Karlsruhe Institute of Technology

About: Karlsruhe Institute of Technology is a education organization based out in Karlsruhe, Germany. It is known for research contribution in the topics: Computer science & Catalysis. The organization has 37946 authors who have published 82138 publications receiving 2197068 citations. The organization is also known as: KIT & University of Karlsruhe.

Measurements of the cosmic-ray positron fraction from 1 to 50 geV

Abstract: Two measurements of the cosmic-ray positron fraction as a function of energy have been made using the High-Energy Antimatter Telescope (HEAT) balloon-borne instrument. The first flight took place from Fort Sumner, New Mexico, in 1994 and yielded results above the geomagnetic cutoff energy of 4.5 GeV. The second flight, from Lynn Lake, Manitoba, in 1995, permitted measurements over a larger energy interval, from 1 to 50 GeV. We present results on the positron fraction based on data from the Lynn Lake flight and compare these with the previously published results from the Fort Sumner flight. The results confirm that the positron fraction does not increase with energy above ≈ 10 GeV, although a small excess above purely secondary production cannot be ruled out. At low energies the positron fraction is slightly larger than that reported from measurements made in the 1960s. This effect could possibly be a consequence of charge dependence in the level of solar modulation.

The currency of reciprocity - gift-exchange in the workplace

Abstract: What determines reciprocity in employment relations? We conducted a controlled field experiment to measure the extent to which monetary and non-monetary gifts affect workers’ performance. We find that non-monetary gifts have a much stronger impact than monetary gifts of equivalent value. We also observe that when workers are offered the choice, they prefer receiving money but reciprocate as if they received a non-monetary gift. This result is consistent with the common saying, "it’s the thought that counts". We underline this point by showing that also monetary gifts can effectively trigger reciprocity if the employer invests more time and effort into the gift’s presentation.

Ecological momentary assessment of mood disorders and mood dysregulation.

Abstract: In this review, we discuss ecological momentary assessment (EMA) studies on mood disorders and mood dysregulation, illustrating 6 major benefits of the EMA approach to clinical assessment: (a) Real-time assessments increase accuracy and minimize retrospective bias; (b) repeated assessments can reveal dynamic processes; (c) multimodal assessments can integrate psychological, physiological, and behavioral data; (d) setting- or context-specific relationships of symptoms or behaviors can be identified; (e) interactive feedback can be provided in real time; and (f) assessments in real-life situations enhance generalizability. In the context of mood disorders and mood dysregulation, we demonstrate that EMA can address specific research questions better than laboratory or questionnaire studies. However, before clinicians and researchers can fully realize these benefits, sets of standardized e-diary questionnaires and time sampling protocols must be developed that are reliable, valid, and sensitive to change.

How to correctly determine the different chlorophyll fluorescence parameters and the chlorophyll fluorescence decrease ratio RFd of leaves with the PAM fluorometer

Abstract: This contribution is a practical guide to the measurement of the different chlorophyll (Chl) fluorescence parameters and gives examples of their development under high-irradiance stress. From the Chl fluorescence induction kinetics upon irradiation of dark-adapted leaves, measured with the PAM fluorometer, various Chl fluorescence parameters, ratios, and quenching coefficients can be determined, which provide information on the functionality of the photosystem 2 (PS2) and the photosynthetic apparatus. These are the parameters Fv, Fm, F0, Fm′, Fv′, NF, and ΔF, the Chl fluorescence ratios Fv/Fm, Fv/F0, ΔF/Fm′, as well as the photochemical (qP) and non-photochemical quenching coefficients (qN, qCN, and NPQ). qN consists of three components (qN = qE + qT + qI), the contribution of which can be determined via Chl fluorescence relaxation kinetics measured in the dark period after the induction kinetics. The above Chl fluorescence parameters and ratios, many of which are measured in the dark-adapted state of leaves, primarily provide information on the functionality of PS2. In fully developed green and dark-green leaves these Chl fluorescence parameters, measured at the upper adaxial leaf side, only reflect the Chl fluorescence of a small portion of the leaf chloroplasts of the green palisade parenchyma cells at the upper outer leaf half. Thus, PAM fluorometer measurements have to be performed at both leaf sides to obtain information on all chloroplasts of the whole leaf. Combined high irradiance (HI) and heat stress, applied at the upper leaf side, strongly reduced the quantum yield of the photochemical energy conversion at the upper leaf half to nearly zero, whereas the Chl fluorescence signals measured at the lower leaf side were not or only little affected. During this HL-stress treatment, qN, qCN, and NPQ increased in both leaf sides, but to a much higher extent at the lower compared to the upper leaf side. qN was the best indicator for non-photochemical quenching even during a stronger HL-stress, whereas qCN and NPQ decreased with progressive stress even though non-photochemical quenching still continued. It is strongly recommended to determine, in addition to the classical fluorescence parameters, via the PAM fluorometer also the Chl fluorescence decrease ratio RFd (Fd/Fs), which, when measured at saturation irradiance is directly correlated to the net CO2 assimilation rate (P N) of leaves. This RFd-ratio can be determined from the Chl fluorescence induction kinetics measured with the PAM fluorometer using continuous saturating light (cSL) during 4–5 min. As the RFd-values are fast measurable indicators correlating with the photosynthetic activity of whole leaves, they should always be determined via the PAM fluorometer parallel to the other Chl fluorescence coefficients and ratios.