283 research outputs found

    Partial Disorder in the Periodic Anderson Model on a Triangular Lattice

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    We report our theoretical results on the emergence of a partially-disordered state at zero temperature and its detailed nature in the periodic Anderson model on a triangular lattice at half filling. The partially-disordered state is characterized by coexistence of a collinear antiferromagnetic order on an unfrustrated honeycomb subnetwork and nonmagnetic state at the remaining sites. This state appears with opening a charge gap between a noncollinear antiferromagnetic metal and Kondo insulator while changing the hybridization and Coulomb repulsion. We also find a characteristic crossover in the low-energy excitation spectrum as a result of coexistence of magnetic order and nonmagnetic sites. The result demonstrates that the partially-disordered state is observed distinctly even in the absence of spin anisotropy, in marked contrast to the partial Kondo screening state found in the previous study for the Kondo lattice model.Comment: 4 pages, 4 figures, accepted for publication in J. Phys. Soc. Jp

    Optimum Arrangement of Resonator in Micro-bunch Free Electron Laser(III. Accelerator, Synchrotron Radiation, and Instrumentation)

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    Using a short-bunched beam of electrons from a linear accelator, the output of the micro-bunch FEL has been studied experimentally to clarify the optimum arrangement of an open resonator on the electron orbit. The output depends sharply on the arrangement, and the maximum output is observed when the resonator axis intersects the electron orbit with the angle of 3°

    Correcting for optical aberrations using multilayer displays

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    Optical aberrations of the human eye are currently corrected using eyeglasses, contact lenses, or surgery. We describe a fourth option: modifying the composition of displayed content such that the perceived image appears in focus, after passing through an eye with known optical defects. Prior approaches synthesize pre-filtered images by deconvolving the content by the point spread function of the aberrated eye. Such methods have not led to practical applications, due to severely reduced contrast and ringing artifacts. We address these limitations by introducing multilayer pre-filtering, implemented using stacks of semi-transparent, light-emitting layers. By optimizing the layer positions and the partition of spatial frequencies between layers, contrast is improved and ringing artifacts are eliminated. We assess design constraints for multilayer displays; autostereoscopic light field displays are identified as a preferred, thin form factor architecture, allowing synthetic layers to be displaced in response to viewer movement and refractive errors. We assess the benefits of multilayer pre-filtering versus prior light field pre-distortion methods, showing pre-filtering works within the constraints of current display resolutions. We conclude by analyzing benefits and limitations using a prototype multilayer LCD.National Science Foundation (U.S.) (Grant IIS-1116452)Alfred P. Sloan Foundation (Research Fellowship)United States. Defense Advanced Research Projects Agency (Young Faculty Award)Vodafone (Firm) (Wireless Innovation Award

    Photo-production of neutral kaons on 12C in the threshold region

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    Kaon photo-production process on 12^{12}C has been studied by measuring neutral kaons in a photon energy range of 0.8-1.1 GeV. Neutral kaons were identified by the invariant mass constructed from two charged pions emitted in the KS0π+πK^{0}_{S}\to\pi^{+}\pi^{-} decay channel. The differential cross sections as well as the integrated ones in the threshold photon energy region were obtained. The obtained momentum spectra were compared with a Spectator model calculation using elementary amplitudes of kaon photo-production given by recent isobar models. Present result provides, for the first time, the information on n(γ,K0)Λn(\gamma,K^{0})\Lambda reaction which is expected to play an important role to construct models for strangeness production by the electromagnetic interaction. Experimental results show that cross section of 12C(γ,K0)^{12}{\rm C}(\gamma,K^0) is of the same order to that of 12C(γ,K+)^{12}{\rm C}(\gamma,K^+) and suggest that slightly backward K0K^0 angular distribution is favored in the γnK0Λ\gamma n\to K^0\Lambda process.Comment: 6 pages, 8 figure

    Prevalence of equine piroplasmosis in Central Mongolia

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    Antigen for the indirect fluorescent antibody test (IFAT) was routinely prepared from infected erythrocytes from horses experimentally infected with Babesia equi and Babesia caballi. With the successful establishment of in vitro cultures of B. equi and B. caballi, it is now possible to employ culture- derived antigens in this test. In this study, in vitro-propagated B. equi- and B. caballi-infected erythrocytes were used as antigen in the IFAT. Various modifications to an established protocol had to be implemented to allow repeatable results. Cultures with 3-4% parasitized erythrocytes were found to be most suitable. As cross-reactions of control sera on heterologous antigen were observed at serum dilutions of up to 1/40, a reciprocal titre of 80 was considered to be positive. In positive samples, specific fluorescence of Babesia parasites and/or erythrocyte membranes was observed. Fifteen sera from Babesia-free horses from Japan all tested negative in the IFAT. One hundred and ten field-horse sera from Central Mongolia were investigated in this study. The results indicate that both B. equi and B. caballi are endemic in horses in Central Mongolia, with 88,2% and 84,5% of horses being seropositive to B. equi and B. caballi, respectively.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

    Development of Hydrophones for Detecting High-Energy Reactions in Water(III. Accelerator, Synchrotron Radiation, and Instrumentation)

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    Acoustic detectors were developed using a piezo ceramic compound PZT. A shape of the PZT detector was essential to obtain a high sensitivity. A detector of a spherically shaped shell structure, whose size was 50 mm in diameter and 2 mm thick, was fabricated. Its sensitivity was calibrated to be about 40 mV/Pa at 54 kHz. Using the hydrophone, acoustic signals generated by an electron-induced cascade shower in water were detected. Experimental results were compared with simulation data and confirmed a consistency in between

    Molecular Modeling Study for Inhibition Mechanism of Human Chymase and Its Application in Inhibitor Design

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    Human chymase catalyzes the hydrolysis of peptide bonds. Three chymase inhibitors with very similar chemical structures but highly different inhibitory profiles towards the hydrolase function of chymase were selected with the aim of elucidating the origin of disparities in their biological activities. As a substrate (angiotensin-I) bound crystal structure is not available, molecular docking was performed to dock the substrate into the active site. Molecular dynamics simulations of chymasecomplexes with inhibitors and substrate were performed to calculate the binding orientation of inhibitors and substrate as well as to characterize conformational changes in the active site. The results elucidate details of the 3D chymase structure as well as the importance of K40 in hydrolase function. Binding mode analysis showed that substitution of a heavier Cl atom at the phenyl ring of most active inhibitor produced a great deal of variation in its orientation causing the phosphinate group to interact strongly with residue K40. Dynamics simulations revealed the conformational variation in region of V36-F41upon substrate and inhibitor binding induced a shift in the location of K40 thus changing its interactions with them. Chymase complexes with the most activecompound and substrate were used for development of a hybrid pharmacophore model which was applied in databases screening. Finally, hits which bound well at the active site, exhibited key interactions and favorable electronic properties were identified as possible inhibitors for chymase. This study not only elucidates inhibitorymechanism of chymase inhibitors but also provides key structural insights which will aid in the rational design of novel potent inhibitors of the enzyme. In general, the strategy applied in the current study could be a promising computational approach and may be generally applicable to drug design for other enzymes
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