1,829 research outputs found
50 Years Later: Women, Work & the Work Ahead (Infographic)
How have things changed for women in the labor force over the last 50 years
Inverse design and implementation of a wavelength demultiplexing grating coupler
Nanophotonics has emerged as a powerful tool for manipulating light on chips.
Almost all of today's devices, however, have been designed using slow and
ineffective brute-force search methods, leading in many cases to limited device
performance. In this article, we provide a complete demonstration of our
recently proposed inverse design technique, wherein the user specifies design
constraints in the form of target fields rather than a dielectric constant
profile, and in particular we use this method to demonstrate a new
demultiplexing grating. The novel grating, which has not been developed using
conventional techniques, accepts a vertical-incident Gaussian beam from a
free-space and separates O-band and C-band
light into separate waveguides. This inverse design concept
is simple and extendable to a broad class of highly compact devices including
frequency splitters, mode converters, and spatial mode multiplexers.Comment: 17 pages, 4 figures, 1 table. A supplementary section describing the
inverse-design algorithm in detail has been added, in addition to minor
corrections and updated reference
Achieving Efficient Strong Scaling with PETSc using Hybrid MPI/OpenMP Optimisation
The increasing number of processing elements and decreas- ing memory to core
ratio in modern high-performance platforms makes efficient strong scaling a key
requirement for numerical algorithms. In order to achieve efficient scalability
on massively parallel systems scientific software must evolve across the entire
stack to exploit the multiple levels of parallelism exposed in modern
architectures. In this paper we demonstrate the use of hybrid MPI/OpenMP
parallelisation to optimise parallel sparse matrix-vector multiplication in
PETSc, a widely used scientific library for the scalable solution of partial
differential equations. Using large matrices generated by Fluidity, an open
source CFD application code which uses PETSc as its linear solver engine, we
evaluate the effect of explicit communication overlap using task-based
parallelism and show how to further improve performance by explicitly load
balancing threads within MPI processes. We demonstrate a significant speedup
over the pure-MPI mode and efficient strong scaling of sparse matrix-vector
multiplication on Fujitsu PRIMEHPC FX10 and Cray XE6 systems
Embedding of psycho-perceptual-motor skills can improve athlete assessment and training programs
Practitioners in a variety of sports seek unique ways to train athletes to better prepare them for competition. In this position paper, we argue that inclusion of psycho-perceptual-motor skills, from the fields of sport psychology and sport expertise, is crucial, but underutilized in the assessment and training of athletes. First, a brief introduction is provided as to why psycho-perceptual-motor skill is vital for training athletes. Second, examples are discussed relating to key concepts. These include the following: assessment of expertise discriminators such as visual anticipation under pressure contexts, incorporation of sports analytics and performance analysis to aid reflection upon previous experiences of good anticipation and coping with pressure, use of qualitative and quantitative measures to understand processes underlying performance and learning, as well as design of representative tasks for assessment and training anticipation under pressure contexts. Third, some recommendations are made to practitioners of sports teams to assist them in taking advantage of psycho-perceptual-motor skill to better prepare athletes for competition. Collectively, we hope this paper stimulates collaboration between practitioners of sports teams and scientists to create a greater focus upon integrated sport psychology and sport expertise in the training of athletes
How large are the incentives to join sub-global carbon reduction initiatives?
This paper attempts to shed some light on what the incentives are for international participation in 'sub-global' carbon reduction initiatives. We use a six-region global general equilibrium trade and carbon emission model recently used by Whalley and Wigle to analyze the international incidence effects of various global carbon tax schemes. Here we modify this model so as to also capture the benefit side of reduced global warming by including emission reduction in the specification of preferences in each region. This change in model structure allows us to examine the strength of the incentives for sub-global arrangements to form with the aim of achieving reduced carbon emissions. Because there are no reliable estimates of the benefits from slowed global warming, we have adopted a procedure of evaluating incentives for any sub-global arrangements to be used relative to a reference point: 50 percent global emission reduction target, as in the 1988 Toronto call, is assumed to represent a full-participation global optimum, in which the sum of marginal country benefits from further global abatement exactly balance marginal country costs from further reductions in sue of carbon-based energy. A number of interesting points emerge from our calculations. Incentives for the larger regions to engage in unilateral emission reductions (including the U.S. which accounts for nearly 25 percent of global emissions) are surprisingly strong (more than half the assumed optimal 50% global reduction). The optimal reduction increases further when pairs of regions who each provide emission reduction benefits to the other are considered (more than 35 percent for North America and Europe). Also, terms-of-trade effects from such cuts help energy importers and amplify (in some cases substantially) the benefits to them of reduced emissions from slowed global warming. But both production and consumption-based cuts create spillover effects stimulating production or consumption in other regions, suggesting that sub-global arrangements to reduce emissions are more likely to be successful if accompanied by constraints on non-participants. The overall picture that emerges is that even with limited country participation in such schemes, significant emission reductions (given the assumed 50% full participation optimal cut) are still beneficial to participating countries
Multicenter Validation of the Vasoactive-Ventilation-Renal Score as a Predictor of Prolonged Mechanical Ventilation After Neonatal Cardiac Surgery
Objectives: We sought to validate the Vasoactive-Ventilation-Renal score, a novel disease severity index, as a predictor of outcome in a multicenter cohort of neonates who underwent cardiac surgery.
Design: Retrospective chart review.
Setting: Seven tertiary-care referral centers.
Patients: Neonates defined as age less than or equal to 30 days at the time of cardiac surgery.
Interventions: Ventilation index, Vasoactive-Inotrope Score, serum lactate, and Vasoactive-Ventilation-Renal score were recorded for three postoperative time points: ICU admission, 6 hours, and 12 hours. Peak values, defined as the highest of the three measurements, were also noted. Vasoactive-Ventilation-Renal was calculated as follows: ventilation index + Vasoactive-Inotrope Score + Δ creatinine (change in creatinine from baseline × 10). Primary outcome was prolonged duration of mechanical ventilation, defined as greater than 96 hours. Receiver operative characteristic curves were generated, and abilities of variables to correctly classify prolonged duration of mechanical ventilation were compared using area under the curve values. Multivariable logistic regression modeling was also performed.
Measurements and Main Results: We reviewed 275 neonates. Median age at surgery was 7 days (25th–75th percentile, 5–12 d), 86 (31%) had single ventricle anatomy, and 183 (67%) were classified as Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Category 4 or 5. Prolonged duration of mechanical ventilation occurred in 89 patients (32%). At each postoperative time point, the area under the curve for prolonged duration of mechanical ventilation was significantly greater for the Vasoactive-Ventilation-Renal score as compared to the ventilation index, Vasoactive-Inotrope Score, and serum lactate, with an area under the curve for peak Vasoactive-Ventilation-Renal score of 0.82 (95% CI, 0.77–0.88). On multivariable analysis, peak Vasoactive-Ventilation-Renal score was independently associated with prolonged duration of mechanical ventilation, odds ratio (per 1 unit increase): 1.08 (95% CI, 1.04–1.12).
Conclusions: In this multicenter cohort of neonates who underwent cardiac surgery, the Vasoactive-Ventilation-Renal score was a reliable predictor of postoperative outcome and outperformed more traditional measures of disease complexity and severity
Alternative student finance : current and future students’ perspectives: Research report, May 2019
Recommended from our members
Inverse-designed diamond photonics
Diamond hosts optically active color centers with great promise in quantum computation, networking, and sensing. Realization of such applications is contingent upon the integration of color centers into photonic circuits. However, current diamond quantum optics experiments are restricted to single devices and few quantum emitters because fabrication constraints limit device functionalities, thus precluding color center integrated photonic circuits. In this work, we utilize inverse design methods to overcome constraints of cutting-edge diamond nanofabrication methods and fabricate compact and robust diamond devices with unique specifications. Our design method leverages advanced optimization techniques to search the full parameter space for fabricable device designs. We experimentally demonstrate inverse-designed photonic free-space interfaces as well as their scalable integration with two vastly different devices: classical photonic crystal cavities and inverse-designed waveguide-splitters. The multi-device integration capability and performance of our inverse-designed diamond platform represents a critical advancement toward integrated diamond quantum optical circuits
- …
