66,765 research outputs found
A generalization of the Lyndon--Hochschild--Serre spectral sequence with applications to group cohomology and decompositions of groups
We set up a Grothendieck spectral sequence which generalizes the
Lyndon--Hochschild--Serre spectral sequence for a group extension K\mono G\epi
Q by allowing the normal subgroup to be replaced by a subgroup, or family
of subgroups which satisfy a weaker condition than normality. This is applied
to establish a decomposition theorem for certain groups as fundamental groups
of graphs of Poincar\'e duality groups. We further illustrate the method by
proving a cohomological vanishing theorem which applies for example to
Thompson's group .Comment: 22 page
Learning from Physics Education Research: Lessons for Economics Education
We believe that economists have much to learn from educational research
practices and related pedagogical innovations in other disciplines, in
particular physics education. In this paper we identify three key features of
physics education research that distinguish it from economics education
research - (1) the intentional grounding of physics education research in
learning science principles, (2) a shared conceptual research framework focused
on how students learn physics concepts, and (3) a cumulative process of
knowledge-building in the discipline - and describe their influence on new
teaching pedagogies, instructional activities, and curricular design in physics
education. In addition, we highlight four specific examples of successful
pedagogical innovations drawn from physics education - context-rich problems,
concept tests, just-in-time teaching, and interactive lecture demonstrations -
and illustrate how these practices can be adapted for economic education.Comment: 19 pages, 3 figures, submitted to Journal of Economic Education, also
available from Social Science Research Network
<http://ssrn.com/abstract=1151430
Learning from physics education research: Lessons for economics education
We believe that economists have much to learn from educational research practices and related pedagogical innovations in other disciplines, in particular physics education. In this paper we identify three key features of physics education research that distinguish it from economics education research - (1) the intentional grounding of physics education research in learning science principles, (2) a shared conceptual research framework focused on how students learn physics concepts, and (3) a cumulative process of knowledge-building in the discipline - and describe their influence on new teaching pedagogies, instructional activities, and curricular design in physics education. In addition, we highlight four specific examples of successful pedagogical innovations drawn from physics education - context-rich problems, concept tests, just-in-time teaching, and interactive lecture demonstrations - and illustrate how these practices can be adapted for economic education.economic education; physics education research (PER); research-based teaching; preconceptions; metacognition; transfer; context-rich problems; peer instruction; just-in-time teaching; interactive lecture demonstration
A comparison of methods to evaluate energy expenditure of incubating wandering albatrosses
Measurements of incubation energetics can vary depending on the method used to measure metabolism of an incubating bird. Therefore, we evaluated the energy expenditure of six male and four female wandering albatrosses (Diomedea exulans Linnaeus) using doubly labeled water (DLW), the rate of mass loss, and estimates of metabolic water production derived from water influx rate (WIR). Incubation metabolic rates (IMR) determined with DLW ( 169 ± 21 kJ kg d SD) were significantly lower than estimates derived from mass loss ( 277 ± 46kJ kg d SD) and WIR ( males=289 ± 60 kJ kg d vs. females = 400 ± 69 kJ kg d SD). Estimates of IMR from f WIR were similar to IMR (305 ± 39 kJ kg d SD) determined by respirometry in a previous study, and IMR from DLW was similar to estimates based on heart rate (HR; 147 ± 26 kJ d SD) determined in another study. Ap- 147 26 plying the different measurements of IMR to construct an en-ergy budget, we estimate that a breeding pair of wandering albatrosses spends 124--234 MJ to incubate the egg for 78 d. Finally, IMRs determined with DLW and HR were similar
Simultaneous polymerization and molding of Pyrrone polymers
Simultaneous polymerization and hot pressing of Pyrrone polymer
Augmented renal clearance is not a risk factor for mortality in Enterobacteriaceae bloodstream infections treated with appropriate empiric antimicrobials
The main objective of the study was to assess whether augmented renal clearance was a risk factor for mortality in a cohort of patients with Enterobacteriaceae sepsis, severe sepsis, or septic shock that all received appropriate antimicrobial therapy within 12 hours. Using a retrospective cohort from Barnes-Jewish Hospital, a 1,250-bed teaching hospital, we collected data on individuals with Enterobacteriaceae sepsis, severe sepsis, and septic shock who received appropriate initial antimicrobial therapy between June 2009 and December 2013. Clinical outcomes were compared according to renal clearance, as assessed by Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulas, sepsis classification, demographics, severity of illness, and comorbidities. We identified 510 patients with Enterobacteriaceae bacteremia and sepsis, severe sepsis, or septic shock. Sixty-seven patients (13.1%) were nonsurvivors. Augmented renal clearance was uncommon (5.1% of patients by MDRD and 3.0% by CKD-EPI) and was not associated with increased mortality. Our results are limited by the absence of prospective determination of augmented renal clearance. However, in this small cohort, augmented renal clearance as assessed by MDRD and CKD-EPI does not seem to be a risk factor for mortality in patients with Enterobacteriaceae sepsis. Future studies should assess this finding prospectively
Exploring Organizational Communication (Micro) History Through Network Connections
In light of the 100th anniversary of the National Communication Association, the following essay offers an initial look at the communication subdiscipline of organizational communication and its development over the past seven-plus decades. As part of this review, we advocate the use of network methods as a microhistory analytic tool to explore the vast number of connections, both between people and research interests, generated as the discipline developed from its humble beginnings. This work represents a small sample of the greater Organizational Communication Genealogy Project. This larger effort seeks to create a detailed review of the discipline as it explores the relationships between advisors and advisees, the development of dissertation and current research topics, the collaborative network of coauthorship, and the contributions of individual scholars through the analysis of interview data, narratives, and historical documents
Viscous Hydrodynamics and Relativistic Heavy Ion Collisions
The matter created in relativistic heavy ion collisions is fairly well
described by ideal hydrodynamics, and somewhat better described by viscous
hydrodynamics. To this point, most viscous calculations have been
two-dimensional, based on an assumption of Bjorken boost invariance along the
beam axis. Here, first results are presented for a fully three-dimensional
viscous model. The model is described and tests of the numerical accuracy of
the code are presented. Two- and three-dimensional runs are compared, and
modest changes are observed for mid-rapidity observables at the highest RHIC
(Relativistic Heavy Ion Collider) energies.Comment: 23 pages, 7 figure
Completion Report: Arkansas State Pesticides in Ground Water Monitoring Project Phase V: Vulnerable areas in Jackson, Monroe, Lawrence and Lonoke Counties
In 1996, sixty-seven water samples were drawn from 65 wells, including 62 new wells and 3 wells sampled previously . One Woodruff County well and two Pulaski County wells were resampled. Thirty-two samples were drawn from 30 wells in Monroe County (well #1 was sampled 3 times during this phase) . Ten wells in Jackson County, 12 wells in Lawrence County and 10 wells in Lonoke were also tested (Figures 1-5) . With the completion of Phase V, the number of wells tested has risen to 231 with a total of 258 samples analyzed . Initially, the wells were tested for 13 pesticides and ni~rate. Two more pesticides, aldicarb and carbofuran were added to the analyte list during Phase V. The analyte list is shown in Table 3 . All results from all the wells are listed in Appendix A. Quality control information for these data follow the results. The Phase V Quality Assurance Report is included in this document as Part II
On the Electronic Spectroscopy of Closed Shell Cations Derived From Resonance Stabilized Radicals: Insights From Theory and Franck-Condon Analysis
Context. Recent attention has been directed on closed-shell aromatic cations as potential carriers of the diffuse interstellar bands. The spectra of mass-selected, matrix-isolated benzylium, and tropylium cations were recently reported. The visible spectrum of benzylium exhibits a large Franck-Condon (FC) envelope, inconsistent with diffuse interstellar band carriers.
Aims. We perform a computational analysis of the experimentally studied benzylium spectrum before extending the methods to a range of larger, closed-shell aromatic cations to determine the potential for this class of systems as diffuse interstellar band carriers.
Methods. Density functional theory (DFT), time-dependant ((TD)DFT), and multi-configurational self-consistent field second-order perturbation theory (MRPT2) methods in concert with multidimensional FC analysis is used to model the benzylium spectrum. These methods are extended to larger closed-shell aromatic hydrocarbon cations derived from resonance-stabilized radicals, which are predicted to show strong S0 → Sn transitions in the visible region. The ionization energies of a range of these systems are also calculated by DFT.
Results. The simulated benzylium spectrum was found to yield excellent agreement with the experimental spectrum showing an extended progression in a low frequency (510 cm-1) ring distortion mode. The FC progression was found to be significantly quenched in the larger species: 1-indanylium, 1-naphthylmethylium, and fluorenium. Excitation and ionization energies of the closed-shell cations were found to be consistent with diffuse interstellar band carriers, with the former lying in the visible range and the latter straddling the Lyman limit in the 13−14 eV range.
Conclusions. Large closed-shell polycyclic aromatic hydrocarbon cations remain viable candidate carriers of the diffuse interstellar bands
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