1,386 research outputs found
Multiple organ dysfunction caused by parathyroid adenoma‑induced primary hyperparathyroidism
We present a 27‑year‑old male with multiple organ dysfunction caused by parathyroid adenoma‑induced primary hyperparathyroidism (PHPT). Initially, the patient experienced a sudden onset of gastrointestinal symptoms, polyuria, polydipsia, bone pain, renal dysfunction, nephrolithiasis, and acute pancreatitis, symptoms associated with hypercalcemia. Biochemical findings suggested PHPT. Renal biopsy showed an acute tubular injury and massive calcium deposits in the tubular epithelial cells and tubular lumina. Moreover, neck ultrasonography suggested the possibility of a parathyroid tumor. We excised his right parathyroid gland. Histopathological analysis revealed features of a parathyroid adenoma. Post‑operatively this patient had normal serum calcium concentration, but was renally insufficient. A recent repeat biopsy showed chronic renal tubular injury. Our findings illustrate the complications of various systems that can occur in patients with PHPT caused by a parathyroid adenoma.Key words: Hypercalcemia, parathyroid adenoma, parathyroid hormone, primary hyperparathyroidis
The Pairing Mechanism in HTSC investigated by Electronic Raman Scattering
By means of electronic Raman scattering we investigated the symmetry of the
energy gap Delta(k), its temperature dependence and its variation with doping
of well characterized Bi2Sr2CaCu2O8+delta single crystals. The oxygen content
delta was varied between the under- and the overdoped regime by subsequently
annealing the same single crystal in Ar and O2, respectively. The symmetry
analysis of the polarized electronic Raman scattering is consistent with a
d_x^2-y^2-wave symmetry of the energy gap in both regimes. The gap ratio
2Delta_max/k_BT_c and its temperature dependence changes with doping similar to
predictions of theories based on paramagnon coupling.Comment: 3 pages, LaTeX, 2 ps figures available on request to
[email protected]
Effect of a Normal-State Pseudogap on Optical Conductivity in Underdoped Cuprate Superconductors
We calculate the c-axis infrared conductivity in
underdoped cuprate superconductors for spinfluctuation exchange scattering
within the CuO-planes including a phenomenological d-wave pseudogap of
amplitude . For temperatures decreasing below a temperature , a gap for develops in in the
incoherent (diffuse) transmission limit. The resistivity shows 'semiconducting'
behavior, i.e. it increases for low temperatures above the constant behavior
for . We find that the pseudogap structure in the in-plane optical
conductivity is about twice as big as in the interplane conductivity
, in qualitative agreement with experiment. This is a
consequence of the fact that the spinfluctuation exchange interaction is
suppressed at low frequencies as a result of the opening of the pseudogap.
While the c-axis conductivity in the underdoped regime is described best by
incoherent transmission, in the overdoped regime coherent conductance gives a
better description.Comment: to be published in Phys. Rev. B (November 1, 1999
Reduction of Tc due to Impurities in Cuprate Superconductors
In order to explain how impurities affect the unconventional
superconductivity, we study non-magnetic impurity effect on the transition
temperature using on-site U Hubbard model within a fluctuation exchange (FLEX)
approximation. We find that in appearance, the reduction of Tc roughly
coincides with the well-known Abrikosov-Gor'kov formula. This coincidence
results from the cancellation between two effects; one is the reduction of
attractive force due to randomness, and another is the reduction of the damping
rate of quasi-particle arising from electron interaction. As another problem,
we also study impurity effect on underdoped cuprate as the system showing
pseudogap phenomena. To the aim, we adopt the pairing scenario for the
pseudogap and discuss how pseudogap phenomena affect the reduction of Tc by
impurities. We find that 'pseudogap breaking' by impurities plays the essential
role in underdoped cuprate and suppresses the Tc reduction due to the
superconducting (SC) fluctuation.Comment: 14 pages, 28 figures To be published in JPS
Application of Deep Learning Long Short-Term Memory in Energy Demand Forecasting
The smart metering infrastructure has changed how electricity is measured in
both residential and industrial application. The large amount of data collected
by smart meter per day provides a huge potential for analytics to support the
operation of a smart grid, an example of which is energy demand forecasting.
Short term energy forecasting can be used by utilities to assess if any
forecasted peak energy demand would have an adverse effect on the power system
transmission and distribution infrastructure. It can also help in load
scheduling and demand side management. Many techniques have been proposed to
forecast time series including Support Vector Machine, Artificial Neural
Network and Deep Learning. In this work we use Long Short Term Memory
architecture to forecast 3-day ahead energy demand across each month in the
year. The results show that 3-day ahead demand can be accurately forecasted
with a Mean Absolute Percentage Error of 3.15%. In addition to that, the paper
proposes way to quantify the time as a feature to be used in the training phase
which is shown to affect the network performance
Asymmetric Fermi superfluid in a harmonic trap
We consider a dilute two-component atomic fermion gas with unequal
populations in a harmonic trap potential using the mean field theory and the
local density approximation. We show that the system is phase separated into
concentric shells with the superfluid in the core surrounded by the normal
fermion gas in both the weak-coupling BCS side and near the Feshbach resonance.
In the strong-coupling BEC side, the composite bosons and left-over fermions
can be mixed. We calculate the cloud radii and compare axial density profiles
systemically for the BCS, near resonance and BEC regimes.Comment: 15 pages, 5 figure
Nitrogen-Functionalized Graphene Nanoflakes (GNFs:N): Tunable Photoluminescence and Electronic Structures
This study investigates the strong photoluminescence (PL) and X-ray excited
optical luminescence observed in nitrogen-functionalized 2D graphene nanoflakes
(GNFs:N), which arise from the significantly enhanced density of states in the
region of {\pi} states and the gap between {\pi} and {\pi}* states. The
increase in the number of the sp2 clusters in the form of pyridine-like N-C,
graphite-N-like, and the C=O bonding and the resonant energy transfer from the
N and O atoms to the sp2 clusters were found to be responsible for the blue
shift and the enhancement of the main PL emission feature. The enhanced PL is
strongly related to the induced changes of the electronic structures and
bonding properties, which were revealed by the X-ray absorption near-edge
structure, X-ray emission spectroscopy, and resonance inelastic X-ray
scattering. The study demonstrates that PL emission can be tailored through
appropriate tuning of the nitrogen and oxygen contents in GNFs and pave the way
for new optoelectronic devices.Comment: 8 pages, 6 figures (including toc figure
Superconductivity in the quasi-two-dimensional Hubbard model
On the basis of spin and pairing fluctuation-exchange approximation, we study
the superconductivity in quasi-two-dimensional Hubbard model. The integral
equations for the Green's function are self-consistently solved by numerical
calculation. Solutions for the order parameter, London penetration depth,
density of states, and transition temperature are obtained. Some of the results
are compared with the experiments for the cuprate high-temperature
superconductors. Numerical techniques are presented in details. With these
techniques, the amount of numerical computation can be greatly reduced.Comment: 17 pages, 13 figure
Homogeneous Fermion Superfluid with Unequal Spin Populations
For decades, the conventional view is that an s-wave BCS superfluid can not
support uniform spin polarization due to a gap in the quasiparticle
excitation spectrum. We show that this is an artifact of the dismissal of
quasiparticle interactions in the conventional approach at the
outset. Such interactions can cause triplet fluctuations in the ground state
and hence non-zero spin polarization at "magnetic field" . The
resulting ground state is a pairing state of quasiparticles on the ``BCS
vacuum". For sufficiently large , the spin polarization of at unitarity
has the simple form . Our study is motivated by the recent
experiments at Rice which found evidence of a homogenous superfluid state with
uniform spin polarization.Comment: 4 pages, 3 figure
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