Macrocrystals of Colloidal Quantum Dots in Anthrancene: Exciton Trannsfer and Polarized Emission

Cataloged from PDF version of article.In this work, centimeter-scale macrocrystals of nonpolar colloidal quantum dots (QDs) incorporated into anthracene were grown for the first time. The exciton transfer from the anthracene host to acceptor QDs was systematically investigated, and anisotropic emission from the isotropic QDs in the anthracene macrocrystals was discovered. Results showed a decreasing photoluminescence lifetime of the donor anthracene, indicating a strengthening energy transfer with increasing QD concentration in the macrocrystals. With the anisotropy study, QDs inside the anthracene host acquired a polarization ratio of similar to 1.5 at 0 degrees collection angle, and this increases to similar to 2.5 at the collection angle of 60 degrees. A proof-of-concept application of these excitonic macrocrystals as tunable color converters on light-emitting diodes was also demonstrated

The Association of Neighborhood Social Capital and Ethnic (Minority) Density with Pregnancy Outcomes in the Netherlands

Background: Perinatal morbidity rates are relatively high in the Netherlands, and significant inequalities in perinatal morbidity and mortality can be found across neighborhoods. In socioeconomically deprived areas, ‘Western’ women are particularly at risk for adverse birth outcomes. Almost all studies to date have explained the disparities in terms of individual determinants of birth outcomes. This study examines the influence of neighborhood contextual characteristics on birth weight (adjusted for gestational age) and preterm birth. We focused on the influence of neighborhood social capital – measured as informal socializing and social connections between neighbors – as well as ethnic (minority) density. Methods: Data on birth weight and prematurity were obtained from the Perinatal Registration Netherlands 2000–2008 dataset, containing 97% of all pregnancies. Neighborhood-level measurements were obtained from three different sources, comprising both survey and registration data. We included 3.422 neighborhoods and 1.527.565 pregnancies for the birth weight analysis and 1.549.285 pregnancies for the premature birth analysis. Linear and logistic multilevel regression was performed to assess the associations of individual and neighborhood level variables with birth weight and preterm birth. Results: We found modest but significant neighborhood effects on birth weight and preterm births. The effect of ethnic (minority) density was stronger than that of neighborhood social capital. Moreover, ethnic (minority) density was associated with higher birth weight for infants of non-Western ethnic minority women compared to Western women (15 grams; 95% CI: 12,4/17,5) as well as reduced risk for prematurity (OR 0.97; CI 0,95/0,99). Conclusions: Our results indicate that neighborhood contexts are associated with birth weight and preterm birth in the Netherlands. Moreover, ethnic (minority) density seems to be a protective factor for non-Western ethnic minority women, but not for Western women. This helps explain the increased risk of Western women in deprived neighborhoods for adverse birth outcomes found in previous studies

Improving the Segmentation Stage of a Pedestrian Tracking Video-based System by means of Evolution Strategies

12 pages, 7 figures.-- Contributed to: Eighth European Workshop on Evolutionary Computation in Image Analysis and Signal Processing (EvoIASP 2006, Budapest, Hungary, Apr 10-12, 2006).Pedestrian tracking video-based systems present particular problems such as the multi fragmentation or low level of compactness of the resultant blobs due to the human shape or movements. This paper shows how to improve the segmentation stage of a video surveillance system by adding morphological post-processing operations so that the subsequent blocks increase their performance. The adjustment of the parameters that regulate the new morphological processes is tuned by means of Evolution Strategies. Finally, the paper proposes a group of metrics to assess the global performance of the surveillance system. After the evaluation over a high number of video sequences, the results show that the shape of the tracks match up more accurately with the parts of interests. Thus, the improvement of segmentation stage facilitates the subsequent stages so that global performance of the surveillance system increases.Funded by CICYT (TIC2002-04491-C02-02)Publicad

Statistical Model of Shape Moments with Active Contour Evolution for Shape Detection and Segmentation

This paper describes a novel method for shape representation and robust image segmentation. The proposed method combines two well known methodologies, namely, statistical shape models and active contours implemented in level set framework. The shape detection is achieved by maximizing a posterior function that consists of a prior shape probability model and image likelihood function conditioned on shapes. The statistical shape model is built as a result of a learning process based on nonparametric probability estimation in a PCA reduced feature space formed by the Legendre moments of training silhouette images. A greedy strategy is applied to optimize the proposed cost function by iteratively evolving an implicit active contour in the image space and subsequent constrained optimization of the evolved shape in the reduced shape feature space. Experimental results presented in the paper demonstrate that the proposed method, contrary to many other active contour segmentation methods, is highly resilient to severe random and structural noise that could be present in the data

International multicentre study of candida auris infections

Background: Candida auris has emerged globally as a multi-drug resistant yeast and is commonly associated with nosocomial outbreaks in ICUs. Methods: We conducted a retrospective observational multicentre study to determine the epidemiology of C. auris infections, its management strategies, patient outcomes, and infection prevention and control practices across 10 centres from five countries. Results: Significant risk factors for C. auris infection include the age group of 61–70 years (39%), recent history of ICU admission (63%), diabetes (63%), renal failure (52%), presence of CVC (91%) and previous history of antibiotic treatment (96%). C. auris was commonly isolated from blood (76%). Echinocandins were the most sensitive drugs. Most common antifungals used for treatment were caspofungin (40%), anidulafungin (28%) and micafungin (15%). The median duration of treatment was 20 days. Source removal was conductedin 74% patients. All-cause crude mortality rate after 30 days was 37%. Antifungal therapy was associated with a reduction in mortality (OR:0.27) and so was source removal (OR:0.74). Contact isolation precautions were followed in 87% patients. Conclusions: C. auris infection carries a high risk for associated mortality. The organism is mainly resistant to most azoles and even amphotericin-B. Targeted antifungal therapy, mainly an echinocandin, and source control are the prominent therapeutic approaches

Large-Area (over 50 cm × 50 cm) Freestanding Films of Colloidal InP/ZnS Quantum Dots

Cataloged from PDF version of article.We propose and demonstrate the fabrication of flexible, freestanding films of InP/ZnS quantum dots (QDs) using fatty acid ligands across very large areas (greater than 50 cm x 50 cm), which have been developed for remote phosphor applications in solid-state lighting. Embedded in a poly(methyl methacrylate) matrix, although the formation of stand alone films using other QDs commonly capped with trioctylphosphine oxide (TOPO) and oleic acid is not efficient, employing myristic acid as ligand in the synthesis of these QDs, which imparts a strongly hydrophobic character to the thin film, enables film formation and ease of removal even on surprisingly large areas, thereby avoiding the need for ligand exchange. When pumped by a blue LED, these Cd-free QD films allow for high color rendering, warm white light generation with a color rendering index of 89.30 and a correlated color temperature of 2298 K. In the composite film, the temperature-dependent emission kinetics and energy transfer dynamics among different-sized InP/ZnS QDs are investigated and a model is proposed. High levels of energy transfer efficiency (up to 80%) and strong donor lifetime modification (from 18 to 4 ns) are achieved. The suppression of the nonradiative channels is observed when the hybrid film is cooled to cryogenic temperatures. The lifetime changes of the donor and acceptor InP/ZnS QDs in the film as a result of the energy transfer are explained well by our theoretical model based on the exciton-exciton interactions among the dots and are in excellent agreement with the experimental results. The understanding of these excitonic interactions is essential to facilitate improvements in the fabrication of photometrically high quality nanophosphors. The ability to make such large-area, flexible, freestanding Cd-free QD films pave the way for environmentally friendly phosphor applications including flexible, surface-emitting light engines

Voltage Regulator Module Noise Analysis for High-Volume Server Applications

This paper presents a methodology to analyze voltage regulator module (VRM) noise coupling problems in high-volume server applications. The technique is applied on a real engineering design. The comprehensive model includes irregular power shapes, decoupling capacitors, and dielectric and conductive loss. Irregular shaped power plane modeling is cross-checked with four separate methods to demonstrate accuracy

Natural Diagonal Riemannian Almost Product and Para-Hermitian Cotangent Bundles

We obtain the natural diagonal almost product and locally product structures on the total space of the cotangent bundle of a Riemannian manifold. We find the Riemannian almost product (locally product) and the (almost) para-Hermitian cotangent bundles of natural diagonal lift type. We prove the characterization theorem for the natural diagonal (almost) para-K\"ahlerian structures on the total spaces of the cotangent bundle.Comment: 10 pages, will appear in Czechoslovak Mathematical Journa