Power spectrum analysis of the light curve of RR Tauri

Power spectrum analysis is applied to the light curve of RR Tauri. Periodicities are found at 80, 200 and 533 days with some variation in the peak positions and power for different decades. Factors involved in the classification of the variable are discussed.Receipt delayed by postal strike in Great Britain.     

Book Review

Electronic Surveying and Navigation by Simon H. Laurila (New York: John Wiley &; Sons, 1976), 545 pages, hardcover, $25.00.     

Predicting spectral features in galaxy spectra from broad-band photometry

We explore the prospects of predicting emission-line features present in galaxy spectra given broad-band photometry alone. There is a general consent that colours, and spectral features, most notably the 4000 Å break, can predict many properties of galaxies, including star formation rates and hence they could infer some of the line properties. We argue that these techniques have great prospects in helping us understand line emission in extragalactic objects and might speed up future galaxy redshift surveys if they are to target emission-line objects only. We use two independent methods, Artificial Neural Networks (based on the ANNz code) and Locally Weighted Regression (LWR), to retrieve correlations present in the colour N -dimensional space and to predict the equivalent widths present in the corresponding spectra. We also investigate how well it is possible to separate galaxies with and without lines from broad-band photometry only. We find, unsurprisingly, that recombination lines can be well predicted by galaxy colours. However, among collisional lines some can and some cannot be predicted well from galaxy colours alone, without any further redshift information. We also use our techniques to estimate how much information contained in spectral diagnostic diagrams can be recovered from broad-band photometry alone. We find that it is possible to classify active galactic nuclei and star formation objects relatively well using colours only. We suggest that this technique could be used to considerably improve redshift surveys such as the upcoming Fibre Multi Object Spectrograph (FMOS) survey and the planned Wide Field Multi Object Spectrograph (WFMOS) survey.     

The effects of land tenure on vulnerability to droughts in Northeastern Brazil

This article presents evidence on two distinct farming systems—one that utilizes common property pasturelands and another based on private pasturelands—in the Brazilian semi-arid zone. The research is based on a survey carried out in the state of Bahia in 2002. A bivariate analysis was carried out to compare agricultural outputs and income generated in each system. Data suggest that there are no significant differences between the two groups concerning income generation. However, farmers using common pasturelands have more diversified systems and invest more on small-animal husbandry, which are adapted to the dry environment. As a consequence, families that use common pasturelands have a higher consumption of animal protein. These families are thus not necessarily more vulnerable to droughts than those with private pasturelands. Formulating effective institutions to control access to the commons is a strategy pursued by some communities, yet, their ecological sustainability is still unknown.     

Matched field processing of deep-water ambient noise

Matched-field ambiguity surfaces produced by deep-water ambient-noise data are discussed and quantified in terms of power levels and correlation values. Two processors were implemented (Bartlett and minimum variance) using data at 35 and 95 Hz with similar but distinct vertical angular distributions. In general, the ambiguity surfaces have both diffuse and discrete components. The diffuse distribution extends across the sound channel with correlation values increasing with distance. The discrete sources have higher correlation values and are distributed in a convergence-zone sidelobe structure. Local wind conditions appear to affect the received power but not the correlation values or the processor output power     

Problems and perspectives of the current Berlin settlement

Since the implementation of the Quadripartite Agreement in June 1972, Berlin has entered a new phase in East-West relations. Once a city of perpetual crisis, it has now become accustomed to the pleasant effects of détente. Through the establishment of many practical improvements, the life of Berliners has become easier and the city has been defused of much of its explosive potential. Nevertheless, if Berlin no longer appears to serve as a major flash point of international tension, serious unresolved problems remain. It is the point of this investigation to examine the most important areas of conflict, showing what trends have developed and what actions and counteractions can be expected in the future. The major underlying hypothesis of this study is that one may be skeptical of any conclusion that we have seen the last of the “Berlin crises”.     

Sufficient conditions for escape in the three-body problem

Sufficient conditions are given for the escape of a member of a three-body system. The set of conditions are similar to those given previously by Tevzadze (1962). The new set compares favorably in most cases with that of Tevzadze.