Density-dependent decline of host abundance resulting from a new infectious disease

Although many new diseases have emerged within the past 2 decades [Cohen, M. L. (1998) Brit. Med. Bull. 54, 523–532], attributing low numbers of animal hosts to the existence of even a new pathogen is problematic. This is because very rarely does one have data on host abundance before and after the epizootic as well as detailed descriptions of pathogen prevalence [Dobson, A. P. & Hudson, P. J. (1985) in Ecology of Infectious Diseases in Natural Populations, eds. Grenfell, B. T. & Dobson, A. P. (Cambridge Univ. Press, Cambridge, U.K.), pp. 52–89]. Month by month we tracked the spread of the epizootic of an apparently novel strain of a widespread poultry pathogen, Mycoplasma gallisepticum, through a previously unknown host, the house finch, whose abundance has been monitored over past decades. Here we are able to demonstrate a causal relationship between high disease prevalence and declining house finch abundance throughout the eastern half of North America because the epizootic reached different parts of the house finch range at different times. Three years after the epizootic arrived, house finch abundance stabilized at similar levels, although house finch abundance had been high and stable in some areas but low and rapidly increasing in others. This result, not previously documented in wild populations, is as expected from theory if transmission of the disease was density dependent.

Estrogen receptor-dependent sexual differentiation of dopaminergic neurons in the preoptic region of the mouse

Although it has been known for some time that estrogen exerts a profound influence on brain development a definitive demonstration of the role of the classical estrogen receptor (ERα) in sexual differentiation has remained elusive. In the present study we used a sexually dimorphic population of dopaminergic neurons in the anteroventral periventricular nucleus of the hypothalamus (AVPV) to test the dependence of sexual differentiation on a functional ERα by comparing the number of tyrosine hydroxylase (TH)-immunoreactive neurons in the AVPV of wild-type (WT) mice with that of mice in which the ERα had been disrupted by homologous recombination (ERKOα). Only a few ERα-immunoreactive neurons were detected in the AVPV of ERKOα mice, and the number of TH-immunoreactive neurons was three times that of WT mice, suggesting that disruption of the ERα gene feminized the number of TH-immunoreactive neurons. In contrast, the AVPV contains the same number of TH-immunoreactive neurons in testicular feminized male mice as in WT males, indicating that sexual differentiation of this population of neurons is not dependent on an intact androgen receptor. The number of TH-immunoreactive neurons in the AVPV of female ERKOα mice remained higher than that of WT males, but TH staining appeared to be lower than that of WT females. Thus, the sexual differentiation of dopamine neurons in the AVPV appears to be receptor specific and dependent on the perinatal steroid environment.

Cholesterol homeostasis in human brain: evidence for an age-dependent flux of 24S-hydroxycholesterol from the brain into the circulation.

We have investigated whether side chain-hydroxylated cholesterol species are important for elimination of cholesterol from the brain. Plasma concentrations of 24-hydroxycholesterol (24-OH-Chol) in the internal jugular vein and the brachial artery in healthy volunteers were consistent with a net flux of this steroid from the brain into the circulation, corresponding to elimination of approximately 4 mg cholesterol during a 24-h period in adults. Results of experiments with rats exposed to 18O2 were also consistent with a flux of 24-OH-Chol from the brain into the circulation. No other oxysterol measured showed a similar behavior as 24-OH-Chol. These results and the finding that the concentration of 24-OH-Chol was 30- to 1500-fold higher in the brain than in any other organ except the adrenals indicate that the major part of 24-OH-Chol present in the circulation originates from the brain. Both the 24-OH-Chol present in the brain and in the circulation were the 24S-stereoisomer. In contrast to other oxysterols, levels of plasma 24-OH-Chol were found to be markedly dependent upon age. The ratio between 24-OH-Chol and cholesterol in plasma was approximately 5 times higher during the first decade of life than during the sixth decade. There was a high correlation between levels of 24-OH-Chol in plasma and cerebrospinal fluid. It is suggested that the flux of 24-OH-Chol from the brain is important for cholesterol homeostasis in this organ.

Challenges for the European Union in times of crisis: reactions

Since the beginning of its existence in the form of communities, this entity faced a lot of challenges that could had been stopped the European dream without the fast, prompt and appropriate reaction of the decision makers. There were a lot of difficult times in its history of more than 60 years but the ambition and need of going forward on the way of integration prevailed and today we can talk about European Union as one of the most important global players, having one of the most complex and fascinating political systems. The tenacity and the willing to succeed off the decision makers made this possible. Moments like “The Empty Chair Crisis“, changes with regards to the decision- making process, convenient for ones but inconvenient for the others, lack of consensus with regards to the new accessions, the big changes that Europe went through in the late 80s etc. showed that the decision makers can have an appropriate response whatever the problem would be and that we must stay together and go on dreaming to a united nation in the form of a federation. Nowadays we are facing maybe the most difficult moment in European Union history. Many of the member states were and still are on the edge. A lot of immediate and prompt actions were taken since the start of financial crisis, either political or economic, drove by the need of going on. We are too much into the integration process, too much dependent one of each other so that we cannot stop and simply go back only to the concept of national state.

Sir Francis Drake revived : who is or may be a pattern to stirre up all heroicke and active spirits of these times, to benefit their countrey and eternize their names by like noble attempts : Being a summary and true relation of foure severall voyages made by the said Sir Francis Drake to the West-Indies ... His voyage made with Chistopher Carleill, Martin Frobusher, Francis Knollis, and others, Their taking the townes of Saint Jago, Sancto Domingo, Carthagena and Saint Augustine : His last voyage (in which he dyed) being accompanied with Sir John Hawkins, Sir Thomas Baskerfield, Sir Nicholas Clifford, with others : His manner of buriall /

La primera obra relata el viaje de 1572-1573, la segunda el viaje de 1577-1580, la tercera el de 1585-1586 y la última del viaje de 1595-1596, en el que murió.

Modulation of higher-plant NAD(H)-dependent glutamate dehydrogenase activity in transgenic tobacco via alteration of beta subunit levels

Glutamate dehydrogenase (GDH; EC 1.4.1.2-1.4.1.4) catalyses in vitro the reversible amination of 2-oxoglutarate to glutamate. In vascular plants the in vivo direction(s) of the GDH reaction and hence the physiological role(s) of this enzyme remain obscure. A phylogenetic analysis identified two clearly separated groups of higher-plant GDH genes encoding either the alpha- or beta-subunit of the GDH holoenzyme. To help clarify the physiological role(s) of GDH, tobacco (Nicotiana tabacum L.) was transformed with either an antisense or sense copy of a beta-subunit gene, and transgenic plants recovered with between 0.5- and 34-times normal leaf GDH activity. This large modulation of GDH activity (shown to be via alteration of beta-subunit levels) had little effect on leaf ammonium or the leaf free amino acid pool, except that a large increase in GDH activity was associated with a significant decrease in leaf Asp (similar to 51%, P=0.0045). Similarly, plant growth and development were not affected, suggesting that a large modulation of GDH beta-subunit titre does not affect plant viability under the ideal growing conditions employed. Reduction of GDH activity and protein levels in an antisense line was associated with a large increase in transcripts of a beta-subunit gene, suggesting that the reduction in beta-subunit levels might have been due to translational inhibition. In another experiment designed to detect post-translational up-regulation of GDH activity, GDH over-expressing plants were subjected to prolonged dark-stress. GDH activity increased, but this was found to be due more likely to resistance of the GDH protein to stress-induced proteolysis, rather than to post-translational up-regulation.

Towards an ethics of engagement in education in global times

Starting from the observation that patterns of educational inequality are widely known but largely invisible in public debates on education, this article argues for the importance of an ethics of education which challenges simple acceptance of 'things as they are'. It suggests possibilities for working with discourses of ethics, rights and citizenship in contingent and strategic ways, and argues for the importance of engaging ethically across difference in current global times. It proposes three interrelated dimensions for an ethics of engagement in education: an ethics of commitment to intellectual rigour; an ethics of civility; and an inter-human ethics of care.

Packing-dependent pore structure in single-walled carbon nanotube arrays

Based on a self-similar array model of single-walled carbon nanotubes (SWNTs), the pore structure of SWNT bundles is analyzed and compared with that obtained from the conventional triangular model and adsorption experimental results. In addition to the well known cylindrical endo-cavities and interstitial pores, two types of newly defined pores with diameters of 2-10 and 8-100 nm are proposed, inter-bundle pores and inter-array pores. In particular, the relationship between the packing configuration of SWNTs and their pore structures is systematically investigated. (c) 2005 American Institute of Physics.

The growing importance of inter-company collaboration

Guest editorial: This special issue has been drawn from papers that were published as part of the Second European Conference on Management of Technology (EuroMOT) which was held at Aston Business School (Birmingham, UK) 10-12 September 2006. This was the official European conference for the International Association for Management of Technology (IAMOT); the overall theme of the conference was “Technology and global integration.” There were many high-calibre papers submitted to the conference and published in the associated proceedings (Bennett et al., 2006). The streams of interest that emerged from these submissions were the importance of: technology strategy, innovation, process technologies, managing change, national policies and systems, research and development, supply chain technology, service and operational technology, education and training, small company incubation, technology transfer, virtual operations, technology in developing countries, partnership and alliance, and financing and investment. This special issue focuses upon the streams of interest that accentuate the importance of collaboration between different organisations. Such organisations vary greatly in character; for instance, they may be large or small, publicly or privately owned, and operate in manufacturing or service sectors. Despite these varying characteristics they all have something in common; they all stress the importance of inter-organisational collaboration as a critical success factor for their organisation. In today's global economy it is essential that organisations decide what their core competencies are what those of complementing organisations are. Core competences should be developed to become a bases of differentiation, leverage and competitive advantage, whilst those that are less mature should be outsourced to other organisations that can claim to have had more recognition and success in that particular core competence (Porter, 2001). This strategic trend can be observed throughout advanced economies and is growing strongly. If a posteriori reasoning is applied here it follows that organisations could continue to become more specialised in fewer areas whilst simultaneously becoming more dependent upon other organisations for critical parts of their operations. Such actions seem to fly in the face of rational business strategy and so the question must be asked: why are organisations developing this way? The answer could lie in the recent changes in endogenous and exogenous factors of the organisation; the former emphasising resource-based issues in the short-term, and strategic positioning in the long-term whilst the later emphasises transaction costs in the short-term and acquisition of new skills and knowledge in the long-term. For a harmonious balance of these forces to prevail requires organisations to firstly declare a shared meta-strategy, then to put some cross-organisational processes into place which have their routine operations automated as far as possible. A rolling business plan would review, assess and reposition each organisation within this meta-strategy according to how well they have contributed (Binder and Clegg, 2006). The important common issue here is that an increasing number of businesses today are gaining direct benefit from increasing their levels of inter-organisational collaboration. Such collaboration has largely been possible due to recent technological advances which can make organisational structures more agile (e.g. the extended or the virtual enterprise), organisational infra-structure more connected, and the sharing of real-time information an operational reality. This special issue consists of research papers that have explored the above phenomenon in some way. For instance, the role of government intervention, the use of internet-based technologies, the role of research and development organisations, the changing relationships between start-ups and established firms, the importance of cross-company communities of practice, the practice of networking, the front-loading of large-scale projects, innovation and the probabilistic uncertainties that organisations experience are explored in these papers. The cases cited in these papers are limited as they have a Eurocentric focus. However, it is hoped that readers of this special issue will gain a valuable insight into the increasing importance of collaborative practices via these studies.

The missing ingredient:inter-municipal cooperation and central-local relations in the UK

The thrust of the argument presented in this chapter is that inter-municipal cooperation (IMC) in the United Kingdom reflects local government's constitutional position and its exposure to the exigencies of Westminster (elected central government) and Whitehall (centre of the professional civil service that services central government). For the most part councils are without general powers of competence and are restricted in what they can do by Parliament. This suggests that the capacity for locally driven IMC is restricted and operates principally within a framework constructed by central government's policy objectives and legislation and the political expediencies of the governing political party. In practice, however, recent examples of IMC demonstrate that the practices are more complex than this initial analysis suggests. Central government may exert top-down pressures and impose hierarchical directives, but there are important countervailing forces. Constitutional changes in Scotland and Wales have shifted the locus of central- local relations away from Westminster and Whitehall. In England, the seeding of English government regional offices in 1994 has evolved into an important structural arrangement that encourages councils to work together. Within the local government community there is now widespread acknowledgement that to achieve the ambitious targets set by central government, councils are, by necessity, bound to cooperate and work with other agencies. In recent years, the fragmentation of public service delivery has affected the scope of IMC. Elected local government in the UK is now only one piece of a complex jigsaw of agencies that provides services to the public; whether it is with non-elected bodies, such as health authorities, public protection authorities (police and fire), voluntary nonprofit organisations or for-profit bodies, councils are expected to cooperate widely with agencies in their localities. Indeed, for projects such as regeneration and community renewal, councils may act as the coordinating agency but the success of such projects is measured by collaboration and partnership working (Davies 2002). To place these developments in context, IMC is an example of how, in spite of the fragmentation of traditional forms of government, councils work with other public service agencies and other councils through the medium of interagency partnerships, collaboration between organisations and a mixed economy of service providers. Such an analysis suggests that, following changes to the system of local government, contemporary forms of IMC are less dependent on vertical arrangements (top-down direction from central government) as they are replaced by horizontal modes (expansion of networks and partnership arrangements). Evidence suggests, however that central government continues to steer local authorities through the agency of inspectorates and regulatory bodies, and through policy initiatives, such as local strategic partnerships and local area agreements (Kelly 2006), thus questioning whether, in the case of UK local government, the shift from hierarchy to network and market solutions is less differentiated and transformation less complete than some literature suggests. Vertical or horizontal pressures may promote IMC, yet similar drivers may deter collaboration between local authorities. An example of negative vertical pressure was central government's change of the systems of local taxation during the 1980s. The new taxation regime replaced a tax on property with a tax on individual residency. Although the community charge lasted only a few years, it was a highpoint of the then Conservative government policy that encouraged councils to compete with each other on the basis of the level of local taxation. In practice, however, the complexity of local government funding in the UK rendered worthless any meaningful ambition of councils competing with each other, especially as central government granting to local authorities is predicated (however imperfectly) on at least notional equalisation between those areas with lower tax yields and the more prosperous locations. Horizontal pressures comprise factors such as planning decisions. Over the last quarter century, councils have competed on the granting of permission to out-of-town retail and leisure complexes, now recognised as detrimental to neighbouring authorities because economic forces prevail and local, independent shops are unable to compete with multiple companies. These examples illustrate tensions at the core of the UK polity of whether IMC is feasible when competition between local authorities heightened by local differences reduces opportunities for collaboration. An alternative perspective on IMC is to explore whether specific purposes or functions promote or restrict it. Whether in the principle areas of local government responsibilities relating to social welfare, development and maintenance of the local infrastructure or environmental matters, there are examples of IMC. But opportunities have diminished considerably as councils lost responsibility for services provision as a result of privatisation and transfer of powers to new government agencies or to central government. Over the last twenty years councils have lost their role in the provision of further-or higher-education, public transport and water/sewage. Councils have commissioning power but only a limited presence in providing housing needs, social care and waste management. In other words, as a result of central government policy, there are, in practice, currently far fewer opportunities for councils to cooperate. Since 1997, the New Labour government has promoted IMC through vertical drivers and the development; the operation of these policy initiatives is discussed following the framework of the editors. Current examples of IMC are notable for being driven by higher tiers of government, working with subordinate authorities in principal-agent relations. Collaboration between local authorities and intra-interand cross-sectoral partnerships are initiated by central government. In other words, IMC is shaped by hierarchical drivers from higher levels of government but, in practice, is locally varied and determined less by formula than by necessity and function. © 2007 Springer.

Higher-order co-occurrences for exploratory point pattern analysis and decision tree clustering on spatial data

Analyzing geographical patterns by collocating events, objects or their attributes has a long history in surveillance and monitoring, and is particularly applied in environmental contexts, such as ecology or epidemiology. The identification of patterns or structures at some scales can be addressed using spatial statistics, particularly marked point processes methodologies. Classification and regression trees are also related to this goal of finding "patterns" by deducing the hierarchy of influence of variables on a dependent outcome. Such variable selection methods have been applied to spatial data, but, often without explicitly acknowledging the spatial dependence. Many methods routinely used in exploratory point pattern analysis are2nd-order statistics, used in a univariate context, though there is also a wide literature on modelling methods for multivariate point pattern processes. This paper proposes an exploratory approach for multivariate spatial data using higher-order statistics built from co-occurrences of events or marks given by the point processes. A spatial entropy measure, derived from these multinomial distributions of co-occurrences at a given order, constitutes the basis of the proposed exploratory methods. © 2010 Elsevier Ltd.

Higher-order co-occurrences for exploratory point pattern analysis and decision tree clustering on spatial data

Analyzing geographical patterns by collocating events, objects or their attributes has a long history in surveillance and monitoring, and is particularly applied in environmental contexts, such as ecology or epidemiology. The identification of patterns or structures at some scales can be addressed using spatial statistics, particularly marked point processes methodologies. Classification and regression trees are also related to this goal of finding "patterns" by deducing the hierarchy of influence of variables on a dependent outcome. Such variable selection methods have been applied to spatial data, but, often without explicitly acknowledging the spatial dependence. Many methods routinely used in exploratory point pattern analysis are2nd-order statistics, used in a univariate context, though there is also a wide literature on modelling methods for multivariate point pattern processes. This paper proposes an exploratory approach for multivariate spatial data using higher-order statistics built from co-occurrences of events or marks given by the point processes. A spatial entropy measure, derived from these multinomial distributions of co-occurrences at a given order, constitutes the basis of the proposed exploratory methods. © 2010 Elsevier Ltd.

Studies of the effects of molecular encounters on N.M.R. spin-lattice relaxation times

This thesis is concerned with investigations of the effects of molecular encounters on nuclear magnetic resonance spin-lattice relaxation times, with particular reference to mesitylene in mixtures with cyclohexane and TMS. The purpose of the work was to establish the best theoretical description of T1 and assess whether a recently identified mechanism (buffeting), that influences n.m.r. chemical shifts, governs Tl also. A set of experimental conditions are presented that allow reliable measurements of Tl and the N. O. E. for 1H and 13C using both C. W. and F.T. n.m.r. spectroscopy. Literature data for benzene, cyclohexane and chlorobenzene diluted by CC14 and CS2 are used to show that the Hill theory affords the best estimation of their correlation times but appears to be mass dependent. Evaluation of the T1 of the mesitylene protons indicates that a combined Hill-Bloembergen-Purcell-Pound model gives an accurate estimation of T1; subsequently this was shown to be due to cancellation of errors in the calculated intra and intemolecular components. Three experimental methods for the separation of the intra and intermolecular relaxation times are described. The relaxation times of the 13C proton satellite of neat bezene, 1,4 dioxane and mesitylene were measured. Theoretical analyses of the data allow the calculation of Tl intra. Studies of intermolecular NOE's were found to afford a general method of separating observed T1's into their intra and intermolecular components. The aryl 1H and corresponding 13C T1 values and the NOE for the ring carbon of mesitylene in CC14 and C6H12-TMS have been used in combination to determine T1intra and T1inter. The Hill and B.P.P. models are shown to predict similarly inaccurate values for T1linter. A buffeting contribution to T1inter is proposed which when applied to the BPP model and to the Gutowsky-Woessner expression for T1inter gives an inaccuracy of 12% and 6% respectively with respect to theexperimentally based T1inter.

Inter-site and inter-scanner diffusion MRI data harmonization.

We propose a novel method to harmonize diffusion MRI data acquired from multiple sites and scanners, which is imperative for joint analysis of the data to significantly increase sample size and statistical power of neuroimaging studies. Our method incorporates the following main novelties: i) we take into account the scanner-dependent spatial variability of the diffusion signal in different parts of the brain; ii) our method is independent of compartmental modeling of diffusion (e.g., tensor, and intra/extra cellular compartments) and the acquired signal itself is corrected for scanner related differences; and iii) inter-subject variability as measured by the coefficient of variation is maintained at each site. We represent the signal in a basis of spherical harmonics and compute several rotation invariant spherical harmonic features to estimate a region and tissue specific linear mapping between the signal from different sites (and scanners). We validate our method on diffusion data acquired from seven different sites (including two GE, three Philips, and two Siemens scanners) on a group of age-matched healthy subjects. Since the extracted rotation invariant spherical harmonic features depend on the accuracy of the brain parcellation provided by Freesurfer, we propose a feature based refinement of the original parcellation such that it better characterizes the anatomy and provides robust linear mappings to harmonize the dMRI data. We demonstrate the efficacy of our method by statistically comparing diffusion measures such as fractional anisotropy, mean diffusivity and generalized fractional anisotropy across multiple sites before and after data harmonization. We also show results using tract-based spatial statistics before and after harmonization for independent validation of the proposed methodology. Our experimental results demonstrate that, for nearly identical acquisition protocol across sites, scanner-specific differences can be accurately removed using the proposed method.

Time-dependent Suppression of Oscillatory Power in Evolving Solar Magnetic Fields

Oscillation amplitudes are generally smaller within magnetically active regions like sunspots and plage when compared to their surroundings. Such magnetic features, when viewed in spatially resolved power maps, appear as regions of suppressed power due to reductions in the oscillation amplitudes. Employing high spatial- and temporal-resolution observations from the Dunn Solar Telescope (DST) in New Mexico, we study the power suppression in a region of evolving magnetic fields adjacent to a pore. By utilizing wavelet analysis, we study for the first time how the oscillatory properties in this region change as the magnetic field evolves with time. Image sequences taken in the blue continuum, G-band, Ca ii K, and Hα filters were used in this study. It is observed that the suppression found in the chromosphere occupies a relatively larger area, confirming previous findings. Also, the suppression is extended to structures directly connected to the magnetic region, and is found to get enhanced as the magnetic field strength increased with time. The dependence of the suppression on the magnetic field strength is greater at longer periods and higher formation heights. Furthermore, the dominant periodicity in the chromosphere was found to be anti-correlated with increases in the magnetic field strength.