113 research outputs found
Equilibria for broadcast range assignment games in ad-hoc networks
No full textAd-hoc networks are an emerging networking
technology, in which the nodes form a network with no fixed
infrastructure: each node forwards messages to the others by using
the wireless links induced by their power levels. Generally,
energy-efficient protocols heavily rely on cooperation. In this
paper, we analyze from a game-theoretic point of view the problem
of performing a broadcast operation from a given station . We
show both theoretical and experimental results on how the
existence of (good) Nash equilibria is determined by factors such
as the transmission power of the stations or the payment policy
that stations can use to enforce their reciprocal cooperation
Exploring the realm of scaled solar system analogues with HARPS
No full textContext. The assessment of the frequency of planetary systems reproducing the Solar System's architecture is still an open problem. Detailed study of multiplicity and architecture is generally hampered by limitations in quality, temporal extension and observing strategy, causing difficulties in detecting low-mass inner planets in the presence of outer giant planetary bodies.
Aims. We present the results of high-cadence and high-precision HARPS observations on 20 solar-type stars known to host a single long-period giant planet in order to search for additional inner companions and estimate the occurence rate fp of scaled Solar System analogs, i.e. systems featuring lower-mass inner planets in the presence of long-period giant planets.
Methods. We carry out combined fits of our HARPS data with literature radial velocities using differential evolution MCMC to refine the literature orbital solutions and search for additional inner planets. We then derive the survey detection limits to provide preliminary estimates of fp.
Results. We generally find better constrained orbital parameters for the known planets than those found in the literature. While no additional inner planet is detected, we find evidence for previously unreported long-period massive companions in systems HD 50499 and HD 73267. We finally estimate the frequency of inner low mass (10-30 M⊕) planets in the presence of outer giant planets as fp<9.84% for P<150 days.
Our preliminary estimate of fp is significantly lower than the values found in the literature; the lack of inner candidate planets found in our sample can also be seen as evidence corroborating the inward migration formation model for super-Earths and mini-Neptunes. Conclusions. Our results also underline the need for high-cadence and high-precision follow-up observations as the key to precisely determine the occurence of Solar System analogs
Fleas associated with non-flying small mammal communities from northern and central Chile: with new host and locality records
No full textFleas associated with small mammals from seven localities from northern and central Chile were assessed. We captured 352 small mammals belonging to 12 species from which we obtained 675 fleas belonging to 15 different species. The most frequently captured flea species were Neotyphloceras crassispina crassispina (n = 198) and N. chilensis (n = 175). High values of flea species richness and diversity were found in Fray Jorge National Park (NP), a north-central Chilean site, whereas the highest values of mean abundance (MA) and prevalence were found in three diverse sites that include Los Molles River, a high altitude site located in northcentral Chile, Fray Jorge NP and Dichato, in south-central Chile. On the other hand, high values of flea richness and diversity were found on two rodent species, Abrothrix olivacea and A. longipilis, whereas the highest values of MA and prevalence were found on Oligoryzomys longicaudatus, A. longipilis and Phyllotis xanthopygus. A total of three new host recordings, nine new localities and nine new host species and locality recordings are reported. Also, this study represents the first known record of Tetrapsyllus (Tetrapsyllus) comis in Chile and the first ecological analysis of Neotyphloceras chilensis.Fleas associated with small mammals from seven localities from northern and central Chile were assessed. We captured 352 small mammals belonging to 12 species from which we obtained 675 fleas belonging to 15 different species. The most frequently captured flea species were Neotyphloceras crassispina crassispina (n = 198) and N. chilensis (n = 175). High values of flea species richness and diversity were found in Fray Jorge National Park (NP), a north-central Chilean site, whereas the highest values of mean abundance (MA) and prevalence were found in three diverse sites that include Los Molles River, a high altitude site located in northcentral Chile, Fray Jorge NP and Dichato, in south-central Chile. On the other hand, high values of flea richness and diversity were found on two rodent species, Abrothrix olivacea and A. longipilis, whereas the highest values of MA and prevalence were found on Oligoryzomys longicaudatus, A. longipilis and Phyllotis xanthopygus. A total of three new host recordings, nine new localities and nine new host species and locality recordings are reported. Also, this study represents the first known record of Tetrapsyllus (Tetrapsyllus) comis in Chile and the first ecological analysis of Neotyphloceras chilensis.Fil: Bazán León, E. A.. Universidad de Santiago de Chile; ChileFil: Bazán León, E. A.. Universidad de Santiago de Chile; ChileFil: Lareschi, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores (i); Argentina. Universidad Nacional de La Plata; ArgentinaFil: Lareschi, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores (i); Argentina. Universidad Nacional de La Plata; ArgentinaFil: Sánchez, Juliana Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores (i); Argentina. Universidad Nacional de La Plata; ArgentinaFil: Sánchez, Juliana Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores (i); Argentina. Universidad Nacional de La Plata; ArgentinaFil: Soto Nilo, G.. Universidad de Santiago de Chile; ChileFil: Soto Nilo, G.. Universidad de Santiago de Chile; ChileFil: Lazzoni, I.. Universidad de Santiago de Chile; ChileFil: Lazzoni, I.. Universidad de Santiago de Chile; ChileFil: Venegas, C. I.. Universidad de Santiago de Chile; ChileFil: Venegas, C. I.. Universidad de Santiago de Chile; ChileFil: Poblete, Y.. Universidad de Santiago de Chile; ChileFil: Poblete, Y.. Universidad de Santiago de Chile; ChileFil: Vásquez, R. A.. Universidad de Santiago de Chile; ChileFil: Vásquez, R. A.. Universidad de Santiago de Chile; Chil
Development of a microwave sensor for the non-invasive detection of plant responses to water stress: A practical application on maize (Zea mays L.)
No full textIn this study, a novel microwave sensing system, consisting of a microstrip self-resonant spiral coil inductively coupled to an external concentric planar probe loop, is presented and applied to the non-destructive detection of morpho-physiological plant responses to water stress. The optimised set-up of the proposed sensor ensures a highly sensitive spiral coil, which is a fundamental requirement to derive accurate information on plants' behavioural alterations related to water stress conditions. The proposed microwave sensor was tested it on two potted maize cultivars (Zea mays L.), namely “Cinquantino Bianchi” (CB) and “Scagliolo Frassine” (SF). For each cultivar, half of the samples were maintained at 100% (T100) field capacity while the other half was at 25% (T25) from 46 to 74 Days After Sowing (DAS). The frequency (fr) shift and the amplitude peaks variation of the real component of the external planar probe input impedance (R(Zinput)) were obtained daily by positioning the sensor on the stem. These measured data were related to morpho-physiological parameters destructively acquired at four different growth stages. The resulting linear correlation between the stem's freshwater content (FWCstem) with both fr (r > −0.64) and the amplitude peaks (R (Zinput)) (r > -0.70) provided evidence of the sensor's ability to identify stem dielectric properties' variations between the two water treatments. Concurrently, the sensor response demonstrated the capability to identify changes in the morphology and histology of the stem. Based on preliminary findings, the proposed sensor shows potential for employment in the real-time monitoring of plant water status, contributing to more economically and environmentally sustainable crop management practices. While the current correlations between plant water content and sensor measurements require further refinement to meet the rigorous industrial standards, nevertheless a large-scale adoption can be envisioned by leveraging IoT methodologies
Protoplanetary disk insights from the first ERIS/vAPP survey at 4 μm
No full textAims. We present high-contrast imaging observations of seven protoplanetary disks at 4 μm using the Enhanced Resolution Imager and Spectrograph (ERIS) on the Very Large Telescope. This study focuses on detecting scattered light from micron-sized dust particles and assessing the potential of the grating vector Apodizing Phase Plat (gvAPP) coronagraph for disk and planet characterization.
Methods. Observations were performed in pupil-stabilized mode with the vAPP coronagraph. Data were reduced using reference differential imaging and angular differential imaging techniques, incorporating principal component analysis for point-source detection. Contrast curves and detection limits were computed for planetary companions and disk features.
Results. The infrared disk signal was resolved in all systems, with first-time 4 μm detections around AS 209 and Elias 2-24, revealing mostly axisymmetric structures extending up to 60 au. Two gaps were detected in the radial profiles of TW Hya (22 au, 35 au) and AS 209 (50 au, 100 au). For Elias 2-24, scattered light emission matched ALMA observations of inner disk structures, marking their first mid-infrared detection. In the case of HD 100546, the vAPP uncovered flared disk structures and faint spiral arms consistent with previous observations. HD 163296 shows a bright inner dust ring, confirming disk asymmetries and features, but we did not detect any planet candidate within the achieved contrast limits. The disk around PDS 70 exhibits clear features, with faint structures detected within the cavity. The observations achieved contrasts enabling the detection of planets down to 800 K, but no companions were detected, implying either low-mass planets, cooler formation scenarios, or a large dust extinction of AV ≳ 20 mag.
Conclusions. The vAPP performed robustly for imaging structures in protoplanetary disks at 4 μm, providing critical insights into disk morphology and constraints on planet formation processes. No planetary-mass companions with temperatures >1000 K are present in our sample
Le unità Liguri e Subliguri delle Colline del Candia (Alpi Apuane): litostratigrafia ed assetto tettonico
No full textThe Liguride and Subliguride units of the Candia Hills (Apuan Alps): lithostratigraphy and tectonic setting. A detailed field mapping (scale 1:5000) of the area located at the west side of the Apuan Alps (Candia Hills, Massa-Carrara province) has been carried on. The lithostratigraphic features and new findings of calcareous Nannofossils from the units outcropping in this area are reported.
The Candia Hills area represents an interesting sector belonging to the Northern Apennine where ligurian (Ottone Unit; Bertotti et al., 1986; Elter et al., 1991, Zanzucchi et al., 1993; Elter et al., in stampa), subligurian (Canetolo and Sanguineto-Marra units; Plesi, 1974; Labaume, 1992, Elter et al., in stampa; Pagani e Zanzucchi, 1970) and non-metamorphic tuscan unit (Tuscan Nappe), overriding the Apuan Metamorphic Complex, are exposed. A good knowledge of this sector could help to understand the complex miocenic tectonic events that led to Apuan Alps exumation (Carmignani et al., 1980; Coli, 1989; Carmignani e Kligfield, 1990).
A tectonic stack of units belonging to the liguride and subliguride domains overlies the Macigno Formation of the Tuscan Nappe.
The sequence of the Ottone Unit consists of thick calcareous turbidites with minor intercalations of ophiolite-bearing polimict pebbly-sandstones and -mudstones.
The Canetolo Unit consists of the Argille and calcari Formation (Early-Middle Eocene) characterized by two lithostratigraphic units ("shaly-calcareous" and "calcareous") whose relationships are connected to an early folding phase.
Between Canetolo Unit and Tuscan Nappe a non-continuous level of silty-marlstones has been recognized; the calcareous Nannofossils assemblage seems indicate a late Oligocene age. This unit has been here called "Mt.Olivero formation" and it can be probably referred to the subliguride domain (Sanguineto and Marra units of the Northern Apennines; Plesi, 1974; Labaume, 1992, Elter et al., in stampa; Pagani e Zanzucchi, 1970; Cerrina Feroni et al., 1990).
Near Case Lazzoni the contact between the Canetolo Unit and the overlying Ottone Unit is characterized by the presence of two tectonic slides; the first tectonic slide is made up of ophiolite-bearing pebbly-mudstones belonging to the Ottone Unit sequence. The second one is represented by medium- to thick-bedded siliciclastic arenites; the meaning of these arenites, still doubtful, would be clarified in other sectors of the Apuan Alps where this lithostratigraphic unit probably crops out.
Along the Candia Hills traverse the tectonic setting is characterized by the hinge zone of a N140 trending wide antiform overturned to SW ("Tyrrenian vergence"); this "post-nappe" structure can be considered the SE longitudinal extension of the Castelpoggio-Ortonovo antiform that has been described northward the study area (Cerrina Feroni et al., 1995).
Key words: Liguride units, Subliguride units, Apuan Alps, lithostratigraphy
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