15,173 research outputs found
Thermal activation energy of 3D vortex matter in NaFe1-xCoxAs (x=0.01, 0.03 and 0.07) single crystals
We report on the thermally activated flux flow dependency on the doping
dependent mixed state in NaFe1-xCoxAs (x=0.01, 0.03, and 0.07) crystals using
the magnetoresistivity in the case of B//c-axis and B//ab-plane. It was found
clearly that irrespective of the doping ratio, magnetoresistivity showed a
distinct tail just above the Tc, offset associated with the thermally activated
flux flow (TAFF) in our crystals. Furthermore, in TAFF region the temperature
dependence of the activation energy follows the relation U(T, B)=U_0 (B)
(1-T/T_c )^q with q=1.5 in all studied crystals. The magnetic field dependence
of the activation energy follows a power law of U_0 (B)~B^(-{\alpha}) where the
exponent {\alpha} is changed from a low value to a high value at a crossover
field of B=~2T, indicating the transition from collective to plastic pinning in
the crystals. Finally, it is suggested that the 3D vortex phase is the dominant
phase in the low-temperature region as compared to the TAFF region in our
series samples
Density functional calculations of the electronic structure and magnetic properties of the hydrocarbon K3picene superconductor near the metal-insulator transition
We have investigated the electronic structures and magnetic properties of of
K3picene, which is a first hydrocarbon superconductor with high transition
temperature T_c=18K. We have shown that the metal-insulator transition (MIT) is
driven in K3picene by 5% volume enhancement with a formation of local magnetic
moment. Active bands for superconductivity near the Fermi level E_F are found
to have hybridized character of LUMO and LUMO+1 picene molecular orbitals.
Fermi surfaces of K3picene manifest neither prominent nesting feature nor
marked two-dimensional behavior. By estimating the ratio of the Coulomb
interaction U and the band width W of the active bands near E_F, U/W, we have
demonstrated that K3picene is located in the vicinity of the Mott transition.Comment: 5 pages, 5 figure
Studies on the Density of Soybean Aphids in Different Cultivars, Planting Dates and Spacings
In order to evaluate the fluctuation of the soybean aphid (Aphis glycines Matsumura) population, six leading soybean cultivars were planted on five different planting dates with different plant densities. The survey of aphid population and climate condition was made from June through September in 1978. According to the differences of planting dates and plant density the soybean aphid populations were varied, and varietal response to the aphid was significantly different. Counting of aphid infestation on the top third trifoliate leaf seemed to be efficient for the estimation of soybean aphid population.Originating text in Korean.Citation: Chung, K. H., Kwon, S. H., Lee, Y. I. (1980). Studies on the Density of Soybean Aphids in Different Cultivars, Planting Dates and Spacings. Journal of the Korean Society for Crop Science, 25(3), 35-40
The prenylated rab GTPase receptor PRA1.F4 contributes to protein exit from the golgi apparatus
Prenylated Rab acceptor1 (PRA1) functions in the recruitment of prenylated Rab proteins to their cognate organelles. Arabidopsis (Arabidopsis thaliana) contains a large number of proteins belonging to the AtPRA1 family. However, their physiological roles remain largely unknown. Here, we investigated the physiological role of AtPRA1.F4, a member of the AtPRA1 family. A T-DNA insertion knockdown mutant of AtPRA1.F4, atpra1.f4, was smaller in stature than parent plants and possessed shorter roots, whereas transgenic plants overexpressing HA:AtPRA1.F4 showed enhanced development of secondary roots and root hairs. However, both overexpression and knockdown plants exhibited increased sensitivity to high-salt stress, lower vacuolar Na+/K+-ATPase and plasma membrane ATPase activities, lower and higher pH in the vacuole and apoplast, respectively, and highly vesiculated Golgi apparatus. HA:AtPRA1.F4 localized to the Golgi apparatus and assembled into high-molecular-weight complexes. atpra1.f4 plants displayed a defect in vacuolar trafficking, which was complemented by low but not high levels of HA:AtPRA1.F4. Overexpression of HA:AtPRA1.F4 also inhibited protein trafficking at the Golgi apparatus, albeit differentially depending on the final destination or type of protein: trafficking of vacuolar proteins, plasma membrane proteins, and trans-Golgi network (TGN)-localized SYP61 was strongly inhibited; trafficking of TGN-localized SYP51 was slightly inhibited; and trafficking of secretory proteins and TGN-localized SYP41 was negligibly or not significantly inhibited. Based on these results, we propose that Golgi-localized AtPRA1.F4 is involved in the exit of many but not all types of post-Golgi proteins from the Golgi apparatus. Additionally, an appropriate level of AtPRA1.F4 is crucial for its function at the Golgi apparatus. ? 2017 American Society of Plant Biologists. All rights reserved.111Ysciescopu
Electronic structures of doped anatase : (M=Co, Mn, Fe, Ni)
We have investigated electronic structures of a room temperature diluted
magnetic semiconductor : Co-doped anatase . We have obtained the
half-metallic ground state in the local-spin-density approximation(LSDA) but
the insulating ground state in the LSDA++SO incorporating the spin-orbit
interaction. In the stoichiometric case, the low spin state of Co is realized
with the substantially large orbital moment. However, in the presence of oxygen
vacancies near Co, the spin state of Co becomes intermediate. The
ferromagnetisms in the metallic and insulating phases are accounted for by the
double-exchange-like and the superexchange mechanism, respectively. Further,
the magnetic ground states are obtained for Mn and Fe doped ,
while the paramagnetic ground state for Ni-doped .Comment: 5 pages, 4 figure
Fractional ac Josephson effect in unconventional superconductors
For certain orientations of Josephson junctions between two p_x-wave or two
d-wave superconductors, the subgap Andreev bound states produce a 4pi-periodic
relation between the Josephson current I and the phase difference phi: I ~
sin(phi/2). Consequently, the ac Josephson current has the fractional frequency
eV/h, where V is the dc voltage. In the tunneling limit, the Josephson current
is proportional to the first power (not square) of the electron tunneling
amplitude. Thus, the Josephson current between unconventional superconductors
is carried by single electrons, rather than by Cooper pairs. The fractional ac
Josephson effect can be observed experimentally by measuring frequency spectrum
of microwave radiation from the junction.Comment: 8 pages, 3 figures, RevTEX 4; v2. - minor typos corrected in proof
Tachyon Vacuum Solution in Open String Field Theory with Constant B Field
We show that Schnabl's tachyon vacuum solution is an exact solution of the
equation of motion of Witten's open bosonic string field theory in the
background of constant antisymmetric two-form field. The action computed at the
vacuum solution is given by the Dirac-Born-Infeld factor multiplied to that
without the antisymmetric tensor field.Comment: 8 page
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