Some thoughts of the future health of the South African Bantu

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Combinatorial Alexander Duality -- a Short and Elementary Proof

Let X be a simplicial complex with the ground set V. Define its Alexander dual as a simplicial complex X* = {A \subset V: V \setminus A \notin X}. The combinatorial Alexander duality states that the i-th reduced homology group of X is isomorphic to the (|V|-i-3)-th reduced cohomology group of X* (over a given commutative ring R). We give a self-contained proof.Comment: 7 pages, 2 figure; v3: the sign function was simplifie

Memorandum: what can be done to avoid coronary heart disease?

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Biological and disease patterns in South African inter-racial populations as modified by rise in privilege

Among the 4 ethnic groups in South Africa. populations may be observed in many stages of transition, from primitiveness to sopnistication. With the rise in socioeconomic circumstances, numerous changes have occurred. Those discussed include mortality rate and age structure, diet, growth, blood pressure, various biochemical measurements, physical activity, and disease pattern. The trend of changes implies that in the future, among non-Whites, diseases of nutritional inadequacy, especially protein-calorie malnutrition and pellagra, will decrease and will no longer be public health burdens. Simultaneously, however, there will be increases in conditions or diseases linked with nutritional excess, such as overweight and hypertension. In non-Whites, these and their ramifications are likely in t;me to exact the high tolls of mortality and morbidity from degenerative diseases which prevail in White populations. It is unlikely that recommendations directed at Whites and the affluent moieties of non-Whites will arrest the rising intensity of risk factors to health

Simulations of Oligomeric Intermediates in Prion Diseases

We extend our previous stochastic cellular automata based model for areal aggregation of prion proteins on neuronal surfaces. The new anisotropic model allow us to simulate both strong beta-sheet and weaker attachment bonds between proteins. Constraining binding directions allows us to generate aggregate structures with the hexagonal lattice symmetry found in recently observed in vitro experiments. We argue that these constraints on rules may correspond to underlying steric constraints on the aggregation process. We find that monomer dominated growth of the areal aggregate is too slow to account for some observed doubling time-to-incubation time ratios inferred from data, and so consider aggregation dominated by relatively stable but non-infectious oligomeric intermediates. We compare a kinetic theory analysis of oligomeric aggregation to spatially explicit simulations of the process. We find that with suitable rules for misfolding of oligomers, possibly due to water exclusion by the surrounding aggregate, the resulting oligomeric aggregation model maps onto our previous monomer aggregation model. Therefore it can produce some of the same attractive features for the description of prion incubation time data. We propose experiments to test the oligomeric aggregation model.Comment: 8 pages, 10 figures For larger versions of several figures, see http://asaph.ucdavis.edu/~dmobley and click on the prion paper lin

The genetic basis of thyroid function: Novel findings and new approaches

Context: Genetic factors are major determinants of thyroid function. Over the last two decades,multiple genetic variants have been associated with variations in normal range thyroid functiontests. Most recently, a large-scale genome-wide association study (GWAS) doubled the number ofknown variants associated with normal range thyrotropin (TSH) and free thyroxine (FT4) levels.Evidence Acquisition: This review summarizes the results of genetic association studies onnormal range thyroid function and explores how these genetic variants can be used in futurestudies to improve our understanding of thyroid hormone regulation and disease.Evidence Synthesis: Serum TSH and FT4 levels are determined by multiple genetic variantson virtually all levels of the hypothalamus-pituitary-thyroid (HPT) axis. Functional followup studies on top of GWAS hits has the potential to discover new key players in thyroidhormone regulation, as exemplified by the identification of the thyroid hormone transporterSLC17A4 and the metabolizing enzyme AADAT. Translational studies may use these geneticvariants to investigate causal associations between thyroid function and various outcomes inMendelian Randomization (MR) studies, to identify individuals with an increased risk of thyroiddysfunction, and to predict the individual HPT axis setpoint.Conclusions: Recent genetic studies have greatl

Influence of the on-time on the ozone production in pulsed dielectric barrier discharges

Understanding the production mechanisms of ozone and other reactive species in atmospheric pressure dielectric barrier discharges (DBDs) has become increasingly important for the optimization and commercial success of these plasma devices in emerging applications, such as plasma medicine, plasma agriculture, and plasma catalysis. In many of these applications, input power modulation is exploited as a means to maintain a low gas temperature. Although the chemical pathways leading to ozone production/destruction and their strong temperature dependence are relatively well understood, the effect of the on-time duration on the performance of these modulated DBDs remains largely unexplored. In this study, we use electrical and optical diagnostics, as well as computational methods, to assess the performance of a modulated DBD device. The well-established Lissajous method for measuring the power delivered to the discharge is not suitable for modulated DBDs because the transients generated at the beginning of each pulse become increasingly important in short on-time modulated plasmas. It is shown that for the same input power and modulation duty-cycle, shorter on-time pulses result in significantly enhanced ozone production, despite their operation at slightly higher temperatures. The key underpinning mechanism that causes this counter-intuitive observation is the more efficient net generation rate of ozone during the plasma on-time due to the lower accumulation of NO2 in the discharge volume

Microbubble-enhanced DBD plasma reactor: Design, characterisation and modelling

The emerging field of atmospheric pressure plasmas (APPs) for treatment of various solutions and suspensions has led to a variety of plasma reactors and power sources. This article reports on the design, characterisation and modelling of a novel plasma-microbubble reactor that forms a dielectric barrier discharge (DBD) at the gas-liquid interface to facilitate the transfer of short-lived highly reactive species from the gas plasma into the liquid phase. The use of microbubbles enabled efficient dispersion of long-lived reactive species in the liquid and UVC-induced oxidation reactions are triggered by the plasma radiation at the gas-liquid interface. A numerical model was developed to understand the dynamics of the reactor, and the model was validated using experimental measurements. Fluid velocities in the riser region of the reactor were found to be an order of magnitude higher for smaller bubbles (~500 µm diameter) than for larger bubbles (~2500 µm diameter); hence provided well-mixed conditions for treatment. In addition to other reactive oxygen species (ROS) and reactive nitrogen species (RNS), 2 a dissolved ozone concentration of 3 µM was recoded after a 15-minute operation of the reactor, demonstrating the suitability of this design for various applications

Paired accelerated arames: The perfect interferometer with everywhere smooth wave amplitudes

Rindler's acceleration-induced partitioning of spacetime leads to a nature-given interferometer. It accomodates quantum mechanical and wave mechanical processes in spacetime which in (Euclidean) optics correspond to wave processes in a ``Mach-Zehnder'' interferometer: amplitude splitting, reflection, and interference. These processes are described in terms of amplitudes which behave smoothly across the event horizons of all four Rindler sectors. In this context there arises quite naturally a complete set of orthonormal wave packet histories, one of whose key properties is their "explosivity index". In the limit of low index values the wave packets trace out fuzzy world lines. By contrast, in the asymptotic limit of high index values, there are no world lines, not even fuzzy ones. Instead, the wave packet histories are those of entities with non-trivial internal collapse and explosion dynamics. Their details are described by the wave processes in the above-mentioned Mach-Zehnder interferometer. Each one of them is a double slit interference process. These wave processes are applied to elucidate the amplification of waves in an accelerated inhomogeneous dielectric. Also discussed are the properties and relationships among the transition amplitudes of an accelerated finite-time detector.Comment: 38 pages, RevTex, 10 figures, 4 mathematical tutorials. Html version of the figures and of related papers available at http://www.math.ohio-state.edu/~gerlac