University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

Photopolymerizable nanocomposite photonic materials and their holographic applications in light and neutron optics

Abstract: We present an overview of recent investigations of photopolymerizable nanocomposite photonic materials in which, thanks to their high degree of material selectivity, recorded volume gratings possess high refractive index modulation amplitude and high mechanical/thermal stability at the same time, providing versatile applications in light and neutron optics. We discuss the mechanism of grating formation in holographically exposed nanocomposite materials, based on a model of the photopolymerization-driven mutual diffusion of monomer and nanoparticles. Experimental inspection of the recorded grating’s morphology by various physicochemical and optical methods is described. We then outline the holographic recording properties of volume gratings recorded in photopolymerizable nanocomposite materials consisting of inorganic/organic nanoparticles and monomers having various photopolymerization mechanisms. Finally, we show two examples of our holographic applications, holographic digital data storage and slow-neut...

Synthesis, Structure, Luminescent, and Magnetic Properties of Carbonato-Bridged ZnII2LnIII2 Complexes [(μ4-CO3)2{ZnIILnLnIII(NO3)}2] (LnIII = GdIII, TbIII, DyIII; L1 = N,N′-Bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L2 = N,N′-Bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato)

Abstract: Carbonato-bridged ZnII2LnIII2 complexes [(μ4-CO3)2{ZnIILnLnIII(NO3)}2]·solvent were synthesized through atmospheric CO2 fixation reaction of [ZnIILn(H2O)2]·xH2O, LnIII(NO3)3·6H2O, and triethylamine, where LnIII = GdIII, TbIII, DyIII; L1 = N,N′-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L2 = N,N′-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato. Each ZnII2LnIII2 structure possessing an inversion center can be described as two di-μ-phenoxo-bridged {ZnIILnLnIII(NO3)} binuclear units bridged by two carbonato CO32– ions. The ZnII ion has square pyramidal coordination geometry with N2O2 donor atoms of Ln and one oxygen atom of a bridging carbonato ion at the axial site. LnIII ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base Ln, two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9–300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic ...

Upper limits from the LIGO and TAMA detectors on the rate of gravitational-wave bursts

Abstract: We report on the first joint search for gravitational waves by the TAMA and LIGO collaborations. We looked for millisecond-duration unmodeled gravitational-wave bursts in 473 hr of coincident data collected during early 2003. No candidate signals were found. We set an upper limit of 0.12 events per day on the rate of detectable gravitational-wave bursts, at 90% confidence level. From software simulations, we estimate that our detector network was sensitive to bursts with root-sum-square strain amplitude above approximately 1–3×10-19 Hz-1/2 in the frequency band 700-2000 Hz. We describe the details of this collaborative search, with particular emphasis on its advantages and disadvantages compared to searches by LIGO and TAMA separately using the same data. Benefits include a lower background and longer observation time, at some cost in sensitivity and bandwidth. We also demonstrate techniques for performing coincidence searches with a heterogeneous network of detectors with different noise spectra and orientations. These techniques include using coordinated software signal injections to estimate the network sensitivity, and tuning the analysis to maximize the sensitivity and the livetime, subject to constraints on the background.

Time-resolved diffuse optical tomographic imaging for the provision of both anatomical and functional information about biological tissue

Abstract: We present in vivo images of near-infrared (NIR) diffuse optical tomography (DOT) of human lower legs and forearm to validate the dual functions of a time-resolved (TR) NIR DOT in clinical diagnosis, i.e., to provide anatomical and functional information simultaneously. The NIR DOT system is composed of time-correlated single-photon-counting channels, and the image reconstruction algorithm is based on the modified generalized pulsed spectral technique, which effectively incorporates the TR data with reasonable computation time. The reconstructed scattering images of both the lower legs and the forearm revealed their anatomies, in which the bones were clearly distinguished from the muscles. In the absorption images, some of the blood vessels were observable. In the functional imaging, a subject was requested to do handgripping exercise to stimulate physiological changes in the forearm tissue. The images of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentration changes in the forearm were obtained from the differential images of the absorption at three wavelengths between the exercise and the rest states, which were reconstructed with a differential imaging scheme. These images showed increases in both blood volume and oxyhemoglobin concentration in the arteries and simultaneously showed hypoxia in the corresponding muscles. All the results have demonstrated the capability of TR NIR DOT by reconstruction of the absolute images of the scattering and the absorption with a high spatial resolution that finally provided both the anatomical and functional information inside bulky biological tissues.