pinecone/core-2020-05-10-deduplication huggingface dataset:
Large flow shears around auroral beads at substorm onset

We present a fine-scale electrodynamic structure behind the auroral beads observed immediately before substorm onset, as inferred from high spatial and temporal resolution measurements of substorm with an all-sky TV camera (ATV) and a coherent high frequency radar of Super Dual Auroral Radar Network in Iceland. On the night of 24 September 2006, the ATV observed eastward propagating auroral beads in the initial brightening arc of a substorm just prior to the poleward expansion. During the sequential passage of the beads across the radar beams, the radar detected large velocity flow shears whose magnitude was in excess of 0.27 s[superscript −1]. The observations suggest that flow shears were located very close to the center of the beads; thus, they corresponded to electric fields converging toward the beads, which is consistent with the existence of upward field-aligned currents (FACs) flowing out of the beads. The temporal and spatial resolutions of the current radar measurement were still insufficient for fully resolving the detailed electrodynamic structure behind the fast moving auroral beads. At least, however, we can suggest the existence of highly localized filamentary FAC structures behind the beads, which would be an important consequence of possible plasma instabilities operating in the M-I coupling region or near the equatorial plane of the magnetosphere.STFC ST/H002480/1Peer-reviewedPublisher Versio
Characterization of nucleation during laboratory earthquakes

We observe the nucleation phase of in-plane ruptures in the laboratory. We show that the nucleation is composed of two distinct phases, a quasi-static and an acceleration stage, followed by dynamic propagation. We propose an empirical model which describes the rupture length evolution: The quasi-static phase is described by an exponential growth while the acceleration phase is described by an inverse power law of time. The transition from quasi-static to accelerating rupture is related to the critical nucleation length, which scales inversely with normal stress in accordance with theoretical predictions, and to a critical surfacic power, which may be an intrinsic property of the interface. Finally, we discuss these results in the frame of previous studies and propose a scaling up to natural earthquake dimensions.Peer-reviewedPublisher Versio
Seismic transect across the Lomonosov and Mendeleev Ridges:\ud
Constraints on the geological evolution of the Amerasia Basin,\ud
Arctic Ocean

We report on seismic and petrological data that provide\ud
new constraints on the geological evolution of the Amerasia\ud
Basin. A seismic reflection transect across theMakarov Basin,\ud
located between the Mendeleev and Lomonosov Ridges,\ud
shows a complete undisturbed sedimentary section of\ud
Mesozoic/Cenozoic age. In contrast to the Mendeleev\ud
Ridge, the margin of the Lomonosov Ridge is wide and\ud
shows horst and graben structures. We suggest that the\ud
Mendeleev Ridge is most likely volcanic in origin and\ud
support this finding with a 40Ar/39Ar isotopic age for a\ud
tholeiitic basalt sampled from the central Alpha/Mendeleev\ud
Ridge. Seismic reflection data for the Makarov Basin show\ud
no evidence of compressional features, consistent with the\ud
Lomonosov Ridge moving as a microplate in the Cenozoic.\ud
We propose that the Amerasia Basin moved as a single\ud
tectonic plate during the opening of the Eurasia Basi
The multiple spots of the Ganymede auroral footprint

International audienceThe interaction between the moons and the magnetosphere of giant planets sometimes gives rise to auroral signatures in the planetary ionosphere, called the satellite footprints. So far, footprints have been detected for Io, Europa, Ganymede and Enceladus. These footprints are usually seen as single spots. However, the Io footprint, the brightest one, displays a much more complex morphology made of at least three different spots and an extended tail. Here, we present Hubble Space Telescope FUV images showing evidence for a second spot in the Ganymede footprint. The spots separation distance changes as Ganymede moves latitudinally in the plasma sheet, as is seen for the Io footprint. This indicates that the processes identified at Io are universal. Moreover, for similar Ganymede System III longitudes, the distance may also vary significantly with time, indicating changes in the plasma sheet density. We identified a rapid evolution of this distance ~8 days after the detection of a volcanic outburst at Io, suggesting that such auroral observations could be used to estimate the plasma density variations at Ganymede
Combining AIRS and MLS observations for three-dimensional gravity wave measurement

Gravity waves play a critical role in transporting energy and momentum between the troposphere, stratosphere, and mesosphere. Satellite measurements provide a powerful tool to investigate these waves across the globe. However, many present methods cannot yield reliable estimates of wave momentum fluxes or the directions of these fluxes. Here we present a new method which addresses this problem by combining observations from Atmospheric Infrared Sounder (AIRS) and Microwave Limb Sounder (MLS) in three dimensions. The method allows direct estimation of horizontal and vertical wavelengths as well as wave amplitude. This in turn allows estimation of both wave momentum flux and the full 3-D direction of propagation, crucially including the horizontal direction. The method thus allows separation of the data into, for example, eastward and westward momentum fluxes, allowing estimation of the net atmospheric forcing due to these waves. We illustrate this method with a proof-of-concept study over the Andes, arguably the largest source of gravity waves in the world. We further critically assess the advantages and disadvantages of our method. Our study highlights the importance of the difference between net and absolute measures of momentum flux
In the right place at the right time! The influence of knowledge governance tools on knowledge transfer and utilization in MNEs

This is the author’s accepted and refereed manuscript to the articleThis article examines the utilization of knowledge transferred between sending and receiving subsidiaries within multinational enterprises. A model was developed and tested on 169 specific knowledge transfer projects. The model explains the utilization of knowledge subject to transfer in terms of hierarchical governance tool efficacy and lateral relationships within the multinational enterprise. The results show that headquarters’ involvement during knowledge development does not have any significant impact on subsequent knowledge utilization in the receiving units and, in fact, hierarchical governance forms have a negative impact on knowledge utilization. However, lateral relationships are positive stimuli to building subsidiary capabilities in the knowledge transfer process that enhance receiving unit knowledge utilization.1, Forfatterversjo
The Mutual Impact of Global Strategy and Organizational Learning: Current Themes and Future Directions

Despite the interest in issues of knowing and learning in the global strategy field, there has been limited mutual engagement and interaction between the fields of global strategy and organizational learning. The purpose of our article is to reflect on and articulate how the mutual exchange of ideas between these fields can be encouraged. To this end, we first conduct a review of the intersection of the fields of global strategy and organizational learning. We then present two recommendations regarding how the interaction between the two fields can be enhanced. Our first recommendation is for global strategy research to adopt a broader notion of organizational learning. Our second recommendation is for global strategy research to capitalize on its attention to context in order to inform and enhance organizational learning theory. We discuss the use of context in a number of common research designs and highlight how the scope for theoretical contributions back to organizational learning varies with the research design that is adopted
Child safety, absolute risk, and the prevention paradox

While child-saftey proposals aim to improve child safety, their possible impact is unclear since there’s been so little discussion of the amount of absolute risk and risk reduction involved in each.  And while precise figures are lacking, rough estimates indicate that the magnitudes are quite small.  I will argue that this risk and benefit data raises important questions about the proposals, including whether parents might reasonably believe that the small absolute risk reduction offered by the proposed changes does not justify the attendant burdens.  This possibility – termed the “prevention paradox” in other contexts – highlights ethical and theoretical challenges in this area of public health
Institutional Ethics Resources: Creating Moral Spaces

Since 1992, institutions accredited by The Joint Commission have been required to have a process in place that allows staff members, patients, and families to address ethical issues or issues prone to conflict. While the commission's expectations clearly have made ethics committees more common, simply having a committee in no way demonstrates its effectiveness in terms of the availability of the service to key constituents, the quality of the processes used, or the outcomes achieved. Beyond meeting baseline accreditation standards, effective ethics resources are requisite for quality care for another reason. The provision of care to the sick is a practice with profound moral dimensions. Clinicians need what Margaret Urban Walker has called “moral spaces,” reflective spaces within institutions in which to explore and communicate values and ethical obligations as they undergird goals of care. Walker proposed that ethicists needed to be concerned with the design and maintenance of these moral spaces. Clearly, that concern needs to extend beyond ethicists to institutional leaders. This essay uses Walker's idea of moral space to describe individuals and groups who are actual and potential ethics resources in health care institutions. We focus on four requisite characteristics of effective resources and the challenges to achieving them, and we identify strategies to build them. In our view, such moral spaces are particularly important for nurses and their colleagues on interprofessional teams and need to be expanded and strengthened in most settings
Robust Bayesian estimation of the hemodynamic response function in event-related BOLD fMRI using basic physiological information.

International audienceIn BOLD fMRI data analysis, robust and accurate estimation of the Hemodynamic Response Function (HRF) is still under investigation. Parametric methods assume the shape of the HRF to be known and constant throughout the brain, whereas non-parametric methods mostly rely on artificially increasing the signal-to-noise ratio. We extend and develop a previously proposed method that makes use of basic yet relevant temporal information about the underlying physiological process of the brain BOLD response in order to infer the HRF in a Bayesian framework. A general hypothesis test is also proposed, allowing to take advantage of the knowledge gained regarding the HRF to perform activation detection. The performances of the method are then evaluated by simulation. Great improvement is shown compared to the Maximum-Likelihood estimate in terms of estimation error, variance, and bias. Robustness of the estimators with regard to the actual noise structure or level, as well as the stimulus sequence, is also proven. Lastly, fMRI data with an event-related paradigm are analyzed. As suspected, the regions selected from highly discriminating activation maps resulting from the method exhibit a certain inter-regional homogeneity in term of HRF shape, as well as noticeable inter-regional differences
Method for bias field correction of brain T1-weighted magnetic resonance images minimizing segmentation error

This work presents a new algorithm (nonuniform intensity correction; NIC) for correction of intensity inhomogeneities in T1-weighted magnetic resonance (MR) images. The bias field and a bias-free image are obtained through an iterative process that uses brain tissue segmentation. The algorithm was validated by means of realistic phantom images and a set of 24 real images. The first evaluation phase was based on a public domain phantom dataset, used previously to assess bias field correction algorithms. NIC performed similar to previously described methods in removing the bias field from phantom images, without introduction of degradation in the absence of intensity inhomogeneity. The real image dataset was used to compare the performance of this new algorithm to that of other widely used methods (N3, SPM'99, and SPM2). This dataset included both low and high bias field images from two different MR scanners of low (0.5 T) and medium (1.5 T) static fields. Using standard quality criteria for determining the goodness of the different methods, NIC achieved the best results, correcting the images of the real MR dataset, enabling its systematic use in images from both low and medium static field MR scanners. A limitation of our method is that it might fail if the bias field is so high that the initial histogram does not show bimodal distribution for white and gray matterPublicad
Nonlinear analysis of EEG during NREM sleep reveals changes in functional connectivity due to natural aging

This is a preprint of an article accepted for publication in the journal, Human Brain Mapping. The definitive version is available online from WileyInterScience at: http://www3.interscience.wiley.com/cgi-bin/jhome/38751The spatial organization of nonlinear interactions between different brain regions\ud
during the first NREM sleep stage is investigated. This is achieved via consideration\ud
of four bipolar electrode derivations, Fp1F3, Fp2F4, O1P3, O2P4, which are used to compare\ud
anterior and posterior interhemispheric interactions and left and right intrahemispheric\ud
interactions. Nonlinear interdependence is detected via application of a previously written\ud
algorithm, along with appropriately generated surrogate data sets. It is now well understood\ud
that the output of neural systems does not scale linearly with inputs received and thus\ud
the study of nonlinear interactions in EEG is crucial. This approach also offers significant\ud
advantages over standard linear techniques, in that the strength, direction and topography\ud
of the interdependencies can all be calculated and considered. Previous research has linked\ud
delta activity during the first NREM sleep stage to performance on frontally-activating tasks\ud
during wake. In the current paper, it is demonstrated that nonlinear mechanisms are the\ud
driving force behind this delta activity. Furthermore, evidence is presented to suggest that\ud
the ageing brain calls upon the right parietal region to assist the pre-frontal cortex. This is\ud
highlighted by statistically significant differences in the rates of communication between the\ud
left pre-frontal cortex and the right parietal region when comparing younger subjects (< 23\ud
years) with older subjects (> 60 years). This assistance has been observed in brain imaging\ud
studies of sleep deprived young adults, suggesting that similar mechanisms may play a role in\ud
the event of healthy aging. Additionally, the contribution to the delta rhythm via nonlinear\ud
mechanisms is observed to be greater in older subjects
Genetic components of functional connectivity in the brain: the heritability of synchronization likelihood

Cognitive functions require the integrated activity of multiple specialized, distributed brain areas. Such functional coupling depends on the existence of anatomical connections between the various brain areas as well as physiological processes whereby the activity in one area influences the activity in another area. Recently, the Synchronization Likelihood (SL) method was developed as a general method to study both linear and nonlinear aspects of coupling. In the present study the genetic architecture of the SL in different frequency bands was investigated. Using a large genetically informative sample of 569 subjects from 282 extended twin families we found that the SL is moderately to highly heritable (41-67%) especially in the alpha frequency (8-13 Hz) range. This index of functional connectivity of the brain has been associated with a number of pathological states of the brain. The significant heritability found here suggests that SL can be used to examine the genetic susceptibility to these condition
Neural Circuits Subserving the Retrieval of Stems and Grammatical Features in Regular and Irregular Verbs

Many languages, including English and Spanish, feature regular (dance 3 danced) and irregular (catch 3 caught) inﬂectional systems. According to psycholinguistic theories, regular and irregular inﬂections are instantiated either by a single or by two specialized mechanisms. Those theories differ in their assumptions concerning the underlying information necessary for the processing of regular verbs. Whereas single mechanism accounts have stated an increased involvement of phonological processing for regular verbs, dual accounts emphasize the prominence of grammatical information. Using event-related functional magnetic resonance imaging, we sought to delineate the brain areas involved in the generation of complex verb forms in Spanish. This language has the advantage of isolating speciﬁc differences in the regular-irregular contrasts in terms of the number of stems associated with a verb while controlling for compositionality (regular and irregular verbs apply sufﬁxes to be inﬂected). The present study showed that areas related to grammatical processing are active for both types of verbs (left opercular inferior frontal gyrus). In addition, major differences between regular and irregular verbs were also observed. Several areas of the prefrontal cortex were selectively active for irregular production, presumably reﬂecting their role in lexical retrieval (bilateral inferior frontal area and dorsolateral prefrontal cortex). Regular verbs, however, showed increased activation in areas related to grammatical processing (anterior superior temporal gyrus/insular cortex) and in the left hippocampus, the latter possibly related to a greater implication of the phonological loop necessary for the reutilization of the same stem shared across all forms in regular verbs
Single Dose of a Dopamine Agonist Impairs Reinforcement Learning in Humans: Evidence from Event-related Potentials and Computational Modeling of Striatal-Cortical Function

Animal findings have highlighted the modulatory role of phasic dopamine (DA) signaling in incentive learning, particularly in the acquisition of reward-related behavior. In humans, these processes remain largely unknown. In a recent study, we demonstrated that a single low dose of a D2/D3 agonist (pramipexole) - assumed to activate DA autoreceptors and thus reduce phasic DA bursts - impaired reward learning in healthy subjects performing a probabilistic reward task. The purpose of this study was to extend these behavioral findings using event-related potentials and computational modeling. Compared with the placebo group, participants receiving pramipexole showed increased feedback-related negativity to probabilistic rewards and decreased activation in dorsal anterior cingulate regions previously implicated in integrating reinforcement history over time. Additionally, findings of blunted reward learning in participants receiving pramipexole were simulated by reduced presynaptic DA signaling in response to reward in a neural network model of striatal-cortical function. These preliminary findings offer important insights on the role of phasic DA signals on reinforcement learning in humans and provide initial evidence regarding the spatiotemporal dynamics of brain mechanisms underlying these processes.Psycholog
Pseudohomophone effects provide evidence of early lexico-phonological processing in visual word recognition

Previous research using event-related brain potentials (ERPs) suggested that phonological processing in visual word recognition occurs rather late, typically after semantic or syntactic processing. Here, we show that phonological activation in visual word recognition can be observed much earlier. Using a lexical decision task, we show that ERPs to pseudohomophones (PsHs) (e.g., ROZE) differed from well-matched spelling controls (e.g., ROFE) as early as 150 ms (P150) after stimulus onset. The PsH effect occurred as early as the word frequency effect suggesting that phonological activation occurs early enough to influence lexical access. Low-resolution electromagnetic tomography analysis (LORETA) revealed that left temporoparietal and right frontotemporal areas are the likely brain regions associated with the processing of phonological information at the lexical level. Altogether, the results show that phonological processes are activated early in visual word recognition and play an important role in lexical access.Peer-reviewedPost-prin
Eye muscle proprioception is represented bilaterally in the sensorimotor cortex

The cortical representation of eye position is still uncertain. In the monkey a proprioceptive representation of the extraocular muscles (EOM) of an eye were recently found within the contralateral central sulcus. In humans, we have previously shown a change in the perceived position of the right eye after a virtual lesion with rTMS over the left somatosensory area. However, it is possible that the proprioceptive representation of the EOM extends to other brain sites, which were not examined in these previous studies. The aim of this fMRI study was to sample the whole brain to identify the proprioceptive representation for the left and the right eye separately. Data were acquired while passive eye movement was used to stimulate EOM proprioceptors in the absence of a motor command. We also controlled for the tactile stimulation of the eyelid by removing from the analysis voxels activated by eyelid touch alone. For either eye, the brain area commonly activated 
by passive and active eye movement was located bilaterally in the somatosensory area extending into the motor and premotor cytoarchitectonic areas. We suggest this is where EOM proprioception is processed. The bilateral representation for either eye contrasts with the contralateral representation of hand proprioception. We suggest that the proprioceptive representation of the two eyes next to each other in either somatosensory cortex and extending into the premotor cortex reflects the integrative nature of the eye position sense, which combines proprioceptive information across the two eyes with the efference copy of the oculomotor comman