Search results for "propagation"
showing 10 items of 676 documents
Discrete spectral incoherent solitons in nonlinear media with noninstantaneous response
2011
International audience; We show theoretically that nonlinear optical media characterized by a finite response time may support the existence of discrete spectral incoherent solitons. The structure of the soliton consists of three incoherent spectral bands that propagate in frequency space toward the low-frequency components in a discrete fashion and with a constant velocity. Discrete spectral incoherent solitons do not exhibit a confinement in the space-time domain, but exclusively in the frequency domain. The kinetic theory describes in detail all the essential properties of discrete spectral incoherent solitons: A quantitative agreement has been obtained between simulations of the kinetic…
Generalised bisection method for optimum ultrasonic ray tracing and focusing in multi-layered structures
2021
Ultrasonic testing has been used for many decades, proving itself very efficient for detecting defects in many industrial sectors. The desire to apply ultrasonic testing to geometrically complex structures, and to anisotropic, inhomogeneous materials, together with the advent of more powerful electronics and software, is constantly pushing the applicability of ultrasonic waves to their limits. General ray tracing models, suitable for calculating the proper incident angle of single element probes and the proper time delay of phased array, are currently required. They can support the development of new imaging techniques, as Full Matrix Capture and Total Focusing Method, and the execution of …
Stable and simple quantitative phase-contrast imaging by Fresnel biprism
2018
Digital holographic (DH) microscopy has grown into a powerful nondestructive technique for the real-time study of living cells including dynamic membrane changes and cell fluctuations in nanometer and sub-nanometer scales. The conventional DH microscopy configurations require a separately generated coherent reference wave that results in a low phase stability and a necessity to precisely adjust the intensity ratio between two overlapping beams. In this work, we present a compact, simple, and very stable common-path DH microscope, employing a self-referencing configuration. The microscope is implemented by a diode laser as the source and a Fresnel biprism for splitting and recombining the be…
Multispectral high resolution sensor fusion for smoothing and gap-filling in the cloud
2020
Remote sensing optical sensors onboard operational satellites cannot have high spectral, spatial and temporal resolutions simultaneously. In addition, clouds and aerosols can adversely affect the signal contaminating the land surface observations. We present a HIghly Scalable Temporal Adaptive Reflectance Fusion Model (HISTARFM) algorithm to combine multispectral images of different sensors to reduce noise and produce monthly gap free high resolution (30 m) observations over land. Our approach uses images from the Landsat (30 m spatial resolution and 16 day revisit cycle) and the MODIS missions, both from Terra and Aqua platforms (500 m spatial resolution and daily revisit cycle). We implem…
Observation of classically 'forbidden' electromagnetic wave propagation and implications for neutrino detection.
2018
Ongoing experimental efforts in Antarctica seek to detect ultra-high energy neutrinos by measurement of radio-frequency (RF) Askaryan radiation generated by the collision of a neutrino with an ice molecule. An array of RF antennas, deployed either in-ice or in-air, is used to infer the properties of the neutrino. To evaluate their experimental sensitivity, such experiments require a refractive index model for ray tracing radio-wave trajectories from a putative in-ice neutrino interaction point to the receiving antennas; this gives the degree of signal absorption or ray bending from source to receiver. The gradient in the density profile over the upper 200 meters of Antarctic ice, coupled wi…
Micropropagation of Sicilian cultivars with an aim to preserve genetic diversity in hazelnut (Corylus avellana L.)
2018
The use of a small number of cultivars in agriculture can lead to a loss of agrobiodiversity. Since in vitro techniques are valuable tools for conserving plant biodiversity, an efficient micropropagation protocol for four Italian hazelnut cultivars, ‘Carrello’, ‘Ghirara’, ‘Minnulara’, and ‘Panottara’, was developed. The highest axillary bud survival was obtained after decontamination with 40 min 1% sodium hypochlorite followed by 40 min 0.1% sodium merthiolate in ‘Minnulara’ and ‘Ghirara’, while the 35þ35 min treatment was the best for ‘Carrello’ and ‘Panottara’. Shoot multiplication was higher in ‘Minnulara’ and ‘Ghirara’ when 6.6 lM N6-benzyladenine was used, even if some hyperhydric shoo…
Effects of plant density and cutting-type on rooting and growth of an extensive green roof of Sedum sediforme (Jacq.) Pau in a Mediterranean environm…
2020
Abstract Species of the Sedum genus are a popular choice for green roofs as they thrive in shallow growth layers and are resilient to extreme environmental conditions; they are also easy to propagate from seed, plantlings or plant parts. The use of rooted cuttings is most widespread due to good rates of establishment. In the interest of cost reduction, the direct spreading of Sedum cuttings over the roof area, especially over large areas, has attracted attention in recent years. Considering the interest on the above method and the seeming lack of experimental data available, this study aims to further knowledge in this area. Experimental tests on direct spreading of unrooted cuttings of Sed…
In Vitro Regeneration of Capparis spinosa L. by Using a Temporary Immersion System
2019
Three caper (Capparis spinosa L.) biotypes grown on the Sicilian island of Salina (38°
In Vitro Rooting of Capparis spinosa L. as Affected by Genotype and by the Proliferation Method Adopted During the Multiplication Phase
2020
The in vitro rooting of three caper (Capparis spinosa L.) selected biotypes, grown in a commercial orchard on the Sicilian island of Salina (38°
The effects of meta-Topolin and benzyladenine on in vitro organogenesis from epicotyl cuttings of Troyer citrange (Citrus sinensis[L.] Osbeck ×Poncir…
2017
Citrus tristeza virus (CTV), worldwide considered as one of the worst disease affecting Citrus plants, produced great changes in citriculture, mainly because it made mandatory the turnover of the sensitive sour orange rootstock with virus resistant ones. Among them, Troyer citrange has become one of the most employed rootstocks, due to its CTV tolerance and to the positive characteristics induced to the scion fruit production. Unfortunately, in Italy, there is a scarcity of seed mother plants. Micropropagation can be a solution for this problem. Among the in vitro techniques allowing the production of good quality true-to-type plants, the regeneration from seedling epicotyl cuttings general…