The cloud-in-cloud problem for non-Gaussian density fields

The cloud-in-cloud problem is studied in the context of the extension to non-Gaussian density fields of the Press-Schechter approach for the calculation of the mass function. As an example of a non-Gaussian probability distribution functions (PDFs) we consider the Chi-square, with various degrees of freedom. We generate density fields in cubic boxes with periodic boundary conditions and then determine the number of points considered collapsed at each scale through an hierarchy of smoothing windows. We find that the mass function we obtain differs from that predicted using the Extended Press-Schechter formalism, particularly for low values of $\sigma$ and for those PDFs most distinct from a Gaussian.Comment: 5 pages, LaTex using mn.sty, matches published version, results for the Inverted Chi-square distribution withdraw

Icebergs in the North Atlantic: Modelling circulation changes and glacio-marine deposition

In order to investigate meltwater events in the North Atlantic, a simple iceberg generation, drift, and melting routine was implemented in a high-resolution OGCM. Starting from the modelled last glacial state, every 25th day cylindrical model icebergs 300 meters high were released at 32 specific points along the coasts. Icebergs launched at the Barents Shelf margin spread a light meltwater lid over the Norwegian and Greenland Seas, shutting down the deep convection and the anti-clockwise circulation in this area. Due to the constraining ocean circulation, the icebergs produce a tongue of relatively cold and fresh water extending eastward from Hudson Strait that must develop at this location, regardless of iceberg origin. From the total amount of freshwater inferred by the icebergs, the thickness of the deposited IRD could be calculated in dependance of iceberg sediment concentration. In this way, typical extent and thickness of Heinrich layers could be reproduced, running the model for 250 years of steady state with constant iceberg meltwater inflow

Hubble Space Telescope Images of Magellanic Cloud Planetary Nebulae: Data and Correlations across Morphological Classes

The morphology of planetary nebulae (PNe) provides an essential tool for understanding their origin and evolution, as it reflects both the dynamics of the gas ejected during the TP-AGB phase, and the central star energetics. Here we study the morphology of 27 Magellanic Cloud planetary nebulae (MCPNe) and present an analysis of their physical characteristics across morphological classes. Similar studies have been successfully carried out for galactic PNe, but were compromised by the uncertainty of individual PN distances. We present our own HST/FOC images of 15 Magellanic Cloud PNe (MCPNe) acquired through a narrow-band lambda 5007 [O III] filter. We use the Richardson-Lucy deconvolution technique on these pre-COSTAR images to achieve post-COSTAR quality. Three PNe imaged before and after COSTAR confirm the high reliability of our deconvolution procedure. We derive morphological classes, dimensions, and surface photometry for all these PNe. We have combined this sample with HST/PC1 images of 15 MCPNe, three of which are in common with the FOC set, acquired by Dopita et al. (1996), to obtain the largest MCPN sample ever examined from the morphological viewpoint. By using the whole database, supplemented with published data from the literature, we have analyzed the properties of the MCPNe and compared them to a typical, complete galactic sample. Morphology of the MCPNe is then correlated with PN density, chemistry, and evolution.Comment: text file lstanghe_mcpn.tex (LaTex); Figures 2 through 10, Figure 5 is in 3 parts (a,b,c); Figure 1 available by regular mail only; ApJ, in press, November 10, 199

Retuning the Catalytic Bias and Overpotential of a [NiFe]-Hydrogenase via a Single Amino Acid Exchange at the Electron Entry/Exit Site

The redox chemistry of the electron entry/exit site in Escherichia coli hydrogenase-1 is shown to play a vital role in tuning biocatalysis. Inspired by nature, we generate a HyaA-R193L variant to disrupt a proposed Arg-His cation-π interaction in the secondary coordination sphere of the outermost, "distal", iron-sulfur cluster. This rewires the enzyme, enhancing the relative rate of H 2 production and the thermodynamic efficiency of H 2 oxidation catalysis. On the basis of Fourier transformed alternating current voltammetry measurements, we relate these changes in catalysis to a shift in the distal [Fe 4S 4] 2+/1+ redox potential, a previously experimentally inaccessible parameter. Thus, metalloenzyme chemistry is shown to be tuned by the second coordination sphere of an electron transfer site distant from the catalytic center

Space of opposition: activism and deliberation in post-apartheid environmental politics

Drawing on recent political theory that examines the relationship between inclusive deliberation and oppositional activism in processes of democratisation, we develop a case study of environmental justice mobilisation in post-apartheid South Africa. We focus on the emergence of a network of social movement organisations embedded in particular localities in the city of Durban, connected into national and transnational campaigns, and centred on grievances around industrial air pollution. We analyse how the geographies of uneven industrial and urban development in Durban combine with sedimented place-based histories of activism to make particular locations spaces of democratic contention, in which the scope and operation of formal democratic procedures are challenged and transformed. We examine the range of strategic engagements adopted by social movement organisations in pursuing their objectives, looking in particular at the dynamic interaction between inclusion in deliberative forums and more adversarial, activist strategies of legal challenge and dramaturgical protest. We identify the key organisational features of groups involved in this environmental justice network, which both enable and constrain particular patterns of democratic engagement with the state and capital. We also identify a disjuncture between the interpretative frames of different actors involved in participatory policy making. These factors help to explain the difficulties faced by social movement organisations in opening up the space for legitimate nonparliamentary opposition in a political culture shaped by norms of conciliation and consensus

Patients' and carers' views on communication and information provision when undergoing assessments in memory services

Objectives: To explore patients' and carers' views on what constitutes high-quality communication and information provision during diagnostic assessment in memory clinic services in three areas of England. Methods: Interviews with 27 people with cognitive impairment (13 with confirmed dementia) and 26 carers (20 matched pairs). Interviews continued until theoretical saturation was reached. Interview transcripts were subject to constant comparative analysis; data interpretation occurred in 'data clinics'. Results: People with memory problems undergoing assessment often have unmet information needs, especially patients with a diagnosis other than Alzheimer's disease and those who do not receive a diagnosis. Patients wish to be kept informed about both the assessment and its outcomes. Some have unrealistic expectations of the process (expecting assessment and diagnosis to be complete in two weeks) and some experience what appear to be long delays (over 12 months) in receiving results. Most appreciated clear and honest communication about any diagnosis. Post-diagnostic groups, organized by local memory services, afford opportunities to learn practical strategies and gain informal peer support. Voluntary organizations may be an essential source of information. Conclusions: Communication and information need improvement for patients undergoing assessment for possible dementia, especially for those considered unlikely to benefit from medication and those with mild cognitive impairment. © The Author(s) 2013

An Attempt to Determine the Largest Scale of Primordial Density Perturbations in the Universe

Inflationary cosmology predicts that the particle horizon should be generically much bigger than the present-day Hubble radius, $1/H_0$. This implies a special regime of super-Hubble scale energy density fluctuations imprinted on the cosmic microwave background radiation (CMBR), which from present theory could only be explained by inflation Causality constraints are used to determine models for the power spectrum that accommodate a suppression scale. A three parameter likelihood analysis is performed of the COBE-DMR 4-year data with respect to the amplitude, spectral index, and suppression scale. It is found that all suppression length scales larger than $1/H_0$ are consistent with the data, but that scales of order $1/H_0$ are slightly preferred, at roughly the one-sigma level. Many non-inflation models would be consistent with a small suppression length scale, whereas for standard inflation models, the duration of the inflation epoch would have to be bounded by a fairly small upper limit. Suppression scales smaller than $1/H_0$ are strongly excluded by the anisotrophy data.Comment: 9 pages, Latex, 1 figure, additional tests reporte