Search results for "pulse"

Unravelling the Intertwined Atomic and Bulk Nature of Localised Excitons by Attosecond Spectroscopy

2021

The electro-optical properties of most semiconductors and insulators of technological interest are dominated by the presence of electron-hole quasi-particles, called excitons. The manipulation of excitons in dielectrics has recently received great attention, with possible applications in different fields including optoelectronics and photonics. Here, we apply attosecond transient reflection spectroscopy in a sequential two-foci geometry and observe sub-femtosecond dynamics of a core-level exciton in bulk MgF2 single crystals. Furthermore, we access absolute phase delays, which allow for an unambiguous comparison with theoretical calculations. Our results show that excitons surprisingly exhi…

Association of Oxidative Stress with Aortic Stiffness in Hypertensive Patients with Chronic Kidney Disease

2011

Several studies have consistently demonstrated that arterial stiffness becomes progressively worse as CKD progresses and a negative correlation of oxidative stress with renal function has been described. There is also sound experimental evidence indicating that oxidative stress is involved in atherogenesis. The contribution of oxidative stress to aortic stiffness is less clear. Aim: To analyse the relationship between plasma levels of 8-ISO-prostaglandin F2alpha (8-ISOPGF2alpha), an index of lipid peroxidation, considered a reliable biomarker of oxidative stress, and aortic stiffness in a group of hypertensive patients with chronic kidney disease. Methods: We enrolled 126 hypertensive patie…

Methylprednisolone-induced hepatotoxicity in a 16-year-old girl with multiple sclerosis.

2018

Multiple sclerosis (MS) is a chronic inflammatory disease with demyelination of the central nervous system. High-dosage corticosteroids are the first-line therapy in the acute relapsing of MS. We report a case of severe high-dose methylprednisolone-induced acute hepatitis in a patient with a new diagnosis of MS. A 16-year-old girl was admitted for urticaria, angioedema, nausea and vomiting a month later she had been diagnosed with MS and treated with high-dosage methylprednisolone. Laboratory investigations showed hepatic insufficiency with grossly elevated liver enzymes. A liver biopsy showed focal centrilobular hepatocyte necrosis with interface hepatitis. Methylprednisolone-induced hepat…

Pulsed Electro-Acoustic space charge apparatus – qualifying, testing and monitoring of insulation for HVDC cables and accessories

2022

Physical Agent Modalities in Early Osteoarthritis: A Scoping Review

2021

Early osteoarthritis (EOA) still represents a challenge for clinicians. Although there is no consensus on its definition and diagnosis, a prompt therapeutic intervention in the early stages can have a significant impact on function and quality of life. Exercise remains a core treatment for EOA; however, several physical modalities are commonly used in this population. The purpose of this paper is to investigate the role of physical agents in the treatment of EOA. A technical expert panel (TEP) of 8 medical specialists with expertise in physical agent modalities and musculoskeletal conditions performed the review following the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and …

Comparing proton momentum distributions in A = 2 and 3 nuclei via 2H 3H and 3He (e,e′p) measurements

2019

We report the first measurement of the $(e,e'p)$ reaction cross-section ratios for Helium-3 ($^3$He), Tritium ($^3$H), and Deuterium ($d$). The measurement covered a missing momentum range of $40 \le p_{miss} \le 550$ MeV$/c$, at large momentum transfer ($\langle Q^2 \rangle \approx 1.9$ (GeV$/c$)$^2$) and $x_B>1$, which minimized contributions from non quasi-elastic (QE) reaction mechanisms. The data is compared with plane-wave impulse approximation (PWIA) calculations using realistic spectral functions and momentum distributions. The measured and PWIA-calculated cross-section ratios for $^3$He$/d$ and $^3$H$/d$ extend to just above the typical nucleon Fermi-momentum ($k_F \approx 250$ …

A control strategy based on intelligent algorithm (PSO) to perform electrical stimulation systems

2017

International audience; Adjusting stimulation parameters using control strategy based on reliable mathematical model that can predict perfectly the muscle response, may improve the efficiency of Functional Electrical Stimulation (FES) systems. In the present project, we investigate the PID control tuning based on the Particle Swarm Optimization (PSO) algorithm at the first time in neuro-muscular systems for updating automatically the stimulation pulse amplitude to track a desired force profiles. In the beginning, The PSO algorithm is used to identify unknown force model parameters. Next, optimal PID gains are found by the same intelligent algorithm to improve the control system. The obtaine…

Extraction Methods of Essential Oils From Herbs and Spices

2017

International audience; This chapter describes both conventional and non‐conventional extraction methods of essential oils (EOs) from herbs and spices. Although hydrodistillation, steam distillation and solvent extraction are the most applied methods, several non‐conventional technologies have been evaluated, especially in respect to EO recovery, and a great potential has been attributed to these non‐conventional methods. For instance, ultrasound, microwave, supercritical fluid, pulsed electric fields, ohmic‐heating and microwave (MW) extraction techniques applied alone or combined with other techniques are potent tools to obtain EOs in a 'green' way from natural resources such as aromatic …

Strongly Coupled Coherent Phonons in Single-Layer MoS 2

2019

We present a transient absorption setup combining broadband detection over the visible-UV range with high temporal resolution ($\sim$20fs) which is ideally suited to trigger and detect vibrational coherences in different classes of materials. We generate and detect coherent phonons (CPs) in single layer (1L) MoS$_2$, as a representative semiconducting 1L-transition metal dichalcogenide (TMD), where the confined dynamical interaction between excitons and phonons is unexplored. The coherent oscillatory motion of the out-of-plane $A'_{1}$ phonons, triggered by the ultrashort laser pulses, dynamically modulates the excitonic resonances on a timescale of few tens fs. We observe an enhancement by…

Ultrasound bioeffects in rats: quantification of cellular damage in the fetal liver after pulsed Doppler imaging

2011

Objective To determine whether pulsed Doppler examination of the ductus venosus in rat fetuses could damage exposed tissue. Methods On gestational day 18, the livers of a mean of approximately five fetuses per mother (n = 5.14, SD = 1.6), in a cohort of 35 pregnant female rats, were exposed individually to pulsed Doppler and these were considered the 'exposed group'. The remaining fetuses in each pregnant rat (n = 5.16, SD = 2.1) formed the 'control group'. We tested for 600, 300, 60, 20, 15, 10 and 3 s of exposure of the fetal ductus venosus and the damage was evaluated measuring a cell death index of apoptotic activity at 7 h post-exposure (n = 16). In addition, subgroups of mothers were …