Modelling of the transient thermal field in laser surface treatment test

In order to develop adequate predictive models of the laser heat treating process in the recent past, the laser surface treatment (LST) test was proposed to relate the obtained microstructure to the known thermal cycle undergone by the material. One of the flat end surfaces of a cylindrical steel rod is exposed to a laser beam. As a consequence the material undergoes different thermal cycles and different microstructure transformations due to the heating effect of the laser beam that it propagates inside the material. The paper presents a thermal model that can be used in the LST test to predict the thermal field inside the rod exposed to the laser beam. The model describes the thermal field generated by a uniform and time-dependent heat source, and also accounts for the convection losses that are due to gas impinging on the exposed surface. The model was verified by comparing the obtained thermal field to direct measurements by thermocouples placed along the rod and to the thermal field obtained with a numerical simulation. Results were found to be in good agreement with the experimental measurements and the numerical results.     

Radio planning and coverage optimization of 3G cellular networks

Radio planning and coverage optimization are critical issues for service providers and vendors that are deploying third generation mobile networks and need to control coverage as well as the huge costs involved. Due to the peculiarities of the Code Division Multiple Access (CDMA) scheme used in 3G cellular systems like UMTS and CDMA2000, network planning cannot be based only on signal predictions, and the approach relying on classical set covering formulations adopted for second generation systems is not appropriate. In this paper we investigate mathematical programming models for supporting the decisions on where to install new base stations and how to select their configuration (antenna height and tilt, sector orientations, maximum emission power, pilot signal, etc.) so as to find a trade-off between maximizing coverage and minimizing costs. The overall model takes into account signal-quality constraints in both uplink and downlink directions, as well as the power control mechanism and the pilot signal. Since even small and simplified instances of this NP-hard problem are beyond the reach of state-of-the-art techniques for mixed integer programming, we propose a Tabu Search algorithm which provides good solutions within a reasonable computing time. Computational results obtained for realistic instances, generated according to classical propagation models, with different traffic scenarios (voice and data) are reported and discussed. Preliminary results have been presented in [5, 7, 8]. This work has been supported by the “Progetto Cofinanziato 2001–2003” of the Italian Ministry of Education, University and Scientific Research (MIUR), Optimization models and methods for telecommunication network design and management. Edoardo Amaldi received the “Diplome” in Mathematical Engineering from the Swiss Federal Institute of Technology at Lausanne (EPFL) in 1988. After one year in the Computational and Neural Systems program, California Institute of Technology, USA, he came back at EPFL where he earned the “Doctoratés Sciences” (PhD) in October 1994. He then joined the School of Operations Research and Industrial Engineering, Cornell University, USA, where he did research and taught graduate courses in mathematical programming. Since 1998 he is with the Dipartimento di Elettronica e Informazione (DEI), Politecnico di Milano, Italy, where he is currently an Associate Professor in Operations Research. His main research interests are in discrete optimization, the design and analysis of algorithms, and computational complexity with applications in telecommunications, image/signal processing, machine learning, and computational biology/finance. In 2005 he received an IBM Faculty Award for his work on the maximum feasible subsystem problem. He serves on the Program Committees of several international workshops and conferences (including the European Symposium on Algorithms, International Network Optimization Conference, International Workshop on Efficient and Experimental Algorithms–WEA) and since 2005 he is on the Steering Committee of WEA. Antonio Capone is an Associate Professor at the Dipartimento di Elettronica e Informazione of the Technical University of Milan (Politecnico di Milano). His expertise is on networking and main research activities include protocol design (MAC and routing) and performance evaluation of wireless access and multi-hop networks, traffic management and quality of service issues in IP networks, and network planning and optimization. He received the M.S. and Ph.D. degrees in electrical engineering from the Politecnico di Milano in 1994 and 1998, respectively. In 2000 he was a visiting professor at UCLA, Computer Science department. He currently serves as editor of the Wiley Journal of Wireless Communications and Mobile Computing. He served in the technical program committee of several international conferences and he is a regular reviewer of the main journals in the networking area. He is currently involved in the scientific and technical activities of several national and European research projects, and he leads several industrial projects. He is a Senior Member of the IEEE. Federico Malucelli (Ferrara, 7/4/62) got a Laurea in Computer Science and Ph.D. in Computer Science both from Universita’ di Pisa in 1988 and 1993 respectively. Since 2003 he is full professor of Operations Research at the Politecnico di Milano. In 1998–2002 he was associate professor of Operations Research at the Politecnico of Milano, and from 1992 to 1998 research associate at Pisa and Perugia Universities. He has visited several foreign universities and research laboratories, including HP Laboratories, Palo Alto (USA), Universite’ de Montreal (Canada) and Linkoping Universitet (Sweden). He has served as research unit coordinator for several nationwide MIUR and CNR research projects on optimization in telecommunications networks and transportation systems. His main research interests include: models and algorithms for combinatorial optimization problems, with applications in particular to telecommunications, transportations, logistics, and electronic circuit design. He has published more than 30 articles on international scietific journals.     

Signal Transduction of Mineralocorticoid and Angiotensin II Receptors in the Central Control of Sodium Appetite: A Narrative Review

Sodium appetite is an innate behavior occurring in response to sodium depletion that induces homeostatic responses such as the secretion of the mineralocorticoid hormone aldosterone from the zona glomerulosa of the adrenal cortex and the stimulation of the peptide hormone angiotensin II (ANG II). The synergistic action of these hormones signals to the brain the sodium appetite that represents the increased palatability for salt intake. This narrative review summarizes the main data dealing with the role of mineralocorticoid and ANG II receptors in the central control of sodium appetite. Appropriate keywords and MeSH terms were identified and searched in PubMed. References to original articles and reviews were examined, selected, and discussed. Several brain areas control sodium appetite, including the nucleus of the solitary tract, which contains aldosterone-sensitive HSD2 neurons, and the organum vasculosum lamina terminalis (OVLT) that contains ANG II-sensitive neurons. Furthermore, sodium appetite is under the control of signaling proteins such as mitogen-activated protein kinase (MAPK) and inositol 1,4,5-thriphosphate (IP3). ANG II stimulates salt intake via MAPK, while combined ANG II and aldosterone action induce sodium intake via the IP3 signaling pathway. Finally, aldosterone and ANG II stimulate OVLT neurons and suppress oxytocin secretion inhibiting the neuronal activity of the paraventricular nucleus, thus disinhibiting the OVLT activity to aldosterone and ANG II stimulation.     

Probiotics Function in Preventing Atopic Dermatitis in Children

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by relapsing eczematous injuries and severe pruritus. In the last few years, the AD prevalence has been increasing, reaching 20% in children and 10% in adults in high-income countries. Recently, the potential role of probiotics in AD prevention has generated considerable interest. As many clinical studies show, the gut microbiota is able to modulate systemic inflammatory and immune responses influencing the development of sensitization and allergy. Probiotics are used increasingly against AD. However, the molecular mechanisms underlying the probiotics mediated anti-allergic effect remain unclear and there is controversy about their efficacy. In this narrative review, we examine the actual evidence on the effect of probiotic supplementation for AD prevention in the pediatric population, discussing also the potential biological mechanisms of action in this regard.     

PD1, CTLA4 and TIGIT Expression on T and NK Cells in Granulomatous Diseases: Sarcoidosis and ANCA-Associated Vasculitis

Sarcoidosis is a granulomatous diseases affecting the lungs. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a histologically granulomatous B-mediated disorder characterized by activated T cells. The expression of immune checkpoint (IC) molecules (PD1, CTLA4, TIGIT) on T- and NK-cells negatively regulate the T-cell immune function. The present study aimed to explore the peripheral distribution of IC molecules to better elucidate their peripheral tolerance failure, which might reflect the development of diseases. Patients referred to Respiratory Diseases and Rheumatology Unit of Siena University Hospital were prospectively and consecutively enrolled. Healthy subjects were also enrolled as a control group. Multicolor flow cytometric analysis was performed to detect IC molecules in the peripheral blood of patients. Twenty-three patients were consecutively and prospectively enrolled in the study: 11 patients had an AAV diagnosis and 12 had sarcoidosis. CD4⁺PD1⁺ cells were higher in sarcoidosis and GPA than in HC (p = 0.0250 and p = 0.0253, respectively). CD56⁺CTLA4⁺ were higher in sarcoidosis than GPA, MPA and HC (p = 0.0085, p = 0.0042 and p = 0.0004, respectively). CTLA4⁺NK cells clustered for 100% of sarcoidosis patients according to decision tree analysis, while PD1⁺CD4 and CD8 cells for clustered for 100% of GPA patients. Our analyses showed substantial differences between sarcoidosis and AAV, further confirming the immunological peculiarity of this disease. Despite these advances, the pathogenesis remains incompletely understood, indicating an urgent need for further research to reveal the distinct immunological events in this process, with the hope to open up new therapeutic avenues and, if possible, to develop preventive measures.     

A Wavelet Perspective on Variational Perceptually-Inspired Color Enhancement

The issue of perceptually-inspired correction of color and contrast in digital images has been recently analyzed with the help of variational principles. These techniques allowed building a general framework in which the action of many already existing algorithms can be more easily understood and compared in terms of intensification of local contrast and control of dispersion around the average intensity value. In this paper we analyze this issue from the dual perspective of wavelet theory, showing that it is possible to build energy functionals of wavelet coefficients that lead to a multilevel perceptually-inspired color correction. By computing the Euler–Lagrange equations associated to the wavelet-based functionals we were able to find an analytical formula for the modification of wavelet detail coefficients that overcomes the problem of an ad-hoc selection based on empirical considerations. Besides these theoretical results, the wavelet perspective provides the computational advantage of generating much faster algorithms in comparison with the spatial variational framework.     

Adaptive memory in multi-model switching control of uncertain plants

This paper describes some recent results in multi-model switching control. The scheme here considered embeds a finite family of pre-designed controllers and a high-level unit which selects, at each instant of time, the candidate controller to be placed in feedback to the uncertain plant. The study considers a switching strategy where controller selection is based on windowed cost functions. The key feature of the proposed strategy is that the window (the memory) is not kept constant, but, on the contrary, is adjusted on-line, on the grounds of measured data. The potential benefits of using an adaptive memory switching strategy are discussed and illustrated through a benchmark example.     

Improving performance of iterative solvers with the AXC format using the Intel Xeon Phi

The Journal of Supercomputing - This work is focused on the application of the new AXC format in iterative algorithms on the Intel Xeon Phi coprocessor to solve linear systems by accelerating the...     

Dealing with different time granularities in formal specifications of real-time systems

The article presents a formalization of the notion of time granularity within a logical language for specifying real-time systems. It provides the specifier with the ability of dealing with different time granularities within a single specification. That is, it allows the specifier to describe the behavior and the properties of a system and its environment with respect to different time scales and to switch among them in a suitable way. The extended logical formalism is then embedded in an object oriented structure that enhances both the expressive power and the executability of the specification language. With regard to expressiveness, it enables one to subdivide a single specification of the system and its environment into different part and to provide a number of specifications of them at different levels of abstraction, each one referring to a different time granularity. With regard to executability, it allows one to verify the consistency and the adequacy of specifications at each step of their incremental development. It also suggests an enlargement of the notions of verification and validation that takes into account the stratified structure of the object oriented specifications.