15,189 research outputs found
Model Design of Wind/PV/Fossil-Fuel Hybrid Systems
This paper presents the analysis and design of a mathematical model for a hybrid-power generation system consisting of a photovoltaic array, wind-turbines, a batterybank and a backup fossil-fuel generator. The static mathematical models of each element are validated by comparing them with field-data obtained in an experimental hybrid generation system in Pachuca, Mexico. Two different state-of-charge models were simulated and compared. The results are presented in this paper. The main purpose of this work is the development of a fuzzy-supervisory-controller for small hybrid-systems
The importance of cephalopods to trawl fisheries in the western Mediterranean
The aim of the study was to define the commercial importance of cephalopods caught by trawlers from five Italian and Spanish Mediterranean ports. From summer 1995 to spring 1996, samples of the catches of trawlers were taken on board. The type of fishing activity was recorded and data were collected from at least three commercial hauls for each port, season and bathymetric stratum (350 m). The species composition and yield of the retained and discarded portions of the catch were noted for each port. From these data the commercial importance of each species was evaluated. Cephalopods were commercially important particularly in the shallower bathymetric stratum
An X-ray study of the SNR G344.7-0.1 and the central object CXOU J170357.8-414302
Aims. We report results of an X-ray study of the supernova remnant (SNR)
G344.7-0.1 and the point-like X-ray source located at the geometrical center of
the SNR radio structure. Methods. The morphology and spectral properties of the
remnant and the central X-ray point-like source were studied using data from
the XMM-Newton and Chandra satellites. Archival radio data and infrared Spitzer
observations at 8 and 24 m were used to compare and study its multi-band
properties at different wavelengths. Results. The XMM-Newton and Chandra
observations reveal that the overall X-ray emission of G344.7-0.1 is extended
and correlates very well with regions of bright radio and infrared emission.
The X-ray spectrum is dominated by prominent atomic emission lines. These
characteristics suggest that the X-ray emission originated in a thin thermal
plasma, whose radiation is represented well by a plane-parallel shock plasma
model (PSHOCK). Our study favors the scenario in which G344.7-0.1 is a 6 x 10^3
year old SNR expanding in a medium with a high density gradient and is most
likely encountering a molecular cloud on the western side. In addition, we
report the discovery of a soft point-like X-ray source located at the
geometrical center of the radio SNR structure. The object presents some
characteristics of the so-called compact central objects (CCO). However, its
neutral hydrogen absorption column (N_{H}) is inconsistent with that of the
SNR. Coincident with the position of the source, we found infrared and optical
objects with typical early-K star characteristics. The X-ray source may be a
foreground star or the CCO associated with the SNR. If this latter possibility
were confirmed, the point-like source would be the farthest CCO detected so far
and the eighth member of the new population of isolated and weakly magnetized
neutron stars.Comment: 9 pages, 8 figures, accepted for publication in Astronomy and
Astrophysics. Higher resolution figures can be seen on A&
Assessment of culture and environment in the Adolescent Brain and Cognitive Development Study: Rationale, description of measures, and early data.
Neurodevelopmental maturation takes place in a social environment in addition to a neurobiological one. Characterization of social environmental factors that influence this process is therefore an essential component in developing an accurate model of adolescent brain and neurocognitive development, as well as susceptibility to change with the use of marijuana and other drugs. The creation of the Culture and Environment (CE) measurement component of the ABCD protocol was guided by this understanding. Three areas were identified by the CE Work Group as central to this process: influences relating to CE Group membership, influences created by the proximal social environment, influences stemming from social interactions. Eleven measures assess these influences, and by time of publication, will have been administered to well over 7,000 9-10 year-old children and one of their parents. Our report presents baseline data on psychometric characteristics (mean, standard deviation, range, skewness, coefficient alpha) of all measures within the battery. Effectiveness of the battery in differentiating 9-10 year olds who were classified as at higher and lower risk for marijuana use in adolescence was also evaluated. Psychometric characteristics on all measures were good to excellent; higher vs. lower risk contrasts were significant in areas where risk differentiation would be anticipated
Observational constraints to boxy/peanut bulge formation time
Boxy/peanut bulges are considered to be part of the same stellar structure as
bars and both could be linked through the buckling instability. The Milky Way
is our closest example. The goal of this letter is determining if the mass
assembly of the different components leaves an imprint in their stellar
populations allowing to estimate the time of bar formation and its evolution.
To this aim we use integral field spectroscopy to derive the stellar age
distributions, SADs, along the bar and disc of NGC 6032. The analysis shows
clearly different SADs for the different bar areas. There is an underlying old
(>=12 Gyr) stellar population for the whole galaxy. The bulge shows star
formation happening at all times. The inner bar structure shows stars of ages
older than 6 Gyrs with a deficit of younger populations. The outer bar region
presents a SAD similar to that of the disc. To interpret our results, we use a
generic numerical simulation of a barred galaxy. Thus, we constrain, for the
first time, the epoch of bar formation, the buckling instability period and the
posterior growth from disc material. We establish that the bar of NGC 6032 is
old, formed around 10 Gyr ago while the buckling phase possibly happened around
8 Gyr ago. All these results point towards bars being long-lasting even in the
presence of gas.Comment: Accepted for publication in MNRAS Letter
Resolving galaxies in time and space: II: Uncertainties in the spectral synthesis of datacubes
In a companion paper we have presented many products derived from the
application of the spectral synthesis code STARLIGHT to datacubes from the
CALIFA survey, including 2D maps of stellar population properties and 1D
averages in the temporal and spatial dimensions. Here we evaluate the
uncertainties in these products. Uncertainties due to noise and spectral shape
calibration errors and to the synthesis method are investigated by means of a
suite of simulations based on 1638 CALIFA spectra for NGC 2916, with
perturbations amplitudes gauged in terms of the expected errors. A separate
study was conducted to assess uncertainties related to the choice of
evolutionary synthesis models. We compare results obtained with the Bruzual &
Charlot models, a preliminary update of them, and a combination of spectra
derived from the Granada and MILES models. About 100k CALIFA spectra are used
in this comparison.
Noise and shape-related errors at the level expected for CALIFA propagate to
0.10-0.15 dex uncertainties in stellar masses, mean ages and metallicities.
Uncertainties in A_V increase from 0.06 mag in the case of random noise to 0.16
mag for shape errors. Higher order products such as SFHs are more uncertain,
but still relatively stable. Due to the large number statistics of datacubes,
spatial averaging reduces uncertainties while preserving information on the
history and structure of stellar populations. Radial profiles of global
properties, as well as SFHs averaged over different regions are much more
stable than for individual spaxels. Uncertainties related to the choice of base
models are larger than those associated with data and method. Differences in
mean age, mass and metallicity are ~ 0.15 to 0.25 dex, and 0.1 mag in A_V.
Spectral residuals are ~ 1% on average, but with systematic features of up to
4%. The origin of these features is discussed. (Abridged)Comment: A&A, accepte
The origin of the Acheulean: the 1.7 million-year-old site of FLK West, Olduvai Gorge (Tanzania)
The appearance of the Acheulean is one of the hallmarks of human evolution. It represents the
emergence of a complex behavior, expressed in the recurrent manufacture of large-sized tools, with
standardized forms, implying more advance forethought and planning by hominins than those required
by the precedent Oldowan technology. The earliest known evidence of this technology dates back to
c. 1.7 Ma. and is limited to two sites (Kokiselei [Kenya] and Konso [Ethiopia]), both of which lack fauna.
The functionality of these earliest Acheulean assemblages remains unknown. Here we present the
discovery of another early Acheulean site also dating to c. 1.7 Ma from Olduvai Gorge. This site provides
evidence of the earliest steps in developing the Acheulean technology and is the oldest Acheulean site in
which stone tools occur spatially and functionally associated with the exploitation of fauna. Simple and
elaborate large-cutting tools (LCT) and handaxes co-exist at FLK West, showing that complex cognition
was present from the earliest stages of the Acheulean. Here we provide a detailed technological study
and evidence of the use of these tools on the butchery and consumption of fauna, probably by early
Homo erectus sensu lato
Valoración funcional en futbolistas y su utilidad en la recuperación tras una lesión
Aim - The objective of this study was to establish reference values for professional football players in a series of previously selected functional tests.
Methods - 42 professional football players were functionally assessed during two seasons (2012/13 and 2013/14), at three different times: preseason, midpoint of the season and end of the season. For this purpose, the following tests were carried out: Counter Movement Jump (bipodal jump), 5 metres Shuttle Run Sprint Test (speed/agility), Barrow Test (agility), Y Balance Test (posture control), Single Hop Test and Triple Hop Test (unipodal jump).
Results - The average obtained values were: Counter Movement Jump (40.25±4.13cm), 5 metres Shuttle Run Sprint Test (10.89±0.38 seconds), Barrow Test (7.46±0.27 seconds), right asymmetry Y Balance Test (4.63±2.16%), left asymmetry Y Balance Test (3.91±2.25%), right Single Hop Test (2.06±0.11 meters), left Single Hop Test (2.07±0.12 meters), right Triple Hop Test (6.87±0.29 meters) and left Triple Hop Test (6.83±0.31).
Conclusion - This paper contributes reference values which can be used to determine the sports performance or quantify the degree of functional recovery of an professional injured football player during his recovery.Objetivo – El objetivo del presente estudio consistió en establecer valores de referencia para futbolistas profesionales en una serie de test funcionales seleccionados previamente.
Método – Durante dos temporadas (2012/13 y 2013/14) y en tres momentos distintos de las mismas, 42 futbolistas profesionales fueron evaluados funcionalmente mediante las siguientes pruebas: CMJ (salto bipodal), 5 m Shuttle Run Sprint Test (velocidad/agilidad), Test de Barrow (agilidad), Y Balance Test (control postural), Single Hop Test y Triple Hop Test (salto unipodal).
Resultados – Los valores medios obtenidos fueron: CMJ (40.25±4.13cm), 5 m Shuttle Run Sprint Test (10.89±0.38 segundos), Test de Barrow (7.46±0.27 segundos), Y Balance asimetrÃa derecha (4.63±2.16%), Y Balance asimetrÃa izquierda (3.91±2.25%), Single Hop Test derecha (2.06±0.11 metros), Single Hop Test izquierda (2.07±0.12 metros), Triple Hop Test derecha (6.87±0.29 metros) y Triple Hop Test izquierda (6.83±0.31).
Conclusión – Este trabajo contribuye aportando valores de referencia que puedan ser utilizados para cuantificar el grado de recuperación funcional durante la recuperación de un futbolista profesional lesionado
AIP1 is a novel Agenet/Tudor domain protein from Arabidopsis that interacts with regulators of DNA replication, transcription and chromatin remodeling
Background: DNA replication and transcription are dynamic processes regulating plant development that are dependent on the chromatin accessibility. Proteins belonging to the Agenet/Tudor domain family are known as histone modification "readers" and classified as chromatin remodeling proteins. Histone modifications and chromatin remodeling have profound effects on gene expression as well as on DNA replication, but how these processes are integrated has not been completely elucidated. It is clear that members of the Agenet/Tudor family are important regulators of development playing roles not well known in plants.
Methods: Bioinformatics and phylogenetic analyses of the Agenet/Tudor Family domain in the plant kingdom were carried out with sequences from available complete genomes databases. 3D structure predictions of Agenet/Tudor domains were calculated by I-TASSER server. Protein interactions were tested in two-hybrid, GST pulldown, semi-in vivo pulldown and Tandem Affinity Purification assays. Gene function was studied in a T-DNA insertion GABI-line.
Results: In the present work we analyzed the family of Agenet/Tudor domain proteins in the plant kingdom and we mapped the organization of this family throughout plant evolution. Furthermore, we characterized a member from Arabidopsis thaliana named AIP1 that harbors Agenet/Tudor and DUF724 domains. AIP1 interacts with ABAP1, a plant regulator of DNA replication licensing and gene transcription, with a plant histone modification "reader" (LHP1) and with non modified histones. AIP1 is expressed in reproductive tissues and its down-regulation delays flower development timing. Also, expression of ABAP1 and LHP1 target genes were repressed in flower buds of plants with reduced levels of AIP1.
Conclusions: AIP1 is a novel Agenet/Tudor domain protein in plants that could act as a link between DNA replication, transcription and chromatin remodeling during flower development
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