680 research outputs found
On the PIE root-structure constraint prohibiting repeated consonants
This paper confronts and resolves the problem of apparent exceptions to the constraint prohibiting the co-occurrence of identical consonants in both syllable margins of the PIE root: schematically, †… Ci … E … Ci …, where † indicates the prohibition of the root structure following it, Ci = the identical consonant, E = the ablauting vowel, and … = optional additional consonants in the syllable margins. In advancement of previous work addressing this problem — most recently exemplified in Cooper (2009), Corbeau (2013) and Weiss (2020) — it eliminates several potential exceptions to the constraint and proposes that, once a cross-linguistic absence-of-contrast principle is taken into account which determines the relation of laryngeal features (glottalization, aspiration, and voicing) to the syllable margins that contain them, no clear-cut exceptions remain
On black hole thermalization, D0 brane dynamics, and emergent spacetime
When matter falls past the horizon of a large black hole, the expectation
from string theory is that the configuration thermalizes and the information in
the probe is rather quickly scrambled away. The traditional view of a classical
unique spacetime near a black hole horizon conflicts with this picture. The
question then arises as to what spacetime does the probe actually see as it
crosses a horizon, and how does the background geometry imprint its signature
onto the thermal properties of the probe. In this work, we explore these
questions through an extensive series of numerical simulations of D0 branes. We
determine that the D0 branes quickly settle into an incompressible symmetric
state -- thermalized within a few oscillations through a process driven
entirely by internal non-linear dynamics. Surprisingly, thermal background
fluctuations play no role in this mechanism. Signatures of the background
fields in this thermal state arise either through fluxes, i.e. black hole hair;
or if the probe expands to the size of the horizon -- which we see evidence of.
We determine simple scaling relations for the D0 branes' equilibrium size, time
to thermalize, lifetime, and temperature in terms of their number, initial
energy, and the background fields. Our results are consistent with the
conjecture that black holes are the fastest scramblers as seen by Matrix
theory.Comment: 43 pages, 12 figures; v2: added analysis showing that results are
consistent with and confirm Susskind conjecture on black hole thermalization.
Added clarification about strong coupling regime. Citation adde
Glassy correlations and microstructures in randomly crosslinked homopolymer blends
We consider a microscopic model of a polymer blend that is prone to phase
separation. Permanent crosslinks are introduced between randomly chosen pairs
of monomers, drawn from the Deam-Edwards distribution. Thereby, not only
density but also concentration fluctuations of the melt are quenched-in in the
gel state, which emerges upon sufficient crosslinking. We derive a Landau
expansion in terms of the order parameters for gelation and phase separation,
and analyze it on the mean-field level, including Gaussian fluctuations. The
mixed gel is characterized by thermal as well as time-persistent (glassy)
concentration fluctuations. Whereas the former are independent of the
preparation state, the latter reflect the concentration fluctuations at the
instant of crosslinking, provided the mesh size is smaller than the correlation
length of phase separation. The mixed gel becomes unstable to microphase
separation upon lowering the temperature in the gel phase. Whereas the length
scale of microphase separation is given by the mesh size, at least close to the
transition, the emergent microstructure depends on the composition and
compressibility of the melt. Hexagonal structures, as well as lamellae or
random structures with a unique wavelength, can be energetically favorable.Comment: 19 pages, 10 figures. Submitted to the Journal of Chemical Physics
(http://jcp.aip.org
Generative Sliced MMD Flows with Riesz Kernels
Maximum mean discrepancy (MMD) flows suffer from high computational costs in
large scale computations. In this paper, we show that MMD flows with Riesz
kernels , have exceptional properties which
allow for their efficient computation. First, the MMD of Riesz kernels
coincides with the MMD of their sliced version. As a consequence, the
computation of gradients of MMDs can be performed in the one-dimensional
setting. Here, for , a simple sorting algorithm can be applied to reduce
the complexity from to for two empirical
measures with and support points. For the implementations we
approximate the gradient of the sliced MMD by using only a finite number of
slices. We show that the resulting error has complexity , where
is the data dimension. These results enable us to train generative models
by approximating MMD gradient flows by neural networks even for large scale
applications. We demonstrate the efficiency of our model by image generation on
MNIST, FashionMNIST and CIFAR10
A proposal for a thesaurus for web services in solar radiation
International audienceMetadata are necessary to discover, describe and exchange any type of information, resource and service at a large scale. A significant amount of effort has been made in the field of geography and environment to establish standards. Efforts still remain to address more specific domains such as renewable energies. This communication focuses on solar energy and more specifically on aspects in solar radiation that relate to geography and meteorology. A thesaurus in solar radiation is proposed for the keys elements in solar radiation namely time, space and radiation types. The importance of time-series in solar radiation is outlined and attributes of the key elements are discussed. An XML schema for encoding metadata is proposed. The exploitation of such a schema in web services is discussed. This proposal is a first attempt at establishing a thesaurus for describing data and applications in solar radiation
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