GaN LNAs for Robust Receiving Systems in Radar and Space Applications

In this contribution a series of integrated circuits and methodologies, purposely developed for application in microwave receiving subsystems, will be presented. The integrated circuits, realized in GaN integrated technologies by different suppliers, find their applications in telecom systems as well as in RADAR ones, mainly for space-based apparatuses. The respective performance, as well as the key design methods will be presented in the contribution for bandwidths ranging from S-Band up to K-Band

A particle model of rolling grain ripples under waves

A simple model is presented for the formation of rolling grain ripples on a flat sand bed by the oscillatory flow generated by a surface wave. An equation of motion is derived for the individual ripples, seen as "particles", on the otherwise flat bed. The model account for the initial apperance of the ripples, the subsequent coarsening of the ripples and the final equilibrium state. The model is related to physical parameters of the problem, and an analytical approximation for the equilibrium spacing of the ripples is developed. It is found that the spacing between the ripples scale with the square-root of the non-dimensional shear stress (the Shields parameter) on a flat bed. The results of the model are compared with measurements, and reasonable agreement between the model and the measurements is demonstrated.Comment: 9 pages incl. figures. Revised versio

Dynamical models for sand ripples beneath surface waves

We introduce order parameter models for describing the dynamics of sand ripple patterns under oscillatory flow. A crucial ingredient of these models is the mass transport between adjacent ripples, which we obtain from detailed numerical simulations for a range of ripple sizes. Using this mass transport function, our models predict the existence of a stable band of wavenumbers limited by secondary instabilities. Small ripples coarsen in our models and this process leads to a sharply selected final wavenumber, in agreement with experimental observations.Comment: 9 pages. Shortened version of previous submissio

A natural saline soil as a model for understanding to what extent the concentration of salt affects the distribution of microorganisms

Soils preserve and sustain life. Their health and functioning are crucial for crop production and for the maintenance of major ecosystem services. Human induced salinity is one of the main soil threats that reduces soil fertility and affect crop yields. In recent times, great attention has been paid to the general shortage of arable land and to the increasing demand for ecological restoration of areas affected by salinization processes. Despite the diffuse interest on the effects of salinization on plants\u2019 growth, and all the derived socioeconomic issues, very few studies analyzed the ecology of the microbial species in naturally saline soils and the resilience of biological fertility in these extreme habitats. Microorganisms inhabiting such environments may share a strategy, may have developed multiple adaptations for maintaining their populations, and cope eventually to extreme conditions by altruistic or cooperative behaviors for maintaining their metabolism active. The understanding and the knowledge of the composition and distribution of microbial communities in natural hypersaline soils can be interesting for ecological reasons but also to develop new restoration strategy where soil fertility was compromised by natural accidents or human mismanagement. The aim of this research was to provide specific information on saline soils in Italy, stressing mainly their distribution, the socioeconomic issues and the understanding of the characterizing ecological processes. Moreover, natural saline soils were used as a model for understanding to what extent the concentration of salt can affect some basic microbial processes. In the present study, physical, chemical and microbiological soil properties were investigated in the shallower horizons of natural salt affected soils in Sicily (Italy), where some ecological contrasting variables acted as strong drivers in fungal and bacterial spatial distribution. Furthermore, the interface between biological and geochemical components in the surface of that peculiar habitat was investigated to evaluate the organization and diversity of the phototrophic and heterotrophic microorganisms. Sixteen soil samples from A horizons were collected according to a random sampling scheme. Bacterial and archaeal communities were characterized by their 16S rDNA genes with T-RFLP method. A total of 92 genera were identified from the 16S pyrosequencing analysis suggesting that cyanobacteria and communities of sulfur bacteria might directly or indirectly promote the formation of protective envelope. Some bacterial phyla appeared spread in the whole area, whatever the salinity gradient, while other groups showed a distribution linked to very compartmentalised soil properties, such as the presence of saline crusts in the soil surface. Results show that saline soils couldn\u2019t contain just one single microbial community selected to withstand extreme osmotic phenomena, but many communities that can be variously correlated to one or more environmental parameters having great importance for the maintenance of the overall homeostasis

Slip distributions on active normal faults measured from LiDAR and field mapping of geomorphic offsets: an example from L\u2019Aquila, Italy, and implications for modelling seismic moment release

Surface slip distributions for an active normal fault in central Italy have been measured using terrestrial laser scanning (TLS), in order to assess the impact of changes in fault orientation and kinematics when modelling subsurface slip distributions that control seismic moment release. The southeastern segment of the surface trace of the Campo Felice active normal fault near the city of L\u2019Aquila was mapped and surveyed using techniques from structural geology and using TLS to define the vertical and horizontal offsets of geomorphic slopes since the last glacial maximum (15 \ub13 ka). The fault geometry and kinematics measured from 43 sites and throw/heave measurements from geomorphic offsets seen on 250 scarp profiles were analysed using a modification of the Kostrov equations to calculate the magnitudes and directions of horizontal principal strain-rates. The map trace of the studied fault is linear, except where a prominent bend has formed to link across a former left-stepping relay-zone. The dip of the fault and slip direction is constant across the bend. Throw-rates since 15 \ub13 ka decrease linearly from the fault centre to the tip, except in the location of the prominent bend where higher throw rates are recorded. Vertical coseismic offsets for two palaeoearthquake ruptures seen as fresh strips of rock at the base of the bedrock scarp also increase within the prominent bend. The principal strain-rate, calculated by combining strike, dip, slip-direction and post 15 \ub13 ka throw, decreases linearly from the fault centre towards the tip; the strain-rate does not increase across the prominent fault bend. The above shows that changes in fault strike, whilst having no effect on the principal horizontal strain-rate, can produce local maxima in throw-rates during single earthquakes that persist over the timescale of multiple earthquakes (15 \ub13 ka). Detailed geomorphological and structural investigation of active faults is therefore a critical input in order to properly define fault activity for the purpose of accurate seismic hazard assessment. We discuss the implications of modelling subsurface slip distributions for earthquake ruptures through inversion of GPS, InSAR and strong motion data using planar fault approximations, referring to recent examples on the nearby Paganica fault that ruptured in the Mw 6.3 2009 L\u2019Aquila Earthquak

Ground effects induced by the 2012 seismic sequence in Emilia: implications for seismic hazard assessment in the Po Plain

Since May 16, 2012, a seismic sequence has affected a wide portion of the Emilia Region (northern Italy), chiefly for the Modena and Ferrara Provinces. The first mainshock (Ml 5.9; focal depth, ca. 6 km) occurred on May 20, 2012, with the epicenter located a few kilometers north of Finale Emilia. A second main shock (Ml 5.8; focal depth, ca. 10 km) occurred on May 29, 2012, about 12 km west of the first earthquake, with the epicenter near Medolla. The seismic sequence has been characterized by five other Ml 655 events, and more than 2,300 aftershocks of lower magnitude, until the end July 2012. The distribution of the aftershocks identifies a WNW-ESE-trending zone ca. 40 km long that is characterized by NNE-SSW nearly pure compression, as indicated by the focal mechanisms. This report focuses on the many ground effects that were induced by this seismic sequence, as mainly cracks, liquefaction-type phenomena, and hydrological anomalies. The aim is to provide a complete representation of such effects, to: illustrate their type, size and areal distribution; identify the zones in the affected area that were most prone to the occurrence of ground effects (i.e., more susceptible to local geological instability in the case of earthquake occurrence); carry out an independent assessment of the intensities of the earthquakes through the ESI 2007 intensity scale, which is based only on coseismic effects on the natural environment

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV