Evidence of conditioned behavior in amoebae De la Fuente, Ildefonso M; Bringas, Carlos; Malaina, Iker ...
Nature communications,
08/2019, Letnik:
10, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Associative memory is the main type of learning by which complex organisms endowed with evolved nervous systems respond efficiently to certain environmental stimuli. It has been found in different ...multicellular species, from cephalopods to humans, but never in individual cells. Here we describe a motility pattern consistent with associative conditioned behavior in the microorganism Amoeba proteus. We use a controlled direct-current electric field as the conditioned stimulus, and a specific chemotactic peptide as the unconditioned stimulus. The amoebae are capable of linking two independent past events, generating persistent locomotion movements that can prevail for 44 min on average. We confirm a similar behavior in a related species, Metamoeba leningradensis. Thus, our results indicate that unicellular organisms can modify their behavior during migration by associative conditioning.
Display omitted
•A one-tube solar receiver containing upward particle suspension was operated on-sun.•Outlet powder temperatures up to 750°C were obtained experimentally.•Absorber wall temperatures ...were measured accurately.•Temperature measurements reveal a powder reflux mode inside the vertical tube.•Wall-to-suspension heat transfer coefficients were found in the range 420–1100W/m2K.
A dense particles suspension was tested in a high temperature single tube on-sun solar receiver at the French National Centre for Scientific Research (in French: Centre National de la Recherche Scientifique=CNRS) solar facility. A powder outlet temperature as high as 750°C was measured thus proving the capacity of this heat transfer fluid concept to reach high operating temperatures. The wall-to-suspension heat transfer coefficient was calculated on the basis of detailed temperature measurements and accounting for the strong recirculation phenomena occurring at the tube wall. It ranges from 420W/m2K to 1100W/m2K for a solid mass flux of 10kg/m2s and 45kg/m2s, respectively. The temperature increase positively influences the heat transfer coefficient; with a 30% increase measured between ∼200°C and 600°C average powder temperatures. Finally, a correlation is proposed to predict the dependency of the heat transfer coefficient and solid mass flux.
During the last decade, some changes in the epidemiology of invasive infections have been reported; however, specific studies with patient-level data are scarce. The aim of this study was to describe ...and evaluate the epidemiologic changes in bloodstream infections (BSI) during the last decade in Andalucía, Spain.
Data from two prospective cohorts of BSI in adults with the same methodology performed 10 years apart in 11 hospitals (eight tertiary and three community) in Andalucía, Spain, were compared; the 2006–7 cohort study was performed between October 2006 and March 2007, and the 2016–17 cohort study was performed between October 2016 and March 2017. Population-based incidence rates were calculated and extrapolated for 1 year. Relative risk ratios were calculated between the 2 periods. Multivariate analyses were performed by logistic regression.
Overall, 1262 episodes of BSI were included, 563 (44.6%) in 2006–7 and 699 (55.3%) in 2016–17. Multivariate models selected the following changes in patients' features in 2016–17, after controlling for type of acquisition: higher age (odds ratio (OR) = 1.02; 95% confidence interval CI 1.01–1.03), lower urinary catheter (OR = 0.37; 95% CI, 0.26–0.48) and lower Pitt score (OR = 0.76; 95% CI, 0.71–0.82). Adjusted estimations considering patients' features and exposure to procedures showed a reduction in coagulase-negative staphylococci (OR = 0.47; 95% CI, 0.32–0.69), and an increase in Proteus spp. (OR = 3.12; 95% CI, 1.18–8.23) and Candida spp. (OR = 3.01; 95% CI, 1.03–8.86).
We found relevant epidemiologic changes in BSI in our area, including rates, frequency of acquisition types, changes in patient's profiles and aetiologic agents.
β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) were used to prepare insoluble polymers using epichlorohydrin as a cross-linking agent and the azo dye Direct Red 83:1 was used as ...target adsorbate. The preliminary study related to adsorbent dosage, pH, agitation or dye concentration allowed us to select the best conditions to carry out the rest of experiments. The kinetics was evaluated by Elovich, pseudo first order, pseudo second order, and intra-particle diffusion models. The results indicated that the pseudo second order model presented the best fit to the experimental data, indicating that chemisorption is controlling the process. The results were also evaluated by Freundlich, Langmuir and Temkin isotherms. According to the determination coefficient (
²), Freunlich gave the best results, which indicates that the adsorption process is happening on heterogeneous surfaces. One interesting parameter obtained from Langmuir isotherm is
(maximum adsorption capacity). This value was six times higher when a β-CDs-EPI polymer was employed. The cross-linked polymers were fully characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA). Also, morphology and particle size distribution were both assessed. Under optimized conditions, the β-CDs-EPI polymer seems to be a useful device for removing Direct Red 83:1 (close 90%), from aqueous solutions and industrial effluents. Complementarily, non-adsorbed dye was photolyzed by a pulsed light driven advanced oxidation process. The proposed methodology is environmental and economically advantageous, considering the point of view of a sustainable recycling economy in the textile dyeing process.
Abstract
As the SARS-CoV-2 has spread and the pandemic has dragged on, the virus continued to evolve rapidly resulting in the emergence of new highly transmissible variants that can be of public ...health concern. The evolutionary mechanisms that drove this rapid diversity are not well understood but neutral evolution should open the first insight. The neutral theory of evolution states that most mutations in the nucleic acid sequences are random and they can be fixed or disappear by purifying selection. Herein, we performed a neutrality test to better understand the selective pressures exerted over SARS-CoV-2 spike protein from homologue proteins of
Betacoronavirus
, as well as to the spikes from human clinical isolates of the virus. Specifically, Tyr and Asn have higher occurrence rates on the Receptor Binding Domain (RBD) and in the overall sequence of spike proteins of
Betacoronavirus
, whereas His and Arg have lower occurrence rates. The in vivo evolutionary phenomenon of SARS-CoV-2 shows that Glu, Lys, Phe, and Val have the highest probability of occurrence in the emergent viral particles. Amino acids that have higher occurrence than the expected by the neutral control, are favorable and are fixed in the sequence while the ones that have lower occurrence than expected, influence the stability and/or functionality of the protein. Our results show that most unique mutations either for SARS-CoV-2 or its variants of health concern are under selective pressures, which could be related either to the evasion of the immune system, increasing the virus’ fitness or altering protein – protein interactions with host proteins. We explored the consequences of those selected mutations in the structure and protein – protein interaction with the receptor. Altogether all these forces have shaped the spike protein and the continually evolving variants.
The effect of osmotic dehydration pretreatment (25% NaCl, 80 °C, 180 min) on the mass transfer and morphometric characteristics of white mushroom pilei during convective drying (50, 65 and 80 °C, ...2.0 m/s) is investigated. Samples were characterized during process in terms of their cross-sectional area, inner-to-outer radius ratio and roundness by using image analysis. Drying data were modeled by an unsteady state 2D-diffusion model where product was considered as a hemispherical shell. A novel shrinkage algorithm was applied to move inner and outer radial boundaries at a different rate to reduce geometry mismatch during simulation and reproduce both the change in size and proportions of product. Results indicated that OD pretreatment affected mass transfer characteristics of product by significantly lowering (p < 0.05) estimated water diffusivities in comparison to those observed in fresh samples (1.1–2.9 × 10−10 m2/s vs. 2.6–7.2 × 10−10 m2/s).
•Fresh and osmodehydrated white mushroom pilei were air-dried.•Size and shape changes of product were evaluated by image analysis.•Radii move at a different rate, flattening sample, in shrinkage algorithm.•Estimated water diffusivities are lower in osmodehydrated product.•Product deformation is reduced by the osmotic dehydration pretreatment.
Hand, foot and mouth disease (HFMD) is a childhood illness frequently caused by genotypes belonging to the enterovirus A species, including coxsackievirus (CV)-A16 and enterovirus (EV)-71. Between ...2010 and 2012, several outbreaks and sporadic cases of HFMD occurred in different regions of Spain. The objective of the present study was to describe the enterovirus epidemiology associated with HFMD in the country. A total of 80 patients with HFMD or atypical rash were included. Detection and typing of the enteroviruses were performed directly in clinical samples using molecular methods. Enteroviruses were detected in 53 of the patients (66%). CV-A6 was the most frequent genotype, followed by CV-A16 and EV-71, but other minority types were also identified. Interestingly, during almost all of 2010, CV-A16 was the only causative agent of HFMD but by the end of the year and during 2011, CV-A6 became predominant, while CV-A16 was not detected. In 2012, however, both CV-A6 and CV-A16 circulated. EV-71 was associated with HFMD symptoms only in three cases during 2012. All Spanish CV-A6 sequences segregated into one major genetic cluster together with other European and Asian strains isolated between 2008 and 2011, most forming a particular clade. Spanish EV-71 strains belonged to subgenogroup C2, as did most of the European sequences circulated. In conclusion, the recent increase of HFMD cases in Spain and other European countries has been due to a larger incidence of circulating species A enteroviruses, mainly CV-A6 and CV-A16, and the emergence of new genetic variants of these viruses.
An annual thermal evaluation of a ventilated roof (VR) for energy-saving purposes in two Mexican cities with warm weather is presented. It was developed a numerical code based on the global energy ...balance method to predict the thermal behavior of the VR. The code was verified, and it showed a good agreement with data reported in the literature. Weather data of the coldest and warmest days of each month for the two cities were provided to the numerical code as boundary conditions to perform the simulations. Thus, to quantify the benefits of using the VR, it was compared with a conventional roof (CR). The results showed that the implementation of VR significantly reduces the annual total heat gain by up to 50 and 60% for the climates BWh and Aw, respectively. In addition, it was found that for both climates the payback period of VR is smaller than a year and a half. In this way, VR is a passive technology with high potential to reduce the energy consumption for thermal comfort in buildings at a relatively low cost.
•A Ventilated Roof (VR) System was evaluated under warm weather conditions of Mexico.•The implementation of VR significantly reduces the annual thermal load by up to 60%.•For a room of 9 m2, the payback period of the VR is smaller than a year and a half.
PDF
