874 research outputs found

    Work Attitudes, Values, Interpersonal Relationships, and Job Characteristics across Cultures: A Comparative Study of Korea, China, and the U. S. A.

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    This study examined cross-cultural/country differences in variables that are related to work motivation across three countries - Korea. China and the U.S. In particular. this study compared the antecedents to work attitudes such as values. job characteristics. and interpersonal relationships. Consistent with the previous findings in cross-cultural management literature. there were significant differences in the variables across the three countries. In addition. there were subtle differences in the functions work attitudes such as organizational commitment and job satisfaction. Implications for cross-cultural management were offered. 본 연구는 종업원들의 동기부여와 관련된 변수들에 관하여 한국, 중국, 미국의 세 나라를 비교하였다. 구체적으로 종업원들의 조직몰입도, 직무만족도, 회사 및 일과 관련된 가치관, 회사에서 대인관계의 성격 및 직무의 성격에 관해서 비교연구를 하였다. 이전의 연구와 마찬가지로 이 세나라 사이에 유의한 상이점이 본 연구에서 발견되었다. 특히 각 나라별로 조직몰입도와 직무만족도에 영향을 주는 영행변수들이 약간씩의 차이를 보였다. 본연구가 이론과 실무에 주는 의미도 정리하였다

    Fabrication of Micro-Perforated Panel (MPP) sound absorbers using Digital Light Processing (DLP) 3D printing technology

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    The fabrication of Micro-Perforated Panels (MPPs) still constitutes a challenge to the acoustic materials industry because it usually requires expensive manufacturing techniques to obtain holes of submillimetre size. In this context, the rise of additive manufacturing or 3D printing (3DP) technologies over the last years has paved the way for the design and development of new materials at the microscopic scale. Among these, Digital Light Processing (DLP) technology emerges as an excellent option due to its advantages in terms of printing speed and higher accuracy when compared to traditional additive manufacturing technologies. This work demonstrates the capacity of DLP technology to fabricate MPPs and explores its design possibilities by using different exposure times in the manufacturing process to attain different hole sizes. To this end, several MPP specimens were fabricated and tested when used as a resonator system in an impedance tube setup to determine their sound absorption performance, the experimental data showing a good agreement when compared to predictions obtained using the Maa model. Preliminary results highlight the potential capabilities of DLP and encourage its use in the design stage of these acoustics resonator systems.The conception of this research work took place at the Department of Mechanical Engineering at the Massachusetts Institute of Technology with support from the University of Alicante (Grant ACIE20-04)

    Xenon excimer emission from multicapillary discharges in direct current mode

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    Microdischarges in xenon have been generated in a pressure range of 400–1013 mbar with a fixed flow rate of 100 sccm. These microdischarges are obtained from three metallic capillary tubes in series for excimer emission. Total discharge voltage is thrice as large as that of a single capillary discharge tube at current levels of up to 12 mA. Total spectral irradiance of vacuum ultraviolet (VUV) emission also increases significantly compared to that of the single capillary discharge. Further, the irradiance of the VUV emission is strongly dependent on pressure as well as the discharge current

    Tau functions as Widom constants

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    We define a tau function for a generic Riemann-Hilbert problem posed on a union of non-intersecting smooth closed curves with jump matrices analytic in their neighborhood. The tau function depends on parameters of the jumps and is expressed as the Fredholm determinant of an integral operator with block integrable kernel constructed in terms of elementary parametrices. Its logarithmic derivatives with respect to parameters are given by contour integrals involving these parametrices and the solution of the Riemann-Hilbert problem. In the case of one circle, the tau function coincides with Widom's determinant arising in the asymptotics of block Toeplitz matrices. Our construction gives the Jimbo-Miwa-Ueno tau function for Riemann-Hilbert problems of isomonodromic origin (Painlev\'e VI, V, III, Garnier system, etc) and the Sato-Segal-Wilson tau function for integrable hierarchies such as Gelfand-Dickey and Drinfeld-Sokolov.Comment: 26 pages, 6 figure

    Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries

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    We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoOx). The copper nanofibers (CuNFs) were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide. Compared to bare CoOxthin-film (CoOxTF) electrodes, the CuNFs@CoOxelectrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate. Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network. Consequently, the CuNFs@CoOxcomposite structure demonstrated here can be used as a promising high-performance electrode for Li-ion batteries

    Ultrafast fluorescent decay induced by metal-mediated dipole-dipole interaction in two-dimensional molecular aggregates

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    Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly interacting dipole molecules self-assembled at close distance on an ordered lattice, is a fascinating fluorescent material. It is distinctively different from the single or colloidal dye molecules or quantum dots in most previous research. In this paper, we verify for the first time that when a 2DMA is placed at a nanometric distance from a metallic substrate, the strong and coherent interaction between the dipoles inside the 2DMA dominates its fluorescent decay at picosecond timescale. Our streak-camera lifetime measurement and interacting lattice-dipole calculation reveal that the metal-mediated dipole-dipole interaction shortens the fluorescent lifetime to about one half and increases the energy dissipation rate by ten times than expected from the noninteracting single-dipole picture. Our finding can enrich our understanding of nanoscale energy transfer in molecular excitonic systems and may designate a new direction for developing fast and efficient optoelectronic devices.Comment: 9 pages, 6 figure

    Changes in Cytokine Expression after Electroacupuncture in Neuropathic Rats

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    The production of proinflammatory cytokines including interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) plays a key role in chronic pain such as neuropathic pain. We investigated changes in cytokine expression in injured peripheral nerves and dorsal root ganglia (DRG) following electroacupuncture (EA) treatment. Neuropathic pain was induced by peripheral nerve injury to the left hind limb of Sprague-Dawley rats under pentobarbital anesthesia. Two weeks later, the nerve-injured rats were treated by EA for 10 minutes. The expression levels of IL-1β, IL-6, and TNF-α in peripheral nerves and DRG of neuropathic rats were significantly increased in nerve-injured rats. However, after EA, the cytokine expression levels were noticeably decreased in peripheral nerves and DRG. These results suggest that EA stimulation can reduce the levels of proinflamtory cytokines elevated after nerve injury

    Effects of a radiation dose reduction strategy for computed tomography in severely injured trauma patients in the emergency department: an observational study

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    <p>Abstract</p> <p>Background</p> <p>Severely injured trauma patients are exposed to clinically significant radiation doses from computed tomography (CT) imaging in the emergency department. Moreover, this radiation exposure is associated with an increased risk of cancer. The purpose of this study was to determine some effects of a radiation dose reduction strategy for CT in severely injured trauma patients in the emergency department.</p> <p>Methods</p> <p>We implemented the radiation dose reduction strategy in May 2009. A prospective observational study design was used to collect data from patients who met the inclusion criteria during this one year study (intervention group) from May 2009 to April 2010. The prospective data were compared with data collected retrospectively for one year prior to the implementation of the radiation dose reduction strategy (control group). By comparison of the cumulative effective dose and the number of CT examinations in the two groups, we evaluated effects of a radiation dose reduction strategy. All the patients met the institutional adult trauma team activation criteria. The radiation doses calculated by the CT scanner were converted to effective doses by multiplication by a conversion coefficient.</p> <p>Results</p> <p>A total of 118 patients were included in this study. Among them, 33 were admitted before May 2009 (control group), and 85 were admitted after May 2009 (intervention group). There were no significant differences between the two groups regarding baseline characteristics, such as injury severity and mortality. Additionally, there was no difference between the two groups in the mean number of total CT examinations per patient (4.8 vs. 4.5, respectively; p = 0.227). However, the mean effective dose of the total CT examinations per patient significantly decreased from 78.71 mSv to 29.50 mSv (p < 0.001).</p> <p>Conclusions</p> <p>The radiation dose reduction strategy for CT in severely injured trauma patients effectively decreased the cumulative effective dose of the total CT examinations in the emergency department. But not effectively decreased the number of CT examinations.</p

    Ultrafast fluorescent decay induced by metal-mediated dipole–dipole interaction in two-dimensional molecular aggregates

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    Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly interacting dipole molecules self-assembled at close distance on an ordered lattice, is a fascinating fluorescent material. It is distinctively different from the conventional (single or colloidal) dye molecules and quantum dots. In this paper, we verify that when a 2DMA is placed at a nanometric distance from a metallic substrate, the strong and coherent interaction between the dipoles inside the 2DMA dominates its fluorescent decay at a picosecond timescale. Our streak-camera lifetime measurement and interacting lattice–dipole calculation reveal that the metal-mediated dipole–dipole interaction shortens the fluorescent lifetime to about one-half and increases the energy dissipation rate by 10 times that expected from the noninteracting single-dipole picture. Our finding can enrich our understanding of nanoscale energy transfer in molecular excitonic systems and may designate a unique direction for developing fast and efficient optoelectronic devices. Keywords: molecular aggregate; fluorescence; nonradiative decay; dipole–dipole interaction; surface plasmonNational Science Foundation (U.S.) (Grant CMMI-1120724)United States. Air Force Office of Scientific Research (Award FA9550-12-1-0488
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