455 research outputs found
Correlations between reflected and transmitted intensity patterns emerging from opaque disordered media
The propagation of monochromatic light through a scattering medium produces
speckle patterns in reflection and transmission, and the apparent randomness of
these patterns prevents direct imaging through thick turbid media. Yet, since
elastic multiple scattering is fundamentally a linear and deterministic
process, information is not lost but distributed among many degrees of freedom
that can be resolved and manipulated. Here we demonstrate experimentally that
the reflected and transmitted speckle patterns are correlated, even for opaque
media with thickness much larger than the transport mean free path, proving
that information survives the multiple scattering process and can be recovered.
The existence of mutual information between the two sides of a scattering
medium opens up new possibilities for the control of transmitted light without
any feedback from the target side, but using only information gathered from the
reflected speckle.Comment: 6 pages, 4 figure
Characterization of ejecta in shock experiments with multiple light scattering
Upon impact, the free surface of a solid metal may eject a cloud of fast and
fine particles. Photon Doppler Velocimetry (PDV) is one of the optical
diagnostics used to characterize these ejecta. Although the technique provides
a direct way to estimate the particle velocities in the single scattering
regime, it has been shown that multiple scattering cannot be neglected in real
ejecta. Here we derive a model for PDV measurements starting from first
principles of wave scattering. We establish rigorously the relationship between
the specific intensity and the measured signal, as well as the radiative
transport equation (RTE) that describes the evolution of the specific intensity
upon scattering and absorption in a dynamic ejecta, including the effects of
inelastic scattering and inhomogenities in the optical properties. We also
establish rigorously the connection between the Monte-Carlo scheme used for
numerical simulations and the solution to the RTE. Using numerical simulations,
we demonstrate the crucial role of multiple scattering and inhomogeneities in
the particle density and size-velocity distribution. These results could
substantially impact the analysis of ejecta by PDV
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The exon junction complex senses energetic stress and regulates contractility and cell architecture in cardiac myocytes
The exon junction complex (EJC) is the main mechanism by which cells select specific mRNAs
for translation into protein. We hypothesized that the EJC is involved in the regulation
of gene expression during the stress response in cardiac myocytes, with implications for
the failing heart. In cultured rat neonatal myocytes, we examined the cellular distribution
of two EJC components eukaryotic translation initiation factor 4A isoform 3 (eIF4A3) and
mago nashi homologue (Mago) in response to metabolic stress. There was significant relocalization
of eIF4A3 and Mago from the nucleus to cytoplasm following 18 h of hypoxia.
Treating myocytes with 50 mM NaN3 for 4 h to mimic the metabolic stress induced by hypoxia
also resulted in significant relocalization of eIF4A3 and Mago to the cytoplasm. To
examine whether the effects of metabolic stress on the EJC proteins were dependent on
the metabolic sensor AMP kinase (AMPK), we treated myocytes with 1 μM dorsomorphin
(DM) in combination with NaN3. DM augmented the translocation of Mago and eIF4A3 from
the nucleus to the cytoplasm. Knockdown of eIF4A3 resulted in cessation of cell contractility
96 h post-treatment and a significant reduction in the number of intact sarcomeres.
Cell area was significantly reduced by both hypoxia and eIF4A3 knockdown, whilst eIF4A3
knockdown also significantly reduced nuclear size. The reduction in nuclear size is unlikely
to be related to apoptosis as it was reversed in combination with hypoxia. These data suggest
for the first time that eIF4A3 and potentially other EJC members play an important role
in the myocyte stress response, cell contractility and morphology
Modelling rubber-tree root diseases, simulations of various inoculum rates and methods of control
Sur la base des résultats d'une étude épidémiologique menée en plantation industrielle pendant 6 années, a été réalisée une étude mathématique des processus spatio-temporels caractérisant le développement de deux maladies du système racinaire causées par #Rigidoporus lignosus et #Phellinus noxius. Il a été possible de simuler différentes situations phytosanitaires. L'usage potentiel du modèle utilisé pour gérer les problèmes sanitaires en plantation et certaines préconisations sont discutés. (D'après résumé d'auteur
Bismuth coordination networks containing deferiprone: synthesis, characterisation, stability and antibacterial activity
A series of bismuth–dicarboxylate–deferiprone coordination networks have been prepared and structurally characterised. The new compounds have been demonstrated to release the iron overload drug deferiprone on treatment with PBS and have also been shown to have antibacterial activity against H. pylori
Developmental motor problems and health-related quality of life in 5-year-old children born extremely preterm: A European cohort study
Aim To measure the association between cerebral palsy (CP) and non-CP-related movement difficulties and health-related quality of life (HRQoL) among 5-year-old children born extremely preterm (<28 weeks gestational age). Method We included 5-year-old children from a multi-country, population-based cohort of children born extremely preterm in 2011 to 2012 in 11 European countries (n = 1021). Children without CP were classified using the Movement Assessment Battery for Children, Second Edition as having significant movement difficulties (<= 5th centile of standardized norms) or being at risk of movement difficulties (6th-15th centile). Parents reported on a clinical CP diagnosis and HRQoL using the Pediatric Quality of Life Inventory. Associations were assessed using linear and quantile regressions. Results Compared to children without movement difficulties, children at risk of movement difficulties, with significant movement difficulties, and CP had lower adjusted HRQoL total scores (beta [95% confidence interval] = -5.0 [-7.7 to -2.3], -9.1 [-12.0 to -6.1], and - 26.1 [-31.0 to -21.2]). Quantile regression analyses showed similar decreases in HRQoL for all children with CP, whereas for children with non-CP-related movement difficulties, reductions in HRQoL were more pronounced at lower centiles. Interpretation CP and non-CP-related movement difficulties were associated with lower HRQoL, even for children with less severe difficulties. Heterogeneous associations for non-CP-related movement difficulties raise questions for research about mitigating and protective factors.Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Grant/Award Number: SFRH/BPD/117597/2016; Horizon 2020 Framework Programme, Grant/Award Number: No 633724 and No 733280; Seventh Framework Programme, Grant/Award Number: No 25988
Developmental cascades of social inhibition and friendships in preterm and full‐term children
Friendships are crucial to children's socioemotional development and quality of life. Children born preterm (<37 weeks gestation) have an increased risk for social relationship difficulties, including fewer friends, but the mechanisms underlying the link between lower gestational age and fewer friendships are not clear. The prospective Bavarian Longitudinal Study investigated potential cascading effects on N = 1,181 children's friendships at 8 years. Path modelling indicated that higher gestational age predicted good early parent–infant relationship quality, good inhibitory control, and higher friendship scores. Good parent–infant relationship quality predicted good inhibitory control, which subsequently predicted low social inhibition at 6 years and higher friendship scores at 8 years. There is evidence of cascading effects from gestational age to early parent–infant relationships, to toddlers' inhibitory control, and to social inhibition, which partially explain differences in children's friendships at 8 years of age
Control of protein translation by phosphorylation of the mRNA 5′-cap-binding complex,
Abstract Initiation of mRNA translation is a key regulatory step in the control of gene expression. Microarray analysis indicates that total mRNA levels do not always reflect protein levels, since mRNA association with polyribosomes is necessary for protein synthesis. Phosphorylation of translation initiation factors offers a costeffective and rapid way to adapt to physiological and environmental changes, and there is increasing evidence that many of these factors are subject to multiple regulatory phosphorylation events. The present article focuses on the nature of reversible phosphorylation and the function of the 5 -cap-binding complex in plants
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