842 research outputs found

    The relationship between import and retail prices: a case study of fresh grapefruit in Japan

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    The study examined the relationship between import price and retail price of grapefruit in Japan. Estimated retail-import price relationship indicate asymmetry responses distributed over time. Import price changes are not fully transmitted to the retail level, with import price increases being passed on more fully than import price decreases.fresh grapefruit, Japan, import and retail price transmission, Demand and Price Analysis, International Relations/Trade,

    T- and L-type Ca 2+ currents in freshly dispersed smooth muscle cells from the human proximal urethra

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    The purpose of the present study was to characterise Ca 2+ currents in smooth muscle cells solated from biopsy samples taken from the proximal urethra of patients undergoing surgery for bladder or prostate cancer. Cells were studied at 37°C using the amphotericin B perforated-patch onfiguration of the patch-clamp technique. Currents were recorded using Cs + -rich pipette solutions to block K + currents. Two components of current, with electrophysiological and pharmacological properties typical of T- and L-type Ca 2+ currents, were present in these cells. When steady-state inactivation curves for the L current were fitted with a Boltzmann equation, this yielded a VÎ of _45 ± 5 mV. In contrast, the T current inactivated with a VÎ of _80 ± 3 mV. The L currents were reduced in a concentration-dependent manner by nifedipine (ED50 = 159 ± 54 nM) and Ni 2+ (ED50 = 65 ± 16 mM) but were enhanced when external Ca 2+ was substituted with Ba 2+ . The T current was little affected by TTX, reduction in external Na + , application of nifedipine at concentrations below 300 nM or substitution of external Ca 2+ with Ba 2+ , but was reduced by Ni 2+ with an ED50 of 6 ± 1 mM. When cells were stepped from _100 to _30 mV in Ca 2+ -free conditions, small inward currents could be detected. These were enhanced 40-fold in divalent-cation-free solution and blocked in a concentration-dependent manner by Mg 2+ with an ED50 of 32 ± 16 mM. These data support the idea that human urethral myocytes possess currents with electrophysiological and pharmacological properties typical of T- and L-type Ca 2+ currents

    Optical Sensing of SF6 Dissociation Levels in Electrical Discharges

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    Sulphur hexafluoride (SF6) is widely used as an insulating medium in high voltage systems including switchgear, transformers and transmission lines. If electrical breakdown occurs in SF6, a corona, glow or arc discharge forms, and this results in dissociation of SF6 molecules. However, if the SF6 gas is pure and the walls of the containing vessel are chemically inert, the products of dissociation tend preferentially to recombine at a rapid rate to reform SF6. If any chemical reaction with gas impurity or wall material occurs during or immediately following a discharge, recombination may be substantially reduced and the insulating efficiency of the high voltage system is degraded as a consequence of the loss of SF6. Invariably, it is the latter process that takes place, because of the presence of contaminants such as oxygen and water vapour

    Optical Sensing of the Corona Wind

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    The phenomenon variously known as the corona wind, electric wind or ionic wind was first reported by Francis Hauksbee, curator of instruments for the Royal Society of London, in 1709. ... Yet, despite the enormous growth of interest in the study of electricity and electrical-related phenomena from the 1800s and the attention of such notaries as Newton, Faraday and Maxwell, the corona wind remained essentially as a curio to be used at science fairs, until the last twenty years. Literature on the corona wind prior to the 1970s is scarce, and its potential applications were limited by the technology of the day. On the other hand, corona discharges have found applications in many fields of industry

    Relationships between Endogenous Plasma Biomarkers of Constitutive Cytochrome P450 3A Activity and Single-Time-Point Oral Midazolam Microdose Phenotype in Healthy Subjects

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    Due to high basal interindividual variation in cytochrome P450 3A (CYP3A) activity and susceptibility to drug interactions, there has been interest in the application of efficient probe drug phenotyping strategies, as well as endogenous biomarkers for assessment of in vivo CYP3A activity. The biomarkers 4β-hydroxycholesterol (4βHC) and 6β-hydroxycortisol (6βHCL) are sensitive to CYP3A induction and inhibition. However, their utility for the assessment of constitutive CYP3A activity remains uncertain. We investigated whether endogenous plasma biomarkers (4βHC and 6βHCL) are associated with basal CYP3A metabolic activity in healthy subjects assessed by a convenient single-time-point oral midazolam (MDZ) phenotyping strategy. Plasma 4βHC and 6βHCL metabolic ratios (MRs) were analysed in 51 healthy adult participants. CYP3A activity was determined after administration of an oral MDZ microdose (100 μg). Simple linear and multiple linear regression analyses were performed to assess relationships between MDZ oral clearance, biomarkers and subject covariates. Among study subjects, basal MDZ oral clearance, 4βHC and 6βHCL MRs ranged 6.5-, 10- and 13-fold, respectively. Participant age and alcohol consumption were negatively associated with MDZ oral clearance (p = 0.03 and p = 0.045, respectively), while weight and female sex were associated with lower plasma 4βHC MR (p = 0.0003 and p = 0.032, respectively). Neither 4βHC nor 6βHCL MRs were associated with MDZ oral clearance. Plasma 4βHC and 6βHCL MRs do not relate to MDZ single-time-point metabolic phenotype in the assessment of constitutive CYP3A activity among healthy individuals

    Calibrating the relation of low-frequency radio continuum to star formation rate at 1 kpc scale with LOFAR

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    9 figures, 6 tables and 17 pages. This paper is part of the LOFAR surveys data release 1 and has been accepted for publication in a special edition of A&A that will appear in Feb 2019, volume 622. The catalogues and images from the data release will be publicly available on lofar-surveys.org upon publication of the journal. Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO.Radio continuum (RC) emission in galaxies allows us to measure star formation rates (SFRs) unaffected by extinction due to dust, of which the low-frequency part is uncontaminated from thermal (free-free) emission. We calibrate the conversion from the spatially resolved 140 MHz RC emission to the SFR surface density (ΣSFR\Sigma_{\rm SFR}) at 1 kpc scale. We used recent observations of three galaxies (NGC 3184, 4736, and 5055) from the LOFAR Two-metre Sky Survey (LoTSS), and archival LOw-Frequency ARray (LOFAR) data of NGC 5194. Maps were created with the facet calibration technique and converted to radio ΣSFR\Sigma_{\rm SFR} maps using the Condon relation. We compared these maps with hybrid ΣSFR\Sigma_{\rm SFR} maps from a combination of GALEX far-ultraviolet and Spitzer 24 μm\mu\rm m data using plots tracing the relation at 1.2×1.21.2\times 1.2-kpc2^2 resolution. The RC emission is smoothed with respect to the hybrid ΣSFR\Sigma_{\rm SFR} owing to the transport of cosmic-ray electrons (CREs). This results in a sublinear relation (ΣSFR)RC[(ΣSFR)hyb]a(\Sigma_{\rm SFR})_{\rm RC} \propto [(\Sigma_{\rm SFR})_{\rm hyb}]^{a}, where a=0.59±0.13a=0.59\pm 0.13 (140 MHz) and a=0.75±0.10a=0.75\pm 0.10 (1365 MHz). Both relations have a scatter of σ=0.3 dex\sigma = 0.3~\rm dex. If we restrict ourselves to areas of young CREs (α>0.65\alpha > -0.65; IνναI_\nu \propto \nu^\alpha), the relation becomes almost linear at both frequencies with a0.9a\approx 0.9 and a reduced scatter of σ=0.2 dex\sigma = 0.2~\rm dex. We then simulate the effect of CRE transport by convolving the hybrid ΣSFR\Sigma_{\rm SFR} maps with a Gaussian kernel until the RC-SFR relation is linearised; CRE transport lengths are l=1l=1-5 kpc. Solving the CRE diffusion equation, we find diffusion coefficients of D=(0.13D=(0.13-1.5)×1028cm2s11.5) \times 10^{28} \rm cm^2\,s^{-1} at 1 GeV. A RC-SFR relation at 1.41.4 GHz can be exploited to measure SFRs at redshift z10z \approx 10 using 140140 MHz observations.Peer reviewe

    Quantitative phase contrast imaging of a shock-wave with a laser-plasma based X-ray source

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    X-ray phase contrast imaging (XPCI) is more sensitive to density variations than X-ray absorption radiography, which is a crucial advantage when imaging weakly-absorbing, low-Z materials, or steep density gradients in matter under extreme conditions. Here, we describe the application of a polychromatic X-ray laser-plasma source (duration ~0.5 ps, photon energy >1 keV) to the study of a laser-driven shock travelling in plastic material. The XPCI technique allows for a clear identification of the shock front as well as of small-scale features present during the interaction. Quantitative analysis of the compressed object is achieved using a density map reconstructed from the experimental data

    The Robinson Gravitational Wave Background Telescope (BICEP): a bolometric large angular scale CMB polarimeter

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    The Robinson Telescope (BICEP) is a ground-based millimeter-wave bolometric array designed to study the polarization of the cosmic microwave background radiation (CMB) and galactic foreground emission. Such measurements probe the energy scale of the inflationary epoch, tighten constraints on cosmological parameters, and verify our current understanding of CMB physics. Robinson consists of a 250-mm aperture refractive telescope that provides an instantaneous field-of-view of 17 degrees with angular resolution of 55 and 37 arcminutes at 100 GHz and 150 GHz, respectively. Forty-nine pair of polarization-sensitive bolometers are cooled to 250 mK using a 4He/3He/3He sorption fridge system, and coupled to incoming radiation via corrugated feed horns. The all-refractive optics is cooled to 4 K to minimize polarization systematics and instrument loading. The fully steerable 3-axis mount is capable of continuous boresight rotation or azimuth scanning at speeds up to 5 deg/s. Robinson has begun its first season of observation at the South Pole. Given the measured performance of the instrument along with the excellent observing environment, Robinson will measure the E-mode polarization with high sensitivity, and probe for the B-modes to unprecedented depths. In this paper we discuss aspects of the instrument design and their scientific motivations, scanning and operational strategies, and the results of initial testing and observations.Comment: 18 pages, 11 figures. To appear in Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III, Proceedings of SPIE, 6275, 200

    X-ray phase-contrast imaging for laser-induced shock waves

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    X-ray phase-contrast imaging (XPCI) is a versatile technique with applications in many fields, including fundamental physics, biology and medicine. Where X-ray absorption radiography requires high density ratios for effective imaging, the image contrast for XPCI is a function of the density gradient. In this letter, we apply XPCI to the study of laser-driven shock waves. Our experiment was conducted at the Petawatt High-Energy Laser for Heavy Ion EXperiments (PHELIX) at GSI. Two laser beams were used: one to launch a shock wave and the other to generate an X-ray source for phase-contrast imaging. Our results suggest that this technique is suitable for the study of warm dense matter (WDM), inertial confinement fusion (ICF) and laboratory astrophysics
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