32 research outputs found
Multi-task Neural Network for Non-discrete Attribute Prediction in Knowledge Graphs
Many popular knowledge graphs such as Freebase, YAGO or DBPedia maintain a
list of non-discrete attributes for each entity. Intuitively, these attributes
such as height, price or population count are able to richly characterize
entities in knowledge graphs. This additional source of information may help to
alleviate the inherent sparsity and incompleteness problem that are prevalent
in knowledge graphs. Unfortunately, many state-of-the-art relational learning
models ignore this information due to the challenging nature of dealing with
non-discrete data types in the inherently binary-natured knowledge graphs. In
this paper, we propose a novel multi-task neural network approach for both
encoding and prediction of non-discrete attribute information in a relational
setting. Specifically, we train a neural network for triplet prediction along
with a separate network for attribute value regression. Via multi-task
learning, we are able to learn representations of entities, relations and
attributes that encode information about both tasks. Moreover, such attributes
are not only central to many predictive tasks as an information source but also
as a prediction target. Therefore, models that are able to encode, incorporate
and predict such information in a relational learning context are highly
attractive as well. We show that our approach outperforms many state-of-the-art
methods for the tasks of relational triplet classification and attribute value
prediction.Comment: Accepted at CIKM 201
Even-Odd Layer-Dependent Anomalous Hall Effect in Topological Magnet MnBi2Te4 Thin Films
A central theme in condensed matter physics is to create and understand the
exotic states of matter by incorporating magnetism into topological materials.
One prime example is the quantum anomalous Hall (QAH) state. Recently, MnBi2Te4
has been demonstrated to be an intrinsic magnetic topological insulator and the
QAH effect was observed in exfoliated MnBi2Te4 flakes. Here, we used molecular
beam epitaxy (MBE) to grow MnBi2Te4 films with thickness down to 1 septuple
layer (SL) and performed thickness-dependent transport measurements. We
observed a non-square hysteresis loop in the antiferromagnetic state for films
with thickness greater than 2 SL. The hysteresis loop can be separated into two
AH components. Through careful analysis, we demonstrated that one AH component
with the larger coercive field is from the dominant MnBi2Te4 phase, while the
other AH component with the smaller coercive field is from the minor Mn-doped
Bi2Te3 phase in the samples. The extracted AH component of the MnBi2Te4 phase
shows a clear even-odd layer-dependent behavior, a signature of
antiferromagnetic thin films. Our studies reveal insights on how to optimize
the MBE growth conditions to improve the quality of MnBi2Te4 films, in which
the QAH and other exotic states are predicted.Comment: 23 pages, 4 figures, comments are welcom
Differences in the gas and dust distribution in the transitional disk of a sun-like young star, PDS 70
We present ALMA 0.87 mm continuum, HCO+ J=4--3 emission line, and CO J=3--2
emission line data of the disk of material around the young, Sun-like star PDS
70. These data reveal the existence of a possible two component transitional
disk system with a radial dust gap of 0."2 +/- 0."05, an azimuthal gap in the
HCO+ J=4--3 moment zero map, as well as two bridge-like features in the gas
data. Interestingly these features in the gas disk have no analogue in the dust
disk making them of particular interest. We modeled the dust disk using the
Monte Carlo radiative transfer code HOCHUNK3D (Whitney et al. 2013) using a two
disk components. We find that there is a radial gap that extends from 15-60 au
in all grain sizes which differs from previous work
Electrical Switching of the Edge Current Chirality in Quantum Anomalous Hall Insulators
A quantum anomalous Hall (QAH) insulator is a topological state of matter, in
which the interior is insulating but electrical current flows along the edges
of the sample, in either clockwise (right-handed) or counter-clockwise
(left-handed) direction dictated by the spontaneous magnetization orientation.
Such chiral edge current (CEC) eliminates any backscattering, giving rise to
quantized Hall resistance and zero longitudinal resistance. In this work, we
fabricate mesoscopic QAH sandwich (i.e. magnetic topological insulator
(TI)/TI/magnetic TI) Hall bar devices and succeed in switching the CEC
chirality in QAH insulators through spin-orbit torque (SOT) by applying a
current pulse and suitably controlled gate voltage. The well-quantized QAH
states with opposite CEC chiralities are demonstrated through four- and
three-terminal measurements before and after SOT switching. Our theoretical
calculations show that the SOT that enables the magnetization switching can be
generated by both bulk and surface carriers in QAH insulators, in good
agreement with experimental observations. Current pulse-induced switching of
the CEC chirality in QAH insulators will not only advance our knowledge in the
interplay between magnetism and topological states but also expedite easy and
instantaneous manipulation of the QAH state in proof-of-concept
energy-efficient electronic and spintronic devices as well as quantum
information applications.Comment: 24 pages, 5 figures, comments are welcom
Interface-Induced Superconductivity in Magnetic Topological Insulator-Iron Chalcogenide Heterostructures
When two different electronic materials are brought together, the resultant
interface often shows unexpected quantum phenomena, including interfacial
superconductivity and Fu-Kane topological superconductivity (TSC). Here, we use
molecular beam epitaxy (MBE) to synthesize heterostructures formed by stacking
together two magnetic materials, a ferromagnetic topological insulator (TI) and
an antiferromagnetic iron chalcogenide (FeTe). We discover emergent
interface-induced superconductivity in these heterostructures and demonstrate
the trifecta occurrence of superconductivity, ferromagnetism, and topological
band structure in the magnetic TI layer, the three essential ingredients of
chiral TSC. The unusual coexistence of ferromagnetism and superconductivity can
be attributed to the high upper critical magnetic field that exceeds the Pauli
paramagnetic limit for conventional superconductors at low temperatures. The
magnetic TI/FeTe heterostructures with robust superconductivity and atomically
sharp interfaces provide an ideal wafer-scale platform for the exploration of
chiral TSC and Majorana physics, constituting an important step toward scalable
topological quantum computation.Comment: 14 pages, 4 figures. Accepted by Science. Comments are welcom
Subaru/HiCIAO imaging of LkH 330 - multi-band detection of the gap and spiral-like structures
We present - and -bands observations of the LkH 330
disk with a multi-band detection of the large gap and spiral-like structures.
The morphology of the outer disk (0\farcs3) at PA=0--45 and
PA=180--290 are likely density wave-induced spirals and comparison
between our observational results and simulations suggests a planet formation.
We have also investigated the azimuthal profiles at the ring and the outer-disk
regions as well as radial profiles in the directions of the spiral-like
structures and semi-major axis. Azimuthal analysis shows a large variety in
wavelength and implies that the disk has non-axisymmetric dust distributions.
The radial profiles in the major-axis direction (PA=) suggest that
the outer region (r\geq0\farcs25) may be influenced by shadows of the inner
region of the disk. The spiral-like directions (PA=10 and 230)
show different radial profiles, which suggests that the surfaces of the
spiral-like structures are highly flared and/or have different dust properties.
Finally, a color-map of the disk shows a lack of an outer eastern region in the
-band disk, which may hint the presence of an inner object that casts a
directional shadow onto the disk.Comment: 12pages, 16 figures, 2 tables, accepted for publication in A
SUBARU Near-Infrared Imaging Polarimetry of Misaligned Disks Around The SR24 Hierarchical Triple System
The SR24 multi-star system hosts both circumprimary and circumsecondary
disks, which are strongly misaligned from each other. The circumsecondary disk
is circumbinary in nature. Interestingly, both disks are interacting, and they
possibly rotate in opposite directions. To investigate the nature of this
unique twin disk system, we present 0.''1 resolution near-infrared polarized
intensity images of the circumstellar structures around SR24, obtained with
HiCIAO mounted on the Subaru 8.2 m telescope. Both the circumprimary disk and
the circumsecondary disk are resolved and have elongated features. While the
position angle of the major axis and radius of the NIR polarization disk around
SR24S are 55 and 137 au, respectively, those around SR24N are
110 and 34 au, respectively. With regard to overall morphology, the
circumprimary disk around SR24S shows strong asymmetry, whereas the
circumsecondary disk around SR24N shows relatively strong symmetry. Our NIR
observations confirm the previous claim that the circumprimary and
circumsecondary disks are misaligned from each other. Both the circumprimary
and circumsecondary disks show similar structures in CO observations in
terms of its size and elongation direction. This consistency is because both
NIR and CO are tracing surface layers of the flared disks. As the radius
of the polarization disk around SR24N is roughly consistent with the size of
the outer Roche lobe, it is natural to interpret the polarization disk around
SR24N as a circumbinary disk surrounding the SR24Nb-Nc system.Comment: 14 pages, 5 figures, accepted for publication in A
Value of contrast-enhanced ultrasound for preoperative assessment of liver reserve function in patients with liver tumors.
This study aimed to investigate the value of contrast-enhanced ultrasound (CEUS) for preoperative assessment of liver reserve function in patients with liver tumors. The indocyanine green (ICG) clearance tests and CEUS examinations of 45 noncirrhotic patients with liver tumors were performed prior to liver resection. Parameters time to peak (TtoPk), arrival time (Atm) as well as perfusion parameters A, k and A x k were generated from time-intensity curve (TIC) of CEUS. The correlation analyses of the ICG clearance per unit time (ICGK) and the retention rate at 15 min (ICGR15) with TtoPk, Atm, A, k and A x k were performed, and the diagnostic ability as well as optimal cut-off values of TtoPk and Atm for differentiating patients with ICGR15>10% from ICGR1510% and ICGR1510% verusus ICGR1510% vs ICGR15, the optimal cut-off values of TtoPk and Atm were 13.307 s and 11.007 s, respectively, while the sensitivity and specificity were 75.0% and 72.7%, 60.6% and 75.0%, respectively. This study revealed that CEUS has the potential to be a new method to evaluate the liver reserve function of patients. With the optimal cut-off values of TtoPk and Atm, qualitative assessment of patients with ICGR15>10% could be more easily achieved by CEUS with good diagnostic abilities