11,800 research outputs found
Transport in the Heavy Fermion Superconductor UPt3
We report new theoretical results and analysis for the transport properties
of superconducting UPt3 based on the leading models for the pairing symmetry.
We use Fermi surface data and the measured inelastic scattering rate to show
that the low-temperature thermal conductivity and transverse sound attenuation
in the A and B phase of UPt3 are in excellent agreement with pairing states
belonging to the two-dimensional orbital E2u representation.Comment: 2 pages, contribution at Int. Conf. LT-22, Helsinki, Finland, 4-11
Aug. 199
The impact of quark masses on pQCD thermodynamics
We present results for several thermodynamic quantities within the
next-to-leading order calculation of the thermodynamic potential in
perturbative QCD at finite temperature and chemical potential including
non-vanishing quark masses. These results are compared to lattice data and to
higher-order optimized perturbative calculations to investigate the trend
brought about by mass corrections.Comment: V2: Major modifications; 12 pages, 13 figure
Some recent developments in quantization of fractal measures
We give an overview on the quantization problem for fractal measures,
including some related results and methods which have been developed in the
last decades. Based on the work of Graf and Luschgy, we propose a three-step
procedure to estimate the quantization errors. We survey some recent progress,
which makes use of this procedure, including the quantization for self-affine
measures, Markov-type measures on graph-directed fractals, and product measures
on multiscale Moran sets. Several open problems are mentioned.Comment: 13 page
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Cryo-EM structure of the potassium-chloride cotransporter KCC4 in lipid nanodiscs.
Cation-chloride-cotransporters (CCCs) catalyze transport of Cl- with K+ and/or Na+across cellular membranes. CCCs play roles in cellular volume regulation, neural development and function, audition, regulation of blood pressure, and renal function. CCCs are targets of clinically important drugs including loop diuretics and their disruption has been implicated in pathophysiology including epilepsy, hearing loss, and the genetic disorders Andermann, Gitelman, and Bartter syndromes. Here we present the structure of a CCC, the Mus musculus K+-Cl- cotransporter (KCC) KCC4, in lipid nanodiscs determined by cryo-EM. The structure, captured in an inside-open conformation, reveals the architecture of KCCs including an extracellular domain poised to regulate transport activity through an outer gate. We identify binding sites for substrate K+ and Cl- ions, demonstrate the importance of key coordinating residues for transporter activity, and provide a structural explanation for varied substrate specificity and ion transport ratio among CCCs. These results provide mechanistic insight into the function and regulation of a physiologically important transporter family
Electronic structure of the substitutional versus interstitial manganese in GaN
Density-functional studies of the electron states in the dilute magnetic
semiconductor GaN:Mn reveal major differences for the case of the Mn impurity
at the substitutional site Mn_Ga versus the interstitial site Mn_I. The
splitting of the two-fold and the three-fold degenerate Mn(d)states in the gap
are reversed between the two cases, which is understood in terms of the
symmetry-controlled hybridization with the neighboring atoms. In contrast to
Mn_Ga, which acts as a deep acceptor, Mn_I acts as a donor, suggesting the
formation of Coulomb-stabilized complexes such as (Mn_Ga Mn_I Mn_Ga), where the
acceptor level of Mn_Ga is passivated by the Mn_I donor. Formation of such
passivated clusters might be the reason for the observed low carrier-doping
efficiency of Mn in GaN. Even though the Mn states are located well inside the
gap,the wave functions are spread far away from the impurity center. This is
caused by the hybridization with the nitrogen atoms, which acquire small
magnetic moments aligned with the Mn moment. Implications of the differences in
the electronic structure for the optical properties are discussed
Comparison of quantization of charge transport in periodic and open pumps
We compare the charges transported in two systems, a spatially periodic and
an open quantum pump, both depending periodically and adiabatically on time.
The charge transported in a cycle was computed by Thouless, respectively by
Buttiker et al. in the two cases. We show that the results agree in the limit
where the two physical situations become the same, i.e., that of a large open
pump.Comment: 7 page
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