468 research outputs found
Advances in Environmental Informatics: Integration of Discrete Event Simulation Methodology with ecological Material Flow Analysis for Modelling eco-efficient Systems
AbstractIn the first section we provide a short review of the rather young field of Environmental Informatics. We argue that Environmental Informatics methods and tools are powerful means in environmental information processing for supporting environmental protection and sustainable development. In the second part we introduce an integrated approach for modeling ecoefficient systems such as complex production systems under an economic as well as an ecological view. This modeling approach allows for the implementation of a combined model representing material and energy flows and bottle necks in machine capacities at the same time (instead of using two different models with different software tools). Finally present a case study from a real waver production site as a proof of concept for this substantial contribution to Environmental Informatics
Advances in Environmental Informatics: Integration of Discrete Event Simulation Methodology with ecological Material Flow Analysis for Modelling eco-efficient Systems
AbstractIn the first section we provide a short review of the rather young field of Environmental Informatics. We argue that Environmental Informatics methods and tools are powerful means in environmental information processing for supporting environmental protection and sustainable development. In the second part we introduce an integrated approach for modeling ecoefficient systems such as complex production systems under an economic as well as an ecological view. This modeling approach allows for the implementation of a combined model representing material and energy flows and bottle necks in machine capacities at the same time (instead of using two different models with different software tools). Finally present a case study from a real waver production site as a proof of concept for this substantial contribution to Environmental Informatics
Do actively managed funds perform better than index funds?: a test in the Canadian market
Actuality of the study: Mutual funds are a favourite investment product among many investors. They provide a simple means of diversification, especially for those with smaller amounts of capital, and the popularity of mutual funds has increased with the success of the marketing efforts behind them. Purpose: This study evaluates the performance of actively managed and index mutual funds within the Canadian equities market. Findings: As index investing has increased in popularity, and other markets have become more connected and open, there is a need for research on equity mutual funds in countries outside the US. Originality / Value: The majority of previous research on index funds and actively managed mutual funds is focused on the US market and related indexes such as the S&P 500. Practical implications: This study suggests that, on average, active funds in Canada fail to beat their benchmarks net (but not gross) of the common fee or management expense ratio. Surprisingly, this research finds no positive relationship between higher fees and better gross performance. Actively managed funds also have poorer performance over the long term. This study finds that investors would be better off purchasing low cost index funds as they provide a more secure return. Future research: This study endorses research on other markets with inclusion of additional variables in order to explain gross performance and secure returns
Timescale-invariant representation of acoustic communication signals by a bursting neuron
Acoustic communication often involves complex sound motifs in which the relative durations of individual elements, but not their absolute durations, convey meaning. Decoding such signals requires an explicit or implicit calculation of the ratios between time intervals. Using grasshopper communication as a model, we demonstrate how this seemingly difficult computation can be solved in real time by a small set of auditory neurons. One of these cells, an ascending interneuron, generates bursts of action potentials in response to the rhythmic syllable-pause structure of grasshopper calls. Our data show that these bursts are preferentially triggered at syllable onset; the number of spikes within the burst is linearly correlated with the duration of the preceding pause. Integrating the number of spikes over a fixed time window therefore leads to a total spike count that reflects the characteristic syllable-to-pause ratio of the species while being invariant to playing back the call faster or slower. Such a timescale-invariant recognition is essential under natural conditions, because grasshoppers do not thermoregulate; the call of a sender sitting in the shade will be slower than that of a grasshopper in the sun. Our results show that timescale-invariant stimulus recognition can be implemented at the single-cell level without directly calculating the ratio between pulse and interpulse durations
Bibliographieren – ... aber wie?
Bibliographische Angaben dienen zwei Zielen: Sie sollen die verwendete Literatur zweifelsfrei identifizieren und sie dadurch (wieder-)auffindbar machen, und sie sollen jede direkte und indirekte Übernahme fremden geistigen Eigentums eindeutig als solche kennzeichnen und die verwendeten Quellen offen legen. Beides ist unabdingbar für korrektes wissenschaftliches Arbeiten. Diese Anleitung versteht sich weniger als eine (fachspezifische) Vorschrift – schon gar nicht als die einzig Richtige! – sondern vielmehr als eine allgemeine Einführung in die Prinzipien des Bibliographierens, anhand derer man sich seinen eigenen Stil erarbeiten kann, der für die eigenen Belange angemessen und praktisch ist. Wichtiger als das sklavische Festhalten an bestimmten Formatierungsvorschriften ist es, ein klares, einheitliches und eingängiges Schema zu verwenden, das alle wichtigen Informationen zur Verfügung stellt und auch in seiner Systematik für Dritte verständlich ist
An Uncharged Amine in the Transition State of the Ribosomal Peptidyl Transfer Reaction
The ribosome has an active site comprised of RNA that catalyzes peptide bond formation. To understand how RNA promotes this reaction requires a detailed understanding of the chemical transition state. Here, we report the Brønsted coefficient of the α-amino nucleophile with a series of puromycin derivatives. Both 50S subunit- and 70S ribosome-catalyzed reactions displayed linear free-energy relationships with slopes close to zero under conditions where chemistry is rate limiting. These results indicate that, at the transition state, the nucleophile is neutral in the ribosome-catalyzed reaction, in contrast to the substantial positive charge reported for typical uncatalyzed aminolysis reactions. This suggests that the ribosomal transition state involves deprotonation to a degree commensurate with nitrogen-carbon bond formation. Such a transition state is significantly different from that of uncatalyzed aminolysis reactions in solution
Top-Down Characterisation of an Antimicrobial Sanitiser, Leading from Quenchers of Efficacy to Mode of Action
We developed a top-down strategy to characterise an antimicrobial, oxidising sanitiser, which has diverse proposed applications including surface-sanitisation of fresh foods, and with benefits for water resilience. The strategy involved finding quenchers of antimicrobial activity then antimicrobial mode of action, by identifying key chemical reaction partners starting from complex matrices, narrowing down reactivity to specific organic molecules within cells. The sanitiser electrolysed-water (EW) retained partial fungicidal activity against the food-spoilage fungus Aspergillus niger at high levels of added soils (30–750 mg mL-1), commonly associated with harvested produce. Soil with high organic load (approx. 98 mg g-1) gave stronger EW inactivation. Marked inactivation by a complex organics mix (YEPD medium) was linked to its protein-rich components. Addition of pure proteins or amino acids (≤1 mg mL-1) fully suppressed EW activity. Mechanism was interrogated further with the yeast model, corroborating marked suppression of EW action by the amino acid methionine. Pre-culture with methionine increased resistance to EW, sodium hypochlorite, or chlorine-free ozonated water. Overexpression of methionine sulfoxide reductases (which reduce oxidised methionine) protected against EW. Fluoroprobe-based analyses indicated that methionine and cysteine inactivate free chlorine species in EW. Intracellular methionine oxidation can disturb cellular FeS-clusters and we showed that EW treatment impairs FeS-enzyme activity. The study establishes the value of a top-down approach for multi-level characterisation of sanitiser efficacy and action. The results reveal proteins and amino acids as key quenchers of EW activity and, among the amino acids, the importance of methionine oxidation and FeS-cluster damage for antimicrobial mode-of-action
Long-term soil water limitation and previous tree vigor drive local variability of drought-induced crown dieback in Fagus sylvatica.
Ongoing climate warming is increasing evapotranspiration, a process that reduces plant-available water and aggravates the impact of extreme droughts during the growing season. Such an exceptional hot drought occurred in Central Europe in 2018 and caused widespread defoliation in mid-summer in European beech (Fagus sylvatica L.) forests. Here, we recorded crown damage in 2021 in nine mature even-aged beech-dominated stands in northwestern Switzerland along a crown damage severity gradient (low, medium, high) and analyzed tree-ring widths of 21 mature trees per stand. We aimed at identifying predisposing factors responsible for differences in crown damage across and within stands such as tree growth characteristics (average growth rates and year-to-year variability) and site-level variables (mean canopy height, soil properties). We found that stand-level crown damage severity was strongly related to soil water availability, inferred from tree canopy height and plant available soil water storage capacity (AWC). Trees were shorter in drier stands, had higher year-to-year variability in radial growth, and showed higher growth sensitivity to moisture conditions of previous late summer than trees growing on soils with sufficient AWC, indicating that radial growth in these forests is principally limited by soil water availability. Within-stand variation of post-drought crown damage corresponded to growth rate and tree size (diameter at breast height, DBH), i.e., smaller and slower-growing trees that face more competition, were associated with increased crown damage after the 2018 drought. These findings point to tree vigor before the extreme 2018 drought (long-term relative growth rate) as an important driver of damage severity within and across stands. Our results suggest that European beech is less likely to be able to cope with future climate change-induced extreme droughts on shallow soils with limited water retention capacity
Using synthetic biological parts and microbioreactors to explore the protein expression characteristics of Escherichia coli
Synthetic
biology has developed numerous parts for the precise
control of protein expression. However, relatively little is known
about the burden these place on a host, or their reliability under
varying environmental conditions. To address this, we made use of
synthetic transcriptional and translational elements to create a combinatorial
library of constructs that modulated expression strength of a green
fluorescent protein. Combining this library with a microbioreactor
platform, we were able to perform a detailed large-scale assessment
of transient expression and growth characteristics of two <i>Escherichia coli</i> strains across several temperatures. This
revealed significant differences in the robustness of both strains
to differing types of protein expression, and a complex response of
transcriptional and translational elements to differing temperatures.
This study supports the development of reliable synthetic biological
systems capable of working across different hosts and environmental
contexts. Plasmids developed during this work have been made publicly
available to act as a reference set for future research
Evolving challenges and strategies for fungal control in the food supply chain
Fungi that spoil foods or infect crops can have major socioeconomic impacts, posing threats to food security. The strategies needed to manage these fungi are evolving, given the growing incidence of fungicide resistance, tightening regulations of chemicals use and market trends imposing new food-preservation challenges. For example, alternative methods for crop protection such as RNA-based fungicides, biocontrol, or stimulation of natural plant defences may lessen concerns like environmental toxicity of chemical fungicides. There is renewed focus on natural product preservatives and fungicides, which can bypass regulations for ‘clean label’ food products. These require investment to find effective, safe activities within complex mixtures such as plant extracts. Alternatively, physical measures may be one key for fungal control, such as polymer materials which passively resist attachment and colonization by fungi. Reducing or replacing traditional chlorine treatments (e.g. of post-harvest produce) is desirable to limit formation of disinfection by-products. In addition, the current growth in lower sugar food products can alter metabolic routing of carbon utilization in spoilage yeasts, with implications for efficacy of food preservatives acting via metabolism. The use of preservative or fungicide combinations, while involving more than one chemical, can reduce total chemicals usage where these act synergistically. Such approaches might also help target different subpopulations within heteroresistant fungal populations. These approaches are discussed in the context of current challenges for food preservation, focussing on pre-harvest fungal control, fresh produce and stored food preservation. Several strategies show growing potential for mitigating or reversing the risks posed by fungi in the food supply chain
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