Supercontinuum generation by higher-order mode excitation in a photonic crystal fiber

We describe an experiment in which a train of femtosecond pulses is coupled into a photonic crystal fiber (PCF) by means of an offset pumping technique that can selectively excite either the mode LP(01) or LP(11) or LP(21). The PCF presents a wide range of wavelengths in which the fundamental mode experiences normal dispersion, whereas LP(11) and LP(21) propagate in the anomalous dispersion regime, generating a supercontinuum based on the soliton fission mechanism. We find that the existence of a cut-off wavelength for the higher-order modes makes the spectral broadening asymmetrical. This latter effect is particularly dramatic in the case of the LP(21) mode, in which, by using a pump wavelength slightly below cut-off, the spectral broadening occurs only on the blue side of the pump wavelength. Our experimental results are successfully compared to numerical solutions of the nonlinear Schrödinger equation

First record of trace fossils from the Oxfordian Argiles rouges de Kheneg Formation (Tiaret, northwestern Algeria)

Three main facies associations FA-3 to FA occur in the Oxfordian Argiles rouges de Kheneg Formation in northwestern Algeria. They correspond respectively to the deeper part of a mixed siliciclastic-carbonate shelf, upper shoreface and offshore transition-lower offshore. The trace fossil association of the Argiles rouges de Kheneg Formation contains fifteen ichnogenera and is moderately diverse for the Upper Jurassic. The formation contains diverse and abundant deep water or dominantly deep water trace fossils (i.e. Belorhaphe, Chondrites, Helminthopsis, Nereites, Megagrapton). They indicate that a part of the formation was deposited in offshore transition to lower offshore environments.</p

Neki biološki parametri trlje blatarice Mullus barbatus L., 1758, u tuniskom zaljevu

The red mullet, Mullus barbatus L. 1758 is one of the main target species of the trawl fishing industry along the continental shelf off the Tunisian Gulf. The reproductive biology of this species has been studied based on statistical sampling conducted between February 2003 and January 2004. Length frequency distribution according to sex revealed that the females were highly represantative in the majority of size classes. Monthly variations in the gonadosomatic index (GSI) showed that males spawn from April to July, whereas the reproductive activity of the females occurs in the late spring and summer (May and July). The estimated lengths at maturity (Lm50) were 13.87 cm for males and 13.94 cm for females. According to the length-weight relationship, positive allometry was confirmed for males, females and pooled sexes.Trlja blatarica, Mullus barbatus L. 1758 je jedna od najvažnijih komercijalnih vrsta koćarskog ribarenja duž obale tuniskog zaljeva. Reprodukcija ove vrste je istraživana na ulovljenim primjercima tijekom uzorkovanja od veljače 2003. do siječnja 2004. Ustanovljena učestalost prema duljini i spolu ukazuje da su ženke rasprostranjenije i u većini u svim razredima. Mjesečna kolebanja gonadosomatskog indeksa (GSI) pokazuju da se mužjaci mrijeste od travnja do srpnja, dok su ženke reproduktivno aktivne u kasno proljeće i ljeto (svibanj, lipanj i srpanj). Duljina pri spolnoj zrelosti (Lm50) iznosila je 13.87 cm za mužjake i 13.94 cm za ženke. Prema duljinsko-masenom odnosu, pozitivna alometrija je ustanovljena za mužjake, ženke i ukupni uzorak

Full modal analysis of the Brillouin gain spectrum of an optical fiber

We present a numerical study of stimulated Brillouin scattering in optical fibers based on a full modal analysis of the acoustic and optical properties. The computation of each acoustic mode supported by the fiber structure allows us a deep and detailed investigation of the characteristics of the Brillouin gain spectrum. We focus our attention on optical fibers acting as acoustic antiwaveguides where the biggest contribution to the Brillouin response often comes from very high-order modes but it is sometimes overlooked because of computational issues. Our analysis clearly highlights their role and their dependence on the physical and geometrical structure of the fiber

BionicWavelet Based Denoising Using Source Separation

We consider the problem of speech denoising using source separation. In this study we have proposed a hybrid technique that consists in applying in the first step, the Bionic Wavelet Transform (BWT) to two different mixtures of the same speech signal with noise. This speech signal is corrupted by a Gaussian white noise with two different values of the Signal to Noise Ratio (SNR) in order to obtain those two mixtures. The second step consists in computing the entropy of each bionic wavelet coefficient and finds the two subbands having the minimal entropy. Those two subbands are used to estimate the separation matrix of the speech signal from noise by using the source separation. Our proposed technique is evaluated by comparing it to the denoising technique based on source separation in time domain

Setting an Upper-Wavelength Limit to the Supercontinuum Generated in a Photonic Crystal Fibre, Journal of Telecommunications and Information Technology, 2009, nr 1

We report about a novel kind of supercontinuum generation in a photonic crystal fibre in which the spectral broadening occurs only on the blue side of the pump wavelength. As a consequence a limit to the extent of the supercontinuum is set and thus a way for tailoring the broadened spectrum according to a peculiar application is provided. We present a theoretical explanation along with experimental data which are supported by the results of a set of numerical simulations

Disposal Behavior of Used Masks during the COVID-19 Pandemic in the Moroccan Community: Potential Environmental Impact

The spread of coronavirus disease-2019 (COVID-19) levied on the Moroccan authorities to increase their mask production capacity, which reached up to 12 million facemask units produced per day. This increase in personal protective equipment (PPE) production and consumption is an efficient tool to address the spread of COVID-19. However, this results in more plastic and microplastic debris being added into the land and marine environments, which will harm the ecosystem, wildlife, and public health. Such a situation needs deep individual behavior observation and tracking, as well as an assessment of the potential environmental impact of this new type of waste. For this reason, we assessed the Moroccan population’s behavior regarding the use and disposal of facemasks and gloves. An exploratory survey was prepared and shared via social media and email with the population of Rabat-Salé-Kénitra and Casablanca-Settat regions. Additionally, we calculated the estimated number and weight of daily and weekly PPE used and generated by the studied regions. The survey showed that 70% of the respondents threw their discarded masks and gloves in house trash or trash bins after their first use, whereas nearly 30% of respondents admitted that they did not wear masks because they did not leave their homes during the lockdown, while from the 70% of facemask users, more than five million (equivalent to 40,000 kg) of facemasks would be generated and disposed of daily by the community of these regions, which presents 35% of the total engendered facemask waste in Morocco. Accordingly, the environment impact of facemasks showed that the greenhouse gas footprint is about 640 kT CO2 eq./year for the whole of Morocco, while the energy footprint is around 60,000 GWh/year. Furthermore, an urgent multidisciplinary environmental assessment of the potential impact of PPE must be conducted among the 12 Moroccan regions. This study demonstrated the real impact of the COVID-19 PPE on human behavior and the environment and suggests a need for providing new didactic management of facemasks and gloves

Elastic anisotropy of polycrystalline Au films: Modeling and respective contributions of X-ray diffraction, nanoindentation and Brillouin light scattering

Elastic properties of non-textured and {1 1 1}-fiber-textured gold thin films were investigated experimentally by several complementary techniques, namely in situ tensile testing under X-ray diffraction (XRD), nanoindentation and Brillouin light scattering (BLS). Specimens were probed along different directions to reveal the strong effects of elastic anisotropy at the (local) grain and (global) film scales. XRD allows the investigation of both local and global anisotropies, while BLS and nanoindentation are limited to global analyses. A micromechanical model, based on the self-consistent scheme, and accounting for the actual microstructure of the films, is applied to interpret experimental data. Although different types of elastic constants can be determined with the used experimental techniques (static/dynamic, local/global), a good agreement is obtained, showing that comparison of these techniques is feasible when carried out carefully. In particular, the use of a micromechanical model to estimate the effects of the local elastic anisotropy at the film scale is unavoidable. The presented results show that XRD, BLS and nanoindentation should capture anisotropic texture effects on elastic constants measurements for materials with a Zener anisotropy index larger than 2. Conversely, the actual texture of a given specimen should be taken into account for a proper analysis of elastic constants measurements using those three experimental techniques

Deep Brain Stimulation in Moroccan Patients With Parkinson's Disease: The Experience of Neurology Department of Rabat

Introduction: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is known as a therapy of choice of advanced Parkinson's disease. The present study aimed to assess the beneficial and side effects of STN DBS in Moroccan Parkinsonian patients.Material and Methods: Thirty five patients underwent bilateral STN DBS from 2008 to 2016 in the Rabat University Hospital. Patients were assessed preoperatively and followed up for 6 to 12 months using the Unified Parkinson's Disease Rating Scale in four conditions (stimulation OFF and ON and medication OFF and ON), the levodopa-equivalent daily dose (LEDD), dyskinesia and fluctuation scores and PDQ39 scale for quality of life (QOL). Postoperative side effects were also recorded.Results: The mean age at disease onset was 42.31 ± 7.29 years [28–58] and the mean age at surgery was 54.66 ± 8.51 years [34–70]. The median disease duration was 11.95 ± 4.28 years [5–22]. Sixty-three percentage of patients were male. 11.4% of patients were tremor dominant while 45.71 showed akinetic-rigid form and 42.90 were classified as mixed phenotype. The LEDD before surgery was 1200 mg/day [800-1500]. All patients had motor fluctuations whereas non-motor fluctuations were present in 61.80% of cases. STN DBS decreased the LEDD by 51.72%, as the mean LEDD post-surgery was 450 [188-800]. The UPDRS-III was improved by 52.27%, dyskinesia score by 66.70% and motor fluctuations by 50%, whereas QOL improved by 27.12%. Post-operative side effects were hypophonia (2 cases), infection (3 cases), and pneumocephalus (2 cases).Conclusion: Our results showed that STN DBS is an effective treatment in Moroccan Parkinsonian patients leading to a major improvement of the most disabling symptoms (dyskinesia, motor fluctuation) and a better QOL