102 research outputs found

    Visual experience is not necessary for efficient survey spatial cognition: Evidence from blindness

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    This study investigated whether the lack of visual experience affects the ability to create spatial infer-ential representations of the survey type. We compared the performance of persons with congenital blindness and that of blindfolded sighted persons on four survey representation-based tasks (Experiment 1). Results showed that persons with blindness performed better than blindfolded sighted controls. We repeated the same tests introducing a third group of persons with late blindness (Experiment 2). This last group performed better than blindfolded sighted participants, whereas differences between participants with late and congenital blindness were nonsignificant. The present findings are compatible with results of other studies, which found that when visual perception is lacking, skill in gathering environmental spatial information provided by nonvisual modalities may contribute to a proper spatial encoding. It is concluded that, although it cannot be asserted that total lack of visual experience incurs no cost, our findings are further evidence that visual experience is not a necessary condition for the development of spatial inferential complex representations. There is a general consensus on the crucial role of visual perception in guiding many of our daily movements in large- and small-scale environ

    A novel TRNSYS type of a coaxial borehole heat exchanger for both short and mid term simulations: B2G model

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    [EN] A dynamic model of a ground source heat pump system is a very useful tool in order to optimize its design and operation. In order to fairly predict the performance of such a system, the dynamic evolution of the fluid entering the heat pump and coming from the borehole heat exchanger (BHE) must be accurately reproduced not only in the long term but also in the short-mid term operating conditions, as it directly affects the coefficient of performance of the heat pump unit. In this context, the B2G model was developed to reproduce the short-term dynamic evolution of the fluid temperature inside the BHE. This work presents the new upgraded version of the B2G dynamic model for a coaxial BHE, which includes several new features to better reproduce not only the short-term but also the mid-term behaviour of the BHE. For that purpose, the model of the surrounding ground has been improved: vertical heat conduction in the grout and ground, heterogenous ground with different layers, and a higher number of ground nodes in the thermal network considered in the model were added, which are automatically located by means of polynomial correlations for any type of ground, geometry and operating conditions. This novel approach has been implemented in TRNSYS for accurately modelling the dynamic behaviour of a coaxial BHE with low computational cost (2.5¿s for a 24¿h simulation period in a modern computer). The model has been validated against experimental data from a dual source heat pump installation in Tribano (Padua, Italy) and has proven capable of accurately reproducing the short-mid term (up to five days) behaviour of the BHE, with a deviation lower than 0.12¿K.The present work has been supported by the European Community Horizon 2020 Program for European Research and Technological Development (2014-2020) inside the framework of the project 656889 –GEOTeCH (Geothermal Technology for Economic Cooling and Heating) and by the Generalitat Valenciana inside the program “Ayudas para la contratación de personal investigador en formación de carácter predoctoral (ACIF/2016/131)”.Cazorla-Marín, A.; Montagud- Montalvá, C.; Tinti, F.; Corberán, JM. (2019). A novel TRNSYS type of a coaxial borehole heat exchanger for both short and mid term simulations: B2G model. Applied Thermal Engineering. 164(114500):1-15. https://doi.org/10.1016/j.applthermaleng.2019.114500S11516411450

    Anticipatory action planning in blind and sighted individuals

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    Several studies on visually guided reach-to-grasp movements have documented that how objects are grasped differs depending on the actions one intends to perform subsequently. However, no previous study has examined whether this differential grasping may also occur without visual input. In this study, we used motion capture technology to investigate the influence of visual feedback and prior visual experience on the modulation of kinematics by intention in sighted (in both full-vision and no-vision conditions), early-blind and late-blind participants. Results provide evidence of modulation of kinematics by intention to a similar degree under both full-vision and no-vision conditions. Moreover, they demonstrate that prior visual experience has little impact on the tailoring of grasping movements to intention. This suggests that sequential action planning does not depend on visual input, and may instead be ascribed to the function of multisensory-motor cortical network that operates and develops not only in light, but also in darkness

    Novel aspects of iron homeostasis in pathogenic bloodstream form Trypanosoma brucei

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    Iron is an essential regulatory signal for virulence factors in many pathogens. Mammals and bloodstream form (BSF) Trypanosoma brucei obtain iron by receptor-mediated endocytosis of transferrin bound to receptors (TfR) but the mechanisms by which T. brucei subsequently handles iron remains enigmatic. Here, we analyse the transcriptome of T. brucei cultured in iron-rich and iron-poor conditions. We show that adaptation to iron-deprivation induces upregulation of TfR, a cohort of parasite-specific genes (ESAG3, PAGS), genes involved in glucose uptake and glycolysis (THT1 and hexokinase), endocytosis (Phosphatidic Acid Phosphatase, PAP2), and most notably a divergent RNA binding protein RBP5, indicative of a non-canonical mechanism for regulating intracellular iron levels. We show that cells depleted of TfR by RNA silencing import free iron as a compensatory survival strategy. The TfR and RBP5 iron response are reversible by genetic complementation, the response kinetics are similar, but the regulatory mechanisms are distinct. Increased TfR protein is due to increased mRNA. Increased RBP5 expression, however, occurs by a post-transcriptional feedback mechanism whereby RBP5 interacts with its own, and with PAP2 mRNAs. Further observations suggest that increased RBP5 expression in iron-deprived cells has a maximum threshold as ectopic overexpression above this threshold disrupts normal cell cycle progression resulting in an accumulation of anucleate cells and cells in G2/M phase. This phenotype is not observed with overexpression of RPB5 containing a point mutation (F61A) in its single RNA Recognition Motif. Our experiments shed new light on how T. brucei BSFs reorganise their transcriptome to deal with iron stress revealing the first iron responsive RNA binding protein that is co-regulated with TfR, is important for cell viability and iron homeostasis; two essential processes for successful proliferation
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