Efficient Medical Image Segmentation Based on Knowledge Distillation.

Recent advances have been made in applying convolutional neural networks to achieve more precise prediction results for medical image segmentation problems. However, the success of existing methods has highly relied on huge computational complexity and massive storage, which is impractical in the real-world scenario. To deal with this problem, we propose an efficient architecture by distilling knowledge from well-trained medical image segmentation networks to train another lightweight network. This architecture empowers the lightweight network to get a significant improvement on segmentation capability while retaining its runtime efficiency. We further devise a novel distillation module tailored for medical image segmentation to transfer semantic region information from teacher to student network. It forces the student network to mimic the extent of difference of representations calculated from different tissue regions. This module avoids the ambiguous boundary problem encountered when dealing with medical imaging but instead encodes the internal information of each semantic region for transferring. Benefited from our module, the lightweight network could receive an improvement of up to 32.6% in our experiment while maintaining its portability in the inference phase. The entire structure has been verified on two widely accepted public CT datasets LiTS17 and KiTS19. We demonstrate that a lightweight network distilled by our method has non-negligible value in the scenario which requires relatively high operating speed and low storage usage.

Gas/particle partitioning of atmospheric PCDD/Fs in a satellite town in Eastern China.

Gas/particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in ambient air was investigated in a satellite town in Eastern China from April 2007 to January 2008 comprehending large temperature variations (from 3 to 34 degrees C, daily average). Molecular weight, molecular structure and ambient temperatures are the three major factors that govern the gas/particle partitioning of atmospheric PCDD/Fs throughout the year. Generally, good agreements were obtained (except for winter) between measured particulate fractions and theoretical estimates of both the Junge-Pankow adsorption model and Harner Bidleman absorption model using different sets of subcooled liquid vapor pressure (P(L)(o)) and octanol-air partition coefficient (K(oa)), respectively. Models utilizing P(L)(o) estimates, derived from gas chromatographic retention indices (GC-RIs), are more accurate than that of entropy-based. Moreover, during winter, the K(oa)-based model using the GC-RIs approach performs better on lower chlorinated PCDD/Fs than that of P(L)(o)-based. Furthermore, possible sources of mismatch between measured and predicted values in winter (3-7 degrees C) were discussed. Gas adsorption artifact was demonstrated to be of minor importance for the phenomena observed. On the other hand, large deviations of slopes (m(r)) and intercepts (b(r)) in logK(p) vs. logP(L)(o)(Pa)/logK(oa) plots from theoretical values are observed in the literature data and these are found to be linearly correlated with ambient temperatures (P<0.001) in this study. This indicates that the non-equilibrium partitioning of PCDD/Fs in winter may be significantly influenced by the colder temperatures that may have slowed down the exchange between gaseous and particulate fractions.

Concentrations, profiles, and sources of atmospheric PCDD/Fs near a municipal solid waste incinerator in Eastern China.

Ambient air monitoring of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was performed to investigate their concentrations, profiles, and sources near a municipal solid waste incinerator (MSWI) in Eastern China. The PCDD/F concentrations varied over a factor of 51.4 from 0.059 to 3.03 pg I-TEQ m(-3) (or over 41.4 from 3.96 to 164 pg m(-3)) and fell at the higher end of the range in recorded peer investigations around the world. Almost all ambient air samples show a unique TCDF-dominanthomologue pattern, characterized by decreasing concentrations with increasing levels of chlorination (except for OCDD). By contrast, the dominant congener in terms of concentration profiles shows temporal and spatial variations among the OCDD, OCDF, and 1,2,3,4,6,7,8-HpCDF. The results from a congener-specific factor analysis between ambient air and PCDD/F emission sources, as well as U.S. EPA Chemical Mass Balance (CMB8.2) and Industrial Source Complex Short Term Version 3 (ISCST3) modeling, suggest that the deterioration of air quality in the study area is primarily attributed to open burning of wastes (OB), followed by hot water boilers (HWBs), traffic, and the MSWI.

Role of nonsteroidal anti-inflammatory drugs in the prevention of post-ERCP pancreatitis: a meta-analysis.

BACKGROUND: The role of prophylactic nonsteroidal anti-inflammatory drugs (NSAIDs) for reduction of pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP) is debated. We performed a meta-analysis of all published randomized controlled trials to evaluate the efficacy of NSAIDs in the prevention of post-ERCP pancreatitis. DATA SOURCES: Searches were conducted in the databases PubMed, EMBASE and the Cochrane Library. Six randomized clinical trials that fulfilled the inclusion criteria and addressed the clinical questions of this analysis were further assessed. Data were extracted by two independent observers according to predetermined criteria. RESULTS: The risk of pancreatitis was lower in the NSAID group than in the placebo group (OR: 0.46, 95% CI: 0.32 to 0.65, P<0.0001). Two hours after ERCP, prophylactic administration of NSAIDs was associated with a lower serum amylase level (WMD: -91.09, 95% CI: -149.78 to -32.40, P=0.002), but there was no difference in mean 24-hour serum amylase values (WMD: -379.00, 95% CI: -805.75 to 47.76, P=0.08). No deaths or NSAID-related complications were noted. CONCLUSIONS: Prophylactic administration of NSAIDs can reduce the incidence of post-ERCP pancreatitis; this administration in patients undergoing ERCP is recommended. Further randomized controlled trials are required before its introduction into routine care.

Agricultural soil monitoring of PCDD/Fs in the vicinity of a municipal solid waste incinerator in Eastern China: temporal variations and possible sources.

The temporal variations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in 33 agricultural soil samples in the vicinity of a municipal solid waste incinerator (MSWI) in Eastern China were determined one year after the initial investigation in 2006. The soil PCDD/F concentrations in 2007 ranged from 73.6 to 377 ng kg(-1) (0.60-6.38 ng I-TEQ kg(-1)). During 2006-2007, the overall soil PCDD/F levels increased significantly, i.e., 33% and 39% for total concentration and I-TEQ (median value), respectively. Moreover, soils in the study area are proved to be almost free from previously suspected PCDD/F sources, i.e., pentachlorophenol/sodium penta-chlorophenate (PCP/PCP-Na) and 1,3,5-trichloro-2-(4-nitrophenoxy) benzene (CNP) contaminations. Furthermore, the results from a congener-specific factor analysis between soils (collected in two investigations) and dioxin emission sources suggest that diffuse sources including open burning of wastes, traffic and hot water boilers are major contributors that are responsible for the accumulation of PCDD/Fs in soils. By contrast, the impact of the presumably major PCDD/F source identified in our previous study, i.e., the MSWI, seems to be limited.

Epidemiology of fatty liver in an islander population of China: a population-based case-control study.

BACKGROUND: Because of difficulty in evaluating fatty liver disease in islander populations, we conducted a cross-sectional study to investigate the prevalence of fatty liver and its risk factors in an islander population of East China. METHODS: Randomized multistage stratified cluster sampling from the islander population was used in a population-based case-control study. Then interview, physical examination, and ultrasonography were done. RESULTS: Univariate logistic-regression analysis showed that male gender, smoking, daily alcohol intake > or =20 g, duration of drinking > or =5 years, total alcohol intake > or =36.5 kg, hypertension and obesity were closely related to fatty liver (all P<0.05). Multivariate stepwise logistic-regression analysis showed duration of drinking > or =5 years and obesity were closely related to fatty liver (both P<0.05), the odds-ratio (OR) (95% CI) was 1.954 (1.364-2.799) and 7.014 (4.919-10.002), respectively. The prevalence of fatty liver in this district was 40.0%. The prevalence of fatty liver in the non-obese and <5 years drinking group, the non-obese and > or =5 years drinking group, the obese and <5 years drinking group and the obese and > or =5 years drinking group were 15.43%, 26.73%, 56.78% and 71.52%, respectively. A dose-response relation between the duration of drinking and fatty liver was not apparent. After stratification by obesity, we found that the severity of fatty liver on ultrasonography was positively correlated with the duration of drinking level in the obese and non-obese groups, Pearson's correlation coefficients were 0.293 in the obese group and 0.178 in the non-obese group (both P<0.05). CONCLUSIONS: The duration of drinking > or =5 years and obesity were two important risk factors for fatty liver in the islander population of East China. The prevalence of fatty liver in this population was high. An alcoholic threshold effect may be more important than a dose-response effect on the morbidity of fatty liver.

Source identification of PCDD/Fs in agricultural soils near to a Chinese MSWI plant through isomer-specific data analysis.

Isomer-specific data were investigated in order to identify the sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in agricultural soils, including Fluvo-aquic and paddy soils, in the vicinity of a Chinese municipal solid waste incineration (MSWI) plant. Homologue and isomer profiles of PCDD/Fs in soils were compared with those of potential sources, including combustion sources, i.e., MSWI flue gas and fly ash; and the impurities in agrochemicals, such as the pentachlorophenol (PCP), sodium pentachlorophenate (PCP-Na) and 1,3,5-trichloro-2-(4-nitrophenoxy) benzene (CNP). The results showed that the PCDD/F isomer profiles of combustion sources and agricultural soils were very similar, especially for PCDFs, although their homologue profiles varied, indicating that all the isomers within each homologue behave identically in the air and soil. Moreover, factor analysis of the isomer compositions among 33 soil samples revealed that the contamination of PCDD/Fs in agricultural soils near the MSWI plant were primarily influenced by the combustion sources, followed by the PCP/PCP-Na and CNP sources. This implication is consistent with our previous findings based on chemometric analysis of homologue profiles of soil and flue gas samples, and identifies PCP/PCP-Na as an additional important source of PCDD/Fs in the local area. This makes the similarities and differences of isomer profiles between Fluvo-aquic and paddy soils more explainable. It is, therefore, advisable to use isomer-specific data for PCDD/F source identifications where possible.

Effects of inorganic chlorine source on dioxin formation using fly ash from a fluidized bed incinerator.

Chlorine source is indispensable for polychlorinated dibenzo-p-dioxin and furan (PCDD/F) formation during municipal solid waste (MSW) incineration. Inorganic chlorine compounds were employed in this study to investigate their effects on PCDD/F formation through heterogeneous synthesis on fly ash surfaces. A fly ash sample obtained from a fluidized bed incinerator was sieved to different size fractions which served as the PCDD/F formation sources. The capability of different metal chlorides which facilitate the formation of PCDDs/Fs was found to follow the trends: Na < Mg < K < Al < Ca, when two particle fractions of >177 miocrom and 104-125 microm were used in the experiments. However, the capability of NaCl, MgCl2 and KCl did not seem much different from each other, whereas CaCl2 and AlCl3 were much more active in PCDD/F formation. NaCl and MgCl2 were relatively effective to produce more PCDDs, while KCl, AlCl3 and CaCl2 generated more PCDFs during heterogeneous reactions occurring on fly ash. 2,3,7,8-TCDF was the most significant contributor to the toxicity of the PCDDs/Fs formed from inorganic chlorine sources. Decreasing the sizes of fly ash particles led to more active formation of PCDDs/Fs when NaCl was used as inorganic chlorine in the experiment. The highest PCDDs/Fs produced from particles with size <37 microm, while the lowest PCDDs/Fs produced from particles with size >177 microm. The toxicity generally increased with decreasing size of the fly ash particles. The formation of PCDDs was mainly facilitated by the two size fractions, 104-125 microm and <37 microm, while the formation of PCDFs was favored by the two other size fractions, >177 microm and 53-104 microm.

Hepatic veno-occlusive disease induced by Gymura segetum: report of two cases.

BACKGROUND: Hepatic veno-occlusive disease (VOD) or sinusoidal obstruction syndrome is associated with a high mortality because of its severity. Gymura segetum, a Chinese herbal medicine, is always used to cure injury and bleeding in rural areas in China. This study was undertaken to better understand VOD and its relations to the effect of Gymura segetum. METHODS: Between 2000 and 2002, two patients were admitted to our department because of VOD. Before admission, both of them had been injured and taken oral decoction of patent drug Gymura segetum. We analyzed the clinical manifestations, diagnosis and therapy of the two patients. RESULTS: Pyrrolizidine in Panax notginseng was proved to induce VOD. The diagnosis of VOD depended on hepatic biopsy. CONCLUSION: Gymura segetum can induce VOD. More attention should be paid to its unsuscepted side effects.