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Search Results: 1 - 10 of 220664 matches for " L. Yao "
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Multi-scale interactions of geological processes during mineralization: cascade dynamics model and multifractal simulation
L. Yao,Q. Cheng
Nonlinear Processes in Geophysics (NPG) , 2011,
Abstract: Relations between mineralization and certain geological processes are established mostly by geologist's knowledge of field observations. However, these relations are descriptive and a quantitative model of how certain geological processes strengthen or hinder mineralization is not clear, that is to say, the mechanism of the interactions between mineralization and the geological framework has not been thoroughly studied. The dynamics behind these interactions are key in the understanding of fractal or multifractal formations caused by mineralization, among which singularities arise due to anomalous concentration of metals in narrow space. From a statistical point of view, we think that cascade dynamics play an important role in mineralization and studying them can reveal the nature of the various interactions throughout the process. We have constructed a multiplicative cascade model to simulate these dynamics. The probabilities of mineral deposit occurrences are used to represent direct results of mineralization. Multifractal simulation of probabilities of mineral potential based on our model is exemplified by a case study dealing with hydrothermal gold deposits in southern Nova Scotia, Canada. The extent of the impacts of certain geological processes on gold mineralization is related to the scale of the cascade process, especially to the maximum cascade division number nmax. Our research helps to understand how the singularity occurs during mineralization, which remains unanswered up to now, and the simulation may provide a more accurate distribution of mineral deposit occurrences that can be used to improve the results of the weights of evidence model in mapping mineral potential.
Sex lethal and upstream ORFs: a bait-and-trap system for ribosomes
Peng Yao, Paul L Fox
Genome Biology , 2011, DOI: 10.1186/gb-2011-12-7-121
Abstract: Upstream open reading frames (uORFs) in mRNAs are short sequences in the 5' untranslated region (UTR) characterized by a start codon, a short open reading frame (ORF) and a stop codon, all upstream of the major start codon that initiates translation of the principal gene product. (The term UTR is actually a misnomer, precisely because of the existence of uORFs, and is more accurately referred to as transcript leader region [1].) A ribosome encountering a uORF has several options, including scanning through the uORF until the major ORF is encountered, translating the uORF and then reinitiating translation of the major ORF, or translating the uORF and then stalling. The latter case can lead to decreased translation of the major ORF, or possibly shortened mRNA half-life by nonsense-mediated decay [1]. Thus, uORFs present diverse opportunities for regulation of gene expression. The likely importance of uORFs is suggested by their presence in about half of all annotated transcripts in both humans and mice [2]. Analysis of a group of uORF-containing mRNAs showed that uORFs reduce protein expression by 30 to 80%. uORF-altering mutations have been predicted or confirmed in more than a dozen human-disease-associated genes [2]. The molecular mechanisms underlying the effect of uORFs on translation are not well understood. There is overwhelming evidence for the importance of mRNA secondary structure in uORF-mediated regulation of translation [3,4]; however, a role for specific 5' UTR-binding proteins is less certain. In an elegant report in Cell, Matthias Hentze and colleagues [5] elucidate a uORF-dependent mechanism by which the Drosophila mRNA-binding protein Sex lethal (Sxl) inhibits translation of its target transcript, male-specific lethal (msl)-2.In Drosophila, dosage compensation equalizes the expression of X-linked genes in males and females. In male flies, the msl-2-containing dosage compensation complex is required for hypertranscription of the single X chromosome [6
New achievements in glaciology in Tibet, China
Tandong Yao,L. G. Thompson
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02883232
Abstract:
Supermicron modes of ammonium ions related to fog in rural atmosphere
X. H. Yao,L. Zhang
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2012,
Abstract: Fog-processed aerosols were identified and analyzed in detail from a large-sized database in which size-segregated atmospheric particles and gases were simultaneously measured at eight Canadian rural sites. In ten samples collected during or following fog events, at least one supermicron mode of particulate NH4+ was observed. The supermicron modes were likely associated with fog events since they were absent on non-fog days. The supermicron mode of NH4+ in the 5–10 μm size range probably reflected the direct contribution from fog droplets. Based on detailed analysis of the chemical compositions and the extent of neutralization, the supermicron mode of NH4+ in the 1–4 μm size range was believed to be caused by fog-processing of ammonium salt aerosols. These aerosol particles consisted of incompletely neutralized sulfuric acid aerosols in NH3-poor conditions or a mixture of ammonium nitrate and ammonium sulfate aerosols in NH3-rich conditions. Interstitial aerosols and fog droplets presented during fog events likely yielded a minor direct contribution to the measured NH4+. The mass median aerodynamic diameter (MMAD) of the 1–4 μm mode of NH4+ strongly depended on ambient temperature (T) and can be grouped into two regimes. In one regime, the MMAD was between 1.1 and 1.7 μm in four samples, when fog occurred at T > 0 °C, and in two samples, at T > 3 °C. The MMAD of NH4+ in this size range was also observed in various atmospheric environments, as discussed in the literature. In the other regime, the MMAD was between 2.8 and 3.4 μm in four samples when fog occurred at T < 4 °C, a phenomenon that was first observed in this study. The MMAD was not related to chemical composition and concentration of ammonium salts. Further investigations are needed in order to fully understand the cause of the MMAD. The larger supermicron mode of ammonium salts aerosol observed at T < 4 °C has added new knowledge on the size distributions and chemical compositions of fog-processed aerosols under various ambient conditions.
The electronic and optical properties of carbon-doped SrTiO3: Density functional characterization
N. Li,K. L. Yao
AIP Advances , 2012, DOI: 10.1063/1.4746023
Abstract: The electronic properties and optical activities of C-doped cubic SrTiO3 in perovskite structure are studied by first-principles calculation. The calculated formation energies show that the substitutional C impurity is preferentially occupied at the Ti site. For C@O, the C impurity introduces spin-polarized gap states, and the associated electron excitations among the valence band, the conduction band and the gap states produce various visible-light absorption thresholds. For C@Ti, some C gap states of s-character appear near the bottom of the conduction band, which result in the lowered optical transition energy and thus the visible light absorption as observed in the experiment.
A Regression-based K nearest neighbor algorithm for gene function prediction from heterogeneous data
Yao Zizhen,Ruzzo Walter L
BMC Bioinformatics , 2006, DOI: 10.1186/1471-2105-7-s1-s11
Abstract: Background As a variety of functional genomic and proteomic techniques become available, there is an increasing need for functional analysis methodologies that integrate heterogeneous data sources. Methods In this paper, we address this issue by proposing a general framework for gene function prediction based on the k-nearest-neighbor (KNN) algorithm. The choice of KNN is motivated by its simplicity, flexibility to incorporate different data types and adaptability to irregular feature spaces. A weakness of traditional KNN methods, especially when handling heterogeneous data, is that performance is subject to the often ad hoc choice of similarity metric. To address this weakness, we apply regression methods to infer a similarity metric as a weighted combination of a set of base similarity measures, which helps to locate the neighbors that are most likely to be in the same class as the target gene. We also suggest a novel voting scheme to generate confidence scores that estimate the accuracy of predictions. The method gracefully extends to multi-way classification problems. Results We apply this technique to gene function prediction according to three well-known Escherichia coli classification schemes suggested by biologists, using information derived from microarray and genome sequencing data. We demonstrate that our algorithm dramatically outperforms the naive KNN methods and is competitive with support vector machine (SVM) algorithms for integrating heterogenous data. We also show that by combining different data sources, prediction accuracy can improve significantly. Conclusion Our extension of KNN with automatic feature weighting, multi-class prediction, and probabilistic inference, enhance prediction accuracy significantly while remaining efficient, intuitive and flexible. This general framework can also be applied to similar classification problems involving heterogeneous datasets.
Supermicron modes of ammonium ions related to fog in rural atmosphere
X. H. Yao,L. Zhang
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2012, DOI: 10.5194/acp-12-11165-2012
Abstract: Fog-processed aerosols were identified and analyzed in detail from a large-sized database in which size-segregated atmospheric particles and gases were simultaneously measured at eight Canadian rural sites. In ten samples collected during or following fog events, at least one supermicron mode of particulate NH4+ was observed. The supermicron modes were likely associated with fog events since they were absent on non-fog days. The supermicron mode of NH4+ in the 5–10 μm size range probably reflected the direct contribution from fog droplets. Based on detailed analysis of the chemical compositions and the extent of neutralization, the supermicron mode of NH4+ in the 1–4 μm size range was believed to be caused by fog-processing of ammonium salt aerosols. These aerosol particles consisted of incompletely neutralized sulfuric acid aerosols in NH3-poor conditions or a mixture of ammonium nitrate and ammonium sulfate aerosols in NH3-rich conditions. Interstitial aerosols and fog droplets presented during fog events likely yielded a minor direct contribution to the measured NH4+. The mass median aerodynamic diameter (MMAD) of the 1–4 μm mode of NH4+ strongly depended on ambient temperature (T) and can be grouped into two regimes. In one regime, the MMAD was between 1.1 and 1.7 μm in four samples, when fog occurred at T > 0 °C, and in two samples, at T > 3 °C. The MMAD of NH4+ in this size range was also observed in various atmospheric environments, as discussed in the literature. In the other regime, the MMAD was between 2.8 and 3.4 μm in four samples when fog occurred at T < 4 °C, a phenomenon that was first observed in this study. The MMAD was not related to chemical composition and concentration of ammonium salts. Further investigations are needed in order to fully understand the cause of the MMAD. The larger supermicron mode of ammonium salts aerosol observed at T < 4 °C has added new knowledge on the size distributions and chemical compositions of fog-processed aerosols under various ambient conditions.
Capacity Worth of Energy Storage System in Renewable Power Generation Plant  [PDF]
Jinbin Li, Yao Yao
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.59B001
Abstract: With the advance in renewable generation technologies, the cost of renewable energy becomes increasingly competitive when compared to fossil fuel-based generation resources. It is economically beneficial to integrate large amounts of renewable capacity in power systems. Unlike traditional generation facilities, however, using renewable resources for generation presents technical challenges in producing continuous power. In this report, an Energy Storage System (ESS) is integrated to smooth the variations in renewable power production and ensure the output power more controllable. Since it requires capital investment for the storage devices, it is important to obtain reasonable estimate of the storage capacities. This project is therefore formulated as an optimization problem in determining the two dominating factors of the capital cost for the ESS: the power capacity and the energy capacity. The objective is to make the renewable power more reliable and simultaneously maximize the economic benefits that can be obtained from the scheme. To make the results more convincing, analyses in this report start with wind generation, for wind has greater variability and unpredictability than other renewable sources. Selection of ESS type is narrowed down to battery energy storage system (BESS) in the scheme. However, the methods presented here are suitable for any type of energy storage methods and are also useful for intermittent renewable energy resources other than wind.
The Senile Brucellosis Spondylitis Clinical Diagnosis and Treatment on as Evaluation Were Retrospectively Analyzed  [PDF]
Yao Yao, Xinming Yang
Surgical Science (SS) , 2018, DOI: 10.4236/ss.2018.98032
Abstract: Objective: To explore senile brucellosis spondylitis clinical features and diagnostic criteria, in order to improve the diagnosis rate and evaluate the clinical effects of treatment strategies. Methods: From January 2002 to August 2015, 62 patients with Brucella-associated spondylitis were treated with comprehensive diagnosis based on epidemiological history, clinical manifestations, imaging findings, laboratory tests, and local biopsy. The positive rate of red plate agglutination test (RBPT) was 45.1%, the positive rate of serum tube agglutination test (SAT) was 51.6%, and the positive rate of brucellosis anti-human immunoglobulin test (Coomb’s) was 100%. All patients underwent X-ray, CT and MRI examinations. The positive rate of blood culture in pathogenic examination was 16.1%, and the positive rate of bone marrow culture was 38.5%. The positive rate of inflammatory granuloma or abscess in the lesion sampling culture was 73.6%. All patients underwent standardized drug therapy and hyperbaric oxygen adjuvant therapy. Among them, 38 patients with neurological impairment were treated with one-stage debridement and posterior pedicle screw fixation on the basis of drug therapy. The paraspinal abscess and the diseased in-tervertebral space tissue were taken for pathological examination during the operation. One week, two weeks, one month, three months, six months and 12 months after treatment, the patients were evaluated and followed up at the monitoring sites. The evaluation indicators were pain scores, activity of daily living (ADL), imaging findings, and laboratory tests. The SPSS15.0 statistical package was used for analysis. Results: All patients were confirmed by the above-mentioned comprehensive examination after admission. 24 patients (38.71%) were treated with standard drug therapy (group A), no adverse drug reactions and abnormal liver and kidney function; the remaining 38 patients (61.29%) were combined with varying degrees of neurological impairment, and surgical treatment was performed after 2 to 4 weeks of drug therapy without improvement (group B). The pain scores showed that there was a statistically significant difference between the two groups at the same time point (P < 0.05). The B group was superior to the A group in both treatment time and pain relief. The blind test evaluation of imaging observation showed that in group B, except for the slow repair of the lesion area, the spine was stable without abscess, sequestrum and inflammatory granulomas, and the score area was stable at 4 -
The Impacts of Graphene Nanosheets and Manganese Valency on Lithium Storage Characteristics in Graphene/Manganese Oxide Hybrid Anode
S. L. Cheekati,Z. Yao,H. Huang
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/819350
Abstract: Graphene nanosheets (GNS) with attached MnOx nanoparticles are studied in regard to their structure and morphology. The relationship between the lithium storage performances and GNS contents as well as manganese valency was investigated. Experimental results showed that the specimen with 44 wt% GNS and high content of MnO delivered high reversible capacity (over twice of that in graphitic carbon anode), good cycling stability (0.8% fading per cycle), and high rate capability (67% at the 800 mA/g), which are dramatically better than pure Mn3O4. The improvement is attributed to the presence of GNS which provides continuous networks for fast electronic conduction and mechanical flexibility for accommodating the large volume change. The MnOx/GNS hybrid material has the added advantages over pure GNS, benefiting from its lithium storage potential of around 0.5 V which not only ensures high rate capability but also reduces the risk of metallic lithium formation with its safety hazard.
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