607 research outputs found
Saturation Effects in a Tunable Coherent Near-Infrared Source
A Saturation Effect in a Tunable Infrared Source Utilizing Four-Wave Parametric Conversion in Potassium Vapor is Reported and is Shown to Be the Result of Parasitic Oscillations. a Hundredfold Increase over Previously Attained Power Levels Has Been Affected Via Elimination of These Oscillations
Stringy K-theory and the Chern character
For a finite group G acting on a smooth projective variety X, we construct
two new G-equivariant rings: first the stringy K-theory of X, and second the
stringy cohomology of X. For a smooth Deligne-Mumford stack Y we also construct
a new ring called the full orbifold K-theory of Y. For a global quotient
Y=[X/G], the ring of G-invariants of the stringy K-theory of X is a subalgebra
of the full orbifold K-theory of the the stack Y and is linearly isomorphic to
the ``orbifold K-theory'' of Adem-Ruan (and hence Atiyah-Segal), but carries a
different, ``quantum,'' product, which respects the natural group grading. We
prove there is a ring isomorphism, the stringy Chern character, from stringy
K-theory to stringy cohomology, and a ring homomorphism from full orbifold
K-theory to Chen-Ruan orbifold cohomology. These Chern characters satisfy
Grothendieck-Riemann-Roch for etale maps.
We prove that stringy cohomology is isomorphic to Fantechi and Goettsche's
construction. Since our constructions do not use complex curves, stable maps,
admissible covers, or moduli spaces, our results simplify the definitions of
Fantechi-Goettsche's ring, of Chen-Ruan's orbifold cohomology, and of
Abramovich-Graber-Vistoli's orbifold Chow.
We conclude by showing that a K-theoretic version of Ruan's Hyper-Kaehler
Resolution Conjecture holds for symmetric products.
Our results hold both in the algebro-geometric category and in the
topological category for equivariant almost complex manifolds.Comment: Exposition improved and additional details provided. To appear in
Inventiones Mathematica
4. National Support for Behavioral Science
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67094/2/10.1177_000276425800100504.pd
Independent Regulation of Reovirus Membrane Penetration and Apoptosis by the μ1 ϕ Domain
Apoptosis plays an important role in the pathogenesis of reovirus encephalitis. Reovirus outer-capsid protein μ1, which functions to penetrate host cell membranes during viral entry, is the primary regulator of apoptosis following reovirus infection. Ectopic expression of full-length and truncated forms of μ1 indicates that the μ1 ϕ domain is sufficient to elicit a cell death response. To evaluate the contribution of the μ1 ϕ domain to the induction of apoptosis following reovirus infection, ϕ mutant viruses were generated by reverse genetics and analyzed for the capacity to penetrate cell membranes and elicit apoptosis. We found that mutations in ϕ diminish reovirus membrane penetration efficiency by preventing conformational changes that lead to generation of key reovirus entry intermediates. Independent of effects on membrane penetration, amino acid substitutions in ϕ affect the apoptotic potential of reovirus, suggesting that ϕ initiates apoptosis subsequent to cytosolic delivery. In comparison to wild-type virus, apoptosis-defective ϕ mutant viruses display diminished neurovirulence following intracranial inoculation of newborn mice. These results indicate that the ϕ domain of μ1 plays an important regulatory role in reovirus-induced apoptosis and disease
Para a noção de transformação curricular
Neste artigo é evidenciada a relação entre currículo e conhecimento, abordando-se o conhecimento escolar na sua seleção, organização e transformação, a partir de uma revisão do conceito de transposição didática e da proposição dos conceitos de transformação curricular e transformação didática. Qualquer debate sobre o currículo exige a dilucidação do conhecimento e uma reflexão sobre os seus diversos significados, sobretudo quando a educação se torna num projeto amplo de questionamento da realidade social. Para além de várias questões colocadas acerca do conhecimento escolar e do modo como a sua organização pode ser realizada, procura-se centrar o debate numa reflexão sobre as fronteiras entre conhecimentos e esclarecer que, sobre essa temática, jamais poderão existir respostas fechadas.This article highlights the link between curriculum and knowledge, the approach
of school knowledge’s selection, organization and transformation is based on a
revision of the concept of didactic transposition and on the proposal of the concepts
of curriculum and didactic transformation. Debates on curriculum demand an
explanation and a reflection on the multiple meanings of knowledge mainly when
education aims to be a broad project to contest social reality. It aims to focus the
discussion on a reflection regarding the borders between knowledges and to show
that in this subject there are never closed answers.Dans cet article est mis en évidence le rapport entre le curriculum et la connaissance,
en abordant la connaissance scolaire dans sa sélection, son organisation et sa
transformation à partir d’une révision du concept de transposition didactique
et de la proposition des concepts de transformation du curriculum et de
transformation didactique. Toute discussion sur le curriculum exige la dilucidation
de la connaissance et une réflexion sur ses plusieurs signifiés, surtout quand
l’éducation devient un projet plus large de mise en question de la réalité sociale.
Au delà des plusieurs questions posées autour de la connaissance scolaire et de la
manière comme son organisation peut être réalisée, on cherche á fixer le débat
dans une réflexion sur les frontières entre connaissances et éclaircir que, sur cette
thématique jamais ne pourront exister des réponses absolues.En este trabajo se pone en evidencia la relación entre el currículum y el
conocimiento, abordándose el conocimiento escolar en su selección, organización
y transformación desde una revisión del concepto de transposición didáctica y de
la proposición de los conceptos de transformación curricular y transformación
didáctica. Cualquier discusión sobre el currículum requiere la aclaración del
conocimiento y una reflexión sobre sus diversos significados, especialmente
cuando la educación se convierte en un proyecto más amplio de cuestionamiento
de la realidad social. Además de varias preguntas sobre el conocimiento escolar y
el modo en el que su organización puede tener lugar, se intenta centrar el debate
en una reflexión sobre las fronteras entre conocimientos y aclarar que en esta
temática jamás podrán existir respuestas cerradas.(undefined
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
Characterization of a murine model of monocrotaline pyrrole-induced acute lung injury
<p>Abstract</p> <p>Background</p> <p>New animal models of chronic pulmonary hypertension in mice are needed. The injection of monocrotaline is an established model of pulmonary hypertension in rats. The aim of this study was to establish a murine model of pulmonary hypertension by injection of the active metabolite, monocrotaline pyrrole.</p> <p>Methods</p> <p>Survival studies, computed tomographic scanning, histology, bronchoalveolar lavage were performed, and arterial blood gases and hemodynamics were measured in animals which received an intravenous injection of different doses of monocrotaline pyrrole.</p> <p>Results</p> <p>Monocrotaline pyrrole induced pulmonary hypertension in Sprague Dawley rats. When injected into mice, monocrotaline pyrrole induced dose-dependant mortality in C57Bl6/N and BALB/c mice (dose range 6–15 mg/kg bodyweight). At a dose of 10 mg/kg bodyweight, mice developed a typical early-phase acute lung injury, characterized by lung edema, neutrophil influx, hypoxemia and reduced lung compliance. In the late phase, monocrotaline pyrrole injection resulted in limited lung fibrosis and no obvious pulmonary hypertension.</p> <p>Conclusion</p> <p>Monocrotaline and monocrotaline pyrrole pneumotoxicity substantially differs between the animal species.</p
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