3,789 research outputs found

    Observation of fractional quantum Hall effect in an InAs quantum well

    Full text link
    The two-dimensional electron system in an InAs quantum well has emerged as a prime candidate for hosting exotic quasi-particles with non-Abelian statistics such as Majorana fermions and parafermions. To attain its full promise, however, the electron system has to be clean enough to exhibit electron-electron interaction phenomena. Here we report the observation of fractional quantum Hall effect in a very low disorder InAs quantum well with a well-width of 24 nm, containing a two-dimensional electron system with a density n=7.8×1011n=7.8 \times 10^{11} cm2^{-2} and low-temperature mobility 1.8×1061.8 \times 10^6 cm2^2/Vs. At a temperature of 35\simeq35 mK and B24B\simeq24 T, we observe a deep minimum in the longitudinal resistance, accompanied by a nearly quantized Hall plateau at Landau level filling factor ν=4/3\nu=4/3

    Analysis of Lean Manufacturing: A Cost Saving Approach in Garments Production Unit

    Get PDF
    Sewing process is one of the most important stages in labor intensive ready-made clothing enterprises. Quality faults occurring during this process adversely affect the product quality and product efficiency, and also increase the production cost. The aim of this study is to investigate whether the knitwear production process is under control in a knitwear production enterprise and to detect the processes with highest rates of sewing faults in sewing department and finally to make suggestions for improving the quality control. Among the Statistical Process Control methods; control list, product control chart were used in the study. “Product control chart” was used to test whether the production process is controlled in the enterprise. Furthermore, the statistical methods were employed to determine the issues that need to be done in the improvement efforts and to detect the relations between the process groups supposedly effective on faults occurring in knitwear production and the amount of faults. Also, the processes with highest amounts of sewing faults and the effects of these processes on fault rates were investigated. As a result, it was concluded that the production process was statistically not under control in the ready-made clothing enterprise. In addition, this study demonstrated that the investigation of each process group by drawing their product control charts would make significant contributions to foresee the results and prepare more effective the improvement plans.

    Primordial Earth mantle heterogeneity caused by the Moon-forming giant impact

    Get PDF
    The giant impact hypothesis for Moon formation successfully explains the dynamic properties of the Earth–Moon system but remains challenged by the similarity of isotopic fingerprints of the terrestrial and lunar mantles. Moreover, recent geochemical evidence suggests that the Earth's mantle preserves ancient (or "primordial") heterogeneity that pre-dates the Moon-forming giant impact. Using a new hydrodynamical method, we here show that Moon-forming giant impacts lead to a stratified starting condition for the evolution of the terrestrial mantle. The upper layer of the Earth is compositionally similar to the disk, out of which the Moon evolves, whereas the lower layer preserves proto-Earth characteristics. As long as this predicted compositional stratification can at least partially be preserved over the subsequent billions of years of Earth mantle convection, a compositional similarity between the Moon and the accessible Earth's mantle is a natural outcome of realistic and high-probability Moon-forming impact scenarios. The preservation of primordial heterogeneity in the modern Earth not only reconciles geochemical constraints but is also consistent with recent geophysical observations. Furthermore, for significant preservation of a proto-Earth reservoir, the bulk major-element composition of the Earth–Moon system may be systematically shifted toward chondritic values

    Microjoule-level mid-infrared femtosecond pulse generation in hollow-core fibres

    Full text link
    We demonstrate a fibre-based approach that generates mid-infrared femtosecond pulses in the 3-4 {\mu}m spectral region with microjoule-level single pulse energy. This is realised in a piece of gas-filled antiresonant hollow-core fibre that is pumped by a two-micron light source. A rapid variation of the dispersion near a structural resonance of the fibre creates a phase-matching point in the mid-infrared, which mediates the frequency-down conversion. We generate femtosecond pulses centred at 3.16 {\mu}m wavelength with the pulse energy of more than 1 {\mu}J, achieving the conversion efficiency as high as 9.4%. The wavelength of the radiation is determined solely by the dielectric wall thickness of the cladding elements, while the yield is subject to other experimental parameters. This, combined with high power-handling capability of hollow-core fibres, makes it possible to power scale the mid-infrared output by either increasing the pulse energy or repetition rate of the pump. The technique presents a new pathway to build an all-fibre-based mid-infrared supercontinuum source, which promises to be a powerful new tool for ultrahigh sensitivity molecular spectroscopy

    Independent association of low serum 25-hydroxyvitamin d and 1,25-dihydroxyvitamin d levels with allcause and cardiovascular mortality. Arch Intern Med.

    Get PDF
    Background: In cross-sectional studies, low serum levels of 25-hydroxyvitamin D are associated with higher prevalence of cardiovascular risk factors and disease. This study aimed to determine whether endogenous 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels are related to all-cause and cardiovascular mortality
    corecore