Observation of accelerating parabolic beams

We report the first observation of accelerating parabolic beams. These accelerating parabolic beams are similar to the Airy beams because they exhibit the unusual ability to remain diffraction-free while having a quadratic transverse shift during propagation. The amplitude and phase masks required to generate these beams are encoded onto a single liquid crystal display. Experimental results agree well with theory

Gouy phase effects on propagation of pure and hybrid vector beams

The robustness of the polarization spatial distribution of vector beams upon propagation is crucial for a number of applications, including optical communications and materials processing. This study has been commonly centered on Gouy phase effects on focused vector beams. In this work, we present a theoretical and experimental analysis of the Gouy phase’s effects on the propagation of pure and hybrid vector beams. Experimental results at various axial planes, before and past the focus, are obtained by using a simplified liquid-crystal spatial light modulator-based optical system that allows the easy generation of these beams. Furthermore, a new alternative optical set-up that is devoid of moving elements is demonstrated, which simplifies this study. We experimentally verify the differences between pure and hybrid vector beams upon propagation. While the first ones remain stable, hybrid vector beams show Gouy phase effects that demonstrate an optical activity where the local polarization states rotate by an angle that depends on the propagation distance. Experimental results agree with the theory

Generation of accelerating Airy and accelerating parabolic beams using phase-only patterns

We generate both accelerated Airy and accelerated parabolic beams using phase-only patterns encoded onto a liquid crystal display (LCD). The usual system length is 2f, where f is the focal length of the Fourier transform lens. We develop a compact optical system having a total system length of f. However, the mask must now incorporate the Fresnel diffraction that is not provided by the reduced optical system length. Finally we incorporate the Fourier transform lens onto the mask. We obtain excellent experimental results with a phase-only pattern and a shorter optical system. This approach makes these beams much easier to implement

Jellyfish Modulate Bacterial Dynamic and Community Structure

Jellyfish blooms have increased in coastal areas around the world and the outbreaks have become longer and more frequent over the past few decades. The Mediterranean Sea is among the heavily affected regions and the common bloom - forming taxa are scyphozoans Aurelia aurita s.l., Pelagia noctiluca, and Rhizostoma pulmo. Jellyfish have few natural predators, therefore their carcasses at the termination of a bloom represent an organic-rich substrate that supports rapid bacterial growth, and may have a large impact on the surrounding environment. The focus of this study was to explore whether jellyfish substrate have an impact on bacterial community phylotype selection. We conducted in situ jellyfish - enrichment experiment with three different jellyfish species. Bacterial dynamic together with nutrients were monitored to assess decaying jellyfish-bacteria dynamics. Our results show that jellyfish biomass is characterized by protein rich organic matter, which is highly bioavailable to ‘jellyfish - associated’ and ‘free - living’ bacteria, and triggers rapid shifts in bacterial population dynamics and composition. Based on 16S rRNA clone libraries and denaturing gradient gel electrophoresis (DGGE) analysis, we observed a rapid shift in community composition from unculturable Alphaproteobacteria to culturable species of Gammaproteobacteria and Flavobacteria. The results of sequence analyses of bacterial isolates and of total bacterial community determined by culture independent genetic analysis showed the dominance of the Pseudoalteromonadaceae and the Vibrionaceae families. Elevated levels of dissolved proteins, dissolved organic and inorganic nutrient release, bacterial abundance and carbon production as well as ammonium concentrations characterized the degradation process. The biochemical composition of jellyfish species may influence changes in the amount of accumulated dissolved organic and inorganic nutrients. Our results can contribute insights into possible changes in bacterial population dynamics and nutrient pathways following jellyfish blooms which have important implications for ecology of coastal waters

Clonally expanded mitochondrial DNA deletions within the choroid plexus in multiple sclerosis

OBJECTIVE: Mitochondrial DNA deletions (Δ-mtDNA) are implicated in the pathogenesis of multiple sclerosis (MS), Parkinson’s disease (PD), Alzheimer’s disease (AD) and ageing. Given the diffuse nature of inflammation in MS, aim of this study was to determine whether Δ-mtDNA caused respiratory deficient cells in excess of age within choroid plexus (CP) and ongoing mutagenesis or clonal expansion accounted for the respiratory deficiency in MS. METHODS: Respiratory chain complex IV and complex II activity was determined sequentially using histochemistry. Δ-mtDNA were characterized using real time PCR, long range PCR, sequencing and single molecule PCR. Sources of reactive oxygen and nitrogen species (RONS) were explored using immunohistochemistry. RESULTS: Respiratory deficient cells (lacking complex IV and with intact complex II activity) within CP epithelium were in excess of age in MS, PD and AD. Subunit-I of complex IV was lacking to a greater extent in MS than controls. Percentage of respiratory deficient cells harboring >50% heteroplasmy level of Δ-mtDNA was significantly greater in MS than PD, AD and controls. Long range PCR and sequencing confirmed Δ-mtDNA. Single molecule PCR identified clonally expanded Δ-mtDNA in MS, despite an increase in sources of RONS. INTERPRETATION: Our findings establish clonal expansion of Δ-mtDNA causing respiratory deficiency in MS and the extraparenchymal intracranial location indicated the potential to involve multiple cell types. Understanding factors that influence clonal expansion of Δ-mtDNA, a molecular link between inflammation and delayed cellular energy failure, may identify potential therapeutic targets for progressive forms of MS as well as other neurodegenerative disorders

International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS

Vortex sensing analysis of radially and pseudo-radially polarized beams

International audienceWe present a simple method to check the exact realization of a radially polarized light beam by means of a vortex-sensing diffraction grating. The use of this grating easily allows the determination of the topological charges included in each of the two circular polarization components of the incident beam. Therefore a pure radially polarized beam can be easily distinguished from a pseudo-radially polarized beam. Experimental results are presented with radial beams generated with two different devices: a patterned radial polarizer and a specially designed liquid crystal device

Generalized diffractive optical elements with asymmetric harmonic response and phase control

International audienceWe report a method to generate phase-only diffractive beam splitters allowing asymmetry of the target diffracted orders, as well as providing a tailored phase difference between the diffracted orders. We apply a well-established design method that requires the determination of a set of numerical parameters, and avoids the use of image iterative algorithms. As a result, a phase lookup table is determined that can be used for any situation where a first-order (blazed) diffractive element is modified to produce higher or- ders with desired intensity and/or phase relation. As examples, we demonstrate the phase difference control on triplicators, as well as on other generalized diffractive elements like bifocal Fresnel lenses and phase masks for the generation of vortex beams. Results are experimentally demonstrated by en- codingthe calculated phasepattern onto parallel-aligned liquid crystalspatial light modulators. © 2013 Optical Society of Americ