Synchronous demodulator

A synchronous demodulator includes a switch which is operated in synchronism with an incoming periodic signal and both divides and applies that signal to two signal channels. The two channels each include a network for computing and holding, for a predetermined length of time, the average signal value on that channel and applies those valves, in the form of two other signals, to the inputs of a differential amplifier. The networks may be R-C networks. The output of the differential amplifier may or may not form the output of the synchronous detector and may or may not be filtered. The output will not include a periodic signal due to the presence of a dc offset. Additionally, the output will not contain any substantial ripple due to periodic components in the input signal. In a somewhat more complex version, containing twice the structural components of the above synchronous demodulator with a more complex switching mechanism, essentially all ripple due to periodic components in the input signal are eliminated

The Variance of Firm Growth Rates: The Scaling Puzzle

Certain recently reported statistical regularities relating to the dispersion of firms' growth rates have begun to attract attention among IO economists. These relationships take the form of power law or scaling relationships and this has led to suggestions that the underlying mechanisms which drive these relationships may have some interesting analogies with the mechanisms which drive scaling relationships in other fields. In particular, it has led to suggestions that there may be some subtle correlations among the growth rates of the different constituent businesses that comprise the firm.In this paper, I report some new empirical evidence in this area and I put forward a new candidate explanation for the relationships we observe. This candidate explanation does not rely on any correlation mechanisms; rather, it is consistent with the view that the typical firm consists of a number of (approximately) independent businesses. The size distribution of the constituent businesses within firms is modelled by reference to an analogy with the partitions of an integer.Firm growth, power law, scaling relationships.

Symposium on Marshall's tendencies: a reply.

In her opening contribution to this symposium, Mary Morgan has provided a critical evaluation of Marshall's Tendencies in which she reviews a series of methodological issues. She characterizes my views quite accurately, while pinpointing the gaps in my account (most notably in relation to pinning down what is meant by a ‘mechanism’). I am therefore going to leave this aspect of things on one side, and turn to other matters.

A Hidden Resource: Household-led Rural Water Supply in Ethiopia

Self supply as a strategy for WASH is defined as "improvement to water supplies delivered largely or wholly through user investment usually at household level." The two research studies reported on in this paper examined self supply in rural Ethiopia, gaining insights on the performance of existing family wells, factors that affect the decision of families to build their own wells and the way they use them, and elements of the enabling environment that can be targeted to promote self supply

Classical electron mass and fields 2

Continued here is the development of a model of the electron (HYDRA), which includes rotational and magnetic terms. The atomic electron state is discussed and a comparison is made with a simple harmonic oscillator. Experimental data is reviewed that supports the possibility of a new lepton

Land Grant Application- Sutton, John (Limington)

Land grant application submitted to the Maine Land Office on behalf of John Sutton for service in the Revolutionary War, by their widow Lois.https://digitalmaine.com/revolutionary_war_me_land_office/1876/thumbnail.jp

Income, Income Inequality and Health: What can we Learn from Aggregate Data?

It has been suggested that, especially in countries with high per capita income, there is an independent effect of income distribution on the health of individuals. One source of evidence in support of this relative income hypothesis are analyses of aggregate cross section data on population health, per capita income and income inequality. We examine the empirical robustness of cross-section analyses by using a new data set to replicate and extend the approach in a frequently cited paper. We find that the estimated relationship between income inequality and life expectancy is dependent on the data set used, the functional form estimated and the way in which the epidemiological transition is specifed. The association is never significant in any of our models. We argue there are serious methodological difficulties in using aggregate cross sections as means of testing hypotheses about the effect of income, and its distribution, on the health of individuals.

Scaffolding Memory: themes, taxonomies, puzzles

Through a selective historical, theoretical, and critical survey of the uses of the concept of scaffolding over the past 30 years, this chapter traces the development of the concept across developmental psychology, educational theory, and cognitive anthropology, and its place in the interdisciplinary field of distributed cognition from the 1990s. Offering a big-picture overview of the uses of the notion of scaffolding, it suggests three ways to taxonomise forms of scaffolding, and addresses the possible criticism that the metaphor of scaffolding retains an overly individualist vision of cognition. The chapter is aimed at a broad interdisciplinary audience interested in processes of learning, teaching, and apprenticeship as they apply to the study of memory