Sentencing Disparities in Yakima County: The Washington Sentencing Reform Act Revisited

This study expands upon an earlier exploration of sentencing disparity in the Yakima County, Washington judicial system. The Sentencing Reform Act was adopted in 1981, becoming effective in 1984, to end inequitable sentences imposed on individuals who are convicted of similar offenses. This work adds to the original study by including an investigation of exceptional sentences and offense type crime. Independent variables are defendants\u27 ethnicity (Hispanic, Native American, and White), age, and gender. The period of investigation includes fiscal years 1986 through 1991. Data was provided to the researchers by the Washington Sentencing Guidelines Commission and was processed using a difference of means test (ANOVA program). The findings suggest that sentencing disparity, while not being widespread, does persist nearly a decade after the Sentencing Reform Act was adopted. Hispanic defendants who had no prior criminal history were apt to receive disproportionately more severe sentences for similar crimes than Native Americans or whites

Data augmentation for models based on rejection sampling

We present a data augmentation scheme to perform Markov chain Monte Carlo inference for models where data generation involves a rejection sampling algorithm. Our idea, which seems to be missing in the literature, is a simple scheme to instantiate the rejected proposals preceding each data point. The resulting joint probability over observed and rejected variables can be much simpler than the marginal distribution over the observed variables, which often involves intractable integrals. We consider three problems, the first being the modeling of flow-cytometry measurements subject to truncation. The second is a Bayesian analysis of the matrix Langevin distribution on the Stiefel manifold, and the third, Bayesian inference for a nonparametric Gaussian process density model. The latter two are instances of problems where Markov chain Monte Carlo inference is doubly-intractable. Our experiments demonstrate superior performance over state-of-the-art sampling algorithms for such problems.Comment: 6 figures. arXiv admin note: text overlap with arXiv:1311.090

Microscopic Mechanism of the Helix-to-Layer Transformation in Elemental Group VI Solids

We study the conversion of bulk Se and Te, consisting of intertwined a helices, to structurally very dissimilar, atomically thin two-dimensional (2D) layers of these elements. Our ab initio calculations reveal that previously unknown and unusually stable \delta - and \eta-2D allotropes may form in an intriguing multi-step process that involves a concerted motion of many atoms at dislocation defects. We identify such a complex reaction path involving zipper-like motion of such dislocations that initiate structural changes. With low activation barriers <0.3 eV along the optimum path, the conversion process may occur at moderate temperatures. We find all one-dimensional (1D) and 2D chalcogen structures to be semiconducting.Comment: accepted by Nano Letter

Conformal Phase Transitions at Weak and Strong Coupling

D3 and D7-branes intersecting in 2+1 dimensions give rise at low energies to N=4 supersymmetric Yang-Mills theory coupled to defect fermions in the fundamental representation. This theory undergoes a BKT-type phase transition from a conformal phase to one in which the fermions acquire a non-zero mass when the 't Hooft coupling of the N=4 SYM exceeds a critical value. To study this transition, we continue the parameters of the model to a regime where a gravitational description is valid. We use it to calculate the masses of mesons and the phase diagram as a function of temperature and chemical potential. We also comment on the relation of our discussion to the transition from the non-abelian Coulomb phase to a confining one believed to occur in QCD at a critical number of flavors.Comment: 52 pages, harvmac; v2: references adde