Radiolysis of myoglobin concentrated gels by protons: specific changes in secondary structure and production of carbon monoxide.

While particle therapy has been used for decades for cancer treatment, there is still a lack of information on the molecular mechanisms of biomolecules radiolysis by accelerated ions. Here, we examine the effects of accelerated protons on highly concentrated native myoglobin, by means of Fourier transform infrared and UV-Visible spectroscopies. Upon irradiation, the secondary structure of the protein is drastically modified, from mostly alpha helices conformation to mostly beta elements at highest fluence. These changes are accompanied by significant production of carbon monoxide, which was shown to come from heme degradation under irradiation. The radiolytic yields of formation of denatured protein, carbon monoxide, and of heme degradation were determined, and found very close to each other: G+denatured Mb ≈ G+CO ≈ G-heme = 1.6 × 10-8 ± 0.1 × 10-8 mol/J = 0.16 ± 0.01 species/100 eV. The denaturation of the protein to a beta structure and the production of carbon monoxide under ion irradiation are phenomena that may play an important role in the biological effects of ionizing radiation.

Kinetics vs. thermodynamics: walking on the line for a five-fold increase in MnSi Curie temperature.

Green and digital transitions will induce tremendous demand for metals and semiconductors. This raises concerns about the availability of materials in the rather near future. Addressing this challenge requires an unprecedented effort to discover new materials that are more sustainable and also to expand their functionalities beyond conventional material limits. From this point of view, complex systems combining semiconductor and magnetic properties in a single material lay the foundations for future nanoelectronics devices. Through a combination of out-of-stable equilibrium processes, we achieved fine control over the crystallisation of non-stoichiometric MnSix (x = 0.92). The Curie temperature shows non-monotonous evolution with crystallisation. At the earliest and final stages, the Curie temperature is comparable with stoichiometric MnSi (TC = 30 K). At the intermediate stage, while the material is crystalline and remains non-stoichiometric, a remarkable fivefold increase in Curie temperature (TC = 150 K) is observed. This finding highlights the potential for controlling the metastability of materials as a promising and relatively unexplored pathway to enhance material properties, without relying on critical materials such as rare earth elements.

Improving physical activity using a single personalized consequence-based approach-avoidance training: Effects on self-reported behaviors, attitudes, and choices.

OBJECTIVE: Despite their potential in improving health behaviors, such as physical activity (PA), the effectiveness of interventions targeting automatic precursors remains contrasted. We examined the effects of a single session of ABC training - a personalized consequence-based approach-avoidance training - on PA, relative to an active control condition and a control condition. METHODS: Middle-aged US participants (N = 360, 53 % of women) either completed an ABC training (being instructed to approach PA to obtain self-relevant consequences), an approach-avoidance training (approaching PA in 90 % of trials), or a control training (approaching PA in 50 % of trials). Participants selected antecedents (e.g., "When I have little time") in which personalized choices between PA and sedentary alternatives were likely to occur. In the ABC training only, after approaching PA, self-relevant consequences were displayed (e.g., increase in the health status of participant's avatar). Primary outcome was self-reported PA seven days after the intervention. Secondary outcomes included choices for PA (vs sedentary) alternatives in a hypothetical free-choice task, intention, automatic and explicit attitudes toward PA. RESULTS: No significant effect of the ABC intervention on PA was observed, so as on intention and explicit attitudes. However, the ABC intervention was associated with higher odds of choosing PA alternatives in the free-choice task and with more positive automatic attitudes toward PA. CONCLUSIONS: While the ABC training was not effective at improving PA, its effects on choices and automatic attitudes suggest that this intervention may still have potential. Future studies with intensive trainings and device-based measures of PA remains needed.

Social comparison in the classroom: Priming approach/avoidance changes the impact of social comparison on self-evaluation and performance.

BACKGROUND: Social comparisons between pupils are especially relevant at school. Such comparisons influence self-perception and performance. When pupils evaluate themselves more negatively and perform worse after an upward comparison (with a better off pupil) than a downward comparison (with a worse-off pupil), this is a contrast effect. On the other hand, when they evaluate themselves more positively and are better after an upward than downward comparison, this is an assimilation effect. AIMS: We examine assimilation and contrast effects of comparison in the classroom on pupils' self-evaluation and performance. Previous work by Fayant, Muller, Nurra, Alexopoulos, and Palluel-Germain (2011) lead us to hypothesize that approach vs. avoidance moderates the impact of upward vs. downward comparison: approach should lead to an assimilation effect on self-evaluation and performance, while avoidance should lead to contrast on self-evaluation and performance. METHODS: To test this hypothesis, we primed pupils with either approach or avoidance before reading upward or downward comparison information about another pupil. We then measured self-evaluation (Experiment 1) and performance (Experiments 1 and 2). RESULTS: Results confirmed our predictions and revealed the predicted interaction on self-evaluation (Experiment 1) and performance (Experiment 2): approach leads to an assimilation effect (in both experiments) whereas avoidance leads to a contrast effect (in Experiment 2). CONCLUSIONS: These experiments replicate previous studies on self-evaluation and also extend previous work on performance and in a classroom setting. Priming approach before upward comparison seems especially beneficial to pupils.

Shallow implanted SiC spin qubits used for sensing an internal spin bath and external YIG spins.

Silicon vacancy (VSi) color centers in bulk SiC are excellent electron spin qubits. However, most spin based quantum devices require shallow spin qubits, whose dynamics is often different from that of bulk ones. Here, we demonstrate (i) a new method for creating shallow VSi (V2) spin qubits below the SiC surface by low energy ion implantation through a sacrificial SiO2 layer, (ii) that these shallow VSi are dipolar coupled to an electronic spin bath, analysed by Hahn echo decay, dynamical decoupling (DD), and optically pumped pulsed electron-electron double resonance experiments (OP-PELDOR), (iii) that their coherence time increases with cooling of the spin bath (from 55 µs at 297 K to 107 µs at 28 K), and that it can be further extended to 220 µs at 100 K by DD, thus demonstrating their relevance for PELDOR-based quantum sensors and processors. Finally, (iv) external spin sensing is demonstrated by the shift of VSi magnetic resonance lines induced by the dipolar stray magnetic field of a nearby ferrimagnetic YIG film.

An Improved STEM/EDX Quantitative Method for Dopant Profiling at the Nanoscale.

In this paper, an improved quantification technique for STEM/EDX measurements of 1D dopant profiles based on the Cliff-Lorimer equation is presented. The technique uses an iterative absorption correction procedure based on density models correlating the local mass density and composition of the specimen. Moreover, a calibration and error estimation procedure based on linear regression and error propagation is proposed in order to estimate the total measurement error in the dopant density. The proposed approach is applied to the measurement of the As profile in a nanodevice test structure. For the calibration, two crystalline Si specimens implanted with different As doses have been used, and the calibration of the Cliff-Lorimer coefficients has been carried out using Rutherford Back Scattering measurements. The As profile measurement has been carried out on an FinFET test structure, showing that quantitative results can be obtained in the nanometer scale and for dopant atomic densities lower than 1%. Using the proposed approach, the measurement error and detection limit for our experimental setup are calculated and the possibility to improve this limit by increasing the observation time is discussed.

The online-VAAST: A short and online tool to measure spontaneous approach and avoidance tendencies.

Among the great variety of approach/avoidance tasks, the Visual Approach/Avoidance by the Self Task (VAAST, Rougier et al., 2018) appears to be a promising tool. Previous work showed that the VAAST leads to large and replicable compatibility effects (e.g., faster response time to approach positive stimuli and avoid negative stimuli than the reverse). In the present contribution, we provide an online and easy-to-use version of the VAAST (namely, the online-VAAST). Across four experiments, we show that the online-VAAST produces effects that are of similar magnitude to those of the lab version of this task. Specifically, we obtained compatibility effects when using positive/negative words (Experiment 1), positive/negative images (Experiment 2), French/North-African first names (Experiment 3), and European American/African American first names (Experiment 4). Moreover, these effects emerged with culturally different populations (i.e., Americans in Experiments 1, 2, and 4, French in Experiment 3). Overall, the online-VAAST could be of great interest for all researchers interested in measuring approach/avoidance tendencies: Its specificities allow reaching large samples both offline and online with no accessibility constraints regarding programming abilities or program copyright.

New recommendations for testing indirect effects in mediational models: The need to report and test component paths.

In light of current concerns with replicability and reporting false-positive effects in psychology, we examine Type I errors and power associated with 2 distinct approaches for the assessment of mediation, namely the component approach (testing individual parameter estimates in the model) and the index approach (testing a single mediational index). We conduct simulations that examine both approaches and show that the most commonly used tests under the index approach risk inflated Type I errors compared with the joint-significance test inspired by the component approach. We argue that the tendency to report only a single mediational index is worrisome for this reason and also because it is often accompanied by a failure to critically examine the individual causal paths underlying the mediational model. We recommend testing individual components of the indirect effect to argue for the presence of an indirect effect and then using other recommended procedures to calculate the size of that effect. Beyond simple mediation, we show that our conclusions also apply in cases of within-participant mediation and moderated mediation. We also provide a new R-package that allows for an easy implementation of our recommendations. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Restoring wild-type-like CA1 network dynamics and behavior during adulthood in a mouse model of schizophrenia.

Schizophrenia is a severely debilitating neurodevelopmental disorder. Establishing a causal link between circuit dysfunction and particular behavioral traits that are relevant to schizophrenia is crucial to shed new light on the mechanisms underlying the pathology. We studied an animal model of the human 22q11 deletion syndrome, the mutation that represents the highest genetic risk of developing schizophrenia. We observed a desynchronization of hippocampal neuronal assemblies that resulted from parvalbumin interneuron hypoexcitability. Rescuing parvalbumin interneuron excitability with pharmacological or chemogenetic approaches was sufficient to restore wild-type-like CA1 network dynamics and hippocampal-dependent behavior during adulthood. In conclusion, our data provide insights into the network dysfunction underlying schizophrenia and highlight the use of reverse engineering to restore physiological and behavioral phenotypes in an animal model of neurodevelopmental disorder.

The Sociolinguistic Repetition Task: A New Paradigm for Exploring the Cognitive Coherence of Language Varieties.

Sociolinguistic studies generally focus on specific sociolinguistic variables. Consequently, they rarely examine whether different sociolinguistic variables have coherent orientation in a specific language variety (a social or a regional dialect) or whether the speakers freely mix sociolinguistic variants. While different attempts have been made to identify coherence and mixing in the production or perception of dialects, our aim is to answer this question at the level of the cognitive representation of varieties. For this purpose, we draw on the phenomenon of sociolinguistic restoration: when they repeat sociolinguistically mixed utterances, people tend to make them homogeneous. The first experiment-a repetition task-reproduced sociolinguistic restoration in an experimental setting. The second experiment-a judgment task-ensured that participants perceived the difference between homogeneous and mixed utterances. We conclude that high-order coherent representations influence the reconstruction of utterances during the repetition task.

Homeostatic Plasticity in the Hippocampus Facilitates Memory Extinction.

Correlated activity in the hippocampus drives synaptic plasticity that is necessary for the recruitment of neuronal ensembles underlying fear memory. Sustained neural activity, on the other hand, may trigger homeostatic adaptations. However, whether homeostatic plasticity affects memory function remains unknown. Here, we use optogenetics to induce cell autonomous homeostatic plasticity in CA1 pyramidal neurons and granule cells of the hippocampus. High-frequency spike trains applied for 10 min decreased the number of excitatory spine synapses and increased the number of inhibitory shaft synapses. This activity stopped dendritic spine formation via L-type voltage-dependent calcium channel activity and protein synthesis. Applied selectively to the ensemble of granule cells encoding a contextual fear memory, the spike trains impaired memory recall and facilitated extinction. Our results indicate that homeostatic plasticity triggered by optogenetic neuronal firing alters the balance between excitation and inhibition in favor of memory extinction.

Of guns and snakes: testing a modern threat superiority effect.

Previous studies suggest that ancient (i.e. evolutionary-based) threats capture attention because human beings possess an inborn module shaped by evolution and dedicated to their detection. An alternative account proposes that a key feature predicting whether a stimulus will capture attention is its relevance rather than its ontology (i.e. phylogenetic or ontogenetic threat). Within this framework, the present research deals with the attentional capture by threats commonly encountered in our urban environment. In two experiments, we investigate the attentional capture by modern threats (i.e. weapons). In Experiment 1, participants responded to a target preceded by a cue, which was a weapon or a non-threatening stimulus. We found a larger cuing effect (faster reaction times to valid vs. invalid trials) with weapons as compared with non-threatening cues. In Experiment 2, modern (e.g. weapons) and ancient threats (e.g. snakes) were pitted against one another as cues to determine which ones preferentially capture attention. Crucially, participants were faster to detect a target preceded by a modern as opposed to an ancient threat, providing initial evidence for a superiority of modern threat. Overall, the present findings appear more consistent with a relevance-based explanation rather than an evolutionary-based explanation of threat detection.

Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies.

Ultrathin layers (<20 nm) of pBR322 plasmid DNA were deposited onto 2.5 µm thick polyester films and exposed to proton Bragg-peak energies (90-3000 keV) at various fluences. A quantitative analysis of radio-induced DNA damage is reported here in terms of single- and double-strand breaks (SSB and DSB, respectively). The corresponding yields as well as G-values and the cross sections exhibit fairly good agreement with the rare available data, stemming from close experimental conditions, namely, based on α particle irradiation. SSB/DSB rates appear to be linear when plotted against linear energy transfer (LET) in the whole energy range studied. All the data present a maximum in the 150-200 keV energy range; as for LET, it peaks at 90 keV. We also show that fragmentation starts to be significant for proton fluences greater than 1 × 1011 cm-2 at the Bragg-peak energies. Finally, we determine the average proton track radial extension, rmax, corresponding to an occupation probability of 100% DSB in the Bragg-peak region. The rmax values determined are in excellent agreement with the radial extensions of proton tracks determined by simulation approaches in water. When plotted as a function of LET, both SSB and DSB cross sections bend back at high LETs.

A Multilab Preregistered Replication of the Ego-Depletion Effect.

Good self-control has been linked to adaptive outcomes such as better health, cohesive personal relationships, success in the workplace and at school, and less susceptibility to crime and addictions. In contrast, self-control failure is linked to maladaptive outcomes. Understanding the mechanisms by which self-control predicts behavior may assist in promoting better regulation and outcomes. A popular approach to understanding self-control is the strength or resource depletion model. Self-control is conceptualized as a limited resource that becomes depleted after a period of exertion resulting in self-control failure. The model has typically been tested using a sequential-task experimental paradigm, in which people completing an initial self-control task have reduced self-control capacity and poorer performance on a subsequent task, a state known as ego depletion Although a meta-analysis of ego-depletion experiments found a medium-sized effect, subsequent meta-analyses have questioned the size and existence of the effect and identified instances of possible bias. The analyses served as a catalyst for the current Registered Replication Report of the ego-depletion effect. Multiple laboratories (k = 23, total N = 2,141) conducted replications of a standardized ego-depletion protocol based on a sequential-task paradigm by Sripada et al. Meta-analysis of the studies revealed that the size of the ego-depletion effect was small with 95% confidence intervals (CIs) that encompassed zero (d = 0.04, 95% CI [-0.07, 0.15]. We discuss implications of the findings for the ego-depletion effect and the resource depletion model of self-control.

Fragile X Mental Retardation Protein (FMRP) controls diacylglycerol kinase activity in neurons.

Fragile X syndrome (FXS) is caused by the absence of the Fragile X Mental Retardation Protein (FMRP) in neurons. In the mouse, the lack of FMRP is associated with an excessive translation of hundreds of neuronal proteins, notably including postsynaptic proteins. This local protein synthesis deregulation is proposed to underlie the observed defects of glutamatergic synapse maturation and function and to affect preferentially the hundreds of mRNA species that were reported to bind to FMRP. How FMRP impacts synaptic protein translation and which mRNAs are most important for the pathology remain unclear. Here we show by cross-linking immunoprecipitation in cortical neurons that FMRP is mostly associated with one unique mRNA: diacylglycerol kinase kappa (Dgkκ), a master regulator that controls the switch between diacylglycerol and phosphatidic acid signaling pathways. The absence of FMRP in neurons abolishes group 1 metabotropic glutamate receptor-dependent DGK activity combined with a loss of Dgkκ expression. The reduction of Dgkκ in neurons is sufficient to cause dendritic spine abnormalities, synaptic plasticity alterations, and behavior disorders similar to those observed in the FXS mouse model. Overexpression of Dgkκ in neurons is able to rescue the dendritic spine defects of the Fragile X Mental Retardation 1 gene KO neurons. Together, these data suggest that Dgkκ deregulation contributes to FXS pathology and support a model where FMRP, by controlling the translation of Dgkκ, indirectly controls synaptic proteins translation and membrane properties by impacting lipid signaling in dendritic spine.

Hippocampal Somatostatin Interneurons Control the Size of Neuronal Memory Ensembles.

Hippocampal neurons activated during encoding drive the recall of contextual fear memory. Little is known about how such ensembles emerge during acquisition and eventually form the cellular engram. Manipulating the activity of granule cells (GCs) of the dentate gyrus (DG), we reveal a mechanism of lateral inhibition that modulates the size of the cellular engram. GCs engage somatostatin-positive interneurons that inhibit the dendrites of surrounding GCs. Our findings reveal a microcircuit within the DG that controls the size of the cellular engram and the stability of contextual fear memory.

Synthesis of FMRFaNV, a Photoreleasable Caged Transmitter Designed to Study Neuron-Glia Interactions in the Central Nervous System.

Neuroscience studies require technologies able to deliver compounds with both scale and timing compatibility with morphological and physiological synaptic properties. In this light, two-photon flash photolysis has been extensively used to successfully apply glutamate or other neurotransmitters at the synaptic level. However, the set of commercially available caged compounds is restricted and incompatible with studies demanding high cell specificity. The gain in cell specificity is especially relevant and challenging when studying neuron-glia interactions in the central nervous system. Here we develop a system to mimic the metabotropic glutamate receptor-dependent response of astrocytes, a glial cell type, following synaptic glutamate release. For this, we expressed an exogeneous orphan Gq-coupled protein of the Mas-related-gene (Mrg) family in glial cells and generated an MrgR's agonist peptide (FMRFa) that was chemically caged with a nitroveratryl photolabile protecting group (NV). NV has an appropriate quantum yield and a high absorption maximum that makes it very adapted to experiments with very short irradiation time. This novel caged compound allowed the activation of MrgR with both single- and two-photon light sources. Indeed, MrgR activation induced calcium transients and morphological changes in astrocytes as described previously. Thus, FMRFaNV is a very promising tool to study neuron-glia interactions.

A mindset of competition versus cooperation moderates the impact of social comparison on self-evaluation.

Do people feel better or worse about themselves when working with someone who is better than they are? We present the first replication of the work of Stapel and Koomen (2005), who showed that being in a competitive vs. cooperative mindset moderates the effects of social comparison on self-evaluation. In Experiment 1, we present a close replication of Stapel and Koomen (2005, Study 2). Participants in competition/cooperation had to self-evaluate after receiving information about the personal characteristics of an upward/downward comparison target. In Experiment 2, we went further by providing feedback about both the comparison target and the self. Our results and a small-scale meta-analysis combining our experiments and Stapel and Koomen's (2005) confirm that a competitive/cooperative mindset moderates the impact of social comparison on self-evaluation; nevertheless, the effect size we found across the two experiments is clearly more modest than the one found in Stapel and Koomen's (2005) work.

Acid-sensing ion channel 1a drives AMPA receptor plasticity following ischaemia and acidosis in hippocampal CA1 neurons.

KEY POINTS: The hippocampal CA1 region is highly vulnerable to ischaemic stroke. Two forms of AMPA receptor (AMPAR) plasticity - an anoxic form of long-term potentiation and a delayed increase in Ca(2+) -permeable (CP) AMPARs - contribute to this susceptibility by increasing excitotoxicity. In CA1, the acid-sensing ion channel 1a (ASIC1a) is known to facilitate LTP and contribute to ischaemic acidotoxicity. We have examined the role of ASIC1a in AMPAR ischaemic plasticity in organotypic hippocampal slice cultures exposed to oxygen glucose deprivation (a model of ischaemic stroke), and in hippocampal pyramidal neuron cultures exposed to acidosis. We find that ASIC1a activation promotes both forms of AMPAR plasticity and that neuroprotection, by inhibiting ASIC1a, circumvents any further benefit of blocking CP-AMPARs. Our observations establish a new interaction between acidotoxicity and excitotoxicity, and provide insight into the role of ASIC1a and CP-AMPARs in neurodegeneration. Specifically, we propose that ASIC1a activation drives certain post-ischaemic forms of CP-AMPAR plasticity. ABSTRACT: The CA1 region of the hippocampus is particularly vulnerable to ischaemic damage. While NMDA receptors play a major role in excitotoxicity, it is thought to be exacerbated in this region by two forms of post-ischaemic AMPA receptor (AMPAR) plasticity - namely, anoxic long-term potentiation (a-LTP), and a delayed increase in the prevalence of Ca(2+) -permeable GluA2-lacking AMPARs (CP-AMPARs). The acid-sensing ion channel 1a (ASIC1a), which is expressed in CA1 pyramidal neurons, is also known to contribute to post-ischaemic neuronal death and to physiologically induced LTP. This raises the question does ASIC1a activation drive the post-ischaemic forms of AMPAR plasticity in CA1 pyramidal neurons? We have tested this by examining organotypic hippocampal slice cultures (OHSCs) exposed to oxygen glucose deprivation (OGD), and dissociated cultures of hippocampal pyramidal neurons (HPNs) exposed to low pH (acidosis). We find that both a-LTP and the delayed increase in the prevalence of CP-AMPARs are dependent on ASIC1a activation during ischaemia. Indeed, acidosis alone is sufficient to induce the increase in CP-AMPARs. We also find that inhibition of ASIC1a channels circumvents any potential neuroprotective benefit arising from block of CP-AMPARs. By demonstrating that ASIC1a activation contributes to post-ischaemic AMPAR plasticity, our results identify a functional interaction between acidotoxicity and excitotoxicity in hippocampal CA1 cells, and provide insight into the role of ASIC1a and CP-AMPARs as potential drug targets for neuroprotection. We thus propose that ASIC1a activation can drive certain forms of CP-AMPAR plasticity, and that inhibiting ASIC1a affords neuroprotection.

"The mask who wasn't there": visual masking effect with the perceptual absence of the mask.

Does a visual mask need to be perceptually present to disrupt processing? In the present research, we proposed to explore the link between perceptual and memory mechanisms by demonstrating that a typical sensory phenomenon (visual masking) can be replicated at a memory level. Experiment 1 highlighted an interference effect of a visual mask on the categorization of auditory targets and confirmed the multimodal nature of knowledge. In Experiment 2, we proposed to reactivate this mask in a categorization task on visual targets. Results showed that the sensory mask has disrupted (slower reaction times) the processing of the targets whether the mask was perceptually present or reactivated in memory. These results support a sensory-based conception of memory processing and suggest that the difference between perceptual processes and memory processes is characterized by the presence (perception) or the absence (memory) of the sensory properties involved in the activity.