Discrimination learning with variable stimulus 'salience'.

BACKGROUND: In nature, sensory stimuli are organized in heterogeneous combinations. Salient items from these combinations 'stand-out' from their surroundings and determine what and how we learn. Yet, the relationship between varying stimulus salience and discrimination learning remains unclear. PRESENTATION OF THE HYPOTHESIS: A rigorous formulation of the problem of discrimination learning should account for varying salience effects. We hypothesize that structural variations in the environment where the conditioned stimulus (CS) is embedded will be a significant determinant of learning rate and retention level. TESTING THE HYPOTHESIS: Using numerical simulations, we show how a modified version of the Rescorla-Wagner model, an influential theory of associative learning, predicts relevant interactions between varying salience and discrimination learning. IMPLICATIONS OF THE HYPOTHESIS: If supported by empirical data, our model will help to interpret critical experiments addressing the relations between attention, discrimination and learning

Analysis of microbial populations in Rusitec fermenters fed diets of variable composition

Trabajo presentado al : Joint Annual Meeting. ADSA-ASAS. Orlando Florida (USA), julio, 2015. T485Fermenters are widely used to study ruminal fermentation, but infonnation on microbial populations developing in fermenters over the incubation period is limited. Four Rusitec fermenters were fed 2 diets representative of those administered to dairy sheep (DAI; 50:50 alfalfa hay:concentrate) and fattening lambs (FAT; 15:85 barley straw:concentrate) in a crossover design with 2 14-d incubation periods to assess the evolution of the microbial populations. There were 4 fermenters per diet. The fermenters received daily 30 g of diet DM and samples from liquid (LIQ) and solid (SOL) digesta were taken on d 3, 8 and 14, and stored frozen at-80ªC until DNA extraction. Concentrations ofbacterial and protozoal DNA and relative abundance offungi and methanogenic archaea to total bacteria! DNA concentration were detennined by real time PCR using previously validated primers and DNA from bacteria and protozoa isolated from sheep rumen as standards. Data were analyzed as a mixed model with repeated measnres using the PROC MlXED of SAS. The model included diet, incubation nm, time, and diet x tin1e as fixed effects, and fermenter as a random effect. Diet x sampling time interactions (P > 0.05) were detected for bacteria! and protozoal DNA concentrations in both digesta phases. The bacteria! DNA concentrations in SOL did not change (P = 0.002) over the incubation period, whereas concentrations in LIQ increased (P < 0.001) by 1.5 and 1.8 times for DAI and FAT diets by the end ofthe incubation, respectively. Protozoal DNA concentrations on d 14 were 37.8 and 8.0 times lower (P < 0.001; means across diets) than those on d 3 for SOL and LIQ phases, respectively. Relative abundance offungi decreased (P < 0.05) with time in both phases, and that ofmethanogenic archaea remain unchanged in LIQ and increased (P = 0.021) in SOL. Concentration of bacteria! and protozoal DNA and the relative abundance of methanogenic archaea were greater in the fermenters fed the DAI diet (P < 0.05) compared with FAT diet. The results show that microbial populations in Rusitec fermenters are affected by the incubated diet and change over the incubation periodPeer reviewe

Chemical composition, physicochemical evaluation and sensory analysis of yogurt added with extract of polyphenolic compounds from Quercus crassifolia oak bark

Introduction: A diet high in calories and saturated fats has been associated with health problems that have been increasing worldwide. Therefore, it is required to increase the number of formulated foods that generate well-being to health. Yogurt is a widely consumed food by all sectors of the population and it can be used as a vehicle to incorporate bioactive compounds. The phenolic compounds present in forest residues, such as those from oak bark, can be used and incorporated into yogurt, to increase its benefits as a functional food. Objective: The objective of this study was to develop a multifunctional yogurt enriched with vegetable oil (2.3% w/w) as a source of omega 6 and 3 and adding nanocapsules (24.5% w/w) of an extract of oak bark from Quercus crassifolia, rich in in phenolic compounds and high antioxidant capacity. Methods: Three yogurt formulations were prepared: F1: yogurt was made with non-fat milk, used as a control, F2: yogurt was prepared with non-fat milk and added with vegetable palm oil, and F3: non-fat yogurt was added with vegetable oil and nanoencapsulated oak bark phenolic extract. The yogurts were characterized in their chemical composition, microbiological analysis, and sensory analysis. Results: The multifunctional product F3 and product F2 presented lactic acid bacteria in concentration of 3.01X106 and 4.73x106, respectively, preserving characteristics of probiotic food. Product F3 presented low levels of syneresis (7.34%) and it was significantly different from the control yogurt (9.01%). The viscosity increased from 150 cP in the control yogurt to 341 cP in F3, due to the increase in the concentrations of solids by nanoencapsulating the phenolic. The wall material used for nanoencapsulation was sodium caseinate and mantodextrin. However, this increase in viscosity did not affect the sensory evaluation of the product. There were no significant differences between the control yogurt and the F2 and F3 products. Conclusion: A yogurt added with vegetable oil and nanoencapsulated oak bark phenolic extract was obtained. It was enhanced by the presence of probiotics, bioactive compounds, and essential fatty acids, and then evaluated and accepted by a sensory panel. Nanoencapsulation is a viable alternative to mask the characteristic astringent taste of phenolic compounds because it was not detected by the panelists

An overview of rice cultivation in Spain and the management of herbicide-resistant weeds

Spain is the second highest rice-producing country in the European Union, with approximately 105, 000 ha used to grow this crop. The major rice-producing regions in Spain are Andalusia, Extremadura, Catalonia, and Valencia, followed by Aragon and Navarre. The main soil texture throughout Spanish rice areas is silty clay loam, with alkaline soils (pH > 7.5)—except in the Extremadura area (pH = 5.5–6)—and a low organic matter content. Water quality in terms of salinity is acceptable, although in some coastal rice areas salinity issues occasionally appear to be a determining factor for high yield achievement. According to a survey carried out on farmers and technicians, the most problematic weeds found in rice crops today in Spain are Echinochloa spp., Leptochloa spp., and Cyperus difformis. Most of the currently authorized herbicides can be classified according to two modes of action: ALS-inhibiting and ACCase-inhibiting. Repeated field applications of herbicides with the same mode of action have resulted in the selection of herbicide-resistant weeds. At present, resistance has been confirmed in different regions of Spain to ALS inhibitors in Echinochloa spp., Leptochloa spp., and Cyperus difformis, and to ACCase inhibitors in Echinochloa spp. and Leptochloa spp. The mechanism of resistance in these species is a mutation in the target site of these herbicides. Several mutations have been found in the ALS gene, both in Echinochloa spp. and Cyperus difformis, distributed in the different rice-growing regions considered in this work. ACCase gene mutations have been mainly found in Leptochloa spp. individuals from Extremadura and Valencia. These different mutations have resulted in different patterns of cross-resistance to ALS- and ACCase-inhibiting herbicides. It is likely that the repeated use of these two modes of action in rice will result in the evolution of more resistant weed populations. The possible availability of new herbicides with alternative modes of action in a short space of time seems very limited, suggesting the need for a more appropriate use of the available alternative strategies (crop rotation, dry sowing, manual weeding, etc.). This work presents a review of the main characteristics of rice cultivation in Spain, emphasizing the current problems in this crop and the management of herbicide-resistant weeds. © 2021 by the authors

Probing the phase transition to a coherent 2D Kondo Lattice

Kondo lattices are systems with unusual electronic properties that stem from strong electron correlation, typically studied in intermetallic 3D compounds containing lanthanides or actinides. Lowering the dimensionality of the system enhances the role of electron correlations providing a new tuning knob for the search of novel properties in strongly correlated quantum matter. The realization of a 2D Kondo lattice by stacking a single-layer Mott insulator on a metallic surface is reported. The temperature of the system is steadily lowered and by using high-resolution scanning tunneling spectroscopy, the phase transition leading to the Kondo lattice is followed. Above 27 K the interaction between the Mott insulator and the metal is negligible and both keep their original electronic properties intact. Below 27 K the Kondo screening of the localized electrons in the Mott insulator begins and below 11 K the formation of a coherent quantum electronic state extended to the entire sample, i.e., the Kondo lattice, takes place. By means of density functional theory, the electronic properties of the system and its evolution with temperature are explained. The findings contribute to the exploration of unconventional states in 2D correlated materialsThis work was supported by Ministerio de Ciencia, Innovación y Universidades through grants, PID2021-128011NB-I00 and PID2019-105458RBI00. Ministerio de Ciencia e Innovación and Comunidad de Madrid through grants “Materiales Disruptivos Bidimensionales (2D)” (MAD2DCM)-UAM and “Materiales Disruptivos Bidimensionales (2D)” (MAD2DCM)-IMDEA-NC funded by the Recovery, Transformation and Resilience Plan, and by NextGenerationEU from the European Union. Comunidad de Madrid through grants NMAT2D-CM P20128/NMT-4511 and NanoMagCost. IMDEA Nanoscience acknowledges support from the “‘Severo Ochoa”’ Programme for Centres of Excellence in R&D CEX2020-001039-S. IFIMAC acknowledges support from the “‘María de Maeztu”’ Programme for Units of Excellence in R&D CEX2018-000805-M. M.G. thanks Ministerio de Ciencia, Innovación y Universidades “Ramón y Cajal” Fellowship RYC2020-029317-I. Allocation of computing time at the Centro de Computación Científica at the Universidad Autónoma de Madrid, the CINECA Consortium INF16_npqcd Project, and Newton HPCC Computing Facility at the University of Calabria (MP

Host preferences and differential contributions of deciduous tree species shape mycorrhizal species richness in a mixed Central European forest

Mycorrhizal species richness and host ranges were investigated in mixed deciduous stands composed of Fagus sylvatica, Tilia spp., Carpinus betulus, Acer spp., and Fraxinus excelsior. Acer and Fraxinus were colonized by arbuscular mycorrhizas and contributed 5% to total stand mycorrhizal fungal species richness. Tilia hosted similar and Carpinus half the number of ectomycorrhizal (EM) fungal taxa compared with Fagus (75 putative taxa). The relative abundance of the host tree the EM fungal richness decreased in the order Fagus > Tilia >> Carpinus. After correction for similar sampling intensities, EM fungal species richness of Carpinus was still about 30–40% lower than that of Fagus and Tilia. About 10% of the mycorrhizal species were shared among the EM forming trees; 29% were associated with two host tree species and 61% with only one of the hosts. The latter group consisted mainly of rare EM fungal species colonizing about 20% of the root tips and included known specialists but also putative non-host associations such as conifer or shrub mycorrhizas. Our data indicate that EM fungal species richness was associated with tree identity and suggest that Fagus secures EM fungal diversity in an ecosystem since it shared more common EM fungi with Tilia and Carpinus than the latter two among each other