188 research outputs found

    Primary ovarian leiomyoma in a postmenopausal woman: a case report

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    Ovarian leiomyoma is a benign primary smooth muscle tumor. It is a small solid tumor commonly occurring in premenopausal women. Here we present a case of large ovarian leiomyoma in a postmenopausal woman

    Teacher professional learning communities : a participatory resource creation approach to OER in Karnataka

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    The presentation focuses on research in open educational resources: the techno-social context such as ICT infrastructure; the pedagogical context as in teacher development; and socio-cultural context (building community), and how these are affected by teacher participation in, and creation of OER. It reviews a survey of teachers in Karnataka (India). The use of digital methods in OER adoption helped teachers to create resources in different formats, using different editors and tools learnt in the workshops, and also to share with peers over mailing lists. OER should be made available in local languages to be contextually relevant

    Studies on the biology of the dog-whelk Nassastolata (Gmelin) of Portonovo waters

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    The morphology, anatomy and sex ratio of the mud snail Nassa stolata (Gmelin) were studied. The species, being a facultative omnivore. feeds mainly on dead animals and the digestive system is suited to this mode of feeding. The radula is of rachiglossate type and is well suited for tearing and rasping. The female reproductive system is more complicated than that of male- Studies on sex ratio clearly show the preponderance of males over females. The males mature at a size of 12.1 mm female at 12.5 mm

    Electronic and Thermoelectric Properties of RuIn_{3-x}A_{x} (A = Sn, Zn)

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    Recently, we reported [M. Wagner et al., J. Mater. Res. 26, 1886 (2011)] transport measurements on the semiconducting intermetallic system RuIn3 and its substitution derivatives RuIn_{3-x}A_{x} (A = Sn, Zn). Higher values of the thermoelectric figure of merit (zT = 0.45) compared to the parent compound were achieved by chemical substitution. Here, using density functional theory based calculations, we report on the microscopic picture behind the measured phenomenon. We show in detail that the electronic structure of the substitution variants of the intermetallic system RuIn_{3-x}A_{x} (A = Sn, Zn) changes in a rigid-band like fashion. This behavior makes possible the fine tuning of the substitution concentration to take advantage of the sharp peak-like features in the density of states of the semiconducting parent compound. Trends in the transport properties calculated using the semi-classical Boltzmann transport equations within the constant scattering time approximation are in good agreement with the former experimental results for RuIn_{3-x}Sn_{x}. Based on the calculated thermopower for the p-doped systems, we reinvestigated the Zn-substituted derivative and obtained ZnO-free RuIn_{3-x}Zn_{x}. The new experimental results are consistent with the calculated trend in thermopower and yield large zT value of 0.8.Comment: PRB Accepted, 11 pages, 10 figure

    Interplay between superconductivity and magnetism in K-doped EuFe2As2

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    Superconductivity is found in 50% K-doped EuFe2As2 sample below 33 K. Our results of electrical resistivity, magnetic susceptibility and 57Fe and 151Eu Mossbauer spectroscopy provide clear evidence that the ordering of the Fe moments observed at 190 K in undoped EuFe2As2 is completely suppressed in our 50% K doped sample, thus there is no coexistence between the Fe magnetic order and the superconducting state. However, short range ordering of the Eu moments is coexisting with the superconducting state below 15 K. A bump in the susceptibility well below Tc as well as a slight broadening of the Fe Mossbauer line below 15 K evidence an interplay between the Eu magnetism and the superconducting state.Comment: 7 pages, 6 figure

    Electronic signature of the vacancy ordering in NbO (Nb3O3)

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    We investigated the electronic structure of the vacancy-ordered 4d-transition metal monoxide NbO (Nb3O3) using angle-integrated soft- and hard-x-ray photoelectron spectroscopy as well as ultra-violet angle-resolved photoelectron spectroscopy. We found that density-functional-based band structure calculations can describe the spectral features accurately provided that self-interaction effects are taken into account. In the angle-resolved spectra we were able to identify the so-called vacancy band that characterizes the ordering of the vacancies. This together with the band structure results indicates the important role of the very large inter-Nb-4d hybridization for the formation of the ordered vacancies and the high thermal stability of the ordered structure of niobium monoxide

    Magnetic Lattice Dynamics of the Oxygen-Free FeAs Pnictides: How Sensitive are Phonons to Magnetic Ordering?

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    To shed light on the role of magnetism on the superconducting mechanism of the oxygen-free FeAs pnictides, we investigate the effect of magnetic ordering on phonon dynamics in the low-temperature orthorhombic parent compounds, which present a spin-density wave. The study covers both the 122 (AFe2As2; A=Ca, Sr, Ba) and 1111 (AFeAsF; A=Ca, Sr) phases. We extend our recent work on the Ca (122 and 1111) and Ba (122) cases by treating computationally and experimentally the 122 and 1111 Sr compounds. The effect of magnetic ordering is investigated through detailed non-magnetic and magnetic lattice dynamical calculations. The comparison of the experimental and calculated phonon spectra shows that the magnetic interactions/ordering have to be included in order to reproduce well the measured density of states. This highlights a spin-correlated phonon behavior which is more pronounced than the apparently weak electron-phonon coupling estimated in these materials. Furthermore, there is no noticeable difference between phonon spectra of the 122 Ba and Sr, whereas there are substantial differences when comparing these to CaFe2As2 originating from different aspects of structure and bonding

    Quantum Confinement

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    Quantum confinement is the spatial confinement of electron–hole pairs (excitons) in one or more dimensions within a material, and also electronic energy levels are discrete. It is due to the confinement of the electronic wave function to the physical dimensions of the particles. In this effect can be divided into three ways, 1D confinement (free carrier in a plane), quantum wells; 2D confinement (carriers are free to move down), quantum wire; and 3D confinement (carriers are confined in all directions), which are discussed in details. In addition the formation mechanism of exciton and quantum confinement behavior of strong, moderate, and weak confinement have been discussed below.MHRD-SPARC (ID: 890/2019) & UKIERI by the Governments of India and UK

    Effect of hybridization on structural and magnetic properties of iron-based superconductors

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    We show that the strong hybridization between the iron 3d and the arsenic 4p orbitals, in the newly discovered iron-based high-Tc_{c} superconductors, leads to an explanation of certain experimental observations that are presently not well understood. The existence of a lattice distortion, the smallness of the Fe magnetic moment in the undoped systems, and the suppression of both the lattice distortion and the magnetic order upon doping with fluorine, are all shown to result from this hybridization.Comment: 4 pages, 2 figure
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