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Aims Atrial fibrillation (AF) has been associated with functional impairment. However, the role exerted by AF on the long-term trajectories of functional mobility remains to be elucidated. This study aimed to evaluate the impact of AF on functional mobility by tracing walking speed (WS) trajectories over 15 years of follow-up in a population-based cohort of individuals aged 60+ years. Methods and results This population-based cohort study included 3141 community-dwelling participants (mean age 73.7 years; 63.6% women) from the Swedish National Study on Aging and Care in Kungsholmen, who were regularly examined from 2001–2004 to 2016–2019. Functional mobility was assessed by measuring WS in a standardized way. The association between AF and WS trajectories was assessed by multivariable joint models accounting for the longitudinal dropouts due to death. Stratified analyses by demographic and clinical factors were performed. The effect-modifying role of oral anticoagulant therapy (OAC), incident heart failure (HF), and incident stroke was finally investigated. At baseline, 285 (9.1%) participants were ascertained to have AF. A faster annual WS decline was observed in persons with AF than in non-AF peers (adjusted β coefficient per year = −0.011, 95% confidence interval: −0.016 to −0.005). Incident HF and stroke were associated with greater WS decline in participants with AF. OAC use was not associated with a slower functional decline. Conclusion Atrial fibrillation is associated with a faster physical function decline in older individuals. Incident HF and stroke possibly accelerate WS decline over time in AF participants. [ABSTRACT FROM AUTHOR]

Background: Research examining the potential effects of stimulant exposure in childhood on subsequent development of substance use disorder (SUD) have focused on differences in the brain reward system as a function of risk. Methods: 18 drug naïve children ages 7 to 12 years (11 High Risk [ADHD + ODD/CD]; 7 Low Risk [ADHD only]), underwent fMRI scans before and after treatment with mixed amphetamine salts, extended release (MAS-XR). We examined correlations between clinical ratings and fMRI activation at baseline and following treatment as a function of risk status. Results: High Risk children had higher activation than Low Risk children at baseline during both the Reward and Surprising Non-Reward conditions. Treatment produced strong differential effects on brain activation pertinent to group and reward outcome. Conclusions: Findings support the hypothesized role of reward mechanisms in SUD risk, and suggest that stimulant treatment may have differential effects on reward processing in relation to SUD risk. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to screen the genes and pathways that are involved in spermatogonia stem cell (SSC) differentiation regulation during the transition from Aundiff to A1. Methods: RNA sequencing was performed to screen differentially expressed genes at 1 d and 2 d after SSC differentiation culture. KEGG pathway enrichment and GO function analysis were performed to reveal the genes and pathways related to the initiation of early SSC differentiation. Results: The GO analysis showed that Rpl21, which regulates cell differentiation initiation, significantly increased after 1 day of SSC differentiation. The expressions of Fn1, Cd9, Fgf2, Itgb1, Epha2, Ctgf, Cttn, Timp2 and Fgfr1, which are related to promoting differentiation, were up-regulated after 2 days of SSC differentiation. The analysis of the KEGG pathway revealed that RNA transport is the most enriched pathway 1 day after SSC differentiation. Hspa2, which promotes the differentiation of male reproductive cells, and Cdkn2a, which participates in the cell cycle, were significantly up-regulated. The p53 pathway and MAPK pathway were the most enriched pathways 2 days after SSC differentiation. Cdkn1a, Hmga2, Thbs1 and Cdkn2a, microRNAs that promote cell differentiation, were also significantly up-regulated. Conclusions: RNA transport, the MAPK pathway and the p53 pathway may play vital roles in early SSC differentiation, and Rpl21, Fn1, Cd9, Fgf2, Itgb1, Epha2, Ctgf, Cttn, Timp2, Fgfr1, Hspa2, Cdkn2a, Cdkn1a, Hmga2 and Thbs1 are involved in the initiation of SSC differentiation. The findings of this study provide a reference for further revelations of the regulatory mechanism of SSC differentiation. [ABSTRACT FROM AUTHOR]

To estimate yield stress and other rheological properties relevant to modeling of wax deposition in pipelines where flow is continuous, but stress varies across the pipe radius, model wax-oil mixtures are cooled at multiple cooling rates under constant shear stress until a temperature is reached, at which flow is arrested by gelation due to wax crystal formation. From these data, combined with a measurement of temperature-dependence of precipitated wax concentration by differential scanning calorimetry, an apparent yield stress σ y , below which flow is arrested at each temperature, is related to the concentration of precipitated wax C p and the cooling rate. Results are reported for multiple concentrations in oil of two independent wax mixtures: a many-component commercial wax mimicking the composition of field oil, and a simpler six-alkane mixture. These transient rheological data are fit to a pseudo "Herschel–Bulkley" constitutive equation from which it is found that the yield stresses obtained during flow under cooling are generally an order of magnitude, or more, lower than the yield stresses obtained in the previous work in flow at a comparable constant temperature after cooling in the absence of flow. We also find a strong decrease in the arrest temperature with a decreasing cooling rate, with no convergence even at the lowest cooling rate of 0.0625 °C min−1, indicating that under slower cooling, flow continues even under low stresses. The cooling-rate-dependent yield stress obtained in our study under constant stress provides a challenge to the recent models of gelation under flow stress and is of relevance to wax deposition in pipelines. [ABSTRACT FROM AUTHOR]

Philosophers and cognitive scientists have been debating about the nature of practical knowledge in skilled action. A big challenge is that of establishing whether and how practical knowledge (knowledge-how) is influenced by, or related to propositional knowledge (knowledge-that). This becomes even more challenging when trying to understand how propositional and motor representations may cooperate in making action performance flexible, while also remaining rational. In this paper, we offer an account that explains how practical knowledge leads to the execution of our actions in a way that accounts for its relation to propositional knowledge, and with respect to the possibility of granting flexibility and rationality. [ABSTRACT FROM AUTHOR]

What mental states guide the execution of our actions? It is generally agreed that the execution of an action is guided by the relevant knowledge state concerning how to perform that action. However, not all agree on which mental states underlie such a knowledge. Some suggest that knowing how to perform an action has mainly to do with the propositional representation about the way to execute that action. Those opposing this view stress the role of the motor, non-propositional representation as the mental state responsible for action performance. The aim of this article is to overcome this dichotomy by showing that an explanation of the cognitive processes underlying knowing how to perform an action needs both propositional and motor states. We defend this view by providing an account of the way in which our propositional knowledge about an action is constituted by the motor representation that guides the execution of that action. [ABSTRACT FROM AUTHOR]

Machine-learning prediction studies have shown potential to inform treatment stratification, but recent efforts to predict psychotherapy outcomes with clinical routine data have only resulted in moderate prediction accuracies. Neuroimaging data showed promise to predict treatment outcome, but previous prediction attempts have been exploratory and reported small clinical sample sizes. Herein, we aimed to examine the incremental predictive value of neuroimaging data in contrast to clinical and demographic data alone (for which results were previously published), using a two-level multimodal ensemble machine-learning strategy. We used pretreatment structural and task-based fMRI data to predict virtual reality exposure therapy outcome in a bicentric sample of N = 190 patients with spider phobia. First, eight 1st-level random forest classifications were conducted using separate data modalities (clinical questionnaire scores and sociodemographic data, cortical thickness and gray matter volumes, functional activation, connectivity, connectivity-derived graph metrics, and BOLD signal variance). Then, the resulting predictions were used to train a 2nd-level classifier that produced a final prediction. No 1st-level or 2nd-level classifier performed above chance level except BOLD signal variance, which showed potential as a contributor to higher-level prediction from multiple regions across the brain (1st-level balanced accuracy = 0.63). Overall, neuroimaging data did not provide any incremental accuracy for treatment outcome prediction in patients with spider phobia with respect to clinical and sociodemographic data alone. Thus, we advise caution in the interpretation of prediction performances from small-scale, single-site patient samples. Larger multimodal datasets are needed to further investigate individual-level neuroimaging predictors of therapy response in anxiety disorders. [ABSTRACT FROM AUTHOR]

The cerebral cortex is closely associated with learning and memory, and fluoride is capable of inducing cortical toxicity, but its mechanism is unclear. This study aimed to investigate the role of endoplasmic reticulum stress and autophagy in fluoride-induced cortical toxicity. Rats exposed to sodium fluoride (NaF) were used as an in vivo model. The results showed that NaF exposure impaired the learning and memory capacities and increased urinary fluoride levels in rats. In addition, NaF exposure induced excessive endoplasmic reticulum stress and associated apoptosis, as evidenced by elevated IRE1α, GRP78, cleaved caspase-12, and cleaved caspase-3, as well as defective autophagy, as evidenced by increased expression of Beclin1, LC3-II, and p62 in cortical areas. Importantly, the endoplasmic reticulum stress inhibitor 4-phenylbutyric acid (4-PBA) alleviated endoplasmic reticulum stress as well as defective autophagy, thus confirming the critical role of endoplasmic reticulum stress and autophagy in fluoride-induced cortical toxicity. Taken together, these results suggest that excessive endoplasmic reticulum stress and its mediated defective autophagy lead to fluoride-induced cortical toxicity. This provides new insights into the mechanisms of fluoride-induced neurotoxicity and a new theoretical basis for the prevention and treatment of fluoride-induced neurotoxicity. [ABSTRACT FROM AUTHOR]

What mental states are required for an agent to know-how to perform an action? This question fuels one of the hottest debates in the current literature on philosophy of action. Answering this question means facing what we call here The Challenge of Format Dualism, which consists in establishing which is the format of the mental representations involved in practical knowledge and, in case they are given in more than one format, explaining how these different formats can interlock. This challenge has generated two parallel debates: the debate between Intellectualism and Anti-Intellectualism on the one hand, and the debate on the Interface Problem on the other. While the former is about whether practical knowledge can be considered a species of propositional knowledge, the latter investigates how motoric and propositional states can be related. Here we offer a unified account capable of explicitly analyzing those two problems within the same philosophical framework. Our account suggests a new way for solving the Interface Problem that paves the way for addressing the debate between Intellectualism and Anti-Intellectualism. [ABSTRACT FROM AUTHOR]

Based on the general assumption that even problematic behaviours are associated with an inherently health-promoting motivation to cope with unpleasant or unsatisfying life situations, the compensatory model of media use focuses on how psychosocial vulnerabilities moderate links between media behaviours and adverse outcomes. The present paper means to further develop this approach by exploring the moderating role of state- and trait-level factors (state: perceived stress; trait: social interaction anxiety and loneliness) on the relation between video game consumption (i.e. playing duration and habitual gaming), motivations (i.e. achievement, social, immersion), and engagement (harmonious and obsessive engagement) within a large-scale sample of mostly heavy gamers. Overall, results provided further evidence for the compensatory approach, with perceived stress emerging as a critical psychosocial factor that intensified positive and negative relations between several gaming behaviours and harmful outcomes. Moreover, our results reiterated the heuristic importance of intra- and interpersonally pressured (i.e. obsessive) engagement to explain adverse gaming outcomes as well as self-determined (i.e. harmonious) engagement as a potentially fruitful gateway toward more healthy gaming. These findings constitute solid empirical groundwork that may contribute to effective prevention and intervention methods against problematic gaming. [ABSTRACT FROM AUTHOR]

Although the evidence for the genetic basis of attention-deficit/hyperactivity disorder (ADHD) is strong, environmental factors, such as the quality of parenting or the home environment, may moderate such genetic liability. The plausible negative effect of a low-quality home environment and negative parenting on child outcomes is well-established; however, the positive effect of a high-quality environment and positive parenting remained largely uninvestigated. Due to the presence of genetic, temperamental, or physiological factors, children who were traditionally considered at-risk for ADHD may be more sensitive to aspects of their environment compared to children who are not at such risk. Therefore, they would be more affected by their environmental experience, either for good or bad. Under supportive environmental conditions, such at-risk individuals might actually outperform their non-vulnerable peers, suggesting that these individual factors might be considered susceptibility factors rather than risk factors. Little is known regarding the positive effect of the environment in the ADHD literature, but it has been demonstrated in cognitive functions that are closely associated with ADHD, such as executive functions (EF). We review this literature and examine the extant empirical support for sensitivity to aspects of the home environment and parenting in the case of ADHD and EF. Moreover, we review factors that could help identify the specific aspects of the home environment and parenting that these children might be more susceptible to. Such knowledge could be valuable when designing preventive interventions and identifying those children that are especially sensitive and could benefit from such interventions. Recommendations for future studies are discussed as well. [ABSTRACT FROM AUTHOR]

Repetitive negative thinking (RNT) captures an important transdiagnostic factor that predisposes to a maladaptive stress response and contributes to diverse psychiatric disorders. Although RNT can best be seen as a continuous symptom dimension that cuts across boundaries from health to various psychiatric disorders, the neural mechanisms underlying RNT have almost exclusively been studied in health and stress-related disorders, such as depression and anxiety disorders. We set out to study RNT from a large-scale brain network perspective in a diverse population consisting of healthy subjects and patients with a broader range of psychiatric disorders. We studied 46 healthy subjects along with 153 patients with a stress-related and/or neurodevelopmental disorder. We focused on three networks, that are associated with RNT and diverse psychiatric disorders: the salience network, default mode network (DMN) and frontoparietal network (FPN). We investigated the relationship of RNT with both network connectivity strength at rest and with the stress-induced changes in connectivity. Across our whole sample, the level of RNT was positively associated with the connectivity strength of the left FPN at rest, but negatively associated with stress-induced changes in DMN connectivity. These findings may reflect an upregulation of the FPN in an attempt to divert attention away from RNT, while the DMN result may reflect a less flexible adaptation to stress, related to RNT. Additionally, we discuss how our findings fit into the non-invasive neurostimulation literature. Taken together, our results provide initial insight in the neural mechanisms of RNT across the spectrum from health to diverse psychiatric disorders. [ABSTRACT FROM AUTHOR]

In a 2.45 GHz plasma torch, carbon dioxide (CO2) has been converted into carbon monoxide (CO) and oxygen (O2) at atmospheric pressure. The conversion and the efficiency of the plasma have been determined using two independent measuring methods: mass spectrometry and Fourier transform infrared absorption spectroscopy. The conversion depends on the measurement position in the exhaust gas duct. The conversion values at the beginning of the exhaust gas duct are significantly higher (maximum conversion is 22 %) than in the thermalized state at the end of the duct. In the cold, thermalized state of the gas, the maximum conversion rate is 8 % at 1.5 eV molecule−1. The maximum efficiency of 25 % is achieved at approximatively 0.6 eV molecule−1 operating at a microwave power of 0.48 kW and a mass flow of 12 slm CO2. [ABSTRACT FROM AUTHOR]

Reconstructions of ocean primary productivity (PP) help to explain past and present biogeochemical cycles and climate changes in the oceans. We document PP variations over the last 50 kyr in a currently oligotrophic subtropical region, the Gulf of Cadiz. Data combine refined results from previous investigations on dinocyst assemblages, alkenones, and stable isotopes (18O, 13C) in planktonic (Globigerina bulloides) and endobenthic (Uvigerina mediterranea) foraminifera from cores MD04‐2805 CQ and MD99‐2339, with new isotopic measurements on epibenthic (Cibicides pachyderma‐Cibicidoides wuellerstorfi) foraminifera and dinocyst‐based estimates of PP using the new n = 1,968 modern database. We constrain PP variations and export production by integrating qualitative information from bioindicators with dinocyst‐based quantitative reconstructions such as PP and seasonal sea surface temperature and information about remineralization from the benthic Δδ13C (difference between epibenthic and endobenthic foraminiferal δ13C signatures). This study also includes new information on alkenone‐based SST and total organic carbon which provides insights into the relationship between past regional hydrological activity and PP regime change. We show that PP, carbon export, and remineralization were generally high in the NE subtropical Atlantic Ocean during the last glacial period and that the Last Glacial Maximum (LGM) had lower Δδ13C than the Heinrich Stadials with sustained high PP, likely allowing enhanced carbon sequestration. We link these PP periods to the dynamics of upwelling, active almost year‐round during sadials, but restricted to spring‐summer during interstadials and LGM, like today. During interstadials, nutrient advection through freshwater inputs during autumn‐winter needs also to be considered to fully understand PP regimes. Key Points: Productivity (PP) in the Gulf of Cadiz is dependent on the seasonality control for both upwelling and nutrient‐enriched freshwater inputsWe show generally high PP, carbon export, and remineralization during the last glacial period at the study siteThe Last Glacial Maximum had lower Δδ13C than the Heinrich Stadials with sustained high PP likely allowing enhanced carbon sequestration [ABSTRACT FROM AUTHOR]

This study aimed to investigate serum levels of neurotrophins, including brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), nerve growth factor (NGF) and neurotrophin-3 (NTF3), and hypothalamic–pituitary–adrenal axis (HPA) members including adrenocorticotropic hormone (ACTH) and cortisol in children with obsessive–compulsive disorder (OCD). The possible relationships between serum neurotrophins and HPA axis members were also addressed. A total of 60 medication-free children with OCD and 57 controls aged 8–18 years were enrolled in this study. The severity of OCD symptoms was determined by the Children's Yale-Brown Obsessive Compulsive Scale. The severity of anxiety and depression symptoms were assessed by self-report inventories. The serum levels of neurotrophins, ACTH, and cortisol were measured using enzyme-linked immunosorbent assay kits. Serum BDNF levels were significantly higher in the OCD group than in the control group for either sex and for the whole sample. Compared to controls, serum ACTH levels were significantly higher in the OCD group for the whole sample. An analysis of covariance was also conducted for the whole sample and indicated that, while controlling the potential confounders, including body-mass index percentile, age, sex, and the severity of depression and anxiety, the results did not change. Strong negative correlations between BDNF, NGF and NTF3, and HPA axis members were determined in the patient group for either sex and for the whole sample. These findings suggest that dysregulations of BDNF and ACTH may be associated with childhood OCD. Furthermore, there may be inverse relationships between certain neurotrophins and HPA axis members in these patients. [ABSTRACT FROM AUTHOR]

Rationale: Palatability and incentive value influence animal food choice. Dopamine D2/3 receptor signaling may mediate the effects of palatability and incentive value on choice. Dopamine signaling is disrupted in attention-deficit hyperactivity disorder (ADHD). Investigating behavioral choice processes under D2/3 receptor agonists will help elucidate behavioral and pharmacological correlates of ADHD. Objectives: To determine (1) how changes in incentive value affects choice of actions for outcomes that differ in palatability; (2) the effects of the D2/3 agonist quinpirole on choice based on palatability and incentive value; (3) how choice differs in spontaneously hypertensive rats (SHR; ADHD model) compared with control strains. Methods: Rats responded instrumentally for two food outcomes (chocolate and grain pellets) that differed in palatability. Following specific satiety of one outcome, rats underwent a choice test. Prior to the choice test, rats were given intra-peritoneal quinpirole (0.01–0.1 mg/kg) body weight. These manipulations were conducted in three strains of rats: SHR rats; the normotensive Wistar-Kyoto (WKY) controls; and Wistar outbred (WIS) controls. Results: All rat strains responded more vigorously for chocolate pellets compared with grain pellets. Quinpirole reduced the effects of palatability and dose-dependently increased the effects of incentive value on choice. SHR rats were the least influenced by incentive value, whereas WKY rats were the least influenced by palatability. Conclusions: These results show that D2/3 signaling modulates choice based on palatability and incentive value. Disruption of this process in SHR rats may mirror motivational impairments observed in ADHD. [ABSTRACT FROM AUTHOR]

Habitual actions have a history of practice and repetition that frees us from attending to what we are doing. Nevertheless, habitual actions seem to be intentional. What does account for the intentionality of habitual actions if they are automatically performed and controlled? In this paper, we address a possible response to a particular version of this issue, that is, the problem of understanding how the intention to execute a habitual action, which comes in a propositional format, interlocks with motor representations, which come in a motoric-pragmatic format. In order to solve this issue, we propose an account according to which the propositional intentions and the motor representations related to our habitual actions interlock through executable action concepts. This allows us to maintain that habitual actions can be, at the same time, automatically initiated, performed, and controlled and, still, intentional. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) is a major cause of death and disability in children in both developed and developing nations. Children and adolescents suffer from TBI at a higher rate than the general population, and specific developmental issues require a unique context since findings from adult research do not necessarily directly translate to children. Findings in pediatric cohorts tend to lag behind those in adult samples. This may be due, in part, both to the smaller number of investigators engaged in research with this population and may also be related to changes in safety laws and clinical practice that have altered length of hospital stays, treatment, and access to this population. The ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Pediatric Moderate/Severe TBI (msTBI) group aims to advance research in this area through global collaborative meta-analysis of neuroimaging data. In this paper, we discuss important challenges in pediatric TBI research and opportunities that we believe the ENIGMA Pediatric msTBI group can provide to address them. With the paucity of research studies examining neuroimaging biomarkers in pediatric patients with TBI and the challenges of recruiting large numbers of participants, collaborating to improve statistical power and to address technical challenges like lesions will significantly advance the field. We conclude with recommendations for future research in this field of study. [ABSTRACT FROM AUTHOR]

Obesity is considered a global health problem affecting more than a third of the population. Complications of obesity include cardiovascular diseases, type 2 diabetes mellitus, malignancy (including prostatic cancer), neurodegeneration and accelerated ageing. In males, these further include erectile dysfunction, poor semen quality and subclinical prostatitis. Although poorly understood, important mediators of obesity that may influence the male reproductive system include hyperinsulinemia, hyperleptinemia, chronic inflammation and oxidative stress. Obesity is known to disrupt male fertility and the reproduction potential, particularly through alteration in the hypothalamic‐pituitary‐gonadal axis, disruption of testicular steroidogenesis and metabolic dysregulation, including insulin, cytokines and adipokines. Importantly, obesity and its underlying mediators result in a negative impact on semen parameters, including sperm concentration, motility, viability and normal morphology. Moreover, obesity inhibits chromatin condensation, DNA fragmentation, increases apoptosis and epigenetic changes that can be transferred to the offspring. This review discusses the impact of obesity on the male reproductive system and fertility, including associated mechanisms. Furthermore, weight management strategies, lifestyle changes, prescription medication, and complementary and alternative medicine in the management of obesity‐induced subfertility is discussed. [ABSTRACT FROM AUTHOR]

Previous studies showed that the cortical reward system plays an important role in deceptive behavior. However, how the reward system activates during the whole course of dishonest behavior and how it affects dishonest decisions remain unclear. The current study investigated these questions. One hundred and two participants were included in the final analysis. They completed two tasks: monetary incentive delay (MID) task and an honesty task. The MID task served as the localizer task and the honesty task was used to measure participants' deceptive behaviors. Participants' spontaneous responses in the honesty task were categorized into three conditions: Correct-Truth condition (tell the truth after guessing correctly), Incorrect-Truth condition (tell the truth after guessing incorrectly), and Incorrect-Lie condition (tell lies after guessing incorrectly). To reduce contamination from neighboring functional regions as well as to increase sensitivity to small effects (Powell et al., Devel Sci 21:e12595, 2018), we adopted the individual functional channel of interest (fCOI) approach to analyze the data. Specially, we identified the channels of interest in the MID task in individual participants and then applied them to the honesty task. The result suggested that the reward system showed different activation patterns during different phases: In the pre-decision phase, the reward system was activated with the winning of the reward. During the decision and feedback phase, the reward system was activated when people made the decisions to be dishonest and when they evaluated the outcome of their decisions. Furthermore, the result showed that neural activity of the reward system toward the outcome of their decision was related to subsequent dishonest behaviors. Thus, the present study confirmed the important role of the reward system in deception. These results can also shed light on how one could use neuroimaging techniques to perform lie-detection. [ABSTRACT FROM AUTHOR]

Background: Psychiatric disorders and related intermediate phenotypes are highly heritable and have a complex, overlapping polygenic architecture. A large-scale genome-wide association study (GWAS) of anxiety disorders identified genetic variants that are significant on a genome-wide. The current study investigated the genetic etiological overlaps between anxiety disorders and frequently cooccurring psychiatric disorders and intermediate phenotypes. Methods: Using case–control and factor score models, we investigated the genetic correlations of anxiety disorders with eight psychiatric disorders and intermediate phenotypes [the volumes of seven subcortical brain regions, childhood cognition, general cognitive ability and personality traits (subjective well-being, loneliness, neuroticism and extraversion)] from large-scale GWASs (n = 7556–298 420) by linkage disequilibrium score regression. Results: Among psychiatric disorders, the risk of anxiety disorders was positively genetically correlated with the risks of major depressive disorder (MDD) (rg ± standard error = 0.83 ± 0.16, p = 1.97 × 10−7), schizophrenia (SCZ) (0.28 ± 0.09, p = 1.10 × 10−3) and attention-deficit/hyperactivity disorder (ADHD) (0.34 ± 0.13, p = 8.40 × 10−3). Among intermediate phenotypes, significant genetic correlations existed between the risk of anxiety disorders and neuroticism (0.81 ± 0.17, p = 1.30 × 10−6), subjective well-being (−0.73 ± 0.18, p = 4.89 × 10−5), general cognitive ability (−0.23 ± 0.08, p = 4.70 × 10−3) and putamen volume (−0.50 ± 0.18, p = 5.00 × 10−3). No other significant genetic correlations between anxiety disorders and psychiatric or intermediate phenotypes were observed (p > 0.05). The case–control model yielded stronger genetic effect sizes than the factor score model. Conclusions: Our findings suggest that common genetic variants underlying the risk of anxiety disorders contribute to elevated risks of MDD, SCZ, ADHD and neuroticism and reduced quality of life, putamen volume and cognitive performance. We suggest that the comorbidity of anxiety disorders is partly explained by common genetic variants. [ABSTRACT FROM AUTHOR]

The mechanism producing enhanced thermal conductivities of nanofluids has been the subject of much debate. The formation of aggregates allowing for percolation paths within the fluid has shown the most promise. This work studies the aggregate formation of a nanofluid and compares the results to earlier thermal conductivity measurements and Monte Carlo simulation results. Static light scattering is employed to measure the fractal dimension of aggregates formed in the nanofluid over time at various temperatures and concentrations. As expected, aggregates form more quickly at higher concentrations and temperatures, which explains the increased enhancement with temperature reported by other research groups. The permanent aggregates in the nanofluid are found to have a fractal dimension of 2.4 and the aggregate formations that grow over time are found to have a fractal dimension of 1.8, which is consistent with diffusion limited aggregation. Predictions indicate that as aggregates grow the viscosity increases at a faster rate than thermal conductivity making the highly aggregated nanofluids unfavorable, especially at the low fractal dimension of 1.8. [ABSTRACT FROM AUTHOR]

Investigates the distribution of stresses in the shear-thinning regime using simulations of the flow of concentrated aggregated colloidal systems at a particulate level. Distribution of shear stress; Manifestation of the microstructural mechanisms associated with large stresses; Highest forces occurring towards the end of the shear thinning.

The direct imaging of flow induced microstructural changes in complex fluids can have advantages over the use of scattering methods, since localized phenomena can be observed directly and more mechanistic insights can be obtained. This is useful in particular for materials with hierarchical or multiscale structures such as aggregated dispersions. Rheoconfocal instruments are ideally suited for this purpose but were, as yet, limited to relatively low imaging rates. In the present work, a stress-controlled rheometer was coupled to a fast scanning, instant structured illumination confocal microscope which uses a multi-array illumination and detection scheme. A second motor is integrated in a custom-made rheoconfocal instrument to achieve the counter-rotation of the lower glass plate. The resulting stagnation plane can be moved within the shearing gap in real time and allows the stable imaging of micro-structural features under steady shear. Velocity profiles were measured to validate the performance of the mechanical components, using particle image velocimetry on a sterically stabilized suspension. Structured illumination optics yielded an excellent inplane spatial resolution, while the multipoint scanning allows speeds as high as 1000 frames per second at full frame resolution. However, for rheological studies the 3D structure should ideally be resolved. The mechanical refocusing using a fast piezo stage at high speeds led to deformations of the lower thin glass plate. To circumvent this bottleneck, a focus-tunable lens was incorporated in the setup to acquire 3D image volumes at video rates. The excellent combination of temporal and spatial resolution under flow is demonstrated here using selected results from aggregated colloidal dispersions. The microstructure of a model depletion gel is studied over a broad range of shear rates under strong to moderate flow conditions. The ability to measure rheological properties while imaging the time-dependent microstructure is demonstrated with particles dispersed in a more viscous PDMS matrix. Transient rheology is reported simultaneously with high resolution imaging of the microscopic structural recovery. This novel tool enables the direct imaging of rheologically complex materials under conditions relevant to processing, to elucidate the physical phenomena underlying nonlinear rheology and thixotropy. [ABSTRACT FROM AUTHOR]

In this article, we propose a new account concerning the interlock between intentions and motor representations (henceforth: MRs), showing that the interface problem is not as deep as previously proposed. Before discussing our view, in the first section we report the ideas developed in the literature by those who have tried to solve this puzzle before us. The article proceeds as follows. In Sections 2 and 3, we address the views by Butterfill and Sinigaglia, and Mylopoulos and Pacherie, respectively, and argue that both solutions entail a translation between representational formats, which both accounts aim to avoid. In Section 4, we present our brand‐new claim, according to which intentions and MRs partially share the same motor format, inasmuch as executable action concepts are naturally represented in the agent's motor system together with the action's outcomes. Indeed, since intentions are constituted by executable action concepts and since there is evidence that action concepts are represented (and, thus, built) in the same motor format as action outcomes, the interlock between intentions and MRs no longer constitutes a problem. Then, in Section 5, we report empirical evidence in support of our claim, and before concluding, in Section 6 we briefly clarify our relations with two very recent accounts that criticized the proposals by Mylopoulos and Pacherie and Butterfill and Sinigaglia: Shepherd's and Burnston's. Finally, in Section 7, we offer some remarks about the philosophical idea defended here. The basic insight is that interface without translation is possible because action concepts are such stuff as MRs are made on. [ABSTRACT FROM AUTHOR]

The viscosity of colloidal dispersions is a highly sensitive function of the microstructure of the dispersion and the nature of the interactions among the particles. While the viscosity of solutions of colloidal hard spheres is well understood, the viscosity in a broader array of colloidal solutions remains poorly studied. Here, we use immersed boundary simulations to investigate the viscosity of a prototypical colloidal solution, adhesive hard spheres, which under the right conditions can percolate to form sample spanning networks. We examine how rigidity of the particle–particle contacts in these dispersions can enhance the dispersion viscosity. By rigidly constraining a fraction of the adhered particles, we establish a reaction coordinate, the extent of rigidity, along which we can track the development of a gelled state characterized by a diverging viscosity. The fraction of rigid bonds is analogous to the extent of reaction for cross-linking in chemical gels, which suggests a close connection between chemical gelation with polymers and physical gelation with adhesive hard spheres. A critical gel point is identified when particles connected by rigid bonds begin to percolate the sample. In the vicinity of critical gel point, we observe a diverging viscosity and critical scaling behavior in agreement with previous studies on adhesive hard spheres. We use these results to formulate empirical equations for the viscosity across a broad range of volume fractions as a function of the extent of rigidity. Most importantly, through these simulations, we show that rigid constraints among the bonded particles are essential to producing the large viscosities measured experimentally in dispersions of adhesive hard spheres. Hydrodynamic interactions alone are insufficient for reproducing experimental observations. [ABSTRACT FROM AUTHOR]

A microrheological model of aggregating dispersions is proposed in which the shear stress is estimated as the sum of hydrodynamic and structural parts. The former is attributed to the hydrodynamic cores of fractal aggregates, which behave as a suspension of impermeable spheres. The latter accounts for the forces transmitted by chains of particles linking neighboring aggregates into a transient network. To calculate the structural part the concept of fractal aggregation is incorporated into a transient network theory, to account for the creation and breakup of chains of colloidal particles connecting the aggregates. Rigid and soft chains are distinguished. The former have multiply connected backbones which deform as contorted elastic rods, while the latter have at least one soft junction and deform without elastic resistance until fully loaded. The contribution of the soft chains to the stress tensor is neglected. The calculations treat two different mechanisms for the evolution of rigid chains: a purely mechanical one, which corresponds to a shear-controlled structure built up in flow, and a thermal mechanism, which pertains to a quasiequilibrium structure undisturbed by shear. We calculate steady-shear viscosities in the former case and viscoelastic functions in the latter. The model can be fitted satisfactorily to the experimental results for a well-characterized polystyrene latex dispersion with physically acceptable parameters. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We experimentally study the behavior of suspensions of silica particles in aqueous solution. Despite many studies on these materials, the dependence of the overall rheological properties of the suspension on particle size, solid volume fraction, ionic strength, and strain history remains debated. In this paper, we manage to manufacture materials and develop procedures that allow us (i) to approach this problem in the best possible way and (ii) to check that the results obtained with well controlled systems (monodisperse silica spherical particles) also apply to less controlled suspensions (crushed silica particles). We find that the elastic modulus-particle size and yield stress-particle size relationships follow power laws that disagree with classical models from the literature. We also show that elastic modulus versus yields stress data fall on a single master curve when rescaled by particle size, whatever are solid volume fraction, resting time, and ionic strength. This suggests that the rescaled elastic modulus can play the role of a parameter in a structural kinetics model of the behavior of thixotropic suspensions. Furthermore confocal observations of the system provided evidence that the evolution of the overall properties of the material with resting time cannot be ascribed to changes in the particle network. [ABSTRACT FROM AUTHOR]

We deal with scaling relations based on fractal theory and rheological properties of a colloidal suspension to determine a structure parameter of colloidal aggregates and thereby predict shear viscosity of the colloidal suspension using an effective-medium model. The parameter denoted by β is m(3-df), where m indicates shear rate (D) dependence of aggregate size R, i.e.R∝D−m, and df is the fractal dimension for the aggregate. A scaling relation between yield stress and particle volume fraction φ is applied to a set of experimental data for colloidal suspensions consisting of 0.13 μm zinc oxide and hydroxyethyl acrylate at φ = 0.01-0.055 to determine β. Another scaling relation between intrinsic viscosity and shear rate is used at lower φ than the relation for the yield stress. It is found that the estimations of β from the two relations are in a good agreement. The parameter β is utilized in establishing rheological models to predict shear viscosity of aggregated suspension as a function of φ and D. An effective-medium (EM) model is employed to take hydrodynamic interaction between aggregates into account. Particle concentration dependence of the suspension viscosity which is given in terms of volume fraction of aggregates φa instead of φ is incorporated to the EM model. It is found that the EM model combined with Quemada’s equation is quite successful in predicting shear viscosity of aggregated suspension. [ABSTRACT FROM AUTHOR]

Gelling colloidal suspensions represent an important class of soft materials. Their mechanical response is characterized by a solid-to-liquid transition at a given shear stress level. Moreover, they often exhibit a complex time-dependent rheological behavior known as thixotropy. The viscosity changes find their origin in the microstructure, which depends on flow history. Yet, the structural response of colloidal gels to flow differs fundamentally from most complex fluids, where flow induces orientation. Upon yielding, low to intermediate volume fraction gels break down in a spatially anisotropic way. Bonds in the velocity-velocity gradient plane are broken, whereas microstructural features in other planes are less affected. The subsequent flow-induced microstructural anisotropy is characterized by typical butterfly scattering patterns. However, as yet there was no evidence for the pertinence of this anisotropy for the rheological properties of these systems. In the present work, orthogonal superposition rheometry was first used to evaluate how the flow-induced microstructure affects the viscoelastic properties. It was shown to retain significant elasticity in the velocity-vorticity plane, even when the structure liquefied. Further, the shearinduced mechanical anisotropy was measured using two-dimensional small amplitude oscillatory shear, exploiting the fact that for suitable thixotropic samples the recovery after arresting the flow is relatively slow. It was hence possible to measure the anisotropy of the moduli upon cessation of flow. The mechanical anisotropy was shown to be spectacular, with the storage moduli in perpendicular directions differing by as much as 2 orders of magnitude. [ABSTRACT FROM AUTHOR]

There is considerable evidence that language comprehenders derive lexical-semantic meaning by mentally simulating perceptual and motor attributes of described events. However, the nature of these simulations-including the level of detail that is incorporated and contexts under which simulations occur-is not well understood. Here, we examine the effects of first- versus third-person perspective on mental simulations during sentence comprehension. First-person sentences describing physical transfer towards or away from the body (e.g., ' You threw the microphone,' ' You caught the microphone') modulated response latencies when responses were made along a front-back axis, consistent with the action-sentence compatibility effect ( ACE). This effect was not observed for third-person sentences (' He threw the microphone,' 'He caught the microphone'). The ACE was observed when making responses along a left-right axis for third-person, but not first-person sentences. Abstract sentences (e.g., ' He heard the message') did not show an ACE along either axis. These results show that perspective is a detail that is simulated during action sentence comprehension, and that motoric activations are flexible and affected by the pronominal perspective used in the sentence. [ABSTRACT FROM AUTHOR]

Objectives: A wealth of studies provide evidence for action simulation during language comprehension. Recent research suggests such action simulations might be sensitive to fine-grained information, such as speed. Here, we present a crucial test for action simulation of speed in language by assessing speed comprehension in patients with Parkinson’s disease (PD). Based on the patients’ motor deficits, we hypothesized that the speed of motion described in language would modulate their performance in semantic tasks. Specifically, they would have more difficulty processing language about relatively fast speed than language about slow speed. Methods: We conducted a semantic similarity judgment task on fast and slow action verbs in patients with PD and age-matched healthy controls. Participants had to decide which of two verbs most closely matched a target word. Results: Compared to controls, PD patients were slower making judgments about fast action verbs, but not for judgments about slow action verbs, suggesting impairment in processing language about fast action. Moreover, this impairment was specific to verbs describing fast action performed with the hand. Conclusions: Problems moving quickly lead to difficulties comprehending language about moving quickly. This study provides evidence that speed is an important part of action representations. (JINS, 2017, 23, 412–420) [ABSTRACT FROM PUBLISHER]

Embodied cognition posits that abstract conceptual knowledge such as mental representations of time and space are at least partially grounded in sensorimotor experiences. If true, then the execution of whole-body movements should result in modulations of temporal and spatial reference frames. To scrutinize this hypothesis, in two experiments participants either walked forward, backward or stood on a treadmill and responded either to an ambiguous temporal question (Experiment 1) or an ambiguous spatial question (Experiment 2) at the end of the walking manipulation. Results confirmed the ambiguousness of the questions in the control condition. Nevertheless, despite large power, walking forward or backward did not influence the answers or response times to the temporal (Experiment 1) or spatial (Experiment 2) question. A follow-up Experiment 3 indicated that this is also true for walking actively (or passively) in free space (as opposed to a treadmill). We explore possible reasons for the null-finding as concerns the modulation of temporal and spatial reference frames by movements and we critically discuss the methodological and theoretical implications. [ABSTRACT FROM AUTHOR]

This contribution explores the hypothesis that the rise of social media use and smartphone possession since 2007 contributed substantially to the international decrease in juvenile crime. The author addresses three processes that aid in understanding how social media and smartphones may have contributed to decreasing juvenile crime statistics. First, activity patterns of young people may have been altered in such a way that substantial less time is spent with unstructured socializing in public places. Second, the rise of social media may have led to additional and alternative possibilities to fulfill psychological and social needs of adolescents, taking away many immaterial motivations for juvenile crime. Third, it is possible that social media and smartphone use have facilitated a shift from offline to online juvenile crime, which is less detected and visible in official crime figures. While these theoretical arguments make the hypothesis plausible, research is needed to provide empirical evidence on the role of social media and smartphones in juvenile crime. [ABSTRACT FROM AUTHOR]

We propose a rheological model for ideal thixotropy, defined as a reversible time-dependent shear-thinning viscous response, in both shearrate- controlled (RC Model) and stress-controlled (SC Model) forms. The model introduces a spectrum of structure parameters that collectively relaxes as a stretched exponential. It retains time-invariance symmetry with only a stretching exponent β as an additional model parameter relative to conventional single-structure-parameter models. The kinetic equations are nonlinear in both the structure parameters and the flow parameters of strain rate or stress. We demonstrate that introducing multiple structure parameters can successfully capture the stretched-exponential and nonmonotonic evolution of stress or shear rate in general step tests; and using nonlinear kinetic equations can explain the relaxation time's dependence on both the initial and final values of shear rate or stress in step tests. We present rheological data for a fumed silica dispersion in a number of shear histories including steady state, step shear rate, step stress, shear-rate ramp, and stress ramp. A systematic way to parameterize the models is provided. Both models fit experimental data well although the SC Model provides better agreement with the measurements. The ideal thixotropic models can be combined with existing methods that incorporate viscoelasticity so as to extend their validity into the region of low shear rates. [ABSTRACT FROM AUTHOR]

Colloidal aggregates in a suspension of carbon black particles are characterized by fractal dimension and their shear dependence. Carbon black particles of 100 nm in diameter are dispersed in Newtonian ethylene glycol with particle volume fraction ϕ ranging from 0.01 to 0.1. Microstructure of the aggregates is estimated by hydrodynamic transport properties such as average settling velocity and shear viscosity. Scaling analysis is conducted to correlate the hydrodynamic transport properties and the fractal dimension d . The fractal dimension is estimated to be 2.21 from the scaling relation between the settling velocity and the particle volume fraction for ϕ = 0.01-0.05. The shear viscosity results show shear-thinning behavior of the colloidal suspension. The intrinsic viscosity for the colloidal aggregates is obtained from the data of shear viscosity versus particle concentration. A scaling relation between the intrinsic viscosity and the shear rate gives d = 1.93 at m = 1/3, where m is the exponent defined by a scaling relation between aggregate radius R and shear rate S, R ∝ S . Another scaling relation using yield stress data presents d = 1.94, which is nearly equivalent to 1.93 from that by the intrinsic viscosity but quite lower than that from the settling velocity. This discrepancy of the fractal dimension can be attributed to growth or restructuring of the colloidal aggregates by the hydrodynamic stress during long-time settling process. [ABSTRACT FROM AUTHOR]

Introduction: Many clinical studies have shown that performance of subjects with attention-deficit/hyperactivity disorder (ADHD) is impaired when stimuli are presented at a slow rate compared to a medium or fast rate. According to the cognitive–energetic model, this finding may reflect difficulty in allocating sufficient effort to regulate the motor activation state. Other studies have shown that the left hemisphere is relatively responsible for keeping humans motivated, allocating sufficient effort to complete their tasks. This leads to a prediction that poor effort allocation might be associated with an affected left-hemisphere functioning in ADHD. So far, this prediction has not been directly tested, which is the aim of the present study.Method: Seventy-seven adults with various scores on the Conners’ Adult ADHD Rating Scale performed a lateralized lexical decision task in three conditions with stimuli presented in a fast, a medium, and a slow rate. The left-hemisphere functioning was measured in terms of visual field advantage (better performance for the right than for the left visual field).Results: All subjects showed an increased right visual field advantage for word processing in the slow presentation rate of stimuli compared to the fast and the medium rate. Higher ADHD scores were related to a reduced right visual field advantage in the slow rate only.Conclusions: The present findings suggest that ADHD symptomatology is associated with less involvement of the left hemisphere when extra effort allocation is needed to optimize the low motor activation state. [ABSTRACT FROM PUBLISHER]