基于AT89S52及DS18B20温度采集系统设计

文章介绍利用数字式温度传感器DS18B20及单片机AT89S52开发简易测温系统,系统设计包括五大部分:主控制器、显示部分、传感器部分、复位部分、时钟电路。整个系统结构简易方便、功耗低、精度高、成本低且稳定性好。     

Broadband penetration and economic growth nexus: evidence from cross-country panel data

This article investigates whether there are Granger causal relationships between broadband penetration, degree of urbanization, foreign direct investment and economic growth using a panel data set covering the G-20 countries for the period 1998–2011. Using our multivariate framework, we first find that all of the variables are cointegrated. Our findings further reveal a network of causal connections between the variables including short-run bidirectional causality between broadband penetration and economic growth among the more developed countries within the G-20. On the other hand, for the developing countries within the G-20, there is evidence of unidirectional causality from economic growth to broadband penetration.     

Does democracy affect taxation and government spending? Evidence from developing countries

Focusing on developing countries in three geographical areas (South-East Asia, Latin America and European Union), we explore the relation between political variables and tax revenue, public spending and their structure. We build a new dataset for the 1990–2005 period with fiscal, political and socio-economic variables. Since democracy is a complex and multidimensional concept, we measure it using two variables, the political strength of democratic institutions, and the protection of civil liberties. We perform three sets of estimates: (i) cross-country pooled OLS regressions with region fixed effects, (ii) country fixed effects regressions and (iii) region specific regressions with country fixed effects. While the first model delivers some significant correlations between political variables and tax items, when controlling for country fixed effects we find that tax revenue and tax composition are in general not significantly correlated with the strength of democratic institutions and the protection of civil liberties. The only exceptions are indirect, trade and property taxes. A similar result applies to public spending, with the exception of defense expenditure. Overall, our findings cast some doubt on the exact public policy channels through which political institutions affect economic development.     

Exports,capabilities, and industrial policy in India

An extensive literature argues that India’s manufacturing sector has underperformed, and that the country has failed to industrialize; in particular, it has failed to take advantage of its labor–abundant comparative advantage. India’s manufacturing sector is smaller as a share of GDP than that of East Asian countries, even after controlling for GDP per capita. Hence, its contribution to overall GDP growth is modest. Without greater participation of the secondary sector, the argument goes, the country will not be able to develop and become a modern economy. Standard arguments blame the “license-permit raj”, the small-scale industrial policy, and the labor laws. All these were part of the industrial policy regime instituted after independence. This regime favored the heavy-machinery subsector. We argue that despite its shortcomings and misallocations, the bias towards machinery, metals, chemicals, and other capital- and skilled labor-intensive products allowed Indian manufacturing to accumulate a wide range of capabilities. We show that India’s manufacturing sector is more diversified and sophisticated than one would expect given the country’s income per capita. This positions India well to continue expanding its exports of other sophisticated products. India’s failure, however, lies in not being able to diversify into labor-intensive sectors and generate the type of structural transformation seen in China.     

The effects of birth weight: Does fetal origin really matter for long-run outcomes?

This paper investigates whether birth weight itself causes individuals’ future life chances. By using a sample of twins in Japan and controlling for the potential effects of genes and family backgrounds, we examine the effect of birth weight on later educational and economic outcomes. The most important finding is that birth weight has a causal effect on academic achievement around the age of 15, but not on the highest years of schooling and earnings.     

Properties of knowledge base and firm survival: Evidence from a sample of French manufacturing firms

The paper analyzes the effects of the properties of firms' knowledge base on the survival likelihood of firms. Drawing upon the analysis of the patterns of co-occurrence of technological classes in patent applications, we derive the coherence, variety and cognitive distance indexes, accounting respectively for technological complementarity, differentiation and dissimilarity in the firms' patent portfolios. The results of our analysis are in line with the previous literature, showing that innovation enhances the survival likelihood of firms. In addition, we show that the search strategies at work in the development of firms' knowledge base matter in reducing the likelihood of a failure event. Knowledge coherence and variety appear to be positively related to firms' survival, while cognitive distance exerts a negative effect. We conclude that firms able to exploit the accumulated technological competences have more chances to be successful in competing durably in the market arena, and derive some policy implications concerning the role of public intervention in the orientation of search efforts in local contexts.     

Analyst firm parent–subsidiary relationship and conflict of interest: evidence from IPO recommendations

We uncover a new source for the conflict of interest in analyst coverage existed before the Regulation FD period by examining whether recommendations within the parent–subsidiary (PS) relationship are more optimistic and whether they have better investment value than non‐PS recommendations. We find evidence consistent with the conflict of interest: PS analysts on average issue more optimistic recommendations, but their recommendations have worse or no better investment value in the calendar‐time portfolio analysis. Analyst firm PS relationship is another source for the conflict of interest in analyst coverage that has not been identified before.     

A look inside AMLF: What traded and who benefited

The Federal Reserve’s AMLF program was designed to provide liquidity to money market funds (MMFs). Between September 2008 and May 2009, the program made $217 billion in non-recourse loans to depository institutions and bank holding companies to purchase asset-backed commercial paper from MMFs. JP Morgan and State Street dominated the program, accounting for over 90% of all loans made. Our analysis suggests that JP Morgan exhibited more self-dealing behavior than State Street. We find that JP Morgan and State Street earned economically and statistically significant cumulative returns of 2.28% and 2.49% (respectively) over the first seven days of the program after controlling for market returns and heteroscedasticity.     

Institutional quality thresholds and the finance – Growth nexus

Using an innovative threshold estimation technique, this study examines whether the growth effect of financial development in countries with distinct levels of institutional development differs. The results demonstrate that there is a threshold effect in the finance-growth relationship. Specifically, we found that the impact of finance on growth is positive and significant only after a certain threshold level of institutional development has been attained. Until then, the effect of finance on growth is nonexistent. This finding suggests that the financial development-growth nexus is contingent on the level of institutional quality, thus supporting the idea that better finance (i.e., financial markets embedded within a sound institutional framework) is potent in delivering long-run economic development.     

H1N1 – the social costs of élite confusion

In May 2011, the World Health Assembly will receive the report of its International Health Regulations Review Committee examining responses to the outbreak of the 2009 H1N1 pandemic influenza and identifying lessons to be learnt. This will emphasise the need for better risk communication in future. But risk and communication are not objective facts; they are socially mediated cultural products. Responses to crises are not only simply determined by the situation at hand, but also through mental models developed over protracted periods. Accordingly, those responsible for advocating the precautionary approach and encouraging the securitisation of health, that both helped encourage a catastrophist outlook in this instance, are unlikely to be held to account. These élite confusions have come at an enormous cost to society.