1,081 research outputs found
Algebraic Torsion in Contact Manifolds
We extract a nonnegative integer-valued invariant, which we call the "order
of algebraic torsion", from the Symplectic Field Theory of a closed contact
manifold, and show that its finiteness gives obstructions to the existence of
symplectic fillings and exact symplectic cobordisms. A contact manifold has
algebraic torsion of order zero if and only if it is algebraically overtwisted
(i.e. has trivial contact homology), and any contact 3-manifold with positive
Giroux torsion has algebraic torsion of order one (though the converse is not
true). We also construct examples for each nonnegative k of contact 3-manifolds
that have algebraic torsion of order k but not k - 1, and derive consequences
for contact surgeries on such manifolds. The appendix by Michael Hutchings
gives an alternative proof of our cobordism obstructions in dimension three
using a refinement of the contact invariant in Embedded Contact Homology.Comment: 53 pages, 4 figures, with an appendix by Michael Hutchings; v.3 is a
final update to agree with the published paper, and also corrects a minor
error that appeared in the published version of the appendi
Digital technology and governance in transition: The case of the British Library
Comment on the organizational consequences of the new information and communications technologies (ICTs) is pervaded by a powerful imagery of disaggregation and a tendency for ?virtual? forms of production to be seen as synonymous with the ?end? of bureaucracy. This paper questions the underlying assumptions of the ?virtual organization?, highlighting the historically enduring, diversified character of the bureaucratic form. The paper then presents case study findings on the web-based access to information resources now being provided by the British Library (BL). The case study evidence produces two main findings. First, radically decentralised virtual forms of service delivery are heavily dependent on new forms of capacity-building and information aggregation. Second, digital technology is embedded in an inherently contested and contradictory context of institutional change. Current developments in the management and control of digital rights are consistent with the commodification of the public sphere. However, the evidence also suggests that scholarly access to information resources is being significantly influenced by the ?information society? objectives of the BL and other institutional players within the network of UK research libraries
Dangerous work: The gendered nature of bullying in the context of higher education
This paper discusses results from a research project which set out to investigate gender differences in the nature and experience of bullying within the higher education sector. Gender differences emerged in the form and perception of bullying as well as in target response. Results also indicate that, irrespective of gender, bullies can capture and subvert organizational structures and procedures (official hierarchies, mentoring systems, probationary reviews) to further their abuse of the target and to conceal aggressive intent. These outcomes are discussed in relation to gendered assumptions behind management practices and in relation to the masculinist ethic that underpins many higher education management initiatives. Overall, results indicate that bullying cannot be divorced from gender and that such behaviour needs to be seen in a gendered context
Population Modeling Highlights Drug Disposition Differences Between Tenofovir Alafenamide and Tenofovir Disoproxil Fumarate in the Blood and Semen
Understanding antiretroviral disposition in the male genital tract, a distinct viral compartment, can provide insight for the eradication of HIV. Population pharmacokinetic modeling was conducted to investigate the disposition of tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF), and emtricitabine and their metabolites in blood and semen. Blood plasma and seminal plasma (SP) concentrations of tenofovir and emtricitabine were measured, as were tenofovir-diphosphate and emtricitabine-triphosphate concentrations in peripheral blood mononuclear cells (PBMCs) and seminal mononuclear cells. Sequential compartmental modeling described drug disposition in blood and semen. Our modeling suggests slower elimination of apparent tenofovir-diphosphate PBMC and faster elimination of tenofovir SP after administration of TAF compared with TDF, likely reflecting flip-flop kinetics. Additionally, TAF metabolism to tenofovir appeared slower in semen compared with blood; however, SP elimination of TAF-derived tenofovir appeared faster than its blood plasma elimination. These findings provide valuable insight for further mechanistic study of cellular entry and drug metabolism in the male genital tract
Cell shape analysis of random tessellations based on Minkowski tensors
To which degree are shape indices of individual cells of a tessellation
characteristic for the stochastic process that generates them? Within the
context of stochastic geometry and the physics of disordered materials, this
corresponds to the question of relationships between different stochastic
models. In the context of image analysis of synthetic and biological materials,
this question is central to the problem of inferring information about
formation processes from spatial measurements of resulting random structures.
We address this question by a theory-based simulation study of shape indices
derived from Minkowski tensors for a variety of tessellation models. We focus
on the relationship between two indices: an isoperimetric ratio of the
empirical averages of cell volume and area and the cell elongation quantified
by eigenvalue ratios of interfacial Minkowski tensors. Simulation data for
these quantities, as well as for distributions thereof and for correlations of
cell shape and volume, are presented for Voronoi mosaics of the Poisson point
process, determinantal and permanental point processes, and Gibbs hard-core and
random sequential absorption processes as well as for Laguerre tessellations of
polydisperse spheres and STIT- and Poisson hyperplane tessellations. These data
are complemented by mechanically stable crystalline sphere and disordered
ellipsoid packings and area-minimising foam models. We find that shape indices
of individual cells are not sufficient to unambiguously identify the generating
process even amongst this limited set of processes. However, we identify
significant differences of the shape indices between many of these tessellation
models. Given a realization of a tessellation, these shape indices can narrow
the choice of possible generating processes, providing a powerful tool which
can be further strengthened by density-resolved volume-shape correlations.Comment: Chapter of the forthcoming book "Tensor Valuations and their
Applications in Stochastic Geometry and Imaging" in Lecture Notes in
Mathematics edited by Markus Kiderlen and Eva B. Vedel Jense
The New âHidden Abodeâ: Reflections on Value and Labour in the New Economy
In a pivotal section of Capital, volume 1, Marx (1976: 279) notes that, in order to understand the capitalist production of value, we must descend into the âhidden abode of productionâ: the site of the labour process conducted within an employment relationship. In this paper we argue that by remaining wedded to an analysis of labour that is confined to the employment relationship, Labour Process Theory (LPT) has missed a fundamental shift in the location of value production in contemporary capitalism. We examine this shift through the work of Autonomist Marxists like Hardt and Negri, Lazaratto and Arvidsson, who offer theoretical leverage to prize open a new âhidden abodeâ outside employment, for example in the âproduction of organizationâ and in consumption. Although they can open up this new âhidden abodeâ, without LPT's fine-grained analysis of control/resistance, indeterminacy and structured antagonism, these theorists risk succumbing to empirically naive claims about the ânew economyâ. Through developing an expanded conception of a ânew hidden abodeâ of production, the paper demarcates an analytical space in which both LPT and Autonomist Marxism can expand and develop their understanding of labour and value production in today's economy. </jats:p
Differential Extracellular, but Similar Intracellular, Disposition of two Tenofovir Formulations in the Male Genital Tract
Background: The male genital tract (MGT) is a viral sanctuary and likely HIV reservoir; understanding MGT pharmacokinet-ics (PK) of antiretrovirals (ARVs) used for curative strategies is critical to eradication and cure. Tenofovir alafenamide (TAF) is a tenofovir (TFV) formulation designed to maximize efficacy/minimize toxicity with unknown MGT PK. Methods: HIV-positive and HIV-negative men receiving TFV-based regimens provided six paired blood plasma (BP) and semen samples. Extracellular (TFV, TAF, emtricitabine [FTC]) drug concentrations in BP and seminal plasma (SP), and intracellular metabolite (IM) and endogenous nucleotide (EN) concentrations were measured in peripheral blood mononuclear cells (PBMCs) and seminal mononuclear cells (SMCs). Exposure ratios for SP:BP, SMC:PBMC and IM:EN were calculated from PK parameters generated by noncompartmental analysis. HIV viral load was measured in BP and SP. Results: Sixteen HIV-positive (n=8, TDF/FTC; n=8, TAF/FTC) and eight HIV-negative (TDF/FTC) men provided samples. Median TFV SP:BP ratios differed between TDF and TAF (1.5 versus 7.4), due to lower TFV BP concentrations with TAF coupled with TFV SP concentrations similar to TDF. FTC SP:BP ratios were approximately 3. SMC concentrations of IMs and ENs were a fraction of PBMC concentrations (1â22%), though IM:EN ratios exceed a suggested protective threshold. Conclusions: TAF SP PK was unexpected. IM SMC concentrations were low relative to PBMC, as were EN concentrations, suggesting differences in cell phenotype and lineage in the MGT; these differences in phenotype and pharmacology may have an impact on selecting and dosing ARVs used in cure strategies
Rapid analysis of local data to inform off-label tocilizumab use early in the COVID-19 pandemic
The interleukin-6 receptor antagonist tocilizumab became widely used early in the coronavirus disease 2019 (COVID-19) pandemic based on small observational studies that suggested clinical benefit in COVID-19 patients with a hyperinflammatory state. To inform our local treatment algorithms in the absence of randomized clinical trial results, we performed a rapid analysis of the first 11 hospitalized COVID-19 patients treated with tocilizumab at our academic medical center. We report their early clinical outcomes and describe the process by which we assembled a team of diverse trainees and stakeholders to extract, analyze, and disseminate data during a time of clinical uncertainty
Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV
A search for pair-production of supersymmetric particles under the assumption
that R-parity is violated via a dominant LQDbar coupling has been performed
using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV.
The observed candidate events in the data are in agreement with the Standard
Model expectation. This result is translated into lower limits on the masses of
charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for
m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81
GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the
95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
Search for the glueball candidates f0(1500) and fJ(1710) in gamma gamma collisions
Data taken with the ALEPH detector at LEP1 have been used to search for gamma
gamma production of the glueball candidates f0(1500) and fJ(1710) via their
decay to pi+pi-. No signal is observed and upper limits to the product of gamma
gamma width and pi+pi- branching ratio of the f0(1500) and the fJ(1710) have
been measured to be Gamma_(gamma gamma -> f0(1500)). BR(f0(1500)->pi+pi-) <
0.31 keV and Gamma_(gamma gamma -> fJ(1710)). BR(fJ(1710)->pi+pi-) < 0.55 keV
at 95% confidence level.Comment: 10 pages, 3 figure
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