Collective Properties of Low-lying Octupole Excitations in 82208Pb126^{208}_{82}Pb_{126}, 2060Ca40^{60}_{20}Ca_{40} and 828O20^{28}_{8}O_{20}

The octupole strengths of $\beta$-stable nucleus $^{208}_{82}Pb_{126}$, a neutron skin nucleus $^{60}_{20}Ca_{40}$ and a neutron drip line nucleus $^{28}_{8}O_{20}$ are studied by using the self-consistent Hartree-Fock calculation plus the random phase approximation (RPA) with Skyrme interaction. The collective properties of low-lying excitations are analyzed by using particle-vibration coupling. The results show that the lowest isoscalar states above threshold in $^{60}_{20}Ca_{40}$ and $^{28}_{8}O_{20}$ are the superpositions of collective excitations and unperturbed transitions from bound state to nonresonance states. For these three nuclei, both the low-lying isoscalar states and giant isoscalar resonance carry isovector strength. The ratio B(IV)/B(IS) is checked. It is found that, for $^{208}_{82}Pb_{126}$, the ratios are equal to $(\frac{N-Z}{A})^2$ in good accuracy, while for $^{60}_{20}Ca_{40}$ and $^{28}_{8}O_{20}$, the ratios are much larger than $(\frac{N-Z}{A})^2$. This results from the excess neutrons with small binding energies in $^{60}_{20}Ca_{40}$ and $^{28}_{8}O_{20}$.Comment: 14 pages, 10 figure

Ordered magnetic and quadrupolar states under hydrostatic pressure in orthorhombic PrCu2

We report magnetic susceptibility and electrical resistivity measurements on single-crystalline PrCu2 under hydrostatic pressure, up to 2 GPa, which pressure range covers the pressure-induced Van Vleck paramagnet-to-antiferromagnet transition at 1.2 GPa. The measured anisotropy in the susceptibility shows that in the pressure-induced magnetic state the ordered 4f-moments lie in the ac-plane. We propose that remarkable pressure effects on the susceptibility and resistivity are due to changes in the quadrupolar state of O22 and/or O20 under pressure. We present a simple analysis in terms of the singlet-singlet model.Comment: 14 pages, 9 figures submitted to Phys. Rev.

Violation of the Ikeda sum rule and the self-consistency in the renormalized quasiparticle random phase approximation and the nuclear double-beta decay

The effect of the inclusion of ground state correlations into the QRPA equation of motion for the two-neutrino double beta ($\beta\beta_{2\nu}$) decay is carefully analyzed. The resulting model, called renormalized QRPA (RQRPA), does not collapse near the physical value of the nuclear force strength in the particle-particle channel, as happens with the ordinary QRPA. Still, the $\beta\beta_{2\nu}$ transition amplitude is only slightly less sensitive on this parameter in the RQRPA than that in the plain QRPA. It is argued that this fact reveals once more that the characteristic behaviour of the $\beta\beta_{2\nu}$ transition amplitude within the QRPA is not an artifact of the model, but a consequence of the partial restoration of the spin-isospin $SU(4)$ symmetry. It is shown that the price paid for bypassing the collapse in the RQRPA is the violation of the Ikeda sum rule.Comment: 16 pages, latex, 3 postscript figure

Body mass index and health care utilization in diabetic and nondiabetic individuals.

BackgroundAlthough controversial, most studies examining the relationship of body mass index (BMI) with mortality in diabetes suggest a paradox: the lowest risk category is above normal weight, versus normal weight in nondiabetic persons. One proposed explanation is greater morbidity of diabetes in normal weight persons. If this were so, it would suggest a health care utilization paradox in diabetes, paralleling the mortality paradox, yet no studies have examined this issue.ObjectiveTo compare the relationship of BMI with health care utilization in diabetic versus nondiabetic persons.DesignPopulation-based cross-sectional study.SubjectsAdults in the 2000-2011 Medical Expenditures Panel Surveys (N=120,389).MeasuresTotal health care expenditures, hospital utilization (≥1 admission), and emergency department utilization (≥1 visit). BMI (kg/m) categories were: <20 (underweight); 20 to <25 (normal); 25 to <30 (overweight); 30 to <35 (obese); and ≥35 (severely obese). Adjustors were age, sex, race/ethnicity, income, health insurance, education, smoking, co-morbidity, urbanicity, region, and year.ResultsAmong diabetic persons, adjusted mean total health care expenditures were significantly lower in obese versus normal weight persons ($1314, 95$513-$2115; P=0.001). By contrast, among nondiabetic persons, total expenditures were nonsignificantly higher in obese versus normal weight persons (-$229, 95% CI, -$460 to$2; P=0.052). Findings for hospital and emergency department utilization exhibited similar patterns.ConclusionsNormal weight diabetic persons used substantially more health care than their overweight and obese counterparts, a difference not observed in nondiabetic persons. These differences support the plausibility of a BMI mortality paradox related to greater morbidity of diabetes in normal weight than in heavier persons

The zeta function on the critical line: Numerical evidence for moments and random matrix theory models

Results of extensive computations of moments of the Riemann zeta function on the critical line are presented. Calculated values are compared with predictions motivated by random matrix theory. The results can help in deciding between those and competing predictions. It is shown that for high moments and at large heights, the variability of moment values over adjacent intervals is substantial, even when those intervals are long, as long as a block containing 10^9 zeros near zero number 10^23. More than anything else, the variability illustrates the limits of what one can learn about the zeta function from numerical evidence. It is shown the rate of decline of extreme values of the moments is modelled relatively well by power laws. Also, some long range correlations in the values of the second moment, as well as asymptotic oscillations in the values of the shifted fourth moment, are found. The computations described here relied on several representations of the zeta function. The numerical comparison of their effectiveness that is presented is of independent interest, for future large scale computations.Comment: 31 pages, 10 figures, 19 table

Optimal Diversity in Investments with Recombinant Innovation

The notion of dynamic, endogenous diversity and its role in theories of investment and technological innovation is addressed. We develop a formal model of an innovation arising from the combination of two existing modules with the objective to optimize the net benefits of diversity. The model takes into account increasing returns to scale and the effect of different dimensions of diversity on the probability of emergence of a third option. We obtain analytical solutions describing the dynamic behaviour of the values of the options. Next diversity is optimized by trading off the benefits of recombinant innovation and returns to scale. We derive conditions for optimal diversity under different regimes of returns to scale. Threshold values of returns to scale and recombination probability define regions where either specialization or diversity is the best choice. In the time domain, when the investment time horizon is beyond a threshold value, a diversified investment becomes the best choice. This threshold will be larger the higher the returns to scale.

Valley-projected edge modes observed in underwater sonic crystals

Recently, the topological physics in acoustics has been attracting much attention. However, all the studies are aimed to elastic or airborne sound systems. Realizing topological insulators for underwater sound is of great importance, since water is another crucial sound medium in addition to solid and air. Here we report an experimental study on the valley-projected edge states for underwater sound. The edge states are directly observed in our ultrasound scanning experiments, together with a solid evidence for the valley-selective excitation. The experimental data agree well with our numerical results. Prospective applications can be anticipated, such as for underwater sound signal processing and ocean noise control.Comment: 5 figure