The Global Search for Liquid Water on Mars from Orbit: Current and Future Perspectives

Due to its significance in astrobiology, assessing the amount and state of liquid water present on Mars today has become one of the drivers of its exploration. Subglacial water was identified by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) aboard the European Space Agency spacecraft Mars Express through the analysis of echoes, coming from a depth of about 1.5 km, which were stronger than surface echoes. The cause of this anomalous characteristic is the high relative permittivity of water-bearing materials, resulting in a high reflection coefficient. A determining factor in the occurrence of such strong echoes is the low attenuation of the MARSIS radar pulse in cold water ice, the main constituent of the Martian polar caps. The present analysis clarifies that the conditions causing exceptionally strong subsurface echoes occur solely in the Martian polar caps, and that the detection of subsurface water under a predominantly rocky surface layer using radar sounding will require thorough electromagnetic modeling, complicated by the lack of knowledge of many subsurface physical parameters. Higher-frequency radar sounders such as SHARAD cannot penetrate deep enough to detect basal echoes over the thickest part of the polar caps. Alternative methods such as rover-borne Ground Penetrating Radar and time-domain electromagnetic sounding are not capable of providing global coverage. MARSIS observations over the Martian polar caps have been limited by the need to downlink data before on-board processing, but their number will increase in coming years. The Chinese mission to Mars that is to be launched in 2020, Tianwen-1, will carry a subsurface sounding radar operating at frequencies that are close to those of MARSIS, and the expected signal-to-noise ratio of subsurface detection will likely be sufficient for identifying anomalously bright subsurface reflectors. The search for subsurface water through radar sounding is thus far from being concluded

Beyond vanilla convolution:random pixel difference convolution for face perception

Abstract Face perception is an essential and significant problem in pattern recognition, concretely including Face Recognition (FR), Facial Expression Recognition (FER), and Race Categorization (RC). Though handcrafted features perform well on face images, Deep Convolutional Neural Networks (DCNNs) have brought new vitality to this field recently. Vanilla DCNNs are powerful at learning high-level semantic features, but are weak in capturing low-level image characteristic changes in illumination, intensity, and texture regarded as key traits in facial processing and feature extraction, which is alternatively the strength of human-designed feature descriptors. To integrate the best of both worlds, we proposed novel Random Pixel Difference Convolution (RPDC) which is efficient alternatives to vanilla convolutional layers in standard CNNs and can promote to extract discriminative and diverse facial features. By means of searched RPDC of high efficiency, we build S-RaPiDiNet, and achieve promising and extensive experiment results in FR ( ≈0.5 % improvement), FER (over 1% growth), and RC (0.25%–3% increase) than baseline network in vanilla convolution, showing strong generalization of RPDC

Mechanical Properties and Strengthening Mechanism of Dredged Silty Clay Stabilized by Cement and Steel Slag

The high moisture content and low strength of dredged soft soils result in significant difficulties in directly reutilizing them in engineering. Improving their mechanical properties effectively and achieving re-utilization with the maximum benefit in engineering is the key to disposing of dredged soils with high moisture content. This study investigated the influences of cement and steel slag ratio, moisture content, the maximum particle size of steel slag, and curing age on the compressive strength of dredged silty clay in a plastic flow state. The performance improvement of dredged silty clay stabilized with cement and steel slag was discussed by comparing to related previous studies. The strengthening mechanism of dredged soils stabilized with cement and steel slag was explored by microstructural observation. The results show that when the ratio of cement to steel slag was 9:6; namely, using steel slag to replace 40% of cement, the strength properties of dredged silty clay stabilized by cement and steel slag could ensure the minimum requirements of the project greater then 100 kPa, and their economics could achieve the best results. The finer the particle size of steel slag was, the better the stabilization effect was. The compressive strength of dredged silty clay stabilized by cement and steel slag with particle sizes of less than 0.075 mm was 1.06 times, 1.10 times, and 1.16 times that of 0.25 mm, 1 mm, and 2 mm and increased linearly over curing ages earlier than 28 days. The compressive strength of dredged silty clay stabilized by cement and steel slag cured for 28 days was 2.44 times, 1.59 times, and 1.36 times that of 3, 7, and 14 days, respectively. The evolution of microstructural characteristics showed that the internal pore sizes of dredged soil decreased the structural compactness increased significantly due to the formation of more calcium silicate hydrate and other agglomerated flocculent gel materials from the further reaction between steel slag and cement hydration products. The results of this study can provide technological parameters for the re-utilization of dredged soil stabilized with cement and steel slag

Decreased dengue cases attributable to the effect of COVID-19 in Guangzhou in 2020.

The dengue fever epidemic in Guangzhou may have been affected by the Coronavirus Disease 2019 (COVID-19) pandemic. The number of dengue cases dropped drastically in 2020, and there have been only 2 local cases, suggesting that dengue has not become endemic in Guangzhou

Binary neural network for automated visual surface defect detection

Abstract As is well-known, defects precisely affect the lives and functions of the machines in which they occur, and even cause potentially catastrophic casualties. Therefore, quality assessment before mounting is an indispensable requirement for factories. Apart from the recognition accuracy, current networks suffer from excessive computing complexity, making it of great difficulty to deploy in the manufacturing process. To address these issues, this paper introduces binary networks into the area of surface defect detection for the first time, for the reason that binary networks prohibitively constrain weight and activation to +1 and −1. The proposed Bi-ShuffleNet and U-BiNet utilize binary convolution layers and activations in low bitwidth, in order to reach comparable performances while incurring much less computational cost. Extensive experiments are conducted on real-life NEU and Magnetic Tile datasets, revealing the least OPs required and little accuracy decline. When classifying the defects, Bi-ShuffleNet yields comparable results to counterpart networks, with at least 2× inference complexity reduction. Defect segmentation results indicate similar observations. Some network design rules in defect detection and binary networks are also summarized in this paper

Polyoxometalate-Supported 3d−4f Heterometallic Single-Molecule Magnets

The reactions of [CuTbLSchiff(H2O)3Cl2]Cl complexes with A- or B-type Anderson polyoxoanions lead to new polyoxometalate-supported 3d−4f heterometallic systems with single-molecule-magnet behavior

Simultaneous detection of enterovirus-D68 and vaccine-related poliovirus 3 in the stool samples of a 5-month hospitalized child with acute respiratory disease: A case report

Human enterovirus (EV) infections can lead to various manifestations, with variable correlations between genotypes and symptoms. Human enterovirus D68 (EV-D68) was considered to be associated with acute respiratory disease and acute flaccid myelitis. In this short report, both EV-D68 and poliovirus 3 were detected in the stool of a hospitalized 5-month child who presented with acute respiratory symptoms and who was recently vaccinated with oral polio vaccine (OPV), using a metatranscriptomic high-throughput sequencing method. The nearly full-length genome sequences with complete open reading frames of EV-D68 and poliovirus 3 were assembled. One previously-reported neurovirulence-related amino acid substitution (T860N) in the EV-D68 VP1 region was observed, but the patient showed no neurological symptoms. More attention should be paid to EV-D68, and continuous multiple syndrome-based surveillance on non-polio enterovirus is called for

Loneliness and Health Service Utilization among the Rural Elderly in Shandong, China: A Cross-Sectional Study

Objectives: To examine the prevalence of loneliness and to explore the association between loneliness and health service utilization among the rural elderly in Shandong Province, China. Methods: A total of 5514 rural people aged 60 and above from Shandong Province, China, were enrolled in this study. Loneliness was used as a binary variable based on a single-item question. Health service utilization was measured by recent two-week physician visits and annual hospitalizations rates. Multiple logistic regression analysis was performed to examine the association between loneliness and health service utilization. Results: The prevalence of loneliness among the rural elderly in Shandong, China, was 25.0%. Loneliness was associated with higher rates of recent two-week physician visits (OR = 1.260, p < 0.01) and annual hospitalizations (OR = 1.183, p < 0.05). The regression results also showed that self-rated health status and chronic conditions were significant and positively associated with both physician visits and hospitalizations rates. Conclusions: Loneliness had a significant association with higher odds of health service utilization among the elderly. The independent contribution of loneliness on health service utilization was smaller than self-rated health status and chronic conditions. Thus, healthcare policies need to shift from an emphasis on controlling health utilization and cost to a greater focus on enabling lonely older people to get more social support

Association of Anthropometric Indices of Obesity with Hypertension in Chinese Elderly: An Analysis of Age and Gender Differences

This study aims to explore the association of anthropometric indices of obesity with hypertension in Chinese elderly and its possible gender and age differences. A total of 7070 adults age 60 or older were interviewed in a cross-sectional study conducted in 2017. Anthropometric indices for each participant were measured by using standard methods of trained doctoral/master students. We performed two binary logistic regression models to examine the association of the nine different anthropometric indices and hypertension by gender. Lastly, analyses were performed in two steps stratified for age. Comparing individuals with and without hypertension, there were statistically significant differences in anthropometric indices except height, a body shape index (ABSI), and hip index (HI) in males; and except height in females. There were gender differences in the relationship between anthropometric indices and the prevalence of hypertension in Chinese older adults. After stratification by age, the associations of all anthropometric indices became weaker, disappeared, or even went in the opposite direction. Furthermore, body mass index (BMI) in men (except individuals older than 80) and hip circumference (HC) in women showed a significant impact on the risk of hypertension. The association of anthropometric indices of obesity with hypertension in Chinese elderly differ by gender and age. These findings indicate a need to develop gender-specific strategies for the male and female elderly in the primary and secondary prevention of hypertension