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Search Results: 1 - 10 of 244455 matches for " L Yan "
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Scatter and Blurring Compensation in Inhomogeneous Media Using a Postprocessing Method
Yan Yan,Gengsheng L. Zeng
International Journal of Biomedical Imaging , 2008, DOI: 10.1155/2008/806705
Abstract: An efficient postprocessing method to compensate for the scattering and blurring effects in inhomogeneous medium in SPECT is proposed. A two-dimensional point spread function (2D-PSF) was estimated in the image domain to model the combination of these two physical effects. This 2D-PSF in the inhomogeneous medium is fitted with an asymmetric Gaussian function based on Monte Carlo simulation results. An efficient further blurring and deconvolution method was used to restore images from the spatially variant 2D-PSF kernel. The compensation is performed using a computer-simulated NCAT phantom and a flanged Jaszczak experimental phantom. The preliminary results demonstrate an improvement in image quality and quantity accuracy with increased image contrast (25% increase compared to uncompensated image) and decreased error (40% decrease compared to uncompensated image). This method also offers an alternative to compensate for scatter and blurring in a more time efficient manner compared to the popular iterative methods. The execution time for this efficient postprocessing method is only a few minutes, which is within the clinically acceptable range.
Distribution of displacement in backward spinning of tube
Kezhi Li,Yan Lü
Chinese Science Bulletin , 1997, DOI: 10.1007/BF02882559
HST/WFPC2 Morphologies of K-selected Extremely Red Galaxies
L. Yan,D. Thompson
Physics , 2002, DOI: 10.1086/367686
Abstract: We selected 115 extremely red objects (EROs) from deep HST WFPC2 archive data combined with ground-based K-band images, with (F814W - Ks) >= 4mag, K-band SNR >= 5, and a median limiting Ks magnitude of 18.7mag, over a corresponding area of 228 sq. arcminutes, for a morphological study of the ERO galaxy population. The survey covered a total of 409 sq. arcminutes over 77 separate WFPC2 fields. This is the first complete sample of bright EROs with high resolution HST morphologies. From a visual morphological classification, we find that 30+/-5% of our EROs have morphologies consistent with a pure bulge or bulge-dominated galaxy (equivalent to E/S0), while disks comprise 64+/-$7% of the sample. Only 6% of the EROs remained unclassifiable. Mergers or strongly interacting systems, which includes sources from both classes, make up 17+/-4% of the full sample. The quantitative MDS profile fitting is consistent with these results. These results highlight the complex nature of optical/near-IR color selected EROs. The dominant component of our sample is comprised of disks, not spheroids or strongly interacting systems like HR10. Using Bruzual & Charlot SED models, we investigated population differences in EROs selected by their (I-K) vs. (R-K) colors and found that I-band based surveys preferentially select systems with prolonged star formation. Real differences in the surface densities of EROs in R-band and I-band based surveys may reflect this color selection effect, complicating the comparisons between and interpretations on the nature of the ERO population.
Distribution of displacement in backward spinning of tube

Kezhi Li,Yan Lü,

科学通报(英文版) , 1997,
Cancer Therapy Targeting the HER2-PI3K Pathway: Potential Impact on the Heart
Giannoula L. Klement,Xinhua Yan
Frontiers in Pharmacology , 2012, DOI: 10.3389/fphar.2012.00113
Abstract: The HER2-PI3K pathway is the one of the most mutated pathways in cancer. Several drugs targeting the major kinases of this pathway have been approved by the Food and Drug Administration and many are being tested in clinical trials for the treatment of various cancers. However, the HER2-PI3K pathway is also pivotal for maintaining the physiological function of the heart, especially in the presence of cardiac stress. Clinical studies have shown that in patients treated with doxorubicin concurrently with Trastuzumab, a monoclonal antibody that blocks the HER2 receptor, the New York Heart Association class III/IV heart failure was significantly increased compared to those who were treated with doxorubicin alone (16 vs. 3%). Studies in transgenic mice have also shown that other key kinases of this pathway, such as PI3Kα, PDK1, Akt, and mTOR, are important for protecting the heart from ischemia-reperfusion and aortic stenosis induced cardiac dysfunction. Studies, however, have also shown that inhibition of PI3Kγ improve cardiac function of a failing heart. In addition, results from transgenic mouse models are not always consistent with the outcome of the pharmacological inhibition of this pathway. Here, we will review these findings and discuss how we can address the cardiac side-effects caused by inhibition of this important pathway in both cancer and cardiac biology.
Surface Rupture and Hazard of Wenchuan Ms 8.0 Earthquake, Sichuan, China  [PDF]
Yong Li, Runqiu Huang, Liang Yan, Alexander L. Densmore, Rongjun Zhou
International Journal of Geosciences (IJG) , 2010, DOI: 10.4236/ijg.2010.11003
Abstract: Longmen Shan is located the special joint between the Qinghai-Tibetan Plateau in the west and the Yangtze craton in the east. Consisting of a series of parallel imbricated thrust, it develops, from the west to the east, the Maoxian-Wenchuan, Yingxiu-Beichuan and Pengxian-Guanxian faults. Wenchuan Ms 8.0 earthquake is a thrust with strike-slip type, and surface ruptures are located in Yingxiu-Beichuan fault zone and Peng- xian-Guanxian fault zone. Based on the geological background, tectonic setting, the active tectonics of Long- men Shan and surface ruptures of the Wenchuan earthquake, a dynamical model to illustrate possible links between surface processes and upward extrusion of lower crustal flow channel at the eastern margin of the Tibetan plateau have been studied, and the results is the material in lower crust in the Longmen Shan moving as nearly-vertical extrusion and uplift, resulting in the surface rate of tectonic movement differing according to depth rate as well as the occurrence of large shallow Wenchuan earthquake.
Visualization of Allostery in P-Selectin Lectin Domain Using MD Simulations
Shouqin Lü,Yan Zhang,Mian Long
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015417
Abstract: Allostery of P-selectin lectin (Lec) domain followed by an epithelial growth factor (EGF)-like domain is essential for its biological functionality, but the underlying pathways have not been well understood. Here the molecular dynamics simulations were performed on the crystallized structures to visualize the dynamic conformational change for state 1 (S1) or state 2 (S2) Lec domain with respective bent (B) or extended (E) EGF orientation. Simulations illustrated that both S1 and S2 conformations were unable to switch from one to another directly. Instead, a novel S1' conformation was observed from S1 when crystallized B-S1 or reconstructed “E-S1” structure was employed, which was superposed well with that of equilibrated S1 Lec domain alone. It was also indicated that the corresponding allosteric pathway from S1 to S1' conformation started with the separation between residues Q30 and K67 and terminated with the release of residue N87 from residue C109. These results provided an insight into understanding the structural transition and the structure-function relationship of P-selectin allostery.
Is It Suitable to Diagnose Acute Rheumatic Fever with Anti-Streptolysin O?
?. Emre ?a?lyan,Onur Akp?nar
Ko?uyolu Kalp Dergisi , 2011,
Abstract: In clinical practice, Anti-streptolizin O (ASO) levels are used for diagnosis of Acute Rheumatic Fever (ARF). We investigated to evaluate the accuracy of using ASO in patients with a murmur in physical examination, in patients with a suspicious ARF history and sometimes only in routine examination. When we evaluate 52 patients' data, high ASO levels was not associated with nor valve structures, neither ARF history. Therefore, we showed that using ASO of levels only is an incorrect application for diagnosis of ARF in clinical practice.
Temporal and spatial distribution of the meiobenthic community in Daya Bay, South China Sea
L. Tang,H. X. Li,Y. Yan
Ocean Science Discussions (OSD) , 2012, DOI: 10.5194/osd-9-1853-2012
Abstract: Spatial and temporal biodiversity patterns of the meiobenthos were studied for the first time in Daya Bay, which is a tropical semi-enclosed basin located in the South China Sea. The abundance, biomass, and composition of the meiobenthos and the basic environmental factors in the bay were investigated. The following 19 taxonomic groups were represented in the meiofauna: Nematoda, Copepoda, Polychaeta, Oligochaeta, Kinorhyncha, Gastrotricha, Ostracoda, Bivalvia, Turbellaria, Nemertinea, Sipuncula, Hydroida, Amphipoda, Cumacea, Halacaroidea, Priapulida, Echinodermata, Tanaidacea, and Rotifera. Total abundance and biomass of the meiobenthos showed great spatial and temporal variation, with mean values of 993.57 ± 455.36 ind cm 2 and 690.51 ± 210.64 μg 10 cm 2, respectively. Nematodes constituted 95.60 % of the total abundance and thus had the greatest effect on meiofauna quantity and distribution, followed by copepods (1.55 %) and polychaetes (1.39 %). Meiobenthos abundance was significantly negatively correlated with water depth at stations (r= 0.747, P<0.05) and significantly negatively correlated with silt-clay content (r= 0.516, P<0.01) and medium diameter (r= 0.499, P<0.01) of the sediment. Similar results were found for correlations of biomass and abundance of nematodes with environmental parameters. Polychaete abundance was positively correlated with the bottom water temperature (r=0.456, P<0.01). Meiobenthos abundance differed significantly among seasons (P<0.05), although no significant difference among stations and the interaction of station × season was detected by two-way ANOVA. In terms of vertical distribution, most of the meiobenthos was found in the surface layer of sediment. This pattern was apparent for nematodes and copepods, but a vertical distribution pattern for polychaetes was not as obvious. Based on the biotic indices and analyses of their correlations and variance, the diversity of this community was likely to be influenced by environmental variations.
Assessment of Acid Deposition Effects on Water Quality of the Upper Rio Grande River Section in Texas  [PDF]
Qin Qian, Badri Parajuli, Qi Fu, Kaiming Yan, John L. Gossage, Thomas Ho
Journal of Water Resource and Protection (JWARP) , 2013, DOI: 10.4236/jwarp.2013.58080

Airborne pollutants such as SO42- and NO3- that cause acid rain may pollute water resources via acid deposition. However, such effects on the water quality of the upper Rio Grande River section in Texas have not been systematically studied. The objective of this study is to collect and analyze field data, and perform hydrological and water chemistry analyses to assess acid deposition effects on the river water quality. The analysis of the precipitation data indicates that the concentrations of ions decrease as the quantity of precipitation increases. The precipitation with higher concentrations of SO42- and NO3- has a lower pH while that with higher concentrations of Ca2+ and Na+ has a relatively higher pH value. The analysis of river data demonstrates that the pH value, Dissolved Oxygen (DO), and Total Dissolved Solid (TDS) generally decrease when the flow rate increases

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