569 research outputs found
A Kucha\v{r} Hypertime Formalism For Cylindrically Symmetric Spacetimes With Interacting Scalar Fields
The Kucha\v{r} canonical transformation for vacuum geometrodynamics in the
presence of cylindrical symmetry is applied to a general non-vacuum case. The
resulting constraints are highly non-linear and non-local in the momenta
conjugate to the Kucha\v{r} embedding variables. However, it is demonstrated
that the constraints can be solved for these momenta and thus the dynamics of
cylindrically symmetric models can be cast in a form suitable for the
construction of a hypertime functional Schr\"odinger equation.Comment: 5 pages, LaTeX, UBCTP-93-02
Seismic tomographic imaging of the Eastern Mediterranean Mantle: Implications for terminal-stage subduction, the uplift of Anatolia, and the development of the North Anatolian Fault
The Eastern Mediterranean captures the eastwest transition from active subduction of Earth'soldest oceanic lithosphere to continental collision, making it an ideal location to study terminalstagesubduction. Asthenospheric or subductionrelated processes are the main candidates for the region's âŒ2kmuplift and Miocene volcanism; however, their relative importance is debated. To address these issues, wepresent new P and S wave relative arrivaltime tomographic models that reveal fast anomalies associatedwith an intact Aegean slab in the west, progressing to a fragmented, partially continental, Cyprean slabbelow central Anatolia. We resolve a gap between the Aegean and Cyprean slabs, and a horizontal tear in theCyprean slab below the Central Anatolian Volcanic Province. Below eastern Anatolia, the completelydetached âBitlisâ slab is characterized by fast wave speeds at âŒ500 km depth. Assuming slab sinkingrates mirror ArabiaAnatolia convergence rates, the Bitlis slab's location indicates an Oligocene (âŒ26 Ma)breakoff. Results further reveal a strong velocity contrast across the North Anatolian Fault likelyrepresenting a 40â60 km decrease in lithospheric thickness from the Precambrian lithosphere north of thefault to a thinned Anatolian lithosphere in the south. Slow uppermostmantle wave speeds below activevolcanoes in eastern Anatolia, and ratios of P to S wave relative traveltimes, indicate a thin lithosphere andmelt contributions. Positive central and eastern Anatolian residual topography requires additional supportfrom hot/buoyant asthenosphere to maintain the 1â2 km elevation in addition to an almost absentlithospheric mantle. Smallscale fast velocity structures in the shallow mantle above the Bitlis slab maytherefore be drips of Anatolian lithospheric mantle
Management of tuberculosis by healthcare practitioners in Pakistan: A systematic review
Objective: To assess the quality of tuberculosis (TB) care in Pakistan, through determining comparison of healthcare practitionersâ knowledge and practices to national and international TB care guidelines. Methods: Studies reporting on knowledge, attitudes and practices of public and private practitioners with TB patients were selected through searching electronic databases and grey literature. Findings: Of 1458 reports, 20 full-texts were assessed, of which 11 met the eligibility and quality criteria; all studies focused on private sector care. Heterogeneity precluded meta-analysis. In 3 of 4 studies, over 50% of practitioners correctly identified a cough as the main TB symptom. However, 4 out of 6 studies showed practitionersâ compliance to be low (under 50%) for the use of sputum microscopy in diagnosis. The poorest quality care occurred in the later stages of treatment, with low compliance in prescribing practices for continuation-phase care and in monitoring and recording treatment progress, the latter of which is particularly critical for treatment success. Conclusion: TB care was variable and generally inadequate, with both a lack of knowledge and a small âknow-doâ gap evidentâpractitioners did not use methods that they know they should use. A lack of recent evidence found suggests that the quality of current practices may not be fully captured and further research is needed, especially on non-allopathic, rural and public-sector contexts. Improved training of practitioners, greater availability of recommended diagnostic tools and expansion of public-private partnerships are suggestions for improving the quality of TB care in Pakistan
Somewhere in Europe (1947): locating Hungary within a shifting geopolitical landscape
Somewhere in Europe/Valahol EurĂłpĂĄban (RadvĂĄnyi, 1947) was one of the first films made in Hungary after 1945. Financed by the Hungarian Communist Party (MKP), it loudly proclaimed a broad European pertinence in an effort to privilege the universal narrative of childhoods disrupted by the war over narrowly national political concerns. The filmâs story of a gang of half-starved children battling for survival in a bombed-out Central European landscape places it squarely within a transnational post-war film-making tradition. Similarities with both Italian neorealism and Soviet socialist realist cinema indicate a shared European experience of the war, but is also attributable to the international training and experience of the filmâs personnel. The director RadvĂĄnyi had worked in the Italian industry, while the scriptwriter was the well-known film theorist BĂ©la BalĂĄzs, who had worked in Weimar Germany and Soviet Russia. This article argues that in spite of its ostensible commitment to a communist and humanist ideology, the film gives an insight into the Hungarian national obsession with territorial integrity. Hungaryâs participation in World War II on the side of the Axis, and its position as a defeated nation under Allied occupation, are seen to complicate the film text. This article contends that in spite its transnational flavour, the filmâs focus on lost children wandering a borderless Europe suggests a preoccupation with the countryâs uncertain position within a shifting geopolitical landscape. In turn, the filmâs official reading by NemeskĂŒrty shows an eagerness to accept the filmâs representation of Hungary as a blameless victim of the war, and gives evidence of a need to insert a (false) break between the countryâs wartime past as a member of the Axis, and the countryâs 1968 present as a member of the Communist world order
An innovative solution for earthquake resistance hybrid steel âconcrete systems with replaceable dissipative steel links
In this work innovative hybrid coupled shear walls (HCSW) are considered, their design is discussed, their efficiency and limitations evaluated by means of nonlinear static (pushover) analysis. Different numbers of storeys, wall geometries and design assumptions are studied in order to give an overview of situations of interest in European seismic prone areas. The design of an experimental test regarding the performance of the connection of a seismic link embedded in a concrete shear wall is presented. This study is part of a larger research project named INNO-HYCO (INNOvative HYbrid and COmposite steel-concrete structural solutions for building in seismic area) funded by the European Commission
A comparison of three data-poor stock assessment methods for the pink spiny lobster fishery in Mauritania
Several data-poor stock assessment methods have recently been proposed and applied
to data-poor fisheries around the world. The Mauritanian pink spiny lobster fishery
has a long history of boom and bust dynamics, with large landings, stock collapse,
and years-long fishery closures, all happening several times. In this study, we have
used catch, fishing efforts, and length-frequency data (LFD) obtained from the fishery
in its most recent period of activity, 2015â2019, and historical annual catch records
starting in 2006 to fit three data-poor stock assessment methods. These were the
length-based Bayesian (LBB) method, which uses LFD exclusively, the Catch-only MSY
(CMSY) method, using annual catch data and assumptions about stock resilience, and
generalised depletion models in the R package CatDyn combined with Pella-Tomlinson
biomass dynamics in a hierarchical inference framework. All threemethods presented the
stock as overfished. The LBB method produced results that were very pessimistic about
stock status but whose reliability was affected by non-constant recruitment. The CMSY
method and the hierarchical combination of depletion and Pella-Tomlinson biomass
dynamics produced more comparable results, such as similar sustainable harvest rates,
but both were affected by large statistical uncertainty. Pella-Tomlinson dynamics in
particular demonstrated stock experiencing wide fluctuations in abundance. In spite of
uncertain estimates, a clear understanding of the status of the stock as overfished and
in need of a biomass rebuilding program emerged as management-useful guidance to
steer exploitation of this economically significant resource into sustainability.info:eu-repo/semantics/publishedVersio
Microstructural And Mechanical Study of The Al-20Sn (MASS%) Alloy Processed By Equal-Channel Angular Pressing By Route C
In this work, the feasibility of an Alâ20Sn (mass%) alloy to improve its mechanical properties through the Equal Channel Angular Pressing (ECAP) process is presented and discussed. Alâ20Sn (mass%) alloy samples with a square section of 16 Ă 16 mm and a length of 100 mm were subjected to the ECAP process through route C (i.e., rotation of 180 degrees between each pass). The characterization of the samples was carried out using X-ray diffraction and the sin^2(Ï) method for residual stresses. Scanning Electron Microscopy (SEM) was used to analyze the morphology and grain size. Vickers microhardness was carried out to analyze the homogeneity of the states of deformation and tensile testing to evaluate the yield strength, ultimate tensile strength and elongation. The results showed that the residual stresses were relatively low, confirming the effect of Sn as stress reliever. The grain size was refined to a sub-micron scale and a ribbon-like morphology was observed. The microhardness values of the severely deformed samples showed a significant increase when compared to the as-cast sample. The tensile tests showed an increase in the yield strength after the first pass, that doubled the yield strength of the as cast sample. A marginal increase in the yield strength after the fifth pass was observed; whilst the ductility remained very similar from 1 to 5 passes.In this work, the feasibility of an Alâ20Sn (mass%) alloy to improve its mechanical properties through the Equal Channel Angular Pressing (ECAP) process is presented and discussed. Alâ20Sn (mass%) alloy samples with a square section of 16 Ă 16 mm and a length of 100 mm were subjected to the ECAP process through route C (i.e., rotation of 180 degrees between each pass). The characterization of the samples was carried out using X-ray diffraction and the sin^2(Ï) method for residual stresses. Scanning Electron Microscopy (SEM) was used to analyze the morphology and grain size. Vickers microhardness was carried out to analyze the homogeneity of the states of deformation and tensile testing to evaluate the yield strength, ultimate tensile strength and elongation. The results showed that the residual stresses were relatively low, confirming the effect of Sn as stress reliever. The grain size was refined to a sub-micron scale and a ribbon-like morphology was observed. The microhardness values of the severely deformed samples showed a significant increase when compared to the as-cast sample. The tensile tests showed an increase in the yield strength after the first pass, that doubled the yield strength of the as cast sample. A marginal increase in the yield strength after the fifth pass was observed; whilst the ductility remained very similar from 1 to 5 passes
Deformation heterogeneity study of a 6061-T6 aluminum alloy processed by equal channel angular pressing
Among the severe plastic deformation techniques, the equal channel angular pressing
(ECAP) has drastically improved the mechanical properties of the processed alloys. However,
information regarding friction phenomenon, which modifies the deformation at the surface and the
heterogeneity microstrain state produced by the process itself, is still scarce. In the present work, the
deformation heterogeneity and the friction effect, at the surface in the bulk material of the 6061-T6
aluminum alloy processed by ECAP, is presented and discussed. The residual stress (RS)
measurements were performed by means of X-Ray diffraction. By means of synchrotron diffraction,
volumetric sections of the ECAPed samples were characterized. Finite element analysis showed a
good agreement with the experimentally obtained residual stress and microhardness mapping
results. The study also showed that the highest deformation zones were located at the outer parts of
the deformed samples (top and bottom), while the inner zone showed strain oscillations of up to
49±2 MPa.Peer ReviewedPostprint (author's final draft
Microstructural evolution and mechanical behavior of an Al-6061 alloy processed by repetitive corrugation and straightening
The repetitive corrugation and straightening process is a severe plastic deformation technique that is particularly suited to process metallic sheets. With this technique, it is possible to develop nano/ultrafine-grained structured materials, and therefore, to improve some mechanical properties such as the yield strength, ultimate tensile strength, and fatigue lifetime. In this study, an Al-6061 alloy was subjected to the repetitive corrugation and straightening process. A new corrugation die design was proposed in order to promote a heterogeneous deformation into the metallic sheet. The evolution of the mechanical properties and microstructure obtained by electron backscatter diffraction of the alloy showed a heterogeneous distribution in the grain size at the initial cycles of the repetitive corrugation and straightening process. Uniaxial tensile tests showed a significant increase in yield strength as the number of repetitive corrugation and straightening passes increased. The distribution of the plastic deformation was correlated with the hardness distribution on the surface. The hardness distribution map matched well with the heterogeneous distribution of the plastic deformation obtained by finite element simulation. A maximum average hardness (147 HV) and yield strength (385 MPa) was obtained for two repetitive corrugation and straightening cycles samplePeer ReviewedPostprint (published version
Genome sequences of six Phytophthora species threatening forest ecosystems
AbstractThe Phytophthora genus comprises of some of the most destructive plant pathogens and attack a wide range of hosts including economically valuable tree species, both angiosperm and gymnosperm. Many known species of Phytophthora are invasive and have been introduced through nursery and agricultural trade. As part of a larger project aimed at utilizing genomic data for forest disease diagnostics, pathogen detection and monitoring (The TAIGA project: Tree Aggressors Identification using Genomic Approaches; http://taigaforesthealth.com/), we sequenced the genomes of six important Phytophthora species that are important invasive pathogens of trees and a serious threat to the international trade of forest products. This genomic data was used to develop highly sensitive and specific detection assays and for genome comparisons and to make evolutionary inferences and will be useful to the broader plant and tree health community. These WGS data have been deposited in the International Nucleotide Sequence Database Collaboration (DDBJ/ENA/GenBank) under the accession numbers AUPN01000000, AUVH01000000, AUWJ02000000, AUUF02000000, AWVV02000000 and AWVW02000000
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