Are Split Tablet Keyboards Better? A Study of Soft Keyboard Layout and Hand Posture

acceptedVersio

Reference deployment models for eliminating user concerns on cloud security

Cloud computing has become a hot topic both in research and in industry, and when making decisions on deploying/adopting cloud computing related solutions, security has always been a major concern. This article summarizes security related issues in cloud computing and proposes five service deployment models to address these issues. The proposed models provide different security related features to address different requirements and scenarios and can serve as reference models for deployment

The Effect of Diel Temperature and Light Cycles on the Growth of Nannochloropsis oculata in a Photobioreactor Matrix

A matrix of photobioreactors integrated with metabolic sensors was used to examine the combined impact of light and temperature variations on the growth and physiology of the biofuel candidate microalgal species Nannochloropsis oculata. The experiments were performed with algal cultures maintained at a constant 20u C versus a 15°C to 25°C diel temperature cycle, where light intensity also followed a diel cycle with a maximum irradiance of 1920 μmol photons m-2 s-1. No differences in algal growth (Chlorophyll a) were found between the two environmental regimes; however, the metabolic processes responded differently throughout the day to the change in environmental conditions. The variable temperature treatment resulted in greater damage to photosystem II due to the combined effect of strong light and high temperature. Cellular functions responded differently to conditions before midday as opposed to the afternoon, leading to strong hysteresis in dissolved oxygen concentration, quantum yield of photosystem II and net photosynthesis. Overnight metabolism performed differently, probably as a result of the temperature impact on respiration. Our photobioreactor matrix has produced novel insights into the physiological response of Nannochloropsis oculata to simulated environmental conditions. This information can be used to predict the effectiveness of deploying Nannochloropsis oculata in similar field conditions for commercial biofuel production. © 2014 Tamburic et al

Continuous cultivation of photosynthetic microorganisms: approaches, applications and future trends

The possibility of using photosynthetic microorganisms, such as cyanobacteria and microalgae, for converting light and carbon dioxide into valuable biochemical products has raised the need for new cost-efficient processes ensuring a constant product quality. Food, feed, biofuels, cosmetics and pharmaceutics are among the sectors that can profit from the application of photosynthetic microorganisms. Biomass growth in a photobioreactor is a complex process influenced by multiple parameters, such as photosynthetic light capture and attenuation, nutrient uptake, photobioreactor hydrodynamics and gas-liquid mass transfer. In order to optimize productivity while keeping a standard product quality, a permanent control of the main cultivation parameters is necessary, where the continuous cultivation has shown to be the best option. However it is of utmost importance to recognize the singularity of continuous cultivation of cyanobacteria and microalgae due to their dependence on light availability and intensity. In this sense, this review provides comprehensive information on recent breakthroughs and possible future trends regarding technological and process improvements in continuous cultivation systems of microalgae and cyanobacteria, that will directly affect cost-effectiveness and product quality standardization. An overview of the various applications, techniques and equipment (with special emphasis on photobioreactors) in continuous cultivation of microalgae and cyanobacteria are presented. Additionally, mathematical modelling, feasibility, economics as well as the applicability of continuous cultivation into large-scale operation, are discussed.This research work was supported by the grant SFRH/BPD/98694/2013 (Bruno Fernandes) from Fundacao para a Ciencia e a Tecnologia (Portugal). The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013. The authors also thank the Project "BioInd Biotechnology and Bioengineering for improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028" Co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDE

A Recent Impact Origin of Saturn’s Rings and Mid-sized Moons

We simulate the collision of precursor icy moons analogous to Dione and Rhea as a possible origin for Saturn's remarkably young rings. Such an event could have been triggered a few hundred million years ago by resonant instabilities in a previous satellite system. Using high-resolution smoothed particle hydrodynamics simulations, we find that this kind of impact can produce a wide distribution of massive objects and scatter material throughout the system. This includes the direct placement of pure-ice ejecta onto orbits that enter Saturn's Roche limit, which could form or rejuvenate rings. In addition, fragments and debris of rock and ice totaling more than the mass of Enceladus can be placed onto highly eccentric orbits that would intersect with any precursor moons orbiting in the vicinity of Mimas, Enceladus, or Tethys. This could prompt further disruption and facilitate a collisional cascade to distribute more debris for potential ring formation, the re-formation of the present-day moons, and evolution into an eventual cratering population of planetocentric impactors

Origin of Mars’s moons by disruptive partial capture of an asteroid

The origin of Mars’s small moons, Phobos and Deimos, remains unknown. They are typically thought either to be captured asteroids or to have accreted from a debris disk produced by a giant impact. Here, we present an alternative scenario wherein fragments of a tidally disrupted asteroid are captured and evolve into a collisional proto-satellite disk. We simulate the initial disruption and the fragments’ subsequent orbital evolution. We find that tens of percent of an unbound asteroid’s mass can be captured and survive beyond collisional timescales, across a broad range of periapsis distances, speeds, masses, spins, and orientations in the Sun–Mars frame. Furthermore, more than one percent of the asteroid’s mass could evolve to circularise in the moons’ accretion region. This implies a lower mass requirement for the parent body than that for a giant impact, which could increase the likelihood of this route to forming a proto-satellite disk that, unlike direct capture, could also naturally explain the moons’ orbits. These three formation scenarios each imply different properties of Mars’s moons to be tested by upcoming spacecraft missions

No dilute core produced in simulations of giant impacts on to Jupiter

A giant impact has been proposed as a possible formation mechanism for Jupiter’s dilute core – the planet’s inferred internal structure in which the transition between its core of heavy elements and its predominantly hydrogen–helium envelope is gradual rather than a discrete interface. A past simulation suggested that a head-on impact of a planet into an almost fully formed, differentiated Jupiter could lead to a post-impact planet with a smooth compositional gradient and a central heavy-element fraction as low as . Here, we present simulations of giant impacts on to Jupiter using improved numerical methods to reassess the feasibility of this scenario. We use the REMIX smoothed particle hydrodynamics (SPH) formulation, which has been newly developed to improve the treatment of mixing in SPH simulations. We note that, as in previous works, chemical mixing is not included in these models and that incorporating such processes at sub-particle scales could improve numerical convergence. We perform giant impact simulations with varying speeds, angles, pre-impact planet structures, and equations of state. In all of our simulations, heavy elements re-settle over short time-scales to form a differentiated core, even in cases where the core is initially disrupted into a transiently mixed state. A dilute core is not produced in any of our simulations. These results, combined with recent observations that indicate Saturn also has a dilute core, suggest that such structures are produced as part of the extended formation and evolution of giant planets, rather than through extreme, low-likelihood giant impacts

A bibliometric study of human–computer interaction research activity in the Nordic-Baltic Eight countries

Human–computer interaction (HCI) has become an important area for designers and developers worldwide, and research activities set in national cultural contexts addressing local challenges are often needed in industry and academia. This study explored HCI research in the Nordic-Baltic countries using bibliometric methods. The results show that the activity varies greatly across the region with activities dominated by Finland, Sweden, and Denmark, even when adjusting for differences in population size and GDP. Research output variations were larger for the top-tier conferences compared to entry-tier conferences and journals. Locally hosted conferences were associated with local increases in research activity. HCI research longevity appears to be an indicator of research maturity and quantity. HCI researchers typically collaborated either with colleagues within the same institution or with researchers from countries outside the Nordic-Baltic region such as US and the UK. There was less collaboration between national and Nordic-Baltic partners. Collaboration appeared especially prevalent for top-tier conference papers. Top-tier conference papers were also more frequently cited than regional-tier and entry-tier conferences, yet journal articles were cited the most. One implication of this study is that the HCI research activity gaps across the Nordic-Baltic countries should be narrowed by increasing the activity in countries with low research outputs. To achieve this, first-time authors could receive guidance through collaborations with experienced authors in the same institution or other labs around the world. More conferences could also be hosted locally. Furthermore, journals may be more effective than conferences if the goal is to accumulate citations.publishedVersio

REMIX SPH – improving mixing in smoothed particle hydrodynamics simulations using a generalised, material-independent approach

We present REMIX, a smoothed particle hydrodynamics (SPH) scheme designed to alleviate effects that typically suppress mixing and instability growth at density discontinuities in SPH simulations. We approach this problem by directly targeting sources of kernel smoothing error and discretisation error, resulting in a generalised, material-independent formulation that improves the treatment both of discontinuities within a single material, for example in an ideal gas, and of interfaces between dissimilar materials. This approach also leads to improvements in capturing wider hydrodynamic behaviour unrelated to mixing. We demonstrate marked improvements in three-dimensional test scenarios, focusing on cases with particles of equal mass across the simulation. This choice is particularly relevant for use cases in astrophysics and engineering – specifically those in which particles are free to evolve over a large range of density scales – where bespoke choices of unequal particle masses in the initial conditions cannot easily be used to address emergent and evolving density discontinuities. We achieve these improvements while maintaining sharp discontinuities; without introducing additional equation of state dependence in, for example, particle volume elements; and without contrived or targeted corrections. Our methods build upon a fully compressible and thermodynamically consistent core-SPH construction, retaining Galilean invariance as well as conservation of mass, momentum, and energy. REMIX is integrated in the open-source, state-of-the-art SWIFT code and is designed with computational efficiency also in mind, meaning that its improved hydrodynamic treatment can be used for high-resolution simulations without prohibitive cost to run-speed