Romanesque and territory. The construction materials of Sardinian medieval churches: new approaches to the valorization, conservation and restoration

This paper is intended to illustrate a multidisciplinary research project devoted to the study of the constructive materials of the Romanesque churches in Sardinia during the “Giudicati” period (11th -13th centuries). The project focuses on the relationship between a selection of monuments and their territory, both from a historical-architectural perspective and from a more modern perspective addressing future restoration works. The methodologies of the traditional art-historical research (study of bibliographic, epigraphic and archival sources, formal reading of artifacts) are flanked by new technologies: digital surveys executed with a 3D laser-scanner, analyses of the materials (stones, mortars, bricks) with different instrumental methods: X-ray fluorescence (XRF) and inductively coupled mass spectrometry (ICP-MS) for chemical composition, X-ray diffractometer (XRD) to determine the alteration phases (e.g., soluble salts), optical microscopy and electronic (SEM) to study textures, mineral assemblages and microstructures, termogravimetric/differential scanning, calorimetric analysis (TG/DTA) for the composition of the binder mortars. This multidisciplinary approach allows the achieving of important results in an archaeometric context: 1) from a historical point of view, with the possible identification of ancient traffics, trade routes, sources of raw materials, construction phases, wall textures; 2) from a conservative point of view, by studying chemical and physical weathering processes of stone materials compatible for replacement in case of future restoration works. Sardinian Romanesque architectural heritage is particularly remarkable: about 200 churches of different types and sizes, with the almost exclusive use of cut stones. Bi- or poly-chromy, deriving from the use of different building materials, characterizes many of these monuments, becoming also a vehicle for political and cultural meanings. The paper will present some case studies aimed to illustrate the progress of the project and the results achieved

Practical large-scale coordinated scheduling in LTE-Advanced networks

In LTE-Advanced, the same spectrum can be re-used in neighboring cells, hence coordinated scheduling is employed to improve the overall network performance (cell throughput, fairness, and energy efficiency) by reducing inter-cell interference. In this paper, we advocate that large-scale coordination can be obtained through a layered solution: a cluster of few (i.e., three) cells is coordinated at the first level, and clusters of coordinated cells are then coordinated at a larger scale (e.g., tens of cells). We model both small-scale coordination and large-scale coordination as optimization problems, show that solving them at optimality is prohibitive, and propose two efficient heuristics that achieve good results, and yet are simple enough to be run at every Transmission Time Interval (TTI). Detailed packet-level simulations show that our layered approach outperforms the existing ones, both static and dynamic

Improving network performance via optimization-based centralized coordination of LTE-A cells

This paper shows how to improve the overall network performance (cell throughput, fairness, and energy efficiency) via centralized coordination of LTE-A cells. We first present optimization models for small-scale coordination (i.e., three cells). Then, we show that extending the same solution to a higher number of cells is generally unfeasible, due to both an unfeasible amount of reporting on the UE side, and too high computational requirements. To overcome this limitation we then propose a layered solution which i) relies on small-scale coordination at the first level (e.g., three cells at the same site), and ii) coordinates groups of coordinated cells at a higher scale (i.e., tens of cells), using optimization models, reaping the benefits of a centralized architecture. We show through packet-level simulations that our scheme brings significant benefits, in terms of fairness, throughput, and energy efficiency

Resource allocation for network-controlled device-to-device communications in LTE-Advanced

Network-controlled device-to-device (D2D) communication allows cellular users to communicate directly, i.e., without passing through the eNodeB, while the latter retains control over resource allocation. This allows the same time–frequency resources to be allocated to spatially separated D2D flows simultaneously, thus increasing the cell throughput. This paper presents a framework for: (1) selecting which communications should use the D2D mode, and when, and (2) allocating resources to D2D and non-D2D users, exploiting reuse for the former. We show that the two problems, although apparently similar, should be kept separate and solved at different timescales in order to avoid problems, such as excessive packet loss. We model both as optimization problems, and propose a heuristic solution to the second, which must be solved at millisecond timescales. Simulation results show that our framework is practically viable, it avoids the problem of packet losses, increases throughput and reduces delays

Endothelial dysfunction in hypertension: pathophysiological mechanism or marker of cardiovascular risk?

Introduction Vascular endothelial production of nitric oxide (NO) plays an important role in the modulation of vessel tone and structure, protecting the vascular wall from atherosclerosis. In pathological conditions, however, the endothelium also produces pro-atherogenic substances (mainly reactive oxygen species), which inactivate NO. The Endothelial dysfunction, induced by reduced NO availability, is known to contribute to the development and progression of vascular damage. For this reason, endothelial function has been a major focus of cardiovascular research in the last few decades. Because NO has a very short half-life and its in vivo measurement is difficult, many researchers prefer to measure its biological activity, particularly the NO-dependent vasodilation, at the level of the coronary and peripheral circulation by endothelial stimuli. The most widely used technique involves measurement of brachial artery flow-mediated dilation. This test allows non-invasive evaluation of endothelium-dependent vasodilation in the peripheral macrocirculation induced by a mechanical stimulus (increase in shear stress caused by 5 minutes of forearm ischemia). The vasodilatatory response is reduced in the presence of major cardiovascular risk factors, particularly essential hypertension. Conclusions Studies conducted mainly in high-risk patients have demonstrated that endothelial dysfunction within the coronary or peripheral circulation is predictive of cardiovascular events (independently of classical risk factors). Drug therapy can improve endothelial function by increasing the availability of NO (a possible adjunctive benefit in terms of preventing vascular damage and improving the prognosis). Future studies will establish whether the evaluation of endothelial function by non-invasive, standardized, reproducible, low-cost techniques is an important test for cardiovascular risk stratification in clinical practice

The eye and the heart

The vasculature of the eye and the heart share several common characteristics. The easily accessible vessels of the eye are therefore—to some extent—a window to the heart. There is interplay between cardiovascular functions and risk factors and the occurrence and progression of many eye diseases. In particular, arteriovenous nipping, narrowing of retinal arteries, and the dilatation of retinal veins are important signs of increased cardiovascular risk. The pressure in the dilated veins is often markedly increased due to a dysregulation of venous outflow from the eye. Besides such morphological criteria, functional alterations might be even more relevant and may play an important role in future diagnostics. Via neurovascular coupling, flickering light dilates capillaries and small arterioles, thus inducing endothelium-dependent, flow-mediated dilation of larger retinal vessels. Risk factors for arteriosclerosis, such as dyslipidaemia, diabetes, or systemic hypertension, are also risk factors for eye diseases such as retinal arterial or retinal vein occlusions, cataracts, age-related macular degeneration, and increases in intraocular pressure (IOP). Functional alterations of blood flow are particularly relevant to the eye. The primary vascular dysregulation syndrome (PVD), which often includes systemic hypotension, is associated with disturbed autoregulation of ocular blood flow (OBF). Fluctuation of IOP on a high level or blood pressure on a low level leads to instable OBF and oxygen supply and therefore to oxidative stress, which is particularly involved in the pathogenesis of glaucomatous neuropathy. Vascular dysregulation also leads to a barrier dysfunction and thereby to small retinal haemorrhage

Holt Oram syndrome: a case report and review of the literature

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Practical feasibility, scalability and effectiveness of coordinated scheduling algorithms in cellular networks towards 5G

Coordinated Scheduling (CS) is used to mitigate inter-cell interference in present (4G) and future (5G) cellular networks. We show that coordination of a cluster of nodes can be formulated as an optimization problem, i.e., placing the Resource Blocks (RB) in each node’s subframe with the least possible over-lapping with neighboring nodes. We provide a clever formulation, which allows optimal solutions to be computed in clusters of ten nodes, and algorithms that compute good suboptimal solutions for clusters of tens of nodes, fast enough for a network to respond to traffic changes in real time. This allows us to assess the relationship between the scale at which CS is performed and its benefits in terms of network energy efficiency and cell-edge user rate. Our results, obtained using realistic power, radiation and Signal-to-Interference-and-Noise-Ratio (SINR) models, show that optimal CS allows a significant protection of cell-edge users. Moreover, this goes hand-in-hand with a reduction in the num-ber of allocated RBs, which in turn allows an operator to reduce its energy consumption. Both benefits actually increase with the size of the clusters. The evaluation is carried out in both a 4G and a foreseen 5G setting, using different power models, system bandwidths and SINR-to-datarate mappings