6,790 research outputs found
Successful prediction of horse racing results using a neural network
Most application work within neural computing continues to employ multi-layer perceptrons (MLP). Though many variations of the fully interconnected feed-forward MLP, and even more variations of the back propagation learning rule, exist; the first section of the paper attempts to highlight several properties of these standard networks. The second section outlines an application-namely the prediction of horse racing result
Feeling Beyond Words: Ineffability and Haptic Translational Praxis of Black German Writings
In this article, I focus on selections from Black German essayistic and creative writings that center experiential knowledge that is personal and often multisensory. My case studies are excerpts from Farbe bekennen: Afro-deutsche Frauen auf den Spuren ihrer Geschichte (1986), its English translation by Anne V. Adams (Showing Our Colors 1992), and Natasha Kelly’s collection of interviews from her documentary film, Millis Erwachen (Milli’s Awakening) (2018), which Kelly herself translated. These texts, I argue, explore the ways in which words fail to fully express the visceral reaction of living while Black in Germany, particularly those that seek to make connections across geographic, linguistic, and generational differences. Focusing on the concept of transvivência (Araújo, Silva, and Silva-Reis) and hapticity of Black life (Tina Campt), I propose a model of translation that acknowledges the limitations of spoken and written words to convey all meaning and yet suggest that awareness through annotation, page format, and explanation might gesture toward more nuanced cultural references and ineffable experiences. Translation of Black-authored works into another language suggests a two-fold translation, from experience into language, from one language into another. I argue that hapticity combined with translation as transvivência has the ability to bridge what is felt and experienced with that which is read and observed. I conclude with a discussion of my own experience of translating Sharon Dodoa Otoo’s essay “Liebe” ‘Love’ from Eure Heimat ist unser Albtraum (Your Homeland is Our Nightmare)
Immigration Dialogue: The Immigrant in Our Midst
As the world experiences global human migration on an unprecedented scale, rich nations struggle to curtail the incoming flood of immigrants, while poor nations suffer population loss. Migration and immigration are not new concepts, what is new are the conditions under which much of this movement occurs and how the world responds.
The Society of Jesus\u27 response has been to name migration as one of its five top international priorities. In June of 2005 three faculty members from John Carroll met with representatives from over twenty national and international Jesuit Universities and social service organizations on the campus of Fairfield University to ask how Jesuit institutions might address this emerging crisis. The program, Migration Studies and Jesuit Identity: Forging a Path Forward, developed by Fairfield faculty and jointly sponsored hy The Association of American Jesuit Colleges and Universities, the Social and International Ministries Office of the United States Jesuit Conference, and Jesuit Refugee Services had the following goals:
To establish collaborative relationships in migration studies, research, and advocacy.
To consider academic research, traditional interdisciplinary course instruction, and experiential educational approaches such as service learning.
To consider an advocacy role in helping to alleviate current injustices experienced by migrants
AOIPS water resources data management system
A geocoded data management system applicable for hydrological applications was designed to demonstrate the utility of the Atmospheric and Oceanographic Information Processing System (AOIPS) for hydrological applications. Within that context, the geocoded hydrology data management system was designed to take advantage of the interactive capability of the AOIPS hardware. Portions of the Water Resource Data Management System which best demonstrate the interactive nature of the hydrology data management system were implemented on the AOIPS. A hydrological case study was prepared using all data supplied for the Bear River watershed located in northwest Utah, southeast Idaho, and western Wyoming
Spin Evolution of Supermassive Black Holes and Galactic Nuclei
The spin angular momentum S of a supermassive black hole (SBH) precesses due
to torques from orbiting stars, and the stellar orbits precess due to dragging
of inertial frames by the spinning hole. We solve the coupled post-Newtonian
equations describing the joint evolution of S and the stellar angular momenta
Lj, j = 1...N in spherical, rotating nuclear star clusters. In the absence of
gravitational interactions between the stars, two evolutionary modes are found:
(1) nearly uniform precession of S about the total angular momentum vector of
the system; (2) damped precession, leading, in less than one precessional
period, to alignment of S with the angular momentum of the rotating cluster.
Beyond a certain distance from the SBH, the time scale for angular momentum
changes due to gravitational encounters between the stars is shorter than
spin-orbit precession times. We present a model, based on the
Ornstein-Uhlenbeck equation, for the stochastic evolution of star clusters due
to gravitational encounters and use it to evaluate the evolution of S in nuclei
where changes in the Lj are due to frame dragging close to the SBH and to
encounters farther out. Long-term evolution in this case is well described as
uniform precession of the SBH about the cluster's rotational axis, with an
increasingly important stochastic contribution when SBH masses are small. Spin
precessional periods are predicted to be strongly dependent on nuclear
properties, but typical values are 10-100 Myr for low-mass SBHs in dense
nuclei, 100 Myr - 10 Gyr for intermediate mass SBHs, and > 10 Gyr for the most
massive SBHs. We compare the evolution of SBH spins in stellar nuclei to the
case of torquing by an inclined, gaseous accretion disk.Comment: 25 page
Is there a Supermassive Black Hole at the Center of the Milky Way?
This review outlines the observations that now provide an overwhelming
scientific case that the center of our Milky Way Galaxy harbors a supermassive
black hole. Observations at infrared wavelength trace stars that orbit about a
common focal position and require a central mass (M) of 4 million solar masses
within a radius of 100 Astronomical Units. Orbital speeds have been observed to
exceed 5,000 km/s. At the focal position there is an extremely compact radio
source (Sgr A*), whose apparent size is near the Schwarzschild radius
(2GM/c^2). This radio source is motionless at the ~1 km/s level at the
dynamical center of the Galaxy. The mass density required by these observations
is now approaching the ultimate limit of a supermassive black hole within the
last stable orbit for matter near the event horizon.Comment: Invited review submitted to International Journal of Modern Physics
D; 23 pages; 10 figure
Chaotic mixing in noisy Hamiltonian systems
This paper summarises an investigation of the effects of low amplitude noise
and periodic driving on phase space transport in 3-D Hamiltonian systems, a
problem directly applicable to systems like galaxies, where such perturbations
reflect internal irregularities and.or a surrounding environment. A new
diagnsotic tool is exploited to quantify how, over long times, different
segments of the same chaotic orbit can exhibit very different amounts of chaos.
First passage time experiments are used to study how small perturbations of an
individual orbit can dramatically accelerate phase space transport, allowing
`sticky' chaotic orbits trapped near regular islands to become unstuck on
suprisingly short time scales. Small perturbations are also studied in the
context of orbit ensembles with the aim of understanding how such
irregularities can increase the efficacy of chaotic mixing. For both noise and
periodic driving, the effect of the perturbation scales roughly in amplitude.
For white noise, the details are unimportant: additive and multiplicative noise
tend to have similar effects and the presence or absence of a friction related
to the noise by a Fluctuation- Dissipation Theorem is largely irrelevant.
Allowing for coloured noise can significantly decrease the efficacy of the
perturbation, but only when the autocorrelation time, which vanishes for white
noise, becomes so large that t here is little power at frequencies comparable
to the natural frequencies of the unperturbed orbit. This suggests strongly
that noise-induced extrinsic diffusion, like modulational diffusion associated
with periodic driving, is a resonance phenomenon. Potential implications for
galaxies are discussed.Comment: 15 pages including 18 figures, uses MNRAS LaTeX macro
High inclination orbits in the secular quadrupolar three-body problem
The Lidov-Kozai mechanism allows a body to periodically exchange its
eccentricity with inclination. It was first discussed in the framework of the
quadrupolar secular restricted three-body problem, where the massless particle
is the inner body, and later extended to the quadrupolar secular nonrestricted
three body problem. In this paper, we propose a different point of view on the
problem by looking first at the restricted problem where the massless particle
is the outer body. In this situation, equilibria at high mutual inclination
appear, which correspond to the population of stable particles that Verrier &
Evans (2008,2009) find in stable, high inclination circumbinary orbits around
one of the components of the quadruple star HD 98800. We provide a simple
analytical framework using a vectorial formalism for these situations. We also
look at the evolution of these high inclination equilibria in the non
restricted case.Comment: 11 pages, 6 figures. Accepted by MNRAS 2009 September 1
Long Term Evolution of Massive Black Hole Binaries
The long-term evolution of massive black hole binaries at the centers of
galaxies is studied in a variety of physical regimes, with the aim of resolving
the ``final parsec problem,'' i.e., how black hole binaries manage to shrink to
separations at which emission of gravity waves becomes efficient. A binary
ejects stars by the gravitational slingshot and carves out a loss cone in the
host galaxy. Continued decay of the binary requires a refilling of the loss
cone. We show that the standard treatment of loss cone refilling, derived for
collisionally relaxed systems like globular clusters, can substantially
underestimate the refilling rates in galactic nuclei. We derive expressions for
non-equilibrium loss-cone dynamics and calculate time scales for the decay of
massive black hole binaries following galaxy mergers, obtaining significantly
higher decay rates than heretofore. Even in the absence of two-body relaxation,
decay of binaries can persist due to repeated ejection of stars returning to
the nucleus on eccentric orbits. We show that this recycling of stars leads to
a gradual, approximately logarithmic dependence of the binary binding energy on
time. We derive an expression for the loss cone refilling induced by the
Brownian motion of a black hole binary. We also show that numerical N-body
experiments are not well suited to probe these mechanisms over long times due
to spurious relaxation.Comment: Replaced to match the accepted version, ApJ, 596 (2003
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