131 research outputs found
Loop-current charge density wave driven by long-range Coulomb repulsion on the kagome lattice
Recent experiments on vanadium-based nonmagnetic kagom\'e metals
VSb ( K, Rb, Cs) revealed evidence for possible spontaneous
time-reversal symmetry (TRS) breaking in the charge density wave (CDW) ordered
state. The long-sought-after quantum order of loop currents has been suggested
as a candidate for the TRS breaking state. However, a microscopic model for the
emergence of the loop-current CDW due to electronic correlations is still
lacking. Here, we calculate the susceptibility of the real and imaginary bond
orders on the kagom\'e lattice near van Hove filling, and reveal the importance
of next-nearest-neighbor Coulomb repulsion in triggering the instability
toward imaginary bond ordered CDW. The concrete effective single-orbital
-- model on the kagom\'e lattice is then studied, where and
are the hopping and Coulomb repulsion on the nearest-neighbor bonds. We
obtain the mean-field ground states, analyze their properties, and determine
the phase diagram in the plane spanned by and at van Hove filling.
The region dominated by is occupied by a real CDW
insulator with the inverse of Star-of-David (ISD) bond configuration.
Increasing indeed drives a first-order transition from the ISD to
stabilized loop-current insulators that exhibit four possible current patterns
of different topological properties, leading to orbital Chern insulators. We
then extend these results away from van Hove filling and show that the
loop-current states survive in the lightly doped orbital Chern insulators, and
give rise to emergent Chern Fermi pockets carrying large Berry curvature and
orbit magnetic moment. Our findings provide a concrete model realization of the
loop-current Chern metal at the mean-field level for the TRS breaking normal
state of the kagom\'e superconductors.Comment: 11 pages, 6 figure
Microscopic model realization of -wave pseudospin current order in SrIrO
The -wave pseudospin current order (PSCO) with staggered circulating
pseudospin current has been proposed as the hidden electronic order to describe
the unexpected breaking of spatial symmetries in stoichiometric
SrIrO and the unconventional pseudogap phenomena in electron doped
SrIrO. However, a microscopic model for the emergence of PSCO is
still lacking. The nearest neighbor Coulomb repulsion , which is expected to
be significant in SrIrO due to the large spatial extension of the
Ir orbitals, is capable of driving PSCO on the mean-field level, albeit
the latter is energetically degenerate to the staggered flux phase with
circulating charge current. We find the in-plane anisotropy in the
effective superexchange interaction between
pseudospins, originating from the cooperative interplay between Hund's rule
coupling and spin-orbit coupling of Ir electrons, is able to lift the
degeneracy and stabilize the pseudospin currents. The effective single-orbital
model of electrons, including onsite Coulomb
repulsion , nearest neighbor Coulomb repulsion , and the in-plane
anisotropy , is then studied. We obtain the mean-field ground states,
analyze their properties, and determine the phase diagram of stoichiometric
SrIrO in the plane spanned by and at a fixed . We
demonstrate the realization of PSCO, and its competition and coexistence
with antiferromagnetism. Remarkably, we find the coexistence of PSCO and
antiferromagnetism naturally leads to spin bond nematicity, with the spin
directions of these three orders forming nontrivial chirality. Furthermore, we
show that the emergence of the coexistent state and its chirality can be tuned
by carrier doping.Comment: 12 pages, 10 figure
Survival of AIDS Patients Treated with Traditional Chinese Medicine in Rural Central China: A Retrospective Cohort Study, 2004β2012
This study aimed to explore the survival of AIDS patients treated with traditional Chinese medicine (TCM) in addition to combined antiretroviral therapy (cART) and of AIDS patients treated with cART. Data of patients taking cART between 30 October 2003 and 30 October 2004 in the National TCM HIV Treatment Trial Program area were retrospectively analyzed, with follow-up from 30 October 2004 to 30 October 2012. The log-rank test was used to compare survival between the two groups. A Cox proportional hazards model was used to determine hazard ratios to identify prognostic factors. The study included 521 patients in the TCM + cART group followed up for 3548 person-years and 375 patients in the cART group followed up for 2523 person-years. Mortality rates were 3.2/100 person-years and 4.2/100 person-years in the TCM + cART and cART groups, respectively. The difference in survival was significant. After adjusting for explanatory variables, the mortality rate of AIDS patients in the cART group was 1.7 times higher than in the TCM + cART group. Male sex, older age, little education, and lower CD4 cell count were risk factors for mortality. TCM intervention in addition to cART could increase survival of AIDS patients
Optimizing the Use of Solid-Phase Reversible Immobilization Beads for High-Throughput Full-Length 16S rDNA Sequencing Library Construction
Solid-phase reversible immobilization (SPRI) beads are widely used for high-throughput sequencing library construction to purify and recover nucleic acids. This research was aimed at investigating the effects of SPRI bead ratio, incubation time, and elution time on nucleic acid recovery during full-length 16S rDNA high-throughput sequencing library construction. The effects of different SPRI bead ratios, incubation times, and elution times were compared for three different initial sample amounts. An L9(3 3 ) orthogonal experiment was designed to determine the optimal combination of these factors. The incubation time of three factors including SPRI beads ratio, incubation time, and elution time had a statistically significant effect on the recovery rate for the initial sample amount of 1500 ng and 3000 ng. The orthogonal experiment results indicated that incubation time had the greatest impact among the three factors. Incubation time significantly influences recovery rate in full-length 16S rDNA high-throughput sequencing library construction. The use of 0.8Γ SPRI beads, 15 minutes of incubation, and 10 minutes of elution resulted in the highest recovery rate. SPRI beads offer a viable method for recovering full-length 16S rDNA amplicons
Closed-Loop Unsupervised Representation Disentanglement with -VAE Distillation and Diffusion Probabilistic Feedback
Representation disentanglement may help AI fundamentally understand the real
world and thus benefit both discrimination and generation tasks. It currently
has at least three unresolved core issues: (i) heavy reliance on label
annotation and synthetic data -- causing poor generalization on natural
scenarios; (ii) heuristic/hand-craft disentangling constraints make it hard to
adaptively achieve an optimal training trade-off; (iii) lacking reasonable
evaluation metric, especially for the real label-free data. To address these
challenges, we propose a \textbf{C}losed-\textbf{L}oop unsupervised
representation \textbf{Dis}entanglement approach dubbed \textbf{CL-Dis}.
Specifically, we use diffusion-based autoencoder (Diff-AE) as a backbone while
resorting to -VAE as a co-pilot to extract semantically disentangled
representations. The strong generation ability of diffusion model and the good
disentanglement ability of VAE model are complementary. To strengthen
disentangling, VAE-latent distillation and diffusion-wise feedback are
interconnected in a closed-loop system for a further mutual promotion. Then, a
self-supervised \textbf{Navigation} strategy is introduced to identify
interpretable semantic directions in the disentangled latent space. Finally, a
new metric based on content tracking is designed to evaluate the
disentanglement effect. Experiments demonstrate the superiority of CL-Dis on
applications like real image manipulation and visual analysis
Unusual double-peak specific heat and spin freezing in a spin-2 triangular lattice antiferromagnet FeAlSe
We report the properties of a triangular lattice iron-chalcogenide
antiferromagnet FeAlSe. The spin susceptibility reveals a
significant antiferromagnetic interaction with a Curie-Weiss temperature
{\Theta} ~ -200K and a spin-2 local moment. Despite a large spin and a
large |{\Theta}|, the low-temperature behaviors are incompatible with
conventional classical magnets. No long-range order is detected down to 0.4K.
Similar to the well-known spin-1 magnet NiGaS, the specific heat of
FeAlSe exhibits an unusual double-peak structure and a T
power law at low temperatures, which are attributed to the underlying
quadrupolar spin correlations and the Halperin-Saslow modes, respectively. The
spin freezing occurs at ~ 14K, below which the relaxation dynamics is probed by
the ac susceptibility. Our results are consistent with the early theory for the
spin-1 system with Heisenberg and biquadratic spin interactions. We argue that
the early proposal of the quadrupolar correlation and gauge glass dynamics may
be well extended to FeAlSe. Our results provide useful insights
about the magnetic properties of frustrated quantum magnets with high spins.Comment: 7 pages, 4 figure
Survival outcomes of stage I colorectal cancer:development and validation of the ACEPLY model using two prospective cohorts
BACKGROUND: Approximately 10% of stage I colorectal cancer (CRC) patients experience unfavorable clinical outcomes after surgery. However, little is known about the subset of stage I patients who are predisposed to high risk of recurrence or death. Previous evidence was limited by small sample sizes and lack of validation. METHODS: We aimed to identify early indicators and develop a risk stratification model to inform prognosis of stage I patients by employing two large prospective cohorts. Prognostic factors for stage II tumors, including T stage, number of nodes examined, preoperative carcinoma embryonic antigen (CEA), lymphovascular invasion, perineural invasion (PNI), and tumor grade were investigated in the discovery cohort, and significant findings were further validated in the other cohort. We adopted disease-free survival (DFS) as the primary outcome for maximum statistical power and recurrence rate and overall survival (OS) as secondary outcomes. Hazard ratios (HRs) were estimated from Cox proportional hazard models, which were subsequently utilized to develop a multivariable model to predict DFS. Predictive performance was assessed in relation to discrimination, calibration and net benefit. RESULTS: A total of 728 and 413 patients were included for discovery and validation. Overall, 6.7% and 4.1% of the patients developed recurrences during follow-up. We identified consistent significant effects of PNI and higher preoperative CEA on inferior DFS in both the discovery (PNI: HRβ=β4.26, 95% CI: 1.70β10.67, pβ=β0.002; CEA: HRβ=β1.46, 95% CI: 1.13β1.87, pβ=β0.003) and the validation analysis (PNI: HRβ=β3.31, 95% CI: 1.01β10.89, pβ=β0.049; CEA: HRβ=β1.58, 95% CI: 1.10β2.28, pβ=β0.014). They were also significantly associated with recurrence rate. Age at diagnosis was a prominent determinant of OS. A prediction model on DFS using Age at diagnosis, CEA, PNI, and number of LYmph nodes examined (ACEPLY) showed significant discriminative performance (C-index: 0.69, 95% CI:0.60β0.77) in the external validation cohort. Decision curve analysis demonstrated added clinical benefit of applying the model for risk stratification. CONCLUSIONS: PNI and preoperative CEA are useful indicators for inferior survival outcomes of stage I CRC. Identification of stage I patients at high risk of recurrence is feasible using the ACEPLY model, although the predictive performance is yet to be improved. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12916-022-02693-7
CMRxRecon: An open cardiac MRI dataset for the competition of accelerated image reconstruction
Cardiac magnetic resonance imaging (CMR) has emerged as a valuable diagnostic
tool for cardiac diseases. However, a limitation of CMR is its slow imaging
speed, which causes patient discomfort and introduces artifacts in the images.
There has been growing interest in deep learning-based CMR imaging algorithms
that can reconstruct high-quality images from highly under-sampled k-space
data. However, the development of deep learning methods requires large training
datasets, which have not been publicly available for CMR. To address this gap,
we released a dataset that includes multi-contrast, multi-view, multi-slice and
multi-coil CMR imaging data from 300 subjects. Imaging studies include cardiac
cine and mapping sequences. Manual segmentations of the myocardium and chambers
of all the subjects are also provided within the dataset. Scripts of
state-of-the-art reconstruction algorithms were also provided as a point of
reference. Our aim is to facilitate the advancement of state-of-the-art CMR
image reconstruction by introducing standardized evaluation criteria and making
the dataset freely accessible to the research community. Researchers can access
the dataset at https://www.synapse.org/#!Synapse:syn51471091/wiki/.Comment: 14 pages, 8 figure
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