213 research outputs found
The unrelaxed dynamical structure of the galaxy cluster Abell 85
For the first time, we explore the dynamics of the central region of a galaxy
cluster within ~kpc from its center by combining optical
and X-ray spectroscopy. We use (1) the caustic technique that identifies the
cluster substructures and their galaxy members with optical spectroscopic data,
and (2) the X-ray redshift fitting procedure that estimates the redshift
distribution of the intracluster medium (ICM). We use the spatial and redshift
distributions of the galaxies and of the X-ray emitting gas to associate the
optical substructures to the X-ray regions. When we apply this approach to
Abell 85 (A85), a complex dynamical structure of A85 emerges from our analysis:
a galaxy group, with redshift is passing through the
cluster center along the line of sight dragging part of the ICM present in the
cluster core; two additional groups, at redshift and
, are going through the cluster in opposite directions,
almost perpendicularly to the line of sight, and have substantially perturbed
the dynamics of the ICM. An additional group in the outskirts of A85, at
redshift , is associated to a secondary peak of the X-ray
emission, at redshift . Although our analysis and
results on A85 need to be confirmed by high-resolution spectroscopy, they
demonstrate how our new approach can be a powerful tool to constrain the
formation history of galaxy clusters by unveiling their central and surrounding
structures.Comment: 12 pages, 11 figures, accepted by Ap
âGreenâ Transportation Taxes and Fees: A Survey Of Californians, MTI Report 08-05
This report explores public opinion on a new and promising conceptâgreen transportation taxes and fees. These are taxes and fees set at variable rates, with higher rates for more polluting vehicles and lower rates for those that pollute less. This approach to transportation taxes and fees adapts the traditional transportation finance system to achieve two critical public benefits at once: encouraging drivers to choose more environmentally-friendly transportation options and raising revenue for needed transportation programs. To test public support for green transportation taxes and fees, the authors conducted a random telephone survey of 1,500 Californians that asked respondents their views on five hypothetical tax and fee options: a flat-rate and a green vehicle registration fee, a flat-rate and a green mileage fee, and a âfeebateâ program for new vehicle purchases under which more-polluting vehicles would be charged a tax and less-polluting vehicles would receive a rebate. The survey results show that the concept of green transportation taxes and fees strongly appeals to Californians. The survey tested this in two ways: by testing support for the three hypothetical green transportation tax and fee policies, and also by comparing support levels for flat-rate versus green versions of two taxes. Majorities of the respondents supported all three green taxes and fees tested. Another striking finding from the survey is that support for the green taxes and fees did not vary greatly by population subgroups; a diverse range of Californians supported the green taxes and fees. An analysis comparing support for the green and flat-rate vehicle registration fee and feebate proposals confirmed that in every subgroup, more people within that subgroup supported the green than the flat version of the two taxes tested
Human response to vibration in residential environments (NANR209), Technical report 6 : determination of exposure-response relationships
This technical report presents the development of exposure-response relationships for the human response to vibration in residential environments. The data used to formulate the relationships presented in this report are those which were collected for the Defra funded project âNANR209: Human response to vibration in residential environmentsâ, the main aim of which was the development of exposure-response relationships. Vibration caused by railway traffic, construction work, and internal sources outside of the residentsâ control were considered. Response data was collected via face to face interviews with residents in their own homes. The questionnaire was presented as a neighbourhood satisfaction survey and gathered information on, among other things, annoyance caused by vibration and noise exposure. Development and implementation of the questionnaire used for the collection of response data is discussed in Technical Report 2 and Technical Report 5. Vibration exposure was determined via measurement and prediction in such a way that, where possible, an estimation of internal vibration exposure was established for each residence in which a questionnaire was completed. The measurement procedures and methods employed to estimate vibration exposure are detailed in Technical Report 1 and Technical Report 3. Estimations of noise exposure were also derived for each residence using the methods detailed in Technical Report 4
Potential Biomass Yields in the South Central US
This paper describes research to create a national database of switchgrass supply as part of the biomass program launched by the Department of Energy. The paper provides an estimate of county level switchgrass yield data for the state of Oklahoma. The estimates are made for the top five most productive and abundant soils for each county in Oklahoma. A simple approach of ratio calculation and estimation is used to predict the switchgrass yield of one soil type by comparing it with the yield of several other crops in another soil type. The data for switchgrass yield for a particular soil type are obtained from the state research experiment stations. The yields for other crops for the top five soils are obtained from the NASS data sources. Switchgrass supply for Oklahoma was estimated to be 49.5 million tons from the top soils with the Northeast crop reporting district to be the dominant supplier.Biofuel, Switchgrass, Ratio Estimation, South Central, Oklahoma, Agricultural and Food Policy, Crop Production/Industries, Environmental Economics and Policy, Production Economics, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies, Resource /Energy Economics and Policy,
Efficiency Gains from "What"-Flexibility in Climate Policy: An Integrated CGE Assessment
We investigate the importance of ?what?-flexibility on top of ?where?- and ?when?-flexibility for alternative emission control schemes that prescribe long-term temperature targets and eventually impose additional constraints on the rate of temperature change. We find that ?what?-flexibility substantially reduces the compliance costs under alternative emission control schemes. When comparing policies that simply involve long-term temperature targets against more stringent strategies that include additional constraints on the rate of temperature increase, it turns out that the latter involve huge additional costs. These costs may be interpreted as additional insurance payments if damages should not only dependent on absolute temperature change but also on the rate of temperature change. --Climate policy,Integrated Assessment,What-flexibility
Institutional Choice and Targeted Killing: A Comparative Perspective
For over a decade, the use of targeted killing has been one of the most controversial issues in counterterrorism policy and law. One longstanding debate over this tactic concerns the allocation of decision-making and oversight authority among the branches of government. As attempts to settle this debate through textual and historical sources yield indeterminant answers, scholars tend to examine them through a functionalist prism, asking what institutional structures best serve the interests of national security while ensuring adequate accountability and preventing unnecessary force.
This article, retaining that functionalist framing of that issue, will approach the question through a comparative law analysis. Three of the countries most heavily engaged in global counterterrorismâthe U.S., the U.K., and Israelâhave adopted substantially different approaches for regulating counterterrorism targeting, each according a primary supervisory role to a different governmental actor: the Executive in the U.S., Parliament in the U.K., and the Judiciary in Israel. This article describes, compares, and critically analyzes these approaches. Drawing on comparative institutional analysis theory, it then examines the findings and reaches three main conclusions. First, that in light of the judiciaryâs unique structural perspective and expertise, some judicial involvement in developing the legal standard that guides and constrains government action is desirable. Second, that suboptimal decision-making and illegality due to executive bias are more likely to occur where the executive is accountable only to its own internal oversight mechanisms. And third, that in both presidential and parliamentarian systems, legislators do not have and are unlikely to have any sort of meaningful influence on executive behavior in this domain. The article concludes by suggesting a few possible institutional reforms
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High-Power, High-Frequency, Annular-Beam Free-Electron Maser
The authors have developed a 15--17 GHz free electron maser (FEM) capable of producing high power pulses with a phase stability appropriate for linear collider applications. The electron beam source is a 1 {micro}s, 800 kV, 5 kA, 6-cm-dia annular electron beam machine called BANSHEE. The beam interacts with the TM{sub 02} mode Raman FEM amplifier in a corrugated cylindrical waveguide where the beam runs close to the interaction device walls to reduce the power density in the fields. They studied the phase stability by analyzing the dispersion relation for an axial FEL, in which the rf field was transversely wiggled and the electron trajectories were purely longitudinal. Detailed particle-in-cell simulations demonstrated the transverse wiggling of the rf mode and the axial FEL interaction and explicit calculations of the growing root of the dispersion relation are included to verify the phase stability
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