Fitting a spatial-temporal rainfall model using Approximate Bayesian Computation

We fit a stochastic spatial-temporal model to high-resolution rainfall radar data for a single rainfall event. Approximate Bayesian Computation (ABC) is used to fit a model of Cox, Isham and Northrop, previously fitted using the Generalised Method of Moments (GMM). We then show that ABC readily adapts to more general, and thus more realistic, variants of the model. The Simulated Method of Moments (SMM) is used to initialise the ABC fit

Thorny Spheres and Black Holes with Strings

We consider thorny spheres, that is 2-dimensional compact surfaces which are everywhere locally isometric to a round sphere $S^2$ except for a finite number of isolated points where they have conical singularities. We use thorny spheres to generate, from a spherically symmetric solution of the Einstein equations, new solutions which describe spacetimes pierced by an arbitrary number of infinitely thin cosmic strings radially directed. Each string produces an angle deficit proportional to its tension, while the metric outside the strings is a locally spherically symmetric solution. We prove that there can be arbitrary configurations of strings provided that the directions of the strings obey a certain equilibrium condition. In general this equilibrium condition can be written as a force-balance equation for string forces defined in a flat 3-space in which the thorny sphere is isometrically embedded, or as a constraint on the product of holonomies around strings in an alternative 3-space that is flat except for the strings. In the case of small string tensions, the constraint equation has the form of a linear relation between unit vectors directed along the string axes.Comment: 37 pages, 11 figure

Cardiovascular Risk Factors Among People being Treated for HIV in Nepal: a Cross-Sectional Study.

Background: Human Immunodeficiency Virus (HIV) and antiretroviral therapy (ART) are found to be strongly associated with cardiovascular diseases. Data are sparse on the prevalence and distribution of cardiovascular risk factors among people being treated for HIV in South Asia region. Methods: A cross-sectional study of 103 HIV patients (51 women and 52 men) attending routine follow-up consultations at the largest ART centre in Nepal was conducted. Data on several cardiovascular risk factors were collected through interview questionnaires, biophysical measurements and consulting medical records. Results: The most common cardiovascular risk factors observed were central obesity [34.6%, 95% Confidence Interval (CI): 25.3% to 43.9%], chronic kidney disease [20.7% (95% CI: 11.6% to 29.7%)] and tachycardia [20.6% (95% CI: 12.7% to 28.5%)]. Females were significantly more likely to have central obesity (male 9.8% vs. female 60%, p=0.016) and chronic kidney disease (male 15.4% vs. female 26.3%, p=0.003) as compared to the males. Participants were fairly active but a large proportion, especially men, had smoked [65% (95% CI: 57%-72.3%)], used tobacco products [66% (95% CI: 56.4%-74.4%)] or drugs (53.8% of the men) and consumed alcohol [60.2% (95% CI: 50.5%-69.1%)]. Conclusion: A high prevalence of several cardiovascular risk factors was observed among patients being treated for HIV in Nepal. Further larger studies are warranted to better understand the relevance and public health impact of cardiovascular risk factors in this region

Correlations between black holes formed in cosmic string breaking

An analysis of cosmic string breaking with the formation of black holes attached to the ends reveals a remarkable feature: the black holes can be correlated or uncorrelated. We find that, as a consequence, the number-of-states enhancement factor in the action governing the formation of uncorrelated black holes is twice the one for a correlated pair. We argue that when an uncorrelated pair forms at the ends of the string, the physics involved is more analogous to thermal nucleation than to particle-antiparticle creation. Also, we analyze the process of intercommuting strings induced by black hole annihilation and merging. Finally, we discuss the consequences for grand unified strings. The process whereby uncorrelated black holes are formed yields a rate which significantly improves over those previously considered, but still not enough to modify string cosmology.Comment: 11 pages, LaTeX. Final version, to appear in Phys. Rev.

Unambiguous probabilities in an eternally inflating universe

``Constants of Nature'' and cosmological parameters may in fact be variables related to some slowly-varying fields. In models of eternal inflation, such fields will take different values in different parts of the universe. Here I show how one can assign probabilities to values of the ``constants'' measured by a typical observer. This method does not suffer from ambiguities previously discussed in the literature.Comment: 7 pages, Final version (minor changes), to appear in Phys. Rev. Let

Univalent Foundations and the UniMath Library

We give a concise presentation of the Univalent Foundations of mathematics outlining the main ideas, followed by a discussion of the UniMath library of formalized mathematics implementing the ideas of the Univalent Foundations (section 1), and the challenges one faces in attempting to design a large-scale library of formalized mathematics (section 2). This leads us to a general discussion about the links between architecture and mathematics where a meeting of minds is revealed between architects and mathematicians (section 3). On the way our odyssey from the foundations to the "horizon" of mathematics will lead us to meet the mathematicians David Hilbert and Nicolas Bourbaki as well as the architect Christopher Alexander

Middle mountains forests of Nepal

Publication no. 3201