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21.
This study is designed to assess the application of neural networks in comparison to the Kaplan-Meier and Cox proportional hazards model in the survival analysis. Three hundred thirty gastric cancer patients admitted to and surgically treated were assessed and their post-surgical survival was determined. The observed baseline survival was determined with the three methods of Kaplan-Meier product limit estimator, Cox and the neural network and results were compared. Then the binary independent variables were entered into the model. Data were randomly divided into two groups of 165 each to test the models and assess the reproducibility. The Chi-square test and the multiple logistic model were used to ensure the groups were similar and the data was divided randomly. To compare subgroups, we used the log-rank test. In the next step, the probability of survival in different periods was computed based on the training group data using the Cox proportional hazards and a neural network and estimating Cox coefficient values and neural network weights (with 3 nodes in hidden layer). Results were used for predictions in the test group data and these predictions were compared using the Kaplan-Meier product limit estimator as the gold standard. Friedman and Kruskal-Wallis tests were used for comparisons as well. All statistical analyses were performed using SPSS version 11.5, Matlab version 7.2, Statistica version 6.0 and S_PLUS 2000. The significance level was considered 5% (alpha = 0.05). The three methods used showed no significance difference in base survival probabilities. Overall, there was no significant difference among the survival probabilities or the trend of changes in survival probabilities calculated with the three methods, but the 4 year (48th month) and 4.5 year (54th month) survival rates were significantly different with Cox compared to standard and estimated probabilities in the neural network (p < 0.05). Kaplan-Meier and Cox showed almost similar results for the baseline survival probabilities, but results with the neural network were different: higher probabilities up to the 4th year, then comparable with the other two methods. Estimates from Cox proportional hazards and the neural network with three nodes in hidden layer were compared with the estimate from the Kaplan-Meier estimator as the gold standard. Neither comparison showed statistically significant differences. The standard error ratio of the two estimate groups by Cox and the neural network to Kaplan-Meier were no significant differences, it indicated that the neural network was more accurate. Although we do not suggest neural network methods to estimate the baseline survival probability, it seems these models is more accurately estimated as compared with the Cox proportional hazards, especially with today's advanced computer sciences that allow complex calculations. These methods are preferable because they lack the limitations of conventional models and obviate the need for unnecessary assumptions including those related to the proportionality of hazards and linearity.  相似文献   
22.
The main objective of this study was to evaluate the potential protective effect of red Grape Seed Extract (GSE) on lead induced hypertension (HTN) and Heart Rate (HR) in male Wistar rats. The rats were randomly assigned to one of 4 groups: Each group received lead acetate (100 ppm in drinking water), GSE (100 mg kg(-1), orally) or Lead + GSE for 45 days. Another group assigned as control group provided with tap water and regular pellet food. The Systolic Blood Pressure (SBP) and heart rate were determined by tail plethysmography coupled to a computer system. There was a sustained elevation of SBP in lead exposed rats that significantly increased at day 18 (lead treated, 112.7 +/- 2.7 mmHg, vs. control, 105.6 +/- 2.6 mmHg, n = 10, p < 0.05) and reached a maximum level at day 36 (lead treated, 124.9 +/- 2.3 mmHg, vs. control, 103.6 +/- 3.1 mmHg, n = 10, p < 0.001). However, the other three groups; showed no significant changes in SBP. Furthermore, the heart rate was increased sustainly in lead exposed animals that was statistically significant at days 36 and 45 (lead treated group, 404.5 +/- 9.4 vs. control group, 381.7 +/- 6.7, n = 10, p < 0.05). The blood lead level in both lead and lead + GSE treated groups was increased significantly compared with control and GSE treated groups (p < 0.001). However, GSE administration had no effect on the blood lead level in lead treated group. According to the result of this study, it may be concluded that GSE could have beneficial effect in protecting the cardiovascular system through its antioxidant activity against oxidative stress.  相似文献   
23.
Long-term effects of different levels of dietary vermicompost manure leachate powder (VCL) were investigated on the nauplii growth and survival, biochemical composition, total carotenoids, and reproductive performance of broodstock Artemia franciscana in laboratory cultures. The instar I nauplii were fed in five treatments including 100% of the microalga Dunaliella salina (Alg; control group, with a density of 18?×?106 cells mL?1) and mixtures of 75% Alg-25% VCL, 50% Alg-50% VCL, 25% Alg-75% VCL, and 100% VCL for 3 weeks. At maturity, 35 pairs (males and females) were individually isolated from each treatment and transferred to 50-mL falcon tubes in which the reproduction and longevity of females were monitored until mortality. Results showed that the total length of Artemia in the control, 75 Alg-25 VCL, and 50 Alg-50 VCL treatments was significantly different from the other groups at the end of the 2nd and 3rd weeks. The pre-puberty survival rate was severely affected by the increased dietary levels of VCL declining from 52% (control) to 6.7% (100 VCL). The adults’ body protein levels in the control and 75 Alg-25 VCL (54–57%) were similar, but both groups were significantly different from the other treatments. However, the lipid content (13.7–19.8%) and total carotenoids (36.5–47.7 μg mg?1) were significantly different between treatments. Many broodstocks’ reproductive characteristics were affected by the diet so that the total number of offspring in the control was markedly higher than the other groups. However, the number of offspring per brood revealed no differences between the control and 75 Alg-25 VCL treatment, but both were significantly dissimilar with the other groups. The interval between two successive brood productions detected in 100 VCL was almost double those in the other groups. The lifetimes of Artemia were not significantly different in the treatments received varied algal diets with the lowest lifespan in 100 VCL treatment. By increasing VCL to over 25%, the growth, survival, and particularly females’ reproductive performance decreased significantly so that Artemia had to be fed only up to 25% VCL (with 75% Alg). These findings indicate an inefficiency of VCL powder supply in long-term feeding to A. franciscana. Moreover, the use of only 25% VCL is apparently appropriate in small-scale laboratory cultures.  相似文献   
24.
Chelates are compounds that are applied to improve nutrition, especially the micronutrients status of plant tissues. During past decades, various chelating agents have been synthesized and introduced to agricultural systems. The recent formulas are aminochelates that are synthesized using various amino acids and a single or several nutrient ions aimed at improving fertilizer use efficiency and more adaptation to environment protection. Apart from their primary use as a micronutrient source, aminochelates represent an effective nitrogen (N) fertilizer in plant nutrition that can avoid negative effects from simple N fertilizers, such as urea. In various studies, higher yield and quality as well as higher concentration of nutrient elements have been obtained by application of aminochelates rather than simple chemical fertilizers. These compounds claimed to be more natural and safer forms of chelating agents, with higher use efficiency and without environmental side effects. However, there is lack of sufficient knowledge especially regarding their detailed impacts and their fate within the soil and plant system. This review provides information concerning the role of aminochelates in plant nutrition and to summarize the previous recent studies that have been done using these fertilizers.  相似文献   
25.
Recently, it is hypothesized that there might be an association between immunological disorders and cervical premalignant and malignant abnormalities. Related studies have been generally focused on some particular autoimmune disease, specially the Systemic Lupus Erythematosus (SLE). This study aimed at comparing the rate of Pap smear abnormalities in female patients with autoimmune diseases and normal counterparts. In a case-control setting, 118 female patients with various autoimmune diseases (the case group) and 118 healthy female counterparts (the control group) were recruited in Tabriz Imam Reza Teaching Centre in a 24 months period of time. The two groups were matched for demographics and known risk factors of cervical malignancy. Frequencies of abnormal Pap smear testing were compared between the two groups. The autoimmune disorders were SLE (74 patients), rheumatoid arthritis or RA (32 patients), systcmic sclerosis or SS (7 patients) and ankylosing spondylitis or AS (5 patients) in the case group. Frequency of abnormal Pap smear testing was significantly higher in the case group comparing with that in the controls (7.6% vs. 1.7%; p = 0.03). Frequency of abnormal Pap smear testing was higher in the patients with SLE (8.1%) and RA (9.3%) comparing with that in the controls; However, these differences were marginally nonsignificant (p = 0.06 and p = 0.07, respectively). Frequency of cases with abnormal Pap smear testing was not statistically different between the autoimmune disorders (p = 0.99). Based on these findings and in conclusion, there might be an association between the autoimmune disorders and occurrence of premalignant or malignant lesions in cervix. Further studies with larger samples sizes are recommended.  相似文献   
26.
Iron (Fe) has very low solubility and plant availability in calcareous soils, and this generally results in restricted plant production and low quality. During last decades, various commercial chelated fertilizers have been used in agricultural systems to meet iron requirements of crops. However, despite extensive application of these commercial chelate fertilizers, there is real doubt and high concerns regarding many aspects of their action, dynamics, efficiency, and safety in plant-soil–environment systems. In the present study, growth and quality of green bean plants (Phaseolus vulgaris L.) were evaluated under foliar and soil applications of Fe-glycine chelate (iron glycine aminochelate) and commercial Fe-EDDHA chelate in a lime soil. The results showed that morphophysiological parameters were improved by the application of Fe-glycine and Fe-EDDHA treatments. Foliar application of Fe-glycine has significantly improved leaf area and Soil-Plant Analyses Development (SPAD) values compared to control and Fe-EDDHA treatments. Pod yield, shoot (but not root) dry weight, and iron concentrations in leaves and pods (but not in root) were significantly higher when plants were treated by Fe-glycine rather than Fe-EDDHA in both soil and foliar applications. Vitamin C and protein contents were significantly improved and phenolic compounds were reduced by foliar application of Fe-glycine and soil application of Fe-EDDHA. The results indicate that foliar application of Fe-glycine can significantly increase Fe concentrations and quality of beans under lime soils with restricted iron availability.  相似文献   
27.
Nitrification inhibitory properties of plant substances offer potential benefits for agricultural applications. In this study, hexane-extracted seed oil, and 10, 20, and 30 mg/pot dry powder of seed exocarp and mesocarp from Acrocomia totai were applied in a quick nitrification bioassay for 24 or 50 hr, as well as for 4 weeks laboratory soil incubation, to investigate their effects on nitrification process. Results showed that applied oil concentrations significantly reduced nitrification rates. The extent of inhibition was increased with the oil concentrations from 5 to 25 µl in both experiments. The exocarp and mesocarp powders also inhibited nitrification, but it was not as high as oil-induced inhibition. Analysis of oil fatty acids showed that oil consisted of 71%, 26%, and 3% of saturated, monounsaturated, and polyunsaturated fatty acids, respectively. This suggests that fatty acids or some unknown ingredients in crude oil could be the responsible inhibiting compound.  相似文献   
28.
Leeches have been reported to harbor several important fish pathogens, including spring viremia of carp virus, infectious hematopoietic necrosis virus (IHNV), and viral hemorrhagic septicemia virus (VHSV), and also may contain blood protozoa. In the present study, leeches were collected from water bodies located in Kurdistan province, Iran. The specimens were tested for IHNV, VHSV, and infectious pancreatic necrosis virus (IPNV) using the PCR method. The results showed that two different species of leeches, Hemiclepsis marginata and Hirudo medicinalis, were infected by IPNV among the seven species studied. The infected leeches were found in areas that were polluted with untreated sewage coming from upstream fish farms culturing Rainbow Trout Oncorhynchus mykiss. In addition, the fish at fish farms in the vicinity had been infected with IPNV 9 months previously. Our results showed that the virus causing infectious pancreatic necrosis is present in the leeches H. marginata and H. medicinalis, suggesting that leeches are a potential source of IPNV in fish farms.

Received October 14, 2015; accepted June 1, 2016 Published online September 29, 2016  相似文献   

29.
The effects of 1-methylcyclopropene (1-MCP) on ripening, superficial scald and concentrations of α-farnesene, conjugated trienols (CTols) and antioxidant enzyme activity of ‘KS6’ Asian pear (Pyrus serotina Rehd.) were studied. 1-MCP treated (2 μL L?1) or untreated control fruit were stored at 1 °C and 90–95% RH for up to 120 days. 1-MCP treated fruit were firmer than untreated fruit. Application of 1-MCP delayed skin color change. Scald appeared after shorter storage duration and was reduced, but not entirely controlled, with 1-MCP. Accumulation of α-farnesene and oxidation were slower in skin of 1-MCP treated fruit compared with controls. Catalase and peroxidase activities in untreated fruit either increased while activities decreased in 1-MCP treated fruit. Superoxide dismutase activity remained stable. The treatment of Asian pears with 1-MCP followed by cold storage maintained textural characteristics with less scald incidence.  相似文献   
30.
Determination of the chemical characteristics of soil for balanced fertilization on large scales is an important factor in achieving a precision agriculture. Laboratory analyses of soil properties are usually expensive and time consuming. Surmounting these problems is possible using geostatistics. Therefore, this research aims at selecting a proper interpolation method using 213 soil samples for alfalfa farmland in Hamadan Province, Iran. Various factors such as pH, EC, , , K, P, Fe, Zn, B and Co were measured. Ordinary kriging and co-kriging were assessed to derive maps of soil physico-chemical properties, using mean absolute error (MAE), mean bias error (MBE), root mean squared error (RMSE) and average kriging standard error (AKSE) as statistical criteria. Variography analysis indicated that the ranges of influence for pH, EC, , , K, P, Zn, Fe, B and Co were 65, 55, 78, 79, 75, 60, 50, 65, 70 and 30 km, respectively, and the measuring error varied between 0.366 and 0.843. The results revealed that, based on precision criteria, co-kriging was the best method for interpolating the chemical properties of soil. Finally, using to the co-kriging for each determined variable, a related zoning map for fertility management of the study area was prepared.  相似文献   
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