Search results for "PULSE"

Acoustic Topological Circuitry in Square and Rectangular Phononic Crystals

2021

International audience; We systematically engineer a series of square and rectangular phononic crystals to create experimental realizations of complex topological phononic circuits. The exotic topological transport observed is wholly reliant upon the underlying structure which must belong to either a square or rectangular lattice system and not to any hexagonal-based structure. The phononic system chosen consists of a periodic array of square steel bars which partitions acoustic waves in water over a broadband range of frequencies (∼0.5MHz). An ultrasonic transducer launches an acoustic pulse which propagates along a domain wall, before encountering a nodal point, from which the acoustic si…

Time-dependent screening explains the ultrafast excitonic signal rise in 2D semiconductors

2020

We calculate the time evolution of the transient reflection signal in an MoS$_2$ monolayer on a SiO$_2$/Si substrate using first-principles out-of-equilibrium real-time methods. Our simulations provide a simple and intuitive physical picture for the delayed, yet ultrafast, evolution of the signal whose rise time depends on the excess energy of the pump laser: at laser energies above the A- and B-exciton, the pump pulse excites electrons and holes far away from the K valleys in the first Brillouin zone. Electron-phonon and hole-phonon scattering lead to a gradual relaxation of the carriers towards small $\textit{Active Excitonic Regions}$ around K, enhancing the dielectric screening. The acc…

Legumes in 21st century Europe: present and future importance in agri-food systems? New challenges for reseach.

2013

Intensification of agriculture since 1950 has globally led to the decline of grain legume crops, which currently represent less than 3 % of arable crops in France and Europe. Nevertheless, legumes have several major assets (i) as plant proteins for animal feed and human food and (ii) as plants fixing atmospheric N2 and thereby saving nitrogen inputs in cropping systems, and (iii) as diversification crops. The analysis of forage and grain legume producing systems in France showed that the dominant system results in a lock-in of the different factors limiting legume insertion into the current systems. But legumes could have a major role to play in the agroecological transition towards more su…

Evaluation of biological properties of extracts obtained from marine biomass assisted by pulsed electric fields (PEF) and pressurized liquid extracti…

2022

Teniendo en cuenta el gran interés por la biodiversidad, los recursos marinos representan una fuente importante de compuestos de alto valor añadido como proteínas y péptidos bioactivos, lípidos y ácido grados vitaminas, minerales y compuestos bioactivos, etc. Los residuos y subproductos del pescado como cabeza, vísceras y piel, entre otros, se descartan o no se utilizan de manera efectiva durante el procesamiento de los alimentos, lo que resulta en un gran desperdicio de recursos, sin embargo, son una gran fuente de compuestos con alto valor añadido y que pueden tener un potencial uso considerable en las industrias alimentaria, farmacéutica, cosmética y otras, existiendo, por lo tanto, un i…

Invasive catfish in northern Italy and their impacts on waterbirds

2022

Predatory fish have occasionally been observed preying on birds, sometimes repeatedly, but few studies were able to unravel the overall significance of avian prey in fish diet and the predation impacts on bird populations. We used a control/impact study setup, using a Nature Reserve in northern Italy and a nearby control area, to determine: 1) the contribution of waterbirds to wels catfish diet in the Reserve, 2) the population density of wels catfish in the Reserve and control area and 3) the potential impacts of waterbird depredation by wels catfish on waterbird population trends. Our stable isotope Bayesian mixing model indicated that birds contributed 12.2% (5–27.9%, 50% confidence inte…

Coherent Amplification of the Short Optical Pulse in a Non-linear Birefringent Medium

2006

International audience; The propagation of the solitary waves in the resonant birefringent amplifier with linear losses is considered. The birefringent optical linear medium contains two-level atoms with the upper state degenerated over projection of angular moment. It is assumed that population of resonance levels of atoms is inverted. The steady state pulse of polarized radiation that is vectorial generalization of the known pi-pulse was analytically found. Numerical simulations demonstrate the formation dynamics solitary waves originated in birefringent amplifier.

Adiposity-Related Predictors of Vascular Aging From a Life Course Perspective : Findings From the Helsinki Birth Cohort Study

2022

A review of sustainable and intensified techniques for extraction of food and natural products

2020

International audience; This review presents innovative extraction techniques and their role in promoting sustainable ingredients forthe food, cosmetic and pharmaceutical industries. These techniques (such as microwave, ultrasound, pulseelectricfield, instant controlled pressure drop, sub- and super-criticalfluid processing, extrusion, mechano-chemistry, high pressure, and ohmic, UV and IR heating) use or produce less solvent, energy, and hazards.This review will provide the necessary theoretical background and some details about green extractiontechniques, their mechanisms, some applications, and environmental impacts. We will pay special attentionto the strategies and present them as succ…

Prepulse Inhibition and Vulnerability to Cocaine Addiction

2021

Preliminary test on a cascode switch for high-frequency applications

2020

Nowadays, an increasing electrification level is being addressed towards different sectors, such as transportation and industrial electronics. To bear that, high speed electrical machines represent a mature technology in different application fields, e.g. avionics, automotive, compressors and spindles. In order to guarantee high speed while keeping high power quality without adopting bulky filtering circuits, DC-AC converters shall be controlled by means of high Pulse Width Modulation (PWM) frequencies. In addition to the emerging switching device technologies, such as those based on Silicon-Carbide (SiC) and Gallium-Nitride (GaN), alternative circuital topologies are crucial in order to co…