Test-Time Distribution Normalization for Contrastively Learned Vision-language Models

Advances in the field of vision-language contrastive learning have made it possible for many downstream applications to be carried out efficiently and accurately by simply taking the dot product between image and text representations. One of the most representative approaches proposed recently known as CLIP has garnered widespread adoption due to its effectiveness. CLIP is trained with an InfoNCE loss that takes into account both positive and negative samples to help learn a much more robust representation space. This paper reveals that the common downstream practice of taking a dot product is only a zeroth-order approximation of the optimization goal, resulting in a loss of information during test-time. Intuitively, since the model has been optimized based on the InfoNCE loss, test-time procedures should also be in alignment. The question lies in how one can retrieve any semblance of negative samples information during inference in a computationally efficient way. To this end, we propose Distribution Normalization (DN), where we approximate the mean representation of a batch of test samples and use such a mean to represent what would be analogous to negative samples in the InfoNCE loss. DN requires no retraining or fine-tuning and can be effortlessly applied during inference. Extensive experiments on a wide variety of downstream tasks exhibit a clear advantage of DN over the dot product on top of other existing test-time augmentation methods.Comment: Accepted to NeurIPS 2023, project webpage: https://fengyuli-dev.github.io/dn-website

Synthesis of Icariin-Zinc and its Protective Effect on Exercise Fatigue and Reproductive System Related Glands in Male Rats

Background: Icariin, a traditional Chinese medicine, plays a protective role in the treatment of exercise fatigue. Zinc, a trace element, plays an important role in the reproductive system. Therefore, we aimed to synthesize an Icariin-Zinc complex (by chemical means) and verify its protective effect on exercise fatigue and the reproductive system using animal experiments.Methods: The icariin-zinc complex was prepared by the reaction of icariin carbonyl and zinc ions (molar ratio 1:3). The molecular formula and structural formula of the complex were identified and tested. Fifty-six rats selected by swimming training were randomly divided into six groups: static control, exercise control, icariin, gluconate zinc (G-Zn group), icariin glucose zinc and icariin-zinc exercise ( low, high dose/L-E group, H-E group) groups. These groups respectively received the following doses: 1 ml/100 g, daily gavage with NS (for the first two groups), 45 mg/kg icariin, 110 mg/kg Gluconate Zinc, Icariin glucose zinc (45 mg/kg Icariin and 110 mg/kg Gluconate Zinc), 60 mg/kg icariin zinc and 180 mg/kg icariin zinc. After 3 weeks of gavage, we conducted 6 weeks of exhaustive swimming training. Test indices such as exhaustive swimming time of rats and body weight were evaluated after the last training exercise. The seminal vesicles, testes, and prostate gland were weighed, and their indices were calculated. The levels of testosterone (in the plasma) and glycogen (in the liver and muscle homogenates) were also evaluated using ELISA.Results: Compared with the static control group, the exhaustive swimming time of the rats in each group was prolonged. Compared with the other groups, the exhaustive swimming time of the L-E and H-E groups was significantly longer (p < 0.01); the Icariin-Zinc complex significantly increased the exhaustive swimming time of the rats. Compared with the static control group, the plasma testosterone content of the L-E and H-E groups increased significantly (p < 0.05). Compared with the exercise control group and G-Zn group, the plasma testosterone content of the H-E group also increased significantly (p < 0.01). The Icariin-Zinc complex significantly increased the serum levels of testosterone in rats. Compared with the control group, the muscle glycogen reserves of each group decreased, indicating that the muscle glycogen reserves of the rats decreased after swimming. Compared with other groups, the Icariin-Zinc complex can reduce the level of glycogen in the muscles, indicating that it can increase the utilization efficiency of glycogen in muscles. Compared with the static control and exercise control groups, the testicular weight of rats in the administration groups increased slightly. The Icariin-Zinc complex increased the testicular weight, indicating that the function of the reproductive system was improved to some extent.Conclusion: Icariin-Zinc can significantly prolong the exhaustive swimming time, improve exercise ability, and increase the plasma testosterone level (which is beneficial for improving the reproductive ability of male rats). Moreover, the beneficial effect of Icariin-Zinc on the glycogen content, testis index, and other reproductive system glands is dose-dependent

Ultra-thin transmissive crystalline silicon high-contrast grating metasurfaces

Dielectric metasurfaces made from crystalline silicon, titanium dioxide, gallium nitride and silicon nitride have developed rapidly for applications in the visible wavelength regime. High performance metasurfaces typically require the realisation of subwavelength, high aspect ratio nanostructures, the fabrication of which can be challenging. Here, we propose and demonstrate the operation of high performance metasurfaces in ultra-thin (100 nm) crystalline silicon at the wavelength of 532 nm. Using optical beam analysis, we discuss fabrication complexity and show that our approach is more fabrication-tolerant than the nanofin approach, which has so far produced the highest performance metasurfaces, but may be difficult to manufacture, especially when using nanoimprint lithography

The Spatial Patterns of Land Surface Temperature and Its Impact Factors: Spatial Non-Stationarity and Scale Effects Based on a Geographically-Weighted Regression Model

Understanding the spatial distribution of land surface temperature (LST) and its impact factors is crucial for mitigating urban heat island effect. However, few studies have quantitatively investigated the spatial non-stationarity and spatial scale effects of the relationships between LST and its impact factors at multi-scales. The main purposes of this study are as follows: (1) to estimate the spatial distributions of urban heat island (UHI) intensity by using hot spots analysis and (2) to explore the spatial non-stationarity and scale effects of the relationships between LST and related impact factors at multiple resolutions (30–1200 m) and to find appropriate scales for illuminating the relationships in a plain city. Based on the LST retrieved from Landsat 8 OLI/TIRS images, the Geographically-Weighted Regression (GWR) model is used to explore the scale effects of the relationships in Zhengzhou City between LST and six driving indicators: The Fractional Vegetation Cover (FVC), the Impervious Surface (IS), the Population Density (PD), the Fossil-fuel CO2 Emission data (FFCOE), the Shannon Diversity Index (SHDI) and the Perimeter-area Fractal Dimension (PAFRAC),which indicate the vegetation abundance, built-up, social-ecological variables and the diversity and shape complexity of land cover types. Our findings showed that the spatial patterns of LST show statistically significant hot spot zones in the center of the study area, partly extending to the western and southern industrial areas, indicating that the intensity of the urban heat island is significantly spatial clustering in Zhengzhou City. In addition, compared with the Ordinary Least Squares (OLS) model, the GWR model has a better ability to characterize spatial non-stationarity and analyze the relationships between the LST and its impact factors by considering the space-varying relationships of different variables, especially at the fine spatial scales (30–480 m). However, the strength of GWR model has become relatively weak with the increase of spatial scales (720–1200 m). This reveals that the GWR model is recommended to be applied in the analysis of UHI problems and related impact factors at scales finer than 480 m in the plain city. If the spatial scale is coarser than 720 m, both OLS and GWR models are suitable for illustrating the correct relationships between UHI effect and its influence factors in the plain city due to their undifferentiated performance. These findings can provide valuable information for urban planners and researchers to select appropriate models and spatial scales seeking to mitigate urban thermal environment effect

Effects of layered double hydroxides incorporation on carbonation resistance of cementitious materials

The development of new or modified cementitious materials is an important part of existing strategies to improve performance and minimize life-cycle costs and to eliminate the CO2's impact on durability. The high anion exchange capacity of layered double hydroxides (LDHs) materials makes their interlayer ion exchange by organic and inorganic anions versatile and easily achieved. LDH-like materials could be used in cementitious materials for their CO32− capturing capacity and to enhance carbonation resistance of cementitious materials.In this work, original LDHs were synthesized, LDHs calcined at 500, 550 and 600 °C, respectively, were prepared. Power X-ray diffraction (XRD), IR-spectroscopy and thermal analysis (TG–DSC) were employed to characterize the component and structural changes of these types of LDHs before and after CO2 capture. Carbonation resistance of cement paste incorporating LDHs was experimentally evaluated for assessment of CO2 capture capacity of LDHs. Ion exchange mechanism of LDHs was also analyzed from adsorption experiments.The results show that LDH-like materials could be used for their CO32− capturing capacity to enhance carbonation resistance of concrete as well as to eliminate CO2's impact on durability aspect especially the LDHs calcined at 600 °C. Calcined LDHs fulfill the structure regeneration after CO2 capture. LDHs have positive effect on improvement of carbonation resistance of cement paste especially at later curing stages. Keywords: Layered double hydroxides (LDHs), Carbonation, Anion exchange, Adsorption, Cementitious material

Spatiotemporal Characteristics of Urban Surface Temperature and Its Relationship with Landscape Metrics and Vegetation Cover in Rapid Urbanization Region

Under the trend of rapid urbanization, the urban heat island (UHI) effect has become a hot issue for scholars to study. In order to better alleviate UHI effect, it is important to understand the effect of landuse/landcover (LULC) and landscape patterns on the urban thermal environment from perspective of landscape ecology. This research aims to quantitatively investigate the effect of LULC landscape patterns on UHI effects more accurately based on a landscape metrics analysis. In addition, we also explore the complex relationship between land surface temperature (LST) and vegetation cover. Taking Zhengzhou City of China as a case study, an integrated method which includes the geographic information system (GIS), remote-sensing (RS) technology, and landscape metrics was employed to facilitate the analysis. Landsat data (2000–2014) were applied to investigate the spatiotemporal evolution patterns of LST and LULC. The results indicated that the mean LST value increased by 2.32°C between 2000 and 2014. The rise of LST was consistent with the trend of rapid urbanization in Zhengzhou City, which resulted in sharp increases in impervious surfaces (IS) and substantial losses of vegetation cover. Furthermore, the investigation of LST and vegetation cover demonstrated that fractional vegetation cover (FVC) had a stronger negative effect on LST than normalized differential vegetation index (NDVI). In addition, LST was obviously correlated with LULC landscape patterns, and both landscape composition and spatial configuration affected UHI effects to varying degrees. This study not only illustrates a feasible way to investigate the relationship between LULC and urban thermal environment but also suggests some important measures to improve urban planning to reduce UHI effects for sustainable development

Urban Regional Logistics Distribution Path Planning Considering Road Characteristics

Generally, road characteristics (such as the longitudinal slope and pavement damage) have an important effect on logistics distribution path, not only the vehicle fuel economy and driving safety but also the benefits and efficiency of logistics companies. It is necessary to explore the influence of road characteristics on logistics distribution path planning. First, a road characteristics evaluation value is defined to quantify road characteristics. With the application of analytic hierarchy process (AHP), the road characteristics evaluation index system with three criteria and eleven indices was built, and then the calculation of the road characteristics evaluation value is proposed based on the fuzzy comprehensive evaluation method. Secondly, a mathematical model of logistics distribution path planning is proposed, in which road characteristics and distance are comprehensively considered. Thirdly, an adaptive genetic algorithm (AGA) is presented with customized crossover operator for the solution of the mathematical model. Finally, through simulation by a real example, the influences of road characteristics and distance on the optimal distribution path are discussed, and the results show the model considering the road characteristics and distance comprehensively achieves superior distribution paths to that considering the distance or road characteristics only

Synthesize of silicon/carbon nanosheets with NaCl template and its application as anode material of lithium-ion batteries

Lithium-ion batteries (LIBs) are used extensively in various applications such as mobile phones and portable computer. Silicon (Si) is regarded as a kind of promising anode material in LIBs because of its high theoretical capacity and low working potential. The major challenges related to Si anodes are their huge volume changes and poor conductivity during lithiation-delithiation. Herein, a two-dimensional structure of Si/petroleum pitches based carbon nanosheets (Si/CNSs) was successfully synthesized via a green and recyclable NaCl template method. This peculiar structural feature of Si/CNS can effectively accommodate the volume expansion of Si anodes and improve their electrochemical performance. A typical sample of Si/CNS-2 exhibits a high reversible capacities of 901mAhg(-1) at 100mAg(-1), good cycling stability (capacity retention of 655mAhg(-1) after 100 cycles at 300mAg(-1)) and excellent rate capability (533mAhg(-1) at 2Ag(-1)). This approach is simple and environment-friendly, which may supply a practicality way to prepare Si-based anode materials for high-performance LIBs