7,521 research outputs found
CO observations of the expanding envelope of IRC plus 10216
High-sensitivity emission profiles were observed for the transition of C12O16 and C13O16 towards IRC + or - 10216. It appears that the spherically symmetric uniform mass-outflow model proposed by Morris is necessary to describe the line profiles. The outflow appears to be slightly accelerated, having a velocity of 15 km/sec at the edges of the CO cloud, compared with 12 km/sec for the more centrally confined molecules
Redefining and Improving School District Governance
Explores recent research literature and emerging practices concerning the roles and responsibilities of district school boards and the issues impeding or assisting their effectiveness
Leading, Learning, and Leadership Support
Offers a framework for improving learning-focused leadership through the use of data and evidence, reallocation of resources, redefined roles and responsibilities, assessment of leadership performance, better governance, and a focus on high schools
Allocating Resources and Creating Incentives to Improve Teaching and Learning
Offers insights from scholarly literature, related theory, and practical activities to inform the efforts of policymakers, researchers and practitioners to allocate resources and create incentives that result in powerful, equitable learning for all
Learning-Focused Leadership and Leadership Support: Meaning and Practice in Urban Systems
Synthesizes three reports on what good education leadership means and how it can best be supported, including the role of the school leader and the transformation of central district offices to focus more on improving instruction. Outlines key practices
How Leaders Invest Staffing Resources for Learning Improvement
Analyzes staffing challenges that guide school leaders' resource decisions in the context of a learning improvement agenda, staff resource investment strategies that improve learning outcomes equitably, and ways to win support for differential investment
PhytoKeys at 100: progress in sustainability, innovation, and speed to enhance publication in plant systematics
The file attached is the Published/publisher’s pdf version of the article.This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.NHM Repositor
A phylogenetic framework for evolutionary study of the nightshades (Solanaceae): a dated 1000-tip tree
© Särkinen et al.; licensee BioMed Central Ltd. 2013
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The attached file is the published version of the article
The performance of yields in organic and conventional cropping systems
Sufficient and stable crop yields are the basis for feeding a growing world population. Limited cropland, climate change, loss of soil quality and biodiversity coupled with excessive use of non-renewable resources require new solutions for future cropping systems beyond existing management practices. Here we compare the yield performance of organic and conventional cropping systems
Decomposition of time-covariant operations on quantum systems with continuous and/or discrete energy spectrum
Every completely positive map G that commutes which the Hamiltonian time
evolution is an integral or sum over (densely defined) CP-maps G_\sigma where
\sigma is the energy that is transferred to or taken from the environment. If
the spectrum is non-degenerated each G_\sigma is a dephasing channel followed
by an energy shift. The dephasing is given by the Hadamard product of the
density operator with a (formally defined) positive operator. The Kraus
operator of the energy shift is a partial isometry which defines a translation
on R with respect to a non-translation-invariant measure.
As an example, I calculate this decomposition explicitly for the rotation
invariant gaussian channel on a single mode.
I address the question under what conditions a covariant channel destroys
superpositions between mutually orthogonal states on the same orbit. For
channels which allow mutually orthogonal output states on the same orbit, a
lower bound on the quantum capacity is derived using the Fourier transform of
the CP-map-valued measure (G_\sigma).Comment: latex, 33 pages, domains of unbounded operators are now explicitly
specified. Presentation more detailed. Implementing the shift after the
dephasing is sometimes more convenien
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