906 research outputs found
Enhancement of type 1 interferon induction with drug and radiation treatments to increase anti-tumor immunity
https://openworks.mdanderson.org/sumexp21/1185/thumbnail.jp
Spin entanglement induced by spin-orbit interactions in coupled quantum dots
We theoretically explore the possibility of creating spin quantum
entanglement in a system of two electrons confined respectively in two
vertically coupled quantum dots in the presence of Rashba type spin-orbit
coupling. We find that the system can be described by a generalized Jaynes -
Cummings model of two modes bosons interacting with two spins. The lower
excitation states of this model are calculated to reveal the underlying physics
of the far infrared absorption spectra. The analytic perturbation approach
shows that an effective transverse coupling of spins can be obtained by
eliminating the orbital degrees of freedom in the large detuning limit. Here,
the orbital degrees of freedom of the two electrons, which are described by two
modes of bosons, serve as a quantized data bus to exchange the quantum
information between two electrons. Then a nontrivial two-qubit logic gate is
realized and spin entanglement between the two electrons is created by virtue
of spin-orbit coupling.Comment: 7 pages, 5 figure
Cooling Torsional Nanomechanical Vibration by Spin-Orbit Interactions
We propose and study a spin-orbit interaction based mechanism to actively
cool down the torsional vibration of a nanomechanical resonator made by
semiconductor materials. We show that the spin-orbit interactions of electrons
can induce a coherent coupling between the electron spins and the torsional
modes of nanomechanical vibration. This coherent coupling leads to an active
cooling for the torsional modes via the dynamical thermalization of the
resonator and the spin ensemble.Comment: 4 pages, 3 figure
Cross-Correlation Detection of Point Sources in WMAP First Year Data
We apply a Cross-correlation (CC) method developed previously for detecting
gamma-ray point sources to the WMAP first year data by using the Point-Spread
Function of WMAP and obtain a full sky CC coefficient map. Analyzing this map,
we find that the CC method is a powerful tool to examine the WMAP foreground
residuals which can be further cleaned accordingly. Evident foreground signals
are found in WMAP foreground cleaned maps and Tegmark cleaned map. In this
process 101 point-sources are detected, and 26 of them are new sources besides
the originally listed WMAP 208 sources. We estimate the flux of these new
sources and verify them by another method. As a result, a revised mask file
based on the WMAP first year data is produced by including these new sources.Comment: 14 pages, 10 figures; accepted for publication by ChJA
The Comparative RNA Web (CRW) Site: an online database of comparative sequence and structure information for ribosomal, intron, and other RNAs
BACKGROUND: Comparative analysis of RNA sequences is the basis for the detailed and accurate predictions of RNA structure and the determination of phylogenetic relationships for organisms that span the entire phylogenetic tree. Underlying these accomplishments are very large, well-organized, and processed collections of RNA sequences. This data, starting with the sequences organized into a database management system and aligned to reveal their higher-order structure, and patterns of conservation and variation for organisms that span the phylogenetic tree, has been collected and analyzed. This type of information can be fundamental for and have an influence on the study of phylogenetic relationships, RNA structure, and the melding of these two fields. RESULTS: We have prepared a large web site that disseminates our comparative sequence and structure models and data. The four major types of comparative information and systems available for the three ribosomal RNAs (5S, 16S, and 23S rRNA), transfer RNA (tRNA), and two of the catalytic intron RNAs (group I and group II) are: (1) Current Comparative Structure Models; (2) Nucleotide Frequency and Conservation Information; (3) Sequence and Structure Data; and (4) Data Access Systems. CONCLUSIONS: This online RNA sequence and structure information, the result of extensive analysis, interpretation, data collection, and computer program and web development, is accessible at our Comparative RNA Web (CRW) Site http://www.rna.icmb.utexas.edu. In the future, more data and information will be added to these existing categories, new categories will be developed, and additional RNAs will be studied and presented at the CRW Site
Dielectric, ferroelectric, magnetic, and magnetoelectric properties of multiferroic laminated composites
Multiferroic laminated composites consisting of lead-zirconate titanate (PZT)/polyvinylidene-fluoride (PVDF) particulate composite layers and Tb-Dy-Fe alloy (Terfenol-D)/PVDF particulate composite layers, prepared by a simple hot-molding technique, were reported. In the laminated composites, the polymer PVDF is inert and used just as a binder. The measured dielectric, ferroelectric, magnetic, and magnetoelectric properties demonstrate strong dependence on volume fraction f of the PVDF in the laminated composites. As f is low (e.g., f<0.3), a low concentration of binder leads to low quality of the composites and thus low performance. Better performance of the composites appears in the intermediate f range. As f further increases, high concentration of the inert PVDF results in weak dielectric, magnetostrictive, piezo- and magnetoelectric responses of the laminated composites. Our results illustrate that the three-phase laminated composites exhibit remarkable magnetoelectric effect especially at high frequency at which the electromechanical resonance appears
Perturbative QCD study of the B-> K^* gamma decay
We apply the perturbative QCD factorization theorem developed recently for
nonleptonic heavy meson decays to the radiative decay . In this
formalism the evolution of the Wilson coefficients from the boson mass down
to the characteristic scale of the decay process is governed by the effective
weak Hamiltonian. The evolution from the characteristic scale to a lower
hadronic scale is formulated by the Sudakov resummation. Besides computing the
dominant contribution arising from the magnetic-penguin operator , we also
calculate the contributions of four-quark operators. By fitting our prediction
for the branching ratio of the decay to the CLEO data, we
determine the meson wave function, that possesses a sharp peak at a low
momentum fraction.Comment: 17 pages, 4 figures; version to appear in Phys. Rev.
Coupled magnetodielectric properties of laminated PbZr0.53Ti0.47O3/NiFe2O4 ceramics
Simple multiferroic laminated ceramics of lead-zirconate-titanate PbZr0.53Ti0.47O3(PZT)/NiFe2O4 were prepared by a conventional ceramic processing. The measured magnetodielectric properties demonstrated strong dependence on the relative thickness of the PZT layers, magnetic bias, and angle between the bias and polarization in the laminated ceramics. Recent theoretical approaches were employed to explain these observed behaviors. The maximum magnetoelectric sensitivity (alpha(E31)) of the ceramics samples could reach up to as high as 0.21 V/A at 11.9 kA/m. In particular, at low magnetic bias, the laminated ceramics were found to have a very large magnetoelectric sensitivity linearly varying with the bias. (C) 2004 American Institute of Physics
- …