31325 research outputs found
Sort by
Precise control of TiO2 overlayer on hematite nanorod arrays by ALD for the photoelectrochemical water splitting
No full textThe short lifetime of electron–hole pairs and high electron–hole recombination rate at surface states significantly limit the practical applications of hematite (α-Fe2O3) photoanodes in photoelectrochemical (PEC) water splitting. Surface modification with a TiO2 overlayer has been demonstrated to be an efficient way to improve the PEC performance. However, a fine control of the TiO2 overlayer and a deep understanding of the impact of the TiO2 overlayer with variable thickness on the PEC performance, to the best of our knowledge, has yet to be done. Here, a conformal ultrathin TiO2 overlayer is successfully deposited on hydrothermal grown one-dimensional hematite nanorod arrays by atomic layer deposition. The morphology and thickness of the TiO2 overlayer can be precisely controlled. The effect of the thickness of the TiO2 overlayer on the overall water splitting efficiency of hematite photoanodes under visible and UV light has been systematically investigated. The charge excitation and transfer mechanism at the semiconductor–electrolyte interface has also been studied.Peer Reviewe
The non-linear impact of risk tolerance on entrepreneurial profit and business survival
No full textEntrepreneurs tend to be risk tolerant but is higher risk tolerance always better? In a sample of about 2100 small businesses, we find an inverted U-shaped relation between risk tolerance and profitability. This relationship holds in a simple bilateral regression, and even after controlling for a large set of individual and business characteristics. Apparently, one major transmission goes from risk tolerance via investments to profits. This is quite robust as it applies for both past and planned investments. Considering business survival, we show, first, that less profitable businesses leave the market while moderately risk tolerant entrepreneurs survive more often. Second, the high risk-low profit part of the U-shaped relation seems to disappear among businesses being 4 years and older, indicating that such inferior risk-profit combinations disappear over time. These findings are important for the concept of business readiness trainings as the motivation (and ability) to take risks should potentially be accompanied by some warning that taking too much risk can be detrimental to long-term business success.Plain English Summary: Very high risk tolerance tends to reduce entrepreneurial profit and survival: Entrepreneurs must be willing to take risks in order to run their business successfully. Accordingly, future entrepreneurs are motivated in respective trainings to overcome higher degrees of risk avoidance. Our research contributes to this issue in that we empirically analyze the profitability and survival of small enterprises, depending on the risk tolerance of the respective entrepreneur. We find the expected positive relation between risk tolerance and entrepreneurial profit, however, only up to a certain degree. Thereafter, higher risk tolerance is detrimental to business success, a result to be considered in entrepreneurial trainings.Deutsche Forschungsgemeinschafthttp://dx.doi.org/10.13039/501100001659Peer Reviewe
Spontaneous single-nucleotide substitutions and microsatellite mutations have distinct distributions of fitness effects
No full textThe fitness effects of new mutations determine key properties of evolutionary processes. Beneficial mutations drive evolution, yet selection is also shaped by the frequency of small-effect deleterious mutations, whose combined effect can burden otherwise adaptive lineages and alter evolutionary trajectories and outcomes in clonally evolving organisms such as viruses, microbes, and tumors. The small effect sizes of these important mutations have made accurate measurements of their rates difficult. In microbes, assessing the effect of mutations on growth can be especially instructive, as this complex phenotype is closely linked to fitness in clonally evolving organisms. Here, we perform high-throughput time-lapse microscopy on cells from mutation-accumulation strains to precisely infer the distribution of mutational effects on growth rate in the budding yeast, Saccharomyces cerevisiae. We show that mutational effects on growth rate are overwhelmingly negative, highly skewed towards very small effect sizes, and frequent enough to suggest that deleterious hitchhikers may impose a significant burden on evolving lineages. By using lines that accumulated mutations in either wild-type or slippage repair-defective backgrounds, we further disentangle the effects of 2 common types of mutations, single-nucleotide substitutions and simple sequence repeat indels, and show that they have distinct effects on yeast growth rate. Although the average effect of a simple sequence repeat mutation is very small (approximately 0.3%), many do alter growth rate, implying that this class of frequent mutations has an important evolutionary impact.Peer Reviewe
What is still at stake in the Gran Chaco? Social-ecological impacts of alternative land-system futures in a global deforestation hotspot
No full textCommodity agriculture continues to spread into tropical dry forests globally, eroding their social-ecological integrity. Understanding where deforestation frontiers expand, and which impacts this process triggers, is thus important for sustainability planning. We reconstructed past land-system change (1985–2015) and simulated alternative land-system futures (2015–2045) for the Gran Chaco, a 1.1 million km2 global deforestation hotspot with high biological and cultural diversity. We co-developed nine plausible future land-system scenarios, consisting of three contrasting policy narratives (Agribusiness, Ecomodernism, and Integration) and three agricultural expansion rates (high, medium, and low). We assessed the social-ecological impacts of our scenarios by comparing them with current biodiversity, carbon density, and areas used by forest-dependent people. Our analyses revealed four major insights. First, intensified agriculture and mosaics of agriculture and remaining natural vegetation have replaced large swaths of woodland since 1985. Second, simulated land-system futures until 2045 revealed potential hotspots of natural vegetation loss (e.g. western and southern Argentinian Chaco, western Paraguayan Chaco), both due to the continued expansion of existing agricultural frontiers and the emergence of new ones. Third, the strongest social-ecological impacts were consistently connected to the Agribusiness scenarios, while impacts were lower for the Ecomodernism and Integration scenarios. Scenarios based on our Integration narrative led to lower social impacts, while Ecomodernism had lower ecological impacts. Fourth, comparing recent land change with our simulations showed that 10% of the Chaco is on a pathway consistent with our Agribusiness narrative, associated with adverse social-ecological impacts. Our results highlight that much is still at stake in the Chaco. Stricter land-use and conservation planning are urgently needed to avoid adverse social-ecological outcomes, and our results charting the option space of plausible land-system futures can support such planning.Peer Reviewe
The power of materiality: Local orders, interaction and global governance
No full textThe article examines the power of materiality in the context of refugee camps, demonstrating how local orders and global governance are intricately interwoven within the material domain. It draws on ethnographic fieldwork conducted in Burmese refugee camps in Thailand to illustrate how sociomateriality can establish spaces of exclusion and associated memberships through their practical implementation, but at the same time permit flexible forms of local manifestations. These aspects represent the tangible realities that people, both ordinary camp residents and local authorities, navigate and achieve in their local public camp life. By means of detailed observation of three distinct camp situations—namely, interactions of membership, checkpoint practices, and the temporary suspension of public camp life—the article argues that mundane sociomaterial practices can both produce and undermine the political intentions of architects to realize materialities of exclusion. Nevertheless, despite their partial and incomplete nature and the capacity of people to circumvent them, the materiality of exclusion is maintained and persists. By elucidating these dynamics, the article contributes to the existing literature that emphasizes the importance of understanding camp governance through the lens of sociomateriality.Peer Reviewe
A beautiful face is good when we’re judged by others, a moral character is better
No full textMoral beauty, reflected in one’s actions, and facial beauty both affect how we are judged. Here, we investigated how moral and facial beauty interact to affect social judgments and emotional responses, employing event-related brain potentials (ERPs). All participants (female) associated positive, neutral, or negative verbal information with faces scoring high or low on attractiveness and performed ratings of the faces as manipulation checks. In a separate test phase, the faces were presented again, and participants made valenced social judgments of the persons. Results show a dominance of moral beauty in valenced social judgments as well as ERPs related to reflexive and evaluative emotional responses (early posterior negativity and late positive potential), whereas facial attractiveness mattered little. In contrast, facial attractiveness affected visual processing (N170). Similarly, relatively shallow impressions of attractiveness and likability that require no knowledge about the person were influenced by both facial attractiveness and social-emotional information. This pattern of dominant effects of social-emotional information regardless of attractiveness shows that when it comes to our emotional responses and social judgments, moral beauty is what matters most, even in the face of physical beauty.Peer Reviewe
Qualitative analysis of fourth-order hyperbolic equations
No full textWe investigate the qualitative properties of weak solutions to the boundary value problems for fourth-order linear hyperbolic equations with constant coefficients in a plane bounded domain convex with respect to characteristics. Our main scope is to prove some analog of the maximum principle, solvability, uniqueness and regularity results for weak solutions of initial and boundary value problems in the space L 2 . The main novelty of this paper is to establish some analog of the maximum principle for fourth-order hyperbolic equations. This question is very important due to natural physical interpretation and helps to establish the qualitative properties for solutions (uniqueness and existence results for weak solutions). The challenge to prove the maximum principle for weak solutions remains more complicated and at that time becomes more interesting in the case of fourth-order hyperbolic equations, especially, in the case of non-classical boundary value problems with data of weak regularity. Unlike second-order equations, qualitative analysis of solutions to fourth-order equations is not a trivial problem, since not only a solution is involved in boundary or initial conditions, but also its high- order derivatives. Other difficulty concerns the concept of weak solution of the boundary value problems with L 2 – data. Such solutions do not have usual traces, thus, we have to use a special notion for traces to poss correctly the boundary value problems. This notion is traces associated with operator L or L -traces. We also derive an interesting interpretation (as periodicity of characteristic billiard or the John's mapping) of the Fredholm's property violation. Finally, we discuss some potential challenges in applying the results and proposed methods.Peer Reviewe
KineWheel–DeepLabCut Automated Paw Annotation Using Alternating Stroboscopic UV and White Light Illumination
No full textThe article processing charge was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 491192747 and the Open Access Publication Fund of Humboldt-Universität zu Berlin.Uncovering the relationships between neural circuits, behavior, and neural dysfunction may require rodent pose tracking. While open-source toolkits such as DeepLabCut have revolutionized markerless pose estimation using deep neural networks, the training process still requires human intervention for annotating key points of interest in video data. To further reduce human labor for neural network training, we developed a method that automatically generates annotated image datasets of rodent paw placement in a laboratory setting. It uses invisible but fluorescent markers that become temporarily visible under UV light. Through stroboscopic alternating illumination, adjacent video frames taken at 720 Hz are either UV or white light illuminated. After color filtering the UV-exposed video frames, the UV markings are identified and the paw locations are deterministically mapped. This paw information is then transferred to automatically annotate paw positions in the next white light-exposed frame that is later used for training the neural network. We demonstrate the effectiveness of our method using a KineWheel–DeepLabCut setup for the markerless tracking of the four paws of a harness-fixed mouse running on top of the transparent wheel with mirror. Our automated approach, made available open-source, achieves high-quality position annotations and significantly reduces the need for human involvement in the neural network training process, paving the way for more efficient and streamlined rodent pose tracking in neuroscience research.Peer Reviewe
Inwiefern standen Missionare den Indigenen in der Neuen Welt eigene Handlungsspielräume zu?
No full textPeer Reviewe
Eine Expert:innenstudie zur Untersuchung des didaktischen Vorgehens von Erwachsenenbildner:innen beim biografischen Arbeiten
No full textZahlreiche empirische Untersuchungen befassen sich mit Lernprozessen von Teilnehmenden bei der pädagogischen Biografiearbeit. Das Vorgehen von Erwachsenenbildner:innen wird jedoch seltener erforscht (vgl. Dausien 2011, S. 114). Die vorliegende Arbeit widmet sich eben jener Perspektive und untersucht explorativ, wie Erwachsenenbildner:innen die Reflexionsprozesse von Teilnehmenden an der pädagogischen Biografiearbeit initiieren und begleiten. Hierfür werden vier offene leitfadengestützte Expert:inneninterviews geführt und in Anlehnung an die Inhaltanalyse nach P. Mayring (2015) ausgewertet und sowohl induktiv als auch deduktiv Kategorien gebildet. Es wird das pädagogische Handeln der Befragten abgebildet und mit didaktischen Modellen und Prinzipien der Erwachsenenbildung verknüpft und so deren Relevanz für die Biografiearbeit hervorgehoben. Es wird gezeigt, welche Ziele die Expert:innen mit ihrer Arbeit verfolgen und wie sie ihr Handeln von einer therapeutischen Arbeit abgrenzen. Die Untersuchung stellt dar, dass die Erwachsenenbildner:innen einen Rahmen schaffen, in dem sich die Teilnehmenden entfalten und ihren Prozess des Reflektierens selber steuern können. In Begleitung der Expert:innen werden Erfahrungen und damit einhergehend Emotionen reflektiert und gedeutet, es wird deutlich, dass Emotionen und Lernen miteinander verbunden sind