8,444 research outputs found
TEA: A Code for Calculating Thermochemical Equilibrium Abundances
We present an open-source Thermochemical Equilibrium Abundances (TEA) code
that calculates the abundances of gaseous molecular species. The code is based
on the methodology of White et al. (1958) and Eriksson (1971). It applies Gibbs
free-energy minimization using an iterative, Lagrangian optimization scheme.
Given elemental abundances, TEA calculates molecular abundances for a
particular temperature and pressure or a list of temperature-pressure pairs. We
tested the code against the method of Burrows & Sharp (1999), the free
thermochemical equilibrium code CEA (Chemical Equilibrium with Applications),
and the example given by White et al. (1958). Using their thermodynamic data,
TEA reproduces their final abundances, but with higher precision. We also
applied the TEA abundance calculations to models of several hot-Jupiter
exoplanets, producing expected results. TEA is written in Python in a modular
format. There is a start guide, a user manual, and a code document in addition
to this theory paper. TEA is available under a reproducible-research,
open-source license via https://github.com/dzesmin/TEA.Comment: 14 pages, 8 figures, article is submitted to ApJS, posted on arXiv
for public commentary, please send comments to the lead autho
Free-field propagation of high intensity noise
Observed spectral data from supersonic jet aircraft are known to contain much more high frequency energy than can be explained by linear acoustic propagation theory. It is believed that the high frequency energy is an effect of nonlinear distortion due to the extremely high acoustic levels generated by the jet engines. The objective, to measure acoustic waveform distortion for spherically diverging high intensity noise, was reached by using an electropneumatic acoustic source capable of generating sound pressure levels in the range of 140 to 160 decibels (re 20 micro Pa). The noise spectrum was shaped to represent the spectra generated by jet engines. Two microphones were used to capture the acoustic pressure waveform at different points along the propagation path in order to provide a direct measure of the waveform distortion as well as spectral distortion. A secondary objective was to determine that the observed distortion is an acoustic effect. To do this an existing computer prediction code that deals with nonlinear acoustic propagation was used on data representative of the measured data. The results clearly demonstrate that high intensity jet noise does shift the energy in the spectrum to the higher frequencies along the propagation path. In addition, the data from the computer model are in good agreement with the measurements, thus demonstrating that the waveform distortion can be accounted for with nonlinear acoustic theory
Abelian Z-theory: NLSM amplitudes and alpha'-corrections from the open string
In this paper we derive the tree-level S-matrix of the effective theory of
Goldstone bosons known as the non-linear sigma model (NLSM) from string theory.
This novel connection relies on a recent realization of tree-level
open-superstring S-matrix predictions as a double copy of super-Yang-Mills
theory with Z-theory --- the collection of putative scalar effective field
theories encoding all the alpha'-dependence of the open superstring. Here we
identify the color-ordered amplitudes of the NLSM as the low-energy limit of
abelian Z-theory. This realization also provides natural higher-derivative
corrections to the NLSM amplitudes arising from higher powers of alpha' in the
abelian Z-theory amplitudes, and through double copy also to Born-Infeld and
Volkov-Akulov theories. The Kleiss-Kuijf and Bern-Carrasco-Johansson relations
obeyed by Z-theory amplitudes thereby apply to all alpha'-corrections of the
NLSM. As such we naturally obtain a cubic-graph parameterization for the
abelian Z-theory predictions whose kinematic numerators obey the duality
between color and kinematics to all orders in alpha'.Comment: 37 pages; v2: references, explanations and arguments for
factorization added; published versio
The BURCHAK corpus: a Challenge Data Set for Interactive Learning of Visually Grounded Word Meanings
We motivate and describe a new freely available human-human dialogue dataset
for interactive learning of visually grounded word meanings through ostensive
definition by a tutor to a learner. The data has been collected using a novel,
character-by-character variant of the DiET chat tool (Healey et al., 2003;
Mills and Healey, submitted) with a novel task, where a Learner needs to learn
invented visual attribute words (such as " burchak " for square) from a tutor.
As such, the text-based interactions closely resemble face-to-face conversation
and thus contain many of the linguistic phenomena encountered in natural,
spontaneous dialogue. These include self-and other-correction, mid-sentence
continuations, interruptions, overlaps, fillers, and hedges. We also present a
generic n-gram framework for building user (i.e. tutor) simulations from this
type of incremental data, which is freely available to researchers. We show
that the simulations produce outputs that are similar to the original data
(e.g. 78% turn match similarity). Finally, we train and evaluate a
Reinforcement Learning dialogue control agent for learning visually grounded
word meanings, trained from the BURCHAK corpus. The learned policy shows
comparable performance to a rule-based system built previously.Comment: 10 pages, THE 6TH WORKSHOP ON VISION AND LANGUAGE (VL'17
Pairs of geometric foliations of regular and singular surfaces
We examine some generic features of surfaces in the Euclidean 3-space related to the Gauss map on the surface. We consider these features on smooth surfaces and on singular surfaces with a cross-cap singularity.
We study some symmetries between two classical pairs of foliations defined on smooth surfaces in : the asymptotic curves and the characteristic curves (called harmonic mean curvature lines in \cite{garciasotomayorharmonic}). The asymptotic curves exist in hyperbolic regions of surfaces and have been well studied. The characteristic curves are in certain ways the analogy of the asymptotic curves in elliptic regions. In this thesis we extend this analogy.
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We produce results on the characteristic curves mirroring those of Uribe-Vargas (\cite{uribevargas}) on the asymptotic curves. By considering cross-ratios of Legendrian lines in the manifold of contact elements to the surface we show that certain properties of the characteristic curves are invariant under projective transformations, and examine their behaviour at cusps of Gauss.
We establish an analogy of the Beltrami-Enepper Theorem, which allows us to distinguish between the two characteristic foliations in a natural geometric way. We show that the local properties of characteristic curves may be used to prove certain global results concerning the elliptic regions of smooth surfaces.
Motivated by the study of the asymptotic, principal and characteristic curves on surfaces in , we construct a natural one-to-one correspondence between the set of non-degenerate binary differential equations (BDEs) and linear involutions on the real projective line. We show that one may construct pairs of BDEs that have various symmetric properties using a single involution on . We study the folded singularities of BDEs, and associate an affine invariant to such points. We show that one may associate a complex parameter to folded singularities that determines the relative positions of various curves of interest.
We show that the BDEs asymptotic, characteristic, and principal curves are related to other quadratic forms on surfaces. These include the BDE that defines the lines of arithmetic mean curvature which are studied in \cite{garciasotomayorarith}, and the third fundamental form of the surface. We define a new pair of foliations of a surface which we label the minimal orthogonal spherical image (MOSI) curves which are the integral curves of those tangent directions to a surface that have orthogonal images under the Gauss map, and are inclined at an extremal angle. We establish the configurations of the MOSI curves in a neighbourhood of umbilic points, parabolic points and cusps of Gauss.
We construct natural 1-parameter families of BDEs that interpolate between the BDEs we have studied, and establish relationships between these families.
We exhibit the existence of a curve of points of zero torsion of the characteristic curves, and a curve of points where the tangent plane to the surface is the osculating plane of a characteristic curve. We determine the behaviour of these curves near cusps of Gauss and umbilic points.
We study BDEs with coefficients that vanish simultaneously at an isolated point and with discriminant having an -singularity at that point. We show that such BDEs can be grouped into three distinct types, and study the differences between these types in terms of their codimension and the linear parts of their coefficients. We establish the topological configurations of the solution curves in each case with codimension .
We study the asymptotic and characteristic curves in the neighbourhood of a parabolic cross-cap, that is, on a singular surface with a cross-cap singularity with a parabolic set having a cusp singularity at the singular point. We obtain the topological configurations of these foliations both in the domain of a parametrisation of such a surface, and on the surface itself. We construct a natural one-parameter family of surfaces with cross-cap singularities in which the parabolic cross-cap is the transition from a hyperbolic cross-cap to an elliptic cross-cap. We study the bifurcations of the asymptotic and characteristic curves in this family
Diffractive lens fabricated with binary features less than 60 nm
We designed, fabricated, and characterized a binary diffractive lens with features less than 60nm. The lens was designed for operation in the red portion of the spectrum. Experimental measurements of lens performance agree with predictions generated by rigorous models of diffraction
CoopeTárcoles, Costa Rica. Equator Initiative Case Study Series
The artisanal fishers of the community of Tárcoles, located in the Gulf of Nicoya on the Pacific coast of North America (Central America)-Costa Rica; faced declining fish stocks due to a combination of overharvesting by commercial shrimp boats and unsustainable local fishing practices. At the same time, development of the tourism sector along the coast threatened to restrict access to the shore and to marginalize their work. The local fishing cooperative Coope Tárcoles R.L. was founded in 1985 to confront these twin threats. At the forefront of these efforts has been the development of fishing bylaws that stress sustainable practices, enshrined in the community's 'Code of Responsible Fishing'. In partnership with CoopeSolidar R.L., the initiative launched a sustainable and community-based ecotourism venture in 2007 to provide an alternative source of income for local residents. In 2009, meanwhile, the group was successful in gaining approval of a community-managed marine area
Hearing voices, dissociation and the self: a functional-analytic perspective
Item does not contain fulltextIn the current paper, we review existing models of the aetiology of voice hearing. We summarise the argument and evidence that voice hearing is primarily a dissociative process, involving critical aspects of self. We propose a complementary perspective on these phenomena that is based on a modern behavioural account of complex behaviour, known as Relational Frame Theory (RFT). This type of approach to voice hearing concerns itself with: the functions served for the individual by this voice hearing; the necessary history, such as trauma, that establishes these functions; and the relevant dissociative processes involving self and others. In short, we propose a trauma-dissociation developmental trajectory in which trauma impacts negatively on the development of self, through the process of dissociation. Using the RFT concept of relations of perspective-taking, our dissociation model purports that trauma gives rise to more co-ordination than distinction relations between self and others, thus weaking an individual's sense of a distinct self. Voice hearing experiences, therefore, reflect an individual's perceptions of self and others, and may indicate impairments in the natural psychological boundaries between these critical related concepts. One clinical implication suggested by this model is that therapeutic 'intervention' should understand the behaviours associated with a sense of self that is fragile and threatened by others. Relations with self and others should be a key focus of therapy, as well as interventions designed to enhance a coherent distinct sense of self.20 p
Alien Registration- Poulin, Joseph Oliver R. (Lewiston, Androscoggin County)
https://digitalmaine.com/alien_docs/27958/thumbnail.jp
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