Two roles of relativistic spin operators

Operators that are associated with several important quantities, like angular momentum, play a double role: they are both generators of the symmetry group and ``observables.'' The analysis of different splittings of angular momentum into "spin" and "orbital" parts reveals the difference between these two roles. We also discuss a relation of different choices of spin observables to the violation of Bell inequalities.Comment: RevTeX 4, 4 pages A discussion on relation of different choices of spin observables to the observed violation of Bell inequalities is added, some misprints corrected and the presentation is clarifie

The plant pathogen Phytophthora cinnamomi influences habitat use by the obligate nectarivore honey possum (Tarsipes rostratus)

Introduced plant pathogens can devastate susceptible plant communities, and consequently impact on animal communities reliant on plants for food and habitat. Specifically, plant pathogens change the floristic diversity of vegetation communities, thereby reducing availability of food sources for fauna (e.g. pollen and nectar) and result in major changes to habitat structure when canopy and understorey plant species succumb to disease. Phytophthora cinnamomi poses a threat to flowering plant species (e.g. Banksia species) which are important food sources for nectarivorous fauna. The honey possum (Tarsipes rostratus) is the only obligate nectarivorous non-flying mammal living on a restrictive diet of nectar and pollen; consequently, these tiny mammals are likely to be particularly vulnerable to the landscape-wide devastation caused by P. cinnamomi. We investigated habitat selection by honey possums in a vegetation community infested with P. cinnamomi to determine how these mammals respond to habitat affected by this pathogen. Over four seasons, 18 honey possums were fitted with radio-transmitters and tracked to identify habitat preferences. Vegetation surveys were compared for locations selected by honey possums (as determined from tracking) and randomly selected sites. Radio-tracking revealed that sites selected by honey possums were significantly taller, denser, and more floristically diverse than their paired random locations. The presence of P. cinnamomi influences habitat use by honey possums, but animals show resilience in terms of using the best of what is available in both P. cinnamomi-affected and unaffected locations. Habitat patches comprising less susceptible species, or plants that have yet to succumb to infection, provide refuge and food resources for honey possums. Management to reduce the spread of existing P. cinnamomi infestations and prevent contamination of new locations will benefit vegetation communities and associated faunal communities, while identifying honey possum food plant species that are resilient to the pathogen may support revegetation attempts

Avian community changes following drought-induced canopy collapse in a Mediterranean-type forest

Context: Extreme drought can result in the widespread die-off of forests and dramatically altered ecosystem structure. Such changes are likly to influence fauna using resouces within these forests. Aims: Following a record hot and dry year/summer in 2010/11, large-scale canopy collapse occurred within a Mediterranean-type mixed jarrah (Eucalyptus marginata)–marri (Corymbia calophylla) forest in south-west Western Australia. We investigated the effects of this collapse on bird assemblages in 2016, 5 years after the initial collapse. Methods: We carried out bird surveys using a standardised search method for five paired drought-affected and adjacent healthy forest plots. Key results: A total of 3042 records of 51 bird species were observed across all surveys. Overall, the pooled (mean ± s.d.) reporting rates for drought-affected plots (13.84 ± 0.60 individuals/survey) were significantly less than the reporting rates for healthy plots (34.44 ± 1.03 individuals/survey) (PERMANOVA: F1 = 54.94, R2 = 0.31, P = 0.001). Species diversity was also higher in healthy plots (t26 = 11.21, P < 0.001). Foliage-searching birds were the most abundant guild across all plots and were reported less often in drought-affected plots (t6 = 2.70, P < 0.04). Conclusions: Drought-affected jarrah forest plots exhibited significant differences in bird assemblages compared to healthy plots. Overall, the drought-affected forest provides a less favourable habitat for birds compared to healthy forest. Implications: With marked variability and extreme climate events predicted for the future, understanding the impacts of such changes will contribute to how we manage forest ecosystems

Bioturbation by echidna (Tachyglossus aculeatus) in a forest habitat, south-western Australia

Bioturbation by digging animals is important for key forest ecosystem processes such as soil turnover, decomposition, nutrient cycling, water infiltration, seedling recruitment, and fungal dispersal. Despite their widespread geographic range, little is known about the role of the short-beaked echidna (Tachyglossus aculeatus) in forest ecosystems. We measured the density and size of echidna diggings in the Northern Jarrah Forest, south-western Australia, to quantify the contribution echidna make to soil turnover. We recorded an overall density of 298 echidna diggings per hectare, 21% of which were estimated to be less than 1 month old. The average size of digs was 50 ± 25 mm in depth and 160 ± 61 mm in length. After taking into account seasonal digging rates, we estimated that echidnas turn over 1.23 tonnes of soil ha−1 year−1 in this forest, representing an important role in ecosystem dynamics. Our work contributes to the growing body of evidence quantifying the role of these digging animals as critical ecosystem engineers. Given that the echidna is the only Australian digging mammal not severely impacted by population decline or range reduction, its functional contribution to health and resilience of forest ecosystems is increasingly important due to the functional loss of most Australian digging mammals

Land use and dingo baiting are correlated with the density of kangaroos in rangeland systems

Rangelands worldwide have been subject to broadscale modification, such as widespread predator control, introduction of permanent livestock water and altered vegetation to improve grazing. In Australia, these landscape changes have resulted in kangaroos (i.e. large macropods) populations increasing over the past 200 years. Kangaroos are a key contributor to total grazing pressure and in conjunction with livestock and feral herbivores have been linked to land degradation. We used 22 years of aerial survey data to investigate whether the density of 3 macropod species in the southern rangelands of Western Australia was associated with: (i) land use, including type of livestock, total livestock, density of feral goats, type of land tenure, and kangaroo commercial harvest effort; (ii) predator management, including permitted dingo control effort, estimated dingo abundance, and presence of the State Barrier Fence (a dingo exclusion fence); and (iii) environmental variables: ruggedness, rainfall, fractional cover, and total standing dry matter. Red kangaroos (Osphranter rufus) were most abundant in flat, open vegetation, on pastoral land, where area permitted for dingo control was high, and numbers were positively associated with antecedent rainfall with a 12-month delay. Western grey kangaroos (Macropus fuliginosus) were most abundant on flat, agricultural land, but less abundant in areas with high permitted dingo control. Euros (Osphranter robustus) were most abundant in rugged pastoral land with open vegetation, where permitted dingo control was high. While environmental variables are key drivers of landscape productivity and kangaroo populations, anthropogenic factors such as land use and permitted dingo control are strongly associated with kangaroo abundance

Hadronic ψ\psi production calculated in the NRQCD factorization formalism

The NRQCD factorization formalism of Bodwin, Braaten, and Lepage prescribes how to write quarkonium production rates as a sum of products of short-distance coefficients times non-perturbative long-distance NRQCD matrix elements. We present, in the true spirit of the factorization formalism, a detailed calculation of the inclusive cross section for hadronic $\psi$ production. We find that in addition to the well known {\it color-singlet} production mechanisms, there are equally important mechanisms in which the $c\bar{c}$ pair that forms the $\psi$ is initially produced in a {\it color-octet} state, in either a ${}^3S_1$, ${}^1S_0$, ${}^3P_0$ or ${}^3P_2$ angular-momentum configuration. In our presentation, we emphasize the ``matching'' procedure, which %is the method that allows us to determine the short-distance coefficients appearing in the factorization formula. We also point out how one may systematically include relativistic corrections in these calculations.Comment: 25 pages, 3 postscript figures, use Revtex and epsfig.sty We fixed some typos, added some text regarding a reference, and changed some equations. The file will be available at http://phenom.physics.wisc.edu

Distinctive diets of eutherian predators in Australia

Introduction of the domestic cat and red fox has devastated Australian native fauna. We synthesized Australian diet analyses to identify traits of prey species in cat, fox and dingo diets, which prey were more frequent or distinctive to the diet of each predator, and quantified dietary overlap. Nearly half (45%) of all Australian terrestrial mammal, bird and reptile species occurred in the diets of one or more predators. Cat and dingo diets overlapped least (0.64 ± 0.27, n = 24 location/time points) and cat diet changed little over 55 years of study. Cats were more likely to have eaten birds, reptiles and small mammals than foxes or dingoes. Dingo diet remained constant over 53 years and constituted the largest mammal, bird and reptile prey species, including more macropods/potoroids, wombats, monotremes and bandicoots/bilbies than cats or foxes. Fox diet had greater overlap with both cats (0.79 ± 0.20, n = 37) and dingoes (0.73 ± 0.21, n = 42), fewer distinctive items (plant material, possums/gliders) and significant spatial and temporal heterogeneity over 69 years, suggesting the opportunity for prey switching (especially of mammal prey) to mitigate competition. Our study reinforced concerns about mesopredator impacts upon scarce/threatened species and the need to control foxes and cats for fauna conservation. However, extensive dietary overlap and opportunism, as well as low incidence of mesopredators in dingo diets, precluded resolution of the debate about possible dingo suppression of foxes and cats

Genomic epidemiology of clinical Campylobacter spp. at a single health trust site

© 2018 The Authors. Published by Microbiology Society. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1099/mgen.0.000227Campylobacter is the leading cause of bacterial enteritis in the developed world, and infections with the organism are largely sporadic in nature. Links between sporadic cases have not been established, with the majority of infections thought to be caused by genetically distinct isolates. Using a read-mapping approach, 158 clinical isolates collected during 2014 from the greater Nottinghamshire area were analysed to assess the local population structure and investigate potential case linkages between sporadic cases of campylobacteriosis. Four instances (2.5 %) of case linkage were observed across the dataset. This study demonstrates that case linkage does occur between sporadic Campylobacter infections, and provides evidence that a dual multi-locus sequence typing/within-lineage single nucleotide polymorphism typing approach to Campylobacter genomic epidemiology provides a benefit to public-health investigations.Nottingham Trent Universit

Charmonium production at neutrino factories

At existing and planned neutrino factories (high energy and high intensity neutrino beam facilities) precision studies of QCD in neutrino-nucleon interactions are a realistic opportunity. We investigate charmonium production in fixed target neutrino experiments. We find that $J/\psi$ production in neutrino-nucleon collision is dominated by the color octet $^3S_1$ NRQCD matrix element in a neutral current process, which is not accessible in photo or leptoproduction. Neutrino experiments at a future Muon Collider will acquire sufficient event rate to accurately measure color octet matrix element contributions. The currently running high energy neutrino experiments, NOMAD and NuTeV could also observe several such events.Comment: 13 pages Latex, with five embedded eps figures. Cosmetic fixups in the figures, otherwise unchange

Structure and properties of a novel fulleride Sm6C60

A novel fulleride Sm6C60 has been synthesized using high temperature solid state reaction. The Rietveld refinement on high resolution synchrotron X-ray powder diffraction data shows that Sm6C60 is isostructural with body-centered cubic A6C60 (A=K, Ba). Raman spectrum of Sm6C60 is similar to that of Ba6C60, and the frequencies of two Ag modes in Sm6C60 are nearly the same as that of Ba6C60, suggesting that Sm is divalent and hybridization between C60 molecules and the Sm atom could exist in Sm6C60. Resistivity measurement shows a weak T-linear behavior above 180 K, the transport at low temperature is mainly dominated by granular-metal theory.Comment: 9 pages, 3 figures, submitted to Phys. Rev. B (March 12, 1999