204 research outputs found
A comparison of three data-poor stock assessment methods for the pink spiny lobster fishery in Mauritania
Several data-poor stock assessment methods have recently been proposed and applied
to data-poor fisheries around the world. The Mauritanian pink spiny lobster fishery
has a long history of boom and bust dynamics, with large landings, stock collapse,
and years-long fishery closures, all happening several times. In this study, we have
used catch, fishing efforts, and length-frequency data (LFD) obtained from the fishery
in its most recent period of activity, 2015–2019, and historical annual catch records
starting in 2006 to fit three data-poor stock assessment methods. These were the
length-based Bayesian (LBB) method, which uses LFD exclusively, the Catch-only MSY
(CMSY) method, using annual catch data and assumptions about stock resilience, and
generalised depletion models in the R package CatDyn combined with Pella-Tomlinson
biomass dynamics in a hierarchical inference framework. All threemethods presented the
stock as overfished. The LBB method produced results that were very pessimistic about
stock status but whose reliability was affected by non-constant recruitment. The CMSY
method and the hierarchical combination of depletion and Pella-Tomlinson biomass
dynamics produced more comparable results, such as similar sustainable harvest rates,
but both were affected by large statistical uncertainty. Pella-Tomlinson dynamics in
particular demonstrated stock experiencing wide fluctuations in abundance. In spite of
uncertain estimates, a clear understanding of the status of the stock as overfished and
in need of a biomass rebuilding program emerged as management-useful guidance to
steer exploitation of this economically significant resource into sustainability.info:eu-repo/semantics/publishedVersio
All functions are (locally) -harmonic (up to a small error) - and applications
The classical and the fractional Laplacians exhibit a number of similarities,
but also some rather striking, and sometimes surprising, structural
differences.
A quite important example of these differences is that any function
(regardless of its shape) can be locally approximated by functions with locally
vanishing fractional Laplacian, as it was recently proved by Serena Dipierro,
Ovidiu Savin and myself.
This informal note is an exposition of this result and of some of its
consequences
Compact Labelings For Efficient First-Order Model-Checking
We consider graph properties that can be checked from labels, i.e., bit
sequences, of logarithmic length attached to vertices. We prove that there
exists such a labeling for checking a first-order formula with free set
variables in the graphs of every class that is \emph{nicely locally
cwd-decomposable}. This notion generalizes that of a \emph{nicely locally
tree-decomposable} class. The graphs of such classes can be covered by graphs
of bounded \emph{clique-width} with limited overlaps. We also consider such
labelings for \emph{bounded} first-order formulas on graph classes of
\emph{bounded expansion}. Some of these results are extended to counting
queries
Robotic ubiquitous cognitive ecology for smart homes
Robotic ecologies are networks of heterogeneous robotic devices pervasively embedded in everyday environments, where they cooperate to perform complex tasks. While their potential makes them increasingly popular, one fundamental problem is how to make them both autonomous and adaptive, so as to reduce the amount of preparation, pre-programming and human supervision that they require in real world applications. The project RUBICON develops learning solutions which yield cheaper, adaptive and efficient coordination of robotic ecologies. The approach we pursue builds upon a unique combination of methods from cognitive robotics, machine learning, planning and agent- based control, and wireless sensor networks. This paper illustrates the innovations advanced by RUBICON in each of these fronts before describing how the resulting techniques have been integrated and applied to a smart home scenario. The resulting system is able to provide useful services and pro-actively assist the users in their activities. RUBICON learns through an incremental and progressive approach driven by the feed- back received from its own activities and from the user, while also self-organizing the manner in which it uses available sensors, actuators and other functional components in the process. This paper summarises some of the lessons learned by adopting such an approach and outlines promising directions for future work
Reversible Keap1 inhibitors are preferential pharmacological tools to modulate cellular mitophagy
Mitophagy orchestrates the autophagic degradation of dysfunctional mitochondria preventing their pathological accumulation and contributing to cellular homeostasis. We previously identified a novel chemical tool (hereafter referred to as PMI), which drives mitochondria into autophagy without collapsing their membrane potential (ΔΨm). PMI is an inhibitor of the protein-protein interaction (PPI) between the transcription factor Nrf2 and its negative regulator, Keap1 and is able to up-regulate the expression of autophagy-associated proteins, including p62/SQSTM1. Here we show that PMI promotes mitochondrial respiration, leading to a superoxide-dependent activation of mitophagy. Structurally distinct Keap1-Nrf2 PPI inhibitors promote mitochondrial turnover, while covalent Keap1 modifiers, including sulforaphane (SFN) and dimethyl fumarate (DMF), are unable to induce a similar response. Additionally, we demonstrate that SFN reverses the effects of PMI in co-treated cells by reducing the accumulation of p62 in mitochondria and subsequently limiting their autophagic degradation. This study highlights the unique features of Keap1-Nrf2 PPI inhibitors as inducers of mitophagy and their potential as pharmacological agents for the treatment of pathological conditions characterized by impaired mitochondrial quality control
ANTI-INFLAMMATORY AND ANTIOXIDANT ACTIVITIES OF METHANOL EXTRACTS AND ALKALOID FRACTIONS OF FOUR MEXICAN MEDICINAL PLANTS OF SOLANACEAE
Background: Methanol extracts and alkaloid fractions of different parts of four plant species belonging to Solanaceae family and used in Mexican traditional medicine were investigated for their total phenolic contents, anti-inflammatory and antioxidant properties.
Materials and Methods: The total phenolic compounds of each extract was determined according to the Folin-Ciocalteu method, while the in vitro radical scavenging activities of the extracts were assessed using the DPPH and ABTS radicals. The in vivo anti-inflammatory activity was determined using the TPA-induced mouse ear edema model.
Results: The methanol extracts contained the highest concentrations of phenolic compounds and also exhibited the best reducing power on the DPPH and ABTS radicals, in a concentration-dependent fashion. However, the anti-inflammatory activity did not follow the same trend, as some alkaloid fractions that showed low radical reducing power exhibited the strongest anti-inflammatory activity.
Conclusion: The methanol extract obtained from the flowers of Nicotiana glauca presented the best overall performance with the largest amount of phenolic compounds (111 µg garlic acid equivalents/g of extract), the best antioxidant activity (94.80% inhibition of DPPH and 97.57% of ABTS) and the highest anti-inflammatory activity (81.93% inhibition of the inflammatio
Expansion and Harvesting of hMSC-TERT
The expansion of human mesenchymal stem cells as suspension culture by means of spinner flasks and microcarriers, compared to the cultivation in tissue culture flasks, offers the advantage of reducing the requirements of large incubator capacities as well as reducing the handling effort during cultivation and harvesting. Nonporous microcarriers are preferable when the cells need to be kept in viable condition for further applications like tissue engineering or cell therapy. In this study, the qualification of Biosilon, Cytodex 1, Cytodex 3, RapidCell and P102-L for expansion of hMSC-TERT with an associated harvesting process using either trypsin, accutase, collagenase or a trypsin-accutase mixture was investigated. A subsequent adipogenic differentiation of harvested hMSC-TERT was performed in order to observe possible negative effects on their (adipogenic) differentiation potential as a result of the cultivation and harvesting method. The cultivated cells showed an average growth rate of 0.52 d-1. The cells cultivated on Biosilon, RapidCell and P102-L were harvested succesfully achieving high cell yield and vitalities near 100%. This was not the case for cells on Cytodex 1 and Cytodex 3. The trypsin-accutase mix was most effective. After spinner expansion and harvesting the cells were successfully differentiated to adipocytes
Identification of osteolineage cell-derived extracellular vesicle cargo implicated in hematopoietic support
Osteolineage cell-derived extracellular vesicles (EVs) play a regulatory role in hematopoiesis and have been shown to promote the ex vivo expansion of human hematopoietic stem and progenitor cells (HSPCs). Here, we demonstrate that EVs from different human osteolineage sources do not have the same HSPC expansion promoting potential. Comparison of stimulatory and non-stimulatory osteolineage EVs by next-generation sequencing and mass spectrometry analyses revealed distinct microRNA and protein signatures identifying EV-derived candidate regulators of ex vivo HSPC expansion. Accordingly, the treatment of umbilical cord blood-derived CD34+ HSPCs with stimulatory EVs-altered HSPC transcriptome, including genes with known roles in cell proliferation. An integrative bioinformatics approach, which connects the HSPC gene expression data with the candidate cargo in stimulatory EVs, delineated the potentially targeted biological functions and pathways during hematopoietic cell expansion and development. In conclusion, our study giv
The cysteine protease legumain is upregulated by vitamin D and regulates vitamin D metabolism
Legumain is a lysosomal asparaginyl endopeptidase involved in different biological processes and pathogenesis of several malignant and non-malignant diseases. Although an increasing number of proteins have been identified as substrates of legumain, the upstream mechanisms regulating the expression and function of legumain are not well-understood. Here, we provide in vitro and in vivo data showing that vitamin D3 (VD3) enhances legumain expression and function. In turn, legumain alters VD3 bioavailability, possibly through proteolytic cleavage of vitamin D binding protein (VDBP) and thereby playing a role in the regulation of VD3 metabolism. Active VD3 (1,25(OH)2D3) increased legumain expression, activity, and secretion in osteogenic cultures of human bone marrow stromal cells. Positive regulation of legumain was also observed in vivo, evidenced by increased expression of legumain mRNA in liver and spleen, as well as increased legumain activity in the kidneys, and increased level of circulating legumain in serum from mice treated with 25(OH)D3 (50 µg/kg, subcutaneous) for 8 days, as compared to vehicle-treated mice. We further showed that legumain cleaved VDBP forming a 45 kDa VDBP fragment in vitro when purified VDBP (55 kDa) was incubated with purified active legumain. In vivo, no VDBP cleavage was found in kidneys or liver from legumain deficient mice (Lgmn-/-), whereas VDBP was cleaved in wild type control mice (Lgmn+/+). Finally, legumain deficiency resulted in increased plasma levels of 25(OH)D3 and total VD3 and altered expression of key renal enzymes involved in VD3 metabolism (CYP24A1 and CYP27B1). Taken together, our data suggest existence of a regulatory interplay between VD3 and legumain
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Supersonic flow of non-ideal fluids in nozzles: An application of similitude theory and lessons for ORC turbine design and flexible use considering system performance
A significant improvement in the economy-of-scale of small-scale organic Rankine cycle (ORC) systems can arise from the appropriate design of components that can be manufactured in large volumes and implemented flexibly into a wide range of systems and potential applications. This, in turn, requires accurate predictions of component performance that can capture variations in the cycle conditions, parameters or changes to the working fluid. In this paper previous work investigating a modified similitude theory used to predict the performance of subsonic ORC turbines is extended to analyse the supersonic flow of organic fluids within 2D converging-diverging nozzles. Two nozzles are developed using a minimum length method of characteristics design model coupled to REFPROP. These are designed for R245fa and Toluene as working fluids with nozzle exit Mach numbers of 1.4 and 1.7 respectively. First, the nozzle performance is confirmed using CFD simulations, and then further CFD simulations are performed to evaluate the performance of the same nozzles over a range of different inlet conditions and with different working fluids. The CFD simulations are compared to predictions made using the original and modified similitude theories, and also to predictions made by conserving the Prandtl-Meyer function for the different operating conditions. The results indicate that whilst the modified similitude model does not accurately predict nozzle performance, conserving the Prandtl-Meyer function allows to predict the nozzle outlet Mach number to within 2% providing there is not a significant change in the polytropic index. Finally, the effect of working fluid replacement on the ORC system is discussed, and preliminary results demonstrate the possibility of matching a particular turbine to a heat source through optimal working fluid selection
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