1,884 research outputs found

    Influence of s-d scattering on the electron density of states in ferromagnet/superconductor bilayer

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    We study the dependence of the electronic density of states (DOS) on the distance from the boundary for a ferromagnet/superconductor bilayer. We calculate the electron density of states in such structure taking into account the two-band model of the ferromagnet (FM) with conducting s and localized d electrons and a simple s-wave superconductor (SC). It is demonstrated that due to the electron s-d scattering in the ferromagnetic layer in the third order of s-d scattering parameter the oscillation of the density of states has larger period and more drastic decrease in comparison with the oscillation period for the electron density of states in the zero order.Comment: 5 pages, 3 figure

    Shot noise in carbon nanotube based Fabry-Perot interferometers

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    We report on shot noise measurements in carbon nanotube based Fabry-Perot electronic interferometers. As a consequence of quantum interferences, the noise power spectral density oscillates as a function of the voltage applied to the gate electrode. The quantum shot noise theory accounts for the data quantitatively. It allows to confirm the existence of two nearly degenerate orbitals. At resonance, the transmission of the nanotube approaches unity, and the nanotube becomes noiseless, as observed in quantum point contacts. In this weak backscattering regime, the dependence of the noise on the backscattering current is found weaker than expected, pointing either to electron-electron interactions or to weak decoherence

    Congenital erythropoietic porphyria associated with myelodysplasia presenting in a 72-year-old man: report of a case and review of the literature

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    Congenital erythropoietic porphyria (CEP) is a rare autosomal recessive disease owing to the deficient activity of uroporphyrinogen III synthase, the fourth enzyme in the porphyrin–haem synthetic pathway. Of the porphyrias, it is the most mutilating type, usually presenting early in life. To date, 12 documented cases of adult onset CEP have been reported. We report the second oldest documented patient with late onset CEP with incidental findings of thrombocytopenia and myelodysplasia with bone-marrow sideroblasts. We further discuss several current and future treatment options for this therapeutically challenging disease.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73760/1/j.1365-2133.2003.05040.x.pd

    Conserved spin and orbital phase along carbon nanotubes connected with multiple ferromagnetic contacts

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    We report on spin dependent transport measurements in carbon nanotubes based multi-terminal circuits. We observe a gate-controlled spin signal in non-local voltages and an anomalous conductance spin signal, which reveal that both the spin and the orbital phase can be conserved along carbon nanotubes with multiple ferromagnetic contacts. This paves the way for spintronics devices exploiting both these quantum mechanical degrees of freedom on the same footing.Comment: 8 pages - minor differences with published versio

    Magnetic properties of Ruddlesden-Popper phases Sr3x_{3-x}Yx_{x}(Fe1.25_{1.25}Ni0.75_{0.75})O7δ_{7-\delta}: A combined experimental and theoretical investigation

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    We present a comprehensive study of the magnetic properties of Sr3x_{3-x}Yx_{x}(Fe1.25_{1.25}Ni0.75_{0.75})O7δ_{7-\delta} (0x0.750 \leq x \leq 0.75). Experimentally, the magnetic properties are investigated using superconducting quantum interference device (SQUID) magnetometry and neutron powder diffraction (NPD). This is complemented by the theoretical study based on density functional theory as well as the Heisenberg exchange parameters. Experimental results show an increase in the N\'eel temperature (TNT_N) with the increase of Y concentrations and O occupancy. The NPD data reveals all samples are antiferromagnetically ordered at low temperatures, which has been confirmed by our theoretical simulations for the selected samples. Our first-principles calculations suggest that the 3D magnetic order is stabilized due to finite inter-layer exchange couplings. The latter give rise to a finite inter-layer spin correlations which disappear above the TNT_N

    Adenoid cystic carcinoma intermingled with ductal carcinoma of the breast: a case report and review of the literature

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    <p>Abstract</p> <p>Introduction</p> <p>Adenoid cystic cancer of the breast is a rare condition, and even rarer are the cases where it is histologically mixed with other variants of cancer within a single lesion. In this report, one of the few cases of mixed adenoid cystic breast cancer intermingled with the infiltrating ductal variant is presented. A subsequent review of the relevant literature presents the existing experience in treating mixed breast cancers with adenoid cystic components with regard to diagnosis, treatment, and prognosis.</p> <p>Case presentation</p> <p>We describe a case of mixed adenoid cystic cancer of the breast with infiltrating ductal carcinoma in a 67-year-old Caucasian woman who underwent mastectomy with sentinel node biopsy.</p> <p>Conclusion</p> <p>Surgery remains the cornerstone of treatment of these patients, and radiotherapy is administered when breast-conserving treatment is undertaken or a large tumor with affected lymph nodes is present. Hormonal treatment does not have a role, as estrogen receptors are always absent from both tumor components. Chemotherapy is nearly always administered on the basis of estrogen receptor and progesterone negativity and the more aggressive potential of the non-adenoid cystic component. The de-differentiation of an indolent type of cancer to a more aggressive one may affect the prognosis.</p

    Experimental cross sections of Ho 165 (α,n) Tm 168 and Er 166 (α,n) Yb 169 for optical potential studies relevant for the astrophysical γ process

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    Background: Optical potentials are crucial ingredients for the prediction of nuclear reaction rates needed in simulations of the astrophysical γ process. Associated uncertainties are particularly large for reactions involving α particles. This includes (γ,α) reactions which are of special importance in the γ process. Purpose: The measurement of (α,n) reactions allows for an optimization of currently used α-nucleus potentials. The reactions Ho165(α,n) and Er166(α,n) probe the optical model in a mass region where γ process calculations exhibit an underproduction of p nuclei which is not yet understood. Method: To investigate the energy-dependent cross sections of the reactions Ho165(α,n) and Er166(α,n) close to the reaction threshold, self-supporting metallic foils were irradiated with α particles using the FN tandem Van de Graaff accelerator at the University of Notre Dame. The induced activity was determined afterwards by monitoring the specific β-decay channels. Results: Hauser-Feshbach predictions with a widely used global α potential describe the data well at energies where the cross sections are almost exclusively sensitive to the α widths. Increasing discrepancies appear towards the reaction threshold at lower energy. Conclusions: The tested global α potential is suitable at energies above 14 MeV, while a modification seems necessary close to the reaction threshold. Since the γ and neutron widths show non-negligible impact on the predictions, complementary data are required to judge whether or not the discrepancies found can be solely assigned to the α width. © 2014 American Physical Society.Peer reviewedFinal Accepted Versio
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