Racial Segregation as a Social Determinant of Health: Evidence from the State of Georgia

Background: Despite decades of research, determining the causes of racial disparities in health remains a pernicious problem in the public health arena. Challenges include further refining definitions of health as well as expanding frameworks for social determinants of health to include relevant and related predictors. Racial segregation as a social determinant of health is understudied but of growing interest in the discourse on health disparities. This paper explores empirically the relationship between racial segregation and other predictors of social determinants of health and their collective impact on health outcomes defined in both objective and subjective terms. Methods: Ordinary least squares regression analysis was used to analyze health outcomes from the Robert Wood Johnson 2018 County Health Rankings for Georgia. At the county level we considered two distinct categories of health outcomes as the dependent variables, including objective measures of health status such as age-adjusted mortality and more subjective measures from the person’s perspective of quality of life such self-reported health. The independent variables representing racial segregation included the black-white segregation and non-white-white segregation indices. Results: Our findings are that racial segregation is not significantly associated with objective health outcome measures. Conversely and surprisingly, counties with higher levels of black-white and nonwhite-white segregation show better self-reported health. Control variables have the expected impact on health outcomes based on previous literature. Conclusions: While segregation does not suggest poorer health status, the findings of higher quality of life assessment is concerning as a person’s perspectives on their health predicts healthy behaviors and access to needed care. We suggest that racial segregation is an important addition to social determinants of health frameworks and models and worthy of continued multidisciplinary research on a national basis

Star cluster evolution in the Magellanic Clouds revisited

The evolution of star clusters in the Magellanic Clouds has been the subject of significant recent controversy, particularly regarding the importance and length of the earliest, largely mass-independent disruption phase (referred to as “infant mortality”). Here, we take a fresh approach to the problem, using a large, independent, and homogeneous data set of UBVR imaging observations, from which we obtain the cluster age and mass distributions in both the Large and Small Magellanic Clouds (LMC, SMC) in a self-consistent manner. We conclude that the (optically selected) SMC star cluster population has undergone at most ~30% (1σ) infant mortality between the age range from about 3–10 Myr, to that of approximately 40–160 Myr. We rule out a 90% cluster mortality rate per decade of age (for the full age range up to 109 yr) at a > 6σ level. Using a simple approach, we derive a “characteristic” cluster disruption time-scale for the cluster population in the LMC that implies that we are observing the initial cluster mass function (CMF). Preliminary results suggest that the LMC cluster population may be affected by <10% infant mortality

Nuclear spin ferromagnetic phase transition in an interacting 2D electron gas

Electrons in a two-dimensional semiconducting heterostructure interact with nuclear spins via the hyperfine interaction. Using a a Kondo lattice formulation of the electron-nuclear spin interaction, we show that the nuclear spin system within an interacting two-dimensional electron gas undergoes a ferromagnetic phase transition at finite temperatures. We find that electron-electron interactions and non-Fermi liquid behavior substantially enhance the nuclear spin Curie temperature into the $mK$ range with decreasing electron density.Comment: 4.1 page

Three-Species Diffusion-Limited Reaction with Continuous Density-Decay Exponents

We introduce a model of three-species two-particle diffusion-limited reactions A+B -> A or B, B+C -> B or C, and C+A -> C or A, with three persistence parameters (survival probabilities in reaction) of the hopping particle. We consider isotropic and anisotropic diffusion (hopping with a drift) in 1d. We find that the particle density decays as a power-law for certain choices of the persistence parameter values. In the anisotropic case, on one symmetric line in the parameter space, the decay exponent is monotonically varying between the values close to 1/3 and 1/2. On another, less symmetric line, the exponent is constant. For most parameter values, the density does not follow a power-law. We also calculated various characteristic exponents for the distance of nearest particles and domain structure. Our results support the recently proposed possibility that 1d diffusion-limited reactions with a drift do not fall within a limited number of distinct universality classes.Comment: 12 pages in plain LaTeX and four Postscript files with figure

The near-IR Mbh-L and Mbh-n relations

We present near-infrared (near-IR) surface photometry (2D profiling) for a sample of 29 nearby galaxies for which supermassive black hole (SMBH) masses are constrained. The data are derived from the UKIDSS-LAS representing a significant improvement in image quality and depth over previous studies based on Two Micron All Sky Survey data. We derive the spheroid luminosity and spheroid Sérsic index for each galaxy with galfit3 and use these data to construct SMBH mass-bulge luminosity (Mbh-L) and SMBH-Sérsic index (Mbh-n) relations. The best-fitting K-band relation for elliptical and disc galaxies is log (Mbh/M⊙) =−0.36(±0.03)(MK+ 18) + 6.17(±0.16), with an intrinsic scatter of 0.4+0.09−0.06 dex, whilst for elliptical galaxies we find log (Mbh/M⊙) =−0.42(±0.06)(MK+ 22) + 7.5(±0.15), with an intrinsic scatter of 0.31+0.087−0.047 dex. Our revised Mbh-L relation agrees closely with the previous near-IR constraint by Graham. The lack of improvement in the intrinsic scatter in moving to higher quality near-IR data suggests that the SMBH relations are not currently limited by the quality of the imaging data but is either intrinsic or a result of uncertainty in the precise number of required components required in the profiling process. Contrary to expectation, a relation between SMBH mass and the Sérsic index was not found at near-IR wavelengths. This latter outcome is believed to be explained by the generic inconsistencies between 1D and 2D galaxy profiling which are currently under further investigatio

Performance characterisation of a new photo-microsensor based sensing head for displacement measurement

This paper presents a robust displacement sensor with nanometre-scale resolution over a micrometre range. It is composed of low cost commercially available slotted photo-microsensors (SPMs). The displacement sensor is designed with a particular arrangement of a compact array of SPMs with specially designed shutter assembly and signal processing to significantly reduce sensitivity to ambient light, input voltage variation, circuit electronics drift, etc. The sensor principle and the characterisation results are described in this paper. The proposed prototype sensor has a linear measurement range of 20 μm and resolution of 21 nm. This kind of sensor has several potential applications, including mechanical structural deformation monitoring system

Coupled Minimal Models with and without Disorder

We analyse in this article the critical behavior of $M$ $q_1$-state Potts models coupled to $N$ $q_2$-state Potts models ($q_1,q_2\in [2..4]$) with and without disorder. The technics we use are based on perturbed conformal theories. Calculations have been performed at two loops. We already find some interesting situations in the pure case for some peculiar values of $M$ and $N$ with new tricritical points. When adding weak disorder, the results we obtain tend to show that disorder makes the models decouple. Therefore, no relations emerges, at a perturbation level, between for example the disordered $q_1\times q_2$-state Potts model and the two disordered $q_1,q_2$-state Potts models ($q_1\ne q_2$), despite their central charges are similar according to recent numerical investigations.Comment: 45 pages, Latex, 3 PS figure