An approach of point sources detection in X-ray astronomical image using support vector machine

Since most of energy sources in our Universe appear point-like structures,the study of point sources detection method on astronomical images has become significant.In this paper,a point sources detection approach on X-ray astronomical image was proposed.Firstly,a thresholding method was used to separate the background noises.Then,the peak detection method was taken to detect the positions of potential point sources.After that,we extracted spectrum features of point sources and backgrounds,and generated the classification model using the Support Vector Machine.Finally,the correct point sources were got after discarding of spurious detections with the classification model.Our approach was applied to the X-ray image of Galaxy NGC 4552.Compared with “wavdetect”,our approach has the same performance of accuracy with a detection error rate of 5%,but a higher efficiency

D/H ratio analysis of pyrolysis-released n-alkanes from asphaltenes for correlating oils from different sources

When oil has been greatly altered by severe biodegradation, asphaltene pyrolysis is commonly conducted to obtain intact n-alkanes for carbon isotope analysis, through which oil source characterization and oil oil correlations can be performed. The ratio of hydrogen isotopes deuterium and hydrogen (D/H ratio) in the individual n-alkanes of oil maltenes has been shown to indicate differences between the depositional environments of the oil sources. The utility of the D/H ratio analysis of n-alkanes from the asphaltene pyrolysis for oil correlation need to be demonstrated. In this study, 18 asphaltene samples from different sources were collected and isothermally pyrolyzed in sealed gold tubes. Effects of the pyrolysis temperature were first illustrated for molecular ratios of alkanes and aromatic compounds and for D/H ratios of pyrolysis-yielded n-alkanes. In the case of n-alkanes in oil maltenes being unavailable for analysis after severe biodegradation, the D/H ratio range of the n-alkanes from the asphaltene pyrolysis was found to be consistent both in normal and biodegraded oils from the same source, indicating that biodegradation has had little effect on their hydrogen isotope signatures. In addition, n-alkanes yielded by asphaltenes from different sources possess clearly different D/H ratios, enabling n-alkane correlation between maltenes that are otherwise very similar. However, relatively large differences of D/H ratios can exist between n-alkanes in the asphaltene pyrolyzates and in maltenes, once the oil was altered by oil mixing formed at different maturity levels. The proposed method is thus helpful in oil oil correlation for significantly biodegraded oil and oil from a mixed origin

Lightweight Design and Evaluation of Square Reflector

In order to reduce the weight of optical elements in space remote sensors while increasing their stiffness, this paper takes an off-axis system secondary mirror as an example to design a square mirror with a size of 500 mm × 500 mm. The mirror adopts ultra-low expansion glass as the raw material. The paper proposed a lightweight form of gradual reinforcement and conducted the mirror assembly simulation analysis. The analysis results show that the weight of the lightweight mirror is 13.6 kg, and the surface density can reach 54.4 kg/m2. Under the circumstances of 1 g gravity and the temperature change of 15 °C~25 °C, the surface shape accuracy of the mirror assembly can reach 1/90λ (λ = 632.8 nm). Through the final testing, the first-order intrinsic frequency of the reflex mirror components is 167.8 Hz. The gap between the test results and the theoretical simulation results is less than 3%, which proves that the mirror assembly in the lightweight form of gradual reinforcement fully meets the index requirements and can provide a theoretical reference for the assembly of a mirror of similar size and type

Design and Evaluation of Flexible Support Based on Space Mirror

The mirror component is one of the most critical components in the space remote sensing payload, and the performance of its support essentially determines the imaging quality of the system. Mirror components need to have high face shape accuracy, high reliability, and high stability. In this paper, taking the square mirror with the size of 550 mm × 450 mm as an example, we chose the Ultra-Low-Expansion Glass (Corning) as the mirror blank material, and through in-depth research on the principle of the three-point backside support and the engineering realization, we designed a three-point backside flexible support structure applied to the space mirror component. The design results were testified by simulation analysis; the results showed that with the mirror’s weight of 13.2 kg, the surface density can reach 48.5 kg/m2. For each gravity acceleration of 1 g, within the temperature range from 16 to 24 °C, carrying a forced displacement of 5 μm, the RMS value of the mirror component can reach 1/55λ (λ = 632.8 nm), which meets the requirement of high face shape accuracy of the mirror component in space. Finally, the mechanical test was carried out on the assembled mirror component, and the intrinsic frequencies of three directions of the mirror component were obtained through the test: 173.8 Hz, 176.4 Hz and 271.5 Hz, respectively. The changes of the mirror and its support structure were all less than 5″ after the 8 g sinusoidal vibration test and the 5.66 g random vibration test, which indicates that the flexible support structure meets the requirements of the high reliability of the space remote sensing loads and the high accuracy of the space mirror component. It shows that the flexible support structure meets the high reliability and high stability requirements of space remote sensing loads. The theoretical data and test results in this research can provide theoretical references for mirror components of the same size and type

Extensive Diversity and Prevalent Fluconazole Resistance among Environmental Yeasts from Tropical China

Yeasts play important roles in both the environment and in human welfare. While some environmental yeasts positively contribute to nutrient cycling and food production, a significant number of yeast species are opportunistic human pathogens, including several that are tolerant/resistant to commonly used antifungal drugs. At present, most of our understanding of environmental yeasts has come from a few terrestrial environments in selected geographic regions. Relatively little is known about yeast diversity in tropical environments and their potential impacts on human health. Here, we characterize culturable yeasts in 968 environmental samples from eight regions in tropical China. Among the 516 soil, 273 freshwater, and 179 seawater samples, 71.5%, 85.7%, and 43.6% contained yeasts, respectively. A total of 984 yeast isolates were analyzed for their DNA barcode sequences and their susceptibilities to fluconazole. DNA sequence comparisons revealed that the 984 yeast isolates likely belonged to 144 species, including 106 known species and 38 putative novel species. About 38% of the 984 isolates belonged to known human pathogens and the most common species was Candida tropicalis, accounting for 21% (207/984) of all isolates. Further analyses based on multi-locus sequence typing revealed that some of these environmental C. tropicalis shared identical genotypes with clinical isolates previously reported from tropical China and elsewhere. Importantly, 374 of the 984 (38%) yeast isolates showed intermediate susceptibility or resistance to fluconazole. Our results suggest that these environmental yeasts could have significant negative impacts on human health

Synergic emissions reduction effect of China's "Air Pollution Prevention and Control Action Plan": benefits and efficiency

Large amounts of fossil fuels that are consumed in association with the urbanization process, lead to billions of tons of greenhouse gases and air pollutants. Air pollution control policies have the synergic effects on carbon emissions reduction, but whether they can improve the synergic emission reduction efficiency (SERE) needs to be studied. 279 Chinese cities are selected as research samples. We evaluate the synergic effect of China's "Air Pollution Prevention and Control Action Plan" (APPCAP) from the perspectives of benefits and efficiency with the Difference-in-differences (DID) model. We further decompose the SERE into synergic emission reduction technological efficiency change (SEREEC) and synergic emission reduction technological change (SERETC) to analyze the internal impact mechanisms. The result shows that: (1) SERE has increased by 8 % from 2010 to 2017, for the expansion of the possibility boundary. (2) The APPCAP has co-benefit of carbon emissions reduction by 1.5 %, but inhibits the SERE increase by 1.2 % because of the lack of resource allocation efficiency improvement. (3) The APPCAP has an inhibitory effect on SEREEC and a promoting effect on SERETC. Therefore, the government should emphasize the source control and treatment efficiency, and further strengthen the system innovation for achieving urban sustainable development effectively.This work was supported by the National Natural Science Foundation of China (grant nos: 71774033 and 31961143006), and Fudan Tyndall Centre of Fudan University (grant no. IDH6286315)

Comparative Analysis of Chemical Constituents of Moringa oleifera Leaves from China and India by Ultra-Performance Liquid Chromatography Coupled with Quadrupole-Time-Of-Flight Mass Spectrometry

With the aim to discuss the similarities and differences of phytochemicals in Moringa oleifera leaves collected from China (CML) and India (IML) in mind, comparative ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS) analysis was performed in this study. A screening analysis based on a UNIFI platform was first carried out to discuss the similarities. Next, untargeted metabolomic analysis based on multivariate statistical analysis was performed to discover the differences. As a result, a total of 122 components, containing 118 shared constituents, were characterized from CML and IML. The structure types included flavonoids, alkaloids, glyosides, organic acids and organic acid esters, iridoids, lignans, and steroids, etc. For CML, 121 compounds were characterized; among these, 18 potential biomarkers with higher contents enabled differentiation from IML. For IML, 119 compounds were characterized; among these, 12 potential biomarkers with higher contents enabled differentiation from CML. It could be concluded that both CML and IML are rich in phytochemicals and that CML is similar to IML in the kinds of the compounds it contains, except for the significant differences in the contents of some compounds. This comprehensive phytochemical profile study provides a basis for explaining the effect of different growth environments on secondary metabolites and exists as a reference for further research into or applications of CML in China

Human anti-CAIX antibodies mediate immune cell inhibition of renal cell carcinoma in vitro and in a humanized mouse model in vivo

Background: Carbonic anhydrase (CA) IX is a surface-expressed protein that is upregulated by the hypoxia inducible factor (HIF) and represents a prototypic tumor-associated antigen that is overexpressed on renal cell carcinoma (RCC). Therapeutic approaches targeting CAIX have focused on the development of CAIX inhibitors and specific immunotherapies including monoclonal antibodies (mAbs). However, current in vivo mouse models used to characterize the anti-tumor properties of fully human anti-CAIX mAbs have significant limitations since the role of human effector cells in tumor cell killing in vivo is not directly evaluated. Methods: The role of human anti-CAIX mAbs on CAIX+ RCC tumor cell killing by immunocytes or complement was tested in vitro by antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and antibody-dependent cellular phagocytosis (ADCP) as well as on CAIX+ RCC cellular motility, wound healing, migration and proliferation. The in vivo therapeutic activity mediated by anti-CAIX mAbs was determined by using a novel orthotopic RCC xenograft humanized animal model and analyzed by histology and FACS staining. Results: Our studies demonstrate the capacity of human anti-CAIX mAbs that inhibit CA enzymatic activity to result in immune-mediated killing of RCC, including nature killer (NK) cell-mediated ADCC, CDC, and macrophage-mediated ADCP. The killing activity correlated positively with the level of CAIX expression on RCC tumor cell lines. In addition, Fc engineering of anti-CAIX mAbs was shown to enhance the ADCC activity against RCC. We also demonstrate that these anti-CAIX mAbs inhibit migration of RCC cells in vitro. Finally, through the implementation of a novel orthotopic RCC model utilizing allogeneic human peripheral blood mononuclear cells in NOD/SCID/IL2Rγ−/− mice, we show that anti-CAIX mAbs are capable of mediating human immune response in vivo including tumor infiltration of NK cells and activation of T cells, resulting in inhibition of CAIX+ tumor growth. Conclusions: Our findings demonstrate that these novel human anti-CAIX mAbs have therapeutic potential in the unmet medical need of targeted killing of HIF-driven CAIX+RCC. The orthotopic tumor xenografted humanized mouse provides an improved model to evaluate the in vivo anti-tumor capabilities of fully human mAbs for RCC therapy. Electronic supplementary material The online version of this article (doi:10.1186/s12943-015-0384-3) contains supplementary material, which is available to authorized users