27,010 research outputs found
Radial density profiles of time-delay lensing galaxies
We present non-parametric radial mass profiles for ten QSO strong lensing
galaxies. Five of the galaxies have profiles close to ,
while the rest are closer to r^{-1}, consistent with an NFW profile. The former
are all relatively isolated early-types and dominated by their stellar light.
The latter --though the modeling code did not know this-- are either in
clusters, or have very high mass-to-light, suggesting dark-matter dominant
lenses (one is a actually pair of merging galaxies). The same models give
H_0^{-1} = 15.2_{-1.7}^{+2.5}\Gyr (H_0 = 64_{-9}^{+8} \legacy), consistent
with a previous determination. When tested on simulated lenses taken from a
cosmological hydrodynamical simulation, our modeling pipeline recovers both H_0
and within estimated uncertainties. Our result is contrary to some
recent claims that lensing time delays imply either a low H_0 or galaxy
profiles much steeper than r^{-2}. We diagnose these claims as resulting from
an invalid modeling approximation: that small deviations from a power-law
profile have a small effect on lensing time-delays. In fact, as we show using
using both perturbation theory and numerical computation from a
galaxy-formation simulation, a first-order perturbation of an isothermal lens
can produce a zeroth-order change in the time delays.Comment: Replaced with final version accepted for publication in ApJ; very
minor changes to text; high resolution figures may be obtained at
justinread.ne
Mapping the Australian Regulatory Environment: Implications for Construction Firms
As regulators, governments are often criticised for overâregulating industries. This research project seeks to examine the regulation affecting the construction industry in a federal system of government. It uses a case study of the Australian system of government to focus on the question of the implications of regulation in the construction industry. Having established the extent of the regulatory environment, the research project considers the costs associated with this environment. Consequently, ways in which the regulatory burden on industry can be reduced are evaluated. The Construction Industry Business Environment project is working with industry and government agencies to improve regulatory harmonisation in Australia, and thereby reduce the regulatory burden on industry. It is found that while taxation and compliance costs are not likely to be reduced in the short term, costs arising from having to adapt to variation between regulatory regimes in a federal system of government, seem the most promising way of reducing regulatory costs. Identifying and reducing adaptive costs across jurisdictional are argued to present a novel approach to regulatory reform
Asbestos Trust Transparency
Originally and for many years, the primary defendants in asbestos cases were companies that mined asbestos or manufactured amphibole-containing thermal insulation. Hundreds of thousands of claims were filed against the major asbestos producers, such as Johns-Manville Corp., Owens Corning Corp., and W.R. Grace & Co. By the late 1990s, asbestos litigation had reached such proportions that the U.S. Supreme Court noted the âelephantine massâ of cases and referred to the litigation as a âcrisis.â Mass filings pressured âmost of the lead defendants and scores of other companiesâ into bankruptcy, including virtually all manufacturers of asbestos-containing thermal insulation. Following a 2000â2002 wave of bankruptcies among asbestos manufacturers, plaintiffsâ lawyers began âa search for new recruits to fill the gap in the ranks of defendants.â Many of todayâs asbestos defendants are formerly peripheral or new defendants associated with chrysotile-containing products âsuch as gaskets, pumps, automotive friction products, and residential construction products.â One plaintiffsâ attorney described the asbestos litigation as an âendless search for a solvent bystander.â This Article argues for legislation, such as that enacted in many states, that requires asbestos plaintiffs to pursue quick compensation from the trusts and allows trust-related exposures and compensation to be properly accounted for in asbestos-related personal injury cases. States with substantial asbestos litigation, such as California, Illinois, New York, and Missouri, need the legislation the most
Global system of rivers: Its role in organizing continental land mass and defining landâtoâocean linkages
The spatial organization of the Earth\u27s land mass is analyzed using a simulated topological network (STNâ30p) representing potential flow pathways across the entire nonglacierized surface of the globe at 30âmin (longitude Ă latitude) spatial resolution. We discuss a semiautomated procedure to develop this topology combining digital elevation models and manual network editing. STNâ30p was verified against several independent sources including map products and drainage basin statistics, although we found substantial inconsistency within the extant literature itself. A broad suite of diagnostics is offered that quantitatively describes individual grid cells, river segments, and complete drainage systems spanning orders 1 through 6 based on the Strahler classification scheme. Continental and globalâscale summaries of key STNâ30p attributes are given. Summaries are also presented which distinguish basins that potentially deliver discharge to an ocean (exorheic) from those that potentially empty into an internal receiving body (endorheic). A total of 59,122 individual grid cells constitutes the global nonglacierized land mass. At 30âmin spatial resolution, the cells are organized into 33,251 distinct river segments which define 6152 drainage basins. A global total of 133.1 Ă 106 km2 bear STNâSOp flow paths with a total length of 3.24 Ă 106 km. The organization of river networks has an important role in linking land mass to ocean. From a continental perspective, lowâorder river segments (orders 1â3) drain the largest fraction of land (90%) and thus constitute a primary source area for runoff and constituents. From an oceanic perspective, however, the small number (n=101) of large drainage systems (orders 4â6) predominates; draining 65% of global land area and subsuming a large fraction of the otherwise spatially remote lowâorder rivers. Along river corridors, only 10% of land mass is within 100 km of a coastline, 25% is within 250 km, and 50% is within 750 km. The global mean distance to river mouth is 1050 km with individual continental values from 460 to 1340 km. The Mediterranean/Black Sea and Arctic Ocean are the most landâdominated of all oceans with land:ocean area ratios of 4.4 and 1.2, respectively; remaining oceans show ratios from 0.55 to 0.13. We discuss limitations of the STNâ30p together with its potential role in future global change studies. STNâ30p is geographically linked to several hundred river discharge and chemistry monitoring stations to provide a framework for calibrating and validating macroscale hydrology and biogeochemical flux models
Standardization of electroencephalography for multi-site, multi-platform and multi-investigator studies: Insights from the canadian biomarker integration network in depression
Subsequent to global initiatives in mapping the human brain and investigations of neurobiological markers for brain disorders, the number of multi-site studies involving the collection and sharing of large volumes of brain data, including electroencephalography (EEG), has been increasing. Among the complexities of conducting multi-site studies and increasing the shelf life of biological data beyond the original study are timely standardization and documentation of relevant study parameters. We presentthe insights gained and guidelines established within the EEG working group of the Canadian Biomarker Integration Network in Depression (CAN-BIND). CAN-BIND is a multi-site, multi-investigator, and multiproject network supported by the Ontario Brain Institute with access to Brain-CODE, an informatics platform that hosts a multitude of biological data across a growing list of brain pathologies. We describe our approaches and insights on documenting and standardizing parameters across the study design,
data collection, monitoring, analysis, integration, knowledge-translation, and data archiving phases of CAN-BIND projects. We introduce a custom-built EEG toolbox to track data preprocessing with open-access for the scientific community. We also evaluate the impact of variation in equipment setup on the accuracy of acquired data. Collectively, this work is intended to inspire establishing comprehensive and standardized guidelines for multi-site studies
Stability, Causality, and Passivity in Electrical Interconnect Models
Modern packaging design requires extensive signal integrity simulations in order to assess the electrical performance of the system. The feasibility of such simulations is granted only when accurate and efficient models are available for all system parts and components having a significant influence on the signals. Unfortunately, model derivation is still a challenging task, despite the extensive research that has been devoted to this topic. In fact, it is a common experience that modeling or simulation tasks sometimes fail, often without a clear understanding of the main reason. This paper presents the fundamental properties of causality, stability, and passivity that electrical interconnect models must satisfy in order to be physically consistent. All basic definitions are reviewed in time domain, Laplace domain, and frequency domain, and all significant interrelations between these properties are outlined. This background material is used to interpret several common situations where either model derivation or model use in a computer-aided design environment fails dramatically.We show that the root cause for these difficulties can always be traced back to the lack of stability, causality, or passivity in the data providing the structure characterization and/or in the model itsel
Reducing Biological Risks to Security: International Policy Recommendations for the Obama Administration
Summarizes discussions among biotechnology and life sciences experts on the risks of bioterrorism and threats to public health and agriculture. Assesses current efforts and makes recommendations for strengthening global prevention and response measures
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