326 research outputs found
Cartan subalgebras and the UCT problem, II
We show that outer approximately represenbtable actions of a finite cyclic
group on UCT Kirchberg algebras satisfy a certain quasi-freeness type property
if the corresponding crossed products satisfy the UCT and absorb a suitable UHF
algebra tensorially. More concretely, we prove that for such an action there
exists an inverse semigroup of homogeneous partial isometries that generates
the ambient C*-algebra and whose idempotent semilattice generates a Cartan
subalgebra. We prove a similar result for actions of finite cyclic groups with
the Rokhlin property on UCT Kirchberg algebras absorbing a suitable UHF
algebra. These results rely on a new construction of Cartan subalgebras in
certain inductive limits of Cartan pairs. We also provide a characterisation of
the UCT problem in terms of finite order automorphisms, Cartan subalgebras and
inverse semigroups of partial isometries of the Cuntz algebra .
This generalizes earlier work of the authors.Comment: minor revisions; final version, accepted for publication in Math.
Ann.; 26 page
Theory of algebraic invariants of vector spaces of Killing tensors: Methods for computing the fundamental invariants
We review computational techniques that can be used in the determination of fundamental invariants of vector spaces of Killing tensors under the action of the isometry group. In particular, for the first time in this study, we employ for these purposes the method of moving frames introduced by Fels and Olver. Illustrative examples are provided
Fluid observers and tilting cosmology
We study perfect fluid cosmological models with a constant equation of state
parameter in which there are two naturally defined time-like
congruences, a geometrically defined geodesic congruence and a non-geodesic
fluid congruence. We establish an appropriate set of boost formulae relating
the physical variables, and consequently the observed quantities, in the two
frames. We study expanding spatially homogeneous tilted perfect fluid models,
with an emphasis on future evolution with extreme tilt. We show that for
ultra-radiative equations of state (i.e., ), generically the tilt
becomes extreme at late times and the fluid observers will reach infinite
expansion within a finite proper time and experience a singularity similar to
that of the big rip. In addition, we show that for sub-radiative equations of
state (i.e., ), the tilt can become extreme at late times and
give rise to an effective quintessential equation of state. To establish the
connection with phantom cosmology and quintessence, we calculate the effective
equation of state in the models under consideration and we determine the future
asymptotic behaviour of the tilting models in the fluid frame variables using
the boost formulae. We also discuss spatially inhomogeneous models and tilting
spatially homogeneous models with a cosmological constant
A window on reality: perceiving edited moving images
Edited moving images entertain, inform, and coerce us throughout our daily lives, yet until recently, the way people perceive movies has received little psychological attention. We review the history of empirical investigations into movie perception and the recent explosion of new research on the subject using methods such as behavioral experiments, functional magnetic resonance imagery (fMRI) eye tracking, and statistical corpus analysis. The Hollywood style of moviemaking, which permeates a wide range of visual media, has evolved formal conventions that are compatible with the natural dynamics of attention and humans’ assumptions about continuity of space, time, and action. Identifying how people overcome the sensory differences between movies and reality provides an insight into how the same cognitive processes are used to perceive continuity in the real world
Fine-mapping of 5q12.1-13.3 unveils new genetic contributors to caries
Caries is a multifactorial disease and little is still known about the host genetic factors influencing susceptibility. Our previous genome-wide linkage scan has identified the interval 5q12.1–5q13.3 as linked to low caries susceptibility in Filipino families. Here we fine-mapped this region in order to identify genetic contributors to caries susceptibility. Four hundred and seventy-seven subjects from 72 pedigrees with similar cultural and behavioral habits and limited access to dental care living in the Philippines were studied. DMFT scores and genotype data of 75 single-nucleotide polymorphisms were evaluated in the Filipino families with the Family-Based Association Test. For replication purposes, a total 1,467 independent subjects from five different populations were analyzed in a case-control format. In the Filipino cohort, statistically significant and borderline associations were found between low caries experience and four genes spanning 13 million base pairs (PART1, ZSWIM6, CCNB1, and BTF3). We were able to replicate these results in some of the populations studied. We detected PART1 and BTF3 expression in whole saliva, and the expression of BTF3 was associated with caries experience. Our results suggest BTF3 may have a functional role in protecting against caries.Fil: Shimizu, T.. Nihon University of Dentistry; JapónFil: Deeley, K.. University of Pittsburgh; Estados UnidosFil: Briseño Ruiz, J.. University of Pittsburgh; Estados UnidosFil: Faraco Junior, I. M.. University of Pittsburgh; Estados UnidosFil: Poletta, Fernando Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET.; ArgentinaFil: Brancher, J. A.. Pontifical Catholic University of Paraná; BrasilFil: Pecharki, G. D.. Pontifical Catholic University of Paraná; BrasilFil: Küchler, E. C.. Universidade Federal Fluminense; BrasilFil: Tannure, P. N.. Universidade Federal do Rio de Janeiro; BrasilFil: Lips, A.. Universidade Federal do Rio de Janeiro; BrasilFil: Vieira, T. C. S.. Universidade Federal Fluminense; BrasilFil: Patir, A.. Istanbul Medipol Universit; TurquíaFil: Yildirim, M.. Istanbul University; TurquíaFil: Mereb, J. C.. Centro de Educación Médica e Investigaciones Clínicas “Norberto Quirno”; ArgentinaFil: Resick, J. M.. University of Pittsburgh; Estados UnidosFil: Brandon, C. A.. University of Pittsburgh; Estados UnidosFil: Cooper, M. E.. University of Pittsburgh; Estados UnidosFil: Seymen, F.. Istanbul University; TurquíaFil: Costa, M. C.. Universidade Federal do Rio de Janeiro; BrasilFil: Granjeiro, J. M.. Universidade Federal Fluminense; BrasilFil: Trevilatto, P. C.. Pontifical Catholic University of Paraná; BrasilFil: Orioli, I. M.. Universidade Federal do Rio de Janeiro; Brasil. Centro de Educación Médica e Investigaciones Clínicas “Norberto Quirno”; ArgentinaFil: Castilla, Eduardo Enrique. Instituto Oswaldo Cruz; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET.; ArgentinaFil: Marazita, M. L.. University of Pittsburgh; Estados UnidosFil: Vieira, A. R.. University of Pittsburgh; Estados Unido
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Disorder-specific functional abnormalities during sustained attention in youth with Attention Deficit Hyperactivity Disorder (ADHD) and with Autism
Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are often comorbid and share behavioural-cognitive abnormalities in sustained attention. A key question is whether this shared cognitive phenotype is based on common or different underlying pathophysiologies. To elucidate this question, we compared 20 boys with ADHD to 20 age and IQ matched ASD and 20 healthy boys using functional magnetic resonance imaging (fMRI) during a parametrically modulated vigilance task with a progressively increasing load of sustained attention. ADHD and ASD boys had significantly reduced activation relative to controls in bilateral striato–thalamic regions, left dorsolateral prefrontal cortex (DLPFC) and superior parietal cortex. Both groups also displayed significantly increased precuneus activation relative to controls. Precuneus was negatively correlated with the DLPFC activation, and progressively more deactivated with increasing attention load in controls, but not patients, suggesting problems with deactivation of a task-related default mode network in both disorders. However, left DLPFC underactivation was significantly more pronounced in ADHD relative to ASD boys, which furthermore was associated with sustained performance measures that were only impaired in ADHD patients. ASD boys, on the other hand, had disorder-specific enhanced cerebellar activation relative to both ADHD and control boys, presumably reflecting compensation. The findings show that ADHD and ASD boys have both shared and disorder-specific abnormalities in brain function during sustained attention. Shared deficits were in fronto–striato–parietal activation and default mode suppression. Differences were a more severe DLPFC dysfunction in ADHD and a disorder-specific fronto–striato–cerebellar dysregulation in ASD
Drug transporters: recent advances concerning BCRP and tyrosine kinase inhibitors
Multidrug resistance is often associated with the (over)expression of drug efflux transporters of the ATP-binding cassette (ABC) protein family. This minireview discusses the role of one selected ABC-transporter family member, the breast cancer resistance protein (BCRP/ABCG2), in the (pre)clinical efficacy of novel experimental anticancer drugs, in particular tyrosine kinase inhibitors
Asymmetric Switching in a Homodimeric ABC Transporter: A Simulation Study
ABC transporters are a large family of membrane proteins involved in a variety of cellular processes, including multidrug and tumor resistance and ion channel regulation. Advances in the structural and functional understanding of ABC transporters have revealed that hydrolysis at the two canonical nucleotide-binding sites (NBSs) is co-operative and non-simultaneous. A conserved core architecture of bacterial and eukaryotic ABC exporters has been established, as exemplified by the crystal structure of the homodimeric multidrug exporter Sav1866. Currently, it is unclear how sequential ATP hydrolysis arises in a symmetric homodimeric transporter, since it implies at least transient asymmetry at the NBSs. We show by molecular dynamics simulation that the initially symmetric structure of Sav1866 readily undergoes asymmetric transitions at its NBSs in a pre-hydrolytic nucleotide configuration. MgATP-binding residues and a network of charged residues at the dimer interface are shown to form a sequence of putative molecular switches that allow ATP hydrolysis only at one NBS. We extend our findings to eukaryotic ABC exporters which often consist of two non-identical half-transporters, frequently with degeneracy substitutions at one of their two NBSs. Interestingly, many residues involved in asymmetric conformational switching in Sav1866 are substituted in degenerate eukaryotic NBS. This finding strengthens recent suggestions that the interplay of a consensus and a degenerate NBS in eukaroytic ABC proteins pre-determines the sequence of hydrolysis at the two NBSs
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