The Impact of Irrigation on Bacterial Community Composition and Diversity in Liaohe Estuary Wetland     

Tiantian Li  Hong Hu  Zhengyan Li  Jianye Zhang  Dong Li 《中国海洋大学学报(英文版)》2018,17(4):855-863

In this study, the sequencing of 16S ribosomal DNA was used to characterize the soil bacterial community composition and diversity in Liaohe estuarine wetland. Soil samples were taken from different locations in the wetland dominated by reed. Moreover, the soil quality parameters were evaluated (pH, moisture, organic matter, total nitrogen, available nitrogen, total phosphorus, available phosphorus). The results showed that the organic matter and nutrient contents were significantly higher in irrigated wetland than those in natural wetland. Major phylogenic groups of bacteria in soil samples including Proteobacteria, Acidobacteria, Gemmatimonadetes, Actinobacteria and Cyanobacteria were analyzed and we found that Proteobacteria was the most abundant in the community, and the phylum Acidobacteria was more abundant in irrigated wetland. Beta diversity analyses indicated that the soil bacterial community was mainly affected by sampling sites rather than seasons. In general, the bacterial community in natural wetland was not significantly different with that in artificial irrigated wetland. Artificial hydraulic engineering irrigated according to the water requirement rule of reed, increased the production of reeds, changed the way of wetland soil material input, but the diversity of bacterial community kept stable relatively.  相似文献   

Quantitative morphometric analysis of the Jama River profile in a tectonically active margin (Northwestern Ecuador)     

Pedro S.B.REYES  Mauricio E.VALAREZO  Jenry CóRDOVA  Fran?ois A.MICHAUD  Camilo ZAPATA 《山地科学学报》2018,15(5):966-975

The longitudinal profile of a river channel can be described in function of mathematical expressions. The logarithmic fit is the most used method to describe the relative equilibrium of a channel elevation profile. Rivers showing zones of high channel gradient and convex-upward profiles can be evaluated in function of the offset distance with respect to the logarithmic curve. The Jama River profile has been constructed using differential GPS data for the downstream reach and 4-m-grid DEM data base for the remaining headward profile. The resulting longitudinal profile shows a prominent knickpoint of about 80 m in elevation characterized by sharp local convexity. The offset distance in vertical direction from the logarithmic plot is interpreted as the successive accumulation of multiple uplift episodes associated with the Jama Fault System activity. The horizontal offset is suggested to represent the remaining retreated distance for the upstream propagation of the Jama knickpoint. The highly resistant Cretaceous rocks outcropping along the Jama knickpoint reach acts as an inflection point between two subprofiles that show well-fitted logarithmic curves, thereby representing a temporary partitioned equilibrium along the Jama River profile.  相似文献   

The higher grain production,the more social deprivation? A case study of Henan province in traditional agricultural areas of China     

Jun-bo Gao  Wei-feng Qiao  Yan-sui Liu  Yu-rui Li  Wei Tu  Yong-xian Zhang 《山地科学学报》2018,15(1):167-180

This paper examines the spatial-temporal dynamics of inequality from the perspective of social deprivation in the context of continuous growth of grain production using national census data from 2000 and 2010 for Henan province, China. Our analytical results show an overall level of social deprivation that is high and a widening social deprivation gap at the county level. The social deprivation shows great spatiotemporal heterogeneity, the higher deprived counties are mainly distributed in central and eastern Henan province, while counties with lower social deprivation are clustered in northwestern regions, formed a belt-shape spatial differential between the south (higher deprived counties clustered) and northwest (low deprived counties clustered) Henan in 2000, and changed toward a core-periphery semi annular spatial structure in 2010, the low deprived counties surrounded by high deprived counties. The social deprivation shows a “west low and east high” spatial pattern, similar to the grain production in Henan province. Socioeconomic development level was low in most counties in Yudong plain despite of keeping the continuous increase of grain production, meaning the higher grain output did not result in the more social development expected in Chinese traditional agricultural areas, and the regional disparity is expected to increase in the near future if development conditions are not changed, which could inspire more targeted rural governance options.  相似文献   

Modeling of local ionospheric time varying characteristics based on singular value decomposition over low-latitude GPS stations     

Raghavendra Neeli  J R K Kumar Dabbakuti  V. Rajesh Chowdhary  Nitin K. Tripathi  Venkata Ratnam Devanaboyina 《Astrophysics and Space Science》2018,363(9):182

Singular Value Decomposition (SVD) model is implemented to recognize the Total Electron Content (TEC) time series of daily, temporal as well as seasonal characteristics throughout the 24th solar cycle period of the year 2015 in the study. The Vertical (vTEC) analysis has been carried out with Global Positioning System (GPS) data sets collected from five stations from India namely GNT, Guntur (16.44^° N, 80.62^° E), and IISC, Bangalore (12.97^° N, 77.59^° E), LCK2, Lucknow (26.76^° N, 80.88^° E), one station from Thailand namely AITB, Bangkok (14.07^° N, 100.61^° E), and one station from South Andaman Island namely PBR, Port Blair (11.43^° N, 92.43^° E), located in low latitude region. The first five singular value modes constitute about 98% of the total variance, which are linearly transformed from the observed TEC data sets. So it is viable to decrease the number of modeling parameters. The Fourier Series Analysis (FSA) is carried out to characterize the solar-cycle, annual and semi-annual dependences through modulating the first three singular values by the solar (F10.7) and geomagnetic (Ap) indices. The positive correlation coefficient (0.75) of daily averaged GPS–TEC with daily averaged F10.7 strongly supports the temporal variations of the ionospheric features depends on the solar activity. Further, the significance and reliability of the SVD model is evaluated by comparing it with GPS–TEC data and the standard global model (Standard Plasma-Spherical Ionospheric Model, SPIM and International Reference Ionosphere, IRI 2016).  相似文献   

Effects of Geometries and Substructures of ICMEs on Geomagnetic Storms     

Jae-Ok Lee  Kyung-Suk Cho  Rok-Soon Kim  Soojeong Jang  Katsuhide Marubashi 《Solar physics》2018,293(9):129

To better understand geomagnetic storm generations by ICMEs, we consider the effect of substructures (magnetic cloud, MC, and sheath) and geometries (impact location of flux-rope at the Earth) of the ICMEs. We apply the toroidal magnetic flux-rope model to 59 CDAW CME–ICME pairs to identify their substructures and geometries, and select 20 MC-associated and five sheath-associated storm events. We investigate the relationship between the storm strength indicated by minimum Dst index \((\mathrm{Dst}_{\mathrm{min}})\) and solar wind conditions related to a southward magnetic field. We find that all slopes of linear regression lines for sheath-storm events are steeper (\({\geq}\,1.4\)) than those of the MC-storm events in the relationship between \(\mathrm{Dst}_{\mathrm{min}}\) and solar wind conditions, implying that the efficiency of sheath for the process of geomagnetic storm generations is higher than that of MC. These results suggest that different general solar wind conditions (sheaths have a higher density, dynamic and thermal pressures with a higher fluctuation of the parameters and higher magnetic fields than MCs) have different impact on storm generation. Regarding the geometric encounter of ICMEs, 100% (2/2) of major storms (\(\mathrm{Dst}_{\mathrm{min}} \leq -100~\mbox{nT}\)) occur in the regions at negative \(P_{Y}\) (relative position of the Earth trajectory from the ICME axis in the \(Y\) component of the GSE coordinate) when the eastern flanks of ICMEs encounter the Earth. We find similar statistical trends in solar wind conditions, suggesting that the dependence of geomagnetic storms on 3D ICME–Earth impact geometries is caused by asymmetric distributions of the geoeffective solar wind conditions. For western flank events, 80% (4/5) of the major storms occur in positive \(P_{Y}\) regions, while intense geoeffective solar wind conditions are not located in the positive \(P_{Y}\). These results suggest that the strength of geomagnetic storms depends on ICME–Earth impact geometries as they determine the solar wind conditions at Earth.  相似文献   

Behaviour of physical parameters in extended gravity with hyperbolic function     

Fakhereh Md. Esmaeili  B. Mishra 《Journal of Astrophysics and Astronomy》2018,39(5):59

In this paper, we have constructed the cosmological model of the universe in f(R, T) theory of gravity in a Bianchi type \(\mathrm{VI}_h\) universe for the functional f(R, T) in the form \(f(R,T)=\mu R+\mu T\), where R and T are respectively Ricci scalar and trace of energy momentum tensor and \(\mu \) is a constant. We have made use of the hyperbolic scale factor to find the physical parameters and metric potentials defined in the space-time. The physical parameters are constrained from different representative values to build up a realistic cosmological model aligned with the observational behaviour. The state finder diagnostic pair is found to be in the acceptable range. The energy conditions of the model are also studied.  相似文献   

A recent history of science cases for optical interferometry     

Denis Defrère  Conny Aerts  Makoto Kishimoto  Pierre Léna 《Experimental Astronomy》2018,46(3):389-399

Optical long-baseline interferometry is a unique and powerful technique for astronomical research. Since the 1980’s (with I2T, GI2T, Mark I to III, SUSI, ...), optical interferometers have produced an increasing number of scientific papers covering various fields of astrophysics. As current interferometric facilities are reaching their maturity, we take the opportunity in this paper to summarize the conclusions of a few key meetings, workshops, and conferences dedicated to interferometry. We present the most persistent recommendations related to science cases and discuss some key technological developments required to address them. In the era of extremely large telescopes, optical long-baseline interferometers will remain crucial to probe the smallest spatial scales and make breakthrough discoveries.  相似文献   

New UV-source catalogs,UV spectral database,UV variables and science tools from the GALEX surveys     

Luciana Bianchi  Alexander de la Vega  Bernard Shiao  Ralph Bohlin 《Astrophysics and Space Science》2018,363(3):56

We present a new, expanded and improved catalog of Ultraviolet (UV) sources from the GALEX All-Sky Imaging survey: GUVcat_AIS (Bianchi et al. in Astrophys. J. Suppl. Ser. 230:24, 2017). The catalog includes 83 million unique sources (duplicate measurements and rim artifacts are removed) measured in far-UV and near-UV. With respect to previous versions (Bianchi et al. in Mon. Not. R. Astron. Soc. 411:2770 2011a, Adv. Space Res. 53:900–991, 2014), GUVcat_AIS covers a slightly larger area, 24,790 square degrees, and includes critical corrections and improvements, as well as new tags, in particular to identify sources in the footprint of extended objects, where pipeline source detection may fail and custom-photometry may be necessary. The UV unique-source catalog facilitates studies of density of sources, and matching of the UV samples with databases at other wavelengths.We also present first results from two ongoing projects, addressing respectively UV variability searches on time scales from seconds to years by mining the GALEX photon archive, and the construction of a database of ～120,000 GALEX UV spectra (range ～1300–3000 Å), including quality and calibration assessment and classification of the grism, hence serendipitous, spectral sources.  相似文献   

The First Solar Seeing Profile Measurement with Two Apertures and Multiple Guide Regions     

Deqing Ren  Gang Zhao  Xin Wang  Christian Beck  Robert Broadfoot 《Solar physics》2018,293(1):1

The sky brightness is a critical parameter for estimating the coronal observation conditions for a solar observatory. As part of a site-survey project in Western China, we measured the sky brightness continuously at the Lijiang Observatory in Yunnan province in 2011. A sky brightness monitor (SBM) was adopted to measure the sky brightness in a region extending from 4.5 to 7.0 apparent solar radii based on the experience of the Daniel K. Inouye Solar Telescope (DKIST) site survey. Every month, the data were collected manually for at least one week. We collected statistics of the sky brightness at four bandpasses located at 450, 530, 890, and 940 nm. The results indicate that aerosol scattering is of great importance for the diurnal variation of the sky brightness. For most of the year, the sky brightness remains under 20 millionths per airmass before local Noon. On average, the sky brightness is less than 20 millionths, which accounts for 40.41% of the total observing time on a clear day. The best observation time is from 9:00 to 13:00 (Beijing time). The Lijiang Observatory is therefore suitable for coronagraphs investigating the structures and dynamics of the corona.  相似文献   

The Space System for Remote Sensing of the Earth Based on the <Emphasis Type="Italic">Arkon</Emphasis> Satellite (On the 20th Anniversary of the First Launch)     

V. V. Efanov  N. N. Klimenko  V. I. Semunkina  S. V. Shostak 《Solar System Research》2018,52(7):597-605

On the eve of the 20th anniversary of the first launch of the Arkon satellite, the article provides a retrospective of the birth, implementation, and development of this unique project that has no comparable counterparts. The authors also single out those remarkable teams of developers and their leaders whose activities have become part of the history of the Lavochkin Research and Production Association and its pride.  相似文献