5,982 research outputs found
Relationship between fork and intestine length in Atlantic bluefin tuna (Thunnus thynnus).
Los datos de longitud a horquilla facilitan información necesaria para las estadísticas de
captura, biología de las pesquerías y estudios de población. Sin embargo, en el muestreo de
atún rojo no siempre es posible recopilar mediciones de los ejemplares, y los investigadores
tienen que recurrir a relaciones biométricas. Mediante una función lineal, se estimó la longitud
a horquilla recta (SFL) a partir de la longitud del intestino y se halló una fuerte relación entre
estas variables (SFL = 1,58, L de intestino -1,98, r2 = 0,96). Esta función lineal puede
utilizarse en futuras estimaciones SFL. Además, lainversa de la inclinación de esta ecuación
representa el índice Nikolsky (Ii), que proporciona información sobre hábitos alimentarios y
clasifica los peces como carnívoros, omnívoros u herbívoros. Se obtuvo un valor de índice
Nikolsky de 0,64, que indica que el atún rojo del Atlántico es un pez carnívoro. Esta
observación coincide con estudios anteriores.Versión de editor
Casimir micro-sphere diclusters and three-body effects in fluids
Our previous article [Phys. Rev. Lett. 104, 060401 (2010)] predicted that
Casimir forces induced by the material-dispersion properties of certain
dielectrics can give rise to stable configurations of objects. This phenomenon
was illustrated via a dicluster configuration of non-touching objects
consisting of two spheres immersed in a fluid and suspended against gravity
above a plate. Here, we examine these predictions from the perspective of a
practical experiment and consider the influence of non-additive, three-body,
and nonzero-temperature effects on the stability of the two spheres. We
conclude that the presence of Brownian motion reduces the set of experimentally
realizable silicon/teflon spherical diclusters to those consisting of layered
micro-spheres, such as the hollow- core (spherical shells) considered here.Comment: 11 pages, 9 figure
LAPW frozen-phonon calculation, shell model lattice dynamics and specific-heat measurement of SnO
An ab-initio Linear Augmented Plane-Wave (LAPW) calculation of the
zone-centered phonon frequencies of SnO has been performed. E symmetry has
been ascribed to the mode observed at 113 cm in Raman measurements,
discarding a previous B assignement. The other phonon modes measured by
Raman spectroscopy are also well reproduced. A new shell-model has also been
developed, that gives good agreement of the zone-centered frequencies compared
to the measured data and the LAPW results. Specific heat measurements have been
performed between 5 K and 110 K. Computation of the specific heat and the
M\"{o}ssbauer recoilless fraction with the improved shell-model shows a good
agreement with the experimental data as a function of temperature.Comment: 11 pages, 1 figure. to appear in Phys. Rev. B (November 1999
Corrosion resistance of anodic layers grown on 304L stainless steel at different anodizing times and stirring speeds
Different chemical and physical treatments have been used to improve the properties and functionalities of steels. Anodizing is one of the most promising treatments, due to its versatility and easy industrial implementation. It allows the growth of nanoestructured oxide films with interesting properties able to be employed in different industrial sectors. The present work studies the influence of the anodizing time (15, 30, 45 and 60 min), as well as the stirring speed (0, 200, 400, and 600 rpm), on the morphology and the corrosion resistance of the anodic layers grown in 304L stainless steel. The anodic layers were characterized morphologically, compositionally, and electrochemically, in order to determine the influence of the anodization parameters on their corrosion behavior in a 0.6 mol L-1 NaCl solution. The results show that at 45 and 60 min anodizing times, the formation of two microstructures is favored, associated with the collapse of the nanoporous structures at the metal-oxide interphace. However, both the stirring speed and the anodizing time have a negligeable effect on the corrosion behavior of the anodized 304L SS samples, since their electrochemical values are similar to those of the non-anodized ones
Bright Stars and Recent Star Formation in the Irregular Magellanic Galaxy NGC2366
The stellar content of the Im galaxy NGC 2366 is discussed on the basis of
CCD BVR photometry. The three brightest blue and red stars have been used to
estimate its distance, obtaining a balue of 2.9 Mpc. The spatial distribution
of the young stellar population is discussed in the light of the integrated
color indices and the color-magnitude diagrams of different zones of the
galaxy. A generalized star formation burst seems to have taken place about 50
Myr ago. The youngest stars are preferentially formed in the South-West part of
the bar, where the giant HII complex NGC 2363 is located, being younger and
bluer. The bar seems to play a role favouring star formation in one of its
extremes. Self-propagation however, does not seem to be triggering star
formation at large scale. A small region, populated by very young stars has
also been found at the East of the galaxy.Comment: Astronomical Journal, accepted. This is a uuencoded, compressed, tar
file (102 Kbytes) of 1 text, 1 table postscript files. Figures are retrieved
as a separate file. One single file with all figures and tables (552Kb) also
available from http://www.ast.cam.ac.uk/~etelles/astronomy.htm
Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter
An in-situ calibration of a logarithmic periodic dipole antenna with a
frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of
a radio station system used for detection of cosmic ray induced air showers at
the Engineering Radio Array of the Pierre Auger Observatory, the so-called
Auger Engineering Radio Array (AERA). The directional and frequency
characteristics of the broadband antenna are investigated using a remotely
piloted aircraft (RPA) carrying a small transmitting antenna. The antenna
sensitivity is described by the vector effective length relating the measured
voltage with the electric-field components perpendicular to the incoming signal
direction. The horizontal and meridional components are determined with an
overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} %
respectively. The measurement is used to correct a simulated response of the
frequency and directional response of the antenna. In addition, the influence
of the ground conductivity and permittivity on the antenna response is
simulated. Both have a negligible influence given the ground conditions
measured at the detector site. The overall uncertainties of the vector
effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in
the square root of the energy fluence for incoming signal directions with
zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is
unchanged with respect to v2. 39 pages, 15 figures, 2 table
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
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