13 research outputs found
PRADER-WILLI SYNDROME, DIAGNOSTICS AND CURRENCY FEATURES
Five boys with Prader-Willi syndrome were examined at the endocrinologist by 2016. All children had minimal diagnostic signs of the syndrome, namely: muscular hypotension, hypogonadism, obesity, mental retardation of varying severity, small hands and feet. In two children there was a disruption of glucose tolerance. All patients had the manifestation of hypergonadotropic hypogonadism. If a minimal diagnostic criteria are found in the newborn, a genetic analysis is necessary
Quantitative analysis of quantum phase slips in superconducting MoGe nanowires revealed by switching-current statistics
We measure quantum and thermal phase-slip rates using the standard deviation
of the switching current in superconducting nanowires at high bias current. Our
rigorous quantitative analysis provides firm evidence for the presence of
quantum phase slips (QPS) in homogeneous nanowires. We observe that as
temperature is lowered, thermal fluctuations freeze at a characteristic
crossover temperature Tq, below which the dispersion of the switching current
saturates to a constant value, indicating the presence of QPS. The scaling of
the crossover temperature Tq with the critical temperature Tc is linear, which
is consistent with the theory of macroscopic quantum tunneling. We can convert
the wires from the initial amorphous phase to a single crystal phase, in situ,
by applying calibrated voltage pulses. This technique allows us to probe
directly the effects of the wire resistance, critical temperature and
morphology on thermal and quantum phase slips.Comment: 7 pages, 7 figures, 1 tabl
Half-Quantum Vortices in Thin Film of Superfluid He
Stability of a half-quantum vortex (HQV) in superfluid He has been
discussed recently by Kawakami, Tsutsumi and Machida in Phys. Rev. B {\bf 79},
092506 (2009). We further extend this work here and consider the A phase of
superfluid He confined in thin slab geometry and analyze the HQV realized
in this setting. Solutions of HQV and singly quantized singular vortex are
evaluated numerically by solving the Ginzburg-Landau (GL) equation and
respective first critical angular velocities are obtained by employing these
solutions. We show that the HQV in the A phase is stable near the boundary
between the A and A phases. It is found that temperature and magnetic
field must be fixed first in the stable region and subsequently the angular
velocity of the system should be increased from zero to a sufficiently large
value to create a HQV with sufficiently large probability. A HQV does not form
if the system starts with a fixed angular velocity and subsequently the
temperature is lowered down to the A phase. It is estimated that the
external magnetic field with strength on the order of 1 T is required to have a
sufficiently large domain in the temperature-magnetic field phase diagram to
have a stable HQV.Comment: 5 pages, 5 figure
Magnetic Response in the Holographic Insulator/Superconductor Transition
We study the magnetic response of holographic superconductors exhibiting an
insulating "normal" phase. These materials can be realized as a CFT
compactified on a circle, which is dual to the AdS Soliton geometry. We study
the response under i) magnetic fields and ii) a Wilson line on the circle.
Magnetic fields lead to formation of vortices and allows one to infer that the
superconductor is of type II. The response to a Wilson line is in the form of
Aharonov-Bohm-like effects. These are suppressed in the holographic
conductor/superconductor transition but, instead, they are unsuppressed for the
insulator case. Holography, thus, predicts that generically insulators display
stronger Aharonov-Bohm effects than conductors. In the fluid-mechanical limit
the AdS Soliton is interpreted as a supersolid. Our results imply that
supersolids display unsuppressed Aharonov-Bohm (or "Sagnac") effects - stronger
than in superfluids.Comment: 31 pages, 24 figures; discussion on vortex lattice, few comments and
references added; article published in JHE
Evaluation of Spin-Triplet Superconductivity in Sr2RuO4
This review presents a summary and evaluations of the superconducting
properties of the layered ruthenate Sr2RuO4 as they are known in the autumn of
2011. This paper appends the main progress that has been made since the
preceding review by Mackenzie and Maeno was published in 2003. Here, special
focus is placed on the critical evaluation of the spin-triplet, odd-parity
pairing scenario applied to Sr2RuO4. After an introduction to superconductors
with possible odd-parity pairing, accumulated evidence for the pairing symmetry
of Sr2RuO4 is examined. Then, significant recent progress on the theoretical
approaches to the superconducting pairing by Coulomb repulsion is reviewed. A
section is devoted to some experimental properties of Sr2RuO4 that seem to defy
simple explanations in terms of currently available spin-triplet scenario. The
next section deals with some new developments using eutectic boundaries and
micro-crystals, which reveals novel superconducting phenomena related to chiral
edge states, odd-frequency pairing states, and half-fluxoid states. Some of
these properties are intimately connected with the properties as a topological
superconductor. The article concludes with a summary of knowledge emerged from
the study of Sr2RuO4 that are now more widely applied to understand the physics
of other unconventional superconductors, as well as with a brief discussion of
relatively unexplored but promising areas of ongoing and future studies of
Sr2RuO4.Comment: 31 pages, 35 figures, published in J. Phys. Soc. Jpn. as a review
article of Special Topic
Universal Features of Counting Statistics of Thermal and Quantum Phase Slips in Nanosize Superconducting Circuits
Superconducting state evolution with applied magnetic flux in mesoscopic rings
The magnetic flux dependence of the vortex state for small mesoscopic superconducting
rings surrounded by a medium is investigated by the phenomenological Ginzburg-Landau
theory. The influences of the ring size and the surface superconductivity on the free
energy and total supercurrent are studied. For narrow rings, the persistent current
evolves towards a periodic behaviour with magnetic flux. The complete paramagnetic or
diamagnetic state, corresponding to positive or negative current flowing in the whole
ring, can occur. A remarkable intermittent superconducting behaviour for the ground-state
transition is found when the strength of surface-suppressed superconductivity is enlarged
or the ring size is decreased. Consequently, a pure superconducting state with positive
total current can be obtained