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The role of right and left parietal lobes in the conceptual processing of numbers
Neuropsychological and functional imaging studies have associated the conceptual processing of numbers with bilateral parietal regions (including intraparietal sulcus). However, the processes driving these effects remain unclear because both left and right posterior parietal regions are activated by many other conceptual, perceptual, attention, and response-selection processes. To dissociate parietal activation that is number-selective from parietal activation related to other stimulus or response-selection processes, we used fMRI to compare numbers and object names during exactly the same conceptual and perceptual tasks while factoring out activations correlating with response times. We found that right parietal activation was higher for conceptual decisions on numbers relative to the same tasks on object names, even when response time effects were fully factored out. In contrast, left parietal activation for numbers was equally involved in conceptual processing of object names. We suggest that left parietal activation for numbers reflects a range of processes, including the retrieval of learnt facts that are also involved in conceptual decisions on object names. In contrast, number selectivity in right parietal cortex reflects processes that are more involved in conceptual decisions on numbers than object names. Our results generate a new set of hypotheses that have implications for the design of future behavioral and functional imaging studies of patients with left and right parietal damage
Polar Bear Conservation in Canada: Defining the Policy Problems
Conservation of polar bears (Ursus maritimus) in Canada is based on the goals and principles of the 1973 International Agreement on the Conservation of Polar Bears and Their Habitat, and has long been considered an exemplar of science-based wildlife management. However, accelerating social and ecological changes in the Arctic raise questions about the polar bear management regimeâs ability to adapt successfully to new challenges. We apply the analytic framework of the policy sciences to develop a comprehensive orientation to this evolving situation, and we suggest possible ways to define and advance shared goals of stakeholders and other participants. We conclude that the decision process in polar bear management does not sufficiently foster identification and securing of common interests among participants who express multiple, competing perspectives in an arena that has been increasingly fragmented and symbolically charged by issues such as the recent listing of polar bears under the U.S. Endangered Species Act. The fundamental challenge for polar bear conservation in Canada is to design a better decision process so that it can constructively reconcile the various perspectives, demands, and expectations of stakeholders.Au Canada, la conservation des ours polaires (Ursus maritimus) respecte les objectifs et les principes de lâAccord international sur la conservation des ours blancs et leur habitat de 1973, qui est considĂ©rĂ© depuis longtemps comme un modĂšle de gestion de la faune fondĂ©e sur la science. Cependant, lâĂ©volution de plus en plus rapide des changements dâordre social et Ă©cologique dans lâArctique a pour effet de soulever des questions sur lâaptitude du rĂ©gime de gestion de lâours polaire Ă bien sâadapter aux nouveaux dĂ©fis. Nous utilisons le cadre de rĂ©fĂ©rence analytique de la science des politiques pour aboutir Ă une orientation exhaustive de cette situation en pleine Ă©volution, et nous suggĂ©rons des maniĂšres possibles de dĂ©finir et de formuler des objectifs partagĂ©s par les parties prenantes et dâautres participants. Nous concluons que le processus de dĂ©cision en matiĂšre de gestion de lâours polaire nâencourage pas suffisamment lâidentification et lâengagement dâintĂ©rĂȘts communs entre les participants qui expriment des perspectives multiples et concurrentes dans un domaine de plus en plus fragmentĂ© et symboliquement caractĂ©risĂ© par des enjeux tels que la liste rĂ©cente dâours polaires en vertu de la loi amĂ©ricaine sur les espĂšces en voie de disparition (U.S. Endangered Species Act). Le dĂ©fi fondamental en ce qui a trait Ă la conservation des ours polaires au Canada consiste Ă concevoir un meilleur processus de dĂ©cision pouvant rĂ©concilier, de maniĂšre constructive, les diverses perspectives, exigences et attentes des parties prenantes
M22: A [Fe/H] Abundance Range Revealed
Intermediate resolution spectra at the Ca II triplet have been obtained for
55 candidate red giants in the field of the globular cluster M22 with the
VLT/FORS instrument. Spectra were also obtained for a number of red giants in
standard globular clusters to provide a calibration of the observed line
strengths with overall abundance [Fe/H]. For the 41 M22 member stars that lie
within the V-V_HB bounds of the calibration, we find an abundance distribution
that is substantially broader than that expected from the observed errors
alone. We argue that this broad distribution cannot be the result of
differential reddening. Instead we conclude that, as has long been suspected,
M22 is similar to omega Cen in having an intrinsic dispersion in heavy element
abundance. The observed M22 abundance distribution rises sharply to a peak at
[Fe/H] = -1.9 with a broad tail to higher abundances: the highest abundance
star in our sample has [Fe/H] = -1.45 dex. If the unusual properties of omega
Cen have their origin in a scenario in which the cluster is the remnant nucleus
of a disrupted dwarf galaxy, then such a scenario likely applies also to M22.Comment: 29 pages, 9 figures, accepted for publication in the Astrophysical
Journa
Relativistic Aharonov-Casher Phase in Spin One
The Aharonov-Casher (AC) phase is calculated in relativistic wave equations
of spin one. The AC phase has previously been calculated from the Dirac-Pauli
equation using a gauge-like technique \cite{MK1,MK2}. In the spin-one case, we
use Kemmer theory (a Dirac-like particle theory) to calculate the phase in a
similar manner. However the vector formalism, the Proca theory, is more widely
known and used. In the presence of an electromagnetic field, the two theories
are `equivalent' and may be transformed into one another. We adapt these
transformations to show that the Kemmer theory results apply to the Proca
theory. Then we calculate the Aharonov-Casher phase for spin-one particles
directly in the Proca formalism.Comment: 12 page
The thick disk rotation-metallicity correlation as a fossil of an "inverse chemical gradient" in the early Galaxy
The thick disk rotation--metallicity correlation, \partial
V_\phi/\partial[Fe/H] =40\div 50 km s^{-1}dex^{-1} represents an important
signature of the formation processes of the galactic disk. We use
nondissipative numerical simulations to follow the evolution of a Milky Way
(MW)-like disk to verify if secular dynamical processes can account for this
correlation in the old thick disk stellar population. We followed the evolution
of an ancient disk population represented by 10 million particles whose
chemical abundances were assigned by assuming a cosmologically plausible radial
metallicity gradient with lower metallicity in the inner regions, as expected
for the 10-Gyr-old MW. Essentially, inner disk stars move towards the outer
regions and populate layers located at higher |z|. A rotation--metallicity
correlation appears, which well resembles the behaviour observed in our Galaxy
at a galactocentric distance between 8 kpc and 10 kpc. In particular,we measure
a correlation of \partial V_\phi/\partial[Fe/H]\simeq 60 km s^{-1}dex^{-1} for
particles at 1.5 kpc < |z| < 2.0 kpc that persists up to 6 Gyr. Our pure N-body
models can account for the V_\phi vs. [Fe/H] correlation observed in the thick
disk of our Galaxy, suggesting that processes internal to the disk such as
heating and radial migration play a role in the formation of this old stellar
component. In this scenario, the positive rotation-metallicity correlation of
the old thick disk population would represent the relic signature of an ancient
"inverse" chemical (radial) gradient in the inner Galaxy, which resulted from
accretion of primordial gas.Comment: Accepted for publication on Astronomy and Astrophysic
A Catalog of HI Clouds in the Large Magellanic Cloud
A 21 cm neutral hydrogen interferometric survey of the Large Magellanic Cloud
(LMC) combined with the Parkes multi-beam HI single-dish survey clearly shows
that the HI gas is distributed in the form of clumps or clouds. The HI clouds
and clumps have been identified using a thresholding method with three separate
brightness temperature thresholds (). Each catalog of HI cloud candidates
shows a power law relationship between the sizes and the velocity dispersions
of the clouds roughly following the Larson Law scaling , with steeper indices associated with dynamically hot regions. The
clouds in each catalog have roughly constant virial parameters as a function
mass suggesting that that the clouds are all in roughly the same dynamical
state, but the values of the virial parameter are significantly larger than
unity showing that turbulent motions dominate gravity in these clouds. The mass
distribution of the clouds is a power law with differential indices between
-1.6 and -2.0 for the three catalogs. In contrast, the distribution of mean
surface densities is a log-normal distribution.Comment: 24 pages, 15 figures, ApJS, in pres
Unbiased Global Optimization of Lennard-Jones Clusters for N <= 201 by Conformational Space Annealing Method
We apply the conformational space annealing (CSA) method to the Lennard-Jones
clusters and find all known lowest energy configurations up to 201 atoms,
without using extra information of the problem such as the structures of the
known global energy minima. In addition, the robustness of the algorithm with
respect to the randomness of initial conditions of the problem is demonstrated
by ten successful independent runs up to 183 atoms. Our results indicate that
the CSA method is a general and yet efficient global optimization algorithm
applicable to many systems.Comment: revtex, 4 pages, 2 figures. Physical Review Letters, in pres
An evaluation of a nurse led unit: an action research study
This study is an exemplar of working in a participatory way with members of the public and health and social care practitioners as co-researchers. A Nurse Consultant Older People working in a nurse-led bed, intermediate care facility in a community hospital acted as joint project lead with an academic researcher. From the outset, members of the public were part of a team of 16 individuals who agreed an evaluation focus and were involved in all stages of the research process from design through to dissemination. An extensive evaluation reflecting all these stakeholdersâ preferences was undertaken. Methods included research and audit including: patient and carer satisfaction questionnaire surveys, individual interviews with patients, carers and staff, staff surveys, graffiti board, suggestion box, first impressions questionnaire, patient tracking and a bed census. A key aim of the study has been capacity building of the research team members which has also been evaluated. In terms of impact, the co-researchers have developed research skills and knowledge, grown in confidence, developed in ways that have impacted elsewhere in their lives, developed posters, presented at conferences and gained a better understanding of the NHS. The evaluation itself has provided useful information on the processes and outcomes of intermediate care on the ward which was used to further improve the service
Biologically driven DOC release from peatlands during recovery from acidification
Peatlands recovering from acidification release dissolved organic carbon (DOC), but no biological role has yet been identified in this process. Here, the authors show that pH increases enhance phenol oxidase activity, pore-water DOC concentrations and lead to greater abundances in Actinobacteria and fungi
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