Two New Species and Temporal Changes in the Prevalence of Eimerians in a Free-Living Population of Townsend\u27s Ground Squirrels (\u3ci\u3eSpermophilus townsendii\u3c/i\u3e) in Idaho

More than 1,180 fecal samples were collected from 253 juvenile and 384 adult Townsend\u27s ground squirrels (Spermophilus townsendii) at the Snae Snake River Birds of Prey Area near Boise, Idaho, from February to June 1992. Oocysts of 7 eimerians were observed. Five are new host records (Eimeria beecheyi, Eimeria bilamellata, Eimeria callospermophili, Eimeria lateralis, and Eimeria morainensis), 2 species are described here as new, and new structural information on E. morainensis is added. Sporulated oocysts of Eimeria adaensis n. sp. are ovoidal, 19.6 x 22.7 (16-22 x 18-26) μm with sporocysts ellipsoidal 7.2 x 11.9 (6-10 x 9-15) μm. No micropyle or oocyst residuum, but polar bodies, Stieda bodies, and sporocyst residua are present. Sporulated oocysts of Eimeria pseudospermophili n. sp. are ovoidal, 24.7 x 28.5 (21-27 x 25-32) μm with sporocysts ellipsoidal 8.8 x 14.2 (8-10 x 12-17) μm. Micropyle and oocyst residuum are absent, but polar bodies and Stieda bodies are present. Sporulated oocysts of E. morainensis are more variable in size and shape than originally described and contain 2 distinctly different residua not previously described. Temporal changes in the prevalence of eimerians of all 7 species combined in adult squirrels showed significant decline (r2 = 0.79, P \u3c 0.001). We hypothesize that this decline was due to drought during the period of squirrel activity. No significant temporal change in the prevalence of eimerians in juvenile squirrels was observed. The prevalence of E. callospermophili, E. adaensis, and all eimerians combined in adults was significantly greater than in juveniles. There was no significant difference in eimerian prevalence between male and female squirrels (P \u3c 0.05)

Going Solo: Discovery of the First Parthenogenetic Gordiid (Nematomorpha: Gordiida)

Despite the severe fitness costs associated with sexual reproduction, its persistence and pervasiveness among multicellular organisms testifies to its intrinsic, short-term advantages. However, the reproductive assurance hypothesis predicts selection favoring asexual reproduction in sparse populations and when mate finding is difficult. Difficulties in finding mates is especially common in parasites, whose life cycles involve multiple hosts, or being released from the host into the external environment where the parasite can find itself trapped without a sexual partner. To solve this problem and guarantee reproduction, parasites in numerous phyla have evolved reproductive strategies, as predicted by the reproductive assurance hypothesis, such as hermaphroditism or parthenogenesis. However, this type of strategy has not been reported from species in the phylum Nematomorpha, whose populations have often been described as sparse. A new Nematomorpha species, Paragordius obamai n. sp., was discovered from Kenya, Africa, and appears to have solved the problem of being trapped without a mate by eliminating the need for males. Paragordius obamai n. sp. represents the first and only known species within this phylum to reproduce asexually. To determine the mechanism of this mating strategy, we ruled out the involvement of reproduction manipulating endosymbionts by use of next generation sequencing data, thus suggesting that parthenogenesis is determined genetically and may have evolved as a means to assure reproduction. Since this new parthenogenetic species and a closely related gonochoristic North American congener, P. varius, are easy to propagate in the laboratory, these gordiids can be used as model systems to test hypotheses on the genetic advantages and disadvantages of asexual reproduction and the genetic determinants of reproductive strategies in parasites

Measurement of nuclide cross-sections of spallation residues in 1 A GeV 238U + proton collisions

The production of heavy nuclides from the spallation-evaporation reaction of 238U induced by 1 GeV protons was studied in inverse kinematics. The evaporation residues from tungsten to uranium were identified in-flight in mass and atomic number. Their production cross-sections and their momentum distributions were determined. The data are compared with empirical systematics. A comparison with previous results from the spallation of 208Pb and 197Au reveals the strong influence of fission in the spallation of 238U.Comment: 20 pages, 10 figures, background information at http://www-wnt.gsi.de/kschmidt

Projectile fragmentation of 129Xe at Elab=790 AMeV

We have measured production yields and longitudinal momentum distributions of projectile-like fragments in the reaction 129Xe + 27Al at an energy of Elab=790 AMeV. Production cross sections higher than expected from systematics were observed for nuclei in the neutron-deficient tails of the isotopic distributions. A comparison with previously measured data from the fragmentation of 136Xe ions shows that the production yields strongly depend on the neutron excess of the projectile with respect to the line of beta-stability. The momentum distributions exhibit a dependence on the fragment neutron-to-proton ratio in isobaric chains, which was not expected from systematics so far. This can be interpreted by a higher excitation of the projectile during the formation of neutron-deficient fragments.Comment: 21 pages, 8 figures, 1 tabl

Evaporation residues produced in spallation of 208Pb by protons at 500A MeV

The production cross sections of fragmentation-evaporation residues in the reaction Pb+p at 500A MeV have been measured using the inverse-kinematics method and the FRS spectrometer (GSI). Fragments were identified in nuclear charge using ionisation chambers. The mass identification was performed event-by-event using the B-rho - TOF - Delta-E technique. Although partially-unresolved ionic charge states induced an ambiguity on the mass of some heavy fragments, production rates could be obtained with a high accuracy by systematically accounting for the polluting ionic charge states. The contribution of multiple reactions in the target was subtracted using a new, partly self-consistent code. The isobaric distributions are found to have a shape very close to the one observed in experiments at higher energy. Kinematic properties of the fragments were also measured. The total and the isotopic cross sections, including charge-pickup cross sections, are in good agreement with previous measurements. The data are discussed in the light of previous spallation measurements, especially on lead at 1 GeV

Chief digital officers:An analysis of the presence of a centralized digital transformation role

By appointing a chief digital officer (CDO), firms decide for a central role responsible for their digital transformation. While CDOs have recently appeared in the C-suites of firms across the globe, the current literature lacks insights into the specific antecedents of CDO presence. Grounded in the peculiarities of the digital age, we provide theoretical arguments explaining how the decision to centralize digital transformation responsibilities might be related to transformation urgency and coordination needs. Empirical analyses based on a panel data set of 913 U.S. and European firms support that transformation urgency and coordination needs predict CDO presence. An additional analysis of moderating temporal effects reveals that, over time, the effect of transformation urgency is weakened and the effect of coordination needs on CDO presence is strengthened. We discuss implications for research and practice regarding the antecedents of CDO presence, TMT research more generally, and centralization in the digital age

Parallel momentum distribution of the 28^{28}Si fragments from 29^{29}P

Distribution of the parallel momentum of $^{28}$Si fragments from the breakup of 30.7 MeV/nucleon $^{29}$P has been measured on C targets. The distribution has the FWHM with the value of 110.5 $\pm$ 23.5 MeV/c which is consistent quantitatively with Galuber model calculation assuming by a valence proton in $^{29}$P. The density distribution is also predicted by Skyrme-Hartree-Fock calculation. Results show that there might exist the proton-skin structure in $^{29}$P.Comment: 4 pages, 4 figure

Changes in microphytobenthos fluorescence over a tidal cycle: implications for sampling designs

Intertidal microphytobenthos (MPB) are important primary producers and provide food for herbivores in soft sediments and on rocky shores. Methods of measuring MPB biomass that do not depend on the time of collection relative to the time of day or tidal conditions are important in any studies that need to compare temporal or spatial variation, effects of abiotic factors or activity of grazers. Pulse amplitude modulated (PAM) fluorometry is often used to estimate biomass of MPB because it is a rapid, non-destructive method, but it is not known how measures of fluorescence are altered by changing conditions during a period of low tide. We investigated this experimentally using in situ changes in minimal fluorescence (F) on a rocky shore and on an estuarine mudflat around Sydney (Australia), during low tides. On rocky shores, the time when samples are taken during low tide had little direct influence on measures of fluorescence as long as the substratum is dry. Wetness from wave-splash, seepage from rock pools, run-off, rainfall, etc., had large consequences for any comparisons. On soft sediments, fluorescence was decreased if the sediment dried out, as happens during low-spring tides on particularly hot and dry days. Surface water affected the response of PAM and therefore measurements used to estimate MPB, emphasising the need for care to ensure that representative sampling is done during low tide