3,057 research outputs found
Contribución al conocimiento de los malófagos (Phthiraptera, Amblycera, Ischnocera) de aves peruanas. Parte 1
Nine species of Mallophaga from Peruvian birds are reported in this work. Two Mallophaga Amblycera: Heteromenopon laticapitis y Menacanthus pici, as well as seven Mallophaga Ischnocera: Alcedoffula theresae, Brueelia brunneinucha, Chelopistes meleagridis, Columbicola columbae, Paragoniocotes aratingae, Penenirmus jungens y Saemundssonia (Saemundssonia) lari, were identified morphologically. A brief description of each chewing lice and discussion about their hosts and distribution is done.En el presente trabajo se reporta nueve especies de malófagos colectados de aves peruanas. Dos malófagos Amblycera: Heteromenopon laticapitis y Menacanthus pici, así como siete malófagos Ischnocera: Alcedoffula theresae, Brueelia brunneinucha, Chelopistes meleagridis, Columbicola columbae, Paragoniocotes aratingae, Penenirmus jungens y Saemundssonia (Saemundssonia) lari, fueron determinados mediante el diagnóstico morfológico. Se realiza una breve descripción de cada malófago, así como la discusión de sus hospederos y distribución
A Cluster of Compact Radio Sources in NGC 2024 (Orion B)
We present deep 3.6 cm radio continuum observations of the H II region NGC
2024 in Orion B obtained using the Very Large Array in its A-configuration,
with angular resolution. We detect a total of 25 compact radio
sources in a region of . We discuss the nature of these sources
and its relation with the infrared and X-ray objects in the region. At least
two of the radio sources are obscured proplyds whose morphology can be used to
restrict the location of the main ionizing source of the region. This cluster
of radio sources is compared with others that have been found in regions of
recent star formation.Comment: 21 pages, 7 figure
Primer registro de Serratospiculum tendo (Nematoda: Diplotriaenidae) para el Perú
We report for first time the presence of nematode, Serratospiculum tendo Nitzsch, 1819, parasitizing air sacs of a Peregrine Falcon (Falco peregrinus Tunstall, 1771). Six nematodes (2 males and 4 females) were collected and identified as S. tendo. The discovery of this nematode is the first record in Peru.Reportamos por primera vez la presencia del nematodo, Serratospiculum tendo Nitzsch, 1819, parasitando los sacos aéreos de un halcón peregrino (Falco peregrinus Tunstall, 1771). Seis nematodos (2 machos y 4 hembras) fueron colectados e identificados como S. tendo. El hallazgo de este nematodo constituye el primer registro en el Perú
Real-time camera motion tracking in planar view scenarios
We propose a novel method for real-time camera motion tracking in planar view scenarios. This method relies on the geometry of a tripod, an initial estimation of camera pose for the first video frame and a primitive tracking procedure. This process uses lines and circles as primitives, which are extracted applying classification and regression tree. We have applied the proposed method to high-definition videos of soccer matches. Experimental results prove that our proposal can be applied to processing high-definition video in real time. We validate the procedure by inserting virtual content in the video sequence
Linear Collider Test of a Neutrinoless Double Beta Decay Mechanism in left-right Symmetric Theories
There are various diagrams leading to neutrinoless double beta decay in
left-right symmetric theories based on the gauge group SU(2)_L x SU(2)_R. All
can in principle be tested at a linear collider running in electron-electron
mode. We argue that the so-called lambda-diagram is the most promising one.
Taking the current limit on this diagram from double beta decay experiments, we
evaluate the relevant cross section e e to W_L W_R, where W_L is the Standard
Model W-boson and W_R the one from SU(2)_R. It is observable if the life-time
of double beta decay and the mass of the W_R are close to current limits. Beam
polarization effects and the high-energy behaviour of the cross section are
also analyzed.Comment: 17 pages, 6 figures. v2: minor changes, references added, to be
published in EPJ
Grazing Collisions of Black Holes via the Excision of Singularities
We present the first simulations of non-headon (grazing) collisions of binary
black holes in which the black hole singularities have been excised from the
computational domain. Initially two equal mass black holes are separated a
distance and with impact parameter . Initial data are
based on superposed, boosted (velocity ) solutions of single black
holes in Kerr-Schild coordinates. Both rotating and non-rotating black holes
are considered. The excised regions containing the singularities are specified
by following the dynamics of apparent horizons. Evolutions of up to are obtained in which two initially separate apparent horizons are present
for . At that time a single enveloping apparent horizon forms,
indicating that the holes have merged. Apparent horizon area estimates suggest
gravitational radiation of about 2.6% of the total mass. The evolutions end
after a moderate amount of time because of instabilities.Comment: 2 References corrected, reference to figure update
Highlights from the Pierre Auger Observatory
The Pierre Auger Observatory is the world's largest cosmic ray observatory.
Our current exposure reaches nearly 40,000 km str and provides us with an
unprecedented quality data set. The performance and stability of the detectors
and their enhancements are described. Data analyses have led to a number of
major breakthroughs. Among these we discuss the energy spectrum and the
searches for large-scale anisotropies. We present analyses of our X
data and show how it can be interpreted in terms of mass composition. We also
describe some new analyses that extract mass sensitive parameters from the 100%
duty cycle SD data. A coherent interpretation of all these recent results opens
new directions. The consequences regarding the cosmic ray composition and the
properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray
Conference, Rio de Janeiro 201
Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory
The Pierre Auger Collaboration has reported evidence for anisotropy in the
distribution of arrival directions of the cosmic rays with energies
eV. These show a correlation with the distribution
of nearby extragalactic objects, including an apparent excess around the
direction of Centaurus A. If the particles responsible for these excesses at
are heavy nuclei with charge , the proton component of the
sources should lead to excesses in the same regions at energies . We here
report the lack of anisotropies in these directions at energies above
(for illustrative values of ). If the anisotropies
above are due to nuclei with charge , and under reasonable
assumptions about the acceleration process, these observations imply stringent
constraints on the allowed proton fraction at the lower energies
Numerical Relativity: A review
Computer simulations are enabling researchers to investigate systems which
are extremely difficult to handle analytically. In the particular case of
General Relativity, numerical models have proved extremely valuable for
investigations of strong field scenarios and been crucial to reveal unexpected
phenomena. Considerable efforts are being spent to simulate astrophysically
relevant simulations, understand different aspects of the theory and even
provide insights in the search for a quantum theory of gravity. In the present
article I review the present status of the field of Numerical Relativity,
describe the techniques most commonly used and discuss open problems and (some)
future prospects.Comment: 2 References added; 1 corrected. 67 pages. To appear in Classical and
Quantum Gravity. (uses iopart.cls
A search for point sources of EeV photons
Measurements of air showers made using the hybrid technique developed with
the fluorescence and surface detectors of the Pierre Auger Observatory allow a
sensitive search for point sources of EeV photons anywhere in the exposed sky.
A multivariate analysis reduces the background of hadronic cosmic rays. The
search is sensitive to a declination band from -85{\deg} to +20{\deg}, in an
energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been
detected. An upper limit on the photon flux has been derived for every
direction. The mean value of the energy flux limit that results from this,
assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial
direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in
which EeV cosmic ray protons are emitted by non-transient sources in the
Galaxy.Comment: 28 pages, 10 figures, accepted for publication in The Astrophysical
Journa
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