The Effect of Target Position and Tactual Recognition Field Size on Touch Bias and Accuracy

Past studies have shown that touchscreen display angles other than those that perpendicularly bisect the operator\u27s line of sight cause the operator to touch slightly below the target. The amount of touch bias created from this misjudgment fluctuates according to the target\u27s position on the screen. Additionally, the percentage of touches that activate a specific target varies according to the size of the tactual recognition field. Out of three square tactual recognition field sizes, this study sought to match these fields with the amount of touch bias occurring in each location (i.e., small amount of touch bias requires only a small field). The results showed that although bias differed according to location, the tactual recognition fields did not vary enough in size, nor were they large enough to find a significant difference between them in the number of touches captured according to the location of the target

Can differences in phosphorus uptake kinetics explain the distribution of cattail and sawgrass in the Florida Everglades?

<p>Abstract</p> <p>Background</p> <p>Cattail (<it>Typha domingensis</it>) has been spreading in phosphorus (P) enriched areas of the oligotrophic Florida Everglades at the expense of sawgrass (<it>Cladium mariscus </it>spp. <it>jamaicense</it>). Abundant evidence in the literature explains how the opportunistic features of <it>Typha </it>might lead to a complete dominance in P-enriched areas. Less clear is how <it>Typha </it>can grow and acquire P at extremely low P levels, which prevail in the unimpacted areas of the Everglades.</p> <p>Results</p> <p>Apparent P uptake kinetics were measured for intact plants of <it>Cladium </it>and <it>Typha </it>acclimated to low and high P at two levels of oxygen in hydroponic culture. The saturated rate of P uptake was higher in <it>Typha </it>than in <it>Cladium </it>and higher in low-P acclimated plants than in high-P acclimated plants. The affinity for P uptake was two-fold higher in <it>Typha </it>than in <it>Cladium</it>, and two- to three-fold higher for low-P acclimated plants compared to high-P acclimated plants. As <it>Cladium </it>had a greater proportion of its biomass allocated to roots, the overall uptake capacity of the two species at high P did not differ. At low P availability, <it>Typha </it>increased biomass allocation to roots more than <it>Cladium</it>. Both species also adjusted their P uptake kinetics, but <it>Typha </it>more so than <it>Cladium</it>. The adjustment of the P uptake system and increased biomass allocation to roots resulted in a five-fold higher uptake per plant for <it>Cladium </it>and a ten-fold higher uptake for <it>Typha</it>.</p> <p>Conclusions</p> <p>Both <it>Cladium </it>and <it>Typha </it>adjust P uptake kinetics in relation to plant demand when P availability is high. When P concentrations are low, however, <it>Typha </it>adjusts P uptake kinetics and also increases allocation to roots more so than <it>Cladium</it>, thereby improving both efficiency and capacity of P uptake. <it>Cladium </it>has less need to adjust P uptake kinetics because it is already efficient at acquiring P from peat soils (e.g., through secretion of phosphatases, symbiosis with arbuscular mycorrhizal fungi, nutrient conservation growth traits). Thus, although <it>Cladium </it>and <it>Typha </it>have qualitatively similar strategies to improve P-uptake efficiency and capacity under low P-conditions, <it>Typha </it>shows a quantitatively greater response, possibly due to a lesser expression of these mechanisms than <it>Cladium</it>. This difference between the two species helps to explain why an opportunistic species such as <it>Typha </it>is able to grow side by side with <it>Cladium </it>in the P-deficient Everglades.</p

Interactive effects of elevated temperature and CO2 on two phylogeographically distinct clones of common reed (Phragmites australis)

The aboveground growth, physiological and biochemical parameters of two clones of the cosmopolitan wetland grass Phragmites australis, grown at four treatment combinations of temperature and O2, were investigated to elucidate whether their climate response differed due to inherent differences in their ecological adaptation. The two phylogeographically distinct P. australis clones (DK clone, European genetic background; ALG clone, Mediterranean genetic background) were grown for 151 days in phytotrons at 19/12 8C (day/night temperature) and 390 ppm CO2, and at elevated temperature (+5 8C) and CO2 (700 ppm) with treatment factors alone or in combination. The ALG clone had 2–4 times higher aboveground biomass, higher light-saturated rates of photosynthesis (Pmax), maximum electron transport rates (ETRmax) and Rubisco activity, and higher photosynthetic nitrogen-use efficiency than the DK clone. The DK clone, however, produced more shoots, leaves and sideshoots, and had 9–51 % higher specific leaf area and 15–39 % higher leaf nitrogen concentration than the ALG clone. Although elevated atmospheric CO2 alone barely affected the aboveground growth of the two P. australis clones, simultaneously elevated temperature and CO2 stimulated growth and aboveground biomass. Overall, elevated CO2 stimulated photosynthesis, but the clones responded differently to a concomitant increase in CO2 and temperature, depending on the phylogeographic background of the plant. The DK clone showed overall stronger responses, and can be considered the more plastic of the two clones with respect to CO2 and temperature. Thus, the DK clone may be better adapted to climate change than the ALG clone, at least in the short term

Genetic and environmental influence on thyroid gland volume and thickness of thyroid isthmus: a twin study.

Objectives Decreased thyroid volume has been related to increased prevalence of thyroid cancer.Subjects and methods One hundred and fourteen Hungarian adult twin pairs (69 monozygotic, 45 dizygotic) with or without known thyroid disorders underwent thyroid ultrasound. Thickness of the thyroid isthmus was measured at the thickest portion of the gland in the midline using electronic calipers at the time of scanning. Volume of the thyroid lobe was computed according to the following formula: thyroid height*width*depth*correction factor (0.63).Results Age-, sex-, body mass index- and smoking-adjusted heritability of the thickness of thyroid isthmus was 50% (95% confidence interval [CI], 35 to 66%). Neither left nor right thyroid volume showed additive genetic effects, but shared environments were 68% (95% CI, 48 to 80%) and 79% (95% CI, 72 to 87%), respectively. Magnitudes of monozygotic and dizygotic co-twin correlations were not substantially impacted by the correction of covariates of body mass index and smoking. Unshared environmental effects showed a moderate influence on dependent parameters (24-50%).Conclusions Our analysis support that familial factors are important for thyroid measures in a general twin population. A larger sample size is needed to show whether this is because of common environmental (e.g. intrauterine effects, regional nutrition habits, iodine supply) or genetic effects

Relationship between Polycyclic Aromatic Hydrocarbons in Sediments and Invertebrates of Natural and Artificial Stormwater Retention Ponds

Sediments and invertebrates were sampled from 9 stormwater retention ponds (SWRPs) and 11 natural, shallow lakes in Denmark. Samples were analyzed for 13 polycyclic aromatic hydrocarbons (PAHs). The SWRPs received urban and highway runoff from various types of drainage areas and the lakes were located in areas of various land uses. Comparing PAHs in the sediments of the SWRPs and the lakes, it was found that levels of total PAH were similar in the two aquatic systems, with median values of 0.94 and 0.63 mg&middot;(kg&middot;DM)&minus;1 in sediments of SWRPs and lakes, respectively. However, the SWRP sediments tended to have higher concentrations of high-molecular-weight PAHs than the lakes. A similar pattern was seen for PAHs accumulated in invertebrates where the median of total PAH was 2.8 and 2.1 mg&middot;(kg&middot;DM)&minus;1 for SWRPs and lakes, respectively. Principal component analysis on the PAH distribution in the sediments and invertebrates showed that ponds receiving highway runoff clustered with lakes in forests and farmland. The same was the case for some of the ponds receiving runoff from residential areas. Overall, results showed that sediment PAH levels in all SWRPs receiving runoff from highways were similar to the levels found in some of the investigated natural, shallow lakes, as were the sediment PAH levels from some of the residential SWRPs. Furthermore, there was no systematic trend that one type of water body exceeded environmental quality standards (EQS) values more often than others. Together this indicates that at least some SWRPs can sustain an invertebrate ecosystem without the organisms experiencing higher bioaccumulation of PAHs then what is the case in shallow lakes of the same region

Experimental Validation of a Filament Transport Model in Turbulent Magnetized Plasmas

In a wide variety of natural and laboratory magnetized plasmas, filaments appear as a result of interchange instability. These convective structures substantially enhance transport in the direction perpendicular to the magnetic field. According to filament models, their propagation may follow different regimes depending on the parallel closure of charge conservation. This is of paramount importance in magnetic fusion plasmas, as high collisionality in the scrape-off layer may trigger a regime transition leading to strongly enhanced perpendicular particle fluxes. This work reports for the first time on an experimental verification of this process, linking enhanced transport with a regime transition as predicted by models. Based on these results, a novel scaling for global perpendicular particle transport in reactor relevant tokamaks such as ASDEURATOM 63305

Real-time identification of the current density profile in the JET Tokamak: method and validation

International audienceThe real-time reconstruction of the plasma magnetic equilibrium in a Tokamak is a key point to access high performance regimes. Indeed, the shape of the plasma current density profile is a direct output of the reconstruction and has a leading effect for reaching a steady-state high performance regime of operation. In this paper we present the methodology followed to identify numerically the plasma current density in a Tokamak and its equilibrium. In order to meet the real-time requirements a C++ software has been developed using the combination of a finite element method, a nonlinear fixed point algorithm associated to a least square optimization procedure. The experimental measurements that enable the identification are the magnetics on the vacuum vessel, the interferometric and polarimetric measurements on several chords and the motional Stark effect. Details are given about the validation of the reconstruction on the JET tokamak, either by comparison with 'off-line' equilibrium codes or real time software computing global quantities