Semantic segmentation is used in many fields, and most fields not only require models with high-quality predictions but also require real-time speed in the forward inference phase. Therefore, our ...goal is to perform high-quality real-time semantic segmentation, thus proposing the feature pyramid aggregation network (FPANet). This network can be regarded as an encoder-decoder model. In the encoder stage, we use ResNet and atrous spatial pyramid pooling (ASPP) to extract more high-level semantic information. In the decoder stage, to simultaneously obtain the semantic and spatial information of the image, we propose a bilateral directional feature pyramid network for semantic segmentation to fuse features at different levels, it is named SeBiFPN. In SeBiFPN, we design a lightweight feature pyramid fusion module (FPFM) to fuse features from two different levels. In addition, when predicting the border region of an image, most real-time semantic segmentation models perform poorly; therefore, we propose a border refinement module (BRM) to improve the problem of inaccurate border segmentation. To reduce the computational complexity of the model, we redesign the ASPP module and reduce the number of feature channels during feature fusion. Our method achieves a better balance of speed and accuracy compared to the state-of-the-art methods on the Cityscapes and CamVid datasets.
Large‐aspect‐ratio composite nanofibers with interior hierarchical interfaces are employed to break the adverse coupling of electric displacement and breakdown strength in flexible poly(vinylidene ...fluoride‐hexafluoropropylene) nanocomposite films, a small loading of 3 vol% BaTiO3@TiO2 nanofibers gives rise to the highestenergy density (≈31.2 J cm−3) ever achieved in polymer nanocomposites dielectrics.
Abstract The Omh 2 ( z i , z j ) two-point diagnostics was proposed as a litmus test of the ΛCDM model, and measurements of the cosmic expansion rate H ( z ) have been extensively used to perform ...this test. The results obtained so far suggested a tension between observations and predictions of the ΛCDM model. However, the data set of H ( z ) direct measurements from cosmic chronometers and baryon acoustic oscillations was quite limited. This motivated us to study the performance of this test on a larger sample obtained in an alternative way. In this paper, we propose that gravitational-wave (GW) standard sirens could provide large samples of H ( z ) measurements in the redshift range of 0 < z < 5, based on the measurements of the dipole anisotropy of luminosity distance arising from the matter inhomogeneities of the large-scale structure and the local motion of the observer. We discuss the effectiveness of our method in the context of the space-borne DECi-herz Interferometer Gravitational-wave Observatory, based on a comprehensive H ( z ) simulated data set from binary neutron star merger systems. Our results indicate that in the GW domain, the Omh 2 ( z i , z j ) two-point diagnostics could effectively distinguish whether ΛCDM is the best description of our Universe. We also discuss the potential of our methodology in determining possible evidence for dark energy evolution, focusing on its performance on the constant and redshift-dependent dark energy equation of state.
In this letter, we propose a novel cosmological model-independent method to determine cosmic curvature, combining the recent measurements of transverse and line-of-sight directions in the baryon ...acoustic oscillations (BAO) with cosmic chronometers (CC) datasets. Considering that the CC dataset is discrete and includes only 32 H(z) measurements, we apply Gaussian process (GP) regression to fit the CC dataset and reconstruct them. Our methodology, which does not need the calibration or selection of any cosmological model, provide multiple measurements of spatial curvature (ΩK) at different redshifts (depending on the redshift coverage of BAO dataset). For combination of all BAO data, we find that the constraint result on cosmic curvature is ΩK=−0.096−0.195+0.190 with 1σ observational uncertainty. Although the measured ΩK is in good agreement with zero cosmic curvature within 1σ confidence level, our result revels the fact of a closed universe. More importantly, our results show that the obtained ΩK measurements are almost unaffected by different priors of the Hubble constant. This could help solve the issue of the Hubble tension that may be caused by inconsistencies in the spatial curvature between the early and late universes.
When developing novel radiopharmaceuticals, a linker moiety between the chelator and targeting vector can have a crucial influence on adjusting the affinity of the tracer and its biodistribution in ...organisms. To develop novel 99mTc-labelled hypoxia imaging radiotracers, in this study, five isocyanide-containing 2-nitroimidazole derivatives with different linkers (L1, L2, L3, L4 and L5) were synthesised and radiolabelled with technetium-99m to obtain five stable 99mTc-complexes (99mTcTc-L1, 99mTcTc-L2, 99mTcTc-L3, 99mTcTc-L4 and 99mTcTc-L5). Corresponding rhenium analogues of 99mTcTc-L1 were synthesised and suggested the structures of these 99mTc-complexes would be a monovalent cation with a technetium (I) core surrounded by six ligands. 99mTcTc-L1 is hydrophilic, while the lipophilicities of 99mTcTc-L2, 99mTcTc-L3, 99mTcTc-L4 and 99mTcTc-L5 are close. In vitro cell experiments showed that all five novel 99mTc-complexes had higher uptake in hypoxic cells compared with aerobic cells, which indicates the complexes have good hypoxia selectivity. The biodistribution of the five 99mTc-complexes in S180 tumour-bearing mice showed that they all had certain uptake in the tumours. Among them, 99mTcTc-L1 had the highest tumour-to-muscle (4.68 ± 0.44) and tumour-to-blood (3.81 ± 0.46) ratios. The introduction of polyethylene glycol (PEG) chains effectively reduced the lipophilicity and decreased uptake by the liver, intestine and blood but also increased clearance from the tumours. In vivo metabolic studies showed 99mTcTc-L1 kept intact and remained stable in tumour, blood and urine at 2 h post-injection. The results of SPECT imaging showed that 99mTcTc-L1 had significant tumour uptake at 2 h post-injection, but there was still high uptake in abdominal organs such as the liver and kidney, suggesting that this complex needs to be further optimised before being used for tumour hypoxia imaging.
Through the modulation of the dipolar entropy under an applied electric field (E), a reversible temperature change (ΔT) could be achieved in a dielectric material, which is known as the ...electrocaloric (EC) effect. Among all EC materials, ferroelectric terpolymer P(VDF-TrFE-CFE) has been regarded as one of the most promising EC materials owing to its large EC effect and superior thermal stability. Yet, the low EC strength limits the application of terpolymers in realistic cooling devices. In this work, using the thermal treatment of quenching and low-temperature annealing, the terpolymers with significantly decreased crystalline size are prepared with their EC performances investigated. Compared to the normal ones, the terpolymers with smaller crystalline size exhibit substantially enhanced EC strength. The better EC performance may be mainly attributed to the lower energy barriers for dipole orientation, which gives rise to higher polarization at low electric fields. This work emphasizes the critical role of crystalline size on the macroscopic properties of EC polymers.
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•Significantly decreased crystalline size of ∼ 30 nm in P(VDF-TrFE-CFE).•Substantially enhanced ΔT/E of ∼ 0.1 K m MV−1 at 150 MV m−1 in P(VDF-TrFE-CFE).•The fabrication of the P(VDF-TrFE-CFE) with small crystalline size is simple.
Due to the accident of Fukushima Daiichi Nuclear Power Plant, some areas were contaminated by released radioisotopes (mainly
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Cs and
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Cs). Effective decontamination is demanded to encourage ...evacuated people to return. This paper proposes a new survey system using an unmanned helicopter equipped with a Compton camera for localizing radionuclides. As a prototype, 32 Ce:Gd
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(Al,Ga)
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O
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(GAGG) crystals were coupled to 16 silicon photomultipliers and 16 avalanched photodiodes as the scatterer and absorber, respectively. A new Dynamic Time-over-Threshold (dToT) method was applied to convert CR-RC shaping signals to digital signals for multi-channel spectra and coincidence acquisition. The system was designed to work in two modes: one is Compton-camera mode (CCM) which obtains the radiation distribution maps through Compton imaging using hovering flights, while the other one is Gamma-camera mode (GCM) which maps the radiation distribution via measured coincidence events using programmed flights. For point source in CCM, an intrinsic efficiency of 1.68% with a combined standard uncertainty of 0.04% and an angular resolution of about 14° (FWHM, full width at half maximum) was achieved. In GCM, a spatial resolution of about 11 cm (FWHM) was obtained when detecting area is 11.2 cm away from the detector, while it was about 28 cm (FWHM) in single detector mode (SDM). Promising results were obtained in field in Fukushima.
Ferroelectric memories are endowed with high data storage density by nanostructure designing, while the robustness is also impaired. For organic ferroelectrics favored by flexible memories, low Curie ...transition temperature limits their thermal stability. Herein, a ferroelectric random access memory (FeRAM) is demonstrated based on an array of P(VDF‐TrFE) lamellae by self‐assembly. Written data shows enhanced thermal endurance up to 90 °C and undergoes 12 thermal cycles between 30 and 80 °C with little volatilization. The promoted thermal stability is attributed to pinning effect at interfaces between grain boundaries and lamellae, where charged domain walls and charged defects are coupled. These results provide a strategy for improving robustness of organic flexible FeRAMs, and reveal an attracting coupling effect between different phases of ferroelectric polymer.
Thermal stability of organic ferroelectric memories is prominent due to their low Curie transition temperature. In this work, ferroelectric random access memory with enhanced thermal stability is achieved based on an array of lamellae by self‐assembly. By switching spectrum a piezoresponse force microscope and scanning Kelvin probe microscope, the mechanism of enhanced thermal stability is presented.
Aiming at the problem of spatial information loss in the semantic segmentation process, we propose a semantic segmentation network, termed the ventral and dorsal network (VDNet), which simulates the ...ventral and dorsal pathways of the cerebral visual cortex. The ventral pathway network focuses on extracting semantic information, and the dorsal pathway network focuses on extracting spatial information. We use the semantic enhancement module (SEM) in the ventral pathway network to fuse information of different scales to enhance the extraction of semantic information, and we use the spatial attention module (SAM) in the dorsal pathway network to assign weights to different locations in space to enhance the extraction of spatial information. By fusing the information of the two pathways, the final semantic segmentation result is obtained. Since the dorsal pathway network is used to specifically enhance the extraction of spatial information, the problem of spatial information loss during the segmentation process is effectively improved, and higher segmentation accuracy can be achieved by using only a small backbone network. On the CamVid, Cityscapes and PASCAL VOC 2012 datasets, we achieve the mean intersection over union (mIoU) of 82.1%, 77.8%, and 81.0%, respectively, which verifies the effectiveness of the proposed method.
An improved light-weight Compton camera exhibiting low power consumption was developed to be mountable on an unmanned helicopter to detect cesium radiation hot spots and confirm the decontamination ...effect of cesium-affected areas. An increase in the Ce:Gd
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(Al,Ga)
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scintillator array from 4 × 4 to 8 × 8 and expansion of the interlayer distance enhanced the detection efficiency and angular resolution, respectively. Measurements were performed over the Ukedo riverbed in Namie, Fukushima Prefecture (Japan). The helicopter's flight path and speed were pre-programmed to lines interspaced by 5 and 10 m intervals and 1 m/s, respectively, facilitating measurements over areas of 65 × 60 m
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and 65 × 180 m
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at a height of 10 m for approximately 20 and 30 min, respectively. Results provided accurate ambient dose equivalent rate maps at a height of 1 m with an angular resolution corresponding to a position resolution of approximately 10 m from a height of 10 m. Hovering flights were executed over hot-spot areas for 10-20 min at a height of 5-20 m. Gamma-ray images of these hot spots were obtained using a reconstruction software. Comparison between position-shifted measurement results showed that the angular resolution coincided with that evaluated in the laboratory (approximately 10°).
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