71 research outputs found
Local modes, phonons, and mass transport in solid He
We propose a model to treat the local motion of atoms in solid He as a
local mode. In this model, the solid is assumed to be described by the Self
Consistent Harmonic approximation, combined with an array of local modes. We
show that in the bcc phase the atomic local motion is highly directional and
correlated, while in the hcp phase there is no such correlation. The correlated
motion in the bcc phase leads to a strong hybridization of the local modes with
the T phonon branch, which becomes much softer than that obtained
through a Self Consistent Harmonic calculation, in agreement with experiment.
In addition we predict a high energy excitation branch which is important for
self-diffusion. Both the hybridization and the presence of a high energy branch
are a consequence of the correlation, and appear only in the bcc phase. We
suggest that the local modes can play the role in mass transport usually
attributed to point defects (vacancies). Our approach offers a more overall
consistent picture than obtained using vacancies as the predominant point
defect. In particular, we show that our approach resolves the long standing
controversy regarding the contribution of point defects to the specific heat of
solid He.Comment: 10 pages, 10 figure
Comparing phoneme frequency, age of acquisition, and loss in aphasia:Implications for phonological universals
Phonological complexity may be central to the nature of human language. It may shape the distribution of phonemes and phoneme sequences within languages, but also determine age of acquisition and susceptibility to loss in aphasia. We evaluated this claim using frequency statistics derived from a corpus of phonologically transcribed Italian words (phonitalia, available at phonitalia,org), rankings of phoneme age of acquisition (AoA) and rate of phoneme errors in patients with apraxia of speech (AoS) as an indication of articulatory complexity. These measures were related to cross-linguistically derived markedness rankings. We found strong correspondences. AoA, however, was predicted by both apraxic errors and frequency, suggesting independent contributions of these variables. Our results support the reality of universal principles of complexity. In addition they suggest that these complexity principles have articulatory underpinnings since they modulate the production of patients with AoS, but not the production of patients with more central phonological difficulties
Gender gap in parental leave intentions: Evidence from 37 countries
This is the final version. Available from Wiley via the DOI in this record. Despite global commitments and efforts, a gender-based division of paid and unpaid work persists. To
identify how psychological factors, national policies, and the broader sociocultural context contribute
to this inequality, we assessed parental-leave intentions in young adults (18–30years old) planning to
have children (N = 13,942; 8,880 identified as women; 5,062 identified as men) across 37 countries that
varied in parental-leave policies and societal gender equality. In all countries, women intended to take
longer leave than men. National parental-leave policies and women’s political representation partially
explained cross-national variations in the gender gap. Gender gaps in leave intentions were paradoxically
larger in countries with more gender-egalitarian parental-leave policies (i.e., longer leave available to
both fathers and mothers). Interestingly, this cross-national variation in the gender gap was driven by
cross-national variations in women’s (rather than men’s) leave intentions. Financially generous leave
and gender-egalitarian policies (linked to men’s higher uptake in prior research) were not associated with
leave intentions in men. Rather, men’s leave intentions were related to their individual gender attitudes.
Leave intentions were inversely related to career ambitions. The potential for existing policies to foster
gender equality in paid and unpaid work is discussed.SSHRC Insight Development GrantSSHRC Insight GrantEconomic and Social Research CouncilState Research AgencyGuangdong 13th-five Philosophy and Social Science Planning ProjectNational Natural Science Foundation of ChinaSwiss National Science FoundationSwiss National Science FoundationCenter for Social Conflict and Cohesion StudiesCenter for Intercultural and Indigenous ResearchSSHRC Postdoctoral FellowshipSlovak Research and Development AgencySwiss National Science FoundationCanada Research ChairsSocial Sciences and Humanities Research Council of CanadaOntario Ministry of Research and InnovationHSE University, RFFaculty of Arts, Masaryk Universit
Plastic properties of solid 4He probed by a moving wire:viscoelastic and stochastic behavior under high stress
We present measurements of a thin wire moving through solid 4He. Measurements were made over a wide temperature range at pressures close to the melting curve. We describe the new experimental technique and present preliminary measurements at relatively high driving forces (stresses) and velocities (strain rates). The wire moves by plastic deformation of the surrounding solid facilitated by quantum tunneling of vacancies and the motion of defects. In the bcc phase we observe very pronounced viscoelastic effects with relaxation times spanning several orders of magnitude. In the hcp phase we observe stochastic step-like motion of the wire. During the step, the wire can move at extremely high velocities. On cooling, the wire ceases to move at a temperature of around 1 K. We are unable to detect any motion at lower temperatures, down to below 10 mK
Tracking the emergence of the consonant bias in visual-word recognition: evidence with developing readers
Recent research with skilled adult readers has consistently revealed an advantage of consonants over vowels in visual-word recognition (i.e., the so-called "consonant bias"). Nevertheless, little is known about how early in development the consonant bias emerges. This work aims to address this issue by studying the relative contribution of consonants and vowels at the early stages of visual-word recognition in developing readers (2(nd) and 4(th) Grade children) and skilled adult readers (college students) using a masked priming lexical decision task. Target words starting either with a consonant or a vowel were preceded by a briefly presented masked prime (50 ms) that could be the same as the target (e.g., pirata-PIRATA [pirate-PIRATE]), a consonant-preserving prime (e.g., pureto-PIRATA), a vowel-preserving prime (e.g., gicala-PIRATA), or an unrelated prime (e.g., bocelo -PIRATA). Results revealed significant priming effects for the identity and consonant-preserving conditions in adult readers and 4(th) Grade children, whereas 2(nd) graders only showed priming for the identity condition. In adult readers, the advantage of consonants was observed both for words starting with a consonant or a vowel, while in 4(th) graders this advantage was restricted to words with an initial consonant. Thus, the present findings suggest that a Consonant/Vowel skeleton should be included in future (developmental) models of visual-word recognition and reading.This research has been partially supported by Grant PTDC/PSI-PCO/104679/2008 from Portuguese FCT (Fundação para a Ciência e Tecnologia) and FEDER (Fundo Europeu de Desenvolvimento Regional) through the European programs QREN (Quadro de Referência Estratégico Nacional) and COMPETE
(Programa Operacional Factores de Competitividade), and by Grant PSI2011-26924 from the Spanish Government. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
A Study on the Acquisition of If-Conditionals by Korean- & Spanish-speaking Learners of English
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