• Magazine of korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.101-112
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• 2019

This case study presented a simplified failure mechanism approach used as a preliminary deformation prediction for the Mexico City's metro system expansion. Because of the Mexico City's difficult subsoils, Line 12 project was considered one of the most challenging projects in Mexico. Mexico City's subsurface conditions can be described as a multilayered stratigraphy changing from soft high plastic clays to dense to very dense cemented sands. The Line 12 trajectory crossed all three main geotechnical Zones in Mexico City. Starting from to west of the City, Line 12 was projected to pass through very dense cemented sands corresponding to the Foothills zone changing to the Transition zone and finalizing in the Lake zone. Due to the change in the subsurface conditions, different constructions methods were implemented including the use of TBM (Tunnel Boring Machine), the NATM (New Austrian Tunneling Method), and cut-and-cover using braced Diaphragm walls for the underground section of the project. Preliminary crown and excavation front deformations were determined using a simplified failure mechanism prior to performing finite element modeling and analysis. Results showed corresponding deformations for the crown and the excavation front to be 3.5cm (1.4in) and 6cm (2.4in), respectively. Considering the complexity of Mexico City's difficult subsoil formation, construction method selection becomes a challenge to overcome. The use of a preliminary results in order to have a notion of possible deformations prior to advanced modeling and analysis could be beneficial and helpful to select possible construction procedures.

• Journal of the Korean Geographical Society
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• v.32 no.2
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• pp.155-174
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• 1997

This paper's main objective is to present an assessment of the impact of NAFTA on the economic structure of the Mexican northem borderlands. The NAFTA is the strategy of a free trade agreement with the United States and Canada, first mentioned by Salinas in June 1990 and established since January 1994. Mexican govemment permitted factories called maquiladoras at the northem borderlands for the first time in 1965. in the early 1980s Mexico was in a deep economic crisis and the international environment was adverse to Mexico. Mexico began to move toward an open economy and abandoned the import-substitution industrialization model that characterized Mexico since the 1930s. Through the new economic reform, the market system was preferred to the regulation; the private ownership, to the public ownership; and the competition, to the protection. The most phenomenal urbanization in northem Mexico has occurred around the major crossing points along the Mexico-U.S. border. The rapid urbanization in northern Mexico has been much due to the industrialization, brought about bv the maquiladora programs and, recently, by the NAFTA.

• Mycobiology
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• v.48 no.5
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• pp.410-417
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• 2020

Fungal ecological interactions play a key role in structuring community assemblages. These associations may involve both antagonistic and synergistic relationships, which are commonly influenced by abiotic factors such as nutrient conditions. However, information for extreme, oligotrophic systems remain poor. Herein, interactions among key members of the aquatic transient fungal community (Aspergillus niger, Cladosporium sp., and Coprinellus micaceus) of a low-nutrient freshwater system in the Cuatro Ci enegas Basin, Mexico were studied. Pairwise interaction bioassays were explored in vitro under different nutrient conditions, including carbohydrates-rich, carbohydrates and amino peptides-rich, and low nutrients. Our results indicated that antagonistic patterns prevail among the studied taxa. However, nutrient-dependent changes were observed in Cladosporium sp. shifting to synergy under carbohydrates-rich conditions, suggesting changes in the fungal community composition as a result of nutrient enrichment. Remarkably, our findings contrast with previous work demonstrating mainly synergistic interactions between our tested fungal isolates and co-occurring autochthonous bacteria (Aeromonas spp. and Vibrio sp.) under low-nutrient conditions. This observation may indicate that bacteria and fungi exhibit distinct community-level responses, driven by nutrient conditions. This contributes to the knowledge of fungal community dynamics and interspecific interactions in an oligotrophic ecosystem, highlighting the relevance of nutrient-based shifts and antagonistic interactions in ecosystem dynamics.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.13-13
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• 1992

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.15-15
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• 1992

• Journal for History of Mathematics
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• v.10 no.1
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• pp.39-45
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• 1997

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1345-1351
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• 2011

Vancomycin therapy failure due to the emergence of tolerance in pneumococci is increasing. The molecular mechanism of tolerance is not clear, but lytA and $pep^{27}$ are known to be involved. Our aim was to evaluate the expression of both genes in vancomycin-tolerant Streptococcus pneumoniae (VTSP) strains. Eleven VTSP strains from a total of 309 clinical isolates of S. pneumoniae from 1997 to 2006 were classified according to the criteria of Liu and Tomasz. All VTSP strains were evaluated for susceptibility according to CLSI criteria, serotype by the Quellung test, and clonality by PFGE. The expressions of lytA and $pep^{27}$ were analyzed in different growth phases by RT-PCR with and without vancomycin. Eighty-two percent of VTSP strains showed resistance to penicillin, and 100% were sensitive to vancomycin and cefotaxime. The most frequent serotypes of VTSP strains were 23F (4/11) and 6B (3/11). Clonal relationship was observed in only two strains. No significant changes were observed in $pep^{27}$ expression in the three phases of growth in VTSP strains with and without vancomycin. Interestingly, $pep^{27}$ expression in the stationary phase in the non-tolerant reference strain R6 was significantly higher. However, no significant differences in lytA expression were observed between VTSP and R6 strains during the phases of growth analyzed. The absence of changes in $pep^{27}$ expression in VTSP strains in the stationary phase may be related to their ability to tolerate high antibiotic concentrations, and thus, they survive and remain in the host under the antibiotic selective pressure reflected in therapeutic failure.

• International Commerce and Information Review
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• v.11 no.3
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• pp.363-390
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• 2009

This study investigates the role of private participation in FTA Negotiation in case of US, Mexico and Japan. We utilize Putnam(1988)'s two stage negotiation model, Schelling Conjecture and Principal-Agent(P-A) theory to understand the role of private sector in FTA Negotiation. Those theories are useful to understand the behavior and interaction of key players such as private sector, congress and government in FTA negotiation. Putnam(1988)'s two stage negotiation model divides the FTA negotiation process into two processes: the external negotiation with foreign country and domestic negotiation with domestic interest group. Principal-Agent(P-A) theory provides the theoretical foundation of Putnam's two stage negotiation model, which is that principal's interest is not identical to the interest of Agent. We showed that the private sector and congress play an important role in FTA negotiation in United States. In case of Mexico, the private sector and government occupy the dominant position in FTA negotiation. In particular, the cooperation of industry and government has been successfully established via COECE in Mexico. In contrast to these countries, the role of private participation in trade policy is relatively low in Japan and Korea.

• Journal of Electrochemical Science and Technology
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• v.8 no.4
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• pp.294-306
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• 2017

Stainless steels and titanium alloys are widely used in the medical industry as replacement materials. These materials may be affected by the conditions and type of environment. In the same manner, soft drinks are widely consumed products. It is of interest for dental industry to know the behavior of medical-grade alloys when these are in contact with soft drinks, since any excessive ion release can suppose a risk for human health. In the present study, the electrochemical behavior of three stainless steel alloys and pure titanium was analyzed using three types of cola soft drinks as electrolyte. The objective of this study was to evaluate the response of these metallic materials in each type of solution (cola standard, light and zero). Different electrochemical techniques were used for the evaluation of the alloys, namely potentiodynamic polarization, linear polarization, and open-circuit potential measurements. The corrosion resistance of the stainless-steel alloys and titanium in the cola soft drinks was provided by the formation of a stable passive film formed by metal oxides. Scanning electron microscopy was used as a complementary technique to reveal corrosion phenomena at the surface of the materials evaluated.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.6
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• pp.365-369
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• 2016

Objectives: To determine the prevalence and oral characteristics of cancer patients treated with bisphosphonates in the oncology and maxillofacial prosthesis departments of the General Hospital of Mexico between 2011 and 2013. Materials and Methods: This cross-sectional study included patients who received prior treatment with bisphosphonates; an intraoral examination was performed by 2 standardized examiners. Results: The prevalence of bisphosphonate-related necrosis in 75 patients was 2.6%; the most common malignancy was breast cancer (84.0%), followed by prostate cancer (16.0%). Exostosis was present in 9.3% of patients and the mean Decayed, Missing, Filled Teeth index was 4.64; 44.0% of the study group had a Community Periodontal Index value between 2 and 2.9 (mean, 0.60). Conclusion: A detailed intraoral assessment must be performed before initiating treatment with bisphosphonates to identify risk factors for osteonecrosis.