Concession contracts in highways often include some kind of clauses （for example, a minimum traffic guarantee） that allow for better management of the business risks. The value of these clauses may be important and ...Concession contracts in highways often include some kind of clauses （for example, a minimum traffic guarantee） that allow for better management of the business risks. The value of these clauses may be important and should be added to the total value of the concession. However, in these cases, traditional valuation techniques, like the NPV （net present value） of the project, are insufficient. An alternative methodology for the valuation of highway concession is one based on the real options approach. This methodology is generally built on the assumption of the evolution of traffic volume as a GBM （geometric Brownian motion）, which is the hypothesis analyzed in this paper. First, a description of the methodology used for the analysis of the existence of unit roots （i.e., the hypothesis of non-stationarity） is provided. The Dickey-Fuller approach has been used, which is the most common test for this kind of analysis. Then this methodology is applied to perform a statistical analysis of traffic series in Spanish toll highways. For this purpose, data on the AADT （annual average daily traffic） on a set of highways have been used. The period of analysis is around thirty years in most cases. The main outcome of the research is that the hypothesis that traffic volume follows a GBM process in Spanish toll highways cannot be rejected. This result is robust, and therefore it can be used as a starting point for the application of the real options theory to assess toll highway concessions.展开更多
Budget hotels, as an emerging hotel model, were started and attained a rapid development in China in the last ten years, and have proven to be important part of China抯 hotel industry. As competitions in the hotel ind...Budget hotels, as an emerging hotel model, were started and attained a rapid development in China in the last ten years, and have proven to be important part of China抯 hotel industry. As competitions in the hotel industry become increasingly fiercer, budget hotel brands launch a fight for seizing more market share. Therefore, it is necessary for Xuchang Jinjiang INN as a famous hotel brand to be distinguished from the hotel product strategies of the developed economic areas in the development environment of the small and medium-sized tourism cities, so as to adapt to the characteristics of regional market.展开更多
Private security companies through the services they provide complement the police in crime prevention, order maintenance, and general improvement of security in societies thereby contributing to sustainable national ...Private security companies through the services they provide complement the police in crime prevention, order maintenance, and general improvement of security in societies thereby contributing to sustainable national development In order to fully benefit from their contribution and prevent them from engaging in illegal activities, states formulate and enforce policies that seek to regulate their activities. This paper examines the regulation of private guards companies in Nigeria using Abuja as its empirical core. The main aim is to promote understanding of how the private security industry is regulated and evaluate the effectiveness of the existing regulatory policy. Data for the paper were generated from in-depth interviews with the NSCDC （Nigeria Security and Civil Defence Corps）, analysis of the policy for PSCs （private security companies）, and a review of the annual performance report of the regulatory agency. The results revealed that the current system of PSC regulation is characterized by a lack of specialty classification of private security licences, limited regulatory scope with a focus on licensing of companies, lack of uniform standards on training, and high cost/difficulties in obtaining operational license. The paper concludes that the current regulatory setup for PSCs in Nigeria is ineffective and unsustainable and recommends an urgent review of the legal framework to alien its provisions with global standards and practices in the private security industry.展开更多
External Corporate Social and Environmental Reporting （CSER） finds its raison d＇etre in corporations＇ search for both a license to operate and accountability towards society. This suggests a relationship between c...External Corporate Social and Environmental Reporting （CSER） finds its raison d＇etre in corporations＇ search for both a license to operate and accountability towards society. This suggests a relationship between corporations and society. In this study, that relationship is analyzed, specifically the relationship between levels of CSER and economic institutions. A strong link with institutions is an outcome of institutionalization. The economic institutions applied are economic freedom and legal origin as a proxy for national corporate governance systems. The results of this descriptive study show associations between CSER levels and economic freedom. CSER is also related to national corporate governance systems through legal origin. CSER appears to be institutionalized, or in any case, corporations seem to be aware of the economic institutionalization of CSER.展开更多
Objective: To investigate the expression of neurotrophin-3 (NT-3) gene in Schwann cells of rat sciatic nerve introduced by an adenovirus vector in vivo. Methods: A recombinant adenovirus vector for NT-3 (Ad-NT-3) was ...Objective: To investigate the expression of neurotrophin-3 (NT-3) gene in Schwann cells of rat sciatic nerve introduced by an adenovirus vector in vivo. Methods: A recombinant adenovirus vector for NT-3 (Ad-NT-3) was propagated in 293 packaging cells and titered with tissue culture infectious dose 50 (TCID 50). Ad-NT-3 was injected directly into the rat sciatic nerve after transection and immediate repair. Immunohistochemical staining was employed to determine the expression of NT-3 in Schwann cells in rat sciatic nerve and the expressive intensity of the tissue slices of the sciatic nerve was measured with LEICA M550 image analysis system. Results: On the 2nd day after injection of Ad-NT-3, positive stain in the Schwann cells was apparent in the vicinity of anastomosis. NT-3 expression increased significantly on the 7th day (P< 0.01) and then decreased 14-28 days after injection (P< 0.01). There was no significant difference of NT-3 expression between the 14th and 28th day groups (P> 0.05). Compared with the 2nd day group, the 14th and 28th day groups still maintained a relatively high level of NT-3 (P< 0.01). Intact and repaired nerves, which were injected with adenovirus encoding LacZ genes ( Ad-LacZ) or physiological saline served as controls, showed no NT-3-positive Schwann cells. Conclusions: An adenovirus vector can be used to induce efficiently the expression of NT-3 gene in Schwann cells of rat peripheral nerves following nerve injury and repair, which suggests that neurotrophic factors can be introduced into Schwann cells with an adenovirus vector to promote peripheral nerve regeneration.展开更多
Objective:To study the effect of nerve growth f actor (NGF) and Schwann cells on axon regeneration of the inferior alveolar nerv e following mandibular lengthening with distraction osteogenesis. Methods:Unilateral man...Objective:To study the effect of nerve growth f actor (NGF) and Schwann cells on axon regeneration of the inferior alveolar nerv e following mandibular lengthening with distraction osteogenesis. Methods:Unilateral mandibular osteodistraction was performed i n 9 healthy adult male goats with a distraction rate of 1 mm/d. Every 3 goats we re killed on days 7, 14 and 28 after mandibular lengthening, respectively. The i nferior alveolar nerves in the distraction callus were harvested and processed f or ultrastructural and NGF immunohistochemical study. The inferior alveolar nerv es from the contralateral side were used as controls. Results:On day 7 after distraction, axon degeneration and Schw ann cell proliferation were observed, and very strong staining of NGF in the dis tracted nerve was detected. On day 14 after distraction, axon regeneration and r emyelination were easily observed, and NGF expression started to decline. On day 28 after distraction, the gray scale of NGF immunoreactivity recovered to the n ormal value and the Schwann cells almost recovered to their normal state. Conclusions:Gradual mandibular osteodistraction can result in mild or moderate axon degeneration of the inferior alveolar nerve. Nerve trauma may stimulate the proliferation of Schwann cells and promote the synthesis and s ecretion of NGF in the Schwann cells. Schwann cells and NGF might play important roles in axon regeneration of the injured inferior alveolar nerve following man dibular lengthening.展开更多
To investigate the effects of Ginse noside Rb 1 on the proliferation of Schwann cells in culture.Methods: Applying MTT assay and Thymidine incorporation assay, the effects of Ginsenoside Rb 1 on the proliferation of S...To investigate the effects of Ginse noside Rb 1 on the proliferation of Schwann cells in culture.Methods: Applying MTT assay and Thymidine incorporation assay, the effects of Ginsenoside Rb 1 on the proliferation of Schwann cells isolated from the sciatic nerve of adult rat were studied.Results: Ginsenoside Rb 1 (10 μg/ml) significantly induced Sc hwann cell proliferation, the effect was similar to NGF (50 μg/ml). At high con centrations of Ginsenoside Rb 1 (1 mg/ml), the proliferation of Schwann cells w as significantly inhibited. Conclusions: Ginsenoside Rb 1 at the optimal concentrations is found to be effective in inducing the proliferation of Schwann cells, but at hi gher concentrations the drug is cytotoxic for Schwann cells.展开更多
文摘Concession contracts in highways often include some kind of clauses （for example, a minimum traffic guarantee） that allow for better management of the business risks. The value of these clauses may be important and should be added to the total value of the concession. However, in these cases, traditional valuation techniques, like the NPV （net present value） of the project, are insufficient. An alternative methodology for the valuation of highway concession is one based on the real options approach. This methodology is generally built on the assumption of the evolution of traffic volume as a GBM （geometric Brownian motion）, which is the hypothesis analyzed in this paper. First, a description of the methodology used for the analysis of the existence of unit roots （i.e., the hypothesis of non-stationarity） is provided. The Dickey-Fuller approach has been used, which is the most common test for this kind of analysis. Then this methodology is applied to perform a statistical analysis of traffic series in Spanish toll highways. For this purpose, data on the AADT （annual average daily traffic） on a set of highways have been used. The period of analysis is around thirty years in most cases. The main outcome of the research is that the hypothesis that traffic volume follows a GBM process in Spanish toll highways cannot be rejected. This result is robust, and therefore it can be used as a starting point for the application of the real options theory to assess toll highway concessions.
文摘Budget hotels, as an emerging hotel model, were started and attained a rapid development in China in the last ten years, and have proven to be important part of China抯 hotel industry. As competitions in the hotel industry become increasingly fiercer, budget hotel brands launch a fight for seizing more market share. Therefore, it is necessary for Xuchang Jinjiang INN as a famous hotel brand to be distinguished from the hotel product strategies of the developed economic areas in the development environment of the small and medium-sized tourism cities, so as to adapt to the characteristics of regional market.
文摘Private security companies through the services they provide complement the police in crime prevention, order maintenance, and general improvement of security in societies thereby contributing to sustainable national development In order to fully benefit from their contribution and prevent them from engaging in illegal activities, states formulate and enforce policies that seek to regulate their activities. This paper examines the regulation of private guards companies in Nigeria using Abuja as its empirical core. The main aim is to promote understanding of how the private security industry is regulated and evaluate the effectiveness of the existing regulatory policy. Data for the paper were generated from in-depth interviews with the NSCDC （Nigeria Security and Civil Defence Corps）, analysis of the policy for PSCs （private security companies）, and a review of the annual performance report of the regulatory agency. The results revealed that the current system of PSC regulation is characterized by a lack of specialty classification of private security licences, limited regulatory scope with a focus on licensing of companies, lack of uniform standards on training, and high cost/difficulties in obtaining operational license. The paper concludes that the current regulatory setup for PSCs in Nigeria is ineffective and unsustainable and recommends an urgent review of the legal framework to alien its provisions with global standards and practices in the private security industry.
文摘External Corporate Social and Environmental Reporting （CSER） finds its raison d＇etre in corporations＇ search for both a license to operate and accountability towards society. This suggests a relationship between corporations and society. In this study, that relationship is analyzed, specifically the relationship between levels of CSER and economic institutions. A strong link with institutions is an outcome of institutionalization. The economic institutions applied are economic freedom and legal origin as a proxy for national corporate governance systems. The results of this descriptive study show associations between CSER levels and economic freedom. CSER is also related to national corporate governance systems through legal origin. CSER appears to be institutionalized, or in any case, corporations seem to be aware of the economic institutionalization of CSER.
文摘Objective: To investigate the expression of neurotrophin-3 (NT-3) gene in Schwann cells of rat sciatic nerve introduced by an adenovirus vector in vivo. Methods: A recombinant adenovirus vector for NT-3 (Ad-NT-3) was propagated in 293 packaging cells and titered with tissue culture infectious dose 50 (TCID 50). Ad-NT-3 was injected directly into the rat sciatic nerve after transection and immediate repair. Immunohistochemical staining was employed to determine the expression of NT-3 in Schwann cells in rat sciatic nerve and the expressive intensity of the tissue slices of the sciatic nerve was measured with LEICA M550 image analysis system. Results: On the 2nd day after injection of Ad-NT-3, positive stain in the Schwann cells was apparent in the vicinity of anastomosis. NT-3 expression increased significantly on the 7th day (P< 0.01) and then decreased 14-28 days after injection (P< 0.01). There was no significant difference of NT-3 expression between the 14th and 28th day groups (P> 0.05). Compared with the 2nd day group, the 14th and 28th day groups still maintained a relatively high level of NT-3 (P< 0.01). Intact and repaired nerves, which were injected with adenovirus encoding LacZ genes ( Ad-LacZ) or physiological saline served as controls, showed no NT-3-positive Schwann cells. Conclusions: An adenovirus vector can be used to induce efficiently the expression of NT-3 gene in Schwann cells of rat peripheral nerves following nerve injury and repair, which suggests that neurotrophic factors can be introduced into Schwann cells with an adenovirus vector to promote peripheral nerve regeneration.
基金ThisstudywassupportedbytheNationalNaturalScienceFoundationofChina (No .3 9970 797)
文摘Objective:To study the effect of nerve growth f actor (NGF) and Schwann cells on axon regeneration of the inferior alveolar nerv e following mandibular lengthening with distraction osteogenesis. Methods:Unilateral mandibular osteodistraction was performed i n 9 healthy adult male goats with a distraction rate of 1 mm/d. Every 3 goats we re killed on days 7, 14 and 28 after mandibular lengthening, respectively. The i nferior alveolar nerves in the distraction callus were harvested and processed f or ultrastructural and NGF immunohistochemical study. The inferior alveolar nerv es from the contralateral side were used as controls. Results:On day 7 after distraction, axon degeneration and Schw ann cell proliferation were observed, and very strong staining of NGF in the dis tracted nerve was detected. On day 14 after distraction, axon regeneration and r emyelination were easily observed, and NGF expression started to decline. On day 28 after distraction, the gray scale of NGF immunoreactivity recovered to the n ormal value and the Schwann cells almost recovered to their normal state. Conclusions:Gradual mandibular osteodistraction can result in mild or moderate axon degeneration of the inferior alveolar nerve. Nerve trauma may stimulate the proliferation of Schwann cells and promote the synthesis and s ecretion of NGF in the Schwann cells. Schwann cells and NGF might play important roles in axon regeneration of the injured inferior alveolar nerve following man dibular lengthening.
文摘To investigate the effects of Ginse noside Rb 1 on the proliferation of Schwann cells in culture.Methods: Applying MTT assay and Thymidine incorporation assay, the effects of Ginsenoside Rb 1 on the proliferation of Schwann cells isolated from the sciatic nerve of adult rat were studied.Results: Ginsenoside Rb 1 (10 μg/ml) significantly induced Sc hwann cell proliferation, the effect was similar to NGF (50 μg/ml). At high con centrations of Ginsenoside Rb 1 (1 mg/ml), the proliferation of Schwann cells w as significantly inhibited. Conclusions: Ginsenoside Rb 1 at the optimal concentrations is found to be effective in inducing the proliferation of Schwann cells, but at hi gher concentrations the drug is cytotoxic for Schwann cells.
