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Australian workers have been interested for some time in the common Ceroplastes on coffee in Kenya as a source from which parasites of Ceroplastes destructor Newst. might be obtained.The doubt that more than one white waxy scale occurs on coffee in East Africa led to an examination of material of C. destructor and certain other allied species. It was found that C. destructor was present in Uganda and Kenya but did not occur on coffee in Kenya, so far as is known at present. C. brevicauda Hall, here raised to specific rank, was found to occur on coffee in Uganda and a new species, C. luteolus, on the same crop in Kenya.Descriptions of C. luteolus, Lecaniodiaspis erratica and Pseudococcus latipes, spp. n., all from coffee, are given.

Summary In this paper are reviewed the status and composition of some genera, and the identity of some non-African wax scales. Points of interest on other wax and soft scales which came to light in the course of the main study, are also discussed.

A computer program is here presented which deals with mathematical models of the urban world. The paper is the resume of the research the authors are doing at the Politecnico di Milano about the interaction between the man and the computer in urban planning.

The true identity of the specimens from Africa recorded as Coccus africanus (Newst.) and C. viridis (Green) is reviewed in detail. Four other species of green scales attacking coffee in Africa south of the Sahara are described as new. These are: C. alpinus—for more than 40 years confused with africanus—C. celatus, C. consimilis and C. viridulus.

In a previous paper, the authors have described an automatic scanning system, and a computer program (ASINI 1) to test the system on simulated data. A second version of the program has been written (ASINI 2) which embodies more sophisticated tracking techniques. Furthermore, simulated photographs in ASINI 2 have dimensions approaching those of real photographs. Experimental results are discussed, and the limitations of the present program in automatic scanning of real photographs are pointed out.

Starting from the theory of linear time invariant filters for optimum processing of the amplitude of single pulses, an ideal time variant system has been synthetized for the analysis of a sequence of random pulses and its performance has been evaluated. Demonstration is given that the system is the optimum one under the hypothesis of gaussian noise and taking as criterion for the evaluation of amplitude resolution the rms deviation.

A very fast pulse amplitude-to-digital converter has been realized connecting a sampling height-to-time converter to a digital time sorter. Very good differential linearity and encoding accuracy have been obtained with an equivalent cloc frequency of some GHz.

Si trattano i problemi incontrati nella transistorizzazione dell'elettronica nucleare quali risultanti dall'esperienza fatta dagli Autori, le caratteristiche generali di impiego e i vantaggi dei transistori, e le attuali prospettive di sviluppo. Si descrivono brevemente gli apparecchi realizzati.

In this paper, the pile-up amplitude distribution of pulses having the most common shape is studied (single and double RC differentation, single and double delay line differentiation). The pile-up effects on timing circuits are then analyzed, and experimental results are discussed. Finally the effeciency of pile-up rejection circuits is examined in order to design the most suitable ones.

A program for investigating the capabilities of automatic scanning of bubble chamber photographs is described. The program consists of two routines: the first (PHOTO) simulates the operation of a film-reading device; the second (ASINI: Automatic Scanning and Identification of Nuclear Interactions) identifies the tracks on the pictures simulated by PHOTO. Experimental results indicate the possibility of pratical implementation of the proposed recognition method.

The problem of achieving the highest resolution in the amplitude measurement of pulses randomly spaced in time is considered, taking into account both noise and pile-up fluctuations due to slow signal tails. Signals composed by a pulse of finite duration and a long tail, are considered: a measuring technique is introduced, based on a linear combination of sampling measurements on the pulse. It is shown that, by a suitable choice of weights, optimum compromise between noise and tail pile-up effects can be reached, allowing good resolution at high counting rates. Results of calculations are given for the well known finite width cusp pulse and exponential tails.

A systematic review of some species of the Coccid genus Saissetia occurring in East Africa led to the rediscovery of two species—S. persimilis (Newst.) and S. somereni (Newst.)—which although of economic importance have been almost completely neglected since they were first described. Both are redescribed in this paper. One new species recently collected in Kenya is described; this is S. pterolobina.Seven species are dealt with in the paper, including the important and widely distributed S. oleae (Bern.). A provisional key for their separation is included, while one species—S. cuneiformis Leonardi—is sunk as a synonym of S. nigra (Nietn.).

A controlled clinical trial comparing streptokinase plus heparin with heparin alone in acute myocardial infarction of less than 12 hours' duration has been conducted in three hospitals in Italy. All the patients were managed in coronary-care units with continuous electrocardiographic monitoring and intensive medical and nursing care. On admission the patients were randomly allocated to heparin or to streptokinase—both drugs being given in standard doses. 321 patients were included in the trial, and survivors were followed up for 40 days; 164 were treated with streptokinase and 157 formed the control group. The total mortality in the streptokinase group was 19 patients (11·6%) and in the control group 18 (11·5%). The frequency of heart-failure, shock, arrhythmias, and non-transmural infarctions did not differ significantly between the two treatment groups. These results do not suggest that streptokinase therapy would reduce the morbidity and the mortality in patients with acute myocardial infarction treated in coronary-care units with the dosage and selection of cases used in this trial.

Equations for the effects of the quantization on the mean value and the variance of a random variable are presented for some usual channel profiles in nuclear instrumentation.

A method is presented to smooth a noisy waveform by introducing a correlation between adjacent channels dependent of the channel number.