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On the ab initio calculation of CVV Auger spectra in closed-shell systems  [PDF]
G. Fratesi,M. I. Trioni,G. P. Brivio,S. Ugenti,E. Perfetto,M. Cini
Physics , 2008, DOI: 10.1103/PhysRevB.78.205111
Abstract: We propose an ab initio method to evaluate the core-valence-valence (CVV) Auger spectrum of systems with filled valence bands. The method is based on the Cini-Sawatzky theory, and aims at estimating the parameters by first-principles calculations in the framework of density-functional theory (DFT). Photoemission energies and the interaction energy for the two holes in the final state are evaluated by performing DFT simulations for the system with varied population of electronic levels. Transition matrix elements are taken from atomic results. The approach takes into account the non-sphericity of the density of states of the emitting atom, spin-orbit interaction in core and valence, and non quadratic terms in the total energy expansion with respect to fractional occupation numbers. It is tested on two benchmark systems, Zn and Cu metals, leading in both cases to L23M45M45 Auger peaks within 2 eV from the experimental ones. Detailed analysis is presented on the relative weight of the various contributions considered in our method, providing the basis for future development. Especially problematic is the evaluation of the hole-hole interaction for systems with broad valence bands: our method underestimates its value in Cu, while we obtain excellent results for this quantity in Zn.
Auger decay of molecular double core-hole state  [PDF]
Motomichi Tashiro,Kiyoshi Ueda,Masahiro Ehara
Physics , 2011, DOI: 10.1063/1.3651082
Abstract: We report on theoretical Auger electron kinetic energy distribution originated from sequential two-step Auger decays of molecular double core-hole (DCH) state, using CH4, NH3 and H2CO molecules as representative examples. For CH4 and NH3 molecules, the DCH state has an empty 1s inner-shell orbital and its Auger spectrum has two well separated components. One is originated from the 1st Auger transition from the DCH state to the triply ionized states with one core hole and two valence holes (CVV states) and the other is originated from the 2nd Auger transition from the CVV states to quadruply valence ionized (VVVV) states. Our result on the NH3 Auger spectrum is consistent with the experimental spectrum of the DCH Auger decay observed recently [Phys. Rev. Lett. 105, 213005 (2010)]. In contrast to CH4 and NH3 molecules, H2CO has four different DCH states with C1s^{-2}, O1s^{-2} and C1s^{-1}O1s^{-1} (singlet and triplet) configurations, and its Auger spectrum has more complicated structure compared to the Auger spectra of CH4 and NH3 molecules. In the H2CO Auger spectra, the C1s^{-1}O1s^{-1} DCH -> CVV Auger spectrum and the CVV -> VVVV Auger spectrum overlap each other, which suggests that isolation of these Auger components may be difficult in experiment. The C1s^{-2} and O1s^{-2} DCH -> CVV Auger components are separated from the other components in the H2CO Auger spectra, and can be observed in experiment. Two-dimensional Auger spectrum, representing a probability of finding two Auger electrons at specific pair of energies, may be obtained by four-electron coincidence detection technique in experiment. Our calculation shows that this two-dimensional spectrum is useful in understanding contributions of CVV and VVVV states to the Auger decay of molecular DCH states.
Auger spectroscopy of strongly correlated systems: present status and future trends  [PDF]
Claudio Verdozzi,Michele Cini,Andrea Marini
Physics , 2000,
Abstract: We review the Cini-Sawatzky approach to the line shape analysis of Auger CVV transitions, in its basic and original formulation. Then, several extensions of the theory are reviewed, namely the inclusion spin-orbit coupling, dynamical/plasmon screening, overlap effects, off-site interactions, the treatment of disorder and the formulation for partially filled bands. We conclude by highlighting what we consider to be future directions in the field.
Effects of Core-Hole Screening on Spin-Polarised Auger Spectra from Ferromagnetic Nickel  [PDF]
T. Wegner,M. Potthoff,W. Nolting
Physics , 1999,
Abstract: We calculate the spin- and temperature-dependent local density of states for ferromagnetic Ni in the presence of a core hole at a distinguished site in the lattice. Correlations among the valence electrons and between valence and core electrons are described within a multi-band Hubbard model which is treated by means of second-order perturbation theory around the Hartree-Fock solution. The core-hole potential causes strong screening effects in the Ni valence band. The local magnetic moment is found to be decreased by a factor 5-6. The consequences for the spin polarisation of CVV Auger electrons are discussed.
Theory of Spin-Resolved Auger-Electron Spectroscopy from Ferromagnetic 3d-Transition Metals  [PDF]
T. Wegner,M. Potthoff,W. Nolting
Physics , 1999, DOI: 10.1103/PhysRevB.61.1386
Abstract: CVV Auger electron spectra are calculated for a multi-band Hubbard model including correlations among the valence electrons as well as correlations between core and valence electrons. The interest is focused on the ferromagnetic 3d-transition metals. The Auger line shape is calculated from a three-particle Green function. A realistic one-particle input is taken from tight-binding band-structure calculations. Within a diagrammatic approach we can distinguish between the \textit{direct} correlations among those electrons participating in the Auger process and the \textit{indirect} correlations in the rest system. The indirect correlations are treated within second-order perturbation theory for the self-energy. The direct correlations are treated using the valence-valence ladder approximation and the first-order perturbation theory with respect to valence-valence and core-valence interactions. The theory is evaluated numerically for ferromagnetic Ni. We discuss the spin-resolved quasi-particle band structure and the Auger spectra and investigate the influence of the core hole.
Programa CVV: preven o do suicídio no contexto das hotlines e do voluntariado
Dockhorn, Carolina Neumann de Barros Falc?o,Werlang, Blanca Susana Guevara
Textos & Contextos (Porto Alegre) , 2008,
Abstract: O comportamento suicida vem ganhando destaque em termos numéricos, constituindo um problema de saúde pública. Diante desta realidade, s o fundamentais a es preventivas com o objetivo de reduzir os alarmantes índices de tentativas de suicídio e de suicídios consumados. Dentre os programas de preven o, existe o recurso de atendimento por meio de hotlines, o qual se faz presente no Brasil através da a o dos Postos CVV, executores do Programa CVV de Preven o do Suicídio e integrantes do Centro de Valoriza o da Vida. Com trabalhadores voluntários, o CVV oferece interven o em crise a sujeitos que telefonam buscando apoio emocional. O objetivo deste artigo é contextualizar historicamente este tipo de servi o, destacando a a o do voluntário como pe a fundamental na sociedade civil, no cuidado efetivo a pessoas em sofrimento e no esfor o para evitar a concretiza o de um desfecho fatal.
Isolation and characterization of a virus (CvV-BW1) that infects symbiotic algae of Paramecium bursaria in Lake Biwa, Japan
Ryo Hoshina, Mayumi Shimizu, Yoichi Makino, Yoshihiro Haruyama, Shin-ichiro Ueda, Yutaka Kato, Masahiro Kasahara, Bun-ichiro Ono, Nobutaka Imamura
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-222
Abstract: CvV-BW1 formed small plaques and had a linear DNA genome of 370 kb, as judged by pulsed-field gel electrophoresis. Restriction analysis indicated that CvV-BW1 DNA belongs to group H, one of the most resistant groups among CvV DNAs. Based on a phylogenetic tree constructed using the dnapol gene, CvV was classified into two clades, A and B. CvV-BW1 belonged to clade B, in contrast to all previously identified virus strains of group H that belonged to clade A.We conclude that CvV-BW1 composes a distinct species within C. variabilis virus.Chlorella virus that infects Chlorella-like algae symbiotic with coelenterate Hydra viridis was first discovered in 1981 and designated HVCV (Hydra viridis Chlorella virus) [1]. Subsequently, another Chlorella virus that infects Chlorella-like algae symbiotic with ciliate Paramecium bursaria was described (Paramecium bursaria Chlorella virus [PBCV]) [2]. Studies on HVCV and PBCV have revealed strong host-parasite relationships [[3] and references therein]: HVCVs do not infect P. bursaria symbionts, whereas PBCVs do not infect hydra symbionts; PBCVs collected in the United States infect algal strain NC64A (representative of U.S. P. bursaria symbionts) and other U.S. P. bursaria symbionts, but they do not infect algal strain Pbi (representative of German P. bursaria symbionts) or other European P. bursaria symbionts; PBCVs collected in Europe infect European P. bursaria symbionts but do not infect U.S. P. bursaria symbionts (Fig. 1). Later, another group of viruses that infect Chlorella-like algae symbiotic with heliozoon, Acanthocystis turfacea was described [4]. Chlorella viruses studied to date, therefore, can be divided into four categories: HVCV, NC64A virus, Pbi virus, and ATCV (Acanthocystis turfacea Chlorella virus). Furthermore, none of the Chlorella viruses infect free-living green algae, and NC64A viruses exhibit a degree of diversification with regard to, for example, plaque size, hyaluronan productivity, and DNA methylation
Monte Carlo simulation based on dynamic disorder model in organic semiconductors: From bandlike to hopping transport  [PDF]
Yao Yao,Wei Si,Xiaoyuan Hou,Chang-Qin Wu
Physics , 2011, DOI: 10.1063/1.4729310
Abstract: The dynamic disorder model for charge carrier transport in organic semiconductors has been extensively studied in recent years. Although it is successful on determining the value of bandlike mobility in the organic crystalline materials, the incoherent hopping, the typical transport characteristic in organic semiconductors, cannot be described. In this work, the decoherence process is taken into account via a phenomenological parameter, say decoherence time, and the projective and Monte Carlo method is applied for this model to determine the waiting time and thus the diffusion coefficient. We find the type of transport changes from bandlike to incoherent hopping with a sufficiently short decoherence time, which indicates the essential role of decoherence time in determining the type of transport in organics. We have also discussed the spatial extent of carriers for different decoherence time, and the transition from delocalization (carrier resides in about 10 molecules) to localization is observed. Based on the experimental results of spatial extent, we estimate the decoherence time in pentacene has the order of 1ps. Furthermore, the dependence of diffusion coefficient on decoherence time is also investigated, and corresponding experiments are discussed.
The Pierre Auger Project and Enhancements  [PDF]
A. Etchegoyen,U. Fr?hlich,A. Lucero,I. Sidelnik,B. Wundheiler for the Pierre Auger Collaboration
Physics , 2010, DOI: 10.1063/1.3480148
Abstract: The current status of the scientific results of the Auger Observatory will be discussed which include spectrum, anisotropy in arrival directions, chemical composition analyses, and limits on neutrino and photon fluxes. A review of the Observatory detection systems will be presented. Auger has started the construction of its second phase which encompasses antennae for radio detection of cosmic rays, high-elevation telescopes, and surface plus muon detectors. Details will be presented on the latter, AMIGA (Auger Muons and Infill for the Ground Array), an Auger project consisting of 85 detector pairs each one composed of a surface water-Cherenkov detector and a buried muon counter. The detector pairs are arranged in an array with spacings of 433 and 750 m in order to perform a detailed study of the 10^17 eV to 10^19 eV spectrum region. Preliminary results on the performance of the 750 m array of surface detectors and the first muon counter prototype will be presented.
Marked Subchondral Bandlike Osteopenia on Radiography after Trauma and Inactivity: A Report of four Cases  [PDF]
J. Gossner,B. W. Raab,J. Larsen,S. Breitkreuz
Case Reports in Orthopedics , 2013, DOI: 10.1155/2013/234278
Abstract: We report about four cases of marked subchondral osteopenia on followup radiography after trauma and prolonged disuse. This localized form of disuse osteopenia has not been reported in details beside the followup imaging of talar neck fractures, where it is known as the “Hawkins sign.” Due to its unique morphology, it can be easily recognized as a benign finding in posttraumatic followup imaging and can be morphologically distinguished from severe complications like complex regional pain syndrome type 1 (Sudeck's disease) or periarticular osteopenia in infectious arthritis. It is important for the radiologist and orthopaedic surgeon to be aware of this form of disuse osteopenia in the proper clinical context. 1. Introduction Subchondral bandlike osteopenia of the talus has been described after talus fracture and is known as the “Hawkins sign” [1]. It is a form of localized disuse osteopenia and develops about 6–8 weeks after trauma if vascular supply is intact [2]. Beside the followup after talus fracture this form of reactive osteopenia has received little attention. We observed marked subchondral osteopenia in the followup after trauma in 4 patients and would like to highlight this finding and to discuss pathogenesis and differential diagnosis to other diseases with focal osteopenia, especially complex regional pain syndrom (CRPS) type 1, partial transient osteoporosis or infectious arthritis. 2. Case Presentations Case??1. In a 16-year-old patient, a scaphoid fracture was treated with internal screw fixation. After a short time of splinting, the patient was adviced to reconvene usage. On followup radiography about 12 weeks after operation of the wrist, subchondral bandlike lucencies could be seen on all carpal bones. The cortex of the bones was intact (Figure 1). He reported reduced activity with the operated wrist. Clinical course was unremarkable, especially that there were no clinical or laboratory signs of infection or CPRS type 1. Figure 1: AP-radiograph of a 16-year-old patient in the follow up after screw fixation of a scaphoid fracture showing bandlike subchondral osteoporosis in all carpal bones. Case??2. A 12-year-old patient presented at our emergency department with complaints of chronic instability of the ankle following a sprain. Because of the pain, she had reduced her normal activities. On the first radiograph no pathology could be seen. As in our first case, the clinical findings were unremarkable and especially, that no signs of inflammation were notable. On the followup radiographs, about 8 months after the first presentation, a
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