The association between cardiorespiratory fitness and cardiometabolic risk in children is mediated by abdominal adiposity: the HAPPY study

Background: It is unclear whether cardiorespiratory fitness (CRF) is independently linked to cardiometabolic risk in children. This study investigated a) the association between CRF level and presence of cardiometabolic risk disorders using health-related cut points, and b) whether these associations were mediated by abdominal adiposity in children. Methods: This was a cross-sectional design study. Anthropometry, biochemical parameters and CRF were assessed in 147 schoolchildren (75 girls) aged 10-14 years. CRF was determined using a maximal cycle ergometer test. Children were classified as ‘fit’ or ‘unfit’ according to published thresholds. Logistic regression was used to investigate the odds of having individual and clustered cardiometabolic risk factors according to CRF level and whether abdominal adiposity mediated these associations. Results: Children classified as unfit had increased odds of presenting individual and clustered cardiometabolic risk factors (p 0.05). Conclusions: This study suggests that the association between CRF and cardiometabolic risk is mediated by abdominal adiposity in 10-14 year-old children and that abdominal adiposity may be a more important determinant of adverse cardiometabolic health in this age group

End-of-life issues in the acute and critically ill patient

The challenges of end-of-life care require emergency physicians to utilize a multifaceted and dynamic skill set. Such skills include medical therapies to relieve pain and other symptoms near the end-of-life. Physicians must also demonstrate aptitude in comfort care, communication, cultural competency, and ethical principles. It is imperative that emergency physicians demonstrate a fundamental understanding of end-of-life issues in order to employ the versatile, multidisciplinary approach required to provide the highest quality end-of-life care for patients and their families

Throughput gains from adaptive transceivers in nonlinear elastic optical networks

In this paper, we link the throughput gains, due to transceiver adaptation, in a point-to-point transmission link to the expected gains in a mesh network. We calculate the maximum network throughput for a given topology as we vary the length scale. We show that the expected gain in the network throughput due to transceiver adaptation is equivalent to the gain in a point-to-point link with a length equal to the mean length of the optical paths across the minimum network cut. We also consider upper and lower bounds on the variation of the gain in the network throughput due to transceiver adaptation, where integer-constrained channel bandwidth assignment and quantized adaptations are considered. This bounds the variability of results that can be expected and indicates why some networks can give apparently optimistic or pessimistic results. We confirm the results of previous authors that show finer quantization steps in the adaptive control lead to an increase in the throughput since the mean loss of throughput per transceiver is reduced. Finally, we consider the likely network advantage of digital nonlinear mitigation and show that a significant tradeoff occurs between the increase in the signal-to-noise ratio for larger mitigation bandwidths and the loss of throughput when routing fewer large-bandwidth superchannels

Throughput gains from adaptive transceivers in nonlinear elastic optical networks

In this paper, we link the throughput gains, due to transceiver adaptation, in a point-to-point transmission link to the expected gains in a mesh network. We calculate the maximum network throughput for a given topology as we vary the length scale. We show that the expected gain in the network throughput due to transceiver adaptation is equivalent to the gain in a point-to-point link with a length equal to the mean length of the optical paths across the minimum network cut. We also consider upper and lower bounds on the variation of the gain in the network throughput due to transceiver adaptation, where integer-constrained channel bandwidth assignment and quantized adaptations are considered. This bounds the variability of results that can be expected and indicates why some networks can give apparently optimistic or pessimistic results. We confirm the results of previous authors that show finer quantization steps in the adaptive control lead to an increase in the throughput since the mean loss of throughput per transceiver is reduced. Finally, we consider the likely network advantage of digital nonlinear mitigation and show that a significant tradeoff occurs between the increase in the signal-to-noise ratio for larger mitigation bandwidths and the loss of throughput when routing fewer large-bandwidth superchannels

Designing adaptive coded modulation for optical networks via achievable information rates

© 2017 IEEE. Achievable information rates are discussed as a tool to analyse and design optical networks. It is shown that the maximum throughput of the network and its dependency of different network parameters can be predicted with such a tool

Hidden spontaneous polarisation in the chalcohalide photovoltaic absorber Sn2SbS2I3

Perovskite-inspired materials aim to replicate the optoelectronic performance of lead-halide perovskites, while eliminating issues with stability and toxicity. Chalcohalides of group IV/V elements have attracted attention due to enhanced stability provided by stronger metal-chalcogen bonds, alongside compositional flexibility and ns2 lone pair cations – a performance-defining feature of halide perovskites. Following the experimental report of solution-grown tin-antimony sulfoiodide (Sn2SbS2I3) solar cells, with power conversion efficiencies above 4%, we assess the structural and electronic properties of this emerging photovoltaic material. We find that the reported centrosymmetric Cmcm crystal structure represents an average over multiple polar Cmc21 configurations. The instability is confirmed through a combination of lattice dynamics and molecular dynamics simulations. We predict a large spontaneous polarisation of 37 μC cm−2 that could be active for electron–hole separation in operating solar cells. We further assess the radiative efficiency limit of this material, calculating ηmax > 30% for film thicknesses t > 0.5 μm

Maximizing the information throughput of ultra-wideband fiber-optic communication systems

Maximized information rates of ultra-wideband (typically, beyond 100~nm modulated bandwidth) lumped-amplified fiber-optic communication systems have been thoroughly examined accounting for the wavelength dependencies of optical fiber parameters in conjunction with the impact of the inelastic inter-channel stimulated Raman scattering (SRS). Three strategies to maximize point-to-point link throughput were proposed: optimizations of non-uniformly and uniformly distributed launch power per channel and the optimization based on adjusting to the target 3 dB ratio between the power of linear amplified spontaneous emission and nonlinear interference noise. The results clearly emphasize the possibility to approach nearly optimal system performance by means of implementing pragmatic engineering sub-optimal optimization strategies

Network equipment and their procurement strategy for high capacity elastic optical networks

© 2016 Optical Society of America. In elastic optical networks, the success of providing high network capacity depends on the optical signal-to-noise ratio (OSNR) values of network lightpaths. As each lightpaths OSNR value defines the modulation format and capacity it can support, having high OSNRlightpaths is always beneficial. Hence, with a given set of modulation formats, service providers need to optimize their optical infrastructure, including in-line amplifiers and reconfigurable optical add-drop multiplexers (ROADMs), given the size and topology of their core networks. This also will have a direct impact on vendors who need strong insight into the requirements of service providers and their networks in terms of equipment and new technology. Therefore, in this paper a comprehensive model based on the local optimization which leads to a global network optimization (LOGON) strategy of the Gaussian noise (GN) model has been proposed, which helps in estimating the lightpath OSNR and clearly quantifies the noise contributions from in-line amplifiers and post-amplification at the ROADMs. The model introduces closed-form expressions to calculate nonlinear impairment (NLI) contributions for various span lengths while using either erbium-doped fiber amplifiers (EDFAs) or H-Raman amplifiers, which helps in optimizing the signal launch power to achieve maximum link OSNR. In addition to this, an offline strategy has been proposed that can help service providers to optimize their procurement of network equipment upfront and give insight into how much of the capacity bottleneck is alleviated in their networks if they do this. To demonstrate all of the above, the UK, Pan-European, and US Core networks have been considered, which illustrate differences in link lengths and reduced node density. It is seen that improving the OSNR conditions at the ROADM increases the network capacity when noise from in-line amplifiers is significantly reduced. Among the three networks, we found that the UK network responded the most to improved OSNR conditions at the ROADM nodes due to small link lengths and less line noise. Among the amplifiers, we found that improving ROADMs while having H-Raman in the links resulted in a maximum capacity increase. For the UK network at FG=12.5 GHz, the capacity increases by 6650 Gbps, while for the larger Pan-European and US networks, the capacity increase reduces to 4550 and 1600 Gbps due to increased link lengths and line noise. Further, following the offline strategy, we are able to accommodate 1737, 1481, and 615 100G demands using H-Raman for the UK, Pan-EU, and US networks at FG=12.5 GHz until 10%blocking is reached. Thereby, H-Raman provides 7.5%, 35.8%, and 94.9%extra capacity, respectively, for the UK, Pan-EU, and US. Finally, using H-Raman, all lightpaths in the UK network operate at PM-64QAM with maximum capacity at the end of the procedure.INSIGHT - EP/L026155/

The benefit of split nonlinearity compensation for single-channel optical fiber communications

In this Letter we analyze the benefit of digital compensation of fiber nonlinearity, where the digital signal processing is divided between the transmitter and receiver. The application of the Gaussian noise model indicates that, where there are two or more spans, it is always beneficial to split the nonlinearity compensation. The theory is verified via numerical simulations, investigating transmission of single channel 50 GBd polarization division multiplexed 256-ary quadrature amplitude modulation over 100 km standard single mode fiber spans, using lumped amplification. For this case, the additional increase in mutual information achieved over transmitter- or receiver-side nonlinearity compensation is approximately 1 bit for distances greater than 2000 km. Further, it is shown, theoretically, that the SNR gain for long distances and high bandwidth transmission is 1.5 dB versus transmitter- or receiver-based nonlinearity compensation