Due to the complex arrangements of the ground objects in high spatial resolution (HSR) imagery scenes, HSR imagery scene classification is a challenging task, which is aimed at bridging the semantic ...gap between the low-level features and the high-level semantic concepts. A combination of multiple complementary features for HSR imagery scene classification is considered a potential way to improve the performance. However, the different types of features have different characteristics, and how to fuse the different types of features is a classic problem. In this paper, a Dirichlet-derived multiple topic model (DMTM) is proposed to fuse heterogeneous features at a topic level for HSR imagery scene classification. An efficient algorithm based on a variational expectation-maximization framework is developed to infer the DMTM and estimate the parameters of the DMTM. The proposed DMTM scene classification method is able to incorporate different types of features with different characteristics, no matter whether these features are local or global, discrete or continuous. Meanwhile, the proposed DMTM can also reduce the dimension of the features representing the HSR images. In our experiments, three types of heterogeneous features, i.e., the local spectral feature, the local structural feature, and the global textural feature, were employed. The experimental results with three different HSR imagery data sets show that the three types of features are complementary. In addition, the proposed DMTM is able to reduce the dimension of the features representing the HSR images, to fuse the different types of features efficiently, and to improve the performance of the scene classification over that of other scene classification algorithms based on spatial pyramid matching, probabilistic latent semantic analysis, and latent Dirichlet allocation.
Scene classification has been studied to allow us to semantically interpret high spatial resolution (HSR) remote sensing imagery. The bag-of-visual-words (BOVW) model is an effective method for HSR ...image scene classification. However, the traditional BOVW model only captures the local patterns of images by utilizing local features. In this letter, a local-global feature bag-of-visual-words scene classifier (LGFBOVW) is proposed for HSR imagery. In LGFBOVW, the shape-based invariant texture index is designed as the global texture feature, the mean and standard deviation values are employed as the local spectral feature, and the dense scale-invariant feature transform (SIFT) feature is employed as the structural feature. The LGFBOVW can effectively combine the local and global features by an appropriate feature fusion strategy at histogram level. Experimental results on UC Merced and Google data sets of SIRI-WHU demonstrate that the proposed method outperforms the state-of-the-art scene classification methods for HSR imagery.
The major virulence determinant of Legionella pneumophila is the type IVB secretion system (T4BSS), which delivers approximately 330 effector proteins into the host cell to modulate various cellular ...processes. However, the functions of most effector proteins remain unclear. WipA, an effector, was the first phosphotyrosine phosphatase of Legionella with unknown function. In this study, we found that WipA induced relatively strong growth defects in yeast in a phosphatase activity‐dependent manner. Phosphoproteomics data showed that WipA was likely involved into endocytosis, FcγR‐mediated phagocytosis, tight junction, and regulation of actin cytoskeleton pathways. Western blotting further confirmed WipA dephosphorylates several proteins associated with actin polymerisation, such as p‐N‐WASP, p‐ARP3, p‐ACK1, and p‐NCK1. Thus, we hypothesised that WipA targets N‐WASP/ARP2/3 complex signalling pathway, leading to disturbance of actin polymerisation. Indeed, we demonstrated that WipA inhibits host F‐actin polymerisation by reducing the G‐actin to F‐actin transition during L. penumophila infection. Furthermore, the intracellular proliferation of wipA/legK2 double mutant was significantly impaired at the late stage of infection, although the absence of WipA does not confer any further effect on actin polymerisation to the legK2 mutant. Collectively, this study provides unique insights into the WipA‐mediated regulation of host actin polymerisation and assists us to elucidate the pathogenic mechanisms of L. pnuemophila infection.
Hijacking host actin polymerisation is one of the strategies used by many bacterial pathogens to successfully survive and replicate within host cells. Here we demonstrate that tyrosine phosphatase WipA, one of the effector proteins secreted by Legionella pneumophila, dephosphorylates p‐NCK1, p‐ACK1, p‐N‐WASP and p‐ARP3, resulting in inhibition of the G‐actin to F‐actin transition. Thus L. pneumophila delivers WipA to hijack N‐WASP‐ARP2/3 complex signaling pathway to disrupt host F‐actin polymerisation during infection.
In recent years, transfer learning with pretrained convolutional networks (CNets) has been successfully applied to land-use classification with high spatial resolution (HSR) imagery. The commonly ...used transfer CNets partially use the feature descriptor part of the pretained CNets, and replace the classifier part of the pretrained CNets in the old task with a new one. This causes the separation and asynchrony between the feature descriptor part and the classifier part of the transferred CNets during the learning process, which reduces the effectiveness of the training process. To overcome this weakness, a transfer learning method with fully pretrained CNets is proposed in this letter for the land-use classification of HSR images. In the proposed method, a multilayer perceptron (MLP) classifier is quickly pretrained using the high-level features extracted by the feature descriptor of the pretrained CNets. Fully pretrained CNets can be generated by concatenating the feature descriptor of the pretrained CNets and the pretained MLP. Because both the feature descriptor and the classifier are pretrained, the separation and asynchrony between the two parts can be avoided during the training process. The final transferred CNets are then obtained by fine-tuning the fully pretrained CNets with the random cropping and mirroring strategy. The experiments show that the proposed method can accelerate the convergence of the training process with no loss of accuracy in land-use classification, and its performance is comparable to other latest methods.
A type of balanced-to-single-ended (BTSE) filtering power divider (FPD) using multilayer mixed-mode magic-T is reported. Based on grounded coplanar waveguide (GCPW) to slotline transitions, a ...mixed-mode magic-T is firstly discussed. It attains out-of-phase and in-phase wideband distributed responses by means of the balanced port E and the single-ended port H, respectively. Then, by coupling the designed mixed-mode magic-T with a stub-loaded resonator (SLR), a BTSE FPD with its port H terminated by a 50-ohm load is proposed. Due to the employed microstrip SLR along with the coupled pair of L-shaped slotline sections, the designed FPD can feature a second-order high- selectivity differential-mode (DM) filtering response with two close-to-passband transmission zeros (TZs) and high broadband common-mode (CM) rejection. Moreover, for experimental- demonstration purposes, two proof-of-concept prototypes corresponding to a mixed-mode magic-T and a BTSE FPD are developed and tested. The mixed-mode magic-T is measured with a BTSE 10-dB return-loss bandwidth from 2.05 to 3.78 GHz and a single-ended-to-single-ended (SETSE) 10-dB return-loss bandwidth from 1.5 to 4.5 GHz, respectively. The measured BTSE FPD features a 10-dB return-loss DM bandwidth of 8.36% along with power isolation levels above 17.7 dB at the output ports and two TZs located 2.74 and 3.55 GHz, respectively.
Pancreatic cancer (PC) is one of the most common malignancies. Surgical resection is a potential curative approach for PC, but most patients are unsuitable for operations when at the time of ...diagnosis. Even with surgery, some patients may still experience tumour metastasis during the operation or shortly after surgery, as precise prognosis evaluation is not always possible. If patients miss the opportunity for surgery and resort to chemotherapy, they may face the challenging issue of chemotherapy resistance. In recent years, liquid biopsy has shown promising prospects in disease diagnosis, treatment monitoring, and prognosis assessment. As a noninvasive detection method, liquid biopsy offers advantages over traditional diagnostic procedures, such as tissue biopsy, in terms of both cost-effectiveness and convenience. The information provided by liquid biopsy helps clinical practitioners understand the molecular mechanisms underlying tumour occurrence and development, enabling the formulation of more precise and personalized treatment decisions for each patient. This review introduces molecular biomarkers and detection methods in liquid biopsy for PC, including circulating tumour cells (CTCs), circulating tumour DNA (ctDNA), noncoding RNAs (ncRNAs), and extracellular vesicles (EVs) or exosomes. Additionally, we summarize the applications of liquid biopsy in the early diagnosis, treatment response, resistance assessment, and prognostic evaluation of PC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Two‐dimensional materials with intrinsic magnetism have recently drawn intense interest for both the fundamental studies and potential technological applications. However, the studies to date have ...been largely limited to mechanically exfoliated materials. Herein, an atmospheric pressure chemical vapor deposition route to ultrathin group VB metal telluride MTe2 (M = V, Nb, Ta) nanoplates with thickness as thin as 3 nm is reported. It is shown that the resulting nanoplates can be systematically evolved from mostly thicker hexagonal domains to thinner triangular domains with an increasing flow rate of the carrier gas. X‐ray diffraction and transmission electron microscopy studies reveal MTe2 (M = V, Nb, Ta) nanoplates are high‐quality single crystals. High‐resolution scanning transmission electron microscope imaging reveals the VTe2 and NbTe2 nanoplates adopt the hexagonal 1T phase and the TaTe2 nanoplates show a monoclinic distorted 1T phase. Electronic transport studies show that MTe2 single crystals exhibit metallic behavior. Magnetic measurements show that VTe2 and NbTe2 exhibit ferromagnetism and TaTe2 shows paramagnetic behavior. The preparation of ultrathin few‐layered MTe2 nanoplates will open up exciting opportunities for the burgeoning field of spintronics, sensors, and magneto‐optoelectronics.
Ultrathin MTe2 (M = V, Nb, Ta) single‐crystal nanoplates are synthesized with a thickness down to 3 nm. The magnetic property investigation reveals that the VTe2 and the NbTe2 show ferromagnetic behavior, and the TaTe2 shows paramagnetic behavior. The synthesis of ultrathin MTe2 will provide an exciting material platform for the burgeoning field of 2D magnetism, spintronics, sensors, and magneto‐optoelectronics.
An approach for the realization of radiofrequency (RF)/microwave balanced filters with simultaneous differential-mode (DM) and common-mode (CM) two-port-reflectionless behavior for bandpass, ...quasi-bandstop, and dual-passband applications is reported. These RF filtering components exploit as basic constituent circuit block a type of two-layer broadband magic-T, in which its two-side/coplanar arms are designed as the balanced feeding ports at the top layer. Specifically, two replicas of this wideband magic-T on a microstrip-to-slotline transition are back-to-back connected between their <inline-formula> <tex-math notation="LaTeX"> {\Delta } </tex-math></inline-formula> terminals by means of a double-complementary-diplexer-based single-ended low-reflection filtering unit inserted at the bottom layer. In addition, their <inline-formula> <tex-math notation="LaTeX"> {\Sigma } </tex-math></inline-formula> accesses are loaded with a resistor to perform the CM RF-power-absorption functionality. Thus, balanced symmetrical-absorptive RF filtering devices for both the DM and CM operations are developed. Such distinctive feature makes this family of microwave filters unique since most of related prior-art balanced filters mainly focused on obtaining the RF-power-absorption property only for the DM or the CM. The theoretical operational foundations and RF design principles of the engineered class of balanced filters with double DM and CM symmetrical-absorptive capabilities are described. Furthermore, their two-layer implementations exemplified in second- and fourth-order bandpass filters (BPFs), a second-order quasi-bandstop filter (BSF), and a second-order dual-band BPF are presented. For experimental-validation purposes, three different prototypes centered around 2 GHz corresponding to single-band BPF and quasi-BSF devices, as well as a dual-band BPF circuit with passbands located at 1.75 and 2.25 GHz, are manufactured and tested. For all these prototypes, 10-dB-referred DM and CM two-port-RF-power-absorption relative spectral ranges larger than 3:1 are measured. Their expected RF filtering functionalities and highly suppressed CM transmission at all frequencies are also verified.
In this article, a single-ended-to-balanced (SETB) broadband magic-T based on microstrip/slotline transitions and microstrip/slotline T-junctions is proposed. For the purpose of miniaturization and ...low interconnection loss, an SETB filtering magic-T with a sharp selectivity is also achieved by introducing a pair of microstrip stub-loaded resonators (SLRs) at the two output ports. For the first design, a U-type microstrip feed line integrated with a circular slot stub is adopted at each output port, which makes the differential-mode (DM) response independent of the common-mode (CM) one. Therefore, the design procedure is simplified significantly. Meanwhile, based on the microstrip/slotline T-junctions, in-phase and out-of-phase two-way equal power division networks can be realized, respectively. For the second design, a DM passband with two transmission zeros (TZs) is generated by introducing SLRs based on the first design. By employing the characteristic mode analysis method, it is easy to find that the center frequency and fractional bandwidth (FBW) can be controlled by changing the dimensions of SLR. To the best of the authors' knowledge, the SETB magic-T with broadband or filtering performances may be the first ever reported. To verify the feasibility of the designs, two prototype circuits of the proposed magic-Ts are fabricated and measured. The simulation results are in good agreement with the measured ones. In these two designs, the functions of in-phase and out-of-phase power dividing, broadband or frequency selectivity, isolation between output ports, and CM suppression can be realized at the same time.
Strain engineering is a promising method to manipulate the electronic and optical properties of two-dimensional (2D) materials. However, with weak van der Waals interaction, severe slippage between ...2D material and substrate could dominate the bending or stretching processes, leading to inefficiency strain transfer. To overcome this limitation, we report a simple strain engineering method by encapsulating the monolayer 2D material in the flexible PVA substrate through spin-coating approach. The strong interaction force between spin-coated PVA and 2D material ensures the mechanical strain can be effectively transferred with negligible slippage or decoupling. By applying uniaxial strain to monolayer MoS
, we observe a higher bandgap modulation up to ~300 meV and a highest modulation rate of ~136 meV/%, which is approximate two times improvement compared to previous results achieved. Moreover, this simple strategy could be well extended to other 2D materials such as WS
or WSe
, leading to enhanced bandgap modulation.
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