Search results for "electromagnetic [current]"
showing 10 items of 1008 documents
Spectral Transmission of the Human Corneal Layers
2021
Este artículo se encuentra disponible en la siguiente URL: https://www.mdpi.com/2077-0383/10/19/4490 Este artículo de investigación pertenece a la sección "Ophthalmology". We have assessed the spectral transmittance of the different layers of the human cornea in the ultraviolet (UV), visible, and near-infrared (IR) spectral ranges. Seventy-four corneal sample donors were included in the study. Firstly, the corneal transmittance was measured using a spectrophotometer. Then, all samples were fixed for histopathological analysis, which allowed us to measure the thickness of each corneal layer. Finally, the absorption coefficients of the corneal layers were computed by a linear model reproducin…
Study of the diurnal cycle of stressed vegetation for the improvement of fluorescence remote sensing
2006
Chlorophyll fluorescence (Chf) emission allows estimating the photosynthetic activity of vegetation - a key parameter for the carbon cycle models - in a quite direct way. However, measuring Chf is difficult because it represents a small fraction of the radiance to be measured by the sensor. This paper analyzes the relationship between the solar induced Chf emission and the photosynthetically active radiation (PAR) in plants under water stress condition. The solar induced fluorescence emission is measured at leaf level by means of three different methodologies. Firstly, an active modulated light fluorometer gives the relative fluorescence yield. Secondly, a quantitative measurement of the Ch…
Sensitivity analysis of the fraunhofer line discrimination method for the measurement of chlorophyll fluorescence using a field spectroradiometer
2007
The Fraunhofer Line Discrimination (FLD) principle is established as a good method for remote sensing of solar induced chlorophyll fluorescence. Some improvements to the method are analysed in order to determine and reduce the sources of error in the estimation of the fluorescence emission. A sensitivity analysis has been performed over simulated data generated from real diurnal cycle measurements.
The effect of ISM absorption on stellar activity measurements and its relevance for exoplanet studies
2017
Past UV and optical observations of stars hosting hot Jupiters have shown that some of these stars present an anomalously low chromospheric activity, significantly below the basal level. For WASP-13, observations have shown that the apparent lack of activity is possibly caused by absorption from the intervening ISM. Inspired by this result, we study the effect of ISM absorption on activity measurements (S and logR'$_{\rm HK}$ indices) for main-sequence late-type stars. To this end, we employ synthetic stellar photospheric spectra combined with varying amounts of chromospheric emission and ISM absorption. We present the effect of ISM absorption on activity measurements by varying several ins…
Tuning active Brownian motion with shot noise energy pulses
2009
The main aim of this work is to explore the possibility of modeling the biological energy support mediated by absorption of ATP (adenosine triphosphate) as an energetic shot noise. We develop a general model with discrete input of energy pulses and study shot-noise-driven ratchets. We consider these ratchets as prototypes of Brownian motors driven by energy-rich ATP molecules. Our model is a stochastic machine able to acquire energy from the environment and convert it into kinetic energy of motion. We present characteristic features and demonstrate the possibility of tuning these motors by adapting the mean frequency of the discrete energy inputs, which are described as a special shot noise…
Recent Probes of Standard and Non-standard Neutrino Physics With Nuclei
2019
We review standard and non-standard neutrino physics probes that are based on nuclear measurements. We pay special attention on the discussion of prospects to extract new physics at prominent rare event measurements looking for neutrino-nucleus scattering, such as the coherent elastic neutrino-nucleus scattering (CE$\nu$NS) that may involve lepton flavor violation (LFV) in neutral-currents (NC). For the latter processes several appreciably sensitive experiments are currently pursued or have been planed to operate in the near future, like the COHERENT, CONUS, CONNIE, MINER, TEXONO, RED100, vGEN, Ricochet, NUCLEUS etc. We provide a thorough discussion on phenomenological and theoretical studi…
Near-Edge X-ray Absorption Fine Structure Investigation of the Quasi-One-Dimensional Organic Conductor (TMTSF)2PF6
2016
We present high-resolution near-edge X-ray absorption fine structure (NEXAFS) measurements at the P L2/3-edges, F K-edge, C K-edge and Se M2/3-edges of the quasi-one-dimensional (1D) conductor and superconductor (TMTSF)2PF6. NEXAFS allows probing the donor and acceptor moieties separately; spectra were recorded between room temperature (RT) and 30 K at normal incidence. Spectra taken around RT were also studied as a function of the angle (θ) between the electric field of the X-ray beam and the 1D conducting direction. In contrast with a previous study of the S L2/3-edges spectra in (TMTTF)2AsF6, the Se M2/3-edges of (TMTSF)2PF6 do not exhibit a well resolved spectrum. Surprisingly, the C K-…
Macroscopic persistent currents in laser deposited YBa2Cu3O7 films
1989
We have investigated persistent currents in a superconducting YBa2Cu3O7 ring of about 1 cm diameter, which was deposited as c-axis textured film on a SrTiO3 substrate by laser ablation. The currents were registered, via their magnetic field distribution, with a small vibrating pick-up coil. At 77 K persistent currents with negligible decay over 103 s have been observed below a critical current density jc=0.9×105 A/cm2, both for a field-cooled and a zero-field-cooled sample. This demonstrates that it is possible to fabricate dissipationless devices of such films on a relatively large scale.
Status and recent developments at the polarized-electron injector of the superconducting Darmstadt electron linear accelerator S-DALINAC
2011
At the superconducting Darmstadt electron linac a 100 keV source of polarized electrons has been installed. Major components had been tested prior to installation at an offline teststand. Commissioning of the new source at the S-DALINAC will take place early in 2011. We report on the performance of the teststand, simulations, developments on the laser systems, new radio-frequency components for the S-DALINAC injector, and the status of the implementation of the source.
Spectral broadening by spatial effects in X-ray microcalorimeters with superconducting absorber and NTD-Ge thermal sensor
2004
We discuss how the sensitivity to the position of absorption of the photons can affect the spectral resolution of X-ray microcalorimeters with superconducting Sn absorber and NTD-Ge thermal sensor. Data obtained through the computer simulations are reported for microcalorimeters with different geometries and phonon transmission probabilities at the interface between the absorber and thermistor.