19 CFR 360.108 - Loss of electronic licensing privileges.

Science.gov (United States)

2010-04-01

... 19 Customs Duties 3 2010-04-01 2010-04-01 false Loss of electronic licensing privileges. 360.108 Section 360.108 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE STEEL IMPORT MONITORING AND ANALYSIS SYSTEM § 360.108 Loss of electronic licensing privileges. Should Commerce determine...

Quasilinear analysis of loss-cone driven weakly relativistic electron cyclotron maser instability

International Nuclear Information System (INIS)

Ziebell, L.F.; Yoon, P.H.

1995-01-01

This paper presents a quasilinear analysis of the relativistic electron cyclotron maser instability. Two electron populations are assumed: a low-temperature background component and a more energetic loss-cone population. The dispersion relation is valid for any ratio of the energetic to cold populations, and includes thermal and relativistic effects. The quasilinear analysis is based upon an efficient kinetic moment method, in which various moment equations are derived from the particle kinetic equation. A model time-dependent loss-cone electron distribution function is assumed, which allows one to evaluate the instantaneous linear growth rate as well as the moment kinetic equations. These moment equations along with the wave kinetic equation form a fully self-consistent set of equations which governs the evolution of the particles as well as unstable waves. This set of equations is solved with physical parameters typical of the earth's auroral zone plasma. copyright 1995 American Institute of Physics

Spin-flip inelastic scattering in electron energy loss spectroscopy of a ferromagnetic metal

International Nuclear Information System (INIS)

Yin, S.; Tosatti, E.

1981-08-01

We calculate the spin polarization occuring during electron inelastic scattering from electron-hole pairs in a model ferromagnetic metal. The polarization is found to have contributions from unequal spin flip as well as non-flip energy loss rates. Our results indicate an asymmetry of the order of a few percent with parameters roughly modeling Fsub(e). The possibilities of comparison with experiments in the presence of simultaneous spin-polarizing elastic scattering are discussed. (author)

Fundamental harmonic electron cyclotron emission for hot, loss-cone type distributions

International Nuclear Information System (INIS)

Bornatici, M.; Ruffina, U.; Westerhof, E.

1988-01-01

Electron cyclotron emission (ECE) is an important diagnostic tool for the study of hot plasmas. ECE can be used not only to measure the electron temperature but also to obtain information about non-thermal characteristics of the electron distribution function. One such a nonthermal characteristic is a loss-cone anisotropy. Loss-cone anisotropy can give rise to unstable growth of electro-magnetic waves around the harmonics of the electron cyclotron resonance and to increased emissivity of electron cyclotron waves. In case of high electron temperatures, also the dispersion properties of the extraordinary (X-) mode arond the fundamental electron cyclotron resonance are changed due to loss-cone anisotropy. The consequences of these dispersion properties for the emissivity of the fundamental harmonic X-mode are analyzed for perpendicular propagation. The emissivity, is calculated for two types of distribution functions having a loss-cone anisotropy. These distribution functions are a relativistic Dory-Guest-Harris type distribution function and modified relativistic Maxwellian distribution having a loss-cone with rounded edges (author). 9 refs.; 2 figs

Optimization of the ATLAS (s)MDT readout electronics for high counting rates

Energy Technology Data Exchange (ETDEWEB)

Kortner, Oliver; Kroha, Hubert; Nowak, Sebastian; Schmidt-Sommerfeld, Korbinian [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Muenchen (Germany)

2016-07-01

In the ATLAS muon spectrometer, Monitored Drift Tube (MDT) chambers are used for precise muon track measurement. For the high background rates expected at HL-LHC, which are mainly due to neutrons and photons produced by interactions of the proton collision products in the detector and shielding, new small-diameter muon drift tube (sMDT)-chambers with half the drift tube diameter of the MDT-chambers and ten times higher rate capability have been developed. The standard MDT readout electronics uses bipolar shaping in front of a discriminator. This shaping leads to an undershoot of same charge but opposite polarity following each pulse. With count rates also the probability of having the subsequent pulse in this undershoot increases, which leads to losses in efficiency and spatial resolution. In order to decrease this effect, discrete prototype electronics including Baseline Restoration has been developed. Results of their tests and data taken with them during muon beamtime measurements at CERN's Gamma Irradiation Facility will be presented. which causes a deterioration of signal pulses by preceding background hits, leading to losses in muon efficiency and drift tube spatial resolution. In order to mitigate these so-called signal pile-up effects, new readout electronics with active baseline restoration (BLR) is under development. Discrete prototype electronics with BLR functionality has been tested in laboratory measurements and in the Gamma Irradiation Facility at CERN under high γ-irradiation rates. Results of the measurements are presented.

Chlorine loss and mass loss from polyvinylchloride and polyvinylidenchloride under the electron beam

International Nuclear Information System (INIS)

Lindberg, K.A.H.; Bertilsson, H.E.

1985-01-01

The loss of chlorine during the irradiation of PVC and PVDC in the electron microscope has been measured by the decay of the X-ray chlorine Kα signal. A number of factors affecting the measured beam damage curves have been considered and the experimental errors reduced to +- 10%. The results show that the chlorine decay curves can be best described by the sum of two exponentials, corresponding to the two different chlorine decay processes, these being: the dehydrochlorination of the polymer molecules and the dehydrochlorination of the polyene structure formed by the beam damage. The higher initial chlorine content of PVDC compared to PVC will result in a larger amount of chlorine atoms reacting with the polyene structure, which is more stable in the electron beam than the undamaged polymer. The chlorine loss, measured by X-ray analysis, has been compared to the mass loss, measured by energy loss analysis, and also with the volume changes of isolated spherical PVC particles. It has been concluded that the mass loss is almost entirely due to chlorine loss and that the residual structure has a density similar to the undamaged PVC. (author)

Direct Detection Electron Energy-Loss Spectroscopy: A Method to Push the Limits of Resolution and Sensitivity.

Science.gov (United States)

Hart, James L; Lang, Andrew C; Leff, Asher C; Longo, Paolo; Trevor, Colin; Twesten, Ray D; Taheri, Mitra L

2017-08-15

In many cases, electron counting with direct detection sensors offers improved resolution, lower noise, and higher pixel density compared to conventional, indirect detection sensors for electron microscopy applications. Direct detection technology has previously been utilized, with great success, for imaging and diffraction, but potential advantages for spectroscopy remain unexplored. Here we compare the performance of a direct detection sensor operated in counting mode and an indirect detection sensor (scintillator/fiber-optic/CCD) for electron energy-loss spectroscopy. Clear improvements in measured detective quantum efficiency and combined energy resolution/energy field-of-view are offered by counting mode direct detection, showing promise for efficient spectrum imaging, low-dose mapping of beam-sensitive specimens, trace element analysis, and time-resolved spectroscopy. Despite the limited counting rate imposed by the readout electronics, we show that both core-loss and low-loss spectral acquisition are practical. These developments will benefit biologists, chemists, physicists, and materials scientists alike.

Sawtooth-induced loss of runaway electrons in tokamaks

International Nuclear Information System (INIS)

Yan Longwen; Shi Bingren; Jiao Yiming

2001-01-01

A model based on banana orbit loss has been proposed to explain the sawtooth effect on the loss of the runaway electrons in tokamaks. Circulating runaway electrons can be transferred into the trapped ones due to magnetic perturbation during sawtooth crashes, then they are repelled to the limiter via toroidal precession drift with a time delay. This model may also clarify the hard X-ray oscillations correlated with the m = 2 mode and the hard X-ray bursts during outer disruptions

Antiscreening mode of projectile-electron loss

International Nuclear Information System (INIS)

Montanari, C.C.; Miraglia, J.E.; Arista, N.R.

2003-01-01

The inelastic contribution of target electrons to different electronic processes in the projectile is obtained by employing the local-density approximation as usually applied in the dielectric formalism. Projectile-electron-loss cross sections due to the electron-electron interaction are calculated and compared with those obtained by using atomic antiscreening theories. We also calculate ionization cross sections and stopping power for bare ions impinging on different gases. The good agreement with the experimental data and the simplicity of the local-density approximation make it an efficient method for describing inelastic processes of gaseous target electrons. It is expected to be useful for targets with large atomic number. In this case, the number of possible final states to be considered by the traditional atomic methods makes it a tough task to be tackled. On the contrary, the more electrons the target has, the better the local plasma approximation is expected to be

The Generalized Multipole Technique for the Simulation of Low-Loss Electron Energy Loss Spectroscopy

DEFF Research Database (Denmark)

Kiewidt, Lars; Karamehmedovic, Mirza

2018-01-01

In this study, we demonstrate the use of a Generalized Multipole Technique (GMT) to simulate low-loss Electron Energy Loss Spectroscopy (EELS) spectra of isolated spheriodal nanoparticles. The GMT provides certain properties, such as semi-analytical description of the electromagnetic fields...

Data Acquisition System for Electron Energy Loss Coincident Spectrometers

International Nuclear Information System (INIS)

Zhang Chi; Yu Xiaoqi; Yang Tao

2005-01-01

A Data Acquisition System (DAQ) for electron energy loss coincident spectrometers (EELCS) has been developed. The system is composed of a Multiplex Time-Digital Converter (TDC) that measures the flying time of positive and negative ions and a one-dimension position-sensitive detector that records the energy loss of scattering electrons. The experimental data are buffered in a first-in-first-out (FIFO) memory module, then transferred from the FIFO memory to PC by the USB interface. The DAQ system can record the flying time of several ions in one collision, and allows of different data collection modes. The system has been demonstrated at the Electron Energy Loss Coincident Spectrometers at the Laboratory of Atomic and Molecular Physics, USTC. A detail description of the whole system is given and experimental results shown

Construction of energy loss function for low-energy electrons in helium

Energy Technology Data Exchange (ETDEWEB)

Dayashankar, [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

1976-02-01

The energy loss function for electrons in the energy range from 50 eV to 1 keV in helium gas has been constructed by considering separately the energy loss in overcoming the ionization threshold, the loss manifested as kinetic energy of secondary electrons and the loss in the discrete state excitations. This has been done by utilizing recent measurements of Opal et al. on the energy spectrum of secondary electrons and incorporating the experimental data on cross sections for twenty-four excited states. The present results of the energy loss function are in good agreement with the Bethe formula for energies above 500 eV. For lower energies, where the Bethe formula is not applicable, the present results should be particularly useful.

Dose-rate-dependent damage of cerium dioxide in the scanning transmission electron microscope.

Science.gov (United States)

Johnston-Peck, Aaron C; DuChene, Joseph S; Roberts, Alan D; Wei, Wei David; Herzing, Andrew A

2016-11-01

Beam damage caused by energetic electrons in the transmission electron microscope is a fundamental constraint limiting the collection of artifact-free information. Through understanding the influence of the electron beam, experimental routines may be adjusted to improve the data collection process. Investigations of CeO 2 indicate that there is not a critical dose required for the accumulation of electron beam damage. Instead, measurements using annular dark field scanning transmission electron microscopy and electron energy loss spectroscopy demonstrate that the onset of measurable damage occurs when a critical dose rate is exceeded. The mechanism behind this phenomenon is that oxygen vacancies created by exposure to a 300keV electron beam are actively annihilated as the sample re-oxidizes in the microscope environment. As a result, only when the rate of vacancy creation exceeds the recovery rate will beam damage begin to accumulate. This observation suggests that dose-intensive experiments can be accomplished without disrupting the native structure of the sample when executed using dose rates below the appropriate threshold. Furthermore, the presence of an encapsulating carbonaceous layer inhibits processes that cause beam damage, markedly increasing the dose rate threshold for the accumulation of damage. Published by Elsevier B.V.

Chirality effect on electron phonon relaxation, energy loss, and thermopower in single and bilayer graphene in BG regime

Science.gov (United States)

Ansari, Meenhaz; Ashraf, S. S. Z.

2017-10-01

We investigate the energy dependent electron-phonon relaxation rate, energy loss rate, and phonon drag thermopower in single layer graphene (SLG) and bilayer graphene (BLG) under the Bloch-Gruneisen (BG) regime through coupling to acoustic phonons interacting via the Deformation potential in the Boltzmann transport equation approach. We find that the consideration of the chiral nature of electrons alters the temperature dependencies in two-dimensional structures of SLG and BLG from that shown by other conventional 2DEG system. Our investigations indicate that the BG analytical results are valid for temperatures far below the BG limit (˜TBG/4) which is in conformity with a recent experimental investigation for SLG [C. B. McKitterick et al., Phys. Rev. B 93, 075410 (2016)]. For temperatures above this renewed limit (˜TBG/4), there is observed a suppression in energy loss rate and thermo power in SLG, but enhancement is observed in relaxation rate and thermopower in BLG, while a suppression in the energy loss rate is observed in BLG. This strong nonmonotonic temperature dependence in SLG has also been experimentally observed within the BG limit [Q. Ma et al., Phys. Rev. Lett. 112, 247401 (2014)].

Magnetic field structure influence on primary electron cusp losses for micro-scale discharges

International Nuclear Information System (INIS)

Dankongkakul, Ben; Araki, Samuel J.; Wirz, Richard E.

2014-01-01

An experimental effort was used to examine the primary electron loss behavior for micro-scale (≲3 cm diameter) discharges. The experiment uses an electron flood gun source and an axially aligned arrangement of ring-cusps to guide the electrons to a downstream point cusp. Measurements of the electron current collected at the point cusp show an unexpectedly complex loss pattern with azimuthally periodic structures. Additionally, in contrast to conventional theory for cusp losses, the overall radii of the measured collection areas are over an order of magnitude larger than the electron gyroradius. Comparing these results to Monte Carlo particle tracking simulations and a simplified analytical analysis shows that azimuthal asymmetries of the magnetic field far upstream of the collection surface can substantially affect the electron loss structure and overall loss area

Coherence in electron energy loss spectrometry

International Nuclear Information System (INIS)

Schattschneider, P.; Werner, W.S.M.

2005-01-01

Coherence effects in electron energy loss spectrometry (EELS) and in energy filtering are largely neglected although they occur frequently due to Bragg scattering in crystals. We discuss how coherence in the inelastically scattered wave field can be described by the mixed dynamic form factor (MDFF), and how it relates to the density matrix of the scattered electrons. Among the many aspects of 'inelastic coherence' are filtered high-resolution images, dipole-forbidden transitions, coherence in plasma excitations, errors in chemical microanalysis, coherent double plasmons, and circular dichroism

Calculated and experimental low-loss electron energy loss spectra of dislocations in diamond and GaN

CERN Document Server

Jones, R; Gutiérrez-Sosa, A; Bangert, U; Heggie, M I; Blumenau, A T; Frauenheim, T; Briddon, P R

2002-01-01

First-principles calculations of electron energy loss (EEL) spectra for bulk GaN and diamond are compared with experimental spectra acquired with a scanning tunnelling electron microscope offering ultra-high-energy resolution in low-loss energy spectroscopy. The theoretical bulk low-loss EEL spectra, in the E sub g to 10 eV range, are in good agreement with experimental data. Spatially resolved spectra from dislocated regions in both materials are distinct from bulk spectra. The main effects are, however, confined to energy losses lying above the band edge. The calculated spectra for low-energy dislocations in diamond are consistent with the experimental observations, but difficulties remain in understanding the spectra of threading dislocations in GaN.

Subexponential loss rate asymptotics for Lévy processes

DEFF Research Database (Denmark)

Andersen, Lars Nørvang

2011-01-01

We consider a Lévy process reflected in barriers at 0 and K > 0. The loss rate is the mean of the local time at K at time 1 when the process is started in stationarity, and is a natural continuous-time analogue of the stationary expected loss rate for a reflected random walk. We derive asymptotic...... for the loss rate when K tends to infinity, when the mean of the Lévy process is negative and the positive jumps are subexponential. In the course of this derivation, we achieve a formula, which is a generalization of the celebrated Pollaczeck-Khinchine formula....

Comprehensive Power Losses Model for Electronic Power Transformer

DEFF Research Database (Denmark)

Yue, Quanyou; Li, Canbing; Cao, Yijia

2018-01-01

and considering the impact of the non-unity power factor and the three-phase unbalanced current, the overall power losses in the distribution network when using the EPT to replace the conventional transformer is analyzed, and the conditions in which the application of the EPT can cause less power losses...... reduced power losses in the distribution network require a comprehensive consideration when comparing the power losses of theEPT and conventional transformer. In this paper, a comprehensive power losses analysis model for the EPT in distribution networks is proposed. By analyzing the EPT self-losses......The electronic power transformer (EPT) has highe rpower losses than the conventional transformer. However, the EPT can correct the power factor, compensate the unbalanced current and reduce the line power losses in the distribution network.Therefore, the higher losses of the EPT and the consequent...

Comprehensive Power Losses Model for Electronic Power Transformer

DEFF Research Database (Denmark)

Yue, Quanyou; Li, Canbing; Cao, Yijia

2018-01-01

The electronic power transformer (EPT) has highe rpower losses than the conventional transformer. However, the EPT can correct the power factor, compensate the unbalanced current and reduce the line power losses in the distribution network.Therefore, the higher losses of the EPT and the consequent...... reduced power losses in the distribution network require a comprehensive consideration when comparing the power losses of theEPT and conventional transformer. In this paper, a comprehensive power losses analysis model for the EPT in distribution networks is proposed. By analyzing the EPT self......-losses and considering the impact of the non-unity power factor and the three-phase unbalanced current, the overall power losses in the distribution network when using the EPT to replace the conventional transformer is analyzed, and the conditions in which the application of the EPT can cause less power losses...

Food loss rate in food supply chain using material flow analysis.

Science.gov (United States)

Ju, Munsol; Osako, Masahiro; Harashina, Sachihiko

2017-03-01

The food loss rate is a factor that represents food consumption efficiency. To improve food consumption efficiency, we need to fundamentally quantify food loss at national and global levels. This study examines food and food waste flow and calculates the food loss rate in the food supply chain by targeting Japan. We analyzed inedible food waste and avoidable food losses in wholesale, manufacturing, retail, food services, and households and considered different supply chain pathways, different food categories representing whole Japanese meals, and weight changes after cooking. The results are as follows: (1) Japan has an overall rate of avoidable food losses of approximately 15% for meals (excluding agricultural losses), (2) the supply sector with the highest food loss rate is food services, and (3) the food category with the highest food loss rate is vegetables. Finally, we proposed a model for calculating food loss rates that could be used for future analysis in Japan or other countries. Copyright © 2017 Elsevier Ltd. All rights reserved.

First-Principles Vibrational Electron Energy Loss Spectroscopy of β -Guanine

Science.gov (United States)

Radtke, G.; Taverna, D.; Lazzeri, M.; Balan, E.

2017-07-01

A general approach to model vibrational electron energy loss spectra obtained using an electron beam positioned away from the specimen is presented. The energy-loss probability of the fast electron is evaluated using first-principles quantum mechanical calculations (density functional theory) of the dielectric response of the specimen. The validity of the method is assessed using recently measured anhydrous β -guanine, an important molecular solid used by animals to produce structural colors. The good agreement between theory and experiments lays the basis for a quantitative interpretation of this spectroscopy in complex systems.

Mass loss rates in the Hertzsprung-Russell diagram

International Nuclear Information System (INIS)

Jager, C. de; Nieuwenhuijzen, H.; Hucht, K.A. van der

1988-01-01

From the literature we collected values for the rate of mass loss for 271 stars, nearly all of population I, and of spectral types 0 through M. Rates of stellar mass loss determined according to six different methods were compared and appear to yield the same result per star within the limits of errors; this is true regardless of the star's position in the HR-diagram. Thus average rates of mass loss were determined, and weights were allocated to the M-determinations for each star. In addition we studied some groups of other stars: fast rotators (22 Be-type stars), and chemically evolved stars (31 Wolf-Rayet stars; 11 C- and 4 S-type stars and 15 nuclei of planetary nebulae). The chemically evolved stars have rates of mass loss which are larger than those of ''normal'' stars occupying the same positions in the Hertzprung-Russel diagram, by factors: 160 for Wolf-Rayet stars; 11 for C-type stars, and by estimated factors of 10 3 to 10 4 for the nuclei of planetary nebulae

Thermal electron heating rate: a derivation

International Nuclear Information System (INIS)

Hoegy, W.R.

1983-11-01

The thermal electron heating rate is an important heat source term in the ionospheric electron energy balance equation, representing heating by photoelectrons or by precipitating higher energy electrons. A formula for the thermal electron heating rate is derived from the kinetic equation using the electron-electron collision operator as given by the unified theory of Kihara and Aono. This collision operator includes collective interactions to produce a finite collision operator with an exact Coulomb logarithm term. The derived heating rate O(e) is the sum of three terms, O(e) O(p) + S + O(int), which are respectively: (1) primary electron production term giving the heating from newly created electrons that have not yet suffered collisions with the ambient electrons, (2) a heating term evaluated on the energy surface m(e)/2 E(T) at the transition between Maxwellian and tail electrons at E(T), and (3) the integral term representing heating of Maxwellian electrons by energetic tail electrons at energies ET. Published ionospheric electron temperature studies used only the integral term O(int) with differing lower integration limits. Use of the incomplete heating rate could lead to erroneous conclusions regarding electron heat balance, since O(e) is greater than O(int) by as much as a factor of two

Examining Relativistic Electron Loss in the Outer Radiation Belt

Science.gov (United States)

Green, J. C.; Onsager, T. G.; O'Brien, P.

2003-12-01

Since the discovery of earth's radiation belts researchers have sought to identify the mechanisms that dictate the seemingly erratic relativistic electron flux levels in the outer belt. Contrary to intuition, relativistic electron flux levels do not always increase during geomagnetic storms even though these storms signify enhanced energy input from the solar wind to the magnetosphere [Reeves et al., 2003; O'Brien et al., 2001]. The fickle response of the radiation belt electrons to geomagnetic activity suggests that flux levels are determined by the outcome of a continuous competition between acceleration and loss. Some progress has been made developing and testing acceleration mechanisms but little is known about how relativistic electrons are lost. We examine relativistic electron losses in the outer belt focusing our attention on flux decrease events of the type first described by Onsager et al. [2002]. The study showed a sudden decrease of geosynchronous >2MeV electron flux occurring simultaneously with local stretching of the magnetic field. The decrease was first observed near 15:00 MLT and progressed to all local times after a period of ˜10 hours. Expanding on the work of Onsager et al. [2002], we have identified ˜ 51 such flux decrease events in the GOES and LANL data and present the results of a superposed epoch analysis of solar wind data, geomagnetic activity indicators, and locally measured magnetic field and plasma data. The analysis shows that flux decreases occur after 1-2 days of quiet condition. They begin when either the solar wind dynamic pressure increases or Bz turns southward pushing hot dense plasma earthward to form a partial ring current and stretched magnetic field at dusk. Adiabatic electron motion in response to the stretched magnetic field may explain the initial flux reduction; however, often the flux does not recover with the magnetic field recovery, indicating that true loss from the magnetosphere is occurring. Using Polar and

Electron dose rate and photon contamination in electron arc therapy

International Nuclear Information System (INIS)

Pla, M.; Podgorsak, E.B.; Pla, C.

1989-01-01

The electron dose rate at the depth of dose maximum dmax and the photon contamination are discussed as a function of several parameters of the rotational electron beam. A pseudoarc technique with an angular increment of 10 degrees and a constant number of monitor units per each stationary electron field was used in our experiments. The electron dose rate is defined as the electron dose at a given point in phantom divided by the number of monitor units given for any one stationary electron beam. For a given depth of isocenter di the electron dose rates at dmax are linearly dependent on the nominal field width w, while for a given w the dose rates are inversely proportional to di. The dose rates for rotational electron beams with different di are related through the inverse square law provided that the two beams have (di,w) combinations which give the same characteristic angle beta. The photon dose at the isocenter depends on the arc angle alpha, field width w, and isocenter depth di. For constant w and di the photon dose at isocenter is proportional to alpha, for constant alpha and w it is proportional to di, and for constant alpha and di it is inversely proportional to w. The w and di dependence implies that for the same alpha the photon dose at the isocenter is inversely proportional to the electron dose rate at dmax

High-resolution monochromated electron energy-loss spectroscopy of organic photovoltaic materials.

Science.gov (United States)

Alexander, Jessica A; Scheltens, Frank J; Drummy, Lawrence F; Durstock, Michael F; Hage, Fredrik S; Ramasse, Quentin M; McComb, David W

2017-09-01

Advances in electron monochromator technology are providing opportunities for high energy resolution (10 - 200meV) electron energy-loss spectroscopy (EELS) to be performed in the scanning transmission electron microscope (STEM). The energy-loss near-edge structure in core-loss spectroscopy is often limited by core-hole lifetimes rather than the energy spread of the incident illumination. However, in the valence-loss region, the reduced width of the zero loss peak makes it possible to resolve clearly and unambiguously spectral features at very low energy-losses (photovoltaics (OPVs): poly(3-hexlythiophene) (P3HT), [6,6] phenyl-C 61 butyric acid methyl ester (PCBM), copper phthalocyanine (CuPc), and fullerene (C 60 ). Data was collected on two different monochromated instruments - a Nion UltraSTEM 100 MC 'HERMES' and a FEI Titan 3 60-300 Image-Corrected S/TEM - using energy resolutions (as defined by the zero loss peak full-width at half-maximum) of 35meV and 175meV, respectively. The data was acquired to allow deconvolution of plural scattering, and Kramers-Kronig analysis was utilized to extract the complex dielectric functions. The real and imaginary parts of the complex dielectric functions obtained from the two instruments were compared to evaluate if the enhanced resolution in the Nion provides new opto-electronic information for these organic materials. The differences between the spectra are discussed, and the implications for STEM-EELS studies of advanced materials are considered. Copyright © 2017 Elsevier B.V. All rights reserved.

Surface energy loss processes in XPS studied by absolute reflection electron energy loss spectroscopy

International Nuclear Information System (INIS)

Nagatomi, T.; Goto, K.

2010-01-01

The results of the investigation of the inelastic interaction of 300-3000 eV electrons with the Ni and Au surfaces by the analysis of absolute reflection electron energy loss spectroscopy (REELS) spectra were described. The present analysis enables the inelastic mean free path (IMFP), surface excitation parameter (SEP) and differential SEP (DSEP) to be obtained simultaneously from an absolute REELS spectrum. The obtained IMFPs for Ni and Au showed a good agreement with those calculated using the TPP-2M predictive equation. The present SEPs determined for Ni and Au were fitted to the Chen's formula describing the dependence of the SEP on the electron energy, and material parameters for Ni and Au in Chen's formula were proposed. The present DESPs were compared with the theoretical results, and a reasonable agreement between the experimentally determined DSEPs and theoretical results was confirmed. The MC modeling of calculating the REELS spectrum, in which energy loss processes due to surface excitations are taken into account, was also described. The IMFP, SEP and DSEP determined by the present absolute REELS analysis were employed to describe energy loss processes by inelastic scattering in the proposed MC simulation. The simulated REELS spectra were found to be in a good agreement with the experimental spectra for both Ni and Au.

Angle-resolved electron energy loss spectroscopy in hexagonal boron nitride

Science.gov (United States)

Fossard, Frédéric; Sponza, Lorenzo; Schué, Léonard; Attaccalite, Claudio; Ducastelle, François; Barjon, Julien; Loiseau, Annick

2017-09-01

Electron energy loss spectra were measured on hexagonal boron nitride single crystals employing an electron energy loss spectroscopic setup composed of an electron microscope equipped with a monochromator and an in-column filter. This setup provides high-quality energy-loss spectra and allows also for the imaging of energy-filtered diffraction patterns. These two acquisition modes provide complementary pieces of information, offering a global view of excitations in reciprocal space. As an example of the capabilities of the method we show how easily the core loss spectra at the K edges of boron and nitrogen can be measured and imaged. Low losses associated with interband and/or plasmon excitations are also measured. This energy range allows us to illustrate that our method provides results whose quality is comparable to that obtained from nonresonant x-ray inelastic scattering but with advantageous specificities such as an enhanced sensitivity at low q and a much greater simplicity and versatility that make it well adapted to the study of two-dimensional materials and related heterostructures. Finally, by comparing theoretical calculations to our measures, we are able to relate the range of applicability of ab initio calculations to the anisotropy of the sample and assess the level of approximation required for a proper simulation of our acquisition method.

Target electron collision effects on energy loss straggling of protons in an electron gas at any degeneracy

International Nuclear Information System (INIS)

Barriga-Carrasco, Manuel D.

2008-01-01

The purpose of the present paper is to describe the effects of target electron collisions on proton energy loss straggling in plasmas at any degeneracy. Targets are considered fully ionized so electronic energy loss is only due to the free electrons. The analysis is focused on targets with electronic density around solid values n e ≅10 23 cm -3 and with temperature around T≅10 eV; these targets are in the limit of weakly coupled electron gases. These types of plasma targets have not been studied extensively, though they are very important for inertial confinement fusion. The energy loss straggling is obtained from an exact quantum-mechanical evaluation, which takes into account the degeneracy of the target plasma, and later it is compared with common classical and degenerate approximations. Then electron collisions in the exact quantum-mechanical straggling calculation are considered. Now the energy loss straggling is enhanced for energies smaller than the energy before the maximum, then decreases around this maximum, and finally tends to the same values with respect to noncollisional calculation. Differences with the same results but not taking into account these collisions are as far as 17% in the cases analyzed. As an example, proton range distributions have been calculated to show the importance of an accurate energy straggling calculation

Mass Loss Rates of Fasting Polar Bears.

Science.gov (United States)

Pilfold, Nicholas W; Hedman, Daryll; Stirling, Ian; Derocher, Andrew E; Lunn, Nicholas J; Richardson, Evan

2016-01-01

Polar bears (Ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the Arctic. As a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which polar bears must rely on fat reserves has increased. To date, there is limited empirical data with which to evaluate the potential energetic capacity of polar bears to withstand longer fasts. We measured the incoming and outgoing mass of inactive polar bears (n = 142) that were temporarily detained by Manitoba Conservation and Water Stewardship during the open-water period near the town of Churchill, Manitoba, Canada, in 2009-2014. Polar bears were given access to water but not food and held for a median length of 17 d. Median mass loss rates were 1.0 kg/d, while median mass-specific loss rates were 0.5%/d, similar to other species with high adiposity and prolonged fasting capacities. Mass loss by unfed captive adult males was identical to that lost by free-ranging individuals, suggesting that terrestrial feeding contributes little to offset mass loss. The inferred metabolic rate was comparable to a basal mammalian rate, suggesting that while on land, polar bears can maintain a depressed metabolic rate to conserve energy. Finally, we estimated time to starvation for subadults and adult males for the on-land period. Results suggest that at 180 d of fasting, 56%-63% of subadults and 18%-24% of adult males in this study would die of starvation. Results corroborate previous assessments on the limits of polar bear capacity to withstand lengthening ice-free seasons and emphasize the greater sensitivity of subadults to changes in sea ice phenology.

Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

Energy Technology Data Exchange (ETDEWEB)

Isomura, Noritake, E-mail: isomura@mosk.tytlabs.co.jp [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Soejima, Narumasa; Iwasaki, Shiro [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Nomoto, Toyokazu; Murai, Takaaki [Aichi Synchrotron Radiation Center (AichiSR), 250-3 Minamiyamaguchi-cho, Seto, Aichi 489-0965 (Japan); Kimoto, Yasuji [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

2015-11-15

Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si{sub 3}N{sub 4}/SiO{sub 2}/Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si{sub 3}N{sub 4}/SiO{sub 2}/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

International Nuclear Information System (INIS)

Isomura, Noritake; Soejima, Narumasa; Iwasaki, Shiro; Nomoto, Toyokazu; Murai, Takaaki; Kimoto, Yasuji

2015-01-01

Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si_3N_4/SiO_2/Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si_3N_4/SiO_2/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

Experimental study of single-electron loss by Ar+ ions in rare-gas atoms

Science.gov (United States)

Reyes, P. G.; Castillo, F.; Martínez, H.

2001-04-01

Absolute differential and total cross sections for single-electron loss were measured for Ar+ ions on rare-gas atoms in the laboratory energy range of 1.5 to 5.0 keV. The electron loss cross sections for all the targets studied are found to be in the order of magnitude between 10-19 and 10-22 cm2, and show a monotonically increasing behaviour as a function of the incident energy. The behaviour of the total single-electron loss cross sections with the atomic target number, Zt, shows different dependences as the collision energy increases. In all cases the present results display experimental evidence of saturation in the single-electron loss cross section as the atomic number of the target increases.

Low-dose electron energy-loss spectroscopy using electron counting direct detectors.

Science.gov (United States)

Maigné, Alan; Wolf, Matthias

2018-03-01

Since the development of parallel electron energy loss spectroscopy (EELS), charge-coupled devices (CCDs) have been the default detectors for EELS. With the recent development of electron-counting direct-detection cameras, micrographs can be acquired under very low electron doses at significantly improved signal-to-noise ratio. In spectroscopy, in particular in combination with a monochromator, the signal can be extremely weak and the detection limit is principally defined by noise introduced by the detector. Here we report the use of an electron-counting direct-detection camera for EEL spectroscopy. We studied the oxygen K edge of amorphous ice and obtained a signal noise ratio up to 10 times higher than with a conventional CCD.We report the application of electron counting to record time-resolved EEL spectra of a biological protein embedded in amorphous ice, revealing chemical changes observed in situ while exposed by the electron beam. A change in the fine structure of nitrogen K and the carbon K edges were recorded during irradiation. A concentration of 3 at% nitrogen was detected with a total electron dose of only 1.7 e-/Å2, extending the boundaries of EELS signal detection at low electron doses.

Electron loss and capture from low-charge-state oxygen projectiles in methane

International Nuclear Information System (INIS)

Santos, A C F; Wolff, W; Sant’Anna, M M; Sigaud, G M; DuBois, R D

2013-01-01

Absolute cross sections for single- and double-electron loss and single- and multiple-electron capture of 15–1000 keV oxygen projectiles (q = −1, 0, 1, 2) colliding with the methane molecule are presented. The experimental data are used to examine cross-section scaling characteristics for the electron loss of various projectiles. In addition, a modified version of the free-collision model was employed for the calculation of the single- and total-electron-loss cross sections of oxygen projectiles presented in this work. The comparison of the calculated cross sections with the present experimental data shows very good agreement for projectile velocities above 1.0 au. The comparison of the present single-electron-capture cross sections with other projectiles having the same charge shows good agreement, and a common curve can be drawn through the different data sets. (paper)

Electron loss mechanisms in collisions of He+ ions with various targets

International Nuclear Information System (INIS)

Sant'Anna, M.M.; Melo, W.S.; Santos, A.C.F.; Sigaud, G.M.; Montenegro, E.C.

1995-01-01

The electron loss of high-velocity ions by neutral atoms is due to two different and competing mechanisms. In the screening mode, the electron loss is basically due to the nucleus-electron interaction, with the target electrons assuming the passive role of decreasing the Coulomb field of the target nucleus in the vicinity of the projectile active electron. For a fixed projectile velocity, this contribution is expected to give a non-linear dependence with the target atomic number Z 2 due to the incomplete screening at the impact parameter region where the projectile ionization is more likely to occur. Within first-order theories, if the screening is completely absent, the expected dependence would be Z 2 2 ; with screening, it should scale between Z 2 and Z 2 2 . On the other hand, in the antiscreening mode, where the loss is due to the action of the target electrons and the target nucleus plays no active role, the expected dependence would be approximately linear with Z 2 . Thus, for first-order theories, the expected overall dependence with Z 2 would be dominated by the screening mode as Z 2 increases. We have measured total electron-loss cross sections of He + ions impinging upon He, Ne, Ar, Kr and Xe targets in the energy range from 1.0 to 4.0 MeV to complement previous measurements and the results point towards a much smaller contribution from the screening mode than expected from first-order theories, possibly due to a saturation effect manifested only in the screening channel. (orig.)

Gamma rays from relativistic electrons undergoing Compton losses in isotropic photon fields

International Nuclear Information System (INIS)

Zdziarski, A.A.

1989-01-01

The kinetic equation describing Compton losses of relativistic electrons in an isotropic field of soft background photons is solved exactly including both continuous energy losses in the classical Thomson regime and catastrophic losses in the quantum Klein-Nishina regime. This extends the previous treatments of this problem, which assumed the validity of either one of these regimes alone. The problem is relevant to astrophysical sources containing relativistic electrons. Analytical solutions for the steady state electron and gamma-ray spectra in the case of power-law soft photons and monoenergetic and power-law electron injections are obtained. Numerical solutions are presented for monoenergetic, blackbody, and power-law soft photons. A comparison between the numerical and the available analytic solutions is made. 15 refs

Loss of speciation rate will impoverish future diversity

OpenAIRE

Rosenzweig, Michael L.

2001-01-01

Human activities have greatly reduced the amount of the earth's area available to wild species. As the area they have left declines, so will their rates of speciation. This loss of speciation will occur for two reasons: species with larger geographical ranges speciate faster; and loss of area drives up extinction rates, thus reducing the number of species available for speciation. Theory predicts steady states in species diversity, and fossils suggest that these have t...

Deconvolution of overlapping features in electron energy-loss spectra: the determination of absolute differential cross sections for electron-impact excitation of electronic states of molecules

International Nuclear Information System (INIS)

Campbell, L.; Brunger, M.J.; Teubner, O.J.P.; Mojarrabi, B.

1996-06-01

A set of three computer programs is reported which allow for the deconvolution of overlapping molecular electronic state structure in electron energy-loss spectra, even in highly perturbed systems. This procedure enables extraction of absolute differential cross sections for electron-impact excitation of electronic states of diatomic molecules from electron energy-loss spectra. The first code in the sequence uses the Rydberg-Klein-Rees procedure to generate potential energy curves from spectroscopic constants, while the second calculates Franck-Condon factors by numerical solution of the Schroedinger equation, given the potential energy curves. The third, given these Franck-Condon factors, the previously calculated relevant energies for the vibrational levels of the respective electronic states and the experimental energy-loss spectra, extracts the differential cross sections for each state. Each program can be run independently, or the three can run in sequence to determine these cross sections from the spectroscopic constants and the experimental energy-loss spectra. The application of these programs to the specific case of electron scattering from nitric oxide (NO) is demonstrated. 25 refs., 2 tabs., 2 figs

Electron energy-loss spectroscopy of quasi-one-dimensional cuprates and vanadates

International Nuclear Information System (INIS)

Atzkern, S.

2001-01-01

In a combination of experimental and theoretical methods in this thesis the electronic structures of quasi-one-dimensional cuprates and vanadates were studied. For this the momentum-dependent loss function was measured by means of the electron energy-loss spectroscopy in transmission on monocrystals of Li 2 CuO 2 , CuGeO 3 , V 2 O 5 and α'-NaVO 5 . The comparison of the experimental data with results from band-structure and cluster calculations allowed conclusions on the mobility and correlations of the electrons in these systems

Reaction rate and energy-loss rate for photopair production by relativistic nuclei

Science.gov (United States)

Chodorowski, Michal J.; Zdziarski, Andrzej A.; Sikora, Marek

1992-01-01

The process of e(+/-) pair production by relativistic nuclei on ambient photons is considered. The process is important for cosmic-ray nuclei in interstellar and intergalactic space as well as in galactic and extragalactic compact objects. The rate of this process is given by an integral of the cross section over the photon angular and energy distribution. In the case of isotropic photons, the angular integration is performed to provide an expression for the rate at given photon energy in the nucleus rest frame. The total rate then becomes a single integral of that rate over the photon energy distribution. Formulas are also given for the fractional energy loss of a relativistic nucleus colliding with a photon of a given energy in the rest frame. The nucleus energy-loss rate is integrated over the photon angular distribution in the case of isotropic photons, and simple fits are provided.

Mass-loss rates of cool stars

Science.gov (United States)

Katrien Els Decin, Leen

2015-08-01

Over much of the initial mass function, stars lose a significant fraction of their mass through a stellar wind during the late stages of their evolution when being a (super)giant star. As of today, we can not yet predict the mass-loss rate during the (super)giant phase for a given star with specific stellar parameters from first principles. This uncertainty directly impacts the accuracy of current stellar evolution and population synthesis models that predict the enrichment of the interstellar medium by these stellar winds. Efforts to establish the link between the initial physical and chemical conditions at stellar birth and the mass-loss rate during the (super)giant phase have proceeded on two separate tracks: (1) more detailed studies of the chemical and morpho-kinematical structure of the stellar winds of (super)giant stars in our own Milky Way by virtue of the proximity, and (2) large scale and statistical studies of a (large) sample of stars in other galaxies (such as the LMC and SMC) and globular clusters eliminating the uncertainty on the distance estimate and providing insight into the dependence of the mass-loss rate on the metallicity. In this review, I will present recent results of both tracks, will show how recent measurements confirm (some) theoretical predictions, but also how results from the first track admonish of common misconceptions inherent in the often more simplified analysis used to analyse the large samples from track 2.

Electronic energy loss of the latent track in heavy ion-irradiated polyimide

International Nuclear Information System (INIS)

Sun Youmei; Liu Jie; Zhang Chonghong; Wang Zhiguang; Jin Yunfan; Duan Jinglai; Song Yin

2005-01-01

In the interaction process of a swift heavy ion (SHI) and polymer, a latent track with radius of several nanometers appears near the ion trajectory due to the dense ionization and excitation. To describe the role of electronic energy loss (dE/dX) e , multi-layer stacks (with different dE/dX) of polyimide (PI) films were irradiated by different SHIs (1.158 GeV Fe 56 and 1.755 GeV Xe 136 ) under vacuum at room temperature. Chemical changes of modified PI films were studied by Fourier Transform Infrared (FTIR) spectroscopy. The main feature of SHI irradiation is the degradation of the functional group and creation of alkyne. The chain disruption rate of PI was investigated in the fluence range from 1 x 10 11 to 6 x 10 12 ions/cm 2 and a wider energy stopping power range (2.2 to 5.2 keV/nm for Fe 56 ions and 8.6 to 11.3 keV/nm for Xe 136 ions). Alkyne formation was observed over the electronic energy loss range of interest. Assuming the saturated track model (the damage process only occur in a cylinder of area σ), the mean degradation and alkyne formation radii in tracks were deduced for Fe and Xe ion irradiation, respectively. The results were validated by the thermal spike model and the threshold electronic energy loss of track formation S et in PI was deduced. The analysis of the irradiated PI films shows that the predictions of the thermal spike model are in qualitative agreement with the curve shape of experimental results. (authors)

Electron Energy-Loss Spectroscopy: Fundamentals and applications in the characterization of minerals

International Nuclear Information System (INIS)

Krishnan, K.M.

1989-04-01

The combined use of an energy-loss spectrometer and an analytical electron microscope with fine probe forming capabilities provides a wealth of information about the sample at high spatial resolution. Fundamental principles governing the physics of the interaction between the fast electron and a thin foil sample, to account for the fine structure in the inelastically scattered fast electron distribution (Electron-Energy Loss Spectroscopy, EELS), will be reviewed. General application of EELS is in the area of low atomic number elements (Z < 11) microanalysis, where it significantly complements the more widely used Energy Dispersive X-ray Spectroscopy (EDXS). However, a careful analysis of the low loss plasmon oscillations and the fine structure in the core-loss edges, can provide additional information related to the bonding and electronic structure of the sample. An illustration of this is presented from our study of Cδ diamond residue from the Allende carbonaceous chondrite. Combination of EELS with channeling effects can provide specific site occupation/valence information in crystalline materials. Details of this novel crystallographic method will be outlined and illustrated with an example of the study of chromite spinels. Finally, some pertinent experimental details will be discussed. 7 figs

Study of optical and electronic properties of nickel from reflection electron energy loss spectra

Science.gov (United States)

Xu, H.; Yang, L. H.; Da, B.; Tóth, J.; Tőkési, K.; Ding, Z. J.

2017-09-01

We use the classical Monte Carlo transport model of electrons moving near the surface and inside solids to reproduce the measured reflection electron energy-loss spectroscopy (REELS) spectra. With the combination of the classical transport model and the Markov chain Monte Carlo (MCMC) sampling of oscillator parameters the so-called reverse Monte Carlo (RMC) method was developed, and used to obtain optical constants of Ni in this work. A systematic study of the electronic and optical properties of Ni has been performed in an energy loss range of 0-200 eV from the measured REELS spectra at primary energies of 1000 eV, 2000 eV and 3000 eV. The reliability of our method was tested by comparing our results with the previous data. Moreover, the accuracy of our optical data has been confirmed by applying oscillator strength-sum rule and perfect-screening-sum rule.

Rate control for electron gun evaporation

International Nuclear Information System (INIS)

Schellingerhout, A.J.G.; Janocko, M.A.; Klapwijk, T.M.; Mooij, J.E.

1989-01-01

Principles for obtaining high-quality rate control for electron gun evaporation are discussed. The design criteria for rate controllers are derived from this analysis. Results are presented which have been obtained with e-guns whose evaporation rate is controlled by a Wehnelt electrode or by sweeping of the electron beam. Further improvements of rate stability can be obtained by improved design of e-guns and power supplies

Resonance effects in projectile-electron loss in relativistic collisions with excited atoms

International Nuclear Information System (INIS)

Voitkiv, A B

2005-01-01

The theory of electron loss from projectile-ions in relativistic ion-atom collisions is extended to the case of collisions with excited atoms. The main feature of such collisions is a resonance which can emerge between electron transitions in the ion and atom. The resonance becomes possible due to the Doppler effect and has a well-defined impact energy threshold. In the resonance case, the ion-atom interaction is transmitted by the radiation field and the range of this interaction becomes extremely long. Because of this the presence of other atoms in the target medium and the size of the space occupied by the medium have to be taken into account and it turns out that microscopic loss cross sections may be strongly dependent on such macroscopic parameters as the target density, temperature and size. We consider both the total and differential loss cross sections and show that the resonance can have a strong impact on the angular and energy distributions of electrons emitted from the projectiles and the total number of electron loss events

Electron loss from multiply protonated lysozyme ions in high energy collisions with molecular oxygen

DEFF Research Database (Denmark)

Hvelplund, P; Nielsen, SB; Sørensen, M

2001-01-01

We report on the electron loss from multiply protonated lysozyme ions Lys-Hn(n)+ (n = 7 - 17) and the concomitant formation of Lys-Hn(n+1)+. in high-energy collisions with molecular oxygen (laboratory kinetic energy = 50 x n keV). The cross section for electron loss increases with the charge state...... of the precursor from n = 7 to n = 11 and then remains constant when n increases further. The absolute size of the cross section ranges from 100 to 200 A2. The electron loss is modeled as an electron transfer process between lysozyme cations and molecular oxygen....

Relativistic effects in the energy loss of a fast charged particle moving parallel to a two-dimensional electron gas

Science.gov (United States)

Mišković, Zoran L.; Akbari, Kamran; Segui, Silvina; Gervasoni, Juana L.; Arista, Néstor R.

2018-05-01

We present a fully relativistic formulation for the energy loss rate of a charged particle moving parallel to a sheet containing two-dimensional electron gas, allowing that its in-plane polarization may be described by different longitudinal and transverse conductivities. We apply our formulation to the case of a doped graphene layer in the terahertz range of frequencies, where excitation of the Dirac plasmon polariton (DPP) in graphene plays a major role. By using the Drude model with zero damping we evaluate the energy loss rate due to excitation of the DPP, and show that the retardation effects are important when the incident particle speed and its distance from graphene both increase. Interestingly, the retarded energy loss rate obtained in this manner may be both larger and smaller than its non-retarded counterpart for different combinations of the particle speed and distance.

Secondary Electron Emission Beam Loss Monitor for LHC

CERN Document Server

Dehning, B; Holzer, E B; Kramer, Daniel

2008-01-01

Beam Loss Monitoring (BLM) system is a vital part of the active protection of the LHC accelerators' elements. It should provide the number of particles lost from the primary hadron beam by measuring the radiation field induced by their interaction with matter surrounding the beam pipe. The LHC BLM system will use ionization chambers as standard detectors but in the areas where very high dose rates are expected, the Secondary Emission Monitor (SEM) chambers will be employed because of their high linearity, low sensitivity and fast response. The SEM needs a high vacuum for proper operation and has to be functional for up to 20 years, therefore all the components were designed according to the UHV requirements and a getter pump was included. The SEM electrodes are made of Ti because of its Secondary Emission Yield (SEY) stability. The sensitivity of the SEM was modeled in Geant4 via the Photo-Absorption Ionization module together with custom parameterization of the very low energy secondary electron production. ...

Electron transfer by excited benzoquinone anions: slow rates for two-electron transitions.

Science.gov (United States)

Zamadar, Matibur; Cook, Andrew R; Lewandowska-Andralojc, Anna; Holroyd, Richard; Jiang, Yan; Bikalis, Jin; Miller, John R

2013-09-05

Electron transfer (ET) rate constants from the lowest excited state of the radical anion of benzoquinone, BQ(-•)*, were measured in THF solution. Rate constants for bimolecular electron transfer reactions typically reach the diffusion-controlled limit when the free-energy change, ΔG°, reaches -0.3 eV. The rate constants for ET from BQ(-•)* are one-to-two decades smaller at this energy and do not reach the diffusion-controlled limit until -ΔG° is 1.5-2.0 eV. The rates are so slow probably because a second electron must also undergo a transition to make use of the energy of the excited state. Similarly, ET, from solvated electrons to neutral BQ to form the lowest excited state, is slow, while fast ET is observed at a higher excited state, which can be populated in a transition involving only one electron. A simple picture based on perturbation theory can roughly account for the control of electron transfer by the need for transition of a second electron. The picture also explains how extra driving force (-ΔG°) can restore fast rates of electron transfer.

Experimental study of single-electron loss by Ar{sup +} ions in rare-gas atoms

Energy Technology Data Exchange (ETDEWEB)

Reyes, P.G. [Facultad de Ciencias, UNAM, Coyoacan (Mexico); Castillo, F. [Instituto de Ciencias Nucleares, UNAM, Coyoacan (Mexico); Martinez, H. [Centro de Ciencias Fisicas, UNAM, Cuernavaca, Morelos (Mexico)]. E-mail: hm@fis.unam.mx

2001-04-28

Absolute differential and total cross sections for single-electron loss were measured for Ar{sup +} ions on rare-gas atoms in the laboratory energy range of 1.5 to 5.0 keV. The electron loss cross sections for all the targets studied are found to be in the order of magnitude between 10{sup -19} and 10{sup -22} cm{sup 2}, and show a monotonically increasing behaviour as a function of the incident energy. The behaviour of the total single-electron loss cross sections with the atomic target number, Z{sub t}, shows different dependences as the collision energy increases. In all cases the present results display experimental evidence of saturation in the single-electron loss cross section as the atomic number of the target increases. (author)

Electron transport in furfural: dependence of the electron ranges on the cross sections and the energy loss distribution functions

Science.gov (United States)

Ellis-Gibbings, L.; Krupa, K.; Colmenares, R.; Blanco, F.; Muńoz, A.; Mendes, M.; Ferreira da Silva, F.; Limá Vieira, P.; Jones, D. B.; Brunger, M. J.; García, G.

2016-09-01

Recent theoretical and experimental studies have provided a complete set of differential and integral electron scattering cross section data from furfural over a broad energy range. The energy loss distribution functions have been determined in this study by averaging electron energy loss spectra for different incident energies and scattering angles. All these data have been used as input parameters for an event by event Monte Carlo simulation procedure to obtain the electron energy deposition patterns and electron ranges in liquid furfural. The dependence of these results on the input cross sections is then analysed to determine the uncertainty of the simulated values.

The effects of degeneracy of the carrier ensemble on the energy loss rate and the high field mobility characteristics under the conditions of low lattice temperatures

International Nuclear Information System (INIS)

Basu, A.; Das, B.; Middya, T.R.; Bhattacharya, D.P.

2017-01-01

The rate of loss of energy of the non-equilibrium electrons to the acoustic mode lattice vibration in a degenerate semiconductor is obtained under the condition, when the lattice temperature is low enough, so that the traditional approximations like the elastic nature of the electron-phonon collisions and the truncation of the phonon distribution to the equipartition law are not valid any more. Using the results of the energy loss rate, the non-ohmic mobility is then calculated. Evaluating the loss rate and the non-ohmic mobility in degenerate samples of Si and Ge we find that significant changes in both the characteristics have been effected compared to that in the non-degenerate samples, in the regime of lower energy and for relatively lower fields. The effected changes are more significant the lower the lattice temperature is.

Unit soil loss rate from various construction sites during a storm.

Science.gov (United States)

Maniquiz, Marla C; Lee, Soyoung; Lee, Eunju; Kong, Dong-Soo; Kim, Lee-Hyung

2009-01-01

The Korean Ministry of Environment (MOE) opts to establish an ordinance having a standard specifying an allowable soil loss rate applicable to construction projects. The predicted amount of soil loss from a construction site exceeding the standard can be used to calculate the percent reduction necessary to comply with the ordinance. This research was conducted to provide a basis to establish a standard by investigating the unit soil loss rates in the three phases of development: pre-construction, active construction and post construction based from 1,036 Environmental Impact Assessment (EIA) reports within the six-year period (2000-2005). Based on the findings, several factors affect the magnitude of soil loss rates particularly storm characteristics, site slope, soil type, location from rivers, as well as the type of construction activity. In general, the unit soil loss rates during the active construction phase are extremely higher in comparison to undisturbed areas; in magnitude of 7 to 80 times larger in urban areas and 18 to 585 times in rural areas. Only between 20 to 40 percent of the soil loss rates was contributed at pre- and post- construction phases indicating that the active construction phase is the most important phase to control.

Precessed electron beam electron energy loss spectroscopy of graphene: Beyond channelling effects

Energy Technology Data Exchange (ETDEWEB)

Yedra, Ll.; Estradé, S., E-mail: sestrade@ub.edu [LENS, MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); TEM-MAT, CCiT, Universitat de Barcelona, Solé i Sabarís 1, 08028 Barcelona (Spain); Torruella, P.; Eljarrat, A.; Peiró, F. [LENS, MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Darbal, A. D. [AppFive LLC, 1095 W Rio Salado Pkway, Suite 110, Tempe, Arizona 85281 (United States); Weiss, J. K. [AppFive LLC, 1095 W Rio Salado Pkway, Suite 110, Tempe, Arizona 85281 (United States); NanoMEGAS SPRL, Blvd. Edmond Machtens 79, B-1080 Brussels (Belgium)

2014-08-04

The effects of beam precession on the Electron Energy Loss Spectroscopy (EELS) signal of the carbon K edge in a 2 monolayer graphene sheet are studied. In a previous work, we demonstrated the use of precession to compensate for the channeling-induced reduction of EELS signal when in zone axis. In the case of graphene, no enhancement of EELS signal is found in the usual experimental conditions, as graphene is not thick enough to present channeling effects. Interestingly, though it is found that precession makes it possible to increase the collection angle, and, thus, the overall signal, without a loss of signal-to-background ratio.

Comments on GUT monopole energy loss and ionization

International Nuclear Information System (INIS)

Hagstrom, R.

1982-01-01

A few comments about the likely behavior of the electromagnetic energy loss and ionization rates of super-slowly moving magnetic monopoles are presented. The questions of energy loss rates and ionization rates for super-low monopoles passing through matter are considered, concentrating on aspects of these issues which affect practical detection techniques. It is worthwhile here to emphasize that there is a potentially great distinction between energy loss rates and ionization rates and that the magnitude of this distinction is really the great issue which must be settled in order to understand the significance of experimental results from present and proposed investigations of the slow monopole question. Energy loss here means the total dE/dX of the projectile due to interactions with the electrons of the slowing medium. To the extent that nuclear collisions can be neglected, this so-called electronic energy loss is the relevant quantity in questions about whether monopoles stop within the earth's crust, whether they are slowed by interstellar plasmas, or the signal in a truly calorimetric measurement (measuring temperature rises along the trajectory), etc. Most of our successful detection techniques depend upon the promotion of ground state electrons into states which lie above some energy gap in the material of the detector: electrons must be knocked completely free from the gas atoms in a proportional chamber gas, electrons must be promoted to a higher band in solid scintillator plastics. These processes are generically identified as ionization

Inelastic vibrational bulk and surface losses of swift electrons in ionic nanostructures

Science.gov (United States)

Hohenester, Ulrich; Trügler, Andreas; Batson, Philip E.; Lagos, Maureen J.

2018-04-01

In a recent paper [Lagos et al., Nature (London) 543, 533 (2017), 10.1038/nature21699] we have used electron energy loss spectroscopy with sub-10 meV energy and atomic spatial resolution to map optical and acoustic, bulk and surface vibrational modes in magnesium oxide nanocubes. We found that a local dielectric description works well for the simulation of aloof geometries, similar to related work for surface plasmons and surface plasmon polaritons, while for intersecting geometries such a description fails to reproduce the rich spectral features associated with excitation of bulk acoustic and optical phonons. To account for scatterings with a finite momentum exchange, in this paper we investigate molecular and lattice dynamics simulations of bulk losses in magnesium-oxide nanocubes using a rigid-ion description and investigate the loss spectra for intersecting electron beams. From our analysis we can evaluate the capability of electron energy loss spectroscopy for the investigation of phonon modes at the nanoscale, and we discuss shortcomings of our simplified approach as well as directions for future investigations.

A technique for determining electron losses for a 20 MeV microtron

International Nuclear Information System (INIS)

Harisha, P.; Nayak, A.R.; Mehta, S.K.; Soni, H.C.; Siddappa, K.

1999-01-01

A 22 orbit, 20 MeV electron microtron is used as a preaccelerator for the 700 MeV booster synchrotron at INDUS-1, CAT, Indore. Estimation of electron losses at the RF cavity from each orbit is important in obtaining the radiation doses from the body of the microtron. Radiation mapping of the microtron can be used to estimate these loss terms as an alternate to actual measurement by using a measuring probe. (author)

Multi-Point Measurements to Characterize Radiation Belt Electron Precipitation Loss

Science.gov (United States)

Blum, L. W.

2017-12-01

Multipoint measurements in the inner magnetosphere allow the spatial and temporal evolution of various particle populations and wave modes to be disentangled. To better characterize and quantify radiation belt precipitation loss, we utilize multi-point measurements both to study precipitating electrons directly as well as the potential drivers of this loss process. Magnetically conjugate CubeSat and balloon measurements are combined to estimate of the temporal and spatial characteristics of dusk-side precipitation features and quantify loss due to these events. To then understand the drivers of precipitation events, and what determines their spatial structure, we utilize measurements from the dual Van Allen Probes to estimate spatial and temporal scales of various wave modes in the inner magnetosphere, and compare these to precipitation characteristics. The structure, timing, and spatial extent of waves are compared to those of MeV electron precipitation during a few individual events to determine when and where EMIC waves cause radiation belt electron precipitation. Magnetically conjugate measurements provide observational support of the theoretical picture of duskside interaction of EMIC waves and MeV electrons leading to radiation belt loss. Finally, understanding the drivers controlling the spatial scales of wave activity in the inner magnetosphere is critical for uncovering the underlying physics behind the wave generation as well as for better predicting where and when waves will be present. Again using multipoint measurements from the Van Allen Probes, we estimate the spatial and temporal extents and evolution of plasma structures and their gradients in the inner magnetosphere, to better understand the drivers of magnetospheric wave characteristic scales. In particular, we focus on EMIC waves and the plasma parameters important for their growth, namely cold plasma density and cool and warm ion density, anisotropy, and composition.

Electron loss process and cross section of multiply charged ions by neutral atoms

International Nuclear Information System (INIS)

Karashima, S.; Watanabe, T.

1985-01-01

The significance of experimental and theoretical results on the electron loss and capture of ions in matter plays an important role in the charge equilibrium problems of fusion plasma physics and of accelerator physics. In the report, we calculate electron stripping cross section by using the binary encounter approximation (BEA). Our treatment of the electron loss process is based on BEA, in which the nucleus of B screened by the surrounding electrons collides with electrons in the ion A sup(q+). The basic approximation in EBA is that the ion interacts with only one electron or nucleus of the target atom at a time. In the calculation for Li sup(2+) + H, we have found that EBA will give approximately reliable results. (Mori, K.)

Simulation of electron energy loss spectra of nanomaterials with linear-scaling density functional theory

International Nuclear Information System (INIS)

Tait, E W; Payne, M C; Ratcliff, L E; Haynes, P D; Hine, N D M

2016-01-01

Experimental techniques for electron energy loss spectroscopy (EELS) combine high energy resolution with high spatial resolution. They are therefore powerful tools for investigating the local electronic structure of complex systems such as nanostructures, interfaces and even individual defects. Interpretation of experimental electron energy loss spectra is often challenging and can require theoretical modelling of candidate structures, which themselves may be large and complex, beyond the capabilities of traditional cubic-scaling density functional theory. In this work, we present functionality to compute electron energy loss spectra within the onetep linear-scaling density functional theory code. We first demonstrate that simulated spectra agree with those computed using conventional plane wave pseudopotential methods to a high degree of precision. The ability of onetep to tackle large problems is then exploited to investigate convergence of spectra with respect to supercell size. Finally, we apply the novel functionality to a study of the electron energy loss spectra of defects on the (1 0 1) surface of an anatase slab and determine concentrations of defects which might be experimentally detectable. (paper)

URCA neutrino-loss rates under conditions found in the carbon-oxygen cores of intermediate-mass stars

International Nuclear Information System (INIS)

Iben, I. Jr.

1978-01-01

In the hope of uncovering additional Urca-active nuclei that might appear during carbon burning in the electron-degenerate carbon-oxygen core of an asymptotic-branch star and avert a thermonuclear runaway, a nuclear-reaction matrix connecting 244 nuclear species has been constructed. Analytic expressions for rates of all relevant β-transitions are also presented and used. It is shown that in matter which is composed initially of elements in a solar-system distribution and which has undergone first complete hydrogen burning and then complete helium burning, neutrino-loss rates due to 11 Urca pairs either rival or exceed neutrino losses predicted by the charge- and neutral-current theories of weak interactions. Most remarkably, no new Urca pairs of any consequence appear as a result of several thousand reactions that are allowed to occur during carbon burning. The dominant Urca-loss rates are still due to the pairs 21 F- 21 Ne, 23 Ne- 23 Na, 25 Na- 25 Mg, and 25 Ne- 25 Na, as in matter containing a solar-system distribution of elements that has undergone prior processing during hydrogen- and helium-burning phases. The abundances of these Urca-active pairs are enhanced by one to three orders of magnitude as a consequence of carbon-burning reactions

Acceleration and loss of relativistic electrons during small geomagnetic storms.

Science.gov (United States)

Anderson, B R; Millan, R M; Reeves, G D; Friedel, R H W

2015-12-16

Past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms ( D s t  > -50 nT) have not been statistically characterized. In this timely study, given the current weak solar cycle, we identify 342 small storms from 1989 through 2000 and quantify the corresponding change in relativistic electron flux at geosynchronous orbit. Surprisingly, small storms can be equally as effective as large storms at enhancing and depleting fluxes. Slight differences exist, as small storms are 10% less likely to result in flux enhancement and 10% more likely to result in flux depletion than large storms. Nevertheless, it is clear that neither acceleration nor loss mechanisms scale with storm drivers as would be expected. Small geomagnetic storms play a significant role in radiation belt relativistic electron dynamics and provide opportunities to gain new insights into the complex balance of acceleration and loss processes.

Absolute single electron loss in collisions of Ar+ with various atoms

Science.gov (United States)

Reyes, P. G.; Martínez, H.; Castillo, F.

2001-07-01

Absolute differential and total cross sections for single electron loss were measured for Ar+ ions on various atoms in the energy range of 1.5 to 5.0 keV. The laboratory angular scan for the distributions ranged from -2.5 to 2.5 degrees. The measured differential cross sections have been integrated over the experimental angular range providing absolute total cross sections. The behavior of the total electron loss cross sections with the target atomic number, Zt, shows different dependences as the collision energy increases. In all cases it displays a saturation as Zt increases.

Loss and thermal model for power semiconductors including device rating information

DEFF Research Database (Denmark)

Ma, Ke; Bahman, Amir Sajjad; Beczkowski, Szymon

2014-01-01

The electrical loading and device rating are both important factors that determine the loss and thermal behaviors of power semiconductor devices. In the existing loss and thermal models, only the electrical loadings are focused and treated as design variables, while the device rating is normally...

Atomic column resolved electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Duscher, G.; Pennycook, S.J.; Browning, N.D.

1998-01-01

Spatially resolved electron energy-loss spectroscopy (EELS) is rapidly developing into a unique and powerful tool to characterize internal interfaces. Because atomic column resolved Z-contrast imaging can be performed simultaneously with EELS in the scanning transmission electron microscope, this combination allows the atomic structure to be correlated with the electronic structure, and thus the local properties of interfaces or defects can be determined directly. However, the ability to characterize interfaces and defects at that level requires not only high spatial resolution but also the exact knowledge of the beam location, from where the spectrum is obtained. Here we discuss several examples progressing from cases where the limitation in spatial resolution is given by the microscopes or the nature of the sample, to one example of impurity atoms at a grain boundary, which show intensity and fine structure changes from atomic column to atomic column. Such data can be interpreted as changes in valence of the impurity, depending on its exact site in the boundary plane. Analysis ofthis nature is a valuable first step in understanding the microscopic structural, optical and electronic properties of materials. (orig.)

Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng, E-mail: dssu@imr.ac.cn [Shenyang National Laboratory of Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016 (China)

2015-12-07

The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials.

Evaluating the Role and Effects of Precipitation on Relativistic Electron Losses during Storms

Science.gov (United States)

Chen, Y.; Fu, X.

2016-12-01

Theoretic studies have suggested that during storm times various waves (e.g., whistler-mode chorus and electromagnetic ion cyclotron waves) can cause significant precipitation of relativistic ( MeV) electrons that are originally trapped inside the outer radiation belt. However, the role of precipitation and its quantitative contribution to the losses of outer-belt electrons remain open questions. In this study, we tackle these questions by systemically examining the latest wave and electron in-situ, simultaneous observations made at different altitudes by Van Allen Probes from near equator, NOAA POES at low Earth orbits near/across electron loss cone, and BARREL under the mesosphere. After calibrating with DEMTER observations, we first confirm and quantify the response of POES MEPED proton channels to MeV electrons. Next, we identify a list of precipitation events from BARREL and POES measurements, examine the temporal adn spatial relation between the two data sets, and estimate the intensities of electron precipitation with ascertained uncertainties. Then, from Van Allen Probes data, we select another list of dropout events during storms. By cross checking the above two lists, we are able to determine the causal relation between precipitation and dropouts through individual case as well as statistical studies so as to quantify the contributions from precipitation. This study mainly focuses on the relatively small L-shells with positive phase space density radial gradient in order to alleviate the impacts from outward radial diffusion and adiabatic effects. Based upon the recent discovery of cross-energy cross-pitch angle coherence, we pay particular attention to the cross-term diffusions which may account for the extra "loss" needed by observed MeV electron dropouts. Results from this observational study will advance our knowledge on the loss mechanism of outer-belt electrons, and thus lay down another stepping stone towards high-fidelity physics-based models for

Electronic energy loss of fast molecules in matter

International Nuclear Information System (INIS)

Steinbeck, J.

1975-06-01

In high velocity collisions of molecular ions the correlated motion influence of the ion cores on the electronic energy loss is investigated. The stopping power in first Born approximation for a random arrangement of target atoms can be formulated in terms of the inelastic electronic structure factor. In treating the target atoms in Hartree-Fock approximation each electron can be regarded as stopping the ion independent of all other electrons without restriction by the Pauli principle. A second equivalent formulation of the stopping power leads to the dielectric function of the target. The results are applied to the stopping of H 2 + -ions. For vanishing distance between the two protons the stopping power per particle is twice that for single proton collisions. For distances in the order of the Bohr radius the correlated stopping power may even be smaller than for uncorrelated protons. With increasing distances the correlation influence vanishes. The stopping of H 2 + -ions in C, Si and Ge is discussed using Clementi wave functions for the core electrons and a free electron approximation with Lindhard's dielectric function for the valence electrons. The comparison with the only experimental result available for H 2 + in C at 300 keV yields qualitative agreement. (orig.) [de

Neutrino energy loss rate in a stellar plasma

International Nuclear Information System (INIS)

Esposito, S.; Mangano, G.; Miele, G.; Picardi, I.; Pisanti, O.

2003-01-01

We review the purely leptonic neutrino emission processes, contributing to the energy loss rate of the stellar plasma. We perform a complete analysis up to the first order in the electromagnetic coupling constant. In particular the radiative electromagnetic corrections, at order α, to the process e + e - →νν-bar at finite density and temperature have been computed. This process gives one of the main contributions to the cooling of stellar interior in the late stages of star evolution. As a result of the analysis we find that the corrections affect the energy loss rate, computed at tree level, by a factor (-4-1)% in the temperature and density region where the pair annihilation is the most efficient cooling mechanism

Particle Rate and Host Accelerator Beam Loss on the MICE Experiment

Energy Technology Data Exchange (ETDEWEB)

Dobbs, Adam James [Imperial College, London (United Kingdom)

2011-10-01

A study is presented of particle rates in the MICE Muon Beamline and their relationship to beam loss produced in ISIS. A brief overview of neutrino physics is presented, together with a discussion on the Neutrino Factory as a motivation for MICE. An overview of MICE itself is then presented, highlighting the need for a systematic understanding of the relationship between the MICE target parameters, ISIS beam loss, and MICE particle rate. The variation of beam loss with target depth is examined and observed to be non-linear. The variation of beam loss with respect to the target dip time in the ISIS cycle is examined and observed to be approximately linear for dip times between 11.1 ms and 12.6 ms after ISIS injection, before tailing at earlier dip times. The variation of beam loss with particle rate is also observed to follow an approximately linear relationship from 0.05 V.ms to 4.7 V.ms beam loss, with a further strong indication that this continues up to 7.1 V.ms. Particle identification using time-of-flight data is used to give an insight into the relative abundances of each particle species present in the MICE beam. Estimates of muon rate are then produced as a function of beam loss. At a level of 2 V.ms beam loss ~10.9 muons per spill for a 3.2 ms spill with negative π → μ optics, and ~31.1 muons per 1 ms spill with positive π → μ optics are observed. Simulations using the ORBIT particle tracking code of the beam loss distributions around the ISIS ring, caused by the MICE target, are also presented and the implications for MICE running discussed.

Impact of stand-by energy losses in electronic devices on smart network performance

Directory of Open Access Journals (Sweden)

Mandić-Lukić Jasmina S.

2012-01-01

Full Text Available Limited energy resources and environmental concerns due to ever increasing energy consumption, more and more emphasis is being put on energy savings. Smart networks are promoted worldwide as a powerful tool used to improve the energy efficiency through consumption management, as well as to enable the distributed power generation, primarily based on renewable energy sources, to be optimally explored. To make it possible for the smart networks to function, a large number of electronic devices is needed to operate or to be in their stand-by mode. The consumption of these devices is added to the consumption of many other electronic devices already in use in households and offices, thus giving rise to the overall power consumption and threatening to counteract the primary function of smart networks. This paper addresses the consumption of particular electronic devices, with an emphasis placed on their thermal losses when in stand-by mode and their total share in the overall power consumption in certain countries. The thermal losses of electronic devices in their stand-by mode are usually neglected, but it seems theoretically possible that a massive increase in their number can impact net performance of the future smart networks considerably so that above an optimum level of energy savings achieved by their penetration, total consumption begins to increase. Based on the current stand-by energy losses from the existing electronic devices, we propose that the future penetration of smart networks be optimized taking also into account losses from their own electronic devices, required to operate in stand-by mode.

Electron energy loss spectroscopy of gold nanoparticles on graphene

International Nuclear Information System (INIS)

DeJarnette, Drew; Roper, D. Keith

2014-01-01

Plasmon excitation decay by absorption, scattering, and hot electron transfer has been distinguished from effects induced by incident photons for gold nanoparticles on graphene monolayer using electron energy loss spectroscopy (EELS). Gold nano-ellipses were evaporated onto lithographed graphene, which was transferred onto a silicon nitride transmission electron microscopy grid. Plasmon decay from lithographed nanoparticles measured with EELS was compared in the absence and presence of the graphene monolayer. Measured decay values compared favorably with estimated radiative and non-radiative contributions to decay in the absence of graphene. Graphene significantly enhanced low-energy plasmon decay, increasing mode width 38%, but did not affect higher energy plasmon or dark mode decay. This decay beyond expected radiative and non-radiative mechanisms was attributed to hot electron transfer, and had quantum efficiency of 20%, consistent with previous reports

The distribution of infered energetic electron loss with respect to plasmapause location: BARREL results.

Science.gov (United States)

Halford, A. J.; Malaspina, D.; Sibeck, D. G.

2017-12-01

One of the long outstanding challenges of understanding the inner magnetosphere is accurately describing radiation belt dynamics. This enterprise can seem daunting as many have stated: "if you've seen one storm you've seen one storm". And although much progress has been made over the last half century since the discovery of the radiation belts, there is still ongoing debate about the relative importance of different loss and source mechanisms. Here we will consider one part of radiation belt dynamics, the loss of electrons ( 30 keV to MeV) to the upper atmosphere and endeavor to identify the relative importance of the different loss mechanisms. As demonstrated in often used cartoon diagrams, and previous studies, many radiation belt loss mechanisms such as chorus, hiss, and EMIC waves are thought to have specific MLT and L dependencies as well as dependence on geomagnetic conditions. Many of these loss mechanisms are identifiable through the energies and time scales in which they precipitate electrons. Thus we expect that the observed electron precipiation should follow similar MLT and L patterns as what caused the loss and not show something completely unexpected such as Atlantis rising out of the Columbia River. Here we will examine the location and geomagnetic conditions under which the Balloon Array for Relativistic Radiation Belt Electron Loss (BARREL) inferred radiation belt electron precipitation. The BARREL mission consisted of 4 campaigns, two in Antarctica and 2 in Sweden, for a total of 55 launches. The flights conducted in Antarctica took advantage of the circumpolar winds allowing for the payloads to cross a range of L-values from L > 2.5 onto open field lines, while the Swedish campaigns were held during turn around where the balloons stayed near L = 5.8. We will present the distribution of precipitation with respect to L and MLT as well as with respect to the boundary of the plasmapause as new work has shown that this boundary clearly separates

Improving patient access to prevent sight loss: ophthalmic electronic referrals and communication (Scotland).

Science.gov (United States)

Khan, A A; Mustafa, M Z; Sanders, R

2015-02-01

With the number of people with sight loss predicted to double to four million people in the UK by the year 2050, preventable visual loss is a significant public health issue. Sight loss is associated with an increased risk of falls, accidents and depression and evidence suggests that 50% of sight loss can be avoided. Timely diagnosis is central to the prevention of sight loss. Access to care can be a limiting factor in preventable cases. By improving referrals and access to hospital eye services it is possible to treat and minimise the number of patients with preventable sight loss and the impact this has on wider society. In 2005, NHS Fife took part in a flagship pilot funded by the Scottish government e-health department to evaluate the feasibility, safety, clinical effectiveness, and cost of electronic referral with images of patients directly from community optometrists to Hospital Eye Service (HES). The pilot study showed that electronic referral was feasible, fast, safe, and obviated the need for outpatient appointments in 128 (37%) patients with a high patient satisfaction. The results of the pilot study were presented and in May 2007, the electronic referral system was rolled out regionally in southeast Scotland. Referrals were accepted at a single site with vetting by a trained team and appointments were allocated within 48 hours. Following the implementation of electronic referral, waiting times were reduced from a median of 14 to 4 weeks. Significantly fewer new patients were seen (7462 vs 8714 [p electronic communication between community optometry practices and hospital eye departments. Five electronic forms were specifically designed for cataract, glaucoma, macula, paediatric and general ophthalmic disease. A Virtual Private Network was created which enabled optometrists to connect to the Scottish clinical information gateway system and send referrals to hospital and receive referral status feedback. Numerous hurdles have been encountered and overcome

Simulation of Probe Position-Dependent Electron Energy-Loss Fine Structure

Energy Technology Data Exchange (ETDEWEB)

Oxley, M. P.; Kapetanakis, M. D.; Prange, Micah P.; Varela, M.; Pennycook, Stephen J.; Pantelides, Sokrates T.

2014-03-31

We present a theoretical framework for calculating probe-position-dependent electron energy-loss near-edge structure for the scanning transmission electron microscope by combining density functional theory with dynamical scattering theory. We show how simpler approaches to calculating near-edge structure fail to include the fundamental physics needed to understand the evolution of near-edge structure as a function of probe position and investigate the dependence of near-edge structure on probe size. It is within this framework that density functional theory should be presented, in order to ensure that variations of near-edge structure are truly due to local electronic structure and how much from the diffraction and focusing of the electron beam.

Two-body loss rates for reactive collisions of cold atoms

Science.gov (United States)

Cop, C.; Walser, R.

2018-01-01

We present an effective two-channel model for reactive collisions of cold atoms. It augments elastic molecular channels with an irreversible, inelastic loss channel. Scattering is studied with the distorted-wave Born approximation and yields general expressions for angular momentum resolved cross sections as well as two-body loss rates. Explicit expressions are obtained for piecewise constant potentials. A pole expansion reveals simple universal shape functions for cross sections and two-body loss rates in agreement with the Wigner threshold laws. This is applied to collisions of metastable 20Ne and 21Ne atoms, which decay primarily through exothermic Penning or associative ionization processes. From a numerical solution of the multichannel Schrödinger equation using the best currently available molecular potentials, we have obtained synthetic scattering data. Using the two-body loss shape functions derived in this paper, we can match these scattering data very well.

Overnight weight loss: relationship with sleep structure and heart rate variability

OpenAIRE

Walter Moraes; Dalva Poyares; Christian Guilleminault; Agostinho Rosa; Marco Tulio Mello; Adriana Rueda; Sergio Tufik

2008-01-01

Background: Weight loss can be caused by a loss of body mass due to metabolism and by water loss as unsensible water loss, sweating, or excretion in feces and urine. Although weight loss during sleep is a well-known phenomenon, it has not yet been studied in relation to sleep structure or autonomic tonus during sleep. Our study is proposed to be a first step in assessing the relationship between overnight weight loss, sleep structure, and HRV (heart rate variability) parameters.Methods: Twent...

Exchange-rate forecasts and asymmetric loss: empirical evidence for the yen/dollar exchange rate

DEFF Research Database (Denmark)

Stadtmann, Georg; Pierdzioch; Rülke

2012-01-01

We used the yen/dollar exchange-rate forecasts of the Wall Street Journal (WSJ) poll to analyse whether exchange-rate forecasters have an asymmetric loss function. To this end, we applied an approach recently developed by Elliott et al. (2005). We found that only few forecasters seem to form...

Multivariate statistical analysis of electron energy-loss spectroscopy in anisotropic materials

International Nuclear Information System (INIS)

Hu Xuerang; Sun Yuekui; Yuan Jun

2008-01-01

Recently, an expression has been developed to take into account the complex dependence of the fine structure in core-level electron energy-loss spectroscopy (EELS) in anisotropic materials on specimen orientation and spectral collection conditions [Y. Sun, J. Yuan, Phys. Rev. B 71 (2005) 125109]. One application of this expression is the development of a phenomenological theory of magic-angle electron energy-loss spectroscopy (MAEELS), which can be used to extract the isotropically averaged spectral information for materials with arbitrary anisotropy. Here we use this expression to extract not only the isotropically averaged spectral information, but also the anisotropic spectral components, without the restriction of MAEELS. The application is based on a multivariate statistical analysis of core-level EELS for anisotropic materials. To demonstrate the applicability of this approach, we have conducted a study on a set of carbon K-edge spectra of multi-wall carbon nanotube (MWCNT) acquired with energy-loss spectroscopic profiling (ELSP) technique and successfully extracted both the averaged and dichroic spectral components of the wrapped graphite-like sheets. Our result shows that this can be a practical alternative to MAEELS for the study of electronic structure of anisotropic materials, in particular for those nanostructures made of layered materials

Loss mechanism of the superthermal electrons across the separatrix into the scrape-off layer in DIVA

International Nuclear Information System (INIS)

Yamamoto, Shin; Sengoku, Seio; Kimura, Haruyuki; Shimomura, Yasuo; Maeda, Hikosuke

1977-10-01

Behavior of superthermal electrons is investigated by using X-ray measurement and electrostatic energy analyser. Superthermal electrons are divided into two groups; i.e. high energy electrons (10 keV - 100 keV) and epithermal electrons (150 eV - 500 eV). Loss flux of the epithermal electrons is obtained and their loss is shown to be explained by destruction of magnetic surfaces near the separatrix due to non-axisymmetric perturbations. Two-dimensional path of high energy electrons is obtained and the effects of non-axisymmetric perturbations on the drift surface are described. (auth.)

Characteristic electron energy losses in monoatomic antimony films on (110) and (112) tungsten faces

International Nuclear Information System (INIS)

Gorodetskij, D.A.; Gorchinskij, A.D.; Shevlyakov, S.A.

1981-01-01

Complex investigations of antimony condensation on a monoatomical clean surface of tungsten monocrystals are carried out. The completion of a physical antimony monolayer has been controlled by the methods of Auger-electron spectroscopy and slow electron diffraction. It is shown that at submonolayer coatings a collectivization of valent electrons occurs leading to appearance of peaks of surface and volumetric plasmons in the energy losses spectrum. The anomalous cencentrational dependence of antimony ionization peak intensity has been found. The origin of previously unexplored peaks in the energy losses spectrum is discussed [ru

High resolution electron energy loss spectroscopy of clean and hydrogen covered Si(001) surfaces: first principles calculations.

Science.gov (United States)

Patterson, C H

2012-09-07

Surface phonons, conductivities, and loss functions are calculated for reconstructed (2×1), p(2×2) and c(4×2) clean Si(001) surfaces, and (2×1) H and D covered Si(001) surfaces. Surface conductivities perpendicular to the surface are significantly smaller than conductivities parallel to the surface. The surface loss function is compared to high resolution electron energy loss measurements. There is good agreement between calculated loss functions and experiment for H and D covered surfaces. However, agreement between experimental data from different groups and between theory and experiment is poor for clean Si(001) surfaces. Formalisms for calculating electron energy loss spectra are reviewed and the mechanism of electron energy losses to surface vibrations is discussed.

A Hall-current model of electron loss after POS opening into high-impedance loads

International Nuclear Information System (INIS)

Greenly, J.B.

1989-01-01

The author discusses how a self-consistent relativistic model of laminar Hall (E x B) electron flow across a POS plasma allows a loss mechanism after opening even in a strongly magnetically-insulated line, downstream of the remaining POS plasma. Opening is assumed to occur at the cathode, either by erosion or push-back. The loss results only when a large voltage appears after opening into a high impedance load. Then the difference in potential between the plasma, which is near anode potential, and the cathode results in an axial component of E at the load end of the plasma, which supports an E x B drift of electrons across the gap. The analytic model predicts that this loss should increase with higher voltage after opening, and could be eliminated only by removing the plasma from the gap, or eliminating cathode electron emission (both difficult), or by confining this downstream electron flow with an applied magnetic field

Use of a silicon surface-barrier detector for measurement of high-energy end loss electrons in a tandem mirror

International Nuclear Information System (INIS)

Saito, T.; Kiwamoto, Y.; Honda, T.; Kasugai, A.; Kurihara, K.; Miyoshi, S.

1991-01-01

An apparatus for the measurement of high-energy electrons (10--500 keV) with a silicon surface-barrier detector is described. The apparatus has special features. In particular, a fast CAMAC transient digitizer is used to directly record the wave form of a pulse train from the detector and then pulse heights are analyzed with a computer instead of on a conventional pulse height analyzer. With this method the system is capable of detecting electrons with a count rate as high as ∼300--400 kilocounts/s without serious deterioration of performance. Moreover, piled up signals are reliably eliminated from analysis. The system has been applied to measure electron-cyclotron-resonance-heating-induced end loss electrons in the GAMMA 10 tandem mirror and has yielded information relating to electron heating and diffusion in velocity space

Distributions of energy losses of electrons and pions in the CBM TRD

International Nuclear Information System (INIS)

Akishina, E.P.; Akishina, T.P.; Ivanov, V.V.; Denisova, O.Yu.

2007-01-01

The distributions of energy losses of electrons and pions in the TRD detector of the CBM experiment are considered. We analyze the measurements of the energy deposits in one-layer TRD prototype obtained during the test beam (GSI, Darmstadt, February 2006) and Monte Carlo simulations for the n-layered TRD realized with the help of GEANT in frames of the CBM ROOT. We show that 1) energy losses both for real measurements and GEANT simulations are approximated with a high accuracy by a log-normal distribution for π and a weighted sum of two log-normal distributions for e; 2) GEANT simulations noticeably differ from real measurements and, as a result, we have a significant loss in the efficiency of the e/π identification. A procedure to control and correct the process of the energy deposit of electrons in the TRD is developed

Electron-ion recombination rates for merged-beams experiments

International Nuclear Information System (INIS)

Pajek, M.

1994-01-01

Energy dependence of the electron-ion recombination rates are studied for different recombination processes (radiative recombination, three-body recombination, dissociative recombination) for Maxwellian relative velocity distribution of arbitrary asymmetry. The results are discussed in context of the electron-ion merged beams experiments in cooling ion storage rings. The question of indication of a possible contribution of the three-body recombination to the measured recombination rates versus relative energy is particularly addressed. Its influence on the electron beam temperature derived from the energy dependence of recombination rate is discussed

Measurement of the radiative cooling rates for high-ionization species of krypton using an electron beam ion trap

International Nuclear Information System (INIS)

Radtke, R.; Biedermann, C.; Fuchs, T.; Fussmann, G.; Beiersdorfer, P.

2000-01-01

We describe a measurement of the radiative cooling rate for krypton made at the Berlin electron beam ion trap (EBIT). The EBIT was tuned to a charge-state distribution approaching the ionization balance of a plasma at a temperature of about 5 keV. To determine the cooling rate, we made use of EBIT's capabilities to sample a wide range of electron-beam energies and distinguish between different radiation channels. We have measured the x-ray emission from bremsstrahlung, radiative recombination, dielectronic recombination, and line radiation following electron-impact excitation. The dominant contribution to the cooling rate is made by the n=3-2, n=4-2,... x rays of the L-shell spectra of krypton, which produce more than 75% of the total radiation loss. A difference with theoretical calculations is noted for the measured total cooling rate. The predicted values are lower by a factor of 1.5-2, depending on the theoretical model. For our measurement of the cooling rate, we estimate an uncertainty interval of 22-30 %. (c) 2000 The American Physical Society

Some thoughts on source monochromation and the implications for electron energy loss spectroscopy

CERN Document Server

Brydson, R; Brown, A

2003-01-01

We briefly outline the factors determining the intrinsic widths of features in electron energy loss near edge structure (ELNES) measured by electron energy loss spectroscopy (EELS) in the transmission electron microscope (TEM). We have made estimates of the differing contributions of both the initial and final state lifetime effects in the ELNES ionisation processes and also show how these may be combined with the instrumental energy resolution. We discuss the potential benefits of source monochromation for ELNES measurements via a comparison of these theoretical estimates with experimental spectra from the literature. We show that for certain core level excitations, solid state broadening mechanisms may be the fundamental limiting factor for resolving fine detail in ELNES. (orig.)

A Numerical Study of Water Loss Rate Distributions in MDCT-based Human Airway Models

Science.gov (United States)

Wu, Dan; Miyawaki, Shinjiro; Tawhai, Merryn H.; Hoffman, Eric A.; Lin, Ching-Long

2015-01-01

Both three-dimensional (3D) and one-dimensional (1D) computational fluid dynamics (CFD) methods are applied to study regional water loss in three multi-detector row computed-tomography (MDCT)-based human airway models at the minute ventilations of 6, 15 and 30 L/min. The overall water losses predicted by both 3D and 1D models in the entire respiratory tract agree with available experimental measurements. However, 3D and 1D models reveal different regional water loss rate distributions due to the 3D secondary flows formed at bifurcations. The secondary flows cause local skewed temperature and humidity distributions on inspiration acting to elevate the local water loss rate; and the secondary flow at the carina tends to distribute more cold air to the lower lobes. As a result, the 3D model predicts that the water loss rate first increases with increasing airway generation, and then decreases as the air approaches saturation, while the 1D model predicts a monotonic decrease of water loss rate with increasing airway generation. Moreover, the 3D (or 1D) model predicts relatively higher water loss rates in lower (or upper) lobes. The regional water loss rate can be related to the non-dimensional wall shear stress (τ*) by the non-dimensional mass transfer coefficient (h0*) as h0* = 1.15 τ*0.272, R = 0.842. PMID:25869455

Enhanced O2 Loss at Mars Due to an Ambipolar Electric Field from Electron Heating

Science.gov (United States)

Ergun, R. E.; Andersson, L. A.; Fowler, C. M.; Woodson, A. K.; Weber, T. D.; Delory, G. T.; Andrews, D. J.; Eriksson, A. I.; Mcenulty, T.; Morooka, M. W.;

Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

Science.gov (United States)

Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.; Neves, R. F. C.; Lopes, M. C. A.; de Oliveira, E. M.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Blanco, F.; García, G.; Lima, M. A. P.; Jones, D. B.

2015-10-01

The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5-10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

International Nuclear Information System (INIS)

Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.

2015-01-01

The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range

Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

Energy Technology Data Exchange (ETDEWEB)

Ferreira da Silva, F.; Lange, E. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Jones, N. C.; Hoffmann, S. V. [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Århus C (Denmark); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Institut de Chimie-Bât. B6C, Université de Liège, B-4000 Liège 1 (Belgium); Brunger, M. J., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); and others

2015-10-14

The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

Annual rate of hearing loss falls after fractionated stereotactic irradiation for vestibular schwannoma

International Nuclear Information System (INIS)

Sakamoto, Touru; Shirato, Hiroki; Takeichi, Norihito; Aoyama, Hidefumi; Fukuda, Satoshi; Miyasaka, Kazuo

2001-01-01

Purpose: The rate of hearing loss in a population before and after irradiation was investigated to determine the effect of irradiation on hearing impairment. Methods and materials: In 72 patients with vestibular schwannoma who received fractionated stereotactic irradiation from 1992 to 1999, 21 had had their hearing levels examined 3 months or more before the treatment. The mean time between the initial examination and treatment was 18.6 months (range: 3-89 months), and the mean time between treatment and the last follow-up was 24.2 months (12-69 months). Thirty-six to 50 Gy in 20-25 fractions over 5 to 6 weeks was given using an X-ray beam from a linear accelerator. Pure tone average (PTA) was measured using the mean hearing level at five frequencies, and the annual rate of hearing loss was defined as [(hearing loss in PTA(dB))/(follow-up period (months)x12)]. Results: The actual cumulative curve of decrease in tumor size of 2 mm or more was 38.3% at 2 years and 80.0% at 3 years. The mean of hearing loss in PTA was 11.6±10.3 dB (-1 to 35 dB) from the initial examination to the start of irradiation and 11.9±14.4 dB (-14 to 37 dB) from the start of irradiation to the last follow-up. The mean annual rates of hearing loss before irradiation and in the 1st, 2nd, 3rd and 4th years after irradiation were, respectively, 18.6, 11.2, 6.2, 5.1, and 5.0 dB/year. The annual rates of hearing loss in the 2nd year (P=0.025) and 3rd year (P=0.018) were significantly slower than the rate before irradiation. Conclusions: The mean annual rate of hearing loss was higher before irradiation than after irradiation, and hearing loss slowed rather than accelerated after irradiation. Although hearing loss after the treatment was usually permanent, fractionated stereotactic irradiation was suggested to be effective to lower the rate of hearing loss

Electronic properties of Mn-phthalocyanine–C60 bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Roth, Friedrich; Herzig, Melanie; Knupfer, Martin; Lupulescu, Cosmin; Darlatt, Erik; Gottwald, Alexander; Eberhardt, Wolfgang

2015-01-01

The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C 60 (MnPc:C 60 ) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C 60 . Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C 60 bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C 60 to MnPc thin films

Characteristic electron energy loss in lanthanum films adsorbed on tungsten (110) single crystal

International Nuclear Information System (INIS)

Gorodetskij, D.A.; Gorchinskij, A.D.; Kobylyanskij, A.V.

1988-01-01

The spectrum of electron energy loss (ELS) in a wide range of energy loss 0-150 eV has been studied for La films adsorbed on W(110) single crystal with the coverage Θ from submonolayer to a few monolayers. The concentration dependence of loss energy peaks amplitude of different nature has been studied for the adsorption of rare earth element on refractory substrate. It has been shown that the essential information for the interpretation of the energy loss nature may be obtained by the investigation of such dependences for La adsorption on W(110). It is found that the surface and bulk plasmons peaks appear in ELS of La-W(110) system before the completion of the physical monolayer. Thus, the collectivization of valence electrons in the rare earth element film at the transition metal surface ensues for the submonolayer coverage like in the case of collective processes in alkali and alkaline earth element films

Electronic energy loss spectra from mono-layer to few layers of phosphorene

International Nuclear Information System (INIS)

Mohan, Brij; Thakur, Rajesh; Ahluwalia, P. K.

2016-01-01

Using first principles calculations, electronic and optical properties of few-layers phosphorene has been investigated. Electronic band structure show a moderate band gap of 0.9 eV in monolayer phosphorene which decreases with increasing number of layers. Optical properties of few-layers of phosphorene in infrared and visible region shows tunability with number of layers. Electron energy loss function has been plotted and huge red shift in plasmonic behaviours is found. These tunable electronic and optical properties of few-layers of phosphorene can be useful for the applications of optoelectronic devices.

Electronic energy loss spectra from mono-layer to few layers of phosphorene

Energy Technology Data Exchange (ETDEWEB)

Mohan, Brij, E-mail: brijmohanhpu@yahoo.com; Thakur, Rajesh; Ahluwalia, P. K. [Department of Physics, Himachal Pradesh University, Shimla (HP) India 171005 (India)

2016-05-23

Using first principles calculations, electronic and optical properties of few-layers phosphorene has been investigated. Electronic band structure show a moderate band gap of 0.9 eV in monolayer phosphorene which decreases with increasing number of layers. Optical properties of few-layers of phosphorene in infrared and visible region shows tunability with number of layers. Electron energy loss function has been plotted and huge red shift in plasmonic behaviours is found. These tunable electronic and optical properties of few-layers of phosphorene can be useful for the applications of optoelectronic devices.

A Practical Core Loss Model for Filter Inductors of Power Electronic Converters

DEFF Research Database (Denmark)

Matsumori, Hiroaki; Shimizu, Toshihisa; Wang, Xiongfei

2018-01-01

This paper proposes a core loss model for filter inductors of power electronic converters. The model allows a computationally efficient analysis on the core loss of the inductor under the square voltage excitation and the premagnetization condition. First, the core loss of the filter inductor under...... buck chopper excitation is evaluated with the proposed model and compared with the conventional methods. The comparison shows that the proposed method results in a better core loss prediction under the premagnetized condition than that of conventional alternatives. Then, the core loss of the filter...... inductor with the pulsewidth modulated inverter excitation is evaluated, which shows that the proposed model not only accurately predicts the core loss but also identifies the hysteresis loss part. These results demonstrate that the approach can further be used for the development of magnetic materials...

Multiple loss processes of relativistic electrons outside the heart of outer radiation belt during a storm sudden commencement

International Nuclear Information System (INIS)

Yu, J.

2015-01-01

By examining the compression-induced changes in the electron phase space density and pitch angle distribution observed by two satellites of Van Allen Probes (RBSP-A/B), we find that the relativistic electrons (>2 MeV) outside the heart of outer radiation belt (L*≥5) undergo multiple losses during a storm sudden commencement. The relativistic electron loss mainly occurs in the field-aligned direction (pitch angle α < 30° or >150°), and the flux decay of the field-aligned electrons is independent of the spatial location variations of the two satellites. However, the relativistic electrons in the pitch angle range of 30°–150° increase (decrease) with the decreasing (increasing) geocentric distance (|ΔL|<0.25) of the RBSP-B (RBSP-A) location, and the electron fluxes in the quasi-perpendicular direction display energy-dispersive oscillations in the Pc5 period range (2–10 min). The relativistic electron loss is confirmed by the decrease of electron phase space density at high-L shell after the magnetospheric compressions, and their loss is associated with the intense plasmaspheric hiss, electromagnetic ion cyclotron (EMIC) waves, relativistic electron precipitation (observed by POES/NOAA satellites at 850 km), and magnetic field fluctuations in the Pc5 band. Finally, the intense EMIC waves and whistler mode hiss jointly cause the rapidly pitch angle scattering loss of the relativistic electrons within 10 h. Moreover, the Pc5 ULF waves also lead to the slowly outward radial diffusion of the relativistic electrons in the high-L region with a negative electron phase space density gradient.

Quantitative analysis of reflection electron energy loss spectra to determine electronic and optical properties of Fe–Ni alloy thin films

International Nuclear Information System (INIS)

Tahir, Dahlang; Oh, Sukh Kun; Kang, Hee Jae; Tougaard, Sven

2016-01-01

Highlights: • Electronic and optical properties of Fe-Ni alloy thin films grown on Si (1 0 0) were studied via quantitative analyses of reflection electron energy loss spectra (REELS). • The energy loss functions (ELF) are dominated by a plasmon peak at 23.6 eV for Fe and moves gradually to lower energies in Fe-Ni alloys towards the bulk plasmon energy of Ni at 20.5 eV. • Fe has a strong effect on the dielectric and optical properties of Fe-Ni alloy thin films even for an alloy with 72% Ni. Electronic and optical properties of Fe-Ni alloy thin films grown on Si (1 0 0) were studied via quantitative analyses of reflection electron energy loss spectra (REELS). - Abstract: Electronic and optical properties of Fe–Ni alloy thin films grown on Si (1 0 0) by ion beam sputter deposition were studied via quantitative analyses of reflection electron energy loss spectra (REELS). The analysis was carried out by using the QUASES-XS-REELS and QUEELS-ε(k,ω)-REELS softwares to determine the energy loss function (ELF) and the dielectric functions and optical properties by analyzing the experimental spectra. For Ni, the ELF shows peaks around 3.6, 7.5, 11.7, 20.5, 27.5, 67 and 78 eV. The peak positions of the ELF for Fe_2_8Ni_7_2 are similar to those of Fe_5_1Ni_4_9, even though there is a small peak shift from 18.5 eV for Fe_5_1Ni_4_9 to 18.7 eV for Fe_2_8Ni_7_2. A plot of n, k, ε_1, and ε_2 shows that the QUEELS-ε(k,ω)-REELS software for analysis of REELS spectra is useful for the study of optical properties of transition metal alloys. For Fe–Ni alloy with high Ni concentration (Fe_2_8Ni_7_2), ε_1, and ε_2 have strong similarities with those of Fe. This indicates that the presence of Fe in the Fe–Ni alloy thin films has a strong effect.

Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

KAUST Repository

Lopatin, Sergei; Cheng, Bin; Liu, Wei-Ting; Tsai, Meng-Lin; He, Jr-Hau; Chuvilin, Andrey

2017-01-01

The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

KAUST Repository

Lopatin, Sergei

2017-09-01

The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

Quantifying the Rate of Ellipsoid Zone Loss in Stargardt Disease.

Science.gov (United States)

Cai, Cindy X; Light, Jacob G; Handa, James T

2018-02-01

To determine a reliable method of using the ellipsoid zone (EZ) on optical coherence tomography (OCT) to track disease progression in Stardgardt disease (STGD). Retrospective reliability study. STGD patients with genetically confirmed ABCA4 gene mutations seen at the Wilmer Eye Institute with follow-up visits separated by at least 12 months were identified. Spectral-domain optical coherence tomography (SD-OCT) macula volume scans centered at the fovea and fundus autofluorescence (FAF) images were obtained. The area of EZ loss was calculated from the SD-OCT and the area of retinal pigment epithelium (RPE) loss from the FAF. Scans were reanalyzed by the primary grader to assess intragrader reliability, and reanalyzed by a second grader to assess intergrader reliability. Sixteen STGD patients (total of 31 eyes) were followed for a mean of 2 years (range 1-4.7 years). The mean rate of EZ loss, 0.31 ± 0.31 mm 2 /year, was similar to the average rate of RPE loss, 0.33 ± 0.38 mm 2 /year. The average area of EZ loss at the initial examination, 4.18 ± 1.91 mm 2 , was larger than the initial area of RPE loss, 2.25 ± 1.66 mm 2 (P disease progression in STGD. This could be used as a sensitive anatomic outcome measure in clinical trials related to STGD. Copyright © 2017 Elsevier Inc. All rights reserved.

Electron Cloud Simulations of a Proton Storage Ring Using Cold Proton Bunches

International Nuclear Information System (INIS)

Sato, Y.; Holmes, Jeffrey A.; Lee, S.Y.; Macek, R.

2008-01-01

Using the ORBIT code we study the sensitivity of electron cloud properties with respect to different proton beam profiles, the secondary electron yield (SEY) parameter, and the proton loss rate. Our model uses a cold proton bunch to generate primary electrons and electromagnetic field for electron cloud dynamics. We study the dependence of the prompt and swept electron signals vs the bunch charge and the recovery of electron clouds after sweeping on the beam loss rate and the SEY. The simulation results are compared with the experimental data measured at the proton storage ring at the Los Alamos National Laboratory. Our simulations indicate that the fractional proton loss rate in the field-free straight section may be an exponential function of proton beam charge and may also be lower than the averaged fractional proton loss rate over the whole ring.

Mass loss rates of OB stars derived from infrared observations

International Nuclear Information System (INIS)

Tanzi, E.G.; Tarenghi, M.; Panagia, N.

1981-01-01

In this paper the authors report briefly on a study of the mass loss of early type stars in the infrared. Up to now near infrared (1.25 - 4.8 μ) broad band photometry of 70 southern OB stars of various luminosity class has been secured. Program stars have been selected, among those bright enough in the infrared to give a suitable photometric accuracy, in order to cover a wide range of spectral types. 37 stars are found to exhibit emission in excess over a blackbody photospheric continuum, which is interpreted in terms of gas ejected in the form of an accelerated wind. By means of model calculations the corresponding mass loss rates are derived. The obtained values compare well with those determined independently by various authors for stars in common. Their data show that mass loss rates increase with luminosity and are a decreasing function of surface gravity. (Auth.)

First principles study of electronic properties, interband transitions and electron energy loss of α-graphyne

Science.gov (United States)

Behzad, Somayeh

2016-04-01

The electronic and optical properties of α-graphyne sheet are investigated by using density functional theory. The results confirm that α-graphyne sheet is a zero-gap semimetal. The optical properties of the α-graphyne sheet such as dielectric function, refraction index, electron energy loss function, reflectivity, absorption coefficient and extinction index are calculated for both parallel and perpendicular electric field polarizations. The optical spectra are strongly anisotropic along these two polarizations. For (E ∥ x), absorption edge is at 0 eV, while there is no absorption below 8 eV for (E ∥ z).

Linguistic input, electronic media, and communication outcomes of toddlers with hearing loss.

Science.gov (United States)

Ambrose, Sophie E; VanDam, Mark; Moeller, Mary Pat

2014-01-01

The objectives of this study were to examine the quantity of adult words, adult-child conversational turns, and electronic media in the auditory environments of toddlers who are hard of hearing (HH) and to examine whether these factors contributed to variability in children's communication outcomes. Participants were 28 children with mild to severe hearing loss. Full-day recordings of children's auditory environments were collected within 6 months of their second birthdays by using Language ENvironment Analysis technology. The system analyzes full-day acoustic recordings, yielding estimates of the quantity of adult words, conversational turns, and electronic media exposure in the recordings. Children's communication outcomes were assessed via the receptive and expressive scales of the Mullen Scales of Early Learning at 2 years of age and the Comprehensive Assessment of Spoken Language at 3 years of age. On average, the HH toddlers were exposed to approximately 1400 adult words per hour and participated in approximately 60 conversational turns per hour. An average of 8% of each recording was classified as electronic media. However, there was considerable within-group variability on all three measures. Frequency of conversational turns, but not adult words, was positively associated with children's communication outcomes at 2 and 3 years of age. Amount of electronic media exposure was negatively associated with 2-year-old receptive language abilities; however, regression results indicate that the relationship was fully mediated by the quantity of conversational turns. HH toddlers who were engaged in more conversational turns demonstrated stronger linguistic outcomes than HH toddlers who were engaged in fewer conversational turns. The frequency of these interactions was found to be decreased in households with high rates of electronic media exposure. Optimal language-learning environments for HH toddlers include frequent linguistic interactions between parents and

Observational evidence of competing source, loss, and transport processes for relativistic electrons in Earth's outer radiation belt

Science.gov (United States)

Turner, Drew; Mann, Ian; Usanova, Maria; Rodriguez, Juan; Henderson, Mike; Angelopoulos, Vassilis; Morley, Steven; Claudepierre, Seth; Li, Wen; Kellerman, Adam; Boyd, Alexander; Kim, Kyung-Chan

Earth’s outer electron radiation belt is a region of extreme variability, with relativistic electron intensities changing by orders of magnitude over time scales ranging from minutes to years. Extreme variations of outer belt electrons ultimately result from the relative impacts of various competing source (and acceleration), loss, and transport processes. Most of these processes involve wave-particle interactions between outer belt electrons and different types of plasma waves in the inner magnetosphere, and in turn, the activity of these waves depends on different solar wind and magnetospheric driving conditions and thus can vary drastically from event to event. Using multipoint analysis with data from NASA’s Van Allen Probes, THEMIS, and SAMPEX missions, NOAA’s GOES and POES constellations, and ground-based observatories, we present results from case studies revealing how different source/acceleration and loss mechanisms compete during active periods to result in drastically different distributions of outer belt electrons. By using a combination of low-Earth orbiting and high-altitude-equatorial orbiting satellites, we briefly review how it is possible to get a much more complete picture of certain wave activity and electron losses over the full range of MLTs and L-shells throughout the radiation belt. We then show example cases highlighting the importance of particular mechanisms, including: substorm injections and whistler-mode chorus waves for the source and acceleration of relativistic electrons; magnetopause shadowing and wave-particle interactions with EMIC waves for sudden losses; and ULF wave activity for driving radial transport, a process which is important for redistributing relativistic electrons, contributing both to acceleration and loss processes. We show how relativistic electron enhancement events involve local acceleration that is consistent with wave-particle interactions between a seed population of 10s to 100s of keV electrons, with a

Many-Body Theory of Proton-Generated Point Defects for Losses of Electron Energy and Photons in Quantum Wells

Science.gov (United States)

Huang, Danhong; Iurov, Andrii; Gao, Fei; Gumbs, Godfrey; Cardimona, D. A.

2018-02-01

The effects of point defects on the loss of either energies of ballistic electron beams or incident photons are studied by using a many-body theory in a multi-quantum-well system. This theory includes the defect-induced vertex correction to a bare polarization function of electrons within the ladder approximation, and the intralayer and interlayer screening of defect-electron interactions is also taken into account in the random-phase approximation. The numerical results of defect effects on both energy-loss and optical-absorption spectra are presented and analyzed for various defect densities, numbers of quantum wells, and wave vectors. The diffusion-reaction equation is employed for calculating distributions of point defects in a layered structure. For completeness, the production rate for Frenkel-pair defects and their initial concentration are obtained based on atomic-level molecular-dynamics simulations. By combining the defect-effect, diffusion-reaction, and molecular-dynamics models with an available space-weather-forecast model, it will be possible in the future to enable specific designing for electronic and optoelectronic quantum devices that will be operated in space with radiation-hardening protection and, therefore, effectively extend the lifetime of these satellite onboard electronic and optoelectronic devices. Specifically, this theory can lead to a better characterization of quantum-well photodetectors not only for high quantum efficiency and low dark current density but also for radiation tolerance or mitigating the effects of the radiation.

Electron - polar acoustical phonon interactions in nitride based diluted magnetic semiconductor quantum well via hot electron magnetotransport

International Nuclear Information System (INIS)

Pandya, Ankur; Shinde, Satyam; Jha, Prafulla K.

2015-01-01

In this paper the hot electron transport properties like carrier energy and momentum scattering rates and electron energy loss rates are calculated via interactions of electrons with polar acoustical phonons for Mn doped BN quantum well in BN nanosheets via piezoelectric scattering and deformation potential mechanisms at low temperatures with high electric field. Electron energy loss rate increases with the electric field. It is observed that at low temperatures and for low electric field the phonon absorption is taking place whereas, for sufficient large electric field, phonon emission takes place. Under the piezoelectric (polar acoustical phonon) scattering mechanism, the carrier scattering rate decreases with the reduction of electric field at low temperatures wherein, the scattering rate variation with electric field is limited by a specific temperature beyond which there is no any impact of electric field on such scattering

Effects of obesity and diabetes on rate of bone density loss.

Science.gov (United States)

Leslie, W D; Morin, S N; Majumdar, S R; Lix, L M

2018-01-01

In this large registry-based study, women with diabetes had marginally greater bone mineral density (BMD) loss at the femoral neck but not at other measurement sites, whereas obesity was not associated with greater BMD loss. Our data do not support the hypothesis that rapid BMD loss explains the increased fracture risk associated with type 2 diabetes and obesity observed in prior studies. Type 2 diabetes and obesity are associated with higher bone mineral density (BMD) which may be less protective against fracture than previously assumed. Inconsistent data suggest that rapid BMD loss may be a contributing factor. We examined the rate of BMD loss in women with diabetes and/or obesity in a population-based BMD registry for Manitoba, Canada. We identified 4960 women aged ≥ 40 years undergoing baseline and follow-up BMD assessments (mean interval 4.3 years) without confounding medication use or large weight fluctuation. We calculated annualized rate of BMD change for the lumbar spine, total hip, and femoral neck in relation to diagnosed diabetes and body mass index (BMI) category. Baseline age-adjusted BMD was greater in women with diabetes and for increasing BMI category (all P obese women but BMI did not significantly affect hip BMD loss.

Emergence of depression following job loss prospectively predicts lower rates of reemployment.

Science.gov (United States)

Stolove, Catherine A; Galatzer-Levy, Isaac R; Bonanno, George A

2017-07-01

Job loss has been associated with the emergence of depression and subsequent long-term diminished labor market participation. In a sample of 500 adults who lost their jobs, trajectories of depression severity from four years before to four years after job loss were identified using Latent Growth Mixture Modeling. Rates of unemployment by trajectory were compared at two and four years following job loss. Four trajectories demonstrated optimal model fit including resilience (72%), chronic pre-to-post job loss depression (9%), emergent depression (10%), and remitting depression (9%). Logistic regression comparing reemployment status by class while controlling for age, gender, and education at two-years post job loss revealed no significant differences by class. An identical logistic regression on four-year reemployment revealed significant differences by class with post-hoc analyses revealing emergent depression resulting in a 33.3% reemployment rate compared to resilient individuals (60.4%) together indicating that depression affects reemployment rather than lack of reemployment causing the emergence of depression. The emergence of depression following job loss significantly increases the risk of continued unemployment. However, observed high rates of resilience with resulting downstream benefits in reemployment mitigates significant concern about the effects of wide spread unemployment on ongoing global economic recovery following the Great Recession. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Measurement of the band gap by reflection electron energy loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Vos, Maarten, E-mail: maarten.vos@anu.edu.au [Electronic Materials Engineering Department, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia); King, Sean W. [Logic Technology Development, Intel Corporation, Hillsboro, OR 97124 (United States); French, Benjamin L. [Ocotillo Materials Laboratory, Intel Corporation, Chandler, AZ 85248 (United States)

2016-10-15

Highlights: • Semiconductors are measured (without surface preparation) using REELS. • At low beam energies it is difficult to measure band gap due to surface impurities. • At very high energies it is difficult to measure band gap due to recoil effect. • At intermediate energies (around 5 keV) one obtains a good estimate of the band gap. - Abstract: We investigate the possibilities of measuring the band gap of a variety of semiconductors and insulators by reflection electron energy loss spectroscopy without additional surface preparation. The band gap is a bulk property, whereas reflection energy loss spectroscopy is generally considered a surface sensitive technique. By changing the energy of the incoming electrons, the degree of surface sensitivity can be varied. Here, we present case studies to determine the optimum condition for the determination of the band gap. At very large incoming electron energies recoil effects interfere with the band gap determination, whereas at very low energies surface effects are obscuring the band gap without surface preparation. Using an incoming energy of 5 keV a reasonable estimate of the band gap is obtained in most cases.

Measurement of the band gap by reflection electron energy loss spectroscopy

International Nuclear Information System (INIS)

Vos, Maarten; King, Sean W.; French, Benjamin L.

2016-01-01

Highlights: • Semiconductors are measured (without surface preparation) using REELS. • At low beam energies it is difficult to measure band gap due to surface impurities. • At very high energies it is difficult to measure band gap due to recoil effect. • At intermediate energies (around 5 keV) one obtains a good estimate of the band gap. - Abstract: We investigate the possibilities of measuring the band gap of a variety of semiconductors and insulators by reflection electron energy loss spectroscopy without additional surface preparation. The band gap is a bulk property, whereas reflection energy loss spectroscopy is generally considered a surface sensitive technique. By changing the energy of the incoming electrons, the degree of surface sensitivity can be varied. Here, we present case studies to determine the optimum condition for the determination of the band gap. At very large incoming electron energies recoil effects interfere with the band gap determination, whereas at very low energies surface effects are obscuring the band gap without surface preparation. Using an incoming energy of 5 keV a reasonable estimate of the band gap is obtained in most cases.

Vacuum ultra-violet and electron energy loss spectroscopy of gaseous and solid organic compounds

International Nuclear Information System (INIS)

Koch, E.E.; Otto, A.

1976-01-01

The experimental arrangements used by the authors for the study of optical vacuum ultra-violet and electron energy loss spectra of organic compounds are described and some theoretical aspects of studies of higher excited states are considered. Results for alkanes, benzene, naphthalene, anthracene and some more complex hydrocarbons are reviewed. Recent results obtained by reflection and electron energy loss spectroscopy for single crystals of anthracene are included and their relevance for gas phase work as well as for the understanding of exciton effects in organic solids is described. (author)

Retrograde amnesia produced by electron beam exposure: causal parameters and duration of memory loss

International Nuclear Information System (INIS)

Wheeler, T.G.; Hardy, K.A.

1985-01-01

The production of retrograde amnesia (RA) upon electron beam exposure has been investigated. RA production was evaluated using a single-trial avoidance task across a 10 4 dose range for 10-, 1-, and 0.1-μsec pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 10 6 rad/sec. By employing a 10 rad (10 6 rad/sec) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory activation which provided a novel stimulus that masked previous stimuli

Evaporation Loss of Light Elements as a Function of Cooling Rate: Logarithmic Law

Science.gov (United States)

Xiong, Yong-Liang; Hewins, Roger H.

2003-01-01

Knowledge about the evaporation loss of light elements is important to our understanding of chondrule formation processes. The evaporative loss of light elements (such as B and Li) as a function of cooling rate is of special interest because recent investigations of the distribution of Li, Be and B in meteoritic chondrules have revealed that Li varies by 25 times, and B and Be varies by about 10 times. Therefore, if we can extrapolate and interpolate with confidence the evaporation loss of B and Li (and other light elements such as K, Na) at a wide range of cooling rates of interest based upon limited experimental data, we would be able to assess the full range of scenarios relating to chondrule formation processes. Here, we propose that evaporation loss of light elements as a function of cooling rate should obey the logarithmic law.

Characterizing Peptide Neutral Losses Induced by Negative Electron-Transfer Dissociation (NETD)

Science.gov (United States)

Rumachik, Neil G.; McAlister, Graeme C.; Russell, Jason D.; Bailey, Derek J.; Wenger, Craig D.; Coon, Joshua J.

2012-01-01

We implemented negative electron-transfer dissociation (NETD) on a hybrid ion trap/Orbitrap mass spectrometer to conduct ion/ion reactions using peptide anions and radical reagent cations. In addition to sequence-informative ladders of a•- and x-type fragment ions, NETD generated intense neutral loss peaks corresponding to the entire or partial side-chain cleavage from amino acids constituting a given peptide. Thus, a critical step towards the characterization of this recently introduced fragmentation technique is a systematic study of synthetic peptides to identify common neutral losses and preferential fragmentation pathways. Examining 46 synthetic peptides with high mass accuracy and high resolution analysis permitted facile determination of the chemical composition of each neutral loss. We identified 19 unique neutral losses from 14 amino acids and three modified amino acids, and assessed the specificity and sensitivity of each neutral loss using a database of 1542 confidently identified peptides generated from NETD shotgun experiments employing high-pH separations and negative electrospray ionization. As residue-specific neutral losses indicate the presence of certain amino acids, we determined that many neutral losses have potential diagnostic utility. We envision this catalogue of neutral losses being incorporated into database search algorithms to improve peptide identification specificity and to further advance characterization of the acidic proteome. PMID:22290482

Probing Plasmonic Nanostructures with Electron Energy - Loss Spectroscopy

DEFF Research Database (Denmark)

Raza, Søren

for nonlocal response. The experimental work comprises the use of electron energy-loss spectroscopy (EELS) to excite and study both localized and propagating surface plasmons in metal structures. Following a short introduction, we present the theoretical foundation to describe nonlocal response in Maxwell......, dimer with nanometer-sized gaps, core-shell nanowire with ultrathin metal shell, and a thin metal film. In all cases we compare the nonlocal models with the local-response approximation. Below the plasma frequency, we find that the distance between the induced positive and negative surface charges...

Comparison of the potentials used for the calculation of the resonant coherent electron capture and loss cross sections

International Nuclear Information System (INIS)

Pauly, N.; Dubus, A.; Roesler, M.

2003-01-01

For incident protons with velocities around 1 a.u., electron capture and loss processes are known to play an important role. In particular, electron emission as well as electronic stopping power are strongly influenced by the charge changing processes. Several different electron capture and loss processes have been identified [Solid State Phys. 43 (1990) 229], i.e. Auger valence band processes, shell processes and resonant coherent processes. In the latter, the incident projectile undergoes a periodic excitation due to the periodic crystalline potential so that an electron can be lost or captured. In the literature, several different choices have been made for the crystalline potential. It is precisely the aim of the present work to review and compare the various potentials used in the literature and to show the influence of this choice on the resonant coherent electron capture and loss cross sections

Blocking Losses With a Photon Counter

Science.gov (United States)

Moision, Burce E.; Piazzolla, Sabino

2012-01-01

It was not known how to assess accurately losses in a communications link due to photodetector blocking, a phenomenon wherein a detector is rendered inactive for a short time after the detection of a photon. When used to detect a communications signal, blocking leads to losses relative to an ideal detector, which may be measured as a reduction in the communications rate for a given received signal power, or an increase in the signal power required to support the same communications rate. This work involved characterizing blocking losses for single detectors and arrays of detectors. Blocking may be mitigated by spreading the signal intensity over an array of detectors, reducing the count rate on any one detector. A simple approximation was made to the blocking loss as a function of the probability that a detector is unblocked at a given time, essentially treating the blocking probability as a scaling of the detection efficiency. An exact statistical characterization was derived for a single detector, and an approximation for multiple detectors. This allowed derivation of several accurate approximations to the loss. Methods were also derived to account for a rise time in recovery, and non-uniform illumination due to diffraction and atmospheric distortion of the phase front. It was assumed that the communications signal is intensity modulated and received by an array of photon-counting photodetectors. For the purpose of this analysis, it was assumed that the detectors are ideal, in that they produce a signal that allows one to reproduce the arrival times of electrons, produced either as photoelectrons or from dark noise, exactly. For single detectors, the performance of the maximum-likelihood (ML) receiver in blocking is illustrated, as well as a maximum-count (MC) receiver, that, when receiving a pulse-position-modulated (PPM) signal, selects the symbol corresponding to the slot with the largest electron count. Whereas the MC receiver saturates at high count rates

THE TRANSITION MASS-LOSS RATE: CALIBRATING THE ROLE OF LINE-DRIVEN WINDS IN MASSIVE STAR EVOLUTION

Energy Technology Data Exchange (ETDEWEB)

Vink, Jorick S.; Graefener, Goetz, E-mail: jsv@arm.ac.uk [Armagh Observatory, College Hill, BT61 9DG Armagh (United Kingdom)

2012-06-01

A debate has arisen regarding the importance of stationary versus eruptive mass loss for massive star evolution. The reason is that stellar winds have been found to be clumped, which results in the reduction of unclumped empirical mass-loss rates. Most stellar evolution models employ theoretical mass-loss rates which are already reduced by a moderate factor of {approx_equal}2-3 compared to non-corrected empirical rates. A key question is whether these reduced rates are of the correct order of magnitude, or if they should be reduced even further, which would mean that the alternative of eruptive mass loss becomes necessary. Here we introduce the transition mass-loss rate M-dot{sub trans} between O and Wolf-Rayet stars. Its novelty is that it is model independent. All that is required is postulating the spectroscopic transition point in a given data set, and determining the stellar luminosity, which is far less model dependent than the mass-loss rate. The transition mass-loss rate is subsequently used to calibrate stellar wind strength by its application to the Of/WNh stars in the Arches cluster. Good agreement is found with two alternative modeling/theoretical results, suggesting that the rates provided by current theoretical models are of the right order of magnitude in the {approx}50 M{sub Sun} mass range. Our results do not confirm the specific need for eruptive mass loss as luminous blue variables, and current stellar evolution modeling for Galactic massive stars seems sound. Mass loss through alternative mechanisms might still become necessary at lower masses, and/or metallicities, and the quantification of alternative mass loss is desirable.

THE TRANSITION MASS-LOSS RATE: CALIBRATING THE ROLE OF LINE-DRIVEN WINDS IN MASSIVE STAR EVOLUTION

International Nuclear Information System (INIS)

Vink, Jorick S.; Gräfener, Götz

2012-01-01

A debate has arisen regarding the importance of stationary versus eruptive mass loss for massive star evolution. The reason is that stellar winds have been found to be clumped, which results in the reduction of unclumped empirical mass-loss rates. Most stellar evolution models employ theoretical mass-loss rates which are already reduced by a moderate factor of ≅2-3 compared to non-corrected empirical rates. A key question is whether these reduced rates are of the correct order of magnitude, or if they should be reduced even further, which would mean that the alternative of eruptive mass loss becomes necessary. Here we introduce the transition mass-loss rate M-dot trans between O and Wolf-Rayet stars. Its novelty is that it is model independent. All that is required is postulating the spectroscopic transition point in a given data set, and determining the stellar luminosity, which is far less model dependent than the mass-loss rate. The transition mass-loss rate is subsequently used to calibrate stellar wind strength by its application to the Of/WNh stars in the Arches cluster. Good agreement is found with two alternative modeling/theoretical results, suggesting that the rates provided by current theoretical models are of the right order of magnitude in the ∼50 M ☉ mass range. Our results do not confirm the specific need for eruptive mass loss as luminous blue variables, and current stellar evolution modeling for Galactic massive stars seems sound. Mass loss through alternative mechanisms might still become necessary at lower masses, and/or metallicities, and the quantification of alternative mass loss is desirable.

Mapping boron in silicon solar cells using electron energy-loss spectroscopy

DEFF Research Database (Denmark)

in the energies of plasmon peaks in the low loss region [5]. We use these approaches to characterize both a thick n-p junction and the 10-nm-thick p-doped layer of a working solar cell. [1] U. Kroll, C. Bucher, S. Benagli, I. Schönbächler, J. Meier, A. Shah, J. Ballutaud, A. Howling, Ch. Hollenstein, A. Büchel, M......Amorphous silicon solar cells typically consist of stacked layers deposited on plastic or metallic substrates making sample preparation for transmission electron microscopy (TEM) difficult. The amorphous silicon layer - the active part of the solar cell - is sandwiched between 10-nm-thick n- and p...... resolution using TEM is highly challenging [3]. Recently, scanning TEM (STEM) combined with electron energy-loss spectroscopy (EELS) and spherical aberration-correction has allowed the direct detection of dopant concentration of 10^20cm-3 in 65-nm-wide silicon devices [4]. Here, we prepare TEM samples...

Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale.

Science.gov (United States)

Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

2016-03-01

Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale

Energy Technology Data Exchange (ETDEWEB)

Colliex, Christian, E-mail: christian.colliex@u-psud.fr; Kociak, Mathieu; Stéphan, Odile

2016-03-15

Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale

International Nuclear Information System (INIS)

Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

2016-01-01

Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

Time evolution of the characteristic electron energy losses spectra of the electrons scattered on polycrystal samples of Al mechanically cleaned in vacuum

International Nuclear Information System (INIS)

Szczesny, R.; Baranowski, A.; Beliczynski, J.

1982-01-01

Measurements by the reflection technique of characteristic electron energy losses (CEEL) with a primary electron beam of energy E 0 =1 keV have been carried out on polycrystal samples of Al. The sample surfaces have been mechanically cleaned in a dinamical vacuum of the order 10 -6 Tr before each measurement. The CEEL spectra have been corrected for the resolving power of the apparatus by the deconvolution method. We have ascertained that the measuring technique and elaboration data method are useful for quickly obtaining the plasmon energy loss spectrum for an investigated material. (author)

Electron energy-loss spectroscopy on fullerenes and fullerene compounds

International Nuclear Information System (INIS)

Armbruster, J.

1996-03-01

A few years ago, a new form of pure carbon, the fullerenes, has been discovered, which shows many fascinating properties. Within this work the spatial and electronic structure of some selected fullerene compounds have been investigated by electron-energy-loss spectroscopy in transmission. Phase pure samples of alkali intercalated fullerides A x C 60 (A=Na, K, Cs) have been prepared using vacuum distillation. Measruements of K 3 C 60 show a dispersion of the charge carrier plasmon close to zero. This can be explained by calculations, which take into account both band structure and local-field (inhomogeneity) effects. The importance of the molecular structure can also be seen from the A 4 C 60 compounds, where the non-metallic properties are explained by a splitting of the t 1u and t 1g derived bands that is caused by electron-correlation and Jahn-Teller effects. First measurements of the electronic structure of Na x C 60 (x>6) are presented and reveal a complete transfer from the sodium atoms but an incomplete transfer onto the C 60 molecules. This behaviour can be explained by taking into account additional electronic states that are situated between the sodium atoms in the octahedral sites and are predicted by calculations using local density approximation. The crystal structure of the higher fullerenes C 76 and C 84 is found to be face-centered cubic

Measurement of the electron quenching rate in an electron beam pumped KrF* laser

International Nuclear Information System (INIS)

Nishioka, Hajime; Kurashima, Toshio; Kuranishi, Hideaki; Ueda, Kenichi; Takuma, Hiroshi; Sasaki, Akira; Kasuya, Koichi.

1988-01-01

The electron quenching rate of KrF * in an electron beam pumped laser has been studied by accurately measuring the saturation intensity in a mixture of Ar/Kr/F 2 = 94/6/0.284. The input intensity of the measurements was widely varied from 100 W cm -2 (small signal region) to 100 MW cm -2 (absorption dominant region) in order to separate laser parameters which are small signal gain coefficient, absorption coefficient, and saturation intensity from the measured net gain coefficients. The gas pressure and the pump rate were varied in the range of 0.5 to 2.5 atm and 0.3 to 1.4 MW cm -3 , respectively. The electron quenching rate constant of 4.5 x 10 -7 cm 3 s -1 was obtained from the pressure and the pump rate dependence of the KrF * saturation intensity with the temperature dependence of the rate gas 3-body quenching rate as a function of gas temperature to the -3rd power. The small signal gain coefficients calculated with the determined quenching rate constants shows excellent agreement with the measurements. (author)

Quantitative nanoscale water mapping in frozen-hydrated skin by low-loss electron energy-loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yakovlev, Sergey [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Misra, Manoj; Shi, Shanling [Unilever Research and Development, Trumbull, CT 06611 (United States); Firlar, Emre [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Libera, Matthew, E-mail: mlibera@stevens.edu [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030 (United States)

2010-06-15

Spatially resolved low-loss electron energy-loss spectroscopy (EELS) is a powerful method to quantitatively determine the water distribution in frozen-hydrated biological materials at high spatial resolution. However, hydrated tissue, particularly its hydrophilic protein-rich component, is very sensitive to electron radiation. This sensitivity has traditionally limited the achievable spatial resolution because of the relatively high noise associated with low-dose data acquisition. We show that the damage caused by high-dose data acquisition affects the accuracy of a multiple-least-squares (MLS) compositional analysis because of inaccuracies in the reference spectrum used to represent the protein. Higher spatial resolution combined with more accurate compositional analysis can be achieved if a reference spectrum is used that better represents the electron-beam-damaged protein component under frozen-hydrated conditions rather than one separately collected from dry protein under low-dose conditions. We thus introduce a method to extract the best-fitting protein reference spectrum from an experimental spectrum dataset. This method can be used when the MLS-fitting problem is sufficiently constrained so that the only unknown is the reference spectrum for the protein component. We apply this approach to map the distribution of water in cryo-sections obtained from frozen-hydrated tissue of porcine skin. The raw spectral data were collected at doses up to 10{sup 5} e/nm{sup 2} despite the fact that observable damage begins at doses as low as 10{sup 3} e/nm{sup 2}. The resulting spatial resolution of 10 nm is 5-10 times better than that in previous studies of frozen-hydrated tissue and is sufficient to resolve sub-cellular water fluctuations as well as the inter-cellular lipid-rich regions of skin where water-mediated processes are believed to play a significant role in the phenotype of keratinocytes in the stratum corneum.

Quantitative nanoscale water mapping in frozen-hydrated skin by low-loss electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Yakovlev, Sergey; Misra, Manoj; Shi, Shanling; Firlar, Emre; Libera, Matthew

2010-01-01

Spatially resolved low-loss electron energy-loss spectroscopy (EELS) is a powerful method to quantitatively determine the water distribution in frozen-hydrated biological materials at high spatial resolution. However, hydrated tissue, particularly its hydrophilic protein-rich component, is very sensitive to electron radiation. This sensitivity has traditionally limited the achievable spatial resolution because of the relatively high noise associated with low-dose data acquisition. We show that the damage caused by high-dose data acquisition affects the accuracy of a multiple-least-squares (MLS) compositional analysis because of inaccuracies in the reference spectrum used to represent the protein. Higher spatial resolution combined with more accurate compositional analysis can be achieved if a reference spectrum is used that better represents the electron-beam-damaged protein component under frozen-hydrated conditions rather than one separately collected from dry protein under low-dose conditions. We thus introduce a method to extract the best-fitting protein reference spectrum from an experimental spectrum dataset. This method can be used when the MLS-fitting problem is sufficiently constrained so that the only unknown is the reference spectrum for the protein component. We apply this approach to map the distribution of water in cryo-sections obtained from frozen-hydrated tissue of porcine skin. The raw spectral data were collected at doses up to 10 5 e/nm 2 despite the fact that observable damage begins at doses as low as 10 3 e/nm 2 . The resulting spatial resolution of 10 nm is 5-10 times better than that in previous studies of frozen-hydrated tissue and is sufficient to resolve sub-cellular water fluctuations as well as the inter-cellular lipid-rich regions of skin where water-mediated processes are believed to play a significant role in the phenotype of keratinocytes in the stratum corneum.

Complete Loss and Thermal Model of Power Semiconductors Including Device Rating Information

DEFF Research Database (Denmark)

Ma, Ke; Bahman, Amir Sajjad; Beczkowski, Szymon

2015-01-01

Thermal loading of power devices are closely related to the reliability performance of the whole converter system. The electrical loading and device rating are both important factors that determine the loss and thermal behaviors of power semiconductor devices. In the existing loss and thermal...

Two types of charge transfer excitations in low dimensional cuprates: an electron energy-loss study

Czech Academy of Sciences Publication Activity Database

Knupfer, M.; Fink, J.; Drechsler, S.-L.; Hayn, R.; Málek, Jiří; Moskvin, A.S.

137-140, - (2004), s. 469-473 ISSN 0368-2048 Institutional research plan: CEZ:AV0Z1010914 Keywords : cuprates * electronic excitations * electron energy-loss spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.069, year: 2004

Duration of memory loss due to electron beam exposure. Final report Jan-May 1983

Energy Technology Data Exchange (ETDEWEB)

Wheeler, T.G.; Tilton, B.M.

1983-08-01

Electron beam exposure has been shown to produce retrograde amnesia (RA). The objective of this study was to determine the duration of memory loss upon electron beam exposure. It is important to know if exposure produces a memory loss of the events which occurred in the preceding 1 sec or memory loss of the preceding minute's events. The task was a single-trial avoidance paradigm. The animal was placed in a small aversive chamber. After a 90-sec adaptation period, a door opened that provided access to a large, dark, preferred chamber. The time required for the animal to enter the preferred chamber was the measure of interest (T). Once inside the preferred chamber, a 1-sec footshock was delivered. Following the footshock by some preset delay (delta T), the animal was exposed to a 10-microsec, 10-rad electron beam (or X-ray). A second trial on the task was run 2 hr postexposure. The second trial consisted of placing the animal in the aversive chamber and monitoring the time (T') required to enter the preferred chamber. If the electron beam exposure interfered with the animal's ability to recall the shock, T' would be greatly reduced as compared with the sham controls. The exposure delay times used were delta T = 1, 3, 5, and 10 sec.

The energy-deposition model. Electron loss of heavy ions in collisions with neutral atoms at low and intermediate energies

International Nuclear Information System (INIS)

Shevelko, V.P.; Litsarev, M.S.; Kato, D.; Tawara, H.

2010-09-01

Single- and multiple-electron loss processes in collisions of heavy many-electron ions (positive and negative) in collisions with neutral atoms at low and intermediate energies are considered using the energy-deposition model. The DEPOSIT computer code, created earlier to calculate electron-loss cross sections at high projectile energies, is extended for low and intermediate energies. A description of a new version of DEPOSIT code is given, and the limits of validity for collision velocity in the model are discussed. Calculated electron-loss cross sections for heavy ions and atoms (N + , Ar + , Xe + , U + , U 28+ , W, W + , Ge - , Au - ), colliding with neutral atoms (He, Ne, Ar, W) are compared with available experimental and theoretical data at energies E > 10 keV/u. It is found that in most cases the agreement between experimental data and the present model is within a factor of 2. Combining results obtained by the DEPOSIT code at low and intermediate energies with those by the LOSS-R code at high energies (relativistic Born approximation), recommended electron-loss cross sections in a wide range of collision energy are presented. (author)

Structural defects in multiferroic BiMnO3 studied by transmission electron microscopy and electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Yang, H.; Chi, Z. H.; Yao, L. D.; Zhang, W.; Li, F. Y.; Jin, C. Q.; Yu, R. C.

2006-01-01

The multiferroic material BiMnO 3 synthesized under high pressure has been systematically studied by transmission electron microscopy and electron energy-loss spectroscopy, and some important structural defects are revealed in this multiferroic material. The frequently observed defects are characterized to be Σ3(111) twin boundaries, Ruddlesden-Popper [Acta Crystallogr. 11, 54 (1958)] antiphase boundaries, and a p p superdislocations connected with a small segment of Ruddlesden-Popper defect. These defects are present initially in the as-synthesized sample. In addition, we find that ordered voids (oxygen vacancies) are easily introduced into the multiferroic BiMnO 3 by electron-beam irradiation

Dissociative electron attachment to ozone: rate constant

International Nuclear Information System (INIS)

Skalny, J.D.; Cicman, P.; Maerk, T.D.

2002-01-01

The rate constant for dissociative electron attachment to ozone has been derived over the energy range of 0-10 eV by using previously measured cross section data revisited here in regards to discrimination effect occurring during the extraction of ions. The obtained data for both possible channels exhibit the maximum at mean electron energies close to 1 eV. (author)

Impact of potassium doping on the electronic structure of tetracene and pentacene: An electron energy-loss study

Energy Technology Data Exchange (ETDEWEB)

Roth, Friedrich, E-mail: Friedrich.Roth@cfel.de [Center for Free-Electron Laser Science / DESY, Notkestraße 85, D-22607 Hamburg (Germany); Knupfer, Martin, E-mail: M.Knupfer@ifw-dresden.de [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)

2015-10-21

We report the doping induced changes of the electronic structure of tetracene and pentacene probed by electron energy-loss spectroscopy in transmission. A comparison between the dynamic response of undoped and potassium-intercalated tetracene and pentacene emphasizes the appearance of a new excitation feature in the former gap upon potassium addition. Interestingly, the momentum dependency of this new excitation shows a negative dispersion. Moreover, the analysis of the C 1s and K 2p core-level excitation results in a significantly lower doping level compared to potassium doped picene, a recently discovered superconductor. Therefore, the present electronic structure investigations open a new pathway to better understand the exceptional differences between acenes and phenacene and their divergent behavior upon alkali doping.

Q FUNCTION AWARE OPTICAL PACKET SWITCH WITH LOW PACKET LOSS RATE

Directory of Open Access Journals (Sweden)

OMPAL SINGH

2017-03-01

Full Text Available Optical packet switching (OPS is a very promising technology for the next generation data transfer due to the very large bandwidth of the optical fiber. The success of the OPS relies heavily on design of the node architecture which supports comparatively larger buffering capacity without detiorating signal quality too much and it should provide very low packet loss probability with reasonably low average delay. In this paper, a design analysis of low complexity OPS node architecture is discussed along-with its advantages. The presented architecture support both fixed and variable length packets. The packets are stored in a single piece of fiber using the WDM technology. Physical layer analysis presented in this paper is to obtain the Q function (Bit Error Rate. Finally, the Monte Carlo simulation is done to obtain the packet loss. The average delay performance of the switch and effect of Q values on packet loss rates are discussed.

Electron attachment rate constant measurement by photoemission electron attachment ion mobility spectrometry (PE-EA-IMS)

International Nuclear Information System (INIS)

Su, Desheng; Niu, Wenqi; Liu, Sheng; Shen, Chengyin; Huang, Chaoqun; Wang, Hongmei; Jiang, Haihe; Chu, Yannan

2012-01-01

Photoemission electron attachment ion mobility spectrometry (PE-EA-IMS), with a source of photoelectrons induced by vacuum ultraviolet radiation on a metal surface, has been developed to study electron attachment reaction at atmospheric pressure using nitrogen as the buffer gas. Based on the negative ion mobility spectra, the rate constants for electron attachment to tetrachloromethane and chloroform were measured at ambient temperature as a function of the average electron energy in the range from 0.29 to 0.96 eV. The experimental results are in good agreement with the data reported in the literature. - Highlights: ► Photoemission electron attachment ion mobility spectrometry (PE-EA-IMS) was developed to study electron attachment reaction. ► The rate constants of electron attachment to CCl 4 and CHCl 3 were determined. ► The present experimental results are in good agreement with the previously reported data.

On FEL integral equation and electron energy loss in intermediate gain regime

International Nuclear Information System (INIS)

Takao, Masaru

1994-03-01

The FEL pendulum equation in a intermediate gain small signal regime is investigated. By calculating the energy loss of the electron beam in terms of the solution of the pendulum equation, we confirm the consistency of the FEL equation in intermediate gain regime. (author)

Simultaneous measurements of ion and electron currents using a novel compact electrostatic end-loss-current detector

Science.gov (United States)

Hirata, M.; Miyake, Y.; Cho, T.; Kohagura, J.; Numakura, T.; Shimizu, K.; Ito, M.; Kiminami, S.; Morimoto, N.; Hirai, K.; Yamagishi, T.; Miyata, Y.; Nakashima, Y.; Miyoshi, S.; Ogura, K.; Kondoh, T.; Kariya, T.

2006-10-01

For the purpose of end-loss-ion and -electron analyses in open-field plasmas, a compact-sized electrostatic end-loss-current detector is proposed on the basis of a self-collection principle for suppressing the effects of secondary-electron emission from a metal collector. For employing this specific method, it is worth noting that no further additional magnetic systems except the ambient open-ended magnetic fields are required in the detector operation. This characteristic property provides a compactness of the total detection system and availability for its use in plasma confinement devices without disturbing plasma-confining magnetic fields. The detector consists of a set of parallel metal plates with respect to lines of ambient magnetic forces of a plasma device for analyzing incident ion currents along with a grid for shielding the collector against strays due to the metal-plate biasing. The characterization experiments are carried out by the use of a test-ion-beam line along with an additional use of a Helmholtz coil system for the formation of open magnetic fields similar to those in the GAMMA 10 end region. The applications of the developed end-loss-current detector in the GAMMA 10 plasma experiments are demonstrated under the conditions with simultaneous incidence of energetic electrons produced by electron-cyclotron heatings for end-loss-plugging potential formation.

Neutrino energy loss rates due to key iron isotopes for core-collapse physics

International Nuclear Information System (INIS)

Nabi, J.-U.

2008-07-01

Accurate estimates of neutrino energy loss rates are needed for the study of the late stages of the stellar evolution, in particular for the cooling of neutron stars and white dwarfs. The energy spectra of neutrinos and antineutrinos arriving at the Earth can also provide useful information on the primary neutrino fluxes as well as neutrino mixing scenario. Proton-neutron quasi-particle random phase approximation (pn-QRPA) theory has recently being used for a microscopic calculation of stellar weak interaction rates of fp-shell nuclide, particularly iron isotopes, with success. Here I present the calculation of neutrino and antineutrino energy loss rates due to key iron isotopes in stellar matter using the pn-QRPA theory. The rates are calculated on a fine grid of temperature-density scale suitable for core-collapse simulators. The calculated rates are compared against earlier calculations. The neutrino cooling rates due to even-even isotopes of iron, 54,56 Fe, are in good agreement with the rates calculated using the large-scale shell model. The pn-QRPA calculated neutrino energy loss rates due to 55 Fe are enhanced roughly around an order of magnitude compared to the large-scale shell model calculation during the oxygen and silicon shell burning stages of massive stars and favor a lower entropy for the cores of massive stars. (author)

Study of semiconductor valence plasmon line shapes via electron energy-loss spectroscopy in the transmission electron microscope

International Nuclear Information System (INIS)

Kundmann, M.K.

1988-11-01

Electron energy-loss spectra of the semiconductors Si, AlAs, GaAs, InAs, InP, and Ge are examined in detail in the regime of outer-shell and plasmon energy losses (0--100eV). Particular emphasis is placed on modeling and analyzing the shapes of the bulk valence plasmon lines. A line shape model based on early work by Froehlich is derived and compared to single-scattering probability distributions extracted from the measured spectra. Model and data are found to be in excellent agreement, thus pointing the way to systematic characterization of the plasmon component of EELS spectra. The model is applied to three separate investigations. 82 refs

Characteristic electron energy loss spectra in SiC buried layers formed by C+ implantation into crystalline silicon

International Nuclear Information System (INIS)

Yan Hui; Chen Guanghua; Kwok, R.W.M.

1998-01-01

SiC buried layers were synthesized by a metal vapor vacuum arc ion source, with C + ions implanted into crystalline Si substrates. According to X-ray photoelectron spectroscopy, the characteristic electron energy loss spectra of the SiC buried layers were studied. It was found that the characteristic electron energy loss spectra depend on the profiles of the carbon content, and correlate well with the order of the buried layers

Analytical modeling of electron energy loss spectroscopy of graphene: Ab initio study versus extended hydrodynamic model.

Science.gov (United States)

Djordjević, Tijana; Radović, Ivan; Despoja, Vito; Lyon, Keenan; Borka, Duško; Mišković, Zoran L

2018-01-01

We present an analytical modeling of the electron energy loss (EEL) spectroscopy data for free-standing graphene obtained by scanning transmission electron microscope. The probability density for energy loss of fast electrons traversing graphene under normal incidence is evaluated using an optical approximation based on the conductivity of graphene given in the local, i.e., frequency-dependent form derived by both a two-dimensional, two-fluid extended hydrodynamic (eHD) model and an ab initio method. We compare the results for the real and imaginary parts of the optical conductivity in graphene obtained by these two methods. The calculated probability density is directly compared with the EEL spectra from three independent experiments and we find very good agreement, especially in the case of the eHD model. Furthermore, we point out that the subtraction of the zero-loss peak from the experimental EEL spectra has a strong influence on the analytical model for the EEL spectroscopy data. Copyright © 2017 Elsevier B.V. All rights reserved.

Relativistic electronic structure calculations on endohedral Gd rate at C60, La rate at C60, Gd rate at C74, and La rate at C74

International Nuclear Information System (INIS)

Lu, J.; Zhang, X.; Zhao, X.

2000-01-01

Relativistic discrete-variational local density functional calculations on endohedral Gd rate at C 60 , La rate at C 60 ,Gd rate at C 74 , and La rate at C 74 are performed. All the C 60 - and C 74 -derived levels are lowered upon endohedral Gd and La doping. Both the Gd (4f 7 5d 1 6s 2 ) and La (5d 1 6s 2 ) atoms only donate their two 6s valence electrons to the cages, leaving behind their 5d electrons when they are placed at the cage centers. Compared with large-band-gap C 60 , small-band-gap C 74 and Gd (La)-metallofullerenes have strong both electron-donating and electron-accepting characters, and the calculated ionization potentials and electron affinities for them agree well with the available experimental data. (orig.)

Investigation of ionization losses of shower electrons in electron-photon shower developed in liquid xenon by gamma quanta in the energy range 1600-3400 MeV

International Nuclear Information System (INIS)

Okhrymenko, L.S.; Slowinski, B.; Strugalski, Z.; Sredniawa, B.

1975-01-01

Results of the investigation of differential distributions of ionization losses and the corresponding fluctuations for shower electrons in the longitudinal development of electron-photon showers produced by gamma-quanta of energies Esub(γ)=1600-3400 MeV in liquid xenon are given. A simple and convenient from the methodical point of view two-parametric function, approximating the observed distribution has been obtained. The independence of the fluctuations of ionization losses of shower electrons on the energy of gamma-quanta in the investigated interval of Esub(γ) values has been found

Electron-beam-induced reduction of Fe3+ in iron phosphate dihydrate, ferrihydrite, haemosiderin and ferritin as revealed by electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Pan, Ying-Hsi; Vaughan, Gareth; Brydson, Rik; Bleloch, Andrew; Gass, Mhairi; Sader, Kasim; Brown, Andy

2010-01-01

The effect of high-energy electron irradiation on ferritin/haemosiderin cores (in an iron-overloaded human liver biopsy), its mineral analogue; six-line ferrihydrite (6LFh), and iron phosphate dihydrate (which has similar octahedral ferric iron to oxygen coordination to that in ferrihydrite and ferritin/haemosiderin cores) has been investigated using electron energy-loss spectroscopy (EELS). Fe L 2,3 -ionisation edges were recorded on two types of electron microscope: a 200 keV transmission electron microscope (TEM) and a 100 keV scanning transmission electron microscope (STEM), in order to investigate the damage mechanisms in operation and to establish a methodology for minimum specimen alteration during analytical electron microscopic characterisation. A specimen damage mechanism dominated by radiolysis that results in the preferential loss of iron co-ordinating ligands (O, OH and H 2 O) is discussed. The net result of irradiation is structural re-organisation and reduction of iron within the iron hydroxides. At sufficiently low electron fluence and particularly in the lower incident energy, finer probe diameter STEM, the alteration is shown to be minimal. All the materials examined exhibit damage which as a function of cumulative fluence is best fitted by an inverse power-law, implying that several chemical and structural changes occur in response to the electron beam and we suggest that these are governed by secondary processes arising from the primary ionisation event. This work affirms that electron fluence and current density should be considered when measuring mixed valence ratios with EELS.

Electronic energy states of HfSe/sub 2/ and NbSe/sub 2/ by low energy electron loss spectroscopy study

Energy Technology Data Exchange (ETDEWEB)

Ito, T; Iwami, M; Hiraki, A [Osaka Univ., Suita (Japan). Faculty of Engineering

1981-06-01

Low energy electron loss spectroscopy (ELS) study was performed on 1T-HfSe/sub 2/ (group IVB metal compound) and 2H-NbSe/sub 2/ (group VB metal compound) by using incident electron energies of 30-250 eV. From the loss data in the second derivative form, maxima in density-of-states in the conduction band of the compounds were deduced through the information on the filled core states by X-ray photoelectron spectroscopy. The conduction band of the transition-metal dichalcogenides could be divided into two parts. The results are discussed in relation to the previous work on WS/sub 2/ (group VIB metal compound), and also to proposals based on band calculations and experimental studies on the transition-metal dichalcogenides with constituent metals of group IVB, VB and VIB.

Low-energy electron energy losses and inelastic mean free paths in zinc, selenium, and zinc selenide

Energy Technology Data Exchange (ETDEWEB)

Bourke, J.D.; Chantler, C.T., E-mail: chantler@unimelb.edu.au

2014-10-15

We compute low-energy optical energy loss spectra for the elemental solids zinc and selenium, and for the binary compound zinc selenide. The optical data are transformed via a constrained partial-pole algorithm to produce momentum-dependent electron energy loss spectra and electron inelastic mean free paths. This enables a comparison between the electron scattering behaviour in a compound solid and its constituent elements. Results cannot be explained by aggregation methods or commonly used universal curves, and prove that new approaches are required. Our work demonstrates new capabilities for the determination of fundamental material properties for a range of structures previously inaccessible to established theoretical models, and at energy levels inaccessible to most experimental techniques.

Low-energy electron energy losses and inelastic mean free paths in zinc, selenium, and zinc selenide

International Nuclear Information System (INIS)

Bourke, J.D.; Chantler, C.T.

2014-01-01

We compute low-energy optical energy loss spectra for the elemental solids zinc and selenium, and for the binary compound zinc selenide. The optical data are transformed via a constrained partial-pole algorithm to produce momentum-dependent electron energy loss spectra and electron inelastic mean free paths. This enables a comparison between the electron scattering behaviour in a compound solid and its constituent elements. Results cannot be explained by aggregation methods or commonly used universal curves, and prove that new approaches are required. Our work demonstrates new capabilities for the determination of fundamental material properties for a range of structures previously inaccessible to established theoretical models, and at energy levels inaccessible to most experimental techniques

Modest weight loss in moderately overweight postmenopausal women improves heart rate variability

DEFF Research Database (Denmark)

Mouridsen, Mette Rauhe; Bendsen, Nathalie Tommerup; Astrup, Arne

2013-01-01

Purpose: To evaluate the effects of weight loss on heart rate (HR) and heart rate variability (HRV) parameters in overweight postmenopausal women. Design and Methods: Forty-nine overweight postmenopausal women with an average body mass index of 28.8 1.9 kg/m2 underwent a 12-week dietary weight......-to-normal intervals for each 5-min period (SDNNindex). Baseline body fat mass (FM%) and changes in body composition was determined by dual X-ray absorptiometry. Before and after the weight-loss period, total abdominal fat, intra-abdominal fat (IAAT), and subcutaneous abdominal fat (SCAT) were measured by single...

Measurement of the electron quenching rate in an electron beam pumped KrF/sup */ laser

Energy Technology Data Exchange (ETDEWEB)

Nishioka, Hajime; Kurashima, Toshio; Kuranishi, Hideaki; Ueda, Kenichi; Takuma, Hiroshi; Sasaki, Akira; Kasuya, Koichi.

1988-09-01

The electron quenching rate of KrF/sup */ in an electron beam pumped laser has been studied by accurately measuring the saturation intensity in a mixture of Ar/Kr/F/sub 2/ = 94/6/0.284. The input intensity of the measurements was widely varied from 100 W cm/sup -2/ (small signal region) to 100 MW cm/sup -2/ (absorption dominant region) in order to separate laser parameters which are small signal gain coefficient, absorption coefficient, and saturation intensity from the measured net gain coefficients. The gas pressure and the pump rate were varied in the range of 0.5 to 2.5 atm and 0.3 to 1.4 MW cm/sup -3/, respectively. The electron quenching rate constant of 4.5 x 10/sup -7/ cm/sup 3/s/sup -1/ was obtained from the pressure and the pump rate dependence of the KrF/sup */ saturation intensity with the temperature dependence of the rate gas 3-body quenching rate as a function of gas temperature to the -3rd power. The small signal gain coefficients calculated with the determined quenching rate constants shows excellent agreement with the measurements.

Investigation of Deuterium Implantation into Beryllium Sample by Electron Energy Loss Spectroscopy

Science.gov (United States)

Afanas'ev, V. P.; Gryazev, A. S.; Kaplya, P. S.; Köppen, M.; Ridzel, O. Yu; Subbotin, N. Yu; Hansen, P.

2017-11-01

Quantitative analysis of hydrogen isotopes in first wall as well as in construction materials of future fusion devices plays a crucial role to understand the evolution of those materials under operation conditions. A quantitative understanding of hydrogen in materials is also an important issue for storing energy as well as for fuel cells. A combination of Electron Energy Loss Spectroscopy (EELS) and Elastic Peak Electron Spectroscopy (EPES) is presented in this study to tackle these problems of modern material research for energy production and storage. Accurate inelastic scattering background subtraction is a key part of the presented quantitative measurement of the Be/D ratio. The differential inelastic scattering cross-section is determined by the fitting procedure. The fitting procedure is based on the iterative solution of the direct problem and minimization of the residual between computed and measured spectra. This study also takes into account the difference in electron energy loss laws for surface and bulk. The inelastic scattering cross-sections for different doses of deuterium ions in beryllium substrate (5.5·1021 m-2 and 2.01·1022 m-2) were defined in a two-layered model. The analysis is carried out for the EELS spectra. Relative concentration of D atoms is defined.

Retrograde amnesia produced by electron beam exposure: causal parameters and duration of memory loss. [Rats

Energy Technology Data Exchange (ETDEWEB)

Wheeler, T.G.; Hardy, K.A.

1985-01-01

The production of retrograde amnesia (RA) upon electron beam exposure has been investigated. RA production was evaluated using a single-trial avoidance task across a 10/sup 4/ dose range for 10-, 1-, and 0.1-..mu..sec pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 10/sup 6/ rad/sec. By employing a 10 rad (10/sup 6/ rad/sec) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory activation which provided a novel stimulus that masked previous stimuli.

Drift Loss-Cone Distributions Electrons in the Jovian Synchrotron Zone from 06 and VIP4 Models

Science.gov (United States)

Wang, K.; Bolton, S. J.; Gulkis, S.; Levin, S. M.

2000-01-01

Relativistic electrons (10-50 MeV) play an important role to account for the observed synchrotron decimetric radiation in Jupiter's inner radiation belt (L loss cone for relativistic electrons using both the O6 and VIP4 magnetic field models. Model maps of the synchrotron emission for specific electron distributions are shown for comparison.

Electron emission and energy loss in grazing collisions of protons with insulator surfaces

International Nuclear Information System (INIS)

Gravielle, M. S.; Miraglia, J. E.; Aldazabal, I.; Arnau, A.; Ponce, V. H.; Aumayr, F.; Lederer, S.; Winter, H.

2007-01-01

Electron emission from LiF, KCl, and KI crystal surfaces during grazing collisions of swift protons is studied using a first-order distorted-wave formalism. Owing to the localized character of the electronic structure of these surfaces, we propose a model that allows us to describe the process as a sequence of atomic transitions from different target ions. Experimental results are presented for electron emission from LiF and KI and energy loss from KI surfaces. Calculations show reasonable agreement with these experimental data. The role played by the charge of the incident particle is also investigated

Evaluating Land Subsidence Rates and Their Implications for Land Loss in the Lower Mississippi River Basin

Directory of Open Access Journals (Sweden)

Lei Zou

2015-12-01

Full Text Available High subsidence rates, along with eustatic sea-level change, sediment accumulation and shoreline erosion have led to widespread land loss and the deterioration of ecosystem health around the Lower Mississippi River Basin (LMRB. A proper evaluation of the spatial pattern of subsidence rates in the LMRB is the key to understanding the mechanisms of the submergence, estimating its potential impacts on land loss and the long-term sustainability of the region. Based on the subsidence rate data derived from benchmark surveys from 1922 to 1995, this paper constructed a subsidence rate surface for the region through the empirical Bayesian kriging (EBK interpolation method. The results show that the subsidence rates in the region ranged from 1.7 to 29 mm/year, with an average rate of 9.4 mm/year. Subsidence rates increased from north to south as the outcome of both regional geophysical conditions and anthropogenic activities. Four areas of high subsidence rates were found, and they are located in Orleans, Jefferson, Terrebonne and Plaquemines parishes. A projection of future landscape loss using the interpolated subsidence rates reveals that areas below zero elevation in the LMRB will increase from 3.86% in 2004 to 19.79% in 2030 and 30.88% in 2050. This translates to a growing increase of areas that are vulnerable to land loss from 44.3 km2/year to 240.7 km2/year from 2011 to 2050. Under the same scenario, Lafourche, Plaquemines and Terrebonne parishes will experience serious loss of wetlands, whereas Orleans and Jefferson parishes will lose significant developed land, and Lafourche parish will endure severe loss of agriculture land.

Losses of runaway electrons in MHD-active plasmas of the COMPASS tokamak

Science.gov (United States)

Ficker, O.; Mlynar, J.; Vlainic, M.; Cerovsky, J.; Urban, J.; Vondracek, P.; Weinzettl, V.; Macusova, E.; Decker, J.; Gospodarczyk, M.; Martin, P.; Nardon, E.; Papp, G.; Plyusnin, V. V.; Reux, C.; Saint-Laurent, F.; Sommariva, C.; Cavalier, J.; Havlicek, J.; Havranek, A.; Hronova, O.; Imrisek, M.; Markovic, T.; Varju, J.; Paprok, R.; Panek, R.; Hron, M.; The COMPASS Team

2017-07-01

The significant role of magnetic perturbations in mitigation and losses of runaway electrons (REs) was documented in dedicated experimental studies of RE at the COMPASS tokamak. REs in COMPASS are produced both in low density quiescent discharges and in disruptions triggered by massive gas injection (MGI). The role of the RE seed produced in the beginning of the discharge on the subsequent RE population proved significant. Modulation of the RE losses by MHD instabilities was observed at several characteristic frequencies, as well as by magnetic field oscillations related to power supplies. Magnetic islands seem to suppress the losses as the HXR signal is low and coherent with the island rotation frequency. Moreover, periods of increased losses of REs observed in the current quench (CQ) and early RE beam plateau phase of the MGI disruptions seem to be linked to the bursts of magnetic perturbation, and to the observation of filaments in the fast visible camera images.

Semiconductor detector with smoothly tunable effective thickness for the study of ionization loss by moderately relativistic electrons

Energy Technology Data Exchange (ETDEWEB)

Shchagin, A.V., E-mail: shchagin@kipt.kharkov.ua [Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Belgorod National Research University, Belgorod (Russian Federation); Shul’ga, N.F.; Trofymenko, S.V. [Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Kharkov National University, Kharkov (Ukraine); Nazhmudinov, R.M.; Kubankin, A.S. [Belgorod National Research University, Belgorod (Russian Federation); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation)

2016-11-15

The possibility of measurement of electrons ionization loss in Si layer of smoothly tunable thickness is shown in the proof-of-principle experiment. The Si surface-barrier detector with the depleted layer thickness controlled by the value of high voltage power supply has been used. Ionization loss spectra for electrons emitted by radioactive source {sup 207}Bi are presented and discussed. Experimental results for the most probable ionization loss in the Landau spectral peak are compared with theoretical calculations. The possibility of research of evolution of electromagnetic field of ultra-relativistic particles traversing media interface with the use of detectors with smoothly tunable thickness is proposed.

Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities

Directory of Open Access Journals (Sweden)

W. Verhoeven

2016-09-01

Full Text Available We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers.

Electron capture rate of a composite of partially ionized atomic nuclei

International Nuclear Information System (INIS)

Yokoi, K.; Takahashi, K.

1979-01-01

Electron captures (or more generally β-transitions) are known to play key roles at various stages of stellar evolution and in many nucleosynthesis processes. With decreasing temperatures and densities, the bound electron captures start to compete with the free electron captures, and eventually in the low-temperature, low-density limit the total capture rate shall converge to that of the orbital electrons observed in laboratory. The authors calculate the occupation probabilities of the electron orbits and the electron capture rates in a mixture of atoms and ions which are supposedly under a chemical equilibrium. (orig./AH)

Miniature electron bombardment evaporation source: evaporation rate measurement

International Nuclear Information System (INIS)

Nehasil, V.; Masek, K.; Matolin, V.; Moreau, O.

1997-01-01

Miniature electron beam evaporation sources which operate on the principle of vaporization of source material, in the form of a tip, by electron bombardment are produced by several companies specialized in UHV equipment. These sources are used primarily for materials that are normally difficult to deposit due to their high evaporation temperature. They are appropriate for special applications such as heteroepitaxial thin film growth requiring a very low and well controlled deposition rate. A simple and easily applicable method of evaporation rate control is proposed. The method is based on the measurement of ion current produced by electron bombardment of evaporated atoms. The absolute evaporation flux values were measured by means of the Bayard-Alpert ion gauge, which enabled the ion current vs evaporation flux calibration curves to be plotted. (author). 1 tab., 4 figs., 6 refs

The rate of Aflatoxin contamination of bread losses in Lorestan provinces

Directory of Open Access Journals (Sweden)

nader Azadbakht

2008-10-01

Full Text Available Azadbakht N1, Khosravinegad K2, Tarrahi MJ3 1. MSc in plant pathology, Khorramabad, Iran 2. BSc in livestock sciences, Khorramabad, Iran 3. Instrustor, Department of Epidemiology, Faculty of Health, Lorestan University of Medical Sciences , Khorramabad, Iran Abstract Background: Aflatoxins belong to a group of toxins called mycotoxins that infection with them can cause complications in humans such as immunity weakness, lung syndrome, liver cancer, esophagus cancer and hemagglutination, and are inhibitor of RNA and protein, as well as cause numorous complications in genital, respiratory and the digestive systems and because of their poisoning and carcinogenic and tumorigenic properties, cause numorous complications in livestock. This research was carried out to determine the rate of Aflatoxine contamination of bread losses in Lorestan province and its comparison with standard levels reported by WHO and FAO. Materials and methods: This study was done by field and laboratory method on 180 samples of losses dried bread in 2009 with randomized distribution in Lorestan provine and detection of samples contamination to aflatoxin was done by HPLC floresence apparatus. Data was analyzed by SPSS software (α=5%. Results: The median rate of types of aflatoxin: B1,B2,G1 and G2 total types of aflatoxin in bread losses (infected, semi-infected and safe in Lorestan were 22.5304,2.4369,0.1923,0.1022 and 25.2636 (µg/kg. Average of minimum and maximum infection to aflatoxin with all types of aflatoxin belonged to Khorramabad (42.9403 and 47.7153 µg/kg and Borujerd (1.8611 and 1.9833 respectively. Average rate of aflatoxin type B1 in infected, semi-infected and safe bread are 64.0536, 1.9167, 0.5629 (µg/kg and average rate of all types of aflatoxin in infected, and safe breads were: 72.0257,1.9990 and 05753 (µg/kg. Also rate of aflatoxin B1 in 29 out of 180 samples are more than standard level and total rate of different types of aflatoxin in 18 samples were

Rates of species loss from Amazonian forest fragments

Science.gov (United States)

Ferraz, Gonçalo; Russell, Gareth J.; Stouffer, Philip C.; Bierregaard, Richard O.; Pimm, Stuart L.; Lovejoy, Thomas E.

2003-01-01

In the face of worldwide habitat fragmentation, managers need to devise a time frame for action. We ask how fast do understory bird species disappear from experimentally isolated plots in the Biological Dynamics of Forest Fragments Project, central Amazon, Brazil. Our data consist of mist-net records obtained over a period of 13 years in 11 sites of 1, 10, and 100 hectares. The numbers of captures per species per unit time, analyzed under different simplifying assumptions, reveal a set of species-loss curves. From those declining numbers, we derive a scaling rule for the time it takes to lose half the species in a fragment as a function of its area. A 10-fold decrease in the rate of species loss requires a 1,000-fold increase in area. Fragments of 100 hectares lose one half of their species in <15 years, too short a time for implementing conservation measures. PMID:14614134

Interpretation of monoclinic hafnia valence electron energy-loss spectra by time-dependent density functional theory

Science.gov (United States)

Hung, L.; Guedj, C.; Bernier, N.; Blaise, P.; Olevano, V.; Sottile, F.

2016-04-01

We present the valence electron energy-loss spectrum and the dielectric function of monoclinic hafnia (m -HfO2) obtained from time-dependent density-functional theory (TDDFT) predictions and compared to energy-filtered spectroscopic imaging measurements in a high-resolution transmission-electron microscope. Fermi's golden rule density-functional theory (DFT) calculations can capture the qualitative features of the energy-loss spectrum, but we find that TDDFT, which accounts for local-field effects, provides nearly quantitative agreement with experiment. Using the DFT density of states and TDDFT dielectric functions, we characterize the excitations that result in the m -HfO2 energy-loss spectrum. The sole plasmon occurs between 13 and 16 eV, although the peaks ˜28 and above 40 eV are also due to collective excitations. We furthermore elaborate on the first-principles techniques used, their accuracy, and remaining discrepancies among spectra. More specifically, we assess the influence of Hf semicore electrons (5 p and 4 f ) on the energy-loss spectrum, and find that the inclusion of transitions from the 4 f band damps the energy-loss intensity in the region above 13 eV. We study the impact of many-body effects in a DFT framework using the adiabatic local-density approximation (ALDA) exchange-correlation kernel, as well as from a many-body perspective using "scissors operators" matched to an ab initio G W calculation to account for self-energy corrections. These results demonstrate some cancellation of errors between self-energy and excitonic effects, even for excitations from the Hf 4 f shell. We also simulate the dispersion with increasing momentum transfer for plasmon and collective excitation peaks.

Improved calculations of the electronic and nuclear energy losses for light ions penetrating H and He targets at intermediate velocities

Energy Technology Data Exchange (ETDEWEB)

Grande, P.L. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica; Schiwietz, G. [Hahn-Meitner-Institut Berlin GmbH (Germany). Dept. FD

1994-06-01

A review is given on the use of the coupled-channel method to calculate the electronic and nuclear energy loss of ions penetrating the matter. This first principle calculation based on an expansion of the time dependent electronic wavefunction in terms of atomic orbitals has been applied to evaluate the impact parameter dependence of the electronic energy loss, the stopping cross-section and the fluctuation is energy loss of ions colliding with H and He atoms at energies of 10 keV/amu to 500 keV/amu. The results have been compared to experimental data as well as to others existing models, local density approximation in an electron gas target, harmonic oscillator target treatment and first order plane-wave-Born approximation. (author). 63 refs, 11 figs.

Numerical study of electron-leakage power loss in a tri-plate transmission line

International Nuclear Information System (INIS)

Barker, R.J.; Goldstein, S.A.

1982-01-01

Numerical simulations have been conducted using NRL's DIODE2D computer code to model the steady-state behavior of electron flow in a radial diode and in its adjacent tri-plate transmission line (TTL). Particular attention was paid to the magnitude of the electron current flowing from the cathode to the anode surface in the TTL. A quantitative value for this effective power loss is given. The electron current is restricted mainly to the transition region in the TTL into which there is seepage of the B/sub z/ that is imposed in the diode gap. This finding highlights the importance of that region to diode designers

Electron energy-loss spectroscopy characterization and microwave absorption of iron-filled carbon-nitrogen nanotubes

International Nuclear Information System (INIS)

Che Renchao; Liang Chongyun; Shi Honglong; Zhou Xingui; Yang Xinan

2007-01-01

Iron-filled carbon-nitrogen (Fe/CN x ) nanotubes and iron-filled carbon (Fe/C) nanotubes were synthesized at 900 deg. C through a pyrolysis reaction of ferrocene/acetonitrile and ferrocene/xylene, respectively. The differences of structure and composition between the Fe/CN x nanotubes and Fe/C nanotubes were investigated by transmission electron microscopy and electron energy-loss spectroscopy (EELS). It was found that the morphology of Fe/CN x nanotubes is more corrugated than that of the Fe/C nanotubes due to the incorporation of nitrogen. By comparing the Fe L 2,3 electron energy-loss spectra of Fe/CN x nanotubes to those of the Fe/C nanotubes, the electron states at the interface between Fe and the tubular wall of both Fe/CN x nanotubes and Fe/C nanotubes were investigated. At the boundary between Fe and the wall of a CN x nanotube, the additional electrons contributed from the doped 'pyridinic-like' nitrogen might transfer to the empty 3d orbital of the encapsulated iron, therefore leading to an intensity suppression of the iron L 2,3 edge and an intensity enhancement of the carbon K edge. However, such an effect could not be found in Fe/C nanotubes. Microwave absorption properties of both Fe/CN x and Fe/C nanocomposites at 2-18 GHz band were studied

Estimates of Annual Soil Loss Rates in the State of São Paulo, Brazil

Directory of Open Access Journals (Sweden)

Grasiela de Oliveira Rodrigues Medeiros

Full Text Available ABSTRACT: Soil is a natural resource that has been affected by human pressures beyond its renewal capacity. For this reason, large agricultural areas that were productive have been abandoned due to soil degradation, mainly caused by the erosion process. The objective of this study was to apply the Universal Soil Loss Equation to generate more recent estimates of soil loss rates for the state of São Paulo using a database with information from medium resolution (30 m. The results showed that many areas of the state have high (critical levels of soil degradation due to the predominance of consolidated human activities, especially in growing sugarcane and pasture use. The average estimated rate of soil loss is 30 Mg ha-1 yr-1 and 59 % of the area of the state (except for water bodies and urban areas had estimated rates above 12 Mg ha-1 yr-1, considered as the average tolerance limit in the literature. The average rates of soil loss in areas with annual agricultural crops, semi-perennial agricultural crops (sugarcane, and permanent agricultural crops were 118, 78, and 38 Mg ha-1 yr-1 respectively. The state of São Paulo requires attention to conservation of soil resources, since most soils led to estimates beyond the tolerance limit.

Electron energy loss spectroscopy microanalysis and imaging in the transmission electron microscope: example of biological applications

International Nuclear Information System (INIS)

Diociaiuti, Marco

2005-01-01

This paper reports original results obtained in our laboratory over the past few years in the application of both electron energy loss spectroscopy (EELS) and electron spectroscopy imaging (ESI) to biological samples, performed in two transmission electron microscopes (TEM) equipped with high-resolution electron filters and spectrometers: a Gatan model 607 single magnetic sector double focusing EEL serial spectrometer attached to a Philips 430 TEM and a Zeiss EM902 Energy Filtering TEM. The primary interest was on the possibility offered by the combined application of these spectroscopic techniques with those offered by the TEM. In particular, the electron beam focusing available in a TEM allowed us to perform EELS and ESI on very small sample volumes, where high-resolution imaging and electron diffraction techniques can provide important structural information. I show that ESI was able to improve TEM performance, due to the reduced chromatic aberration and the possibility of avoiding the sample staining procedure. Finally, the analysis of the oscillating extended energy loss fine structure (EXELFS) beyond the ionization edges characterizing the EELS spectra allowed me, in a manner very similar to the extended X-ray absorption fine structure (EXAFS) analysis of the X-ray absorption spectra, to obtain short-range structural information for such light elements of biological interest as O or Fe. The Philips EM430 (250-300 keV) TEM was used to perform EELS microanalysis on Ca, P, O, Fe, Al and Si. The assessment of the detection limits of this method was obtained working with well-characterized samples containing Ca and P, and mimicking the actual cellular matrix. I applied EELS microanalysis to Ca detection in bone tissue during the mineralization process and to P detection in the cellular membrane of erythrocytes treated with an anti-tumoral drug, demonstrating that the cellular membrane is a drug target. I applied EELS microanalysis and selected area electron

Effects of target electron collisions on energy loss straggling in plasmas of all degeneracies

Energy Technology Data Exchange (ETDEWEB)

Barriga Carrasco, Manuel D. [E.T.S.I. Industriales, Universisdad de Castilla La Mancha, Ciudad Real E13071 (Spain)]. E-mail: ManuelD.Barriga@uclm.es

2007-07-01

The purpose of the present paper is to describe the effects of target electron collisions on the energy loss straggling in plasmas of any degeneracy. We focus our analysis on targets that are in the limit of weakly coupled electron gases, where the random phase approximation can be applied. This type of plasmas targets has not been studied extensively, though they are very important for inertial confinement fusion. The energy loss straggling is obtained from an exact quantum mechanical evaluation, which takes into account the degeneracy of the target plasma, and later it is compared with common classical and degenerate approximations. Also we consider electron collisions in the exact quantum mechanical straggling calculation. Now the maximum straggling occurs at velocities smaller than for the calculations without considering collisions for all kinds of plasmas analyzed. The straggling remains equal or enhances for velocities less than or equal to the velocity at maximum while is slightly decreases for higher velocities. Differences are significant in all cases, that can let large errors creep on in further energy deposition and projectile range studies.

Effects of target electron collisions on energy loss straggling in plasmas of all degeneracies

International Nuclear Information System (INIS)

Barriga Carrasco, Manuel D.

2007-01-01

The purpose of the present paper is to describe the effects of target electron collisions on the energy loss straggling in plasmas of any degeneracy. We focus our analysis on targets that are in the limit of weakly coupled electron gases, where the random phase approximation can be applied. This type of plasmas targets has not been studied extensively, though they are very important for inertial confinement fusion. The energy loss straggling is obtained from an exact quantum mechanical evaluation, which takes into account the degeneracy of the target plasma, and later it is compared with common classical and degenerate approximations. Also we consider electron collisions in the exact quantum mechanical straggling calculation. Now the maximum straggling occurs at velocities smaller than for the calculations without considering collisions for all kinds of plasmas analyzed. The straggling remains equal or enhances for velocities less than or equal to the velocity at maximum while is slightly decreases for higher velocities. Differences are significant in all cases, that can let large errors creep on in further energy deposition and projectile range studies

Metabolic rate and evaporative water loss of Mexican Spotted and Great Horned Owls

Science.gov (United States)

Joseph L. Ganey; Russell P. Balda; Rudy M. King

1993-01-01

We measured rates of oxygen consumption and evaporative water loss (EWL) of Mexican Spotted (Strix occidentalis lucida) and Great Horned (Bubo virginianus) owls in Arizona. Basal metabolic rate averaged 0.84 ccO2. g-1. h-1...

Effect of daily noise exposure monitoring on annual rates of hearing loss in industrial workers.

Science.gov (United States)

Rabinowitz, Peter M; Galusha, Deron; Kirsche, Sharon R; Cullen, Mark R; Slade, Martin D; Dixon-Ernst, Christine

2011-06-01

Occupational noise-induced hearing loss (NIHL) is prevalent, yet evidence on the effectiveness of preventive interventions is lacking. The effectiveness of a new technology allowing workers to monitor daily at-ear noise exposure was analysed. Workers in the hearing conservation program of an aluminium smelter were recruited because of accelerated rates of hearing loss. The intervention consisted of daily monitoring of at-ear noise exposure and regular feedback on exposures from supervisors. The annual rate of change in high frequency hearing average at 2, 3 and 4 KHz before intervention (2000-2004) and 4 years after intervention (2006-2009) was determined. Annual rates of loss were compared between 78 intervention subjects and 234 controls in other company smelters matched for age, gender and high frequency hearing threshold level in 2005. Individuals monitoring daily noise exposure experienced on average no further worsening of high frequency hearing (average rate of hearing change at 2, 3 and 4 KHz = -0.5 dB/year). Matched controls also showed decelerating hearing loss, the difference in rates between the two groups being significant (p hearing loss showed a similar trend but the difference was not statistically significant (p = 0.06). Monitoring daily occupational noise exposure inside hearing protection with ongoing administrative feedback apparently reduces the risk of occupational NIHL in industrial workers. Longer follow-up of these workers will help determine the significance of the intervention effect. Intervention studies for the prevention of NIHL need to include appropriate control groups.

Quantum-size effects in the energy loss of charged particles interacting with a confined two-dimensional electron gas

International Nuclear Information System (INIS)

Borisov, A. G.; Juaristi, J. I.; Muino, R. Diez; Sanchez-Portal, D.; Echenique, P. M.

2006-01-01

Time-dependent density-functional theory is used to calculate quantum-size effects in the energy loss of antiprotons interacting with a confined two-dimensional electron gas. The antiprotons follow a trajectory normal to jellium circular clusters of variable size, crossing every cluster at its geometrical center. Analysis of the characteristic time scales that define the process is made. For high-enough velocities, the interaction time between the projectile and the target electrons is shorter than the time needed for the density excitation to travel along the cluster. The finite-size object then behaves as an infinite system, and no quantum-size effects appear in the energy loss. For small velocities, the discretization of levels in the cluster plays a role and the energy loss does depend on the system size. A comparison to results obtained using linear theory of screening is made, and the relative contributions of electron-hole pair and plasmon excitations to the total energy loss are analyzed. This comparison also allows us to show the importance of a nonlinear treatment of the screening in the interaction process

Simulation study on avoiding runaway electron generation by magnetic perturbations

International Nuclear Information System (INIS)

Tokuda, S.; Yoshino, R.; Matsumoto, T.; Hudson, S.R.; Kawano, Y.; Takizuka, T.

2001-01-01

Simulations have demonstrated that magnetic islands having the widths expected on the major disruption cause the collisionless loss of the relativistic electrons, and that the resultant loss rate is high enough to avoid or to suppress the runaway generation. It is because, for the magnetic fluctuations in the disruption, the loss of the electron confinement due to the breakdown of the toroidal momentum conservation overwhelms the runaway electron confinement due to the phase-averaging effect of relativistic electrons. Simulation results agree closely with recent experiments on fast plasma shutdown, showing that it is possible to prevent the generation of runaway electrons. (author)

Calorimetric Measuring Systems for Characterizing High Frequency Power Losses in Power Electronic Components and Systems

DEFF Research Database (Denmark)

Blaabjerg, Frede; Pedersen, John Kim; Ritchie, Andrew Ewen

2002-01-01

High frequency power losses in power electronic components and systems are very difficult to measure. The same applies to the efficiency of high-efficiency systems and components. An important method to measure losses with high accuracy is the calorimetric measuring systems. This paper describes...... to calibrate such systems are proposed and different applications of the system are given. Two practical examples end the description of the research. It is concluded that such systems have a relative long time-constant but they are accurate and useful for precise power loss measurement....

Preference for gain- or loss-framed electronic cigarette prevention messages.

Science.gov (United States)

Kong, Grace; Cavallo, Dana A; Camenga, Deepa R; Morean, Meghan E; Krishnan-Sarin, Suchitra

2016-11-01

Effective electronic cigarette (e-cigarette) prevention messages are needed to combat the rising popularity/uptake of e-cigarettes among youth. We examined preferences for e-cigarette prevention messages that either emphasized gains (e.g., You save money by not using e-cigarettes) or losses (e.g., You spend money by using e-cigarettes) among adolescents and young adults. Using surveys in two middle schools, four high schools, and one college in CT (N=5405), we assessed students' preferences for gain- or loss-framed e-cigarette prevention messages related to four themes: financial cost, health risks, addiction potential, and social labeling as a smoker. We also assessed whether preferences for each message framing theme differed by sex, school level, cigarette-use status, and e-cigarette use-status. We also examined whether preference for message framing differed by cigarette and e-cigarette susceptibility status among never e-cigarette users. Overall, loss-framing was preferred for message themes related to health risks, addiction potential, and social labeling as a smoker, whereas gain-framing was preferred for message themes related to financial cost. Logistic regression analyses showed that 1) females preferred loss-framed messages for all themes relative to males, 2) lifetime e-cigarette users preferred loss-framed health risks and social labeling messages relative to never users, and 3) high school students preferred gain-framed social labeling messages relative to college students. The preference for message framing did not differ by cigarette or e-cigarette susceptibility. Preference for message framing differed by themes and individual characteristics. This formative research could inform the construction of persuasive e-cigarette prevention messages. Copyright © 2016. Published by Elsevier Ltd.

Electron-beam-induced reduction of Fe{sup 3+} in iron phosphate dihydrate, ferrihydrite, haemosiderin and ferritin as revealed by electron energy-loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Pan, Ying-Hsi; Vaughan, Gareth; Brydson, Rik [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom); Bleloch, Andrew; Gass, Mhairi [SuperSTEM, Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Sader, Kasim [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom); SuperSTEM, Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Brown, Andy, E-mail: a.p.brown@leeds.ac.uk [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom)

2010-07-15

The effect of high-energy electron irradiation on ferritin/haemosiderin cores (in an iron-overloaded human liver biopsy), its mineral analogue; six-line ferrihydrite (6LFh), and iron phosphate dihydrate (which has similar octahedral ferric iron to oxygen coordination to that in ferrihydrite and ferritin/haemosiderin cores) has been investigated using electron energy-loss spectroscopy (EELS). Fe L{sub 2,3}-ionisation edges were recorded on two types of electron microscope: a 200 keV transmission electron microscope (TEM) and a 100 keV scanning transmission electron microscope (STEM), in order to investigate the damage mechanisms in operation and to establish a methodology for minimum specimen alteration during analytical electron microscopic characterisation. A specimen damage mechanism dominated by radiolysis that results in the preferential loss of iron co-ordinating ligands (O, OH and H{sub 2}O) is discussed. The net result of irradiation is structural re-organisation and reduction of iron within the iron hydroxides. At sufficiently low electron fluence and particularly in the lower incident energy, finer probe diameter STEM, the alteration is shown to be minimal. All the materials examined exhibit damage which as a function of cumulative fluence is best fitted by an inverse power-law, implying that several chemical and structural changes occur in response to the electron beam and we suggest that these are governed by secondary processes arising from the primary ionisation event. This work affirms that electron fluence and current density should be considered when measuring mixed valence ratios with EELS.

Genotypic variations in photosynthetic rate and respiratory losses in some grain legumes

Energy Technology Data Exchange (ETDEWEB)

Pandey, R K; Saxena, M C; Kalubarme, M H; Singh, V B; Prasad, V V.S.S. [Gobind Ballabh Pant Univ. of Agriculture and Technology, Pantnagar (India)

1976-01-01

The relative rate of photosynthesis in 12 genotypes of Cajanus cajan as measured by /sup 14/CO/sub 2/ fixation, ranged from 100 percent in Pant A-2 to 126 percent in UPA 120. /sup 14/CO/sub 2/ fixation was not related to specific leaf weight. Respiratory losses in the 20-day period after exposure were 63 and 51 percent respectively, in seedlings of UPA-120 and Prabhat cultivars. The relative rate of photosynthesis in 13 genotypes of Vigna aureus ranged from 100 percent in LM-646 to 196 percent in LM-205. PS-16 also showed high photosynthetic rate. The translocation of /sup 14/C from leaves, stems and petioles to reproductive organs was also determined. Baisakhi accumulated larger proportion of total /sup 14/C in grain and showed lower respiratory loss than PS-16. The relative rate of photosynthesis in 20 Cicer arietinum cultivars ranged from 100 percent in S-330-1 to 224 percent in L-550. There was a considerable contribution from pod and stem towards total photosynthesis.

Electron capture and loss to continuum states in gases and solids

International Nuclear Information System (INIS)

Sellin, I.A.; Laubert, R.

1981-01-01

A key feature of our experimental procedure is the easy interchange of short gaseous and thin solid targets at the same physical position, with all apparatus aperture sizes, dimensions, positions, and other experimental details unaltered. It has therefore been possible to cancel most systematic apparatus effects in comparing gaseous and solid target results. By using single ion-atom collision techniques, by using bare and few-electron ions of appreciably higher charge than heretofore, by extending the velocity range of measurement appreciably above that of earlier experiments, and by studying charge-state variation over an appreciably wider range than used previously, we have been able to test experimentally features of continuum electron-capture and -loss theories which have been inaccessible in previous experiments. (orig./TW)

Surface plasmon modes of a single silver nanorod: An electron energy loss study

DEFF Research Database (Denmark)

Nicoletti, Olivia; Wubs, Martijn; Mortensen, N. Asger

2011-01-01

We present an electron energy loss study using energy filtered TEM of spatially resolved surface plasmon excitations on a silver nanorod of aspect ratio 14.2 resting on a 30 nm thick silicon nitride membrane. Our results show that the excitation is quantized as resonant modes whose intensity maxima...

Effects of keV electron irradiation on the avalanche-electron generation rates of three donors on oxidized silicon

International Nuclear Information System (INIS)

Sah, C.; Sun, J.Y.; Tzou, J.J.

1983-01-01

After keV electron beam irradiation of oxidized silicon, the avalanche-electron-injection generation rates and densities of the bulk compensating donor, the interface states, and the turnaround trap all increase. Heating at 200 0 C can anneal out these three donor-like traps, however, it cannot restore the generation rates back to their original and lower pre-keV electron irradiation values. The experimental results also indicate that all three traps may be related to the same mobile impurity species whose bonds are loosened by the keV electrons and then broken or released by the avalanche injected electrons

Competition Between Radial Loss and EMIC Wave Scattering of MeV Electrons During Strong CME-shock Driven Storms

Science.gov (United States)

Hudson, M. K.; Jaynes, A. N.; Li, Z.; Malaspina, D.; Millan, R. M.; Patel, M.; Qin, M.; Shen, X.; Wiltberger, M. J.

2017-12-01

The two strongest storms of Solar Cycle 24, 17 March and 22 June 2015, provide a contrast between magnetospheric response to CME-shocks at equinox and solstice. The 17 March CME-shock initiated storm produced a stronger ring current response with Dst = - 223 nT, while the 22 June CME-shock initiated storm reached a minimum Dst = - 204 nT. The Van Allen Probes ECT instrument measured a dropout in flux for both events which can be characterized by magnetopause loss at higher L values prior to strong recovery1. However, rapid loss is seen at L 3 for the June storm at high energies with maximum drop in the 5.2 MeV channel of the REPT instrument coincident with the observation of EMIC waves in the H+ band by the EMFISIS wave instrument. The rapid time scale of loss can be determined from the 65 minute delay in passage of the Probe A relative to the Probe B spacecraft. The distinct behavior of lower energy electrons at higher L values has been modeled with MHD-test particle simulations, while the rapid loss of higher energy electrons is examined in terms of the minimum resonant energy criterion for EMIC wave scattering, and compared with the timescale for loss due to EMIC wave scattering which has been modeled for other storm events.2 1Baker, D. N., et al. (2016), Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015, J. Geophys. Res. Space Physics, 121, 6647-6660, doi:10.1002/2016JA022502. 2Li, Z., et al. (2014), Investigation of EMIC wave scattering as the cause for the BARREL 17 January 2013 relativistic electron precipitation event: A quantitative comparison of simulation with observations, Geophys. Res. Lett., 41, 8722-8729, doi:10.1002/2014GL062273.

Monte Carlo Simulations of Electron Energy-Loss Spectra with the Addition of Fine Structure from Density Functional Theory Calculations.

Science.gov (United States)

Attarian Shandiz, Mohammad; Guinel, Maxime J-F; Ahmadi, Majid; Gauvin, Raynald

2016-02-01

A new approach is presented to introduce the fine structure of core-loss excitations into the electron energy-loss spectra of ionization edges by Monte Carlo simulations based on an optical oscillator model. The optical oscillator strength is refined using the calculated electron energy-loss near-edge structure by density functional theory calculations. This approach can predict the effects of multiple scattering and thickness on the fine structure of ionization edges. In addition, effects of the fitting range for background removal and the integration range under the ionization edge on signal-to-noise ratio are investigated.

Electron velocity-space diffusion in a micro-unstable ECRH [electron cyclotron resonance heated] mirror plasma

International Nuclear Information System (INIS)

Hokin, S.A.

1987-09-01

An experimental study of the velocity-space diffusion of electrons in an electron cyclotron resonance heated (ECRH) mirror plasma, in the presence of micro-unstable whistler rf emission, is presented. It is found that the dominant loss mechanism for hot electrons is endloss produced by rf diffusion into the mirror loss cone. In a standard case with 4.5 kW of ECRH power, this loss limits the stored energy to 120 J with an energy confinement time of 40 ms. The energy confinement time associated with collisional scattering is 350 ms in this case. Whistler microinstability rf produces up to 25% of the rf-induced loss. The hot electron temperature is not limited by loss of adiabaticity, but by rf-induced loss of high energy electrons, and decreases with increasing rf power in strong diffusion regimes. Collisional loss is in agreement with standard scattering theory. No super-adiabatic effects are clearly seen. Experiments in which the vacuum chamber walls are lined with microwave absorber reveal that single pass absorption is limited to less than 60%, whereas experiments with reflecting walls exhibit up to 90% absorption. Stronger diffusion is seen in the latter, with a hot electron heating rate which is twice that of the absorber experiments. This increase in diffusion can be produced by two distinct aspects of wall-reflected rf: the broader spatial rf profile, which enlarges the resonant region in velocity space, or a reduction in super-adiabatic effects due to randomization of the electron gyrophase. Since no other aspects of super-adiabaticity are observed, the first mechanism appears more likely. 39 refs., 54 figs

Perturbation of the energy loss spectra for an accelerated electron beam due to the photo injector exit

CERN Document Server

Salah, W

2003-01-01

The influence of the photo-injector exit hall on the energy loss for an accelerated electron beam is investigated, by calculating the total energy transferred from the electrons to the wakefields, which are driven by the beam. The obtained energy loss is compared to those previously obtained for a 'pill-box' cavity. This comparison shows that the influence of this hall, in terms of energy loss, varies over the beam length. It is strongest in the middle of the beam and decreases towards both ends. In consequence of this perturbation, the center of the beam is displaced from its initial position during the first phase (t < 200 ps) where the exit aperture has no effect to a new equilibrium position which takes place at 200 < t < 250 ps. (author)

Electronic and optical properties of Fe, Pd, and Ti studied by reflection electron energy loss spectroscopy

International Nuclear Information System (INIS)

Tahir, Dahlang; Kraaer, Jens; Tougaard, Sven

2014-01-01

We have studied the electronic and optical properties of Fe, Pd, and Ti by reflection electron energy-loss spectroscopy (REELS). REELS spectra recorded for primary energies in the range from 300 eV to 10 keV were corrected for multiple inelastically scattered electrons to determine the effective inelastic-scattering cross section. The dielectric functions and optical properties were determined by comparing the experimental inelastic-electron scattering cross section with a simulated cross section calculated within the semi-classical dielectric response model in which the only input is Im(−1/ε) by using the QUEELS-ε(k,ω)-REELS software package. The complex dielectric functions ε(k,ω), in the 0–100 eV energy range, for Fe, Pd, and Ti were determined from the derived Im(−1/ε) by Kramers-Kronig transformation and then the refractive index n and extinction coefficient k. The validity of the applied model was previously tested and found to give consistent results when applied to REELS spectra at energies between 300 and 1000 eV taken at widely different experimental geometries. In the present paper, we provide, for the first time, a further test on its validity and find that the model also gives consistent results when applied to REELS spectra in the full range of primary electron energies from 300 eV to 10000 eV. This gives confidence in the validity of the applied method.

Counting statistics and loss corrections for the APS

International Nuclear Information System (INIS)

Lee, W.K.; Mills, D.M.

1992-01-01

It has been suggested that for timing experiments, it might be advantageous to arrange the bunches in the storage ring in an asymmetrical mode. In this paper, we determine the counting losses from pulsed x-ray sources from basic probabilistic arguments and from Poisson statistics. In particular the impact on single photon counting losses of a variety of possible filling modes for the Advanced Photon Source (APS) is examined. For bunches of equal current, a loss of 10% occurs whenever the count rate exceeds 21% of the bunch repetition rate. This changes slightly when bunches containing unequal numbers of particles are considered. The results are applied to several common detector/electronics systems

Counting statistics and loss corrections for the APS

International Nuclear Information System (INIS)

Lee, W.K.; Mills, D.M.

1992-01-01

It has been suggested that for timing experiments, it might be advantageous to arrange the bunches in the storage ring in an asymmetrical mode. In this paper, we determine the counting losses from pulsed x-ray sources from basic probabilistic arguments and from Poisson statistics. In particular the impact on single-photon counting losses of a variety of possible filling modes for the Advanced Photon Source (APS) is examined. For bunches of equal current, a loss of 10% occurs whenever the count rate exceeds 21% of the bunch repetition rate. This changes slightly when bunches containing unequal numbers of particles are considered. The results are applied to several common detector/electronics systems

Time integrated x-ray measurments of the very energetic electron end loss profile in TMX-U

International Nuclear Information System (INIS)

Osher, J.E.; Fabyan, J.

1984-01-01

The time-integrated 2-D profile of the thick-target bremsstrahlung produced by energetic end loss electrons has been measured during ECRH operation of TMX-U. Sheets of x-ray film and/or arrays of thermoluminescent dosimeters were placed on the outside of the end tank end wall to measure the relative spatial x-ray profile, with locally added filters of Pb to determine the effective mean x-ray energy. The purpose of this simple survey diagnostic was to allow deduction of the gross features of the ECRH region. The electron source functions needed to fit the x-ray data were modeled for various anchor cell radial distributions mapped along magnetic field lines to the elliptical plasma potential control plates or the Al end walls. The data are generally consistent with (1) major ECR heating in the central 25-cm-diam core, (2) a mean ECRH electron loss energy of 420 keV, and (3) an ECRH coupling efficiency to these hot electrons of greater than or equal to 10%

Phyto-oestrogen excretion and rate of bone loss in postmenopausal women

NARCIS (Netherlands)

Kardinaal, A.F.M.; Morton, M.S.; Brüggemann-Rotgans, I.E.M.; Beresteijn, E.C.H. van

1998-01-01

Objective: The hypothesis was tested that the rate of postmenopausal bone loss is inversely associated with long-term urinary excretion of phyto-oestrogens, as a marker of habitual dietary intake. Design: Secondary analysis of a 10-year follow-up study (1979-1989) among postmenopausal women in the

Evaluation of fluid intake, weight loss and sweat rate in young triathletes

Directory of Open Access Journals (Sweden)

María Cristina Sellés López de Castro

2015-10-01

Full Text Available Introduction: Triathlon is an endurance sport comprising three disciplines: swimming, cycling and running. It is necessary to purpose guidelines in order to avoid dehydration during training or competition and keep good hydration before, during and after physical activity. The aim of this study is to evaluation of fluid intake, weight loss and sweat rate in young triathletes, during different trainings.Material and Methods: A descriptive-observational study in 14 triathletes (7 boys and 7 girls during a session of swimming, other session of cycling, another session of running. Fluid intake, weight loss, % of total body water, % dehydration and sweat rate, were assessed. Triathletes drank water in their drums of 750 ml and urine measurement was performed in containers.Results: The results of our study following the next order: swimming, cycling and running. Water intake 2.66±1.94ml/min, 7.91±7.69ml/min y 7.08±4.13ml/min in boys and 3.43±1.53ml/min, 6.39±5.36ml/min y 8.33±2.74ml/min in girls; weight loss 0.83±0.5kg, 0.47±0.3kg y 0.98±0.4kg in boys and 0.79±0.3kg, 0.47±0.58kg y 0.28±0.21kg in girls; and sweating rate 4.44±4.9ml/ min, 11.81±6.46ml/min y 5.29±3.13ml/min in boys and 3.89±2.4ml/min, 4.69±4.20ml/min and 7.96±5.06ml/min in girls.Conclusions: The percentage of body water and dehydration, loss of weight and sweat rate were compared with other studies and it´s shown that our results are lower than others studies, being below the recommendations of liquid intake in athletes.

Electron-induced hydrogen loss in uracil in a water cluster environment

International Nuclear Information System (INIS)

Smyth, M.; Kohanoff, J.; Fabrikant, I. I.

2014-01-01

Low-energy electron-impact hydrogen loss due to dissociative electron attachment (DEA) to the uracil and thymine molecules in a water cluster environment is investigated theoretically. Only the A ′ -resonance contribution, describing the near-threshold behavior of DEA, is incorporated. Calculations are based on the nonlocal complex potential theory and the multiple scattering theory, and are performed for a model target with basic properties of uracil and thymine, surrounded by five water molecules. The DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster. This growth is due to two effects: the increase of the resonance lifetime and the negative shift in the resonance position due to interaction of the intermediate negative ion with the surrounding water molecules. A similar effect was earlier found in DEA to chlorofluorocarbons

Radiation induced ligand loss from cobalt complexes

International Nuclear Information System (INIS)

Funston, A. M.; McFadyen, W.D.; Tregloan, P.A.

2000-01-01

Full text: Due to the rapid nature of ligand dissociation from cobalt(II) complexes the study of the rate of ligand dissociation necessitates the use of a technique such as pulse radiolysis. This allows the rapid reduction of the corresponding cobalt(III) complex by a reducing radical, such as the aquated electron, to form the cobalt(II) complex. However, to date, no systematic study of either the mechanism of reduction or the influence of the electronic structure on the rate of ligand dissociation has been carried out. In order to understand these processes more fully the mechanism of reduction of a range of related cobalt(III) complexes by the aquated electron and the subsequent rate of ligand dissociation from the resulting cobalt(II) complexes is being investigated. It has been found that a number of processes are observed following the initial rapid reaction of the cobalt(III) complex with the aquated electron. Ultimately ligand loss is observed. Depending upon the complex, the initial processes observed may include the formation of coordinated radicals and electron transfer within the complex. For complexes containing aromatic ligands such as 2,2'-bipyridine, 1,10-phenanthroline and dipyrido[3,2-a:2',3'-c]phenazine the formation of a coordinated radical is observed as the initial reduction step. The kinetics of ligand dissociation of these complexes has been determined. The loss of monodentate ligands is fast and has been indistinguishable from the reduction processes when aromatic ligands are also present in the complex. However, for diamine chelates and diimine chelates spectra of the transient species can be resolved

Evaluation of the Survival Rate and Bone Loss of Implants with Various Lengths

Directory of Open Access Journals (Sweden)

AR. Rokn

2006-12-01

Full Text Available Statement of Problem: The replacement of missing teeth with implant-associated restorations has become a widely used treatment modality in recent years. The length of dental implants may be a critical factor in achieving and maintaining osseointegration.Purpose: The aim of this study was to evaluate the survival rate and bone loss of dental implants with different lengthsMaterials and Methods: A retrospective cohort study was performed on 60 ITI-system implants, evenly distributed into three groups including 8, 10 and 12 mm high implants in the posterior segments of both jaws. Demographic information, oral hygiene,cigarette smoking, implant length, duration of implant placement (at least 24 months,bleeding on probing index and pocket probing depth were recorded for all participants.Bone loss was calculated using pre- and post-operative panoramic radiographs.Results: The mean rate of bone loss was different among the three groups and were found to be 0.21 (0.45, 0.3 (0.41 and 0.43 (0.55 mm in the 8, 10, and 12 mm high implants, respectively. Neither mean bone loss nor bleeding on probing index showed significant differences with implant length. A significant correlation was found between implant length and pocket probing depth (P<0.0001.Conclusion: The results of this study suggest that both short (8 mm high and long (10 or 12 mm high implants may be used with nearly equal success rates in the posterior segments of the jaws.

Dose rate effect in food irradiation

International Nuclear Information System (INIS)

Singh, H.

1991-08-01

It has been suggested that the minor losses of nutrients associated with radiation processing may be further reduced by irradiating foods at the high dose rates generally associated with electron beams from accelerators, rather than at the low dose rates typical of gamma irradiation (e.g. 60 Co). This review briefly examines available comparative data on gamma and electron irradiation of foods to evaluate these suggestions. (137 refs., 27 tabs., 11 figs.)

The effects of electron transfer on the energy loss of slow He2+, C2+, and C4+ ions penetrating a graphene fragment

International Nuclear Information System (INIS)

Mao, Fei; Zhang, Chao; Gao, Cong-Zhang; Dai, Jinxia; Zhang, Feng-Shou

2014-01-01

Electronic energy loss in the collision processes of slow ions with a graphene fragment is investigated by combining ab initio time-dependent density functional theory calculations for electrons with molecular dynamics simulations for ions in real time and real space. We study the electronic energy loss of slow He 2+ , C 2+ , and C 4+ ions penetrating the graphene fragment as a function of the ion velocity, and establish the velocity-proportional energy loss for low-charged ions down to 0.1 a.u. One mechanism clarified in the simulations for electron transfer is polarization capture, which is effective for bare ions at low velocities. The other one is resonance capture, by which the incident ion can capture electrons from the graphene fragment to its electron affinity levels, which have the same, or nearly the same, energy as those of the electron donor levels. The results demonstrate that the nonlinear behavior of energy loss of C 4+ is attributed to the large number of electrons captured by this multi-charged ion during the collision. (paper)

Anisotropic pitch angle distribution of ~100 keV microburst electrons in the loss cone: measurements from STSAT-1

Directory of Open Access Journals (Sweden)

J. J. Lee

2012-11-01

Full Text Available Electron microburst energy spectra in the range of 170 keV to 360 keV have been measured using two solid-state detectors onboard the low-altitude (680 km, polar-orbiting Korean STSAT-1 (Science and Technology SATellite-1. Applying a unique capability of the spacecraft attitude control system, microburst energy spectra have been accurately resolved into two components: perpendicular to and parallel to the geomagnetic field direction. The former measures trapped electrons and the latter those electrons with pitch angles in the loss cone and precipitating into atmosphere. It is found that the perpendicular component energy spectra are harder than the parallel component and the loss cone is not completely filled by the electrons in the energy range of 170 keV to 360 keV. These results have been modeled assuming a wave-particle cyclotron resonance mechanism, where higher energy electrons travelling within a magnetic flux tube interact with whistler mode waves at higher latitudes (lower altitudes. Our results suggest that because higher energy (relativistic microbursts do not fill the loss cone completely, only a small portion of electrons is able to reach low altitude (~100 km atmosphere. Thus assuming that low energy microbursts and relativistic microbursts are created by cyclotron resonance with chorus elements (but at different locations, the low energy portion of the microburst spectrum will dominate at low altitudes. This explains why relativistic microbursts have not been observed by balloon experiments, which typically float at altitudes of ~30 km and measure only X-ray flux produced by collisions between neutral atmospheric particles and precipitating electrons.

Rate of bone loss in postmenopausal and osteoporotic women

International Nuclear Information System (INIS)

Aloia, J.F.; Ross, P.; Vaswani, A.; Zanzi, I.; Cohn, S.H.

1982-01-01

Regional and total bone mass were determined in three groups of women by photon absorptiometry of the distal radius [bone mineral content (BMC)] and total neutron activation analysis [total body calcium (TBCa)], respectively. There were three groups of patients: group A, osteoporotic women treated with a variety of pharmacologic agents; group B, osteoporotic women (controls) taking only calcium supplements; and group C, normal postmenopausal women. The mean TBCa and BMC were considerably higher in the postmenopausal women than in the osteoporotic women. The rate of change of bone mass in group C was -0.45%/yr and -0.9%/yr for the total skeleton and radius, respectively. Group B had no significant rate of loss, whereas group A demonstrated a significant increase in TBCa of 0.75%/yr with no change in the BMC of the radius. There were no significant between-subject correlations for the slopes (rates of change) of the two bone mineral measurements

Electron-energy-loss spectral library and its application to materials science

Energy Technology Data Exchange (ETDEWEB)

Zaluzec, N.J.

1983-09-01

An electron energy loss spectral library can be an invaluable tool in materials research from a fundamental as well as a practical standpoint. Although it will not alleviate all the complications associated with quantification, this type of library can help to elucidate details of spectral profiles previously found intractable. This work was supported by the US Department of Energy. The author also wishes to express his gratitude to the organizing committee for partial financial support provided to attend this meeting.

Electronics for very high rate tracking detectors

International Nuclear Information System (INIS)

Williams, H.H.; Dressnandt, N.; Ekenberg, T.; Gerds, E.J.; Newcomer, F.M.; Tedja, S.; Van Berg, R.; Van der Speigel, J.

1995-01-01

Results are presented on a system of electronics designed for very high rate tracking detectors at the SSC and LHC. The primary goal was a system for signal detection, time measurement, and readout for the straw tracker for SDC. An integrated circuit incorporating eight channels of amplifier-shaper-discriminator (including detector tail cancellation), and two different integrated circuits for time measurement are described. The performance of tracking measurements up to counting rates of 8 MHz per wire is reported, as well as preliminary results from a baseline restoration circuit. (orig.)

Temperature-dependent surface structure, composition, and electronic properties of the clean SrTiO3(111) crystal face: Low-energy-electron diffraction, Auger-electron spectroscopy, electron energy loss, and ultraviolet-photoelectron spectroscopy studies

International Nuclear Information System (INIS)

Lo, W.J.; Somorjai, G.A.

1978-01-01

Low-energy-electron diffraction, Auger-electron spectroscopy, electron-energy-loss, and ultraviolet-photoelectron spectroscopies were used to study the structure, composition, and electron energy distribution of a clean single-crystal (111) face of strontium titanate (perovskite). The dependence of the surface chemical composition on the temperature has been observed along with corresponding changes in the surface electronic properties. High-temperature Ar-ion bombardment causes an irreversible change in the surface structure, stoichiometry, and electron energy distribution. In contrast to the TiO 2 surface, there are always significant concentrations of Ti 3+ in an annealed ordered SrTiO 3 (111) surface. This stable active Ti 3+ monolayer on top of a substrate with large surface dipole potential makes SrTiO 3 superior to TiO 2 when used as a photoanode in the photoelectrochemical cell

Quantification of the boron speciation in alkali borosilicate glasses by electron energy loss spectroscopy

DEFF Research Database (Denmark)

Cheng, D.S.; Yang, G.; Zhao, Y.Q.

2015-01-01

developed a method based on electron energy loss spectroscopy (EELS) data acquisition and analyses, which enables determination of the boron speciation in a series of ternary alkali borosilicate glasses with constant molar ratios. A script for the fast acquisition of EELS has been designed, from which...

Retrospective analysis of survival rates and marginal bone loss on short implants in the mandible.

Science.gov (United States)

Draenert, Florian G; Sagheb, Keyvan; Baumgardt, Katharina; Kämmerer, Peer W

2012-09-01

Short implants have become an interesting alternative to bone augmentation in dental implantology. Design of shorter implants and longer surveillance times are a current research issue. The goal of this study was to show the survival rates of short implants below 9 mm in the partly edentulous mandibular premolar and molar regions with fixed prosthetics. Marginal vertical and 2D bone loss was evaluated additionally. Different implant designs are orientationally evaluated. A total of 247 dental implants with fixed prosthetics (crowns and bridges) in the premolar and molar region of the mandible were evaluated; 47 implants were 9 mm or shorter. Patient data were evaluated to acquire implant survival rates, implant diameter, gender and age. Panoramic X-rays were analysed for marginal bone loss. Average surveillance time was 1327 days. Cumulative survival rate (CSR) of short implants was 98% (1 implants lost) compared to 94% in the longer implants group without significance. Thirty-five of the short implants were Astratech (0 losses) and 12 were Camlog Screw Line Promote Plus (1 loss). Early vertical and two-dimensional marginal bone loss was not significantly different in short and regular length implant group with an average of 0.6 mm and 0.7 mm(2) in short implants over the observation period. Within the limitations of this study, we conclude that short implants with a length of 9 mm or less have equal survival rates compared with longer implants over the observation period of 1-3 years. © 2011 John Wiley & Sons A/S.

Mapping bright and dark modes in gold nanoparticle chains using electron energy loss spectroscopy.

Science.gov (United States)

Barrow, Steven J; Rossouw, David; Funston, Alison M; Botton, Gianluigi A; Mulvaney, Paul

2014-07-09

We present a scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) investigation of gold nanosphere chains with lengths varying from 1 to 5 particles. We show localized EELS signals from the chains and identify energy-loss peaks arising due to l = 1, 2, 3, 4, and 5 plasmon modes through the use of EELS mapping. We also show the evolution of the energy of these modes as the length of a given chain increases, and we find that a chain containing N particles can accommodate at least N experimentally observable modes, in addition to the transverse mode. As the chain length is increased by the addition of one more gold particle to the chain, the new N + 1 mode becomes the highest energy mode, while the existing modes lower their energy and eventually asymptote as they delocalize along the chain. We also show that modes become increasingly difficult to detect with the EELS technique as l approaches N. The data are compared to numerical simulations.

Parameterization of ionization rate by auroral electron precipitation in Jupiter

Directory of Open Access Journals (Sweden)

Y. Hiraki

2008-02-01

Full Text Available We simulate auroral electron precipitation into the Jovian atmosphere in which electron multi-directional scattering and energy degradation processes are treated exactly with a Monte Carlo technique. We make a parameterization of the calculated ionization rate of the neutral gas by electron impact in a similar way as used for the Earth's aurora. Our method allows the altitude distribution of the ionization rate to be obtained as a function of an arbitrary initial energy spectrum in the range of 1–200 keV. It also includes incident angle dependence and an arbitrary density distribution of molecular hydrogen. We show that there is little dependence of the estimated ionospheric conductance on atomic species such as H and He. We compare our results with those of recent studies with different electron transport schemes by adapting our parameterization to their atmospheric conditions. We discuss the intrinsic problem of their simplified assumption. The ionospheric conductance, which is important for Jupiter's magnetosphere-ionosphere coupling system, is estimated to vary by a factor depending on the electron energy spectrum based on recent observation and modeling. We discuss this difference through the relation with field-aligned current and electron spectrum.

Electron-induced hydrogen loss in uracil in a water cluster environment

Energy Technology Data Exchange (ETDEWEB)

Smyth, M.; Kohanoff, J. [Atomistic Simulation Centre, Queen' s University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom); Fabrikant, I. I., E-mail: ifabrikant1@unl.edu [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA and Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

2014-05-14

Low-energy electron-impact hydrogen loss due to dissociative electron attachment (DEA) to the uracil and thymine molecules in a water cluster environment is investigated theoretically. Only the A{sup ′}-resonance contribution, describing the near-threshold behavior of DEA, is incorporated. Calculations are based on the nonlocal complex potential theory and the multiple scattering theory, and are performed for a model target with basic properties of uracil and thymine, surrounded by five water molecules. The DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster. This growth is due to two effects: the increase of the resonance lifetime and the negative shift in the resonance position due to interaction of the intermediate negative ion with the surrounding water molecules. A similar effect was earlier found in DEA to chlorofluorocarbons.

The loss rates of O+ in the inner magnetosphere caused by both magnetic field line curvature scattering and charge exchange reactions

Science.gov (United States)

Ji, Y.; Shen, C.

2014-03-01

With consideration of magnetic field line curvature (FLC) pitch angle scattering and charge exchange reactions, the O+ (>300 keV) in the inner magnetosphere loss rates are investigated by using an eigenfunction analysis. The FLC scattering provides a mechanism for the ring current O+ to enter the loss cone and influence the loss rates caused by charge exchange reactions. Assuming that the pitch angle change is small for each scattering event, the diffusion equation including a charge exchange term is constructed and solved; the eigenvalues of the equation are identified. The resultant loss rates of O+ are approximately equal to the linear superposition of the loss rate without considering the charge exchange reactions and the loss rate associated with charge exchange reactions alone. The loss time is consistent with the observations from the early recovery phases of magnetic storms.

Determination of tropical deforestation rates and related carbon losses from 1990 to 2010.

Science.gov (United States)

Achard, Frédéric; Beuchle, René; Mayaux, Philippe; Stibig, Hans-Jürgen; Bodart, Catherine; Brink, Andreas; Carboni, Silvia; Desclée, Baudouin; Donnay, François; Eva, Hugh D; Lupi, Andrea; Raši, Rastislav; Seliger, Roman; Simonetti, Dario

2014-08-01

We estimate changes in forest cover (deforestation and forest regrowth) in the tropics for the two last decades (1990-2000 and 2000-2010) based on a sample of 4000 units of 10 ×10 km size. Forest cover is interpreted from satellite imagery at 30 × 30 m resolution. Forest cover changes are then combined with pan-tropical biomass maps to estimate carbon losses. We show that there was a gross loss of tropical forests of 8.0 million ha yr(-1) in the 1990s and 7.6 million ha yr(-1) in the 2000s (0.49% annual rate), with no statistically significant difference. Humid forests account for 64% of the total forest cover in 2010 and 54% of the net forest loss during second study decade. Losses of forest cover and Other Wooded Land (OWL) cover result in estimates of carbon losses which are similar for 1990s and 2000s at 887 MtC yr(-1) (range: 646-1238) and 880 MtC yr(-1) (range: 602-1237) respectively, with humid regions contributing two-thirds. The estimates of forest area changes have small statistical standard errors due to large sample size. We also reduce uncertainties of previous estimates of carbon losses and removals. Our estimates of forest area change are significantly lower as compared to national survey data. We reconcile recent low estimates of carbon emissions from tropical deforestation for early 2000s and show that carbon loss rates did not change between the two last decades. Carbon losses from deforestation represent circa 10% of Carbon emissions from fossil fuel combustion and cement production during the last decade (2000-2010). Our estimates of annual removals of carbon from forest regrowth at 115 MtC yr(-1) (range: 61-168) and 97 MtC yr(-1) (53-141) for the 1990s and 2000s respectively are five to fifteen times lower than earlier published estimates. © The Authors Global Change Biology Published by John Wiley & Sons Ltd.

Diffusive scattering of electrons by electron holes around injection fronts

Science.gov (United States)

Vasko, I. Y.; Agapitov, O. V.; Mozer, F. S.; Artemyev, A. V.; Krasnoselskikh, V. V.; Bonnell, J. W.

2017-03-01

Van Allen Probes have detected nonlinear electrostatic spikes around injection fronts in the outer radiation belt. These spikes include electron holes (EH), double layers, and more complicated solitary waves. We show that EHs can efficiently scatter electrons due to their substantial transverse electric fields. Although the electron scattering driven by EHs is diffusive, it cannot be evaluated via the standard quasi-linear theory. We derive analytical formulas describing local electron scattering by a single EH and verify them via test particle simulations. We show that the most efficiently scattered are gyroresonant electrons (crossing EH on a time scale comparable to the local electron gyroperiod). We compute bounce-averaged diffusion coefficients and demonstrate their dependence on the EH spatial distribution (latitudinal extent and spatial filling factor) and individual EH parameters (amplitude of electrostatic potential, velocity, and spatial scales). We show that EHs can drive pitch angle scattering of ≲5 keV electrons at rates 10-2-10-4 s-1 and, hence, can contribute to electron losses and conjugated diffuse aurora brightenings. The momentum and pitch angle scattering rates can be comparable, so that EHs can also provide efficient electron heating. The scattering rates driven by EHs at L shells L ˜ 5-8 are comparable to those due to chorus waves and may exceed those due to electron cyclotron harmonics.

The circumstellar shells and mass loss rates of four M supergiants

International Nuclear Information System (INIS)

Bernat, A.P.

1977-01-01

A reanalysis of the physical structure of the circumstellar gas shells of four bright M supergiants, Betelgeuse, Antares, α Herculis, and μ Cephei, has been undertaken. The observational data include old Hale Observatories plates, recent McDonald Struve telescope plates, and McDonald 2.7 m photoelectric scans. These data are analyzed in the full expanding spherical geometry formulation of the radiative transfer equation.The results of the present analysis indicate that column densities in the gas shells must be revised downward compared with the previous plane-parallel results. However, the physical extents of the shells are considerably larger than previously assumed. These extents are inferred through ionization modeling, Weymann's Ca II technique, and direct observation. Also inferred are schematic wavelength-dependent chromospheric color temperatures. These results lead to much larger mass loss rates (in the range 6.7 x 10 -7 to 4.2 x 10 -4 M/sub sun/ yr -2 ) than previously inferred. The influence of these large rates of mass loss on the evolution of both stars and the Galaxy is briefly discussed

Excitation of high-frequency electromagnetic waves by energetic electrons with a loss cone distribution in a field-aligned potential drop

Science.gov (United States)

Fung, Shing F.; Vinas, Adolfo F.

1994-01-01

The electron cyclotron maser instability (CMI) driven by momentum space anisotropy (df/dp (sub perpendicular) greater than 0) has been invoked to explain many aspects, such as the modes of propagation, harmonic emissions, and the source characteristics of the auroral kilometric radiation (AKR). Recent satellite observations of AKR sources indicate that the source regions are often imbedded within the auroral acceleration region characterized by the presence of a field-aligned potential drop. In this paper we investigate the excitation of the fundamental extraordinary mode radiation due to the accelerated electrons. The momentum space distribution of these energetic electrons is modeled by a realistic upward loss cone as modified by the presence of a parallel potential drop below the observation point. On the basis of linear growth rate calculations we present the emission characteristics, such as the frequency spectrum and the emission angular distribution as functions of the plasma parameters. We will discuss the implication of our results on the generation of the AKR from the edges of the auroral density cavities.

Electron energy distribution function, effective electron temperature, and dust charge in the temporal afterglow of a plasma

International Nuclear Information System (INIS)

Denysenko, I. B.; Azarenkov, N. A.; Kersten, H.

2016-01-01

Analytical expressions describing the variation of electron energy distribution function (EEDF) in an afterglow of a plasma are obtained. Especially, the case when the electron energy loss is mainly due to momentum-transfer electron-neutral collisions is considered. The study is carried out for different EEDFs in the steady state, including Maxwellian and Druyvesteyn distributions. The analytical results are not only obtained for the case when the rate for momentum-transfer electron-neutral collisions is independent on electron energy but also for the case when the collisions are a power function of electron energy. Using analytical expressions for the EEDF, the effective electron temperature and charge of the dust particles, which are assumed to be present in plasma, are calculated for different afterglow durations. An analytical expression for the rate describing collection of electrons by dust particles for the case when the rate for momentum-transfer electron-neutral collisions is independent on electron energy is also derived. The EEDF profile and, as a result, the effective electron temperature and dust charge are sufficiently different in the cases when the rate for momentum-transfer electron-neutral collisions is independent on electron energy and when the rate is a power function of electron energy.

Light Quality Affects Chloroplast Electron Transport Rates Estimated from Chl Fluorescence Measurements.

Science.gov (United States)

Evans, John R; Morgan, Patrick B; von Caemmerer, Susanne

2017-10-01

Chl fluorescence has been used widely to calculate photosynthetic electron transport rates. Portable photosynthesis instruments allow for combined measurements of gas exchange and Chl fluorescence. We analyzed the influence of spectral quality of actinic light on Chl fluorescence and the calculated electron transport rate, and compared this with photosynthetic rates measured by gas exchange in the absence of photorespiration. In blue actinic light, the electron transport rate calculated from Chl fluorescence overestimated the true rate by nearly a factor of two, whereas there was closer agreement under red light. This was consistent with the prediction made with a multilayer leaf model using profiles of light absorption and photosynthetic capacity. Caution is needed when interpreting combined measurements of Chl fluorescence and gas exchange, such as the calculation of CO2 partial pressure in leaf chloroplasts. © Crown copyright 2017.

Calculation of radiation loss of 1. 2 GeV-electrons in a thick silicon monocrystal

Energy Technology Data Exchange (ETDEWEB)

Keshtova, S.V.; Komarov, F.F.; Telegin, V.I.

1988-10-01

The angular distribution of radiation loss of different fractions of 1.2 GeV-electrons during axial channeling in a Si monocrystal of 1.6 mm thickness is discussed. The results of the numerical calculations are compared with the experimental data.

Mechanism and rate of denitrification in an agricultural watershed: Electron and mass balance along groundwater flow paths

Science.gov (United States)

Tesoriero, Anthony J.; Liebscher, Hugh; Cox, Stephen E.

2000-01-01

The rate and mechanism of nitrate removal along and between groundwater flow paths were investigated using a series of well nests screened in an unconfined sand and gravel aquifer. Intensive agricultural activity in this area has resulted in nitrate concentrations in groundwater often exceeding drinking water standards. Both the extent and rate of denitrification varied depending on the groundwater flow path. While little or no denitrification occurred in much of the upland portions of the aquifer, a gradual redox gradient is observed as aerobic upland groundwater moves deeper in the aquifer. In contrast, a sharp shallow redox gradient is observed adjacent to a third‐order stream as aerobic groundwater enters reduced sediments. An essentially complete loss of nitrate concurrent with increases in excess N2 provide evidence that denitrification occurs as groundwater enters this zone. Electron and mass balance calculations suggest that iron sulfide (e.g., pyrite) oxidation is the primary source of electrons for denitrification. Denitrification rate estimates were based on mass balance calculations using nitrate and excess N2 coupled with groundwater travel times. Travel times were determined using a groundwater flow model and were constrained by chlorofluorocarbon‐based age dates. Denitrification rates were found to vary considerably between the two areas where denitrification occurs. Denitrification rates in the deep, upland portions of the aquifer were found to range from from 1.0 to 2.7 mM of N per year. Potential denitrification rates in groundwater adjacent to the stream may be much faster, with rates up to 140 mM per year based on an in situ experiment conducted in this zone.

On the role of the gas environment, electron-dose-rate, and sample on the image resolution in transmission electron microscopy

DEFF Research Database (Denmark)

Ek, Martin; Jespersen, Sebastian Pirel Fredsgaard; Damsgaard, Christian Danvad

2016-01-01

on the electron-dose-rate. In this article, we demonstrate that both the total and areal electron-dose-rates work as descriptors for the dose-rate-dependent resolution and are related through the illumination area. Furthermore, the resolution degradation was observed to occur gradually over time after......The introduction of gaseous atmospheres in transmission electron microscopy offers the possibility of studying materials in situ under chemically relevant environments. The presence of a gas environment can degrade the resolution. Surprisingly, this phenomenon has been shown to depend...... initializing the illumination of the sample and gas by the electron beam. The resolution was also observed to be sensitive to the electrical conductivity of the sample. These observations can be explained by a charge buildup over the electron-illuminated sample area, caused by the beam–gas–sample interaction...

Parameterization of ionization rate by auroral electron precipitation in Jupiter

Directory of Open Access Journals (Sweden)

Y. Hiraki

2008-02-01

Full Text Available We simulate auroral electron precipitation into the Jovian atmosphere in which electron multi-directional scattering and energy degradation processes are treated exactly with a Monte Carlo technique. We make a parameterization of the calculated ionization rate of the neutral gas by electron impact in a similar way as used for the Earth's aurora. Our method allows the altitude distribution of the ionization rate to be obtained as a function of an arbitrary initial energy spectrum in the range of 1–200 keV. It also includes incident angle dependence and an arbitrary density distribution of molecular hydrogen. We show that there is little dependence of the estimated ionospheric conductance on atomic species such as H and He. We compare our results with those of recent studies with different electron transport schemes by adapting our parameterization to their atmospheric conditions. We discuss the intrinsic problem of their simplified assumption. The ionospheric conductance, which is important for Jupiter's magnetosphere-ionosphere coupling system, is estimated to vary by a factor depending on the electron energy spectrum based on recent observation and modeling. We discuss this difference through the relation with field-aligned current and electron spectrum.

Dispersion relation and growth rate in a Cherenkov free electron laser: Finite axial magnetic field

International Nuclear Information System (INIS)

Kheiri, Golshad; Esmaeilzadeh, Mahdi

2013-01-01

A theoretical analysis is presented for dispersion relation and growth rate in a Cherenkov free electron laser with finite axial magnetic field. It is shown that the growth rate and the resonance frequency of Cherenkov free electron laser increase with increasing axial magnetic field for low axial magnetic fields, while for high axial magnetic fields, they go to a saturation value. The growth rate and resonance frequency saturation values are exactly the same as those for infinite axial magnetic field approximation. The effects of electron beam self-fields on growth rate are investigated, and it is shown that the growth rate decreases in the presence of self-fields. It is found that there is an optimum value for electron beam density and Lorentz relativistic factor at which the maximum growth rate can take place. Also, the effects of velocity spread of electron beam are studied and it is found that the growth rate decreases due to the electron velocity spread

Suprathermal electron loss cone distributions in the solar wind: Ulysses observations

International Nuclear Information System (INIS)

Phillips, J. L.; Feldman, W. C.; Gosling, J. T.; Hammond, C. M.; Forsyth, R. J.

1996-01-01

We present observations by the Ulysses solar wind plasma experiment of a new class of suprathermal electron signatures. At low solar latitudes and heliocentric distances beyond 3.37 AU Ulysses encountered seven intervals, ranging in duration from 1 hour to 22 hours, in which the suprathermal distributions included an antisunward field-aligned beam and a return population with a flux dropout typically spanning ±60 deg. from the sunward field-aligned direction. All events occurred between the forward and reverse shocks or waves bounding corotating interaction regions (CIRs). The observations support a scenario in which the sunward-moving electrons result from reflection of the prevailing antisunward field-aligned beam at magnetic field compressions downstream from the spacecraft, with wide loss cones caused by the relatively weak mirror ratio. This hypothesis requires that the field magnitude within the CIRs actually increased locally with increasing field-aligned distance from the Sun

Radiative interaction of a focused relativistic electron beam in energy-loss spectroscopy of nanoscopic platelets

International Nuclear Information System (INIS)

Itskovsky, M. A.; Maniv, T.; Cohen, H.

2008-01-01

A quantum-mechanical scattering theory for relativistic, highly focused electron beams in the vacuum near nanoscopic platelets is presented, revealing an excitation mechanism due to the electron wave scattering from the platelet edges. Radiative electromagnetic excitations within the light cone are shown to arise, allowed by the breakdown of momentum conservation along the beam axis in the inelastic-scattering process. Calculated for metallic (silver and gold) and insulating (SiO 2 and MgO) nanoplatelets, radiative features are revealed above the main surface-plasmon-polariton peak, and dramatic enhancements in the electron-energy-loss probability at gaps of the 'classical' spectra are found. The corresponding radiation should be detectable in the vacuum far-field zone, with e beams exploited as sensitive 'tip detectors' of electronically excited nanostructures

Calculation of radiation loss of 1.2 GeV-electrons in a thick silicon monocrystal

International Nuclear Information System (INIS)

Keshtova, S.V.; Komarov, F.F.

1988-01-01

The angular distribution of radiation loss of different fractions of 1.2 GeV-electrons during axial channeling in a Si monocrystal of 1.6 mm thickness is discussed. The results of the numerical calculations are compared with the experimental data. (author)

Experimental investigation of the trapping and energy loss mechanisms of intense relativistic electron rings in hydrogen gas and plasma

International Nuclear Information System (INIS)

Smith, A.C. Jr.

1977-01-01

The results of an experimental study on the trapping and energy loss mechanisms of intense, relativistic electron rings confined in Astron-like magnetic field geometries are presented. The work is subdivided into four sections: gas trapping; average ring electron energetics; plasma trapping, and hollow-beam cusp-injection into gas and plasma. The mechanisms by which the injected beam coalesces into a current ring in the existing Cornell RECE-Berta facility are considered. To investigate the nature of ring electron energy loss mechanisms following completion of the trapping process, a diagnostic was developed utilizing multi-foil X-ray absorption spectroscopy to analyze the Bremsstrahlung generated by the electrons as they impinge upon a thin tungsten wire target suspended in the circulating current. Finally, a set of preliminary experimental results is presented in which an annular electron beam was passed through a coaxial, non-adiabatic magnetic cusp located at one end of a magnetic mirror well

Free electrons and ionic liquids: study of excited states by means of electron-energy loss spectroscopy and the density functional theory multireference configuration interaction method.

Science.gov (United States)

Regeta, Khrystyna; Bannwarth, Christoph; Grimme, Stefan; Allan, Michael

2015-06-28

The technique of low energy (0-30 eV) electron impact spectroscopy, originally developed for gas phase molecules, is applied to room temperature ionic liquids (IL). Electron energy loss (EEL) spectra recorded near threshold, by collecting 0-2 eV electrons, are largely continuous, assigned to excitation of a quasi-continuum of high overtones and combination vibrations of low-frequency modes. EEL spectra recorded by collecting 10 eV electrons show predominantly discrete vibrational and electronic bands. The vibrational energy-loss spectra correspond well to IR spectra except for a broadening (∼0.04 eV) caused by the liquid surroundings, and enhanced overtone activity indicating a contribution from resonant excitation mechanism. The spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations, with good agreement. The spectra up to about 8 eV are dominated by π-π* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without π orbitals. The EEL spectrum of a saturated solution of methylene green in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study nonvolatile compounds by this technique in the future.

Phonon spectrum of single-crystalline FeSe probed by high-resolution electron energy-loss spectroscopy

Science.gov (United States)

Zakeri, Khalil; Engelhardt, Tobias; Le Tacon, Matthieu; Wolf, Thomas

2018-06-01

Utilizing high-resolution electron energy-loss spectroscopy (HREELS) we measure the phonon frequencies of β-FeSe(001), cleaved under ultra-high vacuum conditions. At the zone center (Γ bar-point) three prominent loss features are observed at loss energies of about ≃ 20.5 and 25.6 and 40 meV. Based on the scattering selection rules we assign the observed loss features to the A1g, B1g, and A2u phonon modes of β-FeSe(001). The experimentally measured phonon frequencies do not agree with the results of density functional based calculations in which a nonmagnetic, a checkerboard or a strip antiferromagnetic order is assumed for β-FeSe(001). Our measurements suggest that, similar to the other Fe-based materials, magnetism has a profound impact on the lattice dynamics of β-FeSe(001).

Effects of ionization and ion loss on dust ion- acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

Science.gov (United States)

Tribeche, Mouloud; Mayout, Saliha

2016-07-01

The combined effects of ionization, ion loss and electron suprathermality on dust ion- acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg- de Vries (dK-- dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK- dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the DIA solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.

Distorted wave calculations for electron loss process induced by bare ion impact on biological targets

International Nuclear Information System (INIS)

Monti, J.M.; Tachino, C.A.; Hanssen, J.; Fojón, O.A.; Galassi, M.E.; Champion, C.; Rivarola, R.D.

2014-01-01

Distorted wave models are employed to investigate the electron loss process induced by bare ions on biological targets. The two main reactions which contribute to this process, namely, the single electron ionization as well as the single electron capture are here studied. In order to further assess the validity of the theoretical descriptions used, the influence of particular mechanisms are studied, like dynamic screening for the case of electron ionization and energy deposition on the target by the impacting projectile for the electron capture one. Results are compared with existing experimental data. - Highlights: ► Distorted wave models are used to investigate ion-molecule collisions. ► Differential and total cross-sections for capture and ionization are evaluated. ► The influence of dynamic screening is determined. ► Capture reaction dominates the mean energy deposited by the projectile on the target

Design and performance of a spin-polarized electron energy loss spectrometer with high momentum resolution

Energy Technology Data Exchange (ETDEWEB)

Vasilyev, D.; Kirschner, J. [Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

2016-08-15

We describe a new “complete” spin-polarized electron energy loss spectrometer comprising a spin-polarized primary electron source, an imaging electron analyzer, and a spin analyzer of the “spin-polarizing mirror” type. Unlike previous instruments, we have a high momentum resolution of less than 0.04 Å{sup −1}, at an energy resolution of 90-130 meV. Unlike all previous studies which reported rather broad featureless data in both energy and angle dependence, we find richly structured spectra depending sensitively on small changes of the primary energy, the kinetic energy after scattering, and of the angle of incidence. The key factor is the momentum resolution.

Simulation of equivalent dose due to accidental electron beam loss in Indus-1 and Indus-2 synchrotron radiation sources using FLUKA code

International Nuclear Information System (INIS)

Sahani, P.K.; Dev, Vipin; Singh, Gurnam; Haridas, G.; Thakkar, K.K.; Sarkar, P.K.; Sharma, D.N.

2008-01-01

Indus-1 and Indus-2 are two Synchrotron radiation sources at Raja Ramanna Centre for Advanced Technology (RRCAT), India. Stored electron energy in Indus-1 and Indus-2 are 450MeV and 2.5GeV respectively. During operation of storage ring, accidental electron beam loss may occur in addition to normal beam losses. The Bremsstrahlung radiation produced due to the beam losses creates a major radiation hazard in these high energy electron accelerators. FLUKA, the Monte Carlo radiation transport code is used to simulate the accidental beam loss. The simulation was carried out to estimate the equivalent dose likely to be received by a trapped person closer to the storage ring. Depth dose profile in water phantom for 450MeV and 2.5GeV electron beam is generated, from which percentage energy absorbed in 30cm water phantom (analogous to human body) is calculated. The simulation showed the percentage energy deposition in the phantom is about 19% for 450MeV electron and 4.3% for 2.5GeV electron. The dose build up factor in 30cm water phantom for 450MeV and 2.5GeV electron beam are found to be 1.85 and 2.94 respectively. Based on the depth dose profile, dose equivalent index of 0.026Sv and 1.08Sv are likely to be received by the trapped person near the storage ring in Indus-1 and Indus-2 respectively. (author)

The reaction rates of electrons with native and irradiated ribonuclease

International Nuclear Information System (INIS)

Schuessler, H.; Ebert, M.; Davies, J.V.

1977-01-01

The rate of reaction of hydrated electrons with proteins depends, amongst other things, on the conformational structure of the protein, and irradiation itself causes conformational changes in proteins. A study has been made of variations in the reaction rates of hydrated electrons with RNase pre-irradiated by the Linac or by a 60 Co γ-source. The reaction rate constants varied with the pre-irradiation dose, the concentration of phosphate buffer, the enzyme concentration and also the presence of 10 -2 M ethanol. These variations serve to emphasize the importance of the tertiary structure of biological molecules in irradiation processes and have significant implications in the mathematical analysis of the inactivation of enzymes in steady-state irradiation processes. (U.K.)

Electron transfer rates and energy releases during denitrification of municipal wastewater

DEFF Research Database (Denmark)

Abdul-Talib, S.; Ujang, Z; Vollertsen, J.

2004-01-01

could be simplified by a two-stage process. In the first stage, nitrate was utilised with significant accumulation of nitrite. In the second stage nitrite was utilised when nitrate depleted. Denitrification rates during the two stages were expressed in terms of electron equivalents (e-eq.) in order...... to compare the process when differennt electron acceptors namlely, nitrate and nitrite were utilised. The energy release rates during the two stages were calculated and compared....

Rate coefficients for low-energy electron dissociative attachment to molecular hydrogen

International Nuclear Information System (INIS)

Horacek, J.; Houfek, K.; Cizek, M.; Murakami, I.; Kato, T.

2003-02-01

Calculation of rate constants for dissociative electron attachment to molecular hydrogen is reported. The calculation is based on an improved nonlocal resonance model of Cizek, Horacek and Domcke which takes fully into account the nonlocality of the resonance dynamics and uses potentials with correct asymptotic forms. The rate constants are calculated for all quantum numbers v and J of the target molecules and for electron temperature in the range 0-30000 K. (author)

Martian Dust Devil Electron Avalanche Process and Associated Electrochemistry

Science.gov (United States)

Jackson, Telana L.; Farrell, William M.; Delory, Gregory T.; Nithianandam, Jeyasingh

2010-01-01

Mars' dynamic atmosphere displays localized dust devils and larger, global dust storms. Based on terrestrial analog studies, electrostatic modeling, and laboratory work these features will contain large electrostatic fields formed via triboelectric processes. In the low-pressure Martian atmosphere, these fields may create an electron avalanche and collisional plasma due to an increase in electron density driven by the internal electrical forces. To test the hypothesis that an electron avalanche is sustained under these conditions, a self-consistent atmospheric process model is created including electron impact ionization sources and electron losses via dust absorption, electron dissociation attachment, and electron/ion recombination. This new model is called the Dust Devil Electron Avalanche Model (DDEAM). This model solves simultaneously nine continuity equations describing the evolution of the primary gaseous chemical species involved in the electrochemistry. DDEAM monitors the evolution of the electrons and primary gas constituents, including electron/water interactions. We especially focus on electron dynamics and follow the electrons as they evolve in the E field driven collisional gas. When sources and losses are self-consistently included in the electron continuity equation, the electron density grows exponentially with increasing electric field, reaching an equilibrium that forms a sustained time-stable collisional plasma. However, the character of this plasma differs depending upon the assumed growth rate saturation process (chemical saturation versus space charge). DDEAM also shows the possibility of the loss of atmospheric methane as a function of electric field due to electron dissociative attachment of the hydrocarbon. The methane destruction rates are presented and can be included in other larger atmospheric models.

Retrograde amnesia produced by electron beam exposure: casual parameters and duration of memory loss. Final report for November 84

Energy Technology Data Exchange (ETDEWEB)

Wheeler, T.G.; Hardy, K.A.

1985-01-01

The production of retrograde amnesia (RA) upon electron-beam exposure was investigated. RA production was evaluated using a single-trial avoidance task for 10, 1, and 0.1 microsecond pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 1,000,000 rad/sec. By employing a 10 rad (1,000,000 rad/s) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory system activation which provided a novel stimulus that masked previous stimuli.

The loss rates of O{sup +} in the inner magnetosphere caused by both magnetic field line curvature scattering and charge exchange reactions

Energy Technology Data Exchange (ETDEWEB)

Ji, Y., E-mail: yji@spaceweather.ac.cn [State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049 (China); Shen, C. [State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China)

2014-03-15

With consideration of magnetic field line curvature (FLC) pitch angle scattering and charge exchange reactions, the O{sup +} (>300 keV) in the inner magnetosphere loss rates are investigated by using an eigenfunction analysis. The FLC scattering provides a mechanism for the ring current O{sup +} to enter the loss cone and influence the loss rates caused by charge exchange reactions. Assuming that the pitch angle change is small for each scattering event, the diffusion equation including a charge exchange term is constructed and solved; the eigenvalues of the equation are identified. The resultant loss rates of O{sup +} are approximately equal to the linear superposition of the loss rate without considering the charge exchange reactions and the loss rate associated with charge exchange reactions alone. The loss time is consistent with the observations from the early recovery phases of magnetic storms.

Theoretical study of electronic transfer current rate at dye-sensitized solar cells

Science.gov (United States)

AL-Agealy, Hadi J. M.; AlMaadhede, Taif Saad; Hassooni, Mohsin A.; Sadoon, Abbas K.; Ashweik, Ahmed M.; Mahdi, Hind Abdlmajeed; Ghadhban, Rawnaq Qays

2018-05-01

In this research, we present a theoretical study of electronic transfer kinetics rate in N719/TiO2 and N719/ZnO dye-sensitized solar cells (DSSC) systems using a simple model depending on the postulate of quantum mechanics theory. The evaluation of the electronic transition current rate in DSSC systems are function of many parameters such that; the reorientation transition energies ΛSe m D y e , the transition coupling parameter ℂT(0), potential exponential effect e-(E/C-EF ) kBT , unit cell volume VSem, and temperature T. Furthermore, the analysis of electronic transfer current rate in N719/TiO2 and N719/ZnO systems show that the rate upon dye-sensitization solar cell increases with increases of transition coupling parameter, decreasing potential that building at interface a results of different material in this devices and increasing with reorientation transition energy. On the other hand, we can find the electronic transfer behavior is dependent of the dye absorption spectrum and mainly depending on the reorientation of transition energy. The replacement of the solvents in both DSSC system caused increasing of current rates dramatically depending on polarity of solvent in subset devices. This change in current rate of electron transfer were attributed to much more available of recombination sites introduced by the solvents medium. The electronic transfer current dynamics are shown to occurs in N719/TiO2 system faster many time compare to ocuures at N719/ZnO system, this indicate that TiO2 a is a good and active material compare with ZnO to using in dye sensitized solar cell devices. In contrast, the large current rate in N719/TiO2 comparing to ZnO of N719/ZnO systems indicate that using TiO2 with N719 dye lead to increasing the efficiency of DSSC.

Radiative interaction of a focused relativistic electron beam in energy-loss spectroscopy of nanoscopic platelets

Science.gov (United States)

Itskovsky, M. A.; Cohen, H.; Maniv, T.

2008-07-01

A quantum-mechanical scattering theory for relativistic, highly focused electron beams in the vacuum near nanoscopic platelets is presented, revealing an excitation mechanism due to the electron wave scattering from the platelet edges. Radiative electromagnetic excitations within the light cone are shown to arise, allowed by the breakdown of momentum conservation along the beam axis in the inelastic-scattering process. Calculated for metallic (silver and gold) and insulating ( SiO2 and MgO) nanoplatelets, radiative features are revealed above the main surface-plasmon-polariton peak, and dramatic enhancements in the electron-energy-loss probability at gaps of the “classical” spectra are found. The corresponding radiation should be detectable in the vacuum far-field zone, with e beams exploited as sensitive “tip detectors” of electronically excited nanostructures.

Energy-filtered real- and k-space secondary and energy-loss electron imaging with Dual Emission Electron spectro-Microscope: Cs/Mo(110)

Energy Technology Data Exchange (ETDEWEB)

Grzelakowski, Krzysztof P., E-mail: k.grzelakowski@opticon-nanotechnology.com

2016-05-15

Since its introduction the importance of complementary k{sub ||}-space (LEED) and real space (LEEM) information in the investigation of surface science phenomena has been widely demonstrated over the last five decades. In this paper we report the application of a novel kind of electron spectromicroscope Dual Emission Electron spectroMicroscope (DEEM) with two independent electron optical channels for reciprocal and real space quasi-simultaneous imaging in investigation of a Cs covered Mo(110) single crystal by using the 800 eV electron beam from an “in-lens” electron gun system developed for the sample illumination. With the DEEM spectromicroscope it is possible to observe dynamic, irreversible processes at surfaces in the energy-filtered real space and in the corresponding energy-filtered k{sub ǁ}-space quasi-simultaneously in two independent imaging columns. The novel concept of the high energy electron beam sample illumination in the cathode lens based microscopes allows chemically selective imaging and analysis under laboratory conditions. - Highlights: • A novel concept of the electron sample illumination with “in-lens” e- gun is realized. • Quasi-simultaneous energy selective observation of the real- and k-space in EELS mode. • Observation of the energy filtered Auger electron diffraction at Cs atoms on Mo(110). • Energy-loss, Auger and secondary electron momentum microscopy is realized.

Electron loss from 0.74 and 1.4 MeV/u low-charge-state argon and xenon ions colliding with neon, nitrogen, and argon

International Nuclear Information System (INIS)

DuBois, R.D.; Santos, A.C.F.; Olson, R.E.

2003-07-01

Absolute total, single, and multiple electron loss cross sections are measured for Ar + -, Ar 2+ -, and Xe 3+ - Ne, N 2 , Ar collisions at 0.74 and 1.4 MeV/u. In addition, a many-body Classical Trajectory Monte Carlo model was used to calculate total and multiple electron loss cross sections for Ar + impact. For N 2 and Ar targets, excellent agreement between the measured and calculated cross sections is found; for the Ne target the experimental data are approximately 40% smaller than the theoretical predictions. The experimental data are also used to examine cross section scaling characteristics for electron loss from fast, low-charge-state, heavy ions. It is shown that multiple electron loss increased the mean charge states of the outgoing argon and xenon ions by two and three respectively. The cross sections decreased with increasing number of electrons lost and scaled roughly as the inverse of the sum of the ionization potentials required to sequentially remove the most weakly bound, next most weakly bound, etc., electrons. This scaling was found to be independent of projectile, incoming charge state, and target. In addition, the experimental total loss cross sections are found to be nearly constant as a function of initial projectile charge state. As a function of impact energy, the theoretical predictions yield an E -1/3 behavior between 0.5 and 30 MeV/u for the total loss cross sections. Within error bars the data are consistent with this energy dependence but are also consistent with an E -1/2 energy dependence. (orig.)

Measurement of power loss during electric vehicle charging and discharging

International Nuclear Information System (INIS)

Apostolaki-Iosifidou, Elpiniki; Codani, Paul; Kempton, Willett

2017-01-01

When charging or discharging electric vehicles, power losses occur in the vehicle and the building systems supplying the vehicle. A new use case for electric vehicles, grid services, has recently begun commercial operation. Vehicles capable of such application, called Grid-Integrated Vehicles, may have use cases with charging and discharging summing up to much more energy transfer than the charging only use case, so measuring and reducing electrical losses is even more important. In this study, the authors experimentally measure and analyze the power losses of a Grid-Integrated Vehicle system, via detailed measurement of the building circuits, power feed components, and of sample electric vehicle components. Under the conditions studied, measured total one-way losses vary from 12% to 36%, so understanding loss factors is important to efficient design and use. Predominant losses occur in the power electronics used for AC-DC conversion. The electronics efficiency is lowest at low power transfer and low state-of-charge, and is lower during discharging than charging. Based on these findings, two engineering design approaches are proposed. First, optimal sizing of charging stations is analyzed. Second, a dispatch algorithm for grid services operating at highest efficiency is developed, showing 7.0% to 9.7% less losses than the simple equal dispatch algorithm. - Highlights: • Grid-to-battery-to-grid comprehensive power loss measurement and analysis. • No previous experimental measurements of Grid-Integrated Vehicle system power loss. • Electric vehicle loss analyzed as a factor of state of charge and charging rate. • Power loss in the building components less than 3%. • Largest losses found in Power Electronics (typical round-trip loss 20%).

Prior rates of visual field loss and lifetime risk of blindness in glaucomatous patients undergoing trabeculectomy.

Science.gov (United States)

Foulsham, W S; Fu, L; Tatham, A J

2015-10-01

Trend-based analyses examining rates of visual field (VF) loss in glaucoma are useful for predicting risk of vision-related morbidity. Although patients with faster losses are likely to require treatment escalation, little is known about rates that might trigger a decision to intervene surgically. The aims of this study were to investigate prior rates of VF loss in patients attending for trabeculectomy and to estimate, in the absence of surgical intervention, lifetime risk of visual impairment, and blindness. A retrospective analysis of 117 eyes of 86 consecutive patients with glaucoma attending for trabeculectomy, including 53 patients referred from general ophthalmology clinics and 33 patients from specialist glaucoma clinics. Rates of change in standard automated perimetry mean deviation were examined using linear regression and random coefficient models. Risk of lifetime visual impairment and blindness was calculated using life expectancy data. Mean age at surgery was 71.0±9.7 years. Patients were followed for 10.7±7.5 years prior to surgery with an average of seven useable fields per eye. On average patients referred from general clinics lost 1.04 dB/year compared with 0.77 dB/year in those referred from glaucoma clinics (P=0.070). Patients referred from general clinics had more medication changes prior to surgery (3.4 and 2.6 changes, respectively; P=0.004). Given Scottish life expectancy data, untreated, 61 eyes (52%) would have passed the threshold for visual impairment, whereas 40 (34%) would have passed the threshold demarcating blindness. Patients attending for trabeculectomy had faster average rates of field loss prior to surgery than published values for the general glaucoma population with over one-third of eyes studied predicted to have become blind without intervention. Those managed by glaucoma specialists had fewer changes in medication and tended to slower rates of VF loss, although the latter did not reach statistical significance.

Gender differences in scalp hair growth rates are maintained but reduced in pattern hair loss compared to controls.

Science.gov (United States)

Van Neste, D J J; Rushton, D H

2016-08-01

Hair loss is related to follicular density, programmed regrowth and hair productivity. The dissatisfaction with hair growth in patients experiencing hair loss might be due to slower linear hair growth rate (LHGR). LHGR and hair diameter was evaluated in Caucasian controls and patients with patterned hair loss employing the validated non-invasive, contrast-enhanced-phototrichogram with exogen collection. We evaluated 59,765 anagen hairs (controls 24,609, patients 35,156) and found thinner hairs grew slower than thicker hairs. LHGR in normal women was generally higher than in normal men. LHGR correlates with hair diameter (P hair of equal thickness in controls, subjects affected with patterned hair loss showed reduced hair growth rates, an observation found in both male and female patients. Males with pattern hair loss showed further reduction in growth rates as clinical severity worsened. However, sample size limitations prevented statistical evaluation of LHGR in severely affected females. Caucasian ethnicity. In pattern hair loss, LHGR significantly contributes to the apparent decrease in hair volume in affected areas. In early onset, LHRG might have a prognostic value in females but not in males. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effects of ionization and ion loss on dust ion-acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

Energy Technology Data Exchange (ETDEWEB)

Mayout, Saliha; Gougam, Leila Ait [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria); Tribeche, Mouloud, E-mail: mouloudtribeche@yahoo.fr, E-mail: mtribeche@usthb.dz [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria); Algerian Academy of Sciences and Technologies, Algiers (Algeria)

2016-03-15

The combined effects of ionization, ion loss, and electron suprathermality on dust ion-acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg-de Vries (dK–dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK-dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the dust ion-acoustic solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.

Effects of ionization and ion loss on dust ion-acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

International Nuclear Information System (INIS)

Mayout, Saliha; Gougam, Leila Ait; Tribeche, Mouloud

2016-01-01

The combined effects of ionization, ion loss, and electron suprathermality on dust ion-acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg-de Vries (dK–dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK-dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the dust ion-acoustic solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.

A comparative study of different methods for calculating electronic transition rates

Science.gov (United States)

Kananenka, Alexei A.; Sun, Xiang; Schubert, Alexander; Dunietz, Barry D.; Geva, Eitan

2018-03-01

We present a comprehensive comparison of the following mixed quantum-classical methods for calculating electronic transition rates: (1) nonequilibrium Fermi's golden rule, (2) mixed quantum-classical Liouville method, (3) mean-field (Ehrenfest) mixed quantum-classical method, and (4) fewest switches surface-hopping method (in diabatic and adiabatic representations). The comparison is performed on the Garg-Onuchic-Ambegaokar benchmark charge-transfer model, over a broad range of temperatures and electronic coupling strengths, with different nonequilibrium initial states, in the normal and inverted regimes. Under weak to moderate electronic coupling, the nonequilibrium Fermi's golden rule rates are found to be in good agreement with the rates obtained via the mixed quantum-classical Liouville method that coincides with the fully quantum-mechanically exact results for the model system under study. Our results suggest that the nonequilibrium Fermi's golden rule can serve as an inexpensive yet accurate alternative to Ehrenfest and the fewest switches surface-hopping methods.

The effects of high electronic energy loss on the chemical modification of polyimide

CERN Document Server

SunYouMei; Jin Yun Fan; Liu Chang Long; LiuJie; Wang Zhi Guang; Zhang Qi; Zhu Zhi Yong

2002-01-01

In order to observe the role of electronic energy loss (dE/dX) sub e on chemical modification of polyimide (PI), the multi-layer stacks (corresponding to different dE/dX) were irradiated by different swift heavy ions (1.37 GeV Ar sup 4 sup 0 , 1.98 GeV Kr sup 8 sup 4 , 1.755 GeV Xe sup 1 sup 3 sup 6 and 2.636 GeV U sup 2 sup 3 sup 8) under vacuum and room temperature. The chemical changes of modified PI films were studied by Fourier transform infrared (FTIR) and ultraviolet/visible (UV/Vis) absorption spectroscopy. The degradation of PI was investigated in the fluence range from 1x10 sup 1 sup 0 to 5.5x10 sup 1 sup 2 ions/cm sup 2 and different electronic energy loss from 0.77 to 11.5 keV/nm. The FTIR results show the absorbance of the typical function group decrease exponentially as a function of fluence. The alkyne end group was found after irradiation and its formation radii were 5.6 and 5.9 nm corresponding to 8.8 and 11.5 keV/nm Xe irradiation respectively. UV/Vis analysis indicates the radiation induced...

Food loss rates at the food retail, influencing factors and reasons as a basis for waste prevention measures.

Science.gov (United States)

Lebersorger, S; Schneider, F

2014-11-01

This paper quantifies food loss rates for fruit & vegetables, dairy products and bread & pastry as well as donations to social services. In addition potential influencing factors and reasons for food losses are investigated in order to provide a basis for the development of waste prevention measures. Detailed data from 612 retail outlets all over Austria, which covered the period of one year, were analysed and sorting analyses of discarded food were carried out in a small sample of retail outlets. Food loss amounts to 1.3% of the sales of dairy products, 2.8% for bread & pastry and 4.2% for fruit & vegetables. Returned bread amounts to additional 9.7% of the sales of bread & pastry. The food loss rates are similar to the results of previous publications. At present, 7% of the food loss is donated to social services, 38% of retail outlets do not donate any articles at all. Food loss rates are declining with increasing sales areas, increasing numbers of purchases per year and increasing sales of the retail outlet, but explain only 33% or less of the variation of food loss rates. Large differences between retail outlets of comparable structure indicate potential for reduction. More than a quarter of discarded food articles did not show any flaws besides the expiration of the best before or sell-by date. Waste prevention approaches should focus on avoiding returns, transfer of best practices, information and education of employees and customers as well as strengthening the donation to social services. Copyright © 2014 Elsevier Ltd. All rights reserved.

Electron-beam induced amorphization of stishovite: Silicon-coordination change observed using Si K-edge extended electron energy-loss fine structure

Science.gov (United States)

van Aken, P. A.; Sharp, T. G.; Seifert, F.

The analysis of the extended energy-loss fine structure (EXELFS) of the Si K-edge for sixfold-coordinated Si in synthetic stishovite and fourfold-coordinated Si in natural α-quartz is reported by using electron energy-loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM). The stishovite Si K-edge EXELFS spectra were measured as a time-dependent series to document irradiation-induced amorphization. The amorphization was also investigated through the change in Si K- and O K-edge energy-loss near edge structure (ELNES). For α-quartz, in contrast to stishovite, electron irradiation-induced vitrification, verified by selected area electron diffraction (SAED), produced no detectable changes of the EXELFS. The Si K-edge EXELFS were analysed with the classical extended X-ray absorption fine structure (EXAFS) treatment and compared to ab initio curve-waved multiple-scattering (MS) calculations of EXAFS spectra for stishovite and α-quartz. Highly accurate information on the local atomic environment of the silicon atoms during the irradiation-induced amorphization of stishovite is obtained from the EXELFS structure parameters (Si-O bond distances, coordination numbers and Debye-Waller factors). The mean Si-O bond distance R and mean Si coordination number N changes from R=0.1775 nm and N=6 for stishovite through a disordered intermediate state (R 0.172 nm and N 5) to R 0.167 nm and N 4.5 for a nearly amorphous state similar to α-quartz (R=0.1609 nm and N=4). During the amorphization process, the Debye-Waller factor (DWF) passes through a maximum value of as it changes from for sixfold to for fourfold coordination of Si. This increase in Debye-Waller factor indicates an increase in mean-square relative displacement (MSRD) between the central silicon atom and its oxygen neighbours that is consistent with the presence of an intermediate structural state with fivefold coordination of Si. The distribution of coordination states can be estimated by

Preoperative weight loss in super-obese patients: study of the rate of weight loss and its effects on surgical morbidity

Directory of Open Access Journals (Sweden)

Marco Aurelio Santo

2014-01-01

Full Text Available OBJECTIVES: The incidence of obesity and particularly super obesity, has increased tremendously. At our institution, super obesity represents 30.1% of all severely obese individuals in the bariatric surgery program. In super obesity, surgical morbidity is higher and the results are worse compared with morbid obesity, independent of the surgical technique. The primary strategy for minimizing complications in these patients is to decrease the body mass index before surgery. Preoperative weight reduction can be achieved by a hypocaloric diet, drug therapy, an intragastric balloon, or hospitalization. The objective of this study was to analyze the results of a period of hospitalization for preoperative weight loss in a group of super-obese patients. METHODS: Twenty super-obese patients were submitted to a weight loss program between 2006 and 2010. The mean patient age was 46 years (range 21-59. The mean BMI was 66 kg/m2 (range 51-98 and 12 were women. The average hospital stay was 19.9 weeks and the average weight loss was 19% of the initial weight (7-37%. The average caloric intake was 5 kcal/kg/day. After the weight loss program, the patients underwent gastric bypass surgery. RESULTS: The statistical analysis revealed that after 14 weeks of treatment (15% loss of initial weight, the weight loss was not significant. All patients had satisfactory surgical recovery and were discharged after an average of 4.6 days. CONCLUSION: In super obesity, preoperative weight loss is an important method for reducing surgical risks. Hospitalization and a hypocaloric diet are safe and effective. After 14 weeks, the weight loss rate stabilized, signaling the time of surgical intervention in our study.

Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

Science.gov (United States)

He, Z.-H.; Thomas, A. G. R.; Beaurepaire, B.; Nees, J. A.; Hou, B.; Malka, V.; Krushelnick, K.; Faure, J.

2013-02-01

We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

Energy Technology Data Exchange (ETDEWEB)

He, Z.-H.; Thomas, A. G. R.; Nees, J. A.; Hou, B.; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48106-2099 (United States); Beaurepaire, B.; Malka, V.; Faure, J. [Laboratoire d' Optique Appliquee, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)

2013-02-11

We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

A Comparison of Response Rate, Response Time, and Costs of Mail and Electronic Surveys.

Science.gov (United States)

Shannon, David M.; Bradshaw, Carol C.

2002-01-01

Compared response rates, response time, and costs of mail and electronic surveys using a sample of 377 college faculty members. Mail surveys yielded a higher response rate and a lower rate of undeliverable surveys, but response time was longer and costs were higher than for electronic surveys. (SLD)

Increased Frame Rate for Plane Wave Imaging Without Loss of Image Quality

DEFF Research Database (Denmark)

Jensen, Jonas; Stuart, Matthias Bo; Jensen, Jørgen Arendt

2015-01-01

Clinical applications of plane wave imaging necessitate the creation of high-quality images with the highest possible frame rate for improved blood flow tracking and anatomical imaging. However, linear array transducers create grating lobe artefacts, which degrade the image quality especially...... in the near field for λ-pitch transducers. Artefacts can only partly be suppressed by increasing the number of emissions, and this paper demonstrates how the frame rate can be increased without loss of image quality by using λ/2-pitch transducers. The number of emissions and steering angles are optimized...

THE MASS-LOSS RETURN FROM EVOLVED STARS TO THE LARGE MAGELLANIC CLOUD. VI. LUMINOSITIES AND MASS-LOSS RATES ON POPULATION SCALES

International Nuclear Information System (INIS)

Riebel, D.; Meixner, M.; Srinivasan, S.; Sargent, B.

2012-01-01

We present results from the first application of the Grid of Red Supergiant and Asymptotic Giant Branch ModelS (GRAMS) model grid to the entire evolved stellar population of the Large Magellanic Cloud (LMC). GRAMS is a pre-computed grid of 80,843 radiative transfer models of evolved stars and circumstellar dust shells composed of either silicate or carbonaceous dust. We fit GRAMS models to ∼30,000 asymptotic giant branch (AGB) and red supergiant (RSG) stars in the LMC, using 12 bands of photometry from the optical to the mid-infrared. Our published data set consists of thousands of evolved stars with individually determined evolutionary parameters such as luminosity and mass-loss rate. The GRAMS grid has a greater than 80% accuracy rate discriminating between oxygen- and carbon-rich chemistry. The global dust injection rate to the interstellar medium (ISM) of the LMC from RSGs and AGB stars is on the order of 2.1 × 10 –5 M ☉ yr –1 , equivalent to a total mass injection rate (including the gas) into the ISM of ∼6 × 10 –3 M ☉ yr –1 . Carbon stars inject two and a half times as much dust into the ISM as do O-rich AGB stars, but the same amount of mass. We determine a bolometric correction factor for C-rich AGB stars in the K s band as a function of J – K s color, BC K s = -0.40(J-K s ) 2 + 1.83(J-K s ) + 1.29. We determine several IR color proxies for the dust mass-loss rate (M-dot d ) from C-rich AGB stars, such as log M-dot d = (-18.90/((K s -[8.0])+3.37) - 5.93. We find that a larger fraction of AGB stars exhibiting the 'long-secondary period' phenomenon are more O-rich than stars dominated by radial pulsations, and AGB stars without detectable mass loss do not appear on either the first-overtone or fundamental-mode pulsation sequences.

Characteristic losses of electrons energy under reflection from leadsilicate glasses

International Nuclear Information System (INIS)

Gusarov, A.I.; Mashkov, V.A.; Pronin, V.P.; Tyutikov, A.M.

1986-01-01

The spectra of characteristic losses of energy (CLE) for the case of electron reflection from the surface of leadsilicate glasses of the composition xPbOx(1-x)SiO 2 , depending on molar concentration of lead oxide x, has been calculated for the first time. It is shown that the given model of glass energy structure permits to describe correctly general behaviour of CLE spectrum. However, the energy of plasma maximum measured experimentally remains approximately constant. The behaviour can be conditioned by ω 0 dependence on x[4], which has not been taken into account, and (or) by a slower change in ΔE, than it has been assumed. Further refining of theory and experiment is required to solve the problem

Effect of steam corrosion on core post strength loss: I. Low, chronic steam ingress rates

International Nuclear Information System (INIS)

Wichner, R.P.

1976-10-01

The purpose of the study was to assess the effect of chronic, low levels of steam ingress into the primary system of the HTGR on the corrosion, and consequent strength loss of the core support posts. The assessment proceeded through the following three steps: (1) The impurity composition in the primary system was estimated as a function of a range of steady ingress rates of from 0.001 to 1.0 g/sec, both by means of an analysis of the Dragon steam ingress experiment and a computer code, TIMOX, which treats the primary system as a well-mixed pot. (2) The core post burnoffs which result from 40-year exposures to these determined impurity atmospheres were then estimated using a corrosion rate expression derived from published ATJ-graphite corrosion rate data. Burnoffs were determined for both the core posts at the nominal and the maximum sustained temperature, estimated to be 90 0 C above nominal. (3) The final step involved assessment of the degree of strength loss resulting from the estimated burnoffs. An empirical equation was developed for this purpose which compares reasonably well with strength loss data for a number of different graphites and specimen geometries

A high-repetition rate LWFA for studies of laser propagation and electron generation

Science.gov (United States)

He, Zhaohan; Easter, James; Hou, Bixue; Krushelnick, Karl; Nees, John; Thomas, Alec

2010-11-01

Advances in ultrafast optics today have enabled laser systems to deliver ever shorter and more intense pulses. When focused, such laser pulses can easily exceed relativistic intensities where the wakefield created by the strong laser electric field can be used to accelerate electrons. Laser wakefield acceleration of electrons holds promise for future compact electron accelerators or drivers of other radiation sources in many scientific, medical and engineering applications. We present experimental studies of laser wakefield acceleration using the λ-cubed laser at the University of Michigan -- a table-top high-power laser system operating at 500 Hz repetition rate. The high repetition rate allows statistical studies of laser propagation and electron acceleration which are not accessible with typical sub-0.1 Hz repetition rate systems. In addition, we compare the experiments with particle-in-cell simulations using the code OSIRIS.

Electron energy-loss spectroscopy study of NiTi shape memory alloys

International Nuclear Information System (INIS)

Yang, Z.Q.; Schryvers, D.

2008-01-01

Electron energy loss spectroscopy (EELS) investigations were carried out on NiTi shape memory alloys. The composition of lens-shaped precipitates is determined to be Ni 4 Ti 3 by model-based EELS quantification, and the Ni-depleted zone in the B2 matrix surrounding the Ni 4 Ti 3 precipitates was quantified. The Young's modulus Y m of the B2 matrix with 51 at.% Ni and the Ni 4 Ti 3 precipitates was evaluated to be about 124 and 175 GPa, respectively. The intensity of the Ni L 3 edge for the precipitate is slightly higher than that for the B2 phase

Nutrient and Organic Carbon Losses, Enrichment Rate, and Cost of Water Erosion

Directory of Open Access Journals (Sweden)

Ildegardis Bertol

Full Text Available ABSTRACT Soil erosion from water causes loss of nutrients and organic carbon, enriches the environment outside the erosion site, and results in costs. The no-tillage system generates increased nutrient and C content in the topsoil and, although it controls erosion, it can produce a more enriched runoff than in the conventional tillage system. This study was conducted in a Humic Cambisol in natural rainfall from 1997 to 2012 to quantify the contents and total losses of nutrients and organic C in soil runoff, and to calculate the enrichment rates and the cost of these losses. The treatments evaluated were: a soil with a crop, consisting of conventional tillage with one plowing + two harrowings (CT, minimum tillage with one chisel plowing + one harrowing (MT, and no tillage (NT; and b bare soil: one plowing + two harrowings (BS. In CT, MT, and NT, black oat, soybean, vetch, corn, turnip, and black beans were cultivated. Over the 15 years, 15.5 Mg ha-1 of limestone, 525 kg ha-1 of N (urea, 1,302 kg ha-1 of P2O5 (triple superphosphate, and 1,075 kg ha-1 of K2O (potassium chloride were used in the soil. The P, K, Ca, Mg, and organic C contents in the soil were determined and also the P, K, Ca, and Mg sediments in the runoff water. From these contents, the total losses, the enrichment rates (ER, and financial losses were calculated. The NT increased the P, K, and organic C contents in the topsoil. The nutrients and organic C content in the runoff from NT was greater than from CT, showing that NT was not a fully conservationist practice for soil. The linear model y = a + bx fit the data within the level of significance (p≤0.01 when the values of P, K, and organic C in the sediments from erosion were related to those values in the soil surface layer. The nutrient and organic C contents were higher in the sediments from erosion than in the soil where the erosion originated, generating values of ER>1 for P, K, and organic C. The value of the total losses

New model for assessing dose and dose rate sensitivity of Gamma ray radiation loss in polarization maintaining optical fibers

International Nuclear Information System (INIS)

Zhang Hongchen; Liu Hai; Qiao Wenqiang; Xue Huijie; He Shiyu

2012-01-01

Highlights: ► Building a new phenomenological theory model to investigate the relation about the irradiation induced loss with irradiation dose and dose rate. ► The Gamma ray irradiation induced loss of the “Capsule” type and “Panda” type polarization maintaining optical fibers at 1310 nm wavelength are investigated. ► The anti irradiation performance of the “Panda” type polarization maintaining optical fiber is better than that of the “Capsule” type polarization maintaining optical fiber, the reason is that the stress region doped by GeO 2 . - Abstract: The Gamma ray irradiation induced loss of the “Capsule” type and “Panda” type polarization maintaining optical fibers at 1310 nm wavelength are investigated. A phenomenological theory model is introduced and the influence of irradiation dose and dose rate on the irradiation induced loss is discussed. The phenomenological theoretical results are consistent with the experimental results of the irradiation induced loss for the two types of polarization maintaining optical fibers. The anti irradiation performance of the “Panda” type polarization maintaining optical fiber is better than that of the “Capsule” type polarization maintaining optical fiber, the reason is that the stress region dope with GeO 2 . Meanwhile, both of the polarization maintaining optical fiber irradiation induced loss increase with increasing the irradiation dose. In the case of same dose, the high dose rate Gamma ray irradiation induced optical fiber losses are higher than that of the low dose rate.

Heart rate detection from an electronic weighing scale

International Nuclear Information System (INIS)

González-Landaeta, R; Casas, O; Pallàs-Areny, R

2008-01-01

We propose a novel technique for beat-to-beat heart rate detection based on the ballistocardiographic (BCG) force signal from a subject standing on a common electronic weighing scale. The detection relies on sensing force variations related to the blood acceleration in the aorta, works even if wearing footwear and does not require any sensors attached to the body because it uses the load cells in the scale. We have devised an approach to estimate the sensitivity and frequency response of three commercial weighing scales to assess their capability to detect the BCG force signal. Static sensitivities ranged from 490 nV V −1 N −1 to 1670 nV V −1 N −1 . The frequency response depended on the subject's mass but it was broad enough for heart rate estimation. We have designed an electronic pulse detection system based on off-the-shelf integrated circuits to sense heart-beat-related force variations of about 0.24 N. The signal-to-noise ratio of the main peaks of the force signal detected was higher than 30 dB. A Bland–Altman plot was used to compare the RR time intervals estimated from the ECG and BCG force signals for 17 volunteers. The error was ±21 ms, which makes the proposed technique suitable for short-term monitoring of the heart rate

Effectiveness of mobile electronic devices in weight loss among overweight and obese populations: a systematic review and meta-analysis.

Science.gov (United States)

Khokhar, Bushra; Jones, Jessica; Ronksley, Paul E; Armstrong, Marni J; Caird, Jeff; Rabi, Doreen

2014-01-01

Mobile electronic devices, such as mobile phones and PDAs, have emerged as potentially useful tools in the facilitation and maintenance of weight loss. While RCTs have demonstrated a positive impact of mobile interventions, the extent to which mobile electronic devices are more effective than usual care methods is still being debated. Electronic databases were systematically searched for RCTs evaluating the effectiveness of mobile electronic device interventions among overweight and obese adults. Weighted mean difference for change in body weight was the primary outcome. The search strategy yielded 559 citations and of the 108 potentially relevant studies, six met the criteria. A total of 632 participants were included in the six studies reporting a mean change in body weight. Using a random-effects model, the WMD for the effect of using mobile electronic devices on reduction in body weight was -1.09 kg (95% CI -2.12, -0.05). When stratified by the type of mobile electronic device used, it suggests that interventions using mobile phones were effective at achieving weight loss, WMD = -1.78 kg (95% CI -2.92, -0.63). This systematic review and meta-analysis suggests that mobile electronic devices have the potential to facilitate weight loss in overweight and obese populations, but further work is needed to understand if these interventions have sustained benefit and how we can make these mHealth tools most effective on a large scale. As the field of healthcare increasingly utilizes novel mobile technologies, the focus must not be on any one specific device but on the best possible use of these tools to measure and understand behavior. As mobile electronic devices continue to increase in popularity and the associated technology continues to advance, the potential for the use of mobile devices in global healthcare is enormous. More RCTs with larger sample sizes need to be conducted to look at the cost-effectiveness, technical and financial feasibility of adapting such m

On the influence of the electron dose rate on the HRTEM image contrast

Energy Technology Data Exchange (ETDEWEB)

Barthel, Juri, E-mail: ju.barthel@fz-juelich.de [RWTH Aachen University, Ahornstraße 55, 52074 Aachen (Germany); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Lentzen, Markus; Thust, Andreas [Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

2017-05-15

We investigate a possible dependence between the applied electron dose-rate and the magnitude of the resulting image contrast in HRTEM of inorganic crystalline objects. The present study is focussed on the question whether electron irradiation can induce excessively strong atom vibrations or displacements, which in turn could significantly reduce the resulting image contrast. For this purpose, high-resolution images of MgO, Ge, and Au samples were acquired with varying dose rates using a C{sub S}-corrected FEI Titan 80–300 microscope operated at 300 kV accelerating voltage. This investigation shows that the magnitude of the signal contrast is independent from the dose rates occurring in conventional HRTEM experiments and that excessively strong vibrations or displacements of bulk atoms are not induced by the applied electron irradiation. - Highlights: • No dependence between electron dose rate and HRTEM image contrast is found. • This finding is in full accordance with established solid-state physics theory. • Object-related causes for the previous Stobbs-factor phenomenon are ruled out.

The Dose Rate Dependence of the Yield of Trapped Electrons in Crystalline Ice

DEFF Research Database (Denmark)

Nilsson, Johan Daniel Göran; Pagsberg, Palle Bjørn

1980-01-01

in competition with other reactions and we propose a simple model where we assume that the mobile electrons can undergo bimolecular bulk reactions with protons and OH radicals. Rate constants of 3.0 × 1015 M−1 S−1 and 1.4 × 1014 M−1 S−1 for the two reactions were required in the model in order to account......The yield of localized excess electrons in crystalline H2O ice has been studied as a function of the dose rate at various temperatures in the range −10 to −40°C. The G value was found to decrease significantly with increasing dose rate. Thus it appears that the localization of electrons takes place...

Electrons in water radiolysis

International Nuclear Information System (INIS)

Laverne, J.A.; Pimblott, S.M.

2006-01-01

The hydrated electron is the main reducing species produced in the radiolysis of water. Many studies have examined its reactivity using pulsed radiolysis techniques and competition kinetics. Data bases list hundreds of rate coefficients for reaction of the hydrated electron with substances ranging from inorganic ions like nitrate to biopolymers like DNA. Although the chemistry of the hydrated electron is often examined, its mechanism of formation and variation in yield are considerable less known, especially under extreme conditions such as in high temperature water or with heavy ion radiolysis. This work will examine various aspects of the radiation chemistry of the hydrated electron beginning with the generation of secondary electrons in primary energy loss events during the passage of ionizing radiation to the radiolytic yields of the hydrated electron produced by different types of radiation. Ion radiation is a 'white light source.' Energy losses range from the minimum excitation energy of the medium up to the kinematic maximum determined by the collision parameters. However, certain energy loss events are more probable than others. The dipole oscillator strength distributions of media essentially give the probability of energy loss events in collisions with no momentum transfer. Dipole oscillator distributions have been constructed from experimental data for a wide variety of materials including all the phases of water. Calculations using cross sections based on dipole oscillator distributions show that the most probable energy loss event in water is only about 20 eV with an average value closer to 60 eV. The preponderance of energy loss events of less than 100 eV means that many low energy electrons are formed by the passage of a single ion. Low energy electrons have short mean free paths and they remain in the vicinity of the primary energy loss events. The spatial distribution of these low energy electrons defines the radial track structure of the incident

Long- and short-lived electrons with anomalously high collision rates in laser-ionized gases

International Nuclear Information System (INIS)

Kampfrath, Tobias; Perfetti, Luca; Tegeder, Petra; Wolf, Martin; Frischkorn, Christian; Gericke, Dirk O.

2007-01-01

Ultrashort broadband terahertz pulses are applied to probe the electron dynamics of gaseous Ar and O 2 following ionization by an intense femtosecond laser pulse. The conductivity in the plasma center is extracted by a modified Wentzel-Kramers-Brillouin approach. It exhibits a nearly perfect Drude-like spectral shape and yields the temporal evolution of the free-electron density and collision rate. While the electron density in the Ar plasma remains nearly constant during the first 200 ps after generation, it decays much faster in O 2 due to dissociative recombination which is only possible in molecular plasmas. Adding a small amount of the electron scavenger SF 6 to Ar reduces the electron lifetime in the plasma dramatically and allows us to determine the electron temperature to about 20 000 K. Furthermore, anomalously high, metal-like electron collision rates of up to 25 THz are found. Kinetic plasma theory substantially underestimates these rates pointing towards additional and more complex processes randomizing the total electronic momentum. Our results are relevant to both lightning control and generation of terahertz radiation by intense laser pulses in gases

Electron-impact excitation rate-coefficients and polarization of subsequent emission for Ar"+ ion

International Nuclear Information System (INIS)

Dipti; Srivastava, Rajesh

2016-01-01

Electron impact excitation in Ar"+ ions has been studied by using fully relativistic distorted wave theory. Calculations are performed to obtain the excitation cross-sections and rate-coefficients for the transitions from the ground state 3p"5 (J=3/2) to fine-structure levels of excited states 3p"44s, 3p"44p, 3p"45s, 3p"45p, 3p"43d and 3p"44d. Polarization of the radiation following the excitation has been calculated using the obtained magnetic sub-level cross-sections. Comparison of the present rate-coefficients is also done with the previously reported theoretical results for some unresolved fine structure transitions. - Highlights: • Fully relativistic distorted wave theory has been used to study the excitation of fine-structure states of Ar"+. • We have calculated electron-impact excitation cross-sections for the wide range of incident electron energies. • Electron impact excitation rate-coefficients are calculated as a function of electron temperature. • Polarization of photons emitted following the decay of the excited fine-structure states are also reported.

The electronic quenching rates of NO(A2Σ+, v'=0-2)

International Nuclear Information System (INIS)

Nee, J.B.; Juan, C.Y.; Hsu, J.Y.; Yang, J.C.; Chen, W.J.

2004-01-01

The electronic quenching rates of NO(A 2 Σ + , v ' =0-2) are measured for the gases He, Ar, Xe, N 2 , O 2 , CO 2 , N 2 O, and SF 6 . The variations of the fluorescence intensity were measured for the (0,0), (1,0), and (2,0) bands of the γ band system when the quencher gases were added. The quenching rates were determined by using the Stern-Volmer plots with the known radiative lifetimes of the excited states. The electronic quenching rate constants are fast for the group of gases of O 2 , CO 2 , N 2 O, and SF 6 , whose quenching rate constants are in the order of 10 -10 cm 3 /s. The quenching rate constants are slow for the group of gases including He, Ar, Xe, and N 2 whose rate constants are in the order of 10 -14 cm 3 /s. For the slow group, the quenching rate constants increase rapidly for v ' =2 compared with those of v ' =0 and 1. The charge transfer model and collision complex model are used to understand the quenching mechanism. For the fast group which mainly consists of gases with positive electron affinities, the charge transfer model adequately describes the mechanism. For the slow quenching group, a theoretical background is provided by consider the coupling of initial and final states in the complex potential surfaces

Electron-beam induced amorphization of stishovite: Silicon-coordination change observed using Si K-edge extended electron energy-loss fine structure

International Nuclear Information System (INIS)

Aken, P.A. van; Sharp, T.G.; Seifert, F.

1998-01-01

The analysis of the extended energy-loss fine structure (EXELFS) of the Si K-edge for sixfold-coordinated Si in synthetic stishovite and fourfold-coordinated Si in natural α-quartz is reported by using electron energy-loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM). The stishovite Si K-edge EXELFS spectra were measured as a time-dependent series to document irradiation-induced amorphization. The amorphization was also investigated through the change in Si K- and O K-edge energy-loss near edge structure (ELNES). For α-quartz, in contrast to stishovite, electron irradiation-induced vitrification, produced no detectable changes of the EXELFS. The Si K-edge EXELFS were analysed with the classical extended X-ray absorption fine structure (EXAFS) treatment and compared to ab initio curve-waved multiple-scattering (MS) calculations of EXAFS spectra for stishovite and α-quartz. Highly accurate information on the local atomic environment of the silicon atoms during the irradiation-induced amorphization of stishovite is obtained from the EXELFS structure parameters The mean Si-O bond distance R and mean Si coordination number N changes from R=0.1775 nm and N=6 for stishovite through a disordered intermediate state (R∼0.172 nm and N∼5) to R∼0.167 nm and N∼4.5 for a nearly amorphous state similar to α-quartz (R=0.1609 nm and N=4). During the amorphization process, the Debye-Waller factor (DWF) passes through a maximum value of σ N 2 ∼83.8pm 2 as it changes from σ st 2 =51.8pm 2 for sixfold to σ qu 2 =18.4pm 2 for fourfold coordination of Si. This increase in Debye-Waller factor indicates an increase in mean-square relative displacement (MSRD) between the central silicon atom and its oxygen neighbours. Using the EXELFS data for amorphization, a new method is developed to derive the relative amounts of Si coordinations in high-pressure minerals with mixed coordination. For the radiation-induced amorphization process of

The uniformity study of non-oxide thin film at device level using electron energy loss spectroscopy

Science.gov (United States)

Li, Zhi-Peng; Zheng, Yuankai; Li, Shaoping; Wang, Haifeng

2018-05-01

Electron energy loss spectroscopy (EELS) has been widely used as a chemical analysis technique to characterize materials chemical properties, such as element valence states, atoms/ions bonding environment. This study provides a new method to characterize physical properties (i.e., film uniformity, grain orientations) of non-oxide thin films in the magnetic device by using EELS microanalysis on scanning transmission electron microscope. This method is based on analyzing white line ratio of spectra and related extended energy loss fine structures so as to correlate it with thin film uniformity. This new approach can provide an effective and sensitive method to monitor/characterize thin film quality (i.e., uniformity) at atomic level for thin film development, which is especially useful for examining ultra-thin films (i.e., several nanometers) or embedded films in devices for industry applications. More importantly, this technique enables development of quantitative characterization of thin film uniformity and it would be a remarkably useful technique for examining various types of devices for industrial applications.

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

CERN Document Server

Kassel, Florian; Dabrowski, Anne; de Boer, Wim

2016-01-01

The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field,...

EELOSS: the program for calculation of electron energy loss data

International Nuclear Information System (INIS)

Tanaka, Shun-ichi

1980-10-01

A computer code EELOSS has been developed to obtain the electron energy loss data required for shielding and dosimetry of beta- and gamma-rays in nuclear plants. With this code, the following data are obtainable for any energy from 0.01 to 15 MeV in any medium (metal, insulator, gas, compound, or mixture) composed of any choice of 69 elements with atomic number 1 -- 94: a) Collision stopping power, b) Restricted collision stopping power, c) Radiative stopping power, and d) Bremsstrahlung production cross section. The availability of bremsstrahlung production cross section data obtained by the EELOSS code is demonstrated by the comparison of calculated gamma-ray spectrum with measured one in Pb layer, where electron-photon cascade is included implicitly. As a result, it is concluded that the uncertainty in the bremsstrahlung production cross sections is negligible in the practical shielding calculations of gamma rays of energy less than 15 MeV, since the bremsstrahlung production cross sections increase with the gamma-ray energy and the uncertainty for them decreases with increasing the gamma-ray energy. Furthermore, the accuracy of output data of the EELOSS code is evaluated in comparison with experimental data, and satisfactory agreements are observed concerning the stopping power. (J.P.N.)

Independent component analysis: A new possibility for analysing series of electron energy loss spectra

International Nuclear Information System (INIS)

Bonnet, Nogl; Nuzillard, Danielle

2005-01-01

A complementary approach is proposed for analysing series of electron energy-loss spectra that can be recorded with the spectrum-line technique, across an interface for instance. This approach, called blind source separation (BSS) or independent component analysis (ICA), complements two existing methods: the spatial difference approach and multivariate statistical analysis. The principle of the technique is presented and illustrations are given through one simulated example and one real example

Energy loss of pions and electrons of 1 to 6 GeV/c in drift chambers operated with Xe,CO2(15\\%)

CERN Document Server

Andronic, A; Braun-Munzinger, P; Bucher, D; Busch, O; Catanescu, V; Ciobanu, M; Daues, H W; Emschermann, D; Fateev, O V; Foka, Y; Garabatos, C; Gunji, T; Herrmann, N; Inuzuka, M; Kislov, E; Lindenstruth, V; Ludolphs, W; Mahmoud, T; Petracek, V; Petrovici, M; Rusanov, I R; Sandoval, A; Santo, R; Schicker, R; Simon, R S; Smykov, L P; Soltveit, H K; Stachel, J; Stelzer, H; Tsiledakis, G; Vulpescu, B; Wessels, J P; Windelband, B; Xu, C; Zaudtke, O; Zanevsky, Yu; Yurevich, V

2004-01-01

We present measurements of the energy loss of pions and electrons in drift chambers operated with a Xe,CO2(15%) mixture. The measurements are carried out for particle momenta from 1 to 6 GeV/c using prototype drift chambers for the ALICE TRD. Microscopic calculations are performed using input parameters calculated with GEANT3. These calculations reproduce well the measured average and most probable values for pions, but a higher Fermi plateau is required in order to reproduce our electron data. The widths of the measured distributions are smaller for data compared to the calculations. The electron/pion identification performance using the energy loss is also presented.

The numerical evaluation on non-radiative multiphonon transition rate from different electronic bases

International Nuclear Information System (INIS)

Zhu Bangfen.

1985-10-01

A numerical calculation on the non-radiative multiphonon transition probability based on the adiabatic approximation (AA) and the static approximation (SA) has been accomplished in a model of two electronic levels coupled to one phonon mode. The numerical results indicate that the spectra based on different approximations are generally different apart from those vibrational levels which are far below the classical crossing point. For large electron-phonon coupling constant, the calculated transition rates based on AA are more reliable; on the other hand, for small transition coupling the transition rates near or beyond the cross region are quite different for two approximations. In addition to the diagonal non-adiabatic potential, the mixing and splitting of the original static potential sheets are responsible for the deviation of the transition rates based on different approximations. The relationship between the transition matrix element and the vibrational level shift, the Huang-Rhys factor, the separation of the electronic levels and the electron-phonon coupling is analysed and discussed. (author)

Application of electron energy loss spectroscopy for single wall carbon nanotubes (review)

International Nuclear Information System (INIS)

Mittal, N.; Jain, S.; Mittal, J.

2015-01-01

Electron energy loss spectroscopy (EELS) is among the few techniques that are available for the characterization of modified single wall carbon nanotubes (SWCNTs) having nanometer dimensions (~1-3 nm). CNTs can be modified either by surface functionalization or coating, between bundles of nanotubes by doping, intercalation and fully or partially filling the central core. EELS is an exclusive technique for the identification, composition analysis, and crystallization studies of the chemicals and materials used for the modification of SWCNTs. The present paper serves as a compendium of research work on the application of EELS for the characterization of modified SWCNTs. (authors)

Vicinage effects in energy loss and electron emission during grazing scattering of heavy molecular ions from a solid surface

International Nuclear Information System (INIS)

Song Yuanhong; Wang Younian; Miskovic, Z.L.

2005-01-01

Vicinage effects in the energy loss and the electron emission spectra are studied in the presence of Coulomb explosion of swift, heavy molecular ions, during their grazing scattering from a solid surface. The dynamic response of the surface is treated by means of the dielectric theory within the specular reflection model using the plasmon pole approximation for the bulk dielectric function, whereas the angle-resolved energy spectra of the electrons emitted from the surface are obtained on the basis of the first-order, time-dependent perturbation theory. The evolution of the charge states of the constituent ions in the molecule during scattering is described by a nonequilibrium extension of the Brandt-Kitagawa model. The molecule scattering trajectories and the corresponding Coulomb explosion dynamics are evaluated for the cases of the internuclear axis being either aligned in the beam direction or randomly oriented in the directions parallel to the surface. Our calculations show that the vicinage effect in the energy loss is generally weaker for heavy molecules than for light molecules. In addition, there is clear evidence of the negative vicinage effect in both the energy loss and the energy spectra of the emitted electrons for molecular ions at lower speeds and with the axis aligned in the direction of motion

Estimating the month-specific effect of complementary food on weight loss occurrence rate in less than 2 years old children

Directory of Open Access Journals (Sweden)

Alireza Abadi

2012-09-01

Full Text Available Introduction: Weight loss in children is one of the health problems that could occur several times for achild; therefore it is categorized as a recurrent event. In this study, we investigated the weight loss riskfactors firstly by using proportional rates model and then by applying time-dependent coefficient ratesmodel.Materials and Methods: In this study, the information of 1673 babies who were born in 2006 or 2007and were visited for monthly check ups at Tehran east health centers during their first two years of life wereincluded in the analysis. We first fitted the standard proportional rates model to this data with the purposeof determining weigh loss major risk factors. After adjusting these factors, the month-specific effect ofcomplementary foods on weight loss occurrence rate was explored using time-varying coefficient ratesmodel.Results: Our findings showed that the risk of weight loss gets heightened as with the increase in theintake of complementary foods. This negative effect is likely to be the most between 9 and 11 months ofage and then tends to weaken as the baby grows older. The results of Wald-type statistic showed that theimpact of complementary food on the occurrence of weight loss is significantly different with respect to thechild ‘age (P<0.001.Conclusion: Considering the variability of the effect of complementary food on the occurrence of weightloss, time-varying coefficient rates model can give more appropriate estimation of this effect thanproportional rates model.

High-rate deposition of SI absorber layers by electron beam evaporation and first electron beam crystallization tests

OpenAIRE

Saager, Stefan; Ben Yaala, Marwa; Heinß, Jens-Peter; Temmler, Dietmar; Pfefferling, Bert; Metzner, Christoph

2014-01-01

In earlier electron beam physical vapor deposition tests (EB-PVD), using a conventional copper crucible (A), high Si deposition rates at relatively high EB power together with a contamination level of 1016 cm-3 are demonstrated. To improve the rate vs. EB power relation as well as the Si layer purity, two alternative high rate EBPVD methods are investigated and reported here - a contact-less crucible setup (B) and a crucible-free setup (C).In these experiments comparable deposition rates of ~...

Establishment of the relationship between 137Cs loss and soil erosion rates

International Nuclear Information System (INIS)

Phan Son Hai

2003-01-01

The key stages involved in the use of 137 Cs in soil erosion assessment is presented. The method have been successfully applied in pilot scale. These main stages can be summarized as follows: 1/ selection of reference sites next to the study site and establishment of a reference fallout inventory for the study site; 2/measurement of the current spatial distribution of 137 Cs inventory; 3/ evaluation of the pattern of 137 Cs redistribution at the study site; 4/ development of a calibration relationship between 137 CS loss and gain and rate of soil erosion; 5/ estimation of soil redistribution rates using the calibration relationship. (PSH)

Gamow-Teller strength distributions and electron capture rates for 55Co and 56Ni

International Nuclear Information System (INIS)

Nabi, Jameel-Un; Rahman, Muneeb-Ur

2005-01-01

The Gamow-Teller strength (GT) distributions and electron capture rates on 55 Co and 56 Ni have been calculated using the proton-neutron quasiparticle random phase approximation theory. We calculate these weak interaction mediated rates over a wide temperature (0.01x10 9 -30x10 9 K) and density (10-10 11 gcm -3 ) domain. Electron capture process is one of the essential ingredients involved in the complex dynamics of supernova explosion. Our calculations of electron capture rates show differences with the reported shell model diagonalization approach calculations and are comparatively enhanced at presupernova temperatures. We note that the GT strength is fragmented over many final states

Design and construction of a high-stability, low-noise power supply for use with high-resolution electron energy loss spectrometers

International Nuclear Information System (INIS)

Katz, J.E.; Davies, P.W.; Crowell, J.E.; Somorjai, G.A.

1982-01-01

The design and construction of a high-stability, low-noise power supply which provides potentials for the lens and analyzer elements of a 127 0 Ehrhardt-type high-resolution electron energy loss spectrometer (HREELS) is described. The supply incorporates a filament emission-control circuit and facilities for measuring electron beam current at each spectrometer element, thus facilitating optimal tuning of the spectrometer. Spectra obtained using this supply are shown to have a four-fold improvement in signal-to-noise ratio and a higher resolution of the vibrational loss features when compared with spectra taken using a previously existing supply based on passive potential divider networks

Photometric and polarimetric variability and mass-loss rate of the massive binary Wolf-Rayet star HDE 311884 (WN6 + 05: V)

International Nuclear Information System (INIS)

Moffat, A.F.J.; Drissen, L.; Robert, C.; Lamontagne, R.; Coziol, R.

1990-01-01

Photometric and polarimetric monitoring of the Wolf-Rayet (W-R) + O-type binary system HDE 311884 = WR 47 over many orbital cycles shows the clear effects of phase-dependent electron scattering of O-star light as the orbiting O companion shines through varying column density of W-R stellar wind material. In contrast to this wind-type eclipse, the stars themselves do not quite eclipse. Both photometry and polarimetry give a consistent estimate of the mass-loss rate of the W-R component: at about 0.00003 solar mass/yr. The orbital inclination, i = 70 deg, along with the previously published velocity orbit, yields high masses: M(WN6) = 48 solar masses and M(O5:V) = 57 solar masses. 33 refs

Sequential Proton Loss Electron Transfer in Deactivation of Iron(IV) Binding Protein by Tyrosine Based Food Components

DEFF Research Database (Denmark)

Tang, Ning; Skibsted, Leif Horsfelt

2017-01-01

The iron(IV) binding protein ferrylmyoglobin, MbFe(IV)=O, was found to be reduced by tyrosine based food components in aqueous solution through a sequential proton loss electron transfer reaction mechanism without binding to the protein as confirmed by isothermal titration calorimetry. Dopamine a...

Energetic electron propagation in the decay phase of non-thermal flare emission

Energy Technology Data Exchange (ETDEWEB)

Huang, Jing; Yan, Yihua [Key Laboratory of Solar Activities, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Tsap, Yuri T., E-mail: huangj@nao.cas.cn [Crimean Astrophysical Observatory of Kyiv National Taras Shevchenko University, 98409 Crimea, Nauchny (Ukraine)

2014-06-01

On the basis of the trap-plus-precipitation model, the peculiarities of non-thermal emission in the decay phase of solar flares have been considered. The calculation formulas for the escape rate of trapped electrons into the loss cone in terms of time profiles of hard X-ray (HXR) and microwave (MW) emission have been obtained. It has been found that the evolution of the spectral indices of non-thermal emission depend on the regimes of the pitch angle diffusion of trapped particles into the loss cone. The properties of non-thermal electrons related to the HXR and MW emission of the solar flare on 2004 November 3 are studied with Nobeyama Radioheliograph, Nobeyama Radio Polarimeters, RHESSI, and Geostationary Operational Environmental Satellite observations. The spectral indices of non-thermal electrons related to MW and HXR emission remained constant or decreased, while the MW escape rate as distinguished from that of the HXRs increased. This may be associated with different diffusion regimes of trapped electrons into the loss cone. New arguments in favor of an important role of the superstrong diffusion for high-energy electrons in flare coronal loops have been obtained.

Hot Electron Photoemission from Plasmonic Nanostructures: The Role of Surface Photoemission and Transition Absorption

DEFF Research Database (Denmark)

Babicheva, Viktoriia; Zhukovsky, Sergei; Ikhsanov, Renat Sh

2015-01-01

We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of "transition absorption", i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate photoemis......We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of "transition absorption", i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate...... photoemission rate and transition absorption for nanoparticles surrounded by various media with a broad range of permittivities and show that photoemission rate and transition absorption follow the same dependence on the permittivity. Thus, we conclude that transition absorption is responsible...

Radiobiological response to ultra-short pulsed megavoltage electron beams of ultra-high pulse dose rate.

Science.gov (United States)

Beyreuther, Elke; Karsch, Leonhard; Laschinsky, Lydia; Leßmann, Elisabeth; Naumburger, Doreen; Oppelt, Melanie; Richter, Christian; Schürer, Michael; Woithe, Julia; Pawelke, Jörg

2015-08-01

In line with the long-term aim of establishing the laser-based particle acceleration for future medical application, the radiobiological consequences of the typical ultra-short pulses and ultra-high pulse dose rate can be investigated with electron delivery. The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) was used to mimic the quasi-continuous electron beam of a clinical linear accelerator (LINAC) for comparison with electron pulses at the ultra-high pulse dose rate of 10(10) Gy min(-1) either at the low frequency of a laser accelerator or at 13 MHz avoiding effects of prolonged dose delivery. The impact of pulse structure was analyzed by clonogenic survival assay and by the number of residual DNA double-strand breaks remaining 24 h after irradiation of two human squamous cell carcinoma lines of differing radiosensitivity. The radiation response of both cell lines was found to be independent from electron pulse structure for the two endpoints under investigation. The results reveal, that ultra-high pulse dose rates of 10(10) Gy min(-1) and the low repetition rate of laser accelerated electrons have no statistically significant influence (within the 95% confidence intervals) on the radiobiological effectiveness of megavoltage electrons.

Plasma Heating and Losses in Toroidal Multipole Fields

International Nuclear Information System (INIS)

Armentrout, C. J.; Barter, J. D.; Breun, R. A.; Cavallo, A. J.; Drake, J. R.; Etzweiler,; Greenwood, J. R.

1974-01-01

The heating and loss of plasmas have been studied in three pulsed, toroidal multipole devices: a large levitated octupole, a small supported octupole and a very small supported quadrupole. Plasmas are produced by gun injection and heated by electron and ion cyclotron resonance heating and ohmic heating. Electron cyclotron heating rates have been measured over a wide range of parameters, and the results are in quantitative agreement with stochastic heating theory. Electron cyclotron resonance heating produces ions with energies larger than predicted by theory. With the addition of a toroidal field, ohmic heating gives densities as high as 10 13 cm -3 in the toroidal quadrupole and 10 12 cm -3 in the small octupole. Plasma losses for n=5 x 10 9 cm -3 plasmas are inferred from Langmuir probe and Fabry-Perot interferometer measurements, and measured with special striped collectors on the wall and rings. The loss to a levitated ring is measured using a modulated light beam telemeter. The confinement is better than Bohm but considerably worse than classical. Low frequency convective cells which are fixed in space are observed. These cells around the ring are diminished when a weak toroidal field is added, and loss collectors show a vastly reduced flux to the rings. Analysis of the spatial density profile shows features of B-independent diffusion. The confinement is sensitive to some kinds of dc field errors, but surprisingly insensitive to perturbations of the ac confining field

Reliability prediction system based on the failure rate model for electronic components

International Nuclear Information System (INIS)

Lee, Seung Woo; Lee, Hwa Ki

2008-01-01

Although many methodologies for predicting the reliability of electronic components have been developed, their reliability might be subjective according to a particular set of circumstances, and therefore it is not easy to quantify their reliability. Among the reliability prediction methods are the statistical analysis based method, the similarity analysis method based on an external failure rate database, and the method based on the physics-of-failure model. In this study, we developed a system by which the reliability of electronic components can be predicted by creating a system for the statistical analysis method of predicting reliability most easily. The failure rate models that were applied are MILHDBK- 217F N2, PRISM, and Telcordia (Bellcore), and these were compared with the general purpose system in order to validate the effectiveness of the developed system. Being able to predict the reliability of electronic components from the stage of design, the system that we have developed is expected to contribute to enhancing the reliability of electronic components

Precise method for correcting count-rate losses in scintillation cameras

International Nuclear Information System (INIS)

Madsen, M.T.; Nickles, R.J.

1986-01-01

Quantitative studies performed with scintillation detectors often require corrections for lost data because of the finite resolving time of the detector. Methods that monitor losses by means of a reference source or pulser have unacceptably large statistical fluctuations associated with their correction factors. Analytic methods that model the detector as a paralyzable system require an accurate estimate of the system resolving time. Because the apparent resolving time depends on many variables, including the window setting, source distribution, and the amount of scattering material, significant errors can be introduced by relying on a resolving time obtained from phantom measurements. These problems can be overcome by curve-fitting the data from a reference source to a paralyzable model in which the true total count rate in the selected window is estimated from the observed total rate. The resolving time becomes a free parameter in this method which is optimized to provide the best fit to the observed reference data. The fitted curve has the inherent accuracy of the reference source method with the precision associated with the observed total image count rate. Correction factors can be simply calculated from the ratio of the true reference source rate and the fitted curve. As a result, the statistical uncertainty of the data corrected by this method is not significantly increased

Electron Beam Return-Current Losses in Solar Flares: Initial Comparison of Analytical and Numerical Results

Science.gov (United States)

Holman, Gordon

2010-01-01

Accelerated electrons play an important role in the energetics of solar flares. Understanding the process or processes that accelerate these electrons to high, nonthermal energies also depends on understanding the evolution of these electrons between the acceleration region and the region where they are observed through their hard X-ray or radio emission. Energy losses in the co-spatial electric field that drives the current-neutralizing return current can flatten the electron distribution toward low energies. This in turn flattens the corresponding bremsstrahlung hard X-ray spectrum toward low energies. The lost electron beam energy also enhances heating in the coronal part of the flare loop. Extending earlier work by Knight & Sturrock (1977), Emslie (1980), Diakonov & Somov (1988), and Litvinenko & Somov (1991), I have derived analytical and semi-analytical results for the nonthermal electron distribution function and the self-consistent electric field strength in the presence of a steady-state return-current. I review these results, presented previously at the 2009 SPD Meeting in Boulder, CO, and compare them and computed X-ray spectra with numerical results obtained by Zharkova & Gordovskii (2005, 2006). The phYSical significance of similarities and differences in the results will be emphasized. This work is supported by NASA's Heliophysics Guest Investigator Program and the RHESSI Project.

Development of a high repetition rate laser-plasma accelerator for ultra-fast electron diffraction experiments

International Nuclear Information System (INIS)

Beaurepaire, B.

2009-01-01

Electronic microscopy and electron diffraction allowed the understanding of the organization of atoms in matter. Using a temporally short source, one can measure atomic displacements or modifications of the electronic distribution in matter. To date, the best temporal resolution for time resolved diffraction experiments is of the order of a hundred femto-seconds (fs). Laser accelerators are good candidates to reach the femtosecond temporal resolution in electron diffraction experiments. Such accelerators used to work at a low repetition rate, so that it was necessary to develop a new one operating at a high repetition rate in order to accumulate a large amount of data. In this thesis, a laser-plasma accelerator operating at the kHz repetition rate was developed and built. This source generates electron bunches at 100 keV from 3 mJ and 25 fs laser pulses. The physics of the acceleration has been studied, and the effect of the laser wavefront on the electron transverse distribution has been demonstrated. (author)

HPLC detection of loss rate and cell migration of HUVECs in a proanthocyanidin cross-linked recombinant human collagen-peptide (RHC)–chitosan scaffold

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jing; Deng, Aipeng [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Yang [Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Gao, Lihu; Xu, Na; Liu, Xin; Hu, Lunxiang; Chen, Junhua [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Shulin, E-mail: yshulin@njust.edu.cn [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

2015-11-01

Porous scaffolds with appropriate pore structure, biocompatibility, mechanical property and processability play an important role in tissue engineering. In this paper, we fabricated a recombinant human collagen-peptide (RHC)–chitosan scaffold cross-linked by premixing 30% proanthocyanidin (PA) in one-step freeze-drying. To remove the residual acetic acid, optimized 0.2 M phosphate buffer of pH 6.24 with 30% ethanol (PBSE) was selected to neutralize the lyophilized scaffold followed by three times deionized water rinse. Ninhydrin assay was used to characterize the components loss during the fabrication process. To detect the exact RHC loss under optimized neutralization condition, high performance liquid chromatography (HPLC) equipped size exclusion chromatography column was used and the total RHC loss rate through PBSE rinse was 19.5 ± 5.08%. Fourier transform infrared spectroscopy (FT-IR) indicated hydrogen bonding among RHC, chitosan and PA, it also presented a probative but not strong hydrophobic interaction between phenyl rings of polyphenols and pyrrolidine rings of proline in RHC. Further, human umbilical vein endothelial cell (HUVEC) viability analyzed by a scanning electron microscope (SEM) and acridine orange/ethidium bromide (AO/EB) fluorescence staining exhibited that this scaffold could not only promote cell proliferation on scaffold surface but also permit cells migration into the scaffold. qRT-PCR exhibited that the optimized scaffold could stimulate angiogenesis associated genes VEGF and CD31 expression. These characterizations indicated that this scaffold can be considered as an ideal candidate for tissue engineering. - Highlights: • PA cross-linked recombinant human collagen–chitosan scaffold. • Fabrication in one-step lyophilization with neutralization. • HPLC detection of RHC loss rate • HUVEC proliferation and migration in scaffold • Angiogenesis associated gene expressions were increased in scaffold cell culturing.

A Note on Forecasting the Rate of Change of the Price of Oil: Asymmetric Loss and Forecast Rationality

Directory of Open Access Journals (Sweden)

Christian Pierdzioch

2013-03-01

Full Text Available We study whether forecasts of the rate of change of the price of oil are rational. To this end, we consider a model that allows the shape of forecasters’ loss function to be studied. The shape of forecasters’ loss function may be consistent with a symmetric or an asymmetric loss function. We find that an asymmetric loss function often (but not always makes forecasts look rational, and we also report that forecast rationality may have changed over time.

Comparison of initial damage rates using neutron and electron irradiations

International Nuclear Information System (INIS)

Goldstone, J.A.R.

1978-08-01

The purpose of this experiment was twofold: (1) The number of interstitials that pin dislocations was studied as a function of neutron energy. (2) By comparison with electron irradiations on the sample, a correlation between the predicted and measured numbers of defects was found. All irradiations were performed on the same high purity copper sample. The sample was machined in the form of a cantilever beam with a flexural resonant frequency of 770 Hz. Changes in Young's modulus at constant strain amplitude were monitored continuously through changes in the resonant frequency of the sample. These changes in the modulus can be related to the number of pinning points added to dislocation lines, which are in turn related to the number of free interstitials produced. Neutron energy dependence experiments were done from 2 to 24 MeV on the copper sample and at 14 MeV on a gold sample. By equating pinning rates from electron and neutron irradiations and using the free interstitial production rate obtained from electron irradiations, an estimate of the free interstitial production cross section for neutrons of 2 to 24 MeV was made

Energy loss and charge exchange processes of high energy heavy ions channeled in crystals

International Nuclear Information System (INIS)

Poizat, J.C.; Andriamonje, S.; Anne, R.; Faria, N.V.d.C.; Chevallier, M.; Cohen, C.; Dural, J.; Farizon-Mazuy, B.; Gaillard, M.J.; Genre, R.; Hage-Ali, M.; Kirsch, R.; L'hoir, A.; Mory, J.; Moulin, J.; Quere, Y.; Remillieux, J.; Schmaus, D.; Toulemonde, M.

1990-01-01

The interaction of moving ions with single crystals is very sensitive to the orientation of the incident beam with respect to the crystalline directions of the target. Our experiments show that high energy heavy ion channeling deeply modifies their slowing down and charge exchange processes. This is due to the fact that channeled ions interact only with outershell target electrons, which means that the electron density they experience is very low and that the binding energy, and then the momentum distribution of these electrons, are quite different from the corresponding average values associated to random incidence. The two experimental studies presented here show the reduction of the energy loss rate for fast channeled heavy ions and illustrate the two aspects of channeling effects on charge exchange, the reduction of electron loss on one hand, and of electron capture on the other hand

Growth rate of dislocation loop in Fe-Ni-Cr alloy under Kr+ ion and electron irradiation

International Nuclear Information System (INIS)

Kimoto, T.; Allen, C.W.; Rehn, L.E.

1991-10-01

In order to examine the effect of irradiating particle species on the growth rate of radiation-induced dislocation loops, a solution-annealed Fe-25Ni-15Cr-0.02C alloy was irradiated at 723 K first by 1.5 MeV Kr + ions for 2520 sec, then by 1.5 MeV Kr + ions and 1.0 MeV electrons simultaneously for 780 sec, and finally by 1.0 MeV electrons for 780 sec with the HVEM-Tandem Facility in Argonne National Laboratory. The calculated damage rate by 1.5 MeV Kr + ions was 5.8 x 10 -4 dpa/s, and that by 1.0 MeV electrons was 1 x 10 -4 dpa/s. The growth rate of a dislocation loop located at the center of the specimen was 7 x 10 -3 nm/s for the Kr + ion irradiation, 4 x 10 -2 nm/s for the simultaneous Kr + and electron irradiation, and (2--3) x 10 -2 nm/s for the electron irradiation. This implies that the electron irradiation is about 19 times more effective in the growth of radiation-induced dislocation loops than the Kr + ion irradiation. The dislocation loop growth rate under the simultaneous Kr + and electron irradiation is higher than the sum of the growth rates under the individual Kr + and electron irradiations. 5 refs., 4 figs

Coupled force-balance and particle-occupation rate equations for high-field electron transport

International Nuclear Information System (INIS)

Lei, X. L.

2008-01-01

It is pointed out that in the framework of balance-equation approach, the coupled force-balance and particle-occupation rate equations can be used as a complete set of equations to determine the high-field transport of semiconductors in both strong and weak electron-electron interaction limits. We call to attention that the occupation rate equation conserves the total particle number and maintains the energy balance of the relative electron system, and there is no need to introduce any other term in it. The addition of an energy-drift term in the particle-occupation rate equation [Phys. Rev. B 71, 195205 (2005)] is physically inadequate for the violation of the total particle-number conservation and the energy balance. It may lead to a substantial unphysical increase of the total particle number by the application of a dc electric field

Influence of radiation defects on electrical losses in silicon diodes irradiated with electrons

International Nuclear Information System (INIS)

Poklonski, N. A.; Gorbachuk, N. I.; Shpakovski, S. V.; Lastovskii, S. B.; Wieck, A.

2010-01-01

Silicon diodes with a p + -n junction irradiated with 3.5-MeV electrons (the fluence ranged from 10 15 to 4 x 10 16 cm -2 ) have been studied. It is established that the dependence of the tangent of the angle of electrical losses tanδ on the frequency f of alternating current in the range f = 10 2 -10 6 Hz is a nonmonotonic function with two extrema: a minimum and a maximum. Transformation of the dependences tanδ(f) as the electron fluence and annealing temperature are increased is caused by a variation in the resistance of n-Si (the base region of the diodes) as a result of accumulation (as the fluence is increased) or disappearance and reconfiguration (in the course of annealing) of radiation defects. The role of time lag of the defect recharging in the formation of tanδ(f) is insignificant.

Defect production and subsequent effects induced by electronic energy loss of swift heavy ion

International Nuclear Information System (INIS)

Hou Mingdong; Liu Jie; Sun Youmei; Yin Jingmin; Yao Huijun; Duan Jinglai; Mo Dan; Zhang Ling; Chen Yanfeng; Chinese Academy of Sciences, Beijing

2008-01-01

Swift heavy ion in matter is one of forfront fields of nuclear physics in the world. A series of new phenomena were discovered in recent years. The history and sta- tus on the development of this field were reviewed. Electronic energy loss effects induced by swift heavy ion irradiation, such as defect production and evolution, ion latent track formation, phase transformation and anisotropy plastic deformation were introduced emphatically. A trend of future investigation was explored. (authors)

Apparent rates of production and loss of dissolved gaseous mercury (DGM) in a southern reservoir lake (Tennessee, USA)

International Nuclear Information System (INIS)

Zhang Hong; Dill, Christopher

2008-01-01

Apparent rates of dissolved gaseous mercury (DGM) concentration changes in a southern reservoir lake (Cane Creek Lake, Cookeville, Tennessee) were investigated using the DGM data collected in a 12-month study from June 2003 to May 2004. The monthly mean apparent DGM production rates rose from January (3.2 pg L -1 /h), peaked in the summer months (June-August: 8.9, 8.0, 8.6 pg L -1 /h), and fell to the lowest in December (1.6 pg L -1 /h); this trend followed the monthly insolation march for both global solar radiation and UVA radiation. The monthly apparent DGM loss rates failed to show the similar trend with no consistent pattern recognizable. The spring and summer had higher seasonal mean apparent DGM production rates than the fall and winter (6.8, 9.0, 3.9, 5.0 pg L -1 /h, respectively), and the seasonal trend also appeared to closely follow the solar radiation variation. The seasonal apparent DGM loss featured similar rate values for the four seasons (5.5, 4.3, 3.3, and 3.9 pg L -1 /h for spring, summer, fall, and winter, respectively). Correlation was found of the seasonal mean apparent DGM production rate with the seasonal mean morning solar radiation (r = 0.9084, p < 0.01) and with the seasonal mean morning UVA radiation (r = 0.9582, p < 0.01). No significant correlation was found between the seasonal apparent DGM loss rate and the corresponding afternoon solar radiation (r = 0.5686 for global radiation and 0.6098 for UVA radiation). These results suggest that DGM production in the lake engaged certain photochemical processes, either primary or secondary, but the DGM loss was probably driven by some dark processes

Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy.

Science.gov (United States)

Liu, Qianlang; March, Katia; Crozier, Peter A

2017-07-01

Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO 2 anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO 2 showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1eV above the MgO valence band. At the surfaces of TiO 2 nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. Copyright © 2016 Elsevier B.V. All rights reserved.

Energy-loss return gate via liquid dielectric polarization.

Science.gov (United States)

Kim, Taehun; Yong, Hyungseok; Kim, Banseok; Kim, Dongseob; Choi, Dukhyun; Park, Yong Tae; Lee, Sangmin

2018-04-12

There has been much research on renewable energy-harvesting techniques. However, owing to increasing energy demands, significant energy-related issues remain to be solved. Efforts aimed at reducing the amount of energy loss in electric/electronic systems are essential for reducing energy consumption and protecting the environment. Here, we design an energy-loss return gate system that reduces energy loss from electric/electronic systems by utilizing the polarization of liquid dielectrics. The use of a liquid dielectric material in the energy-loss return gate generates electrostatic potential energy while reducing the dielectric loss of the electric/electronic system. Hence, an energy-loss return gate can make breakthrough impacts possible by amplifying energy-harvesting efficiency, lowering the power consumption of electronics, and storing the returned energy. Our study indicates the potential for enhancing energy-harvesting technologies for electric/electronics systems, while increasing the widespread development of these systems.

Heart rate recovery improves after weight loss in overweight and obese women with polycystic ovary syndrome.

Science.gov (United States)

Thomson, Rebecca L; Buckley, Jonathan D; Noakes, Manny; Clifton, Peter M; Norman, Robert J; Brinkworth, Grant D

2010-03-01

To determine the effects of weight loss on heart rate recovery (HRR) in overweight women with polycystic ovary syndrome (PCOS). A 10-week prospective clinical intervention. Clinical research unit. Fifty-seven overweight and obese women with PCOS (age: 29.8 +/- 0.8 years; body mass index [BMI] 36.2 +/- 0.7 kg/m(2)). A dietary plan of 5-6 MJ/day ( approximately 30% energy restricted). Heart rate recovery (defined as the reduction in heart rate after 1 minute from peak heart rate after a graded treadmill test to exhaustion), weight, waist circumference, blood pressure, glucose, insulin, homeostasis model assessment of insulin resistance, and sex steroids before and after the intervention. The mean percentage of weight loss was (-6.7 +/- 0.4%). There were significant reductions in waist circumference (-6.9 +/- 0.6 cm), blood pressure (-4.9/-2.5 +/- 1.2/1.2 mm Hg), fasting insulin (-3.4 +/- 0.7 mU/L), fasting glucose (-0.17 +/- 0.05 mmol/L), homeostasis model assessment of insulin resistance (-0.43 +/- 0.09), T (-0.38 +/- 0.07 nmol/L), free androgen index (-2.86 +/- 0.58), and an increase in sex hormone-binding globulin [SHBG] (5.86 +/- 1.12 nmol/L). The HRR improved from 30.9 +/- 1.1 to 38.0 +/- 1.1 beats/min and that was related to the reduction in body weight (r = -0.34) and waist circumference (r = -0.27). Weight loss in overweight and obese women with PCOS is associated with improvements in HRR, which suggests improved autonomic function. This highlights the importance of weight loss to reduce the cardiovascular disease risk in these women. Crown Copyright 2010. Published by Elsevier Inc. All rights reserved.

Electron energy-loss spectrometry at the frontier of spatial and energy resolution

International Nuclear Information System (INIS)

Hofer, F.; Grogger, W.; Kothleitner, G.

2004-01-01

Full text: Electron energy-loss spectroscopy (EELS) in the transmission electron microscope (TEM) is now used routinely as a means of measuring chemical and structural properties of very small regions of a thin specimen. The power of this technique depends significantly on two parameters: its spatial resolution and the energy resolution available in the spectrum and in the energy-filtered TEM (EFTEM) image. The cold field emission source and the Schottky emitter have made an energy resolution below 1 eV possible and it is now feasible to obtain data with a spatial resolution close to atomic dimensions, given the right instrumentation and specimen. EFTEM allows to record elemental maps at sub-nanometre resolution, being mainly limited by chromatic and spherical aberration of the objective lens and by delocalization of inelastic scattering. Recently the possibility of correcting spherical and even chromatic aberrations of electron lenses has become a practical reality thus improving the point resolution of the TEM to below 0.1 nm. The other limiting factor for EFTEM resolution is delocalization. However, recent measurements show that resolution values in the range of 1 nm and below can be achieved, even for energy-losses of only a few eV. In terms of energy-resolution, EELS and EFTEM compare less favourably with other spectroscopies. For common TEMs, the overall energy-resolution is mainly determined by the energy width of the electron source, typically between 0.5 and 1.5 eV. For comparison, synchrotron x-ray sources and beam line spectrometers, provide a resolution well below 0.1 eV for absorption spectroscopy. During the early sixties, the energy spread of an electron beam could be reduced by incorporating an energy-filter into the illumination system, but the system lacked spatial resolution. Later developments combined high energy resolution in the range of 0.1 eV with improved spatial resolution. Recently, FEI introduced a new high resolution EELS system based

Chapter 6 Quantum Mechanical Methods for Loss-Excitation and Loss-Ionization in Fast Ion-Atom Collisions

Science.gov (United States)

Belkic, Dzevad

Inelastic collisions between bare nuclei and hydrogen-like atomic systems are characterized by three main channels: electron capture, excitation, and ionization. Capture dominates at lower energies, whereas excitation and ionization prevail at higher impact energies. At intermediate energies and in the region of resonant scattering near the Massey peak, all three channels become competitive. For dressed or clothed nuclei possessing electrons, such as hydrogen-like ions, several additional channels open up, including electron loss (projectile ionization or stripping). The most important aspect of electron loss is the competition between one- and two-electron processes. Here, in a typical one-electron process, the projectile emits an electron, whereas the target final and initial states are the same. A prototype of double-electron transitions in loss processes is projectile ionization accompanied with an alteration of the target state. In such a two-electron process, the target could be excited or ionized. The relative importance of these loss channels with single- and double-electron transitions involving collisions of dressed projectiles with atomic systems is also strongly dependent on the value of the impact energy. Moreover, impact energies determine which theoretical method is likely to be more appropriate to use for predictions of cross sections. At low energies, an expansion of total scattering wave functions in terms of molecular orbitals is adequate. This is because the projectile spends considerable time in the vicinity of the target, and as a result, a compound system comprised of the projectile and the target can be formed in a metastable molecular state which is prone to decay. At high energies, a perturbation series expansion is more appropriate in terms of powers of interaction potentials. In the intermediate energy region, atomic orbitals are often used with success while expanding the total scattering wave functions. The present work is focused on

Miniaturized Stretchable and High-Rate Linear Supercapacitors

OpenAIRE

Zhu, Wenjun; Zhang, Yang; Zhou, Xiaoshuang; Xu, Jiang; Liu, Zunfeng; Yuan, Ningyi; Ding, Jianning

2017-01-01

Linear stretchable supercapacitors have attracted much attention because they are well suited to applications in the rapidly expanding field of wearable electronics. However, poor conductivity of the electrode material, which limits the transfer of electrons in the axial direction of the linear supercapacitors, leads to a serious loss of capacity at high rates. To solve this problem, we use gold nanoparticles to decorate aligned multiwall carbon nanotube to fabricate stretchable linear electr...

Gas exchange patterns and water loss rates in the Table Mountain cockroach, Aptera fusca (Blattodea: Blaberidae).

Science.gov (United States)

Groenewald, Berlizé; Bazelet, Corinna S; Potter, C Paige; Terblanche, John S

2013-10-15

The importance of metabolic rate and/or spiracle modulation for saving respiratory water is contentious. One major explanation for gas exchange pattern variation in terrestrial insects is to effect a respiratory water loss (RWL) saving. To test this, we measured the rates of CO2 and H2O release ( and , respectively) in a previously unstudied, mesic cockroach, Aptera fusca, and compared gas exchange and water loss parameters among the major gas exchange patterns (continuous, cyclic, discontinuous gas exchange) at a range of temperatures. Mean , and per unit did not differ among the gas exchange patterns at all temperatures (P>0.09). There was no significant association between temperature and gas exchange pattern type (P=0.63). Percentage of RWL (relative to total water loss) was typically low (9.79±1.84%) and did not differ significantly among gas exchange patterns at 15°C (P=0.26). The method of estimation had a large impact on the percentage of RWL, and of the three techniques investigated (traditional, regression and hyperoxic switch), the traditional method generally performed best. In many respects, A. fusca has typical gas exchange for what might be expected from other insects studied to date (e.g. , , RWL and cuticular water loss). However, we found for A. fusca that expressed as a function of metabolic rate was significantly higher than the expected consensus relationship for insects, suggesting it is under considerable pressure to save water. Despite this, we found no consistent evidence supporting the conclusion that transitions in pattern type yield reductions in RWL in this mesic cockroach.

Investigation of Electron Beam Induced Mass Loss of Embedding Media in the Low Voltage STEM

Czech Academy of Sciences Publication Activity Database

Novotná, V.; Hrubanová, Kamila; Nebesářová, J.; Krzyžánek, Vladislav

2014-01-01

Roč. 20, S3 (2014), s. 1270-1271 ISSN 1431-9276 R&D Projects: GA MŠk EE.2.3.20.0103; GA MŠk(CZ) LO1212; GA ČR(CZ) GA14-20012S; GA TA ČR TE01020118 Institutional support: RVO:68081731 Keywords : mass loss * mass -thickness measurement * low voltage STEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.877, year: 2014

Long-term loss rates of radioisotopes of cobalt, zinc, ruthenium, caesium and silver by Mytilus edulis under field conditions

International Nuclear Information System (INIS)

Dahlgaard, H.

1999-01-01

Long-term loss rates of cobalt, zinc, ruthenium, caesium and silver by Mytilus edulis soft parts as well as shells were measured under field conditions in the Mediterranean Sea at Monaco during a period of 13 months after experimental contamination. For all 5 elements, the loss could be described by two exponential functions for the soft parts and one for the shells. Biological half lives for the long-lived compartment ranged from ∼20 days for caesium to 100 - 200 days for cobalt, zinc, ruthenium and silver for soft parts as well as for shells. A comparison with results from similar experiments performed under very different environmental conditions in the Baltic Sea indicated that caesium and maybe silver had a faster turnover in the warm and saline Mediterranean, whereas loss rates for cobalt and zinc were comparable. It is argued, that reliable deduction of loss rates require experiments running over several months to a year, and it is pointed out that shorter term experiments - even up to 3 months - may give biased results. (author)

Observability of localized magnetoplasmons in quantum dots: Scrutinizing the eligibility of far-infrared, Raman, and electron-energy-loss spectroscopies

Energy Technology Data Exchange (ETDEWEB)

Kushwaha, Manvir S. [Department of Physics and Astronomy, Rice University, P.O. Box 1892, Houston, Texas 77251 (United States)

2016-03-15

We investigate a one-component, quasi-zero dimensional, quantum plasma exposed to a parabolic potential and an applied magnetic field in the symmetric gauge. If the size of such a system as can be realized in the semiconducting quantum dots is on the order of the de-Broglie wavelength, the electronic and optical properties become highly tunable. Then the quantum size effects challenge the observation of many-particle phenomena such as the magneto-optical absorption, Raman intensity, and electron energy-loss spectrum. An exact analytical solution of the problem leads us to infer that these many-particle phenomena are, in fact, dictated by the generalized Kohn’s theorem (GKT) in the long-wavelength limit. Maneuvering the confinement and/or the magnetic field furnishes the resonance energies capable of being explored with the FIR, Raman, and/or electron-energy-loss spectroscopy. This implies that either of these probes is competent in observing the localized magnetoplasmons in the system. As an application of the rigorous analytical diagnosis of the system, we have presented various pertinent single-particle, such as Fock-Darwin spectrum, Fermi energy, zigzag excitation spectrum, and magneto-optical transitions, and the many-particle phenomena, such as magneto-optical absorption, Raman intensity, and electron energy-loss probability. In the latter, the energy position of the resonance peaks is observed to be independent of the electron-electron interactions and hence of the number of electrons in the quantum dot in compliance with the GKT. It is found that both confinement potential and magnetic field play a decisive role in influencing the aforementioned many-particle phenomena. Specifically, increasing (decreasing) the strength of the confining potential is found to be analogous to shrinking (expanding) the size of the quantum dots and results into a blue (red) shift in the respective spectra. Intensifying the magnetic field has two-fold effects in the resonance

Growth rate enhancement of free-electron laser by two consecutive ...

Indian Academy of Sciences (India)

2014-06-03

Jun 3, 2014 ... been the subject of many papers published by different groups all around the world. The radiation is generated by relativistic electron beam passing through a wiggler. ..... Shown in figure 2 are plots of growth rate, Im ¯k, vs.

Rates of bone loss among women initiating antidepressant medication use in midlife.

Science.gov (United States)

Diem, Susan J; Ruppert, Kristine; Cauley, Jane A; Lian, YinJuan; Bromberger, Joyce T; Finkelstein, Joel S; Greendale, Gail A; Solomon, Daniel H

2013-11-01

Concern has been raised that medications that block serotonin reuptake may affect bone metabolism, resulting in bone loss. The aim of the study was to compare annual bone mineral density (BMD) changes among new users of selective serotonin reuptake inhibitors (SSRIs), new users of tricyclic antidepressants (TCAs), and nonusers of antidepressant medications. We conducted a prospective cohort study at five clinical centers in the United States. The study included 1972 community-dwelling women, aged 42 years and older, enrolled in the Study of Women's Health Across the Nation (SWAN). The use of antidepressant medications was assessed by interview and verified from medication containers at annual visits. Subjects were categorized as nonusers (no SSRI or TCA use at any examination), SSRI users (initiated SSRI use after the baseline SWAN visit), or TCA users (initiated TCA use after the baseline visit), using a computerized dictionary to categorize type of medication. BMD at the lumbar spine, total hip, and femoral neck was measured using dual-energy x-ray absorptiometry at annual visits. BMD was compared among 311 new users of SSRIs, 71 new users of TCAs, and 1590 nonusers. After adjustment for potential confounders, including age, race, body mass index, menopausal status, and hormone therapy use, mean lumbar spine BMD decreased on average 0.68% per year in nonusers, 0.63% per year in SSRI users (P = .37 for comparison to nonusers), and 0.40% per year in TCA users (P = .16 for comparison to nonusers). At the total hip and femoral neck, there was also no evidence that SSRI or TCA users had an increased rate of bone loss compared with nonusers. Results were similar in subgroups of women stratified by the Center for Epidemiologic Studies Depression Scale (women, use of SSRIs and TCAs was not associated with an increased rate of bone loss at the spine, total hip, or femoral neck.

Preliminary report on electron energy-loss measurements for CCl3, CCl2F2, CCl3F

International Nuclear Information System (INIS)

Bushnell, D.L. Jr.; Huebner, R.H.; Celotta, R.J.; Mielczarek, S.R.

1975-01-01

Currently, nation-wide research efforts are devoted to studying the possible ozone (O 3 ) depletion in the stratosphere by the chemical action of chlorine atoms released from CCl 2 F 2 or CCl 3 F upon absorption of ultraviolet radiation. Since electron-impact data taken in the forward scattering direction can be used to derive oscillator strengths and thus to yield apparent photoabsorption cross sections, such an analysis for CCl 2 F 2 , CCLl 3 F, and CClF 3 was carried out. Oscillator-strength distributions were obtained between 5 and 20 eV and are compared to available photoabsorption data. Certain photoabsorption values agree very well with these electron-impact data, but other optical studies deviate in some spectral regions by as much as a factor of 5. Also, the electron energy-loss spectrum reveals electronic transitions previously undetected by photoabsorption

Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients

International Nuclear Information System (INIS)

Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; Ji, Wei

2015-01-01

Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Important swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. We show that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections

Simulation of multicomponent losses in electron beam melting and refining at varying scan frequencies

International Nuclear Information System (INIS)

Powell, A.; Szekely, J.; Van Den Avyle, J.; Damkroger, B.

1995-01-01

A two-stage model is presented to describe alloy element evaporation rates from molten metal due to transient local heating by an electron beam. The first stage is a simulation of transient phenomena near the melt surface due to periodic heating by a scanning beam, the output of which is the relationship between operating parameters, surface temperature, and evaporation rate. At high scan rates, this can be done using a simple one-dimensional heat transfer model of the surface layer; at lower scan rates, a more complex three-dimensional model with fluid flow and periodic boundary conditions is necessary. The second stage couples this evaporation-surface temperature relationship with a larger steady state heat transfer and fluid flow model of an entire melting hearth or mold, in order to calculate local and total evaporation rates. Predictions are compared with experimental results from Sandia's 310-kW electron beam melting furnace, in which evaporation rates and vapor compositions were studied in pure titanium and Ti-6%Al-4%V alloy. Evaporation rates were estimated from rate of condensation on a substrate held over the hearth, and were characterized as a function of beam power (150 and 225 kW), scan frequency (30, 115 and 450 Hz) and background pressure (10 -3 , 10 -4 and 10 -5 torr)

Evolutionary developments in x ray and electron energy loss microanalysis instrumentation for the analytical electron microscope

Science.gov (United States)

Zaluzec, Nester J.

Developments in instrumentation for both X ray Dispersive and Electron Energy Loss Spectroscopy (XEDS/EELS) over the last ten years have given the experimentalist a greatly enhanced set of analytical tools for characterization. Microanalysts have waited for nearly two decades now in the hope of getting a true analytical microscope and the development of 300 to 400 kV instruments should have allowed us to attain this goal. Unfortunately, this has not generally been the case. While there have been some major improvements in the techniques, there has also been some devolution in the modern AEM (Analytical Electron Microscope). In XEDS, the majority of today's instruments are still plagued by the hole count effect, which was first described in detail over fifteen years ago. The magnitude of this problem can still reach the 20 percent level for medium atomic number species in a conventional off-the-shelf intermediate voltage AEM. This is an absurd situation and the manufacturers should be severely criticized. Part of the blame, however, also rests on the AEM community for not having come up with a universally agreed upon standard test procedure. Fortunately, such a test procedure is in the early stages of refinement. The proposed test specimen consists of an evaporated Cr film approx. 500 to 1000A thick supported upon a 3mm diameter Molybdenum 200 micron aperture.

Two-electron one-photon decay rates in doubly ionized atoms

International Nuclear Information System (INIS)

Baptista, G.B.

1984-01-01

The transion rate for the two-electron one-photon and one-electron one-photon decaying processes in atoms bearing initially two K-shell vacancies were evaluated for Ne up to Zr. The two-electron one-photon decay process is considered to be the result of the interaction between the jumping electrons and their interaction with the radiation field. The calculation is performed in second order perturbation theory and the many particle states are constructed from single particle solutions. The present approach allows one to discuss several aspects of the decaying process. The results obtained for the branching ratio between the two processes reproduces reasonably well available experimental data and show an almost linear dependence on the second power of the atomic number. A comparison with other theoretical predictions is also presented for the two decaying processes and the strong dependence of the branching ratio on the initial configuration of the decaying atom is pointed out. (Author) [pt

Detection of water and its derivatives on individual nanoparticles using vibrational electron energy-loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Crozier, Peter A., E-mail: crozier@asu.edu [School for the Engineering of Matter, Transport and Energy, Arizona State University, 501 E. Tyler Mall, Tempe, AZ 85287-6106 (United States); Aoki, Toshihiro [LeRoy Eyring Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704 (United States); Liu, Qianlang [School for the Engineering of Matter, Transport and Energy, Arizona State University, 501 E. Tyler Mall, Tempe, AZ 85287-6106 (United States)

2016-10-15

Understanding the role of water, hydrate and hydroxyl species on nanoparticle surfaces and interfaces is very important in both physical and life sciences. Detecting the presence of oxygen-hydrogen species with nanometer resolution is extremely challenging at present. Here we show that the recently developed vibrational electron energy-loss spectroscopy using subnanometer focused electron beams can be employed to spectroscopically identify the local presence and variation of OH species on nanoscale surfaces. The hydrogen-oxygen fingerprint can be correlated with highly localized structural and morphological information obtained from electron imaging. Moreover, the current approach exploits the aloof beam mode of spectral acquisition which does not require direct electron irradiation of the sample thus greatly reducing beam damage to the OH bond. These findings open the door for using electron microscopy to probe local hydroxyl and hydrate species on nanoscale organic and inorganic structures. - Highlights: • High spatial resolution spectroscopic detection of water related species in nanoparticles. • Detection of OH stretch modes with vibrational EELS. • Differentiation between hydrate and hydroxide species on or on nanoparticles. • Detection of hydrate on a single 60 nm oxide nanoparticle of MgO. • Use of aloof beam EELS to minimize radiation damage.

Electron irradiation effects on lithium peroxide

Science.gov (United States)

Kikkawa, Jun; Shiotsuki, Taishi; Shimo, Yusuke; Koshiya, Shogo; Nagai, Takuro; Nito, Takehiro; Kimoto, Koji

2018-03-01

In this study, electron irradiation effects on lithium peroxide (Li2O2), which is an important discharge product of Li-air (or Li-O2) batteries, were investigated using selected-area electron diffraction (SAED) and high-energy resolution electron energy-loss spectroscopy (EELS). The results obtained show that Li2O2 to Li2O transformation occurs with 80 and 300 keV incident electrons under high electron dose rates at 20 and -183 °C. The Li2O2 to Li2O transformation rate for 300 keV was 1/5 of that for 80 keV with the irradiation taking place at -183 °C. We also present a series of the EELS spectra that can be used as a criterion to judge the molar ratio of Li2O to Li2O2 in the general systems where Li2O2 and Li2O coexist.

Investigation of electron-loss and photon scattering correction factors for FAC-IR-300 ionization chamber

Science.gov (United States)

Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

2017-02-01

The parallel-plate free-air ionization chamber termed FAC-IR-300 was designed at the Atomic Energy Organization of Iran, AEOI. This chamber is used for low and medium X-ray dosimetry on the primary standard level. In order to evaluate the air-kerma, some correction factors such as electron-loss correction factor (ke) and photon scattering correction factor (ksc) are needed. ke factor corrects the charge loss from the collecting volume and ksc factor corrects the scattering of photons into collecting volume. In this work ke and ksc were estimated by Monte Carlo simulation. These correction factors are calculated for mono-energy photon. As a result of the simulation data, the ke and ksc values for FAC-IR-300 ionization chamber are 1.0704 and 0.9982, respectively.

Effect of cuticular abrasion and recovery on water loss rates in queens of the desert harvester ant Messor pergandei.

Science.gov (United States)

Johnson, Robert A; Kaiser, Alexander; Quinlan, Michael; Sharp, William

2011-10-15

Factors that affect water loss rates (WLRs) are poorly known for organisms in natural habitats. Seed-harvester ant queens provide an ideal system for examining such factors because WLRs for mated queens excavated from their incipient nests are twofold to threefold higher than those of alate queens. Indirect data suggest that this increase results from soil particles abrading the cuticle during nest excavation. This study provides direct support for the cuticle abrasion hypothesis by measuring total mass-specific WLRs, cuticular abrasion, cuticular transpiration, respiratory water loss and metabolic rate for queens of the ant Messor pergandei at three stages: unmated alate queens, newly mated dealate queens (undug foundresses) and mated queens excavated from their incipient nest (dug foundresses); in addition we examined these processes in artificially abraded alate queens. Alate queens had low WLRs and low levels of cuticle abrasion, whereas dug foundresses had high WLRs and high levels of cuticle abrasion. Total WLR and cuticular transpiration were lowest for alate queens, intermediate for undug foundresses and highest for dug foundresses. Respiratory water loss contributed ~10% of the total WLR and was lower for alate queens and undug foundresses than for dug foundresses. Metabolic rate did not vary across stages. Total WLR and cuticular transpiration of artificially abraded alate queens increased, whereas respiratory water loss and metabolic rate were unaffected. Overall, increased cuticular transpiration accounted for essentially all the increased total water loss in undug and dug foundresses and artificially abraded queens. Artificially abraded queens and dug foundresses showed partial recovery after 14 days.

Characterisation of nano-structured titanium and aluminium nitride coatings by indentation, transmission electron microscopy and electron energy loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Girleanu, M., E-mail: maria.girleanu@uha.fr [Mecanique, Materiaux et Procedes de Fabrication, LPMT (EA CNRS 4365), Universite de Haute Alsace, 61 rue Albert Camus, F-68093 Mulhouse (France); Pac, M.-J.; Louis, P. [Mecanique, Materiaux et Procedes de Fabrication, LPMT (EA CNRS 4365), Universite de Haute Alsace, 61 rue Albert Camus, F-68093 Mulhouse (France); Ersen, O.; Werckmann, J. [Departement Structures et Interfaces, IPCMS (UMR CNRS 7504), Universite de Strasbourg, 23 rue du Loess, F-67087 Strasbourg (France); Rousselot, C. [Departement Micro Nano Sciences et Systemes, FEMTO-ST (UMR CNRS 6174), Universite de Franche-Comte, BP 71427, F-25211 Montbeliard (France); Tuilier, M.-H. [Mecanique, Materiaux et Procedes de Fabrication, LPMT (EA CNRS 4365), Universite de Haute Alsace, 61 rue Albert Camus, F-68093 Mulhouse (France)

2011-07-01

Titanium and aluminium nitride Ti{sub 1-x}Al{sub x}N films deposited by radiofrequency magnetron reactive sputtering onto steel substrate are examined by transmission electron microscopy over all the range of composition (x = 0, 0.5, 0.68, 0.86, 1). The deposition parameters are optimised in order to grow nitride films with low stress over all the composition range. Transmission electron microscopy cross-section images of Vickers indentation prints performed on that set of coatings show the evolution of their damage behaviour as increasing x Al content. Cubic Ti-rich nitrides consist of small grains clustered in rather large columns sliding along each other during indentation. Hexagonal Al-rich films grow in thinner columns which can be bent under the Vickers tip. Indentation tests carried out on TiN and AlN films are simulated using finite element modelling. Particular aspects of shear stresses and displacements in the coating/substrate are investigated. The growth mode and the nanostructure of two typical films, TiN and Ti{sub 0.14}Al{sub 0.86}N, are studied in detail by combining transmission electron microscopy cross-sections and plan views. Electron energy loss spectrum taken across Ti{sub 0.14}Al{sub 0.86}N film suggests that a part of nitrogen atoms is in cubic-like local environment though the lattice symmetry of Al-rich coatings is hexagonal. The poorly crystallised domains containing Ti and N atoms in cubic-like environment are obviously located in grain boundaries and afford protection of the coating against cracking.

Characterisation of nano-structured titanium and aluminium nitride coatings by indentation, transmission electron microscopy and electron energy loss spectroscopy

International Nuclear Information System (INIS)

Girleanu, M.; Pac, M.-J.; Louis, P.; Ersen, O.; Werckmann, J.; Rousselot, C.; Tuilier, M.-H.

2011-01-01

Titanium and aluminium nitride Ti 1-x Al x N films deposited by radiofrequency magnetron reactive sputtering onto steel substrate are examined by transmission electron microscopy over all the range of composition (x = 0, 0.5, 0.68, 0.86, 1). The deposition parameters are optimised in order to grow nitride films with low stress over all the composition range. Transmission electron microscopy cross-section images of Vickers indentation prints performed on that set of coatings show the evolution of their damage behaviour as increasing x Al content. Cubic Ti-rich nitrides consist of small grains clustered in rather large columns sliding along each other during indentation. Hexagonal Al-rich films grow in thinner columns which can be bent under the Vickers tip. Indentation tests carried out on TiN and AlN films are simulated using finite element modelling. Particular aspects of shear stresses and displacements in the coating/substrate are investigated. The growth mode and the nanostructure of two typical films, TiN and Ti 0.14 Al 0.86 N, are studied in detail by combining transmission electron microscopy cross-sections and plan views. Electron energy loss spectrum taken across Ti 0.14 Al 0.86 N film suggests that a part of nitrogen atoms is in cubic-like local environment though the lattice symmetry of Al-rich coatings is hexagonal. The poorly crystallised domains containing Ti and N atoms in cubic-like environment are obviously located in grain boundaries and afford protection of the coating against cracking.

Determination of the air attenuation and electronic loss for the free air concentric cylinders ionization chamber

International Nuclear Information System (INIS)

Oliveira, Hebert Pinto Silveira de

2010-01-01

Along the latest years, the LNMRI has been proceeding a continuous research work with a concentric cylinders type free air ionizing chamber (VICTOREEN, model 481), aiming to establish it as a new national standard, and, as a consequence, replace the worldwide accepted secondary standard, calibrated by PTB. Taking into account that the absolute determination of kerma in air with a free air ionizing chamber implies the acquirement of a number of correction factors. The main objective of the present work comprises the determination of the two factors, specifically, electronic loss (k e ) and air attenuation (k a ). The correction factors were obtained through mammography qualities reference spectrum, using Monte Carlo simulation method. The Penelope code was used in the simulation procedures. Simulations took place in two stages, the acquirement of specters related to the qualities of interest (mammography) with the x ray tube (Pantak, model HF160 e Panalytical, model XRF window), and the free-air ionization chamber. The data were compared to those related to the BIPM chamber, to electronic loss were not detected. The comparison between air attenuation factors was obtained data bellow 0.13%. (author)

Estimating gene gain and loss rates in the presence of error in genome assembly and annotation using CAFE 3.

Science.gov (United States)

Han, Mira V; Thomas, Gregg W C; Lugo-Martinez, Jose; Hahn, Matthew W

2013-08-01

Current sequencing methods produce large amounts of data, but genome assemblies constructed from these data are often fragmented and incomplete. Incomplete and error-filled assemblies result in many annotation errors, especially in the number of genes present in a genome. This means that methods attempting to estimate rates of gene duplication and loss often will be misled by such errors and that rates of gene family evolution will be consistently overestimated. Here, we present a method that takes these errors into account, allowing one to accurately infer rates of gene gain and loss among genomes even with low assembly and annotation quality. The method is implemented in the newest version of the software package CAFE, along with several other novel features. We demonstrate the accuracy of the method with extensive simulations and reanalyze several previously published data sets. Our results show that errors in genome annotation do lead to higher inferred rates of gene gain and loss but that CAFE 3 sufficiently accounts for these errors to provide accurate estimates of important evolutionary parameters.

Transmucosal gas-loss rates in middle ears initially filled with O2 or CO2.

Science.gov (United States)

Kania, Romain E; Vérillaud, Benjamin; Ars, Bernard; Tran Ba Huy, Patrice; Herman, Philippe; Ar, Amos

2016-10-01

This study investigates the role of different gases in clearance of gas in the middle ear cavity (ME) by its mucosal blood flow. A rat model was used to measure gas volume changes in the ME cavity at constant pressure without ventilation. We disturbed the normal gas composition of the ME by filling it with O 2 or CO 2 , measured the consequent changes in gas volume over time and compared these results with previously obtained ones for air and N 2 . The first 5 min of the primary transient phase (phase I) for O 2 or CO 2 was characterized by a volume loss decrease of -0.49 ± 0.34 μL and -46.28 ± 8.49 μL, respectively, with volume loss increase for air and N 2 differing greatly, at +0.17 ± 0.17 and +2.31 ± 0.81, respectively. The CO 2 value of -46.28 μL showed that a volume of gas equivalent to that of the ME cleft volume was eliminated within the first 5 min. In the second phase (phase II), all gases showed a linear decrease in volume, which presumably represents a steady-state gas loss rate. However, the gas loss rate of -0.307 ± 0.170 μL min -1 for O 2 -filled MEs was significantly higher than the mean of -0.124 μL min -1 for all other gases. We used a previously established mathematical model to calculate the effective ME mucosal blood flow rate under steady-state (phase II) conditions. The blood flow results for O 2 -filled MEs differed greatly from those of the other gases (89.0 ± 49.28 vs. 26.5 μL min -1 , on average), which suggest that the model used to calculate blood flow should be modified if used with O 2 -filled MEs. Further work should involve a comparison of our method with different methods to verify ME blood flow rate. Copyright © 2016 Elsevier B.V. All rights reserved.

Complication rate of posterior capsule rupture with vitreous loss during phacoemulsification at a Hawaiian cataract surgical center: a clinical audit

Directory of Open Access Journals (Sweden)

Chen M

2014-02-01

Full Text Available Ming Chen,1 Kara C LaMattina,2 Thomas Patrianakos,2 Surendar Dwarakanathan2 1Department of Surgery, Division of Ophthalmology, University of Hawaii, Honolulu, HI, USA; 2Division of Ophthalmology, John H Stroger, Jr Hospital of Cook County, Chicago, IL, USA Purpose: To compare the complication rate of posterior capsule rupture (PCR with vitreous loss during phacoemulsification at an ambulatory surgical center with published results as a clinical audit for quality control. Methods: A retrospective chart review of 3,339 consecutive patients who underwent routine phacoemulsification by four experienced private practice surgeons from January 1, 2011 to June 30, 2012 at The Surgical Suites, Honolulu, HI, USA. All cases with PCR and vitreous loss were identified and selected for the study. Risk factors of this complication were further examined. Data were sent to John H Stroger Jr Hospital of Cook County, Division of Ophthalmology, for literature review, analysis, and write-up. Results: Twenty-three of the 3,339 cases incurred PCR and vitreous loss during phacoemulsification, for an incidence rate of 0.68%. Miosis, shallow chamber, restlessness, pseudoexfoliation syndrome, floppy iris syndrome, and zonulopathy were the main causes. In addition, surgeon volume (number of cases was inversely correlated with PCR. Conclusion: The rate of PCR with vitreous loss during phacoemulsification in this study may be lower than other published results done at academic centers. However, there was no compatible study available for comparison, as existing studies performed at academic centers included resident cases. This study identified risk factors for PCR/vitreous loss both preoperatively and postoperatively that may assist in application of preventive measures to decrease rates of PCR/vitreous loss. Keywords: phacoemulsification complications, posterior capsule rupture, vitreous loss, vitrectomy, miosis, pseudoexfoliation, floppy iris syndrome, zonulopathy

A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra

International Nuclear Information System (INIS)

Da, B.; Sun, Y.; Ding, Z. J.; Mao, S. F.; Zhang, Z. M.; Jin, H.; Yoshikawa, H.; Tanuma, S.

2013-01-01

A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO 2 in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.

Determination of heart rate variability with an electronic stethoscope.

Science.gov (United States)

Kamran, Haroon; Naggar, Isaac; Oniyuke, Francisca; Palomeque, Mercy; Chokshi, Priya; Salciccioli, Louis; Stewart, Mark; Lazar, Jason M

2013-02-01

Heart rate variability (HRV) is widely used to characterize cardiac autonomic function by measuring beat-to-beat alterations in heart rate. Decreased HRV has been found predictive of worse cardiovascular (CV) outcomes. HRV is determined from time intervals between QRS complexes recorded by electrocardiography (ECG) for several minutes to 24 h. Although cardiac auscultation with a stethoscope is performed routinely on patients, the human ear cannot detect heart sound time intervals. The electronic stethoscope digitally processes heart sounds, from which cardiac time intervals can be obtained. Accordingly, the objective of this study was to determine the feasibility of obtaining HRV from electronically recorded heart sounds. We prospectively studied 50 subjects with and without CV risk factors/disease and simultaneously recorded single lead ECG and heart sounds for 2 min. Time and frequency measures of HRV were calculated from R-R and S1-S1 intervals and were compared using intra-class correlation coefficients (ICC). The majority of the indices were strongly correlated (ICC 0.73-1.0), while the remaining indices were moderately correlated (ICC 0.56-0.63). In conclusion, we found HRV measures determined from S1-S1 are in agreement with those determined by single lead ECG, and we demonstrate and discuss differences in the measures in detail. In addition to characterizing cardiac murmurs and time intervals, the electronic stethoscope holds promise as a convenient low-cost tool to determine HRV in the hospital and outpatient settings as a practical extension of the physical examination.

On a temporal evolution of the ultra-relativistic electron spectrum by action of synchrotron losses and turbulent acceleration

International Nuclear Information System (INIS)

Samsonov, A.M.; Fedorenko, V.N.

1981-01-01

The kinetic equation describing temporal evolution of the ultra-relativistic electrons' energy spectrum effected by synchrotron losses and turbulent acceleration is solved for the isotropic part of the electrons' distribution function. The original distribution is assumed to be given in the form of a power spectrum. Turbulence properties are stated by means of the turbulent acceleration coefficient depending on epsilon energy D(epsilon)=D 0 epsilon 3 which is related to the synchrotron losses coefficient b(epsilon)=b 0 epsilon 3 so that the isotropization of the distribution function is provided without essential acceleration of particles. The initial spectrum is conserved up to some values of time t and energy epsilon connected by inequality epsilonb 0 t 0 /D 0 -2 if epsilonD 0 t>>1 and b 0 >>D 0 . Finally, are possible applications of the solution to description of processes in supernova shells and radio galaxies are discussed [ru

Mass-loss Rates from Coronal Mass Ejections: A Predictive Theoretical Model for Solar-type Stars

Energy Technology Data Exchange (ETDEWEB)

Cranmer, Steven R. [Department of Astrophysical and Planetary Sciences, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309 (United States)

2017-05-10

Coronal mass ejections (CMEs) are eruptive events that cause a solar-type star to shed mass and magnetic flux. CMEs tend to occur together with flares, radio storms, and bursts of energetic particles. On the Sun, CME-related mass loss is roughly an order of magnitude less intense than that of the background solar wind. However, on other types of stars, CMEs have been proposed to carry away much more mass and energy than the time-steady wind. Earlier papers have used observed correlations between solar CMEs and flare energies, in combination with stellar flare observations, to estimate stellar CME rates. This paper sidesteps flares and attempts to calibrate a more fundamental correlation between surface-averaged magnetic fluxes and CME properties. For the Sun, there exists a power-law relationship between the magnetic filling factor and the CME kinetic energy flux, and it is generalized for use on other stars. An example prediction of the time evolution of wind/CME mass-loss rates for a solar-mass star is given. A key result is that for ages younger than about 1 Gyr (i.e., activity levels only slightly higher than the present-day Sun), the CME mass loss exceeds that of the time-steady wind. At younger ages, CMEs carry 10–100 times more mass than the wind, and such high rates may be powerful enough to dispel circumstellar disks and affect the habitability of nearby planets. The cumulative CME mass lost by the young Sun may have been as much as 1% of a solar mass.

Upon Accounting for the Impact of Isoenzyme Loss, Gene Deletion Costs Anticorrelate with Their Evolutionary Rates.

Directory of Open Access Journals (Sweden)

Christopher Jacobs

Full Text Available System-level metabolic network models enable the computation of growth and metabolic phenotypes from an organism's genome. In particular, flux balance approaches have been used to estimate the contribution of individual metabolic genes to organismal fitness, offering the opportunity to test whether such contributions carry information about the evolutionary pressure on the corresponding genes. Previous failure to identify the expected negative correlation between such computed gene-loss cost and sequence-derived evolutionary rates in Saccharomyces cerevisiae has been ascribed to a real biological gap between a gene's fitness contribution to an organism "here and now" and the same gene's historical importance as evidenced by its accumulated mutations over millions of years of evolution. Here we show that this negative correlation does exist, and can be exposed by revisiting a broadly employed assumption of flux balance models. In particular, we introduce a new metric that we call "function-loss cost", which estimates the cost of a gene loss event as the total potential functional impairment caused by that loss. This new metric displays significant negative correlation with evolutionary rate, across several thousand minimal environments. We demonstrate that the improvement gained using function-loss cost over gene-loss cost is explained by replacing the base assumption that isoenzymes provide unlimited capacity for backup with the assumption that isoenzymes are completely non-redundant. We further show that this change of the assumption regarding isoenzymes increases the recall of epistatic interactions predicted by the flux balance model at the cost of a reduction in the precision of the predictions. In addition to suggesting that the gene-to-reaction mapping in genome-scale flux balance models should be used with caution, our analysis provides new evidence that evolutionary gene importance captures much more than strict essentiality.

Upon Accounting for the Impact of Isoenzyme Loss, Gene Deletion Costs Anticorrelate with Their Evolutionary Rates.

Science.gov (United States)

Jacobs, Christopher; Lambourne, Luke; Xia, Yu; Segrè, Daniel

2017-01-01

System-level metabolic network models enable the computation of growth and metabolic phenotypes from an organism's genome. In particular, flux balance approaches have been used to estimate the contribution of individual metabolic genes to organismal fitness, offering the opportunity to test whether such contributions carry information about the evolutionary pressure on the corresponding genes. Previous failure to identify the expected negative correlation between such computed gene-loss cost and sequence-derived evolutionary rates in Saccharomyces cerevisiae has been ascribed to a real biological gap between a gene's fitness contribution to an organism "here and now" and the same gene's historical importance as evidenced by its accumulated mutations over millions of years of evolution. Here we show that this negative correlation does exist, and can be exposed by revisiting a broadly employed assumption of flux balance models. In particular, we introduce a new metric that we call "function-loss cost", which estimates the cost of a gene loss event as the total potential functional impairment caused by that loss. This new metric displays significant negative correlation with evolutionary rate, across several thousand minimal environments. We demonstrate that the improvement gained using function-loss cost over gene-loss cost is explained by replacing the base assumption that isoenzymes provide unlimited capacity for backup with the assumption that isoenzymes are completely non-redundant. We further show that this change of the assumption regarding isoenzymes increases the recall of epistatic interactions predicted by the flux balance model at the cost of a reduction in the precision of the predictions. In addition to suggesting that the gene-to-reaction mapping in genome-scale flux balance models should be used with caution, our analysis provides new evidence that evolutionary gene importance captures much more than strict essentiality.

Intense synchrotron radiation from a magnetically compressed relativistic electron layer

International Nuclear Information System (INIS)

Shearer, J.W.; Nowak, D.A.; Garelis, E.; Condit, W.C.

1975-10-01

Using a simple model of a relativistic electron layer rotating in an axial magnetic field, energy gain by an increasing magnetic field and energy loss by synchrotron radiation were considered. For a typical example, initial conditions were approximately 8 MeV electron in approximately 14 kG magnetic field, at a layer radius of approximately 20 mm, and final conditions were approximately 4 MG magnetic field approximately 100 MeV electron layer energy at a layer radius of approximately 1.0 mm. In the final state, the intense 1-10 keV synchrotron radiation imposes an electron energy loss time constant of approximately 100 nanoseconds. In order to achieve these conditions in practice, the magnetic field must be compressed by an imploding conducting liner; preferably two flying rings in order to allow the synchrotron radiation to escape through the midplane. The synchrotron radiation loss rate imposes a lower limit to the liner implosion velocity required to achieve a given final electron energy (approximately 1 cm/μsec in the above example). In addition, if the electron ring can be made sufficiently strong (field reversed), the synchrotron radiation would be a unique source of high intensity soft x-radiation

Investigation the effect of porosity on corrosion of macroporous silicon in 1.0 M sodium hydroxide solution using weight loss measurements, electrochemical methods and scanning electron microscope

International Nuclear Information System (INIS)

Lai, Chuan; Xiang, Zhen

2015-01-01

Highlights: • The dissolution of silicon wafers conforms Faraday’s laws of electrolysis. • The porosity effect on macroporous silicon corrosion was investigated. • The corrosion rate increase linearly with porosity increasing. • The porosity effect on activation parameters was obtained. - Abstract: In this study, the macroporous silicon has been fabricated by electrochemical anodization. The dissolution of n-type silicon wafers in etching solution conforms Faraday’s laws of electrolysis. The fabricated macroporous silicon with different porosity corrosion in 1.0 M NaOH was systemically investigated by weight loss measurements, electrochemical methods and scanning electron microscope. Results show that with the porosity increasing, the corrosion rate of macroporous silicon in 1.0 M NaOH increases linearly. In addition, the increase of corrosion rate of macroporous silicon with relative higher porosity was determined by the pre-exponential factor.

Defect production rates by electrons, ions and neutrons in cubic metals

International Nuclear Information System (INIS)

Jung, P.; Nielsen, B.R.; Andersen, H.H.

1982-01-01

The results of an interlaboratory program to study low temperature damage rates in dilute alloys of 300 ppM Zr in vanadium, niobium and molybdenum with electrons, light ions, fission neutrons and high energy neutrons are summarized. Additional experiments and literature data supplied complete sets of data also for the fcc metals Al, Cu and Pt. From the initial damage rates, displacement functions for each material were derived which give the number of stable defects produced by a recoil event of a certain knock-on energy. The low and high energy part of the displacement function was determined from the results of the electron and neutron irradiations, respectively, while the light ion data supplied information on the intermediate energy range. The displacement function allows the reliable calculation of atomic displacement rates also for particles and/or energies not employed in this program. For all metals the displacement rates for high energy neutrons scaled reasonably with the minimum displacement energies. This allows to estimate neutron damage rates also for those cubic metals where no high energy neutron results are available. For stainless steel, e.g., an average displacement energy of about 120 eV is deduced. The results are suggested to find practical use in defect calculations for fusion reactor first wall technology and in correlating the corresponding simulation experiments

Observability of localized magnetoplasmons in quantum dots: Scrutinizing the eligibility of far-infrared, Raman, and electron-energy-loss spectroscopies

Directory of Open Access Journals (Sweden)

Manvir S. Kushwaha

2016-03-01

Full Text Available We investigate a one-component, quasi-zero dimensional, quantum plasma exposed to a parabolic potential and an applied magnetic field in the symmetric gauge. If the size of such a system as can be realized in the semiconducting quantum dots is on the order of the de-Broglie wavelength, the electronic and optical properties become highly tunable. Then the quantum size effects challenge the observation of many-particle phenomena such as the magneto-optical absorption, Raman intensity, and electron energy-loss spectrum. An exact analytical solution of the problem leads us to infer that these many-particle phenomena are, in fact, dictated by the generalized Kohn’s theorem (GKT in the long-wavelength limit. Maneuvering the confinement and/or the magnetic field furnishes the resonance energies capable of being explored with the FIR, Raman, and/or electron-energy-loss spectroscopy. This implies that either of these probes is competent in observing the localized magnetoplasmons in the system. As an application of the rigorous analytical diagnosis of the system, we have presented various pertinent single-particle, such as Fock-Darwin spectrum, Fermi energy, zigzag excitation spectrum, and magneto-optical transitions, and the many-particle phenomena, such as magneto-optical absorption, Raman intensity, and electron energy-loss probability. In the latter, the energy position of the resonance peaks is observed to be independent of the electron-electron interactions and hence of the number of electrons in the quantum dot in compliance with the GKT. It is found that both confinement potential and magnetic field play a decisive role in influencing the aforementioned many-particle phenomena. Specifically, increasing (decreasing the strength of the confining potential is found to be analogous to shrinking (expanding the size of the quantum dots and results into a blue (red shift in the respective spectra. Intensifying the magnetic field has two-fold effects in

Investigation of electron-loss and photon scattering correction factors for FAC-IR-300 ionization chamber

International Nuclear Information System (INIS)

Mohammadi, S.M.; Tavakoli-Anbaran, H.; Zeinali, H.Z.

2017-01-01

The parallel-plate free-air ionization chamber termed FAC-IR-300 was designed at the Atomic Energy Organization of Iran, AEOI. This chamber is used for low and medium X-ray dosimetry on the primary standard level. In order to evaluate the air-kerma, some correction factors such as electron-loss correction factor (k e ) and photon scattering correction factor (k sc ) are needed. k e factor corrects the charge loss from the collecting volume and k sc factor corrects the scattering of photons into collecting volume. In this work k e and k sc were estimated by Monte Carlo simulation. These correction factors are calculated for mono-energy photon. As a result of the simulation data, the k e and k sc values for FAC-IR-300 ionization chamber are 1.0704 and 0.9982, respectively.

Two dimensional CCD [charged coupled device] arrays as parallel detectors in electron energy loss and x-ray wavelength dispersive spectroscopy

International Nuclear Information System (INIS)

Zaluzec, N.J.

1988-08-01

Parallel detection systems for spectroscopy have generally been based upon linear detector arrays. Replacing the linear arrays with two dimensional systems yields more complicated devices; however, there are corresponding benefits which can be realized for both x-ray and electron energy loss spectroscopy. The operational design of these systems, as well as preliminary results from the construction of such a device used for electron spectroscopy, are presented. 10 refs., 8 figs

Profound vision loss impairs psychological well-being in young and middle-aged individuals.

Science.gov (United States)

Garcia, Giancarlo A; Khoshnevis, Matin; Gale, Jesse; Frousiakis, Starleen E; Hwang, Tiffany J; Poincenot, Lissa; Karanjia, Rustum; Baron, David; Sadun, Alfredo A

2017-01-01

The aim of this study was to evaluate the effects of profound vision loss on psychological well-being in adolescents, young adults, and middle-aged adults with regard to mood, interpersonal interactions, and career-related goals. In addition, we assessed the significance of the resources that may be used to enhance psychological well-being in cases of profound vision loss, and in particular, examined the utility of low vision aids and the role of the ophthalmologist as a provider of emotional support. A questionnaire was issued to individuals aged 13-65 years with profound vision loss resulting from Leber's hereditary optic neuropathy (LHON). Depression prevalence was evaluated with questions regarding major depressive disorder symptomatology. Participants appraised the effects of vision loss on their interpersonal interactions and career goals by providing an impact rating (IR) on a 21-point psychometric scale from -10 to +10. Social well-being index was defined as the average of interpersonal IR and career IR. Subjects were additionally asked about the use of low vision aids and sources of emotional support. A total of 103 participants (mean age =26.4±11.2 years at LHON diagnosis; mean ± standard deviation) completed the questionnaire. Nearly half (49.5%) met the depression criteria after vision loss. Negative impacts on interpersonal interactions (median IR = -5) and career goals (median IR = -6) were observed; both ratings were worse ( P negative interpersonal IR and career IR. Sixty-eight percent of subjects used electronic vision aids; controlling for age, social well-being index was higher among these individuals than for those who did not use electronic aids ( P =0.03). Over half of the participants (52.4%) asserted that they derived emotional support from their ophthalmologist. Profound vision loss in adolescents, young adults, and middle-aged adults is associated with significant negative psychological and psychosocial effects, which are influenced by

Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Liu, Qianlang [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States); March, Katia [Laboratoire de Physique des Solides, Bâtiment 510, Université Paris-Sud, 91405 Orsay Cedex (France); Crozier, Peter A., E-mail: CROZIER@asu.edu [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States)

2017-07-15

Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO{sub 2} anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO{sub 2} showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60 nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1 eV above the MgO valence band. At the surfaces of TiO{sub 2} nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. - Highlights: • Bandgap states detected with aloof beam monochromated EELS on oxide nanoparticle surfaces. • Dielectric theory applied to simulate the spectra and interpret surface structure. • Density of states models also be employed to understand the surface electronic structure. • In MgO, one states associate with water species was found close to the valence band edge. • In anatase, two mid-gap states associated with point defects were found.

Radial diffusion in the Uranian radiatian belts - Inferences from satellite absorption loss models

Science.gov (United States)

Hood, L. L.

1989-01-01

Low-energy charged particle (LECP) phase space density profiles available from the Voyager/1986 Uranus encounter are analyzed, using solutions of the time-averaged radial diffusion equation for charged particle transport in a dipolar planetary magnetic field. Profiles for lower-energy protons and electrons are first analyzed to infer radial diffusion rate as a function of L, assuming that satellite absorption is the dominant loss process and local sources for these particles are negligible. Satellite macrosignatures present in the experimentally derived profiles are approximately reproduced in several cases, lending credence to the loss model and indicating that magnetospheric distributed losses are not as rapid as satellite absorption near the minimum satellite L shells for the particles. Diffusion rates and L dependences are found to be similar to those previously inferred in the inner Jovian magnetosphere (Thomsen et al., 1977) and for the inner Saturnian magnetosphere (Hood, 1985). Profiles for higher energy electrons and protons are also analyzed using solutions that allow for the existence of significant particle sources as well as sinks. Possible implications for radial diffusion mechanisms in the Uranian radiation belts are discussed.

Fundamental rate-loss trade-off for the quantum internet.

Science.gov (United States)

Azuma, Koji; Mizutani, Akihiro; Lo, Hoi-Kwong

2016-11-25

The quantum internet holds promise for achieving quantum communication-such as quantum teleportation and quantum key distribution (QKD)-freely between any clients all over the globe, as well as for the simulation of the evolution of quantum many-body systems. The most primitive function of the quantum internet is to provide quantum entanglement or a secret key to two points efficiently, by using intermediate nodes connected by optical channels with each other. Here we derive a fundamental rate-loss trade-off for a quantum internet protocol, by generalizing the Takeoka-Guha-Wilde bound to be applicable to any network topology. This trade-off has essentially no scaling gap with the quantum communication efficiencies of protocols known to be indispensable to long-distance quantum communication, such as intercity QKD and quantum repeaters. Our result-putting a practical but general limitation on the quantum internet-enables us to grasp the potential of the future quantum internet.

Local secondary-electron emission spectra of graphite and gold surfaces obtained using the Scanning Probe Energy Loss Spectrometer (SPELS)

International Nuclear Information System (INIS)

Lawton, J J; Pulisciano, A; Palmer, R E

2009-01-01

Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.

Local secondary-electron emission spectra of graphite and gold surfaces obtained using the Scanning Probe Energy Loss Spectrometer (SPELS)

Energy Technology Data Exchange (ETDEWEB)

Lawton, J J; Pulisciano, A; Palmer, R E, E-mail: R.E.Palmer@bham.ac.u [Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)

2009-11-25

Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.

Calculation of dose-rate conversion factors for external exposure to photons and electrons

International Nuclear Information System (INIS)

Kocher, D.C.

1978-01-01

Methods are presented for the calculation of dose-rate conversion factors for external exposure to photon and electron radiation from radioactive decay. A dose-rate conversion factor is defined as the dose-equivalent rate per unit radionuclide concentration. Exposure modes considered are immersion in contaminated air, immersion in contaminated water, and irradiation from a contaminated ground surface. For each radiation type and exposure mode, dose-rate conversion factors are derived for tissue-equivalent material at the body surface of an exposed individual. In addition, photon dose-rate conversion factors are estimated for 22 body organs. The calculations are based on the assumption that the exposure medium is infinite in extent and that the radionuclide concentration is uniform. The dose-rate conversion factors for immersion in contaminated air and water then follow from the requirement that all of the energy emitted in the radioactive decay is absorbed in the infinite medium. Dose-rate conversion factors for ground-surface exposure are calculated at a reference location above a smooth, infinite plane using the point-kernel integration method and known specific absorbed fractions for photons and electrons in air

Direct observation and theory of trajectory-dependent electronic energy losses in medium-energy ion scattering.

Science.gov (United States)

Hentz, A; Parkinson, G S; Quinn, P D; Muñoz-Márquez, M A; Woodruff, D P; Grande, P L; Schiwietz, G; Bailey, P; Noakes, T C Q

2009-03-06

The energy spectrum associated with scattering of 100 keV H+ ions from the outermost few atomic layers of Cu(111) in different scattering geometries provides direct evidence of trajectory-dependent electronic energy loss. Theoretical simulations, combining standard Monte Carlo calculations of the elastic scattering trajectories with coupled-channel calculations to describe inner-shell ionization and excitation as a function of impact parameter, reproduce the effects well and provide a means for far more complete analysis of medium-energy ion scattering data.

Predicting the Rate Constant of Electron Tunneling Reactions at the CdSe-TiO2 Interface.

Science.gov (United States)

Hines, Douglas A; Forrest, Ryan P; Corcelli, Steven A; Kamat, Prashant V

2015-06-18

Current interest in quantum dot solar cells (QDSCs) motivates an understanding of the electron transfer dynamics at the quantum dot (QD)-metal oxide (MO) interface. Employing transient absorption spectroscopy, we have monitored the electron transfer rate (ket) at this interface as a function of the bridge molecules that link QDs to TiO2. Using mercaptoacetic acid, 3-mercaptopropionic acid, 8-mercaptooctanoic acid, and 16-mercaptohexadecanoic acid, we observe an exponential attenuation of ket with increasing linker length, and attribute this to the tunneling of the electron through the insulating linker molecule. We model the electron transfer reaction using both rectangular and trapezoidal barrier models that have been discussed in the literature. The one-electron reduction potential (equivalent to the lowest unoccupied molecular orbital) of each molecule as determined by cyclic voltammetry (CV) was used to estimate the effective barrier height presented by each ligand at the CdSe-TiO2 interface. The electron transfer rate (ket) calculated for each CdSe-ligand-TiO2 interface using both models showed the results in agreement with the experimentally determined trend. This demonstrates that electron transfer between CdSe and TiO2 can be viewed as electron tunneling through a layer of linking molecules and provides a useful method for predicting electron transfer rate constants.

Joint density of states of wide-band-gap materials by electron energy loss spectroscopy

International Nuclear Information System (INIS)

Fan, X.D.; Peng, J.L.; Bursill, L.A.

1998-01-01

Kramers-Kronig analysis for parallel electron energy loss spectroscopy (PEELS) data is developed as a software package. When used with a JEOL 4000EX high-resolution transmission electron microscope (HRTEM) operating at 100 keV this allows us to obtain the dielectric function of relatively wide band gap materials with an energy resolution of approx 1.4 eV. The imaginary part of the dielectric function allows the magnitude of the band gap to be determined as well as the joint-density-of-states function. Routines for obtaining three variations of the joint-density of states function, which may be used to predict the optical and dielectric response for angle-resolved or angle-integration scattering geometries are also described. Applications are presented for diamond, aluminum nitride (AlN), quartz (SiO 2 ) and sapphire (Al 2 O 3 ). The results are compared with values of the band gap and density of states results for these materials obtained with other techniques. (authors)

Electron energy-loss spectroscopy of single nanocrystals: mapping of tin allotropes

Science.gov (United States)

Roesgaard, Søren; Ramasse, Quentin; Chevallier, Jacques; Fyhn, Mogens; Julsgaard, Brian

2018-05-01

Using monochromated electron energy-loss spectroscopy (EELS), we are able to map different allotropes in Sn-nanocrystals embedded in Si. It is demonstrated that α-Sn and β-Sn, as well as an interface related plasmon, can be distinguished in embedded Sn-nanostructures. The EELS data is interpreted by standard non-negative matrix factorization followed by a manual Lorentzian decomposition. The decomposition allows for a more physical understanding of the EELS mapping without reducing the level of information. Extending the analysis from a reference system to smaller nanocrystals demonstrates that allotrope determination in nanoscale systems down below 5 nm is possible. Such local information proves the use of monochromated EELS mapping as a powerful technique to study nanoscale systems. This possibility enables investigation of small nanostructures that cannot be investigated through other means, allowing for a better understanding and thus leading to realizations that can result in nanomaterials with improved properties.

Amplification of radiation near cyclotron frequency due to electron population inversion

International Nuclear Information System (INIS)

Lee, L.C.; Wu, C.S.

1980-01-01

Amplification of electromagnetic waves via the cyclotron maser mechanism by a population of weakly relativistic electrons is studied. The effect of a tenuous population of low energy background plasma is included. It is found that both the ordinary and extraordinary modes can be excited by the weakly relativistic electrons with a loss-cone distribution. The growth rate for the extraordinary mode is much higher than that for the ordinary mode. Velocity spread in the energetic electron distribution function may reduce the growth rate by a factor of approximately 10 from that in the monoenergetic case. The maximum growth rate for the fast extraordinary mode (X mode) occurs near the upper hybrid cutoff frequency. Numerical results are obtained and discussed

Dosimetric accuracy at low monitor unit setting in electron beams at different dose rates

International Nuclear Information System (INIS)

Ravikumar, M.; Ravichandran, R.; Supe, Sanjay S.; Sharma, Anil K.

1999-01-01

As electron beam with low monitor unit (LMU) settings are used in some dosimetric studies, better understanding of accuracy in dose delivery at LMU setting is necessary. The dose measurements were carried out with 0.6 cm 3 farmer type ion chamber at d max in a polystyrene phantom. Measurements at different MUs show that the dose linearity ratio (DLR) increases as the MU setting decreases below 20 MU and DLRs are found to increase when the incident electron beams have higher energies. The increase in DLR is minimum for low dose rate setting for all five electron beam energies (6, 9, 12, 16 and 20 MeV). As the variation in dose delivery is machine-specific, a detailed study should be conducted before the low MU setting is implemented. Since errors in dose delivery are high at higher dose rates, low dose rate may be better at low MU unit setting. (author)

Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells.

Science.gov (United States)

Laschinsky, Lydia; Karsch, Leonhard; Leßmann, Elisabeth; Oppelt, Melanie; Pawelke, Jörg; Richter, Christian; Schürer, Michael; Beyreuther, Elke

2016-08-01

Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10(10) Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone.

Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells

International Nuclear Information System (INIS)

Laschinsky, Lydia; Karsch, Leonhard; Schuerer, Michael; Lessmann, Elisabeth; Beyreuther, Elke; Oppelt, Melanie; Pawelke, Joerg; Richter, Christian

2016-01-01

Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10"1"0 Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone. (orig.)

Development of highly flexible and ultra-low permeation rate thin-film barrier structure for organic electronics

International Nuclear Information System (INIS)

Kim, Namsu; Graham, Samuel

2013-01-01

A flexible thin-film encapsulation architecture for organic electronics was built and consisted of a silicon oxide/alumina and parylene layer deposited over Ca sensors on a barrier-coated polyethylene terephthalate substrate. The film's effective water vapor transmission rate was 2.4 ± 1.5 × 10 −5 g/m 2 /day at 20 °C and 50% relative humidity. Flexural tests revealed that for films deposited on the polyethylene terephthalate substrate, the barrier layer failed due to cracking at a curvature radius of 6.4 mm, corresponding to a strain of 0.8%. Adding an epoxy top coat of suitable thickness shifted the neutral axis toward the encapsulation layer, reducing the induced strain. Barrier performance was maintained under the 6.4 mm radius of curvature in this encapsulation structure. Thus, shifting the neutral axis via device structural design is an effective method of extending the flexibility of thin-film encapsulation structure without compromising the performance loss as a barrier layer. - Highlights: • High performance barrier is fabricated on flexible substrate. • The water vapor transmission rate is 2.4 ± 1.5 × 10 −5 g/m 2 /day. • The structure maintains its performance under a small radius of bending curvature

Effectiveness of two contrasting mulching rates to reduce post-fire soil and organic matter losses

Science.gov (United States)

Silva, Flavio; Prats, Sergio; Vieira, Diana; Puga, João; Lopes, Rita; Gonzaléz-Pelayo, Oscar; Caetano, Ana; Campos, Isabel; Keizer, Jacob

2017-04-01

Wildfire-affected soils can reveal strong responses in runoff generation and associated soil (fertility) losses, thereby constituting a major threat to the typically shallow and poor forest soils of the Portuguese mountain areas. Mulching with logging residues from these forests has proven to provide a protective soil cover that is highly effective in reducing post-fire runoff and especially erosion (Prats et al., 2012, 2014, 2016a, 2016b). However, these past experiments have all applied comparatively large amounts of forest residues, in the order of 10 Mg ha-1, so that the relationship between application rate and effectiveness is still poorly known. Such relationship would nonetheless be of crucial importance for the employment of forest residue mulching in practice, as one of the possible emergency stabilization measures to be contemplated in post-fire land management of a recently-burned area. Further research gaps that exist in relation to post-fire forest residue mulching include its effectiveness in reducing soil fertility losses (C, N, P; Ferreira et al., 2016a, 2016b) and in minimizing export of contaminants (especially PAHs and metals; Campos et al., 2016), and its (secondary) impacts on soil biological activity and diversity (Puga et al., 2016) and on forest productivity (including through the addition of organic matter to the soil surface, partially replacing the burned litter layer; Prats et al. 2016b). In the framework of the EU-project RECARE, the effectiveness of two contrasting mulching rates with forest logging residues has been tested following a wildfire that on August 9th - 10th 2015 consumed some 715 ha of eucalypt plantations in the Semide municipality, central Portugal. Commercially-available logging residues (chopped bark and twigs) from eucalypt plantations were purchased, transported to the study site and applied to six out of nine 16 m2 erosion bounded plots that had been installed in a burned eucalypt plantation using a randomized

Electron scattering rate in epitaxial YBa2Cu3O7 superconducting films

Science.gov (United States)

Flik, M. I.; Zhang, Z. M.; Goodson, K. E.; Siegal, M. P.; Phillips, Julia M.

1992-09-01

This work determines the electron scattering rate in the a-b plane of epitaxial YBa2Cu3O7 films using two techniques. Infrared spectroscopy yields the scattering rate at temperatures of 10, 78, and 300 K by fitting reflectance data using thin-film optics and a model for the free-carrier conductivity. The scattering rate is also obtained using kinetic theory and an extrapolation of normal-state electrical resistivity data to superconducting temperatures based on the Bloch theory for the phonon-limited electrical resistivity of metals. The scattering rates determined using both techniques are in agreement and show that the electron mean free path in the a-b plane of YBa2Cu3O7 superconducting films is three to four times the coherence length. Hence YBa2Cu3O7 is pure but not in the extreme pure limit. An average defect interaction range of 4 nm is obtained using the defect density resulting from flux-pinning considerations.

Electron transfer rates and equilibria between substituted phenoxide ions and phenoxyl radicals

International Nuclear Information System (INIS)

Steenken, S.; Neta, P.

1979-01-01

The rate constants for electron transfer from a series of substituted isomeric dihydroxy- and diaminobenzenes to different substituted phenoxyl radicals were measured by observing the decay or buildup of one of the radicals invoved. In many cases the electron transfer reactions were reversible and the equilibrium constants could be calculated from the individual rate constants for attainment of equilibrium and from the concentrations of the species involved at equilibrium. From the equilibrium constants the one-electron redox potentials for 15 individual Q - ./Q 2- pairs were determined, using the value for hydroquinone (23 mV at pH 13.5) as a reference. The potential for catechol (43 mV) is near that of hydroquinone; resorcinol is oxidized much less readily (300 mV), while phenol is even a weaker reductant (>500mV). Methyl, methoxy, and hydroxy substituents decrease the redox potentials while acetyl and carboxyl substituents increase these values. Ascorbate has a potential (15mV) similar to that of hydroquinone, while TMPD (82mV) and p-phenylenediamine (183mV) are less easily oxidized

Diagnostic for a high-repetition rate electron photo-gun and first measurements

Science.gov (United States)

Filippetto, D.; Doolittle, L.; Huang, G.; Norum, E.; Portmann, G.; Qian, H.; Sannibale, F.

2015-05-01

The APEX electron source at LBNL combines the high-repetition-rate with the high beam brightness typical of photoguns, delivering low emittance electron pulses at MHz frequency. Proving the high beam quality of the beam is an essential step for the success of the experiment, opening the doors of the high average power to brightness-hungry applications as X-Ray FELs, MHz ultrafast electron diffraction etc.. As first step, a complete characterization of the beam parameters is foreseen at the Gun beam energy of 750 keV. Diagnostics for low and high current measurements have been installed and tested, and measurements of cathode lifetime and thermal emittance in a RF environment with mA current performed. The recent installation of a double slit system, a deflecting cavity and a high precision spectrometer, allow the exploration of the full 6D phase space. Here we discuss the present layout of the machine and future upgrades, showing the latest results at low and high repetition rate, together with the tools and techniques used.

Ionization rates and profiles of electron concentration in Martian atmosphere

International Nuclear Information System (INIS)

Komitov, B.; Spasov, S.; Gogoshev, M.

1981-01-01

The ionization and vertical profiles of electron concentration in the Martian atmosphere are calculated as functions of the solar zenith angles varying from O deg to 90 deg. A neutral atmospheric model based on direct mass-spectometric measurements from the Viking-1 landing modul is employed in the calculation. The Earth data of the ionization solar flux at the same level of the solar activity and for the month of the Viking-1 measurements reduced for the Mars orbit are used. The numerical result for the photoionization rates and quasi-equilibrium electron-concentration profiles in the upper Martian atmosphere at different solar zenith angles from 0 deg to 100 deg are presented. It is shown that the maxima of both quantities decrease and move towards the upper atmosphere regions. The calculated electron density at the zenith solar angle of 40 deg are compared to Viking-1 experimental data and a good agreement is achieved

A scenario for impacts of water availability loss due to climate change on riverine fish extinction rates

OpenAIRE

Tedesco, Pablo; Oberdorff, Thierry; Cornu, Jean-François; Beauchard, O.; Brosse, S.; Durr, H. H.; Grenouillet, G.; Leprieur, F.; Tisseuil, Clément; Zaiss, Rainer; Hugueny, Bernard

2013-01-01

1. Current models estimating impact of habitat loss on biodiversity in the face of global climate change usually project only percentages of species committed to extinction' on an uncertain time-scale. Here, we show that this limitation can be overcome using an empirically derived background extinction rate-area' curve to estimate natural rates and project future rates of freshwater fish extinction following variations in river drainage area resulting from global climate change.2. Based on fu...

Tensor decompositions for the analysis of atomic resolution electron energy loss spectra

Energy Technology Data Exchange (ETDEWEB)

Spiegelberg, Jakob; Rusz, Ján [Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala (Sweden); Pelckmans, Kristiaan [Department of Information Technology, Uppsala University, Box 337, S-751 05 Uppsala (Sweden)

2017-04-15

A selection of tensor decomposition techniques is presented for the detection of weak signals in electron energy loss spectroscopy (EELS) data. The focus of the analysis lies on the correct representation of the simulated spatial structure. An analysis scheme for EEL spectra combining two-dimensional and n-way decomposition methods is proposed. In particular, the performance of robust principal component analysis (ROBPCA), Tucker Decompositions using orthogonality constraints (Multilinear Singular Value Decomposition (MLSVD)) and Tucker decomposition without imposed constraints, canonical polyadic decomposition (CPD) and block term decompositions (BTD) on synthetic as well as experimental data is examined. - Highlights: • A scheme for compression and analysis of EELS or EDX data is proposed. • Several tensor decomposition techniques are presented for BSS on hyperspectral data. • Robust PCA and MLSVD are discussed for denoising of raw data.

High-energy inverse free-electron laser accelerator

International Nuclear Information System (INIS)

Courant, E.D.; Pellegrini, C.; Zakowicz, W.

1985-01-01

We study the inverse free electron laser (IFEL) accelerator and show that it can accelerate electrons to the few hundred GeV region with average acceleration rates of the order of 200 meV/m. Several possible accelerating structures are analyzed, and the effect of synchrotron radiation losses is studied. The longitudinal phase stability of accelerated particles is also analyzed. A Hamiltonian description, which takes into account the dissipative features of the IFEL accelerator, is introduced to study perturbations from the resonant acceleration. Adiabatic invariants are obtained and used to estimate the change of the electron phase space density during the acceleration process

Comparison of rate of En masse retraction and anchorage loss in conventional labial appliance with labial and lingual force: A clinical study

Directory of Open Access Journals (Sweden)

Dilshad Quraishi

2018-01-01

Full Text Available Aims: The rate of en masse retraction and anchorage loss were compared between labial appliance with lingual force and conventional labial appliance. Subjects and Methods: The sample consists of 14 patients and they were divided into two groups. In Group 1 – labial appliance with lingual force, elastomeric chain was placed from the palatal surface of the canines to the palatal surface of the molars. In Group 2 – labial appliance with labial force, elastomeric chain was placed from the crimpable hook distal to lateral incisor to the molar tube hooks. The rate of en masse retraction and anchorage loss was calculated for both the groups during retraction in dental casts (R0, initial; R1, 4 weeks; R2, 8 weeks; and R3, 12 weeks. Statistical Analysis Used: Student's paired t-test. Results: The rate of retraction was faster and anchorage loss was lower with labial appliance with lingual force, i.e., Group 1. The difference of anchorage loss in Group 1 and Group 2 shows t = 4.824 and P value= 0.000, which is statistically highly significant. The difference of rate of retraction in Group 1 and Group 2 shows t = 3.573 and P value = 0.004, which is statistically signifcant. Conclusions: The rate of retraction was faster and anchorage loss was lower with labial appliance with lingual force, thus indicating that this new technique of space closure utilizes biomechanical advantage of lingual force in conventional labial appliance.

The impact of rate of weight loss on body composition and compensatory mechanisms during weight reduction

DEFF Research Database (Denmark)

Coutinho, Sílvia Ribeiro; With, Emilie; Rehfeld, Jens F

2018-01-01

BACKGROUND & AIMS: Rapid weight loss (WL) has been associated with a larger loss of fat free mass and a disproportional reduction in resting metabolic rate (RMR), but the evidence is inconclusive. We aimed to evaluate the impact of WL rate on body composition and compensatory mechanisms activated...... with WL (reduced RMR, increased exercise efficiency (ExEff) and appetite), both during negative and neutral energy balance (EB). METHODS: Thirty-five participants with obesity were randomized to lose a similar weight rapidly (4 weeks) or gradually (8 weeks), and afterwards to maintain it (4 weeks). Body...... weight and composition, RMR, ExEff (10, 25 and 50 W), appetite feelings and appetite-regulating hormones (active ghrelin, cholecystokinin, total peptide YY (PYY), active glucagon-like peptide-1 and insulin), in fasting and every 30 min up to 2.5 h, were measured at baseline and after each phase. RESULTS...

Influence of radiation exposure rate on somatic mutation frequency and loss of reproductive integrity in tradescantia stamen hairs

International Nuclear Information System (INIS)

Ichikawa, S.; Nauman, C.H.; Sparrow, A.H.; Takahashi, C.S.

1978-01-01

Inflorescences of Tradescantia clone 02 (2n=12), hetero- or hemi-zygous for flower color, were exposed to a series of γ-ray exposures at two different exposure rates, 29.3 R/min and 0.026-0.52 R/min. Pink mutation-response curves, and survival curves based on reproductive integrity, were constructed for each of the exposure rates. Loss of reproductive integrity was also assessed at high (256 R/min) and low (0.52-4.17 R/min) γ-ray exposure rates in T. blossfeldiana (2n=72). All observations were made on stamen hairs. The higher exposure rate was 1.3-1.7 times more effective in inducing pink mutations in clone 02. A greater efficiency of the higher exposure rate was also found for both taxa at the loss of reproductive integrity endpoint. The D 0 values obtained at the higher exposure rates, 154 R for clone 02 and 720 R for T. blossfeldiana, were significantly lower than the corresponding values of 270 R and 1880 R obtained at the lower exposure rates. These D 0 's differ by factors of 1.75 and 2.61 for clone 02 and T. blossfeldiana, respectively. D 0 's for the two taxa were found to be inversely correlated with their interphase chromosome volumes. (Auth.)

High-resolution parallel electron energy-loss spectroscopy of MnL2,3-edges in inorganic manganese compounds