Search results for "RAYS"

The thin and medium filters of the EPIC camera on-board XMM-Newton: measured performance after more than 15 years of operation

2016

After more than 15 years of operation of the EPIC camera on board the XMM-Newton X-ray observatory, we have reviewed the status of its Thin and Medium filters. We have selected a set of Thin and Medium back-up filters among those still available in the EPIC consortium and have started a program to investigate their status by different laboratory measurements including: UV/VIS transmission, Raman scattering, X-Ray Photoelectron Spectroscopy, and Atomic Force Microscopy. Furthermore, we have investigated the status of the EPIC flight filters by performing an analysis of the optical loading in the PN offset maps to gauge variations in the optical and UV transmission. We both investigated repea…

ESR response of alanine films exposed to low-energy (1-40 keV) X-rays

2018

Introduction L-a-alanine has aroused considerable interest for use in radiation ESR dosimetry. In this work, we examined the energy response of alanine ESR films in the low energy X-photon energy range between 1 keV and 40 keV. Dose measurements through a reference ionization chamber and a semiconductor detection system were also performed to complement ESR measurements. Methods Commercial alanine ESR films were used. All ESR signal measurements were also done using an XBand (9.7 GHz) Bruker spectrometer. The dosimeters were irradiated at the "Livio Scarsi" Laboratory (LAX) of the University of Palermo, where X-ray beams in the 1–40 keV energy range are produced using a Seifert SN60 tube. R…

X-ray flares of the young planet host DS Tuc A

2022

Abridged. We observed the 40 Myr old star DS Tuc A with XMM-Newton and recorded two X-ray bright flares, with the second event occurring about 12 ks after the first one. Their duration from the rise to the end of the decay was of about 8-10 ks in soft X-rays (0.3-10 keV). The flares were also recorded in the band 200-300 nm with the UVM2 filter of the Optical Monitor. The duration of the flares in UV was about 3 ks. The observed delay between the peak in the UV band and in X-rays is a probe of the heating phase followed by the evaporation and increase of density and emission measure of the flaring loop. The coronal plasma temperature at the two flare peaks reached 54-55 MK. The diagnostics …

Solar UV-B radiation affects leaf quality and insect herbivory in the southern beech tree Nothofagus antarctica

2004

We examined the effects of solar ultraviolet-B (UV-B) radiation on plant-insect interactions in Tierra del Fuego (55°S), Argentina, an area strongly affected by ozone depletion because of its proximity to Antarctica. Solar UV-B under Nothofagus antarctica branches was manipulated using a polyester plastic film to attenuate UV-B (uvb-) and an Aclar film to provide near-ambient UV-B (uvb+). The plastic films were placed on both north-facing (i.e., high solar radiation in the Southern Hemisphere) and south-facing branches. Insects consumed 40% less leaf area from north- than from south-facing branches, and at least 30% less area from uvb+ branches than from uvb-branches. The reduced herbivory …

Experimental Validation of a Novel Method for Harmonic Mitigation for a Three-Phase Five-Level Cascaded H-Bridges Inverter

2019

In modern high-power electrical drives, the efficiency of the system is a crucial constraint. Moreover, the efficiency of power converters plays a fundamental role in modern applications requiring also a limited weight, such as the electric vehicles and novel more electric aircraft. The reduction of losses pushes for systems with a dc bus and a high number of dc/ac converters, widespread in the vehicle, not burdened by a too expensive data processing system. The purpose of this article is to concur to reduce losses by proposing an innovative selective harmonic mitigation method based on the identification of the working areas where the reference harmonics present lower amplitudes. In partic…

Electrical Aging Tests on Enameled Wire Exposed to Gamma Irradiation

2011

LACTATE DEHYDROGENASE ISOENZYMES IN THE NERVOUS TISSUE?V..

1965

Defining the genomic signature of totipotency and pluripotency during early human development.

2013

The genetic mechanisms governing human pre-implantation embryo development and the in vitro counterparts, human embryonic stem cells (hESCs), still remain incomplete. Previous global genome studies demonstrated that totipotent blastomeres from day-3 human embryos and pluripotent inner cell masses (ICMs) from blastocysts, display unique and differing transcriptomes. Nevertheless, comparative gene expression analysis has revealed that no significant differences exist between hESCs derived from blastomeres versus those obtained from ICMs, suggesting that pluripotent hESCs involve a new developmental progression. To understand early human stages evolution, we developed an undifferentiation netw…

Inflammatory Murine Skin Responses to UV-B Light Are Partially Dependent on Endothelin-1 and Mast Cells

2006

Endothelin (ET-1) has been shown to crucially contribute to UV-induced skin responses such as tanning. To test whether ET-1 is also involved in early cutaneous reactions to UV, we assessed ET-1 skin levels in UV-irradiated mice. In correlation with the levels of UV-induced skin inflammation, ET-1 concentrations increased substantially and continually. Moreover, blocking of ET-1 receptors (ET A ) resulted in significantly decreased cutaneous inflammation following UV irradiation. When we assessed skin responses to ET-1 injections, we observed prominent mast cell degranulation and mast cell-dependent inflammation. Since mast cells also critically contributed to UV-induced inflammation, we det…

Proof of Concept of an Irradiance Estimation System for Reconfigurable Photovoltaic Arrays

2015

In order to reduce the mismatch effect caused by non-uniform shadows in PV arrays, reconfigurable interconnections approaches have been recently proposed in the literature. These systems usually require the knowledge of the solar radiation affecting every solar module. The aim of this work is to evaluate the effectiveness of three irradiance estimation approaches in order to define which can be well suited for reconfigurable PV arrays. It is presented a real-time solar irradiance estimation device (IrradEst), implementing the three different estimation methods. The proposed system is based on mathematical models of PV modules enabling to estimate irradiation values by sensing a combination …