595 research outputs found

    An integrated reconfigurable Bragg grating utilising a photoresponsive co-polymer

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    Reconfigurable Bragg grating devices are of significant interest for telecomm applications. Such devices can be fabricated by combining a UV-written silica Bragg grating with an azobenzene-based polymer - a photoresponsive material that undergoes reversible refractive index change on exposure to ultraviolet light. The preliminary 17 GHz tuning response suggests future applicability

    On two-point boundary value problems in multi-ion electrodiffusion

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    AbstractThe solvability is established of certain two-point boundary value problems for nonlinear equations that arise in multi-ion electrodiffusion. Topological methods are adduced to prove the existence of solutions under appropriate conditions on the physical parameters

    Simple Fluids with Complex Phase Behavior

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    We find that a system of particles interacting through a simple isotropic potential with a softened core is able to exhibit a rich phase behavior including: a liquid-liquid phase transition in the supercooled phase, as has been suggested for water; a gas-liquid-liquid triple point; a freezing line with anomalous reentrant behavior. The essential ingredient leading to these features resides in that the potential investigated gives origin to two effective core radii.Comment: 7 pages including 3 eps figures + 1 jpeg figur

    Spatial correlations in vote statistics: a diffusive field model for decision-making

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    We study the statistics of turnout rates and results of the French elections since 1992. We find that the distribution of turnout rates across towns is surprisingly stable over time. The spatial correlation of the turnout rates, or of the fraction of winning votes, is found to decay logarithmically with the distance between towns. Based on these empirical observations and on the analogy with a two-dimensional random diffusion equation, we propose that individual decisions can be rationalised in terms of an underlying "cultural" field, that locally biases the decision of the population of a given region, on top of an idiosyncratic, town-dependent field, with short range correlations. Using symmetry considerations and a set of plausible assumptions, we suggest that this cultural field obeys a random diffusion equation.Comment: 18 pages, 5 figures; added sociophysics references

    A framework for digital sunken relief generation based on 3D geometric models

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    Sunken relief is a special art form of sculpture whereby the depicted shapes are sunk into a given surface. This is traditionally created by laboriously carving materials such as stone. Sunken reliefs often utilize the engraved lines or strokes to strengthen the impressions of a 3D presence and to highlight the features which otherwise are unrevealed. In other types of reliefs, smooth surfaces and their shadows convey such information in a coherent manner. Existing methods for relief generation are focused on forming a smooth surface with a shallow depth which provides the presence of 3D figures. Such methods unfortunately do not help the art form of sunken reliefs as they omit the presence of feature lines. We propose a framework to produce sunken reliefs from a known 3D geometry, which transforms the 3D objects into three layers of input to incorporate the contour lines seamlessly with the smooth surfaces. The three input layers take the advantages of the geometric information and the visual cues to assist the relief generation. This framework alters existing techniques in line drawings and relief generation, and then combines them organically for this particular purpose

    A predictive preoperative and postoperative nomogram for postoperative potency recovery after robot-assisted radical prostatectomy

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    Purpose: Prediction of potency recovery following robot-assisted radical prostatectomy (RARP) is useful for better patient counseling and postoperative treatment strategies. In this study we propose a preoperative and postoperative nomogram to predict postoperative potency recovery following RARP.Materials and Methods: Patients from development set (6,502) were selected to develop the nomograms, and patients in validation set (2,706) were used for validation. Cox regression models were fitted on the development cohort to predict potency recovery after RARP using as prognostic factors the covariates selected. Two nomograms were drawn using the regression coefficients of the preoperative and postoperative Cox models.Results: The discrimination ability of the preoperative model was evaluated on the development cohort using the receiver operator curves estimated at 3, 6, 12 and 24 months. The AUC at these time points was 0.726, 0.734, 0.754, and 0.778, respectively. The areas under the curve of the postoperative model at 3, 6, 12 and 24 months were 0.746, 0.756 and 0.777, and 0.801, respectively. Preoperative and postoperative predictive models were validated using a separate set of 2,706 patients. The AUCs of the preoperative model at 3, 6, 12 and 24 months were 0.789, 0.772, 0.768, and 0.778, respectively. The ROC curves of the postoperative model at 3, 6, 12 and 24 months with AUCs of 0.807, 0.797, 0.793 and 0.798, respectively. Along with age and preoperative sexual function, nerve-sparing technique determines the potency outcomes justifying better AUC for postoperative model vs the preoperative model.Conclusions: The above nomograms help us to predict with good accuracy the probability of potency recovery within 3, 6, 12 and 24 months following surgery taking into consideration preoperative and postoperative factors. This is a novel tool for the care giver to predict realistic expectation of potency outcomes to the patients, while preoperative and immediate postoperative counseling

    Analytical results for coupled map lattices with long-range interactions

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    We obtain exact analytical results for lattices of maps with couplings that decay with distance as r−αr^{-\alpha}. We analyze the effect of the coupling range on the system dynamics through the Lyapunov spectrum. For lattices whose elements are piecewise linear maps, we get an algebraic expression for the Lyapunov spectrum. When the local dynamics is given by a nonlinear map, the Lyapunov spectrum for a completely synchronized state is analytically obtained. The critical lines characterizing the synchronization transition are determined from the expression for the largest transversal Lyapunov exponent. In particular, it is shown that in the thermodynamical limit, such transition is only possible for sufficiently long-range interactions, namely, for α≀alphac<d\alpha\le alpha_c<d, where dd is the lattice dimension.Comment: 4 pages, 2 figures, corrections included. Phys. Rev. E 68, 045202(R) (2003); correction in pres

    Development and implementation of natural killer cell simultaneous ADCC and direct killing assay

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    Assays to quantify natural killer (NK) cell killing efficacy have traditionally focused on assessing either direct killing or antibody dependent cell-mediated cytotoxicity (ADCC) independently. Due to the probability that immunotherapeutic interventions affect NK cell-mediated direct killing and NK cell-mediated ADCC differently, we developed an assay with the capacity to measure NK cell-mediated direct killing and ADCC simultaneously with cells from the same human donor. Specifically, this design allows for a single NK cell population to be split into several experimental conditions (e.g., direct killing, ADCC), thus controlling for potential confounders associated with human-to-human variation when assessing immunotherapy impacts. Our Natural Killer cell Simultaneous ADCC and Direct Killing Assay (NK-SADKA) allows researchers to reproducibly quantify both direct killing and ADCC by human NK cells. Furthermore, this optimized experimental design allows for concurrent analysis of the NK cells via flow cytometric immunophenotyping of NK cell populations which will facilitate the identification of relationships between NK cell phenotype and the subsequent killing potential. This assay will be valuable for assessing the broader impact(s) of immunotherapy strategies on both modes of NK cell killing

    The impact of Covid-19 on lifestyle and dietary habits during and after lockdown in people with neurological conditions, and their perceptions of how these changes have impacted their physical and mental health: a cross-sectional survey study

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    Introduction:- Research has shown that the Covid-19 pandemic may have had negative effects on lifestyle factors of people in the UK, however research is limited in terms of the impact on people living with neurological conditions such as Multiple Sclerosis (MS), Parkinson’s (PD) and spinal cord injury (SCI). This study explores the impact that the pandemic had on mental health and lifestyle factors such as dietary habits, supplement use and exercise in those with MS, PD and SCI. Methods:- A cross-sectional, online, questionnaire study was carried out on a cohort of 134 people in the United Kingdom during the Covid-19 pandemic. Participants completed the questionnaire between June 2021–February 2022. Eligibility criteria included being over the age of 18 years, and declaring having been formally diagnosed with either MS (n=27, female=81%), PD (n=84, female=35%), SCI (n=23, female=61%). Results:- 33% of participants reported an increased consumption of alcohol and 29% a decreased consumption of fruit and vegetables. However, 64% of participants reported no change in diet (p < 0.001). Vitamin D, multivitamin/minerals, probiotic and fish oil were the most commonly consumed supplements by participants. Although intake of any supplement was not significantly impacted by Covid-19 for the total cohort, by condition, and by sex, a generalised linear mixed model indicated SCI participants consumed more supplement types during Covid-19 than before (OR:1.98; 95% CI [1.04, 3.77]). Additionally, 29% of participants reported they contacted their families less than pre-pandemic (p=0.001), and 60% reported they experienced more fatigue since the pandemic. Open-ended questions added quality context to the categorical data. Conclusion:- This study suggests that the impact Covid-19 has had on people with neurological conditions is complex and individual, yet the negative effects may be more pronounced than the general public. Overall, there were changes in lifestyle behaviours, some which may be detrimental to health and life quality in these already vulnerable groups. Therefore, these changes need to be considered in the aftermath of the pandemic

    Processing of ultrafine-size particulate metal matrix composites by advanced shear technology

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    Copyright @ 2009 ASM International. This paper was published in Metallurgical & Materials Transactions A 40A(3) and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.Lack of efficient mixing technology to achieve a uniform distribution of fine-size reinforcement within the matrix and the high cost of producing components have hindered the widespread adaptation of particulate metal matrix composites (PMMCs) for engineering applications. A new rheo-processing method, the melt-conditioning high-pressure die-cast (MC-HPDC) process, has been developed for manufacturing near-net-shape components of high integrity. The MC-HPDC process adapts the well-established high shear dispersive mixing action of a twin-screw mechanism to the task of overcoming the cohesive force of the agglomerates under a high shear rate and high intensity of turbulence. This is followed by direct shaping of the slurry into near-net-shape components using an existing cold-chamber die-casting process. The results indicate that the MC-HPDC samples have a uniform distribution of ultrafine-sized SiC particles throughout the entire sample in the as-cast condition. Compared to those produced by conventional high-pressure die casting (HPDC), MC-HPDC samples have a much improved tensile strength and ductility.EP-SR
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