212 research outputs found
Expansion of Vortex Cores by Strong Electronic Correlation in LaSrCuO at Low Magnetic Induction
The vortex core radius \rv, defined as the peak position of the supercurrent
around the vortex, has been determined by muon spin rotation measurements in
the mixed state of \lscox for , 0.15, and 0.19. At lower doping (x=0.13
and 0.15), \rv(T) increases with decreasing temperature T, which is opposite to
the behavior predicted by the conventional theory. Moreover, \rv(T\to0) is
significantly larger than the Ginsburg-Landau coherence length determined by
the upper critical field, and shows a clear tendency to decrease with
increasing the doping x. These features can be qualitatively reproduced in a
microscopic model involving antiferromagnetic electronic correlations.Comment: 6 pages, 4 figures, to be published in Phys. Rev.
Resummation of Running Coupling Effects in Semileptonic B Meson Decays and Extraction of
We present a determination of from semileptonic B decays that
includes resummation of supposedly large perturbative corrections, originating
from the running of the strong coupling. We argue that the low value of the BLM
scale found previously for inclusive decays is a manifestation of the
renormalon divergence of the perturbative series starting already in third
order. A reliable determination of from inclusive decays is possible
if one either uses a short-distance b quark mass or eliminates all unphysical
mass parameters in terms of measured observables, such that all infra-red
contributions of order cancel explicitly. We find that using the
running mass significantly reduces the perturbative
coefficients already in low orders. For a semileptonic branching ratio of
we obtain from
inclusive decays, in good agreement with the value extracted from exclusive
decays.Comment: 37 pages + 4 figures, final version accepted for publication in Phys.
Rev.
Semileptonic form factors - a model-independent approach
We demonstrate that the B->D(*) l nu form factors can be accurately predicted
given the slope parameter rho^2 of the Isgur-Wise function. Only weak
assumptions, consistent with lattice results, on the wavefunction for the light
degrees of freedom are required to establish this result. We observe that the
QCD and 1/m_Q corrections can be systematically represented by an effective
Isgur-Wise function of shifted slope. This greatly simplifies the analysis of
semileptonic B decay. We also investigate what the available semileptonic data
can tell us about lattice QCD and Heavy Quark Effective Theory. A rigorous
identity relating the form factor slope difference rho_D^2-rho_A1^2 to a
combination of form factor intercepts is found. The identity provides a means
of checking theoretically evaluated intercepts with experiment.Comment: 18 pages, Revtex, 4 postscript figures, uses epsfig.st
Field dependence of the vortex structure in chiral p-wave superconductors
To investigate the different vortex structure between two chiral pairing p_x
+(-) i p_y, we calculate the pair potential, the internal field, the local
density of states, and free energy in the vortex lattice state based on the
quasiclassical Eilenberger theory, and analyze the magnetic field dependence.
The induced opposite chiral component of the pair potential plays an important
role in the vortex structure. It also produces H^{1/2}-behavior of the
zero-energy density of states at higher field. These results are helpful when
we understand the vortex states in Sr2RuO4.Comment: 11 pages, 10 figures, to be published in Phys. Rev.
Childbirth after adolescent and young adult cancer: a population-based study
Purpose: Annually, > 45,000 US women are diagnosed with cancer during adolescence and young adulthood (AYA). Since 2006, national guidelines have recommended fertility counseling for cancer patients. We examined childbirth after AYA cancer by calendar period, cancer diagnosis, and maternal characteristics. Methods: We identified a cohort of women with an incident invasive AYA cancer diagnosis at ages 15–39 during 2000–2013 in North Carolina. Cancer records were linked with statewide birth certificates through 2014. Hazard ratios (HR) and 95% confidence intervals (CI) for first post-diagnosis live birth were calculated using Cox proportional hazards regression. Results: Among 17,564 AYA cancer survivors, 1989 had ≥ 1 birth after diagnosis during 98,397 person-years. The 5- and 10-year cumulative incidence of live birth after cancer was 10 and 15%, respectively. AYA survivors with a post-diagnosis birth were younger at diagnosis, had lower stage disease, and had less often received chemotherapy than those without a birth. The 5-year cumulative incidence of post-diagnosis birth was 10.0% for women diagnosed during 2007–2012, compared to 9.4% during 2000–2005 (HR = 1.01; 0.91, 1.12), corresponding to periods before and after publication of American Society of Clinical Oncology fertility counseling guidelines in 2006. Conclusions: Despite advances in fertility preservation options and recognition of fertility counseling as a part of high-quality cancer care, the incidence of post-diagnosis childbirth has remained stable over the last 15 years. Implications for Cancer Survivors: Our study uses statewide data to provide recent, population-based estimates of how often AYA women have biological children after a cancer diagnosis
Dimensionality of spin modulations in 1/8-doped lanthanum cuprates from the perspective of NQR and muSR experiments
We investigate the dimensionality of inhomogeneous spin modulation patterns
in the cuprate family of high-temperature superconductors with particular focus
on 1/8-doped lanthanum cuprates. We compare one-dimensional stripe modulation
pattern with two-dimensional checkerboard of spin vortices in the context of
nuclear quadrupole resonance(NQR) and muon spin rotation(muSR) experiments. In
addition, we also consider the third pattern, a two-dimensional superposition
of spin spirals. Overall, we have found that none of the above patterns leads
to a consistent interpretation of the two types of experiments considered.
This, in particular, implies that the spin vortex checkerboard cannot be ruled
out on the basis of available NQR/muSR experimental results.Comment: 6 pages, 2 figure
Triplet superconductivity in quasi one-dimensional systems
We study a Hubbard hamiltonian, including a quite general nearest-neighbor
interaction, parametrized by repulsion V, exchange interactions Jz, Jperp,
bond-charge interaction X and hopping of pairs W. The case of correlated
hopping, in which the hopping between nearest neighbors depends upon the
occupation of the two sites involved, is also described by the model for
sufficiently weak interactions. We study the model in one dimension with usual
continuum-limit field theory techniques, and determine the phase diagram. For
arbitrary filling, we find a very simple necessary condition for the existence
of dominant triplet superconducting correlations at large distance in the spin
SU(2) symmetric case: 4V+J<0. In the correlated hopping model, the three-body
interaction should be negative for positive V. We also compare the predictions
of this weak-coupling treatment with numerical exact results for the
correlated-hopping model obtained by diagonalizing small chains, and using
novel techniques to determine the opening of the spin gap.Comment: 8 pages, 3 figure
Mimicking superinfection exclusion disrupts alphavirus infection and transmission in the yellow fever mosquito Aedes aegypti
Multiple viruses, including pathogenic viruses, bacteriophages, and even plant viruses, cause a phenomenon termed superinfection exclusion whereby a currently infected cell is resistant to secondary infection by the same or a closely related virus. In alphaviruses, this process is thought to be mediated, at least in part, by the viral protease (nsP2) which is responsible for processing the nonstructural polyproteins (P123 and P1234) into individual proteins (nsP1–nsP4), forming the viral replication complex. Taking a synthetic biology approach, we mimicked this naturally occurring phenomenon by generating a superinfection exclusion-like state in Aedes aegypti mosquitoes, rendering them refractory to alphavirus infection. By artificially expressing Sindbis virus (SINV) and chikungunya virus (CHIKV) nsP2 in mosquito cells and transgenic mosquitoes, we demonstrated a reduction in both SINV and CHIKV viral replication rates in cells following viral infection as well as reduced infection prevalence, viral titers, and transmission potential in mosquitoes.</p
Muon spin relaxation studies of incommensurate magnetism and superconductivity in stage-4 LaCuO and LaSrCuO
This paper reports muon spin relaxation (MuSR) measurements of two single
crystals of the title high-Tc cuprate systems where static incommensurate
magnetism and superconductivity coexist. By zero-field MuSR measurements and
subsequent analyses with simulations, we show that (1) the maximum ordered Cu
moment size (0.36 Bohr magneton) and local spin structure are identical to
those in prototypical stripe spin systems with the 1/8 hole concentration; (2)
the static magnetism is confined to less than a half of the volume of the
sample, and (3) regions with static magnetism form nano-scale islands with the
size comparable to the in-plane superconducting coherence length. By
transverse-field MuSR measurements, we show that Tc of these systems is related
to the superfluid density, in the same way as observed in cuprate systems
without static magnetism. We discuss a heuristic model involving percolation of
these nanoscale islands with static magnetism as a possible picture to
reconcile heterogeneity found by the present MuSR study and long-range spin
correlations found by neutron scattering.Comment: 19 pages, 15 figures, submitted to Phys. Rev. B. E-mail:
[email protected]
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