1,581 research outputs found

    Fast image decompression for telebrowsing of images

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    Progressive image transmission (PIT) is often used to reduce the transmission time of an image telebrowsing system. A side effect of the PIT is the increase of computational complexity at the viewer's site. This effect is more serious in transform domain techniques than in other techniques. Recent attempts to reduce the side effect are futile as they create another side effect, namely, the discontinuous and unpleasant image build-up. Based on a practical assumption that image blocks to be inverse transformed are generally sparse, this paper presents a method to minimize both side effects simultaneously

    Quasiparticle Interactions for f2^2-Impurity Anderson Model with Crystalline-Electric-Field: Numerical Renormalization Group Study

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    The aspect of the quasiparticle interaction of a local Fermi liquid, the impurity version of f2^2-based heavy fermions, is studied by the Wilson numerical renormalization group method. In particular, the case of the f2^2-singlet crystalline-electric-field ground state is investigated assuming the case of UPt3_3 with the hexagonal symmetry. It is found that the interorbital interaction becomes larger than the intraorbital one in contrast to the case of the bare Coulomb interaction for the parameters relevant to UPt3_3. This result offers us a basis to construct a microscopic theory of the superconductivity of UPt3_3 where the interorbital interactions are expected to play important roles.Comment: 9 pages, 5 figure

    Building a 3.5 m prototype interferometer for the Q & A vacuum birefringence experiment and high precision ellipsometry

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    We have built and tested a 3.5 m high-finesse Fabry-Perot prototype inteferometer with a precision ellipsometer for the QED test and axion search (Q & A) experiment. We use X-pendulum-double-pendulum suspension designs and automatic control schemes developed by the gravitational-wave detection community. Verdet constant and Cotton-Mouton constant of the air are measured as a test. Double modulation with polarization modulation 100 Hz and magnetic-field modulation 0.05 Hz gives 10^{-7} rad phase noise for a 44-minute integration.Comment: This draft has been presented in the 5th Edoardo Amaldi Conference on Gravitational Wave

    Hmong of Germany: Preliminary Report on the Resettlement of Lao Hmong Refugees in Germany

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    This paper briefly describes the resettlement of Lao Hmong refugees in Germany since the fall of Laos in 1975. Data for this paper were collected during my two visits to the Hmong community of Gammertingen in southern Germany. Although, it has been known that there are Lao Hmong refugees living in Germany, literature about their resettlement in academic journals and the western media has been nonexistent. Therefore, information about their population, social, educational and economic status has not been available. While serving in the U.S. Army, I was fortunate to be stationed in Germany and had several opportunities to visits and interact with this isolate Hmong community. Therefore, I would like to share what little information I have gathered about this forgotten Hmong community. This paper provides a preliminary report on the resettlement process, population, social, educational and economic status of this community. Data were collected primarily through informal direct interviews with the head of household from four families of the original five families that resettled in Germany. As of the writing of this paper, there is no other known Hmong community in Germany other than this Gammertingen Hmong community

    Dynamical Screening and Superconducting State in Intercalated Layered Metallochloronitrides

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    An essential property of layered systems is the dynamical nature of the screened Coulomb interaction. Low energy collective modes appear as a consequence of the layering and provide for a superconducting-pairing channel in addition to the electron-phonon induced attractive interaction. We show that taking into account this feature allows to explain the high critical temperatures (Tc~26K) observed in recently discovered intercalated metallochloronitrides. The exchange of acoustic plasmons between carriers leads to a significant enhancement of the superconducting critical temperature that is in agreement with the experimental observations

    Improved Simulation of the Mass Charging for ASTROD I

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    The electrostatic charging of the test mass in ASTROD I (Astrodynamical Space Test of Relativity using Optical Devices I) mission can affect the quality of the science data as a result of spurious Coulomb and Lorentz forces. To estimate the size of the resultant disturbances, credible predictions of charging rates and the charging noise are required. Using the GEANT4 software toolkit, we present a detailed Monte Carlo simulation of the ASTROD I test mass charging due to exposure of the spacecraft to galactic cosmic-ray (GCR) protons and alpha particles (3He, 4He) in the space environment. A positive charging rate of 33.3 e+/s at solar minimum is obtained. This figure reduces by 50% at solar maximum. Based on this charging rate and factoring in the contribution of minor cosmic-ray components, we calculate the acceleration noise and stiffness associated with charging. We conclude that the acceleration noise arising from Coulomb and Lorentz effects are well below the ASTROD I acceleration noise limit at 0.1 mHz both at solar minimum and maximum. The coherent Fourier components due to charging are investigated, it needs to be studied carefully in order to ensure that these do not compromise the quality of science data in the ASTROD I mission.Comment: 20 pages, 14 figures, submitted to International Journal of Modern Physics

    Effect of Spin-Orbit Interaction in Spin-Triplet Superconductor: Structure of d{\bf d}-vector and Anomalous 17^{17}O-NQR Relaxation in Sr2_2RuO4_4

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    Supposing the spin-triplet superconducting state of Sr2_2RuO4_4, the spin-orbit (SO) coupling associated with relative motion in Cooper pairs is calculated by extending the method for the dipole-dipole coupling given by Leggett in the superfluid 3^{3}He. It is shown that the SO coupling works only in the equal-spin pairing (ESP) state to make the pair angular momentum L\hbar{\vec L} and the pair spin angular momentum id×d{\rm i}{\vec d}\times{\vec d}^{*} parallel with each other. The SO coupling gives rise to the internal Josephson effect in a chiral ESP state as in superfluid A-phase of 3^3He with a help of an additional anisotropy arising from SO coupling of atomic origin which works to direct the {\bf d}-vector into abab-plane. This resolves the problem of the anomalous relaxation of 17^{17}O-NQR and the structure of {\bf d}-vector in Sr2_2RuO4_4.Comment: Accepted for publication in J. Phys. Soc. Jpn. vol.79 (2010), No.2 (February issue); 18 pages, 2 figure

    A theory of new type of heavy-electron superconductivity in PrOs_4Sb_12: quadrupolar-fluctuation mediated odd-parity pairings

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    It is shown that unconventional nature of superconducting state of PrOs_4Sb_12, a Pr-based heavy electron compound with the filled-Skutterudite structure, can be explained in a unified way by taking into account the structure of the crystalline-electric-field (CEF) level, the shape of the Fermi surface determined by the band structure calculation, and a picture of the quasiparticles in f2^{2}-configuration with magnetically singlet CEF ground state. Possible types of pairing are narrowed down by consulting recent experimental results. In particular, the chiral "p"-wave states such as p_x+ip_y is favoured under the magnetic field due to the orbital Zeeman effect, while the "p"-wave states with two-fold symmetery such as p_x can be stabilized by a feedback effect without the magnetic field. It is also discussed that the double superconducting transition without the magnetic field is possible due to the spin-orbit coupling of the "triplet" Cooper pairs in the chiral state.Comment: 12 pages, 2 figures, submitted to J. Phys.: Condens. Matter Lette
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