PubMed Health⌕ Search

Biomedical subjects

Min Shao

Publications and source records attributed to Min Shao.

13 recordsLinked to original sources
PubMed2006

Improved optimization of soft-partition-weighted-sum filters and their application to image restoration.

Soft-partition-weighted-sum (Soft-PWS) filters are a class of spatially adaptive moving-window filters for signal and image restoration. Their performance is shown to be promising. However, optimization of the Soft-PWS filters has received only limited attention. Earlier work focused on a stochastic-gradient method that is computationally prohibitive in many applications. We describe a novel radial basis function interpretation of the Soft-PWS filters and present an efficient optimization procedure. We apply the filters to the problem of noise reduction. The experimental results show that the Soft-PWS filter outperforms the standard partition-weighted-sum filter and the Wiener filter.

Algorithms↗
PubMed2006

Optimization of partition-based Weighted Sum filters and their application to image denoising.

Partition-based Weighted Sum (P-WS) filtering is an effective method for processing nonstationary signals, especially those with regularly occurring structures, such as images. P-WS filters were originally formulated as Hard-partition Weighted Sum (HP-WS) filters and were successfully applied to image denoising. This formulation relied on intuitive arguments to generate the filter class. Here we present a statistical analysis that justifies the use of weighted sum filters after observation space partitioning. Unfortunately, the HP-WS filters are nondifferentiable and an analytical solution for their global optimization is therefore difficult to obtain. A two-stage suboptimal training procedure has been reported in the literature, but prior to this research no evaluation on the optimality of this approach has been reported. Here, a Genetic Algorithm (GA) HP-WS optimization procedure is developed that, in simulations, shows that the simpler two-stage training procedure yields near optimal results. Also developed in this paper are Soft-partition Weighted Sum (SP-WS) filters. The SP-WS filters utilize soft, or fuzzy, partitions that yield a differentiable filtering operation, enabling the development of gradient-based optimization procedures. Image denoising simulation results are presented comparing HP-WS and SP-WS filters, their optimization procedures, and wavelet-based image denoising. These results show that P-WS filters, in general, outperform traditional and wavelet-based image filters, and SP-WS filters utilizing soft partitioning not only allow for simple optimization, but also yields improved performance.

Algorithms↗
PubMed2006

[Individualized and comprehensive therapy for severe acute pancreatitis in early stage: analysis of 110 cases].

OBJECTIVE: To investigate the risk factors of exacerbation of severe acute pancreatitis (SAP) in early stage, in order to formulate therapeutic strategies including minimally invasive intervention and organ support, and to finalize an individualized and comprehensive therapy for the SAP in early stage to decrease the mortality. METHODS: Fifty-three patients with SAP admitted from 1995 to 1999 was categorized as group 1, and 57 patients admitted from 2000 to 2005 as group 2, were analyzed retrospectively. Ranson's score, acute physiological and chronic health evaluation II (APACHE II) score, Balthazar CT grade, presence or absence of biliary tract obstruction, hypoxia, lung infection, shock, abdomen compartment syndrome (ACS), hyperlipemia, pleural effusion were analysed logistically. Mortality following different treatments and incidence rate of complications were also evaluated. RESULTS: In the two groups, 13 patients of the group 1 and 14 of group 2 were complicated with multiple organ dysfunction syndrome (MODS) in the early stage. There was difference in Ranson's score, APACHE II, Balthazar CT grade, between the groups with and without MODS (all P<0.05). Higher incidences of shock, biliary tract obstruction, ACS, hyperlipemia, pleural effusion were seen in group with MODS (P<0.01). Mortality of group 2 patients was lowered after receiving a comprehensive therapy including bedside hemodialysis (CBP) and artificial liver support (P<0.01). CONCLUSION: Development of MODS in SAP and its mortality are related to strategies of treatment, and adoption of an individualized and comprehensive therapy for the SAP in early stage can decrease the complications and the mortality.

Acute Disease↗
PubMed2005

Online volatile organic compound measurements using a newly developed proton-transfer ion-trap mass spectrometry instrument during New England Air Quality Study--Intercontinental Transport and Chemical Transformation 2004: performance, intercomparison, and compound identification.

We have used a newly developed proton-transfer ion-trap mass spectrometry (PIT-MS) instrument for online trace gas analysis of volatile organic compounds (VOCs) during the 2004 New England Air Quality Study-Intercontinental Transport and Chemical Transformation study. The PIT-MS instrument uses proton-transfer reactions with H3O+ ions to ionize VOCs, similarto a PTR-MS (proton-transfer reaction mass spectrometry) instrument but uses an ion trap mass spectrometer to analyze the product ions. The advantages of an ion trap are the improved identification of VOCs and a near 100% duty cycle. During the experiment, the PIT-MS instrument had a detection limit between 0.05 and 0.3 pbbv (S/N = 3 (signal-to-noise ratio)) for 2-min integration time for most tested VOCs. PIT-MS was used for ambient air measurements onboard a research ship and agreed well with a gas chromatography mass spectrometer). The comparison included oxygenated VOCs, aromatic compounds, and others such as isoprene, monoterpenes, acetonitrile, and dimethyl sulfide. Automated collision-induced dissociation measurements were used to determine the contributions of acetone and propanal to the measured signal at 59 amu; both species are detected at this mass and are thus indistinguishable in conventional PTR-MS.

Air Movements↗
PubMed2005

Distributions and source apportionment of ambient volatile organic compounds in Beijing city, China.

Ambient measurements of 108 volatile organic compounds (VOCs), including alkanes, alkenes, aromatics, and halogenated hydrocarbons, were conducted from 2002 to 2003 at six sites in Beijing city. The mean mass concentration of total VOCs was 132.6 +/- 52.2 microg/m3, with alkanes, aromatics, and alkenes accounting for 35%, 22%, and 17%, respectively. The concentrations of most VOC species showed a seasonal pattern, with higher values in November, mildly lower in March, and much lower in July. In winter and spring, apparent diurnal variations of reactive compounds such as 1,3-butadiene and isoprene were observed, whereas those were not distinct in summer. The propylene equivalent concentration was used to evaluate the contribution of individual VOCs in ozone formation. Reactive olefins from anthropogenic emissions dominated the reactions with OH at each season. In summer, isoprene became the largest contributor, followed by 1-butene and propene. The source profiles in Beijing, including vehicle exhaust, gasoline vapor, painting operations, and asphalt pavement, were investigated. Based on the measurement of source profiles and ambient concentrations of VOCs in Beijing, chemical mass balance receptor model was applied to estimate contributions of several potential VOCs sources in Beijing. The results indicated that vehicle exhaust contributed on average 57.7%, followed by painting operations, gasoline vapor, and liquefied petroleum gas (LPG) at 12.4%, 11.3%, and 5.8%, respectively.

Air Pollutants↗
PubMed2005

Biological activities of purified harpin(Xoo) and harpin(Xoo) detection in transgenic plants using its polyclonal antibody.

Many harpins have been found in plant pathogen bacteria that can elicit disease and insect resistance in plants, and promote plant growth. In this work, we overexpressed and purified Xanthomonas oryzae pv. oryzae harpin, harpin(Xoo), in Escherichia coli BL21/pGEX-hpa1. Harpin(Xoo) was fused to the C-terminus of glutathione S-transferase (GST) and purified using the Bulk GST purification module and thrombin cleavage capture kit. Purified harpin(Xoo) protein was sensitive to protease K and stable to heat treatment, and could not induce a hypersensitive response after treatment with various plant metabolic inhibitors; these characteristics were similar to harpin(Ea) of Erwinia amylovora. The purified harpin(Xoo) showed a similar ability to induce tobacco mosaic virus resistance in tobacco as harpin(Ea). Its antibody worked well in detecting the purified harpin(Xoo), harpin(Xoo) in the total protein of E. coli BL21/pGEX-hpa1 and an hpa1 transgenic rice.

Bacterial Outer Membrane Proteins↗
PubMed2004

An interference cancellation algorithm for noninvasive extraction of transabdominal fetal electroencephalogram (TaFEEG).

The electroencephalogram is a noninvasive method of demonstrating cerebral function. The fetal electroencephalogram (FEEG) contains important information regarding the status of a fetus. It is believed that disorganization of normal FEEG development may help detect the onset of cerebral palsy and mental retardation syndromes. Unfortunately, noninvasive methods of monitoring FEEG are not currently available. Noninvasively obtained abdominal surface electrical recordings include FEEG components, but are dominated by large interfering components, and, thus, have very low signal to noise ratio. In this paper, we propose a multistep extraction procedure to separate the four main components in transabdominal recordings: 1) maternal ECG; 2) FECG; and 3) FEEG signals as well as 4) interfering baseline wander. The algorithm is tested on simulated and real transabdominal recordings. This study shows that the proposed method successfully extracts the desired FEEG signal.

Abdomen↗
PubMed2004

Genetic diversity of harpins from Xanthomonas oryzae and their activity to induce hypersensitive response and disease resistance in tobacco.

Three hrfA (hypersensitive response-functioning faction A) homologues (hrfl, hrf2 and hrf3) are cloned from 12 strains of Xanthomonas oryzae using PCR based techniques. Hrf1, hrf2 and hrf3 are derived from strains belonging to X. o. pv. oryzae, X. o. pv. oryzicola and X. o. pv. oryzae respectively. Sequence analysis shows that all three genes encode glycine-rich proteins with various numbers of GGG-GG motifs. They all share a conserved cysteine residue at position 45 or 47. Hrf1 and hrf3 encode Harpin(xoo) while hrf2 encodes Harpin(xooc) Hrf1 and hrf3 encodes two different types of Harpin(xoo) proteins. Hrf1 from X. o. pv. oryzae strains (JxoIII, JxoIV, Jxov, Pxo61, Pxo76, Pxo79, Pxo99, Pxo99 and Pxo124) encodes a 15.6 kD Harpin(xoo) with 3 GGG-GG motifs while Hrf3 from strain Pxo86 and Pxo112 encodes a 15.9 kD Harpin(xoo) with 4 GGG-GG motifs. Harpin(xooc) encoded by hrf2 from X. o. pv. oryzicola (strain RS105) has the molecular weight of 15.3 kD and contains 2 GGG-GG motifs. Cluster analysis is performed using deduced sequences of hrf1, hrf2 and hrf3 as well as previously reported Hpa1 and Xopl protein sequence. The results indicated that Harpin(xoo) and Harpin(xooc) belong to two closely related subgroups. Hrf, hrf2 and hrf3 are expressed in E. coli strain BL21 successfully. Under the same condition, hrf1, hrf2 and hrf3 are expressed at the level of 0.389, 0.530 and 0.083 mg/mL respectively. All expressed hrf1, hrf2 and hrf3 proteins (Harpins) are shown to be able to induce hypersensitive reaction and TMV resistance on tobacco. Among the three proteins, Hrf2 has the highest activity while Hrf3 has the lowest activity.

Amino Acid Motifs↗
PubMed2004

[Vegetation diversity of wild Chinese alligator (Alligator sinensis) habitats].

In June and July of 2003, a field survey on the vegetation of 22 Chinese alligator habitats distributed in Nanling county, Jingxian county, Guangde county, Langxi county and Xuancheng city of Anhui province was conducted, and the plant species of the habitats were recorded and analyzed. The results showed that the vegetation of the whole habitats was secondary, and there were 294 species vascular plants, belonging to 92 families. Pteioblastus amarus shrubbery could be found in all sites, and part differences of the vegetation consisted in different habitats. The relationship between Chinese alligator and habitat vegetation was also analyzed. All of these could offer some basic botanical data for the further protection of the Chinese alligator.

Alligators and Crocodiles↗
PubMed2004

Interannual variability of carbon cycle implied by a 2-d atmospheric transport model.

A 2-dimensional atmospheric transport model is deployed in a simplified CO2 inverse study. Calculated carbon flux distribution for the interval from 1981 to 1997 confirms the existence of a terrestrial carbon sink in mid-high latitude area of North Hemisphere. Strong interannual variability exists in carbon flux patterns, implying a possible link with ENSO and other natural episodes such as Pinatubo volcano eruption in 1991. Mechanism of this possible link was investigated with statistic method. Correlation analysis indicated that in North Hemisphere, climatic factors such as temperature and precipitation, to some extend, could influence the carbon cycle process of land and ocean, thus cause considerable change in carbon flux distribution. In addition, correlation study also demonstrated the possible, important role of Asian terrestrial ecosystems in carbon cycle.

Atmosphere↗
PubMed2004

Chemical composition and quantitative relationship between meteorological condition and fine particles in Beijing.

The recent year's monitor results of Beijing indicated that the pollution level of fine particles PM2.5 showed an increasing trend. To understand pollution characteristics of PM2.5 and its relationship with the meteorological conditions in Beijing, a one-year monitoring of PM2.5 mass concentration and correspondent meteorological parameters was performed in Beijing in 2001. The PM2.5 levels in Beijing were very high, the annual average PM2.5 concentration in 2001 was 7 times of the National Ambient Air Quality Standards proposed by US EPA. The major chemical compositions were organics, sulfate, crustals and nitrate. It was found that the mass concentrations of PM2.5 were influenced by meteorological conditions. The correlation between the mass concentrations of PM2.5 and the relative humidity was found. And the correlation became closer at higher relative humidity. And the mass concentrations of PM2.5 were negtive-correlated to wind speeds, but the correlation between the mass concentration of PM2.5 and wind speed was not good at stronger wind.

Air Pollutants↗
PubMed2002

[A backward trajectory inversion model for methane emission over Beijing area].

A Backward trajectory inversion model was established for estimating methane emission over Beijing area, with in situ data of methane measurement. The model was systematically tested for its ability on reflecting diffusion processes in atmospheric boundary layers. In specific condition, the model acted excellently on calculating emission strength and distribution over an area of 100 km scale. By applying to Beijing area with 9 days real methane data and practice meteorological data, the model showed source patches in this area with emission rate 0.0066-0.026 mg/(m2.s), which was correspond well to rice fields emission, the major methane source, in this region. Model results of source patches also showed certain spatial correlation with rice fields distribution.

China↗