This paper proposes a more inclusive statistical model for predicting image noise in Computed Tomography (CT), associated with scanning factors, considering the effect of beam hardening and image processing filters. I...This paper proposes a more inclusive statistical model for predicting image noise in Computed Tomography (CT), associated with scanning factors, considering the effect of beam hardening and image processing filters. It is based on power functions where the levels of the parameters will determine the rate of noise variation with respect to a given scanning factor. It includes the influence of tube potential, tube current, slice thickness, Field of View (FOV), reconstruction methods and post-processing filters. To validate the model, tomographic measurements were made by using a PMMA phantom that simulates paediatric head and adult abdomen, a PET bottle was used to simulate the head of the new-born. The influence of ROI (Region Of Interest) size over nonlinear model parameters was analysed, and high variations of powers of attenuation and FOV were found depending on ROI size. A nonlinear robust regression method was used. The validation was performed graphically by weighted residual analysis. A nonlinear noise model was obtained with an adjusted coefficient of determination for ROI sizes between 10% and 70% of the phantom diameter or FOV. The model confirms the significance of the tube current, slice thickness and beam hardening effect on image. The process of estimation of the parameters of the model by Nonlinear Robust Regression turned out to be optimal.展开更多
Axillary buds, collected from greenhouse-grown plants of Bambusa vulgaris Schrad. ex Wendl (B. vulgaris), were incubated on a static liquid culture medium, Murashige and Skoog (MS) medium with 2% (w/v) sucrose, and su...Axillary buds, collected from greenhouse-grown plants of Bambusa vulgaris Schrad. ex Wendl (B. vulgaris), were incubated on a static liquid culture medium, Murashige and Skoog (MS) medium with 2% (w/v) sucrose, and supplemented with 12.0 μM 6-benzyladenine (BA). They were transferred to a temporary immersion system (TIS) using liquid MS medium supplemented with 0 (CK-free medium), 6.0, 12.0, 18.0 μM BA. The morphological and anatomical indicators were measured. The BA influenced in vitro multiplication of B. vulgaris. The best results were achieved in the SIT with a concentration of 6.0 μM of BA, which increased the number of shoots (5.1 shoots/explant) in the absence of hyperhydric shoots. Results demonstrated that the water content in the sprouts increased with 12.0 and 18.0 μM BA every four hours. Furthermore, these high levels of BA contributed to a lower accumulation of phenolic compounds and lignin content. The total chlorophyll significantly increased when using 6.0 uM BA, but decreased both parameters with other treatments. These results favor to increase the number of shoots/explants during in vitro multiplication. They will also optimize the in vitro culture conditions, leading to an improvement of in vitro propagation methods for this species.展开更多
Boolean homomorphisms of a hypercube, which correspond to the morphisms in the category of finite Boolean algebras, coincide with the linear isometries of the category of finite binary metric vector spaces.
The objective of this work was to study the effect of the heat treatment and further operation aging on the stereological parameters(size,quantity and volume fraction)of precipitates within ferrite grains of a creep-r...The objective of this work was to study the effect of the heat treatment and further operation aging on the stereological parameters(size,quantity and volume fraction)of precipitates within ferrite grains of a creep-resistant 1.25Cr0.5Mo steel after long-term operation.The heat treatment was similar to the treatment that is carried out in industrial steam pipelines after welding(post weld heat treatment-PWHT)during installation and/or repairing.The operation aging corresponds to a subsequent long in-service operation after repairing.To determine the stereological parameters,SEM digital images were taken from samples of this material after conditions of in-service-aged(after long-term operation),in-service-aged and heat-treated(simulating repairing)and in-service-aged,heat-treated and in-laboratory aged(simulating subsequent long-term operation after repairing).The results indicate that the changes in the stereological parameters of the precipitates within ferrite grains after PWHT is associated with the coarsening process of the within-ferrite-grain precipitates as well as stabilizing the microstructure,since the material aging after PWHT of an in-serviced aged material would not change the stereological parameters.展开更多
Background:Diabetes mellitus is a chronic metabolic disease that is a risk factor for epidemic pathologies.Under hyperglycemic conditions,the enzyme aldose reductase catalyzes the formation of sorbitol in the metaboli...Background:Diabetes mellitus is a chronic metabolic disease that is a risk factor for epidemic pathologies.Under hyperglycemic conditions,the enzyme aldose reductase catalyzes the formation of sorbitol in the metabolism of glucose via polyols,leading to the development of diabetic complications.Therefore,inhibitors of this enzyme are therapeutic targets for the prophylaxis and treatment of these conditions.Methods:In this study,a generalized linear regression model was developed to analyze flavonoids-obtained from a database-that have been tested as inhibitors of aldose reductase.In this sense,the molecular descriptors implemented in DRAGON and MATLAB software were used to determine the correlation between the chemical structure of the inhibitors and their pharmacological activity.The model was validated according to the Organisation for Economic Co-operation and Development Standards and subsequently used for the virtual screening of the flavonoids identified in Jatropha gossypiifolia L.Results:The proposed model showed a good fit for its statistical parameters(R2=0.95).In addition,it showed good predictive power(R2 ext=0.94)and robustness(Q2 LOO=0.92).The experimental chemical space wherein the predictions were reliable(domain of application)was also defined.Finally,the model was used to identify 10 flavonoids from Jatropha gossypiifolia L.as candidates for natural drugs.Compounds with a low probability of oral absorption were identified,among which the elagic acid biflavonoid showed the greatest promise(pIC50 predicted=9.75).Conclusion:The Jatropha gossypiifolia L.species harbors flavonoids with high potential as inhibitors of the aldose reductase enzyme,in which the biflavonoid ellagic acid was shown to be the most promising inhibitor of the aldose reductase enzyme,suggesting its possible use in the treatment of the late complications of diabetes mellitus.展开更多
文摘This paper proposes a more inclusive statistical model for predicting image noise in Computed Tomography (CT), associated with scanning factors, considering the effect of beam hardening and image processing filters. It is based on power functions where the levels of the parameters will determine the rate of noise variation with respect to a given scanning factor. It includes the influence of tube potential, tube current, slice thickness, Field of View (FOV), reconstruction methods and post-processing filters. To validate the model, tomographic measurements were made by using a PMMA phantom that simulates paediatric head and adult abdomen, a PET bottle was used to simulate the head of the new-born. The influence of ROI (Region Of Interest) size over nonlinear model parameters was analysed, and high variations of powers of attenuation and FOV were found depending on ROI size. A nonlinear robust regression method was used. The validation was performed graphically by weighted residual analysis. A nonlinear noise model was obtained with an adjusted coefficient of determination for ROI sizes between 10% and 70% of the phantom diameter or FOV. The model confirms the significance of the tube current, slice thickness and beam hardening effect on image. The process of estimation of the parameters of the model by Nonlinear Robust Regression turned out to be optimal.
文摘Axillary buds, collected from greenhouse-grown plants of Bambusa vulgaris Schrad. ex Wendl (B. vulgaris), were incubated on a static liquid culture medium, Murashige and Skoog (MS) medium with 2% (w/v) sucrose, and supplemented with 12.0 μM 6-benzyladenine (BA). They were transferred to a temporary immersion system (TIS) using liquid MS medium supplemented with 0 (CK-free medium), 6.0, 12.0, 18.0 μM BA. The morphological and anatomical indicators were measured. The BA influenced in vitro multiplication of B. vulgaris. The best results were achieved in the SIT with a concentration of 6.0 μM of BA, which increased the number of shoots (5.1 shoots/explant) in the absence of hyperhydric shoots. Results demonstrated that the water content in the sprouts increased with 12.0 and 18.0 μM BA every four hours. Furthermore, these high levels of BA contributed to a lower accumulation of phenolic compounds and lignin content. The total chlorophyll significantly increased when using 6.0 uM BA, but decreased both parameters with other treatments. These results favor to increase the number of shoots/explants during in vitro multiplication. They will also optimize the in vitro culture conditions, leading to an improvement of in vitro propagation methods for this species.
文摘Boolean homomorphisms of a hypercube, which correspond to the morphisms in the category of finite Boolean algebras, coincide with the linear isometries of the category of finite binary metric vector spaces.
基金supported by the bilateral agreement CAPES-Brazil/MES–Cuba(project number 146/12)carried out at the Brazilian research laboratories LAPROSOLDA-LDTAD from Federal University of Uberlandia(UFU)DEMa-CCDM from Federal University of Sao Carlos(UFSCar)。
文摘The objective of this work was to study the effect of the heat treatment and further operation aging on the stereological parameters(size,quantity and volume fraction)of precipitates within ferrite grains of a creep-resistant 1.25Cr0.5Mo steel after long-term operation.The heat treatment was similar to the treatment that is carried out in industrial steam pipelines after welding(post weld heat treatment-PWHT)during installation and/or repairing.The operation aging corresponds to a subsequent long in-service operation after repairing.To determine the stereological parameters,SEM digital images were taken from samples of this material after conditions of in-service-aged(after long-term operation),in-service-aged and heat-treated(simulating repairing)and in-service-aged,heat-treated and in-laboratory aged(simulating subsequent long-term operation after repairing).The results indicate that the changes in the stereological parameters of the precipitates within ferrite grains after PWHT is associated with the coarsening process of the within-ferrite-grain precipitates as well as stabilizing the microstructure,since the material aging after PWHT of an in-serviced aged material would not change the stereological parameters.
文摘Background:Diabetes mellitus is a chronic metabolic disease that is a risk factor for epidemic pathologies.Under hyperglycemic conditions,the enzyme aldose reductase catalyzes the formation of sorbitol in the metabolism of glucose via polyols,leading to the development of diabetic complications.Therefore,inhibitors of this enzyme are therapeutic targets for the prophylaxis and treatment of these conditions.Methods:In this study,a generalized linear regression model was developed to analyze flavonoids-obtained from a database-that have been tested as inhibitors of aldose reductase.In this sense,the molecular descriptors implemented in DRAGON and MATLAB software were used to determine the correlation between the chemical structure of the inhibitors and their pharmacological activity.The model was validated according to the Organisation for Economic Co-operation and Development Standards and subsequently used for the virtual screening of the flavonoids identified in Jatropha gossypiifolia L.Results:The proposed model showed a good fit for its statistical parameters(R2=0.95).In addition,it showed good predictive power(R2 ext=0.94)and robustness(Q2 LOO=0.92).The experimental chemical space wherein the predictions were reliable(domain of application)was also defined.Finally,the model was used to identify 10 flavonoids from Jatropha gossypiifolia L.as candidates for natural drugs.Compounds with a low probability of oral absorption were identified,among which the elagic acid biflavonoid showed the greatest promise(pIC50 predicted=9.75).Conclusion:The Jatropha gossypiifolia L.species harbors flavonoids with high potential as inhibitors of the aldose reductase enzyme,in which the biflavonoid ellagic acid was shown to be the most promising inhibitor of the aldose reductase enzyme,suggesting its possible use in the treatment of the late complications of diabetes mellitus.