In the open range 1<p<q<∞, under a certain geometrical condition on weights, two-weight norm inequality for the product fractional integral operator, whose kernel has singularity appeared on each of ...the coordinate subspaces, is shown to follow from the Fefferman–Phong-type characteristic for the product cubes. This geometrical condition turns out to be the testing condition of Carleson-type embedding for product dyadic cubes.
Overview of the SACLA facility Yabashi, Makina; Tanaka, Hitoshi; Ishikawa, Tetsuya
Journal of synchrotron radiation,
20/May , Letnik:
22, Številka:
3
Journal Article
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In March 2012, SACLA started user operations of the first compact X‐ray free‐electron laser (XFEL) facility. SACLA has been routinely providing users with stable XFEL light over a wide photon energy ...range from 4 to 15 keV and an ultrafast pulse duration below 10 fs. The facility supports experimental activities in broad fields by offering high‐quality X‐ray optics and diagnostics, as well as reliable multiport charge‐coupled‐device detectors, with flexible experimental configurations. A two‐stage X‐ray focusing system was developed that enables the highest intensity of 1020 W cm−2. Key scientific results published in 2013 and 2014 in diverse fields are reviewed. The main experimental systems developed for these applications are summarized. A perspective on the facility upgrade is presented.
The free-electron laser, first proposed by Madey in 1971, has significantly reduced laser wavelengths to the vacuum ultraviolet and soft X-ray regions. Recently, an X-ray free-electron laser (XFEL) ...was operated at 1.2 Aa at the Linac Coherent Light Source (LCLS). Here, we report the successful generation of sub-angstrom laser light using a compact XFEL source, combining a short-period undulator with an 8 GeV electron beam. The shortest wavelength attained-0.634 Aa (63.4 pm)-is four orders of magnitude smaller than the 694 nm generated by Maiman's first laser. The maximum power exceeded 10 GW with a pulse duration of 10 super(-14) s. This achievement will contribute to the widespread use of XFEL sources and provide broad opportunities for exploring new fields in science.
Multiple‐beamline operation of SACLA Tono, Kensuke; Hara, Toru; Yabashi, Makina ...
Journal of synchrotron radiation,
March 2019, Letnik:
26, Številka:
2
Journal Article
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The SPring‐8 Ångstrom Compact free‐electron LAser (SACLA) began parallel operation of three beamlines (BL1–3) in autumn 2017 to increase the user beam time of the X‐ray free‐electron laser. The ...success of the multiple‐beamline operation is based on two technological achievements: (i) the fast switching operation of the SACLA main linear accelerator, which provides BL2 and BL3 with pulse‐by‐pulse electron beams, and (ii) the relocation and upgrade of the SPring‐8 Compact SASE Source for BL1, for the generation of a soft X‐ray free‐electron laser. Moreover, the photon beamlines and experimental stations were upgraded to facilitate concurrent user experiments at the three beamlines and accommodate more advanced experiments.
The parallel operation of three free‐electron laser (FEL) beamlines was first conducted using the SPring‐8 Ångstrom Compact free‐electron LAser (SACLA), to offer more opportunities for advanced studies using X‐ray FELs.
X-ray free-electron lasers (XFELs)1,2 are widely operated on the basis of self-amplified spontaneous emission (SASE)3,4, where spontaneous radiation from the electron beam is amplified along the ...magnetic field in undulators. Despite their high intensities, SASE-XFELs have a broad spectrum due to the stochastic starting-up process5. To narrow the bandwidth, self-seeding has been proposed6,7 and recently demonstrated8,9, where the seed pulse produced by monochromatizing the SASE-XFELs from the first section of undulators using a thin crystal in transmission geometry is amplified in the remaining undulators. Here, we present an efficient self-seeding scheme using the Bragg reflection to produce a seed pulse. We applied this scheme to SPring-8 Angstrom Compact free-electron LAser (SACLA)10, and produced nearly Fourier-transform-limited XFEL pulses that correspond to an increase in spectral brightness by a factor of six compared with SASE-XFELs. This achievement will not only enhance the throughput of present XFEL experiments but also should open new opportunities for X-ray science.A nearly Fourier-limited X-ray free-electron laser beam is generated by a self-seeding scheme. The beam in the first half of the undulators is monochromatized via Bragg reflection, and is subsequently amplified in the remaining undulators.
The action of the generalized fractional integral operators and the generalized fractional maximal operators is investigated in the framework of Morrey spaces. A typical property of the functions ...which belongs to Morrey spaces under pointwise multiplication by the generalized fractional integral operators and the generalized fractional maximal operators is established. The boundedness property of the fractional integral operators on the predual of Morrey spaces is shown as well. A counterexample concerning the Fefferman-Phong inequality is given by the use of the characteristic function of the Cantor set.
Aquatic insects having a high diversity are good biotic indicators for freshwater quality. Their larvae living in freshwater are sensitive to pesticides, and its impacts has been examined not only ...through laboratory toxicity studies using water and sediment exposure but also through higher-tier micro-/mesocosm studies and field monitoring. Many sophisticated statistical methods have been applied to assess the impacts of pesticides at levels from species to community, but their body burden has been studied much less, especially in relation to toxicity. We review the uptake, metabolism with relevant detoxifying enzymes, and depuration of pesticides in aquatic insect larvae, which determine their body burden and help to understand the toxicity profiles specific to each chemical class. We also discuss experimental conditions, environmental factors, and species sensitivity in relation to the bioconcentration/-accumulation and toxicity of pesticides.
This paper examines how intellectual property rights (IPR) protection affects innovation and foreign direct investment (FDI) using a North–South quality-ladder model incorporating the exogenous and ...costless imitation of technology and subsidy policies for both R&D and FDI. We show that for the interior steady state to be stable, either R&D or FDI subsidy rates must be positive. Our findings also indicate that strengthening IPR protection promotes both innovation and FDI. Moreover, a strengthening of IPR protection can also improve welfare if the initial IPR protection in the South is weak and the R&D subsidy rate is not too high.
•The purpose is to examine how intellectual property rights (IPR) protection affects innovation, foreign direct investment (FDI), and welfare analytically.•The model is a North–South quality-ladder model incorporating the exogenous imitation of technology and subsidy policies for both R&D and FDI.•For the interior steady state to be stable, either of the R&D or FDI subsidy rates must be positive.•Strengthening IPR protection promotes both innovation and FDI.•Strengthening IPR protection can improve welfare if initial IPR protection in the South is weak.
We determined the pulse duration of x-ray free electron laser light at 10 keV using highly resolved single-shot spectra, combined with an x-ray free electron laser simulation. Spectral profiles, ...which were measured with a spectrometer composed of an ultraprecisely figured elliptical mirror and an analyzer flat crystal of silicon (555), changed markedly when we varied the compression strength of the electron bunch. The analysis showed that the pulse durations were reduced from 31 to 4.5 fs for the strongest compression condition. The method, which is readily applicable to evaluate shorter pulse durations, provides a firm basis for the development of femtosecond to attosecond sciences in the x-ray region.
Turbulence related to flow oscillations near the seabed, in the wave bottom boundary layer (WBBL), is the phenomenon responsible for the suspension and transport of sediments. The vertical ...distribution of turbulent eddy viscosity within the WBBL is a key parameter that determines the vertical distribution of suspended sediments. For practical coastal engineering applications, the most used method to parameterize turbulence consists in specifying the shape of the one-dimensional-vertical (1DV) profile of eddy viscosity. Different empirical models have been proposed for the vertical variation of eddy viscosity in the WBBL. In this study, we consider the exponential-type profile, which was validated and calibrated by direct numerical simulation (DNS) and experimental data for turbulent channel and open-channel flows, respectively. This model is generalized to the WBBL, and the period-averaged eddy viscosity is calibrated by a two-equation baseline (BSL) k-ω model for different conditions. This model, together with a β-function (where β is the inverse of the turbulent Schmidt number), is used in modeling suspended sediment concentration (SSC) profiles over wave ripples, where field and laboratory measurements of SSC show two kinds of concentration profiles depending on grain particles size. Our study shows that the convection–diffusion equation, for SSC in WBBLs over sand ripples with an upward convection term, reverts to the classical advection–diffusion equation (ADE) with an “apparent” sediment diffusivity εs*=α εs related to the sediment diffusivity εs by an additional parameter α associated with the convective sediment entrainment process over sand ripples, which is defined by two equations. In the first, α depends on the relative importance of upward convection related to coherent vortex shedding and downward settling of sediments. When the convective transfer is very small, above low-steepness ripples, α≈1. In the second, α depends on the relative importance of coherent vortex shedding and random turbulence. When random turbulence is more important than coherent vortex shedding, α≈1, and “apparent” sediment diffusivity reverts to the classical sediment diffusivity εs*≈ εs. Comparisons with experimental data show that the proposed method allows a good description of both SSC for fine and coarse sand and “apparent” sediment diffusivity εs*.
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