8,504 research outputs found
Awarding Innovation: An Assessment of the Digital Media and Learning Competition
Increasing availability and accessibility of digital media have changed the ways in which young people learn, socialize, play, and engage in civic life. Seeking to understand how learning environments and institutions should transform to respond to these changes, the John D. and Catherine T. MacArthur Foundation (the Foundation) launched the Digital Media and Learning (DML) Initiative in 2005. This report highlights the successes and challenges of one component of the DML Initiative: the DML Competition (the Competition)
Aging, rejuvenation, and memory effects in short-range Ising spin glass: CuCoCl-FeCl graphite bi-intercalation compound
Non-equilibrium aging dynamics in 3D Ising spin glass
CuCoCl-FeCl GBIC has been studied by zero-field
cooled (ZFC) magnetization and low frequency AC magnetic susceptibility ( Hz), where K. The time dependence of the
relaxation rate dd for the ZFC magnetization
after the ZFC aging protocol, shows a peak at a characteristic time
near a wait time (aging behavior), corresponding to a crossover from
quasi equilibrium dynamics to non-equilibrium. The time strongly
depends on , temperature (), magnetic field (), and the
temperature shift (). The rejuvenation effect is observed in both
and under the -shift and -shift
procedures. The memory of the specific spin configurations imprinted during the
ZFC aging protocol can be recalled when the system is re-heated at a constant
heating rate. The aging, rejuvenation, and memory effects observed in the
present system are discussed in terms of the scaling concepts derived from
numerical studies on 3D Edwards-Anderson spin glass model.Comment: 14 pages, 14 figures; Eur. Phys. J. B accepted for publicatio
The Psychological Impact of ‘Mild Lockdown’ in Japan during the COVID-19 Pandemic : A Nationwide Survey under a Declared State of Emergency
This study examined the psychological distress caused by non-coercive lockdown (mild lockdown) in Japan. An online survey was conducted with 11,333 people (52.4% females; mean age = 46.3 ± 14.6 years, range = 18–89 years) during the mild lockdown in the seven prefectures most affected by COVID-19 infection. Over one-third (36.6%) of participants experienced mild-to-moderate psychological distress (Kessler Psychological Distress Scale [K6] score 5–12), while 11.5% reported serious psychological distress (K6 score ≥ 13). The estimated prevalence of depression (Patient Health Questionnaire-9 score ≥ 10) was 17.9%. Regarding the distribution of K6 scores, the proportion of those with psychological distress in this study was significantly higher when compared with the previous national survey data from 2010, 2013, 2016, and 2019. Healthcare workers, those with a history of treatment for mental illness, and younger participants (aged 18–19 or 20–39 years) showed particularly high levels of psychological distress. Psychological distress severity was influenced by specific interactional structures of risk factors: high loneliness, poor interpersonal relationships, COVID-19-related sleeplessness and anxiety, deterioration of household economy, and work and academic difficulties. Even when non-coercive lockdowns are implemented, people’s mental health should be considered, and policies to prevent mental health deterioration are needed. Cross-disciplinary public–private sector efforts tailored to each individual’s problem structure are important to address the mental health issues arising from lockdown
Quantum fluctuations in high field magnetization of 2D square lattice J1-J2 antiferromagnets
The J1-J2 square lattice Heisenberg model with spin S=1/2 has three phases
with long-range magnetic order and two unconventionally ordered phases
depending on the ratio of exchange constants. It describes a number of recently
found layered vanadium oxide compounds. A simple means of investigating the
ground state is the study of the magnetization curve and high-field
susceptibility. We discuss these quantities by using the spin-wave theory and
the exact diagonalization in the whole J1-J2 plane. We compare both results and
find good overall agreement in the sectors of the phase diagram with magnetic
order. Close to the disordered regions the magnetization curve shows strong
deviations from the classical linear behaviour caused by large quantum
fluctuations and spin-wave approximation breaks down. On the FM side (J1<0)
where one approaches the quantum gapless spin nematic ground state this region
is surprisingly large. We find that inclusion of second order spin-wave
corrections does not lead to fundamental improvement. Quantum corrections to
the tilting angle of the ordered moments are also calculated. They may have
both signs, contrary to the always negative first order quantum corrections to
the magnetization. Finally we investigate the effect of the interlayer coupling
and find that the quasi-2D picture remains valid up to |J_\perp/J1| ~ 0.3.Comment: 13 pages, 6figure
Linear response in aging glassy systems, intermittency and the Poisson statistics of record fluctuations
We study the intermittent behavior of the energy decay and linear magnetic
response of a glassy system during isothermal aging after a deep thermal quench
using the Edward-Anderson spin glass model as a paradigmatic example. The large
intermittent changes in the two observables are found to occur in a correlated
fashion and through irreversible bursts, `quakes', which punctuate reversible
and equilibrium-like fluctuations of zero average. The temporal distribution of
the quakes it found to be a Poisson distribution with an average growing
logarithmically on time, indicating that the quakes are triggered by record
sized fluctuations. As the drift of an aging system is to a good approximation
subordinated to the quakes, simple analytical expressions (Sibani et al. Phys
Rev B 74, 224407, 2006) are available for the time and age dependence of the
average response and average energy. These expressions are shown to capture the
time dependencies of the EA simulation results. Finally, we argue that whenever
the changes of the linear response function and of its conjugate
autocorrelation function follow from the same intermittent events a
fluctuation-dissipation-like relation can arise between the two in
off-equilibrium aging.Comment: 10 pages, 17 figures. The mproved version now includes a direct
analysis of the intermittent signal. The new title is hopefully more
informative. Accepted for publication in EPJ
Global DNA methylation and transcriptional analyses of human ESC-derived cardiomyocytes.
With defined culture protocol, human embryonic stem cells (hESCs) are able to generate cardiomyocytes in vitro, therefore providing a great model for human heart development, and holding great potential for cardiac disease therapies. In this study, we successfully generated a highly pure population of human cardiomyocytes (hCMs) (>95% cTnT(+)) from hESC line, which enabled us to identify and characterize an hCM-specific signature, at both the gene expression and DNA methylation levels. Gene functional association network and gene-disease network analyses of these hCM-enriched genes provide new insights into the mechanisms of hCM transcriptional regulation, and stand as an informative and rich resource for investigating cardiac gene functions and disease mechanisms. Moreover, we show that cardiac-structural genes and cardiac-transcription factors have distinct epigenetic mechanisms to regulate their gene expression, providing a better understanding of how the epigenetic machinery coordinates to regulate gene expression in different cell types
VCre/VloxP and SCre/SloxP: new site-specific recombination systems for genome engineering
We developed two new site-specific recombination systems named VCre/VloxP and SCre/SloxP for genome engineering. Their recognition sites are different from Cre recognition sites because VCre and SCre recombinases share less protein similarity with Cre, even though the basic 13-8-13 structures of their recognition sites are identical. Mutant VloxP and SloxP, which have the same uses as mutant loxP, were also developed. VCre/VloxP and SCre/SloxP in combination with Cre/loxP and Flp/FRT systems can serve as powerful tools for genome engineering, especially when used to genetically modify both alleles of a single gene in mouse and human cells
On the interband pairing in doped graphane
An estimation shows that the interband pairing channel between the valence
band components of doped graphane can support a superconducting transition
temperature (or a contribution into this expected event) of the order of 100 K
at the coupling strength near 1 eV
MuSR studies of RE(O,F)FeAs (RE = La, Nd, Ce) and LaOFeP systems: possible incommensurate/stripe magnetism and superfluid density
Muon spin relaxation (MuSR) measurements in iron oxy-pnictide systems have
revealed: (1) commensurate long-range order in undoped LaOFeAs; (2) Bessel
function line shape in La(O0.97F0.03)FeAs which indicates possible
incommensurate or stripe magnetism; (3) anomalous weak magnetism existing in
superconducting LaOFeP, Ce(O0.84F0.16)FeAs, and Nd(O0.88F0.12)FeAs but absent
in superconducting La(O0.92F0.08)FeAs; and (4) scaling of superfluid density
and Tc in the Ce, La, and Nd-FeAs superconductors following a nearly linear
relationship found in cuprates.Comment: 4 pages, 5 figures (color
Mental health and social isolation under repeated mild lockdowns in Japan
The influence of repeated lockdowns on mental health and social isolation is unknown. We conducted a longitudinal study of the influence of repeated mild lockdowns during two emergency declarations in Japan, in May 2020 and February 2021. The analyses included 7893 people who participated in all online surveys. During repeated mild lockdowns, mental and physical symptoms decreased overall, while loneliness increased and social networks decreased. Subgroup analyses revealed that depression and suicidal ideation did not decrease only in the younger age group (aged 18–29 years) and that younger and middle-aged people (aged 18–49 years), women, people with a history of treatment for mental illness, and people who were socially disadvantaged in terms of income had higher levels of mental and physical symptoms at all survey times. Additionally, comprehensive extraction of the interaction structure between depression, demographic attributes, and psychosocial variables indicated that loneliness and social networks were most closely associated with depression. These results indicate that repeated lockdowns have cumulative negative effects on social isolation and loneliness and that susceptible populations, such as young people and those with high levels of loneliness, require special consideration during repeated lockdown situations
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