437 research outputs found
Probabilistic Fragmentation and Effective Power Law
A simple fragmentation model is introduced and analysed. We show that, under
very general conditions, an effective power law for the mass distribution
arises with realistic exponent. This exponent has a universal limit, but in
practice the effective exponent depends on the detailed breaking mechanism and
the initial conditions. This dependence is in good agreement with experimental
results of fragmentation.Comment: 4 pages Revtex, 2 figures, zipped and uuencode
From the Kondo Regime to the Mixed-Valence Regime in a Single-Electron Transistor
We demonstrate that the conductance through a single-electron transistor at
low temperature is in quantitative agreement with predictions of the
equilibrium Anderson model. When an unpaired electron is localized within the
transistor, the Kondo effect is observed. Tuning the unpaired electron's energy
toward the Fermi level in nearby leads produces a cross-over between the Kondo
and mixed-valence regimes of the Anderson model.Comment: 3 pages plus one 2 page postscript file of 5 figures. Submitted to
PR
Novel Properties of The Apparent Metal-Insulator Transition in Two-Dimensional Systems
The low-temperature conductivity of low-density, high-mobility,
two-dimensional hole systems in GaAs was studied. We explicitly show that the
metal-insulator transition, observed in these systems, is characterized by a
well-defined critical density, p_0c. We also observe that the low-temperature
conductivity of these systems depends linearly on the hole density, over a wide
density range. The high-density linear conductivity extrapolates to zero at a
density close to the critical density.Comment: 4 Figure
Singlet-triplet transition in a single-electron transistor at zero magnetic field
We report sharp peaks in the differential conductance of a single-electron
transistor (SET) at low temperature, for gate voltages at which charge
fluctuations are suppressed. For odd numbers of electrons we observe the
expected Kondo peak at zero bias. For even numbers of electrons we generally
observe Kondo-like features corresponding to excited states. For the latter,
the excitation energy often decreases with gate voltage until a new zero-bias
Kondo peak results. We ascribe this behavior to a singlet-triplet transition in
zero magnetic field driven by the change of shape of the potential that
confines the electrons in the SET.Comment: 4 p., 4 fig., 5 new ref. Rewrote 1st paragr. on p. 4. Revised author
list. More detailed fit results on page 3. A plotting error in the horizontal
axis of Fig. 1b and 3 was corrected, and so were the numbers in the text read
from those fig. Fig. 4 was modified with a better temperature calibration
(changes are a few percent). The inset of this fig. was removed as it is
unnecessary here. Added remarks in the conclusion. Typos are correcte
Near real-time estimation of water vapour in the troposphere using ground GNSS and the meteorological data
Transmission Phase of a Quantum Dot with Kondo Correlation Near the Unitary Limit
The complex transmission amplitude -- both magnitude and phase -- of a
quantum dot (QD) with Kondo correlation was measured near the unitary limit.
Contrary to previous phase measurements, performed far from this limit [Ji et
al., Science 290, 779 (2000)], the transmission phase was observed to evolve
linearly over a range of about 1.5 pi when the Fermi energy was scanned through
a Kondo pair -- a pair of spin degenerate energy levels. Moreover, the phase in
Coulomb blockade (CB) peak, adjancent to the Kondo pair, retained a memory of
the Kondo correlation and did not exhibit the familiar behavior in the CB
regime. These results do not agree with theoretical predictions, suggesting
that a full explanation may go beyond the framework of the Anderson model.Comment: 4 pages, 4 figure
Spin-1/2 Kondo effect in an InAs nanowire quantum dot: the Unitary limit, conductance scaling and Zeeman splitting
We report on a comprehensive study of spin-1/2 Kondo effect in a
strongly-coupled quantum dot realized in a high-quality InAs nanowire. The
nanowire quantum dot is relatively symmetrically coupled to its two leads, so
the Kondo effect reaches the Unitary limit. The measured Kondo conductance
demonstrates scaling with temperature, Zeeman magnetic field, and
out-of-equilibrium bias. The suppression of the Kondo conductance with magnetic
field is much stronger than would be expected based on a g-factor extracted
from Zeeman splitting of the Kondo peak. This may be related to strong
spin-orbit coupling in InAs.Comment: 12 pages, 7 figures. Revised version accepted for publicatio
Observation of the Metal-Insulator Transition in Two-Dimensional n-type GaAs
The observation of a carrier-density driven metal-insulator transition in
n-type GaAs-based heterostructure is reported. Although weaker than in
comparable-quality p-type GaAs samples, the main features of the transition are
rather similar.Comment: 3 pages, 3 figure
Efficacy and safety of lumasiran for infants and young children with primary hyperoxaluria type 1: 12-month analysis of the phase 3 ILLUMINATE-B trial
BACKGROUND: Primary hyperoxaluria type 1 (PH1) is a rare genetic disease that causes progressive kidney damage and systemic oxalosis due to hepatic overproduction of oxalate. Lumasiran demonstrated efficacy and safety in the 6-month primary analysis period of the phase 3, multinational, open-label, single-arm ILLUMINATE-B study of infants and children < 6 years old with PH1 (ClinicalTrials.gov: NCT03905694 (4/1/2019); EudraCT: 2018–004,014-17 (10/12/2018)). Outcomes in the ILLUMINATE-B extension period (EP) for patients who completed ≥ 12 months on study are reported here. METHODS: Of the 18 patients enrolled in the 6-month primary analysis period, all entered the EP and completed ≥ 6 additional months of lumasiran treatment (median (range) duration of total exposure, 17.8 (12.7–20.5) months). RESULTS: Lumasiran treatment was previously reported to reduce spot urinary oxalate:creatinine ratio by 72% at month 6, which was maintained at 72% at month 12; mean month 12 reductions in prespecified weight subgroups were 89%, 68%, and 71% for patients weighing < 10 kg, 10 to < 20 kg, and ≥ 20 kg, respectively. The mean reduction from baseline in plasma oxalate level was reported to be 32% at month 6, and this improved to 47% at month 12. Additional improvements were also seen in nephrocalcinosis grade, and kidney stone event rates remained low. The most common lumasiran-related adverse events were mild, transient injection-site reactions (3 patients (17%)). CONCLUSIONS: Lumasiran treatment provided sustained reductions in urinary and plasma oxalate through month 12 across all weight subgroups, with an acceptable safety profile, in infants and young children with PH1. GRAPHICAL ABSTRACT: A higher resolution version of the Graphical abstract is available as Supplementary information
Unexpected Behavior of the Local Compressibility Near the B=0 Metal-Insulator Transition
We have measured the local electronic compressibility of a two-dimensional
hole gas as it crosses the B=0 Metal-Insulator Transition. In the metallic
phase, the compressibility follows the mean-field Hartree-Fock (HF) theory and
is found to be spatially homogeneous. In the insulating phase it deviates by
more than an order of magnitude from the HF predictions and is spatially
inhomogeneous. The crossover density between the two types of behavior, agrees
quantitatively with the transport critical density, suggesting that the system
undergoes a thermodynamic change at the transition.Comment: As presented in EP2DS-13, Aug. 1999. (4 pages, 4 figures
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