258 research outputs found
A retrospective analysis of longitudinal changes in bone mineral content in cystic fibrosis
Background:
We aimed to describe the longitudinal changes in bone mineral content and influencing factors, in children with cystic fibrosis (CF).
Methods:
One hundred children (50 females) had dual X-ray absorptiometry (DXA) performed. Of these, 48 and 24 children had two to three scans, respectively over 10 years of follow-up. DXA data were expressed as lumbar spine bone mineral content standard deviation score (LSBMCSDS) adjusted for age, gender, ethnicity and bone area. Markers of disease, anthropometry and bone biochemistry were collected retrospectively.
Results:
Baseline LSBMCSDS was >0.5 SDS in 13% children, between −0.5; 0.5 SDS, in 50% and ≤−0.5 in the remainder. Seventy-eight percent of the children who had baseline LSBMCSDS >−0.5, and 35% of the children with poor baseline (LSBMCSDS<−0.5), showed decreasing values in subsequent assessments. However, mean LS BMC SDS did not show a significant decline in subsequent assessments (−0.51; −0.64; −0.56; p=0.178). Lower forced expiratory volume in 1 s percent (FEV1%) low body mass index standard deviation scores (BMI SDS) and vitamin D were associated with reduction in BMC.
Conclusions:
Bone mineral content as assessed by DXA is sub-optimal and decreases with time in most children with CF and this study has highlighted parameters that can be addressed to improve bone health
Effects of surface vibrations on interlayer mass-transport: ab initio molecular dynamics investigation of Ti adatom descent pathways and rates from TiN/TiN(001) islands
We carry out density-functional ab initio molecular dynamics (AIMD)
simulations of Ti adatom (Tiad) migration on, and descent from, TiN
-faceted epitaxial islands on TiN(001) at temperatures T ranging from 1200
to 2400 K. Adatom-descent energy-barriers determined via ab initio
nudged-elastic-band calculations at 0 Kelvin suggest that Ti interlayer
transport on TiN(001) occurs essentially exclusively via direct hopping onto a
lower layer. However, AIMD simulations reveal comparable rates for Tiad descent
via direct-hopping vs. push-out/exchange with a Ti island edge atom for T >=
1500 K. We demonstrate that the effect is due to surface vibrations, which
yield considerably lower activation energies at finite temperatures by
significantly modifying the adatom push/out-exchange reaction pathway.Comment: 13 Figure
Phase Diagram of Multilayer Magnetic Structures
Multilayer "ferromagnet-layered antiferromagnet" (Fe/Cr) structures
frustrated due to the roughness of layer interfaces are studied by numerical
modeling methods. The "thickness-roughness" phase diagrams for the case of thin
ferromagnetic film on the surface of bulk antiferromagnet and for two
ferromagnetic layers separated by an antiferromagnetic interlayer are obtained
and the order parameter distributions for all phases are found. The phase
transitions nature in such systems is considered. The range of applicability
for the "magnetic proximity model" proposed by Slonczewski is evaluated.Comment: 8 pages, 8 figure
Theoretical investigations of a highly mismatched interface: the case of SiC/Si(001)
Using first principles, classical potentials, and elasticity theory, we
investigated the structure of a semiconductor/semiconductor interface with a
high lattice mismatch, SiC/Si(001). Among several tested possible
configurations, a heterostructure with (i) a misfit dislocation network pinned
at the interface and (ii) reconstructed dislocation cores with a carbon
substoichiometry is found to be the most stable one. The importance of the slab
approximation in first-principles calculations is discussed and estimated by
combining classical potential techniques and elasticity theory. For the most
stable configuration, an estimate of the interface energy is given. Finally,
the electronic structure is investigated and discussed in relation with the
dislocation array structure. Interface states, localized in the heterostructure
gap and located on dislocation cores, are identified
Concept of Suicide: Neurophysiological/Genetic Theories and Possible Oxytocin Relevance
The suicidal behavior is regarded as the act by which a person seeks to take his life, being aware
of the consequences of his action. In our review, besides describing the main introductory
aspects for the concept of suicide, we focus our attention on the main neurophysiological
and genetical mechanisms relevant for this extremely difficult to manage and controversial
behavior. Moreover, considering the latest interests in the current literature on the relevance
of central oxytocin to various superior cognitive behaviors, we will also make a short
description on how important effects of oxytocin could be in the context of suicidal behavior.Суїцидальна поведінка – це дії, в результаті яких особа намагається позбавити себе життя, усвідомлюючи наслідки
таких дій. У даному огляді, окрім опису основних загальних аспектів концепції суїциду, ми концентрували увагу на
основних нейрофізіологічних та генетичних аспектах, котрі
мають відношення до цього вкрай важко контрольованого та
повного протиріч типу поведінки. Окрім того, враховуючи
велику цікавість, яку викликає в сучасній літературі задіяність центральної окситоцинової системи в контроль когнітивної поведінки вищих типів, ми надали короткий опис
того, наскільки ефекти окситоцину можуть бути важливими
в контексті суїцидальної поведінки
Ab Initio Molecular Dynamics Simulations of Nitrogen/VN(001) Surface Reactions: Vacancy-Catalyzed N 2
Effects of incident N atom kinetic energy on TiN/TiN(001) film growth dynamics: A molecular dynamics investigation
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