567 research outputs found
Imagined Self-Motion Differs from Perceived Self-Motion: Evidence from a Novel Continuous Pointing Method
Background The extent to which actual movements and imagined movements maintain a shared internal representation has been a matter of much scientific debate. Of the studies examining such questions, few have directly compared actual full-body movements to imagined movements through space. Here we used a novel continuous pointing method to a) provide a more detailed characterization of self-motion perception during actual walking and b) compare the pattern of responding during actual walking to that which occurs during imagined walking. Methodology/Principal Findings This continuous pointing method requires participants to view a target and continuously point towards it as they walk, or imagine walking past it along a straight, forward trajectory. By measuring changes in the pointing direction of the arm, we were able to determine participants' perceived/imagined location at each moment during the trajectory and, hence, perceived/imagined self-velocity during the entire movement. The specific pattern of pointing behaviour that was revealed during sighted walking was also observed during blind walking. Specifically, a peak in arm azimuth velocity was observed upon target passage and a strong correlation was observed between arm azimuth velocity and pointing elevation. Importantly, this characteristic pattern of pointing was not consistently observed during imagined self-motion. Conclusions/Significance Overall, the spatial updating processes that occur during actual self-motion were not evidenced during imagined movement. Because of the rich description of self-motion perception afforded by continuous pointing, this method is expected to have significant implications for several research areas, including those related to motor imagery and spatial cognition and to applied fields for which mental practice techniques are common (e.g. rehabilitation and athletics)
Electronic and phononic properties of cinnabar: ab initio calculations and some experimental results
We report ab initio calculations of the electronic band structure, the
corresponding optical spectra, and the phonon dispersion relations of trigonal
alpha-HgS (cinnabar). The calculated dielectric functions are compared with
unpublished optical measurements by Zallen and coworkers. The phonon dispersion
relations are used to calculate the temperature and isotopic mass dependence of
the specific heat which has been compared with experimental data obtained on
samples with the natural isotope abundances of the elements Hg and S (natural
minerals and vapor phase grown samples) and on samples prepared from isotope
enriched elements by vapor phase transport. Comparison of the calculated
vibrational frequencies with Raman and ir data is also presented. Contrary to
the case of cubic beta-HgS (metacinnabar), the spin-orbit splitting of the top
valence bands at the Gamma-point of the Brillouin zone (Delta_0) is positive,
because of a smaller admixture of 5d core electrons of Hg. Calculations of the
lattice parameters, and the pressure dependence of Delta_0 and the
corresponding direct gap E_0~2eV are also presented. The lowest absorption edge
is confirmed to be indirect.Comment: 13 pages, 15 figure
SpikeInterface, a unified framework for spike sorting
Much development has been directed toward improving the performance and automation of spike sorting. This continuous development, while essential, has contributed to an over-saturation of new, incompatible tools that hinders rigorous benchmarking and complicates reproducible analysis. To address these limitations, we developed SpikeInterface, a Python framework designed to unify preexisting spike sorting technologies into a single codebase and to facilitate straightforward comparison and adoption of different approaches. With a few lines of code, researchers can reproducibly run, compare, and benchmark most modern spike sorting algorithms; pre-process, post-process, and visualize extracellular datasets; validate, curate, and export sorting outputs; and more. In this paper, we provide an overview of SpikeInterface and, with applications to real and simulated datasets, demonstrate how it can be utilized to reduce the burden of manual curation and to more comprehensively benchmark automated spike sorters.ISSN:2050-084
Electronic, vibrational, and thermodynamic properties of ZnS (zincblende and rocksalt structure)
We have measured the specific heat of zincblende ZnS for several isotopic
compositions and over a broad temperature range (3 to 1100 K). We have compared
these results with calculations based on ab initio electronic band structures,
performed using both LDA and GGA exchange- correlation functionals. We have
compared the lattice dynamics obtained in this manner with experimental data
and have calculated the one-phonon and two-phonon densities of states. We have
also calculated mode Grueneisen parameters at a number of high symmetry points
of the Brillouin zone. The electronic part of our calculations has been used to
investigate the effect of the 3d core electrons of zinc on the spin-orbit
splitting of the top valence bands. The effect of these core electrons on the
band structure of the rock salt modification of ZnS is also discussed.Comment: 33pages, 16 Figures, submitted to Phys. Rev.
Early-life viral infection and allergen exposure interact to induce an asthmatic phenotype in mice
<p>Abstract</p> <p>Background</p> <p>Early-life respiratory viral infections, notably with respiratory syncytial virus (RSV), increase the risk of subsequent development of childhood asthma. The purpose of this study was to assess whether early-life infection with a species-specific model of RSV and subsequent allergen exposure predisposed to the development of features of asthma.</p> <p>Methods</p> <p>We employed a unique combination of animal models in which BALB/c mice were neonatally infected with pneumonia virus of mice (PVM, which replicates severe RSV disease in human infants) and following recovery, were intranasally sensitised with ovalbumin. Animals received low-level challenge with aerosolised antigen for 4 weeks to elicit changes of chronic asthma, followed by a single moderate-level challenge to induce an exacerbation of inflammation. We then assessed airway inflammation, epithelial changes characteristic of remodelling, airway hyperresponsiveness (AHR) and host immunological responses.</p> <p>Results</p> <p>Allergic airway inflammation, including recruitment of eosinophils, was prominent only in animals that had recovered from neonatal infection with PVM and then been sensitised and chronically challenged with antigen. Furthermore, only these mice exhibited an augmented Th2-biased immune response, including elevated serum levels of anti-ovalbumin IgE and IgG<sub>1 </sub>as well as increased relative expression of Th2-associated cytokines IL-4, IL-5 and IL-13. By comparison, development of AHR and mucous cell change were associated with recovery from PVM infection, regardless of subsequent allergen challenge. Increased expression of IL-25, which could contribute to induction of a Th2 response, was demonstrable in the lung following PVM infection. Signalling via the IL-4 receptor α chain was crucial to the development of allergic inflammation, mucous cell change and AHR, because all of these were absent in receptor-deficient mice. In contrast, changes of remodelling were evident in mice that received chronic allergen challenge, regardless of neonatal PVM infection, and were not dependent on signalling via the IL-4 receptor.</p> <p>Conclusion</p> <p>In this mouse model, interaction between early-life viral infection and allergen sensitisation/challenge is essential for development of the characteristic features of childhood asthma, including allergic inflammation and a Th2-biased immune response.</p
Lattice Dynamics and Specific Heat of - GeTe: a theoretical and experimental study
We extend recent \textit{ab initio} calculations of the electronic band
structure and the phonon dispersion relations of rhombohedral GeTe to
calculations of the density of phonon states and the temperature dependent
specific heat. The results are compared with measurements of the specific heat.
It is discovered that the specific heat depends on hole concentration, not only
in the very low temperature region (Sommerfeld term) but also at the maximum of
(around 16 K). To explain this phenomenon, we have performed
\textit{ab initio} lattice dynamical calculations for GeTe rendered metallic
through the presence of a heavy hole concentration ( 2
10 cm). They account for the increase observed in the maximum of
.Comment: 8 pages, 7 figures, ref. 19 correcte
Inequality, Fiscal Capacity and the Political Regime: Lessons from the Post-Communist Transition
Using panel data for twenty-seven post-communist economies between 1987-2003, we examine the nexus of relationships between inequality, fiscal capacity (defined as the ability to raise taxes efficiently) and the political regime. Investigating the impact of political reform we find that full political freedom is associated with lower levels of income inequality. Under more oligarchic (authoritarian) regimes, the level of inequality is conditioned by the stateâs fiscal capacity. Specifically, oligarchic regimes with more developed fiscal systems are able to defend the prevailing vested interests at a lower cost in terms of social injustice. This empirical finding is consistent with the model developed by Acemoglu (2006). We also find that transition countries undertaking early macroeconomic stabilisation now enjoy lower levels of inequality; we confirm that education fosters equality and the suggestion of Commander et al (1999) that larger countries are prone to higher levels of inequality.http://deepblue.lib.umich.edu/bitstream/2027.42/57211/1/wp831 .pd
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Purpose in life predicts better emotional recovery from negative stimuli
Purpose in life predicts both health and longevity suggesting that the ability to find meaning from lifeâs experiences, especially when confronting lifeâs challenges, may be a mechanism underlying resilience. Having purpose in life may motivate reframing stressful situations to deal with them more productively, thereby facilitating recovery from stress and trauma. In turn, enhanced ability to recover from negative events may allow a person to achieve or maintain a feeling of greater purpose in life over time. In a large sample of adults (aged 36-84 years) from the MIDUS study (Midlife in the U.S., http://www.midus.wisc.edu/), we tested whether purpose in life was associated with better emotional recovery following exposure to negative picture stimuli indexed by the magnitude of the eyeblink startle reflex (EBR), a measure sensitive to emotional state. We differentiated between initial emotional reactivity (during stimulus presentation) and emotional recovery (occurring after stimulus offset). Greater purpose in life, assessed over two years prior, predicted better recovery from negative stimuli indexed by a smaller eyeblink after negative pictures offset, even after controlling for initial reactivity to the stimuli during the picture presentation, gender, age, trait affect, and other well-being dimensions. These data suggest a proximal mechanism by which purpose in life may afford protection from negative events and confer resilience is through enhanced automatic emotion regulation after negative emotional provocation
Neurodata Without Borders: Creating a Common Data Format for Neurophysiology
The Neurodata Without Borders (NWB) initiative promotes data standardization in neuroscience to increase research reproducibility and opportunities. In the first NWB pilot project, neurophysiologists and software developers produced a common data format for recordings and metadata of cellular electrophysiology and optical imaging experiments. The format specification, application programming interfaces, and sample datasets have been released
The Effect of a Brief Mindfulness Intervention on Memory for Positively and Negatively Valenced Stimuli
A core component of mindfulness is non-judgmental observation of internal and external stimuli. The present study investigated the effect of mindfulness on memory for emotional stimuli. Participants were exposed to a brief mindfulness intervention and subsequently performed a verbal learning test consisting of positive, neutral, and negative words. Control participants received no intervention and directly performed the verbal learning test. After 20 min, participants recalled as many words as possible. Participants in the mindfulness condition remembered a significantly lower proportion of negative words compared to control participants. No differences between both groups were observed for the proportion of remembered positive words. These findings suggest that memory processes may be a potential mechanism underlying the link between mindfulness and subjective well-being
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