Impacts of fragmented accretion streams onto Classical T Tauri Stars: UV and X-ray emission lines

Context. The accretion process in Classical T Tauri Stars (CTTSs) can be studied through the analysis of some UV and X-ray emission lines which trace hot gas flows and act as diagnostics of the post-shock downfalling plasma. In the UV band, where higher spectral resolution is available, these lines are characterized by rather complex profiles whose origin is still not clear. Aims. We investigate the origin of UV and X-ray emission at impact regions of density structured (fragmented) accretion streams.We study if and how the stream fragmentation and the resulting structure of the post-shock region determine the observed profiles of UV and X-ray emission lines. Methods. We model the impact of an accretion stream consisting of a series of dense blobs onto the chromosphere of a CTTS through 2D MHD simulations. We explore different levels of stream fragmentation and accretion rates. From the model results, we synthesize C IV (1550 {\AA}) and OVIII (18.97 {\AA}) line profiles. Results. The impacts of accreting blobs onto the stellar chromosphere produce reverse shocks propagating through the blobs and shocked upflows. These upflows, in turn, hit and shock the subsequent downfalling fragments. As a result, several plasma components differing for the downfalling velocity, density, and temperature are present altoghether. The profiles of C IV doublet are characterized by two main components: one narrow and redshifted to speed $\approx$ 50 km s$^{-1}$ and the other broader and consisting of subcomponents with redshift to speed in the range 200 $\approx$ 400 km s$^{-1}$. The profiles of OVIII lines appear more symmetric than C IV and are redshifted to speed $\approx$ 150 km s$^{-1}$. Conclusions. Our model predicts profiles of C IV line remarkably similar to those observed and explains their origin in a natural way as due to stream fragmentation.Comment: 11 pages, 10 figure

On the lower semicontinuous envelope of functionals defined on polyhedral chains

In this note we prove an explicit formula for the lower semicontinuous envelope of some functionals defined on real polyhedral chains. More precisely, denoting by $H \colon \mathbb{R} \to \left[ 0,\infty \right)$ an even, subadditive, and lower semicontinuous function with $H(0)=0$, and by $\Phi_H$ the functional induced by $H$ on polyhedral $m$-chains, namely \Phi_{H}(P) := \sum_{i=1}^{N} H(\theta_{i}) \mathcal{H}^{m}(\sigma_{i}), \quad\mbox{for every }P=\sum_{i=1}^{N} \theta_{i} [[ \sigma_{i} ]] \in\mathbf{P}_m(\mathbb{R}^n), we prove that the lower semicontinuous envelope of $\Phi_H$ coincides on rectifiable $m$-currents with the $H$-mass \mathbb{M}_{H}(R) := \int_E H(\theta(x)) \, d\mathcal{H}^m(x) \quad \mbox{ for every } R= [[ E,\tau,\theta ]] \in \mathbf{R}_{m}(\mathbb{R}^{n}). Comment: 14 page

Hot Jupiters accreting onto their parent stars: effects on the stellar activity

Hot Jupiters (HJs) are massive gaseous planets orbiting close to their host stars. Due to their physical characteristics and proximity to the central star, HJs are the natural laboratories to study the process of star-planet interaction (SPI). Phenomena related to SPI may include the inflation and the evaporation of planetary atmospheres, the formation of cometary tails and bow shocks and magnetospheric interaction between the magnetic field of the planet and that of the star. Several works suggest that some systems show enhanced stellar activity in phase with the planetary rotation period. In this work, we use a 3D magneto-hydrodynamic model that describes a system composed of a star and an HJ and that includes the corresponding planetary and stellar winds. The aim is to investigate whether the material evaporating from the planet interacts with the stellar extended corona, and generates observable features. Our simulation shows that, in some conditions, the planetary wind expands and propagates mainly along the planetary orbit. Moreover, part of the planetary wind collides with the stellar wind and a fraction of the planet's outflow is funnelled by the stellar magnetic field and hits the stellar surface. In both events, the material is heated up to temperatures of a few MK by a shock. These phenomena could manifest in the form of enhanced stellar activity at some orbital phases of the planet.Comment: Accepted for publication in Astronomische Nachrichten - Astronomical Note

Cyst nematodes of the genus Heterodera and Globodera in Sicily

A survey was conducted in Sicily, from 2007 to 2009, to obtain insights on specific composition, frequency and geographical distribution of cyst nematodes associated to crops of agricultural economic importance. Soil and root samples were collected mainly from crops showing chlorosis, poor growth and reduced yield. Cysts and larvae were extracted and identified to species level by comparative examination of morphological and morphometric characters. Confirmation of the species identity was also made by molecular analysis for some species. Seven species of the genus Heterodera Schmidt, 1871 and two of the genus Globodera Skarbilovic, 1959 were found. They were H. avenae Wollenweber, 1924, H. bifenestra Cooper, 1955, H. carotae Jones, 1950, H. goettingiana Liebscher, 1892, H. hordecalis Andersson, 1974, H. latipons Franklin, 1969 and H. schachtii Schmidt, G. rostochiensis (Wollenweber, 1923) Behrens, 1975 and G. pallida (Stone, 1973) Behrens, 1975. All species dectected are known to occur in Europe and the Mediterranean basin, but H. avenae, H. hordecalis, and H. latipons had not been reported from Sicily and H. bifenestra is a new report for Italy

Severe damage caused by Meloidogyne artiellia on cereals and leguminous in Sicily

The root-knot nematode Meloidogyne artiellia Franklin has been reported in various Italian regions on host plants belonging to the families Graminaceae, Leguminosae and Cruciferae, on which it is responsible for severe yield losses. It had never been detected in Sicily. In spring 2008, the nematode was found in different legume and cereal fields in the area of Caltagirone (province of Catania, Sicily). Fields infested with the nematode showed patches of stunted, chlorotic, withered and dwarfed plants. Moreover, ears of wheat were small and kernels appeared dried; finally, roots were scrubby. Infected plants were durum wheat (Triticum durum Desf.), barley (Hordeum vulgare L.), chickpea (Cicer arietinum L.), broad bean (Vicia faba L.), lentil (Lens culinaris Medik.) and vetch (Vicia sativa L.) Root observations showed brownings, small galls and mature females bearing egg masses and larvae at root bifurcations

Microendoscopic Surgery of Middle Ear and Petrous Bone: Benefits Analysis

Objectives: Endoscopy has become routinely used in middle ear surgery. The aim of this study is to analyze where this tool may complement the traditional microscopic approach. This is a retrospective study done in single tertiary hospital. Methods: We reviewed 342 middle ear/petrous bone surgical procedures performed between 2005 and 2015. Only cases in which both microscopic and endoscope-assisted techniques were used have been included. Sixty-six patients received this double-technique surgery: 51 (77.2%) had middle ear/mastoid and petrous bone cholesteatomas (46 middle ear and mastoid and 5 acquired/congenital petrous bone cholesteatomas), 5 (7.5%) had glomus tympanicum tumors (GTT), 4 (6%) had an ossicular chain dislocation, 3 (4.5%) had purulent chronic otitis media, 2 (3%) had tympanosclerosis, and 1 (1.5%) had an ossicular chain malformation. Results: The endoscope was helpful to remove disease remnants not accessible by microscope in 41 (62%) of the cases; 37 (90%) were cholesteatomas, 3 (7%) were GTT, and only 1 (3%) was an open tympanosclerosis. In the remaining 25 (37.8%) cases, the endoscope was useful only to visualize the cavity since the microscope had already been successful in removing the entire lesion. Conclusions: The endoscopy can add valuable information and support to the usual microscope approach alone. The consensus of a single best technique does not yet exist, but the physician should choose the best modality or combination of modalities in order to cure the patient and prevent any possible complications or recurrence of the pathology

X-ray emission from stellar jets by collision against high-density molecular clouds: an application to HH 248

We investigate the plausibility of detecting X-ray emission from a stellar jet that impacts against a dense molecular cloud. This scenario may be usual for classical T Tauri stars with jets in dense star-forming complexes. We first model the impact of a jet against a dense cloud by 2D axisymmetric hydrodynamic simulations, exploring different configurations of the ambient environment. Then, we compare our results with XMM-Newton observations of the Herbig-Haro object HH 248, where extended X-ray emission aligned with the optical knots is detected at the edge of the nearby IC 434 cloud. Our simulations show that a jet can produce plasma with temperatures up to 10 MK, consistent with production of X-ray emission, after impacting a dense cloud. We find that jets denser than the ambient medium but less dense than the cloud produce detectable X-ray emission only at the impact onto the cloud. From the exploration of the model parameter space, we constrain the physical conditions (jet density and velocity, cloud density) that reproduce well the intrinsic luminosity and emission measure of the X-ray source possibly associated with HH 248. Thus, we suggest that the extended X-ray source close to HH 248 corresponds to the jet impacting on a dense cloud.Comment: Accepted for publication in ApJ. (12 pages, 12 figures

Control of the root-knot nematode, Meloidogyne incognita, in organic protected crops in Sicily

The effectiveness of different methods for controlling the root-knot, Meloidogyne incognita, suitable in organic farming in protected crops, was assessed in tomato during the 2009-2010 crop cycle, on sandy soil in a coastal area of southern Sicily (Italy). The treatments tested were: 60 day soil solarization alone and combined with commercial formulations of plant extracts of Quillaja saponaria Molina, Azadiractha indica Juss., Brassica carinata A. Brown, Tagetes spp., mycorrhizal fungi (Glomus spp.), or pellets and extracts of A. indica. The formulations were applied three or four times at intervals of 30 days. Non treated plots served as a control. The application of plant extracts or the mycorrhizal fungi combined with soil solarization significantly reduced the population of M. incognita in the soil and suppressed root galling on tomatoes compared to both non treated and solarized control plots. All plant derived formulations combined with soil solarization increased marketable yield. The greatest increases were obtained using A. indica or the mycorrhizal formulations in combination with soil solarization

The Niguarda MEWS, a new and refined tool to determine criticality and instability in Internal Medicine Ward and Emergency Medicine Unit

This study compares the effect of the modified early warning score (MEWS) versus a new early warning system (Niguarda MEWS) for detecting instability and criticality in hospital medical departments. A retrospective observational study was conducted in the Internal Medicine ward of Niguarda Ca' Granda Hospital in Milan between November 2013 and October 2014. MEWS and Niguarda-MEWS were gathered using: systolic blood pressure, respiratory frequency, heart rate, temperature, level of consciousness, oxygen saturation, creatinine level, hematocrit level and age. In order to determine if the patient was critical or not the MEWS criticality cut-off value chosen was 3, while in the Niguarda MEWS it was 6. The primary outcome was the correlation between the critical level of the two scores and in-hospital mortality. The secondary endpoint was the correlation between a specific disease and the two scores. In the study, 471 patients were included, using both the MEWS and the Niguarda MEWS score at admittance: 33.4% of patients turned out to be critically ill using the former, 40.98% when using the latter. Therefore, the specificity of scores was 70% for MEWS and 73% for Niguarda MEWS, the sensitivity 58% for MEWS and 63% for Niguarda MEWS, Niguarda MEWS area under the curve (AUC): 0.736, MEWS AUC: 0.670. For the secondary outcome, the new score is higher for genitourinary and respiratory diseases. Niguarda-MEWS could be an optimal tool to detect criticality and instability in order to address the patient to the right level of care