Photoactive organic-inorganic hybrid polymer waveguides for optical device technologies

© 2020 SPIE. Organic-inorganic hybrid polymers based on ureasils have found application as waveguides in luminescent solar concentrators and visible light communications. The mechanical properties, and thus processability of ureasils, has previously been qualitatively linked to the chemical structure, but has not yet been studied in detail. In this study, a series of low molecular weight ureasil polymers has been synthesised, and the correlation between the chemical structure and the optical and mechanical properties investigated. A wide-range of techniques are employed to investigate this relationship, including steady-state photoluminescence and Fourier-transform infrared spectroscopy, 4-point flexural testing, and uniaxial tensile testing.This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 818762 - SPECTRACON). T. J. F. S. thanks the EPSRC (EP/N509620/1) for financial support

Flexible Blue-Light Fiber Amplifiers to Improve Signal Coverage in Advanced Lighting Communication Systems

Visible-light communication (VLC) based on white light-emitting diodes has recently attracted much attention to provide high-bitrate data communication in indoor environments. One of the remaining challenges to be resolved to enable the proliferation of VLC systems is related to channel attenuation and multiple path fading. Here, we introduce an advanced VLC system integrating an optical amplifier as a promising solution to overcome channel impairments, providing high bitrate coverage. The optical amplifier is a flexible fiber based on a poly(fluorene)-based lumophore doped within a di-ureasil organic-inor- ganic hybrid. Optical amplification is demonstrated for pre-amplifier and relay node scenarios, yielding a maximum gain of 5.9 G 0.2 dB and 3.7 G 0.2 dB, respectively, establishing the proposed approach as a promising cost-effective solution for VLCs. Additionally, numerical simulations show, for a realistic envi- ronment, a 207% improvement in the coverage area, using existing lighting infrastructure without extra cost.R.C.E. acknowledges funding from the European Research Council (ERC) under the European Union’s Ho- rizon 2020 research and innovation programme (grant agreement no. 818762 - SPECTRACON)

Thermoresponsive Host Polymer Matrix for Self-Healing Luminescent Solar Concentrators

© 2019 American Chemical Society. Luminescent solar concentrators (LSCs) are a promising solar energy technology for reducing architectural barriers to the integration of photovoltaic systems into the built environment. In this work, the first demonstration of thin-film LSCs based on a thermally reversible cross-linked host polymer is presented. This smart material is obtained via a dynamic-chemistry approach based on the Diels-Alder (DA) reaction between a furan-functionalized acrylic copolymer and an aliphatic bismaleimide to obtain optically clear, cross-linked systems capable of healing mechanical damage upon heat treatment. By carefully tuning the concentration of a perylene-based luminophore dopant, an optical efficiency as high as 4.9% can be achieved with this DA-based LSC. In addition, full recovery of device efficiency is demonstrated after complete thermal healing of mechanically induced surface damages as a result of the embedded DA functionality. The approach presented here paves the way to the development of highly efficient multifunctional thermoresponsive smart LSC systems.European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 818762

Dynamic input demand functions and resource adjustment for US agriculture: state evidence

The paper presents an econometric model of dynamic agricultural input demand functions that include research based technical change and autoregressive disturbances and fits the model to annual data for a set of state aggregates pooled over 1950–1982. The methodological approach is one of developing a theoretical foundation for a dynamic input demand system and accepting state aggreage behavior as approximated by nonlinear adjustment costs and long-term profit maximization. Although other studies have largely ignored autocorrelation in dynamic input demand systems, the results show shorter adjustment lags with autocorrelation than without. Dynamic input demand own-price elasticities for the six input groups are inelastic, and the demand functions possess significant cross-price and research effects

Risk Factors for HIV-1 seroconversion among Taiwanese men visiting gay saunas who have sex with men

<p>Abstract</p> <p>Background</p> <p>Men having sex with men (MSM) accounts for 33.6% of all reported cases of HIV-1 infection in Taiwan. The aim of this study was to investigate the epidemiology of HIV-1 infection among MSM in gay saunas in Taiwan.</p> <p>Methods</p> <p>Patrons of 5 gay saunas were recruited for a weekly volunteer counseling and testing program from 2001 to 2005. Questionnaires were collected for a risk factor analysis. HIV-1 subtypes were determined using DNA sequencing and phylogenetic analyses.</p> <p>Results</p> <p>HIV-1 prevalence rates among MSM in gay saunas in 2001 through 2005 were 3.4%, 5.1%, 8.9%, 8.5%, and 8.3%, respectively. In total, 81 of 1, 093 (7.4%) MSM had HIV-1 infection. Fifty-two HIV-1 strains were genotyped, and all of them were subtype B. HIV-seropositive men were significantly younger than the seronegatives. Only 37.1% used condoms every time during sexual intercourse. A multivariate logistic regression analysis showed that the risk factors for HIV-1 were being uncircumcised (odds ratio (OR) = 2.19; 95% confidence interval (CI), 1.08~4.45); having sexual intercourse with at least 2 partners during each sauna visit (≥ 2 vs. ≤ 1, OR = 1.71; 95% CI, 1.02~2.89); and the role played during anal intercourse (versatile vs. an exclusively insertive role, OR = 2.76; 95% CI, 1.42~5.36).</p> <p>Conclusions</p> <p>Overall, 7.4% Taiwanese MSM participating in this study had HIV-1 subtype B infection. Uncircumcised, being versatile role during anal intercourse, and having sex with more than one person during each sauna visit were main risk factors for HIV-1 infection.</p

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Etoposide Induces ATM-Dependent Mitochondrial Biogenesis through AMPK Activation

DNA damage such as double-stranded DNA breaks (DSBs) has been reported to stimulate mitochondrial biogenesis. However, the underlying mechanism is poorly understood. The major player in response to DSBs is ATM (ataxia telangiectasia mutated). Upon sensing DSBs, ATM is activated through autophosphorylation and phosphorylates a number of substrates for DNA repair, cell cycle regulation and apoptosis. ATM has been reported to phosphorylate the alpha subunit of AMP-activated protein kinase (AMPK), which senses AMP/ATP ratio in cells, and can be activated by upstream kinases. Here we provide evidence for a novel role of ATM in mitochondrial biogenesis through AMPK activation in response to etoposide-induced DNA damage.Three pairs of human ATM+ and ATM- cells were employed. Cells treated with etoposide exhibited an ATM-dependent increase in mitochondrial mass as measured by 10-N-Nonyl-Acridine Orange and MitoTracker Green FM staining, as well as an increase in mitochondrial DNA content. In addition, the expression of several known mitochondrial biogenesis regulators such as the major mitochondrial transcription factor NRF-1, PGC-1alpha and TFAM was also elevated in response to etoposide treatment as monitored by RT-PCR. Three pieces of evidence suggest that etoposide-induced mitochondrial biogenesis is due to ATM-dependent activation of AMPK. First, etoposide induced ATM-dependent phosphorylation of AMPK alpha subunit at Thr172, indicative of AMPK activation. Second, inhibition of AMPK blocked etoposide-induced mitochondrial biogenesis. Third, activation of AMPK by AICAR (an AMP analogue) stimulated mitochondrial biogenesis in an ATM-dependent manner, suggesting that ATM may be an upstream kinase of AMPK in the mitochondrial biogenesis pathway.These results suggest that activation of ATM by etoposide can lead to mitochondrial biogenesis through AMPK activation. We propose that ATM-dependent mitochondrial biogenesis may play a role in DNA damage response and ROS regulation, and that defect in ATM-dependent mitochondrial biogenesis could contribute to the manifestations of A-T disease

Genetic instability and anti-HPV immune response as drivers of infertility associated with HPV infection

Funding Information: RFBR grant 17–54-30002, Ministry of Science and Higher Education of the Russian Federation (Agreement No. 075–15–2019-1660) to Olga Smirnova. Publisher Copyright: © 2021, The Author(s).Human papillomavirus (HPV) is a sexually transmitted infection common among men and women of reproductive age worldwide. HPV viruses are associated with epithelial lesions and cancers. HPV infections have been shown to be significantly associated with many adverse effects in reproductive function. Infection with HPVs, specifically of high-oncogenic risk types (HR HPVs), affects different stages of human reproduction, resulting in a series of adverse outcomes: 1) reduction of male fertility (male infertility), characterized by qualitative and quantitative semen alterations; 2) impairment of couple fertility with increase of blastocyst apoptosis and reduction of endometrial implantation of trophoblastic cells; 3) defects of embryos and fetal development, with increase of spontaneous abortion and spontaneous preterm birth. The actual molecular mechanism(s) by which HPV infection is involved remain unclear. HPV-associated infertility as Janus, has two faces: one reflecting anti-HPV immunity, and the other, direct pathogenic effects of HPVs, specifically, of HR HPVs on the infected/HPV-replicating cells. Adverse effects observed for HR HPVs differ depending on the genotype of infecting virus, reflecting differential response of the host immune system as well as functional differences between HPVs and their individual proteins/antigens, including their ability to induce genetic instability/DNA damage. Review summarizes HPV involvement in all reproductive stages, evaluate the adverse role(s) played by HPVs, and identifies mechanisms of viral pathogenicity, common as well as specific for each stage of the reproduction process.publishersversionPeer reviewe

High-frequency variability in neutron-star low-mass X-ray binaries

Binary systems with a neutron-star primary accreting from a companion star display variability in the X-ray band on time scales ranging from years to milliseconds. With frequencies of up to ~1300 Hz, the kilohertz quasi-periodic oscillations (kHz QPOs) represent the fastest variability observed from any astronomical object. The sub-millisecond time scale of this variability implies that the kHz QPOs are produced in the accretion flow very close to the surface of the neutron star, providing a unique view of the dynamics of matter under the influence of some of the strongest gravitational fields in the Universe. This offers the possibility to probe some of the most extreme predictions of General Relativity, such as dragging of inertial frames and periastron precession at rates that are sixteen orders of magnitude faster than those observed in the solar system and, ultimately, the existence of a minimum distance at which a stable orbit around a compact object is possible. Here we review the last twenty years of research on kHz QPOs, and we discuss the prospects for future developments in this field.Comment: 66 pages, 37 figures, 190 references. Review to appear in T. Belloni, M. Mendez, C. Zhang, editors, "Timing Neutron Stars: Pulsations, Oscillations and Explosions", ASSL, Springe