2444402 research outputs found
Sort by
Paradiesgemeinschaften : raumzeitliche und soziale Aspekte von Paradiesdarstellungen in der Literatur des Mittelalters und der Frühen Neuzeit /
No full textThe cost of regulating effort : reward and difficulty cues with longer prediction horizons have a stronger impact on performance
No full textMany theories on cognitive effort start from the assumption that cognitive effort can be expended at will, and flexibly up- or down-regulated depending on expected task demand and rewards. However, while effort regulation has been investigated across a wide range of incentive conditions, few investigated the cost of effort regulation itself. Across four experiments, we studied the effects of reward expectancy and task difficulty on effort expenditure in a perceptual decision-making task (random-dot-motion) and a cognitive control task (colour-naming Stroop), and within each task comparted cues between short (cueing the next trial) and long (cueing the next six trials) prediction horizons. We found that participants used the cue information only when it was valid for multiple trials in a row. In the random-dot-motion task, a high reward expectancy resulted in better accuracy, especially in easy trials, but only with long prediction horizon. Similarly, in the Stroop task, the reward facilitation of reaction time was only observed after reward cues with a long prediction horizon. Together, our results indicate that people experience a cost to effort regulation, and that lower adjustment frequency can compensate for this cost.Many theories on cognitive effort start from the assumption that cognitive effort can be expended at will, and flexibly up- or down-regulated depending on expected task demand and rewards. However, while effort regulation has been investigated across a wide range of incentive conditions, few investigated the cost of effort regulation itself. Across four experiments, we studied the effects of reward expectancy and task difficulty on effort expenditure in a perceptual decision-making task (random-dot-motion) and a cognitive control task (colour-naming Stroop), and within each task comparted cues between short (cueing the next trial) and long (cueing the next six trials) prediction horizons. We found that participants used the cue information only when it was valid for multiple trials in a row. In the random-dot-motion task, a high reward expectancy resulted in better accuracy, especially in easy trials, but only with long prediction horizon. Similarly, in the Stroop task, the reward facilitation of reaction time was only observed after reward cues with a long prediction horizon. Together, our results indicate that people experience a cost to effort regulation, and that lower adjustment frequency can compensate for this cost.A
A detailed plant model in CFD that resolves the microclimate around individual leaves
No full textPlant factories require effective ventilation to promote proper plant growth. Computational Fluid Dynamics (CFD) is commonly used to evaluate ventilation strategies in these environments. Traditionally, porous models have been employed to study ventilation in plant factories. However, this study proposes an alternative approach using actual plant geometry, consisting of leaves and stems, which reduces the need for fitting parameters typically used in porous models. The study focuses on basil, with plant geometry based on experimental data to ensure accurate representation. This new plant model accounts for the heat and mass balance of each leaf, assigning individual temperature and humidity values. Radiative heat exchange was also included in the plant model by using the solar ray tracing algorithm to solve for shortwave radiation and the surface to surface radiation model for longwave thermal radiation. Validation was conducted in a small plant factory-like environment (1500 mm × 420 mm x 800 mm) under night-like conditions without shortwave radiation and day-like conditions, with shortwave radiation. Key variables such as transpiration rate and leaf temperature were measured and simulated. The coefficient of variation between measured and simulated transpiration rates ranged from 10 % to 15 % for night-time and 15 % for day-time. Root mean square deviations for leaf temperature were 0.4–0.6 °C at night and 0.5–1.6 °C during the day. A different test case, with air supplied from the bottom instead of the side, demonstrated the new model's capabilities. Overall, the new plant model visualises airflow around and through the canopy, and shows promise for improving ventilation strategies in vertical farming systems.Plant factories require effective ventilation to promote proper plant growth. Computational Fluid Dynamics (CFD) is commonly used to evaluate ventilation strategies in these environments. Traditionally, porous models have been employed to study ventilation in plant factories. However, this study proposes an alternative approach using actual plant geometry, consisting of leaves and stems, which reduces the need for fitting parameters typically used in porous models. The study focuses on basil, with plant geometry based on experimental data to ensure accurate representation. This new plant model accounts for the heat and mass balance of each leaf, assigning individual temperature and humidity values. Radiative heat exchange was also included in the plant model by using the solar ray tracing algorithm to solve for shortwave radiation and the surface to surface radiation model for longwave thermal radiation. Validation was conducted in a small plant factory-like environment (1500 mm × 420 mm x 800 mm) under night-like conditions without shortwave radiation and day-like conditions, with shortwave radiation. Key variables such as transpiration rate and leaf temperature were measured and simulated. The coefficient of variation between measured and simulated transpiration rates ranged from 10 % to 15 % for night-time and 15 % for day-time. Root mean square deviations for leaf temperature were 0.4–0.6 °C at night and 0.5–1.6 °C during the day. A different test case, with air supplied from the bottom instead of the side, demonstrated the new model's capabilities. Overall, the new plant model visualises airflow around and through the canopy, and shows promise for improving ventilation strategies in vertical farming systems.A
Sustainable functional electrospun polyamide 11/halloysite derivatives nanofibrous membranes for water treatment applications
No full textMembrane-based approaches are an exciting alternative for the filtration and remediation of polluted water and for the removal of different traditional and emerging contaminants. This work focuses on the design and development of sustainable bio-polymeric blends based on polyamide 11 (PA11) employed to produce different Electrospun Nanofiber Membranes (ENMs) through the electrospinning process. Moreover, different eco-friendly functional nanofillers based on hybrid halloysite (HNT) derivatives were employed as dopant agents of the starting polymeric blends in a ratio of 1, 2 and 5 wt% of PA11 to achieve better mechanical and thermal features as well as retention performances of specific wastewater organic contaminants. Chemical-physical and structural-morphological characterizations, concerning all the nanofillers and the obtained sustainable membranes, are reported as well as the removal and separation studies of two selected anionic and cationic dyes, methyl orange (MO) and methylene blue (MB) in a dead-end filtration apparatus. The newly developed composite ENMs, compared to pristine PA11 ones, show good tensile mechanical and thermal properties, and increased MO and MB removal rates, modulated by the different HNT derivatives employed. Dead-end filtration experiments were performed using 1 and 3 layers of each type of ENM revealing, for 1-layer PA11 ENMs containing HNT modified with octadecylphosphonic acid and (3-aminopropyl)triethoxysilane (PA11@C18_HNT_NH2) and dimethyloctadecyl[3(trimethoxysilyl)propyl]ammoniumchloride (PA11@HNT_N + C18), a selectivity towards the removal of the cationic dye MB with a separation efficiency of 69.8 and 73.3 % respectively. Hence, 3-layer PA11 ENMs doped with HNT functionalized with (3-aminopropyl)triethoxysilane (PA11@HNT_NH2) display the highest retention rate for MO and MB respectively of 100 and 89.8 %.Membrane-based approaches are an exciting alternative for the filtration and remediation of polluted water and for the removal of different traditional and emerging contaminants. This work focuses on the design and development of sustainable bio-polymeric blends based on polyamide 11 (PA11) employed to produce different Electrospun Nanofiber Membranes (ENMs) through the electrospinning process. Moreover, different eco-friendly functional nanofillers based on hybrid halloysite (HNT) derivatives were employed as dopant agents of the starting polymeric blends in a ratio of 1, 2 and 5 wt% of PA11 to achieve better mechanical and thermal features as well as retention performances of specific wastewater organic contaminants. Chemical-physical and structural-morphological characterizations, concerning all the nanofillers and the obtained sustainable membranes, are reported as well as the removal and separation studies of two selected anionic and cationic dyes, methyl orange (MO) and methylene blue (MB) in a dead-end filtration apparatus. The newly developed composite ENMs, compared to pristine PA11 ones, show good tensile mechanical and thermal properties, and increased MO and MB removal rates, modulated by the different HNT derivatives employed. Dead-end filtration experiments were performed using 1 and 3 layers of each type of ENM revealing, for 1-layer PA11 ENMs containing HNT modified with octadecylphosphonic acid and (3-aminopropyl)triethoxysilane (PA11@C18_HNT_NH2) and dimethyloctadecyl[3(trimethoxysilyl)propyl]ammoniumchloride (PA11@HNT_N + C18), a selectivity towards the removal of the cationic dye MB with a separation efficiency of 69.8 and 73.3 % respectively. Hence, 3-layer PA11 ENMs doped with HNT functionalized with (3-aminopropyl)triethoxysilane (PA11@HNT_NH2) display the highest retention rate for MO and MB respectively of 100 and 89.8 %.A
Euclid : early release observations : globular clusters in the Fornax galaxy cluster, from dwarf galaxies to the intracluster field
No full textWe present an analysis of Euclid observations of a 0.6 deg2 field in the central region of the Fornax galaxy cluster that were acquired during the performance verification phase. With these data, we investigated the potential of Euclid to identify globular clusters (GCs) at 20 Mpc and validated the search methods using artificial GCs and known GCs within the field from the literature. Our analysis of artificial GCs injected into the data shows that Euclid's data in the IE band is 80% complete at about IE ∼ 26.0 mag (MV ~ –5.0 mag), and it resolves GCs as small as rh = 2.5 pc. In the IE band, we detected more than 95% of the known GCs from previous spectroscopic surveys and GC candidates of the ACS Fornax Cluster Survey, of which more than 80% are resolved. We identify more than 5000 new GC candidates within the field of view down to IE = 25.0 mag, about 1.5 mag fainter than the typical GC luminosity function turn-over magnitude, and we investigated their spatial distribution within the intracluster field. We then focused on the GC candidates around dwarf galaxies and investigated their numbers, stacked luminosity distribution, and stacked radial distribution. While the overall GC properties are consistent with those in the literature, we found an interesting over-representation of relatively bright candidates within a small number of relatively GC-rich dwarf galaxies. Our work confirms the capabilities of Euclid data in detecting GCs and separating them from foreground and background contaminants at a distance of 20 Mpc, particularly for low GC-count systems such as dwarf galaxies.We present an analysis of Euclid observations of a 0.6 deg2 field in the central region of the Fornax galaxy cluster that were acquired during the performance verification phase. With these data, we investigated the potential of Euclid to identify globular clusters (GCs) at 20 Mpc and validated the search methods using artificial GCs and known GCs within the field from the literature. Our analysis of artificial GCs injected into the data shows that Euclid's data in the IE band is 80% complete at about IE ∼ 26.0 mag (MV ~ –5.0 mag), and it resolves GCs as small as rh = 2.5 pc. In the IE band, we detected more than 95% of the known GCs from previous spectroscopic surveys and GC candidates of the ACS Fornax Cluster Survey, of which more than 80% are resolved. We identify more than 5000 new GC candidates within the field of view down to IE = 25.0 mag, about 1.5 mag fainter than the typical GC luminosity function turn-over magnitude, and we investigated their spatial distribution within the intracluster field. We then focused on the GC candidates around dwarf galaxies and investigated their numbers, stacked luminosity distribution, and stacked radial distribution. While the overall GC properties are consistent with those in the literature, we found an interesting over-representation of relatively bright candidates within a small number of relatively GC-rich dwarf galaxies. Our work confirms the capabilities of Euclid data in detecting GCs and separating them from foreground and background contaminants at a distance of 20 Mpc, particularly for low GC-count systems such as dwarf galaxies.A
Euclid : early release observations : overview of the Perseus cluster and analysis of its luminosity and stellar mass functions
No full textThe Euclid Early Release Observations (ERO) programme targeted the Perseus cluster of galaxies, gathering deep data in the central region of the cluster over 0.7 deg2, including the cluster core up to 0.25 r200. The dataset reaches a point-source depth of IE = 28.0 (YE, JE, HE = 25.3), AB magnitudes at 5 σ with a 0''.16 (0''.48) full width at half maximum (FWHM), and a surface brightness limit of 30.1 (29.2) mag arcsec‑2 for radially integrated galaxy profiles. The exceptional depth and spatial resolution of this wide-field multi-band data enable simultaneous detection and characterisation of both bright galaxies and low surface brightness ones, along with their globular cluster systems, from the optical to the near-infrared (NIR). Cluster membership was determined using several methods in order to maximise the completeness and minimise the contamination of foreground and background sources. We adopted a catalogue of 1100 dwarf galaxies, detailed in the corresponding ERO paper, that includes their photometric and structural properties. We identified all other sources in the Euclid images and obtained accurate photometric measurements using AutoProf or AstroPhot for 137 bright cluster galaxies and SourceExtractor for half a million compact sources. This study advances beyond previous analyses of the cluster and enables a range of scientific investigations, which are summarised here. We derived the luminosity and stellar mass functions (LF and SMF) of the Perseus cluster in the Euclid IE band thanks to supplementary u, g, r, i, z, and Hα data from the Canada-France-Hawai'i Telescope (CFHT). Our LF and SMF are the deepest recorded for the Perseus cluster, highlighting the groundbreaking capabilities of the Euclid telescope. We fit the LF and SMF with a Schechter plus Gaussian model. The LF features a dip at M(IE) ≃ ‑19 and a faint-end slope of αS ≃ ‑1.2 to ‑1.3. The SMF displays a low-mass-end slope of αS ≃ ‑1.2 to ‑1.35. These observed slopes are flatter than those predicted for dark matter halos in cosmological simulations, offering significant insights for models of galaxy formation and evolution.The Euclid Early Release Observations (ERO) programme targeted the Perseus cluster of galaxies, gathering deep data in the central region of the cluster over 0.7 deg2, including the cluster core up to 0.25 r200. The dataset reaches a point-source depth of IE = 28.0 (YE, JE, HE = 25.3), AB magnitudes at 5 σ with a 0''.16 (0''.48) full width at half maximum (FWHM), and a surface brightness limit of 30.1 (29.2) mag arcsec‑2 for radially integrated galaxy profiles. The exceptional depth and spatial resolution of this wide-field multi-band data enable simultaneous detection and characterisation of both bright galaxies and low surface brightness ones, along with their globular cluster systems, from the optical to the near-infrared (NIR). Cluster membership was determined using several methods in order to maximise the completeness and minimise the contamination of foreground and background sources. We adopted a catalogue of 1100 dwarf galaxies, detailed in the corresponding ERO paper, that includes their photometric and structural properties. We identified all other sources in the Euclid images and obtained accurate photometric measurements using AutoProf or AstroPhot for 137 bright cluster galaxies and SourceExtractor for half a million compact sources. This study advances beyond previous analyses of the cluster and enables a range of scientific investigations, which are summarised here. We derived the luminosity and stellar mass functions (LF and SMF) of the Perseus cluster in the Euclid IE band thanks to supplementary u, g, r, i, z, and Hα data from the Canada-France-Hawai'i Telescope (CFHT). Our LF and SMF are the deepest recorded for the Perseus cluster, highlighting the groundbreaking capabilities of the Euclid telescope. We fit the LF and SMF with a Schechter plus Gaussian model. The LF features a dip at M(IE) ≃ ‑19 and a faint-end slope of αS ≃ ‑1.2 to ‑1.3. The SMF displays a low-mass-end slope of αS ≃ ‑1.2 to ‑1.35. These observed slopes are flatter than those predicted for dark matter halos in cosmological simulations, offering significant insights for models of galaxy formation and evolution.A
Agrobacterium-mediated genetic transformation of Melia volkensii Gürke
No full textMelia volkensii, a native dryland tree species in Eastern Africa, is extensively grown for its timber that resists termites, as well as for firewood and animal fodder. This study presents the first successful genetic transformation of Melia volkensii mediated by Agrobacterium tumefaciens. A new binary vector enabled the introduction of the reporter gene M24::eGFP resulting in robust gene expression. This breakthrough facilitates future genetic improvement of M. volkensii, including applications of CRISPR-Cas-9 technology, to develop superior varieties for reforestation and sustainable land management in arid regions.Melia volkensii, a native dryland tree species in Eastern Africa, is extensively grown for its timber that resists termites, as well as for firewood and animal fodder. This study presents the first successful genetic transformation of Melia volkensii mediated by Agrobacterium tumefaciens. A new binary vector enabled the introduction of the reporter gene M24::eGFP resulting in robust gene expression. This breakthrough facilitates future genetic improvement of M. volkensii, including applications of CRISPR-Cas-9 technology, to develop superior varieties for reforestation and sustainable land management in arid regions.A
