Bistable Helmholtz dark spatial optical solitons in materials with self-defocusing saturable nonlinearity

We present, to the best of our knowledge, the first exact dark spatial solitons of a nonlinear Helmholtz equation with a self-defocusing saturable refractive-index model. These solutions capture oblique (arbitrary-angle) propagation in both the forward and backward directions, and they can also exhibit a bistability characteristic. A detailed derivation is presented, obtained by combining coordinate transformations and direct-integration methods, and the corresponding solutions of paraxial theory are recovered asymptotically as a subset. Simulations examine the robustness of the new Helmholtz solitons, with stationary states emerging from a range of perturbed input beams

Opinion Cascades and Echo-Chambers in Online Networks: A Proof of Concept Agent-Based Model

In online networks, the polarization of opinions (e.g., regarding presidential elections or referenda) has been associated with the creation of “echo-chambers” of like-minded peers, secluded from those of contrary viewpoints. Previous work has commonly attributed such phenomena to self-regarding preferences (e.g., confirmation bias), individual differences, and the pre-dispositions of users, with clusters forming over repeated interactions. The present work provides a proof of concept Agent-Based Model that demonstrates online networks are susceptible to echo-chambers from a single opinion cascade, due to the spatiotemporal order induced by lateral transmission. This susceptibility is found to vary as a function of degree of interconnectivity and opinion strength. Critically, such effects are found despite globally proportionate levels of opinions, equally rational agents (i.e. absent conformity, confirmation bias or pre-disposition architecture), and prior to cyclical interactions. The assumptions and implications of this work, including the value of Agent-Based Modelling to cognitive psychology, are discussed

Correlation of RBC total PL and RBC GPL omega-3 index (n = 13).

<p>Correlation of RBC total PL and RBC GPL omega-3 index (n = 13).</p

Correlations between RBC GPL fatty acids and other RBC PL fractions before and after n-3 supplementation.

<p>n.s. not significant.</p

Effects of DHA supplementation on fatty acid composition (%wt/wt) of individual RBC PL fractions.

<p>Differences between study start and end were based on baseline values. Paired t-test: *p<0.05, **p<0.01, *p<0.001.</p

Recovery of total RBC fatty acids using different extraction procedures (<i>P</i><0.05).

<p>Recovery of total RBC fatty acids using different extraction procedures (<i>P</i><0.05).</p

Changes in fatty acids (%wt/wt) during storage of RBC samples (n = 13) in methanol over a period of 8 months at −80°C.

*<p>Differences in fatty acid contents caused through sample storage were related to fatty acid contents of samples without storage. Mean and SD are expressed as %wt/wt. n.s.: not significant.</p

Intra- and inter-assay reproducibility of the GPL fatty acid analysis.

<p>Mean and SD are expressed as %wt/wt.</p

Phospholipid Species in Newborn and 4 Month Old Infants after Consumption of Different Formulas or Breast Milk

<div><p>Introduction</p><p>Arachidonic acid (AA) and docosahexaenoic acid (DHA) are important long-chain polyunsaturated fatty acids for neuronal and cognitive development and are ingredients of infant formulae that are recommended but there is no evidence based minimal supplementation level available. The aim of this analysis was to investigate the effect of supplemented AA and DHA on phospholipid metabolism.</p><p>Methods</p><p>Plasma samples of a randomized, double-blind infant feeding trial were used for the analyses of phospholipid species by flow-injection mass spectrometry. Healthy term infants consumed isoenergetic formulae (intervention formula with equal amounts of AA and DHA—IF, control formula without additional AA and DHA—CF) from the first month of life until the age of 120 days. A group of breast milk (BM) -fed infants was followed as a reference.</p><p>Results</p><p>The plasma profile detected in newborns was different from 4 month old infants, irrespective of study group. Most relevant changes were seen in higher level of LPC16:1, LPC20:4, PC32:1, PC34:1 and PC36:4 and lower level of LPC18:0, LPC18:2, PC32:2, PC36:2 and several ether-linked phosphatidylcholines in newborns. The sum of all AA and DHA species at 4 month old infants in the CF group showed level of 40% (AA) and 51% (DHA) of newborns. The supplemented amount of DHA resulted in phospholipid level comparable to BM infants, but AA phospholipids were lower than in BM infants. Interestingly, relative contribution of DHA was higher in ether-linked phosphatidylcholines in CF fed infants, but IF and BM fed infants showed higher overall ether-linked phosphatidylcholines levels.</p><p>Conclusion</p><p>In conclusion, we have shown that infant plasma phospholipid profile changes remarkably from newborn over time and is dependent on the dietary fatty acid composition. A supplementation of an infant formula with AA and DHA resulted in increased related phospholipid species.</p></div

Fatty acid content (g/100 mL) of the studied infant formulas.

<p>Fatty acid content (g/100 mL) of the studied infant formulas.</p