351 research outputs found
Forest and forest succession in Hong Kong, China
Hong Kong is on the northern margin of the Asian tropics. The original forest cover was cleared centuries ago but secondary forest has developed since 1945 at many sites protected from fire and cutting. There are also older forest patches maintained behind villages for reasons of 'feng shui', the Chinese system of geomancy. All plants >2cm dbh were identified and measured in forty-four 400-m2 plots. Detrended correpondence analysis showed a floristic continuum, with the motane sites (>500m) most distinct and some overlap between lowland post-1945 secondary forest and the feng shui woods. The 30-40 year-old secondary forest is dominated by Persea spp. Montane forest is similar but lacks several common lowland taxa of tropical genera and includes more subtropical taxa. The feng shui woods have the most complex structure and contain some tree species not found in other forest types. Their origin and history is obscure but we suggest that both planting and selective harvesting have had a role in their current species composition.published_or_final_versio
A numerical study of the impact of climate and emission changes on surface ozone over South China in Autumn time in 2000-2050
2012-2013 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe
On the Computational Precision of Finite Element Algorithms in Slope Stability Problems
Although the finite element method (FEM) has been used extensively to analyse the slope stability problems, the computational precision and definition of failure are still two main key concepts of finite element algorithms that attract the attention of researchers. In this paper, the modified Euler algorithm and the explicit modified Euler algorithm with stress corrections are used to analyse two dimensional (2D) slope stability problems with the associated flow rule, based on the shear strength reduction method. The rounded hyperbolic Mohr-Coulomb (M-C) yield surface is applied. Effects of the element type and various definitions of failure on the computational precision of 2D slope stability problems are evaluated. Conclusions can be drawn that the modified Euler scheme is applicable when the factor of safety (FOS) is small; however, the explicit modified Euler algorithm with stress corrections is more precise if the factor of safety is relatively large. The fully integrated quadrilateral isoparametric element is better than the triangular element in terms of the precision. With respect to the definition of failure, the displacement mutation of the characteristic point combining with the continuums of the plastic zone can be regarded as a reliable definition of failure and can be widely used to perform and analyse numerical simulations of slope stability problems
้ฃ็ฎก็ๅ็ผ็ถ่ๆทๅทด็ต่ฝ็งป็ถ็ดฐ่ๆ่ฒ้ซ่ฎๅ็นๅพ็ๆฏ่ผ
BACKGROUND & OBJECTIVE: Local lymph node and blood metastasis could occur at early stage of esophageal squamous cell carcinoma (ESCC), which may be the key factors of its recurrence and poor prognosis. However, the mechanism of ESCC metastasis is unclear. This study was to analyze the genetic changes in primary lesion and lymph node metastases of ESCC, to screen for and locate ESCC metastasis-related genes. METHODS: Genomic alterations in 15 pairs of primary lesions and matched metastatic lymph nodes of ESCC were analyzed by comparative genomic hybridization (CGH). RESULTS: In the 15 pairs of tissues, the most common chromosomal alterations were the gains of 3q, 8q, 6p, 20p, 5p, 18p, 2p, 2q and 1q, and the losses of 10p, 10q, 17p, 18q, 4p and 13q. Of these changes, the most significant finding was the gain of 6p with a frequency of 47% in metastatic lymph nodes and 13% in primary lesions, and the gain of 20p with a frequency of 73% in metastatic lymph nodes and 33% in primary lesions. The second interesting finding was the loss of 10p with a frequency of 53% in metastatic lymph nodes and 13% in primary lesions, and the loss of 10q with a frequency of 47% in metastatic lymph nodes and 13% in primary lesions. CONCLUSION: The gains of 6p and 20p and the losses of 10p and 10q are common genomic alterations in primary lesion and lymph node metastases of ESCC, which may code ESCC metastasis-related genes.่ๆฏ่็ฎ็:้ฃ็ฎก็ๆฉๆๅฏ็ผ็ๅฑ้จๆทๅทดๆ่ก่ก่ฝ็งป,้ๆฏๅฐ่ดๅพฉ็ผๅ้ ๅๅทฎ็ไธป่ฆๅๅ ใไฝๆฏ,้ฃ็ฎก็่ฝ็งป็ผ็็ๅๅญๆฉๅถๅฐไธๆธ
ๆฅใๆฌ็ ็ฉถๆจๅจๅๆ้ฃ็ฎก็ๅ็ผ็ถๅๆทๅทด็ต่ฝ็งป็ถ่
ซ็ค็ดฐ่ๆ่ฒ้ซ่ฎๅ็็นๅพ,ๅฐๆพๆๅฎไฝ่้ฃ็ฎก็่ฝ็งป็ธ้ๅบๅ ,ๅ ๆทฑๅฐๅ
ถ่ฝ็งปๆฉๅถ็ไบ่งฃใๆนๆณ:ๆ็จๆฏ่ผๅบๅ ็ต้ไบคๆ่ก(comparativegenomichybridization,CGH)ๅๆ15ไพ้ฃ็ฎก็ๆฃ่
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ถๅฐๆ็ๆทๅทด็ต่ฝ็งป็ถ็ๆ่ฒ้ซๅบๅ ็ตๆน่ฎใ็ตๆ:ๆๅธธ่ฆๆ่ฒ้ซDNAๆท่ฒๆธๅขๅ ็้จไฝๆฏ3q,8q,6p,20p,5p,18p,2p,2q,1q;ๅธธ่ฆ็ๆ่ฒ้ซDNAๆท่ฒๆธไธๅคฑ็้จไฝๆฏ10p,10q,17p,18q,4p,13qใๅ
ถไธญ,ๆๆๆ็พฉ็็ผ็พๆฏ6pๅขๅ (ๅ็ผ็ถ:2/15,13%,่ฝ็งป็ถ:7/15,47%),20pๅขๅ (ๅ็ผ็ถ:5/15,33.3%,่ฝ็งป็ถ:11/15,73.3%)ใ็ฌฌไบๅ็ผ็พๆฏ10pไธๅคฑ(ๅ็ผ็ถ:2/15,13.3%,่ฝ็งป็ถ:8/15,53%),10qไธๅคฑ(ๅ็ผ็ถ:2/15,13.3%,่ฝ็งป็ถ:7/15,46.6%)ใ็ต่ซ:้ฃ็ฎก็ๅ็ผ็ถๅๆทๅทด็ต่ฝ็งป็ถ็ดฐ่ๆ่ฒ้ซๅบๅ ็ตๆน่ฎๆ้กฏ่็้จไฝๆฏ6p,20p็ๅขๅ ๅ10p,10q็ไธๅคฑ;้ไบ้จไฝๅฏ่ฝๅญๅจ่้ฃ็ฎก็็ดฐ่ๆทๅทด็ต่ฝ็งป็ธ้็ๅบๅ ใlink_to_subscribed_fulltex
Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay
The decay channel
is studied using a sample of events collected
by the BESIII experiment at BEPCII. A strong enhancement at threshold is
observed in the invariant mass spectrum. The enhancement can be fit
with an -wave Breit-Wigner resonance function with a resulting peak mass of
and a
narrow width that is at the 90% confidence level.
These results are consistent with published BESII results. These mass and width
values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics
Genetic Diversity and Linkage Disequilibrium in Chinese Bread Wheat (Triticum aestivum L.) Revealed by SSR Markers
Two hundred and fifty bread wheat lines, mainly Chinese mini core accessions, were assayed for polymorphism and linkage disequilibrium (LD) based on 512 whole-genome microsatellite loci representing a mean marker density of 5.1 cM. A total of 6,724 alleles ranging from 1 to 49 per locus were identified in all collections. The mean PIC value was 0.650, ranging from 0 to 0.965. Population structure and principal coordinate analysis revealed that landraces and modern varieties were two relatively independent genetic sub-groups. Landraces had a higher allelic diversity than modern varieties with respect to both genomes and chromosomes in terms of total number of alleles and allelic richness. 3,833 (57.0%) and 2,788 (41.5%) rare alleles with frequencies of <5% were found in the landrace and modern variety gene pools, respectively, indicating greater numbers of rare variants, or likely new alleles, in landraces. Analysis of molecular variance (AMOVA) showed that A genome had the largest genetic differentiation and D genome the lowest. In contrast to genetic diversity, modern varieties displayed a wider average LD decay across the whole genome for locus pairs with r2>0.05 (P<0.001) than the landraces. Mean LD decay distance for the landraces at the whole genome level was <5 cM, while a higher LD decay distance of 5โ10 cM in modern varieties. LD decay distances were also somewhat different for each of the 21 chromosomes, being higher for most of the chromosomes in modern varieties (<5โผ25 cM) compared to landraces (<5โผ15 cM), presumably indicating the influences of domestication and breeding. This study facilitates predicting the marker density required to effectively associate genotypes with traits in Chinese wheat genetic resources
Synaptic Plasticity and NO-cGMP-PKG Signaling Regulate Pre- and Postsynaptic Alterations at Rat Lateral Amygdala Synapses Following Fear Conditioning
In vertebrate models of synaptic plasticity, signaling via the putative โretrograde messengerโ nitric oxide (NO) has been hypothesized to serve as a critical link between functional and structural alterations at pre- and postsynaptic sites. In the present study, we show that auditory Pavlovian fear conditioning is associated with significant and long-lasting increases in the expression of the postsynaptically-localized protein GluR1 and the presynaptically-localized proteins synaptophysin and synapsin in the lateral amygdala (LA) within 24 hrs following training. Further, we show that rats given intra-LA infusion of either the NR2B-selective antagonist Ifenprodil, the NOS inhibitor 7-Ni, or the PKG inhibitor Rp-8-Br-PET-cGMPS exhibit significant decreases in training-induced expression of GluR1, synaptophysin, and synapsin immunoreactivity in the LA, while those rats infused with the PKG activator 8-Br-cGMP exhibit a significant increase in these proteins in the LA. In contrast, rats given intra-LA infusion of the NO scavenger c-PTIO exhibit a significant decrease in synapsin and synaptophysin expression in the LA, but no significant impairment in the expression of GluR1. Finally, we show that intra-LA infusions of the ROCK inhibitor Y-27632 or the CaMKII inhibitor KN-93 impair training-induced expression of GluR1, synapsin, and synaptophysin in the LA. These findings suggest that the NO-cGMP-PKG, Rho/ROCK, and CaMKII signaling pathways regulate fear memory consolidation, in part, by promoting both pre- and post-synaptic alterations at LA synapses. They further suggest that synaptic plasticity in the LA during auditory fear conditioning promotes alterations at presynaptic sites via NO-driven โretrograde signalingโ
Mifepristone Increases the Cytotoxicity of Uterine Natural Killer Cells by Acting as a Glucocorticoid Antagonist via ERK Activation
Background: Mifepristone (RU486), a potent antagonist of progesterone and glucocorticoids, is involved in immune regulation. Our previous studies demonstrated that mifepristone directly augments the cytotoxicity of human uterine natural killer (uNK) cells. However, the mechanism responsible for this increase in cytotoxicity is not known. Here, we explored whether the increased cytotoxicity in uNK cells produced by mifepristone is due to either anti-progesterone or anti-glucocorticoid activity, and also investigated relevant changes in the mitogen-activated protein kinase (MAPK) pathway. Methodology/Principal Findings: Uterine NK cells were isolated from decidual samples and incubated with different concentrations of progesterone, cortisol, or mifepristone. The cytotoxicity and perforin expression of uNK cells were detected by mitochondrial lactate dehydrogenase-based MTS staining and flow cytometry assays, respectively. Phosphorylation of components of the MAPK signaling pathway was detected by Western blot. Cortisol attenuated uNK cell-mediated cytotoxicity in a concentration-dependent manner whereas progesterone had no effect. Mifepristone alone increased the cytotoxicity and perforin expression of uNK cells; these effects were blocked by cortisol. Furthermore, mifepristone increased the phosphorylation of ERK1/2 in a cortisol-reversible manner. Specific ERK1/2 inhibitor PD98059 or U0126 blocked cortisol- and mifepristone-induced responses in uNK cells
Direct Stimulation of Adult Neural Stem/Progenitor Cells In Vitro and Neurogenesis In Vivo by Salvianolic Acid B
Background: Small molecules have been shown to modulate the neurogenesis processes. In search for new therapeutic drugs, the herbs used in traditional medicines for neurogenesis are promising candidates. Methodology and Principal Findings: We selected a total of 45 natural compounds from Traditional Chinese herbal medicines which are extensively used in China to treat stroke clinically, and tested their proliferation-inducing activities on neural stem/progenitor cells (NSPCs). The screening results showed that salvianolic acid B (Sal B) displayed marked effects on the induction of proliferation of NSPCs. We further demonstrated that Sal B promoted NSPCs proliferation in dose- and time-dependent manners. To explore the molecular mechanism, PI3K/Akt, MEK/ERK and Notch signaling pathways were investigated. Cell proliferation assay demonstrated that Ly294002 (PI3K/Akt inhibitor), but neither U0126 (ERK inhibitor) nor DAPT (Notch inhibitor) inhibited the Sal B-induced proliferation of cells. Western Blotting results showed that stimulation of NSPCs with Sal B enhanced the phosphorylation of Akt, and Ly294002 abolished this effect, confirming the role of Akt in Sal B mediated proliferation of NSPCs. Rats exposed to transient cerebral ischemia were treated for 4 weeks with Sal B from the 7th day after stroke. BrdU incorporation assay results showed that exposure Sal B could maintain the proliferation of NSPCs after cerebral ischemia. Morris water maze test showed that delayed post-ischemic treatment with Sal B improved cognitive impairment after stroke in rats
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