1,763 research outputs found

    Luminescence spectroscopy of matrix-isolated z 6P state atomic manganese

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    The relaxation of electronically excited atomic manganese isolated in solid rare gas matrices is observed from recorded emission spectra, to be strongly site specific. z 6P state excitation of Mn atoms isolated in the red absorption site in Ar and Kr produces narrow a 4D and a 6D state emissions while blue-site excitation produces z 6P state fluorescence and broadened a 4D and a 6D emissions. Mn/Xe exhibits only a single thermally stable site whose emission at 620 nm is similar to the broad a 6D bands produced with blue-site excitation in Ar and Kr. Thus in ArsKrd, excitation of the red site at 393 s400d nm produces narrow line emissions at 427.5 s427.8d and 590 s585.7d nm. From their spectral positions, linewidths, and long decay times, these emission bands are assigned to the a 4D7/2 and a 6D9/2 states, respectively. Excitation of the blue site at 380 s385.5d nm produces broad emission at 413 s416d nm which, because of its nanosecond radiative lifetime, is assigned to resonance z 6P!a 6S fluorescence. Emission bands at 438 s440d and 625 s626.8d nm, also produced with blue-site excitation, are broader than their red-site equivalents at 427.5 and 590 nm s427.8 and 585.7 nm in Krd but from their millisecond and microsecond decay times are assigned to the a 4D and a 6D states. The line features observed in high resolution scans of the red-site emission at 427.5 and 427.8 nm in Mn/Ar and Mn/ Kr, respectively, have been analyzed with the Wp optical line shape function and identified as resolved phonon structure originating from very weak sS=0.4d electron-phonon coupling. The presence of considerable hot-phonon emission seven in 12 K spectrad and the existence of crystal field splittings of 35 and 45 cmâ1 on the excited a 4D7/2 level in Ar and Kr matrices have been identified in Wp line shape fits. The measured matrix lifetimes for the narrow red-site a 6D state emissions s0.29 and 0.65 msd in Ar and Kr are much shorter than the calculated s3 sd gas phase value. With the lifetime of the metastable a 6D9/2 state shortened by four orders of magnitude in the solid rare gases, it is clear that the probability of the âforbiddenâ a 6D!a 6S atomic transition is greatly enhanced in the solid state. A novel feature identified in the present work is the large width and shifted 4D and 6D emissions produced for Mn atoms isolated in the blue sites of Ar and Kr. In contrast, these states produce narrow, unshifted sgas-phase-liked 4D and 6D state emissions from the red site

    Learning to Live with the New Foreign Nongrantor Trust Rules

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    The Small Business Job Protection Act of 1996 (the 1996 Act) was intended to deal a heavy blow to the appeal of foreign trusts to U.S. persons. The results were mixed. On the one hand, the 1996 Act imposes an array of reporting requirements, imposes harsh penalties on failures to comply with these requirements, increases the interest charge imposed on taxes paid on distributions of accumulated income from foreign trusts, treats loans of cash from foreign trusts as distributions, and expands the kinds of gifts that can be treated as indirect transfers from foreign trusts. On the other hand, curiously, the 1996 Act encourages the creation of foreign trusts by its adoption of a set of criteria for foreignness that is both more objective than the criteria formerly used and more biased in favor of foreign status. This Article discusses how to create foreign trusts, examines their exposure and the exposure of their U.S. beneficiaries to U.S. income tax, and describes the reporting requirements imposed on their creators, their beneficiaries, and the trusts themselves. In addition to explaining the rules, this Article also considers the extent to which foreign trusts continue to be useful planning tools for U.S. persons

    Laser excitation spectroscopy of the A and B states of jet-cooled copper dimer: evidence for large electronic isotope shifts

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    Journal ArticleFluorescence excitation spectra recorded for the A-X system of jet-cooled Cu2 show conclusive evidence of a ?? = 0 transition, and the A state is thereby definitively assigned as ??u+. A previous assignment of the B state as ??u+ is confirmed, but the vibrational levels of this state are complicated by the presence of a perturbation at v' = 0. The perturbing state does not, however, appear to be either of the two optically accessible electronic states in this spectral region. Anomalously large electronic isotope shifts are observed for the A and B states, and this behavior is discussed in terms of the correspondingly large "specific mass shifts" observed in the optical spectra of atomic copper for transitions that couple states differing in the number of d electrons. Due to the large spin-orbit coupling constants in the "cMiole" configurations, it is proposed that the low-energy-excited molecular states of Cu2 derived from these configurations should be described by Hund's case (c) coupling. Dynamical effects observed in the gas phase and in solid matrices are briefly discussed in terms of this bonding scheme

    Polymer Translocation Dynamics in the Quasi-Static Limit

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    Monte Carlo (MC) simulations are used to study the dynamics of polymer translocation through a nanopore in the limit where the translocation rate is sufficiently slow that the polymer maintains a state of conformational quasi-equilibrium. The system is modeled as a flexible hard-sphere chain that translocates through a cylindrical hole in a hard flat wall. In some calculations, the nanopore is connected at one end to a spherical cavity. Translocation times are measured directly using MC dynamics simulations. For sufficiently narrow pores, translocation is sufficiently slow that the mean translocation time scales with polymer length N according to \propto (N-N_p)^2, where N_p is the average number of monomers in the nanopore; this scaling is an indication of a quasi-static regime in which polymer-nanopore friction dominates. We use a multiple-histogram method to calculate the variation of the free energy with Q, a coordinate used to quantify the degree of translocation. The free energy functions are used with the Fokker-Planck formalism to calculate translocation time distributions in the quasi-static regime. These calculations also require a friction coefficient, characterized by a quantity N_{eff}, the effective number of monomers whose dynamics are affected by the confinement of the nanopore. This was determined by fixing the mean of the theoretical distribution to that of the distribution obtained from MC dynamics simulations. The theoretical distributions are in excellent quantitative agreement with the distributions obtained directly by the MC dynamics simulations for physically meaningful values of N_{eff}. The free energy functions for narrow-pore systems exhibit oscillations with an amplitude that is sensitive to the nanopore length. Generally, larger oscillation amplitudes correspond to longer translocation times.Comment: 13 pages, 13 figure

    Contamination of histology biopsy specimen - a potential source of error for surgeons: a case report

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    Tissue contamination is a common occurrence in pathology, but surgeons are relatively unaware of this. We present the case of a 45-year-old man with Barrett's oesophagus, in which the histology of routine biopsies of an asymptomatic patient, were reported as 'carcinoma in situ'. Further biopsies were taken over a three month period but showed no evidence of malignancy. Tissue contamination or 'cross over' was identified as the likely cause of the abnormal result. This case report highlights the importance of the correlation of the clinical and histopathological findings and tissue contamination should be considered when both of these findings are not consistent

    Analysis, Design, Implementation, and Deployment of a Prototype Maintenance Advisor Expert System for the MK92 Fire Control System

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    17 USC 105 interim-entered record; under review.In an effort to meet the challenges presented by the fiscal realities of today's defense budget, the Department of Defense (DoD) is seeking to exploit technology that promises to decrease operating costs, while improving operational readiness. Efforts which reduce repair costs, system down time, and the reliance upon outside technical representative are of particular interest. The development of the MK92 Maintenance Advisor Expert System (MK92 MAES) is one such effort. This paper describes the design and development of the MK92 MAES for the diagnosis and repair of the MK92 MOD 2 fire control system deployed on U.S. Navy guided missile frigates. System development is presented in terms of an expert system life cycle model which includes a thorough cost/benefit analysis, a novel approach for knowledge acquisition, an implementation strategy using a visual expert system development environment, and a phased deployment strategy. The system was developed by faculty and graduate students at the Naval Postgraduate School in cooperation with the Naval Warfare Center, Port Hueneme Division.The author thanks...Dean of Research Office at the Naval Postgraduate School for paying the publication cost

    Implementing Outcome-Based Quality Measures Using the MDS-HC

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    Data can be used to develop outcome-based measures to ensure the quality of home and community-based services (HCBS). Outcome-based measures are an essential but often missing puzzle piece in assuring HCBS quality, and promoting advanced payment models to include HCBS. The MDS-HC, or the Minimum Data Set Home Care, is a tool to help identify the needs of and services for older adults and people with disabilities who live in the community. Many validated outcome-based measures developed by interRAI may be constructed from the data collected in Massachusetts through the Long Term Services and Supports (LTSS) Policy Lab, a resource in partnership with Massachusetts state agencies to aid executive-level decision-makers in program planning, policy evaluation and fiscal forecasting in the LTSS arena

    The Myth of the Risk Premium

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    Present-day economists consider observable interest rates to be the arithmetic sum of a pure interest rate, a risk premium, and a price premium, each of which can be determined in separation from the others. This conception is problematic in that it is disconnected from ordinary demand-and-supply price theory. We present an alternative realist approach for the study of human action under uncertainty. This approach leads us to appreciate that, in a free-market setting, all known risks that pertain to business either tend to be eliminated through entrepreneurial activity, or are considered to be irrelevant from the point of view of the acting persons. The implication is that differences in observable interest rates cannot be explained as compensations for risk, but do result from different subjective appreciations of available investment opportunities

    Effects of trapping site on the spectroscopy of 1P1 excited group 12 metal atoms in rare gas matrices

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    A molecular dynamics deposition model has been used to simulate the growth of rare gas matrices doped with atoms of the group 12 elements zinc, cadmium and mercury. This study investigates the sites occupied by Zn, Cd and Hg metal atoms when isolated in the solid rare gases. To probe the results, the resonance 1 P 1-1 S 0 transitions of the matrix-isolated metal atoms were calculated and compared with the recorded spectra of the M/RG solids. The theoretical spectroscopy obtained in this work was generated using the molecular dynamics with quantum transitions method. In Ne matrices the metal atoms preferably occupy tetra- and hexa-vacancy sites while in the case of Xe matrices, only the single vacancy site is formed. For Ar and Kr matrices Zn but especially Cd can be trapped in tetra- and hexa-vacancy sites in addition to single-vacancy sites, while Hg atoms show exclusive occupancy in single vacancy sites.Fil: Lara Moreno, M.. Universidad de La Habana; Cuba. Instituto Superior de Tecnologías y Ciencias Aplicadas.; Cuba. Université de Bordeaux; Francia. Centre National de la Recherche Scientifique; FranciaFil: Alvarez Hernández, J.. Universidad de La Habana; Cuba. Instituto Superior de Tecnologías y Ciencias Aplicadas.; Cuba. University of Rochester. Department of Chemistry; Estados UnidosFil: Negrín Yuvero, Lázaro Hassiel. Universidad de La Habana; Cuba. Instituto Superior de Tecnologías y Ciencias Aplicadas.; Cuba. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: McCaffrey, J. G.. National University of Ireland. Maynooth University. Department of Chemistry; IrlandaFil: Rojas Lorenzo, G.. Universidad de La Habana; Cuba. Instituto Superior de Tecnologías y Ciencias Aplicadas.; Cub
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