693 research outputs found

    Sharks of the order Carcharhiniformes from the British Coniacian, Santonian and Campanian (Upper Cretaceous).

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    Bulk sampling of phosphate-rich horizons within the British Coniacian to Campanian (Upper Cretaceous) yielded very large samples of shark and ray teeth. All of these samples yielded teeth of diverse members of the Carcharhiniformes, which commonly dominate the fauna. The following species are recorded and described: Pseudoscyliorhinus reussi (Herman, 1977) comb. nov., Crassescyliorhinus germanicus (Herman, 1982) gen. nov., Scyliorhinus elongatus (Davis, 1887), Scyliorhinus brumarivulensis sp. nov., ? Palaeoscyllium sp., Prohaploblepharus riegrafi (Müller, 1989) gen. nov., ? Cretascyliorhinus sp., Scyliorhinidae inc. sedis 1, Scyliorhinidae inc. sedis 2, Pteroscyllium hermani sp. nov., Protoscyliorhinus sp., Leptocharias cretaceus sp. nov., Palaeogaleus havreensis Herman, 1977, Paratriakis subserratus sp. nov., Paratriakis tenuis sp. nov., Paratriakis sp. indet. and ? Loxodon sp. Taxa belonging to the families ?Proscylliidae, Leptochariidae, and Carcharhinidae are described from the Cretaceous for the first time. The evolutionary and palaeoecological implications of these newly recognised faunas are discussed

    Continuous Symmetries of Difference Equations

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    Lie group theory was originally created more than 100 years ago as a tool for solving ordinary and partial differential equations. In this article we review the results of a much more recent program: the use of Lie groups to study difference equations. We show that the mismatch between continuous symmetries and discrete equations can be resolved in at least two manners. One is to use generalized symmetries acting on solutions of difference equations, but leaving the lattice invariant. The other is to restrict to point symmetries, but to allow them to also transform the lattice.Comment: Review articl

    Acceptability and feasibility of a national essential medicines list in Canada: a qualitative study of perceptions of decision-makers and policy stakeholders.

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    BACKGROUND: Policy approaches have been considered to address inconsistent and inequitable prescription drug coverage in Canada, including a national essential medicines list. We sought to explore key factors influencing the acceptability and feasibility of an essential medicines list in Canada. METHODS: We conducted semi-structured interviews with decision-makers and other key stakeholders from government or pan-Canadian institutions, civil society and the private sector across Canada. We analyzed data using inductive thematic analysis and by applying Kingdon's Multiple Streams Framework to analyze the emergent themes deductively. RESULTS: We conducted 21 interviews before thematic saturation was achieved. We categorized emergent themes to describe the problem, the essential medicines list policy (including content and process), and politics. There was consensus among participants that prescription drug coverage was an important problem to address. Participants differed in their views on how to define essential medicines and concerns about what would be excluded from an essential medicines list. There was consensus on important features for a process to develop an essential medicines list: an independent decision-making body, use of defined selection criteria based on quality evidence, and clear communication of the purpose of the essential medicines list. Federal government financing and the broader pharmacare model, engagement of various interest groups and changing political agendas emerged as core political factors to consider if developing a Canadian essential medicines list. INTERPRETATION: Although stakeholders' views on the content of a Canadian essential medicines list varied, there was consensus on the process to formulate and implement an essential medicines list or common national formulary, including choosing medicines based on best evidence. Greater understanding is now needed on how patients, clinicians and the public perceive the concept of an essential medicines list

    Selection of WHO-recommended essential medicines for non-communicable diseases on National Essential Medicines Lists.

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    BACKGROUND: Non-communicable diseases (NCDs) are the leading cause of death worldwide. Inadequate and inequitable access to essential NCD medicines is a major concern, particularly in low- and middle-income countries. National Essential Medicines Lists (EMLs) are important policy tools that indicate which medicines are prioritized as essential within a country's health system. This study sought to analyze a wide range of national essential medicines lists (EMLs) for their inclusion of priority non communicable disease (NCD) interventions recommended by the World Health Organization (WHO). METHODS: Three lists of WHO endorsed priority NCD interventions were included. A database with 137 national EMLs and the WHO EML was created from the WHO Repository and these EMLs were compared for listing of priority NCD interventions. RESULTS: Across 137 countries with national EMLs, the median percentage of 20 Best Buys interventions listed was 90% (IQR 80-95) and 31 Package of essential noncommunicable disease interventions (PEN) interventions listed was 94% (IQR 90-97), of 9 HEARTS interventions was 100% (IQR 89-100), and of the 43 unique interventions across the three priority lists was 88% (IQR 84-93). Less than 80% of the 43 interventions were listed by 22 (16%) countries and less than half of the interventions were listed by 2 countries: Angola (35%) and Cambodia (23%). Interventions listed on the fewest number of national EMLs were: influenza vaccine, HPV vaccine, hepatitis B vaccine, cervical cancer chemotherapy, codeine, promethazine, senna, and oxygen. CONCLUSION: Most NCD interventions have been prioritized in national policy in most cases. The majority of priority medicines for NCDs described within key WHO NCD technical packages are listed on nearly all national EMLs across 137 countries of all income levels. Most NCD interventions have been prioritized in national policy in most cases, but in some countries and for select interventions such as the HPV vaccine, prioritization may be reviewed

    HI intensity mapping with the MIGHTEE survey: power spectrum estimates

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    Intensity mapping (IM) with neutral hydrogen is a promising avenue to probe the large scale structure of the Universe. With MeerKAT single-dish measurements, we are constrained to scales >1>1 degree, and this will allow us to set important constraints on the Baryon acoustic oscillations and redshift space distortions. However, with MeerKAT's interferometric observation, we can also probe relevant cosmological scales. In this paper, we establish that we can make a statistical detection of HI with one of MeerKAT's existing large survey projects (MIGHTEE) on semi-linear scales, which will provide a useful complementarity to the single-dish IM. We present a purpose-built simulation pipeline that emulates the MIGHTEE observations and forecast the constraints that can be achieved on the HI power spectrum at z=0.27z = 0.27 for k>0.3k > 0.3 Mpc1\rm{Mpc}^{-1} using the foreground avoidance method. We present the power spectrum estimates with the current simulation on the COSMOS field that includes contributions from HI, noise and point source models from the data itself. The results from our \textit{visibility} based pipeline are in good agreement to the already available MIGHTEE data. This paper demonstrates that MeerKAT can achieve very high sensitivity to detect HI with the full MIGHTEE survey on semi-linear scales (signal-to-noise ratio >7> 7 at k=0.49k=0.49 Mpc1\rm{Mpc}^{-1}) which are instrumental in probing cosmological quantities such as the spectral index of fluctuation, constraints on warm dark matter, the quasi-linear redshift space distortions and the measurement of the HI content of the Universe up to z0.5z\sim 0.5.Comment: 12 pages, 8 figures, Submitted to MNRAS, comments welcom

    MIGHTEE polarization early science fields: the deep polarized sky

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    The MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) is one of the MeerKAT large survey projects, designed to pathfind SKA key science. MIGHTEE is undertaking deep radio imaging of four well-observed fields (COSMOS, XMM-LSS, ELAIS S1, and CDFS) totaling 20 square degrees to μJy sensitivities. Broad-band imaging observations between 880 and1690 MHz yield total intensity continuum, spectro-polarimetry, and atomic hydrogen spectral imaging. Early science data from MIGHTEE are being released from initial observations of COSMOS and XMM–LSS. This paper describes the spectro-polarimetric observations, the polarization data processing of the MIGHTEE early science fields, and presents polarization data images and catalogues. The catalogues include radio spectral index, redshift information, and Faraday rotation measure synthesis results for 13 267 total intensity radio sources down to a polarized intensity detection limit of ∼20 μJy bm−1. Polarized signals were detected from 324 sources. For the polarized detections, we include a catalogue of Faraday Depth from both Faraday Synthesis and Q, U fitting, as well as total intensity and polarization spectral indices. The distribution of redshift of the total radio sources and detected polarized sources are the same, with median redshifts of 0.86 and 0.82, respectively. Depolarization of the emission at longer-wavelengths is seen to increase with decreasing total-intensity spectral index, implying that depolarization is intrinsic to the radio sources. No evidence is seen for a redshift dependence of the variance of Faraday depth

    Energy Response and Longitudinal Shower Profiles Measured in CMS HCAL and Comparison With Geant4

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    The response of the CMS combined electromagnetic and hadron calorimeter to beams of pions with momenta in the range 5-300 GeV/c has been measured in the H2 test beam at CERN. The raw response with the electromagnetic compartment calibrated to electrons and the hadron compartment calibrated to 300 GeV pions may be represented by sigma = (1.2) sqrt{E} oplus (0.095) E. The fraction of energy visible in the calorimeter ranges from 0.72 at 5 GeV to 0.95 at 300 GeV, indicating a substantial nonlinearity. The intrinsic electron to hadron ratios are fit as a function of energy and found to be in the range 1.3-2.7 for the electromagnetic compartment and 1.4-1.8 for the hadronic compartment. The fits are used to correct the non-linearity of the e pi response to 5% over the entire measured range resulting in a substantially improved resolution at low energy. Longitudinal shower profile have been measured in detail and compared to Geant4 models, LHEP-3.7 and QGSP-2.8. At energies below 30 GeV, the data, LHEP and QGSP are in agreement. Above 30 GeV, LHEP gives a more accurate simulation of the longitudinal shower profile

    Design, Performance, and Calibration of CMS Hadron Endcap Calorimeters

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    Detailed measurements have been made with the CMS hadron calorimeter endcaps (HE) in response to beams of muons, electrons, and pions. Readout of HE with custom electronics and hybrid photodiodes (HPDs) shows no change of performance compared to readout with commercial electronics and photomultipliers. When combined with lead-tungstenate crystals, an energy resolution of 8\% is achieved with 300 GeV/c pions. A laser calibration system is used to set the timing and monitor operation of the complete electronics chain. Data taken with radioactive sources in comparison with test beam pions provides an absolute initial calibration of HE to approximately 4\% to 5\%

    Design, Performance, and Calibration of the CMS Hadron-Outer Calorimeter

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    The CMS hadron calorimeter is a sampling calorimeter with brass absorber and plastic scintillator tiles with wavelength shifting fibres for carrying the light to the readout device. The barrel hadron calorimeter is complemented with an outer calorimeter to ensure high energy shower containment in the calorimeter. Fabrication, testing and calibration of the outer hadron calorimeter are carried out keeping in mind its importance in the energy measurement of jets in view of linearity and resolution. It will provide a net improvement in missing \et measurements at LHC energies. The outer hadron calorimeter will also be used for the muon trigger in coincidence with other muon chambers in CMS
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