Air and Water Pollution: A Visual Communication on Pollution

Not provided

Joseph Priestley

n/

A book of French poetry, from A.D. 1550 to the present time

XXII, 515 p

Bounds on the achromatic number of partial triple systems

A complete $k$-colouring of a hypergraph is an assignment of $k$ colours to the points such that (1) there is no monochromatic hyperedge, and (2) identifying any two colours produces a monochromatic hyperedge. The achromatic number of a hypergraph is the maximum $k$ such that it admits a complete $k$-colouring. We determine the maximum possible achromatic number among all maximal partial triple systems, give bounds on the maximum and minimum achromatic numbers of Steiner triple systems, and present a possible connection between optimal complete colourings and projective dimension

Temperature Influences Carbon Accumulation in Moist Tropical Forests

Evergreen broad-leaved tropical forests can have high rates of productivity and large accumulations of carbon in plant biomass and soils. They can therefore play an important role in the global carbon cycle, influencing atmospheric CO2 concentrations if climate warms. We applied meta-analyses to published data to evaluate the apparent effects of temperature on carbon fluxes and storages in mature, moist tropical evergreen forest ecosystems. Among forests, litter production, tree growth, and belowground carbon allocation all increased significantly with site mean annual temperature (MAT); total net primary productivity (NPP) increased by an estimated 0.2–0.7 Mg C·ha−1·yr−1·°C−1. Temperature had no discernible effect on the turnover rate of aboveground forest biomass, which averaged 0.014 yr−1 among sites. Consistent with these findings, forest biomass increased with site MAT at a rate of 5–13 Mg C·ha−1·°C−1. Despite greater productivity in warmer forests, soil organic matter accumulations decreased with site MAT, with a slope of −8 Mg C·ha−1·°C−1, indicating that decomposition rates of soil organic matter increased with MAT faster than did rates of NPP. Turnover rates of surface litter also increased with temperature among forests. We found no detectable effect of temperature on total carbon storage among moist tropical evergreen forests, but rather a shift in ecosystem structure, from low-biomass forests with relatively large accumulations of detritus in cooler sites, to large-biomass forests with relatively smaller detrital stocks in warmer locations. These results imply that, in a warmer climate, conservation of forest biomass will be critical to the maintenance of carbon stocks in moist tropical forests

Internalization and recycling of activated thrombin receptors

Shortly after activation by either thrombin or the tethered ligand domain peptide SFLLRN, thrombin receptors undergo homologous desensitization, temporarily losing their ability to respond to both agonists. We have examined the role of receptor internalization and recycling in this process using receptor-directed antibodies as probes. The results show within 1 min of activation >85% of the approximately 200,000 thrombin receptors on megakaryoblastic human erythroleukemia (HEL) and CHRF-288 cells are sequestered into endosomes via coated pits, after which the majority are transferred to lysosomes. This process does not require proteolysis of the receptor and occurs with sufficient speed to play a major role in the regulation of thrombin receptor function. Although most of the internalized receptors are ultimately degraded, approximately 25% return to the cell surface. These recycled receptors are in a state in which they can respond to SFLLRN but not thrombin; nor do they self-activate despite the apparent continued presence of the tethered ligand. In contrast to other G protein-coupled receptors, which are internalized and then recycled in an activatable state, recovery of the thrombin response occurs only after the expression on the cell surface of adequate numbers of newly synthesized receptors

Children, family and the state : revisiting public and private realms

The state is often viewed as part of the impersonal public sphere in opposition to the private family as a locus of warmth and intimacy. In recent years this modernist dichotomy has been challenged by theoretical and institutional trends which have altered the relationship between state and family. This paper explores changes to both elements of the dichotomy that challenge this relationship: a more fragmented family structure and more individualised and networked support for children. It will also examine two new elements that further disrupt any clear mapping between state/family and public/private dichotomies: the third party role of the child in family/state affairs and children's application of virtual technology that locates the private within new cultural and social spaces. The paper concludes by examining the rise of the 'individual child' hitherto hidden within the family/state dichotomy and the implications this has for intergenerational relations at personal and institutional levels

Hole Dynamics in Polymer Langmuir Films

This article develops a model for the closing of a gaseous hole in a liquid domain within a two-dimensional fluid layer coupled to a Stokesian subfluid substrate, and compares this model to experiments following hole dynamics in a polymer Langmuir monolayer. Closure of such a hole in a fluid layer is driven by the line tension at the hole boundary and the difference in surface pressure within the hole and far outside it. The observed rate of hole closing is close to that predicted by our model using estimates of the line tension obtained by other means, assuming that the surface pressure in the gas is negligible. This result both supports the model and suggests an independent means of determining the line tension. Unlike most previous hydrodynamics models of Langmuir films, the closing of a hole necessarily involves vertical motion of the underlying incompressible fluid. Fluid is dragged along with the liquid monolayer towards the center of the hole, and must plunge away from the surface. An explicit expression is found for this vertical fluid flow in the bulk substrate

Hybrid organic-inorganic nanoparticles: controlled incorporation of gold nanoparticles into virus-like particles and application in surface-enhanced Raman spectroscopy.

A capsid is the protein coat surrounding a virus' genome that ensures its protection and transport. The capsid of murine polyomavirus (muPy) consists of one major (VP1) and two minor (VP2/3) proteins, from which just VP1 is sufficient to form the capsid when expressed recombinantly (1). From a material engineering point of view, viral capsids are of interest because they present a paradigm for complex self-assembly on the nanometer scale. Understanding and controlling these assembly dynamics will allow the construction of nanoscale structures using a self-assembly process. The first step in this direction was the discovery that capsids of several viruses can be reversibly disassembled into their building blocks and reassembled using the same building blocks by simply changing the buffer conditions (2, 3). Such capsids already find applications as targeted in vivo delivery vectors for genes, proteins or small molecular drugs (4, 5), as optical probes for biomedical imaging and sensing purposes with unprecedented resolution and sensitivity and can potentially be used as templates for nanoelectronics (6, 7)

Action research and democracy

This contribution explores the relationship between research and learning democracy. Action research is seen as being compatible with the orientation of educational and social work research towards social justice and democracy. Nevertheless, the history of action research is characterized by a tension between democracy and social engineering. In the social-engineering approach, action research is conceptualized as a process of innovation aimed at a specific Bildungsideal. In a democratic approach action research is seen as research based on cooperation between research and practice. However, the notion of democratic action research as opposed to social engineering action research needs to be theorized. So called democratic action research involving the implementation by the researcher of democracy as a model and as a preset goal, reduces cooperation and participation into instruments to reach this goal, and becomes a type of social engineering in itself. We argue that the relationship between action research and democracy is in the acknowledgment of the political dimension of participation: ‘a democratic relationship in which both sides exercise power and shared control over decision-making as well as interpretation’. This implies an open research design and methodology able to understand democracy as a learning process and an ongoing experiment