The Oklo Natural Nuclear Reactors : Evidence of Variable Constants?

There is apparently virtually universal agreement that certain deposits found at the Oklo uranium mine in Gabon, Africa are the remains of “natural nuclear reactors.” This paper examines the make-up and configuration of some of these reactors and shows that these deposits were not capable of a sustained nuclear fission chain reaction if the nuclear characteristics of the isotopes involved were the same as they are today. If these deposits really are the remains of natural nuclear reactors, then they appear to provide support for the hypothesis that nuclear constants have changed over time

Midazolam use for dental conscious sedation: how safe are we?

Aim: To explore the safety awareness of midazolam use amongst dentist in the UK. Materials and methods: A cross-sectional study on 203 dentists was undertaken, 146 of whom currently practice conscious sedation using intravenous midazolam. Use of high strength midazolam; awareness of the Rapid Response Report (RRR) and the National Reporting and Learning System (NRLS); and midazolam related incidents were explored. Results: Formal training in conscious sedation was variable with 35.6% holding a postgraduate sedation qualification. Flumazenil administration was common practice (63%) although used very selectively. Use to reverse respiratory depression was minimal (4%). Awareness of the RRR and the NRLS was generally low but higher among those working in general dental practice (p<0.05). Comparative analysis showed that high dose midazolam was administered more frequently in gastroenterology than in dentistry (p<0.001) with higher incidences of overdose (12.4% Vs 4.8%) and death (8.3% Vs 0%) within a 3 year period. Conclusions: High strength midazolam administration remains prevalent in dentistry, despite recommendations by the DoH. Use of flumazenil for reasons other than respiratory depression in dentistry should warrant little concern. The low incidence of reported harm is positive but may be due to a lack of uptake of national reporting systems

Stochastic Chemical Reactions in Micro-domains

Traditional chemical kinetics may be inappropriate to describe chemical reactions in micro-domains involving only a small number of substrate and reactant molecules. Starting with the stochastic dynamics of the molecules, we derive a master-diffusion equation for the joint probability density of a mobile reactant and the number of bound substrate in a confined domain. We use the equation to calculate the fluctuations in the number of bound substrate molecules as a function of initial reactant distribution. A second model is presented based on a Markov description of the binding and unbinding and on the mean first passage time of a molecule to a small portion of the boundary. These models can be used for the description of noise due to gating of ionic channels by random binding and unbinding of ligands in biological sensor cells, such as olfactory cilia, photo-receptors, hair cells in the cochlea.Comment: 33 pages, Journal Chemical Physic

Scalable variational Gaussian process classification

Gaussian process classification is a popular method with a number of appealing properties. We show how to scale the model within a variational inducing point framework, outperforming the state of the art on benchmark datasets. Importantly, the variational formulation can be exploited to allow classification in problems with millions of data points, as we demonstrate in experiments.JH was supported by a MRC fellowship, AM and ZG by EPSRC grant EP/I036575/1, and a Google Focussed Research award.This is the final version of the article. It was first available from JMLR via http://jmlr.org/proceedings/papers/v38/hensman15.pd

The bloodstream differentiation - division of Trypanosoma brucei studied using mitochondrial markers

In the bloodstream of its mammalian host, the African trypanosome Trypanosoma brucei undergoes a life cycle stage differentiation from a long, slender form to a short, stumpy form. This involves three known major events: exit from a proliferative cell cycle, morphological change and mitochondrial biogenesis. Previously, models have been proposed accounting for these events (Matthews & Gull 1994a). Refinement of, and discrimination between, these models has been hindered by a lack of stage-regulated antigens useful as markers at the single-cell level. We have now evaluated a variety of cytological markers and applied them to investigate the coordination of phenotypic differentiation and cell cycle arrest. Our studies have focused on the differential expression of the mitochondrial enzyme dihydrolipoamide dehydrogenase relative to the differentiation-division of bloodstream trypanosomes. The results implicate a temporal order of events: commitment, division, phenotypic differentiation

MCMC for variationally sparse Gaussian processes

Gaussian process (GP) models form a core part of probabilistic machine learning. Considerable research effort has been made into attacking three issues with GP models: how to compute efficiently when the number of data is large; how to approximate the posterior when the likelihood is not Gaussian and how to estimate covariance function parameter posteriors. This paper simultaneously addresses these, using a variational approximation to the posterior which is sparse in support of the function but otherwise free-form. The result is a Hybrid Monte-Carlo sampling scheme which allows for a non-Gaussian approximation over the function values and covariance parameters simultaneously, with efficient computations based on inducing-point sparse GPs. Code to replicate each experiment in this paper will be available shortly.JH was funded by an MRC fellowship, AM and ZG by EPSRC grant EP/I036575/1 and a Google Focussed Research award.This is the final version of the article. It first appeared from the Neural Information Processing Systems Foundation via https://papers.nips.cc/paper/5875-mcmc-for-variationally-sparse-gaussian-processe

Food assessment: a discursive analysis of diet talk in interviews with older men who are obese

Objective: Obesity rates are increasing faster in men than in women, with particular concerns raised regarding older men. However, men are less likely than women to engage in weight-loss activities such as dieting, typically constructed as a feminine practice. Previous research has argued that men’s food consumption is notably different and unhealthier than women’s. The novel contribution of this article is an analysis of food assessments in order to explore how older men (mostly) undergoing weight management programmes make sense of changes in their nutritional intake. Design: Semi-structured interviews were conducted with 30 men who were obese, 27 of whom were engaged in weight loss programmes. Discursive psychology was employed to analyse the data. Results: In contrast to other research, participants constructed nutritional advice as enlightening. Participants worked up ‘ownership’ and pleasure assessments to certain food choices which they contrasted with new, less calorific, eating practices. Moreover, new diets were constructed as acceptable. Conclusion: Our study contributes new insights about how nutritional advice impacts upon preconceived (mis)understandings of healthy eating practices. During the interviews, men positioned themselves as educators – health promoters might usefully develop nutritional advice in collaboration with men who have successfully changed their diets for optimum effect

Study of parameter degeneracy and hierarchy sensitivity of NO ν A in presence of sterile neutrino

The first hint of the neutrino mass hierarchy is believed to come from the long-baseline experiment NOνA. Recent results from NOνA shows a mild preference towards the CP phase δ13 ¼ −90° and normal hierarchy. Fortunately this is the favorable area of the parameter space which does not suffer from the hierarchy-δ13 degeneracy and thus NOνA can have good hierarchy sensitivity for this true combination of hierarchy and δ13. Apart from the hierarchy-δ13 degeneracy there is also the octant-δ13 degeneracy. But this does not affect the favorable parameter space of NOνA as this degeneracy can be resolved with a balanced neutrino and antineutrino run. However, if we consider the existence of a light sterile neutrino then there may be additional degeneracies which can spoil the hierarchy sensitivity of NOνA even in the favorable parameter space. In the present work we find that apart from the degeneracies mentioned above, there are additional hierarchy and octant degeneracies that appear with the new phase δ14 in the presence of a light sterile neutrino in the eV scale. In contrast to the hierarchy and octant degeneracies appearing with δ13, the parameter space for hierarchy-δ14 degeneracy is different in neutrinos and antineutrinos though the octant- δ14 degeneracy behaves similarly in neutrinos and antineutrinos. We study the effect of these degeneracies on the hierarchy sensitivity of NOνA for the true normal hierarchy.Monojit Ghosh, Shivani Gupta, Zachary M. Matthews, Pankaj Sharma, and Anthony G. William