1,349 research outputs found
Discovery of 21cm absorption in a DLA towards TXS 0311+430: The first low spin temperature absorber at z > 1
We report the detection of HI 21 cm absorption from the damped
Lyman- system (DLA) towards TXS 0311+430, with the Green Bank
Telescope. The 21 cm absorption has a velocity spread (between nulls) of km s and an integrated optical depth of km s. We also present new Giant Metrewave Radio
Telescope 602 MHz imaging of the radio continuum. TXS 0311+430 is unresolved at
this frequency, indicating that the covering factor of the DLA is likely to be
high. Combining the integrated optical depth with the DLA HI column density of
\nhi = \cm, yields a spin temperature of K, assuming a covering factor of unity. This is the first case of
a low spin temperature ( DLA and is among the lowest
ever measured in any DLA. Indeed, the measured for this DLA is similar to
values measured in the Milky Way and local disk galaxies. We also determine a
lower limit (Si/H) solar for the DLA metallicity, amongst the
highest abundances measured in DLAs at any redshift. Based on low redshift
correlations, the low , large 21 cm absorption width and high metallicity
all suggest that the DLA is likely to arise in a massive,
luminous disk galaxy.Comment: 5 pages, 3 figures. Accepted for publication in MNRAS (Letters
Paths to Statistical Fluency for Ecologists
Twenty-first century ecology requires statistical fluency. Observational and experimental studies routinely gather non-Normal, multivariate data at many spatiotemporal scales. Experimental studies routinely include multiple blocked and nested factors. Ecological theories
routinely incorporate both deterministic and stochastic processes. Ecological debates frequently revolve around choices of statistical analyses. Our journals are replete with likelihood and state-space models, Bayesian and frequentist inference, complex multivariate analyses, and papers on
statistical theory and methods. We test hypotheses, model data, and forecast future environmental conditions. And many appropriate statistical methods are not automated in software packages. It is time for ecologists to understand statistical modeling well enough to construct nonstandard statistical models and apply various types of inference – estimation, hypothesis testing, model selection, and prediction – to our models and scientific questions. In short, ecologists need to
move beyond basic statistical literacy and attain statistical fluency.Organismic and Evolutionary Biolog
Diffuse Interstellar Bands in z < 0.6 CaII Absorbers
The diffuse interstellar bands (DIBs) probably arise from complex organic
molecules whose strength in local galaxies correlates with neutral hydrogen
column density, N(HI), and dust reddening, E(B-V). Since CaII absorbers in
quasar (QSO) spectra are posited to have high N(HI) and significant E(B-V),
they represent promising sites for the detection of DIBs at cosmological
distances. Here we present the results from the first search for DIBs in 9
CaII-selected absorbers at 0.07 < z_abs < 0.55. We detect the 5780Ang DIB in
one line of sight at z_abs = 0.1556; this is only the second QSO absorber in
which a DIB has been detected. Unlike the majority of local DIB sight-lines,
both QSO absorbers with detected DIBs show weak 6284Ang absorption compared
with the 5780Ang band. This may be indicative of different physical conditions
in intermediate redshift QSO absorbers compared with local galaxies. Assuming
that local relations between the 5780Ang DIB strength and N(HI) and E(B-V)
apply in QSO absorbers, DIB detections and limits can be used to derive N(HI)
and E(B-V). For the one absorber in this study with a detected DIB, we derive
E(B-V) = 0.23mag and log[N(HI)] >= 20.9, consistent with previous conclusions
that CaII systems have high HI column densities and significant reddening. For
the remaining 8 CaII-selected absorbers with 5780Ang DIB non-detections, we
derive E(B-V) upper limits of 0.1-0.3mag.Comment: 5 pages, 2 figures. Accepted to MNRAS Letter
The advocacy coalition framework and implementation of the Endangered Species Act: a case study in Western water politics
Theories about subsystem activity typically focus on policy formulation processes. One causal model of public policymaking, the advocacy coalition framework, offers a potentially useful way to bridge the gap between policy formulation and implementation in examining subsystem activity. The purpose of this paper is to assess the analytical utility of the advocacy coalition framework by examining the stability of policy-producing coalitions over time in the face of implementation complexities. An analysis of the policy changes that occurred during the implementation of the Endangered Species Act vis-a-vis planning for the construction of the Bureau of Reclamation's Animas-La Plata water project is conducted. The analysis reveals how coalitions protect their policy core beliefs during technical disputes through the acquiescence of secondary aspects of belief systems
Intergovernmental relations and the advocacy coalition framework: the operation of federalism in Denver water politics.
The relationship between intergovernmental relations and the formulation and implementation of public policies is not well understood by scholars. Borrowing from the advocacy coalition framework, this study contends that public policies reflect the strategic choices of federal, state, and local actors operating within policy subsystems. The success of various governmental policy strategies is dependent on the autonomy of each actor and the level of policy fragmentation within the subsystem. These variables are defined, operationalized, and examined within the context of intergovernmental relations in Denver water politics
A conceptual framework for analyzing bureaucratic politics and autonomy
Although many scholars recognize that bureaucracy plays a fundamental role in governing, few have systematically examined how agencies use their resources to achieve their goals. The conflicts inherent in the use of the term "bureaucratic power" to describe an agency's ability to accomplish its objectives is one reason for this deficiency. I suggest, based on the work of several scholars, that the concept of agency autonomy is a better mechanism for explaining bureaucratic behavior. In this paper, I develop a conceptual framework of bureaucratic politics and autonomy. The conceptual framework is composed of two independent variables--expertise and constituency support-plus two intervening variables--organizational vitality and leadership. I define the dependent variable, autonomy, and present indicators. Finally, I discuss each variable and propose hypotheses
Building the Reservoir to Nowhere: The Role of Agencies in Advocacy Coalitions
The purpose of the advocacy coalition framework is to explain policy change over time through an examination of the stability of advocacy coalitions within policy subsystems. Recently, scholars have confirmed that advocacy coalitions are held together by shared belief systems, specifically in distributive policy arenas. We contend that federal agencies, in distributive policy arenas, provide both the anchors and support systems for the development and maintenance of belief systems. This anchoring helps provide adequate resources, access to political institutions, ability to control administrative process, and/or the capacity to deliver public goods and services. We conducted an analysis of the policy changes that occurred during the implementation of the National Environmental Policy Act for the construction of the Bureau of Reclamation’s Animas-La Plata project. This is an example where administrators, through the management of information, were able to control the policy process. The analysis provides a needed replication of previous findings regarding policy change and offers new insights into how institutions are critical to subsystem stability over time
- …