+1,5° C: Wieviel Treibhausgase dürfen wir noch emittieren? CCCA Fact Sheet #40

Um die globale Erwärmung und somit die Auswirkungen des Klimawandels, wie im Pariser Übereinkommen festgelegt, auf +1,5 °C bzw. unter +2 °C gegenüber dem vorindustriellen Niveau (1850-1900) zu begrenzen muss für die Klimaneutralitätsziele die Gesamtmenge an Treibhausgas (THG)-Emissionen entsprechend beschränkt werden. Unter aktuellen Maßnahmenplänen, ohne zusätzliche Schritte, bewegen wir uns noch in diesem Jahrhundert auf +2,8 °C zu, was deutlich größere Schäden und Verluste zur Folge hätte. Das Factsheet basiert auf der umfangreichen Ausarbeitung in: CCCA (2022): +1,5° C: Wieviel Treibhausgase dürfen wir noch emittieren? Hintergrundpapier zu globalen und nationalen Treibhausgasbudgets. K. Steininger, T. Schinko, H. Rieder, H. Kromp-Kolb, S. Kienberger, G. Kirchengast, C. Michl, I. Schwarzl, S. Lambert. Wien: CCC

First passage and first hitting times of Lévy flights and Lévy walks

Abstract For both Lévy flight and Lévy walk search processes we analyse the full distribution of first-passage and first-hitting (or first-arrival) times. These are, respectively, the times when the particle moves across a point at some given distance from its initial position for the first time, or when it lands at a given point for the first time. For Lévy motions with their propensity for long relocation events and thus the possibility to jump across a given point in space without actually hitting it (‘leapovers’), these two definitions lead to significantly different results. We study the first-passage and first-hitting time distributions as functions of the Lévy stable index, highlighting the different behaviour for the cases when the first absolute moment of the jump length distribution is finite or infinite. In particular we examine the limits of short and long times. Our results will find their application in the mathematical modelling of random search processes as well as computer algorithms

Search reliability and search efficiency of combined Lévy–Brownian motion: long relocations mingled with thorough local exploration

A combined dynamics consisting of Brownian motion and Levy flights is exhibited by a variety of biological systems performing search processes. Assessing the search reliability of ever locating the target and the search efficiency of doing so economically of such dynamics thus poses an important problem. Here we model this dynamics by a one-dimensional fractional Fokker-Planck equation combining unbiased Brownian motion and Levy flights. By solving this equation both analytically and numerically we show that the superposition of recurrent Brownian motion and Levy flights with stable exponent α<1, by itself implying zero probability of hitting a point on a line, lead to transient motion with finite probability of hitting any point on the line. We present results for the exact dependence of the values of both the search reliability and the search efficiency on the distance between the starting and target positions as well as the choice of the scaling exponent α of the Levy flight component

Analysis of plant mitochondrial function using fluorescent protein sensors

Mitochondrial physiology sets the basis for function of the organelle and vice versa. While a limited range of in vivo parameters, such as oxygen consumption, has been classically accessible for measurement, a growing collection of fluorescent protein sensors can now give insights into the physiology of plant mitochondria. Nevertheless, the meaningful application of these sensors in mitochondria is technically challenging and requires rigorous experimental standards. Here we exemplify the application of three genetically encoded sensors to monitor glutathione redox potential, pH, and calcium in the matrix of mitochondria in intact plants. We describe current methods for quantitative imaging and analysis in living root tips by confocal microscopy and discuss methodological limitations