Low-power-consumption coherent receiver architecture for satellite optical links

As the demand for satellite data transmission increases, higher capacity optical links need to be developed to allow satellites to be connected directly to ground stations (GST). The advantages of Low Earth Orbit (LEO) direct-to-Earth links are smaller latency when compared to relay systems using Geostationary Orbit (GEO) satellites, i.e. LEO-to-GEO and GEO-to-GST, and an increased available bandwidth offered by the optical spectrum with respect to radio frequency (RF) which allows for much higher link capacity. The increase in data rate of optical satellite to ground links towards 100 Gbps will require implementing optical coherent transceivers with capability to compensate for Doppler shift and atmospheric channel impairments. An important figure of merit which needs to be carefully considered in a satellite system is the equipment power consumption. The power consumption of coherent receivers used for terrestrial applications is closely related to the bit rate, with a receiver back-end digital signal processing being responsible for the vast majority of the power consumed. In this paper we propose a hybrid approach to signal processing consisting of simplified digital and analogue elements allowing for significant power reduction. Moreover, one of the attractive aspects of the proposed approach is that it does not require an increased complexity for an increase in baud rate. It will be discussed that the analogue approach to the frequency and phase recovery would allow a saving of approximately 40% to 50% of power on the overall DSP block at baud rates between 10 Gbaud and 100 Gbaud

Phase locking of an Optical Injection Phase-lock Loop coherent receiver under emulated atmospheric fading conditions

An Optical Injection Phase-Lock Loop coherent receiver has been tested against various levels of deep atmospheric fading to experimentally evaluate its feasibility in a ground-to-satellite optical communications application

The effects of endogenous and exogenous androgens on cardiovascular disease risk factors and progression

Cardiovascular disease incidence rates have long been known to significantly differ between the two sexes. Estrogens alone fail to explain this phenomenon, bringing an increasing amount of attention to the role of androgens. Contrary to what was initially hypothesized, androgens seem to have an overall cardioprotective effect, especially in men. Recent studies and published data continue to support this notion displaying a consistent inverse correlation with atherosclerosis progression and cardiovascular disease both in regressive and prospective study models. Clinical studies have also revealed what seems to be a differential androgenic effect on various cardiovascular risk factors between men and women. Further insight indicates that in order to avoid confusion it may be also preferable to separately examine the effects of endogenous androgen levels from exogenous testosterone administration, as well as discern the differential results of low to normal and supraphysiological administration doses. This review summarizes old and recent data according to the above distinctions, in an attempt to further our understanding of the role of androgens in cardiovascular disease

NMR-Based Metabolomics: The Foodome and the Assessment of Dietary Exposure as a Key Step to Evaluate the Effect of Diet on Health

NMR-based metabolomics has gained important insight into the associations between the metabolic status and health, as metabolomics signatures are found in blood, urine, stools, or saliva, differentiating healthy subjects from those affected by diseases or disorders. Although health status has been linked to diet, a measurable fingerprint is rarely found within the metabolome, demonstrating that the diet is curing or, at least, is modifying the subject metabolome away from or closer to a healthy status. The success in finding the correlation between the metabolome and a diet-related disease has, as the main obstacle, the inability to characterize the actual diet followed by the subject. Thus, a big scientific effort has been launched to find metabolite patterns which are characterizing precisely the personal food consumption in order to classify people according to their actual diet. Most of the studies based on NMR-metabolomics are focused on finding biomarkers within the dietary exposome, e.g., originating from food or gut microbiota, without a specific focus on the endogenous metabolome. The main drawback in such approach is a combination of: (i) the actual composition of the meal, (ii) the bioaccessibility of bioactive compounds, and (iii) the processing capability of the gut microbiota. In this chapter, these three aspects are illustrated, where NMR spectroscopy (effectively or potentially) gains relevant information in the discovery of biomarkers for the true food consumption, as a preliminary step in successful \u201cdietary effect studies.\u201