Constellations matched to the Rayleigh fading channel

We introduce a new technique for designing signal sets matched to the Rayleigh fading channel, In particular, we look for n-dimensional (n⩾2) lattices whose structure provides nth-order diversity. Our approach is based on a geometric formulation of the design problem which in turn can be solved by using a number-geometric approach. Specifically, a suitable upper bound on the pairwise error probability makes the design problem tantamount to the determination of what is called a critical lattice of the body S={x=(x₁, ···, x_n)∈Rⁿ, |Π_i=1ⁿx_i|⩽1}. The lattices among which we search for an optimal solution are the standard embeddings in R ⁿ of the number ring of some totally real number field of degree n over Q. Simulation results confirm that this approach yields lattices with considerable coding gains     

A new approach to study the influence of the weld bead morphology on the fatigue behaviour of Ti–6Al–4V laser beam-welded butt joints

Ti–6Al–4V is an alloy increasingly used in aeronautics due to its high mechanical properties coupled with lightness. An effective technology used to manufacture titanium components with a reduced buy-to-fly ratio is laser beam welding. Previous studies showed that the key factor that rules the mechanical properties and the fatigue life of the joint is its morphology. The aims of this paper were to investigate the influence of the geometrical features of the joints (height of the top and root reinforcement, depth and radius of the underfill, and the valley–valley underfill distance) on their mechanical properties and also to conduct a finite element (FE) analysis on the real geometry of the welded joints. Ti–6Al–4V rolled sheets 3.2 mm thick were welded in butt joint configuration using a laser source and their performance was studied in terms of weld morphology, microstructure, Vickers microhardness and fatigue life. A full factorial plan, designed varying the welding speed and laser power, was carried out. The real geometry and then the joint morphology were studied through an innovative approach: for each specimen, both the total weld face and the total root surface were acquired using a confocal microscope. Finally, through these acquisitions, the clouds of points of the scanned surfaces were used in order to carry out a FE analysis capable of providing a stress concentration factor, K _t , value for each detected joint. The main results are the realization of a reliable FE model by an experimental agreement and the relationship found amongst the fatigue performances and some noticeable metallurgical and geometrical features, such as the underfill depth and the aspect ratio defined as the ratio between the maximum height of the joint and the valley–valley underfill distance.     

Linear SVM-based recognition of elementary juggling movements using correlation dimension of Euler Angles of a single arm

Recognizing the human arm movements has several applications, and it can be performed in a number of ways through the use of one or more sensor devices that the technology offers. This paper aims to exploit the exercises performed by jugglers in order to recognize the arm movements on the basis of the only information on the arm orientation provided by the Euler Angles. The proposed recognizer has two modules, i.e., a feature extractor and a classifier. The former reconstructs the dynamics of the system and estimates three correlation dimensions, each associated with a given Euler Angle. The latter is formed by a Linear Support Vector Machine. Extensive experimentations show the effectiveness of the proposed approach.

     

Self‐Assembly of TbPc2 Single‐Molecule Magnets on Surface through Multiple Hydrogen Bonding

The complexation between 2‐ureido‐4[1H]‐pyrimidinone (UPy) and 2,7‐diamido‐1,8‐naphthyridine (NaPy) is used to promote the mild chemisorption of a UPy‐functionalized terbium(III) double decker system on a silicon surface. The adopted strategy allows the single‐molecule magnet behavior of the system to be maintained unaltered on the surface.     

Minimal neural network topology optimization for aesthetic classification

Neural Computing and Applications - In this article, a minimum neural network topology in terms of units and connections (neurons and weights), making visual aesthetically categorized images, will...     

An approach to providing a user of a “social folksonomy” with recommendations of similar users and potentially interesting resources

“Social folksonomies” can be regarded as new-generation folksonomies obtained by empowering classical folksonomies with some features typical of social networks. Currently, they represent the natural evolution of traditional folksonomies since the presence of social network features in them could lead to an enormous increase of their performance. In order to efficiently and effectively handle this kind of folksonomies, new approaches appear compulsory because the simple extension of the ones operating on classical folksonomies appears incapable of fully capturing the new potentials of these entities. In this paper, we first illustrate a new approach that fully exploits the “social” features of these folksonomies to provide a user with recommendations of similar users and resources. Then, we present some experiments devoted to measure its performance. Finally, we compare it with various related ones already proposed in the literature.     

Morphology of the European sea bass (Dicentrarchus labrax) tongue

The European sea bass, a member of the Moronidae family, is a food fish, considered one of the first models for the intensive breeding in salt water. It has nowadays an important and increasing presence in the international fishing markets. Sea basses are carnivorous, feeding on little fishes and invertebrates. Considering the important role of the tongue during the intraoral transport and the swallowing of food, scarce data are present in literature about its morphology. The aim of this study was to analyze the morphology of the tongue by means of scanning electron and light microscopy. Adult sea basses were obtained from the aquarium of the Sicilian Center of Experimental Ichthyiopathology of the University of Messina. The fishes were anaesthetized with MS 222 and the heads were then quickly removed and processed for the paraffin embedding and SEM processing. Three different tongue regions could be distinguished: an apex, a body, and a root. Scanning electron and light microscopy showed the presence of numerous canine-like teeth, surrounded by taste buds and numerous fungiform and conical papillae. The teeth were curved and their tips were posteriorly oriented. The results confirm, in teleosts too, the fundamental role of the tongue in the mechanics of food ingestion. Moreover, the presence of taste buds demonstrates the interaction of food processing and taste. These data could be a potential source to identify new and better methods of nutrition in the breeding of this fish.     

Prevalence of sensitization to Cupressus sempervirens: a 4-year retrospective study

In the last few years Cupressus sempervirens has been identified as the cause of an increasing number of cases of late winter-early spring pollinosis in Mediterranean countries. We conducted a 4-year retrospective study of a large group of subjects with documented allergic respiratory disease in order to determine the prevalence, clinical significance and annual rate of sensitization to C. sempervirens pollen. Anamnestic data and skin prick tests (SPT) with common aeroallergens and C. sempervirens extract were collected from 1397 subjects (712 male and 685 female) resident in Latium, a region in central Italy, with complaints related to upper- or lower-respiratory-tract disorders or conjunctival disease. Two hundred and forty-three subjects (17.4%) showed positive results to C. sempervirens extract; 47 (19.3%) of them were monosensitized. The annual sensitization rate of SPT positivity to C. sempervirens varied from 7.2% in 1995 to 22% in 1998. All the subjects monosensitized to cypress pollen had symptoms from January through April. Our study suggests that sensitivity to C. sempervirens is responsible for respiratory symptoms in an increasing percentage of subjects. Further studies are needed to determine its frequency at the national level.     

A multilayer perceptron neural network-based approach for the identification of responsiveness to interferon therapy in multiple sclerosis patients

Multiple sclerosis is an idiopathic inflammatory disease characterized by multiple focal lesions in the white matter of the central nervous system. Multiple sclerosis patients are usually treated with interferon-β, but disease activity decrease in only 30-40% of patients. In the attempt to differentiate between responders and non-responders, we screened the main genes involved in the interferon signaling pathway for 38 single nucleotide polymorphisms (SNPs) in a multiple sclerosis Caucasian population from South Italy. We then analyzed the data using a multilayer perceptron neural network-based approach, in which we evaluated the global weight of a set of SNPs localized in different genes and their association with response to interferon therapy through a feature selection procedure (a combination of automatic relevance determination and backward elimination). The neural approach appears to be a useful tool in identifying gene polymorphisms involved in the response of patients to interferon therapy: 2 out of 5 genes were identified as containing 4 out of 38 significant single nucleotide polymorphisms, with a global accuracy of 70% in predicting responder and non-responder patients.     

Isolation and Characterization of Squamous Cell Carcinoma-Derived Stem-like Cells: Role in Tumor Formation

In human epidermis, keratinocyte stem cells (KSC) are characterized by high levels of β₁-integrin, resulting in the rapid adhesion to type IV collagen. Since epithelial tumors originate from KSC, we evaluated the features of rapidly adhering (RAD) keratinocytes derived from primary human squamous cell carcinoma of the skin (cSCC). RAD cells expressed higher levels of survivin, a KSC marker, as compared to non-rapidly adhering (NRAD) cells. Moreover, RAD cells proliferated to a greater extent and were more efficient in forming colonies than NRAD cells. RAD cells also migrated significantly better than NRAD cells. When seeded in a silicone chamber and grafted onto the back skin of NOD SCID mice, RAD cells formed tumors 2–4 fold bigger than those derived from NRAD cells. In tumors derived from RAD cells, the mitotic index was significantly higher than in those derived from NRAD cells, while Ki-67 and survivin expression were more pronounced in RAD tumors. This study suggests that SCC RAD stem cells play a critical role in the formation and development of epithelial tumors.