Beyond the second order magnetic anisotropy tensor: Higher-order components due to oriented magnetite exsolutions in pyroxenes, and implications for paleomagnetic and structural interpretations

Exsolved iron oxides in silicate minerals can be nearly ideal paleomagnetic recorders, due to their single-domain-like behaviour and the protection from chemical alteration by their surrounding silicate host. Because their geometry is crystallographically controlled by the host silicate, these exsolutions possess a shape preferred orientation that is ultimately controlled by the mineral fabric of the silicates. This leads to potentially significant anisotropic acquisition of remanence, which necessitates correction to make accurate interpretations in paleodirectional and paleointensity studies. Here, we investigate the magnetic shape anisotropy carried by magnetite exsolutions in pyroxene single crystals, and in pyroxene-bearing rocks based on torque measurements and rotational hysteresis data. Image analysis is used to characterize the orientation distribution of oxides, from which the observed anisotropy can be modelled. Both the high-field torque signal and corresponding models contain components of higher order, which cannot be accurately described by second order tensors usually employed to describe magnetic fabrics. Conversely, low-field anisotropy data do not show this complexity and can be adequately described with second-order tensors. Hence, magnetic anisotropy of silicate-hosted exsolutions is field-dependent and this should be taken into account when interpreting isolated ferromagnetic fabrics, and in anisotropy corrections

Arl13b in Primary Cilia Regulates the Migration and Placement of Interneurons in the Developing Cerebral Cortex

Coordinated migration and placement of interneurons and projection neurons lead to functional connectivity in the cerebral cortex; defective neuronal migration and the resultant connectivity changes underlie the cognitive defects in a spectrum of neurological disorders. Here we show that primary cilia play a guiding role in the migration and placement of postmitotic interneurons in the developing cerebral cortex, and that this process requires the ciliary protein, Arl13b. Through live imaging of interneuronal cilia we show migrating interneurons display highly dynamic primary cilia and we correlate cilia dynamics with the interneuron’s migratory state. We demonstrate that the guidance cue receptors essential for interneuronal migration localize to interneuronal primary cilia, but their concentration and dynamics are altered in the absence of Arl13b. Expression of Arl13b variants known to cause Joubert syndrome induce defective interneuronal migration, suggesting that defects in cilia-dependent interneuron migration may underlie the neurological defects in Joubert syndrome patients

Arl13b-regulated cilia activities are essential for polarized radial glial scaffold formation

The construction of cerebral cortex begins with the formation of radial glia. Once formed, polarized radial glial cells divide either symmetrically or asymmetrically to balance appropriate production of progenitor cells and neurons. Upon birth, neurons use the processes of radial glia as scaffolding for oriented migration. Radial glia thus provide an instructive structural matrix to coordinate the generation and placement of distinct groups of cortical neurons in the developing cerebral cortex. Here we show that Arl13b, a cilia-specific small GTPase mutated in Joubert syndrome patients, is critical for the initial formation of the polarized radial progenitor scaffold. Through developmental stage-specific deletion of Arl13b in mouse cortical progenitors, we found that early neuroepithelial deletion of ciliary Arl13b leads to a reversal in the apical-basal polarity of radial progenitors and aberrant neuronal placement. Arl13b modulates ciliary signaling necessary for radial glial polarity. Our findings demonstrate that Arl13b signaling in primary cilia is important for the initial formation of a polarized radial glial scaffold and suggest that disruption of this process may contribute to aberrant neurodevelopment and brain abnormalities in Joubert syndrome-related ciliopathies

Towards estimating affective states in Virtual Reality based on behavioral data

Inferring users' perceptions of Virtual Environments (VEs) is essential for Virtual Reality (VR) research. Traditionally, this is achieved through assessing users' affective states before and after being exposed to a VE, based on standardized, self-assessment questionnaires. The main disadvantage of questionnaires is their sequential administration, i.e. a user's affective state is measured asynchronously to its generation within the VE. A synchronous measurement of users' affective states would be highly favorable, e.g. in the context of adaptive systems. Drawing from nonverbal behavior research, we argue that behavioral measures could be a powerful approach to assess users' affective states in VR. In this paper, we contribute by providing methods and measures evaluated in a user study involving 42 participants to assess a users' affective states by measuring head movements during VR exposure. We show that head yaw significantly correlates with presence, mental and physical demand, perceived performance, and system usability. We also exploit the identified relationships for two practical tasks that are based on head yaw: i) predicting a user's affective state, and ii) detecting manipulated questionnaire answers, i.e. answers that are possibly non-truthful. We found that affective states can be predicted significantly better than a naive estimate for mental demand, physical demand, perceived performance, and usability. Further, manipulated or non-truthful answers can also be estimated significantly better than by a naive approach. These findings mark an initial step in the development of novel methods to assess user perception of VEs.ISSN:1434-9957ISSN:1359-433

Political Ideology and Executive Functioning: The Effect of Conservatism and Liberalism on Cognitive Flexibility and Working Memory Performance

Although models of political ideology traditionally focus on the motivations that separate conservatives and liberals, a growing body of research is directly exploring the cognitive factors that vary due to political ideology. Consistent with this emerging literature, the present research proposes that conservatives and liberals excel at tasks of distinct working memory processes (i.e., inhibition and updating, respectively). Consistent with this hypothesis, three studies demonstrate that conservatives are more likely to succeed at response inhibition and liberals are more likely to succeed at response updating. Moreover, this effect is rooted in different levels of cognitive flexibility and independent of respondents’ demographics, intelligence, religiosity, and motivation. Collectively, these findings offer an important perspective on the cognitive factors that delineate conservatism and liberalism, the role of cognitive flexibility in specific working memory processes, and the impact of political ideology on a multitude of behaviors linked to inhibition and updating (e.g., creativity, problem-solving, self-control)

Political Ideology and Executive Functioning: The Effect of Conservatism and Liberalism on Cognitive Flexibility and Working Memory Performance

Although models of political ideology traditionally focus on the motivations that separate conservatives and liberals, a growing body of research is directly exploring the cognitive factors that vary due to political ideology. Consistent with this emerging literature, the present research proposes that conservatives and liberals excel at tasks of distinct working memory processes (i.e., inhibition and updating, respectively). Consistent with this hypothesis, three studies demonstrate that conservatives are more likely to succeed at response inhibition and liberals are more likely to succeed at response updating. Moreover, this effect is rooted in different levels of cognitive flexibility and independent of respondents’ demographics, intelligence, religiosity, and motivation. Collectively, these findings offer an important perspective on the cognitive factors that delineate conservatism and liberalism, the role of cognitive flexibility in specific working memory processes, and the impact of political ideology on a multitude of behaviors linked to inhibition and updating (e.g., creativity, problem-solving, self-control)

The self-control consequences of political ideology

Evidence from three studies reveals a critical difference in self-control as a function of political ideology. Specifically, greater endorsement of political conservatism (versus liberalism) was associated with greater attention regulation and task persistence. Moreover, this relationship is shown to stem from varying beliefs in freewill; specifically, the association between political ideology and selfcontrol is mediated by differences in the extent to which belief in freewill is endorsed, is independent of task performance or motivation, and is reversed when freewill is perceived to impede (rather than enhance) self-control. Collectively, these findings offer insight into the self-control consequences of political ideology by detailing conditions under which conservatives and liberals are better suited to engage in self-control and outlining the role of freewill beliefs in determining these conditions

Indicators of Training Success in Virtual Reality Using Head and Eye Movements

An essential aspect in the evaluation of Virtual Training Environments (VTEs) is the assessment of users’ training success, preferably in real-time, e.g. to continuously adapt the training or to provide feedback. To achieve this, leveraging users’ behavioral data has been shown to be a valid option. Behavioral data include sensor data from eye trackers, head-mounted displays, and hand-held controllers, as well as semantic data like a trainee’s focus on objects of interest within a VTE. While prior works investigated the relevance of mostly one and in rare cases two behavioral data sources at a time, we investigate the benefits of the combination of three data sources. We conduct a user study with 48 participants in an industrial training task to find correlations between training success and measures extracted from different behavioral data sources. We show that all individual data sources, i.e. eye gaze position and head movement, as well as duration of objects in focus are related to training success. Moreover, we find that simultaneously considering multiple behavioral data sources allows to better explain training success. Further, we show that training outcomes can already be predicted significantly better than chance by only recording trainees for parts of their training. This could be used for dynamically adapting a VTE’s difficulty. Finally, our work further contributes to reaching the long-term goal of substituting traditional evaluation of training success (e.g. through pen-and-paper tests) with an automated approach

The self-control consequences of political ideology

Evidence from three studies reveals a critical difference in self-control as a function of political ideology. Specifically, greater endorsement of political conservatism (versus liberalism) was associated with greater attention regulation and task persistence. Moreover, this relationship is shown to stem from varying beliefs in freewill; specifically, the association between political ideology and self-control is mediated by differences in the extent to which belief in freewill is endorsed, is independent of task performance or motivation, and is reversed when freewill is perceived to impede (rather than enhance) self-control. Collectively, these findings offer insight into the self-control consequences of political ideology by detailing conditions under which conservatives and liberals are better suited to engage in self-control and outlining the role of freewill beliefs in determining these conditions