The Supernova Remnant G11.2-0.3 and its central Pulsar

The plerion inside the composite Supernova Remnant G11.2-0.3 appears to be dominated by the magnetic field to an extent unprecedented among well known cases. We discuss its evolution as determined by a central pulsar and the interaction with the surrounding thermal remnant, which in turn interacts with the ambient medium. We find that a plausible scenario exists, where all the observations can be reproduced with rather typical values for the parameters of the system; we also obtain the most likely period for the still undetected pulsar.Comment: 10 pages, to be published on ApJ Letters. Formatted using AASTe

Testing Taylor’s Law in Urban Population Dynamics Worldwide with Simultaneous Equation Models

Knowledge of long-term population trends is still incomplete at the global scale. In this perspective, human and animal ecology has intensively studied the relationship between the Mean (M) size and the Variance (V) of specific attributes of subpopulations within a given regional system. One of the best-known relationships between these two attributes suitable to describe long-term population trends is governed by Taylor’s law (TL). The present article contributes to the recent literature on population trends worldwide by testing the long-term relationship (1950–2015) between the overall variance and mean in the total population of 1857 metropolitan agglomerations in 155 countries classified into 9 world macro-regions. To estimate the unknown parameter(s) of the V–M relation we made use of a simultaneous equation system using both linear (classical TL) and quadratic specifications, with the aim of ascertaining a wide range of simplified (or more complex) association rules between the two dimensions of demographic change. The empirical results show that TL is verified in all nine cases, although a quadratic relationship provides slightly better results than the classical, linear relationship. More specifically, similar estimates for both linear and quadratic relationships were characteristic of ‘new’ demographic continents with more recent and intense urbanization processes (the Americas, and African and Asian countries). The predominance of quadratic relationships characterized regions with long-established urbanization processes, such as Europe, Russia, and, partly, China and the Middle East. The relevance of the TL for a refined understanding of urbanization mechanisms worldwide, and the importance of a quadratic term for distinguishing metropolitan systems that have experienced different development paths, were finally discussed

Original approach for thrombolytic therapy in patients with Ilio-femoral deep vein thrombosis: 2 years follow-up

Objective: The aim of the study was to discuss the results of catheter-directed thrombolysis and complementary procedures to treat acute iliofemoral deep vein thrombosis (DVT) evaluating the safety and effectivness of an easy access such as the Great Saphenous Vein. Methods and materials: A total of 22 consecutive patients with iliofemoral thrombosis and two patients with femoro-popliteal thrombosis on recent onset diagnosed with Ultrasound Doppler and contrast venography underwent intrathrombus drip infusion of urokinase while intravenous heparin was continued using saphenical access. Residual venous stenosis were treated in six patients by percutaneous balloon Angioplasty and stenting. All patients underwent routine venous duplex imaging at 30 days, 3 months, 6 months and every 6 months thereafter. Results: Complete patency of thrombosed veins was restored in 22 patients (91 %) with prompt symptomatic relief. There were no major complications in the immediate outcomes. At follow-up, two patients reported a persistant slim iliac vein stenosis, two patients had post-thrombotic syndrome, and two patients showed Deep Vein Reflux. Conclusion: Local thrombolysis using saphenical access was a safe and effective approach for the treatment of acute iliofemoral deep vein thrombosis. It seems to be a valid, easy and safe alternative, reducing the risks of haematoma and venous lesions, which can be observed when using femoral, popliteal, and trans-jugular access

Seeking the Optimal Dimension of Local Administrative Units: A Reflection on Urban Concentration and Changes in Municipal Size

In the search for a better administrative functioning as a key dimension of economic performances, changes in municipal boundaries and the creation (or suppression) of local administrative units reflect a progressive adjustment to a spatially varying population size and density. With intense population growth, municipal size reflects the overall amount (and spatial concentration) of services and infrastructures, being functionally related with agglomeration economies, land availability for building, and specific sociodemographic attributes of local communities. Based on these premises, the intrinsic relationship between settlement expansion, population growth, and municipal size in a metropolitan region of Southern Europe (Attica, hosting the Greater Athens’ area in Central Greece) was investigated in this study over nearly one century as a contribution to a refined investigation of the (changing) organization of local administrative units under a complete metropolitan cycle from urbanization to reurbanization. Based on descriptive statistics, mapping, (parametric and nonparametric) correlation coefficients, and econometric techniques, a quantitative analysis of the relationship between population size and density and municipal area provides pivotal knowledge to policy and planning adjustments toward a more balanced spatial distribution of population and administered land among local government units. Together with a slight decrease in the average municipal size over time, the average population density per municipal unit increased systematically, with a considerable reduction in spatial heterogeneity of settlements. The observed goodness-of-fit of the linear model explaining municipal area with population density, increased significantly over time. Empirical results of our study indicate that municipal size has slowly adjusted to population density across metropolitan areas, determining an imbalanced spatial distribution of resident population and a supposedly less efficient government partition. The recent administrative reform of local authorities in Greece (the so-called ‘Kallikratis’ law) seems to consolidate–rather than rebalance this organizational structure over space, reflecting spatially polarized settlements. Such conditions represent a base for informed analysis of the spatial structure of local administrative units as a pivotal element of economic sustainability and may contribute to the debate on the optimal size of municipalities at both urban and metropolitan scales of governance

Efficient high-resolution 3-D interpolation of meteorological variables for operational use

Abstract. In recent years, the use of mesoscale meteorological network data has been growing. An Optimal Interpolation (OI) method is used to interpolate on a regular grid the hourly averaged values of temperature, relative humidity, wind vector, atmospheric pressure, and hourly cumulated precipitation. For all variables, except precipitation, the background (i.e. first guess) information is obtained by detrending the observations using the geographical parameters. For precipitation, the M. Lema radar-derived best estimate of precipitation rate at the ground is used. The characteristics of the OI schemes are shown in several test cases using data from ARPA Lombardia's mesoscale meteorological network. Finally, a quantitative diagnostics for temperature and relative humidity is carried out by using Cross Validation (CV) scores computed with large sets of data

Dust in active nuclei. I. Evidence for "anomalous" properties

We present observational evidences that dust in the circumnuclear region of AGNs has different properties than in the Galactic diffuse interstellar medium. By comparing the reddening of optical and infrared broad lines and the X-ray absorbing column density we find that the E(B-V)/N_H ratio is nearly always lower than Galactic by a factor ranging from ~3 up to ~100. Other observational results indicate that the Av/N_H ratio is significantly lower than Galactic in various classes of AGNs including intermediate type 1.8-1.9 Seyferts, hard X-ray selected and radio selected quasars, broad absorption line QSOs and grism selected QSOs. The lack of prominent absorption features at 9.7um (silicates) and at 2175A (carbon dip) in the spectra of Seyfert 2s and of reddened Seyfert 1s, respectively, add further evidence for dust in the circumnuclear region of AGNs being different from Galactic. These observational results indicate that the dust composition in the circumnuclear region of AGNs could be dominated by large grains, which make the extinction curve flatter, featureless and are responsible for the reduction of the E(B-V)/N_H and Av/N_H ratios. Regardless of the physical origin of these phenomena, the reduced dust absorption with respect to what expected from the gaseous column density should warn about a mismatch between the optical and the X-ray classification of the active galactic nuclei in terms of their obscuration.Comment: 9 pages, 3 figures, accepted for publication in A&

Revealing the active galactic nucleus in the superantennae through L-band spectroscopy

We present an L-band spectrum of the Ultraluminous Infrared Galaxy IRAS 19254-7245 (the Superantennae), obtained with VLT-ISAAC. The high signal to noise ratio allows a study of the main spectral features with unprecedented detail for an extragalactic source. We argue that the main energy source in the IR is an obscured AGN. This is indicated by the low equivalent width of the 3.3 micron PAH feature, the broad absorption feature at 3.4 um, and the steep continuum at lambda>3.7 um (f_lambda ~lambda^(2.7)). The substructure of the 3.4 um absorption feature indicates that the absorption is due to hydrocarbon chains of 6-7 carbon atoms.Comment: 12 pages, 3 figures. ApJ Letters, in pres