2,055 research outputs found

    Endogenous growth and recycling : a material balance approach

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    In this paper we analyze the importance of recycling in the strive for sustainable development. In contrast to former approaches we emphasize the role of the waste stock as a source of valuable inputs. We enhance a Romer (1990) type endogenous growth model by a material balance condition that re°ects the circulation of matter in the economy. DiŸerentiated intermediate products are produced from recycled waste and virgin resources. These material intermediates are then employed in the production of ¯nal output. They either end up as waste after consumption or are bound in the capital stock { depending on the utilization of the produced output. We show that, even in the absence of environmental policy, long-run development is sustainable in this economy. The intuition is, that, as waste is a valuable resource in our model, not recycling part of it, cannot be optimal in the long-run.non-renewable resources, recycling, endogenous growth, sustainable development

    Creation of strange matter at low initial m/T

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    We demonstrate that the creation of strange matter is conceivable in the midrapidity region of heavy ion collisions at Brookhaven RHIC and CERN LHC. A finite net-baryon density, abundant (anti)strangeness production, as well as strong net-baryon and net-strangeness fluctuations, provide suitable initial conditions for the formation of strangelets or metastable exotic multistrange ( baryonic) objects. Even at very high initial entropy per baryon SyAinit ÂŻ 500 and low initial baryon numbers of Ainit B ÂŻ 30 a quark-gluon-plasma droplet can immediately charge up with strangeness and accumulate net-baryon number. PACS numbers: 25.75.Dw, 12.38.Mh, 24.85.

    Lyot-based Low Order Wavefront Sensor: Implementation on the Subaru Coronagraphic Extreme Adaptive Optics System and its Laboratory Performance

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    High throughput, low inner working angle (IWA) phase masks coronagraphs are essential to directly image and characterize (via spectroscopy) earth-like planets. However, the performance of low-IWA coronagraphs is limited by residual pointing errors and other low-order modes. The extent to which wavefront aberrations upstream of the coronagraph are corrected and calibrated drives coronagraphic performance. Addressing this issue is essential for preventing coronagraphic leaks, thus we have developed a Lyot-based low order wave front sensor (LLOWFS) to control the wavefront aberrations in a coronagraph. The LLOWFS monitors the starlight rejected by the coronagraphic mask using a reflective Lyot stop in the downstream pupil plane. The early implementation of LLOWFS at LESIA, Observatoire de Paris demonstrated an open loop measurement accuracy of 0.01 lambda/D for tip-tilt at 638 nm when used in conjunction with a four quadrant phase mask (FQPM) in the laboratory. To further demonstrate our concept, we have installed the reflective Lyot stops on the Subaru Coronagraphic Extreme AO (SCExAO) system at the Subaru Telescope and modified the system to support small IWA phase mask coronagraphs (< 1 lambda/D) on-sky such as FQPM, eight octant phase mask, vector vortex coronagraph and the phase induced amplitude apodization complex phase mask coronagraph with a goal of obtaining milli arc-second pointing accuracy. Laboratory results have shown the measurement of tip, tilt, focus, oblique and right astigmatism at 1.55 um for the vector vortex coronagraph. Our initial on-sky result demonstrate the closed loop accuracy of < 7 x 10-3 lambda/D at 1.6 um for tip, tilt and focus aberrations with the vector vortex coronagraph.Comment: 9 pages, 9 Figures, Proc. of SPIE Astronomical Telescopes + Instrumentation 201

    On-sky demonstration of low-order wavefront sensing and control with focal plane phase mask coronagraphs

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    The ability to characterize exoplanets by spectroscopy of their atmospheres requires direct imaging techniques to isolate planet signal from the bright stellar glare. One of the limitations with the direct detection of exoplanets, either with ground- or space-based coronagraphs, is pointing errors and other low-order wavefront aberrations. The coronagraphic detection sensitivity at the diffraction limit therefore depends on how well low-order aberrations upstream of the focal plane mask are corrected. To prevent starlight leakage at the inner working angle of a phase mask coronagraph, we have introduced a Lyot-based low-order wavefront sensor (LLOWFS), which senses aberrations using the rejected starlight diffracted at the Lyot plane. In this paper, we present the implementation, testing and results of LLOWFS on the Subaru Coronagraphic Extreme Adaptive Optics system (SCExAO) at the Subaru Telescope. We have controlled thirty-five Zernike modes of a H-band vector vortex coronagraph in the laboratory and ten Zernike modes on sky with an integrator control law. We demonstrated a closed-loop pointing residual of 0.02 mas in the laboratory and 0.15 mas on sky for data sampled using the minimal 2-second exposure time of the science camera. We have also integrated the LLOWFS in the visible high-order control loop of SCExAO, which in closed-loop operation has validated the correction of the non-common path pointing errors between the infrared science channel and the visible wavefront sensing channel with pointing residual of 0.23 mas on sky.Comment: 12 pages, 15 figures, Accepted and scheduled for publication in September 2015 issue of the PAS

    Nano-optomechanical measurement in the photon counting regime

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    Optically measuring in the photon counting regime is a recurrent challenge in modern physics and a guarantee to develop weakly invasive probes. Here we investigate this idea on a hybrid nano-optomechanical system composed of a nanowire hybridized to a single Nitrogen-Vacancy (NV) defect. The vibrations of the nanoresonator grant a spatial degree of freedom to the quantum emitter and the photon emission event can now vary in space and time. We investigate how the nanomotion is encoded on the detected photon statistics and explore their spatio-temporal correlation properties. This allows a quantitative measurement of the vibrations of the nanomechanical oscillator at unprecedentedly low light intensities in the photon counting regime when less than one photon is detected per oscillation period, where standard detectors are dark-noise-limited. These results have implications for probing weakly interacting nanoresonators, for low temperature experiments and for investigating single moving markers

    Approach for tuberculosis-associated immune reconstitution inflammatory syndrome in an HIV-negative patient

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    A male refugee from the Middle East was diagnosed with pulmonary tuberculosis and Pott’s disease with paravertebral abscess. After starting the standard regimen, the sputum culture converted to negative and the patient’s general condition improved. Six weeks later, the patient presented with clinical worsening of known symptoms, new appearance of focal neurological deficits and progress of radiological features showing progression of the paravertebral abscess. Immune reconstitution inflammatory syndrome with Mycobacterium tuberculosis (TB-IRIS) was presumed, and treatment with high-dose steroids was started. Due to recurrent relapses while tapering, corticosteroids had to be given over a prolonged period. After treatment completion, the patient was in a good general condition, abscesses had decreased and neurological deficits were in complete remission. This case presents the rare manifestation of TB-IRIS in HIV-negative patients and its management in a high-income country

    Relationship intention and relationship quality as predictors of clothing retail customers' loyalty

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    Retailers endeavour to establish and maintain strong relationships with customers in order to build customer loyalty. Unfortunately, such endeavours are not always successful as not all retail customers reciprocate retailers’ relationship efforts. Customers’ intentions to engage in relationships with retailers (i.e. relationship intentions) should thus be the starting point in building customer loyalty. Moreover, customers’ perceptions of the strength of their relationship with a retailer (i.e. relationship quality) should also be considered when building customer loyalty. The purpose of this study is to determine whether clothing retail customers’ relationship intentions and relationship quality, individually and in combination, predict their loyalty to clothing retailers. Data were collected from 511 respondents in South Africa’s greater Tshwane metropolitan area. From a hierarchical multiple regression analysis, it was found that clothing retail customers’ relationship intentions and relationship quality are individually, and in combination, predictors of their loyalty to the retailer. Results furthermore indicate that relationship quality mediates the relationship between relationship intention and customer loyalty. The findings highlight the importance of first determining customers’ relationship intentions, and then reinforcing positive perceptions of relationship quality when building customer loyalty.http://www.tandfonline.com/loi/rirr20hj2019Marketing Managemen
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