Rearrangement procedures in regenerative multibeammobile communications satellites with frequency reuse

After a short overview on the European tendencies about a Land Mobile Satellite Service, this paper describes an advanced system architecture, based on multiple spot-beams and on-board processing, capable of providing message and voice services over a wide European coverage, including some North-Africa and Middle-East countries. A remarkable problem associated with spot-beam configurations is the requirement for flexibility in the capacity offer to the various coverage areas. This means incorporating procedures for changing the on-board modulator-to-spot associations, respecting the constraints imposed by frequency reuse. After discussing the requirements of the rearrangement procedure, an on-purpose algorithm is presented. This paper is derived from work performed on contract to the European Space Agency (ESA)

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

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

PolyGloT: A Personalized and Gamified eTutoring System

The digital age is changing the role of educators and pushing for a paradigm shift in the education system as a whole. Growing demand for general and specialized education inside and outside classrooms is at the heart of this rising trend. In modern, heterogeneous learning environments, the one-size-fits-all approach is proven to be fundamentally flawed. Individualization through adaptivity is, therefore, crucial to nurture individual potential and address accessibility needs and neurodiversity. By formalizing a learning framework that takes into account all these different aspects, we aim to define and implement an open, content-agnostic, and extensible eTutoring platform to design and consume adaptive and gamified learning experiences. Adaptive technology supplementing teaching can extend the reach of every teacher, making it possible to scale 1-1 learning experiences. There are many successful existing technologies available but they come with fixed environments that are not always suitable for the targeted audiences of the course material. This paper presents PolyGloT, a system able to help teachers to design and implement a gamified and adaptive learning paths. Through it we address some important issues including the engagement, fairness, and effectiveness of learning environments. We do not only propose an innovative platform that could foster the learning process of different disciplines, but it could also help teachers and instructors in organizing learning material in an easy-access repositoryComment: 6 pages; 5 figure

Trophic connectivity between the terrestrial and marine ecosystems of Malpelo Island, Colombia, evaluated through stable isotope analysis

Living beings inhabit heterogeneous environments, in which communities that are classified as discrete can be continuous and connected in innumerable ways. The components of food webs can cross borders between ecosystems, and as result, the structure and trophic dynamics of ecosystems can change. The goal of this study was to evaluate trophic connectivity between the terrestrial and marine ecosystems of Malpelo Island, Colombia (4º00’05.63” N; 81º36’36.41” W), based on the isotopic (δ13C and δ15N) assessment of 403 samples (107 terrestrial and 296 marine). Samples were collected in 2017–2021. δ13CTerrestrial values ranged from − 30.3‰ to − 15.0‰ and δ13CMarine ranged from − 24.0‰ to − 9.8‰; δ15NTerrestrial ranged from 3.7‰ to 21.3‰ and δ15NMarine ranged from 4.5 to 16.9‰. The mixing model (simmr package) indicated that detritusTerrestrial (δ13C = − 18.9 ± 0.30‰ SE) contributed more to the food web than C3 plants (–29.4 ± 0.22‰), and reflected high δ13CMarine content. There was high isotopic overlap (65–82%) and a high trophic connection between environments of Malpelo Island due to high similarity between isospaces. These results evidence the role of the donor habitat (marine) on the receptor habitat (terrestrial) and the role of the Nazca booby Sula granti regarding nutrient transfers between the two environments. The presence and preservation of this seabird is essential to maintain the balance of this insular ecosystem. The analysis of δ13C and δ15N tracers was useful to establish the trophic relationships between small oceanic island environments with presence of large seabird communities.Fundacion Alium PacificInstituto Andaluz de Ciencias de la Tierra (CSIC-UGR) National Geographic Society CP-059ER-1

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

Modeling the Coupled Mass‐Heat Transport in Lennard–Jones‐Like Binary Mixtures by Approach‐to‐Equilibrium Molecular Dynamics

A general theoretical framework to address the coupled heat-mass transport and predict the corresponding Soret and Dufour coefficients is presented. It is shown that by starting from microscopical definitions of heat and mass currents, conservation laws dictate the form of the differential equations governing the time evolution of the temperature and mass density profiles along the sample. The present theoretical device is finally validated using as benchmark system a two-component Lennard–Jones (LJ) liquid system, for which generalized diffusivities are estimated in different reduced temperature and density regions of phase diagram