Web navigation for individuals with dyslexia: An exploratory study

In this paper, we present an exploratory study of the web navigation experiences of dyslexic users. Findings indicate that dyslexics exhibit distinctive web navigation behaviour and preferences. We believe that the outcomes of this study add to our understanding of the particular needs of this web user population and have implications for the design of effective navigation structures

Depositional behaviors of trace metals around hydrothermal vents in the Scotia Sea

Sediment deposition along the East Scotia Ridge (ESR) in the Southern Oceanis dominated by biogenic sediment due to its location within the diatom belt and is influenced by the Antarctic Circumpolar Current mainly flowing west to east. Hydrothermal vent systems occur along the ESR, are characterized by nine tectonic segments (E1-E9). Sediment cores in the vicinity of ridge segments E2 and E9 from the ESR were analyzed to gain a better understanding of potential vent fluids related to trace metal distributions in surrounding modern marine sediments. Solid phase multicore and porewater samples collected during the R/V Polarstern Expedition PS_119 were located on both east and west sides of the ESR. Samples were selected at different distances from the hydrothermal vents along two west to east transects crossing E2 and E9 to gain a broader understanding of how chemical signatures within the sediment column change due to their proximity to the vents. As hydrothermally emitted plumes move throughout the water column, they affect where trace metals are deposited onto underlying sediments. Each core was analyzed using an inductively coupled plasma mass spectrometry. Analysis across the transects show a steady increase in trace metal concentrations on the eastern side of the ESR compared to samples from the western side indicating a currents-induced eastward movement of hydrothermal plumes from the ESR. In addition, sediments near E9 exhibited much higher trace metal enrichments compared to segment E2 signifying a more trace metal-rich magmatic substrate source and different water-rock interactions increased metal concentrations within plumes and their deposits. Understanding the effects of hydrothermal activity on marine sediment is crucial when studying the productivity of an area using trace metal proxies because trace metal input from hydrothermal vents can overprint chemical signatures left from phytoplankton in marine sediments. Silver seems to be relatively unaffected by hydrothermal activity as it has similar concentrations within the cores analyzed, while cobalt and copper concentrations fluctuated with different distances from the hydrothermal vents. Thus, copper and cobalt have the potential to indicate changes in deep ocean currents, while silver may be a good productivity proxy in the Southern Ocean

Ecotoxicity of basil (Ocimum Basilicum) extract in aquaculture feeds: Is it really eco-safe for the aquatic environment?

Plant extract and essential oils are gaining application in aquaculture, but data about their environmental impact are limited and their potential effects on aquatic organisms are largely unknown. For this study, ecotoxicity tests were performed under standardized conditions on fish feed supplemented with 3 % w/w of a basil supercritical extract (F1-BEO; substance A), F1-BEO extract (substance B), and fish feed without F1-BEO extract (substance C) on three model species of different trophic levels (bacteria, primary producer, primary consumer) considered representative for freshwater (Aliivibrio fischeri, Raphidocelis subcapitata, Daphnia magna) and marine (A. fischeri, Phaeodactylum tricornutum, Paracentrotus lividus) ecosystems. Ecotoxicological response was largely comparable within the same trophic level (whichever the ecosystem). EC50 was not calculable in the concentration range here tested (3.9–500 mg/L) for freshwater and marine microalgae, suggesting that none of the substances were toxic for primary producers. Reduction of A. fischeri bioluminescence at the tested concentration (0.5–10 mg/L) was observed only for substance A (EC50 9.53 mg/L and 9 mg/L for freshwater and marine ecosystems, respectively). Notably, in P. lividus embryotoxicity was higher for substances A (EC50 1.80 mg/L) and C (EC50 4.6 mg/L) than for substance B (EC50 7.10 mg/L), suggesting a toxic effect due to feed dissolution. In contrast, substance B was more toxic (EC50 0.34 mg/L) in D. magna than substances A (EC50 3.98 mg/L) and C (EC50 5.50 mg/L). Based on the Globally Harmonized System of Classification and Labelling of Chemicals, all substances were categorized Acute 2, except for substance A which was categorized Acute 1 for D. magna. Overall, the substances were found to be potentially toxic for an aquatic ecosystem, especially for primary consumer. Further study of plant extract and essential oils is needed to better understand their effects and fate on the aquatic environment

Marine Biodegradability and Ecotoxicity of MWool((R)) Recycled Wool Fibers: A Circular-Economy-Based Material

Pollution of the marine environment by microfibers is considered a problem for ecosystem conservation. The amount of microplastic, localization of sources, and associated ecotoxicity are well known in the literature. Wastewater from washing machines is the main source of microplastic fibers in the aquatic environment, and fabrics made from recycled plastic are widely reused. The circular economy also promotes recycling of dyed natural wool materials as a basis for making new clothing, but in this case, less research has been conducted on the behaviour and effects of recycled wool microfibers in marine ecosystems. MWool((R)) (MW) and MWool((R)) carded (MWc) products made from recycled wool fibers were tested in mesocosms to investigate the biodegradation of wool fibers over a 260-day period and the effects of this process on marine ecosystems in terms of microfiber inputs and the ecotoxicological effects of by-products and chemicals released during degradation. The early degradation process was associated with the loss of artificial pigments from the dyed wool, particularly pink and red, which occurred within 30-90 days of exposure. Mean release of microparticles into contact water is significantly different from control (T0, p < 0.01) at 90 days MWc (36.6 mg/L) and 180 days MW (42.9 mg/L). The biodegradation process is accompanied by swelling of wool fibers, which is associated with a significant increase in mean wool thickness (p < 0.05, 18.8 +/-.1 mu m at T0 vs. 24.0 +/- 7.1 mu m). In both cases, the contact water was not associated with signs of ecotoxicity for the marine species tested in this study (Phaeodactylum tricornutum, Brachionus plicatilis, and Paracentrotus lividus)

Mussel watch program for microplastics in the Mediterranean sea: Identification of biomarkers of exposure using Mytilus galloprovincialis

Microplastics (MPs) are ubiquitous pollutants that have also been detected in the aquatic ecosystems at high concentrations. The use of shellfish as bioindicators is widespread for assessing and monitoring the environmental quality in both freshwater and marine environments. On this path, biomarkers represent an effective tool in monitoring programs. This minireview would broaden the existing knowledge on biomarkers of MPs in the Mediterranean mussel Mytilus galloprovincialis. This species was selected as it is widely distributed across the Mediterranean Sea and used as a bioindicator to monitor the presence of MPs in the marine environment. The literature search returned only 11 studies, mainly related to oxidative stress biomarkers. Although certain biomarkers were explored to estimate the effects of MPs on M. galloprovincialis, a battery of standardized and validated biomarkers as well as the inclusion of new ones are needed in future studies to obtain more comparable and robust findings across the Mediterranean Sea

Increasing the Neutralino Relic Abundance with Slepton Coannihilations: Consequences for Indirect Dark Matter Detection

We point out that if the lightest supersymmetric particle (LSP) is a Higgsino- or Wino-like neutralino, the net effect of coannihilations with sleptons is to increase the relic abundance, rather than producing the usual suppression, which takes place if the LSP is Bino-like. The reason for the enhancement lies in the effective thermally averaged cross section at freeze-out: sleptons annihilate (and co-annihilate) less efficiently than the neutralino(s)-chargino system, therefore slepton coannihilations effectively act as parasite degrees of freedom at freeze-out. Henceforth, the thermal relic abundance of LSP's corresponds to the cold Dark Matter abundance for smaller values of the LSP mass, and larger values of the neutralino pair annihilation cross section. In turn, at a given thermal neutralino relic abundance, this implies larger indirect detection rates, as a result of an increase in the fluxes of antimatter, gamma rays and neutrinos from the Sun orginating from neutralino pair annihilations.Comment: 16 pages, 6 figures, references added, typos corrected, matches with the published versio

Dark Matter in split extended supersymmetry

We consider the split extended (N=2) supersymmetry scenario recently proposed by Antoniadis et al. [hep-ph/0507192] as a realistic low energy framework arising from intersecting brane models. While all scalar superpartners and charged gauginos are naturally at a heavy scale, the model low energy spectrum contains a Higgsino-like chargino and a neutralino sector made out of two Higgsino and two Bino states. We show that the lightest neutralino is a viable dark matter candidate, finding regions in the parameter space where its thermal relic abundance matches the latest determination of the density of matter in the Universe by WMAP. We also discuss dark matter detection strategies within this model: we point out that current data on cosmic-ray antimatter already place significant constraints on the model, while direct detection is the most promising technique for the future. Analogies and differences with respect to the standard split SUSY scenario based on the MSSM are illustrated.Comment: 14 pages, references added, typos corrected, matches with the published versio

Cyclic Symmetry Finite Element Forced Response Analysis of a Distortion-Tolerant Fan with Boundary Layer Ingestion

Accurate prediction of the blade vibration stress is required to determine overall durability of fan blade design under Boundary Layer Ingestion (BLI) distorted flow environments. Traditional single blade modeling technique is incapable of representing accurate modeling for the entire rotor blade system subject to complex dynamic loading behaviors and vibrations in distorted flow conditions. A particular objective of our work was to develop a high-fidelity full-rotor aeromechanics analysis capability for a system subjected to a distorted inlet flow by applying cyclic symmetry finite element modeling methodology. This reduction modeling method allows computationally very efficient analysis using a small periodic section of the full rotor blade system. Experimental testing by the use of the 8-foot by 6-foot Supersonic Wind Tunnel Test facility at NASA Glenn Research Center was also carried out for the system designated as the Boundary Layer Ingesting Inlet/Distortion-Tolerant Fan (BLI2DTF) technology development. The results obtained from the present numerical modeling technique were evaluated with those of the wind tunnel experimental test, toward establishing a computationally efficient aeromechanics analysis modeling tool facilitating for analyses of the full rotor blade systems subjected to a distorted inlet flow conditions. Fairly good correlations were achieved hence our computational modeling techniques were fully demonstrated. The analysis result showed that the safety margin requirement set in the BLI2DTF fan blade design provided a sufficient margin with respect to the operating speed range

Dirac gaugino as leptophilic dark matter

We investigate the leptophilic properties of Dirac gauginos in an R--symmetric N=2 supersymmetric model with extended gauge and Higgs sectors. The annihilation of Dirac gauginos to leptons requires no chirality flip in the final states so that it is not suppressed as in the Majorana case. This implies that it can be sizable enough to explain the positron excess observed by the PAMELA experiment with moderate or no boost factors. When squark masses are heavy, the annihilation of Dirac gauginos to hadrons is controlled by their Higgsino fraction and is driven by the $hZ$ and $W^+W^-$ final states. Moreover, at variance with the Majorana case, Dirac gauginos with a non-vanishing higgsino fraction can also have a vector coupling with the $Z$ gauge boson leading to a sizable spin--independent scattering cross section off nuclei. Saturating the current antiproton limit, we show that Dirac gauginos can leave a signal in direct detection experiments at the level of the sensitivity of dark matter searches at present and in the near future.Comment: 24 pages, 10 figures, typos corrected, final version published on JCA

Assessment of Technologies for Noncryogenic Hybrid Electric Propulsion

The Subsonic Fixed Wing Project of NASA's Fundamental Aeronautics Program is researching aircraft propulsion technologies that will lower noise, emissions, and fuel burn. One promising technology is noncryogenic electric propulsion, which could be either hybrid electric propulsion or turboelectric propulsion. Reducing dependence on the turbine engine would certainly reduce emissions. However, the weight of the electricmotor- related components that would have to be added would adversely impact the benefits of the smaller turbine engine. Therefore, research needs to be done to improve component efficiencies and reduce component weights. This study projects technology improvements expected in the next 15 and 30 years, including motor-related technologies, power electronics, and energy-storage-related technologies. Motor efficiency and power density could be increased through the use of better conductors, insulators, magnets, bearings, structural materials, and thermal management. Energy storage could be accomplished through batteries, flywheels, or supercapacitors, all of which expect significant energy density growth over the next few decades. A first-order approximation of the cumulative effect of each technology improvement shows that motor power density could be improved from 3 hp/lb, the state of the art, to 8 hp/lb in 15 years and 16 hp/lb in 30 years