Deformation and weak decay of Lambda hypernuclei

We use the self-consistent mean-field theory to discuss the ground state and decay properties of $\Lambda$ hypernuclei. We first discuss the deformation of $\Lambda$ hypernuclei using the relativistic mean-field (RMF) approach. We show that, although most of hypernuclei have a similar deformation parameter to the core nucleus, the shape of $^{28}$Si is drastically altered, from oblately deformed to spherical, if a $\Lambda$ particle is added to this nucleus. We then discuss the pionic weak decay of neutron-rich $\Lambda$ hypernuclei using the Skyrme Hartree-Fock + BCS method. We show that, for a given isotope chain, the decay rate increases as a function of mass number, due to the strong neutron-proton interaction.Comment: A talk given at Sendai International Symposium on Strangeness Nuclear and Hadronic Systems (SENDAI08), Dec. 15-18, 2008, Sendai, Japa

Dense and Warm Molecular Gas between Double Nuclei of the Luminous Infrared Galaxy NGC 6240

High spatial resolution observations of the 12CO(1-0), HCN(1-0), HCO+(1-0), and 13CO(1-0) molecular lines toward the luminous infrared merger NGC 6240 have been performed using the Nobeyama Millimeter Array and the RAINBOW Interferometer. All of the observed molecular emission lines are concentrated in the region between the double nuclei of the galaxy. However, the distributions of both HCN and HCO+ emissions are more compact compared with that of 12CO, and they are not coincident with the star-forming regions. The HCN/12CO line intensity ratio is 0.25; this suggests that most of the molecular gas between the double nuclei is dense. A comparison of the observed high HCN/13CO intensity ratio, 5.9, with large velocity gradient calculations suggests that the molecular gas is dense [n(H_2)=10^{4-6} cm^-3] and warm (T_kin>50 K). The observed structure in NGC 6240 may be explained by time evolution of the molecular gas and star formation, which was induced by an almost head-on collision or very close encounter of the two galactic nuclei accompanied with the dense gas and star-forming regions.Comment: 25 pages, 8 figures, To be appeared in PASJ 57, No.4 (August 25, 2005) issu

Estimation of Regional Evapotranspiration Using Remotely Sensed Land Surface Temperature. Part 1: Measurement of Evapotranspiration at the Environmental Research Center and Determination of Priestley-taylor Parameter

In order to study the distribution of evapotranspiration in the humid region using remote sensing technology, the parameter (alpha) in the Priestley-Taylor model was determined. The daily means of the parameter alpha = 1.14 can be available from summer to autumn and alpha = to approximately 2.0 in winter. The results of the satellite and the airborne sensing done on 21st and 22nd January, 1983, are described. Using the vegetation distribution in the Tsukuba Academic New Town, as well as the radiation temperature obtained by remote sensing and the radiation data observed at the ground surface, the evapotranspiration was calculated for each vegetation type by the Priestley-Taylor method. The daily mean evapotranspiration on 22nd January, 1983, was approximately 0.4 mm/day. The differences in evapotranspiration between the vegetation types were not detectable, because the magnitude of evapotranspiration is very little in winter

Estimation of Regional Evapotranspiration Using Remotely Sensed Land Surface Temperature. Part 2: Application of Equilibrium Evaporation Model to Estimate Evapotranspiration by Remote Sensing Technique

In a humid region like Japan, it seems that the radiation term in the energy balance equation plays a more important role for evapotranspiration then does the vapor pressure difference between the surface and lower atmospheric boundary layer. A Priestley-Taylor type equation (equilibrium evaporation model) is used to estimate evapotranspiration. Net radiation, soil heat flux, and surface temperature data are obtained. Only temperature data obtained by remotely sensed techniques are used

Pump- and Probe-polarization Analyses of Ultrafast Carrier Dynamics in Organic Superconductors

We investigated photo-excited carrier relaxation dynamics in the strongly correlated organic superconductors kappa-(BEDT-TTF)(2)Cu(NCS)(2) and kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br, using different polarizations of pump and probe pulses. Below the glasslike transition temperature (T (g)) anisotropic responses for probe polarization were observed in both compounds. Decomposing the data into anisotropic and isotropic components, we found the anisotropic component shows no pump polarization dependence, meaning that dissipative excitation process was dominant for the anisotropic carrier relaxation. This behavior indicates that the appearance of anisotropic responses can be associated with spatial symmetry breaking due to structural change of BEDT-TTF molecules

Engineering transport by concatenated maps

We present a generalized kick rotor model in which the phase of the kick can vary from kick to kick. This additional freedom allows one to control the transport in phase space. For a specific choice of kick-to-kick phases, we predict novel forms of accelerator modes which are potentially of high relevance for future experimental studies

Nonlinear Cyclic Stress-Strain Relations of Soils

A cyclic torsional shear testing system was developed to measure the dynamic properties of soils at a wide range of strain levels (10-4 ~ 1%). Use of proximity transducer and pneumatic actuator in a closed loop system enabled us to measure the deformation at very small strains. A new simple nonlinear model of G/Gmax = 1/(α+γβ) agreed well with the test results of various geologic materials. In this model, parameter a represents the strain at which the stiffness starts to decrease, and parameter α controls the rate of the stiffness degradation. Loose sands had larger α and β, whereas clays and mudstones had smaller α and β. A unique relationship of β = 0.2logα + 0.3 was also found from the compiled data