Intertwined strands for ecology in planetary health

Ecology is both blessed and burdened by romanticism, with a legacy that is multi-edged for health. The prefix ‘eco-’ can carry a cultural and political (subversive) baggage, associated with motivating environmental activism. Ecology is also practiced as a technical ‘science’, with quantitative and deterministic leanings and a biophysical emphasis. A challenge for planetary health is to avoid lapsing into, or rejecting, either position. A related opportunity is to adopt ecological thought that offers a rich entrance to understanding living systems: a relationality of connectedness, interdependence, and reciprocity to understand health in a complex and uncertain world. Planetary health offers a global scale framing; we regard its potential as equivalent to the degree to which it can embrace, at its core, ecological thought, and develop its own political narrative

Exploring the landscape of the space of heuristics for local search in SAT

Local search is a powerful technique on many combinatorial optimisation problems. However, the effectiveness of local search methods will often depend strongly on the details of the heuristics used within them. There are many potential heuristics, and so finding good ones is in itself a challenging search problem. A natural method to search for effective heuristics is to represent the heuristic as a small program and then apply evolutionary methods, such as genetic programming. However, the search within the space of heuristics is not well understood, and in particular little is known of the associated search landscapes. In this paper, we consider the domain of propositional satisfiability (SAT), and a generic class of local search methods called ‘WalkSAT’. We give a language for generating the heuristics; using this we generated over three million heuristics, in a systematic manner, and evaluated their associated fitness values. We then use this data set as the basis for an initial analysis of the landscape of the space of heuristics. We give evidence that the heuristic landscape exhibits clustering. We also consider local search on the space of heuristics and show that it can perform quite well, and could complement genetic programming methods on that space

Systematic search for local-search SAT heuristics

Heuristics for local-search are a commonly used method of improving the performance of algorithms that solve hard computational problems. Generally these are written by human experts, however a long-standing research goal has been to automate the construction of these heuristics. In this paper, we investigate the applicability of a systematic search on the space of heuristics to be used in a local-search SAT solver

Elements of Mechanics

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Calculating pp-values and their significances with the Energy Test for large datasets

The energy test method is a multi-dimensional test of whether two samples are consistent with arising from the same underlying population, through the calculation of a single test statistic (called the $T$-value). The method has recently been used in particle physics to search for differences between samples that arise from CP violation. The generalised extreme value function has previously been used to describe the distribution of $T$-values under the null hypothesis that the two samples are drawn from the same underlying population. We show that, in a simple test case, the distribution is not sufficiently well described by the generalised extreme value function. We present a new method, where the distribution of $T$-values under the null hypothesis when comparing two large samples can be found by scaling the distribution found when comparing small samples drawn from the same population. This method can then be used to quickly calculate the $p$-values associated with the results of the test.Comment: 9 pages (including title page); 4 figure

Test Facility and Preliminary Performance of a 100 kW Class MPD Thruster

A 260 kW magnetoplasmadynamic (MPD) thruster test facility was assembled and used to characterize thrusters at power levels up to 130 kW using argon and helium propellants. Sensitivities of discharge characteristics to arc current, mass flow rate, and applied magnetic field were investigated. A thermal efficiency correlation developed by others for low power MPD thrusters defined parametric guidelines to minimize electrode losses in MPD thrusters. Argon and helium results suggest that a parameter defined as the product of arc voltage and the square root of the mass flow rate must exceed 0.7 V/kg(sup 1/2)/sec(sup 1/2) in order to obtain thermal efficiencies in excess of 60 percent

The reliability of sickling and solubility tests and peripheral blood film method for sickle cell disease screening at district health centers in Uganda.

Bien que les analyses hématies falciformes, la solubilité et le film sanguin périphérique soient aujourd’hui disponibles pour le dépistage de la maladie drépanocytaire en Ouganda, leur fiabilité et aisance d’applicabilité n’ont pas été déterminées. Cette étude a été, par conséquent réalisée pour déterminer la fiabilité de la méthode de dépistage des analyses des hématies falciformes et de la solubilité ainsi que le film sanguin périphérique pour la SCD (sigle anglais pour Sickle cell disease) en Ouganda. Ceci a été une étude descriptive basée au laboratoire et réalisée par le Collège des Sciences de la Sante de l’Université de Makerere. Les 200 prélèvements des enfants ages de 6 mois à 5 ans ont été analysés de façon indépendante en utilisant la méthode des analyses d’hématies falciformes, la solubilité et le film sanguin périphérique. L’acétate de cellulose de l’électrophorèse de l’hémoglobine a été utilise comme échantillon. Les analyses des hématies falciformes et de solubilité ont eu la sensibilité de 65,0% et 45,0%, respectivement, et le film sanguin périphérique a eu 35,0%/. Les hématies falciformes, la solubilité et le film sanguin périphérique ont eu les spécifications de 95,6%, 90,0% et 96,7% respectivement. Les hématies falciformes ont eu la précision diagnostique de 92,5%, la solubilité – 85,5% et le film sanguin périphérique – 90,5%. Les hématies falciformes ont eu le Kappa de Cohen de 0,6, la solubilité – 0,3 et le film sanguin périphérique – 0,4. L’analyse des hématies falciformes a eu une période de rotation de 38 minutes, la solubilité – 70 minutes et le film sanguin périphérique – 44 minutes. En conclusion, l’analyse des hématies falciformes a été plus fiable et plus facile à exécuter que l’analyse de la solubilité et la méthode de film sanguin périphérique. Elle serait, par conséquent, une analyse recommandée pour le dépistage préliminaire des enfants pour la SCD aux centres de santé IV au niveau de districts et confirmer seulement les résultats positifs en utilisant l’électrophorèse de l’hémoglobine.KEY WORDS: Screening - Sickling and solubility tests -Peripheral blood film - Sickle cell disease - Uganda

Derivation and Performance of Standardized Enhanced Liver Fibrosis (ELF) Test Thresholds for the Detection and Prognosis of Liver Fibrosis

INTRODUCTION: Noninvasive tests are increasingly used to assess liver fibrosis and determine prognosis but suggested test thresholds vary. We describe the selection of standardized thresholds for the Enhanced Liver Fibrosis (ELF) test for the detection of liver fibrosis and for prognostication in chronic liver disease. METHODS: A Delphi method was used to identify thresholds for the ELF test to predict histological liver fibrosis stages, including cirrhosis, using data derived from 921 patients in the EUROGOLF cohort. These thresholds were then used to determine the prognostic performance of ELF in a subset of 457 patients followed for a mean of 5 years. RESULTS: The Delphi panel selected sensitivity of 85% for the detection of fibrosis and >95% specificity for cirrhosis. The corresponding thresholds were 7.7, 9.8, and 11.3. Eighty-five percent of patients with mild or worse fibrosis had an ELF score ≥7.7. The sensitivity for cirrhosis of ELF ≥9.8 was 76%. ELF ≥11.3 was 97% specific for cirrhosis. ELF scores show a near-linear relationship with Ishak fibrosis stages. Relative to the <7.7 group, the hazard ratios for a liver-related outcome at 5 years were 21.00 (95% CI, 2.68-164.65) and 71.04 (95% CI, 9.4-536.7) in the 9.8 to <11.3 and ≥11.3 subgroups, respectively. CONCLUSION: The selection of standard thresholds for detection and prognosis of liver fibrosis is described and their performance reported. These thresholds should prove useful in both interpreting and explaining test results and when considering the relationship of ELF score to Ishak stage in the context of monitoring

Monoid presentations of groups by finite special string-rewriting systems

We show that the class of groups which have monoid presentations by means of finite special [λ]-confluent string-rewriting systems strictly contains the class of plain groups (the groups which are free products of a finitely generated free group and finitely many finite groups), and that any group which has an infinite cyclic central subgroup can be presented by such a string-rewriting system if and only if it is the direct product of an infinite cyclic group and a finite cyclic group

The application of fixed hydrophobic patterns for confinement of aqueous solutions in proteomic microarrays

A protein microarray hybridisation system has been implemented by employing patterned hydrophobic thin films on hydrophilic substrates as a means of confinement for aqueous samples. This approach has the ability to handle, and keep separate, small sample volumes of just a few microlitres. In addition, the system is more straightforward to use than the existing multi-well gasket solution. The paper describes the fabrication method and the system is demonstrated for a model protein microarray assay