Simulation Studies for the First Pathfinder of the CATCH Space Mission

The Chasing All Transients Constellation Hunters (CATCH) space mission is an intelligent constellation consisting of 126 micro-satellites in three types (A, B, and C), designed for X-ray observation with the objective of studying the dynamic universe. Currently, we are actively developing the first Pathfinder (CATCH-1) for the CATCH mission, specifically for type-A satellites. CATCH-1 is equipped with Micro Pore Optics (MPO) and a 4-pixel Silicon Drift Detector (SDD) array. To assess its scientific performance, including the effective area of the optical system, on-orbit background, and telescope sensitivity, we employ the Monte Carlo software Geant4 for simulation in this study. The MPO optics exhibit an effective area of $41$ cm$^2$ at the focal spot for 1 keV X-rays, while the entire telescope system achieves an effective area of $29$ cm$^2$ at 1 keV when taking into account the SDD detector's detection efficiency. The primary contribution to the background is found to be from the Cosmic X-ray Background. Assuming a 625 km orbit with an inclination of $29^\circ$, the total background for CATCH-1 is estimated to be $8.13\times10^{-2}$ counts s$^{-1}$ in the energy range of 0.5--4 keV. Based on the background within the central detector and assuming a Crab-like source spectrum, the estimated ideal sensitivity could achieve $1.9\times10^{-12}$ erg cm$^{-2}$ s$^{-1}$ for an exposure of 10$^4$ s in the energy band of 0.5--4 keV. Furthermore, after simulating the background caused by low-energy charged particles near the geomagnetic equator, we have determined that there is no need to install a magnetic deflector

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Enhancing Ecosystem Services in the Agro-Pastoral Transitional Zone Based on Local Sustainable Management: Insights from Duolun County in Northern China

Ecosystem and associated ecosystem services (ESs) in the agro-pastoral transitional zone of northern China (APTZNC) are sensitive to climate change and human activities. Essential to designing targeted policy interventions toward achieving sustainability in the APTZNC is a comprehensive understanding of the spatiotemporal changes in ESs and their drivers. This study identified the spatiotemporal changes in six ESs in Duolun County from 2000 to 2017. The impacts of drivers—temperature, precipitation, wind speed, vegetation cover (FVC), land use/cover (LULC), soil type, altitude, and slope—on the changes in the ESs in the county and its ecological production zones were then explored. The results indicated that the six ESs improved during the study period. The drivers influencing changes in ESs over time exhibited similarities across regions. Although FVC contributed to improvements in the food supply, grass production, carbon sequestration, and soil wind erosion (SLwind), it also reduced water yield, which may exacerbate the water shortage in arid and semi-arid areas. In regions where the ecology was in the recovery phase, especially in slope farmland, the inhibition of soil water erosion (SLwater) by FVC was easily offset by the higher SLwater potential from increased precipitation. The decrease in wind speed improved the regional ESs, whereas the increase in temperature posed a threat to SLwind. The drivers affecting the spatial patterns of ESs varied among zones. Across the three zones, the greater influential drivers of ESs were FVC and LULC. The impacts of topographic drivers and soil type on the distribution of ESs should also be noted in the agro-zone and agro-pastoral zone, respectively. Our study advocated that ES management should be adjusted to local conditions, and differentiated planning policies should be implemented in line with the ecological characteristics in the APTZNC, which will contribute to regional ecological sustainable development

Enhancing Ecosystem Services in the Agro-Pastoral Transitional Zone Based on Local Sustainable Management: Insights from Duolun County in Northern China

Ecosystem and associated ecosystem services (ESs) in the agro-pastoral transitional zone of northern China (APTZNC) are sensitive to climate change and human activities. Essential to designing targeted policy interventions toward achieving sustainability in the APTZNC is a comprehensive understanding of the spatiotemporal changes in ESs and their drivers. This study identified the spatiotemporal changes in six ESs in Duolun County from 2000 to 2017. The impacts of drivers—temperature, precipitation, wind speed, vegetation cover (FVC), land use/cover (LULC), soil type, altitude, and slope—on the changes in the ESs in the county and its ecological production zones were then explored. The results indicated that the six ESs improved during the study period. The drivers influencing changes in ESs over time exhibited similarities across regions. Although FVC contributed to improvements in the food supply, grass production, carbon sequestration, and soil wind erosion (SLwind), it also reduced water yield, which may exacerbate the water shortage in arid and semi-arid areas. In regions where the ecology was in the recovery phase, especially in slope farmland, the inhibition of soil water erosion (SLwater) by FVC was easily offset by the higher SLwater potential from increased precipitation. The decrease in wind speed improved the regional ESs, whereas the increase in temperature posed a threat to SLwind. The drivers affecting the spatial patterns of ESs varied among zones. Across the three zones, the greater influential drivers of ESs were FVC and LULC. The impacts of topographic drivers and soil type on the distribution of ESs should also be noted in the agro-zone and agro-pastoral zone, respectively. Our study advocated that ES management should be adjusted to local conditions, and differentiated planning policies should be implemented in line with the ecological characteristics in the APTZNC, which will contribute to regional ecological sustainable development

Marine Environmental Regionalization for the Beibu Gulf Based on a Physical-Biological Model

A physical–biological ocean model was employed to investigate characteristics of the Beibu Gulf in the northwest South China Sea (SCS) from 2011 to 2015. We adopted the spatially constrained multivariate clustering method to determine the refined marine environmental regionalization using 10 variables from the model output, and compared regionalization differences in ENSO (El Niño–Southern Oscillation) years. The simulated physical and biochemical variables display a wide spectrum of patterns in space and time. The regionalization maps indicated that the Qiongzhou Strait and its adjacent area can be classified as a separate region, characterized by the rich presence of nutrients, phytoplankton, zooplankton, and detritus, owing to the water invasion from the western Guangdong estuary. As a result of the invasive progression of the SCS, the northern and southern gulf show distinct features over a boundary near 20° N. In the La Niña year (2011), the classified boundary of the Qiongzhou Strait-northeastern gulf moved southwards due to enhanced phytoplankton growth. In the El Niño year (2015), the current collision from the northern gulf and SCS resulted in the boundary of the northern and southern gulf moving to approximately 19° N. These results provide useful guidance on subregional marine management and subregional studies for the gulf

A Fast-Response Ultraviolet Phototransistor with a PVK QDs/ZnO Nanowire Heterostructure and Its Application in Pharmaceutical Solute Detection

The sensitivity and photoelectric noise of UV photodetectors are challenges that need to be overcome in pharmaceutical solute detection applications. This paper presents a new device concept for a CsPbBr3 QDs/ZnO nanowire heterojunction structure for phototransistors. The lattice match of the CsPbBr3 QDs and ZnO nanowire reduces the generation of trap centers and avoids carrier absorption by the composite center, which greatly improves the carrier mobility and high detectivity (8.13 × 1014 Jones). It is worth noting that by using high-efficiency PVK quantum dots as the intrinsic sensing core, the device has a high responsivity (6381 A/W) and responsivity frequency (300 Hz). Thus, a UV detection system for pharmaceutical solute detection is demonstrated, and the type of solute in the chemical solution is estimated by the waveform and the size of the output 2f signals