41,203 research outputs found

    Comment on "Under-reported data analysis with INAR-hidden Markov chains"

    Full text link
    In Fernandez-Fontelo et al (Statis. Med. 2016, DOI 10.1002/sim.7026) hidden integer-valued autoregressive (INAR) processes are used to estimate reporting probabilities for various diseases. In this comment it is demonstrated that the Poisson INAR(1) model with time-homogeneous underreporting can be expressed equivalently as a completely observed INAR(inf) model with a geometric lag structure. This implies that estimated reporting probabilities depend on the assumed lag structure of the latent process.Comment: This is the pre-reviewing version of a letter published in Statistics in Medicine 38(5), 893-898: https://onlinelibrary.wiley.com/doi/full/10.1002/sim.8032 Fernandez-Fontelo et al published a reply which raises some interesting further points: https://onlinelibrary.wiley.com/doi/10.1002/sim.8033 After a 12 month embargo period the accepted version will be made available on arxi

    First-principles study of ferroelectricity and pressure-induced phase transitions in HgTiO3_3

    Full text link
    Ground-state structure is found and pressure-induced phase transitions up to 210 kbar are studied in mercury titanate from first principles within the density functional theory. It is established that the R3cR3c structure experimentally observed in HgTiO3_3 is metastable at ambient pressure. With increasing the hydrostatic pressure, the ground-state structure changes following the R3ˉR3cPbnmR{\bar 3} \to R3c \to Pbnm sequence. It is shown that the appearance of ferroelectricity in HgTiO3_3 at P=0P = 0 is associated with an unstable phonon mode. Optical and elastic properties of different phases of mercury titanate are calculated. The quasiparticle band gap calculated in the \emph{GW} approximation (Eg=2.43E_g = 2.43 eV) agrees with experimental data better than the value obtained in the LDA approximation (1.49 eV). Analysis of the thermodynamic stability explains why the synthesis of mercury titanate is possible only at high pressures.Comment: 8 pages, 4 figures, 5 tables; to appear in Phase Transition

    The Glasgow sustainable urban drainage system management project: Case studies (Belvidere hospital and Celtic FC stadium areas)

    Get PDF
    The Glasgow Sustainable Urban Drainage System (SUDS) Management Project satisfies the first phase of the Glasgow Surface Water Management Project. This is Glasgow City Council’s contribution to the Transformation of Rural and Urban Spatial Structure (TRUST) project, one of the European Union’s (EU) interregional (INTERREG IIIB) funded research projects. The remit of this EU project comprises also other representative regions in Europe. The project shows also how SUDS can contribute to the overall catchment dynamics of cities such as Glasgow, ultimately relieving stress on the current predominantly combined sewer system. Fifty-seven sites within 46 areas of Glasgow were identified for investigation. A detailed soil chemistry analysis, a preliminary SUDS feasibility assessment and a desk study relating to historical planning issues that may be relevant for subsequent future development and regeneration options were undertaken. Detailed design and management guidelines were then drafted for selected representative demonstration areas (Belvidere Hospital and Celtic FC Stadium Areas) of high public and property developers interest, and education value. A combination of infiltration trenches or swales with ponds or underground storage were the most likely SUDS options for the majority of the demonstration areas. Soil contamination issues were considered when selecting SUDS because heavy metals such as lead and zinc can cause environmental health problems

    Nanocrystalline semiconductors: synthesis, properties, and perspectives

    Get PDF
    The preparation of hollow particles of ZnO by calcination of hydrozincite coated poly(styrene) beads is reported. Synthetic studies have been performed on such polymer/inorganic composite precursors in order to establish the optimum conditions for the preparation of the ZnO particles. The morphological properties of the powders were characterised by optical microscopy and scanning electron microscopy. The micrometric ZnO particles show morphological characteristics related to the template used in their preparation

    The Glasgow sustainable urban drainage system management project: Case studies (Belvidere hospital and Celtic FC stadium areas)

    Get PDF
    The Glasgow Sustainable Urban Drainage System (SUDS) Management Project satisfies the first phase of the Glasgow Surface Water Management Project. This is Glasgow City Council’s contribution to the Transformation of Rural and Urban Spatial Structure (TRUST) project, one of the European Union’s (EU) interregional (INTERREG IIIB) funded research projects. The remit of this EU project comprises also other representative regions in Europe. The project shows also how SUDS can contribute to the overall catchment dynamics of cities such as Glasgow, ultimately relieving stress on the current predominantly combined sewer system. Fifty-seven sites within 46 areas of Glasgow were identified for investigation. A detailed soil chemistry analysis, a preliminary SUDS feasibility assessment and a desk study relating to historical planning issues that may be relevant for subsequent future development and regeneration options were undertaken. Detailed design and management guidelines were then drafted for selected representative demonstration areas (Belvidere Hospital and Celtic FC Stadium Areas) of high public and property developers interest, and education value. A combination of infiltration trenches or swales with ponds or underground storage were the most likely SUDS options for the majority of the demonstration areas. Soil contamination issues were considered when selecting SUDS because heavy metals such as lead and zinc can cause environmental health problems

    Vaults. III. Vault ribonucleoprotein particles open into flower-like structures with octagonal symmetry.

    Get PDF
    The structure of rat liver vault ribonucleoprotein particles was examined using several different staining techniques in conjunction with EM and digestion with hydrolytic enzymes. Quantitative scanning transmission EM demonstrates that each vault particle has a total mass of 12.9 +/- 1 MD and contains two centers of mass, suggesting that each vault particle is a dimer. Freeze-etch reveals that each vault opens into delicate flower-like structures, in which eight rectangular petals are joined to a central ring, each by a thin hook. Vaults examined by negative stain and conventional transmission EM (CTEM) also reveal the flower-like structure. Trypsin treatment of vaults resulted exclusively in cleavage of the major vault protein (p104) and concurrently alters their structure as revealed by negative stain/CTEM, consistent with a localization of p104 to the flower petals. We propose a structural model that predicts the stoichiometry of vault proteins and RNA, defines vault dimer-monomer interactions, and describes two possible modes for unfolding of vaults into flowers. These highly dynamic structural variations are likely to play a role in vault function

    A failed invasion? Commercially introduced pollinators in Southern France

    Get PDF
    The natural diversity of Bombus terrestris subspecies could be under threat from the commercialisation of bumblebees. Therefore, to determine whether commercially imported bumblebees are able to establish and spread, we carried out long-term observations of bumblebees in southern France. Our surveys occurred before, during, and after the importation (between 1989 and 1996) of thousands of colonies of the Sardinian subspecies B. t. sassaricus. Queens and males of B. t. sassaricus were observed foraging outside commercial greenhouses in 1991, 1993, and 1994 and feral workers were observed foraging on native vegetation nearly two years after the importation of B. t. sassaricus ceased. However, no B. t. sassaricus, or F1 hybrids were observed after 1998. We conclude that B. t. sassaricus remains inconspicuous in France and competition from the three native subspecies may have prevented it from becoming invasive. However, genetic interference through introgression cannot be ruled out

    Dyspraxia in a patient with corticobasal degeneration: the role of visual and tactile inputs to action

    Get PDF
    Objectives-To investigate the roles of visual and tactile information in a dyspraxic patient with corticobasal degeneration (CBD) who showed dramatic facilitation in miming the use of a tool or object when he was given a tool to manipulate; and to study the nature of the praxic and neuropsychological deficits in CBD. Methods-The subject had clinically diagnosed CBD, and exhibited alien limb behaviour and striking ideomotor dyspraxia. General neuropsychological evaluation focused on constructional and visuospatial abilities, calculation, verbal fluency, episodic and semantic memory, plus spelling and writing because impairments in this domain were presenting complaints. Four experiments assessed the roles of visual and tactile information in the facilitation of motor performance by tools. Experiment I evaluated the patient's performance of six limb transitive actions under six conditions: (1) after he described the relevant tool from memory, (2) after he was shown a Line drawing of the tool, (3) after he was shown a real exemplar of the tool, (4) after he watched the experimenter perform the action, (5) while he was holding the tool, and (6) immediately after he had performed the action with the tool but with the tool removed from his grasp. Experiment 2 evaluated the use of the same six tools when the patient had tactile but no visual information (while he was blindfolded). Experiments 3 and 4 assessed performance of actions appropriate to the same six tools when the patient had either neutral or inappropriate tactile feedback-that is, while he was holding a non-tool object or a different tool. Results-Miming of tool use was not facilitated by visual input; moreover, lack of visual information in the blindfolded condition did not reduce performance. The principal positive finding was a dramatic facilitation of the patient's ability to demonstrate object use when he was holding either the appropriate tool or a neutral object. Tools inappropriate to the requested action produced involuntary performance of the stimulus relevant action. Conclusions-Tactile stimulation was paramount in the facilitation of motor performance in tool use by this patient with CBD. This outcome suggests that tactile information should be included in models which hypothesise modality specific inputs to the action production system. Significant impairments in spelling and letter production that have not previously been reported in CBD have also been documented
    corecore