It has been suggested that external and/or internal limitations paradoxically may lead to superior learning, that is, the concepts of starting small and less is more (Elman, ; Newport, ). In this ...paper, we explore the type of incremental ordering during training that might help learning, and what mechanism explains this facilitation. We report four artificial grammar learning experiments with human participants. In Experiments 1a and 1b we found a beneficial effect of starting small using two types of simple recursive grammars: right‐branching and center‐embedding, with recursive embedded clauses in fixed positions and fixed length. This effect was replicated in Experiment 2 (N = 100). In Experiment 3 and 4, we used a more complex center‐embedded grammar with recursive loops in variable positions, producing strings of variable length. When participants were presented an incremental ordering of training stimuli, as in natural language, they were better able to generalize their knowledge of simple units to more complex units when the training input “grew” according to structural complexity, compared to when it “grew” according to string length. Overall, the results suggest that starting small confers an advantage for learning complex center‐embedded structures when the input is organized according to structural complexity.
•A novel kinetic model for IBE fermentation was proposed.•The proposed structure correlates sporulation and solventogenesis with pH.•The structure includes an in-line equation for pH dynamics.•The ...proposed model attains a R2 = 0.9931 and a p-value <0.001.•Shows predictive IBE capabilities for both initial and controlled pH manipulation.
This work makes use of the so-called phenomenological non-structured modelling approach to propose a novel mathematical structure for the description and prediction of the pH effect over an Isopropanol-Butanol-Ethanol (IBE) fermentation system by Clostridium acetobutylicum pIPA3-Cm2, which includes both an in-line approximation of the pH of the culture medium and also novel expressions to reflect its real time effect over the biomass growth and metabolic response in an attempt to generate a base for the development of process intensification strategies for said fermentation system for biofuel production purposes.
The proposed model attained a correlation index R2 = 0.9931 and a p-value <0.001 versus experimental data reported by Lee at al. (2012), predicting a total of 20.1617 kg m−3 of IBEs with a yield of 0.3341 kgIBE kgSg−1 after 42 h of batch fermentation. Additionally, both the proposed parameters for critical and optimal pH (pHc = 3.4977; pHop = 6.5) and simulation results based on the equation proposed for the modelling of the pH dynamic were consistent with experimental reports for both ABE and IBE fermentation systems under a wide array of operational conditions.
A combined experimental and numerical approach is used to extract information on the kinetics of ion evaporation from the region of high electric field around the tip of a Taylor cone of the neutral ...solvent propylene carbonate (PC) mixed with two ionic liquids. On the numerical side, the electric field on the surface of the liquid is computed in the absence of evaporation by solving the electrohydrodynamic problem in this region within the framework of the leaky dielectric model. These computations justify the approximate (2% max error) scaling Emax = β Ek for the maximum electric field on the surface, with Ek = γ1/2 ϵ0−2/3 (K/Q)1/6 for 0.111 < K < 0.888 S m−1 and a numerical value of β ≈ 0.76. Here γ is the surface tension of PC, ϵ0 is the electrical permittivity of vacuum, and K and Q are the liquid electrical conductivity and flow rate. On the experimental side, 16 different propylene carbonate solutions with either of the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4) or EMI-bis(trifluoro-methylsulfonyl)imide (EMI-Im) are electrosprayed in a vacuum from a single Taylor cone, and their emissions of charged drops and ions are analysed by time-of-flight mass spectrometry at varying liquid flow rates Q. The sprays contain exclusively drops at large Q, both for small and for large electrical conductivities K, but enter a mixed ion–drop regime at sufficiently large K and small Q. Interestingly, the mixtures containing 10% and 15% (vol) EMI-Im exhibit no measurable ion currents at high Q, but approach a purely ionic regime (almost no drops) at small Q. The charge/mass ratio for the drops produced in these two mixtures increases continuously with decreasing Q, and gets very close to ionic values. Measured ion currents are represented versus computed maximum electric fields Emax on the liquid surface to infer ion evaporation kinetics. Comparison of measured ion currents with predictions from ion evaporation theory yields an anomalously low activation energy (~1.1 eV). This paradox appears to be due to alteration of the pure conj–eet electric field in the scaling laws used for the pure cone–jet regime, due to the substantial ion current density arising even when the ion current is relatively small. Elimination of this interference would require future ion current measurements in the 10–100 pA level. The electrical propulsion characteristics of the emissions from these liquids are determined and found to be excellent, particularly for 10% and 15% (vol) EMI-Im.
•Eye tracking is often used to reveal co-activation in interactive cognitive systems.•Here, the activation of representations is necessarily temporally contingent.•Transitions are vital for detecting ...temporal contingencies in eye movements.•We assess transitions by means of multilevel markov modeling.•We discuss applications and implications for different theoretical frameworks.
Many eye tracking studies are designed to reveal the co-activation of representations in interactive cognitive systems, such as lexical candidates in the human language system. Such co-activation is presumed to occur within participants on a trial-level. However, traditional analyses mostly use the viewing tendency of participants over trials (e.g., average fixation proportions to visual referents), rather than individual fixation patterns within trials (e.g., consecutive fixations across visual referents). Instead, we argue that assessing temporal dependencies of eye movements between relevant referents is better suited for detecting co-activation in an interactive system, compared to other oft-used methods that may falsely accept or reject interaction hypotheses. We demonstrate how to analyze eye movement transitions with a multilevel markov modeling approach using a relevant experimental example (bilingual co-activation in a visual world paradigm), and discuss the practical applications and theoretical implications when analyzing transitions in any type of eye tracking data.
The role of mid-cingulate cortex (MCC), also referred to as dorsal anterior cingulate cortex, in regulating cognitive control is a topic of primary importance in cognitive neuroscience. Although many ...studies have shown that MCC responds to cognitive demands, lesion studies in humans are inconclusive concerning the causal role of the MCC in the adaptation to these demands. By elegantly combining single-cell recordings with behavioural methods, Sheth et al. Sheth, S. et al. Human dorsal anterior cingulate cortex neurons mediate ongoing behavioural adaptation. Nature 488, 218-22 (2012). recently were able to show that neurons in MCC encode cognitive demand. Importantly, this study also claimed that focal lesions of the MCC abolished behavioural adaptation to cognitive demands. Here we show that the absence of post-cingulotomy behavioural adaptation reported in this study may have been due to practice effects. We run a control condition where we tested subjects before and after a dummy treatment, which substituted cingulotomy with a filler task (presentation of a documentary). The results revealed abolished behavioural adaptation following the dummy treatment. Our findings suggest that future work using proper experimental designs is needed to advance the understanding of the causal role of the MCC in behavioural adaptation.
Previous dot-probe studies indicate that threat-related face cues induce a bias in spatial attention. Independently of spatial attention, a recent psychophysical study suggests that a bilateral ...fearful face cue improves low spatial-frequency perception (LSF) and impairs high spatial-frequency perception (HSF). Here, we combine these separate lines of research within a single dot-probe paradigm. We found that a bilateral fearful face cue, compared with a bilateral neutral face cue, speeded up responses to LSF targets and slowed down responses to HSF targets. This finding is important, as it shows that emotional cues in dot-probe tasks not only bias where information is preferentially processed (i.e., an attentional bias in spatial location), but also bias what type of information is preferentially processed (i.e., a perceptual bias in spatial frequency).
Secure residential youth care facilities try to optimize their help by offering gender-specific treatment, in an attempt to achieve positive behavioral change in adolescents. In this study, we ...examined behavioral change in a sample of 239 Dutch adolescents (M age = 15.59 years, SD = 1.36 years, 54.9% girls) in secure residential care. Pretest, posttest and follow-up measurements were carried out for behavioral problems, PTSD symptoms, emotion regulation, perceived competence and family problems. Comparisons were made between girls in gender-specific care, and girls and boys in regular care. Missing data analyses revealed the dataset contained many missing values. Analyses were performed at group level, using MANCOVA, ANCOVA's and bootstrapped planned contrast, and at case level, using the Reliable Change Index. At group level, results revealed higher effectiveness of gender-specific care for girls compared to regular care for girls, only in diminishing externalizing behavioral problems. Overall, there were more similarities than differences in the effectiveness of gender-specific versus regular help. At individual level, 0-58% of the adolescents improved during their stay in secure residential care. However, most adolescents showed no change (25-88%) or even deterioration (0-39%). These results strongly emphasize the need for alternative interventions.
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