Technische Universität Dresden: Qucosa
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The impact of salps (Salpa thompsoni) on the Antarctic krill population (Euphausia superba). an individual‑based modelling study
No full textBackground
Krill (Euphausia superba) and salps (Salpa thompsoni) are key macrozooplankton grazers in the Southern Ocean ecosystem. However, due to differing habitat requirements, both species previously exhibited little spatial overlap. With ongoing climate change-induced seawater temperature increase and regional sea ice loss, salps can now extend their spatial distribution into historically krill-dominated areas and increase rapidly due to asexual reproduction when environmental conditions are favorable. Understanding the potential effects on krill is crucial, since krill is a species of exceptional trophic significance in the Southern Ocean food web. Negative impacts on krill could trigger cascading effects on its predators and prey. To address this question, we combined two individual-based models on salps and krill, which describe the whole life cycle of salp individuals and the dynamic energy budget of individual krill. The resulting new model PEKRIS (PErformance of KRIll vs. Salps) simulates a krill population for 100 years under varying chlorophyll-a concentrations in the presence or absence of salps.
Results
All of the investigated krill population properties (abundance, mean length, and yearly egg production) were significantly impacted by the presence of salps. On the other hand, salp density was not impacted if krill were present. The medians of krill population properties deviated during variable maximum chlorophyll-a density per year when salps were introduced by − 99.9% (− 234 individuals per 1000 m3) for krill density, − 100% (− 22,062 eggs per 1000 m3) for krill eggs and − 0.9% (− 0.3 mm) for mean length of krill.
Conclusions
If both species compete for the same food resource in a closed space, salps seem to inhibit krill populations. Further simulation studies should investigate whether this effect prevails if different phytoplankton sizes and consumption preferences of krill are implemented. Furthermore, direct predation of the two species or consumption of krill fecal pellets by salps could change the impact size of the food competition
Liver fat as risk factor of hepatic and cardiometabolic diseases
No full textNon-alcoholic fatty liver disease (NAFLD) is a disorder characterized by excessive accumulation of fat in the liver that can progress to liver inflammation (non-alcoholic steatohepatitis [NASH]), liver fibrosis, and cirrhosis. Although most efforts for drug development are focusing on the treatment of the latest stages of NAFLD, where significant fibrosis and NASH are present, findings from studies suggest that the amount of liver fat may be an important independent risk factor and/or predictor of development and progression of NAFLD and metabolic diseases. In this review, we first describe the current tools available for quantification of liver fat in humans and then present the clinical and pathophysiological evidence that link liver fat with NAFLD progression as well as with cardiometabolic diseases. Finally, we discuss current pharmacological and non-pharmacological approaches to reduce liver fat and present open questions that have to be addressed in future studies
Response to (K)RAS/G12C and EGFR Inhibition in a Patient With NRAS/G12C-Mutated Rectal Cancer
No full textThe three human Ras genes HRAS, NRAS, and KRAS belong to the most frequently mutated oncogenes in human cancer. They encode similar proteins that share 82%-90% overall sequence identity and are made up of 188-189 amino acids. Most Ras alterations are still not druggable.1 Sotorasib (formerly known as AMG 510) is the first-in-class KRAS/G12C inhibitor and has recently demonstrated superior activity in KRAS/G12C-mutant, pretreated lung cancer compared with chemotherapy.2,3 Recently, phase II data from the CodeBreaK100 trial have shown antitumor activity of sotorasib in patients with heavily pretreated KRAS/G12C-mutant colorectal cancer (CRC).4 Combining KRAS/G12C and EGFR inhibition seems to increase the activity compared with KRAS/G12C blockade alone and is the current strategy for registration studies (ClincalTrials.gov identifiers: NCT05198934 and NCT04793958).5,6 Sotorasib binds to KRAS/G12C through a unique interaction with a surface groove created by side-chain rotation of histidine 95 (His95).7 So far, there are no clinical data indicating that sotorasib is active in patients with NRAS/G12C- or HRAS/G12C-mutated cancer. - Here, we report a patient with NRAS/G12C-mutated rectal cancer who responded to treatment with sotorasib and the EGFR antibody panitumumab. Written consent to publish the information contained in this article was obtained from the patient. [Aus: Introduction
Microalgae contribution in enhancing the circular economy drive of biochemical conversion systems: A review
No full textThe global impact of greenhouse gas emissions requires concerted efforts to reduce emissions and energy use, and to increase carbon capture and sequestration. Promoting the circular economy in CO₂ sequestration systems optimises resource use and reduces the emissions burden throughout the supply chain. Carbon capture from anaerobic digestion, composting and fermentation (particularly ethanol) processes offers great opportunities for climate change mitigation. The waste/by-products generated from these processes can limit the need to source nutrients from outside the system and increase the potential for circular economy. The integration of microalgae cultivation with each of anaerobic digestion, composting and ethanol fermentation processes provides a new model for climate change mitigation of biogenic CO₂ and circular economy. While this model is limited by high energy consumption and nutrient demand, seasonal variability, operational efficiency and end-user requirements, further research and policy support will go a long way in realising the associated benefits, including in CO₂ fixation, nutrient recovery, waste remediation and as an alternative source of animal feed
Bilateral investment treaties and portfolio investment
No full textWe analyze the effect of bilateral investment treaties (BITs) on bilateral foreign portfolio investment in equity and debt securities. We find that expropriation risk and the level of a BIT’s investor protection are complementary. Applying a Poisson Pseudo-Maximum-Likelihood model to a panel of 60 home and 39 host countries from 2002 to 2017, we find that host countries receive 40% more bilateral equity investment when they protect foreign investors with a BIT. This effect almost doubles when investment protection of BITs is strong, and the political risk of the host country is high
High-concentration measurements with optical aerosol spectrometers by signal fluctuation analysis
No full textOptical aerosol measurement systems can be classified into single-particle counting techniques and ensemble techniques. In single-particle counting instruments, such as optical aerosol spectrometers, each particle is analyzed individually. This allows for the accurate measurement of the number concentration and the size distribution of the measured aerosol. Current aerosol spectrometers suffer from a limited concentration range due to coincidence errors. In contrast, ensemble techniques, such as photometers, are suitable for high-concentration measurements. One major drawback of such instruments is that they only provide information about one aerosol property, which is typically the mass concentration. A new ensemble technique for the simultaneous measurement of two aerosol properties, namely particle size and concentration, was developed and experimentally verified. The results show that the median particle size (D50) of a monodisperse aerosol can be determined with a deviation of about 10 %, and the concentration with a deviation of about 30 %. With individual instrument calibration, the accuracy can be further improved to approximately 5 % with respect to particle size and 10 % with respect to concentration. The method may be either implemented as a standalone measurement device or, as an add-on for e. g. optical particle spectrometers in the form of a high-concentration mode
Development of a Motion Control for a highly dynamic, self‑propelled driving simulator
No full textThe new concept of the self-propelled driving simulator comprises a hexapod, a yaw joint and a wheel-based motion platform with four individually steerable wheels. This concept provides a theoretically unlimited motion range, which especially enables highly dynamic drive maneuvers. To ensure an omnidirectional motion, the motion platform has to accelerate instantly in any direction. This requirement leads to the main challenges in the control system of the simulator: taking into account the nonlinear and transient tire characteristics and generating the target accelerations as expected by the driver. According to these requirements, the Motion Control is only for controlling the horizontal dynamics of the motion platform. The Motion Control presented in this paper includes various model definitions, especially regarding the essential tire characteristics considered within an extended HSRI (Highway Safety Research Institute) tire model. The Motion Control as Two-Degrees-of-Freedom control contains a Feedforward for generating target body forces, a Control Allocation for an optimal force distribution to the wheels, a Single Wheel Control as a specific control of the tire forces, and a Compensation Control on acceleration level. Investigation of this control by simulation, using a simplified reference model, already revealed a high controller performance regarding accuracy and quality. The optimal force distribution leads to an equal adhesion utilization and the Compensation Control compensates the remaining Single Wheel Control deviations. Difficulties only occur for the steering angle in the case of low velocity up to a standstill. Due to the exact input–output linearization, the Single Wheel Control leads to a singularity and instability. Therefore, the steering angle requires exceptional control in this case
Experimental and numerical study on the transport of dilute bubbles in a T-junction channel flow
No full textThe present study investigates the transport of dilute bubbles by transitional flow in a joining, cross-flow-type T-junction channel geometry with Reynolds numbers at the outlet branch from Re₃ = 600 to 1800 and an inlet volume flow rate ratio of 1. Bubbles with diameters between d/b = 400 and 600 µm are considered. The schematic pattern of the single-phase flow is introduced based on streakline dye visualizations. Complex 3D flow due to the narrow channel design dominates the recirculation area and flow instabilities become important with increasing Reynolds number, which can be observed by the fading of dye intensity. A numerical method is presented with unsteady boundary conditions based on laser Doppler velocimetry measurements. Bubble trajectories are obtained by an Euler-Lagrange approach. Using high-speed shadowgraphy method combined with image processing, bubble sizes were measured, and bubble trajectories were evaluated. Experimental bubble trajectories and numerically predicted bubble positions show good agreement for Re₃ = 600, which is also the case with the dye visualization image. For higher Reynolds numbers, measurements of the bubble trajectories are reported and compared to dye visualization images. The increasing flow instabilities influence the bubble transport, resulting in large variations of bubble locations
The Willpower Paradox: Possible and Impossible Conceptions of Self-Control
No full textSelf-control denotes the ability to override current desires to render behavior consistent with long-term goals. A key assumption is that self-control is required when short-term desires are transiently stronger (more preferred) than long-term goals and people would yield to temptation without exerting self-control. We argue that this widely shared conception of self-control raises a fundamental yet rarely discussed conceptual paradox: How is it possible that a person most strongly desires to perform a behavior (e.g., eat chocolate) and at the same time desires to recruit self-control to prevent themselves from doing it? A detailed analysis reveals that three common assumptions about self-control cannot be true simultaneously. To avoid the paradox, any coherent theory of self-control must abandon either the assumption (a) that recruitment of self-control is an intentional process, or (b) that humans are unitary agents, or (c) that self-control consists in overriding the currently strongest desire. We propose a taxonomy of different kinds of self-control processes that helps organize current theories according to which of these assumptions they abandon. We conclude by outlining unresolved questions and future research perspectives raised by different conceptions of self-control and discuss implications for the question of whether self-control can be considered rational
Biomarkers in 5q‑associated spinal muscular atrophy - a narrative review
No full text5q-associated spinal muscular atrophy (SMA) is a rare genetic disease caused by mutations in the SMN1 gene, resulting in a loss of functional SMN protein and consecutive degeneration of motor neurons in the ventral horn. The disease is clinically characterized by proximal paralysis and secondary skeletal muscle atrophy. New disease-modifying drugs driving SMN gene expression have been developed in the past decade and have revolutionized SMA treatment. The rise of treatment options led to a concomitant need of biomarkers for therapeutic guidance and an improved disease monitoring. Intensive efforts have been undertaken to develop suitable markers, and numerous candidate biomarkers for diagnostic, prognostic, and predictive values have been identified. The most promising markers include appliance-based measures such as electrophysiological and imaging-based indices as well as molecular markers including SMN-related proteins and markers of neurodegeneration and skeletal muscle integrity. However, none of the proposed biomarkers have been validated for the clinical routine yet. In this narrative review, we discuss the most promising candidate biomarkers for SMA and expand the discussion by addressing the largely unfolded potential of muscle integrity markers, especially in the context of upcoming muscle-targeting therapies. While the discussed candidate biomarkers hold potential as either diagnostic (e.g., SMN-related biomarkers), prognostic (e.g., markers of neurodegeneration, imaging-based markers), predictive (e.g., electrophysiological markers) or response markers (e.g., muscle integrity markers), no single measure seems to be suitable to cover all biomarker categories. Hence, a combination of different biomarkers and clinical assessments appears to be the most expedient solution at the time