594 research outputs found
Aggregation Operators for Fuzzy Rationality Measures.
Fuzzy rationality measures represent a particular class of aggregation operators. Following the axiomatic approach developed in [1,3,4,5] rationality of fuzzy preferences may be seen as a fuzzy property of fuzzy preferences. Moreover, several rationality measures can be aggregated into a global rationality measure. We will see when and how this can be done. We will also comment upon the feasibility of their use in real life applications. Indeed, some of the rationality measures proposed, though intuitively (and axiomatically) sound, appear to be quite complex from a computational point of view
Pentaquark spectrum in string dynamics
The masses of and pentaquarks are evaluated in a
framework of the Effective Hamiltonian approach to QCD using the Jaffe-Wilczek
approximation. The mass of the state is found to
be MeV higher than the observed mass.Comment: 6 pages, 1 figure included, LaTeX2e; several references added;
misprints corrected; to appear in Physics Letters
Phase field approach to optimal packing problems and related Cheeger clusters
In a fixed domain of we study the asymptotic behaviour of optimal
clusters associated to -Cheeger constants and natural energies like the
sum or maximum: we prove that, as the parameter converges to the
"critical" value , optimal Cheeger clusters
converge to solutions of different packing problems for balls, depending on the
energy under consideration. As well, we propose an efficient phase field
approach based on a multiphase Gamma convergence result of Modica-Mortola type,
in order to compute -Cheeger constants, optimal clusters and, as a
consequence of the asymptotic result, optimal packings. Numerical experiments
are carried over in two and three space dimensions
Phonological facilitation of grammatical gender retrieval.
In Dutch, the gender of nouns is marked by the definite articles de (common gender) and het (neuter gender). Most models of language production assume that gender information is retrieved via the noun's syntactic representation (or lemma). The authors test Caramazza's (1997) alternative proposal, according to which gender information is retrieved via the noun's phonological word form (or lexeme). In three picture-word experiments, which differed in the tasks to be performed (noun production, article+noun production, article production, and gender decision), clear phonological effects were obtained in tasks involving the retrieval of the noun's gender information. It is argued that traditional models of language production have difficulty in accounting for the occurrence and/or the size of these effects whereas they follow quite naturally from Caramazza's (1997) Independent Network model. © 2004 Psychology Press Ltd
Quark droplets stability induced by external magnetic field
The influence of a constant homogeneous external magnetic field on the
formation and stability of quark droplets is investigated within a simple Nambu
-- Jona-Lasinio model by using a thermodynamic approach. For a vanishing
magnetic field stable quark droplets, which are schematically the bags of
massless quarks, are allowed to exist only at , where is the
quark coupling constant, , and is the value of
the coupling constant above which chiral symmetry is spontaneously broken down.
On the other hand, a nonvanishing external magnetic field can induce the
stability of quark droplets so that they may exist even at . In this
case, depending on the value of , quark droplets are composed either of
massive or massless quarks.Comment: 16 pages, 9 figures, REVTEX4; new references added; minor changes of
the tex
Phenotypic covariance of longevity, immunity and stress resistance in the Caenorhabditis nematodes
Background \ud
Ageing, immunity and stresstolerance are inherent characteristics of all organisms. In animals, these traits are regulated, at least in part, by forkhead transcription factors in response to upstream signals from the Insulin/Insulin– like growth factor signalling (IIS) pathway. In the nematode Caenorhabditis elegans, these phenotypes are molecularly linked such that activation of the forkhead transcription factor DAF-16 both extends lifespan and simultaneously increases immunity and stress resistance. It is known that lifespan varies significantly among the Caenorhabditis species but, although DAF-16 signalling is highly conserved, it is unclear whether this phenotypic linkage occurs in other species. Here we investigate this phenotypic covariance by comparing longevity, stress resistance and immunity in four \ud
Caenorhabditis species. \ud
\ud
Methodology/Principal Findings \ud
We show using phenotypic analysis of DAF-16 influenced phenotypes that among four closely related Caenorhabditis nematodes, the gonochoristic species (Caenorhabditis remanei and Caenorhabditis brenneri) have diverged \ud
significantly with a longer lifespan, improved stress resistance and higher immunity than the hermaphroditic species (C. elegans and Caenorhabditis briggsae). Interestingly, we also observe significant differences in expression levels between the daf-16 homologues in these species using Real-Time PCR, which positively correlate with the observed phenotypes. Finally, we provide additional evidence in support of a role for DAF-16 in regulating phenotypic coupling by using a combination of wildtype isolates, constitutively active daf-16 mutants and bioinformatic analysis. \ud
\ud
Conclusions \ud
The gonochoristic species display a significantly longer lifespan (p < 0.0001)and more robust immune and stress response (p<0.0001, thermal stress; p<0.01, heavy metal stress; p<0.0001, pathogenic stress) than the hermaphroditic species. Our data suggests that divergence in DAF-16 mediated phenotypes may underlie many of the differences observed between these four species of Caenorhabditis nematodes. These findings are further supported by the correlative higher daf-16 expression levels among the gonochoristic species and significantly higher lifespan, immunity and stress tolerance in the constitutively active daf-16 hermaphroditic mutants
Phenotypic covariance of Longevity, Immunity and Stress Resistance in the Caenorhabditis Nematodes
Background: Ageing, immunity and stresstolerance are inherent characteristics of all organisms. In animals, these traits are regulated, at least in part, by forkhead transcription factors in response to upstream signals from the Insulin/Insulin–like growth factor signalling (IIS) pathway. In the nematode Caenorhabditis elegans, these phenotypes are molecularly linked such that activation of the forkhead transcription factor DAF-16 both extends lifespan and simultaneously increases immunity and stress resistance. It is known that lifespan varies significantly among the Caenorhabditis species but, although DAF-16 signalling is highly conserved, it is unclear whether this phenotypic linkage occurs in other species. Here we investigate this phenotypic covariance by comparing longevity, stress resistance and immunity in four Caenorhabditis species. \ud
\ud
Methodology/Principal Findings: We show using phenotypic analysis of DAF-16 influenced phenotypes that among four closely related Caenorhabditis nematodes, the gonochoristic species (Caenorhabditis remanei and Caenorhabditis brenneri) have diverged significantly with a longer lifespan, improved stress resistance and higher immunity than the hermaphroditic species (C. elegans and Caenorhabditis briggsae). Interestingly, we also observe significant differences in expression levels between the daf-16 homologues in these species using Real-Time PCR, which positively correlate with the observed phenotypes. Finally, we provide additional evidence in support of a role for DAF-16 in regulating phenotypic coupling by using a combination of wildtype isolates, constitutively active daf-16 mutants and bioinformatic analysis. \ud
\ud
Conclusions: The gonochoristic species display a significantly longer lifespan (p<0.0001) and more robust immune and stress response (p<0.0001, thermal stress; p<0.01, heavy metal stress; p<0.0001, pathogenic stress) than the hermaphroditic species. Our data suggests that divergence in DAF-16 mediated phenotypes may underlie many of the differences observed between these four species of Caenorhabditis nematodes. These findings are further supported by the correlative higher daf-16 expression levels among the gonochoristic species and significantly higher lifespan, immunity and stress tolerance in the constitutively active daf-16 hermaphroditic mutants
Dynamical Boson Stars
The idea of stable, localized bundles of energy has strong appeal as a model
for particles. In the 1950s John Wheeler envisioned such bundles as smooth
configurations of electromagnetic energy that he called {\em geons}, but none
were found. Instead, particle-like solutions were found in the late 1960s with
the addition of a scalar field, and these were given the name {\em boson
stars}. Since then, boson stars find use in a wide variety of models as sources
of dark matter, as black hole mimickers, in simple models of binary systems,
and as a tool in finding black holes in higher dimensions with only a single
killing vector. We discuss important varieties of boson stars, their dynamic
properties, and some of their uses, concentrating on recent efforts.Comment: 79 pages, 25 figures, invited review for Living Reviews in
Relativity; major revision in 201
Very low prevalence of ultrasound detected tenosynovial abnormalities in healthy subjects throughout the age range: OMERACT ultrasound minimal disease study
Objectives: This study aimed to determine the prevalence of ultrasound detected tendon abnormalities in healthy subjects (HS)
across the age range. /
Methods: Adult HS (age 18 to 80 years) were recruited in 23 international Outcome Measures in Rheumatology (OMERACT)
ultrasound centres and clinically assessed to exclude inflammatory diseases or overt osteoarthritis before undergoing a bilateral
ultrasound examination of digit flexor (DF) 1-5 and extensor carpi ulnaris (ECU) tendons to detect the presence of tenosynovial
hypertrophy (TSH), power Doppler (TPD) and tenosynovial effusion (TEF), usually considered ultrasound signs of inflammatory
diseases. A comparison cohort of Rheumatoid Arthritis (RA) patients was taken from the Birmingham BEACON early arthritis
inception cohort. /
Results: 939 HS and 144 RA patients were included. The majority of HS (85%) had grade 0 for TSH, TPD and TEF in all DF and ECU
tendons examined. There was statistically significant difference in the proportion of TSH and TPD involvement between HS and
RA subjects (HS vs RA p<0.001). In HS there was no difference in the presence of ultrasound abnormalities between age groups. /
Conclusions: Ultrasound detected TSH and TPD abnormalities are rare in HS and can be regarded as markers of active
inflammatory disease in newly presenting suspected RA
Amino acid positions subject to multiple co-evolutionary constraints can be robustly identified by their eigenvector network centrality scores
As proteins evolve, amino acid positions key to protein structure or function are subject to mutational constraints. These positions can be detected by analyzing sequence families for amino acid conservation or for co-evolution between pairs of positions. Co-evolutionary scores are usually rank-ordered and thresholded to reveal the top pairwise scores, but they also can be treated as weighted networks. Here, we used network analyses to bypass a major complication of co-evolution studies: For a given sequence alignment, alternative algorithms usually identify different, top pairwise scores. We reconciled results from five commonly-used, mathematically divergent algorithms (ELSC, McBASC, OMES, SCA, and ZNMI), using the LacI/GalR and 1,6-bisphosphate aldolase protein families as models. Calculations used unthresholded co-evolution scores from which column-specific properties such as sequence entropy and random noise were subtracted; “central” positions were identified by calculating various network centrality scores. When compared among algorithms, network centrality methods, particularly eigenvector centrality, showed markedly better agreement than comparisons of the top pairwise scores. Positions with large centrality scores occurred at key structural locations and/or were functionally sensitive to mutations. Further, the top central positions often differed from those with top pairwise co-evolution scores: Instead of a few strong scores, central positions often had multiple, moderate scores. We conclude that eigenvector centrality calculations reveal a robust evolutionary pattern of constraints – detectable by divergent algorithms – that occur at key protein locations. Finally, we discuss the fact that multiple patterns co-exist in evolutionary data that, together, give rise to emergent protein functions
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