EMPIRICAL EVALUATION OF EXPECTED RETURNS FROM RESEARCH ON STOCK STRUCTURE FOR DETERMINATION OF TOTAL ALLOWABLE CATCH

An approach to incorporating new information using Bayes' theorem is applied to obtain estimates of expected returns from research on stock structure for determination of total allowable catch (TAC). Expected returns are measured relative to quantitative performance criteria that are inferred from fishery management objectives. Principles of the approach are outlined and a detailed case study of Tasmanian orange roughy is reported.     

Photoionization branching ratios and asymmetry parameters for inner- and outer-valence shells of H2S in the 18–70 eV energy range

Branching ratios, asymmetry parameters and relative partial cross sections have been obtained for photoionization of the outer and the inner valence shells of H₂S. These measurements were made in the photon energy range 18–70 eV using synchrotron radiation. Our results are compared to a set of calculations using a developed extension of the self-consistent field-Xα scattered-wave method to the continuum states. This comparison shows a qualitative agreement between the experimental and calculated β curves of the outer valence shells. The largely predominant sulfur 3p contribution to the outer valence orbitais 2b₁, 5a₁, 2b₂ is revealed in the corresponding β curves by a Cooper minimum also predicted in the same energy range for the β(3p) of the atomic sulfur. This comparison also shows discrepancies in the branching ratios curves and we suggest that this theoretical framework is better adapted to predict photoionization processes in the outer valence shells than in the inner ones.     

An allylation-metathesis sequence as a convergent strategy towards enantiopure equivalents of highly functionalized cyclic dienes

Highly enantioenriched equivalents of cyclic dienes have been readily prepared by asymmetric allylation of unsaturated aldehydes using a chiral allyltitanium reagent, followed by a ring-closing metathesis. The resulting β-hydroxy allylsilanes react stereoselectively with a wide variety of electrophilic reagents.     

A phase space for gravitational radiation

We give a new definition, based on considerations of well-posedness for a certain asymptotic initial value problem, of the phase space for the radiative degrees of freedom of the gravitational field in exact General Relativity. This space fibres over the space of final states, with the fibres being the purely radiative degrees of freedom. The symplectic form is rigorously identified.The infrared sectors are shown to be the level surfaces of a moment map of an action of the quotient group Supertranslations/Translations. A similar result holds for Electromagnetism in Minkowski space.     

The robust shortest path problem in series-parallel multidigraphs with interval data

In this paper the robust shortest path problem in edge series-parallel multidigraphs with interval costs is examined. The maximal regret criterion is applied to calculate the optimal solution. It is shown that this problem is NP-hard. A pseudopolynomial algorithm for the studied problem is constructed.     

The flux of meteoroids in the vicinity of the orbit of Comet Halley

Summary On the basis of simultaneous observations of the Orionid meteor shower in Italy and Czechoslovakia during the period 1978–1982 the flux densities of meteor particles in the near-perihelion distances have been derived and related to previous results of observations of the shower associated with Comet Halley. A maximum flux rate of 2·10⁻¹⁰ m⁻² s⁻¹ has been obtained for the particles of the mass range higher than 10⁻⁶ kg at the distances of (0.09÷0.005) A.U. from the orbit of the comet. The flux in the most inner core of the stream, relative to the particles of the mass range lower than 10⁻⁶ kg, is controlled by the fresh cometary ejecta and hence depends on the mass-loss rate of the of the comet and on its gas/dust relation. The meteor shower observations yield a mass loss rate of solid particles of 3.3·10¹¹kg/revolution. Ths value increases the hazard of the space experiments by more than 1 order of magnitude.

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Riassunto Sulla base di simultanee osservazioni dello sciame meteorico delle Orionidi effettuate in Italia e Cecoslovacchia nel periodo 1978–1982, sono state determinate le densità del flusso delle particelle meteoriche e messe poi in relazione a quelle di precedenti risultati delle osservazioni dello sciame associato alla Cometa Halley. Un valore massimo del flusso pari a 2·10⁻¹⁰ m⁻² s⁻¹ è stato ottenuto per particelle di massa maggiore di 10⁻⁶ kg a distanze di (0.09÷0.005) A.U. dall'orbita della cometa. Il flusso nella parte piú interna della corrente di particelle, relativo a particelle di massa minore di 10⁻⁶ kg, è controllato dai getti freschi di materia cometaria, per cui esso dipende dal coefficiente di perdita di massa della cometa e dalla relazione che intercorre tra gas e polvere cometaria. Le osservazioni degli sciami di meteore forniscono un coefficiente di perdita di massa di particelle solide pari a 3.3·10¹¹ kg per ogni rivoluzione. Questo valore accresce di piú di un ordine di grandezza il rischio connesso ad esperimenti spaziali.

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Резюме На основе одновременных наблюдений метеора Орионида в Италии и Чехословакии в период 1978–1982 г.г., определены плотности потоков метеорных частиц на расстояниях вблизи перигелия кометы Галлея, а также установлена связя с предыдущими резулятатами по наблюдению ливней, связанных с кометой Галлея. Получена максимальная величина потока 2·10⁻¹⁰ м⁻¹ с⁻¹ для частиц с массами более 10⁻⁶ кг на расстояниях (0.09÷0.005) аед. от орбиты кометы. Поток в самой внутренней части течения частиц, по отношению к частицам с массой меньшей 10⁻⁶ кг, контролируется свежими выбросами вещества кометы и, следовательно, зависит от скорости потери массы кометой и от отношения ?газ/пыль? для вещества кометы. Наблюдения метеорных ливней дают значение скорости потери массы для твердых частиц 3.3·10¹¹ кг/оборот. Эта величина увеличивает риск космических экспериментов более чем на порядок.