Information Technology (IT) consolidates as an essential element to support the business strategies to survive and rapidly adapts to changes in the competitive environment. This paper examines the impact of the use ...Information Technology (IT) consolidates as an essential element to support the business strategies to survive and rapidly adapts to changes in the competitive environment. This paper examines the impact of the use of information systems (IS) and strategic organization knowledge (SOK) on firm performance in 150 Brazilian companies. The study uses partial least squares structural equation modeling (PLS-SEM) and establishes models to express the relationship among the constructs examined. The study identifies that the direct influence of 1S use on performance is moderately significant. However, when mediated by orientation strategy, the total effect of IS use on firm performance is demonstrated to be highly significant. The model explains 54% of the variability of firm performance and confirms IS use as a fundamental resource to support strategic business processes.展开更多
This paper is devoted to studying symmetry reduction of Cauchy problems for the fourth-order quasi-linear parabolic equations that admit certain generalized conditional symmetries (GCSs). Complete group classificati...This paper is devoted to studying symmetry reduction of Cauchy problems for the fourth-order quasi-linear parabolic equations that admit certain generalized conditional symmetries (GCSs). Complete group classification results are presented, and some examples are given to show the main reduction procedure.展开更多
Hybrid modeling approaches have recently been investigated as an attractive alternative to model fermentation processes. Normally, these approaches require estimation data to train the empirical model part of a hybrid...Hybrid modeling approaches have recently been investigated as an attractive alternative to model fermentation processes. Normally, these approaches require estimation data to train the empirical model part of a hybrid model. This may result in decreasing the generalization ability of the derived hybrid model. Therefore, a simultaneous hybrid modeling approach is presented in this paper. It transforms the training of the empirical model part into a dynamic system parameter identification problem, and thus allows training the empirical model part with only measured data. An adaptive escaping particle swarm optimization(AEPSO) algorithm with escaping and adaptive inertia weight adjustment strategies is constructed to solve the resulting parameter identification problem, and thereby accomplish the training of the empirical model part. The uniform design method is used to determine the empirical model structure. The proposed simultaneous hybrid modeling approach has been used in a lab-scale nosiheptide batch fermentation process. The results show that it is effective and leads to a more consistent model with better generalization ability when compared to existing ones. The performance of AEPSO is also demonstrated.展开更多
The Cauchy problem for some parabolic fractional partial differential equation of higher orders and with time delays is considered. The existence and unique solution of this problem is studied. Some smoothness propert...The Cauchy problem for some parabolic fractional partial differential equation of higher orders and with time delays is considered. The existence and unique solution of this problem is studied. Some smoothness properties with respect to the parameters of these delay fractional differential equations are considered.展开更多
This paper uses a Value at Risk (VaR) approach to evaluate a country financial vulnerability, by analyzing the risk exposure of its Central Bank, as if their assets are subject to market risk. The Brazilian currency...This paper uses a Value at Risk (VaR) approach to evaluate a country financial vulnerability, by analyzing the risk exposure of its Central Bank, as if their assets are subject to market risk. The Brazilian currency exchange swaps contracts (USS/Brazilian Reais) are submitted to a delta-normal VaR method, in order to evaluate the market risk of each swaps series, by modeling the variance of the daily returns, from August 1999 to January 2003. All daily returns series exhibited heteroscedasticity in the conditional variance and sudden changes in the unconditional variance. The points of changes of the unconditional variance were determined through the Iterative Cumulative Sum of Squares (ICSS) algorithm, and the conditional variance was modeled with Markov-Switching-Generalized Autoregressive Conditional Heteroscedasticity (SWGARCH) in order to capture heteroscedasticity and regime change. The results lead to two main conclusions: First, a VaR model must incorporate heteroscedasticity and regime switching in order to describe the variance of the tested series, submitted to brisk changes of economic and political scenarios. Second, a volatility-based VaR do not necessarily generate forward-looking indicators, but rather coincident indicators of possible financial vulnerabilities. The future research will evolve towards evaluating the effects of the Basel III recommendations as if they could be applied to this crisis period.展开更多
The agency theory indicates the existence of costs as a way to mitigate conflicts between shareholders and managers, including: managerial compensation program, acquisition of shares by managers, monitoring of execut...The agency theory indicates the existence of costs as a way to mitigate conflicts between shareholders and managers, including: managerial compensation program, acquisition of shares by managers, monitoring of executives, and controlling shareholders. This study aims to determine the relevance of some variables related to compensation programs and of other determinants of the corporate debt level. It has considered a sample of 89 firms, which were analyzed through logistic regression (cross section). The model created has indicated a level of predictive assertiveness of approximately 87%.展开更多
This study developed a short-term econometric model of world natural rubber price Standard Malaysia Rubber Grade 20 (SMR20). Both single and simultaneous equations were utilized using monthly data from January 1990-...This study developed a short-term econometric model of world natural rubber price Standard Malaysia Rubber Grade 20 (SMR20). Both single and simultaneous equations were utilized using monthly data from January 1990-December 2008 as estimation period and data from January 2009-June 2009 was used as an ex-ante forecast. The data were tested for unit root and Vector Error Correction and co-integration method was used to estimate the parameters of the model. The models specifications were developed in order to discover the inter-relationships between NR production, consumption and prices of SMR20 and to determine forecast price of SMR20. Comparative analysis between the single-equation specification and simultaneous supply-demand and price equation were made in terms of their estimation accuracy based on RMSE, MAE and (U-Thile) criteria. Ex-ante forecasts was carried out for the period of January 2009-June 2009. The results revealed that the values of the RMSE, MAE and U of simultaneous supply-demand and price equations model were comparatively smaller than the values generated by the single-equation model. These statistics suggest that the simultaneous equation of supply-demand and price model is more accurate and efficient measure in terms of its statistical criteria than the single-equation model in predicting the price of SMR20 in the next 6 months.展开更多
Fish farming is a strategic activity for both the economy and food security of the Tocantins state. Nowadays, there are about eighty small fish farmers in the region of Divin6polis in Tocantins state. The technologica...Fish farming is a strategic activity for both the economy and food security of the Tocantins state. Nowadays, there are about eighty small fish farmers in the region of Divin6polis in Tocantins state. The technological level of fish farmers is low and it was found that only 30% of farmers could ever get to the point of selling fish. Therefore, the objective of this paper is to investigate which socioeconomic factors have influence on the fact of fish farmers in the region of Divin6polis and in Tocantins state reach a level of efficiency in production enough that the fish can be good for sale in the local market. To estimate this relation the logit model was chosen, with methodology based on the empirical model used in Musaba and Namukwambi. Following the production of fish farms in the Western of Tocantins state, the collect of the data, during 2012, were conduct with interviews of 30 fish farms, visiting them in their homes and applying a questionnaire. Through the use of econometric models of probability for limited dependent variables, it was found that factors such as participation in federal programs to transfer income, total area of water and production in ponds are key factors in determining the likelihood of producer to sell fish.展开更多
In this paper, we study the optimal control problem of nonlinear differentialinclusions with principle operator being pseudomonotone. First, we give some propertiesof solutions of certain evolution equations. Further,...In this paper, we study the optimal control problem of nonlinear differentialinclusions with principle operator being pseudomonotone. First, we give some propertiesof solutions of certain evolution equations. Further, we prove the existence of admissibletrajectories for evolution inclusions. Then, we extend the Fillipov's selection theoremand discuss a general Lagrange type optimal control problem. Finally, we present anexample that demonstrates the appplicability of our results.展开更多
Prostate cancer is a common malignancy among men in Western countries. Recently the morbidity and mortality of prostate cancer increase dramatically in several oriental countries including China. Rapidly evolving tech...Prostate cancer is a common malignancy among men in Western countries. Recently the morbidity and mortality of prostate cancer increase dramatically in several oriental countries including China. Rapidly evolving technology in molecular biology such as high-throughput sequencing and integrative analysis of genomic and transcriptomic landscapes have enabled the identification of key oncogenic events for prostate cancer initiation, progression and resistance to hormonal therapy. These surging data of prostate cancer genome also provide insights on ethnic variation and the differences in histological subtype of this disease. In this review, differences in the incidence of prostate cancer and the prevalence of main genetic alterations between Asian and Western populations are discussed. We also review the recent findings on the mechanisms underlying neuroendocrine differentiation of prostate cancer and the development of small cell neuroendocrine carcinoma after androgen deprivation therapy.展开更多
The authors prove well posedness in Gevrey classes of Cauchy problem for nonlinear hyper- bolic equations of constant multiplicity with Holder dependence on the time variable.
The Niutangjie tungsten deposit is a bedded skarn-type scheelite deposit and is located at the junction between Ziyuan and Xingan counties in the north of Guangxi,China.The deposit is genetically related to a fine-gra...The Niutangjie tungsten deposit is a bedded skarn-type scheelite deposit and is located at the junction between Ziyuan and Xingan counties in the north of Guangxi,China.The deposit is genetically related to a fine-grained two-mica granite within the orefield.Zircon LA-ICP-MS U-Pb dating of the granite yielded a Silurian(Caledonian)age of 421.8±2.4 Ma,which is contemporaneous with the adjacent Yuechengling batholith.Mineralization within the skarn is associated with a quartz,garnet,and diopside gangue,and scheelite is present in a number of different mineral assemblages,such as quartz-scheelite and quartz-sulfide-scheelite;these assemblages correspond to oxide and sulfide stages of mineralization.Sm-Nd isotope analysis of scheelite yielded an isochron age of 421±24 Ma.Although the uncertainty on this date is high,this age suggests that the scheelite mineralization formed during the Late Caledonian,at a similar time to the emplacement of the Niutangjie granite.Zircons within the granite have?Hf(t)values and Hf two-stage model ages of?6.5 to?11.6,and 1.79 to 2.11 Ga,respectively.These data suggest that the magma that formed the granite was derived from Mesoproterozoic crustal materials.Scheelite?Nd(t)values range from?13.06 to?13.26,also indicative of derivation from ancient crustal materials.Recent research has identified Caledonian magmatism in the western Nanling Range,indicating that this magmatism may be the source of contemporaneous tungsten mineralization.展开更多
We study the Cauchy problem of a semilinear parabolic equation. We construct an appropriate Harnack quantity and get a differential Harnack inequality. Using this inequality, we prove the finite-time blow-up of the po...We study the Cauchy problem of a semilinear parabolic equation. We construct an appropriate Harnack quantity and get a differential Harnack inequality. Using this inequality, we prove the finite-time blow-up of the positive solutions and recover a classical Harnack inequality. We also obtain a result of Liouville type for the elliptic equation.展开更多
In this paper, we consider the following equation ut=(um)xx+(un)x, with the initial condition as Dirac measure. Attention is focused on existence, nonexistence, uniqueness and the asymptotic behavior near (0,0)...In this paper, we consider the following equation ut=(um)xx+(un)x, with the initial condition as Dirac measure. Attention is focused on existence, nonexistence, uniqueness and the asymptotic behavior near (0,0) of solution to the Cauchy's problem. The special feature of this equation lies in nonlinear convection effect, i.e., the equation possesses nonlinear hyperbolic character as well as degenerate parabolic one. The situation leads to a more sophisticated mathematical analysis. To our knowledge, the solvability of singular solution to the equation has not been concluded yet. Here based on the previous works by the authors, we show that there exists a critical number n0=m+2 such that a unique source-type solution to this equation exists if 0≤n展开更多
文摘Information Technology (IT) consolidates as an essential element to support the business strategies to survive and rapidly adapts to changes in the competitive environment. This paper examines the impact of the use of information systems (IS) and strategic organization knowledge (SOK) on firm performance in 150 Brazilian companies. The study uses partial least squares structural equation modeling (PLS-SEM) and establishes models to express the relationship among the constructs examined. The study identifies that the direct influence of 1S use on performance is moderately significant. However, when mediated by orientation strategy, the total effect of IS use on firm performance is demonstrated to be highly significant. The model explains 54% of the variability of firm performance and confirms IS use as a fundamental resource to support strategic business processes.
基金Supported by the National Natural Science Foundation of China under Grant No.10671156the Natural Science Foundation of Shaanxi Province of China under Grant No.SJ08A05
文摘This paper is devoted to studying symmetry reduction of Cauchy problems for the fourth-order quasi-linear parabolic equations that admit certain generalized conditional symmetries (GCSs). Complete group classification results are presented, and some examples are given to show the main reduction procedure.
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120042120014)
文摘Hybrid modeling approaches have recently been investigated as an attractive alternative to model fermentation processes. Normally, these approaches require estimation data to train the empirical model part of a hybrid model. This may result in decreasing the generalization ability of the derived hybrid model. Therefore, a simultaneous hybrid modeling approach is presented in this paper. It transforms the training of the empirical model part into a dynamic system parameter identification problem, and thus allows training the empirical model part with only measured data. An adaptive escaping particle swarm optimization(AEPSO) algorithm with escaping and adaptive inertia weight adjustment strategies is constructed to solve the resulting parameter identification problem, and thereby accomplish the training of the empirical model part. The uniform design method is used to determine the empirical model structure. The proposed simultaneous hybrid modeling approach has been used in a lab-scale nosiheptide batch fermentation process. The results show that it is effective and leads to a more consistent model with better generalization ability when compared to existing ones. The performance of AEPSO is also demonstrated.
文摘The Cauchy problem for some parabolic fractional partial differential equation of higher orders and with time delays is considered. The existence and unique solution of this problem is studied. Some smoothness properties with respect to the parameters of these delay fractional differential equations are considered.
文摘This paper uses a Value at Risk (VaR) approach to evaluate a country financial vulnerability, by analyzing the risk exposure of its Central Bank, as if their assets are subject to market risk. The Brazilian currency exchange swaps contracts (USS/Brazilian Reais) are submitted to a delta-normal VaR method, in order to evaluate the market risk of each swaps series, by modeling the variance of the daily returns, from August 1999 to January 2003. All daily returns series exhibited heteroscedasticity in the conditional variance and sudden changes in the unconditional variance. The points of changes of the unconditional variance were determined through the Iterative Cumulative Sum of Squares (ICSS) algorithm, and the conditional variance was modeled with Markov-Switching-Generalized Autoregressive Conditional Heteroscedasticity (SWGARCH) in order to capture heteroscedasticity and regime change. The results lead to two main conclusions: First, a VaR model must incorporate heteroscedasticity and regime switching in order to describe the variance of the tested series, submitted to brisk changes of economic and political scenarios. Second, a volatility-based VaR do not necessarily generate forward-looking indicators, but rather coincident indicators of possible financial vulnerabilities. The future research will evolve towards evaluating the effects of the Basel III recommendations as if they could be applied to this crisis period.
文摘The agency theory indicates the existence of costs as a way to mitigate conflicts between shareholders and managers, including: managerial compensation program, acquisition of shares by managers, monitoring of executives, and controlling shareholders. This study aims to determine the relevance of some variables related to compensation programs and of other determinants of the corporate debt level. It has considered a sample of 89 firms, which were analyzed through logistic regression (cross section). The model created has indicated a level of predictive assertiveness of approximately 87%.
文摘This study developed a short-term econometric model of world natural rubber price Standard Malaysia Rubber Grade 20 (SMR20). Both single and simultaneous equations were utilized using monthly data from January 1990-December 2008 as estimation period and data from January 2009-June 2009 was used as an ex-ante forecast. The data were tested for unit root and Vector Error Correction and co-integration method was used to estimate the parameters of the model. The models specifications were developed in order to discover the inter-relationships between NR production, consumption and prices of SMR20 and to determine forecast price of SMR20. Comparative analysis between the single-equation specification and simultaneous supply-demand and price equation were made in terms of their estimation accuracy based on RMSE, MAE and (U-Thile) criteria. Ex-ante forecasts was carried out for the period of January 2009-June 2009. The results revealed that the values of the RMSE, MAE and U of simultaneous supply-demand and price equations model were comparatively smaller than the values generated by the single-equation model. These statistics suggest that the simultaneous equation of supply-demand and price model is more accurate and efficient measure in terms of its statistical criteria than the single-equation model in predicting the price of SMR20 in the next 6 months.
文摘Fish farming is a strategic activity for both the economy and food security of the Tocantins state. Nowadays, there are about eighty small fish farmers in the region of Divin6polis in Tocantins state. The technological level of fish farmers is low and it was found that only 30% of farmers could ever get to the point of selling fish. Therefore, the objective of this paper is to investigate which socioeconomic factors have influence on the fact of fish farmers in the region of Divin6polis and in Tocantins state reach a level of efficiency in production enough that the fish can be good for sale in the local market. To estimate this relation the logit model was chosen, with methodology based on the empirical model used in Musaba and Namukwambi. Following the production of fish farms in the Western of Tocantins state, the collect of the data, during 2012, were conduct with interviews of 30 fish farms, visiting them in their homes and applying a questionnaire. Through the use of econometric models of probability for limited dependent variables, it was found that factors such as participation in federal programs to transfer income, total area of water and production in ponds are key factors in determining the likelihood of producer to sell fish.
基金Supported by the Natural Science Foundation of Guizhou university(200101007)
文摘In this paper, we study the optimal control problem of nonlinear differentialinclusions with principle operator being pseudomonotone. First, we give some propertiesof solutions of certain evolution equations. Further, we prove the existence of admissibletrajectories for evolution inclusions. Then, we extend the Fillipov's selection theoremand discuss a general Lagrange type optimal control problem. Finally, we present anexample that demonstrates the appplicability of our results.
基金supported by the Prostate Cancer Foundationthe Broad Stem Cell Research Center at University of California, Los Angeles+5 种基金supported by the Department of Defense Prostate Cancer Research Program W81XWH-11-1-0227 (PI: Jiaoti Huang)W81XWH-12-1-0206 (PI: Lily Wu)UCLA SPORE in prostate cancer (PI: Robert Reiter)NCI 1R01CA158627 (PI: Leonard Marks)Stand-up-to-Cancer Dream Team Award (PI: Small and Witte)Prostate Cancer Foundation Honorable A. David Mazzone Special Challenge Award (PI: Robert Reiter)
文摘Prostate cancer is a common malignancy among men in Western countries. Recently the morbidity and mortality of prostate cancer increase dramatically in several oriental countries including China. Rapidly evolving technology in molecular biology such as high-throughput sequencing and integrative analysis of genomic and transcriptomic landscapes have enabled the identification of key oncogenic events for prostate cancer initiation, progression and resistance to hormonal therapy. These surging data of prostate cancer genome also provide insights on ethnic variation and the differences in histological subtype of this disease. In this review, differences in the incidence of prostate cancer and the prevalence of main genetic alterations between Asian and Western populations are discussed. We also review the recent findings on the mechanisms underlying neuroendocrine differentiation of prostate cancer and the development of small cell neuroendocrine carcinoma after androgen deprivation therapy.
文摘The authors prove well posedness in Gevrey classes of Cauchy problem for nonlinear hyper- bolic equations of constant multiplicity with Holder dependence on the time variable.
基金financially supported by National Natural Science Foundation of China (Grant Nos. 41172074, 41230315)Ministry of Science and Technology of China (Grant No. 2012CB416704)+1 种基金China Geological Survey (Grant No. 1212010632100)Deep Exploration Program of the Ministry of Land and Resources (Grant No. 201011046)
文摘The Niutangjie tungsten deposit is a bedded skarn-type scheelite deposit and is located at the junction between Ziyuan and Xingan counties in the north of Guangxi,China.The deposit is genetically related to a fine-grained two-mica granite within the orefield.Zircon LA-ICP-MS U-Pb dating of the granite yielded a Silurian(Caledonian)age of 421.8±2.4 Ma,which is contemporaneous with the adjacent Yuechengling batholith.Mineralization within the skarn is associated with a quartz,garnet,and diopside gangue,and scheelite is present in a number of different mineral assemblages,such as quartz-scheelite and quartz-sulfide-scheelite;these assemblages correspond to oxide and sulfide stages of mineralization.Sm-Nd isotope analysis of scheelite yielded an isochron age of 421±24 Ma.Although the uncertainty on this date is high,this age suggests that the scheelite mineralization formed during the Late Caledonian,at a similar time to the emplacement of the Niutangjie granite.Zircons within the granite have?Hf(t)values and Hf two-stage model ages of?6.5 to?11.6,and 1.79 to 2.11 Ga,respectively.These data suggest that the magma that formed the granite was derived from Mesoproterozoic crustal materials.Scheelite?Nd(t)values range from?13.06 to?13.26,also indicative of derivation from ancient crustal materials.Recent research has identified Caledonian magmatism in the western Nanling Range,indicating that this magmatism may be the source of contemporaneous tungsten mineralization.
文摘We study the Cauchy problem of a semilinear parabolic equation. We construct an appropriate Harnack quantity and get a differential Harnack inequality. Using this inequality, we prove the finite-time blow-up of the positive solutions and recover a classical Harnack inequality. We also obtain a result of Liouville type for the elliptic equation.
基金National Natural Science Foundation of China (Grant Nos. 10671103 and 11001142)
文摘In this paper, we consider the following equation ut=(um)xx+(un)x, with the initial condition as Dirac measure. Attention is focused on existence, nonexistence, uniqueness and the asymptotic behavior near (0,0) of solution to the Cauchy's problem. The special feature of this equation lies in nonlinear convection effect, i.e., the equation possesses nonlinear hyperbolic character as well as degenerate parabolic one. The situation leads to a more sophisticated mathematical analysis. To our knowledge, the solvability of singular solution to the equation has not been concluded yet. Here based on the previous works by the authors, we show that there exists a critical number n0=m+2 such that a unique source-type solution to this equation exists if 0≤n