620 research outputs found
Entropy Spectrum of a Carged Black Hole of Heterotic String Theory via Adiabatic Invariance
Using adiabatic invariance and the Bohr-Sommerfeld quantization rule we
investigate the entropy spectroscopy of a charged black hole of heterotic
string theory. It is shown that the entropy spectrum is equally spaced
identically to the Schwarzschild, Reissner-Nordstr\"om and Kerr black holes.
Since the adiabatic invariance method does not use quasinormal mode analysis,
there is no need to impose the small charge limit and no confusion on whether
the real part or imaginary part is responsible for the entropy spectrum.Comment: 8 pages, no figure
Believing in the Gift: a Case of Successful Relationships of Exchange in the Colombian Amazon
Since the late 70’s, the Colombian anthropologist Juan Alvaro Echeverri has logged more than five years in Uitoto and closely related communities in the Colombian Amazon. His relationships with individuals there have been long-lived and surprisingly successful, in contrast with the often-noted disappointment of many philanthropically oriented outsiders—NGO agents, anthropologists, missionaries, government personnel—who come to find ‘their Indians’ to be too materialistic and demanding, and of the Indians who cease to find these would-be philanthropists generous, desirable, or even interesting interlocutors. This essay, meant to be both an ethnographic and theoretical exposition on the forms and implications of substance exchange and an entertaining manifesto of admiration for an exemplary Amazonianist scholar, proves that the parties involved have achieved, and continue to achieve, practical, satisfying, and sustainable relationships, mostly through material gifts that index their mutual recognition as moral interlocutors
Circulating Glycated Albumin and Glomerular Anionic Charges
Aiming to discern the mechanisms by which circulating
glycated albumin alters the glomerular filtration properties
that lead to glomerular dysfunction in diabetes, the authors
studied the distribution and densities of anionic charges
through the rat glomerular wall upon intravascular infusion
of Amadori products, as well as in various conditions of
increased glomerular permselectivity. Polylysine-gold was
used as the probe to reveal the anionic charges. The study
was carried on renal tissue sections of bovine serum albumin
(BSA)- and glycated BSA–injected, normoglycemic
animals. Results were generated through morphometrical
evaluations of the gold labeling. Changes in glomerular anionic
distribution were corroborated on renal tissue sections
of short- and long-term diabetic rats and of normal newborn
rats, situations known for abnormal glomerular filtration.
Altered renal function in these conditions was clearly
associated with changes in glomerular anionic charges. On
the other hand, the infusion of glycated albumin in the circulation
of normal rats, though altering glomerular filtration
properties, did not modify the distribution and density of
the polylysine-gold labeling through the glomerular basement
membrane. Thus, anionic charges seem not to be the
factor involved in the early changes of glomerular permeability
induced by circulating glycated albumin
An Instance Selection Algorithm for Big Data in High imbalanced datasets based on LSH
Training of Machine Learning (ML) models in real contexts often deals with
big data sets and high-class imbalance samples where the class of interest is
unrepresented (minority class). Practical solutions using classical ML models
address the problem of large data sets using parallel/distributed
implementations of training algorithms, approximate model-based solutions, or
applying instance selection (IS) algorithms to eliminate redundant information.
However, the combined problem of big and high imbalanced datasets has been less
addressed. This work proposes three new methods for IS to be able to deal with
large and imbalanced data sets. The proposed methods use Locality Sensitive
Hashing (LSH) as a base clustering technique, and then three different sampling
methods are applied on top of the clusters (or buckets) generated by LSH. The
algorithms were developed in the Apache Spark framework, guaranteeing their
scalability. The experiments carried out in three different datasets suggest
that the proposed IS methods can improve the performance of a base ML model
between 5% and 19% in terms of the geometric mean.Comment: 23 pages, 15 figure
Uso compartido de una letrina por el zorro Cerdocyon thous y perros domésticos Canis familiaris (Carnivora: Canidae) en una zona periurbana del Valle de Aburrá (Antioquia, Colombia)
Many species of carnivores make latrines by accumulating their feces at specific sites. These serve to mark their territory and warn other individuals about their presence, as a strategy to avoid direct competition for the area and its resources. The study of latrines can provide relevant information on habitat use, ecological behavior of species and their dietMuchas especies de carnívoros conforman letrinas al acumular sus heces en sitios específicos. Estas sirven para marcar su territorio y advertir a otros individuos sobre su presencia, como una estrategia para evitar competencia directa por el área y sus recursos . El estudio de las letrinas puede aportar información relevante sobre el uso del hábitat, el comportamiento ecológico de las especies y sobre su diet
La circuncisión femenina, la antropología y el liberalismo
A new comer to the anthropology of African peoples and to the study of female genital cutting, the author reacts to the speeches and writings of American and Sierra Leonean scholar Fuambai Ahmadu on these matters. Inspired by her work, the author argues that many of the perceptions and much of the rhetoric of anti FGM (anti Female Genital Mutilation) movements are parochial, imperialistic, and illiberal, and suggests that anthropologists and others take counsel from anthropology’s age-old methodological prescription to attend carefully and over an extended period of time to the discourses and other practices of the people we study and to be reflexively critical about our own premises and beliefs, prior to adopting any purportedly liberal cause that seeks to eradicate any alien social practice.Este ensayo es una respuesta positiva del autor, un antropólogo con experiencia en otros temas, a una ponencia y varios escritos de la antropóloga sierraleonesa y estadinense del Dr. Fuambai Ahmadu sobre el tema de la circuncisión femenina en África. Persuadido por los argumentos de Ahmadu, el autor arguye que parte de las percepciones y de la retórica de los movimientos anti MGF (anti mutilación genital femenina) son parroquiales y no liberales y hace un llamado para que antropólogos, y otros, acepten la prescripción metodológica de nuestra disciplina de prestar atención cuidadosa y a lo largo de un buen período de tiempo, a lo que la gente sobre quien escribimos dice y hace. Además, de ser críticos con nuestras propias premisas y creencias, antes de adoptar cualquier causa supuestamente liberal que busque erradicar o establecer esta o aquella práctica social
Femtosecond pulses and dynamics of molecular photoexcitation: RbCs example
We investigate the dynamics of molecular photoexcitation by unchirped
femtosecond laser pulses using RbCs as a model system. This study is motivated
by a goal of optimizing a two-color scheme of transferring
vibrationally-excited ultracold molecules to their absolute ground state. In
this scheme the molecules are initially produced by photoassociation or
magnetoassociation in bound vibrational levels close to the first dissociation
threshold. We analyze here the first step of the two-color path as a function
of pulse intensity from the low-field to the high-field regime. We use two
different approaches, a global one, the 'Wavepacket' method, and a restricted
one, the 'Level by Level' method where the number of vibrational levels is
limited to a small subset. The comparison between the results of the two
approaches allows one to gain qualitative insights into the complex dynamics of
the high-field regime. In particular, we emphasize the non-trivial and
important role of far-from-resonance levels which are adiabatically excited
through 'vertical' transitions with a large Franck-Condon factor. We also point
out spectacular excitation blockade due to the presence of a quasi-degenerate
level in the lower electronic state. We conclude that selective transfer with
femtosecond pulses is possible in the low-field regime only. Finally, we extend
our single-pulse analysis and examine population transfer induced by coherent
trains of low-intensity femtosecond pulses.Comment: 25 pages, 12 figure
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