Search results for "RAYS"
showing 10 items of 1136 documents
High Resolution X-ray Spectroscopy of Pre-Main-Sequence Stars: TWA 5 and PZ Tel
2004
We report on the analysis of high resolution X-ray spectra of two pre-main-sequence stars: TWA 5 (observed with XMM-Newton) and PZ Telescopii (observed with Chandra/HETGS). TWA 5 is a classical T Tauri star in the TW Hydrae association while PZ Tel is a rapidly rotating weak-lined T Tauri star in the beta-Pictoris moving group. For both stars we have reconstructed the emission measure distribution and derived the coronal abundances to check for possible patterns of the abundances related to the first ionization potential of the various elements. We have also derived estimates of the plasma density from the analysis of the He-like triplets. We compare the characteristics of our targets with …
Characterization of the ESR response of alanine dosimeters to low-energy (1-40 keV) X-rays
2016
The aminoacid L-a-alanine has attracted considerable interest for use in radiation ESR dosimetry and has been formally accepted as a secondary standard for high-dose (kGy) and transfer dosimetry . The accuracy of the method is quite high, largely due to the low dependence of the alanine response on various irradiation parameters (photon energies above 100 keV, dose rate, temperature, etc.). Furthermore, this system presents alinear response to dose, fairly high sensitivity, tissue equivalence, absence of fading, small dimensions, ruggedn ess, and non-destructive readout. In this work, we examined the energy dependence of alanine ESR dosimeters in the low energy X-photon energy range between…
Photovoltaic performance of amorphous silicon flexible solar modules under mechanical loading
2007
The applications of photovoltaic devices can be significantly expanded by directly integrating them into structures. Solar cells integrated into structures can help to power a variety of devices such as structural monitoring sensors and unmanned aerial vehicles (UAVs). However, little work has been reported in the literature on the performance of solar cells under deformation. Thus, a thorough investigation on the photovoltaic behavior of solar modules under mechanical loading is necessary in order to provide the optimal integration conditions for practical applications. The photovoltaic performance of commercially available amorphous silicon solar modules was tested under applied mechanica…
Nanowire Ordered Arrays for Electrochemical Sensing of H2O2
2016
Today, electrochemical sensors are considered very interesting in comparison to conventional techniques because they are very adaptable, cheap, have very low limit of detection and low detection time. The most used electrochemical technique is the amperometry . In amperometric sensors, a fixed potential is applied to the electrochemical cell, and a corresponding current, due to a reduction or oxidation reaction, is then obtained. This current it can be correlated with the bulk concentration of the detecting species (the solute) such as H2O2. Hydrogen peroxide is an essential mediator in food, pharmaceutical, clinical, industrial, and environmental analyses therefore, it is of great importan…
Efficient FPGA Implementation of a Knowledge-Based Automatic Speech Classifier
2005
Speech recognition has become common in many application domains, from dictation systems for professional practices to vocal user interfaces for people with disabilities or hands-free system control. However, so far the performance of Automatic Speech Recognition (ASR) systems are comparable to Human Speech Recognition (HSR) only under very strict working conditions, and in general far lower. Incorporating acoustic-phonetic knowledge into ASR design has been proven a viable approach to rise ASR accuracy. Manner of articulation attributes such as vowel, stop, fricative, approximant, nasal, and silence are examples of such knowledge. Neural networks have already been used successfully as dete…
Palmprint principal lines extraction
2014
The palmprint recognition has become a focus in biological recognition and image processing fields. In this process, the features extraction (with particular attention to palmprint principal line extraction) is especially important. Although a lot of work has been reported, the representation of palmprint is still an open issue. In this paper we propose a simple, efficient, and accurate palmprint principal lines extraction method. Our approach consists of six simple steps: normalization, median filtering, average filters along four prefixed directions, grayscale bottom-hat filtering, combination of bottom-hat filtering, binarization and post processing. The contribution of our work is a new…
Texture Synthesis for Digital Restoration in the Bit-Plane Representation
2007
In this paper we propose a new approach to handle the problem of restoration of grayscale textured images. The purpose is to recovery missing data of a damaged area. The key point is to decompose an image in its bit-planes, and to process bits rather than pixels. We propose two texture synthesis methods for restoration. The first one is a random generation process, based on the conditional probability of bits in the bit-planes. It is designed for images with stochastic textures. The second one is a best-matching method, running on each bit-plane, that is well suited to synthesize periodic patterns. Results are compared with a state-of-the-art restoration algorithm.
DOES STILL EXIST A CORRELATION BETWEEN X-RAYS OCCUPATIONAL EXPOSURE AND BENIGN NODULAR THYROID DISEASE?
2019
Objective: The prevalence of benign nodular thyroid disease in the general population is high, as shown by various studies, and the diagnosis is eased by the improved diagnostic capacity of the instruments used. The aim of the present study is the evaluation of occupational exposure to ionizing radiation as a possible significant risk factor in the determinism of this pathology. Method: A cross-sectional observational study in “A category” X-ray exposed workers (doctors, nurses, technicians) of the University Hospital of Palermo, compared with a sample of the general population, was carried out from June 2016 to June 2017. We evaluated data obtained from the Personal Health Records, includi…
Scritti in onore di Pellegrino Capaldo
2014
La qualità dei servizi è stata riconosciuta come un rilevante aspetto caratterizzante la performance dell’azienda pubblica, analogamente alla capacità di operare secondo criteri di efficienza e nel rispetto dei vincoli di bilancio. Sebbene sia possibile riscontrare alcuni significativi casi di adozione di politiche di customer satisfaction nelle amministrazioni pubbliche italiane, a tutt’oggi il tema presenta significative criticità, specialmente in ordine agli aspetti metodologici e agli strumenti operativi che consentano di integrare dette politiche nel sistema di programmazione e controllo delle aziende che erogano tali servizi. Il presente lavoro adotta una diversa prospettiva di analis…
Collisionless shock heating of heavy ions in SN 1987A
2019
Astrophysical shocks at all scales, from those in the heliosphere up to the cosmological shock waves, are typically "collisionless", because the thickness of their jump region is much shorter than the collisional mean free path. Across these jumps, electrons, protons, and ions are expected to be heated at different temperatures. Supernova remnants (SNRs) are ideal targets to study collisionless processes because of their bright post-shock emission and fast shocks. Although optical observations of Balmer-dominated shocks in young SNRs showed that the post-shock proton temperature is higher than the electron temperature, the actual dependence of the post-shock temperature on the particle mass…