Practical Bayesian Optimization for Variable Cost Objectives

We propose a novel Bayesian Optimization approach for black-box functions with an environmental variable whose value determines the tradeoff between evaluation cost and the fidelity of the evaluations. Further, we use a novel approach to sampling support points, allowing faster construction of the acquisition function. This allows us to achieve optimization with lower overheads than previous approaches and is implemented for a more general class of problem. We show this approach to be effective on synthetic and real world benchmark problems.Comment: 8 pages, 7 figure

Dietary provocation of reginic allergy in young rats

Atopic allergies are common and important causes of childhood morbidity. Treatment for conditions such as eczema, asthma and rhinitis is usually symptomatic and attention has therefore turned to their possible prevention. Though the genetic predisposition to atopic allergies is not in doubt, their provocation by environmental factors, as shown by a number of clinical studies, suggests that non-genetic factors may moderate the expression of atopic symptoms. One such factor is exclusive breast feeding, protecting the human infant against sensitization to several recognized antigens; an antigen non-specific effect. In contrast, other studies have shown that infants fed with cows milk preparations have more atopic disease and more immunoglobulin E antibody (lgE), though many do not produce an lgE response to cows milk proteins. Therefore it is not established from the clinical data whether cows milk feeds themselves provoke allergies, or if removing the protective effect of breast milk results in sensitization. Furthermore, feeding supplements of cows milk to a breast fed baby is a common practice, and its immunological effect is uncertain, though clinical evidence suggests that such a feeding regimen fails to protect against atopic allergies. Jarrett and her colleagues have characterized lgE responses in Hooded Lister rats and this species was chosen for my investigations to determine if supplements of cows milk fed to suckling rat pups modifies the subsequent lgE antibody response to ovalbumin; this antigen non-specific effect was demonstrated. Supplements of a cows milk-based preparation increased the lgE and lgG response to injected ovalbumin. The effect was antigen dose dependent, more evident when a small dose was injected than with a higher dose which produced comparably high lgE responses in both supplemented and unsupplemented animals. In contrast to the effect with the low dose, a higher dose reduced the lgG antiovalbumin response in supplemented rats; the explanation for this is unknown. One suggested mechanism of the antigen non-specific effect of cows milk feeds in human infants is that of disturbance in intestinal bacterial colonization, releasing endotoxin adjuvant into the circulation; my experiments in rats lend some support to this concept. The supplementary feeds with a cows milk preparation did not provoke an antibody response to cows milk proteins, suggesting that the detrimental effects of cows milk feeds are not confined to milk protein antigens; as in human infants, they potentiate sensitization to several recognized antigens. It is clear that such an effect is not just that of removing the protection against atopic allergy afforded by breast milk. Supplementary feeds to suckling rat pups did not influence the previously described antigen specific suppression of lgE response in the offspring of sensitized females; I have shown that suppression results from passive transfer of maternal antibody to the offspring. The relevance of this to human atopic allergy is uncertain and there is, as yet, no evidence that allergic mothers protect their babies against sensitization. The lgE antibody response to immunization regimens previously described for eliciting such responses in adult outbred Hooded Lister rats were studied in the young rat by paper radioallergosorbent test and by passive cutaneous anaphylaxis. The factors which initiate the allergic response in the young rat may well also apply to the origin of atopic allergy in human infants. Allergic rats demonstrate anaphylaxis with intravenous antigen challenge and increased antigen absorption with oral antigen challenge; these effects parallel closely the clinical effects of human reaginic allergy. The results of these studies support the view that dietary supplements fed to suckling mammals have important immunological consequences

Work related mortality from gastrointestinal diseases and alcohol among seafarers employed in British merchant shipping from 1939 to 2002

Objectives: To investigate work related mortality from gastrointestinal diseases and from alcohol among seafarers who were employed in British merchant shipping from 1939 to 2002. Methods: A longitudinal study, based on official mortality files from 1976-2002 and official mortality returns from 1939-1975, with a population of 7.29 million seafarer-years at risk. Results: From 1939 to 2002, there were 864 deaths from gastrointestinal diseases and 72 from alcoholism. Overall mortality from gastrointestinal diseases fell from 18.4 per 100,000 in 1939-49 to 9.3 in 1970-79 and 0.3 in 1990-2002. Mortality from alcoholism, and from alcohol-related diseases such as liver cirrhosis and diseases of the pancreas, increased up to the 1960s or 1970s, but fell thereafter. From 1950 to 1972, mortality from gastrointestinal diseases was 1.8 times higher among Asian seafarers compared to British seafarers, largely because of liver disease, peritonitis and peptic ulcer. At the time of the last censuses of seamen in 1961 and 1971, compared with the general British male working aged population, morality among British seafarers was greatly increased for peritonitis and alcoholism but not for most other gastrointestinal diseases. Conclusions: Sharp reductions in mortality from gastrointestinal diseases and from alcoholism since the 1970s contrasts with increases among the general British population, and are largely because of the “flagging-out” of most British deep sea ships, and consequent reductions in long voyages, as well as reductions in alcohol consumption among seafarers at work. Largely because of the healthy worker effect, seafarers were usually only at increased risks from particularly acute diseases

Efficient Bayesian Nonparametric Modelling of Structured Point Processes

This paper presents a Bayesian generative model for dependent Cox point processes, alongside an efficient inference scheme which scales as if the point processes were modelled independently. We can handle missing data naturally, infer latent structure, and cope with large numbers of observed processes. A further novel contribution enables the model to work effectively in higher dimensional spaces. Using this method, we achieve vastly improved predictive performance on both 2D and 1D real data, validating our structured approach.Comment: Presented at UAI 2014. Bibtex: @inproceedings{structcoxpp14_UAI, Author = {Tom Gunter and Chris Lloyd and Michael A. Osborne and Stephen J. Roberts}, Title = {Efficient Bayesian Nonparametric Modelling of Structured Point Processes}, Booktitle = {Uncertainty in Artificial Intelligence (UAI)}, Year = {2014}

Distribution of Gaussian Process Arc Lengths

We present the first treatment of the arc length of the Gaussian Process (GP) with more than a single output dimension. GPs are commonly used for tasks such as trajectory modelling, where path length is a crucial quantity of interest. Previously, only paths in one dimension have been considered, with no theoretical consideration of higher dimensional problems. We fill the gap in the existing literature by deriving the moments of the arc length for a stationary GP with multiple output dimensions. A new method is used to derive the mean of a one-dimensional GP over a finite interval, by considering the distribution of the arc length integrand. This technique is used to derive an approximate distribution over the arc length of a vector valued GP in $\mathbb{R}^n$ by moment matching the distribution. Numerical simulations confirm our theoretical derivations.Comment: 10 pages, 4 figures, Accepted to The 20th International Conference on Artificial Intelligence and Statistics (AISTATS