Immunostaining of skeletal tissues

Peer reviewedPreprin

A new method for suppressing excited-state contaminations on the nucleon form factors

One of the most challenging tasks in lattice calculations of baryon form factors is the analysis and control of excited-state contaminations. Taking the isovector axial form factors of the nucleon as an example, both a dispersive representation and a calculation in chiral effective field theory show that the excited-state contributions become dominant at fixed source-sink separation when the axial current is spatially distant from the nucleon source location. We address this effect with a new method in which the axial current is localized by a Gaussian wave-packet and apply it on a CLS ensemble with $N_f=2+1$ flavors of O($a$) improved Wilson fermions with a pion mass of $m_\pi=200\,$MeV.Comment: 7 pages, 6 figures, 1 table, Proceedings for the 36th Annual International Symposium on Lattice Field Theory, 22-28 July 2018, Michigan State University, East Lansing, Michigan, US

A Duality Exact Sequence for Legendrian Contact Homology

We establish a long exact sequence for Legendrian submanifolds L in P x R, where P is an exact symplectic manifold, which admit a Hamiltonian isotopy that displaces the projection of L off of itself. In this sequence, the singular homology H_* maps to linearized contact cohomology CH^* which maps to linearized contact homology CH_* which maps to singular homology. In particular, the sequence implies a duality between the kernel of the map (CH_*\to H_*) and the cokernel of the map (H_* \to CH^*). Furthermore, this duality is compatible with Poincare duality in L in the following sense: the Poincare dual of a singular class which is the image of a in CH_* maps to a class \alpha in CH^* such that \alpha(a)=1. The exact sequence generalizes the duality for Legendrian knots in Euclidean 3-space [24] and leads to a refinement of the Arnold Conjecture for double points of an exact Lagrangian admitting a Legendrian lift with linearizable contact homology, first proved in [6].Comment: 57 pages, 10 figures. Improved exposition and expanded analytic detai

New Keynesian versus old Keynesian government spending multipliers

Renewed interest in fiscal policy has increased the use of quantitative models to evaluate policy. Because of modeling uncertainty, it is essential that policy evaluations be robust to alternative assumptions. We find that models currently being used in practice to evaluate fiscal policy stimulus proposals are not robust. Government spending multipliers in an alternative empirically-estimated and widely-cited new Keynesian model are much smaller than in these old Keynesian models; the estimated stimulus is extremely small with GDP and employment effects only one-sixth as large

International Conference on “Foresight Studies on Work in the Knowledge Society“ in Monte de Caparica (FCT-UNL) on 19-20 October 2006

On 19 and 20 October 2006, the Research Centre on Enterprise and Work Organisation (IET) organised the first international conference on “Foresight Studies on Work in the Knowledge Society”. It took place at the auditorium of the new Library of FCT-UNL and had the support of the research project “CodeWork@VO” (financed by FCT-MCTES and co-ordinated by INESC, Porto). The conference related to the European research project “Work Organisation and Restructuring in the Knowledge Society” (WORKS), which is financed by the European Commission. The main objective of the conference was to analyse and discuss research findings on the trends of work structures in the knowledge society, and to debate on new work organisation models and new forms of work supported by ICT.Knowledge Society; work; Foresight

Light-front time picture of the Bethe-Salpeter equation

We show the light-front representation of the field theoretical Bethe-Salpeter equation (BSE) in the ladder approximation using the quasi potential reduction. We discuss the equivalence of the covariant ladder Bethe-Salpeter equation with an infinite set of coupled equations for the Green's functions of the different light-front Fock-states.Comment: 7p, Few-Body Systems (2003

Dissimilar bouncy walkers

We consider the dynamics of a one-dimensional system consisting of dissimilar hardcore interacting (bouncy) random walkers. The walkers' (diffusing particles') friction constants xi_n, where n labels different bouncy walkers, are drawn from a distribution rho(xi_n). We provide an approximate analytic solution to this recent single-file problem by combining harmonization and effective medium techniques. Two classes of systems are identified: when rho(xi_n) is heavy-tailed, rho(xi_n)=A xi_n^(-1-\alpha) (0<alpha<1) for large xi_n, we identify a new universality class in which density relaxations, characterized by the dynamic structure factor S(Q,t), follows a Mittag-Leffler relaxation, and the the mean square displacement of a tracer particle (MSD) grows as t^delta with time t, where delta=alpha/(1+\alpha). If instead rho is light-tailedsuch that the mean friction constant exist, S(Q,t) decays exponentially and the MSD scales as t^(1/2). We also derive tracer particle force response relations. All results are corroborated by simulations and explained in a simplified model.Comment: 11 pages, to appear in Journal of Chemical Physic