Synthetic smooth muscle cell phenotype is associated with increased nicotinamide adenine dinucleotide phosphate oxidase activity: Effect on collagen secretion

ObjectiveSmooth muscle cells (SMCs) from prosthetic vascular grafts secrete higher levels of collagen than aortic SMCs under basal conditions and during incubation with oxidized low-density lipoprotein. We postulated that reactive oxygen species (ROS) contributed to the observed difference. The objective of this study was to assess the effect of ROS on collagen secretion by aortic and graft SMCs and explore the mechanism involved.MethodsSMCs isolated from canine aorta or Dacron thoracoabdominal grafts were incubated with 6-anilinoquinoline-5,8-quinone (LY83583), an agent that induces superoxide production. Type I collagen in the conditioned medium was measured by enzyme-linked immunosorbent assay, and superoxide anion production was measured by lucigenin assay.ResultsLY83583 stimulated a rapid increase in collagen production by graft SMCs that paralleled the LY83583-induced increase in superoxide production. The increase in both collagen and superoxide was greater in graft SMCs than aortic SMCs. Collagen and superoxide production were inhibited by superoxide scavengers. Nicotinamide adenine dinucleotide phosphate (NADPH) induced significantly more superoxide production by graft SMCs than aortic SMCs, suggesting that the NADPH oxidase system was more active in graft SMCs. NADPH oxidase inhibitors blocked the superoxide and collagen production induced by LY83583.ConclusionIn SMCs, the synthetic phenotype is associated with increased NADPH oxidase activity and elevated superoxide production in response to an oxidative stress. Superoxide, in turn, leads to increased collagen production.Clinical RelevanceThe inflammatory process after prosthetic vascular graft implantation causes oxidative stress that can stimulate collagen production by graft SMCs, contributing to the progression of intimal hyperplasia. The exaggerated response of graft SMCs to oxidative stress offers a potential target for therapeutic interventions

Building, Reality, Caring: What Nurses in Three Australian Psychogeriatric Assessment Units Say about the Built Environment

Many people believe that ‘purpose-built’ facilities will diminish some of the challenging behaviours exhibited by older people with dementia or psychiatric conditions. This study aimed to explore and understand what hands-on nurses in psychogeriatric assessment units experience and think of the built environment as a part of their day to day work. Twenty-one unstructured interviews were conducted with nurses at three psychogeriatric assessment units. The units ranged in style from an ancient adapted building to a contemporary 'purpose-built' facility. A critical hermeneutics derived from Gadamer was used to explore the interviews. It found that nurses think of the built environment in relation to the care needs of their patients, and feel bureaucratic restrictions in using the built environment more keenly than the shortcomings of the built environment itself. Nurses saw themselves and their patients as 'outcasts' or victims of those with money and power. The study concludes with suggestions for challenging the status quo, but also considers that being regarded as 'outcasts' allows opportunities to avoid being overly impressed by technological marvels

PTF11iqb: cool supergiant mass-loss that bridges the gap between Type IIn and normal supernovae

The supernova (SN) PTF11iqb was initially classified as a Type IIn event caught very early after explosion. It showed narrow Wolf–Rayet (WR) spectral features on day 2 (as in SN 1998S and SN 2013cu), but the narrow emission weakened quickly and the spectrum morphed to resemble Types II-L and II-P. At late times, H? exhibited a complex, multipeaked profile reminiscent of SN 1998S. In terms of spectroscopic evolution, we find that PTF11iqb was a near twin of SN 1998S, although with somewhat weaker interaction with circumstellar material (CSM) at early times, and stronger interaction at late times. We interpret the spectral changes as caused by early interaction with asymmetric CSM that is quickly (by day 20) enveloped by the expanding SN ejecta photosphere, but then revealed again after the end of the plateau when the photosphere recedes. The light curve can be matched with a simple model for CSM interaction (with a mass-loss rate of roughly 10?4 M? yr?1) added to the light curve of a normal SN II-P. The underlying plateau requires a progenitor with an extended hydrogen envelope like a red supergiant at the moment of explosion, consistent with the slow wind speed (<80?km?s?1) inferred from narrow H? emission. The cool supergiant progenitor is significant because PTF11iqb showed WR features in its early spectrum – meaning that the presence of such WR features does not necessarily indicate a WR-like progenitor. Overall, PTF11iqb bridges SNe IIn with weaker pre-SN mass-loss seen in SNe II-L and II-P, implying a continuum between these types

PTF11iqb: cool supergiant mass-loss that bridges the gap between Type IIn and normal supernovae

The supernova (SN) PTF11iqb was initially classified as a Type IIn event caught very early after explosion. It showed narrow Wolf–Rayet (WR) spectral features on day 2 (as in SN 1998S and SN 2013cu), but the narrow emission weakened quickly and the spectrum morphed to resemble Types II-L and II-P. At late times, H? exhibited a complex, multipeaked profile reminiscent of SN 1998S. In terms of spectroscopic evolution, we find that PTF11iqb was a near twin of SN 1998S, although with somewhat weaker interaction with circumstellar material (CSM) at early times, and stronger interaction at late times. We interpret the spectral changes as caused by early interaction with asymmetric CSM that is quickly (by day 20) enveloped by the expanding SN ejecta photosphere, but then revealed again after the end of the plateau when the photosphere recedes. The light curve can be matched with a simple model for CSM interaction (with a mass-loss rate of roughly 10?4 M? yr?1) added to the light curve of a normal SN II-P. The underlying plateau requires a progenitor with an extended hydrogen envelope like a red supergiant at the moment of explosion, consistent with the slow wind speed (<80?km?s?1) inferred from narrow H? emission. The cool supergiant progenitor is significant because PTF11iqb showed WR features in its early spectrum – meaning that the presence of such WR features does not necessarily indicate a WR-like progenitor. Overall, PTF11iqb bridges SNe IIn with weaker pre-SN mass-loss seen in SNe II-L and II-P, implying a continuum between these types

Brain-inspired nanophotonic spike computing:challenges and prospects

Nanophotonic spiking neural networks (SNNs) based on neuron-like excitable subwavelength (submicrometre) devices are of key importance for realizing brain-inspired, power-efficient artificial intelligence (AI) systems with high degree of parallelism and energy efficiency. Despite significant advances in neuromorphic photonics, compact and efficient nanophotonic elements for spiking signal emission and detection, as required for spike-based computation, remain largely unexplored. In this invited perspective, we outline the main challenges, early achievements, and opportunities toward a key-enabling photonic neuro-architecture using III-V/Si integrated spiking nodes based on nanoscale resonant tunnelling diodes (nanoRTDs) with folded negative differential resistance. We utilize nanoRTDs as nonlinear artificial neurons capable of spiking at high-speeds. We discuss the prospects for monolithic integration of nanoRTDs with nanoscale light-emitting diodes and nanolaser diodes, and nanophotodetectors to realize neuron emitter and receiver spiking nodes, respectively. Such layout would have a small footprint, fast operation, and low power consumption, all key requirements for efficient nano-optoelectronic spiking operation. We discuss how silicon photonics interconnects, integrated photorefractive interconnects, and 3D waveguide polymeric interconnections can be used for interconnecting the emitter-receiver spiking photonic neural nodes. Finally, using numerical simulations of artificial neuron models, we present spike-based spatio-temporal learning methods for applications in relevant AI-based functional tasks, such as image pattern recognition, edge detection, and SNNs for inference and learning. Future developments in neuromorphic spiking photonic nanocircuits, as outlined here, will significantly boost the processing and transmission capabilities of next-generation nanophotonic spike-based neuromorphic architectures for energy-efficient AI applications. This perspective paper is a result of the European Union funded research project ChipAI in the frame of the Horizon 2020 Future and Emerging Technologies Open programme.</p

Damping scales of neutralino cold dark matter

The lightest supersymmetric particle, most likely the neutralino, might account for a large fraction of dark matter in the Universe. We show that the primordial spectrum of density fluctuations in neutralino cold dark matter (CDM) has a sharp cut-off due to two damping mechanisms: collisional damping during the kinetic decoupling of the neutralinos at about 30 MeV (for typical neutralino and sfermion masses) and free streaming after last scattering of neutralinos. The last scattering temperature is lower than the kinetic decoupling temperature by one order of magnitude. The cut-off in the primordial spectrum defines a minimal mass for CDM objects in hierarchical structure formation. For typical neutralino and sfermion masses the first gravitationally bound neutralino clouds have to have masses above 10^(-7) solar masses.Comment: 13 pages, 5 figures; typos corrected; accepted by Physical Review

Multilocal programming and applications

Preprint versionMultilocal programming aims to identify all local minimizers of unconstrained or constrained nonlinear optimization problems. The multilocal programming theory relies on global optimization strategies combined with simple ideas that are inspired in deflection or stretching techniques to avoid convergence to the already detected local minimizers. The most used methods to solve this type of problems are based on stochastic procedures and a population of solutions. In general, population-based methods are computationally expensive but rather reliable in identifying all local solutions. In this chapter, a review on recent techniques for multilocal programming is presented. Some real-world multilocal programming problems based on chemical engineering process design applications are described.Fundação para a Ciência e a Tecnologia (FCT