Niches of marine mammals in the European Arctic

The Arctic is warming rapidly, with concomitant sea ice losses and ecosystem changes. The animals most vulnerable to Arctic food web changes are long-lived and slow-growing such as marine mammals, which may not be able to adapt rapidly enough to respond to changes in their resource bases. To determine the current extent and sources of these resource bases, we examined isotopic and trophic niches for marine mammals in the European Arctic using skin carbon (δ13C) and nitrogen (δ 15N) stable isotope (SI) compositions from 10 species: blue, fin, humpback, minke, sperm and white whales, bearded and ringed seals, walruses and polar bears, and dietary fatty acids (FAs) in polar bears, walruses and most of the whale species listed here. SI values showed clear species separation by trophic behaviour and carbon sources. Bearded seals, walruses and white whales had the smallest isotopic niches; these species are all resident High Arctic species and are likely to be particularly vulnerable to changes in Arctic ecosystems. We found clear separation between FA groupings driven by pelagic, benthic and planktonic/algal sources: pelagic FAs in all whales, benthic FAs in walruses, and copepod/algae/dinoflagellate FAs in polar bears, with some polar bear compositions approaching those of the whales and walruses. There is strong niche partitioning between study species with minimal functional redundancy, which could impact Arctic ecosystem structure and connectivity if populations of these large nutrient vectors are reduced or lost

Projectile-charge-state dependence of target L

This article discusses projectile-charge-state dependence of target L-shell ionization by 1.86-MeV/amu and silicon ions and 1.8-MeV/amu chlorine ions

SAMPO, A Fortran IV Program for Computer Analysis of Gamma Spectra from Ge(Li) Detectors, and for Other Spectra with Peaks

SAMPO is a Fortran IV program written to perform the data- reduction analysis described by J. T. Routti and S. G. Prussin in Photopeak Method for the Computer Analysis of Gamma-Ray Spectra from Semiconductor Detectors, Nuclear Instruments and Methods 72, 125-142 (1969). The code has also been used to analyze other spectra with peaks and continua. Program SAMPO can be used for an automatic off-line or an interactive on-line analysis. It includes algorithms for line-shape, energy, and efficiency calibrations, and peak-search and peak-fitting routines. Different options are available to make the code applicable to accurate nuclear spectroscopic work as well as to routine data reduction. The mathematical methods and their coding are briefly described. Instructions for using the program and for preparing input data are given and the optimal strategies for running the code are discussed. Instructions are given for using the LRL program library version of SAMPO and for obtaining source decks

Angular distribution measurements of secondary-particle fluxes with spallation detectors and comparisons to hadron cascade calculations

A method is described for measuring angular distributions of momentum- integrated secondary-particle fluxes from high-energy accelerator targets by studying gamma-ray spectroscopically spallation reactions induced in foils placed around the targets. Results obtained for different threshold energies at 15- to 165-deg angles with copper foils at 22 GeV/c at the CERN Proton Synchrotron are presented. They are further interpreted with the aid of calculated spallation cross sections and compared with good agreement to the results of Monte Carlo computations of hadronic cascades

Interactive graphical computing for simulating and unfolding measured distributions

Techniques for the simulation and solution of the unfolding problem are described. The mathematical formalisms employed permit the use of a priori information of the solution to improve the stability and the uniqueness of the solution. In the computation graphical interaction with an on-line terminal is used. The methods are illustrated by considering examples of neutron spectroscopy with activation detectors. (25 refs)