Healing the Blind Goddess: Race and Criminal Justice

Once again, issues of race, ethnicity, and class within our criminal justice system have been thrust into the public spotlight. On both sides of the country, in our nation\u27s two largest cities, police are being called to account for acts of violence directed toward poor people of color. In New York City, a West African immigrant named Amadou Diallo was killed by four white police officers, who fired forty-one bullets at the unarmed man as he stood in the vestibule of his apartment building in a poor section of the Bronx. Did race influence the officers\u27 decisions to fire the fatal shots? Did the social class of Mr. Diallo or of the jury in Albany, to which the officers\u27 trials were transferred, influence the decision to acquit the officers? In Los Angeles, a former officer with the CRASH Unit of the Los Angeles Police Department\u27s Rampart Division has described, in excruciating detail, at least thirty police officers\u27 repeated misuses of their authority in an impoverished area of predominantly Latino immigrants. The scandal, which the Police Department itself conservatively estimates to implicate a staggering 120 cases, involved the shooting of unarmed people, conspiracies to put the innocent in jail, planting guns on suspects, and orchestrating the deportation of witnesses to police abuses. Could such massive and flagrant abuses of police power have festered for so long if they had instead transpired in a white, middle-class neighborhood

Inference with interference between units in an fMRI experiment of motor inhibition

An experimental unit is an opportunity to randomly apply or withhold a treatment. There is interference between units if the application of the treatment to one unit may also affect other units. In cognitive neuroscience, a common form of experiment presents a sequence of stimuli or requests for cognitive activity at random to each experimental subject and measures biological aspects of brain activity that follow these requests. Each subject is then many experimental units, and interference between units within an experimental subject is likely, in part because the stimuli follow one another quickly and in part because human subjects learn or become experienced or primed or bored as the experiment proceeds. We use a recent fMRI experiment concerned with the inhibition of motor activity to illustrate and further develop recently proposed methodology for inference in the presence of interference. A simulation evaluates the power of competing procedures.Comment: Published by Journal of the American Statistical Association at http://www.tandfonline.com/doi/full/10.1080/01621459.2012.655954 . R package cin (Causal Inference for Neuroscience) implementing the proposed method is freely available on CRAN at https://CRAN.R-project.org/package=ci

Conductivity of Metallic Si:B near the Metal-Insulator Transition: Comparison between Unstressed and Uniaxially Stressed Samples

The low-temperature dc conductivities of barely metallic samples of p-type Si:B are compared for a series of samples with different dopant concentrations, n, in the absence of stress (cubic symmetry), and for a single sample driven from the metallic into the insulating phase by uniaxial compression, S. For all values of temperature and stress, the conductivity of the stressed sample collapses onto a single universal scaling curve. The scaling fit indicates that the conductivity of si:B is proportional to the square-root of T in the critical range. Our data yield a critical conductivity exponent of 1.6, considerably larger than the value reported in earlier experiments where the transition was crossed by varying the dopant concentration. The larger exponent is based on data in a narrow range of stress near the critical value within which scaling holds. We show explicitly that the temperature dependences of the conductivity of stressed and unstressed Si:B are different, suggesting that a direct comparison of the critical behavior and critical exponents for stress- tuned and concentration-tuned transitions may not be warranted

The stability of a crystal with diamond structure for patchy particles with tetrahedral symmetry

The phase diagram of model anisotropic particles with four attractive patches in a tetrahedral arrangement has been computed at two different values for the range of the potential, with the aim of investigating the conditions under which a diamond crystal can be formed. We find that the diamond phase is never stable for our longer-ranged potential. At low temperatures and pressures, the fluid freezes into a body-centred-cubic solid that can be viewed as two interpenetrating diamond lattices with a weak interaction between the two sublattices. Upon compression, an orientationally ordered face-centred-cubic crystal becomes more stable than the body-centred-cubic crystal, and at higher temperatures a plastic face-centered-cubic phase is stabilized by the increased entropy due to orientational disorder. A similar phase diagram is found for the shorter-ranged potential, but at low temperatures and pressures, we also find a region over which the diamond phase is thermodynamically favored over the body-centred-cubic phase. The higher vibrational entropy of the diamond structure with respect to the body-centred-cubic solid explains why it is stable even though the enthalpy of the latter phase is lower. Some preliminary studies on the growth of the diamond structure starting from a crystal seed were performed. Even though the diamond phase is never thermodynamically stable for the longer-ranged model, direct coexistence simulations of the interface between the fluid and the body-centred-cubic crystal and between the fluid and the diamond crystal show that, at sufficiently low pressures, it is quite probable that in both cases the solid grows into a diamond crystal, albeit involving some defects. These results highlight the importance of kinetic effects in the formation of diamond crystals in systems of patchy particles.Comment: 15 pages, 13 figure

Prevalence of drooling, swallowing, and feeding problems in cerebral palsy across the lifespan: a systematic review and meta‐analyses

Aim: To determine the prevalence of drooling, swallowing, and feeding problems in persons with cerebral palsy (CP) across the lifespan. Method: A systematic review was conducted using five different databases (AMED, CINAHL, Embase, MEDLINE, and PubMed). The selection process was completed by two independent researchers and the methodological quality of included studies was assessed using the STROBE and AXIS guidelines. Meta-analyses were conducted to determine pooled prevalence estimates of drooling, swallowing, and feeding problems with stratified group analyses by type of assessment and Gross Motor Function Classification System level. Results: A total of 42 studies were included. Substantial variations in selected outcome measures and variables were observed, and data on adults were limited. Pooled prevalence estimates determined by meta-analyses were as high as 44.0% (95% confidence interval [CI] 35.6–52.7) for drooling, 50.4% (95% CI 36.0–64.8) for swallowing problems, and 53.5% (95% CI 40.7–65.9) for feeding problems. Group analyses for type of assessments were non-significant; however, more severely impaired functioning in CP was associated with concomitant problems of increased drooling, swallowing, and feeding. Interpretation: Drooling, swallowing, and feeding problems are very common in people with CP. Consequently, they experience increased risks of malnutrition and dehydration, aspiration pneumonia, and poor quality of life. What this paper adds: Drooling, swallowing, and feeding problems are very common in persons with cerebral palsy (CP). The prevalence of drooling, swallowing, and feeding problems is 44.0%, 50.4%, and 53.5% respectively. There are limited data on the prevalence of drooling, swallowing, and feeding problems in adults. Higher Gross Motor Function Classification System levels are associated with higher prevalence of drooling, swallowing, and feeding problems. There is increased risk for malnutrition, dehydration, aspiration pneumonia, and poor quality of life in CP

Microscopic and Macroscopic Signatures of Antiferromagnetic Domain Walls

Magnetotransport measurements on small single crystals of Cr, the elemental antiferromagnet, reveal the hysteretic thermodynamics of the domain structure. The temperature dependence of the transport coefficients is directly correlated with the real-space evolution of the domain configuration as recorded by x-ray microprobe imaging, revealing the effect of antiferromagnetic domain walls on electron transport. A single antiferromagnetic domain wall interface resistance is deduced to be of order $5\times10^{-5}\mathrm{\mu\Omega\cdot cm^{2}}$ at a temperature of 100 K.Comment: 3 color figure

The low-density/high-density liquid phase transition for model globular proteins

The effect of molecule size (excluded volume) and the range of interaction on the surface tension, phase diagram and nucleation properties of a model globular protein is investigated using a combinations of Monte Carlo simulations and finite temperature classical Density Functional Theory calculations. We use a parametrized potential that can vary smoothly from the standard Lennard-Jones interaction characteristic of simple fluids, to the ten Wolde-Frenkel model for the effective interaction of globular proteins in solution. We find that the large excluded volume characteristic of large macromolecules such as proteins is the dominant effect in determining the liquid-vapor surface tension and nucleation properties. The variation of the range of the potential only appears important in the case of small excluded volumes such as for simple fluids. The DFT calculations are then used to study homogeneous nucleation of the high-density phase from the low-density phase including the nucleation barriers, nucleation pathways and the rate. It is found that the nucleation barriers are typically only a few $k_{B}T$ and that the nucleation rates substantially higher than would be predicted by Classical Nucleation Theory.Comment: To appear in Langmui

Magnetic-Field-Induced Localization Transition in HgCdTe

We have performed magnetoresistance and Hall-resistance measurements on low-carrier-concentration n-type samples of Hg_(0.76)Cd_(0.24)Te at millikelvin temperatures. We observe an abrupt rise in the Hall resistance and magnetoresistance at a characteristic field H_c which is a significant function of temperature and which allows us to reject magnetic freezeout or localization by disorder as possible mechanisms. We believe our data provide compelling evidence for a model where the magnetic field induces localization of the electrons into a three-dimensional Wigner lattice

The Electron Glass in a Switchable Mirror: Relaxation, Aging and Universality

The rare earth hydride YH$_{3-\delta}$ can be tuned through the metal-insulator transition both by changing $\delta$ and by illumination with ultraviolet light. The transition is dominated by strong electron-electron interactions, with transport in the insulator sensitive to both a Coulomb gap and persistent quantum fluctuations. Via a systematic variation of UV illumination time, photon flux, Coulomb gap depth, and temperature, we demonstrate that polycrystalline YH$_{3-\delta}$ serves as a model system for studying the properties of the interacting electron glass. Prominent among its features are logarithmic relaxation, aging, and universal scaling of the conductivity

Electron correlation and disorder in Hg_(1-x)Cd_xTe in a magnetic field

We report both linear and nonlinear magnetoconductance measurements on two different density samples of similar stoichiometry Hg_(1-x)Cd_xTe for 0.01<T<2.5 K and 0<H<80 kOe. The critical magnetic field for driving the samples through the metal-insulator transition is proportional to temperature at low T and saturates at T∼2 K, in quantitative agreement with a theory for the melting of a Wigner crystal in magnetic field. In the insulating state, we observe a non-Ohmic I-V characteristic at threshold electric fields less than 1 mV/cm. By analogy to theories for charge-density-wave depinning, we estimate that the electrons are correlated over regions of a few hundred lattice spacings. Finally, we map out the phase boundary between the low-T–high-H electron solid and the high-T–low-H correlated fluid, explicitly demonstrating the necessity of millikelvin temperatures for studying the relative roles of disorder and Coulomb interactions in the electron solid