing stress-induced martensite was analyzed after 60 days of immersion in a 3.5% NaCl solution. The stress-induced martensite was retained in the sample after a load-unload compression cycle up to a pseudoelastic deformation of 4.5%. The corrosion of the alloy occurs by dealuminization, where β phase located in the areas between the needles of martensite is dissolved due to the preferential loss of aluminum, and the posterior redeposition of copper takes place.Fil: Montecinos, S.. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física de Materiales; ArgentinaFil: Klímek, P.. No especifíca;Fil: Sláma, M.. No especifíca;Fil: Suarez, S.. Universitat Saarland; AlemaniaFil: Simison, Silvia Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

The impact of Charlson comorbidity index on the functional capacity of COVID-19 survivors: a prospective cohort study with one-year follow-up

Objective: To determine the association between the Charlson comorbidity index (CCI) score after discharge with 6-min walk test (6MWT) 1 year after discharge in a cohort of COVID-19 survivors. Methods: In this prospective study, data were collected from a consecutive sample of patients hospitalized for COVID-19. The CCI score was calculated from the comorbidity data. The main outcome was the distance walked in the 6MWT at 1 year after discharge. Associations between CCI and meters covered in the 6MWT were assessed through crude and adjusted linear regressions. The model was adjusted for possible confounding factors (sex, days of hospitalization, and basal physical capacity through sit-to-stand test one month after discharge). Results: A total of 41 patients were included (mean age 58.8 +/- 12.7 years, 20/21 men/women). A significant association was observed between CCI and 6MWT (meters): (i) crude model: beta = -18.7, 95% CI = -34.7 to -2.6, p < 0.05; (ii) model adjusted for propensity score including sex, days of hospitalization, and sit-to-stand: beta = -23.0, 95% CI = -39.1 to -6.8, p < 0.05. Conclusions: A higher CCI score after discharge indicates worse performance on the 6MWT at 1-year follow-up in COVID-19 survivors. The CCI score could also be used as a screening tool to make important clinical decisions

Protective effect of stromal Dickkopf-3 in prostate cancer: opposing roles for TGFBI and ECM-1

Aberrant transforming growth factor–β (TGF-β) signaling is a hallmark of the stromal microenvironment in cancer. Dickkopf-3 (Dkk-3), shown to inhibit TGF-β signaling, is downregulated in prostate cancer and upregulated in the stroma in benign prostatic hyperplasia, but the function of stromal Dkk-3 is unclear. Here we show that DKK3 silencing in WPMY-1 prostate stromal cells increases TGF-β signaling activity and that stromal cellconditioned media inhibit prostate cancer cell invasion in a Dkk-3-dependent manner. DKK3 silencing increased the level of the cell-adhesion regulator TGF-β–induced protein (TGFBI) in stromal and epithelial cell-conditioned media, and recombinant TGFBI increased prostate cancer cell invasion. Reduced expression of Dkk-3 in patient tumors was associated with increased expression of TGFBI. DKK3 silencing reduced the level of extracellular matrix protein-1 (ECM-1) in prostate stromal cell-conditioned media but increased it in epithelial cell-conditioned media, and recombinant ECM-1 inhibited TGFBI-induced prostate cancer cell invasion. Increased ECM1 and DKK3 mRNA expression in prostate tumors was associated with increased relapse-free survival. These observations are consistent with a model in which the loss of Dkk-3 in prostate cancer leads to increased secretion of TGFBI and ECM-1, which have tumor-promoting and tumor-protective roles, respectively. Determining how the balance between the opposing roles of extracellular factors influences prostate carcinogenesis will be key to developing therapies that target the tumor microenvironment

Logarithmic correction to BH entropy as Noether charge

We consider the role of the type-A trace anomaly in static black hole solutions to semiclassical Einstein equation in four dimensions. Via Wald's Noether charge formalism, we compute the contribution to the entropy coming from the anomaly induced effective action and unveil a logarithmic correction to the Bekenstein-Hawking area law. The corrected entropy is given by a seemingly universal formula involving the coefficient of the type-A trace anomaly, the Euler characteristic of the horizon and the value at the horizon of the solution to the uniformization problem for Q-curvature. Two instances are examined in detail: Schwarzschild and a four-dimensional massless topological black hole. We also find agreement with the logarithmic correction due to one-loop contribution of conformal fields in the Schwarzschild background.Comment: 14 pages, JHEP styl