4,989 research outputs found
Categorical Cell Decomposition of Quantized Symplectic Algebraic Varieties
We prove a new symplectic analogue of Kashiwara's Equivalence from D-module
theory. As a consequence, we establish a structure theory for module categories
over deformation quantizations that mirrors, at a higher categorical level, the
Bialynicki-Birula stratification of a variety with an action of the
multiplicative group. The resulting categorical cell decomposition provides an
algebro-geometric parallel to the structure of Fukaya categories of Weinstein
manifolds. From it, we derive concrete consequences for invariants such as
K-theory and Hochschild homology of module categories of interest in geometric
representation theory.Comment: Version 2. A number of minor edits and corrections. Comments welcom
Computational Investigations of Biomolecular Mechanisms in Genomic Replication, Repair and Transcription
High fidelity maintenance of the genome is imperative to ensuring stability and proliferation of cells. The genetic material (DNA) of a cell faces a constant barrage of metabolic and environmental assaults throughout the its lifetime, ultimately leading to DNA damage. Left unchecked, DNA damage can result in genomic instability, inviting a cascade of mutations that initiate cancer and other aging disorders. Thus, a large area of focus has been dedicated to understanding how DNA is damaged, repaired, expressed and replicated. At the heart of these processes lie complex macromolecular dynamics coupled with intricate protein-DNA interactions. Through advanced computational techniques it has become possible to probe these mechanisms at the atomic level, providing a physical basis to describe biomolecular phenomena. To this end, we have performed studies aimed at elucidating the dynamics and interactions intrinsic to the functionality of biomolecules critical to maintaining genomic integrity: modeling the DNA editing mechanism of DNA polymerase III, uncovering the DNA damage recognition/repair mechanism of thymine DNA glycosylase and linking genetic disease to the functional dynamics of the pre-initiation complex transcription machinery. Collectively, our results elucidate the dynamic interplay between proteins and DNA, further broadening our understanding of these complex processes involved with genomic maintenance
It is the process, not the test: A mixed method study of a professional learning community at one elementary school in Oklahoma.
The juxtaposition of the quest for reaching accountability benchmarks and the desire for meeting students' individual needs has created a problem for district administration, site principals, and school staff. As a result, the stakeholders have struggled to redefine the way instructional and social support services are delivered to its rapidly changing students.This new "era of accountability" has called for unique investigations into ways in which schools are meeting the new requirements. A mixed method study of one Title I elementary school in Oklahoma explored how a professional learning community (PLC) was both developed and implemented in this case. In addition, the study sought to explore how learning for both staff and students was affected. Like many districts that formerly identified themselves as "suburban, " the area in which this school is located has experienced rapidly changing demographics. This change has resulted in a student population that has compared to the district as a whole, a greater incidence of poverty, higher mobility rates, and a larger percentage of non-English speaking students. These factors have perpetuated a learning gap on both state and local assessments.This study attempted to tell the story of one school's search to create the best possible teaching and learning environment while meeting the current high-stakes accountability measures for student performance. This study sought to determine if, in this case, the establishment of professional learning communities was a viable strategy for addressing accountability demands while encouraging the use of best instructional practices. The analysis focused on the school's use of teacher collaboration as a means to facilitate conversation about teaching and learning, create common assessments, conduct data analyses, and reflect on how their goals were met.In 2001, the most far-reaching educational accountability initiative was launched by the Bush administration. The No Child Left Behind Act required all students to show incremental growth toward mastery of state standards with all students demonstrating proficiency by 2014.The study indicated that increased student learning is strongly encouraged by the development of professional learning communities. In this case, the development of the PLC served as a means to focus the conversation on student achievement while encouraging collaboration among school staff as a means of addressing individual students' learning needs. The study also suggested that the development of meaningful community partnerships played an integral part in the PLC process
Sedimentology and depositional environments in the Mesozoic, West of Shetland
As part of Phase 3 of the Faroe-Shetland Consortium project on the UK sector of the Faroe-Shetland Basin, BGS completed detailed (10 cm-scale) sedimentary logging of 604.77 m of conventional core recovered from 19 wells, drilled between 1974 and 1995. The project originally focussed solely on Jurassic-aged sediments, as identified in BGS held well databases. In reality, the project examined a suit of sediments ranging from the Triassic, Jurassic and Lower Cretaceous. In addition, a suite of complementary palynological sampling was completed. The goal was to provide additional depositional environment information from palyno-facies analysis, along with age determination for the sediments. Together, the two new datasets form an integrated re-assessment of the Mesozoic-aged depositional environments located to the West of Shetland.
The Triassic-aged deposits of the Papa Group record deposition in a fluvial environment, whereby the fluvial systems display meandering to braided characteristics. In places, particularly in the upper parts of the cored Triassic-aged strata, the sediments display evidence for nearshore, wave-working processes. The nearshore working may be evidence for a transgression event at the top of the cored Triassic interval; something which should be investigated further in the future.
Within the Jurassic-aged succession, two main groups were analysed: the Skerry Group and the Humber Group. Sediments within the Skerry Group were deposited within a fully marine, shelfal environment (the Stack Skerry Formation) and a relatively deeper-water, outer shelf to bathyal environment (the Sule Skerry Formation). Late Jurassic-aged sediments from the Humber Group are represented by the Rona Member, the Solan Sandstone Member and the Ridge Conglomerate Member. BGS has subdivided the Rona Member into five “facies”, largely on the basis of depositional environment. These include: Rona R1 (Fluvial), Rona R2 (Fan Delta), Rona R3 (Marginal Marine), Rona R4 (Shoreface/Littoral) and Rona R5 (Shallow Marine). Deposits of the Rona R4 facies represent good hydrocarbon reservoir targets, whilst the Rona R3 facies has the potential to form a sourcing lithology. The Solan Sandstone Member, interpreted to be contemporaneous with the deposition of the Rona Member, was deposited in a deep-marine, turbidite fan system. The Kimmeridge Clay Formation is encountered in a number of wells, typically represented by a dark grey- to black-coloured, hemi-pelagic mud-prone succession.
The Early Cretaceous-aged Cromer Knoll Group is also present in the core data, represented by: turbidite fan deposits, formed in a deep marine environment (204/19-1 & 205/21-1A); and by shoreface/littoral deposits representative of a marine setting (205/26a-2). These sediments appear to rest unconformably on the Kimmeridge Clay Formation
Nucleon mass and pion loops: Renormalization
Using Dyson--Schwinger equations, the nucleon propagator is analyzed
nonperturbatively in a field--theoretical model for the pion--nucleon
interaction. Infinities are circumvented by using pion--nucleon form factors
which define the physical scale. It is shown that the correct, finite,
on--shell nucleon renormalization is important for the value of the mass--shift
and the propagator. For physically acceptable forms of the pion--nucleon form
factor the rainbow approximation together with renormalization is inconsistent.
Going beyond the rainbow approximation, the full pion--nucleon vertex is
modelled by its bare part plus a one--loop correction including an effective
. It is found that a consistent value for the nucleon mass--shift can
be obtained as a consequence of a subtle interplay between wave function and
vertex renormalization. Furthermore, the bare and renormalized pion--nucleon
coupling constant are approximately equal, consistent with results from the
Cloudy Bag Model.Comment: 14 pages, 6 figure
Chiral Extrapolation of Hadronic Observables
One of the great challenges of lattice QCD is to produce unambiguous
predictions for the properties of physical hadrons. We review recent progress
with respect to a major barrier to achieving this goal, namely the fact that
computation time currently limits us to large quark mass. Using insights from
the study of the lattice data itself, together with the general constraints of
chiral symmetry, we demonstrate that it is possible to extrapolate accurately
and in an essentially model independent manner from the mass region where
calculations will be performed within the next five years to the chiral limit.Comment: Lattice2002(plenary) Invited presentation at The XX Int. Symposium on
Lattice Field Theory, Lattice 2002, MIT Boston, June 24--29, 200
Lacrimal Gland Involvement in Lymphomatoid Granulomatosis and Review of the Literature
Objective. To describe the clinicoradiological and histopathological findings in a case of lacrimal gland enlargement secondary to lymphomatoid granulomatosis (LG) and to review the literature. Design. Case report and systematic literature review. Methods. A 75-year-old woman presented with right ptosis. Computerised tomography showed lacrimal gland enlargement, and biopsy done was inconclusive. She subsequently developed pulmonary symptoms and underwent transbronchial biopsy that was diagnosed as LG. Pub Med and OVID databases were searched using the term “orbit/eye involvement in lymphomatoid granulomatosis”. Articles that predated the databases were gathered from current references. Results. The patient underwent lacrimal gland biopsy which revealed necrotic and inflamed tissue with no further categorisation but transbronchial biopsy helped in establishing the diagnosis of LG. On initiation of prednisolone and cyclophosphamide, her orbital lesion resolved but the patient died following massive pulmonary hemorrhage within a month of diagnosis. Conclusion. Ophthalmic involvement in LG is very rare. Varied presentations are due to central nervous system involvement, vasculitis, or infiltration of ocular or orbital structures. LG is an angiocentric and angiodestructive granulomatous disorder and can involve any tissue, thus accounting for the variable presentations reported in literature
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