197 research outputs found
Nonabelian Jacobian of smooth projective surface : a survey
The nonabelian Jacobian J(X; L, d) of a smooth projective surface X is inspired by the classical theory of Jacobian of curves. It is built as a natural scheme interpolating between the Hilbert scheme X [d] of subschemes of length d of X and the stack M X (2, L, d) of torsion free sheaves of rank 2 on X having the determinant O X (L) and the second Chern class (= number) d. It relates to such influential ideas as variations of Hodge structures, period maps, nonabelian Hodge theory, Homological mirror symmetry, perverse sheaves, geometric Langlands program. These relations manifest themselves by the appearance of the following structures on J(X; L, d):
a sheaf of reductive Lie algebras
(singular) Fano toric varieties whose hyperplane sections are (singular) Calabi-Yau varieties
trivalent graphs.
This is an expository paper giving an account of most of the main properties of J(X; L, d) uncovered in Reider 2006 and ArXiv:1103.4794v1
Nonabelian Jacobian of Projective Surfaces : Geometry and Representation Theory
The Jacobian of a smooth projective curve is undoubtedly one of the most remarkable and beautiful objects in algebraic geometry. This work is an attempt to develop an analogous theory for smooth projective surfaces - a theory of the nonabelian Jacobian of smooth projective surfaces. Just like its classical counterpart, our nonabelian Jacobian relates to vector bundles (of rank 2) on a surface as well as its Hilbert scheme of points. But it also comes equipped with the variation of Hodge-like structures, which produces a sheaf of reductive Lie algebras naturally attached to our Jacobian. This constitutes a nonabelian analogue of the (abelian) Lie algebra structure of the classical Jacobian. This feature naturally relates geometry of surfaces with the representation theory of reductive Lie algebras/groups. This work’s main focus is on providing an in-depth study of various aspects of this relation. It presents a substantial body of evidence that the sheaf of Lie algebras on the nonabelian Jacobian is an efficient tool for using the representation theory to systematically address various algebro-geometric problems. It also shows how to construct new invariants of representation theoretic origin on smooth projective surfaces
MRI Parameters Of Alzheimer's Disease in an Arab Population of Wadi Ara, Israel
Magnetic resonance imaging (MRI) findings are reported from 15 individuals in an Arab–Israeli community who were diagnosed with Alzheimer's disease (AD). The quantitative parameters that were used for MRI analyses included gradings (0–3) and linear measurements of different brain structures. Generalized tissue loss was assessed by combined measurements of the ventricles (ventricular score, VS) and sulcal grading and width (SG, SW, respectively). Loss of brain tissue in specific regions of interest, eg, temporal lobes, basal ganglia, and midbrain, was evaluated by precise measurements. We observed abnormal tissue characteristics, expressed as high intensity foci in white matter on T2W sequences, as well as tissue loss, both generalized and focal. Most notable were changes involving the head of the caudate nuclei, the midbrain, and to a lesser degree, medial temporal structures.National Institute of Aging (UO1-AG17173); National Institute on Alcohol Abuse and Alcoholism (R37-AA07112, K05-AA00219); US Department of Veterans Affair
Low unesterified:esterified eicosapentaenoic acid (EPA) plasma concentration ratio is associated with bipolar disorder episodes, and omega‐3 plasma concentrations are altered by treatment
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/115916/1/bdi12337_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/115916/2/bdi12337.pd
Characterization of the 4-canonical birationality of algebraic threefolds
In this article we present a 3-dimensional analogue of a well-known theorem
of E. Bombieri (in 1973) which characterizes the bi-canonical birationality of
surfaces of general type. Let be a projective minimal 3-fold of general
type with -factorial terminal singularities and the geometric genus
. We show that the 4-canonical map is {\it not}
birational onto its image if and only if is birationally fibred by a family
of irreducible curves of geometric genus 2 with
where is a general irreducible member in .Comment: 25 pages, to appear in Mathematische Zeitschrif
Anti-Pluricanonical Systems On Q-Fano Threefolds
We investigate birationality of the anti-pluricanonical map , the
rational map defined by the anti-pluricanonical system , on
-Fano threefolds.Comment: 18 page
On complex surfaces diffeomorphic to rational surfaces
In this paper we prove that no complex surface of general type is
diffeomorphic to a rational surface, thereby completing the smooth
classification of rational surfaces and the proof of the Van de Ven conjecture
on the smooth invariance of Kodaira dimension.Comment: 34 pages, AMS-Te
Atomic excitation during recollision-free ultrafast multi-electron tunnel ionization
Modern intense ultrafast pulsed lasers generate an electric field of
sufficient strength to permit tunnel ionization of the valence electrons in
atoms. This process is usually treated as a rapid succession of isolated
events, in which the states of the remaining electrons are neglected. Such
electronic interactions are predicted to be weak, the exception being
recollision excitation and ionization caused by linearly-polarized radiation.
In contrast, it has recently been suggested that intense field ionization may
be accompanied by a two-stage `shake-up' reaction. Here we report a unique
combination of experimental techniques that enables us to accurately measure
the tunnel ionization probability for argon exposed to 50 femtosecond laser
pulses. Most significantly for the current study, this measurement is
independent of the optical focal geometry, equivalent to a homogenous electric
field. Furthermore, circularly-polarized radiation negates recollision. The
present measurements indicate that tunnel ionization results in simultaneous
excitation of one or more remaining electrons through shake-up. From an atomic
physics standpoint, it may be possible to induce ionization from specific
states, and will influence the development of coherent attosecond XUV radiation
sources. Such pulses have vital scientific and economic potential in areas such
as high-resolution imaging of in-vivo cells and nanoscale XUV lithography.Comment: 17 pages, 4 figures, original format as accepted by Nature Physic
High-intensity mechanical therapy for loss of knee extension for worker's compensation and non-compensation patients
<p>Abstract</p> <p>Background</p> <p>Knee flexion contractures have been associated with increased pain and a reduced ability to perform activities of daily living. Contractures can be treated either surgically or conservatively, but these treatment options may not be as successful with worker's compensation patients. The purposes of retrospective review were to 1) determine the efficacy of using adjunctive high-intensity stretch (HIS) mechanical therapy to treat flexion contractures, and 2) compare the results between groups of worker's compensation and non-compensation patients.</p> <p>Methods</p> <p>Fifty-six patients (19 women, 37 men, age = 51.5 ± 17.0 years) with flexion contractures were treated with HIS mechanical therapy as an adjunct to outpatient physical therapy. Mechanical therapy was only prescribed for those patients whose motion had reached a plateau when treated with physical therapy alone. Patients were asked to perform six, 10-minute bouts of end-range stretching per day with the ERMI Knee Extensionater<sup>(r) </sup>(ERMI, Inc., Atlanta, GA). Passive knee extension was recorded during the postoperative visit that mechanical therapy was prescribed, 3 months after beginning mechanical therapy, and at the most recent follow-up. We used a mixed-model 2 × 3 ANOVA (group × time) to evaluate the change in passive knee extension between groups over time.</p> <p>Results</p> <p>Regardless of group, the use of adjunctive HIS mechanical therapy resulted in passive knee extension deficits that significantly improved from 10.5° ± 5.2° at the initial visit to 2.6° ± 3.5° at the 3 month visit (p < 0.001). The degree of extension was maintained at the most recent follow-up (2.0° ± 2.9°), which was significantly greater than the initial visit (p < 0.001), but did not differ from the 3 month visit (p = 0.23). The gains in knee extension did not differ between worker's compensation and non-compensation patients (p = 0.56).</p> <p>Conclusions</p> <p>We conclude that the adjunctive use of HIS mechanical therapy is an effective treatment option for patients with knee flexion contractures, regardless of whether the patient is being treated as part of a worker's compensation claim or not.</p
Corporate Social Responsibility/Sustainability Reporting Among the Fortune Global 250: Greenwashing or Green Supply Chain?
The sustainability reporting efforts of MNCs who are members of the Fortune Global 250 (FG250) was investigated. The focus was on sustainability reporting by MNCs of supply chain impacts. The reporting of FG250 MNCs was examined to determine if greenwashing was occurring or whether MNCs had committed to operating a green supply chain. A mixed methodology was used consisting of quantitative analysis of twenty-five MNC CSR/sustainability reports which were randomly selected from the FG250 listing. Qualitative analysis using content analysis was also conducted on the reports. Both methodologies concentrated on the sustainability reporting of the selected MNCs in regard to their supply chain. Findings were mixed as there were great variations among the MNCs in their level of sustainability reporting about their supply chains. Some MNCs did not report on the activities of their supply chain at all (20%), the majority of the MNCs reported on their supply chain impacts at the value and goal level (48%), while the rest reported at the management approach level (32%). A majority of the sampled MNCs could be accused of greenwashing due to the lack of detailed quantitative information provided by the MNCs on the environmental impacts of their supply chai
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