951 research outputs found
On Topology of the Moduli Space of Gapped Hamiltonians for Topological Phases
The moduli space of gapped Hamiltonians that are in the same topological
phase is an intrinsic object that is associated to the topological order. The
topology of these moduli spaces is used recently in the construction of Floquet
codes. We propose a systematical program to study the topology of these moduli
spaces. In particular, we use effective field theory to study the cohomology
classes of these spaces, which includes and generalizes the Berry phase. We
discuss several applications to studying phase transitions. We show that
nontrivial family of gapped systems with the same topological order can protect
isolated phase transitions in the phase diagram, and we argue that the phase
transitions are characterized by screening of topological defects. We argue
that family of gapped systems obey a version of bulk-boundary correspondence.
We show that family of gapped systems in the bulk with the same topological
order can rule out family of gapped systems on the boundary with the same
topological boundary condition, constraining phase transitions on the boundary.Comment: 37 pages, 2 figure
An Effective Field Theory for Fractional Quantum Hall Systems near
We propose an effective field theory (EFT) of fractional quantum Hall systems
near the filling fraction that flows to pertinent IR candidate
phases, including non-abelian Pfaffian, anti-Pfaffian, and particle-hole
Pfaffian states (Pf, APf, and PHPf). Our EFT has a 2+1 O(2)
Chern-Simons gauge theory coupled to four Majorana fermions by a discrete
charge conjugation gauge field, with Gross-Neveu-Yukawa-Higgs terms. Including
deformations via a Higgs condensate and fermion mass terms, we can map out a
phase diagram with tunable parameters, reproducing the prediction of the
recently-proposed percolation picture and its gapless topological quantum phase
transitions. Our EFT captures known features of both gapless and gapped sectors
of time-reversal-breaking domain walls between Pf and APf phases. Moreover, we
find that PfAPf domain walls have higher tension than domain walls in the
PHPf phase. Then the former, if formed, may transition to the
energetically-favored PHPf domain walls; this could, in turn, help further
induce a bulk transition to PHPf.Comment: 72 pages, 10 figures, 5 tables. Many appendices. Add Sec 2.2, new
remarks in Conclusion, and other clarifications. Accepted by Physical Review
Researc
An hourglass model for the flare of HST-1 in M87
To explain the multi-wavelength light curves (from radio to X-ray) of HST-1
in the M87 jet, we propose an hourglass model that is a modified two-zone
system of Tavecchio & Ghisellini (hereafter TG08): a slow hourglass-shaped or
Laval nozzle-shaped layer connected by two revolving exponential surfaces
surrounding a fast spine, through which plasma blobs flow. Based on the
conservation of magnetic flux, the magnetic field changes along the axis of the
hourglass. We adopt the result of TG08---the high-energy emission from GeV to
TeV can be produced through inverse Compton by the two-zone system, and the
photons from radio to X-ray are mainly radiated by the fast inner zone system.
Here, we only discuss the light curves of the fast inner blob from radio to
X-ray. When a compressible blob travels down the axis of the first bulb in the
hourglass, because of magnetic flux conservation, its cross section experiences
an adiabatic compression process, which results in particle acceleration and
the brightening of HST-1. When the blob moves into the second bulb of the
hourglass, because of magnetic flux conservation, the dimming of the knot
occurs along with an adiabatic expansion of its cross section. A similar broken
exponential function could fit the TeV peaks in M87, which may imply a
correlation between the TeV flares of M87 and the light curves from radio to
X-ray in HST-1. The Very Large Array (VLA) 22 GHz radio light curve of HST-1
verifies our prediction based on the model fit to the main peak of the VLA 15
GHz radio light curve.Comment: 14 pages, 2 figures, accepted for publication in A
Effective field theory for fractional quantum Hall systems near ν = 5/2
We propose an effective field theory (EFT) of fractional quantum Hall systems near the filling fraction ν = 5/2 that flows to pertinent IR candidate phases, including non-Abelian Pfaffian, anti-Pfaffian, and particle-hole Pfaffian states (Pf, APf, and PHPf). Our EFT has a (2+1)D O(2)_(2,L) Chern-Simons gauge theory coupled to four Majorana fermions by a discrete charge-conjugation gauge field, with Gross-Neveu-Yukawa-Higgs terms. Including deformations via a Higgs condensate and fermion mass terms, we can map out a phase diagram with tunable parameters, reproducing the prediction of the recently proposed percolation picture and its gapless topological quantum phase transitions. Our EFT captures known features of both gapless and gapped sectors of time-reversal-breaking domain walls between Pf and APf phases. Moreover, we find that Pf∣APf domain walls have higher tension than domain walls in the PHPf phase. Then the former, if formed, may transition to the energetically favored PHPf domain walls; this could, in turn, help further induce a bulk transition to PHPf
Effective field theory for fractional quantum Hall systems near ν = 5/2
We propose an effective field theory (EFT) of fractional quantum Hall systems near the filling fraction ν = 5/2 that flows to pertinent IR candidate phases, including non-Abelian Pfaffian, anti-Pfaffian, and particle-hole Pfaffian states (Pf, APf, and PHPf). Our EFT has a (2+1)D O(2)_(2,L) Chern-Simons gauge theory coupled to four Majorana fermions by a discrete charge-conjugation gauge field, with Gross-Neveu-Yukawa-Higgs terms. Including deformations via a Higgs condensate and fermion mass terms, we can map out a phase diagram with tunable parameters, reproducing the prediction of the recently proposed percolation picture and its gapless topological quantum phase transitions. Our EFT captures known features of both gapless and gapped sectors of time-reversal-breaking domain walls between Pf and APf phases. Moreover, we find that Pf∣APf domain walls have higher tension than domain walls in the PHPf phase. Then the former, if formed, may transition to the energetically favored PHPf domain walls; this could, in turn, help further induce a bulk transition to PHPf
Childhood tuberculosis in southern Taiwan, with emphasis on central nervous system complications
Background/PurposeChildhood tuberculosis (TB) continues to be a major public health problem in Taiwan. Taiwan remains a highly endemic area despite neonatal Bacillus Calmette–Guérin (BCG) vaccination and the availability of anti-TB therapy. The presentation is highly variable and it is often difficult to make an accurate diagnosis. This study was designed to evaluate the demographic, clinical, and laboratory findings and outcomes of TB in children with emphasis on central nervous system (CNS) complications.MethodsThe medical records of 80 children diagnosed with TB at a medical center in southern Taiwan over the past 24 years (1988–2012) were reviewed.ResultsAmong them, 48.8% (39/80) had pulmonary TB, 27.5% (22/80) had isolated extrapulmonary TB, and 23.7% (19/80) had disseminated TB. Most infected cases were aged either < 4 years or > 12 years. TB contact history was found in 42.5% (34/80) cases. Fourteen (17.5%) of the cases had CNS involvement. The most common presentations were fever (85.7%), signs of increased intracranial pressure (71.4%), drowsiness (64.3%), and focal neurological signs (57.1%). The major radiological findings were tuberculoma (50%), basilar enhancement (41.6%), infarction (41.6%), hydrocephalus (16.6%), and transverse myelitis (16.6%). The case fatality of CNS TB was 14.3% and 21.4% had neurologic sequelae.ConclusionFindings suggest that positive exposure history and suspicious clinical presentations are important clues for further confirmatory laboratory and image studies in childhood TB. CNS TB usually presented as part of disseminated TB in children. Early diagnosis and treatment may lead to favorable outcomes in CNS TB
Real-time Automatic M-mode Echocardiography Measurement with Panel Attention from Local-to-Global Pixels
Motion mode (M-mode) recording is an essential part of echocardiography to
measure cardiac dimension and function. However, the current diagnosis cannot
build an automatic scheme, as there are three fundamental obstructs: Firstly,
there is no open dataset available to build the automation for ensuring
constant results and bridging M-mode echocardiography with real-time instance
segmentation (RIS); Secondly, the examination is involving the time-consuming
manual labelling upon M-mode echocardiograms; Thirdly, as objects in
echocardiograms occupy a significant portion of pixels, the limited receptive
field in existing backbones (e.g., ResNet) composed from multiple convolution
layers are inefficient to cover the period of a valve movement. Existing
non-local attentions (NL) compromise being unable real-time with a high
computation overhead or losing information from a simplified version of the
non-local block. Therefore, we proposed RAMEM, a real-time automatic M-mode
echocardiography measurement scheme, contributes three aspects to answer the
problems: 1) provide MEIS, a dataset of M-mode echocardiograms for instance
segmentation, to enable consistent results and support the development of an
automatic scheme; 2) propose panel attention, local-to-global efficient
attention by pixel-unshuffling, embedding with updated UPANets V2 in a RIS
scheme toward big object detection with global receptive field; 3) develop and
implement AMEM, an efficient algorithm of automatic M-mode echocardiography
measurement enabling fast and accurate automatic labelling among diagnosis. The
experimental results show that RAMEM surpasses existing RIS backbones (with
non-local attention) in PASCAL 2012 SBD and human performances in real-time
MEIS tested. The code of MEIS and dataset are available at
https://github.com/hanktseng131415go/RAME
Refractory gastric variceal bleeding secondary to splenic vein occlusion associated with abdominal lymphadenopathy
SummarySplenic vein occlusion caused by abdominal lymphadenopathy is rare. We herein present the case of a 80-year-old man with refractory isolated gastric variceal bleeding in the absence of pancreatic or liver disease. Left-sided portal hypertension was confirmed by angiography, and para-aortic lymphadenopathy compressing the splenic vein was identified by serial abdominal computed tomography. Endoscopic sclerosing therapy failed to treat the recurring gastric variceal hemorrhage. Therefore, splenectomy was suggested and the patient was successfully treated. The patient had been variceal bleeding free for 12 months since the surgery. In patients with isolated gastric varices but without advanced liver disease, a variety of diagnostic techniques should be attempted to elucidate the nature of portal hypertension, and left-sided portal hypertension should be suspected. For those cases in which endoscopic treatment failed to treat refractory gastric variceal bleeding, splenectomy can be an effective option
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