6,656 research outputs found
A thermodynamic uncertainty relation for a system with memory
We introduce an example of thermodynamic uncertainty relation (TUR) for
systems modeled by a one-dimensional generalised Langevin dynamics with memory,
determining the motion of a micro-bead driven in a complex fluid. Contrary to
TURs typically discussed in the previous years, our observables and the entropy
production rate are one-time variables. The bound to the signal-to-noise ratio
of such state-dependent observables only in some cases can be mapped to the
entropy production rate. For example, this is true in Markovian systems. Hence,
the presence of memory in the system complicates the thermodynamic
interpretation of the uncertainty relation
Gabriel-Ulmer duality for topoi and its relation with site presentations
Let be a regular cardinal. We study Gabriel-Ulmer duality when one
restricts the 2-category of locally -presentable categories with
-accessible right adjoints to its locally full sub-2-category of
-presentable Grothendieck topoi with geometric -accessible
morphisms. In particular, we provide a full understanding of the locally full
sub-2-category of the 2-category of -small cocomplete categories with
-colimit preserving functors arising as the corresponding 2-category of
presentations via the restriction. We analyse the relation of these
presentations of Grothendieck topoi with site presentations and we show that
the 2-category of locally -presentable Grothendieck topoi with
geometric -accessible morphisms is a reflective sub-bicategory of the
full sub-2-category of the 2-category of sites with morphisms of sites
genearated by the weakly -ary sites in the sense of Shulman [37].Comment: 25 page
Electromagnetic Form Factors of Nucleons in a Light-cone Diquark Model
We investigate the electromagnetic form factors of nucleons within a simple
relativistic quark spectator-diquark model using the light-cone formalism.
Melosh rotations are applied to both quark and vector diquark. It is shown that
the difference between vector and scalar spectator diquarks reproduces the
right electric form factor of neutrons, and both the form factors
and of the proton and neutron agree with experimental data well up
to in this simple model.Comment: 16 pages, Revtex4, minor changes, to appear in Phys. Rev.
The geometry of Coherent topoi and Ultrastructures
We show that coherent topoi are right Kan injective with respect to flat
embeddings of topoi. We recover the ultrastructure on their category of points
as a consequence of this result. We speculate on possible notions of
ultracategory in various arenas of formal model theory.Comment: 24 pages. Comments are welcome
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