3,745 research outputs found
Disease Localization in Multilayer Networks
We present a continuous formulation of epidemic spreading on multilayer
networks using a tensorial representation, extending the models of monoplex
networks to this context. We derive analytical expressions for the epidemic
threshold of the SIS and SIR dynamics, as well as upper and lower bounds for
the disease prevalence in the steady state for the SIS scenario. Using the
quasi-stationary state method we numerically show the existence of disease
localization and the emergence of two or more susceptibility peaks, which are
characterized analytically and numerically through the inverse participation
ratio. Furthermore, when mapping the critical dynamics to an eigenvalue
problem, we observe a characteristic transition in the eigenvalue spectra of
the supra-contact tensor as a function of the ratio of two spreading rates: if
the rate at which the disease spreads within a layer is comparable to the
spreading rate across layers, the individual spectra of each layer merge with
the coupling between layers. Finally, we verified the barrier effect, i.e., for
three-layer configuration, when the layer with the largest eigenvalue is
located at the center of the line, it can effectively act as a barrier to the
disease. The formalism introduced here provides a unifying mathematical
approach to disease contagion in multiplex systems opening new possibilities
for the study of spreading processes.Comment: Revised version. 25 pages and 18 figure
Fano resonances in plasmonic core-shell particles and the Purcell effect
Despite a long history, light scattering by particles with size comparable
with the light wavelength still unveils surprising optical phenomena, and many
of them are related to the Fano effect. Originally described in the context of
atomic physics, the Fano resonance in light scattering arises from the
interference between a narrow subradiant mode and a spectrally broad radiation
line. Here, we present an overview of Fano resonances in coated spherical
scatterers within the framework of the Lorenz-Mie theory. We briefly introduce
the concept of conventional and unconventional Fano resonances in light
scattering. These resonances are associated with the interference between
electromagnetic modes excited in the particle with different or the same
multipole moment, respectively. In addition, we investigate the modification of
the spontaneous-emission rate of an optical emitter at the presence of a
plasmonic nanoshell. This modification of decay rate due to electromagnetic
environment is referred to as the Purcell effect. We analytically show that the
Purcell factor related to a dipole emitter oriented orthogonal or tangential to
the spherical surface can exhibit Fano or Lorentzian line shapes in the near
field, respectively.Comment: 28 pages, 10 figures; invited book chapter to appear in "Fano
Resonances in Optics and Microwaves: Physics and Application", Springer
Series in Optical Sciences (2018), edited by E. O. Kamenetskii, A. Sadreev,
and A. Miroshnichenk
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A viable mouse model of factor X deficiency provides evidence for maternal transfer of factor X.
BackgroundActivated factor X (FXa) is a vitamin K-dependent serine protease that plays a pivotal role in blood coagulation by converting prothrombin to thrombin. There are no reports of humans with complete deficiency of FX, and knockout of murine F10 is embryonic or perinatal lethal.ObjectiveWe sought to generate a viable mouse model of FX deficiency.MethodsWe used a socket-targeting construct to generate F10-knockout mice by eliminating F10 exon 8 (knockout allele termed F10(tm1Ccmt), abbreviated as '-'; wild-type '+'), and a plug-targeting construct to generate mice expressing a FX variant with normal antigen levels but low levels of FX activity [4-9% normal in humans carrying the defect, Pro343-->Ser, termed FX Friuli (mutant allele termed F10(tm2Ccmt), abbreviated as F)].ResultsF10 knockout mice exhibited embryonic or perinatal lethality. In contrast, homozygous Friuli mice [F10 (F/F)] had FX activity levels of approximately 5.5% (sufficient to rescue both embryonic and perinatal lethality), but developed age-dependent iron deposition and cardiac fibrosis. Interestingly, F10 (-/F) mice with FX activity levels of 1-3% also showed complete rescue of lethality. Further study of this model provides evidence supporting a role of maternal FX transfer in the embryonic survival.ConclusionsWe demonstrate that, while complete absence of FX is incompatible with murine survival, minimal FX activity as low as 1-3% is sufficient to rescue the lethal phenotype. This viable low-FX mouse model will facilitate the development of FX-directed therapies as well as investigation of the FX role in embryonic development
Mitochondrial Uncoupling Proteins In Mammals And Plants
Uncoupling proteins (UCPs) belong to a distinct cluster of the mitochondrial anion carrier family. Up to five different uncoupling protein types were found in mitochondria of mammals and plants, and recently in fishes, fungi and protozoa. They exhibit a significantly conserved structure with several motifs specific to either the whole cluster or protein type. Uncoupling proteins, as well as the whole mitochondrial anion carrier gene family, probably emerged in evolution before the separation of animal, fungi, and plant kingdoms and originate from an anion/nucleotide or anion/anion transporter ancestor. Mammalian UCP1, UCP2, UCP3, and plant uncoupling proteins pUCP1 and pUCP2 are similar and seem to form one subgroup, whereas UCP4 and BMCP1 belong to a different group. Molecular, biochemical, and phylogenic data suggest that UCP2 could be considered as an UCP-prototype. UCP1 plays its biological role mainly in the non-shivering thermogenesis while the role of the other types is unknown. However, hypotheses have suggested that they are involved in the general balance of basic energy expenditure, protection from reactive oxygen species, and, in plants, in fruit ripening and seed ontogeny.212201212Kuan, J., Saier M.H., Jr., (1993) Res. Microbiol., 144, pp. 671-672Kuan, J., Saier M.H., Jr., (1993) Crit. Rev. Biochem. Mol. Biol., 28, pp. 209-233El Moualij, B., Duyckaerts, C., Lamotte-Brasseur, J., Sluse, F.E., (1997) Yeast, 13, pp. 573-581Palmieri, F., Indiveri, C., Bisaccia, F., Krämer, R., (1993) J. Bioenerg. Biomembr., 25, pp. 525-535Ježek, P., Garlid, K.D., (1990) J. Biol. Chem., 265, pp. 19303-19311Ricquier, D., Kader, J.-C., (1976) Biochem. Biophys. Res. 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Sequence polymorphism from EST data in sugarcane: a fine analysis of 6-phosphogluconate dehydrogenase genes
This paper presents preliminary results demonstrating the use of the sugarcane expressed sequence tag (EST) database (SUCEST) to detect single nucleotide polymorphisms (SNPs) inside 6-phosphogluconate dehydrogenase genes (Pgds). Sixty-four Pgd-related EST sequences were identified and partitioned into two clear-cut sets of 14 and 50 ESTs, probably corresponding to two genes, A and B, respectively. Alignment of A sequences allowed the detection of a single SNP while alignment of B sequences permitted the detection of 39 reliable SNPs, 27 of which in the coding sequence of the gene. Thirty-eight SNPs were binucleotidic and a single one was trinucleotidic. Nine insertions/deletions from one to 72 base pairs long were also detected in the noncoding 3? and 5? sequences. The soundness and the consequences of those preliminary observations on sequence polymorphism in sugarcane are discussed.O presente estudo apresenta resultados preliminares demonstrando a utilização da base de dados de ESTs de cana-de-açúcar para detectar polimorfismo de base única (SNP para Single Nucleotide Polymorphism). Sessenta e quatro ESTs relacionados aos genes da 6-phosphogluconate deshydrogenases (Pgds) foram identificados e divididos em dois conjuntos bem delimitados, de 14 e 50 ESTs, correspondendo a dois genes, A e B. O alinhamento das seqüências do grupo A permitiu a detecção de um único SNP e o alinhamento das seqüências do grupo B permitiu a detecção de 39 SNP, incluindo 27 na região codificante do gene. Trinta e oito SNP foram bi-nucleotídicos e um único tri-nucleotídico. Nove inserções/supressões de um até 72 pares de base foram detectados nas regiões não-codificantes 3? ou 5?. A robustez e as conseqüências dessas observações preliminares são discutidas.16116
Tolerância ao calor de caprinos e ovinos sem-lã em Sobral.
Resumo: Caprinos das raças Canindé, Anglo-Nubiana e Bhuj e avinos sem-la Morada Nova e Santa Inês foram comparados quanta às temperaturas retais e taxa respiratoria, antes e imediatamente apos o exercício e durante o período de uma hora de repouso apos o0 exercicio, para avaliaçao da tolerância ao calor ambiental. Resultados mostraram que a temperatura retal inicial nao foi diferente entre as cinco raças; apos exercicio, elevou de 1,25ºC até 1,95ºC nas diferentes raças; nao houve diferença da elevaçao da temperatura corporal entre espécies. Apos exercício, a recuperaçao foi rapida nos caprinos Bhuj e Canindé. A recuperaçao foi mais lenta na Anglo-Nubiana e nos avinos. A variaçao inicial no ritmo respiratorio apresentou-se elevada na Anglo-Nubiana em comparaçao com as outras raças de caprinos e avinos. Depois do exercicio, os avinos apresentaram menoI elevaçao no ritmo respiratorio do que os caprinos. Isto pode explicar o grau de recuperaçao mais rapida da temperatura corporal dos caprinos Bhuj e Canindé, os quais tiveram distintamente os mais elevados ritmos respiratorios após o exercicio. 0 ritmo respiratório da Anglo-Nubiana voltou ao normal dentro de 15 minutas apos o exercicio; somente o da Bhuj continuou elevado após os 15 minutos de descanso. Todas as espécies voltaram ao ritmo respiratório normal, após os trinta minutos de descanso. [Heat tolerance of goats and woolless sheep in Sobral Brazil]
Cerenkov angle and charge reconstruction with the RICH detector of the AMS experiment
The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the
International Space Station (ISS) will be equipped with a proximity focusing
Ring Imaging Cerenkov (RICH) detector, for measurements of particle electric
charge and velocity. In this note, two possible methods for reconstructing the
Cerenkov angle and the electric charge with the RICH, are discussed. A
Likelihood method for the Cerenkov angle reconstruction was applied leading to
a velocity determination for protons with a resolution of around 0.1%. The
existence of a large fraction of background photons which can vary from event
to event, implied a charge reconstruction method based on an overall efficiency
estimation on an event-by-event basis.Comment: Proceedings submitted to RICH 2002 (Pylos-Greece
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