503 research outputs found

    Late Eocene-Oligocene granulite facies garnet-sillimanite migmatites from the Mogok Metamorphic belt, Myanmar, and implications for timing of slip along the Sagaing Fault

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    MPS is grateful to the Oxford-Burma Aung San Suu Kyi trust for funding research and field visits to Mogok. U-Th-Pb geochronology was funded by UCSB and NSF grants EAR-1348003 and EAR-1551054 to BH.The Mogok Metamorphic Belt (MMB) in Myanmar is a polymetamorphic, mainly Paleogene granulite-uppermost amphibolite facies terrane consisting mainly of marbles and calc-silicates hosting spinel, ruby and sapphire. Jurassic charnockite-syenite intrusions, as well as Eocene-Miocene leucogranite intrusions are also present. Pelitic rocks are uncommon, and where present, have sillimanite, both as primary inclusions in garnet and as secondary Bt + Sil coronas around garnet. Core samples from the Kyi-Tauk-Pauk gold mine at Thabeikkiyin, north of Mandalay, are mostly Grt + Bt + Sill gneisses and migmatites with uncommon interbanded Opx + Grt + Bt gneisses. Pseudosection modelling suggests prograde garnet growth occurred by biotite-dehydration melting that reached peak P–T conditions of 870–970 °C and ~ 0.9 GPa, and was followed by garnet breakdown forming coarse retrograde Bt + Sil coronas. U[sbnd]Pb monazite data show an early high-grade granulite event at 43–32 Ma, and a later upper amphibolite sillimanite-grade event peaking at 23–20 Ma, with a change in monazite chemistry after c. 22 Ma that is consistent with fluid/(melt) interaction and garnet breakdown. Elevated Th/U ratios from ~35 to 22 Ma, and at ~18 Ma are compatible with melt influx at that time, timing that is similar to the age of the regional Kabaing leucogranite in the Mogok valley area. Our data show that peak granulite facies metamorphism along the Mogok Metamorphic belt was mainly Middle Eocene-Early Oligocene, with upper amphibolite facies metamorphism extending to earliest Miocene. The MMB is cut abruptly by the Sagaing fault, a large-scale dextral fault that extends from the Andaman Sea north to the East Himalayan syntaxis. Our new U[sbnd]Pb monazite data constrain the oldest age of initiation of the eastern branch of the cross-cutting Sagaing dextral strike-slip fault atPostprintPeer reviewe

    Promoting health workers' ownership of infection prevention and control: using Normalization Process Theory as an interpretive framework

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    Background All health workers should take responsibility for infection prevention and control (IPC). Recent reduction in key reported healthcare-associated infections in the UK is impressive, but the determinants of success are unknown. It is imperative to understand how IPC strategies operate as new challenges arise and threats of antimicrobial resistance increase. Methods The authors undertook a retrospective, independent evaluation of an action plan to enhance IPC and ‘ownership’ (individual accountability) for IPC introduced throughout a healthcare organization. Twenty purposively selected informants were interviewed. Data were analysed inductively. Normalization Process Theory (NPT) was applied to interpret the findings and explain how the action plan was operating. Findings Six themes emerged through inductive analysis. Theme 1: ‘Ability to make sense of ownership’ provided evidence of the first element of NPT (coherence). Regardless of occupational group or seniority, informants understood the importance of IPC ownership and described what it entailed. They identified three prerequisites: ‘Always being vigilant’ (Theme 2), ‘Importance of access to information’ (Theme 3) and ‘Being able to learn together in a no-blame culture’ (Theme 4). Data relating to each theme provided evidence of the other elements of NPT that are required to embed change: planning implementation (cognitive participation), undertaking the work necessary to achieve change (collective action), and reflection on what else is needed to promote change as part of continuous quality improvement (reflexive monitoring). Informants identified barriers (e.g. workload) and facilitators (clear lines of communication and expectations for IPC). Conclusion Eighteen months after implementing the action plan incorporating IPC ownership, there was evidence of continuous service improvement and significant reduction in infection rates. Applying a theory that identifies factors that promote/inhibit routine incorporation (‘normalization’) of IPC into everyday health care can help explain the success of IPC initiatives and inform implementation

    Animal-side serologic assay for rapid detection of Mycobacterium bovis infection in multiple species of free-ranging wildlife

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    Numerous species of mammals are susceptible to Mycobacterium bovis, the causative agent of bovine tuberculosis (TB). Several wildlife hosts have emerged as reservoirs of M. bovis infection for domestic livestock in different countries. In the present study, blood samples were collected from Eurasian badgers (n=1532), white-tailed deer (n=463), brushtail possums (n=129), and wild boar (n=177) for evaluation of antibody responses to M. bovis infection by a lateral-flow rapid test (RT) and multiantigen print immunoassay (MAPIA). Magnitude of the antibody responses and antigen recognition patterns varied among the animals as determined by MAPIA; however, MPB83 was the most commonly recognized antigen for each host studied. Other seroreactive antigens included ESAT-6, CFP10, and MPB70. The agreement of the RT with culture results varied from 74% for possums to 81% for badgers to 90% for wild boar to 97% for white-tailed deer. Small numbers of wild boar and deer exposed to M. avium infection or paratuberculosis, respectively, did not cross-react in the RT, supporting the high specificity of the assay. In deer, whole blood samples reacted similarly to corresponding serum specimens (97% concordance), demonstrating the potential for field application. As previously demonstrated for badgers and deer, antibody responses to M. bovis infection in wild boar were positively associated with advanced disease. Together, these findings suggest that a rapid TB assay such as the RT may provide a useful screening tool for certain wildlife species that may be implicated in the maintenance and transmission of M. bovis infection to domestic livestock.The authors are grateful to Peter Andersen and Jim McNair for kindly providing certain antigens used in C this study. Badger samples were taken under projects funded by the Department for Environment, Food, and Rural Affairs (Defra), UK. The authors acknowledge the support of staff from CSL, VLA Starcross, Defra Wildlife Unit, and permission from the Independent Scientific Group for use of sera from the RBCT. Spanish wild boar samples were obtained with support from MEC Plan Nacional AGL2005-07401 and Santander - Fundacion M. Botin

    Low thrust propulsion in a coplanar circular restricted four body problem

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    This paper formulates a circular restricted four body problem (CRFBP), where the three primaries are set in the stable Lagrangian equilateral triangle configuration and the fourth body is massless. The analysis of this autonomous coplanar CRFBP is undertaken, which identies eight natural equilibria; four of which are close to the smaller body, two stable and two unstable, when considering the primaries to be the Sun and two smaller bodies of the solar system. Following this, the model incorporates `near term' low-thrust propulsion capabilities to generate surfaces of articial equilibrium points close to the smaller primary, both in and out of the plane containing the celestial bodies. A stability analysis of these points is carried out and a stable subset of them is identied. Throughout the analysis the Sun-Jupiter-Asteroid-Spacecraft system is used, for conceivable masses of a hypothetical asteroid set at the libration point L4. It is shown that eight bounded orbits exist, which can be maintained with a constant thrust less than 1:5 10􀀀4N for a 1000kg spacecraft. This illustrates that, by exploiting low-thrust technologies, it would be possible to maintain an observation point more than 66% closer to the asteroid than that of a stable natural equilibrium point. The analysis then focusses on a major Jupiter Trojan: the 624-Hektor asteroid. The thrust required to enable close asteroid observation is determined in the simplied CRFBP model. Finally, a numerical simulation of the real Sun-Jupiter-624 Hektor-Spacecraft is undertaken, which tests the validity of the stability analysis of the simplied model

    Selecting superluminous supernovae in faint galaxies from the first year of the Pan-STARRS1 Medium Deep Survey

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    The Pan-STARRS1 (PS1) survey has obtained imaging in five bands (griz yP1) over 10 Medium Deep Survey (MDS) fields covering a total of 70 square degrees. This paper describes the search for apparently hostless supernovae (SNe) within the first year of PS1 MDS data with an aim of discovering superluminous supernovae (SLSNe). A total of 249 hostless transients were discovered down to a limiting magnitude of MAB ∼ 23.5, of which 76 were classified as Type Ia supernovae (SNe Ia). There were 57 SNe with complete light curves that are likely core-collapse SNe (CCSNe) or type Ic SLSNe and 12 of these have had spectra taken. Of these 12 hostless, non-Type Ia SNe, 7 were SLSNe of type Ic at redshifts between 0.5 and 1.4. This illustrates that the discovery rate of type Ic SLSNe can be maximized by concentrating on hostless transients and removing normal SNe Ia. We present data for two possible SLSNe; PS1-10pm (z = 1.206) and PS1-10ahf (z = 1.1), and estimate the rate of type Ic SLSNe to be between 3+3−2×10−5 and 8+2−1×10−5 that of the CCSN rate within 0.3 ≤ z ≤ 1.4 by applying a Monte Carlo technique. The rate of slowly evolving, type Ic SLSNe (such as SN2007bi) is estimated as a factor of 10 lower than this range

    Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

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    Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization
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