Nuclear forensics using gamma-ray spectroscopy

Much of George Dracoulis's research career was devoted to utilizing gamma-ray spectroscopy in fundamental studies in nuclear physics. This same technology is useful in a wide range of applications in the area of nuclear forensics. Over the past several years, our research group has made use of both high- and low- resolution gamma ray spectrometers to: identify the first sample of plutonium large enough to be weighed; determine the yield of the Trinity nuclear explosion; measure fission fragment yields as a function of target nucleus and neutron energy; and observe fallout in the U. S. from the Fukushima nuclear reactor accident.Comment: 3 pages; 7 figures; conference proceedin

Let's Get "Real" About Using Economic Data

Breeden, Gibbons and Litzenberger (1989), and Lamont (1999), use "economic tracking portfolios" to forecast macroeconomic data. Tracking portfolios are constructed to reflect market expectations and reveal the impact of news. However, these papers, as well as many related studies which examine the market impact of macroeconomic news, use "currently available" macroeconomic data. The combination of various different "vintages" of economic data has several important and undesirable consequences, particularly when the timing of information and its impact on financial markets is the focus of investigation. We therefore use a real-time macroeconomic data set to accurately mimic the accumulation of macroeconomic information in real time. We attempt to shed new light on the methodology used to construct tracking portfolios, as well as on the impact of macroeconomic news on financial markets. In addition, we address a number of related questions, including: Does the data revision process itself have an impact on financial markets? Do market participants: (i) care about "final" releases of macroeconomic variables; or (ii) form their decisions based on preliminary data; or (iii) instead form their decisions by using vintages of data which they assume correspond to those vintages used by public policy decision-makers?

Let's Get "Real" about Using Economic Data

We show that using data which are properly available in real time when assessing the sensitivity of asset prices to economic news leads to different empirical findings that when data availability and timing issues are ignored. We do this by focusing on a particular example, namely Chen, Roll and Ross (1986), and examine whether innovations to economic variables can be viewed as risks that are rewarded in asset markets. Our findings support the view that data uncertainty is sufficiently prevalent to warrant careful use of real-time data when forming real-time news measures, and in general when undertaking empirical financial investigations involving macroeconomic data. Nous démontrons que l'utilisation de données qui sont disponibles en temps réel pour établir la sensibilité des prix d'actifs aux nouvelles économiques mène à des résultats empiriques différents de ceux obtenus lorsque la disponibilité des données et les considérations temporelles ne sont pas prises en compte. Pour ce faire, nous nous concentrons sur un exemple en particulier, c'est-à-dire Chen, Roll et Ross (1986), et nous regardons si les innovations aux variables économiques peuvent être perçues comme étant des risques qui sont récompensés dans les marchés des actifs. Nos résultats entérinent la présomption que l'incertitude des données est suffisamment prévalente pour assurer une utilisation prudente des données en temps réel lors de l'établissement de mesures de nouvelles en temps réel, et en général lorsqu'on entreprend des enquêtes financières empiriques impliquant des données macroéconomiques.Market efficiency, expectations, news, data revision process, Efficacité des marchés, attentes, nouvelles, processus de révision des données

Let's Get "Real" about Using Economic Data.

We show that using data which are properly available in real time when assessing the sensitivity of asset prices to economic news leads to different empirical findings than when data availability and timing issues are ignored. We do this by focusing on a particular example, namely Chen, Roll and Ross (1986), and examine whether innovations to economic variables can be viewed as risks that are rewarded in asset markets. Our findings support the view that data uncertainty is sufficiently prevalent to warrant careful use of real-time data when forming real-time news measures, and in general when undertaking empirical financial investigations involving macroeconomic data.

Observations of Fallout from the Fukushima Reactor Accident in San Francisco Bay Area Rainwater

We have observed fallout from the recent Fukushima Dai-ichi reactor accident in samples of rainwater collected in the San Francisco Bay area. Gamma ray spectra measured from these samples show clear evidence of fission products - 131,132I, 132Te, and 134,137Cs. The activity levels we have measured for these isotopes are very low and pose no health risk to the public.Comment: 5 pages, 2 figure

Electrocardiography in idiopathic hypercalcaemia and other cation disorders of childhood

Electrocardiograms of 100 healthy infants aged from 2 weeks to 12 months were recorded and analysed in order to provide standard measurements for comparison with those made in electrocardiograms of infants suffering from idiopathic hypercalcaemia and other disorders of cation balance. The conclusions of this investigation may he summarized as follows:- 1. The heart rate falls as age increases. The rate lay between 207 and 102 per minute in this series. 2. The P wave, PR interval, QRS complex and T wave lengthen as age increases, independently of heart rate. 3. The PR interval, QRS complex and T wave lengthen as the heart rate falls, independently of age. 4. The ST segment shortens as age increases, and lengthens as the heart rate falls. 5. The QT interval lengthens as the heart rate falls. The influence of heart rate is so profound that it is necessary to apply a correction to the measured QT interval to permit comparisons between QT intervals recorded at different heart rates. The corrected QT interval is referred to as the QTc value. 6. Time intervals in this series of healthy infants have the following minimum and maximum values: P wave = 0.04-0.08 second; T wave = 0.09-0.15 second; PR interval = 0.08-0.14 second; ST segment = 0.05-0.11 second; QRS complex = 0.05-0.08 second; QT interval = 0.21-0.29 second; QTc value = 0.36-0.42. Electrocardiograms of 25 patients with idiopathic hypercalcaemia were recorded. Certain features were compared with those of healthy subjects, and with those of 3 newborn infants with hypercalcaemia caused by the injection of calcium gluconate during replacement transfusion. The conclusions of this investigation may be summarized as follows:- 1 . Newborn infants with hypercalcaemia have a shortened ST segment and a decrease in the QTc value. 2. In patients with idiopathic hypercalcaemia, hypercalcaemia is accompanied by a shortened ST segment, but not by a decrease in the QTc value because of the undue length of the T wave. The QTc value cannot therefore be used to give an indication of the serum calcium level. 3 . In idiopathic hypercalcaemia the contour of the ST-T complex is often abnormal with a prominent broad flat-topped T wave, which is not directly related to the level of serum calcium. 4. The abnormal contour of the ST-T complex in idiopathic hypercalcaemia may reflect interference with myocardial activity either by a heart lesion caused by vitamin D, or by the action of a chemical substance associated with it. An animal experiment was conducted in order to gain information concerning heart lesions caused by vitamin D. Vitamin and vitamin D[3] were each given to 9 young rabbits and there were 9 controls. A study was made of the pathological changes in the heart and aorta. The conclusions of this investigation may be summarized as follows:- 1. Aortic lesions, found in every rabbit given vitamin D, are accepted as evidence of the toxicity of the doses given. 2. Of the heart lesions caused by vitamin D, lesions immediately subjacent to the endocardium apparently occur most frequently, focal lesions of the myocardium less frequently and coronary artery lesions least frequently. 3. Vitamin D[2] is at least as toxic to the heart as vitamin D[3] and may be more so. 4. It was not found possible to assess the prognosis of these heart lesions, and their ultimate effect, if any, on heart function, but myocardial and coronary artery lesions such as these could account for the electrocardiographic changes in idiopathic hypercalcaemia. 5. Myocardial and coronary artery lesions are unlikely to be caused by the usual prophylactic doses of vitamin D unless the vitamin were to exert a cumulative effect by such a mechanism as has been postulated in idiopathic hypercalcaemia of infancy. 6. Detailed histological examination of the heart of infants dying in the course of idiopathic hypercalcaemia is an important requirement