Teleonomic entropy: measuring the phase-space of end-directed systems

We introduce a novel way of measuring the entropy of a set of values undergoing changes. Such a measure becomes useful when analyzing the temporal development of an algorithm designed to numerically update a collection of values such as artificial neural network weights undergoing adjustments during learning. We measure the entropy as a function of the phase-space of the values, i.e. their magnitude and velocity of change, using a method based on the abstract measure of entropy introduced by the philosopher Rudolf Carnap. By constructing a time-dynamic two-dimensional Voronoi diagram using Voronoi cell generators with coordinates of value- and value-velocity (change of magnitude), the entropy becomes a function of the cell areas. We term this measure teleonomic entropy since it can be used to describe changes in any end-directed (teleonomic) system. The usefulness of the method is illustrated when comparing the different approaches of two search algorithms, a learning artificial neural network and a population of discovering agents. (C) 2004 Elsevier Inc. All rights reserved.

Lipid, sugar and liposaccharide based delivery systems 2

The vast majority of biologically active compounds will never be considered as potential drugs due to inherently poor bioavailability. This review discusses the progress in the development of chemical systems to improve the metabolic stability, absorption and physicochemical properties of potential drugs. Delivery systems that involve the conjugation of lipid and/or sugar moieties are highlighted, as well as novel methods of conjugation of these groups to drugs. The use of sugar molecules to target drugs to particular organs or cells is also discussed, as is the use of lipids in the growing area of gene delivery. This is an update of a previous review [1].

The prevalence and concentration of Escherichia coli O157 in faeces of cattle from different production systems at slaughter

Aims: To determine the prevalence and concentration of Escherichia coli O157 shed in faeces at slaughter, by beef cattle from different production systems. Methods and Results: Faecal samples were collected from grass-fed (pasture) and lot-fed (feedlot) cattle at slaughter and tested for the presence of E. coli O157 using automated immunomagnetic separation (AIMS). Escherichia coli O157 was enumerated in positive samples using the most probable number (MPN) technique and AIMS and total E. coli were enumerated using Petrifilm. A total of 310 faecal samples were tested (155 from each group). The geometric mean count of total E. coli was 5 x 10(5) and 2.5 x 10(5) CFU g(-1) for lot- and grass-fed cattle, respectively. Escherichia coli O157 was isolated from 13% of faeces with no significant difference between grass-fed (10%) and lot-fed cattle (15%). The numbers of E. coli O157 in cattle faeces varied from undetectable (

Ethics and health systems research in 'post'-conflict situations

Although considerable attention has been given to ethical issues related to clinical research in developing countries, in particular related to HIV therapy, there has been limited focus on health systems research, despite its increasing importance in the light of current trends in development assistance. This paper examines ethical issues related to health systems research in 'post'-conflict situations, addressing both generic issues for developing countries and those issues specific to 'post'-conflict societies, citing examples from the author's Cambodian experience. It argues that the destruction of health infrastructure results in a loss of structures and processes that would otherwise protect prospective research subjects who are part of vulnerable populations. It identifies the growth of health systems research as part of a trend towards sectoral and programmatic development assistance, the emergence of 'knowledge generation' as a form of research linked to development, and the potential for conflict where multilateral and bilateral donors are both primary funders and users of health systems research. It also examines the position of the health system researcher in relation to the sponsors of this research, and the health system being analysed.

Macrocyclic systems containing 2,6,9-trioxabicyclo[3.3.1]-nona-3,7-dienes as chiral spacer groups: Synthesis, stereochemical features and preliminary complexation properties

Novel 2:2-macrocycles bearing bridged concave 2,6,9-trioxabicyclo[3.3.1]nona-3,7-dienes as chiral spacer units were obtained by cyclocondensation reaction of the chiral bisacid chloride and the corresponding diols, while use of methylene diamines instead of diols afforded 1:1 macrocycles only. Applying the same, but now template-assisted, experimental procedure to the reaction of the bisacid chloride with triethylene glycol brought about a significant increase in yield as well as a suitable simplification of the work-up during preparation and separation of the corresponding 1:1 as well as 2:2 macrocycles, when compared to results reported previously. HPLC separation on chiral columns revealed the presence of diastereoisomers [RR(S,S)- and RS-(meso)-forms] for all 2:2 macrocycles, which was further evidenced by the CD spectrum of one of those species as an example. Preliminary ESI-MS experiments indicated strong complexation abilities of the sulphur-containing ligand towards Ag(I), Cu(II) and Au(III) ions.

The promotion and disruption of community service delivery systems

In this paper, we report data drawn from a larger project on the functioning of the Queensland community service delivery system, particularly that providing services to people with disabilities. Our reasoning for focusing at this level is that, from the service user's perspective, support is derived from the service delivery system, not just individual service providers. Defining the service delivery system as formal services and informal support networks, we undertook interviews and focus groups with service providers in six areas in Queensland: inner urban, outer urban, rural and remote. The period on which we report is one in which considerable reform activity had been undertaken by funding bodies of the Commonwealth and State governments. We report on those factors we identified which promote the integrated functioning of the service delivery system, as well as those factors that disrupt it. We conclude with a brief evaluative analysis of the current status of the system.

A multi-scaled approach for simulating chemical reaction systems

In this paper we give an overview of some very recent work, as well as presenting a new approach, on the stochastic simulation of multi-scaled systems involving chemical reactions. In many biological systems (such as genetic regulation and cellular dynamics) there is a mix between small numbers of key regulatory proteins, and medium and large numbers of molecules. In addition, it is important to be able to follow the trajectories of individual molecules by taking proper account of the randomness inherent in such a system. We describe different types of simulation techniques (including the stochastic simulation algorithm, Poisson Runge–Kutta methods and the balanced Euler method) for treating simulations in the three different reaction regimes: slow, medium and fast. We then review some recent techniques on the treatment of coupled slow and fast reactions for stochastic chemical kinetics and present a new approach which couples the three regimes mentioned above. We then apply this approach to a biologically inspired problem involving the expression and activity of LacZ and LacY proteins in E. coli, and conclude with a discussion on the significance of this work.

Merging of low-mass systems and the origin of the Fundamental Plane

We present a new set of dissipationless N-body simulations to examine the feasibility of creating bright ellipticals (following the Kormendy relation, hereafter KR) by hierarchically merging present-day early-type dwarf galaxies, and to study how the encounter parameters affect the location of the end product in the (mu(e))-R-e plane. We investigate the merging of one-component galaxies of both equal and different masses, the merging of two-component galaxy models to explore the effect of dark haloes on the final galaxy characteristics, and the merging of ultracompact dwarf galaxies. We find that the increase of (mu(e)) with R-e is attributable to an increase in the initial orbital energy. The merger remnants shift down in the (mu(e))-R-e plane and fail to reach the KR. Thus, the KR is not reproducible by mergers of dwarf early-type systems, rendering untenable the theory that present-day dwarfs are responsible for even a small fraction of the present-day ellipticals, unless a considerable amount of dissipation is invoked. However, we do find that present-day dwarfs can be formed by the merger of ultracompact dwarfs.