5,713 research outputs found
Properties of highly frustrated magnetic molecules studied by the finite-temperature Lanczos method
The very interesting magnetic properties of frustrated magnetic molecules are
often hardly accessible due to the prohibitive size of the related Hilbert
spaces. The finite-temperature Lanczos method is able to treat spin systems for
Hilbert space sizes up to 10^9. Here we first demonstrate for exactly solvable
systems that the method is indeed accurate. Then we discuss the thermal
properties of one of the biggest magnetic molecules synthesized to date, the
icosidodecahedron with antiferromagnetically coupled spins of s=1/2. We show
how genuine quantum features such as the magnetization plateau behave as a
function of temperature.Comment: 7 pages, 10 figures, submitted to EPJ
Multi-Level quasi-Newton methods for the partitioned simulation of fluid-structure interaction
In previous work of the authors, Fourier stability analyses have been performed of Gauss-Seidel iterations between the flow solver and the structural solver in a partitioned fluid-structure interaction simulation. These analyses of the flow in an elastic tube demonstrated that only a number of Fourier modes in the error on the interface displacement are unstable. Moreover, the modes with a low wave number are most unstable and these modes can be resolved on a coarser grid. Therefore, a new class of quasi-Newton methods with more than one grid level is introduced. Numerical experiments show a significant reduction in run time
On explicit results at the intersection of the Z_2 and Z_4 orbifold subvarieties in K3 moduli space
We examine the recently found point of intersection between the Z_2 and Z_4
orbifold subvarieties in the K3 moduli space more closely. First we give an
explicit identification of the coordinates of the respective Z_2 and Z_4
orbifold theories at this point. Secondly we construct the explicit
identification of conformal field theories at this point and show the
orthogonality of the two subvarieties.Comment: Latex, 23 page
Oscillatory combustion in rockets Third semiannual report, Jun. 1 - Nov. 30, 1965
Rocket engine oscillatory combustion studie
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Alterations in T1 of normal and reperfused infarcted myocardium after Gd-BOPTA versus GD-DTPA on inversion recovery EPI.
This study tested whether Gd-BOPTA/Dimeg or Gd-DTPA exerts greater relaxation enhancement for blood and reperfused infarcted myocardium. Relaxivity of Gd-BOPTA is increased by weak binding to serum albumin. Thirty-six rats were subjected to reperfused infarction before contrast (doses = 0.05, 0.1, and 0.2 mmol/kg). delta R1 was repeatedly measured over 30 min. Gd-BOPTA caused greater delta R1 for blood and myocardium than did Gd-DTPA; clearance of both agents from normal- and infarcted myocardium was similar to blood clearance; plots of delta R1 myocardium/delta R1 blood showed equilibrium phase contrast distribution. Fractional contrast agent distribution volumes were approximately 0.24 for both agents in normal myocardium, 0.98 and 1.6 for Gd-DTPA and Gd-BOPTA, respectively, in reperfused infarction. The high value for Gd-BOPTPA was ascribed to greater relaxivity in infarction versus blood. It was concluded that Gd-BOPTA/Dimeg causes a greater delta R1 than Gd-DTPA in regions which contain serum albumin
Reação de acessos de feijoeiro comum, coletados no litoral médio e sul do Rio Grande do Sul, ao crestamento bacteriano comum, murcha-de-curtobacterium e antracnose.
Acessos de feijoeiro comum, oriundos de coleta realizada no litoral médio e sul do Rio Grande do Sul, foram testados para reação ao crestamento bacteriano comum, murcha-de-curtobacterium e para três patótipos de Colletotrichum lindemuthianum. Nenhum acesso teve reação de resistência ao crestamento bacteriano comum e à murcha-de-curtobacterium. Seis acessos tiveram reação de resistência conjunta aos patótipos de C. lindemuthianum
Obtenção de famílias com resistência conjunta ao crestamento bacteriano comum e à murcha-de-curtobacterium.
Utilizando como genitores doadores linhagens e acessos de feijoeiro comum (Phaseolus vulgaris) com resistência ao crestamento bacteriano comum e à murcha-de-curtobacterium, e como genitores recorrentes linhagens elites foram realizados retrocruzamentos com o objetivo de obter famílias com resistência conjunta aos dois patógenos
Numerical Ricci-flat metrics on K3
We develop numerical algorithms for solving the Einstein equation on
Calabi-Yau manifolds at arbitrary values of their complex structure and Kahler
parameters. We show that Kahler geometry can be exploited for significant gains
in computational efficiency. As a proof of principle, we apply our methods to a
one-parameter family of K3 surfaces constructed as blow-ups of the T^4/Z_2
orbifold with many discrete symmetries. High-resolution metrics may be obtained
on a time scale of days using a desktop computer. We compute various geometric
and spectral quantities from our numerical metrics. Using similar resources we
expect our methods to practically extend to Calabi-Yau three-folds with a high
degree of discrete symmetry, although we expect the general three-fold to
remain a challenge due to memory requirements.Comment: 38 pages, 10 figures; program code and animations of figures
downloadable from http://schwinger.harvard.edu/~wiseman/K3/ ; v2 minor
corrections, references adde
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