1,749 research outputs found
PRIMARY ELECTIONS IN THE SOUTH: A STUDY IN UNIPARTY POLITICS, by Cortez A. M. Ewing. University of Oklahoma Press, Norman, 1953. Pp. xii, 112. $2.75.
The degeneracy of behavior and the rise of neuroimaging to measure affective states in dogs
It is gratifying and significant that so many scientists from diverse fields are arguing in-depth regarding a particularly complex set of social emotions in a non-human animal. Emotions play a fundamental role in decision making and information processing. Neuroimaging is important in understanding the cognitive and emotional worlds of non-human animals and can help measure covert emotions lacking clear behavioral correlates. Various experimental approaches could clarify the relative importance of attachment and aggression in jealousy and whether the phenomenon we measured is more akin to human envy or jealousy. Reverse inference from amygdala activation is probably justified because behavior is “degenerate”: there are fewer behavioral programs than brain states that give rise to them. Individual differences are also important
The degeneracy of behavior and the rise of neuroimaging to measure affective states in dogs
It is gratifying and significant that so many scientists from diverse fields are arguing in-depth regarding a particularly complex set of social emotions in a non-human animal. Emotions play a fundamental role in decision making and information processing. Neuroimaging is important in understanding the cognitive and emotional worlds of non-human animals and can help measure covert emotions lacking clear behavioral correlates. Various experimental approaches could clarify the relative importance of attachment and aggression in jealousy and whether the phenomenon we measured is more akin to human envy or jealousy. Reverse inference from amygdala activation is probably justified because behavior is “degenerate”: there are fewer behavioral programs than brain states that give rise to them. Individual differences are also important
On Convergence of the Inexact Rayleigh Quotient Iteration with the Lanczos Method Used for Solving Linear Systems
For the Hermitian inexact Rayleigh quotient iteration (RQI), the author has
established new local general convergence results, independent of iterative
solvers for inner linear systems. The theory shows that the method locally
converges quadratically under a new condition, called the uniform positiveness
condition. In this paper we first consider the local convergence of the inexact
RQI with the unpreconditioned Lanczos method for the linear systems. Some
attractive properties are derived for the residuals, whose norms are
's, of the linear systems obtained by the Lanczos method. Based on
them and the new general convergence results, we make a refined analysis and
establish new local convergence results. It is proved that the inexact RQI with
Lanczos converges quadratically provided that with a
constant . The method is guaranteed to converge linearly provided
that is bounded by a small multiple of the reciprocal of the
residual norm of the current approximate eigenpair. The results are
fundamentally different from the existing convergence results that always
require , and they have a strong impact on effective
implementations of the method. We extend the new theory to the inexact RQI with
a tuned preconditioned Lanczos for the linear systems. Based on the new theory,
we can design practical criteria to control to achieve quadratic
convergence and implement the method more effectively than ever before.
Numerical experiments confirm our theory.Comment: 20 pages, 8 figures. arXiv admin note: text overlap with
arXiv:0906.223
Diffusion Tensor Imaging of Dolphin Brains Reveals Direct Auditory Pathway to Temporal Lobe
The brains of odontocetes (toothed whales) look grossly different from their terrestrial relatives. Because of their adaptation to the aquatic environment and their reliance on echolocation, the odontocetes’ auditory system is both unique and crucial to their survival. Yet, scant data exist about the functional organization of the cetacean auditory system. A predominant hypothesis is that the primary auditory cortex lies in the suprasylvian gyrus along the vertex of the hemispheres, with this position induced by expansion of ‘associative0 regions in lateral and caudal directions. However, the precise location of the auditory cortex and its connections are still unknown. Here, we used a novel diffusion tensor imaging (DTI) sequence in archival post-mortem brains of a common dolphin (Delphinus delphis) and a pantropical dolphin (Stenella attenuata) to map their sensory and motor systems. Using thalamic parcellation based on traditionally defined regions for the primary visual (V1) and auditory cortex (A1), we found distinct regions of the thalamus connected to V1 and A1. But in addition to suprasylvian-A1, we report here, for the first time, the auditory cortex also exists in the temporal lobe, in a region near cetacean-A2 and possibly analogous to the primary auditory cortex in related terrestrial mammals (Artiodactyla). Using probabilistic tract tracing, we found a direct pathway from the inferior colliculus to the medial geniculate nucleus to the temporal lobe near the sylvian fissure. Our results demonstrate the feasibility of postmortem DTI in archival specimens to answer basic questions in comparative neurobiology in a way that has not previously been possible and shows a link between the cetacean auditory system and those of terrestrial mammals. Given that fresh cetacean specimens are relatively rare, the ability to measure connectivity in archival specimens opens up a plethora of possibilities for investigating neuroanatomy in cetaceans and other species
One pair of hands is not like another: caudate BOLD response in dogs depends on signal source and canine temperament
Influence of the PM-Processing Route and Nitrogen Content on the Properties of Ni-Free Austenitic Stainless Steel
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