7,423 research outputs found
Experimental assessment of predation risk for juvenile green sturgeon, Acipenser medirostris, by two predatory fishes
Morphology of the recently re-classified Tasman masked booby (Sula dactylatra tasmani) breeding on the Kermadec Islands
Once thought to be extinct, the Tasman Booby Sula tasmani has recently been re-classified as a subspecies of the Masked Booby S. dactylatra on the basis of genetic data. This re-classification raises the issue of whether this novel clade has a distinct morphology. Morphological differences in size, as well as coloration of integuments, bill and iris have been found in other subspecies of the Masked Booby but have not yet been reported for live Kermadec Islands breeding individuals. Museum specimens from this breeding location have been separated from other Pacific breeding subspecies by their longer wings. We sampled a total of 21 individuals from North Meyer Islet, Kermadec Group, New
Zealand, and applied molecular sexing to obtain sex-specific morphometric measurements. We matched dimorphism in vocalization with genetic sexing results and photographic documentation of human-assessed bill, foot and eye coloration. While culmen measurements were consistent with reports from museum specimens, wing chords from living specimens of Tasman Masked Boobies were 3% and 4% larger in males and females, respectively. Females had larger culmens and wings than males, consistent with the low extent of sexual dimorphism reported from museum skins. Adult Tasman Masked Boobies had yellow to buff-yellow feet, while fledglings, as in most sulids, had grey
to greyish-yellow feet. Our findings confirm the distinctively long wing and particular iris coloration previously reported for the taxon and provide the first description of integument coloration of live specimens. This study highlights the importance of including in situ assessment in taxon descriptions
Recolonization of Raoul Island by Kermadec red-crowned parakeets Cyanoramphus novaezelandiae cyanurus after eradication of invasive predators, Kermadec Islands archipelago, New Zealand
The Kermadec red-crowned parakeet Cyanoramphus novaezelandiae was driven to extinction on Raoul Island over 150 years ago by introduced cats Felis catus and rats (Rattus norvegicus and R. exulans). These predators were eradicated from the island (2,938 ha) between 2002-04 during the world’s largest multispecies eradication project. In 2008 we documented a unique recolonisation event when parakeets were observed to have returned to Raoul, presumably from a nearby island group, The Herald Islets (51 ha). We captured and aged 100 parakeets, of which 44% were born in 2008, and breeding was observed on Raoul Island. This represents the first evidence of nesting of this species on Raoul Island since 1836. Our findings highlight the global conservation potential for island avifaunas by prioritising eradication areas through consideration of proximity of remnant populations to target management locations, instead of the classical translocation approach alone. The natural recolonization of parakeets on Raoul Island from a satellite source population is to our knowledge, a first for parrot conservation and the first documented population expansion and island recolonization of a parrot species after removal of invasive predators
Parametric vision simulation study, part 2 Final report
Effects of landing site redesignation on visibility during manned lunar landin
Demixing of aqueous polymer two-phase systems in low gravity
When polymers such as dextran and poly(ethylene glycol) are mixed in aqueous solution biphasic systems often form. On Earth the emulsion formed by mixing the phases rapidly demixes because of phase density differences. Biological materials can be purified by selective partitioning between the phases. In the case of cells and other particulates the efficiency of these separations appears to be somewhat compromised by the demixing process. To modify this process and to evaluate the potential of two-phase partitioning in space, experiments on the effects of gravity on phase emulsion demixing were undertaken. The behavior of phase systems with essentially identical phase densities was studied at one-g and during low-g parabolic aircraft maneuvers. The results indicate the demixing can occur rather rapidly in space, although more slowly than on Earth. The demixing process was examined from a theoretical standpoint by applying the theory of Ostwald ripening. This theory predicts demizing rates many orders of magnitude lower than observed. Other possible demixing mechanisms are considered
Proposal for the determination of nuclear masses by high-precision spectroscopy of Rydberg states
The theoretical treatment of Rydberg states in one-electron ions is
facilitated by the virtual absence of the nuclear-size correction, and
fundamental constants like the Rydberg constant may be in the reach of planned
high-precision spectroscopic experiments. The dominant nuclear effect that
shifts transition energies among Rydberg states therefore is due to the nuclear
mass. As a consequence, spectroscopic measurements of Rydberg transitions can
be used in order to precisely deduce nuclear masses. A possible application of
this approach to the hydrogen and deuterium, and hydrogen-like lithium and
carbon is explored in detail. In order to complete the analysis, numerical and
analytic calculations of the quantum electrodynamic (QED) self-energy remainder
function for states with principal quantum number n=5,...,8 and with angular
momentum L=n-1 and L=n-2 are described (j = L +/- 1/2).Comment: 21 pages; LaTe
Genetically Distinct Behavioral Modules Underlie Natural Variation in Thermal Performance Curves
Thermal reaction norms pervade organismal traits as stereotyped responses to temperature, a fundamental environmental input into sensory and physiological systems. Locomotory behavior represents an especially plastic read-out of animal response, with its dynamic dependence on environmental stimuli presenting a challenge for analysis and for understanding the genomic architecture of heritable variation. Here we characterize behavioral reaction norms as thermal performance curves for the nematode Caenorhabditis briggsae, using a collection of 23 wild isolate genotypes and 153 recombinant inbred lines to quantify the extent of genetic and plastic variation in locomotory behavior to temperature changes. By reducing the dimensionality of the multivariate phenotypic response with a function-valued trait framework, we identified genetically distinct behavioral modules that contribute to the heritable variation in the emergent overall behavioral thermal performance curve. Quantitative trait locus mapping isolated regions on Chromosome II associated with locomotory activity at benign temperatures and Chromosome V loci related to distinct aspects of sensitivity to high temperatures, with each quantitative trait locus explaining up to 28% of trait variation. These findings highlight how behavioral responses to environmental inputs as thermal reaction norms can evolve through independent changes to genetically distinct modular components of such complex phenotypes
Syzygies in equivariant cohomology for non-abelian Lie groups
We extend the work of Allday-Franz-Puppe on syzygies in equivariant
cohomology from tori to arbitrary compact connected Lie groups G. In
particular, we show that for a compact orientable G-manifold X the analogue of
the Chang-Skjelbred sequence is exact if and only if the equivariant cohomology
of X is reflexive, if and only if the equivariant Poincare pairing for X is
perfect. Along the way we establish that the equivariant cohomology modules
arising from the orbit filtration of X are Cohen-Macaulay. We allow singular
spaces and introduce a Cartan model for their equivariant cohomology. We also
develop a criterion for the finiteness of the number of infinitesimal orbit
types of a G-manifold.Comment: 28 pages; minor change
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