Dense wavelength-division multiplexing passive optical networks and ultra-dense wavelength-division multiplexing passive optical networks are strong candidates to future next-generation passive ...optical network stage 3 access networks in order to satisfy increasing bandwidth demand, but their deployment is still a great challenge for telecommunication operators. Time and wavelength division multiplexed PON (TWDM-PON) has already been chosen by ITU-T as one of the best architectures in brownfield contexts to allow the reuse of the optical distribution network. Our proposal exploits the advantages of TWDM in order to reach a balance between coexistence with legacy systems and gradual and cost-effective migration towards pure wavelength division multiplexed PON (WDM-PON). In order to fulfill this aim, with reference to downstream traffic enhancement, two main novelties are presented: 1) the use of a multi-pump Raman amplifier (MRA) to satisfy the future necessity of large gain bandwidth; 2) the introduction of advanced modulation techniques to increase spectral efficiency and the future number of user channels (a less than 7 GHz-wide channel bandwidth providing 10 Gb/s bitrate has been demonstrated). A coherent system has been also proposed and its main impairments have been evaluated. The MRA has been accurately optimized to minimize power consumption without compromising performances. In the upstream direction, a semiconductor optical amplifier has been considered. The performances of the proposed TWDM-PON have been predicted through numerical simulations based on a system-level commercial CAD software.
Abstract
In this work, simple semi-empirical correlations to describe the temperature and the pressure dependence of the dynamic viscosity of low GWP refrigerants, namely HydroFluoroOlefins (HFOs) ...and HydroChloroFluoroOlefins (HCFOs), in the liquid phase are presented. Firstly, the experimental liquid dynamic viscosity data available in scientific literature and databases were collected and statistically analyzed. From the data collected for low pressures, the Latini et al. (2002, 1990) correlation for the dynamic viscosity of liquid refrigerants in saturated conditions was re-fitted and constants expressly dedicated to the studied low GWP refrigerants were obtained. Then, the proposed temperature-dependent correlation was modified to represent liquid dynamic viscosity dependence on pressure. In addition, an artificial neural network was developed to predict the dependence of the liquid viscosity of the studied refrigerants on temperature and pressure. This model was trained, validated, and tested for the selected dataset. The results of the proposed correlations and the multi-layer perceptron neural network were compared with the liquid viscosity calculations provided by some of the most well-known literature correlations and REFPROP 10.0, proving the accuracy of the proposed models for engineering applications.
The use of nuclear emulsions in very large physics experiments is now possible thanks to the recent improvements in the industrial production of emulsions and to the development of fast automated ...microscopes. In this paper the hardware performances of the
European Scanning System (ESS) are described. The ESS is a very fast automatic system developed for the mass scanning of the emulsions of the OPERA experiment, which requires microscopes with scanning speeds of
∼
20
cm
2
/
h
in an emulsion volume of
44
μ
m
thickness.
BACKGROUND
Clusterin, a heterodimeric glycoprotein found at several sites in the human male reproductive tract, could be a marker of morphologically abnormal spermatozoa, while TUNEL positivity ...indicates DNA fragmentation. Metabolic disorders such as diabetes mellitus and obesity may compromise sperm quality and fertility of men; however, little evidence specifically links hypertension with the impairment of male reproductive function.
METHODS
By flow cytometric, immunofluorescence (TUNEL assay and clusterin immunolabeling) and immunohistochemical (peroxidase-streptavidin method) analyses, we have compared both clusterin- and TUNEL labeling in ejaculated spermatozoa from healthy normotensive donors and hypertensive subjects with the purpose to reveal possible differences between the two conditions.
RESULTS
Data analysis from the normotensive (n = 25) and hypertensive subjects (n = 25) demonstrate a significant correlation between high levels of clusterin immunolabeling and the presence of sperm DNA damage, which is often associated with abnormal morphology. In the normotensive subjects, a low percentage (15.3 ± 4.5) of spermatozoa positive for high levels of clusterin was detected; however, this percentage significantly increased (30.9 ± 13.0) (P < 0.01) in hypertensive subjects. Standard semen evaluations does not reveal any significant differences between the two groups of subjects, except for a reduced forward motility and lower sperm vitality in the hypertensive subjects.
CONCLUSIONS
This pilot study strongly suggests a relationship between hypertension and markers indicative of poor sperm quality. In hypertensive subjects, high levels of clusterin immunolabeling identified a consistent fraction of ejaculated spermatozoa carrying both DNA fragmentation and strong morphological alterations, which was not correlated with age or with sperm cell mortality. The alternative possibility that sperm damage observed is due to adverse effects of anti-hypertensive drugs does not find support in the literature nor in the drug data sheets. The relationship observed between hypertension and human semen represents a novel and possibly relevant information to be considered in the study of male fertility.
In the Test Cover problem we are given a hypergraph
H
=
(
V
,
E
)
with
|
V
|
=
n
,
|
E
|
=
m
, and we assume that
E
is a
test cover
, i.e. for every pair of vertices
x
i
,
x
j
, there exists an edge
...e
∈
E
such that
|
{
x
i
,
x
j
}
∩
e
|
=
1
. The objective is to find a minimum subset of
E
which is a test cover. The problem is used for identification across many areas, and is NP-complete. From a parameterized complexity standpoint, many natural parameterizations of Test Cover are either
W
1
-complete or have no polynomial kernel unless
c
o
N
P
⊆
N
P
/
p
o
l
y
, and thus are unlikely to be solveable efficiently. However, in practice the size of the edges is often bounded. In this paper we study the parameterized complexity of Test-
r
-Cover, the restriction of Test Cover in which each edge contains at most
r
≥
2
vertices. In contrast to the unbounded case, we show that the following below-bound parameterizations of Test-
r
-Cover are fixed-parameter tractable with a polynomial kernel: (1) Decide whether there exists a test cover of size
n
-
k
, and (2) decide whether there exists a test cover of size
m
-
k
, where
k
is the parameter. In addition, we prove a new lower bound
⌈
2
(
n
-
1
)
r
+
1
⌉
on the minimum size of a test cover when the size of each edge is bounded by
r
. Test-
r
-Cover parameterized above this bound is unlikely to be fixed-parameter tractable; in fact, we show that it is para-NP-complete, as it is NP-hard to decide whether an instance of Test-
r
-Cover has a test cover of size exactly
2
(
n
-
1
)
r
+
1
.
Today, telecommunication operators are facing an epochal challenge due to the need of higher reconfigurability, flexibility, and dynamicity for their networks. In the latest years, this necessity has ...been addressed by the introduction of Software-Defined Networking (SDN), mainly in the fields of data centers and core networks. The present work introduces a unified metro-access optical network architecture based on some features inspired by SDN models. The essential aim is to enable bandwidth shared among different passive optical networks (PONs) in order to achieve higher adaptability to increasingly migratory and volatile traffic patterns. Even if the present work is mainly focused on the architecture, several hints for specific implementation of the network nodes are detailed as well in order to demonstrate its feasibility. Several numerical simulations have been performed to assess the performance of the proposed solution both about physical effects and about quality of service. Bit error ratio degradation due to physical impairments has been evaluated and traffic congestion has been estimated in terms of burst loss probability and average throughput.
BACKGROUND Semen is the major vehicle for HIV-1 infection as it contains free and cell-associated virions and infected cells. However, the presence of HIV-1 in spermatozoa has been a matter of ...debate, since the sperm cell fraction may contain somatic infected cells that jeopardize the attribution of the detected virus to the spermatozoa. METHODS Spermatozoa from 12 HIV-1 seropositive subjects were purified by multilayered Percoll gradient followed by osmotic shock. Residual presence of non-seminal cells (NCS) in purified spermatozoa, was then evaluated by cytometric and molecular analysis. HIV-1 DNA was revealed by nested PCR and in situ PCR after sperm chromatin decondensation. DNA-fragmented ejaculated spermatozoa in semen of infected subjects were detected by terminal deoxynucleotidyl transferase-mediated dUDP nick-end labeling (TUNEL) analysis. RESULTS Purification procedure adopted allowed complete removal of NCS. On purified sperm cells, HIV-1 DNA was detected in 5 out of 12 subjects by nested-PCR. On crude semen of 10 out of 12 subjects, HIV-1 DNA was in situ detected in a small percentage of abnormal spermatozoa with a wide range of structural alterations. TUNEL analysis revealed an increased percentage of DNA-fragmented ejaculated spermatozoa in semen of infected subjects. CONCLUSIONS We report molecular evidence demonstrating that HIV-1 infected subjects can ejaculate small amounts of HIV-1 DNA-positive abnormal spermatozoa. Their possible role in HIV-1 sexual transmission remains to be clarified.
In recent years, architectures, devices, and components in telecommunication networks have been challenged by evolutionary and revolutionary factors which are drastically changing the traffic ...features. Most of these changes imply the need for major re-configurability and programmability not only in data-centers and core networks, but also in the metro-access segment. In a wide variety of contexts, this necessity has been addressed by the proposed introduction of the innovative paradigm of software-defined networks (SDNs). Several solutions inspired by the SDN model have been recently proposed also for metro and access networks, where the adoption of a new generation of software-defined reconfigurable integrated photonic devices is highly desirable. In this paper, we review the possible future application scenarios for software-defined metro and access networks and software-defined photonics (SDP), on the base of analytics, statistics, and surveys. This work describes the reasons underpinning the presented radical change of paradigm and summarizes the most significant solutions proposed in literature, with a specific emphasis to physical-layer reconfigurable networks and a focus on both architectures and devices.
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