Topological conditions for discrete symmetry breaking and phase transitions

In the framework of a recently proposed topological approach to phase transitions, some sufficient conditions ensuring the presence of the spontaneous breaking of a Z_2 symmetry and of a symmetry-breaking phase transition are introduced and discussed. A very simple model, which we refer to as the hypercubic model, is introduced and solved. The main purpose of this model is that of illustrating the content of the sufficient conditions, but it is interesting also in itself due to its simplicity. Then some mean-field models already known in the literature are discussed in the light of the sufficient conditions introduced here

A congenital anterior urethrocutaneous fistula in a boy whose mother was exposed to ionizing radiations: a case report and literature review

Anterior congenital urethrocutaneous fistula is a rare anomaly that may present in an isolated fashion or in association with other anomalies of the genital urinary tract or anorectal malformations. A case of congenital anterior urethrocutaneous fistula nonassociated with other congenital anomalies in a 3-year-old male whose mother has been exposed to Chernobyl's nuclear fallout is described. The patient was successfully operated with no recurrence. We report a review of the literature about etiology and surgical strategy including the role of ionizing radiations. The congenital anterior urethrocutaneous fistula represents a rare malformation. The etiopathogenesis is unknown

Process integration study of tail-end Ca-Looping process for CO2capture in cement plants

In this work, the integration of Calcium looping (CaL) process into a cement plant for post-combustion CO2capture is assessed via process simulations. In the proposed scheme, the carbonator of the CaL process is used as an end-of-pipe unit to capture the CO2from the cement kiln gas. From the results obtained, it is demonstrated that CO2capture efficiencies of the order of 90% are achievable, with CaL reactors operating in conditions not far from those demonstrated for application in power plants. The integration of the tail-end CaL process results in a significant increase of the total fuel consumption (about two to three times higher) compared to the benchmark cement plant without CO2capture. On the other hand, the heat from the CaL process can be recovered by a steam cycle producing decarbonized electric power that may exceed the needs of the plant auxiliaries (including the ASU and the CO2compression and purification unit), exporting in this way electricity to the grid and so resulting in CO2emission credits from a life cycle perspective. The resulting specific primary energy consumption for CO2avoided (SPECCA) highly depends on the reference power generation technology considered, and it ranges between 2.7 and 3.7 MJLHV/kgCO2in a coal-fired power generation scenario. As for the retrofittability of existing cement plants, the operation of the suspension preheating tower after the implementation of the CaL unit, as well as the position of the CaL carbonator with respect to the raw mill, have been assessed. Based on the results obtained, no critical issues have been found from a technical point of view in the adoption of the tail-end CaL process in existing cement kilns

Urgent need for preservation of grapevine (Vitis vinifera L. subsp. vinifera) germplasm from small circum-Sicilian islands as revealed by SSR markers and traditional use investigations

Since the last decades grapevine germplasm is undergoing a process of rapid genetic erosion. This process is of particular concern in minor circum-Sicilian islands, because of the sharp reduction of the cultivated surfaces and the shift of their economy from agriculture to tourism. Aiming at valorising and preserving the surviving varieties we collected 185 accessions during several surveys since 2007. Six nuclear microsatellite markers were used for germplasm characterization, yielding 75 different genetic profiles. We found out that most genetic profiles (39) were not listed in national and international grapevine databases, confirming that the Sicilian minor islands represent underexplored hotspots of genetic diversity for grapevine. We also identified several synonymies, often due to geographic isolation, having 20 varieties at least two names. Conversely, 18 homonyms collectively indicated 34 genetically different accessions. Interviews with farmers provided information on current and past usage, and the origin and type of cultivation practices as well. The study also shows the urgent need for preservation of local grapevine germplasm, due to the disappearance of the elder caretakers of these traditional varieties. For rare germplasm preservation most part of the collected grapevine cultivars were introduced in an ex situ collection field

Automated detection of lung nodules in low-dose computed tomography

A computer-aided detection (CAD) system for the identification of pulmonary nodules in low-dose multi-detector computed-tomography (CT) images has been developed in the framework of the MAGIC-5 Italian project. One of the main goals of this project is to build a distributed database of lung CT scans in order to enable automated image analysis through a data and cpu GRID infrastructure. The basic modules of our lung-CAD system, consisting in a 3D dot-enhancement filter for nodule detection and a neural classifier for false-positive finding reduction, are described. The system was designed and tested for both internal and sub-pleural nodules. The database used in this study consists of 17 low-dose CT scans reconstructed with thin slice thickness (~300 slices/scan). The preliminary results are shown in terms of the FROC analysis reporting a good sensitivity (85% range) for both internal and sub-pleural nodules at an acceptable level of false positive findings (1-9 FP/scan); the sensitivity value remains very high (75% range) even at 1-6 FP/scanComment: 4 pages, 2 figures: Proceedings of the Computer Assisted Radiology and Surgery, 21th International Congress and Exhibition, Berlin, Volume 2, Supplement 1, June 2007, pp 357-35

The census of nuclear activity of late-type galaxies in the Virgo cluster

The first spectroscopic census of AGNs associated to late-type galaxies in the Virgo cluster is carried on by observing 213 out of a complete set of 237 galaxies more massive than M_dyn>10^{8.5} solar masses. Among them, 77 are classified as AGNs (including 21 transition objects, 47 LINERs and 9 Seyferts), and comprize 32% of the late-type galaxies in Virgo. Due to spectroscopic incompleteness at most 21 AGNs are missed in the survey, so that the fraction would increase up to 41%. Using corollary Near-IR observations, that enable us to estimate galaxies dynamical masses, it is found that AGNs are hosted exclusively in massive galaxies, i.e. M_dyn\gsim 10^{10} solar masses. Their frequency increases steeply with the dynamical mass from zero at M_dyn\approx10^{9.5} solar masses to virtually 1 at M_dyn>10^{11.5} solar masses. These frequencies are consistent with the ones of low luminosity AGNs found in the general field by the SDSS. Massive galaxies that harbor AGNs commonly show conspicuous r-band star-like nuclear enhancements. Conversely they often, but not necessarily contain massive bulges. Few well known AGNs (e.g. M61, M100, NGC4535) are found in massive Sc galaxies with little or no bulge. The AGN fraction seems to be only marginally sensitive to galaxy environment. We infer the black hole masses using the known scaling relations of quiescent black holes. No black holes lighter than $\sim 10^6$ \msol are found active in our sample.Comment: The paper contains 13 figures and 5 tables; accepted for publication in MNRA

Four-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET

© Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 License.The eruption of the Icelandic volcano Eyjafjallaj ökull in April-May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET). Based on multi-wavelength Raman lidar systems, EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude. In this work we show the four-dimensional (4-D) distribution of the Eyjafjallajökull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April-26 May 2010). All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio) are stored in the EARLINET database available at www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at www.earlinet.org. During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the upper troposphere down to the local planetary boundary layer (PBL). After 19 April 2010, volcanic particles were detected over southern and south-eastern Europe. During the first half of May (5-15 May), material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. The last observations of the event were recorded until 25 May in Central Europe and in the Eastern Mediterranean area. The 4-D distribution of volcanic aerosol layering and optical properties on European scale reported here provides an unprecedented data set for evaluating satellite data and aerosol dispersion models for this kind of volcanic events.Peer reviewe

WHO European Childhood Obesity Surveillance Initiative: body mass index and level of overweight among 6-9-year-old children from school year 2007/2008 to school year 2009/2010

Background: The World Health Organization (WHO) Regional Office for Europe has established the Childhood Obesity Surveillance Initiative (COSI) to monitor changes in overweight in primary-school children. The aims of this paper are to present the anthropometric results of COSI Round 2 (2009/2010) and to explore changes in body mass index (BMI) and overweight among children within and across nine countries from school years 2007/2008 to 2009/2010. Methods: Using cross-sectional nationally representative samples of 6−9-year-olds, BMI, anthropometric Z-scores and overweight prevalence were derived from measured weight and height. Significant changes between rounds were assessed using variance and t-tests analyses. Results: At Round 2, the prevalence of overweight (including obesity; WHO definitions) ranged from 18% to 57% among boys and from 18% to 50% among girls; 6 − 31% of boys and 5 − 21% of girls were obese. Southern European countries had the highest overweight prevalence. Between rounds, the absolute change in mean BMI (range: from −0.4 to +0.3) and BMI-for-age Z-scores (range: from −0.21 to +0.14) varied statistically significantly across countries. The highest significant decrease in BMI-for-age Z-scores was found in countries with higher absolute BMI values and the highest significant increase in countries with lower BMI values. The highest significant decrease in overweight prevalence was observed in Italy, Portugal and Slovenia and the highest significant increase in Latvia and Norway. Conclusions: Changes in BMI and prevalence of overweight over a two-year period varied significantly among European countries. It may be that countries with higher prevalence of overweight in COSI Round 1 have implemented interventions to try to remedy this situation

Silicon Mie Resonators for Highly Directional Light Emission from monolayer MoS2

Controlling light emission from quantum emitters has important applications ranging from solid-state lighting and displays to nanoscale single-photon sources. Optical antennas have emerged as promising tools to achieve such control right at the location of the emitter, without the need for bulky, external optics. Semiconductor nanoantennas are particularly practical for this purpose because simple geometries, such as wires and spheres, support multiple, degenerate optical resonances. Here, we start by modifying Mie scattering theory developed for plane wave illumination to describe scattering of dipole emission. We then use this theory and experiments to demonstrate several pathways to achieve control over the directionality, polarization state, and spectral emission that rely on a coherent coupling of an emitting dipole to optical resonances of a Si nanowire. A forward-to-backward ratio of 20 was demonstrated for the electric dipole emission at 680 nm from a monolayer MoS2 by optically coupling it to a Si nanowire

Patterns and localized structures in bistable semiconductor resonators

We report experiments on spatial switching dynamics and steady state structures of passive nonlinear semiconductor resonators of large Fresnel number. Extended patterns and switching front dynamics are observed and investigated. Evidence of localization of structures is given.Comment: 5 pages with 9 figure