386 research outputs found

    Geometrical entanglement of highly symmetric multipartite states and the Schmidt decomposition

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    In a previous paper we examined a geometric measure of entanglement based on the minimum distance between the entangled target state of interest and the space of unnormalized product states. Here we present a detailed study of this entanglement measure for target states with a large degree of symmetry. We obtain analytic solutions for the extrema of the distance function and solve for the Hessian to show that, up to the action of trivial symmetries, the solutions correspond to local minima of the distance function. In addition, we show that the conditions that determine the extremal solutions for general target states can be obtained directly by parametrizing the product states via their Schmidt decomposition.Comment: 16 pages, references added and discussion expande

    The behaviours that dementia care home staff in South Africa find challenging:An exploratory study

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    Background: Behavioural and psychological symptoms of dementia are often the reasons for moving to a care home. Care staff, often with limited dementia training, may have to support residents with distressed behaviour on a daily basis. Evidence about the support of residents with distressed or challenging behaviour in the South African context is lacking. This exploratory study aimed to gain an understanding of what care home staff perceived to be distressed behaviour, their coping strategies and how they learned to work with residents with behavioural symptoms of dementia. Methods: An exploratory study was conducted among 17 participants working in four care homes in the Western Cape province of South Africa in 2014. Semi-structured interviews were audio-recorded. Data were analysed thematically. Findings: Findings reflected the literature with regard to examples of behavioural symptoms of people with dementia that staff find challenging to manage. Overall, the majority of staff reported holding positive feelings about working with people with dementia. All preferred interpersonal approaches to manage distressed behaviour above medication although a small minority noted the use of medication in some cases. Dementia training was considered by most participants as an unmet need. Conclusion: This exploratory study identified care home workers’ desires for training about dementia and their preferences for interpersonal as opposed to pharmacological approaches to managing residents’ distressed behaviour. The legacy of race and cultural perspectives in South Africa appears to still influence care practice and provision. Staff commitment, their interest in advancing their practice and their aspirations to offer more person-centred care were evident. Dementia training was identified as potentially helpful to care home staff who manage residents’ distressed behaviour. Training should be developed in South Africa to promote good practice

    Chemically Induced Cryptic Sesquiterpenoids and Expression of Sesquiterpene Cyclases in Botrytis cinerea Revealed New Sporogenic (+)-4-Epieremophil-9-en-11-ols

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    The sequencing of the genomes of the B05.10 and T4 strains of the fungus Botrytis cinerea revealed an abundance of novel biosynthetic gene clusters, the majority of which were unexpected on the basis of the previous analyses of the fermentation of these and closely related species. By systematic alteration of easy accessible cultivation parameters, using chemical induction with copper sulfate, we have found a cryptic sesquiterpenoid family with new structures related to eremophil-9-ene, which had the basic structure of the sesquiterpene (+)-5-epiaristolochene ((+)-4-epieremophil-9- ene). An expression study of the sesquiterpene cyclase genes present in the Botrytis cinerea genome, under culture conditions, is reported. In general, a 3 day delay and a higher BcSTC genes expression were observed when copper (5 ppm) was fed to the fermentation broth. In addition, to the observed effect on the BcBOT2 (BcSTC1) gene, involved in the biosynthesis of the botrydial toxin, a higher expression level for BcSTC3 and BcSTC4 was observed with respect to the control in the strain B05.10. Interestingly, under copper conditions, the BcSTC4 gene was the most expressed gene in the Botrytis cinerea UCA992 strain. In vitro evaluation of the biological role of these metabolites indicates that they contributed to the conidial development in B. cinerea and appear to be involved in self-regulation of the production of asexual spores. Furthermore, they promoted the formation of complex appressoria or infection cushions

    COMADRE: A global data base of animal demography

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    This is the final version. Available on open access from Wiley via the DOI in this recordData accessibility: The data associated with this manuscript can be accessed at www.comadre-db.orgThe open-data scientific philosophy is being widely adopted and proving to promote considerable progress in ecology and evolution. Open-data global data bases now exist on animal migration, species distribution, conservation status, etc. However, a gap exists for data on population dynamics spanning the rich diversity of the animal kingdom world-wide. This information is fundamental to our understanding of the conditions that have shaped variation in animal life histories and their relationships with the environment, as well as the determinants of invasion and extinction. Matrix population models (MPMs) are among the most widely used demographic tools by animal ecologists. MPMs project population dynamics based on the reproduction, survival and development of individuals in a population over their life cycle. The outputs from MPMs have direct biological interpretations, facilitating comparisons among animal species as different as Caenorhabditis elegans, Loxodonta africana and Homo sapiens. Thousands of animal demographic records exist in the form of MPMs, but they are dispersed throughout the literature, rendering comparative analyses difficult. Here, we introduce the COMADRE Animal Matrix Database, an open-data online repository, which in its version 1.0.0 contains data on 345 species world-wide, from 402 studies with a total of 1625 population projection matrices. COMADRE also contains ancillary information (e.g. ecoregion, taxonomy, biogeography, etc.) that facilitates interpretation of the numerous demographic metrics that can be derived from its MPMs. We provide R code to some of these examples. Synthesis: We introduce the COMADRE Animal Matrix Database, a resource for animal demography. Its open-data nature, together with its ancillary information, will facilitate comparative analysis, as will the growing availability of databases focusing on other aspects of the rich animal diversity, and tools to query and combine them. Through future frequent updates of COMADRE, and its integration with other online resources, we encourage animal ecologists to tackle global ecological and evolutionary questions with unprecedented sample size.Australian Research Council (ARC)Evolutionary Demography Laboratory at the Max Planck Institute for Demographic Research (MPIDR)Natural Environment Research Council (NERC

    How Coupling Determines the Entrainment of Circadian Clocks

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    Autonomous circadian clocks drive daily rhythms in physiology and behaviour. A network of coupled neurons, the suprachiasmatic nucleus (SCN), serves as a robust self-sustained circadian pacemaker. Synchronization of this timer to the environmental light-dark cycle is crucial for an organism's fitness. In a recent theoretical and experimental study it was shown that coupling governs the entrainment range of circadian clocks. We apply the theory of coupled oscillators to analyse how diffusive and mean-field coupling affects the entrainment range of interacting cells. Mean-field coupling leads to amplitude expansion of weak oscillators and, as a result, reduces the entrainment range. We also show that coupling determines the rigidity of the synchronized SCN network, i.e. the relaxation rates upon perturbation. %(Floquet exponents). Our simulations and analytical calculations using generic oscillator models help to elucidate how coupling determines the entrainment of the SCN. Our theoretical framework helps to interpret experimental data

    Diurnal Variations of Mouse Plasma and Hepatic Bile Acid Concentrations as well as Expression of Biosynthetic Enzymes and Transporters

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    Diurnal fluctuation of bile acid (BA) concentrations in the enterohepatic system of mammals has been known for a long time. Recently, BAs have been recognized as signaling molecules beyond their well-established roles in dietary lipid absorption and cholesterol homeostasis.The current study depicted diurnal variations of individual BAs detected by ultra-performance liquid chromatography/mass spectrometry (UPLC/MS) in serum and livers collected from C57BL/6 mice fed a regular chow or a chow containing cholestyramine (resin). Circadian rhythms of mRNA of vital BA-related nuclear receptors, enzymes, and transporters in livers and ilea were determined in control- and resin-fed mice, as well as in farnesoid X receptor (FXR) null mice. The circadian profiles of BAs showed enhanced bacterial dehydroxylation during the fasting phase and efficient hepatic reconjugation of BAs in the fed phase. The resin removed more than 90% of BAs with β-hydroxy groups, such as muricholic acids and ursodeoxycholic acid, from serum and livers, but did not exert as significant influence on CA and CDCA in both compartments. Both resin-fed and FXR-null mouse models indicate that BAs regulate their own biosynthesis through the FXR-regulated ileal fibroblast growth factor 15. BA flux also influences the daily mRNA levels of multiple BA transporters.BA concentration and composition exhibit circadian variations in mouse liver and serum, which influences the circadian rhythms of BA metabolizing genes in liver and ileum. The diurnal variations of BAs appear to serve as a signal that coordinates daily nutrient metabolism in mammals

    Ozone observations and a model of marine boundary layer photochemistry during SAGA 3

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    A major purpose of the third joint Soviet‐American Gases and Aerosols (SAGA 3) oceanographic cruise was to examine remote tropical marine O3 and photochemical cycles in detail. On leg 1, which took place between Hilo, Hawaii, and Pago‐Pago, American Samoa, in February and March 1990, shipboard measurements were made of O3, CO, CH4, nonmethane hydrocarbons (NMHC), NO, dimethyl sulfide (DMS), H2S, H2O2, organic peroxides, and total column O3. Postcruise analysis was performed for alkyl nitrates and a second set of nonmethane hydrocarbons. A latitudinal gradient in O3 was observed on SAGA 3, with O3 north of the intertropical convergence zone (ITCZ) at 15–20 parts per billion by volume (ppbv) and less than 12 ppbv south of the ITCZ but never ≤3 ppbv as observed on some previous equatorial Pacific cruises (Piotrowicz et al., 1986; Johnson et al., 1990). Total column O3 (230–250 Dobson units (DU)) measured from the Akademik Korolev was within 8% of the corresponding total ozone mapping spectrometer (TOMS) satellite observations and confirmed the equatorial Pacific as a low O3 region. In terms of number of constituents measured, SAGA 3 may be the most photochemically complete at‐sea experiment to date. A one‐dimensional photochemical model gives a self‐consistent picture of O3‐NO‐CO‐hydrocarbon interactions taking place during SAGA 3. At typical equatorial conditions, mean O3 is 10 ppbv with a 10–15% diurnal variation and maximum near sunrise. Measurements of O3, CO, CH4, NMHC, and H2O constrain model‐calculated OH to 9 × 105 cm−3 for 10 ppbv O3 at the equator. For DMS (300–400 parts per trillion by volume (pptv)) this OH abundance requires a sea‐to‐air flux of 6–8 × 109 cm−2 s−1, which is within the uncertainty range of the flux deduced from SAGA 3 measurements of DMS in seawater (Bates et al., this issue). The concentrations of alkyl nitrates on SAGA 3 (5–15 pptv total alkyl nitrates) were up to 6 times higher than expected from currently accepted kinetics, suggesting a largely continental source for these species. However, maxima in isopropyl nitrate and bromoform near the equator (Atlas et al., this issue) as well as for nitric oxide (Torres and Thompson, this issue) may signify photochemical and biological sources of these species
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