88,525 research outputs found
Shellable weakly compact subsets of
We show that for every weakly compact subset of with finite
Cantor-Bendixson rank, there is a reflexive Banach lattice and an operator
such that . On the other hand, we
exhibit an example of a weakly compact set of homeomorphic to
for which such and cannot exist. This answers a
question of M. Talagrand in the 80's.Comment: 13 page
Cumulative Risk and a Call for Action in Environmental Justice Communities
Health disparities, social inequalities, and environmental injustice cumulatively affect individual and community vulnerability and overall health; yet health researchers, social scientists and environmental scientists generally study them separately. Cumulative risk assessment in poor, racially segregated, economically isolated and medically underserved communities needs to account for their multiple layers of vulnerability, including greater susceptibility, greater exposure, less preparedness to cope, and less ability to recover in the face of exposure. Recommendations for evidence-based action in environmental justice communities include: reducing pollution in communities of highest burden; building on community resources; redressing inequality when doing community-based research; and creating a screening framework to identify communities of greatest risk
Water splits to degrade two-dimensional group-IV monochalcogenides in nanoseconds
The experimental exfoliation of layered group-IV monochalcogenides
--semiconductors isostructural to black phosphorus-- using processes similar to
those followed in the production of graphene or phosphorene has turned out
unsuccessful thus far, as if the chemical degradation observed in black
phosphorus was aggravated in these monochalcogenides. Here, we document a
facile dissociation of water by these materials within ten nanoseconds from
room-temperature Car-Parrinello molecular dynamics calculations under standard
temperature and pressure conditions. These results suggest that humidity must
be fully eradicated to exfoliate monolayers successfully, for instance, by
placing samples in a hydrophobic solution during mechanical exfoliation. From
another materials perspective, these two-dimensional materials that create
individual hydrogen ions out of water without illumination may become relevant
for applications in hydrogen production and storage.Comment: This document is the Accepted Manuscript version of Published Work
that appeared in final form in ACS Central Science, copyright American
Chemical Society after peer review and technical editing by the publisher. To
access the final edited and published work please use the following link:
https://pubs.acs.org/doi/10.1021/acscentsci.8b0058
Geodesic Forests in the Last-Passage Percolation
The aim of this article is to study the forest composed by point-to-line
geodesics in the last-passage percolation model with exponential weights. We
will show that the location of the root can be described in terms of the maxima
of a random walk, whose distribution will depend on the geometry of the
substrate (line). For flat substrates, we will get power law behaviour of the
height function, study its scaling limit, and describe it in terms of
variational problems involving the Airy process.Comment: 20 page
Ticket to Work: Choosing the Right Employment Network
The purpose of this guide is to educate New Yorkers with disabilities who have a Ticket to Work from the Social Security Administration on how to secure the services and supports to go to work by choosing an Employment Network
The convex hull of a Banach-Saks set
A subset of a Banach space is called Banach-Saks when every sequence in
has a Ces{\`a}ro convergent subsequence. Our interest here focusses on the
following problem: is the convex hull of a Banach-Saks set again Banach-Saks?
By means of a combinatorial argument, we show that in general the answer is
negative. However, sufficient conditions are given in order to obtain a
positive result.Comment: 29 page
Supplemental Security Income: Calculating the Impact of Earnings on Benefits
The purpose of this guide is to educate New Yorkers with disabilities about the impact of earnings on Supplemental Security Income benefits
Negative results for approximation using single layer and multilayer feedforward neural networks
We prove a negative result for the approximation of functions defined on
compact subsets of (where ) using feedforward neural
networks with one hidden layer and arbitrary continuous activation function. In
a nutshell, this result claims the existence of target functions that are as
difficult to approximate using these neural networks as one may want. We also
demonstrate an analogous result (for general ) for neural
networks with an \emph{arbitrary} number of hidden layers, for activation
functions that are either rational functions or continuous splines with
finitely many pieces.Comment: 12 pages, submitted to a Journa
Dynamic analysis and control PID path of a model type gantry crane
This paper presents an alternate form for the dynamic modelling of a
mechanical system that simulates in real life a gantry crane type, using
Euler's classical mechanics and Lagrange formalism, which allows find the
equations of motion that our model describe. Moreover, it has a basic model
design system using the SolidWorks software, based on the material and
dimensions of the model provides some physical variables necessary for
modelling. In order to verify the theoretical results obtained, a contrast was
made between solutions obtained by simulation in SimMechanics-Matlab and
Euler-Lagrange equations system, has been solved through Matlab libraries for
solving equation's systems of the type and order obtained. The force is
determined, but not as exerted by the spring, as this will be the control
variable. The objective to bring the mass of the pendulum from one point to
another with a specified distance without the oscillation from it, so that, the
answer is overdamped. This article includes an analysis of PID control in which
the equations of motion of Euler-Lagrange are rewritten in the state space,
once there, they were implemented in Simulink to get the natural response of
the system to a step input in F and then draw the desired trajectories
Fundamental units of length and time
Ideal rods and clocks are defined as an infinitesimal symmetry of the
spacetime. Since no a priori geometric structure is considered, all the
possible models of spacetime are obtained.Comment: Part of the results of this article has been announced at the meeting
``XXIV International Workshop on the Fundamental Problems of High Energy
Physics and Field Theory'' 27-29 June 2001, Protvino, Russi
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