130 research outputs found
Resonance Spectra of Caged Stringy Black Hole and Its Spectroscopy
The Maggiore's method (MM), which evaluates the transition frequency that
appears in the adiabatic invariant from the highly damped quasinormal mode
(QNM) frequencies, is used to investigate the entropy/area spectra of the
Garfinkle--Horowitz--Strominger black hole (GHSBH). Instead of the ordinary
QNMs, we compute the boxed QNMs (BQNMs) that are the characteristic resonance
spectra of the confined scalar fields in the GHSBH geometry. For this purpose,
we assume that the GHSBH has a confining cavity (mirror) placed in the vicinity
of the event horizon. We then show how the complex resonant frequencies of the
caged GHSBH are computed using the Bessel differential equation that arises
when the scalar perturbations around the event horizon are considered. Although
the entropy/area is characterized by the GHSBH parameters, their quantization
is shown to be independent of those parameters. However, both spectra are
equally spaced.Comment: New References have been added. Thanks to Prof. Carlos A. R. Herdeir
Spectroscopy of Lifshitz Black Hole
We studied the thermodynamics and spectroscopy of a -dimensional,
Lifshitz black hole (LBH). Using the Wald's entropy formula and the Hawking
temperature, we derived the quasilocal mass of the LBH. Based on the exact
solution to the near-horizon Zerilli equation of the massive scalar waves, we
computed the quasinormal modes of the LBH via employing the adiabatic
invariant quantity for the LBH. This study shows that the entropy and area
spectra of the LBH are equally spaced.Comment: 9 pages, 1 figur
Photonics and fracture toughness of heterogeneous composite materials
Fracture toughness measures the resistance of a material to fracture. This fundamental property is used in diverse engineering designs including mechanical, civil, materials, electronics and chemical engineering applications. In spite of the advancements made in the past 40 years, the evaluation of this remains challenging for extremely heterogeneous materials such as composite concretes. By taking advantage of the optical properties of a thin birefringent coating on the surface of opaque, notched composite concrete beams, here we sense the evolution of the maximum shear stress distribution on the beams under loading. The location of the maximum deviator stress is tracked ahead of the crack tip on the experimental concrete samples under the ultimate load, and hence the effective crack length is characterised. Using this, the fracture toughness of a number of heterogeneous composite beams is evaluated and the results compare favourably well with other conventional methods using combined experimental and numerical/analytical approaches. Finally a new model, correlating the optically measured shear stress concentration factor and flexural strength with the fracture toughness of concretes is proposed. The current photonics-based study could be vital in evaluating the fracture toughness of even opaque and complex heterogeneous materials more effectively in future
Efficacy of AZM therapy in patients with gingival overgrowth induced by Cyclosporine A: a systematic review
<p>Abstract</p> <p>Background</p> <p>In daily clinical practice of a dental department it's common to find gingival overgrowth (GO) in periodontal patients under treatment with Cyclosporine A (CsA). The pathogenesis of GO and the mechanism of action of Azithromycin (AZM) are unclear. A systematic review was conducted in order to evaluate the efficacy of Azithromycin in patients with gingival overgrowth induced by assumption of Cyclosporine A.</p> <p>Methods</p> <p>A bibliographic search was performed using the online databases MEDLINE, EMBASE and Cochrane Central of Register Controlled Trials (CENTRAL) in the time period between 1966 and September 2008.</p> <p>Results</p> <p>The literature search retrieved 24 articles; only 5 were Randomised Controlled Trials (RCTs), published in English, fulfilled the inclusion criteria. A great heterogeneity between proposed treatments and outcomes was found, and this did not allow to conduct a quantitative meta-analysis. The systematic review revealed that a 5-day course of Azithromycin with Scaling and Root Planing reduces the degree of gingival overgrowth, while a 7-day course of metronidazole is only effective on concomitant bacterial over-infection.</p> <p>Conclusion</p> <p>Few RCTs on the efficacy of systemic antibiotic therapy in case of GO were found in the literature review. A systemic antibiotic therapy without plaque and calculus removal is not able to reduce gingival overgrowth. The great heterogeneity of diagnostic data and outcomes is due to the lack of precise diagnostic methods and protocols about GO. Future studies need to improve both diagnostic methods and tools and adequate classification aimed to determine a correct prognosis and an appropriate therapy for gingival overgrowth.</p
Comprehensive analysis via exome sequencing uncovers genetic etiology in autosomal recessive nonsyndromic deafness in a large multiethnic cohort
Purpose:Autosomal recessive nonsyndromic deafness (ARNSD) is characterized by a high degree of genetic heterogeneity, with reported mutations in 58 different genes. This study was designed to detect deafness-causing variants in a multiethnic cohort with ARNSD by using whole-exome sequencing (WES).Methods:After excluding mutations in the most common gene, GJB2, we performed WES in 160 multiplex families with ARNSD from Turkey, Iran, Mexico, Ecuador, and Puerto Rico to screen for mutations in all known ARNSD genes.Results:We detected ARNSD-causing variants in 90 (56) families, 54 of which had not been previously reported. Identified mutations were located in 31 known ARNSD genes. The most common genes with mutations were MYO15A (13), MYO7A (11), SLC26A4 (10), TMPRSS3 (9), TMC1 (8), ILDR1 (6), and CDH23 (4). Nine mutations were detected in multiple families with shared haplotypes, suggesting founder effects.Conclusion:We report on a large multiethnic cohort with ARNSD in which comprehensive analysis of all known ARNSD genes identifies causative DNA variants in 56 of the families. In the remaining families, WES allows us to search for causative variants in novel genes, thus improving our ability to explain the underlying etiology in more families.Genet Med 18 4, 364-371. © American College of Medical Genetics and Genomics
Diagnostic accuracy of a clinical diagnosis of idiopathic pulmonary fibrosis: An international case-cohort study
We conducted an international study of idiopathic pulmonary fibrosis (IPF) diagnosis among a large group of physicians and compared their diagnostic performance to a panel of IPF experts. A total of 1141 respiratory physicians and 34 IPF experts participated. Participants evaluated 60 cases of interstitial lung disease (ILD) without interdisciplinary consultation. Diagnostic agreement was measured using the weighted kappa coefficient (\u3baw). Prognostic discrimination between IPF and other ILDs was used to validate diagnostic accuracy for first-choice diagnoses of IPF and were compared using the Cindex. A total of 404 physicians completed the study. Agreement for IPF diagnosis was higher among expert physicians (\u3baw=0.65, IQR 0.53-0.72, p20 years of experience (C-index=0.72, IQR 0.0-0.73, p=0.229) and non-university hospital physicians with more than 20 years of experience, attending weekly MDT meetings (C-index=0.72, IQR 0.70-0.72, p=0.052), did not differ significantly (p=0.229 and p=0.052 respectively) from the expert panel (C-index=0.74 IQR 0.72-0.75). Experienced respiratory physicians at university-based institutions diagnose IPF with similar prognostic accuracy to IPF experts. Regular MDT meeting attendance improves the prognostic accuracy of experienced non-university practitioners to levels achieved by IPF experts
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