47 research outputs found
eX-ViT: A Novel eXplainable Vision Transformer for Weakly Supervised Semantic Segmentation
Recently vision transformer models have become prominent models for a range
of vision tasks. These models, however, are usually opaque with weak feature
interpretability. Moreover, there is no method currently built for an
intrinsically interpretable transformer, which is able to explain its reasoning
process and provide a faithful explanation. To close these crucial gaps, we
propose a novel vision transformer dubbed the eXplainable Vision Transformer
(eX-ViT), an intrinsically interpretable transformer model that is able to
jointly discover robust interpretable features and perform the prediction.
Specifically, eX-ViT is composed of the Explainable Multi-Head Attention
(E-MHA) module, the Attribute-guided Explainer (AttE) module and the
self-supervised attribute-guided loss. The E-MHA tailors explainable attention
weights that are able to learn semantically interpretable representations from
local patches in terms of model decisions with noise robustness. Meanwhile,
AttE is proposed to encode discriminative attribute features for the target
object through diverse attribute discovery, which constitutes faithful evidence
for the model's predictions. In addition, a self-supervised attribute-guided
loss is developed for our eX-ViT, which aims at learning enhanced
representations through the attribute discriminability mechanism and attribute
diversity mechanism, to localize diverse and discriminative attributes and
generate more robust explanations. As a result, we can uncover faithful and
robust interpretations with diverse attributes through the proposed eX-ViT
Accuracy of generalized gradient approximation functionals for density functional perturbation theory calculations
We assess the validity of various exchange-correlation functionals for
computing the structural, vibrational, dielectric, and thermodynamical
properties of materials in the framework of density-functional perturbation
theory (DFPT). We consider five generalized-gradient approximation (GGA)
functionals (PBE, PBEsol, WC, AM05, and HTBS) as well as the local density
approximation (LDA) functional. We investigate a wide variety of materials
including a semiconductor (silicon), a metal (copper), and various insulators
(SiO -quartz and stishovite, ZrSiO zircon, and MgO periclase).
For the structural properties, we find that PBEsol and WC are the closest to
the experiments and AM05 performs only slightly worse. All three functionals
actually improve over LDA and PBE in contrast with HTBS, which is shown to fail
dramatically for -quartz. For the vibrational and thermodynamical
properties, LDA performs surprisingly very good. In the majority of the test
cases, it outperforms PBE significantly and also the WC, PBEsol and AM05
functionals though by a smaller margin (and to the detriment of structural
parameters). On the other hand, HTBS performs also poorly for vibrational
quantities. For the dielectric properties, none of the functionals can be put
forward. They all (i) fail to reproduce the electronic dielectric constant due
to the well-known band gap problem and (ii) tend to overestimate the oscillator
strengths (and hence the static dielectric constant)
Determination of six sulfonylurea herbicides in environmental water samples by magnetic solid-phase extraction using multi-walled carbon nanotubes as adsorbents coupled with high-performance liquid chromatography
The role of hot-working on the microstructure and mechanical properties of the L12-type manganese-modified Al3Ti alloy
The crystal structure of a manganese-modified Al3Ti intermetallic alloy has been changed from the tetragonal D022 to the L12 cubic structure. The cast alloy shows considerable compression ductility at room temperature. To improve its mechanical properties further, hot-working experiments have been conducted. The results showed that the Al67Mn8Ti25 intermetallic alloy maintains very good hot-workability, the cast alloy can be reduced 60% by a single hot-pressing stroke without cracking. The role of hot-working on the microstructure and the mechanical properties of the alloy have been studied. It was found that the hot-worked alloy shows a deformed structure and some work-hardening after hot-working. Experiments indicated that the starting temperature for recrystallization is about 1173 K and complete recrystallization of the deformed alloy occurs at about 1273 K. Good hot-workability and a high recrystallization temperature permit potential for elevated temperature use. A transmission electron microscopy study on the evolution of dislocation structures in the recovery and recrystallization processes is also reported.Peer reviewed: YesNRC publication: Ye
First-principles investigation of monatomic gold wires under tension
Ab initio pseudopotential total-energy calculations on infinite monatomic chains of Au are performed within density functional theory. We use the density functional perturbation theory to study the phonon spectra of these gold wires as a function of strain. Our results show that there does not seem to be a range of strain for which the linear chain is stable, contrary to what was stated by Ribeiro and Cohen [Phys. Rev. B 68 (2003) 035423]. For low strain, the zigzag chain is the stable geometry; while for higher strain, the chains with two or more aligned gold atoms are found to be more stable. At the limit between these two regimes, we predict a transition structure (an asymmetric zigzag chain) to be the most stable
Construction of ultrasonic nanobubbles carrying CAIX polypeptides to target carcinoma cells derived from various organs
Abstract Background Ultrasound molecular imaging is a novel diagnostic approach for tumors, whose key link is the construction of targeted ultrasound contrast agents. However, available targeted ultrasound contrast agents for molecular imaging of tumors are only achieving imaging in blood pool or one type tumor. No targeted ultrasound contrast agents have realized targeted ultrasound molecular imaging of tumor parenchymal cells in a variety of solid tumors so far. Carbonic anhydrase IX (CAIX) is highly expressed on cell membranes of various malignant solid tumors, so it’s a good target for ultrasound molecular imaging. Here, targeted nanobubbles carrying CAIX polypeptides for targeted binding to a variety of malignant tumors were constructed, and targeted binding ability and ultrasound imaging effect in different types of tumors were evaluated. Results The mean diameter of lipid targeted nanobubbles was (503.7 ± 78.47) nm, and the polypeptides evenly distributed on the surfaces of targeted nanobubbles, which possessed the advantages of homogenous particle size, high stability, and good safety. Targeted nanobubbles could gather around CAIX-positive cells (786-O and Hela cells), while they cannot gather around CAIX-negative cells (BxPC-3 cells) in vitro, and the affinity of targeted nanobubbles to CAIX-positive cells were significantly higher than that to CAIX-negative cells (P < 0.05). Peak intensity and duration time of targeted nanobubbles and blank nanobubbles were different in CAIX-positive transplanted tumor tissues in vivo (P < 0.05). Moreover, targeted nanobubbles in CAIX-positive transplanted tumor tissues produced higher peak intensity and longer duration time than those in CAIX-negative transplanted tumor tissues (P < 0.05). Finally, immunofluorescence not only confirmed targeted nanobubbles could pass through blood vessels to enter in tumor tissue spaces, but also clarified imaging differences of targeted nanobubbles in different types of transplanted tumor tissues. Conclusions Targeted nanobubbles carrying CAIX polypeptides can specifically enhance ultrasound imaging in CAIX-positive transplanted tumor tissues and could potentially be used in early diagnosis of a variety of solid tumors derived from various organs
Inhibition of prostate cancer growth using doxorubicin assisted by ultrasound-targeted nanobubble destruction
Insights into Endothelin Receptors in Pulmonary Hypertension
Pulmonary hypertension (PH) is a disease which affects the cardiopulmonary system; it is defined as a mean pulmonary artery pressure (mPAP) > 20 mmHg as measured by right heart catheterization at rest, and is caused by complex and diverse mechanisms. In response to stimuli such as hypoxia and ischemia, the expression and synthesis of endothelin (ET) increase, leading to the activation of various signaling pathways downstream of it and producing effects such as the induction of abnormal vascular proliferation during the development of the disease. This paper reviews the regulation of endothelin receptors and their pathways in normal physiological processes and disease processes, and describes the mechanistic roles of ET receptor antagonists that are currently approved and used in clinical studies. Current clinical researches on ET are focused on the development of multi-target combinations and novel delivery methods to improve efficacy and patient compliance while reducing side effects. In this review, future research directions and trends of ET targets are described, including monotherapy and precision medicine