Dye lasing in optically manipulated liquid aerosols

We report lasing in airborne, rhodamine B-doped glycerol-water droplets with diameters ranging between 7.7 and 11.0 mu m, which were localized using optical tweezers. While being trapped near the focal point of an infrared laser, the droplets were pumped with a Q-switched green laser. Our experiments revealed nonlinear dependence of the intensity of the droplet whispering gallery modes (WGMs) on the pump laser fluence, indicating dye lasing. The average wavelength of the lasing WGMs could be tuned between 600 and 630 nm by changing the droplet size. These results may lead to new ways of probing airborne particles, exploiting the high sensitivity of stimulated emission to small perturbations in the droplet laser cavity and the gain medium

Numerical and experimental assessment of the modal curvature method for damage detection in plate structures

This paper is concerned with the use of numerically obtained modal curvatures for damage detection in both isotropic and composite laminated plates. Numerical simulations are carried out by using COMSOL Multiphysics as FEM solver of the governing equations, in which a Mindlin-Reissner plate model is assumed and defects are introduced as localized smoothed variations of the baseline (healthy) configuration. Experiments are also performed on steel and aluminum plates using scanning laser vibrometry. This study confirms that the central difference method greatly amplifies the measurement errors and its application leads to ineffective predictions for damage detection, even after denoising. As a consequence, different numerical techniques should be explored to allow the use of numerically obtained modal curvatures for structural health monitoring. Herein, the Savitzky-Golay filter (or least-square smoothing filter) is considered for the numerical differentiation of noisy data

Novel decay dynamics revealed for virus-mediated drug activation in cytomegalovirus infection

Human cytomegalovirus (CMV) infection is a substantial cause of morbidity and mortality in immunocompromised hosts and globally is one of the most important congenital infections. The nucleoside analogue ganciclovir (GCV), which requires initial phosphorylation by the viral UL97 kinase, is the mainstay for treatment. To date, CMV decay kinetics during GCV therapy have not been extensively investigated and its clinical implications not fully appreciated. We measured CMV DNA levels in the blood of 92 solid organ transplant recipients with CMV disease over the initial 21 days of ganciclovir therapy and identified four distinct decay patterns, including a new pattern exhibiting a transient viral rebound (Hump) following initial decline. Since current viral dynamics models were unable to account for this Hump profile, we developed a novel multi-level model, which includes the intracellular role of UL97 in the continued activation of ganciclovir, that successfully described all the decline patterns observed. Fitting the data allowed us to estimate ganciclovir effectiveness in vivo (mean 92%), infected cell half-life (mean 0.7 days), and other viral dynamics parameters that determine which of the four kinetic patterns will ensue. An important clinical implication of our results is that the virological efficacy of GCV operates over a broad dose range. The model also raises the possibility that GCV can drive replication to a new lower steady state but ultimately cannot fully eradicate it. This model is likely to be generalizable to other anti-CMV nucleoside analogs that require activation by viral enzymes such as UL97 or its homologues

Numerical and experimental assessment of the modal curvature method for damage detection in plate structures

Use of modal curvatures obtained from modal displacement data for damage detection in isotropic and composite laminated plates is addressed through numerical examples and experimental tests. Numerical simulations are carried out employing COMSOL Multiphysics as finite element solver of the equations governing the Mindlin-Reissner plate model. Damages are introduced as localized non-smooth variations of the bending stiffness of the baseline (healthy) configuration. Experiments are also performed on steel and aluminum plates using scanning laser vibrometry. The obtained results confirm that use of the central difference method to compute modal curvatures greatly amplifies the measurement errors and its application leads to unreliable predictions for damage detection, even after denoising. Therefore, specialized ad hoc numerical techniques must be suitably implemented to enable structural health monitoring via modal curvature changes. In this study, the Savitzky-Golay filter (also referred to as least-square smoothing filter) is considered for the numerical differentiation of noisy data. Numerical and experimental results show that this filter is effective for the reliable computation of modal curvature changes in plate structures due to defects and/or damages

Risk Factors for Frequent Readmissions and Barriers to Transplantation in Patients with Cirrhosis

Background: Hospital readmission rate is receiving increasing regulatory scrutiny. Patients with cirrhosis have high hospital readmissions rates but the relationship between frequent readmissions and barriers to transplantation remains unexplored. The goal of this study was to determine risk factors for frequent readmissions among patients with cirrhosis and identify barriers to transplantation in this population. Methods: We retrospectively reviewed medical records of 587 patients with a confirmed diagnosis of cirrhosis admitted to a large tertiary care center between May 1, 2008 and May 1, 2009. Demographics, clinical factors, and outcomes were recorded. Multivariate logistic regression was performed to identify risk factors for high readmission rates. Transplant-related factors were assessed for patients in the high readmission group. Results: The 587 patients included in the study had 1557 admissions during the study period. A subset of 87 (15%) patients with 5 or more admissions accounted for 672 (43%) admissions. The factors associated with frequent admissions were non-white race (OR = 2.45, p = 0.01), diabetes (OR = 2.04, p = 0.01), higher Model for End-Stage Liver Disease (MELD) score (OR = 35.10, p30) and younger age (OR = 0.98, p = 0.02). Among the 87 patients with ≥5 admissions, only 14 (16%) underwent liver transplantation during the study period. Substance abuse, medical co-morbidities, and low (<15) MELD scores were barriers to transplantation in this group. Conclusions: A small group of patients with cirrhosis account for a disproportionately high number of hospital admissions. Interventions targeting this high-risk group may decrease frequent hospital readmissions and increase access to transplantation. © 2013 Ganesh et al

Analysis of fracture mechanisms and surface quality in drilling of composite materials

The aim of this work is to clarify the interaction mechanisms between the drilling tool and material. Drilling tests were carried out on glass/polyester and carbon/epoxy composites using different twist drills. The cutting tools and machined surfaces were examined by optical microscopy, scanning microscopy and surface profilometry to study composite damage and tool wear. Among the defects caused by drilling, delamination appears to be the most critical and may occurs at both the entrance and exit planes. A prediction model of thrust force for drilling without delamination is proposed.Определены механизмы взаимодействия между сверлом и материалом. Испытания проводили на стеклонаполненном полиэфире и эпоксикарбопласте с использованием различных спиральных сверл. Режущий инструмент и обработанные поверхности изучали с помощью оптической микроскопии, сканирующей микроскопии и поверхностной профилометрии, чтобы выявить повреждение композиционного материала и износ инструмента. Среди дефектов, вызванных сверлением, наиболее серьезным является расслоение как на плоскостях входа, так и выхода. Предложена модель прогнозирования усилия подачи при сверлении без расслоения

Cluster architecture of old, neglected Croatian grapevine varieties (Vitis vinifera L.)

Grape cluster architecture is an important trait affecting fruit composition and yield. Damage caused by gray mold (Botrytis cinerea) is directly related to cluster density and some other environmental factors. The aim of this study was to quantify characteristics of fully mature clusters of eleven old Croatian grapevine varieties (Vitis vinifera L.) which so far have not been phenotypically described in detail, and to examine Botrytis cinerea disease severity on their grapes under field conditions. Eight variables that describe the appearance of clusters were quantified in three consecutive years including cluster weight, length, width, volume, compactness, rachis weight, number of berries and single berry weight. Two-factor analysis of variance provided estimates of varietal and annual differences. Significant differences among eleven old Croatian varieties for all cluster traits were determined. Results suggest diverse cluster morphology within the old Croatian varieties revealing three variety groups by PCA analysis and their varying degrees of sensitivity to Botrytis. These phenotypic data on cluster structure represent a basis for future research, such as QTL analysis or assessment of productivity of these varieties

Defect structures in nematic liquid crystals around charged particles

We numerically study the orientation deformations in nematic liquid crystals around charged particles. We set up a Ginzburg-Landau theory with inhomogeneous electric field. If the dielectric anisotropy varepsilon_1 is positive, Saturn ring defects are formed around the particles. For varepsilon_1<0, novel "ansa" defects appear, which are disclination lines with their ends on the particle surface. We find unique defect structures around two charged particles. To lower the free energy, oppositely charged particle pairs tend to be aligned in the parallel direction for varepsilon_1>0 and in the perpendicular plane for varepsilon_1<0 with respect to the background director . For identically charged pairs the preferred directions for varepsilon_1>0 and varepsilon_1<0 are exchanged. We also examie competition between the charge-induced anchoring and the short-range anchoring. If the short-range anchoring is sufficiently strong, it can be effective in the vicinity of the surface, while the director orientation is governed by the long-range electrostatic interaction far from the surface.Comment: 10 papes, 12 figures, to appear in European Physical Journal

Comparison of Response of Building Structures to Blast Loading and Seismic Excitations

Blast loading and earthquake excitations can be regarded as the most destructive events a building structure can experience during its life. Response of the structures to these two types of dynamic loading can be of comparable magnitude. Therefore, in this study, response of a benchmark 10-story building to moderate blast loading is compared to that produced by several different synthetic ground motions whose spectra are compatible with the uniform hazard spectra for selected sites in the eastern and western regions of Canada. The results show that the lateral story drifts produced by blast loading are significantly larger than the corresponding seismic drifts. The study concludes that consideration of the global response of a building to blast loads is important, and response parameters, such as the lateral drifts and floor responses, should be paid attention in the design and response assessment procedures for blast loading

Variable viral clearance despite adequate ganciclovir plasma levels during valganciclovir treatment for cytomegalovirus disease in D+/R- transplant recipients

ABSTRACT: BACKGROUND: Valganciclovir, the oral prodrug of ganciclovir, has been demonstrated equivalent to iv ganciclovir for CMV disease treatment in solid organ transplant recipients. Variability in ganciclovir exposure achieved with valganciclovir could be implicated as a contributing factor for explaining variations in the therapeutic response. This prospective observational study aimed to correlate clinical and cytomegalovirus (CMV) viral load response (DNAemia) with ganciclovir plasma concentrations in patients treated with valganciclovir for CMV infection/disease. METHODS: Seven CMV D+/R- transplant recipients (4 kidney, 2 liver and 1 heart) were treated with valganciclovir (initial dose was 900-1800 mg/day for 3-6.5 weeks, followed by 450-900 mg/day for 2-9 weeks). DNAemia was monitored by real time quantitative PCR and ganciclovir plasma concentration was measured at trough (Ctrough) and 3 h after drug administration (C3h) by HPLC. RESULTS: Four patients presented with CMV syndrome, two had CMV tissue-invasive disease after prophylaxis discontinuation, and one liver recipient was treated pre-emptively for asymptomatic rising CMV viral load 5 weeks post-transplantation in the absence of prophylaxis. CMV DNAemia decreased during the first week of treatment in all recipients except in one patient (median decrease: -1.2 log copies/mL, range: -1.8 to 0) despite satisfactory ganciclovir exposure (AUC0-12 = 48 mg.h/L, range for the 7 patients: 40-118 mg.h/L). Viral clearance was obtained in five patients after a median of time of 34 days (range: 28-82 days). Two patients had recurrent CMV disease despite adequate ganciclovir exposure (65 mg.h/L, range: 44-118 mg.h/L). CONCLUSIONS: Valganciclovir treatment for CMV infection/disease in D+/R- transplant recipients can thus result in variable viral clearance despite adequate ganciclovir plasma concentrations, probably correlating inversely with anti-CMV immune responses after primary infection