4,030 research outputs found

    Depth from Monocular Images using a Semi-Parallel Deep Neural Network (SPDNN) Hybrid Architecture

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    Deep neural networks are applied to a wide range of problems in recent years. In this work, Convolutional Neural Network (CNN) is applied to the problem of determining the depth from a single camera image (monocular depth). Eight different networks are designed to perform depth estimation, each of them suitable for a feature level. Networks with different pooling sizes determine different feature levels. After designing a set of networks, these models may be combined into a single network topology using graph optimization techniques. This "Semi Parallel Deep Neural Network (SPDNN)" eliminates duplicated common network layers, and can be further optimized by retraining to achieve an improved model compared to the individual topologies. In this study, four SPDNN models are trained and have been evaluated at 2 stages on the KITTI dataset. The ground truth images in the first part of the experiment are provided by the benchmark, and for the second part, the ground truth images are the depth map results from applying a state-of-the-art stereo matching method. The results of this evaluation demonstrate that using post-processing techniques to refine the target of the network increases the accuracy of depth estimation on individual mono images. The second evaluation shows that using segmentation data alongside the original data as the input can improve the depth estimation results to a point where performance is comparable with stereo depth estimation. The computational time is also discussed in this study.Comment: 44 pages, 25 figure

    Modeling the RXTE light curve of η\eta Carinae from a 3-D SPH simulation of its binary wind collision

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    The very massive star system η\eta Carinae exhibits regular 5.54-year (2024-day) period disruptive events in wavebands ranging from the radio to X-ray. There is a growing consensus that these events likely stem from periastron passage of an (as yet) unseen companion in a highly eccentric (ϵ0.9\epsilon \sim 0.9) orbit. This paper presents three-dimensional (3-D) Smoothed Particle Hydrodynamics (SPH) simulations of the orbital variation of the binary wind-wind collision, and applies these to modeling the X-ray light curve observed by the Rossi X-ray Timing Explorer (RXTE). By providing a global 3-D model of the phase variation of the density of the interacting winds, the simulations allow computation of the associated variation in X-ray absorption, presumed here to originate from near the apex of the wind-wind interaction cone. We find that the observed RXTE light curve can be readily fit if the observer's line of sight is within this cone along the general direction of apastron. Specifically, the data are well fit by an assumed inclination i=45i = 45^{\circ} for the orbit's polar axis, which is thus consistent with orbital angular momentum being along the inferred polar axis of the Homunculus nebula. The fits also constrain the position angle ϕ\phi that an orbital-plane projection makes with the apastron side of the semi-major axis, strongly excluding positions ϕ<9\phi < 9^{\circ} along or to the retrograde side of the axis, with the best fit position given by ϕ=27\phi = 27^{\circ}. Overall the results demonstrate the utility of a fully 3-D dynamical model for constraining the geometric and physical properties of this complex colliding-wind binary system.Comment: 5 pages, 4 figures, accepted to MNRAS Letter

    Changing Labor Market Opportunities for Women and the Quality of Teachers 1957-1992

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    School officials and policy makers have grown increasingly concerned about their ability to attract and retain talented teachers. A number of authors have shown that in recent years the brightest students at least those with the highest verbal and math scores on standardized tests are less likely to enter teaching. In addition, it is frequently claimed that the ability of schools to attract these top students has been steadily declining for years. There is, however, surprisingly little evidence measuring the extent to which this popular proposition is true. We have good reason to suspect that the quality of those entering teaching has fallen over time. Teaching has remained a predominately female profession for years; at the same time, the employment opportunities for talented women outside of teaching have soared. In this paper, we combine data from four longitudinal surveys of high school graduates spanning the years 1957-1992 to examine how the propensity for talented women to enter teaching has changed over time. We find that while the quality of the average new female teacher has fallen only slightly over this period, the likelihood that a female from the top of her high school class will eventually enter teaching has fallen dramatically from 1964 to 1992 by our estimation, from almost 20% to under 4%.

    Supercritical multicomponent solvent coal extraction

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    The yield of organic extract from the supercritical extraction of coal with larger diameter organic solvents such as toluene is increased by use of a minor amount of from 0.1 to 10% by weight of a second solvent such as methanol having a molecular diameter significantly smaller than the average pore diameter of the coal

    Payout Policy in the 21st Century

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    We survey 384 CFOs and Treasurers, and conduct in-depth interviews with an additional two dozen, to determine the key factors that drive dividend and share repurchase policies. We find that managers are very reluctant to cut dividends, that dividends are smoothed through time, and that dividend increases are tied to long-run sustainable earnings but much less so than in the past. Rather than increasing dividends, many firms now use repurchases as an alternative. Paying out with repurchases is viewed by managers as being more flexible than using dividends, permitting a better opportunity to optimize investment. Managers like to repurchase shares when they feel their stock is undervalued and in an effort to affect EPS. Dividend increases and the level of share repurchases are generally paid out of residual cash flow, after investment and liquidity needs are met. Financial executives believe that retail investors have a strong preference for dividends, in spite of the tax disadvantage relative to repurchases. In contrast, executives believe that institutional investors as a class have no strong preference between dividends and repurchases. In general, management views provide at most moderate support for agency, signaling, and clientele hypotheses of payout policy. Tax considerations play only a secondary role. By highlighting where the theory and practice of corporate payout policy are consistent and where they are not, we attempt to shed new light on important unresolved issues related to payout policy in the 21st century.

    Bowel cancer screening and people with intellectual disabilities: working in co-production and establishing principles for good practice initiatives

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    Bowel cancer is the fourth most common cancer in England, and with one in 20 people developing the condition, it is the second highest cause of cancer deaths. If diagnosed early, treatment can be more effective and bowel cancer screening programmes can reduce these mortality figures, yet for people with learning disabilities, the uptake of screening is significantly lower than the rest of the population. Aims To describe the process of co-production when working with a group of people with learning disabilities to explore why they may be reluctant to access bowel cancer screening. Methods A consultation meeting was held with one of the authors, six people with learning disabilities, an advocate and two specialist nurses. A feedback session was organised and a report using clear information was written in conjunction with the participants. Findings Participants discussed what gets in the way of attending for bowel screening and what might help to increase uptake, including awareness, support and clear information. Conclusion Working in co-production proved mutually beneficial as local clinicians also learned how to communicate more effectively with people who have learning disabilities

    The Molecular Gas Environment around Two Herbig Ae/Be Stars: Resolving the Outflows of LkHa 198 and LkHa 225S

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    Observations of outflows associated with pre-main-sequence stars reveal details about morphology, binarity and evolutionary states of young stellar objects. We present molecular line data from the Berkeley-Illinois-Maryland Association array and Five Colleges Radio Astronomical Observatory toward the regions containing the Herbig Ae/Be stars LkHa 198 and LkHa 225S. Single dish observations of 12CO 1-0, 13CO 1-0, N2H+ 1-0 and CS 2-1 were made over a field of 4.3' x 4.3' for each species. 12CO data from FCRAO were combined with high resolution BIMA array data to achieve a naturally-weighted synthesized beam of 6.75'' x 5.5'' toward LkHa 198 and 5.7'' x 3.95'' toward LkHa 225S, representing resolution improvements of factors of approximately 10 and 5 over existing data. By using uniform weighting, we achieved another factor of two improvement. The outflow around LkHa 198 resolves into at least four outflows, none of which are centered on LkHa 198-IR, but even at our resolution, we cannot exclude the possibility of an outflow associated with this source. In the LkHa 225S region, we find evidence for two outflows associated with LkHa 225S itself and a third outflow is likely driven by this source. Identification of the driving sources is still resolution-limited and is also complicated by the presence of three clouds along the line of sight toward the Cygnus molecular cloud. 13CO is present in the environments of both stars along with cold, dense gas as traced by CS and (in LkHa 225S) N2H+. No 2.6 mm continuum is detected in either region in relatively shallow maps compared to existing continuum observations.Comment: 14 pages, 10 figures (5 color), accepted for publication in Ap

    Quasiparticles in the vortex state of V3Si

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    Low-energy quasiparticle excitations in the vortex state of the superconductor V3Si have been investigated using the de Haas-van Alphen effect. Quantum oscillations persist to surprisingly low values of B0/B(c2) is similar to 0.6 and T/T(c) is similar to 0.001. The superconducting state introduces a field-dependent quasiparticle damping which has a value HBAR tau-1 almost-equal-to 0.25 DELTA at the lowest fields investigated, considerably less than the superconducting gap DELTA. Quantum oscillations are attributed to the presence of a gapless excitation spectrum and may be a universal characteristic of superconductors in the vortex state
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