1,149 research outputs found
Hypertemporal Imaging of NYC Grid Dynamics
Hypertemporal visible imaging of an urban lightscape can reveal the phase of
the electrical grid granular to individual housing units. In contrast to
in-situ monitoring or metering, this method offers broad, persistent,
real-time, and non-permissive coverage through a single camera sited at an
urban vantage point. Rapid changes in the phase of individual housing units
signal changes in load (e.g., appliances turning on and off), while slower
building- or neighborhood-level changes can indicate the health of distribution
transformers. We demonstrate the concept by observing the 120 Hz flicker of
lights across a NYC skyline. A liquid crystal shutter driven at 119.75 Hz
down-converts the flicker to 0.25 Hz, which is imaged at a 4 Hz cadence by an
inexpensive CCD camera; the grid phase of each source is determined by analysis
of its sinusoidal light curve over an imaging "burst" of some 25 seconds.
Analysis of bursts taken at ~15 minute cadence over several hours demonstrates
both the stability and variation of phases of halogen, incandescent, and some
fluorescent lights. Correlation of such results with ground-truth data will
validate a method that could be applied to better monitor electricity
consumption and distribution in both developed and developing cities.Comment: This paper uses astronomical techniques applied to the study of urban
lights. This research is reproducible but the data access is restricted. A
Github repository contains all code supporting this research as well as
additional material: https://github.com/fedhere/detect12
BCS - BEC crossover at T=0: A Dynamical Mean Field Theory Approach
We study the T=0 crossover from the BCS superconductivity to Bose-Einstein
condensation in the attractive Hubbard Model within dynamical mean field
theory(DMFT) in order to examine the validity of Hartree-Fock-Bogoliubov (HFB)
mean field theory, usually used to describe this crossover, and to explore
physics beyond it. Quantum fluctuations are incorporated using iterated
perturbation theory as the DMFT impurity solver. We find that these
fluctuations lead to large quantitative effects in the intermediate coupling
regime leading to a reduction of both the superconducting order parameter and
the energy gap relative to the HFB results. A qualitative change is found in
the single-electron spectral function, which now shows incoherent spectral
weight for energies larger than three times the gap, in addition to the usual
Bogoliubov quasiparticle peaks.Comment: 11 pages,12 figures, Published versio
Verification and Validation of Semantic Annotations
In this paper, we propose a framework to perform verification and validation
of semantically annotated data. The annotations, extracted from websites, are
verified against the schema.org vocabulary and Domain Specifications to ensure
the syntactic correctness and completeness of the annotations. The Domain
Specifications allow checking the compliance of annotations against
corresponding domain-specific constraints. The validation mechanism will detect
errors and inconsistencies between the content of the analyzed schema.org
annotations and the content of the web pages where the annotations were found.Comment: Accepted for the A.P. Ershov Informatics Conference 2019(the PSI
Conference Series, 12th edition) proceedin
EMT and MET: necessary or permissive for metastasis?
Epithelial-to-mesenchymal transition (EMT) and its reverse mesenchymal-to-epithelial transition (MET) have been suggested to play crucial roles in metastatic dissemination of carcinomas. These phenotypic transitions between states are not binary. Instead, carcinoma cells often exhibit a spectrum of epithelial/mesenchymal phenotype(s). While epithelial/mesenchymal plasticity has been observed preclinically and clinically, whether any of these phenotypic transitions are indispensable for metastatic outgrowth remains an unanswered question. Here, we focus on epithelial/mesenchymal plasticity in metastatic dissemination and propose alternative mechanisms for successful dissemination and metastases beyond the traditional EMT/MET view. We highlight multiple hypotheses that can help reconcile conflicting observations, and outline the next set of key questions that can offer valuable insights into mechanisms of metastasis in multiple tumor models
Optimising the flow through a concertinaed filtration membrane
Membrane filtration is a vital industrial process, with applications
including air purification and blood filtration. In this paper, we study the
optimal design for a concertinaed filtration membrane composed of angled porous
membranes and dead-ends. We examine how the filter performance depends on the
angle, position, thickness, and permeance of the membrane, through a
combination of numerical and asymptotic approaches, the latter in the limit of
a slightly angled membrane. We find that, for a membrane of fixed angle and
physical properties, there can exist multiple membrane positions that maximise
the flux for an applied pressure difference. More generally, we show that while
the maximal flux achievable depends on the membrane thickness and permeance,
the optimal membrane configuration is always in one of two setups: centred and
diagonal across the full domain; or angled and in the corner of the domain.Comment: 24 pages, 10 figure
Viscosity of strongly interacting quantum fluids: spectral functions and sum rules
The viscosity of strongly interacting systems is a topic of great interest in
diverse fields.
We focus here on the bulk and shear viscosities of \emph{non-relativistic}
quantum fluids, with particular emphasis on strongly interacting ultracold
Fermi gases. We use Kubo formulas for the bulk and shear viscosity spectral
functions, and respectively, to derive exact,
non-perturbative results. Our results include: a microscopic connection between
the shear viscosity and the normal fluid density ; sum rules for
and and their evolution through the BCS-BEC
crossover; universal high-frequency tails for and the dynamic
structure factor . We use our sum rules to show that, at
unitarity, is identically zero and thus relate
to density-density correlations. We predict that frequency-dependent shear
viscosity of the unitary Fermi gas can be experimentally
measured using Bragg spectroscopy.Comment: Published versio
- …