Polarization scattering by intra-channel collisions.

We show that polarization modulated and polarization multiplexed transmission may be significantly impaired by the polarization scattering induced by intra-channel cross-phase modulation and four-wave mixing. In polarization multiplexed transmission, channel interleaving may be used to mitigate the effect when two-pulse collisions are dominant

Bandwidth measurements and capacity exploitation in Gigabit Passive Optical Networks2014 Fotonica AEIT Italian Conference on Photonics Technologies

We report an experimental investigation on the measurement of the available bandwidth for users in Gigabit Passive Optical Networks (GPON) and the limitations caused by the Internet protocols. We point out that the huge capacity offered by the GPON highlights the enormous differences that can be showed among the available and actually exploitable bandwidth in the case of TCP. In this ultrabroadband environment we also investigated on use of the UDP and of the multisession TCP. A correlation in terms of QoE is also reported

Intra-channel nonlinearity in differentially phase-modulated transmission

The mechanisms responsible for nonlinear impairments in single-channel phase modulated system employing differential detection are investigated. The role of dispersion precompensation is discussed. It is shown that precompensation may be designed as to minimize the in-phase components of the fluctuations thus reducing nonlinear impairments. In differential-phase-shift-keying the effect of precompensation is stronger than in differential-quadrature-phase-shift-keying. The results of an analytic theory are compared with split-step based computer simulations using realistic system parameters

Multilevel bandwidth measurements and capacity exploitation in gigabit passive optical networks

The authors report an experimental investigation on the measurement of the available bandwidth for the users in gigabit passive optical networks (GPON) and the limitations caused by the Internet protocols, and transfer control protocol (TCP) in particular. We point out that the huge capacity offered by the GPON highlights the enormous differences that can be showed among the available and actually exploitable bandwidth. In fact, while the physical layer capacity can reach value of 100 Mb/s and more, the bandwidth at disposal of the user (i.e. either throughput at transport layer or goodput at application layer) can be much lower when applications and services based on TCP protocol are considered. In the context of service level agreements (SLA) verification, we show how to simultaneously measure throughput and line capacity by offering a method to verify multilayer SLA. We also show how it is possible to better exploit the physical layer capacity by adopting multiple TCP connections avoiding the bottleneck of a single connection

Facing the Reality: Validation of Energy Saving Mechanisms on a Testbed

Two energy saving approaches, called Fixed Upper Fixed Lower (FUFL) and Dynamic Upper Fixed Lower (DUFL), switching off idle optical Gigabit Ethernet (GbE) interfaces during low traffic periods, have been implemented on a testbed. We show on a simple network scenario that energy can be saved using off-the-shelf equipment not explicitly designed for dynamic on/off operation. No packet loss is experienced in our experiments. We indicate the need for faster access to routers in order to perform the reconfiguration. This is particularly important for the more sophisticated energy saving approaches such as DUFL, since FUFL can be implemented locally

Pharmacological investigation on the anti-oxidant and anti-inflammatory activity of N-acetylcysteine in an ex vivo model of COPD exacerbation

Oxidative stress is recognized to be one of predisposing factor in the pathogenesis of COPD. The oxidant/antioxidant imbalance is significantly pronounced in patients with COPD exacerbation. N-acetylcysteine (NAC) seems to be able to reduce COPD exacerbations by modulating the oxidative stress in addition to its well-known mucolytic activity, but there are discordant findings on the actual anti-oxidant activity of NAC

Psychopathology, symptoms of attention-deficit/hyperactivity disorder, and risk factors in juvenile offenders

Background: The aim of this study was to assess the prevalence of potential environmental and psychopathological risk factors, with special focus on symptoms of attention-deficit/hyperactivity disorder (ADHD), in a sample of adolescent offenders in relation to the type of crime committed. Methods: The assessment included data collection and administration of clinical standardized scales such as the Youth Self-Report and Conners’ Adolescent Self-Report Scale. A total of 135 juvenile offenders participated in the study. In relation to the type of crime committed, we identified three groups matched for age and sex (crimes against people, property crimes, and alcohol-drug-related crimes). Results: Fifty-two percent of juvenile offenders reported educational achievement problems and 34% reported a family history of psychiatric disorders. We detected a statistically significant difference between the three groups with regard to ADHD (P=0.01) and conduct problems (P=0.034). Juvenile offenders who had committed crimes against people showed more ADHD symptoms (18%) and conduct problems (20%) than adolescents who had committed property crimes and alcohol-drug-related crimes. Sixty percent of the juvenile offenders who had committed property crimes and 54% of those who had committed alcohol-drug-related crimes showed problems in academic achievement. Conclusion: These findings suggest the need to implement specific interventions for prevention and treatment of specific criminal behavior

Executive Functions and Deafness: Results in a Group of Cochlear Implanted Children

Objects: This study aimed to evaluate the Executive Function (EF) domains in a group of profoundly deaf children treated with cochlear implant (CI) in comparison to normal hearing (NH) children. The secondary aim was to evaluate the influence exerted by the age at cochlear implant activation on EFs. Materials and Methods: 32 children were enrolled into two groups: group A of 17 CI users with a mean age of 8.78 years and group B of 15 NH subjects with a mean age of 7.99 years (SD + 2.3). All subjects were tested using the following tests: the subtests for working memory of the neuropsychological evaluation battery for the developmental age (Batteria di valutazione neuropsicologica per l’età evolutive), inhibition and control of the impulsive response—CAF, and the tower of London test. Results: No children with CIs scored within the normal range in the tests administered for the evaluation of EF domains. The same scores were significantly lower when compared with scores obtained by NH children. Children with younger age at CI activation showed better executive performances in planning, working memory (backward digit span), and cognitive flexibility (categorical fluency). Conclusion: The results of this study highlight that cochlear implantation plays a role in improving hearing and consequently influences the development of EFs in deaf children

N-Acetylcysteine protects human bronchi by modulating the release of neurokinin A in an ex vivo model of COPD exacerbation

Abstract Aims N-Acetylcysteine (NAC) reduces the risk of exacerbation of chronic obstructive pulmonary disease (COPD). Although NAC also has anti-inflammatory activity, the detailed mechanism leading to its protective role remains to be elucidated. We tested the impact of NAC against the effects of lipopolysaccharide (LPS) in an ex vivo model of COPD exacerbation, and investigated the role of neurokinin A (NKA) in this context. Main methods Isolated airways from COPD patients were incubated overnight with LPS (100 ng/ml). NAC was tested at concentrations resembling the plasma levels elicited by oral administration of NAC at 200 mg/day (very low dose), 600 mg/day (low dose) and 1.200 mg/day (high dose). Key findings NAC at high concentrations normalized the peroxidase activity, H2O2, malondialdehyde (MDA), nitric oxide, glutathione (GSH), total antioxidant capacity (TAC), and interleukin 6 (IL-6) (overall change 34.32% ± 4.22%, P  Significance This study demonstrates that, along with its well-known antioxidant activity, the protective effect of NAC against the detrimental effect of LPS is due to the modulation of NKA and IL-6 levels