12 research outputs found
Reconciling dynamic and seismic models of Earth's lower mantle: The dominant role of thermal heterogeneity
No full textInternational audienceTwo large low-shear-velocity provinces (LLSVPs) in the deep mantle beneath Africa and the Pacific are generally interpreted as hot but chemically dense ‘piles’, which have remained isolated from mantle circulation for several hundred million years. This interpretation largely hinges on four seismic observations: (i) their shear wave velocity anomalies are considered too large for purely thermal structures; (ii) shear wave velocity gradients at their edges are sharp; (iii) their shear to compressional wave-speed anomaly ratios are high; and (iv) their shear and bulk-sound velocity anomalies appear to be anti-correlated. However, using compressible global mantle circulation models driven by 300 Myr of plate motion history and thermodynamic methods for converting from physical to seismic structure, we show that observed lower mantle shear wave velocity anomalies do not require, and are most likely incompatible with, large-scale chemical ‘piles’. A prescribed core-mantle-boundary temperature of 4000 K, which is consistent with current estimates, combined with anelastic seismic sensitivity to temperature, ensures that purely thermal LLSVPs, strongly focussed beneath Africa and the Pacific by subduction history, can reconcile observed shear wave velocity anomalies and gradients. By contrast, shear wave velocity anomalies from models that include dense chemical ‘piles’ at the base of Earth's mantle, where ‘piles’ correspond to only 3% of the mantle's volume, are substantially stronger than the tomographic model S40RTS, even after accounting for limited tomographic resolution. Our results also suggest that in the presence of post-perovskite, elevated ratios between shear and compressional wave-speed anomalies and the correlation between shear and bulk-sound velocity anomalies cannot be used to discriminate between thermal and compositional heterogeneity at depth: in all calculations, an anti-correlation only occurs within the post-perovskite stability field. Taken together, this implies that although there must be considerable chemical heterogeneity within Earth's mantle, large, coherent ‘piles’ are not required to reconcile the seismic observations examined here. Indeed, our results suggest that if chemical heterogeneity is present in these regions, its dynamical and seismic significance is far less than has previously been inferred
On the role of thermal heterogeneities on the rheology of MgO under conditions of the Earth’s lower mantle
No full textAbstractThe Earth’s mantle is characterised by large thermal heterogeneities associated with hot rising plumes and cold downwelling slabs. These lateral temperature variations in excess of 1000K may have a crucial influence on the rheology of mantle rocks. Here we use a numerical multiscale model that allows us to make predictions from first principles with no adjustable parameters on the deformation of MgO under the extreme conditions of mantle pressure, temperature and strain rate, in order to investigate the sensitivity of mantle viscosity to the temperature heterogeneities inferred from a global high resolution mantle circulation model. Our results show that under the very low strain rates of the mantle, MgO deforms mostly at low stresses (few tens of MPa) in an athermal regime, where the deformation is insensitive to both temperature and strain rate, leading to a very weak phase throughout much of the upper half of the lower mantle. In its lower half, the weak phase gives way to high material strength with thermally activated viscosities in the cold downwelling slabs, while much of the hot upwelling flow remains in the athermal regime, resulting in large lateral variations in the inferred material strength of MgO. Our results suggest the presence of large lateral viscosity variations in the deepest parts of the lower mantle, associated in particular with the graveyard of old subducted oceanic lithosphere
Testing absolute plate reference frames and the implications for the generation of geodynamic mantle heterogeneity structure
No full textInternational audienceAbsolute reference frames are a means of describing the motion of plates on the surface of the Earth over time, relative to a fixed point or “frame.” Multiple models of absolute plate motion have been proposed for the Cretaceous–Tertiary period, however, estimating the robustness and limitations of each model remains a significant limitation for refining both regional and global models of plate motion as well as fully integrated and time dependent geodynamic models. Here, we use a novel approach to compare five models of absolute plate motion in terms of their consequences for forward modelled deep mantle structure since at least 140 Ma. We show that the use of hotspots, either fixed or moving, or palaeomagnetics, with or without corrections for true-polar wander, leads to significant differences in palaeo-plate velocities of over 10 cm/yr as well as differences in the location of palaeo-plate boundaries of up to 30° in longitude and latitude. Furthermore, we suggest that first order differences in forward predicted mantle structure between the models are due mostly to differences in palaeo-plate velocities, whereas variation in the location of plate boundaries may contribute to smaller wavelength offsets. We present a global comparison of the absolute reference frames in terms of mantle structure, which we have tomographically filtered to reflect the resolution of the seismic tomography model S20RTS. At very long wavelengths hotspot models best reproduce the mantle structure. However, when geometry and the match of smaller-scale subducted slab volumes are compared, a hybrid model based on moving hotspots after 100 Ma and palaeomagnetic data before (with no corrections for true-polar wander), best reproduces the overall mantle structure of slab burial grounds, even though no single model fits best at all mantle depths. We find also that the published subduction reference frame tested here results in a modelled mantle structure that agrees well with S20RTS for depths > 2500 km, equivalent to subduction before the Cretaceous, but not for shallower depths. This indicates that a careful assimilation of hotspot, palaeomagnetic and seismic tomography data into future absolute plate motion models is required to derive a more robust subduction reference frame
Constraints on the presence of post-perovskite in Earth's lowermost mantle from tomographic-geodynamic model comparisons
No full textLower mantle tomography models consistently feature an increase in the ratio of shear-wave velocity (VS) to compressional-wave velocity (VP) variations and a negative correlation between shear-wave and bulk-sound velocity (VC) variations. These seismic characteristics, also observed in the recent SP12RTS model, have been interpreted to be indicative of large-scale chemical variations. Other explanations, such as the lower mantle post-perovskite (pPv) phase, which would not require chemical heterogeneity, have been explored less. Constraining the origin of these seismic features is important, as geodynamic simulations predict a fundamentally different style of mantle convection under both scenarios. Here, we investigate to what extent the presence of pPv explains the observed high VS/VP ratios and negative VS–VC correlation globally. We compare the statistical properties of SP12RTS with the statistics of synthetic tomography models, derived from both thermal and thermochemical models of 3-D global mantle convection. We convert the temperature fields of these models into seismic velocity structures using mineral physics lookup tables with and without pPv. We account for the limited tomographic resolution of SP12RTS using its resolution operator for both VS and VP structures. This allows for direct comparisons of the resulting velocity ratios and correlations. Although the tomographic filtering significantly affects the synthetic tomography images, we demonstrate that the effect of pPv remains evident in the ratios and correlations of seismic velocities. We find that lateral variations in the presence of pPv have a dominant influence on the VS/VP ratio and VS–VC correlation, which are thus unsuitable measures to constrain the presence of large-scale chemical variations in the lowermost mantle. To explain the decrease in the VS/VP ratio of SP12RTS close to the CMB, our results favour a pPv-bearing CMB region, which has implications for the stability field of pPv in the Earth's mantle
Automated scan-vs-BIM registration using columns segmented by deep learning for construction progress monitoring:“This paper is based on the MSc thesis of the first author.”
No full textIn construction automation applications, coarse registration between 3D Building Information Modelling (BIM) and the as-built point cloud is vital for the monitoring of construction progress. This can be achieved by extracting highly distinct geometric features in both datasets to speed up the correspondence search. However, the existing geometric feature-based coarse registration methods have limitations in the Architecture, Engineering, Construction & Facility Management (AEC/FM) context because building designs often contain a considerable self-similarity, symmetry, and lack of texture. In this work, we propose an automatic coarse registration method that is motivated by the Random Sample Consensus (RANSAC) algorithm to estimate the transformation parameters that best align the as-built point cloud in the coordinate frame of the BIM model by matching the corresponding columns. The method is based on the extraction of columns from the as-built point cloud and the as-planned BIM model. For the point cloud data, fully automated column extraction techniques are used by applying deep learning, whereas the BIM model columns are extracted from the available semantic information. Experiments are carried out on real-life datasets from the building construction site to validate the proposed method. The results show that our proposed column-based registration method achieved an RMSE of 2 centimeters, and the cloud-to-cloud mean distance of 1.6cm ± 1.8cm after fine registration. The accuracy of the co-registration result shows that our proposed approach contributes to automating the registration between the as-built point cloud and the as-planned BIM model for construction progress monitoring.</p
Behind the medical mask : medical technology and medical power
No full textThis thesis explores the role of technology as a resource in the
structure of medical domination of birth and death, stressing
technology's pivotal position at the intersection of control and
uncertainty.
Based in Intensive Care and Obstetrics (between which the health status
of patients diverges sharply), it notes the convergence of technology
used and examines the contest for control within the labour process.
This includes using technology to facilitate a 'standardized' birth or
death; a more retrospectively defensible event. In general, the
'burden of proof' is concluded to lie with those wishing not to
intervene rather than the reverse.
Given the (cognitively male) biomedical model, mind-body dualism is an
assumption embedded in medical technology: this is especially
significant in childbirth, where it fractures the woman's ontological
experience of giving birth. Its positivistic and pathological
emphasis is associated with a reification of processes and a
commodification of their 'solution': which becomes located in
technology. It is argued that commodification in health provision will
increase with the further application of market principles to the NHS.
It is concluded that 'uncertainty', endemic to medicine and a possible
challenge to control, is proactively manipulated and pressed into the
service of medical domination. Technology is used to mask uncertainty
and aid the medical profession's control of patients/relatives, and
subordinate work groups.
A technological fix may be viewed as the opposite to re-discovering
societal dreams and myths, however, more paradoxically, it is concluded
that dreams and myths have become attached to technology. Thus, the
symbolic role of technology is: to provide hope of continued survival
(or cure), the veiling of existential uncertainty and the offer of
'absolution' - should all efforts fail (a freedom from guilt in the
assurance that "everything possible was tried"). Its 'heroic' project
is viewed as an existentially 'masculine' health provision and
'feminized' health care is posited as an alternative
Ancient goat genomes reveal mosaic domestication in the Fertile Crescent
No full textCurrent genetic data are equivocal as to whether goat domestication occurred multiple times or was a singular process. We generated genomic data from 83 ancient goats (51 with genome-wide coverage) from Paleolithic to Medieval contexts throughout the Near East. Our findings demonstrate that multiple divergent ancient wild goat sources were domesticated in a dispersed process that resulted in genetically and geographically distinct Neolithic goat populations, echoing contemporaneous human divergence across the region. These early goat populations contributed differently to modern goats in Asia, Africa, and Europe. We also detect early selection for pigmentation, stature, reproduction, milking, and response to dietary change, providing 8000-year-old evidence for human agency in molding genome variation within a partner species.ERG In grant [295729-CodeX]; Science Foundation Ireland Award [12/ERC/B2227]; HERA Joint Research Programme Uses of the Past (CitiGen); European Union [649307]; ERC Consolidator-grant [647787]; Marie Sktodowska-Curie Individual Fellowship SCRIBE H2020-MSCA-IF-2016 [747424]; Science Foundation Ireland (SFI) [12/ERC/B2227] Funding Source: Science Foundation Ireland (SFI); Marie Curie Actions (MSCA) [747424] Funding Source: Marie Curie Actions (MSCA)Supported by ERG In grant 295729-CodeX. Additional support from Science Foundation Ireland Award 12/ERC/B2227. P.M.D. was supported by the HERA Joint Research Programme Uses of the Past (CitiGen): and the European Union's Horizon 2020 research and innovation program uncle r grant agreement no. 649307. A.M. was supported by ERC Consolidator-grant 647787 Local Adraptation. M.D.T. was supported by the Marie Sktodowska-Curie Individual Fellowship SCRIBE H2020-MSCA-IF-2016 747424. Author contributions: D.G.B. conceived of the project and designed the research, wit'n input from J.B. and M.C.; C.C., RP., L.M., D.O., B.S.A., N.B., L.K.H., M.M., R.Ke.; C.M.E., G.B.O.; FP.. T.C., J.D.V., A.F.M., D.D., N.D., O.C.; R.Kh., S.B., R.R.S., A.A.V., E.W.S., H.A.K., and S.M. provided samples and data; K.G.D., V.E.M., V.M., A.S.; A.J.H., and M.D.T. performed gertomics laboratory work; P.M.D. performed ABC analyses, with input from A.M., K.G.D. and D.G.B.; K.G.D. performed the computational analyses with input from D.G.B., V.E.M., M.P.V., and M.D.Ta D.G.B. and K.G.D. wrote the paper with input from all other co-authors; K.G.D. and P.M.D. wrote the supplementary information with input from all other authors
Daily Dope (November 18, 1968)
No full textA daily newsletter with University of Lethbridge campus news."THE DAILY DOPE'
PUBLISHED DAILY BY THE UNIVERSITY OF LETHBRIDGE
FOR INTERNAL COMMUNICATION vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
NOVEMBER 18, 1968 Vol. Ill Ho. 52
OFFICIAL NOTICES
MARY ANN A, RADLEY and DAVID WILLMS, please see Mr. Lambert as soon as possible.
FINAL EXAM SCHEDULE
Preliminary Fall Semester Final Exam Schedules are now posted at strategic points on the campus. Conflicts should be reported to the Registrar's Office before Friday, November 22, at 4:30 p.m.
This is the first of THREE DRAFTS.
ATTENTION: The University will close at noon on December 24, and at
noon on December 31,
UNIVERSITY LECTURE SERIES
DATE: Tuesday, November 19 TIME: noon PL ACE: Lecture Theatre, of the
Kate Afidrews Building
SPEAKER: Dr. Robert A. Nilan TOPIC: RADIATION AND GENES with emphasis
on some of the consequences for man
DR. NILAN is Professor of Genetics, Agronomist and chairman of the Program in Genetics at Washington State University. He graduated from the University of British Columbia in 1946 (B.S.A.) and continued with graduate study at the University (M.S.A, 1948). He earned his doctorate in genetics from the University of Wisconsin (Ph.D. 1951).
Dr. Nilan is the author or co-author of over 95 articles in numerous national and international journals, and he has received professional recognition in the United States, Switzerland, East Germany, West Germany, The Netherlands, and Italy to mention a few of the countries where he has presented papers at scientific symposia.
The lecture on Tuesday will be of general interest, It will be followed in the afternoon by a more specialized seminar of interest primarily to biologists,
BOOKSTORE: Effective November 18 until November 22 inclusive (5 days), the Bookstore will not open until 9:30 a.m., one-half hour later than usual.
________________________ Over)_ _ _THE DAILY DOPE
- 2 -
NEW IN THE BOOKSTORE
Student Protest: The Student Radical In Search of Issues or, please
don't shoot the piano player. '
The Negro Pilgrimage in America. ,go
The Witnesses: Highlights of the Warren Commission on the
assassination of President Kennedy. I.00
Helen Keller: Her Socialist Years. 2.00
The University Game: A tough unsettling look at the University
in Canada. 2.40
BASKETBALL: Harlem Aces versus the Southern Alberta Chinooks, Thursday
November 21, at 8:00 p.m. in the Kate Andrews Gym.
PRICES: Adults: 1.00 Under 14 $ .75
BIOLOGY SEMINAR
TITLE: Radiation mutagenesis in plants^ control and mechanics
TIME: 4:00 p.m.
LOCATION: Room 213 of the Science Building
SPEAKER: Dr. Robert A. Nilan, Washington State University
STUDENT NOTICES
A number of typewriters are now available for the use of students. They
are located, in the basement of the Science Building and are accessible
from the main floor, west side entrance.
PLEASE DO NOT MOVE OR REMOVE THE TYPEWRITERS OR FURNITURE FROM THIS AREA.
PLEASE USE THE RECEPTACLES FOR TRASH.
PLEASE ADVISE THE SECRETARY IN ROOM 118 IF REPAIRS ARE REQUIRED.
Will the following students please call at the Cashier's window:
LA TRESA BELTS HEATHER K. MURRAY HENRY YEE
LAVON V. GARRETT KARIN C. PEDERSON PHILIP M. PASKAL
ALAN L. MATSON KATHRYN F. Yr MA SHIT A
Would the following students please contact Dr. Earl in the Student Teaching
Office as soon as possible:
CECILIA BARICH
MARNIE JO CO C HL AN
BONNIE MICHAELIS
LIS NIELSEN
ROSALIE REIMER
SANDRA GROENWOLD
HOCKEY GAME: University of Lethbridge Kod.iaks versus Labor Club, at
the Arena, today, . Monday November 18, at 8:00 p.m
Universal Patterns in Color-Emotion Associations Are Further Shaped by Linguistic and Geographic Proximity
No full textMany of us “see red,” “feel blue,” or “turn green with envy.” Are such color-emotion associations fundamental to our shared cognitive architecture, or are they cultural creations learned through our languages and traditions? To answer these questions, we tested emotional associations of colors in 4,598 participants from 30 nations speaking 22 native languages. Participants associated 20 emotion concepts with 12 color terms. Pattern-similarity analyses revealed universal color-emotion associations (average similarity coefficient r =.88). However, local differences were also apparent. A machine-learning algorithm revealed that nation predicted color-emotion associations above and beyond those observed universally. Similarity was greater when nations were linguistically or geographically close. This study highlights robust universal color-emotion associations, further modulated by linguistic and geographic factors. These results pose further theoretical and empirical questions about the affective properties of color and may inform practice in applied domains, such as well-being and design. © The Author(s) 2020
Eu sou a mulher que eu quero ser: da sua criação até a configuração da identidade como mulher
No full textThis article gives account of the author as performerin the processes of research-creation: Runway and Conversation with my shadow of the Group Pasarela2. From the personal sight look to show how the performance is a route of methodology and creation which contributes to the inquiry of oneself, for the life comprehension in the dialogue with feminist authors and women of the daily life. It narrates the way as these two processes have changed their ways of felling as woman, meeting the pleasure as a feeling which allows for independence.Este artículo expone la participación de la autora como performer en los procesos de investigación creación: Pasarela y Conversación con mi sombra del Grupo Pasarela[1]. Desde una mirada personal pretende evidenciar cómo el performance es una ruta metodológica y de creación que contribuye a la indagación de sí misma, para la comprensión de la vida, en diálogo con autoras feministas y mujeres de su vida cotidiana. Narra la manera cómo estos dos procesos han trasformado sus maneras de sentirse mujer, encontrándose con el placer como un sentimiento que permite la independencia.Este artigo dá conta da participação da autora comoperformer nos processos de criação et pesquisa: Pasarela e Conversación com mi sombra da companhia Grupo Pasarela3. De uma perspectiva pessoal quer comprovar como a performance é uma rota metodológica e de criação que contribui à sua própria investigação, para a compreensão da vida, em diálogo com as autoras feministas e as mulheres de sua vida diária. Ela narra o modo como estes dois processos tem transformado as maneiras para sentir-se mulher, descobrindo no prazer um sentimento que permite a independênci
