Existence of the solution of Szebehely's equation in three dimensions using a two-parametric family of orbits

The three-dimensional inverse problem is investigated. A quasi-linear system of partial differential equations is derived for the determination of the potential. The solution of this system is studied by a method of differential geometry. A necessary condition for the solution is derived and the determination of the potential is reduced to algebraic equations written in vectorial form. A few examples are also given.     

THE USE OF A CROSS-CORRELATION TECHNIQUE TO ENHANCE JANSSON''S DECONVOLUTION PROCEDURE

The use of a cross-correlation prefiltering technique to enhance the ability of Jansson's iterativedeconvolution procedure to deconvolve extremely noisy chromatographic data is investigated.Test casesinclude peaks whose resolutions are as low as 0.35 and whose signal-to-noise ratios are as low as 1:1.Evaluation criteria include RMS error,relative peak error and peak area repeatability.For comparisonpurposes,relative peak area errors and peak area variances are also evaluated for noisy but well resolvedpeaks that have only been prefiltered with the cross-correlation filter.Jansson's method in conjunctionwith cross-correlation prefiltering is shown not only to resolve overlapped peaks but in some cases toimprove their signal-to-noise ratios.The study also establishes some limits to the capabilities of Jansson'smethod will regard to adverse data conditions.     

Long periodic perturbations of Trojan asteroids

The motion of the Trojan asteroids is studied in the elliptic restricted three-body problem of the Sun-Jupiter-asteroid system. Long periodic perturbations of the orbital elements are discussed. Relations between dynamical parameters are considered and comparisons are made with Bien's and Schubart's results.     

Risk management tools for sustainable fisheries management under changing climate: a sea cucumber example

Sustainable fisheries management into the future will require both understanding of and adaptation to climate change. A risk management approach is appropriate due to uncertainty in climate projections and the responses of target species. Management strategy evaluation (MSE) can underpin and support effective risk management. Climate change impacts are likely to differ by species and spatially. We use a spatial MSE applied to a multi-species data-poor sea cucumber/béche-de-mer fishery to demonstrate the utility of MSE to test the performance of alternative harvest strategies in meeting fishery objectives; this includes the ability to manage through climate variability and change, and meeting management objectives pertaining to resource status and fishery economic performance. The impacts of fishing relative to the impacts of climate change are distinguished by comparing future projection distributions relative to equivalent no-fishing no-climate-change trials. The 8 modelled species exhibit different responses to environmental variability and have different economic value. Status quo management would result in half the species falling below target levels, moderate risks of overall and local depletion, and significant changes in species composition. The three simple strategies with no monitoring (spatial rotation, closed areas, multi-species composition) were all successful in reducing these risks, but with fairly substantial decreases in the average profit. Higher profits (for the same risk levels) could only be achieved with strategies that included monitoring and hence adaptive management. Spatial management approaches based on adaptive feedback performed best overall.     

Petrology and Mineralogy of Eclogite and Garnet Amphibolite from Puerto Cabello, Venezuela

Occurrences of eclogite, eclogite-amphibolite, and garnet amphibolitefrom Puerto Cabello, Venezuela are described. Chemical analysesof thirteen rocks, eight garnets, six clinopyroxenes, and nineamphiboles are presented. Field evidence shows that the eclogitesand associated mafic rocks occur as sheets or lenses conformablewith pelitic and calcareous rocks and have been metamorphosedin situ. The associated country rocks have attained a metamorphicmineral assemblage typical of the epidote-amphibolite facies.The chemical composition of the eclogite and associated rocksis variable but is essentially that of tholeiitic basalt. Clino-pyroxenesfrom the eclogites are omphacites containing 34–51 moleper cent jadeite and the remainder largely diopside; coexistinggarnets contain approximately 50 mole per cent almandine, 24mole per cent pyrope, 25 mole per cent grossular+andradite,and 1 mole per cent spessartine. Determinations for the temperatureof metamorphism of these rocks give approximately 525±50°C. Determinations of total pressure of metamorphism, basedon the jadeite content of omphacite, on glaucophane II, kyanite,and calcite stability fields, and on stratigraphic reconstructionsgive a range of values between 5 and 10 kb with a most probablevalue near 7 kb. These data suggest a moderate geothermal gradientduring metamorphism of approximately 20 °C/km. An evaluationof the role of volatiles during metamorphism indicates thatthe original basalts were converted to eclogites in an environmentclosed to water and carbon dioxide. The field relationshipsat Puerto Cabello demonstrate the general instability of eclogite;the great majority of mafic rocks are amphibolites, garnet amphibolites,and eclogite-amphibolites. Eclogites, sensu stricto, are preservedonly in random ‘dry’ pockets within the stratigraphicsection containing the metabasalts. The transformation of basaltto eclogite to amphibolite is considered to have been a continuousparagenetic sequence during a single pseriod of metamorphism.