7,403 research outputs found
Probabilistic Inference from Arbitrary Uncertainty using Mixtures of Factorized Generalized Gaussians
This paper presents a general and efficient framework for probabilistic
inference and learning from arbitrary uncertain information. It exploits the
calculation properties of finite mixture models, conjugate families and
factorization. Both the joint probability density of the variables and the
likelihood function of the (objective or subjective) observation are
approximated by a special mixture model, in such a way that any desired
conditional distribution can be directly obtained without numerical
integration. We have developed an extended version of the expectation
maximization (EM) algorithm to estimate the parameters of mixture models from
uncertain training examples (indirect observations). As a consequence, any
piece of exact or uncertain information about both input and output values is
consistently handled in the inference and learning stages. This ability,
extremely useful in certain situations, is not found in most alternative
methods. The proposed framework is formally justified from standard
probabilistic principles and illustrative examples are provided in the fields
of nonparametric pattern classification, nonlinear regression and pattern
completion. Finally, experiments on a real application and comparative results
over standard databases provide empirical evidence of the utility of the method
in a wide range of applications
Genetic characterization of Acipenser sturio L., 1758 in relation to other sturgeon species using satellite DNA
We obtained and characterized a satellite (st) DNA family named HindIII from the genomes of the Adriatic sturgeon Acipenser naccarii Bonaparte, 1836, Siberian sturgeon Acipenser baerii Brandt, 1869, and beluga sturgeon Huso huso (L., 1758). We did not find this stDNA in the genome of the Atlantic sturgeon Acipenser sturio L., 1758. The comparison of sturgeon species using the HindIII stDNA revealed the following: (1) A. naccarii and A. baerii are closely related; (2) H. huso appears to belong to the genus Acipenser and, probably, Huso is not a separate genus within the Acipenserinae; (3) A. sturio differs from the other three studied species by the absence of the HindIII stDNA and, most likely, it represents a separate evolutionary lineage within the Acipenseridae. The data on the HindIII stDNA can be successfully used for species identification of sturgeon specimens captured in different European regions.En este trabajo presentamos la caracterización del genoma de Acipenser sturio L., 1758 en relación con el genoma de Acipenser naccarii Bonaparte, 1836, Acipenser baerii Brandt, 1869 y Huso huso (L., 1758) utilizando una familia de ADN satélite (la familia HindIII). Nuestro análisis revela que: (1) A. naccarii y A. baerii son especies muy emparentadas; (2) H. huso aparece muy relacionada con las especies del género Acipenser y, probablemente, podría ser considerada como una especie perteneciente a dicho género, y (3) A. sturio difiere del resto de las especies analizadas, lo que sugiere que esta especie ha debido seguir una evolución independiente respecto a las otras especies. Estos datos pueden ser muy útiles, no sólo para establecer las relaciones filogenéticas entre A. sturio y las otras especies de Acipenseridae, sino también para la identificación de ejemplares de esturiones capturados en diferentes regiones europeas.Instituto Español de Oceanografí
2MASS J154043.42-510135.7: a new addition to the 5 pc population
The aim of the project is to find the stars nearest to the Sun and to
contribute to the completion of the stellar and substellar census of the solar
neighbourhood. We identified a new late-M dwarf within 5 pc, looking for high
proper motion sources in the 2MASS-WISE cross-match. We collected astrometric
and photometric data available from public large-scale surveys. We complemented
this information with low-resolution optical and near-infrared spectroscopy
with instrumentation on the ESO NTT to confirm the nature of our candidate. We
also present a high-quality medium-resolution VLT/X-shooter spectrum covering
the 400 to 2500 nm wavelength range. We classify this new neighbour as an
M7.00.5 dwarf using spectral templates from the Sloan Digital Sky Survey
and spectral indices. Lithium absorption at 670.8 nm is not detected in the
X-shooter spectrum, indicating that the M7 dwarf is older than 600 Myr and more
massive than 0.06 M. We also derive a trigonometric distance of 4.4
pc, in agreement with the spectroscopic distance estimate, making
2MASS\,J154043.42510135.7 the nearest M7 dwarf to the Sun. This
trigonometric distance is somewhat closer than the 6 pc distance reported
by the ALLWISE team, who independently identified this object recently. This
discovery represents an increase of 25\% in the number of M7--M8 dwarfs already
known at distances closer than 8\,pc from our Sun. We derive a density of
\,=\,1.90.910\,pc for M7 dwarfs in the 8 pc
volume, a value similar to those quoted in the literature. This new ultracool
dwarf is among the 50 nearest systems to the Sun, demonstrating that our
current knowledge of the stellar census within the 5 pc sample remains
incomplete. 2M1540 represents a unique opportunity to search for extrasolar
planets around ultracool dwarfs due to its proximity and brightness.Comment: 8 pages, 5 figures. Acepted in Astronomy & Astrophysics (15/05/2005
Binary frequency of planet-host stars at wide separations: A new brown dwarf companion to a planet-host star
The aim of the project is to improve our knowledge on the multiplicity of
planet-host stars at wide physical separations.
We cross-matched approximately 6200 square degree area of the Southern sky
imaged by the Visible Infrared Survey Telescope for Astronomy (VISTA)
Hemisphere Survey (VHS) with the Two Micron All Sky Survey (2MASS) to look for
wide common proper motion companions to known planet-host stars. We
complemented our astrometric search with photometric criteria.
We confirmed spectroscopically the co-moving nature of seven sources out of
16 companion candidates and discarded eight, while the remaining one stays as a
candidate. Among these new wide companions to planet-host stars, we discovered
a T4.5 dwarf companion at 6.3 arcmin (~9000 au) from HIP70849, a K7V star which
hosts a 9 Jupiter mass planet with an eccentric orbit. We also report two new
stellar M dwarf companions to one G and one metal-rich K star. We infer stellar
and substellar binary frequencies for our complete sample of 37 targets of
5.4+/-3.8% and 2.7+/-2.7% (1 sigma confidence level), respectively, for
projected physical separations larger than ~60-160 au assuming the range of
distances of planet-host stars (24-75 pc). These values are comparable to the
frequencies of non planet-host stars. We find that the period-eccentricity
trend holds with a lack of multiple systems with planets at large
eccentricities (e > 0.2) for periods less than 40 days. However, the lack of
planets more massive than 2.5 Jupiter masses and short periods (<40 days)
orbiting single stars is not so obvious due to recent discoveries by
ground-based transit surveys and space missions.Comment: Accepted for publication in A&A, 13 pages, 5 figures, 3 tables,
optical spectra will be available at CDS Strasbour
Optical sensor to determine plant spacing for precise application
Congreso Agroingeniería 2015. Orihuela (Alicante). 1 a 3 de junio de 2015La automatización en el manejo de la mala hierba de forma individualizada está siendo una
realidad cada vez más cercana, tanto objetivos de eficiencia como de beneficio económico se
están consiguiendo. En un futuro muy próximo la mecanización y su diseño tendrá que
contemplar técnicas de monitorización o detección de precisión. El objetivo de este estudio fue
evaluar la capacidad de un sensor óptico para determinar el espacio entre las plantas de una
misma línea de cultivo en diferentes condiciones: laboratorio y campo. Este equipo de trabajo ha
investigado la detección del cultivo con un sensor fotoeléctrico de infrarrojo (880 nm) en modo
opuesto. La barrera fotoeléctrica de transmisión, usa un par de sensores y al paso de la planta
por la cortina de luz interrumpe el haz. La señal de luz se recibe de forma simultánea en tiempo
real mediante un sistema de control de alta velocidad. El sensor fotoeléctrico fue capaz de
detectar la planta de tomate y por tanto de terminar la separación entre ellas de forma muy
precisa. El uso de sistemas de detección como este puede dar lugar a una nueva era que
permita el control en la línea de cultivo de la mala hierba de forma más económica y a la
automatización de la operación. El control preciso de la mala hierba es un reto importante para
este grupo, por ello tenemos previsto seguir trabajando en esta línea.Automation of individual crop plant care in commercial vegetable crop fields has increased
practical feasibility and improved efficiency and economic benefit. Its systems approach is taken
in the mechanization engineering design by the incorporation of precision sensing techniques.
The objective of this study was design-sensing capabilities in an implement for measuring plant
spacing under different test conditions: laboratory and field. For that proposal, a photoelectric
transmission barrier, by using an optical light curtain transmitter and receiver, evaluated the
interruption by the tomato stem of the light curtain, being recorded simultaneously in real-time by
a high-speed embedded control system. The optical sensor provided tomato plant detection and
therefore the spacing between tomato plants was determined with accuracy. The use of this
detection system may result in a new era that allow for an online control of aggressive weeds and
the automation of weeding tools, which we plan to pursue through future research.Junta de Andalucía P12-AGR-122
Determination by optical systems of the inter-plant real distance for precise weed control
La automatización en el manejo de las malas hierbas de forma individualizada está siendo una realidad cada vez más cercana, atendiendo a objetivos tanto de eficiencia como de beneficios económicos. En un futuro muy próximo la mecanización y su diseño tendrá que contemplar técnicas de monitorización o detección de precisión. El objetivo de este estudio fue evaluar la capacidad de un sensor óptico para determinar la distancia entre las plantas de una misma línea de cultivo en condiciones de laboratorio y campo. En concreto, se ha investigado la detección de plantas con un sensor fotoeléctrico de infrarrojo (880 nm) en modo opuesto. El sensor fotoeléctrico fue capaz de detectar la planta de tomate y por tanto permitir conocer la separación entre ellas de forma muy precisa. El uso de sistemas de detección como este puede dar lugar a una nueva era que permita el control en la línea de cultivo de la mala hierba de forma más económica y a la automatización de la operación.Automation of individual crop plant care in comercial vegetable crop fields has increased practical feasibility and improved efficiency and economic benefit. Its systems approach is taken in the mechanization engineering design by the incorporation of precision sensing techniques. The objective of this study was design-sensing capabilities in an implement for measuring plant spacing under different test conditions: laboratory and field. The optical sensor provided tomato plant detection and therefore the spacing between tomato plants was determined with accuracy. The use of this detection system may result in a new era that allow for an online control of aggressive weeds and the automation of weeding tools, which we plan to pursue through future research
On the variability of HD 170699 - a possible COROT target
We present the analysis of the variability of HD 170699, a COROT star showing
the characteristics of a non evolutionary Delta Scuti star with high rotational
velocity. There is a clear period of 10.45 c/d with 5.29 mmag amplitude in the
y filter. From the data, it can be seen that the star shows multi-periodicity
and it is necessary to add more frequencies to adjust the observationsComment: To appear in RevMexAA(SC) in Proceedings of XII Reunion Regional
Latinoamericana de la UAI held in Isla Margarita, Venezuela, October 22-26,
200
Representative Stress-Strain Curve by Spherical Indentation on Elastic-Plastic Materials
Tensile stress-strain curve of metallic materials can be determined by the representative stress-strain curve from the spherical indentation. Tabor empirically determined the stress constraint factor (stress CF), ψ, and strain constraint factor (strain CF), β, but the choice of value for ψ and β is still under discussion. In this study, a new insight into the relationship between constraint factors of stress and strain is analytically described based on the formation of Tabor’s equation. Experiment tests were performed to evaluate these constraint factors. From the results, representative stress-strain curves using a proposed strain constraint factor can fit better with nominal stress-strain curve than those using Tabor’s constraint factors
Morphometric and genetic analysis as proof of the existence of two sturgeon species in the Guadalquivir river
Morphometric and genetic methods were used
to identify two sturgeon species, Acipenser naccarii Bo-
naparte, 1836, and A. sturio Linnaeus, 1758, captured in
some of the principal rivers of the Iberian Peninsula,
including the Guadalquivir. After measuring 25 Iberian
specimens from a ®shery and several Spanish and Por-
tuguese museums and applying stepwise discriminant
analysis (SDA), four specimens preserved in di erent
museums [two specimens from the Guadalquivir river
(EBD-8173 and EBD-8174), one specimen from the
Tagus river (MUC1) and one specimen from the
Mondego river (MUC46B)], as well as ®ve specimens
captured in the Guadalquivir river in the 1940s but not
preserved (CM1, CM2, CM3, CM4 and CM5), were
identi®ed as A. naccarii. After cloning and character-
isation of a satellite-DNA family, HindIII, from
A. naccarii genome, its absence from the genome of
A. sturio was determined. Using this satellite-DNA as a
genetic marker and by means of dot-blotting, we dem-
onstrate that the DNA of the two specimens captured
during the mid-1970s in the Guadalquivir river cross-
hybridised with HindIII satellite-DNA sequences of
A. naccarii. We conclude that A. naccarii is autochtho-
nous to the Iberian Peninsula and is not, as was previ-
ously believed, endemic to the Adriatic Sea
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