Polarization modulation instability in a Manakov fiber system

The Manakov model is the simplest multicomponent model of nonlinear wave theory: It describes elementary stable soliton propagation and multisoliton solutions, and it applies to nonlinear optics, hydrodynamics, and Bose-Einstein condensates. It is also of fundamental interest as an asymptotic model in the context of the widely used wavelength-division-multiplexed optical fiber transmission systems. However, although its physical relevance was confirmed by the experimental observation of Manakov (vector) solitons in a planar waveguide in 1996, there have in fact been no quantitative experiments confirming its validity for nonlinear dynamics other than soliton formation. Here, we report experiments in optical fiber that provide evidence of passband and baseband polarization modulation instabilities in a defocusing Manakov system. In the spontaneous regime, we also reveal a unique saturation effect as the pump power increases. We anticipate that such observations may impact the application of this minimal model to describe and understand more complicated phenomena in nature, such as the formation of extreme waves in multicomponent systems

Dynamics of cascaded resonant radiations in a dispersion-varying optical fiber

International audienceWe use a dispersion-varying optical fiber to experimentally explore the dynamics of resonant radiations emitted from Raman-shifting solitons in the vicinity of the second zero-dispersion. The evolving zero-dispersion wavelength with fiber length allows to observe unprecedented processes such as a cascade of resonant radiations, the emission of multiple resonant radiations from a single soli-ton and the generation of a 500 nm continuum exclusively composed of resonant radiations. All experiments are interpreted using numerical simulations of the generalized nonlinear Schrödinger equation which are in excellent agreement

The basis for ductility evaluation in SFRC structures in MC2020: An investigation on slabs and shallow beams

The paper presents a synthesis of an extensive experimental campaign on linear and two-dimensional steel fiber reinforced concrete (SFRC) structural elements carried out to check the ductility requirements aimed at guaranteeing limit analysis approaches for the computation of ultimate load-bearing capacity of SFRC structures; special attention is devoted to the role of the degree of redundancy of the structure. In particular, full-scale shallow beams and slabs reinforced with steel fibers (with or without conventional longitudinal reinforcement) were tested in two different laboratories: the Politecnico di Milano (PoliMI) and the University of Brescia (UniBS). In this experimental campaign, two different fiber contents and fiber types were considered. The experimental investigation, carried out within the activities to support Annex L of Eurocode 2, was fundamental also for developing the design rules included in the fib Model Code 2020 and allowed to formulate conclusions regarding optimization of the mix design, ductility, and design prediction at the ultimate capacity

Realizability of Polytopes as a Low Rank Matrix Completion Problem

This article gives necessary and sufficient conditions for a relation to be the containment relation between the facets and vertices of a polytope. Also given here, are a set of matrices parameterizing the linear moduli space and another set parameterizing the projective moduli space of a combinatorial polytope

Rat models of acute inflammation: a randomized controlled study on the effects of homeopathic remedies

BACKGROUND: One of the cardinal principles of homeopathy is the "law of similarities", according to which patients can be treated by administering substances which, when tested in healthy subjects, cause symptoms that are similar to those presented by the patients themselves. Over the last few years, there has been an increase in the number of pre-clinical (in vitro and animal) studies aimed at evaluating the pharmacological activity or efficacy of some homeopathic remedies under potentially reproducible conditions. However, in addition to some contradictory results, these studies have also highlighted a series of methodological difficulties. The present study was designed to explore the possibility to test in a controlled way the effects of homeopathic remedies on two known experimental models of acute inflammation in the rat. To this aim, the study considered six different remedies indicated by homeopathic practice for this type of symptom in two experimental edema models (carrageenan- and autologous blood-induced edema), using two treatment administration routes (sub-plantar injection and oral administration). METHODS: In a first phase, the different remedies were tested in the four experimental conditions, following a single-blind (measurement) procedure. In a second phase, some of the remedies (in the same and in different dilutions) were tested by oral administration in the carrageenan-induced edema, under double-blind (treatment administration and measurement) and fully randomized conditions. Seven-hundred-twenty male Sprague Dawley rats weighing 170–180 g were used. Six homeopathic remedies (Arnica montana D4, Apis mellifica D4, D30, Atropa belladonna D4, Hamamelis virginiana D4, Lachesis D6, D30, Phosphorus D6, D30), saline and indomethacin were tested. Edema was measured using a water-based plethysmometer, before and at different times after edema induction. Data were analyzed by ANOVA and Student t test. RESULTS: In the first phase of experiments, some statistically significant effects of homeopathic remedies (Apis, Lachesis and Phosporus) were observed (the reduction in paw volume increase ranging from 10% to 28% at different times since edema induction). In the second phase of experiments, the effects of homeopathic remedies were not confirmed. On the contrary, the unblinded standard allopathic drug indomethacin exhibited its anti-inflammatory effect in both experimental phases (the reduction in paw volume increase ranging from 14% to 40% in the first phase, and from 18% to 38% in the second phase of experiments). CONCLUSION: The discrepancies between single-blind and double-blind methods in animal pharmacological research are noteworthy and should be better investigated, also in non-homeopathic research

Immediate versus delayed implant placement after anterior single tooth extraction: the timing randomized controlled clinical trial

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Immediate vs. Delayed Implant Placement after Anterior Single Tooth Extraction: The Timing Randomised Controlled Clinical Trial.

to compare need for bone augmentation, surgical complications, periodontal, radiographic, aesthetic and patient reported outcomes in subjects receiving implant placement at the time of extraction (IMI) or 12 weeks thereafter. METHODS: Subjects requiring single tooth extraction in the anterior and premolar areas were recruited in 7 private practices. Implant position and choice of platform were restoratively driven. Measurements were performed by calibrated and masked examiners. RESULTS: IMI was unfeasible in 7.5% of cases. 124 subjects were randomized. One implant was lost in the IMI group. IMI required bone augmentation in 72% of cases compared with 43.9% for delayed (P=0.01), while wound failure occurred in 26.1% and 5.3% of cases, respectively (P=0.02). At 1 year, IMI had deeper probing depths (4.1±1.2 mm vs. 3.3±1.1 mm, P<0.01). A trend for greater radiographic bone loss was observed at IMI over the initial 3-year period (Ptrend<0.01). Inadequate pink aesthetic scores were obtained in 19% of delayed and in 42% of IMI implant cases (P=0.03). No differences in patient reported outcomes were observed. CONCLUSIONS: Immediate implant placement should not be recommended when aesthetics are important, IMI should be limited to selected cases. Longer follow-up is needed to assess differences in complication rates. This article is protected by copyright. All rights reserved

Sexual Intercourse for Induction of Spontaneous Onset of Labor: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

INTRODUCTION: Sexual intercourse during pregnancy is commonly believed to trigger the onset of contractions and, therefore, labor. However, in low-risk pregnancies, there is neither association with preterm birth, premature rupture of membranes, or low birth weight, nor with spontaneous onset of labor at term. AIM: To evaluate the effectiveness of sexual intercourse for spontaneous onset of labor at term in singleton pregnancies. METHODS: The systematic search was conducted using electronic databases from inception of each database to June 2019. Review of articles also included the abstracts of all references retrieved from the search. Inclusion criteria were randomized controlled trials comparing sexual intercourse in singleton low-risk pregnancies at term with controls (either reduced number of coitus or no coitus) for spontaneous onset of labor. Estimates were pooled using random-effects meta-analysis. MAIN OUTCOME MEASURES: The primary outcome was the incidence of spontaneous onset of labor. The summary measures were reported as summary relative risk with 95% CI using the random-effects model of DerSimonian and Laird. RESULTS: Data extracted from 3 trials, including 1,483 women with singleton pregnancy at term and cephalic presentation, were analyzed. Women who were randomized in the sexual intercourse group had similar incidence of spontaneous onset of labor compared with control subjects (0.82% vs 0.80%; relative risk 1.02, 95% CI 0.98-1.07). CLINICAL IMPLICATION: Sexual intercourse should not be restricted in low-risk term pregnancies. Further studies are needed to properly evaluate the impact of orgasm, penetration, condom use, frequency of intercourse and other factors on induction of labor at term. STRENGTH & LIMITATIONS: Our study has several strengths. The three included trials had low risk of allocation bias; intention-to-treat analysis was used; this is the first meta-analysis on this issue so far. Limitations mainly depend on the design of the included studies. Firstly, compliance to the protocol relied on self-reporting by patients; in addition, not all the features of sexual intercourse could be adequately assessed (orgasm, nipple stimulation, sexual positions, etc.). CONCLUSION: In women with singleton, cephalic, low-risk pregnancies, sexual intercourse at term does not significantly increase the incidence of spontaneous onset of labor

Engineering Branch-and-Cut Algorithms for the Equicut Problem

A minimum equicut of an edge-weighted graph is a partition of the nodes of the graph into two sets of equal size such hat the sum of the weights of edges joining nodes in different partitions is minimum. We compare basic linear and semidefnite relaxations for the equicut problem, and and that linear bounds are competitive with the corresponding semidefnite ones but can be computed much faster. Motivated by an application of equicut in theoretical physics, we revisit an approach by Brunetta et al. and present an enhanced branch-and-cut algorithm. Our computational results suggest that the proposed branch-andcut algorithm has a better performance than the algorithm of Brunetta et al.. Further, it is able to solve to optimality in reasonable time several instances with more than 200 nodes from the physics application