11 research outputs found
Change detection of land use and land cover of the southeast coastal area in Fujian, China
No full text
Modelling study on the impact of deep building foundations on the groundwater system
No full textCoastal areas are usually the preferred place of habitation for human beings. Anthropogenic activities such as the construction of high-rise buildings and underground transport systems usually require extensive deep foundations and ground engineering works, which may unintentionally modify the coastal groundwater system because the construction materials of foundations are usually of low hydraulic conductivity. In this paper, the impact of these building foundations on the groundwater regime is studied using hypothetical flow and transport models. Various possible realizations of foundation distributions are generated using stochastic parameters derived from a topographical map of an actual coastal area in Hong Kong. The effective hydraulic conductivity is first calculated for different realizations and the results show that the effective hydraulic conductivity can be reduced significantly. Then a hypothetical numerical model based on FEFLOW is set up to study the change of hydraulic head, groundwater discharge, and saltwater-fresh water interface. The groundwater level and flow are modified to various degrees, depending on the foundations percentage and the distribution pattern of the buildings. When the foundations percentage is high and the building foundations are aggregated, the hydraulic head is raised significantly and the originally one-dimensional groundwater flow field becomes complicated. Seaward groundwater discharge will be reduced and some groundwater may become seepage through the ground surface. The transport model shows that, after foundations are added, overall the seawater and fresh groundwater interface moves landward, so extensive foundations may induce seawater intrusion. It is believed that the modification of the coastal groundwater system by building foundations may have engineering and environmental implications, such as submarine groundwater discharge, foundation corrosion, and slope stability. Copyright © 2007 John Wiley & Sons, Ltd.link_to_subscribed_fulltex
Physical mechanisms for the offshore detachment of the Changjiang Diluted Water in the East China Sea
Get PDFAuthor Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C02002, doi:10.1029/2006JC003994.Physical mechanisms for the summertime offshore detachment of the Changjiang Diluted Water (CDW) into the East China Sea are examined using the high-resolution, unstructured-grid, Finite-Volume Coastal Ocean Model (FVCOM). The model results suggest that isolated low salinity water lens detected west of Cheju Island can be formed by (1) a large-scale adjustment of the flow field to the Changjiang discharge and (2) the detachment of anticyclonic eddies as a result of baroclinic instability of the CDW front. Adding the Changjiang discharge intensifies the clockwise vorticity of the subsurface current (originating from the Taiwan Warm Current) flowing along the 50-m isobath and thus drives the low-salinity water in the northern coastal area of the Changjiang mouth offshore over a submerged plateau that extends toward Cheju Island. Given a model horizontal resolution of less than 1.0 km, the CDW front becomes baroclinically unstable and forms a chain of anticyclonic and cyclonic eddies. The offshore detachment of anticyclonic eddies can carry the CDW offshore. This process is enhanced under northward winds as a result of the spatially nonuniform interaction of wind-induced Ekman flow and eddy-generated frontal density currents. Characteristics of the model-predicted eddy field are consistent with previous theoretical studies of baroclinic instability of buoyancy-driven coastal density currents and existing satellite imagery. The plume stability is controlled by the horizontal Ekman number. In the Changjiang, this number is much smaller than the criterion suggested by a theoretical analysis.The development of FVCOM is supported
by the Massachusetts Fisheries Institute through NOAA grants DOC/
NOAA/NA04NMF4720332 and DOC/NOAA/NA05NMF4721131 and also
the U.S. GLOBEC Northwest Atlantic/Georges Bank program through
NSF grants OCE-0234545 and OCE-0227679, NOAA grant NA160P2323
and ONR subcontract grant from Woods Hole Oceanographic Institution. P. Ding
is supported by the Chinese National Key Basic Research Project grant
2002CB412403. X. Mao is supported by the National Natural Science
Foundation of China (NSFC) grant 40576079
Phytoliths and rice: from wet to dry and back again in the Neolithic Lower Yangtze
Get PDFMore than half of the world’s population today relies on rice as its main staple food, and the expansion of rice farming has had a major impact on Asian environments. The trajectories from wild to cultivated to domesticated rice and the development of more intensive arable systems, provided a basis for the development of social complexity in China, mainland Southeast Asia and parts of India (Glover and Higham 1996; Fuller and Qin 2009; 2010). The spread of wet rice agriculture has also been linked to methane expansion and global warming (Ruddiman et al. 2008; Ruddiman 2013; Fuller et al. 2011). Distinguishing between wet and dry farmed rice in archaeological contexts is key to understanding developing rice systems and their role in both socioeconomic change and environmental impacts. One method of determining changes in arable system is to analyse ecological community groupings in the weed assemblages, which has long been applied in Europe (e.g. Jones 1995; Charles et al. 2003), and more recently to rice cultivation (Fuller & Qin 2009; Weisskopf et al. 2014). In the present contribution we present a new method and illustrate it by application to sites from a sequence in the Lower Yangtze region of China.
In this paper we use differing ratios of phytolith morphotypes that are divided into those that are genetically predisposed to produce silica bodies in grasses (fixed) and those morphotypes that are formed only when there is sufficient uptake of water (sensitive). Madella et al. (2009) developed this model using ratios of short to long cell phytoliths from the leaves of grasses from the Triticaceae family to understand winter cereal irrigation (of wheat or barley) in arid zones in the Near East. Jenkins et al. (2011) expanded this, also using Triticaceae, with experimental work in Jordan to further interpret Near Eastern water management. Here, this model is taken a step further and, using ratios of fixed and sensitive cells from all available Poaceae in the phytolith assemblages, applied to ethnographic rice field samples from India and Chinese archaeological sites that provide a sequence of change from ca. 5000 BC to 2300 BC
Labor costs for prehistoric earthwork construction: experimental and archaeological insights from the Lower Yangzi Basin, China
No full textThis is the accepted manuscript of an article published by the Society for American Archaeology © 2015. Used by permission from American Antiquity, volume 80, number 1.This paper examines choices of earth-working tools made by Neolithic Chinese populations. In the Hemudu Culture (7000–5000 B.P.), bone (scapula) digging tools were used from the earliest times, whereas peoples in surrounding areas used stone spades. A range of experiments on manufacturing costs, durability, and use efficiency under realistic conditions show that bone and stone spades are functionally equivalent when soils are soft, but that stone implements provide significant and easily perceived advantages when working harder soils. The persistence of scapular spades in the Hemudu Culture would have constrained decisions about undertaking large construction projects under normal soil conditions. Our results show that, in addition to generalized labor for construction, labor demands for producing earth-working implements for largescale prehistoric earthworks could have also been substantial. These findings not only help explain the processes of intensifying rice-agriculture and sedentary settlements in the Lower Yangzi Basin, but also create a solid foundation for further investigation of how the recruitment of both generalized and specialized laborers, the organization of craft production, and the relevant logistics for large-scale earthworks may have paralleled concentrations of political power in prehistory.This research was funded by a Henry R. Luce Foundation Dissertation Fellowship/American Council of Learned Societies grant (#9431 01 18 04 01-7301) awarded to the first author and by the University of Arizona Je Tsongkhapa Endowment for Central and Inner Asian Archaeology
PCR analysis and phenotypes of mutants.
No full text<p>(A) PCR verification of gene deletion. Lane 1, a 42,725 bp fragment was amplified using primers ZB287/ZB288. The size of the fragment was too large and could not be PCR-amplified, thus no band was seen in lane 1. Lane 2, a 1981 bp fragment was amplified using primers ZB287/ZB288. The CDA biosynthetic gene cluster was replaced with the <i>aac(3)IV</i> gene. Lane3, a 927 bp fragment was amplified using primers ZB287/ZB288, and the resistance gene was removed. Lane 4, a 4073 bp fragment was amplified with primers ZB289/ZB290. Lanes 5 and 6 showed the bands before and after removing the <i>aphII</i> resistance gene. Lane 7, a 928 bp fragment was amplified with primers ZB285/ZB286. Lanes 8 and 9 showed thebands before and after removing the <i>aphII</i> resistance gene. WT, wild type strain; ZB1∼ZB8, serial mutant strains. (B) PCR verification of gene deletion. Lane 1: the fragment was amplified with primers ZB145/ZB146 and primers were both within <i>sco3229</i>. Lane 2: the fragment was amplified with primers ZB195/ZB196 and primerZB195 was within <i>sco5089</i> and primer ZB196 was within <i>sco5090</i>. Lane 3: the fragment was amplified with primers ZB184/ZB186 and primerZB184 was within <i>sco1103</i> and primer ZB184 was within <i>sco1104</i>. Lane 4: the fragment as a positive control was amplified with primers ZB147/ZB148 and primers were both within <i>sco5888</i>. M: 150 bp ladder. (C) PCR verification of the resistance removing. Lane 1: M145; Lane 2: ZB1; Lane 3: ZB2. The three fragments were amplified with primers ZB189/ZB190, primers were both within the <i>acc(3)IV</i> gene. Lane 4: M 145; Lane 5: ZB3; Lane 6: ZB4; Lane 7: ZB7; Lane 8: ZB8. The five fragments were amplified with primers ZB187/ZB188, primers were both within the <i>aphII</i> gene. M: 150 bp ladder. (D) Bioassay of CDA extracts from the WT strain and CDA-null mutant strain ZB2. (E) Phenotypes of wild-type and three mutant strains. The spores were cultured for 2 days (left) and 5 days (right) on R2YE agar.</p
RifZ (AMED_0655) Is a Pathway-Specific Regulator for Rifamycin Biosynthesis in Amycolatopsis mediterranei
No full textABSTRACT
Rifamycin and its derivatives are particularly effective against the pathogenic mycobacteria
Mycobacterium tuberculosis
and
Mycobacterium leprae
. Although the biosynthetic pathway of rifamycin has been extensively studied in
Amycolatopsis mediterranei
, little is known about the regulation in rifamycin biosynthesis. Here, an
in vivo
transposon system was employed to identify genes involved in the regulation of rifamycin production in
A. mediterranei
U32. In total, nine rifamycin-deficient mutants were isolated, among which three mutants had the transposon inserted in
AMED_0655
(
rifZ
, encoding a LuxR family regulator). The
rifZ
gene was further knocked out via homologous recombination, and the transcription of genes in the rifamycin biosynthetic gene cluster (
rif
cluster) was remarkably reduced in the
rifZ
null mutant. Based on the cotranscription assay results, genes within the
rif
cluster were grouped into 10 operons, sharing six promoter regions. By use of electrophoretic mobility shift assay and DNase I footprinting assay, RifZ was proved to specially bind to all six promoter regions, which was consistent with the fact that RifZ regulated the transcription of the whole
rif
cluster. The binding consensus sequence was further characterized through alignment using the RifZ-protected DNA sequences. By use of bionformatic analysis, another five promoters containing the RifZ box (CTACC-N8-GGATG) were identified, among which the binding of RifZ to the promoter regions of both
rifK
and
orf18
(
AMED_0645
) was further verified. As RifZ directly regulates the transcription of all operons within the
rif
cluster, we propose that RifZ is a pathway-specific regulator for the
rif
cluster.
IMPORTANCE
To this day, rifamycin and its derivatives are still the first-line antituberculosis drugs. The biosynthesis of rifamycin has been extensively studied, and most biosynthetic processes have been characterized. However, little is known about the regulation of the transcription of the rifamycin biosynthetic gene cluster (
rif
cluster), and no regulator has been characterized. Through the employment of transposon screening, we here characterized a LuxR family regulator, RifZ, as a direct transcriptional activator for the
rif
cluster. As RifZ directly regulates the transcription of the entire
rif
cluster, it is considered a pathway-specific regulator for rifamycin biosynthesis. Therefore, as the first regulator characterized for direct regulation of
rif
cluster transcription, RifZ may provide a new clue for further engineering of high-yield industrial strains.
</jats:p
Multiplex precise base editing in cynomolgus monkeys
No full text© 2020, The Author(s). Common polygenic diseases result from compounded risk contributed by multiple genetic variants, meaning that simultaneous correction or introduction of single nucleotide variants is required for disease modeling and gene therapy. Here, we show precise, efficient, and simultaneous multiplex base editing of up to three target sites across 11 genes/loci in cynomolgus monkey embryos using CRISPR-based cytidine- and adenine-base editors. Unbiased whole genome sequencing demonstrates high specificity of base editing in monkey embryos. Our data demonstrate feasibility of multiplex base editing for polygenic disease modeling in primate zygotes
Germline variation at 8q24 and prostate cancer risk in men of European ancestry (vol 9, 4616, 2018)
No full textCorrection to: Nature Communications; https://doi.org/10.1038/s41467-018-06863-1, published online 5 November 2018.</p
