The life on Mars dilemma and the sample return mission

The dilemma of whether there is life on Mars impacts on the method used for sampling. The NASA Mars Sample Return Mission should be used to resolve the problems

A computer system to perform structure comparison using TOPS representations of protein structure

We describe the design and implementation of a fast topology–based method for protein structure comparison. The approach uses the TOPS topological representation of protein structure, aligning two structures using a common discovered pattern and generating measure of distance derived from an insert score. Heavy use is made of a constraint-based pattern matching algorithm for TOPS diagrams that we have designed and described elsewhere Gilbert et al. (1999). The comparison system is maintained at the European Bioinformatics Institute and is available over the Web via the at tops.ebi.ac.uk/tops. Users submit a structure description in Protein Data Bank (PDB) format and can compare it with structures in the entire PDB or a representative subset of protein domains, receiving the results by email

Analysis of signalling pathways using the prism model checker

We describe a new modelling and analysis approach for signal transduction networks in the presence of incomplete data. We illustrate the approach with an example, the RKIP inhibited ERK pathway [1]. Our models are based on high level descriptions of continuous time Markov chains: reactions are modelled as synchronous processes and concentrations are modelled by discrete, abstract quantities. The main advantage of our approach is that using a (continuous time) stochastic logic and the PRISM model checker, we can perform quantitative analysis of queries such as if a concentration reaches a certain level, will it remain at that level thereafter? We also perform standard simulations and compare our results with a traditional ordinary differential equation model. An interesting result is that for the example pathway, only a small number of discrete data values is required to render the simulations practically indistinguishable

Adaptive Element-Free Galerkin method applied to the limit analysis of plates

The implementation of an h-adaptive Element-Free Galerkin (EFG) method in the framework of limit analysis is described. The naturally conforming property of mesh- free approximations (with no nodal connectivity required) facilitates the implementation of h-adaptivity. Nodes may be moved, discarded or introduced without the need for complex manipulation of the data structures involved. With the use of the Taylor expansion technique, the error in the computed displacement field and its derivatives can be estimated throughout the problem domain with high accuracy. A stabilized conforming nodal integration scheme is extended to error estimators and results in an efficient and truly meshfree adaptive method. To demonstrate its effectiveness the procedure is then applied to plates with various boundary conditions

Land rights and the forest peoples of Africa: historical, legal and anthropological perspectives: legal rights under international law

International law, and more particularly international human rights law, has for some time been seen as a positive tool to support indigenous peoples’ rights; when it comes to land rights, however, such positivity is new. September 2007 marked the start of a new era for indigenous peoples, with the adoption of the United Nations Declaration on the Rights of Indigenous Peoples. Despite this recent development, international law has historically played a negative role regarding indigenous peoples’ rights, and more especially their rights to land. An important tool in the hands of the colonial powers, international law has been a central vehicle in the dispossession of indigenous peoples. Most of the rules regarding title to territory under international law were aimed at justifying the dispossession of indigenous peoples of their lands. While various legal systems applied, during colonisation, to land rights for indigenous peoples – depending on which state was the coloniser – international law played the role of common denominator, ensuring that all powers adhered to the same legal doctrine. The rules governing title to territory under international law became the basis of the ‘rules of the game’ between the colonial powers, and as such had a direct impact on indigenous peoples’ land rights. Because of this legacy, international law still plays a huge part in the contemporary situations faced by indigenous communities throughout the continent today. But this legacy is seriously challenged by recent development stemming from international human rights law. The first part of this chapter provides the historical background, setting out the complexity of contemporary indigenous land claims. Based on this analysis, the second part of the chapter examines the content of states’ obligations regarding land rights for indigenous peoples under international human rights law

Should Farmers Invest in Financial Assets as a Risk Management Strategy? Some Evidence from New Zealand

Off-farm investment as a risk management strategy is not widespread among New Zealand sheep and beef farmers. This study explores the potential for risk reduction by the diversification of farm asset portfolios to include financial investments such as industrial equities and government bonds of various types. Results show that the negative correlations between long-run rates of return on farm assets and financial investments could result in a significant reduction of risk if equities and bonds were included in farm investment portfolios. However, when combined with information about attitudes to risks, it does not seem likely that farmers would adopt such strategies purely in order to stabilise incomes. Deregulation of the New Zealand economy in the mid 1980's had little impact on farmers' optimal allocation of their assets.Agricultural Finance, Risk and Uncertainty,

The Dominance of Metal-Rich Streams in Stellar Halos: A Comparison Between Substructure in M31 and Lambda-CDM Models

Extensive photometric and spectroscopic surveys of the Andromeda galaxy (M31) have discovered tidal debris features throughout M31's stellar halo. We present stellar kinematics and metallicities in fields with identified substructure from our on-going SPLASH survey of M31 red giant branch stars with the DEIMOS spectrograph on the Keck II 10-m telescope. Radial velocity criteria are used to isolate members of the kinematically-cold substructures. The substructures are shown to be metal-rich relative to the rest of the dynamically hot stellar population in the fields in which they are found. We calculate the mean metallicity and average surface brightness of the various kinematical components in each field, and show that, on average, higher surface brightness features tend to be more metal-rich than lower surface brightness features. Simulations of stellar halo formation via accretion in a cosmological context are used to illustrate that the observed trend can be explained as a natural consequence of the observed dwarf galaxy mass-metallicity relation. A significant spread in metallicity at a given surface brightness is seen in the data; we show that this is due to time effects, namely the variation in the time since accretion of the tidal streams' progenitor onto the host halo. We show that in this theoretical framework a relationship between the alpha-enhancement and surface brightness of tidal streams is expected, which arises from the varying times of accretion of the progenitor satellites onto the host halo. Thus, measurements of the alpha-enrichment, metallicity, and surface brightness of tidal debris can be used to reconstruct the luminosity and time of accretion onto the host halo of the progenitors of tidal streams.Comment: 11 pages, 6 figures, published in Ap

Activation analysis of admixtures in certain semiconductive materials

The use of extractions and chromatographic operations to separate macrobases, and to divide elements into groups convenient for gamma-spectrometric analysis is discussed. Methods are described for the activation detection of some impurities in silicon, arsenic, thallium, and trichloromethylsilane, on the basis of the extraction properties of bis(2-chlorethyl ether) and dimethylbenzylalkylammonium chloride. A schematic diagram of the extraction separation of elements-admixture is presented showing the aqueous and organic phases. The content percentage of the various elements are given in tables