Frequency shift keyed demodulator Patent

Frequency shift keyed demodulator - circuit diagram

Political dimensions of demographic change: an address

The title of this conference, "Seismic Shifts: The Economic Impact of Demographic Change," might suggest that economic "earthquakes" lie ahead, but while the metaphor is geological, I do not think it was intended to be catastrophically geological. In fact, it is quite appropriate to visualize the demographic trends that we see under way as a kind of "human tectonics"... Of course, geological time spans centuries, millennia, millions of years. By these standards, demographic change that takes place over decades is quite rapid. Yet, by the standards of economic change, demographic change is very slow, gradual, even stately. ; If we embrace the imagery of demography as human tectonics, demographic trends--if left unattended--could produce earthquakes, and such a possibility has given rise to a number of nightmare fantasies. But enough of this geology. ; What I propose to do is to highlight some of the fantasies, often political in purpose, and the empirical facts, and then to tell you what political policy responses might emerge from careful analysis of those facts--responses that are politically difficult and perhaps painful, but less alarming and draconian than those that have been widely promoted by the fantasies.Demography ; Economic conditions

La dépopulation : science et politique

Quatre thèmes sont développés dans cet article, à savoir : que le débat sur la dépopulation est dominé par la confusion au niveau des sens du mot et au niveau des causes, conséquences et mesures à prendre; que la question de la dépopulation est étroitement liée aux idéologies politiques et aux valeurs culturelles; que les données et les méthodes démographiques, ainsi que certains démographes éminents, ont joué un rôle considérable dans ce débat; que l’avenir de la fécondité est plus impénétrable que jamais, de sorte que la pertinence des inquiétudes sur la dépopulation n’est pas évidente.This paper is structured around four propositions about population decline: (1) discussions about population decline have been plagued with confusion about the very meaning of the topic, as well as about causes, consequences and policy measures; (2) the issue is closely tied to political ideologies and cultural values; (3) demographic data and methods, and some prominent demographers, have played central roles in the debate; (4) the future of fertility is even murkier than usual, and therefore the legitimacy of concerns about population decline is not obvious.Cuatro temas son desarrollados en este artículo, a saber: 1) el debate sobre la despoblación está dominado por la confusión tanto en su significado como en sus causas, consecuencias y medidas a tomar; 2) la cuestión de la despoblación esta estrechamente ligada a ideologías políticas y a valores culturales; 3) los datos y métodos demográficos, así como algunos eminentes demógrafos han jugado un role importante en este debate; 4) el porvenir de la fecundidad es cada vez más impenetrable y la pertinencia de las inquietudes sobre la despoblación no es evidente

Effect of helicity and rotation on the free decay of turbulent flows

The self-similar decay of energy in a turbulent flow is studied in direct numerical simulations with and without rotation. Two initial conditions are considered: one non-helical (mirror-symmetric), and one with maximal helicity. The results show that, while in the absence of rotation the energy in the helical and non-helical cases decays with the same rate, in rotating flows the helicity content has a major impact on the decay rate. These differences are associated with differences in the energy and helicity cascades when rotation is present. Properties of the structures that arise in the flow at late times in each time are also discussed.Comment: 4 pages, 4 figure

The microscopic nature of localization in the quantum Hall effect

The quantum Hall effect arises from the interplay between localized and extended states that form when electrons, confined to two dimensions, are subject to a perpendicular magnetic field. The effect involves exact quantization of all the electronic transport properties due to particle localization. In the conventional theory of the quantum Hall effect, strong-field localization is associated with a single-particle drift motion of electrons along contours of constant disorder potential. Transport experiments that probe the extended states in the transition regions between quantum Hall phases have been used to test both the theory and its implications for quantum Hall phase transitions. Although several experiments on highly disordered samples have affirmed the validity of the single-particle picture, other experiments and some recent theories have found deviations from the predicted universal behaviour. Here we use a scanning single-electron transistor to probe the individual localized states, which we find to be strikingly different from the predictions of single-particle theory. The states are mainly determined by Coulomb interactions, and appear only when quantization of kinetic energy limits the screening ability of electrons. We conclude that the quantum Hall effect has a greater diversity of regimes and phase transitions than predicted by the single-particle framework. Our experiments suggest a unified picture of localization in which the single-particle model is valid only in the limit of strong disorder

The decay of turbulence in rotating flows

We present a parametric space study of the decay of turbulence in rotating flows combining direct numerical simulations, large eddy simulations, and phenomenological theory. Several cases are considered: (1) the effect of varying the characteristic scale of the initial conditions when compared with the size of the box, to mimic "bounded" and "unbounded" flows; (2) the effect of helicity (correlation between the velocity and vorticity); (3) the effect of Rossby and Reynolds numbers; and (4) the effect of anisotropy in the initial conditions. Initial conditions include the Taylor-Green vortex, the Arn'old-Beltrami-Childress flow, and random flows with large-scale energy spectrum proportional to $k^4$. The decay laws obtained in the simulations for the energy, helicity, and enstrophy in each case can be explained with phenomenological arguments that separate the decay of two-dimensional from three-dimensional modes, and that take into account the role of helicity and rotation in slowing down the energy decay. The time evolution of the energy spectrum and development of anisotropies in the simulations are also discussed. Finally, the effect of rotation and helicity in the skewness and kurtosis of the flow is considered.Comment: Sections reordered to address comments by referee

Situs inversus totalis in a fetus with a deletion at 7q36.2 detected on microarray analysis

Laterality disorders are a heterogeneous group of disorders associated with maternal diseases (maternal IDDM), maternal exposures to teratogens (retinoic acid), chromosome abnormalities and single gene disorders (ZIC3 mutation). We report on a fetus with a submicroscopic deletion at 7q36.2 with right atrial isomerism (RAI). CASE: The mother was a 30y G4P1SA2L1 and the father was 35y. Both were healthy and non-consanguineous and their family history was non-contributory. They had a healthy son and daughter and had two miscarriages. MSS was negative. Detailed fetal U/S and echocardiography at 20w showed: RAI with ...postprin

U.S. Commission on Immigration Reform

The U.S. Commission on Immigration Reform was created by Congress to assess U.S. immigration policy and make recommendations regarding its implementation and effects. Mandated in the Immigration Act of 1990 to submit an interim report in 1994 and a final report in 1997, the Commission has undertaken public hearings, fact-finding missions, and expert consultations to identify the major immigration-related issues facing the United States today.LBJ School of Public Affair

The decay of Batchelor and Saffman rotating turbulence

The decay rate of isotropic and homogeneous turbulence is known to be affected by the large-scale spectrum of the initial perturbations, associated with at least two cannonical self-preserving solutions of the von K\'arm\'an-Howarth equation: the so-called Batchelor and Saffman spectra. The effect of long-range correlations in the decay of anisotropic flows is less clear, and recently it has been proposed that the decay rate of rotating turbulence may be independent of the large-scale spectrum of the initial perturbations. We analyze numerical simulations of freely decaying rotating turbulence with initial energy spectra $\sim k^4$ (Batchelor turbulence) and $\sim k^2$ (Saffman turbulence) and show that, while a self-similar decay cannot be identified for the total energy, the decay is indeed affected by long-range correlations. The decay of two-dimensional and three-dimensional modes follows distinct power laws in each case, which are consistent with predictions derived from the anisotropic von K\'arm\'an-Howarth equation, and with conservation of anisotropic integral quantities by the flow evolution