538 research outputs found

    Using five-minute bird counts to study magpie (Gymnorhina tibicen) impacts on other birds in New Zealand

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    We used five-minute bird counts to investigate whether introduced Australian magpies (Gymnorhina tibicen) influence the abundance of other birds in rural New Zealand. Over 3 years, magpies were removed from five c. 900-ha study blocks, one in each of Northland, Waikato, Bay of Plenty, Wellington and Southland. Birds were counted in both the treatment blocks and paired non-treatment blocks for the 3 years of removal and also 1 year before. To minimise problems raised elsewhere with index counts we (1) selected treatment blocks and count stations using randomisation procedures, (2) used trained observers who spent equal time in paired treatment and non-treatment blocks, and (3) counted all blocks at the same time of year and only in good weather. On average, 548 magpies were removed from each treatment block each year, with magpie counts reduced by 76% relative to non-treatment blocks. Our results suggest magpies may restrict the movements of some birds (including kererū and tūī) in rural areas, but are less important than pest mammals at limiting population abundance at a landscape scale. We submit that five-minute bird counts were appropriate for our objectives, but that more research to examine their relationship to absolute densities is needed

    Effectiveness of the global protected area network in representing species diversity

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    The Fifth World Parks Congress in Durban, South Africa, announced in September 2003 that the global network of protected areas now covers 11.5% of the planet's land surface. This surpasses the 10% target proposed a decade earlier, at the Caracas Congress, for 9 out of 14 major terrestrial biomes. Such uniform targets based on percentage of area have become deeply embedded into national and international conservation planning. Although politically expedient, the scientific basis and conservation value of these targets have been questioned. In practice, however, little is known of how to set appropriate targets, or of the extent to which the current global protected area network fulfils its goal of protecting biodiversity. Here, we combine five global data sets on the distribution of species and protected areas to provide the first global gap analysis assessing the effectiveness of protected areas in representing species diversity. We show that the global network is far from complete, and demonstrate the inadequacy of uniform—that is, 'one size fits all'—conservation targets

    Random planar graphs and the London street network

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    In this paper we analyse the street network of London both in its primary and dual representation. To understand its properties, we consider three idealised models based on a grid, a static random planar graph and a growing random planar graph. Comparing the models and the street network, we find that the streets of London form a self-organising system whose growth is characterised by a strict interaction between the metrical and informational space. In particular, a principle of least effort appears to create a balance between the physical and the mental effort required to navigate the city

    A Qualitative Exploration of Seriously Ill Patients’ Experiences of Goals of Care Discussions in Australian Hospital Settings

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    © 2020, Society of General Internal Medicine. Background: Goals of care (GOC) is a communication and decision-making process that occurs between a clinician and a patient (or surrogate decision-maker) during an episode of care to facilitate a plan of care that is consistent with the patient’s preferences and values. Little is known about patients’ experiences of these discussions. Objective: This study explored patients’ perspectives of the GOC discussion in the hospital setting. Design: An explorative qualitative design was used within a social constructionist framework. Participants: Adult patients were recruited from six Australian hospitals across two states. Eligible patients had had a GOC discussion and they were identified by the senior nurse or their doctor for informed consent and interview. Approach: Semi-structured individual or dyadic interviews (with the carer/family member present) were conducted at the bedside or at the patient’s home (for recently discharged patients). Interviews were audio-recorded and transcribed verbatim. Data were analysed for themes. Key Results: Thirty-eight patient interviews were completed. The key themes identified were (1) values and expectations, and (2) communication (sub-themes: (i) facilitators of the conversation, (ii) barriers to the conversation, and (iii) influence of the environment). Most patients viewed the conversation as necessary and valued having their preferences heard. Effective communication strategies and a safe, private setting were facilitators of the GOC discussion. Deficits in any of these key elements functioned as a barrier to the process. Conclusions: Effective communication, and patients’ values and expectations set the stage for goals of care discussions; however, the environment plays a significant role. Communication skills training and education designed to equip clinicians to negotiate GOC interactions effectively are essential. These interventions must also be accompanied by systemic changes including building a culture supportive of GOC, clear policies and guidelines, and champions who facilitate uptake of GOC discussions

    Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV

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    We present a search for the production of neutral Higgs bosons decaying into tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tautau pairs, and we then interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL

    Measurement of the photon+b+b-jet production differential cross section in ppˉp\bar{p} collisions at \sqrt{s}=1.96~\TeV

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    We present measurements of the differential cross section dsigma/dpT_gamma for the inclusive production of a photon in association with a b-quark jet for photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is the photon transverse momentum. The b-quark jets are required to have pT>15 GeV and rapidity |y_jet| < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the Fermilab Tevatron ppˉp\bar{p} Collider at sqrt(s)=1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the Sherpa and Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.

    Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV

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    We present final searches of the anomalous gammaWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wgamma, WW, and WZ production with leptonic final states. The analyzed data correspond to up to 8.6/fb of integrated luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96 TeV. We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2 TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154, -0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization, and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL

    Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV

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    We present the first measurement of the inclusive three-jet differential cross section as a function of the invariant mass of the three jets with the largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96 TeV. The measurement is made in different rapidity regions and for different jet transverse momentum requirements and is based on a data set corresponding to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at the Fermilab Tevatron Collider. The results are used to test the three-jet matrix elements in perturbative QCD calculations at next-to-leading order in the strong coupling constant. The data allow discrimination between parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected chi2 values for NNPD

    Search for pair production of the scalar top quark in muon+tau final states

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    We present a search for the pair production of scalar top quarks (t~1\tilde{t}_{1}), the lightest supersymmetric partners of the top quarks, in ppˉp\bar{p} collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of {7.3 fb1fb^{-1}} collected with the \dzero experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a bb quark, a charged lepton, and a scalar neutrino (ν~\tilde{\nu}). We investigate final states arising from t~1t~1ˉbbˉμτν~ν~\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\mu\tau \tilde{\nu} \tilde{\nu} and t~1t~1ˉbbˉττν~ν~\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\tau\tau \tilde{\nu} \tilde{\nu}. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the (mt~1m_{\tilde{t}_{1}},mν~m_{\tilde{\nu}}) plane.Comment: Submitted to Phys. Lett.
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