90 research outputs found
Cognitive processes in categorical and associative priming: a diffusion model analysis
Cognitive processes and mechanisms underlying different forms of priming were investigated using a diffusion model approach. In a series of 6 experiments, effects of prime-target associations and of a semantic and affective categorical match of prime and target were analyzed for different tasks. Significant associative and categorical priming effects were found in standard analyses of response times (RTs) and error frequencies. Results of diffusion model analyses revealed that priming effects of associated primes were mapped on the drift rate parameter (v), while priming effects of a categorical match on a task-relevant dimension were mapped on the extradecisional parameters (t(0) and d). These results support a spreading activation account of associative priming and an explanation of categorical priming in terms of response competition. Implications for the interpretation of priming effects and the use of priming paradigms in cognitive psychology and social cognition are discussed
Monte Carlo Simulations of the Transition Radiation Detector of the AMS-02 Experiment
The Transition Radiation Detector of the AMS-02 experiment on the
International Space Station is used for the separation of cosmic-ray positrons
and electrons from protons and anti-protons, and for the identification of
nuclei up to carbon (Z<=6). We present the Geant4 simulation that is used to
describe the ionization and transition radiation processes and compare its
results to flight data from AMS-02. After applying empirical corrections to the
simulated data, the particle energy deposition and likelihood distributions in
the TRD are described with high accuracy.Comment: 7 pages, 9 figures. Accepted for publication in Nuclear Inst. and
Methods in Physics Research, A. CC-BY-NC-ND 4.0 licens
Isoprene emission and photosynthesis during heat waves and drought in black locust
Extreme weather conditions, like heat waves and drought, can substantially affect tree physiology and the emissions of biogenic volatile organic compounds (BVOC), including isoprene. To date, however, there is only limited understanding of BVOC emission patterns during prolonged heat and coupled heat–drought stress as well as post-stress recovery. To assess the impacts of heat and heat–drought stress on BVOC emissions, we studied gas exchange and isoprene emissions of black locust trees under controlled environmental conditions. Leaf gas exchange of isoprene, CO2 and H2O was quantified using branch chambers connected to a protontransfer-reaction mass spectrometer and an infrared gas analyzer. Heat and heat–drought stress resulted in a sharp decline of photosynthesis and stomatal conductance. Simultaneously, isoprene emissions increased six- to eight-fold in the heat and heat–drought treatment and resulted in a carbon loss that was equivalent to 12 % and 20 % of assimilated carbon at the time of measurement. Once temperature stress was released at the end of two 15 days long heat waves, stomatal conductance remained reduced, while isoprene emissions and photosynthesis recovered quickly to values of the control trees. Further, we found isoprene emissions to co-vary with net photosynthesis during non-stressful conditions, while during the heat waves, isoprene emissions could be solely described by non-linear functions of light and temperature. However, when isoprene emissions betweentreatments were compared under the same temperature and light conditions (e.g., T = 30° C, PAR = 500 µmol m−2 s−1), heat and heat–drought stressed trees would emit less isoprene than control trees. Ourfindings suggest that different parameterizations of light and temperature functions are needed in order to predict tree isoprene emissions under heat and combined heat–drought stress
ARLTS1 polymorphisms and basal cell carcinoma of the skin
Polymorphisms in the ARLTS1 gene, a member of the Ras super-family, have been associated with susceptibility in different cancer types. The involvement of the gene in apoptotic signalling motivated us to study the role of ARLTS1 polymorphic variations in basal cell carcinoma of the skin (BCC). In a case-control study, 529 cases diagnosed with BCC and 533 controls from Hungary, Romania and Slovakia were genotyped for the S99S (297G>A), P131L (392C>T), L132L (396G>C), C148R (442T>C) and W149X (446G>A) polymorphisms in the ARLTS1 gene. No significant association between any of the single nucleotide polymorphisms (SNP) and risk of BCC (S99S, odds ratio (OR) 0.96, 95% confidence interval (CI) 0.60-1.53; P131L, OR 1.31 95%CI 0.74-2.31; L132L, OR 0.50, 95%CI 0.02-7.07; C148R, OR 0.50, 95%CI 0.69-1.18; and W149X, OR 1.01, 95%CI 0.37-2.79) was detected. Furthermore, no significant difference in the distribution of haplotypes due to five polymorphisms in the ARLTS1 gene was found between the BCC cases and controls. Our data rule out an association between variants in ARLTS1 and risk of BCC in the investigated population
Hot drought reduces the effects of elevated COâ‚‚ on tree water use efficiency and carbon metabolism
- Trees are increasingly exposed to hot droughts due to CO2-induced climate change. However, the direct role of [CO2] in altering tree physiological responses to drought and heat stress remains ambiguous.
- Pinus halepensis (Aleppo pine) trees were grown from seed under ambient (421 ppm) or elevated (867 ppm) [CO2]. The 1.5-yr-old trees, either well watered or drought treated for 1 month, were transferred to separate gas-exchange chambers and the temperature gradually increased from 25°C to 40°C over a 10 d period. Continuous whole-tree shoot and root gasexchange measurements were supplemented by primary metabolite analysis.
- Elevated [CO2] reduced tree water loss, reflected in lower stomatal conductance, resulting in a higher water-use efficiency throughout amplifying heat stress. Net carbon uptake declined strongly, driven by increases in respiration peaking earlier in the well-watered (31– 32°C) than drought (33–34°C) treatments unaffected by growth [CO2]. Further, drought altered the primary metabolome, whereas the metabolic response to [CO2] was subtle and mainly reflected in enhanced root protein stability.
- The impact of elevated [CO2] on tree stress responses was modest and largely vanished with progressing heat and drought. We therefore conclude that increases in atmospheric [CO2] cannot counterbalance the impacts of hot drought extremes in Aleppo pine
Isoprene emission and photosynthesis during heatwaves and drought in black locust
Extreme weather conditions like heatwaves and drought can substantially
affect tree physiology and the emissions of isoprene. To date, however, there
is only limited understanding of isoprene emission patterns during prolonged
heat stress and next to no data on emission patterns during coupled
heat–drought stress or during post-stress recovery. We studied gas exchange
and isoprene emissions of black locust trees under episodic heat stress and
in combination with drought. Heatwaves were simulated in a controlled
greenhouse facility by exposing trees to outside temperatures
+10 °C, and trees in the heat–drought treatment were supplied with half of the irrigation water given to
heat and control trees. Leaf gas exchange of isoprene, CO2 and H2O
was quantified using self-constructed, automatically operating chambers,
which were permanently installed on leaves (n = 3 per treatment). Heat and
combined heat–drought stress resulted in a sharp decline of net
photosynthesis (Anet) and stomatal conductance. Simultaneously,
isoprene emissions increased 6- to 8-fold in the heat and heat–drought
treatment, which resulted in a carbon loss that was equivalent to 12 and
20 % of assimilated carbon at the time of measurement. Once temperature
stress was released at the end of two 15-day-long heatwaves, stomatal
conductance remained reduced, while isoprene emissions and Anet
recovered quickly to values of the control trees. Further, we found that
isoprene emissions covaried with Anet during nonstress
conditions, while during the heatwaves, isoprene emissions were not related
to Anet but to light and temperature. Under standard air
temperature and light conditions (here 30 °C and photosynthetically
active radiation of 500 µmol m−2 s−1), isoprene
emissions of the heat trees were by 45 % and the heat–drought trees were
by 27 % lower than in control trees. Moreover, temperature response
curves showed that not only the isoprene emission factor changed during both
heat and heat–drought stress, but also the shape of the response. Because
introducing a simple treatment-specific correction factor could not reproduce
stress-induced isoprene emissions, different parameterizations of light and
temperature functions are needed to describe tree isoprene emissions under
heat and combined heat–drought stress. In order to increase the accuracy of
predictions of isoprene emissions in response to climate extremes, such
individual stress parameterizations should be introduced to current BVOC
models
Height Simulation in a Virtual Reality CAVE System: Validity of Fear Responses and Effects of an Immersion Manipulation
Acrophobia is characterized by intense fear in height situations. Virtual reality (VR) can be used to trigger such phobic fear, and VR exposure therapy (VRET) has proven effective for treatment of phobias, although it remains important to further elucidate factors that modulate and mediate the fear responses triggered in VR. The present study assessed verbal and behavioral fear responses triggered by a height simulation in a 5-sided cave automatic virtual environment (CAVE) with visual and acoustic simulation and further investigated how fear responses are modulated by immersion, i.e., an additional wind simulation, and presence, i.e., the feeling to be present in the VE. Results revealed a high validity for the CAVE and VE in provoking height related self-reported fear and avoidance behavior in accordance with a trait measure of acrophobic fear. Increasing immersion significantly increased fear responses in high height anxious (HHA) participants, but did not affect presence. Nevertheless, presence was found to be an important predictor of fear responses. We conclude that a CAVE system can be used to elicit valid fear responses, which might be further enhanced by immersion manipulations independent from presence. These results may help to improve VRET efficacy and its transfer to real situations
Comparison between B·R·A·H·M·S PCT direct, a new sensitive point-of-care testing device for rapid quantification of procalcitonin in emergency department patients and established reference methods - a prospective multinational trial
Background: Procalcitonin (PCT) is increasingly being used for the diagnostic and prognostic work up of patients with suspected infections in the emergency department (ED). Recently, B·R·A·H·M·S PCT direct, the first high sensitive point-of-care test (POCT), has been developed for fast PCT measurement on capillary or venous blood samples. Methods: This is a prospective, international comparison study conducted in three European EDs. Consecutive patients with suspicion of bacterial infection were included. Duplicate determination of PCT was performed in capillary (fingertip) and venous whole blood (EDTA), and compared to the reference method. The diagnostic accuracy was evaluated by correlation and concordance analyses. Results: Three hundred and three patients were included over a 6-month period (60.4% male, median age 65.2 years). The correlation between capillary or venous whole blood and the reference method was excellent: r2=0.96 and 0.97, sensitivity 88.1% and 93.0%, specificity 96.5% and 96.8%, concordance 93% and 95%, respectively at a 0.25 μg/L threshold. No significant bias was observed (-0.04 and -0.02 for capillary and venous whole blood) although there were 6.8% and 5.1% outliers, respectively. B·R·A·H·M·S PCT direct had a shorter time to result as compared to the reference method (25 vs. 144 min, difference 119 min, 95% CI 110-134 min, p<0.0001). Conclusions: This study found a high diagnostic accuracy and a faster time to result of B·R·A·H·M·S PCT direct in the ED setting, allowing shortening time to therapy and a more wide-spread use of PCT
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