397 research outputs found

    New calculation of atmospheric neutrino fluxes

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    We have performed a one-dimensional Monte Carlo calculation of atmospheric neutrino fluxes in the energy range 0.05 GeV–20 GeV including muon polarization effects. It is shown that the calculated n m On e ratio does not appear sufficient to explain the Kamiokande data from sub-GeV to multi-GeV energy region. It is suggested that neutrino oscillations would provide a solution to the anomalous n m On e ratio

    An autopsy report on multiple system atrophy diagnosed immunohistochemically despite severe ischaemic damage: a new approach for investigation of medical practice associated deaths in Japan

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    A 60-year old man with a 10-year history of multiple system atrophy (MSA) was found in respiratory arrest. After 4 months of respiratory support with two episodes of septic shock, he died. Autopsy disclosed severe atrophy of the mesencephalon, brainstem, medulla oblongata and cerebellum. Gallyas–Braak, α-synuclein and ubiquitin-positive inclusions in the cytoplasm of glial cells were evident, despite the severe ischaemic damage due to respiratory arrest and subsequent respiratory support for 4 months. The cause of respiratory arrest was not identified, but could be explained by the natural history of MSA. The bereaved family, who had suspected malpractice, was satisfied with the explanation based on the investigation performed by eight expert doctors, one expert nurse, two coordinator nurses and two lawyers in the model project promoted by the Japanese government

    Aharonov-Bohm Effect for Parallel and T-shaped Double Quantum Dots

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    We investigate the Aharonov-Bohm (AB) effect for the double quantum dots in the Kondo regime using the slave-boson mean-field approximation. In contrast to the non-interacting case, where the AB oscillation generally has the period of 4π\pi when the two-subring structure is formed via the interdot tunneling tct_c, we find that the AB oscillation has the period of 2π\pi in the Kondo regime. Such effects appear for the double quantum dots close to the T-shaped geometry even in the charge-fluctuation regime. These results follow from the fact that the Kondo resonance is always fixed to the Fermi level irrespective of the detailed structure of the bare dot-levels.Comment: 3 pages, 4 figures; minor change

    Structural Phase Transition Accompanied by Metal - Insulator Transition in PrRu4P12

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    A structural phase transition has been found using electron diffraction technique in PrRu4P12 accompanied by a metal - insulator (M - I) transition (TMI = 60K). Weak superlattice spots appeared at (H, K, L) (H + K + L = 2n + 1; n is an integer) position at a temperature of T = 12 K and 40 K. Above T = 70 K, the spots completely vanished. The space group of the low temperature phase is probably Pm3. This is the first observation of a symmetry other than Im3 in skutterudite compounds.Comment: 7 pages, 2 figures; J. Phys.: Condens. Matter (in press

    The degeneration and destruction of femoral articular cartilage shows a greater degree of deterioration than that of the tibial and patellar articular cartilage in early stage knee osteoarthritis: a cross-sectional study

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    SummaryObjectiveThe aim of the present study was to examine whether the degenerative and morphological changes of articular cartilage in early stage knee osteoarthritis (OA) occurred equally for both femoral- and tibial- or patellar- articular cartilage using magnetic resonance imaging (MRI)-based analyses.DesignThis cross-sectional study was approved by the ethics committee of our university. Fifty patients with early stage painful knee OA were enrolled. The patients underwent 3.0 T MRI on the affected knee joint. Healthy volunteers who did not show MRI-based OA changes were also recruited as controls (n = 19). The degenerative changes of the articular cartilage were quantified by a T2 mapping analysis, and any structural changes were conducted using Whole Organ Magnetic Resonance Imaging Score (WORMS) technique.ResultsAll patients showed MRI-detected OA morphological changes. The T2 values of femoral condyle (FC) (P < 0.0001) and groove (P = 0.0001) in patients with early stage knee OA were significantly increased in comparison to those in the control, while no significant differences in the T2 values of patellar and tibial plateau (TP) were observed between the patients and the control. The WORMS cartilage and osteophyte scores of the femoral articular cartilage were significantly higher than those in the patellar- (P = 0.001 and P = 0.007, respectively) and tibial- (P = 0.0001 and P < 0.0001, respectively) articular cartilage in the patients with early stage knee OA.ConclusionsThe degradation and destruction of the femoral articular cartilage demonstrated a greater degree of deterioration than those of the tibial- and patellar- articular cartilage in patients with early stage knee OA

    Scientific Drilling and Related Research in the Samail Ophiolite, Sultanate of Oman

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    This workshop report describes plans for scientific drilling in the Samail ophiolite in Oman in the context of past, current, and future research. Long-standing plans to study formation and evolution of the Samail crust and upper mantle, involving igneous and metamorphic processes at an oceanic spreading center, have been augmented by recent interest in ongoing, low temperature processes. These include alteration and weathering, and the associated sub-surface biosphere supported by chemical potential energy due to disequilibrium between mantle peridotite and water near the surface. This interest is motivated in part by the possibility of geological carbon capture and storage via engineered, accelerated mineral carbonation in Oman

    Resonance Kondo Tunneling through a Double Quantum Dot at Finite Bias

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    It is shown that the resonance Kondo tunneling through a double quantum dot (DQD) with even occupation and singlet ground state may arise at a strong bias, which compensates the energy of singlet/triplet excitation. Using the renormalization group technique we derive scaling equations and calculate the differential conductance as a function of an auxiliary dc-bias for parallel DQD described by SO(4) symmetry. We analyze the decoherence effects associated with the triplet/singlet relaxation in DQD and discuss the shape of differential conductance line as a function of dc-bias and temperature.Comment: 11 pages, 6 eps figures include

    Kondo effect in systems with dynamical symmetries

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    This paper is devoted to a systematic exposure of the Kondo physics in quantum dots for which the low energy spin excitations consist of a few different spin multiplets SiMi>|S_{i}M_{i}>. Under certain conditions (to be explained below) some of the lowest energy levels ESiE_{S_{i}} are nearly degenerate. The dot in its ground state cannot then be regarded as a simple quantum top in the sense that beside its spin operator other dot (vector) operators Rn{\bf R}_{n} are needed (in order to fully determine its quantum states), which have non-zero matrix elements between states of different spin multiplets 0 \ne 0. These "Runge-Lenz" operators do not appear in the isolated dot-Hamiltonian (so in some sense they are "hidden"). Yet, they are exposed when tunneling between dot and leads is switched on. The effective spin Hamiltonian which couples the metallic electron spin s{\bf s} with the operators of the dot then contains new exchange terms, JnsRnJ_{n} {\bf s} \cdot {\bf R}_{n} beside the ubiquitous ones JisSiJ_{i} {\bf s}\cdot {\bf S}_{i}. The operators Si{\bf S}_{i} and Rn{\bf R}_{n} generate a dynamical group (usually SO(n)). Remarkably, the value of nn can be controlled by gate voltages, indicating that abstract concepts such as dynamical symmetry groups are experimentally realizable. Moreover, when an external magnetic field is applied then, under favorable circumstances, the exchange interaction involves solely the Runge-Lenz operators Rn{\bf R}_{n} and the corresponding dynamical symmetry group is SU(n). For example, the celebrated group SU(3) is realized in triple quantum dot with four electrons.Comment: 24 two-column page
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