746 research outputs found
Secure Grouping Protocol Using a Deck of Cards
We consider a problem, which we call secure grouping, of dividing a number of
parties into some subsets (groups) in the following manner: Each party has to
know the other members of his/her group, while he/she may not know anything
about how the remaining parties are divided (except for certain public
predetermined constraints, such as the number of parties in each group). In
this paper, we construct an information-theoretically secure protocol using a
deck of physical cards to solve the problem, which is jointly executable by the
parties themselves without a trusted third party. Despite the non-triviality
and the potential usefulness of the secure grouping, our proposed protocol is
fairly simple to describe and execute. Our protocol is based on algebraic
properties of conjugate permutations. A key ingredient of our protocol is our
new techniques to apply multiplication and inverse operations to hidden
permutations (i.e., those encoded by using face-down cards), which would be of
independent interest and would have various potential applications
Extreme ion heating in the dayside ionosphere in response to the arrival of a coronal mass ejection on 12 March 2012
Simultaneous measurements of the polar ionosphere with the European Incoherent Scatter (EISCAT) ultra high frequency (UHF) radar
at Tromsø and the EISCAT Svalbard radar (ESR) at Longyearbyen were made
during 07:00–12:00 UT on 12 March 2012. During the period, the Advanced Composition Explorer (ACE) spacecraft
observed changes in the solar wind which were due to the arrival of
coronal mass ejection (CME) effects associated with the 10 March M8.4 X-ray
event. The solar wind showed two-step variations which caused strong
ionospheric heating. First, the arrival of shock structures in the solar wind
with enhancements of density and velocity, and a negative interplanetary magnetic field (IMF)-<i>B<sub>z</sub></i> component
caused strong ionospheric heating around Longyearbyen; the ion temperature at
about 300 km increased from about 1100 to 3400 K over Longyearbyen while
that over Tromsø increased from about 1050 to 1200 K. After the passage
of the shock structures, the IMF-<i>B<sub>z</sub></i> component showed positive values and
the solar wind speed and density also decreased. The second strong
ionospheric heating occurred after the IMF-<i>B<sub>z</sub></i> component showed
negative values again; the negative values lasted for more than
1.5 h. This solar wind variation caused stronger heating of the ionosphere in
the lower latitudes than higher latitudes, suggesting expansion of the auroral
oval/heating region to the lower latitude region. This study shows an example
of the CME-induced dayside ionospheric heating: a short-duration and very large rise in the ion temperature which was closely related to the polar
cap size and polar cap potential variations as a result of interaction
between the solar wind and the magnetosphere
The Fulde-Ferrell-Larkin-Ovchinnikov State in the Organic Superconductor k-(BEDT-TTF)2Cu(NCS)2 as Observed in Magnetic Torque Experiments
We present magnetic-torque experiments on the organic superconductor
k-(BEDT-TTF)2Cu(NCS)2 for magnetic fields applied parallel to the 2D
superconducting layers. The experiments show a crossover from a second-order to
a first-order transition when the upper critical field reaches 21 T. Beyond
this field, which we interpret as the Pauli limit for superconductivity, the
upper critical field line shows a pro-nounced upturn and a phase transition
line separates the superconducting state into a low- and a high-field phase. We
interpret the data in the framework of a Fulde-Ferrell-Larkin-Ovchinnikov
state.Comment: 2 pages, 1 figur
Inhomogeneous electronic structure probed by spin-echo experiments in the electron doped high-Tc superconductor Pr_{1.85}Ce_{0.15}CuO_{4-y}
63Cu nuclear magnetic resonance (NMR) spin-echo decay rate (T_2^{-1})
measurements are reported for the normal and superconducting states of a single
crystal of Pr_{1.85}Ce_{0.15}CuO_{4-y} (PCCO) in a magnetic field B_0=9T over
the temperature range 2K<T<200K. The spin-echo decay rate is
temperature-dependent for T<55K, and has a substantial dependence on the radio
frequency (rf) pulse parameters below T~25K. This dependence indicates that
T_2^{-1} is strongly effected by a local magnetic field distribution that can
be modified by the rf pulses, including ones that are not at the nuclear Larmor
frequency. The low-temperature results are consistent with the formation of a
static inhomogeneous electronic structure that couples to the rf fields of the
pulses.Comment: 4 pages, 4 figure
Influência das variáveis solvente, temperatura e tempo na extração de compostos fenólicos totais em sementes de maracujá gerada no processamento industrial.
O objetivo deste trabalho consistiu em quantificar o teor de compostos fenólicos totais no sentido de agregar valor funcional e nutricional a este resíduo agroindustrial e avaliar a influência dos variáveis tipos de solvente, tempo e temperatura na extração destes compostos.Edição dos Anais do 12º Congresso Nacional da Sociedade Brasileira de Alimentação e Nutrição, Foz do Iguaçu, PR, 13 a 16 de agosto de 2013
Faraday rotation spectra of bismuth-substituted ferrite garnet films with in-plane magnetization
Single crystalline films of bismuth-substituted ferrite garnets have been
synthesized by the liquid phase epitaxy method where GGG substrates are dipped
into the flux. The growth parameters are controlled to obtain films with
in-plane magnetization and virtually no domain activity, which makes them
excellently suited for magnetooptic imaging. The Faraday rotation spectra were
measured across the visible range of wavelengths. To interprete the spectra we
present a simple model based on the existence of two optical transitions of
diamagnetic character, one tetrahedral and one octahedral. We find excellent
agreement between the model and our experimental results for photon energies
between 1.77 and 2.53 eV, corresponding to wavelengths between 700 and 490 nm.
It is shown that the Faraday rotation changes significantly with the amount of
substituted gallium and bismuth. Furthermore, the experimental results suggest
that the magnetooptic response changes linearly with the bismuth substitution.Comment: 15 pages, 6 figures, published in Phys. Rev.
Antiferromagnetic Phases in the Fulde-Ferrell-Larkin-Ovchinnikov State of CeCoIn_5
The antiferromagnetic (AFM) order in the Fulde-Ferrell-Larkin-Ovchinnikov
(FFLO) superconducting state is analyzed on the basis of a Ginzburg-Landau
theory. To examine the possible AFM-FFLO state in CeCoIn_5, we focus on the
incommensurate AFM order characterized by the wave vector Q = Q_{0} \pm q_inc
with Q_0 =(\pi,\pi,\pi) and q_inc \parallel [110] or [1-10] in the tetragonal
crystal structure. We formulate the two component Ginzburg-Landau theory and
investigate the two degenerate incommensurate AFM order. We show that the
pinning of AFM moment due to the FFLO nodal planes leads to multiple phases in
magnetic fields along [100] or [010]. The phase diagrams for various coupling
constants between the two order parameters are shown for the comparison with
CeCoIn_5. Experimental results of the NMR and neutron scattering measurements
are discussed.Comment: 6pages, Proceedings of ICHE2010, To appear in J. Phys. Soc. Jpn.
Supp
Pre-M Phase-promoting Factor Associates with Annulate Lamellae in Xenopus Oocytes and Egg Extracts
We have used complementary biochemical and in vivo approaches to study the compartmentalization of M phase-promoting factor (MPF) in prophase Xenopus eggs and oocytes. We first examined the distribution of MPF (Cdc2/CyclinB2) and membranous organelles in high-speed extracts of Xenopus eggs made during mitotic prophase. These extracts were found to lack mitochondria, Golgi membranes, and most endoplasmic reticulum (ER) but to contain the bulk of the pre-MPF pool. This pre-MPF could be pelleted by further centrifugation along with components necessary to activate it. On activation, Cdc2/CyclinB2 moved into the soluble fraction. Electron microscopy and Western blot analysis showed that the pre-MPF pellet contained a specific ER subdomain comprising "annulate lamellae" (AL): stacked ER membranes highly enriched in nuclear pores. Colocalization of pre-MPF with AL was demonstrated by anti-CyclinB2 immunofluorescence in prophase oocytes, in which AL are positioned close to the vegetal surface. Green fluorescent protein-CyclinB2 expressed in oocytes also localized at AL. These data suggest that inactive MPF associates with nuclear envelope components just before activation. This association may explain why nuclei and centrosomes stimulate MPF activation and provide a mechanism for targeting of MPF to some of its key substrates
Mechanism for the Singlet to Triplet Superconductivity Crossover in Quasi-One-Dimensional Organic Conductors
Superconductivity of quasi-one-dimensional organic conductors with a
quarter-filled band is investigated using the two-loop renormalization group
approach to the extended Hubbard model for which both the single electron
hopping t_{\perp} and the repulsive interaction V_{\perp} perpendicular to the
chains are included. For a four-patches Fermi surface with deviations to
perfect nesting, we calculate the response functions for the dominant
fluctuations and possible superconducting states. By increasing V_{\perp}, it
is shown that a d-wave (singlet) to f-wave (triplet) superconducting state
crossover occurs, and is followed by a vanishing spin gap. Furthermore, we
study the influence of a magnetic field through the Zeeman coupling, from which
a triplet superconducting state is found to emerge.Comment: 11 pages, 15 figures, published versio
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