By employing a precise method for locating and directly imaging the active switching region in a resistive random access memory (RRAM) device, a nanoscale conducting channel consisting of an ...amorphous Ta(O) solid solution surrounded by nearly stoichiometric Ta2O5 is observed. Structural and chemical analysis of the channel combined with temperature‐dependent transport measurements indicate a unique resistance switching mechanism.
A new method is introduced for searching the integral solution to the system of non-instantaneous impulsive Riemann–Liouville fractional differential equations (NIRFrDE). For the system of NIRFrDE, ...its equivalent system is gained by applying some transformations, and its special integral solution and approximate integral solution are found out by considering fractional derivative from the whole interval and each local interval in the equivalent system, and then the error between the integral solution and approximate integral solution is computed to discover that the formula of integral solution is with some arbitrary constants. Finally, the main result is explained by computing the integral solution of a numerical example.
•Summarize the four fundamental issues in BUS image segmentation.•Study the basic ideas, theories, pros and cons of BUS image segmentation approaches, group them into categories, and extensively ...review each category in depth by discussing the principles, application issues, and advantages/disadvantages.•Discuss the four major directions of BUS image segmentation.
Breast cancer is one of the leading causes of cancer death among women worldwide. In clinical routine, automatic breast ultrasound (BUS) image segmentation is very challenging and essential for cancer diagnosis and treatment planning. Many BUS segmentation approaches have been studied in the last two decades, and have been proved to be effective on private datasets. Currently, the advancement of BUS image segmentation seems to meet its bottleneck. The improvement of the performance is increasingly challenging, and only few new approaches were published in the last several years. It is the time to look at the field by reviewing previous approaches comprehensively and to investigate the future directions. In this paper, we study the basic ideas, theories, pros and cons of the approaches, group them into categories, and extensively review each category in depth by discussing the principles, application issues, and advantages/disadvantages.
Due to the complicated structure of breast and poor quality of ultrasound images, accurately and automatically locating regions of interest (ROIs) and segmenting tumors are challenging problems for ...breast ultrasound (BUS) computer-aided diagnosis systems. In this paper, we propose a fully automatic BUS image segmentation approach for performing accurate and robust ROI generation, and tumor segmentation. In the ROI generation step, the proposed adaptive reference point (RP) generation algorithm can produce the RPs automatically based on the breast anatomy; and the multipath search algorithm generates the seeds accurately and fast. In the tumor segmentation step, we propose a segmentation framework in which the cost function is defined in terms of tumor׳s boundary and region information in both frequency and space domains. First, the frequency constraint is built based on the newly proposed edge detector which is invariant to contrast and brightness; and then the tumor pose, position and intensity distribution are modeled to constrain the segmentation in the spatial domain. The well-designed cost function is graph-representable and its global optimum can be found. The proposed fully automatic segmentation method is applied to a BUS database with 184 cases (93 benign and 91 malignant), and the performance is evaluated by the area and boundary error metrics. Compared with the newly published fully automatic method, the proposed method is more accurate and robust in segmenting BUS images.
•We propose a reference point (RP) generation algorithm based on breast anatomy.•We propose a new segmentation framework modeling tumor properties in two domains.•The proposed frequency constraint is invariant to the brightness and contrast.•The proposed cost function is graph-representable and can be globally optimized.
•A two-link flexible manipulator experimental apparatus is constructed.•A Takagi-Sugeno model based fuzzy neural network controller is investigated.•A generalized minimum variance self-tuning control ...algorithm is designed.•Experiments are conducted on vibration suppression using the designed schemes.
This paper presents experimental investigations on active vibration control of a two-link flexible manipulator (TLFM), utilizing a generalized minimum variance self-tuning control (GMVSTC) and Takagi-Sugeno model based fuzzy neural network control (TS-FNN) schemes. The GMVSTC algorithm consists of an on-line identifier in the form of controlled autoregressive moving average model and a vibration control signal generator, and the TS-FNN control algorithm generates control actions taking full advantages of fuzzy logic controller and a neural controller. Experimental setup of the two-link flexible manipulator is constructed. Experimental comparison research on vibration attenuation is conducted during and after the motor motion, to verify the designed controllers. The effectiveness of the designed controllers is evaluated in terms of vibration suppression as compared to that of the classical PD control. The experimental results demonstrate that the designed controller can damp out both the large and the small amplitude vibration of a two-link flexible manipulator more quickly than that the traditional linear PD controller, especially for the small amplitude residual vibration.
This paper is mainly concerned with the initial value problem (IVP) for two types of impulsive fractional differential equations (IFrDE) with the Hilfer‐generalized fractional derivative. For these ...IVPs of IFrDE, their equivalent integral equations with an arbitrary constant are built by constructing an approximate solution and calculating the error between the approximate solution and the exact solution, which uncover that there are many solutions for these IVPs of IFrDE. We offer some numerical examples to explain the obtained results.
Abstract
The estimation of spectroscopic and photometric redshifts (spec-
z
and photo-
z
) is crucial for future cosmological surveys. It can directly affect several powerful measurements of the ...universe, such as weak lensing and galaxy clustering. In this work, we explore the accuracies of spec-
z
and photo-
z
that can be obtained by the China Space Station Optical Surveys, which is a next-generation space survey, using a neural network. The one-dimensional Convolutional Neural Networks and Multi-Layer Perceptron (MLP, the simplest form of an artificial neural network) are employed to derive spec-
z
and photo-
z
, respectively. The mock spectral and photometric data used for training and testing the networks are generated based on the COSMOS catalog. The networks have been trained with noisy data by creating Gaussian random realizations to reduce the statistical effects, resulting in a similar redshift accuracy for data with both high and low signal-to-noise ratios. The probability distribution functions of the predicted redshifts are also derived via Gaussian random realizations of the testing data, and then the best-fit redshifts and 1
σ
errors also can be obtained. We find that our networks can provide excellent redshift estimates with accuracies of ∼0.001 and 0.01 on spec-
z
and photo-
z
, respectively. Compared to existing photo-
z
codes, our MLP has a similar accuracy but is more efficient in the training process. The fractions of catastrophic redshifts or outliers can be dramatically suppressed compared to the ordinary template-fitting method. This indicates that the neural network method is feasible and powerful for spec-
z
and photo-
z
estimations in future cosmological surveys.
Hypocotyl elongation is dramatically influenced by environmental factors and phytohormones. Indole‐3‐acetic acid (IAA) plays a prominent role in hypocotyl elongation, whereas abscisic acid (ABA) is ...regarded as an inhibitor through repressing IAA synthesis and signalling. However, the regulatory role of ABA in local IAA deactivation remains largely uncharacterized. In this study, we confirmed the antagonistic interplay of ABA and IAA during the hypocotyl elongation of tomato (Solanum lycopersicum) seedlings. We identified an IAA oxidase enzyme DIOXYGENASE FOR AUXIN OXIDATION2 (SlDAO2), and its expression was induced by both external and internal ABA signals in tomato hypocotyls. Moreover, the overexpression of SlDAO2 led to a reduced sensitivity to IAA, and the knockout of SlDAO2 alleviated the inhibitory effect of ABA on hypocotyl elongation. Furthermore, an ABA‐responsive regulatory SlAREB1/SlABI3‐1/SlABI5 cascade was identified to act upstream of SlDAO2 and to precisely control its expression. SlAREB1 directly bound to the ABRE present in the SlDAO2 promoter to activate SlDAO2 expression, and SlABI3‐1 enhanced while SlABI5 inhibited the activation ability of SlAREB1 by directly interacting with SlAREB1. Our findings revealed that ABA might induce local IAA oxidation and deactivation via SlDAO2 to modulate IAA homoeostasis and thereby repress hypocotyl elongation in tomato.
Summary statement
We found that ABA regulates expression of IAA oxidase gene SlDAO2 via the AREB1/ABI3‐1/ABI5 transcription factor cascade, and thereby modulating IAA homeostasis and inhibiting hypocotyl elongation in tomato seedlings.
VEGF/VEGFR2 pathway is the central therapeutic target in anti-angiogenic treatment in multiple cancers. However, little work has been carried out concerning the pro-malignancy functions of VEGFR2 ...that are independent of its pro-angiogenesis effects in gastric cancer. Here, we demonstrated that VEGFR2 up-regulation in gastric cancer tissues was a prognostic marker for poor disease-free survival and overall survival of gastric cancer patients.
Immunohistochemistry was used to detect VEGFR2 and VTN expressions in specimens. Kaplan-Meier curves were constructed for survival analysis. Stably knockdown cell lines and overexpression cell lines were constructed by small interfering RNA and plasmids transfection. Real-time PCR and Western blot were used to confirm the expressions of target genes at both RNA and protein levels. Cell proliferation was measured by using Cell Counting Kit-8 and xenograft models. Microarray and bioinformatic analysis were also performed to identify the relationship between Vitronectin (VTN) and VEGFR2.
When overexpressed in gastric cancer cells, VEGFR2 increased cellular proliferation and invasion in vitro and tumor formation in xenograft models. By using integrating microarray and bioinformatic analysis, we identifiedVTN as a downstream of VEGFR2 pathway. In gain- and loss-of function analysis in gastric cancer cells, VTN was further verified in consistent with VEGFR2 in expression levels and in regulating cell growth and motility in vitro and in vivo. Moreover, in gastric cancer samples, VTN was as also revealed as a poor prognostic factor.
Our present findings defined a novel activity for VEGFR2 in promoting tumorogenicity, motility and indicating a poor survival in gastric cancer beyond its known pro-angiogenic effects.
Our present findings defined a novel activity for VEGFR2 in promoting tumorogenicity, motility and indicating a poor survival in gastric cancer beyond its known pro-angiogenic effects, which may provide a new and valuable target for design of therapies for intervention and a new cognitive perspective for the anti-angiogenesis therapies.
An integrated memory cell with a memristor and a trilayer crested barrier selector, showing repeatable nonlinear current–voltage switching loops is presented. The fully atomic‐layer‐deposited ...TaN1+x/Ta2O5/TaN1+x crested barrier selector yields a large nonlinearity (>104), high endurance (>108), low variability, and low temperature dependence.
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