1,274 research outputs found
Thinking beyond organism energy use: A trait-based bioenergetic mechanistic approach for predictions of life history traits in marine organisms
The functional trait-based bioenergetic approach is emergent in many ecological spectra, from the conservation of natural resources to mitigation and adaptation strategies in a global climate change context. Such an approach relies on being able to exploit mechanistic rules to connect environmental human-induced variability to functional traits (i.e. all those specific traits defining species in terms of their ecological roles) and use these to provide estimates of species life history traits (LH; e.g. body size, fecundity per life span, number of reproductive events). LHs are species-specific and proximate determinants of population characteristics in a certain habitat. They represent the most valuable quantitative information to investigate how broad potential distributional boundaries of a species are, and to feed predictive population models. There is much to be found in the current literature that describes mechanistic functional trait-based bioenergetics models, using them to test ecological hypotheses, but a mathematical framework often renders interpretation and use complicated. Here, we wanted to present a simpler interpretation and description of one of the most important recent mechanistic bioenergetic theories: the dynamic energy budget theory by Kooijman (Dynamic Energy Budget Theory for Metabolic Organisation, 2010, Cambridge University Press, Cambridge). Our main aim was to disentangle those aspects that at first reading may seem too mathematically challenging to many marine biologists, ecologists and environmental scientists, and present them for use in mechanistic applications
Il GIS come strumento di fruizione territoriale e valorizzazione turistica
The goal of this work has been to achieve a Geographic Information System, using innovative
cartographic representation of the land and landscape, which can provide to the end users an easier
and immediate access regarding tourist, cultural and environmental information.
This is an ongoing research, carried out in collaboration with the Department of Civil, Engineering,
Environmental, Aerospace, Materials (DICAM) of University of Palermo, with the objective to
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Atti 17a Conferenza Nazionale ASITA - Riva del Garda 5-7 novembre 2013
achieve a complete integration between software used only by qualified specialists in the field and
online platforms display.
To experience this work, has been used tourist information about the four regional Sicilian Parks:
Madonie, Nebrodi, Etna and Alcantara.
The software tools used in this project are the ESRI ArcGIS 9 and Google Earth for the display
platform of the virtual globe.
For such purpose, the study has been divided into three steps:
\uf0b7 First step: gathering maps necessary in order to achieve the objectives and the realization of
the thematic maps, either for the environmentally protective restrictions and the territorial
administrative boundary.
\uf0b7 Second step: research and selection of tourist information for each park; creation and
processing of its thematic maps.
\uf0b7 Third step: export of thematic maps in Google Earth using KML interchange format,
integrated with the addition of metadata containing the characteristics of places.
The results obtained to date from this research show that the integration of GIS and online display
platforms of satellite images, enriched in geographic content, can be valuable support to the new
vision of \u201cdigital tourism\u201d, allowing the use of tourist information to heterogeneous users not
necessarily specialized.
This study, in the near future, can be extended embracing new environmental contexts and more
tourist information
Evaluation of the Stormwater Capture Potential of New York City Soils: Implications of Infiltration Rate Variability on Urban Runoff Predictions
The properties used to characterize soils and, more specifically, those that are used to describe the rate at which water infiltrates into them, are key parameters in most rainfall-runoff models. Because these parameters are known to be highly variable, they are a known source of uncertainty in our ability to predict runoff from pervious surfaces. The goals of this study were to a) characterize the heterogeneity in soil and infiltration characteristics in specific types of pervious surfaces found in New York City, and b) to study the potential effect of this heterogeneity on prediction of the total volume and peak rate of runoff from specific rainfall hyetographs. Characterization of soil and infiltration characteristics was performed at a variety of sites throughout NYC during Summer and Fall 2009. As expected, statistical analysis of the data, which includes nearly two dozen individual tests, showed high variability. The USEPA Stormwater Management Model, (SWMM) an industry standard, was then used to examine the impact of this heterogeneity on predictions of peak flow and total runoff volume for a design storm. The preliminary results of this work suggest that although soil and infiltration properties are highly variable, only a small portion of this range can significantly alter the runoff predictions obtained from SWMM using this particular design storm. Future research will address the significance of the variability in runoff predictions given a more diverse set of storm events for more generalizeable results
The comet 17P/Holmes 2007 outburst: the early motion of the outburst material
Context. On October 24, 2007 the periodic comet 17P/Holmes underwent an
astonishing outburst that increased its apparent total brightness from
magnitude V\sim17 up to V\sim2.5 in roughly two days. We report on Wendelstein
0.8 m telescope (WST) photometric observations of the early evolution stages of
the outburst. Aims. We studied the evolution of the structure morphology, its
kinematic, and estimated the ejected dust mass. Methods. We analized 126 images
in the BVRI photometric bands spread between 26/10/2007 and 20/11/2007. The
bright comet core appeared well separated from that one of a quickly expanding
dust cloud in all the data, and the bulk of the latter was contained in the
field of view of our instrument. The ejected dust mass was derived on the base
of differential photometry on background stars occulted by the moving cloud.
Results. The two cores were moving apart from each other at a relative
projected constant velocity of (9.87 +/- 0.07) arcsec/day (0.135 +/-0.001
km/sec). In the inner regions of the dust cloud we observed a linear increase
in size at a mean constant velocity of (14.6+/-0.3) arcsec/day (0.200+/-0.004
km/sec). Evidence of a radial velocity gradient in the expanding cloud was also
found. Our estimate for the expanding coma's mass was of the order of 10^{-2}-1
comet's mass implying a significant disintegration event. Conclusions. We
interpreted our observations in the context of an explosive scenario which was
more probably originated by some internal instability processes, rather than an
impact with an asteroidal body. Due to the peculiar characteristics of this
event, further observations and investigations are necessary in order to
enlight the nature of the physical processes that determined it.Comment: 5 pages, 3 figures, A&A accepte
New and updated stellar parameters for 90 transit hosts. The effect of the surface gravity
Context. Precise stellar parameters are crucial in exoplanet research for
correctly determining of the planetary parameters. For stars hosting a
transiting planet, determining of the planetary mass and radius depends on the
stellar mass and radius, which in turn depend on the atmospheric stellar
parameters. Different methods can provide different results, which leads to
different planet characteristics.}%Spectroscopic surface gravities have shown
to be poorly constrained, but the photometry of the transiting planet can
provide an independent measurement of the surface gravity.
Aims. In this paper, we use a uniform method to spectroscopically derive
stellar atmospheric parameters, chemical abundances, stellar masses, and
stellar radii for a sample of 90 transit hosts. Surface gravities are also
derived photometrically using the stellar density as derived from the light
curve. We study the effect of using these different surface gravities on the
determination of the chemical abundances and the stellar mass and radius.
Methods. A spectroscopic analysis based on Kurucz models in LTE was performed
through the MOOG code to derive the atmospheric parameters and the chemical
abundances. The photometric surface gravity was determined through isochrone
fitting and the use of the stellar density, directly determined from the light
curve. Stellar masses and radii are determined through calibration formulae.
Results. Spectroscopic and photometric surface gravities differ, but this has
very little effect on the precise determination of the stellar mass in our
spectroscopic analysis. The stellar radius, and hence the planetary radius, is
most affected by the surface gravity discrepancies. For the chemical
abundances, the difference is, as expected, only noticable for the abundances
derived from analyzing of lines of ionized species.Comment: 12 pages, 6 figures, 5 tables, accepted to A&
A new analysis of the WASP-3 system: no evidence for an additional companion
In this work we investigate the problem concerning the presence of additional
bodies gravitationally bounded with the WASP-3 system. We present eight new
transits of this planet and analyse all the photometric and radial velocity
data published so far. We did not observe significant periodicities in the
Fourier spectrum of the observed minus calculated (O-C) transit timing and
radial velocity diagrams (the highest peak having false-alarm probabilities of
56 per cent and 31 per cent, respectively) or long-term trends. Combining all
the available information, we conclude that the radial velocity and transit
timing techniques exclude, at 99 per cent confidence limit, any perturber more
massive than M \gtrsim 100 M_Earth with periods up to 10 times the period of
the inner planet. We also investigate the possible presence of an exomoon on
this system and determined that considering the scatter of the O-C transit
timing residuals a coplanar exomoon would likely produce detectable transits.
This hypothesis is however apparently ruled out by observations conducted by
other researchers. In case the orbit of the moon is not coplanar the accuracy
of our transit timing and transit duration measurements prevents any
significant statement. Interestingly, on the basis of our reanalysis of SOPHIE
data we noted that WASP-3 passed from a less active (log R'_hk=-4.95) to a more
active (log R'_hk=-4.8) state during the 3 yr monitoring period spanned by the
observations. Despite no clear spot crossing has been reported for this system,
this analysis claims for a more intensive monitoring of the activity level of
this star in order to understand its impact on photometric and radial velocity
measurements.Comment: MNRAS accepted (14/08/2012
Segmentazione delle serie temporali nell’analisi dei dati: un esempio di applicazione a dati sismo-vulcanici.
Il presente report descrive quanto sviluppato dagli autori per l’analisi delle serie temporali utilizzate
per il monitoraggio sismo-vulcanico del vulcano Etna. La necessitĂ di ottenere una rappresentazione ridotta
delle serie temporali ha portato alla ricerca ed alla implementazione degli algoritmi di segmentazione oggetto
del presente lavoro.
Le metodologie introdotte nel paragrafo 2, largamente applicate nella disciplina del data mining su
serie temporali, costituiscono ad oggi lo stato dell’arte per quanto riguarda le tecniche di approssimazione di
serie temporali. In particolare, l’applicazione dell’algoritmo bottom-up ha permesso una compressione
elevata dei dati, consentendo quindi una rappresentazione con un numero di punti inferiore rispetto a quello
delle serie temporali di partenza. In questo contesto la scelta delle soglie errore, legata indirettamente al
numero di segmenti con cui si approssima la serie temporale, è stata scelta in modo empirico. Questa scelta è
stata vincolata alla dimensione dei buffer di dati da impiegare per scopi di visualizzazione ed elaborazione.
Future implementazioni riguarderanno l’ottimizzazione in linea degli algoritmi Sliding Window in modo da
operare in real-time sugli streaming di dati ed ottimizzarne l’archiviazione e la visualizzazione
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