13,252 research outputs found
Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey
We present luminosity and surface brightness distributions of 40,111 galaxies
with K-band photometry from the United Kingdom Infrared Telescope (UKIRT)
Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and
optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS).
Various features and limitations of the new UKIDSS data are examined, such as a
problem affecting Petrosian magnitudes of extended sources. Selection limits in
K- and r-band magnitude, K-band surface brightness and K-band radius are
included explicitly in the 1/Vmax estimate of the space density and luminosity
function. The bivariate brightness distribution in K-band absolute magnitude
and surface brightness is presented and found to display a clear
luminosity--surface brightness correlation that flattens at high luminosity and
broadens at low luminosity, consistent with similar analyses at optical
wavelengths. Best fitting Schechter function parameters for the K-band
luminosity function are found to be M*-5 log h=-23.19 +/- 0.04, alpha=-0.81 +/-
0.04 and phi*=(0.0166 +/- 0.0008)h^3 Mpc^{-3}, although the Schechter function
provides a poor fit to the data at high and low luminosity, while the
luminosity density in the K band is found to be j = (6.305 +/- 0.067) x 10^8
L_sun h Mpc^{-3}. However, we caution that there are various known sources of
incompleteness and uncertainty in our results. Using mass-to-light ratios
determined from the optical colours we estimate the stellar mass function,
finding good agreement with previous results. Possible improvements are
discussed that could be implemented when extending this analysis to the full
LAS.Comment: 17 pages, 24 figures, matches MNRAS accepted versio
A Bioeconomic Model for Management of Orange Roughy Stocks
The paper reports the results of a bioeconomic analysis of the exploitation of a recently discovered orange roughy stock located off Tasmania. The parameters of the model are based on the experience derived from the orange roughy fisheries in New Zealand where stocks have been heavily exploited. The model is used to predict the open-access equilibrium stock, and to calculate the stock which maximizes the net present value and the stock level consistent with the F,,, Rule. Assuming a linear approach path, the net present value of the fishery at each of these stocks is calculated. The results are used to estimate the benefit of management and the cost of a conservative stock policy. It is suggested that the results will contribute to the development of a management policy for the Tasmanian stock, and for stocks which are likely to be discovered elsewhereFishery management, bioeconomic model, orange roughy, Environmental Economics and Policy, Production Economics,
âDominant ethnicityâ and the âethnic-civicâ dichotomy in the work of A. D. Smith
This article considers the way in which the work of Anthony Smith has helped to structure debates surrounding the role of ethnicity in present-day nations. Two major lines of enquiry are evident here. First, the contemporary role of dominant ethnic groups within 'their' nations and second, the interplay between ethnic and civic elements in nationalist argument. The two processes are related, but maintain elements of distinctiveness. Smith's major contribution to the dominant ethnicity debate has been to disembed ethnicity from the ideologically-charged and/or anglo-centric discourse of ethnic relations and to place it in historical context, thereby opening up space for dominant group ethnicity to be considered as a distinct phenomenon. This said, Smith's work does not adequately account for the vicissitudes of dominant ethnicity in the contemporary West. Building on the classical works of Hans Kohn and Friedrich Meinecke, Anthony Smith has also made a seminal contribution to the debate on civic and ethnic forms of national identity and nationalist ideology. As well as freeing this debate from the strong normative overtones which it has often carried, he has continued to insist that the terms civic and ethnic should be treated as an ideal-typical distinction rather than a scheme of classification
The fragmentation of expanding shells III: Oligarchic accretion and the mass spectrum of fragments
We use SPH simulations to investigate the gravitational fragmentation of
expanding shells through the linear and non--linear regimes. The results are
analysed using spherical harmonic decomposition to capture the initiation of
structure during the linear regime; the potential-based method of Smith et al.
(2009) to follow the development of clumps in the mildly non-linear regime; and
sink particles to capture the properties of the final bound objects during the
highly non-linear regime. In the early, mildly non--linear phase of
fragmentation, we find that the clump mass function still agrees quite well
with the mass function predicted by the analytic model. However, the sink mass
function is quite different, in the sense of being skewed towards high-mass
objects. This is because, once the growth of a condensation becomes non-linear,
it tends to be growing non-competitively from its own essentially separate
reservoir; we call this Oligarchic Accretion.Comment: 14 pages, accepted for publication in MNRA
A discernable and manageable standard for partisan gerrymandering
The case of Veith v. Jubelirer (2004) challenges us to find a standard for partisan gerrymandering that is judicially discernable and manageable. Without such a standard even the most egregious partisan gerrymanders cannot be effectively challenged. However, we argue that the way to find a suitable standard is not to embark on a quest for a ânewâ standard. Rather it is to take the existing valid measures that science gives us, and show that these can be grounded in constitutionally protected rights. Using recent results in social choice theory, we show that the existing partisan symmetry standard can be derived from an individual right to equal protection. We also show that the existing technology for measuring partisan symmetry can provide a judicially manageable test for partisan bias
A metabolic model of the mitochondrion and its use in modelling diseases of the tricarboxylic acid cycle.
BACKGROUND: Mitochondria are a vital component of eukaryotic cells and their dysfunction is implicated in a large number of metabolic, degenerative and age-related human diseases. The mechanism or these disorders can be difficult to elucidate due to the inherent complexity of mitochondrial metabolism. To understand how mitochondrial metabolic dysfunction contributes to these diseases, a metabolic model of a human heart mitochondrion was created. RESULTS: A new model of mitochondrial metabolism was built on the principle of metabolite availability using MitoMiner, a mitochondrial proteomics database, to evaluate the subcellular localisation of reactions that have evidence for mitochondrial localisation. Extensive curation and manual refinement was used to create a model called iAS253, containing 253 reactions, 245 metabolites and 89 transport steps across the inner mitochondrial membrane. To demonstrate the predictive abilities of the model, flux balance analysis was used to calculate metabolite fluxes under normal conditions and to simulate three metabolic disorders that affect the TCA cycle: fumarase deficiency, succinate dehydrogenase deficiency and α-ketoglutarate dehydrogenase deficiency. CONCLUSION: The results of simulations using the new model corresponded closely with phenotypic data under normal conditions and provided insight into the complicated and unintuitive phenotypes of the three disorders, including the effect of interventions that may be of therapeutic benefit, such as low glucose diets or amino acid supplements. The model offers the ability to investigate other mitochondrial disorders and can provide the framework for the integration of experimental data in future studies.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Synoptic/planetary-scale interactions and blocking over the North Atlantic Ocean
The central theme of this project has been the diagnosis of blocking anticyclogenesis and the corresponding interactions with synoptic-scale circulations. To that end an extensive investigation of the dynamics and energetics of a major blocking anticyclone and two upstream cyclones, all of which occurred over the North Atlantic Ocean and the United States in January 1979, was undertaken. Data for the study were provided by Goddard Laboratory for Atmospheres (GLA) 4 LAT by 5 LON FGGE analyses. The methodology has primarily focused on the diagnosis of circulation forcing mechanisms using the modified forms (referred to as the extended forms) of the height tendency and Zwack-Okossi equations developed by our research group. Calculations use routine second-order finite differencing with boundary layer fraction and sensible heating and latent heat release represented as parameterized quantities. Of particular interest are the latent heat release estimates, which combine convectional parameterized values with estimates derived from satellite IR data. The latter were obtained using an algorithm derived by Dr. Franklin R. Robertson of NASA's Marshall Space Flight Center. Results are contained in project reports, theses and publications identified in previous review summaries and reports, and publications listed at the end of this summary. Significant accomplishments in the past year are presented
Gerrymandering the Presidency: Why Trump could lose the popular vote in 2020 by 6 percent and still win a second term.
Donald Trump was the clear Electoral College winner in the 2016 election, despite losing the popular vote by a wide margin to Hillary Clinton. Anthony J. McGann, Charles Anthony Smith, Michael Latner and Alex Keena write that, unless the Supreme Court stops congressional gerrymandering, President Trump can guarantee re-election in 2020 â even if he loses by 6 percent
Maryland's electoral maps show how proportional representation could solve the problem of gerrymandering
This week the US Supreme Court hears a case concerning the constitutionality of partisan gerrymandering in Maryland. Examining current, past, and alternative electoral maps, Alex Keena, Michael Latner, Anthony J. McGann, and Charles Anthony Smith find that by making districts more competitive, some redistricting plans can actually work against one party or the other. Only the introduction of proportional representation with multi-member districts, they argue, would mean a truly fair electoral system for Maryland
Containing the costs of Medicare: letter from British Columbia
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