Theoretical Study on Rotational Bands and Shape Coexistence of 183,185,187^{183,185,187}{Tl} in the Particle Triaxial-Rotor Model

By taking the particle triaxial-rotor model with variable moment of inertia, we investigate the energy spectra, the deformations and the single particle configurations of the nuclei $^{183,185,187}$Tl systemically. The calculated energy spectra agree with experimental data quite well. The obtained results indicate that the aligned bands observed in $^{183,185,187}$Tl originate from the $[530]{{1/2}}^{-}$, $[532]{{3/2}}^{-}$, $[660]{{1/2}}^{+}$ proton configuration coupled to a prolate deformed core, respectively. Whereas, the negative parity bands built upon the ${{9/2}}^{-}$ isomeric states in $^{183,185,187}$Tl are formed by a proton with the $[505]{{9/2}}^{-}$ configuration coupled to a core with triaxial oblate deformation, and the positive parity band on the ${{13/2}}^{+}$ isomeric state in $^{187}$Tl is generated by a proton with configuration $[606]{{13/2}}^{+}$ coupled to a triaxial oblate core.Comment: 16 pages, 5 figures. To appear in Physical Review

ECONOMIC EFFECTS OF U.S. DAIRY PROGRAMS

Based on econometric analysis, this article estimates effects of terminating the milk order system and milk price support, singly and together, over the period 1966-90. Since 1980, milk orders have raised the national blend price by 1-2%; price support has raised the blend price to well above the market clearing price, by over 21% in 1983. Short- and long-run benefits and costs are estimated for various policy options under 1990 conditions.Agricultural and Food Policy,

New insights into the Ds0∗(2317)D^{*}_{s0}(2317) and other charm scalar mesons

Through the scattering of light-pseudoscalar mesons ($\pi,K,\eta,\eta'$) off charmed mesons ($D, D_s$), we study the $D^{*}_{s0}(2317)$ state and other relevant charm scalar mesons in a unitarized chiral effective field theory approach. We investigate the charm scalar meson poles with different strangeness ($S$) and isospin ($I$) quantum numbers as well as their corresponding residues, which provide the coupling strengths of the charm scalar mesons. Both the light-quark mass and $N_C$ dependences of the pole positions of the $D^{*}_{s0}(2317)$ and the poles with $(S,I)=(0,1/2)$ are analyzed in detail in this work. Interestingly we observe quite similar pion mass trajectories for the resonance pole at around 2.1 GeV with $(S,I)=(0,1/2)$ to those of the $f_0(500)$ given in the literature. When increasing the values of $N_C$ we find that a bound state and a virtual state in the $(S,I)=(1,0)$ channel asymmetrically approach the $D K$ threshold for $N_C<6$, and they meet at this threshold at $N_C=6$. When $N_C>6$, the bound and virtual states move into the complex plane on the second Riemann sheet and become a symmetric pair of resonance poles. For large enough values of $N_C$, neither the $D^{*}_{s0}(2317)$ pole nor the poles with $(S,I)=(0,1/2)$ tend to fall down to the real axis, indicating that they do not behave like a standard quark-antiquark meson at large $N_C$.Comment: 26 pages, published version in PR

A pairwise maximum entropy model describes energy landscape for spiral wave dynamics of cardiac fibrillation

Heart is an electrically-connected network. Spiral wave dynamics of cardiac fibrillation shows chaotic and disintegrated patterns while sinus rhythm shows synchronized excitation patterns. To determine functional interactions between cardiomyocytes during complex fibrillation states, we applied a pairwise maximum entropy model (MEM) to the sequential electrical activity maps acquired from the 2D computational simulation of human atrial fibrillation. Then, we constructed energy landscape and estimated hierarchical structure among the different local minima (attractors) to explain the dynamic properties of cardiac fibrillation. Four types of the wave dynamics were considered: sinus rhythm; single stable rotor; single rotor with wavebreak; and multiple wavelet. The MEM could describe all types of wave dynamics (both accuracy and reliability>0.9) except the multiple random wavelet. Both of the sinus rhythm and the single stable rotor showed relatively high pairwise interaction coefficients among the cardiomyocytes. Also, the local energy minima had relatively large basins and high energy barrier, showing stable attractor properties. However, in the single rotor with wavebreak, there were relatively low pairwise interaction coefficients and a similar number of the local minima separated by a relatively low energy barrier compared with the single stable rotor case. The energy landscape of the multiple wavelet consisted of a large number of the local minima separated by a relatively low energy barrier, showing unstable dynamics. These results indicate that the MEM provides information about local and global coherence among the cardiomyocytes beyond the simple structural connectivity. Energy landscape analysis can explain stability and transitional properties of complex dynamics of cardiac fibrillation, which might be determined by the presence of 'driver' such as sinus node or rotor.Comment: Presented at the 62nd Biophysical Society Annual Meeting, San Francisco, California, 201

The Thermal Memory of Reionization History

The recent measurement by WMAP of a large electron scattering optical depth tau_e = 0.17 +- 0.04 is consistent with a simple model of reionization in which the intergalactic medium (IGM) is ionized at redshift z ~ 15, and remains highly ionized thereafter. Here, we show that existing measurements of the IGM temperature from the Lyman-alpha forest at z ~ 2 - 4 rule out this ``vanilla'' model. Under reasonable assumptions about the ionizing spectrum, as long as the universe is reionized before z = 10, and remains highly ionized thereafter, the IGM reaches an asymptotic thermal state which is too cold compared to observations. To simultaneously satisfy the CMB and forest constraints, the reionization history must be complex: reionization begins early at z >~ 15, but there must have been significant (order unity) changes in fractions of neutral hydrogen and/or helium at 6 < z < 10, and/or singly ionized helium at 4 < z < 10. We describe a physically motivated reionization model that satisfies all current observations. We also explore the impact of a stochastic reionization history and show that a late epoch of (HeII --> HeIII) reionization induces a significant scatter in the IGM temperature, but the scatter diminishes with time quickly. Finally, we provide an analytic formula for the thermal asymptote, and discuss possible additional heating mechanisms that might evade our constraints.Comment: 10 pages, submitted to ApJ, new references, additional discussion on earlier work and partial HeII reionizatio

The Low Column Density Lyman-alpha Forest

We develop an analytical method based on the lognormal approximation to compute the column density distribution of the Lyman-alpha forest in the low column density limit. We compute the column density distributions for six different cosmological models and found that the standard, COBE-normalized CDM model cannot fit the observations of the Lyman-alpha forest at z=3. The amplitude of the fluctuations in that model has to be lowered by a factor of almost 3 to match observations. However, the currently viable cosmological models like the lightly tilted COBE-normalized CDM+Lambda model, the CHDM model with 20% neutrinos, and the low-amplitude Standard CDM model are all in agreement with observations, to within the accuracy of our approximation, for the value of the cosmological baryon density at or higher than the old Standard Bing Bang Nucleosynthesis value of 0.0125 for the currently favored value of the ionizing radiation intensity. With the low value for the baryon density inferred by Hogan & Rugers (1996), the models can only marginally match observations.Comment: three postscript figures included, submitted to ApJ

Residual proton-neutron interactions and the NpNnN_{\rm p} N_{\rm n} scheme

We investigate the correlation between integrated proton-neutron interactions obtained by using the up-to-date experimental data of binding energies and the $N_{\rm p} N_{\rm n}$, the product of valence proton number and valence neutron number with respect to the nearest doubly closed nucleus. We make corrections on a previously suggested formula for the integrated proton-neutron interaction. Our results demonstrate a nice, nearly linear, correlation between the integrated p-n interaction and $N_{\rm p} N_{\rm n}$, which provides us with a firm foundation of the applicability of the $N_{\rm p} N_{\rm n}$ scheme to nuclei far from the stability line.Comment: four pages, three figures, Physical Review C, in pres

Superfluidity in Three-species Mixture of Fermi Gases across Feshbach Resonances

In this letter a generalization of the BEC-BCS crossover theory to a multicomponent superfluid is presented by studying a three-species mixture of Fermi gas across two Feshbach resonances. At the BEC side of resonances, two kinds of molecules are stable which gives rise to a two-component Bose condensate. This two-component superfluid state can be experimentally identified from the radio-frequency spectroscopy, density profile and short noise measurements. As approaching the BCS side of resonances, the superfluidity will break down at some point and yield a first-order quantum phase transition to normal state, due to the mismatch of three Fermi surfaces. Phase separation instability will occur around the critical regime.Comment: 4 pages, 3 figures, revised versio

The Potential for Wind Energy Meeting Electricity Needs on Vancouver Island

In this paper, an in-depth analysis of power supply and demand on Vancouver Island is used to provide information about the optimal allocation of power across ‘generating’ sources and to investigate the economics of wind generation and penetrability into the Island grid. The methodology developed can be extended to a region much larger than Vancouver Island. Results from the model indicate that Vancouver Island could experience blackouts in the near future unless greater name-plate capacity is developed. While wind-generated energy has the ability to contribute to the Island’s power needs, the problem with wind power is its intermittency. The results indicate that wind power may not be able to prevent shortfalls, regardless of the overall name-plate capacity of the wind turbines. Further, costs of reducing CO2 emissions using wind power are unacceptably large, perhaps more than $100 per t CO2, although this might be attributable to the mix of power sources making up the Island’s grid.Economics of wind power, grid system modeling, operations research