Ultrafast-pulse diagnostic using third-order frequency-resolved optical gating in organic films

We report on the diagnostic of ultrafast pulses by frequency-resolved optical gating (FROG) based on strong third-harmonic generation (THG) in amorphous organic thin films. The high THG conversion efficiency of these films allows for the characterization of sub-nanojoule short pulses emitting at telecommunication wavelengths using a low cost portable fiber spectrometer

Third-order optical autocorrelator for time-domain operation at telecommunication wavelengths

We report on amorphous organic thin films that exhibit efficient third-harmonic generation at telecommunication wavelengths. At 1550 nm, micrometer-thick samples generate up to 17 µW of green light with input power of 250 mW delivered by an optical parametric oscillator. This high conversion efficiency is achieved without phase matching or cascading of quadratic nonlinear effects. With these films, we demonstrate a low-cost, sensitive third-order autocorrelator that can be used in the time-frequency domain

Ovarian hormones modify anxiety behavior and glucocorticoid receptors after chronic social isolation stress

Chronic social isolation could lead to a disruption in the Hypothalamic-Pituitary-Adrenal (HPA) axis, resulting in anxiety and depressive-like behaviors but cycling estrogens could modify these behaviors. The aim of this study was to determine if changes in ovarian hormones during the normal cycle could interact with social isolation to alter anxiety and depressive-like behaviors. In parallel, we examined the expression of glucocorticoid receptor (GR) and synaptic vesicle protein synaptophysin in the hippocampus and hypothalamus of Sprague Dawley normal cycling female rats. We assigned rats to either isolated or paired housing for 8 weeks. To assess anxiety and depressive-like behaviors, we used the open field test and forced swim test, respectively. Female rats were tested at either diestrus, estrus, or proestrus stage of the estrous cycle. After behaviors, rats were perfused and brains collected. Brain sections containing hippocampus and hypothalamus were analyzed using immunohistochemistry for synaptophysin and glucocorticoid receptor (GR) levels. We found an increase in depressive-like behaviors for isolated animals compared to paired housed rats, regardless of the estrous cycle stage. Interestingly, we found a decrease in anxiety behaviors in females in the estrus stage accompanied by a decrease in GR expression in hippocampal DG and CA3. However, no changes in synaptophysin were observed in any of the areas of studied. Our results support the beneficial effects of circulating ovarian hormones in anxiety, possibly by decreasing GR expression

Publisher’s Note: “Dispersion calibration for the National Ignition Facility electron–positron–proton spectrometers for intense laser matter interactions” [Rev. Sci. Instrum. 92, 033516 (2021)] (Rev. Sci. Instrum. 92, 059902 (2021)

Electron-positron pairs, produced in intense laser-solid interactions, are diagnosed using magnetic spectrometers with image plates, such as the National Ignition Facility (NIF) Electron Positron Proton Spectrometers (EPPS). Although modeling can help infer the quantitative value, the accuracy of the models needs to be verified to ensure measurement quality. The dispersion of low-energy electrons and positrons may be affected by fringe magnetic fields near the entrance of the EPPS. We have calibrated the EPPS with six electron beams from a Siemens Oncor linear accelerator (linac) ranging in energy from $2.7$--$15.2$ $\mathrm{MeV}$ as they enter the spectrometer. A Geant4 TOPAS Monte-Carlo simulation was set up to match depth dose curves and lateral profiles measured in water at $100$ $\mathrm{cm}$ source-surface distance. An accurate relationship was established between the bending magnet current setting and the energy of the electron beam at the exit window. The simulations and measurements were used to determine the energy distributions of the six electron beams at the EPPS slit. Analysis of the scanned image plates together with the determined energy distribution arriving in the spectrometer provide improved dispersion curves for the EPPS.Comment: Published in Review of Scientific Instruments, 5 pages, 3 figures, This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishin

The Halo and Rings of the Planetary Nebula NGC 40 in the Mid-Infrared

We present imaging and spectroscopy of NGC 40 acquired using the Spitzer Space Telescope (Spitzer), and the Infrared Space observatory (ISO). These are used to investigate the nature of emission from the central nebular shell, from the nebular halo, and from the associated circumnebular rings. It is pointed out that a variety of mechanisms may contribute to the mid-infrared (MIR) fluxes, and there is evidence for a cool dust continuum, strong ionic transitions, and appreciable emission by polycyclic aromatic hydrocarbons (PAHs). Prior observations at shorter wavelengths also indicate the presence of warmer grains, and the possible contribution of H2 transitions. It is suggested that an apparent jet-like structure to the NE of the halo represents one of the many emission spokes that permeate the shell. The spokes are likely to be caused by the percolation of UV photons through a clumpy interior shell, whilst the jet-like feature is enhanced due to locally elevated electron densities; a result of interaction between NGC 40 and the interstellar medium. It is finally noted that the presence of the PAH, 21 microns and 30 microns spectral features testifies to appreciable C/O ratios within the main nebular shell. Such a result is consistent with abundance determinations using collisionally excited lines, but not with those determined using optical recombination linesComment: 13 pages, 8 figures, Accepted for publication in MNRAS. 37 pages in arXi

Spitzer Mid-Infrared Observations of Seven Bipolar Planetary Nebulae

We have investigated the mid-infrared (MIR) and visual structures of seven bipolar planetary nebulae (BPNe), using imaging and spectroscopy acquired using the Spitzer Space Telescope (SST), and the Observatorio Astronomico Nacional in Mexico. The results show that the sources are more extended towards longer MIR wavelengths, as well as having higher levels of surface brightness in the 5.8 and 8.0 microns bands. It is also noted that the 5.8/4.5 and 8.0/4.5 microns flux ratios increase with increasing distance from the nuclei of the sources. All of these latter trends may be attributable to emission by polycyclic aromatic hydrocarbons (PAHs) and/or warm dust continua within circum-nebular photo-dissociation regions (PDRs). A corresponding decrease in the flux ratios 8.0/5.8 microns may, by contrast, arise due to changes in the properties of the PAH emitting grains. We note evidence for possible 8.0 microns ring-like structures in the envelope of NGC 2346, located in a region beyond the minor axis limits of the ionized envelope. An analysis of the inner two rings shows that whilst they have higher surface brightnesses at longer MIR wavelengths, they are relatively stronger (compared to underlying emission) at 3.6 and 4.5 microns. There is also evidence for point reflection symmetry along the major axis of the outflow.Comment: 27 pages, 22 figures, Accepted for publication in MNRAS. 69 pages in arXi

Vascular interstitial cells in retinal arteriolar annuli are altered during hypertension

The authors thank Veronica Melgarejo, Lorena Noya, and Angel Vazquez for technical assistance. Supported by grants from Instituto de Salud Carlos III (PI12/00605, PI16/00719, SAF2014-59945-R, and Red de Investigación Renal REDinREN 12/0021/0013), Spain; Fundação para a Ciência e a Tecnologia (SFRH/BPD/102573/2014, SFRH/BD/95330/2013), Ministerio da Educação e Ciência, Portugal; and Fondo Europeo de Desarrollo Regional (FEDER).Supported by grants from Instituto de Salud Carlos III (PI12/00605, PI16/00719, SAF2014-59945-R, and Red de Investigacion Renal REDinREN 12/0021/0013), Spain; Fundacao para a Ciencia e a Tecnologia (SFRH/BPD/102573/2014, SFRH/BD/95330/2013), Ministerio da Educacao e Ciencia, Portugal; and Fondo Europeo de Desarrollo Regional (FEDER).PURPOSE. It has been suggested that arteriolar annuli localized in retinal arterioles regulate retinal blood flow acting as sphincters. Here, the morphology and protein expression profile of arteriolar annuli have been analyzed under physiologic conditions in the retina of wildtype, β-actin-Egfp, and Nestin-gfp transgenic mice. Additionally, to study the effect of hypertension, the KAP transgenic mouse has been used. METHODS. Cellular architecture has been studied using digested whole mount retinas and transmission electron microscopy. The profile of protein expression has been analyzed on paraffin sections and whole mount retinas by immunofluorescence and histochemistry. RESULTS. The ultrastructural analysis of arteriolar annuli showed a different cell population found between endothelial and muscle cells that matched most of the morphologic criteria established to define interstitial Cajal cells. The profile of protein expression of these vascular interstitial cells (VICs) was similar to that of interstitial Cajal cells and different from the endothelial and smooth muscle cells, because they expressed b-actin, nestin, and CD44, but they did not express CD31 and a-SMA or scarcely express F-actin. Furthermore, VICs share with pericytes the expression of NG2 and platelet-derived growth factor receptor beta (PDGFR-β). The high expression of Ano1 and high activity of nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase observed in VICs was diminished during hypertensive retinopathy suggesting that these cells might play a role on the motility of arteriolar annuli and that this function is altered during hypertension. CONCLUSIONS. A novel type of VICs has been described in the arteriolar annuli of mouse retina. Remarkably, these cells undergo important molecular modifications during hypertensive retinopathy and might thus be a therapeutic target against this disease