213 research outputs found
The Breathing Mode in Extended Skyrme Model
We study an extended Skyrme model which includes fourth and sixth-order
terms. We explore some static properties like the -nucleon mass
splitting and investigate the Skyrmion breathing mode in the framework of the
linear response theory. We find that the monopole response function has a
pronounced peak located at 400 MeV, which we identify to the Roper
resonance . As compared to the standard one, the extended Skyrme model
provides a more accurate description of baryon properties.Comment: 12 pages of plain Latex and 3 figures (available from the authors),
preprint IPNO/TH 93-0
Effective chiral Lagrangians for spin-1 mesons
The commonly used types of effective theory for vector mesons are reviewed
and their relationships clarified. They are shown to correspond to different
choices of field for spin-1 particles and the rules for transforming between
them are described. The importance of respecting chiral symmetry is stressed.
The choice of fields that transform homogeneously under the nonlinear
realisation of chiral symmetry imposes no preconceptions about the types of
coupling for the mesons. This representation thus provides a convenient
framework for relating different theories. It is also used to elucidate the
nature of the assumptions in specific hidden-gauge and massive Yang-Mills
models that have been widely used.Comment: 46 pages (RevTeX
Outcomes of patients with advanced idiopathic pulmonary fibrosis treated with nintedanib or pirfenidone in a real-world multicentre cohort
Background and objective Antifibrotic therapy with nintedanib or pirfenidone slows disease progression and reduces mortality in patients with idiopathic pulmonary fibrosis (IPF). However, patients with advanced IPF, as defined by forced vital capacity (FVC) < 50% and/or diffusion capacity for carbon monoxide (DLCO) < 30% of predicted, have not been included in randomized trials, and the outcomes of such patients who initiate treatment are not well understood. We determined lung function, disease progression and mortality outcomes following initiation of antifibrotic therapy in patients with advanced IPF at the time of treatment initiation compared to those with mild-moderate IPF. Methods We included 502 patients enrolled in IPF registries from four Nordic countries. Linear mixed models were used to assess change in FVC and DLCO over time. Cox proportional hazards models were used to assess transplant-free survival and progression- and transplant-free survival. Results Of 502 patients, 66 (13%) had advanced IPF. Annual change in FVC was -125 ml (95% CI -163, -87) among patients with mild-moderate IPF, and +28 ml (95% CI -96, +152) among those with advanced IPF. Advanced IPF at treatment initiation was associated with poorer transplant-free survival (hazard ratio [HR] 2.39 [95% CI 1.66, 3.43]) and progression- and transplant-free survival (HR 1.60 [95% CI 1.15, 2.23]). Conclusion In a broadly representative IPF population, patients with advanced IPF at the initiation of antifibrotic therapy did not have greater lung function decline over time compared with those with mild-moderate IPF, but had substantially higher mortality. Prospective studies are needed to determine the effect of antifibrotic therapy in patients with advanced IPF.Peer reviewe
On different lagrangian formalisms for vector resonances within chiral perturbation theory
We study the relation of vector Proca field formalism and antisymmetric
tensor field formalism for spin-one resonances in the context of the large N_C
inspired chiral resonance Lagrangian systematically up to the order O(p6) and
give a transparent prescription for the transition from vector to antisymmetric
tensor Lagrangian and vice versa. We also discuss the possibility to describe
the spin-one resonances using an alternative "mixed" first order formalism,
which includes both types of fields simultaneously, and compare this one with
the former two. We also briefly comment on the compatibility of the above
lagrangian formalisms with the high-energy constraints for concrete VVP
correlator.Comment: 34 pages, 3 figure
Cooperative Regulation of the Activity of Factor Xa within Prothrombinase by Discrete Amino Acid Regions from Factor Va Heavy Chain†
ABSTRACT: The prothrombinase complex catalyzes the activation of prothrombin to R-thrombin. We have repetitively shown that amino acid region 695DYDY698 from the COOH terminus of the heavy chain of factor Va regulates the rate of cleavage of prothrombin at Arg271 by prothrombinase. We have also recently demonstrated that amino acid region 334DY335 is required for the optimal activity of prothrombinase. To assess the effect of these six amino acid residues on cofactor activity, we created recombinant factor Va molecules combining mutations at amino acid regions 334–335 an
Isoscalar NN spin-orbit potential from a Skyrme model with scalar mesons
As a first step toward circumventing the difficulty to obtain an attractive
isospin-independent NN spin-orbit force from Skyrme-type models involving only
pions, we investigate an improved Skyrme Lagrangian that incorporates the
scalar-isoscalar meson \epsilon which can be viewed as the cause behind the
enhancement of the -wave. We find that at large distances, the main
contribution to the spin-orbit potential comes from the scalar Lagrangian and
it is found to be attractive. We briefly discuss how to pursue this work to
finally obtain a medium-range attractive interaction.Comment: 10 pages (revtex) + 2 figures; use \psfig command. Minor changes in
the text and some discussion added in the last section. To be published in Z.
Phys.
Consumer perceptions of co-branding alliances: Organizational dissimilarity signals and brand fit
This study explores how consumers evaluate co-branding alliances between dissimilar partner firms. Customers are well aware that different firms are behind a co-branded product and observe the partner firms’ characteristics. Drawing on signaling theory, we assert that consumers use organizational characteristics as signals in their assessment of brand fit and for their purchasing decisions. Some organizational signals are beyond the control of the co-branding partners or at least they cannot alter them on short notice. We use a quasi-experimental design and test how co-branding partner dissimilarity affects brand fit perception. The results show that co-branding partner dissimilarity in terms of firm size, industry scope, and country-of-origin image negatively affects brand fit perception. Firm age dissimilarity does not exert significant influence. Because brand fit generally fosters a benevolent consumer attitude towards a co-branding alliance, the findings suggest that high partner dissimilarity may reduce overall co-branding alliance performance
Procoagulant Adaptation of a Blood Coagulation Prothrombinase-like Enzyme Complex in Australian Elapid Venom
The macromolecular enzyme complex prothrombinase serves an indispensable role in blood coagulation as it catalyzes the conversion of prothrombin to thrombin, a key regulatory enzyme in the formation of a blood clot. Interestingly, a virtually identical enzyme complex is found in the venom of some Australian elapid snakes, which is composed of a cofactor factor Va-component and a serine protease factor Xa-like subunit. This review will provide an overview of the identification and characterization of the venom prothrombinase complex and will discuss the rationale for its powerful procoagulant nature responsible for the potent hemostatic toxicity of the elapid venom
Endocytosis of plasma-derived factor V by megakaryocytes occurs via a clathrin-dependent, specific membrane binding event
Megakaryocytes were analyzed for their ability to endocytose factor V to define the cellular mechanisms regulating this process. In contrast to fibrinogen, factor V was endocytosed by megakaryocytes derived from CD34 + cells or megakaryocyte-like cell lines, but not by platelets. CD41 + ex vivo -derived megakaryocytes endocytosed factor V, as did subpopulations of the megakaryocyte-like cells MEG-01, and CMK. Similar observations were made for fibrinogen. Phorbol diester-induced megakaryocytic differentiation of the cell lines resulted in a substantial increase in endocytosis of both proteins as compared to untreated cells that did not merely reflect their disparate plasma concentrations. Factor IX, which does not associate with platelets or megakaryocytes, was not endocytosed by any of the cells examined. Endocytosis of factor V by megakaryocytes proceeds through a specific and independent mechanism as CHRF-288 cells endocytosed fibrinogen but not factor V, and the presence of other plasma proteins had no effect on the endocytosis of factor V by MEG-01 cells. Furthermore, as the endocytosis of factor V was also demonstrated to occur through a clathrin-dependent mechanism, these combined data demonstrate that endocytosis of factor V by megakaryocytes occurs via a specific, independent, and most probably receptor-mediated, event.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75473/1/j.1538-7836.2005.01190.x.pd
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