174 research outputs found
Some notes on religion and democratic liberty
"My intention is to discuss briefly several elements of the connection between liberal
democracy and religion. This topic is decisive in much of Richard Neuhaus’
work. Conserving liberty is a central task today, and religion’s place in this task
important, although controversial."(...
Hegel and progressivism
"We often assert that the United States’ constitutional principles began to change
near the beginning of the twentieth century. This change is associated with “progressivism.”
It was trumpeted by publicists and authors such as Herbert Croly and
John Dewey, and implemented by political leaders such as Woodrow Wilson and
the two Roosevelts. Progressivism involves moving away from limited government
toward the beginnings of the welfare state, increasing the regulation of business,
expanding the dominance of the President over Congress, justifying direct
appeals from the President to the people (leadership as opposed to statesmanship),
and attacking the teaching of individual natural rights in favor of group interests,
mass appeals, and some forms of (weak) collectivism."(...
Turbulence, Feedback, and Slow Star Formation
One of the outstanding puzzles about star formation is why it proceeds so
slowly. Giant molecular clouds convert only a few percent of their gas into
stars per free-fall time, and recent observations show that this low star
formation rate is essentially constant over a range of scales from individual
cluster-forming molecular clumps in the Milky Way to entire starburst galaxies.
This striking result is perhaps the most basic fact that any theory of star
formation must explain. I argue that a model in which star formation occurs in
virialized structures at a rate regulated by supersonic turbulence can explain
this observation. The turbulence in turn is driven by star formation feedback,
which injects energy to offset radiation from isothermal shocks and keeps
star-forming structures from wandering too far from virial balance. This model
is able to reproduce observational results covering a wide range of scales,
from the formation times of young clusters to the extragalactic IR-HCN
correlation, and makes additional quantitative predictions that will be
testable in the next few years.Comment: 4 pages, 2 figures, CUP conference format. To be published in "IAU
Symposium 237: Triggered Star Formation in a Turbulent ISM", eds. B.
Elmegreen & J. Palou
OH yields from the CH3CO+O-2 reaction using an internal standard
Laser flash photolysis of CH3C(O)OH at 248 nm was used to create equal zero time yields of CH3CO and OH. The absolute OH yield from the CH3CO + O2 (+M) reaction was determined by following the OH temporal profile using the zero time
OH concentration as an internal standard. The OH yield from CH3CO + O2 (+M) was observed to decrease with increasing pressure with an extrapolated zero pressure yield
close to unity (1.1 ± 0.2, quoted uncertainties correspond to 95% confidence limits). The results are in quantitative agreement with those obtained from 248 nm acetone
photolysis in the presence of O2
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How Leaders Agree with Teachers in Schools on Measures of Leadership Practice: A Two-Level Latent Class Analysis of the Comprehensive Assessment of Leadership for Learning
Background: Across the recent research on school leadership, leadership for learning has emerged as a strong framework for integrating current theories, such as instructional, transformational, and distributed leadership as well as effective human resource practices, instructional evaluation, and resource allocation. Yet, questions remain as to how, and to what extent teachers and leaders practice the skills and tasks that are known to be associated with effective school leadership, and to what extent do teachers and leaders agree that these practices are taking place in their school. Purpose of the Study: We examine these issues through applying a congruency-typology model to the validation sample of the Comprehensive Assessment of Leadership for Learning (CALL), (117 schools across the US, including 3,367 teachers and their school leaders) to examine the extent to which there may be significantly different subgroups of teacher and leader responders to the survey, how these subgroups may cluster non-randomly in schools, and to what extent the subgroups of teachers and principals are aligned or not on their perception that the skills and practices of leadership for learning take place in their school. Research Design: We used multilevel latent class analysis (LCA) to identify significantly different types of teacher and leader responders to CALL, including a cross-level interaction to examine the extent to which there is a typology model of teacher responders across schools and the extent to which the teacher subgroup responses align with the leader of the school. Findings: We find that there are three statistically significant different subgroups of teacher responders to CALL, Low (31.4%), Moderate (43.3%), and High (25.4%). In addition, these subgroups cluster non-randomly across three different types of schools: schools with low leadership for learning (40.2%), moderate leadership for learning (47.0%), and the smallest subgroup, schools with high leadership for learning (12.8%). Conclusions: Our findings suggest that a congruency-typology model of leadership for learning is useful for understanding the context of practice, as schools may be on a continuum of practice in which there is strong alignment between teacher and leader responder types in the low and high schools – indicating problematic or beneficial contexts – but that leaders in the moderate type may be working to move their school towards instructional improvement through leadership for learning. As a quantitative phenomenology, this study provides a rich contextual analysis of the relationship between teachers and leaders on a multisource feedback survey of leadership for learning in schools. Keywords: School Leadership, Leadership for Learning, Leadership Styles, Instructional Leadership, Transformational Leadership, Latent Class Analysis, Mixture Modeling, Multivariate Methods, Multisource Feedback, Survey Research, Online Surveys, Teacher Leadership, Principal
The Atomic to Molecular Transition in Galaxies. II: HI and H_2 Column Densities
Gas in galactic disks is collected by gravitational instabilities into giant
atomic-molecular complexes, but only the inner, molecular parts of these
structures are able to collapse to form stars. Determining what controls the
ratio of atomic to molecular hydrogen in complexes is therefore a significant
problem in star formation and galactic evolution. In this paper we use the
model of H_2 formation, dissociation, and shielding developed in the previous
paper in this series to make theoretical predictions for atomic to molecular
ratios as a function of galactic properties. We find that the molecular
fraction in a galaxy is determined primarily by its column density and
secondarily by its metallicity, and is to good approximation independent of the
strength of the interstellar radiation field. We show that the column of atomic
hydrogen required to shield a molecular region against dissociation is ~10 Msun
pc^-2 at solar metallicity. We compare our model to data from recent surveys of
the Milky Way and of nearby galaxies, and show that the both the primary
dependence of molecular fraction on column density and the secondary dependence
on metallicity that we predict are in good agreement with observed galaxy
properties.Comment: Accepted to ApJ. 22 pages, 13 figures, emulateapj format. This
version corrects a minor error in the binning procedure in section 4.1.2. The
remainder of the paper is unchange
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Is There a Typology of Teacher and Leader Responders to CALL, and Do They Cluster in Different Types of Schools? A Two-Level Latent Class Analysis of CALL Survey Data
Background: Across the recent research on school leadership, leadership for learning has emerged as a strong framework for integrating current theories, such as instructional, transformational, and distributed leadership as well as effective human resource practices, instructional evaluation, and resource allocation. Yet, questions remain as to how, and to what extent teachers and leaders practice the skills and tasks that are known to be associated with effective school leadership, and to what extent do teachers and leaders agree that these practices are taking place in their school.
Purpose of the Study: We examine these issues through applying a congruency-typology model to the validation sample of the Comprehensive Assessment of Leadership for Learning (CALL), (117 schools across the US, including 3,367 teachers and their school leaders) to examine the extent to which there may be significantly different subgroups of teacher and leader responders to the survey, how these subgroups may cluster non-randomly in schools, and to what extent the subgroups of teachers and principals are aligned or not on their perception that the skills and practices of leadership for learning take place in their school.
Research Design: We used multilevel latent class analysis (LCA) to identify significantly different types of teacher and leader responders to CALL, including a cross-level interaction to examine the extent to which there is a typology model of teacher responders across schools and the extent to which the teacher subgroup responses align with the leader of the school.
Findings: We find that there are three statistically significant different subgroups of teacher responders to CALL, Low (31.4%), Moderate (43.3%), and High (25.4%). In addition, these subgroups cluster non-randomly across three different types of schools: schools with low leadership for learning (40.2%), moderate leadership for learning (47.0%), and the smallest subgroup, schools with high leadership for learning (12.8%).
Conclusions: Our findings suggest that a congruency-typology model of leadership for learning is useful for understanding the context of practice, as schools may be on a continuum of practice in which there is strong alignment between teacher and leader responder types in the low and high schools – indicating problematic or beneficial contexts – but that leaders in the moderate type may be working to move their school towards instructional improvement through leadership for learning. As a quantitative phenomenology, this study provides a rich contextual analysis of the relationship between teachers and leaders on a multisource feedback survey of leadership for learning in schools
Time-Resolved Measurements and Master Equation Modelling of the Unimolecular Decomposition of CH3OCH2
The rate coefficient for the unimolecular decomposition of CH3OCH2,k(1), has been measured in time-resolved experiments by monitoring the HCHO product. CH3OCH2 was rapidly and cleanly generated by 248 nm excimer photolysis of oxalyl chloride, (ClCO)(2), in an excess of CH3OCH3, and an excimer pumped dye laser tuned to 353.16 nm was used to probe HCHO via laser induced fluorescence. k(1)(T,p) was measured over the ranges: 573-673 K and 0.1-4.3 x 10(18) molecule cm(-3) with a helium bath gas. In addition, some experiments were carried out with nitrogen as the bath gas. Ab initio calculations on CH3OCH2 decomposition were carried out and a transition-state for decomposition to CH3 and H2CO was identified. This information was used in a master equation rate calculation, using the MESMER code, where the zero-point-energy corrected barrier to reaction, Delta E-0,E-1, and the energy transfer parameters, x T-n, were the adjusted parameters to best fit the experimental data, with helium as the buffer gas. The data were combined with earlier measurements by Loucks and Laidler (Can J. Chem. 1967, 45, 2767), with dimethyl ether as the third body, reinterpreted using current literature for the rate coefficient for recombination of CH3OCH2. This analysis returned Delta E-0,E-1 = (112.3 +/- 0.6) kJ mol(-1), and leads to k(1)(infinity)(T) = 2.9 x 10(12) (T/300)(2)(.5) exp(-106.8 kJ mol(-1)/RT). Using this model, limited experiments with nitrogen as the bath gas allowed N-2 energy transfer parameters to be identified and then further MESMER simulations were carried out, where N-2 was the buffer gas, to generate k(1)(T,p) over a wide range of conditions: 300-1000 K and N-2 = 10(12) -10(25) molecule cm(-3). The resulting k(1)(T,p) has been parameterized using a Troe-expression, so that they can be readily be incorporated into combustion models. In addition, k(1)(T,p) has been parametrized using PLOG for the buffer gases, He, CH3OCH3 and N-2.Peer reviewe
The gas-phase reaction of NH2 with formaldehyde (CH2O) is not a source of formamide (NH2CHO) in interstellar environments
The first experimental study of the low-temperature kinetics of the gas-phase
reaction of NH2 with formaldehyde (CH2O) has been performed. This reaction has
previously been suggested as a source of formamide (NH2CHO) in interstellar
environments. A pulsed Laval nozzle equipped with laser-flash photolysis and
laser-induced fluorescence spectroscopy was used to create and monitor the
temporal decay of NH2 in the presence of CH2O. No loss of NH2 could be observed
via reaction with CH2O and we place an upper-limit on the rate coefficient of
<6x10-12 cm3 molecule-1 s-1 at 34K. Ab initio calculations of the potential
energy surface were combined with RRKM calculations to predict a rate
coefficient of 6.2x10-14 cm3 molecule-1 s-1 at 35K, consistent with the
experimental results. The presence of a significant barrier, 18 kJ mol-1, for
the formation of formamide as a product, means that only the H-abstraction
channel producing NH3 + CHO, in which the transfer of an H-atom can occur by
quantum mechanical tunnelling through a 23 kJ mol-1 barrier, is open at low
temperatures. These results are in contrast with a recent theoretical study
which suggested that the reaction could proceed without a barrier and was
therefore a viable route to gas-phase formamide formation. The calculated rate
coefficients were used in an astrochemical model which demonstrated that this
reaction produces only negligible amounts of gas-phase formamide under
interstellar and circumstellar conditions. The reaction of NH2 with CH2O is
therefore not an important source of formamide at low temperatures in
interstellar environments.Comment: Manuscript, 14 pages, 4 figures. Supporting Information, 8 pages, 2
figures. Accepted for publication in The Astrophysical Journal Letter
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