2,586 research outputs found
Computational Study of Halide Perovskite-Derived ABX Inorganic Compounds: Chemical Trends in Electronic Structure and Structural Stability
The electronic structure and energetic stability of ABX halide
compounds with the cubic and tetragonal variants of the perovskite-derived
KPtCl prototype structure are investigated computationally within the
frameworks of density-functional-theory (DFT) and hybrid (HSE06) functionals.
The HSE06 calculations are undertaken for seven known ABX compounds
with A = K, Rb and Cs, and B = Sn, Pd, Pt, Te, and X = I. Trends in band gaps
and energetic stability are identified, which are explored further employing
DFT calculations over a larger range of chemistries, characterized by A = K,
Rb, Cs, B = Si, Ge, Sn, Pb, Ni, Pd, Pt, Se and Te and X = Cl, Br, I. For the
systems investigated in this work, the band gap increases from iodide to
bromide to chloride. Further, variations in the A site cation influences the
band gap as well as the preferred degree of tetragonal distortion. Smaller A
site cations such as K and Rb favor tetragonal structural distortions,
resulting in a slightly larger band gap. For variations in the B site in the
(Ni, Pd, Pt) group and the (Se, Te) group, the band gap increases with
increasing cation size. However, no observed chemical trend with respect to
cation size for band gap was found for the (Si, Sn, Ge, Pb) group. The findings
in this work provide guidelines for the design of halide ABX compounds
for potential photovoltaic applications
Testing the Evolution of the Correlations between Supermassive Black Holes and their Host Galaxies using Eight Strongly Lensed Quasars
One of the main challenges in using high redshift active galactic nuclei to
study the correlations between the mass of the supermassive Black Hole (MBH)
and the properties of their active host galaxies is instrumental resolution.
Strong lensing magnification effectively increases instrumental resolution and
thus helps to address this challenge. In this work, we study eight strongly
lensed active galactic nuclei (AGN) with deep Hubble Space Telescope imaging,
using the lens modelling code Lenstronomy to reconstruct the image of the
source. Using the reconstructed brightness of the host galaxy, we infer the
host galaxy stellar mass based on stellar population models. MBH are estimated
from broad emission lines using standard methods. Our results are in good
agreement with recent work based on non-lensed AGN, demonstrating the potential
of using strongly lensed AGNs to extend the study of the correlations to higher
redshifts. At the moment, the sample size of lensed AGN is small and thus they
provide mostly a consistency check on systematic errors related to resolution
for the non-lensed AGN. However, the number of known lensed AGN is expected to
increase dramatically in the next few years, through dedicated searches in
ground and space based wide field surveys, and they may become a key diagnostic
of black hole and galaxy co-evolution.Comment: 12 pages, 4 figures, 3 tables. MNRAS in press. Comments welcom
Shorter Lines Facilitate Reading in Those Who Struggle
People with dyslexia, who ordinarily struggle to read, sometimes remark that reading is easier when e-readers are used. Here, we used eye tracking to observe high school students with dyslexia as they read using these devices. Among the factors investigated, we found that reading using a small device resulted in substantial benefits, improving reading speeds by 27%, reducing the number of fixations by 11%, and importantly, reducing the number of regressive saccades by more than a factor of 2, with no cost to comprehension. Given that an expected trade-off between horizontal and vertical regression was not observed when line lengths were altered, we speculate that these effects occur because sluggish attention spreads perception to the left as the gaze shifts during reading. Short lines eliminate crowded text to the left, reducing regression. The effects of attention modulation by the hand, and of increased letter spacing to reduce crowding, were also found to modulate the oculomotor dynamics in reading, but whether these factors resulted in benefits or costs depended on characteristics, such as visual attention span, that varied within our sample
Trends in the incidence of dementia in people with hypertension in the UK 2000 to 2021
INTRODUCTION: We investigated trends in the incidence of dementia in UK adults with hypertension. METHODS: Primary care electronic health records from IQVIA Medical Research Data UK, previously known as THIN, were used to identify 2,133,118 adults aged ≥40 years with hypertension over 2000 to 2021. The annual incidence rate and average annual percentage change in recorded dementia diagnoses were estimated and stratified by sex, 10-year age bands, Townsend deprivation quintiles and dementia subtype. RESULTS: The crude incidence rate of dementia in people with hypertension increased from 1.98 (95% confidence internal [CI] 1.89-2.07) per 1000 person-years at risk (PYAR) in 2000 to 5.29 per 1000 PYAR (95% CI 5.07-5.53) in 2021, corresponding to an average annual increase of 4.1% (95% CI 3.3-5.0). Those aged ≥80 years, the most economically deprived (Townsend = 5), and Alzheimer's disease subtype reported the highest incidence rate within their respective categories. DISCUSSION: The annual incidence rate of dementia in the hypertensive population has increased over the last 22 years. HIGHLIGHTS: New dementia diagnosis in the hypertensive population has increased over 22 years.The Alzheimer's disease subtype reported the highest incidence rate in people with hypertension.Difference in dementia incidence between hypertensive females and males has reduced.Difference in dementia incidence among deprivation categories has reduced in recent years
H0LiCOW XII. Lens mass model of WFI2033-4723 and blind measurement of its time-delay distance and
We present the lens mass model of the quadruply-imaged gravitationally lensed
quasar WFI2033-4723, and perform a blind cosmographical analysis based on this
system. Our analysis combines (1) time-delay measurements from 14 years of data
obtained by the COSmological MOnitoring of GRAvItational Lenses (COSMOGRAIL)
collaboration, (2) high-resolution imaging,
(3) a measurement of the velocity dispersion of the lens galaxy based on
ESO-MUSE data, and (4) multi-band, wide-field imaging and spectroscopy
characterizing the lens environment. We account for all known sources of
systematics, including the influence of nearby perturbers and complex
line-of-sight structure, as well as the parametrization of the light and mass
profiles of the lensing galaxy. After unblinding, we determine the effective
time-delay distance to be , an average
precision of . This translates to a Hubble constant , assuming a flat CDM
cosmology with a uniform prior on in the range [0.05, 0.5].
This work is part of the Lenses in COSMOGRAIL's Wellspring (H0LiCOW)
collaboration, and the full time-delay cosmography results from a total of six
strongly lensed systems are presented in a companion paper (H0LiCOW XIII).Comment: Version accepted by MNRAS. 29 pages including appendix, 17 figures, 6
tables. arXiv admin note: text overlap with arXiv:1607.0140
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Cathelicidin preserves intestinal barrier function in polymicrobial sepsis.
ObjectivesThe intestinal epithelium compartmentalizes the sterile bloodstream and the commensal bacteria in the gut. Accumulating evidence suggests that this barrier is impaired in sepsis, aggravating systemic inflammation. Previous studies reported that cathelicidin is differentially expressed in various tissues in sepsis. However, its role in sepsis-induced intestinal barrier dysfunction has not been investigated.DesignTo examine the role of cathelicidin in polymicrobial sepsis, cathelicidin wild-(Cnlp+/+) and knockout (Cnlp-/-) mice underwent cecal-ligation and puncture (CLP) followed by the assessment of septic mortality and morbidity as well as histological, biochemical, immunological, and transcriptomic analyses in the ileal tissues. We also evaluated the prophylactic and therapeutic efficacies of vitamin D3 (an inducer of endogenous cathelicidin) in the CLP-induced murine polymicrobial sepsis model.ResultsThe ileal expression of cathelicidin was increased by three-fold after CLP, peaking at 4 h. Knockout of Cnlp significantly increased 7-day mortality and was associated with a higher murine sepsis score. Alcian-blue staining revealed a reduced number of mucin-positive goblet cells, accompanied by reduced mucin expression. Increased number of apoptotic cells and cleavage of caspase-3 were observed. Cnlp deletion increased intestinal permeability to 4kD fluorescein-labeled dextran and reduced the expression of tight junction proteins claudin-1 and occludin. Notably, circulating bacterial DNA load increased more than two-fold. Transcriptome analysis revealed upregulation of cytokine/inflammatory pathway. Depletion of Cnlp induced more M1 macrophages and neutrophils compared with the wild-type mice after CLP. Mice pre-treated with cholecalciferol (an inactive form of vitamin D3) or treated with 1alpha, 25-dihydroxyvitamin D3 (an active form of VD3) had decreased 7-day mortality and significantly less severe symptoms. Intriguingly, the administration of cholecalciferol after CLP led to worsened 7-day mortality and the associated symptoms.ConclusionsEndogenous cathelicidin promotes intestinal barrier integrity accompanied by modulating the infiltration of neutrophils and macrophages in polymicrobial sepsis. Our data suggested that 1alpha, 25-dihydroxyvitamin D3 but not cholecalciferol is a potential therapeutic agent for treating sepsis
Brain-like associative learning using a nanoscale non-volatile phase change synaptic device array
Recent advances in neuroscience together with nanoscale electronic device
technology have resulted in huge interests in realizing brain-like computing
hardwares using emerging nanoscale memory devices as synaptic elements.
Although there has been experimental work that demonstrated the operation of
nanoscale synaptic element at the single device level, network level studies
have been limited to simulations. In this work, we demonstrate, using
experiments, array level associative learning using phase change synaptic
devices connected in a grid like configuration similar to the organization of
the biological brain. Implementing Hebbian learning with phase change memory
cells, the synaptic grid was able to store presented patterns and recall
missing patterns in an associative brain-like fashion. We found that the system
is robust to device variations, and large variations in cell resistance states
can be accommodated by increasing the number of training epochs. We illustrated
the tradeoff between variation tolerance of the network and the overall energy
consumption, and found that energy consumption is decreased significantly for
lower variation tolerance.Comment: Original article can be found here:
http://journal.frontiersin.org/Journal/10.3389/fnins.2014.00205/abstrac
Are changes in semantic and structural information sufficient for oculomotor capture?
. The new-object hypothesis proposes that the appearance of something new (new semantic and structural information and/or spatiotemporal newness), not the accompanying low-level perceptual transients, causes an involuntary reorienting of attention (S. . We investigated whether semantic and structural changes alone are sufficient to capture the eyes as strongly as abrupt onsets do. Observers moved their eyes to a target object while another object either onset or smoothly and quickly morphed. If semantic and structural changes are sufficient to capture the eyes, morphs should capture the eyes as strongly as onsets do. Results show that morphs were not fixated first as often as onsets. These findings indicate that new semantic and structural information alone is far less effective at capturing the eyes as onsets
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