Fluid Coexistence close to Criticality: Scaling Algorithms for Precise Simulation

A novel algorithm is presented that yields precise estimates of coexisting liquid and gas densities, $\rho^{\pm}(T)$, from grand canonical Monte Carlo simulations of model fluids near criticality. The algorithm utilizes data for the isothermal minima of the moment ratio $Q_{L}(T;_{L})$ $\equiv< m^{2}>_{L}^{2}/_{L}$ in $L$$\times$$...$$\times$$L$ boxes, where $m=\rho-_{L}$. When $L$$\to$$\infty$ the minima, $Q_{\scriptsize m}^{\pm}(T;L)$, tend to zero while their locations, $\rho_{\scriptsize m}^{\pm}(T;L)$, approach $\rho^{+}(T)$ and $\rho^{-}(T)$. Finite-size scaling relates the ratio {\boldmath $\mathcal Y$}$=$$(\rho_{\scriptsize m}^{+}-\rho_{\scriptsize m}^{-})/\Delta\rho_{\infty}(T)$ {\em universally} to ${1/2}(Q_{\scriptsize m}^{+}+Q_{\scriptsize m}^{-})$, where $\Delta\rho_{\infty}$$=$$\rho^{+}(T)-\rho^{-}(T)$ is the desired width of the coexistence curve. Utilizing the exact limiting $(L$$\to$$\infty)$ form, the corresponding scaling function can be generated in recursive steps by fitting overlapping data for three or more box sizes, $L_{1}$, $L_{2}$, $...$, $L_{n}$. Starting at a $T_{0}$ sufficiently far below $T_{\scriptsize c}$ and suitably choosing intervals $\Delta T_{j}$$=$$T_{j+1}-T_{j}$$>$0 yields $\Delta\rho_{\infty}(T_{j})$ and precisely locates $T_{\scriptsize c}$

Universality of Ionic Criticality: Size- and Charge-Asymmetric Electrolytes

Grand canonical simulations designed to resolve critical universality classes are reported for $z$:1 hard-core electrolyte models with diameter ratios $\lambda {=} a_+/a_- {\lesssim} 6$. For $z {=} 1$ Ising-type behavior prevails. Unbiased estimates of $T_c(\lambda)$ are within 1% of previous (biased) estimates but the critical densities are $\sim$5 % lower. Ising character is also established for the 2:1 and 3:1 equisized models, along with critical amplitudes and improved $T_c$ estimates. For $z {=} 3$, however, strong finite-size effects reduce the confidence level although classical and O$(n {\geq} 3)$ criticality are excluded.Comment: 4 pages, 3 figure

Reply to Comment on ``Determination of pion-baryon coupling constants from QCD sum rules''

In response to Kim's comment (nucl-th/9903040) on the sum rules for pion-baryon coupling constants obtained in hep-ph/9512259 and hep-ph/9606471, we point out that our treatment of the continuum is consistent with duality and with the fact that the correlator in the presence of an external meson or field should be represented by a double dispersion relation.Comment: 5 pages (RevTeX), reply to nucl-th/990304

Hadronic decay of a vector meson from the lattice

We explore the decay of a vector meson to two pseudoscalar mesons on the lattice with $N_f=2$ flavours of sea quark. Although we are working with quark masses that do not allow a physical decay, we show how the transition rate can be evaluated from the amplitude for $\rho \to \pi \pi$ and from the annihilation component of $\pi \pi \to \pi \pi$. We explore the decay amplitude for two different pion momenta and find consistent results. The coupling strength we find is in agreement with experiment. We also find evidence for a shift in the $\rho$ mass caused by mixing with two pion states.Comment: 13 pages, version as accepted for Physics Letters

Surface Waves on a Semi-toroidal Water Ring

We study the dynamics of surface waves on a semi-toroidal ring of water that is excited by vertical vibration. We create this specific fluid volume by patterning a glass plate with a hydrophobic coating, which confines the fluid to a precise geometric region. To excite the system, the supporting plate is vibrated up and down, thus accelerating and decelerating the fluid ring along its toroidal axis. When the driving acceleration is sufficiently high, the surface develops a standing wave, and at yet larger accelerations, a traveling wave emerges. We also explore frequency dependencies and other geometric shapes of confinement

Tumor Biology and Racial Disparities in Reconstruction After Mastectomy: A SEER Database Analysis

Introduction: Significant disparities in immediate breast reconstruction after mastectomy have persisted, and may even be increasing, despite large-scale efforts to minimize them, such as the Women’s Health and Cancer Rights Act of 1998. Immediate breast reconstruction has been shown to lead to higher rates of surgical satisfaction, minimize delay in post-operative cancer treatment, and improve the quality of life and overall well-being of mastectomy patients. However only 25-40% of eligible women in the United States receive reconstruction. The rate of reconstruction is even lower in African American and Hispanic women compared to White women. To better understand this disparity, this study uses national population-based data to examine how demographic factors, socioeconomic factors, and disease characteristics interact and affect the rate of immediate breast reconstruction (IBR) after mastectomy. Methods: Women with AJCC7 Stage 0-III breast cancer who underwent mastectomy from 2010 to 2012 were identified in the Surveillance, Epidemiology and End Results Program (SEER) database. Race, Hispanic ethnicity, age, marital status, insurance status, tumor grade, AJCC7 stage and hormone receptor/ Her2Neu profile were compared between women undergoing mastectomy with IBR and mastectomy alone using univariate and multivariate analysis. Results: We identified 51,115 women who underwent mastectomy for Stage 0-III breast cancer from 2010-2012, of whom 15,389 (30.1%) received IBR. On multivariate analysis, age (p Conclusion: The decision to undergo reconstruction after mastectomy is influenced by many factors. Our results show that even after adjusting for tumor characteristics, socioeconomic factors are independently associated with receiving IBR after mastectomy. Further research is needed to elucidate the factors that influence the decision to undergo IBR in order to eliminate these persistent disparities