Modulation of the CD8+-T-cell response by CD4+ CD25+ regulatory T cells in patients with Hepatitis B virus infection

CD4+ CD25+ regulatory T cells have been shown to maintain peripheral tolerance against self and foreign antigens. In this study we analyzed the effect of circulating CD4+ CD25+ T cells on CD8+-T-cell responses of patients with chronic and resolved hepatitis B virus (HBV) infection. We demonstrated that circulating CD4+ CD25+ T cells modulate the function and expansion of HBV-specific CD8+ cells ex vivo in all patients, regardless of whether they have chronic or resolved HBV infection. The possible role of CD4+ CD25+ T cells in the pathogenesis of chronic HBV infection is not supported by these data. However, these results might have implications for optimizing future immunotherapeutic approaches to HBV treatment

Numerical modelling of the sound absorption spectra for bottleneck dominated porous metallic structures

Numerical simulations are used to test the ability of several common equivalent fluid models to predict the sound absorption behaviour in porous metals with “bottleneck” type structures. Of these models, Wilson's relaxation model was found to be an excellent and overall best fit for multiple sources of experimental acoustic absorption data. Simulations, incorporating Wilson's model, were used to highlight the relative importance of key geometrical features of bottleneck structures on the normal incidence sound absorption spectrum. Simulations revealed significant improvements in absorption behaviour would be achieved, over a “benchmark” structure from the literature, by maximising the porosity (0.8) and targeting a permeability in the range of 4.0 × 10 −10 m 2 . Such a modelling approach should provide a valuable tool in the optimisation of sound absorption performance and structural integrity, to meet application-specific requirements, for a genre of porous materials that offer a unique combination of acoustic absorption and load bearing capability

The optimum slaughter weight for different ewe mature sizes

Lamb producers have the option to market lambs at a range of slaughter weights. However, there are limited price premiums for heavier carcasses on a per kilogram basis. Any economic advantage of heavy lambs is realised by extra weight and not price. Both genetic and on-farm factors contribute to extra weight gain. Firstly, lamb weight and growth is correlated to its mature size and lambs from larger parents grow faster and reach heavier weights, but also have greater feed requirements. Secondly, stocking and reproductive rate account for the majority of variation in whole-farm profit, but increasing these also increases feed requirements. The production of heavy lambs is therefore a trade-off with maximising stocking and reproductive rate within the pool of available feed resources. We hypothesise that slaughter weight does not increase with mature size, due to the priority to increase stocking and reproductive rate for profit maximisation

Extended G-vertex colored partition algebras as centralizer algebras of symmetric groups

The Partition algebras Pk(x) have been defined in [M1] and [Jo]. We introduce a new class of algebras for every group G called “Extended G-Vertex Colored Partition Algebras," denoted by Pbk(x,G), which contain partition algebras Pk(x), as subalgebras. We generalized Jones result by showing that for a finite group G, the algebra Pbk(n,G) is the centralizer algebra of an action of the symmetric group Sn on tensor space W⊗k , where W = C n|G| . Further we show that these algebras Pbk(x,G) contain as subalgebras the “G-Vertex Colored Partition Algebras Pk(x,G)," introduced in [PK1]

Agricultural research for nutrition outcomes – rethinking the agenda

Agriculture and food are assumed to be critical determinants of stunting and micronutrient deficiency. However, agriculture research for development has not translated as expected into better nutrition outcomes. We argue that to do so, agriculture research needs to be fundamentally changed, from the current emphasis on supply-side production and productivity goals to understanding consumption and addressing factors that can improve diet quality. Some of the research will be to improve the efficiency of supply for more nutritious foods. Other research will need to focus on factors that promote diet quality rather than focus on food security goals through stocks of staple cereals. Because of its importance in low-income, high-burden countries, agriculture can also contribute more effectively to multisectoral nutrition-sensitive development strategies and programs. Critical roles for agricultural research in multisectoral actions will be better metrics, indicators and research studies for diet quality and better evaluation methods – both randomized trials for specific interventions and contribution analysis through theories of change for more complex multisectoral system interventions to prevent stunting and micronutrient deficiencies. To achieve improvements in nutrition outcomes at scale, researchers must engage in new partnerships. In food systems, these partnerships must include more disciplines from agriculture and food science through economics and social science to business and delivery science. Food system researchers will also need to engage more with value chain actors and policy makers. Current efforts to improve nutrition outcomes at scale are severely hampered by data and evidence gaps that prevent better decisions and faster learning

Evolutionary estimation of a Coupled Markov Chain credit risk model

There exists a range of different models for estimating and simulating credit risk transitions to optimally manage credit risk portfolios and products. In this chapter we present a Coupled Markov Chain approach to model rating transitions and thereby default probabilities of companies. As the likelihood of the model turns out to be a non-convex function of the parameters to be estimated, we apply heuristics to find the ML estimators. To this extent, we outline the model and its likelihood function, and present both a Particle Swarm Optimization algorithm, as well as an Evolutionary Optimization algorithm to maximize the likelihood function. Numerical results are shown which suggest a further application of evolutionary optimization techniques for credit risk management

Adventures in Bidirectional Programming

Most programs get used in just one direction, from input to output. But sometimes, having computed an output, we need to be able to update this output and then calculate backwards to find a correspondingly updated input. The problem of writing such bidirectional transformations — often called lenses — arises in applications across a multitude of domains and has been attacked from many perspectives [1–12, etc.]. See [13] for a detailed survey

The permeability of virtual macroporous structures generated by sphere packing models: comparison with analytical models

Realistic porous structures typical of those made by replication of packed beds of spherical particles have been produced by a novel modelling method. Fluid dynamics simulation of the permeability of these structures agrees well with experimental measurements and similar modelling of structures derived from X-ray tomographic images. By varying the model structures the “bottleneck” flow concept proposed by analytical models in the literature was substantiated, confirming the high dependence of permeability on the size of the windows connecting the pores but also highlighting the need for accurate determination of the connectivity of the pores for these models to be accurate

Modelling and optimisation of sound absorption in replicated microcellular metals

Wilson's poroacoustic model has been shown to be an accurate predictor of sound absorption in porous metals with bottleneck type structures. When used to optimise pore structures, using porosity and permeability as variables, the most broadband absorption is predicted for the highest porosity achievable (approximately 70%) and for a permeability of the order 10−10 m2. Although performance close to that for glass wool is not possible, with these porosities, specific strength and stiffness exceeding those for many polymers are obtained, making these materials viable for load bearing components with credible soundproofing

Exact sampling of self-avoiding paths via discrete Schramm-Loewner evolution

We present an algorithm, based on the iteration of conformal maps, that produces independent samples of self-avoiding paths in the plane. It is a discrete process approximating radial Schramm-Loewner evolution growing to infinity. We focus on the problem of reproducing the parametrization corresponding to that of lattice models, namely self-avoiding walks on the lattice, and we propose a strategy that gives rise to discrete paths where consecutive points lie an approximately constant distance apart from each other. This new method allows us to tackle two non-trivial features of self-avoiding walks that critically depend on the parametrization: the asphericity of a portion of chain and the correction-to-scaling exponent.Comment: 18 pages, 4 figures. Some sections rewritten (including title and abstract), numerical results added, references added. Accepted for publication in J. Stat. Phy