While aggregate data do not show the investment echoes predicted by vintage-capital models, echoes arise in rates of entry and exit of firms at the industry level. Moreover, industries where prices decline rapidly experience early ‘shakeouts’. The relation emerges naturally in a vintage-capital model in which exit of firms sometimes accompanies the replacement of their capital, and in which a s...

The echolocating bat, Eptesicus fuscus, perceives the distance to sonar targets from the delay of echoes and the shape of targets from the spectrum of echoes. However, shape is perceived in terms of the target's range proftle. The time separation of echo components from parts of the target located at different distances is reconstructed from the echo spectrum and added to the estimate of absolu...

Automatic detection of severe weather events is of great interest to meteorologists. In this paper, we describe and evaluate a method to identify hook echoes automatically in radar reflectivity data. The method is based on the skeletonization of 2D shapes which are used to describe the shape of storms. We use 4 skeleton shape features: curvature, curve orientation, thickness variation and bound...

In nature, sounds of interest arrive at the eardrums accompanied by echoes that reflect off of surfaces. This superposition can distort the cues by which we localize the source of a sound. Yet, we seem to have no difficulty turning precisely toward the source even in the presence of moderately intense echoes. The article by Devore and colleagues in this issue of Neuron suggests that the auditor...

It is demonstrated that the time evolution of the heteronuclear polarization-transfer process in a dipolar-coupled nuclear spin system can be reversed, leading to the observation of cross-polarization echoes. The cross-polarization echoes are induced by consecutive application of two pulse trains that produce effective Hamiltonians that differ only in sign. Cross-polarization echoes have been r...

A manifesto, signed by a number of Bishops and by the presidents of several religious bodies, has been issued condemning charity lotteries, and particularly lotteries for hospitals. The i sasons given why the Churches "feel that the lottery method for hospitals and philanthropic purposes is a retrograde step"' are that the appeal of the lottery is to the possibility of gain for self?an appeal d...

Speaking on " National Decay and Regeneration" at Edinburgh, the Dean of St. Paul's said that only one kind of natural selection was favoured by modern life?that against disease. That had gone on so rapidly that most of the epidemics which formerly ravaged the cities had assumed a much milder type, and were far less destructive to life. To introduce a savage into any European town was to senten...

Sir Harry Baldwin, Surgeon-Dentist to the King, lecturing before the People's League of Health, drew attention to the chief methods of avoiding the decay of the teeth. These, he insisted, were to ensure an active circulation of blood in the gums by means of a vigorously but discreetly used toothbrush, that need not be of too stiff bristles. Hygiene of the mouth was all important, but he did not...

It will probably come as a surprise to many to read some of the tests set to the children in Council Schools. Those failing to pass them are, we understand, considered to be mentally deficient. A child of four has to discriminate between a ?ircle, a square, a triangle and other mathematical forms. He or she must also draw a square correctly, repeat sentences of twelve or thirteen syllables, and...

We define a quantity, the so-called purity fidelity, which measures the rate of dynamical irreversibility due to decoherence, observed e.g in echo experiments, in the presence of an arbitrary small perturbation of the total (system + environment) Hamiltonian. We derive a linear response formula for the purity fidelity in terms of integrated time correlation functions of the perturbation. Our re...