Integration of Heterogeneous Networks: Protocols, Technologies, and Applications

Today, the possibility of being connected to the Internet at every time and without interruption is almost a reality. The great capabilities of new generation cellular networks and their wide coverage enable people to use the innumerable resources of the Internet, almost everywhere and in any mobility scenario. All modern mobile devices have multiple interfaces to get connected to the Internet, and (almost) all smartphone users think to know which interface is the best one to use in a specific situation. In particular, despite the great improvement of cellular networks, in certain situations, the use of an alternative network (for instance, WiFi, is to be preferred). Therefore, the selection of the best network is not straightforward. If we change perspective and we do not talk about people and their smartphones, rather about mobile machines (say vehicles) that have to stay connected in order to provide or to receive a certain service, then the matter of finding, at every time, the best network to connect to, appears a little more urgent. Furthermore, since in some situations it could be very important to have a performing connection, for example with very low delay, then it is evident that the selection of the best network is not trivial. The characteristics of the networks to use, in order to choose the best network, are different according to the application at hand. A world where machines move automatically and use the Internet just like humans seems at the moment far away, but it is rapidly approaching. Besides the problem of network selection, one could wonder why one should just use the best network, instead of using all networks available in order to get the best "sides" of all? The development of efficient methods for the integration of multiple networks is an interesting but still open research area. This thesis focuses on the interaction and integration of heterogeneous networks. Several innovative protocols, technologies, and applications developed, in order to make network integration easier for humans and automatic for machines, will be presented

Vertical handover between WiFi and UMTS networks: experimental performance analysis

In this paper, we analyze the performance of vertical handover (VHO) algorithms for seamless mobility between WiFi and UMTS networks. We focus on a no-coupling scenario, characterized by the lack of any form of cooperation between the involved players (users and network operators). In this “hostile ” scenario, the VHO operations are completely operated by the mobile terminal (MT), and the network authentication procedures are unoptimized, leading to typically long handover times. In this context, we first propose a low-complexity Received Signal Strength Indicator (RSSI)-based algorithm and, then, an improved hybrid RSSI/goodput version. We present experimental results based on the implementation of a real testbed with commercial WiFi (Guglielmo) and UMTS (Telecom Italia) Italian deployed networks. Despite the relatively long handover times experienced in our testbed, the proposed RSSI-based VHO algorithm guarantees an effective goodput increase at the MTs. Moreover, this algorithm mitigates the ping-pong phenomenon. Our results show that, by using simple MT-driven VHO mechanisms, the users can benefit from redundant and heterogeneous wireless network infrastructures. This can be done by leveraging on pre-existing commercially deployed networks, without the need for any modification of them.

Telomere length is independently associated with subclinical atherosclerosis in subjects with type 2 diabetes: a cross-sectional study

Aims: Individuals with type 2 diabetes show shorter leukocyte telomere length (LTL) compared to people without diabetes. Reduced LTL is associated with increased carotid intima-media thickness (IMT) in healthy subjects. The aim of the study is to assess whether LTL also correlates with IMT in patients with diabetes. Methods: In a cohort of 104 subjects with type 2 diabetes and atherogenic dyslipidemia, we assessed anthropometric, hemodynamic and metabolic parameters. Common carotid IMT was expressed as the maximum IMT. LTL was assessed by a specific real-time PCR reaction. Results: At univariate analysis, IMT values were positively correlated with age (p < 0.001), previous history of cardiovascular events (p < 0.005), fasting plasma glucose (p < 0.01), HbA1c (p < 0.05) and negatively correlated with LTL (p < 0.05). In a multivariate model, age (p < 0.001) and LTL (p < 0.05) were the only independent predictors of maximum IMT, with an adjusted R2 of 0.22. Conclusions: LTL is an independent predictor of subclinical atherosclerosis pointing to a role of LTL as an early marker of vascular burden and cardiovascular disease also in type 2 diabetes

Effects of TiO₂ and Co₃O₄ Nanoparticles on Circulating Angiogenic Cells

<div><p>Background and Aim</p><p>Sparse evidence suggests a possible link between exposure to airborne nanoparticles (NPs) and cardiovascular (CV) risk, perhaps through mechanisms involving oxidative stress and inflammation. We assessed the effects of TiO₂ and Co₃O₄ NPs in human circulating angiogenic cells (CACs), which take part in vascular endothelium repair/replacement.</p><p>Methods</p><p>CACs were isolated from healthy donors’ buffy coats after culturing lymphomonocytes on fibronectin-coated dishes in endothelial medium for 7 days. CACs were pre-incubated with increasing concentration of TiO₂ and Co₃O₄ (from 1 to 100 μg/ml) to test the effects of NP – characterized by Transmission Electron Microscopy – on CAC viability, apoptosis (caspase 3/7 activation), function (fibronectin adhesion assay), oxidative stress and inflammatory cytokine gene expression.</p><p>Results</p><p>Neither oxidative stress nor cell death were associated with exposure to TiO₂ NP (except at the highest concentration tested), which, however, induced a higher pro-inflammatory effect compared to Co₃O₄ NPs (p<0.01). Exposure to Co₃O₄ NPs significantly reduced cell viability (p<0.01) and increased caspase activity (p<0.01), lipid peroxidation end-products (p<0.05) and pro-inflammatory cytokine gene expression (p<0.05 or lower). Notably, CAC functional activity was impaired after exposure to both TiO₂ (p<0.05 or lower) and Co₃O₄ (p<0.01) NPs.</p><p>Conclusions</p><p>In vitro exposure to TiO₂ and Co₃O₄ NPs exerts detrimental effects on CAC viability and function, possibly mediated by accelerated apoptosis, increased oxidant stress (Co₃O₄ NPs only) and enhancement of inflammatory pathways (both TiO₂ and Co₃O₄ NPs). Such adverse effects may be relevant for a potential role of exposure to TiO₂ and Co₃O₄ NPs in enhancing CV risk in humans.</p></div

Effects of NPs on CAC inflammation.

<p>Effects of TiO₂ and Co₃O₄ NPs on IL-1β (A), TNF-α (B) and MCP-1(C) gene expression in CACs following 6h and 24h (D-F) of exposure. Data are expressed as -ΔΔCt and represent the relative gene expression of CACs cultured in the presence of NPs in relation to control, normalized for the endogenous control GAPDH. (<i>N = 7</i>; *p<0.05 vs control;** p<0.01 vs control) (IL-1β = interleukin-1β; TNF-α = tumor necrosis factor-α; MCP-1 = monocyte chemoattractant protein-1; BSA = bovine serum albumin).</p

Effects of NPs on CAC apoptosis and oxidative stress.

<p>Effect of TiO₂ and Co₃O₄ NPs on caspase 3/7 activation (A) and on oxidant stress formation (TBARS) (B) in CACs following 24 h of exposure (MDA = Malondialdehyde; NP = nanoparticle; BSA = bovine serum albumin) (*p<0.05 vs control; **p<0.01 vs control).</p

Cellular morphology.

<p>Morphology of CACs cells untreated (A) and following incubation with different concentration of TiO₂ (B) and Co₃O₄ NPs (C). (CAC = circulating angiogenic cells).</p

NP effects on CAC viability.

<p>Effect of TiO₂ and Co₃O₄ NPs in affecting CAC viability following 24 and 48h of exposure (A) function assessed by adhesion assay on fibronectin (B) in CACs following 24h of exposure (NP = nanoparticle; BSA = bovine serum albumin; SE = standard error) (*p<0.05; **p<0.01 vs control).</p