With plans for advancing into the rest of the solar system in the coming decades, an understanding of how interlinked satellite systems behave as a network will be essential. The relatively recent development of optics as a method of space communication means that inter-satellite networks are more feasible than ever. That said, there are currently no analyses which take into account a planet-wide, largely uncoordinated, optically linked satellite network. To provide a look at the properties of such a network, movement and connections of Earth's currently active satellites were simulated based on real-world data, and their networks modeled via graphs. Ultimately, it was found that many properties of such a network are periodic, fluctuating in sync with the orbital time of low-earth orbit satellites. This, among other data, suggests that the peaks of these waves are caused by a meeting of satellites near the north and south poles.

The Twomey effect describes the radiative forcing associated with a change in cloud albedo due to an increase in anthropogenic aerosol emissions. It is driven by the perturbation in cloud droplet number concentration (1Nd; ant) in liquid-water clouds and is currently understood to exert a cooling effect on climate. The Twomey effect is the key driver in the effective radiative forcing due to aerosol–cloud interactions, but rapid adjustments also contribute. These adjustments are essentially the responses of cloud fraction and liquid water path to 1Nd; ant and thus scale approximately with it. While the fundamental physics of the influence of added aerosol particles on the droplet concentration (Nd) is well described by established theory at the particle scale (micrometres), how this relationship is expressed at the large-scale (hundreds of kilometres) perturbation, 1Nd; ant, remains uncertain. The discrepancy between process understanding at particle scale and insufficient quantification at the climate-relevant large scale is caused by co-variability of aerosol particles and updraught velocity and by droplet sink processes. These operate at scales on the order of tens of metres at which only localised observations are available and at which no approach yet exists to quantify the anthropogenic perturbation. Different atmospheric models suggest diverse magnitudes of the Twomey effect even when applying the same anthropogenic aerosol emission perturbation. Thus, observational data are needed to quantify and constrain the Twomey effect. At the global scale, this means satellite data. There are four key uncertainties in determining 1Nd; ant, namely the quantification of (i) the cloud-active aerosol – the cloud condensation nuclei (CCN) concentrations at or above cloud base, (ii) Nd, (iii) the statistical approach for inferring the sensitivity of Nd to aerosol particles from the satellite data and (iv) uncertainty in the anthropogenic perturbation to CCN concentrations, which is not easily accessible from observational data. This review discusses deficiencies of current approaches for the different aspects of the problem and proposes several ways forward: in terms of CCN, retrievals of optical quantities such as aerosol optical depth suffer from a lack of vertical resolution, size and hygroscopicity information, non-direct relation to the concentration of aerosols, difficulty to quantify it within or below clouds, and the problem of insufficient sensitivity at low concentrations, in addition to retrieval errors. A future path forward can include utilising co-located polarimeter and lidar instruments, ideally including high-spectral-resolution lidar capability at two wavelengths to maximise vertically resolved size distribution information content. In terms of Nd, a key problem is the lack of operational retrievals of this quantity and the inaccuracy of the retrieval especially in broken-cloud regimes. As for the Nd-to-CCN sensitivity, key issues are the updraught distributions and the role of Nd sink processes, for which empirical assessments for specific cloud regimes are currently the best solutions. These considerations point to the conclusion that past studies using existing approaches have likely underestimated the true sensitivity and, thus, the radiative forcing due to the Twomey effect.

Yes / This paper is concerned with the effects on the network performance of moving parts of what is considered traditionally to belong to the ground segment to on board the satellite. Initially, an overview of geostationary satellite communication systems and payload technology is presented, followed by a description of the network architecture and protocols that are the basis of the simulation models. The results obtained from this testbed are presented before concluding with a discussion of the results obtained.

No description available.

Resistance exercise training is the most effective and accepted strategy for increasing skeletal muscle mass and strength. There is tremendous individual variability in the adaptive response to exercise and the source(s) contributing to this variability are largely unknown. Recent evidence in the literature supports the notion that capillaries may be a potential target for improving outcomes to chronic resistance exercise. Aerobic exercise training is a proven stimulus for eliciting angiogenesis and increasing capillary content. Therefore, we hypothesize that completing a period of aerobic training prior to resistance training will result in a greater increase in fibre cross sectional area (CSA) compared to resistance training alone. Fourteen participants (8M, 6F) completed 6 weeks of unilateral single leg aerobic training prior to undergoing 10 weeks of bilateral lower body resistance exercise training. Performance and anthropometric measures were completed at baseline, post aerobic training and post resistance training. Skeletal muscle biopsies were obtained from the vastus lateralis and immunofluorescent staining of muscle cross sections was completed to determine fibre CSA and satellite cell content. Following unilateral aerobic training, single leg VO2 work peak (Watts) (p<0.001), and oxygen consumption (O2 mL  min-1) (p=.0033) was significantly higher in the aerobically trained limb (EX) versus the control (CTL) limb. Capillary to perimeter fibre exchange index (CFPE) (p<0.05), a measure of microvascular perfusion, was significantly higher in the EX versus CTL limb following unilateral aerobic training. Resistance training resulted in increases in 1-repetition maximum of both squat (p<0.0001) and leg press (p<0.0001). A main effect of time was observed for limb fat free mass (p<0.0001) as determined via DEXA. Type-II fibre CSA of the EX limb was greater (p<0.05) versus CTL limb following resistance exercise training. Type-II fibre associated satellite cell content of the CTL limb was elevated (p<0.01) following resistance training. Results suggest that a period of unilateral aerobic training elevates the aerobic capacity and relative microvascular perfusion of the trained leg significantly in comparison to the non-aerobically conditioned limb. Subsequent resistance training, bilateral leg strength increased post resistance training while type II CSA increased in the aerobically pre-conditioned limb following resistance training. Collectively, these results suggest that a period of aerobic preconditioning may augment the muscle’s ability to respond to a hypertrophic stimulus. / Thesis / Master of Science (MSc) / Resistance exercise training is the most effective and accepted strategy for increasing skeletal muscle mass and strength. Yet, there is tremendous individual variability in the adaptive response to exercise and the source(s) contributing to this variability are largely unknown. Recently, evidence has emerged suggesting that capillaries may be a potential target for enhancing the adaptive response to chronic resistance exercise training. Research has only begun to characterize the extent to which microvascular perfusion (capillarization and blood flow to the muscle) plays a role in muscle health and resistance training outcomes. Currently, it is unknown if elevating microvascular perfusion is enough to facilitate greater accretion (hypertrophy) of muscle mass and strength following resistance training. Therefore, the current study hypothesized that increased microvascular perfusion induced by a pre-conditioning period of aerobic training, lasting 6-weeks, would be sufficient to enhance muscle accretion (hypertrophy) and elevate muscle stem cell content following resistance exercise training. To examine this, a cohort of young men and women performed 6 weeks of unilateral (single-leg) cycling following by 10 weeks of bilateral (both legs) resistance exercise training. Results demonstrated an increased oxidative capacity and capillary perfusion in the aerobically-trained limb following single-leg cycling, as expected. Consistent with our initial hypothesis, we observed superior muscle hypertrophy of type-II muscle fibres (increased fibre cross-sectional area), in the aerobically-conditioned limb following resistance training. The results suggest that muscle capillarization may be a determinant and facilitator of adaptation to resistance training and its outcomes.

Yes / Guest Editorial of Special Issue (featuring eight original papers, comprising 133 pages in total). Whilst satellite systems continue to be at the forefront of broadcast communication service provision, they have an increasingly important role to play in the provision of global Internet services. There has been a strong trend towards convergence of communication services in recent times, with the Internet providing the ideal platform on which to base such convergence. Even traditional circuit-switched applications (such as voice and video streaming) have been shown to work effectively over the Internet. Although the Internet is prevalent in the developed world, satellites are vital to extending this into more remote and sparsely populated regions of the world. It is therefore important that satellite technology is advanced to provide seamless interoperability with the Internet and adequate Quality of Service (QoS) support. The purpose of this special issue is to present research devoted to furthering satellite technology and networking to support the provision of both current and future applications.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / This paper discusses the design, configuration, and operation of a satellite station built for the Center for Space Telemetering and Telecommunications Laboratory in the Klipsch School of Electrical and Computer Engineering Engineering at New Mexico State University (NMSU). This satellite station consists of a computer-controlled antenna tracking system, 2m/70cm transceiver, satellite tracking software, and a demodulator. The satellite station receives satellite telemetry, allows for voice communications, and will be used in future classes. Currently this satellite station is receiving telemetry from an amateur radio satellite, UoSAT-OSCAR-11. Amateur radio satellites are referred to as Orbiting Satellites Carrying Amateur Radio (OSCAR) satellites.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / A telemetry system has been developed at the University of Arizona to serve as a baseline for future CubeSat designs. Two satellites are scheduled for launch in November of 2002. One features a beacon that operates autonomously of all but the power system and can independently deploy the antennas. The other will test the performance of new semiconductor devices in low earth orbit. Sensors will monitor voltages, currents (from which attitude and tumble rate can be derived), received signal strength and a distribution of temperatures. The CubeSat’s architecture, operating system, sensors, telemetry format and link budget are discussed.

Dans un contexte de convergence vers IP du monde des télécommunications, les systèmes de communication par satellite se doivent de suivre la tendance pour rester compétitifs et s'intégrer efficacement au monde Internet. Après avoir rappelé les enjeux d'une convergence dans les systèmes satellite et dressé un panorama des architectures de convergence envisageables, nous avons identifié les limites des systèmes actuels en termes de convergence vers IP. Notre choix se porte alors sur l'architecture IP/GSE pour la voie aller. Nous spécifions ensuite le protocole d'encapsulation GSE-Alt, inspiré de GSE mais adapté à la voie retour. Le déploiement de nouveaux services et l'évolution de services existants sont assurés et rendus plus aisés grâce à la couche IP. Les couches GSE et GSE-Alt optimisent le transport d'IP. Pour offrir un support de communication répondant à la diversité des exigences de qualité des services applicatif, nous définissons ensuite plusieurs mécanismes autorisant la mise en cohérence du traitement de la qualité de service (QoS) aux différents niveaux protocolaires dans les systèmes de communication par satellite. Enfin, pour permettre une interconnexion et une intégration du monde satellite au monde Internet, nous étudions les besoins en termes de déploiement du routage IP. Nous définissons alors une architecture permettant au satellite de réaliser de la commutation de niveau IP. Cette convergence vers un système « tout IP » du segment de communication par satellite est le fondement nécessaire à son insertion transparente au reste du monde des télécommunications. / The world of telecommunications converging towards IP, the telecommunication satellite systems have to follow the trend to stay competitive and to be integrated to the Internet world. We first remind the issues of convergence in satellite communications, then we list the different convergence architectures conceivable in satellite systems and describe the limits of current systems in term of IP convergence. Our choice is devoted to the IP/GSE architecture for the forward link. Then, we specify the GSE-Alt protocol, inspired from GSE but adapted to the return link. The deployment of new services and the evolution of existing services are possible and made easier thanks to the IP layer. Both layers GSE and GSE-Alt optimize the transport of the IP packets. In order to propose a communication support allowing various quality of service (QoS) needs, we specify several mechanisms allowing a great coherence of the quality of service treatments at the different protocol levels. Finally, to allow an interconnection and an integration of the satellite world to the Internet world, we study the requirements in term of IP routing deployment. Therefore, we specify an architecture allowing the satellite to make the switching at the IP level. This convergence of the satellite towards an "all IP" system is the base required to its transparent insertion to the rest of the telecommunication world.