Automatic detection of low surface brightness galaxies from SDSS images

Low surface brightness (LSB) galaxies are galaxies with central surface brightness fainter than the night sky. Due to the faint nature of LSB galaxies and the comparable sky background, it is difficult to search LSB galaxies automatically and efficiently from large sky survey. In this study, we established the Low Surface Brightness Galaxies Auto Detect model (LSBG-AD), which is a data-driven model for end-to-end detection of LSB galaxies from Sloan Digital Sky Survey (SDSS) images. Object detection techniques based on deep learning are applied to the SDSS field images to identify LSB galaxies and estimate their coordinates at the same time. Applying LSBG-AD to 1120 SDSS images, we detected 1197 LSB galaxy candidates, of which 1081 samples are already known and 116 samples are newly found candidates. The B-band central surface brightness of the candidates searched by the model ranges from 22 mag arcsec $^ {- 2}$ to 24 mag arcsec $^ {- 2}$, quite consistent with the surface brightness distribution of the standard sample. 96.46\% of LSB galaxy candidates have an axis ratio ($b/a$) greater than 0.3, and 92.04\% of them have $fracDev\_r$\textless 0.4, which is also consistent with the standard sample. The results show that the LSBG-AD model learns the features of LSB galaxies of the training samples well, and can be used to search LSB galaxies without using photometric parameters. Next, this method will be used to develop efficient algorithms to detect LSB galaxies from massive images of the next generation observatories.Comment: 11 pages, 9 figures,accepted to be published on MNRA

Consensus with a reference state for fractional-order multi-agent systems

International audienc

Hypoxia inducible factor-1α-dependent epithelial to mesenchymal transition under hypoxic conditions in prostate cancer cells

Prostate cancer is the most commonly diagnosed cancer in men and the second leading cause of cancer death. Hypoxia is an environmental stimulus that plays an important role in the development and cancer progression especially for solid tumors. The key regulator under hypoxic conditions is stabilized hypoxia-inducible factor (HIF)-1α. In the present study, immune-fluorescent staining, siRNAs, qRT-PC, immunoblotting, cell migration and invasion assays were carried out to test typical epithelial to mesenchymal transition under hypoxia and the key regulators of this process in PC3, a human prostate cancer cell line. Our data demonstrated that hypoxia induces diverse molecular, phenotypic and functional changes in prostate cancer cells that are consistent with EMT. We also showed that a cell signal factor such as HIF-1α, which might be stabilized under hypoxic environment, is involved in EMT and cancer cell invasive potency. The induced hypoxia could be blocked by HIF-1α gene silencing and reoxygenation of EMT in prostate cancer cells, hypoxia partially reversed accompanied by a process of mesenchymal-epithelial reverting transition (MErT). EMT might be induced by activation of HIF-1α-dependent cell signaling in hypoxic prostate cancer cells

Hypoxia inducible factor-1a-dependent epithelial to mesenchymal transition under hypoxic conditions in prostate cancer cells

Prostate cancer is the most commonly diagnosed\r\ncancer in men and the second leading cause of cancer death.\r\nHypoxia is an environmental stimulus that plays an important\r\nrole in the development and cancer progression especially for\r\nsolid tumors. The key regulator under hypoxic conditions is\r\nstabilized hypoxia-inducible factor (HIF)-1a. In the present\r\nstudy, immune-fluorescent staining, siRNAs, qRT-PC, immunoblotting, cell migration and invasion assays were carried\r\nout to test typical epithelial to mesenchymal transition under\r\nhypoxia and the key regulators of this process in PC3, a human\r\nprostate cancer cell line. Our data demonstrated that hypoxia\r\ninduces diverse molecular, phenotypic and functional changes\r\nin prostate cancer cells that are consistent with EMT. We\r\nalso showed that a cell signal factor such as HIF-1a, which\r\nmight be stabilized under hypoxic environment, is involved in\r\nEMT and cancer cell invasive potency. The induced hypoxia\r\ncould be blocked by HIF-1a gene silencing and reoxygenation\r\nof EMT in prostate cancer cells, hypoxia partially reversed\r\naccompanied by a process of mesenchymal-epithelial reverting\r\ntransition (MErT). EMT might be induced by activation of\r\nHIF-1a-dependent cell signaling in hypoxic prostate cancer\r\ncells

Satellite evidence for China's leading role in restoring vegetation productivity over global karst ecosystems

Karst ecosystems occupy approximately 20% of the Earth's land surface with the unique and vulnerable geomorphological and hydrogeological characteristics. To date, it remains a challenge to accurately monitor ecosystem productivity from space, as well as their responses to the environmental conditions due to climate change and anthropogenic pressure, which is pivotal to the sustainable development strategies in global karst areas. Here we use a reconstructed long-term solar-induced chlorophyll fluorescence dataset (SIF) and two satellite-based gross primary productivity (GPP) products to examine the patterns and trends of vegetation productivity within global karst ecosystems, and to assess the relative contributions of different countries to the restoration of these fragile ecosystems over the period 2001–2016. As an effective proxy for terrestrial GPP, SIF reveals a greening trend across most of the world's karst areas. China and the European Union (EU) lead the world in vegetation greening within their karst areas by 78.02% and 42.44%, respectively. The total net increase in SIF shows that China alone accounted for 43.66% with just 7.0% of global karst area. Brazil is the only country with a negative greening trend. Recent land cover changes caused by the grain-for-green programme in China and deforestation in Brazil account for 36.93% and 64.71% of the increases and decreases, respectively. Our results have significant implications for restoring ecosystem productivity in global karst areas

Satellite evidence for China's leading role in restoring vegetation productivity over global karst ecosystems

Karst ecosystems occupy approximately 20% of the Earth's land surface with the unique and vulnerable geomorphological and hydrogeological characteristics. To date, it remains a challenge to accurately monitor ecosystem productivity from space, as well as their responses to the environmental conditions due to climate change and anthropogenic pressure, which is pivotal to the sustainable development strategies in global karst areas. Here we use a reconstructed long-term solar-induced chlorophyll fluorescence dataset (SIF) and two satellite-based gross primary productivity (GPP) products to examine the patterns and trends of vegetation productivity within global karst ecosystems, and to assess the relative contributions of different countries to the restoration of these fragile ecosystems over the period 2001–2016. As an effective proxy for terrestrial GPP, SIF reveals a greening trend across most of the world's karst areas. China and the European Union (EU) lead the world in vegetation greening within their karst areas by 78.02% and 42.44%, respectively. The total net increase in SIF shows that China alone accounted for 43.66% with just 7.0% of global karst area. Brazil is the only country with a negative greening trend. Recent land cover changes caused by the grain-for-green programme in China and deforestation in Brazil account for 36.93% and 64.71% of the increases and decreases, respectively. Our results have significant implications for restoring ecosystem productivity in global karst areas