428 research outputs found
Local representations of the loop braid group
We study representations of the loop braid group LBn from the perspective of extending representations of the braid group Bn. We also pursue a generalization of the braid/Hecke/Temperlely-Lieb paradigm-uniform finite dimensional quotient algebras of the loop braid group algebras
Daydreaming factories
Optimisation of factories, a cornerstone of production engineering for the past half century, relies on formulating the challenges with limited degrees of freedom. In this paper, technological advances are reviewed to propose a “daydreaming” framework for factories that use their cognitive capacity for looking into the future or “foresighting”. Assessing and learning from the possible eventualities enable breakthroughs with many degrees of freedom and make daydreaming factories antifragile. In these factories with augmented and reciprocal learning and foresighting processes, revolutionary reactions to external and internal stimuli are unnecessary and industrial co-evolution of people, processes and products will replace industrial revolutions
Electrical stimulation alleviates depressive-like behaviors of rats: investigation of brain targets and potential mechanisms
Deep brain stimulation (DBS) is a promising therapy for patients with refractory depression. However, key questions remain with regard to which brain target(s) should be used for stimulation, and which mechanisms underlie the therapeutic effects. Here, we investigated the effect of DBS, with low- and high-frequency stimulation (LFS, HFS), in different brain regions (ventromedial prefrontal cortex, vmPFC; cingulate cortex, Cg; nucleus accumbens (NAc) core or shell; lateral habenula, LHb; and ventral tegmental area) on a variety of depressive-like behaviors using rat models. In the naive animal study, we found that HFS of the Cg, vmPFC, NAc core and LHb reduced anxiety levels and increased motivation for food. In the chronic unpredictable stress model, there was a robust depressive-like behavioral phenotype. Moreover, vmPFC HFS, in a comparison of all stimulated targets, produced the most profound antidepressant effects with enhanced hedonia, reduced anxiety and decreased forced-swim immobility. In the following set of electrophysiological and histochemical experiments designed to unravel some of the underlying mechanisms, we found that vmPFC HFS evoked a specific modulation of the serotonergic neurons in the dorsal raphe nucleus (DRN), which have long been linked to mood. Finally, using a neuronal mapping approach by means of c-Fos expression, we found that vmPFC HFS modulated a brain circuit linked to the DRN and known to be involved in affect. In conclusion, HFS of the vmPFC produced the most potent antidepressant effects in naive rats and rats subjected to stress by mechanisms also including the DRN.postprin
Polygon model from first order gravity
The gauge fixed polygon model of 2+1 gravity with zero cosmological constant
and arbitrary number of spinless point particles is reconstructed from the
first order formalism of the theory in terms of the triad and the spin
connection. The induced symplectic structure is calculated and shown to agree
with the canonical one in terms of the variables.Comment: 20 pages, presentation improved, typos correcte
Short-time scaling behavior of growing interfaces
The short-time evolution of a growing interface is studied within the
framework of the dynamic renormalization group approach for the
Kadar-Parisi-Zhang (KPZ) equation and for an idealized continuum model of
molecular beam epitaxy (MBE). The scaling behavior of response and correlation
functions is reminiscent of the ``initial slip'' behavior found in purely
dissipative critical relaxation (model A) and critical relaxation with
conserved order parameter (model B), respectively. Unlike model A the initial
slip exponent for the KPZ equation can be expressed by the dynamical exponent
z. In 1+1 dimensions, for which z is known exactly, the analytical theory for
the KPZ equation is confirmed by a Monte-Carlo simulation of a simple ballistic
deposition model. In 2+1 dimensions z is estimated from the short-time
evolution of the correlation function.Comment: 27 pages LaTeX with epsf style, 4 figures in eps format, submitted to
Phys. Rev.
Layer-by-Layer Assembled Nanowire Networks Enable Graph Theoretical Design of Multifunctional Coatings
Multifunctional coatings are central for information, biomedical,
transportation and energy technologies. These coatings must possess
hard-to-attain properties and be scalable, adaptable, and sustainable, which
makes layer-by-layer assembly (LBL) of nanomaterials uniquely suitable for
these technologies. What remains largely unexplored is that LBL enables
computational methodologies for structural design of these composites.
Utilizing silver nanowires (NWs), we develop and validate a graph theoretical
(GT) description of their LBL composites. GT successfully describes the
multilayer structure with nonrandom disorder and enables simultaneous rapid
assessment of several properties of electrical conductivity, electromagnetic
transparency, and anisotropy. GT models for property assessment can be rapidly
validated due to (1) quasi-2D confinement of NWs and (2) accurate microscopy
data for stochastic organization of the NW networks. We finally show that
spray-assisted LBL offers direct translation of the GT-based design of
composite coatings to additive, scalable manufacturing of drone wings with
straightforward extensions to other technologies
Timelike surfaces in Lorentz covariant loop gravity and spin foam models
We construct a canonical formulation of general relativity for the case of a
timelike foliation of spacetime. The formulation possesses explicit covariance
with respect to Lorentz transformations in the tangent space. Applying the loop
approach to quantize the theory we derive the spectrum of the area operator of
a two-dimensional surface. Its different branches are naturally associated to
spacelike and timelike surfaces. The results are compared with the predictions
of Lorentzian spin foam models. A restriction of the representations labeling
spin networks leads to perfect agreement between the states as well as the area
spectra in the two approaches.Comment: a wrong sign corrected in equation (65
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