Search results for " Dispersion"

Effective Hamiltonians in Nonrelativistic Quantum Electrodynamics

2021

In this paper, we consider some second-order effective Hamiltonians describing the interaction of the quantum electromagnetic field with atoms or molecules in the nonrelativistic limit. Our procedure is valid only for off-energy-shell processes, specifically virtual processes such as those relevant for ground-state energy shifts and dispersion van der Waals and Casimir-Polder interactions, while on-energy-shell processes are excluded. These effective Hamiltonians allow for a considerable simplification of the calculation of radiative energy shifts, dispersion, and Casimir-Polder interactions, including in the presence of boundary conditions. They can also provide clear physical insights int…

<title>Refractive properties of separate erythrocytes of Chernobyl clean-up workers at different pH</title>

2000

This study is focused on the modifications in erythrocytes of Chernobyl nuclear power plant accident clean-up workers as a late health effect of short-term impact of high level radioactive contamination. As a result, a new method based on erythrocyte (RBC) refractive index properties at different pH has been elaborated. According to the light dispersion theory for fluids refractive index is associated with molecules mass m. This feature is widely used for estimation of cell dry mass. But there is another refractive index dependency from molecules charge q regardless of its sing. This feature is not being used for cell quantitative and qualitative characterization. In this study, RBC were in…

First simultaneous mercury and major volatiles characterization of atmospheric hydrothermal emissions at the Pisciarelli's fumarolic system (Campi Fl…

2020

Abstract Hydrothermal systems with active surface expressions are important natural source of atmospheric mercury. Here we report on the first simultaneous assessment of gaseous elemental mercury (GEM) and major volatiles (H2S and CO2) fluxes from the fumarolic system of Pisciarelli, currently the most active at the Campi Flegrei caldera (CFc), Naples (Italy). This was achieved via a GPS-synchronized Lumex and MultiGAS survey which extends similar investigations reported elsewhere. GEM concentrations measured in the fumarolic emissions were consistently above background air level close to the degassing area (mean ~ 8 ± 3 ng m−3 on average) and ranged up to 12,000 ng m−3. Our data evidenced …

Evolution of CO2, SO2, HCl, and HNO3in the volcanic plumes from Etna

2014

The volcanic plumes from degassing Etna (Italy) were extensively probed with instruments onboard the Deutsches Zentrum fur Luft- und Raumfahrt research aircraft Falcon during the contrail, volcano, and cirrus experiment CONCERT on 29/30 September 2011. Up to 10.4 ppmv SO2 and 0.3 ppmv HCl were detected with the atmospheric chemical ionization mass spectrometer AIMS at 3.1 km altitude and 20 km distance to the summit. HNO3 is the dominant reactive nitrogen component in the plumes. Linking aircraft and ground-based observations by Hybrid Single-Particle Lagrangian Integrated Trajectory dispersion modeling, we identify two crater plumes with different compositions primarily injected by the Boc…

Application and evaluation of biomagnetic and biochemical monitoring of the dispersion and deposition of volcanically-derived particles at Mt. Etna, …

2010

article i nfo Article history: Received 6 August 2009 Accepted 4 January 2010 Available online xxxx Biomagnetic monitoring, using tree leaves as passive surfaces for particle collection, has been shown to be a promising technique for assessing the dispersion and deposition of particles in the context of anthropogenic pollution. By comparing leaves' magnetic properties with trace metal levels measured in the leaves, we here assess the utility of the biomagnetic technique as a sensitive, fast and inexpensive method for assessment of volcanic plume deposition. Samples of sweet chestnut leaves (Castanea sativa) were collected from the area surrounding Mt. Etna volcano in Sicily during the 2008 …

The assessment of volcanic gas hazard by means of numerical models: An example from Vulcano Island (Sicily)

1999

Volcanic activity can inject large quantities of gases and aerosols into the atmosphere both during and between eruptions, creating a health risk for the local population. The paper describes how the volcanic gas concentration in the air can be computed by a flow model simulating the wind field over a digital terrain model of the volcano coupled with a Lagrangian particle model that uses the known (measured) gas emission rates to simulate gas dispersion. The coupling provides hazard maps for a number of meteorological conditions, introduced as boundary and initial conditions to the wind flow model, and permits the estimation of the risk both for actual and increased emission rates. An appli…

Guided Wave Techniques for Damage Detection in Composite Aerospace Structures

2018

Composite materials make up an increasing portion of today’s aerospace structures (see, e.g. Boeing 787 and Airbus 380). These aircrafts’ fuselage, for example, is composed of a laminated composite skin connected to composite stringers and C-frames. Of primary importance is the detection of damage in these built-up structures, whether caused by the manufacturing process or in service (e.g. impacts). A related issue is the characterization of the composite (visco)elastic mechanical properties, that can also be related to the quantification of potential damage. Guided elastic waves propagating in the ~100s kHz regime lend themselves to provide the necessary sensitivity to these two conditions…

CFD simulation of heavy pollutants in urban areas: the case study of Messina.

2008

Effect of short homopolymer on structure and gelation of aqueous laponite dispersions

2007

O Brasil na rota das migrações internacionais qualificadas espanholas no século XXI

2018

In order to understand recent migration, it is crucial to analyze the migratory modalities such as skilled international migration to Brazil, especially considering the ongoing transnational economic processes and their effects on the corresponding societies. Therefore, this article seeks to understand how the migratory dynamics of highly skilled Spanish professionals to the country are established taking into account the theoretical contribution of the circulation of brains and the category of knowledge workers. For this purpose, information from Brazilian?s Ministry of Labor is used on labor authorizations, financial contributions and insertion in the formal market in Spain; as well as da…