1,097 research outputs found
Towards a better classification of unclear eruptive variables: the cases of V2492 Cyg, V350 Cep, and ASASSN-15qi
Eruptive variables are young stars that show episodic variations of
brightness: EXors/FUors variations are commonly associated with enhanced
accretion outbursts occurring at intermittent cadence of months/years (EXors)
and decades/centuries (FUors). Variations that can be ascribed to a variable
extinction along their line of sight are instead classified as UXors. We aim at
investigating the long-term photometric behaviour of three sources classified
as eruptive variables. We present data from the archival plates of the Asiago
Observatory relative to the fields where the targets are located. For the sake
of completeness we have also analysed the Harvard plates of the same regions
that cover a much longer historical period, albeit at a lower sensitivity,
however we are only able to provide upper limits. A total of 273 Asiago plates
were investigated, providing a total of more than 200 magnitudes for the three
stars, which cover a period of about 34 yr between 1958 and 1991. We have
compared our data with more recently collected literature data. Our plates
analysis of V2492 Cyg provides historical upper limits that seem not to be
compatible with the level of the activity monitored during the last decade.
Therefore, recently observed accretion phenomena could be associated with the
outbursting episodes, more than repetitive obscuration. While a pure extinction
does not seem the only mechanism responsible for the ASASSN-15qi fluctuations,
it can account quite reasonably for the recent V350 Cep variations.Comment: 12 pages, accepted by A&
Association between diverticulosis and colonic neoplastic lesions in individuals with a positive faecal immunochemical test
Background The association between diverticulosis and colonic neoplastic lesions has been suggested, but data in literature are conflicting. This study aimed to investigate such a relationship in patients participating in a colorectal cancer screening program who underwent high-quality colonoscopy.Methods Data from consecutive individuals 50-75 years of age with a positive faecal immunological test were considered. Diverticulosis was categorised as present or absent. The prevalence of neoplastic lesions (adenoma, advanced adenoma, and cancer) between individuals with and those without diverticula was compared. A multivariate analysis was performed.Results Overall, data from 970 consecutive individuals were evaluated, and diverticulosis was detected in 354 (36.5%) cases. At least one adenoma was detected in 490 (50.5%) people, at least one advanced adenoma in 264 (27.2%), multiple adenoma in 71 (7.3%), whilst a cancer was diagnosed in 48 (4.9%) cases. At univariate analysis, the adenoma detection rate in patients with diverticula was significantly higher than in controls (55.9% vs 47.4%; p=0.011). At multivariate analysis, presence of diverticulosis was an independent risk factor for both adenoma detection rate (OR=1.58; 95% CI=1.14-2.18; p=0.006) and advanced adenoma (OR=1.57; 95% CI=1.10-2.24; p=0.013), but not for colorectal cancer.Conclusions In a colorectal screening setting, the adenoma detection rate was significantly higher in individuals with diverticulosis than in controls
KINEMATICS OF THE TRUNK AND THE SPINE DURING UNRESTRICTED AND RESTRICTED SQUATS – A PRELIMINARY ANALYSIS
The aim of the study was the assessment and comparison of trunk kinematics during restricted (knee not beyond toes) and unrestricted squats. Eight repetitions of restricted and unrestricted squats with 0, 25% and 50% bodyweight loading using a barbell were assessed with a 12 camera motion analysis system. A trunk marker set was developed and applied that allowed the measurement of the 3D kinematics of the trunk, divided into three segments (lumbar, thoracic and upper trunk) and the analysis of the sagittal curvature (lumbar and thoracic spine). The preliminary results of four subjects showed a larger range of sagittal motion between lumbar and pelvic segments for the restricted compared to the unrestricted squat. The lumbar curvature straightened with increasing load. The unrestricted execution seems to lead to higher stresses in the lower back
SOILS WITH HIGH ORGANIC CARBON STORAGE CAPACITY IN DEPTH
Most studies about soil organic carbon (OC) stock focus on the topsoil storage capacity, however,
it has been proved that OC can reach relatively high values also in depth. The aim of this work was
a preliminary investigation of the soil types with a high OC content in depth and the relationship
with the main pedogenetic factors. The dataset was the 1,414 Italian National Soil Typologies
(STU). The selected attributes were: mean value of OC in the superficial functional horizon (L1);
weighted average value between 50 and 100 cm (L2) and under 100 cm (L3); WRB classification;
main lithology, morphology and land-use. About 92% of typologies had more than 0.58% of OC in
L1, about 30% in L2, and 10% in L3. The highest OC contents were in L2 of Histosols, Umbrisols,
Podzols, Vertisols, Andosols, and in L3 of Vertisols, Andosols, Fluvisols. STU on volcanic rocks,
slope and residual deposits showed relatively higher accumulation in L2; soils on delta plane,
lacustrine and alluvial deposits, both in L2 and L3. STU on upland plains, transitional areas with
plateau in the mountain, high gradient mountains and low plains, showed higher OC content.
Land-use was not significantly connected with OC content in depth. About 65% of the studied
territory (47% of Italian surface) had a relatively high CO content in L2, and about 2% in L3. The
main processes connected to soil CO storage capacity in depth were morphological, namely
colluvium and alluvium, as well as pedological, in particular, podzolization and andisolization
POISSON project - III - Investigating the evolution of the mass accretion rate
As part of the POISSON project (Protostellar Optical-Infrared Spectral Survey
on NTT), we present the results of the analysis of low-resolution NIR spectra
0.9-2.4 um) of two samples of YSOs in Lupus and Serpens (52 and 17 objects),
with masses 0.1-2.0 Msun and ages from 10^5 to a few 10^7 yr. After determining
the accretion parameters of the Lup and Ser targets by analysing their HI
near-IR emission features, we added the results to those from previous regions
(investigated in POISSON with the same methodology). We obtained a final
catalogue (143 objects) of mass accretion rates (Macc) derived in a homogeneous
fashion and analysed how Macc correlates with M* and how it evolves in time. We
derived the accretion luminosity (Lacc) and Macc for Lup and Ser objects from
the Br_gamma line by using relevant empirical relationships from the literature
that connect HI line luminosity and Lacc. To minimise the biases and also for
self-consistency, we re-derived mass and age for each source using the same set
of evolutionary tracks. We observe a correlation MaccM*^2.2, similarly to what
has previously been observed in several star-forming clouds. The time variation
of Macc is roughly consistent with the expected evolution in viscous disks,
with an asymptotic decay that behaves as t^-1.6. However, Macc values are
characterised by a large scatter at similar ages and are on average higher than
the predictions of viscous models. Although part of the scattering may be
related to the employed empirical relationship and to uncertainties on the
single measurements, the general distribution and decay trend of the Macc
points are real. These findings might be indicative of a large variation in the
initial mass of the disks, of fairly different viscous laws among disks, of
varying accretion regimes, and of other mechanisms that add to the dissipation
of the disks, such as photo-evaporation.Comment: 18 pages, 10 figures, accepted by A&
Comparing different approaches - data mining, geostatistic, and deterministic pedology - to assess the frequency of WRB Reference Soil Groups in the Italian soil regions
Estimating frequency of soil classes in map unit is always affected by some degree of uncertainty, especially at
small scales, with a larger generalization.
The aim of this study was to compare different possible approaches - data mining, geostatistic, deterministic
pedology - to assess the frequency of WRB Reference Soil Groups (RSG) in the major Italian soil regions.
In the soil map of Italy (Costantini et al., 2012), a list of the first five RSG was reported in each major 10 soil
regions. The soil map was produced using the national soil geodatabase, which stored 22,015 analyzed and
classified pedons, 1,413 soil typological unit (STU) and a set of auxiliary variables (lithology, land-use, DEM).
Other variables were added, to better consider the influence of soil forming factors (slope, soil aridity index,
carbon stock, soil inorganic carbon content, clay, sand, geography of soil regions and soil systems) and a grid at 1
km mesh was set up.
The traditional deterministic pedology assessed the STU frequency according to the expert judgment presence in
every elementary landscape which formed the mapping unit.
Different data mining techniques were firstly compared in their ability to predict RSG through auxiliary variables
(neural networks, random forests, boosted tree, supported vector machine (SVM)). We selected SVM according
to the result of a testing set. A SVM model is a representation of the examples as points in space, mapped so that
examples of separate categories are divided by a clear gap that is as wide as possible.
The geostatistic algorithm we used was an indicator collocated cokriging. The class values of the auxiliary
variables, available at all the points of the grid, were transformed in indicator variables (values 0, 1). A principal
component analysis allowed us to select the variables that were able to explain the largest variability, and to
correlate each RSG with the first principal component, which explained the 51% of the total variability. The
principal component was used as collocated variable. The results were as many probability maps as the estimated
WRB classes. They were summed up in a unique map, with the most probable class at each pixel.
The first five more frequent RSG resulting from the three methods were compared.
The outcomes were validated with a subset of the 10% of the pedons, kept out before the elaborations. The error
estimate was produced for each estimated RSG.
The first results, obtained in one of the most widespread soil region (plains and low hills of central and southern
Italy) showed that the first two frequency classes were the same for all the three methods. The deterministic
method differed from the others at the third position, while the statistical methods inverted the third and fourth
position.
An advantage of the SVM was the possibility to use in the same elaboration numeric and categorical variable,
without any previous transformation, which reduced the processing time.
A Bayesian validation indicated that the SVM method was as reliable as the indicator collocated cokriging, and
better than the deterministic pedological approach
Spitzer-MIPS survey of the young stellar content in the Vela Molecular Cloud-D
A new, unbiased Spitzer-MIPS imaging survey (~1.8 square degs) of the young
stellar content of the Vela Molecular Cloud-D is presented. The survey is
complete down to 5mJy and 250mJy at 24micron (mu) and 70mu, respectively. 849
sources are detected at 24mu and 52 of them also have a 70mu counterpart. The
VMR-D region is one that we have already partially mapped in dust and gas
millimeter emission, and we discuss the correlation between the Spitzer compact
sources and the mm contours. About half of the 24mu sources are located inside
the region delimited by the 12CO(1-0) contours (corresponding to only one third
of the full area mapped with MIPS) with a consequent density increase of about
100% of the 24mu sources [four times for 70mu ones] moving from outside to
inside the CO contours. About 400 sources have a 2MASS counterpart. So we have
constructed a Ks vs. Ks-[24] diagram and identified the protostellar
population. We find an excess of Class I sources in VMR-D in comparison with
other star forming regions. This result is reasonably biased by the sensitivity
limits, or, alternatively, may reflect a very short lifetime (<=10^6yr) of the
protostellar content in this cloud. The MIPS images have identified embedded
cool objects in most of the previously identified starless cores; in addition,
there are 6 very young, possibly Class 0 objects identified. Finally we report
finding of the driving sources for a set of five out of six very compact
protostellar jets previously discovered in near-infrared images.Comment: 29 pages, 14 figures. To appear in Ap.
DESIGN OF STRENGTH EXERCISES FOR THE ABDUCTOR MUSCLES USING MUSCULOSKELETAL MODELING
Strength training exercises, require a specific joint range of motion and muscle-specific loading to avoid injury and allow adaptation of tissue. The purpose of this study was to design suitable strength training exercises for the hip abductor muscles based on predicted joint loading and motion. Using Opensim modeling, hip abduction/adduction movement was combined with internal/external rotation of the hip and an external force that was applied to the foot. The direction of the force was systematically rotated to mimic a change of the position towards the cable pulley system. M. gluteus mediuswas divided into an anterior and a posterior part. It was not possible to find a single exercise that allowed the training of the anterior and the posterior part simultaneously with a muscle activation \u3e50%. Herein, it has been shown that modeling can be used to design strength-training exercises
Comparing Different Approaches - Data Mining, Geostatistic, and Deterministic Pedology - to Assess the Frequency of WRB Reference Soil Groups in the Italian Soil Regions
The assessment of class frequency in soil map legends is affected by uncertainty, especially at small scales, where generalization is
larger. The aim of this study was to test the hypothesis that data mining or geostatistic techniques provide better estimation of class
frequency than traditional deterministic pedology in a national soil map.
In the map of Italian soil regions compiled at 1:5,000,000 reference scale, soil classes were the WRB Reference Soil Groups
(RSGs). Different data mining techniques, namely neural networks, random forests, boosted tree, classification and regression tree,
supported vector machine (SVM), were tested and the last one gave the best RSGs predictions, using selected auxiliary variables
and 22,015 classified soil profiles. Given the categorical target variable, the multi-collocated indicator cokriging was the algorithm
chosen for the geostatistic approach. The first five more frequent RSGs resulting from the three methods were compared. The
outcomes were validated with a Bayesian approach on a subset of 10% of geographically representative profiles, kept out before
the elaborations.
The most frequent classes were uniformly predicted by the three methods, which instead differentiated notably for the classes with
a lower occurrence. The Bayesian validation indicated that the SVM method was as reliable as the multi-collocated indicator
cokriging, and both more than the deterministic pedological approach. An advantage of the SVM was the possibility to use numeric
and categorical variable in the same elaboration, without any previous transformation, which notably reduced the processing time
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