An analysis of “exactly distributed” test statistics for multivariate event tests

In this paper we derive a rule that identifies when exact tests may be used in the context of the multivariate regression model. Our derivation extends distribution theory reported in Rao (1973) and leads to the specification of exact tests for several event study hypothesis forms of interest to accounting and finance researchers. For tests where the event parameter is constrained to be equal across firms, we show that an infinite set of exact tests is available, of which the well known portfoliot-test is a special case. We conduct simulations using data from the CRSP Daily Returns file, and find that several test statistics, including exactly distributed statistics derived using the multivariate regression model, significantly over-reject the hypotheses examined.     

Integración económica,crisis económicas y ciclos económicos en México

This article analyzes the peculiarity of the dynamics of economic fluctuations of the Mexican economy, within the framework of its integration with the US and Canada; the article demonstrates how the Mexican economy make endogenous the macroeconomic crises from the USA (2001 and 2007), and how the business cycles of both countries became more aligned to each other. Based on the heterodox economic theory of crises and cycles, we check the “empirical law of economic dynamics” of the Mexican capitalist system according to the logic of the Multiplier-Accelerator theory that allowed us to study the dynamics of business cycles for the period of the study (1993-2013). To do this, we construct and estimate a stationary VAR model and utilize the Granger causality tests and quarterly data.     

Theoretical considerations on the proposed of recovery of purchasing power of the minimum wage in Mexico

Regarding the recent proposal made by the Mexico City Government about the recovery of the purchasing power of the minimum wage, some reflections on the theories of production and distribution are proposed. We first review the seminal paper written by Cobb and Douglas (1928). Some obstacles in measuring the marginal factor products, and a pair of inconsistencies between the theories of production and distribution on the one hand, and some exercises of quantifying “productivities” on the other hand, are presented. Finally, a model of imperfect competition, which displays the dispute over income between economic agents, is included. One conclusion is that income distribution does not follow a simple rule, but a bargaining process based on market power in a historical context that provides inertia and in which institutions play a key role.     

Influence of information systems on organizational results

In recent years, information systems (IS) comprise one of the main fields of study in business organization, caused by the need to identify their business value. Therefore, in this research and based on a theoretical review, a model is developed for the evaluation of the success of the IS for small and medium enterprises (SME) to determine the influence of the IS in the organizational results. To reach this goal, the Partial Least Squares (PLS) statistical technique was used through a survey made to 133 companies of Tamaulipas state, Mexico. The results obtained allow deducing that the companies that pay more attention on improving the quality of the system, of the information, and of the information systems, favor their organizational results. This work contributes to the literature on the measurement of the success of the IS in the context of a country with an emerging economy, particularly by allowing to identify in a broader manner the measurement of its effectiveness and its incidence in the business performance.     

Effect of information quality due accounting regulatory changes: Applied case to Mexican real sector

The purpose of this paper is to examine whether changes in accounting standards improve value relevance of financial information on listed companies in Mexico. The research was conducted for the period 2000–2013 using a sample of 141 companies that report to the Mexican stock exchange using the methodology of panel data. Our findings show that changes in local regulations (generally accepted accounting principles) to internationally approved standards (Financial Reporting Standards and International Financial Reporting Standards) increase the value relevance and therefore the quality of information. The study shows that the accounting information with international Financial Reporting Standards is more trustworthy for foreign and national investors.     

浅析802.11n走向无线前端的瓶颈

针对802.11n设备从技术角度分析其广泛推广全面应用所遇到的瓶颈,就目前来说这些困难或多或少被厂商或管理人员通过多种方法弱化甚至化解。很多困难的排除已经不再复杂,这些都预示着11n技术离广泛应用越来越近。     

S频段RDSS业务全球扩展分析

随着全球卫星导航系统（GNSS）的发展,现有的卫星无线电导航频率划分已无法满足日益增 长的需求。根据ITU规则,S频段2 483.5～2 500 MHz频率范围在部分区域和部分国家为卫星 无线电测定服务（RDSS）业 务的首要分配,且该频率范围与地面移动通信服务2.5 GHz以上的频率范围接近,易于实现 导航 系统与移动通信系统实现硬件复用,使得该频段受到欧盟“伽利略”系统的重视,并提出了 RDSS 业务全球扩展的议题。在简要介绍S频段RDSS业务全球扩展背景的基础上,分析了S频段 RDSS业务全球扩展的可行性,并针对我国S频段RDSS业务的使用情况和卫星导航系统频率资 源占有情况,分析了我国开展S频段RDSS业务全球扩展研究的必要性,基于频率和轨位申报 的需求,提出了需要研究的内容。     

The complex reality of biodiversity conservation through Natural Protected Area policy: Three cases from the Yucatan Peninsula,Mexico

The federal policy of Natural Protected Areas has become the main instrument for conserving biodiversity in Mexico. Established in territories representative of different ecosystems but also of cultural diversity, protected areas in Mexico have historically been created and managed with a centralized rationale, creating several conflicts with local communities over the use of natural resources. The country's approach to protected areas perfectly illustrates the complexities, difficulties and challenges entailed in biodiversity conservation. This paper develops a critical analysis of this policy instrument in Mexico, and analyzes three Natural Protected Areas in the Yucatan Peninsula: The Calakmul Biosphere Reserve, the Celestún Biosphere Reserve, and the Otoch Ma’ax Yetel Kooh Natural Protected Area. The case studies serve as examples of the most common difficulties that arise in Mexican Natural Protected Area policy: (1) uncoordinated public policies; (2) the usual conflict between environmental authorities and local people over the management of natural resources; and (3) the exclusion of local people's perspectives, values and beliefs in conservation policy development and implementation.     

采用矢量网络分析的超宽带脉冲传播特性测量方法

介绍了一种采用矢量网络分析对超宽带脉冲传播特性进行测量的方法。首先通过测 量,得到收发天线之间环路的频域响应;然后设计合适的激励脉冲波形,通过傅里叶变换至 频域,经过一系列算法处理,得到接收信号的频域函数;最后经过傅里叶逆变换,恢复出超 宽带信号时域波形。研究了这种方法的基本流程,解决了实际应用中存在的一些问题,并在 此基础上构建了测试系统。对超宽带信号的直线传播和反射进行了测试,测试结果验证了该 方法的有效性及其优势。