656 research outputs found
Anisotropic electrical resistivity of LaFeAsO: evidence for electronic nematicity
Single crystals of LaFeAsO were successfully grown out of KI flux.
Temperature dependent electrical resistivity was measured with current flow
along the basal plane, \rho_perpend(T), as well as with current flow along the
crystallographic c-axis, \rho_parallel(T), the latter one utilizing electron
beam lithography and argon ion beam milling. The anisotropy ratio was found to
lie between \rho_parallel/\rho_perpend = 20 - 200. The measurement of
\rho_perpend(T) was performed with current flow along the tetragonal [1 0 0]
direction and along the [1 1 0] direction and revealed a clear in-plane
anisotropy already at T \leq 175 K. This is significantly above the
orthorhombic distortion at T_0 = 147 K and indicates the formation of an
electron nematic phase. Magnetic susceptibility and electrical resistivity give
evidence for a change of the magnetic structure of the iron atoms from
antiferromagnetic to ferromagnetic arrangement along the c-axis at T^\ast = 11
K.Comment: 10 pages, 6 figures, minor change
Induced Bradycardia Effects on Angiogenesis, Growth and Development in Early Development in Chicken Embryos, Gallus domesticus
Ruck, Sylvia A. Induced Bradycardia Effects on Angiogenesis, Growth and Development in Early Development in Chicken Embryos, Gallus domesticus. Master of Science (Biology), December 2010, 42 pp., 9 illustrations, references, 44 titles. Cardiac performance, angiogenesis and growth was investigated during early chicken development. Heart rate, and thus arterial pulse pressure and cardiac output, were altered with the bradycardic drug ZD7288. Heart rates at 72 h of development of control embryos and those dosed with chicken Ringer were not different at 171 bpm. Acute and chronic application of ZD7288 caused significant bradycardia. Chronic dosing of Ringer and ZD7288 changed neither eye diameter nor development rate. Chronic dosing of ZD7288 did not significantly alter CAM vessel density close to the embryo (2, 3 and 4 mm) but at farther distances (5 and 6 mm) chronic dosing with both Ringer and ZD7288 decreased vessel density by 13 -16%. Chronic dosing with ZD7288 also reduced body mass by 20%. Thus, lowered heart rate and cardiac output had little effect on vessel density or developmental stage, but did reduce embryo growth. i
Complete mitogenome sequences of smooth hammerhead sharks, Sphyrna zygaena, from the eastern and western Atlantic
We report the first mitogenome sequences of the circumglobally distributed, highly mobile, smooth hammerhead shark, Sphyrna zygaena, from the eastern and western Atlantic. Both genomes were 16,729 bp long with 13 protein-coding genes, two rRNAs, 22 tRNAs and a non-coding control region. The two Atlantic shark sequences differ from each other by 13 SNPs, and by 43 and 44 SNPs from the published mitogenome of an S. zygaena specimen from the eastern Pacific Ocean. The cross-Atlantic mitogenome sequences reported here provide a resource to assist with population genetics studies of this widely exploited species of conservation concern
Quality of life in elderly ICU survivors before the COVID-19 pandemic: a systematic review and meta-analysis of cohort studies
Objectives The influence of age on intensive care unit
(ICU) decision-making
is complex, and it is unclear if
it is based on expected subjective or objective patient
outcomes. To address recent concerns over age-based
ICU
decision-making,
we explored patient-assessed
quality of
life (QoL) in ICU survivors before the COVID-19
pandemic.
Design A systematic review and meta-analysis
of cohort
studies published between January 2000 and April 2020,
of elderly patients admitted to ICUs.
Primary and secondary outcome measures We
extracted data on self-reported
QoL (EQ-5D
composite
score), demographic and clinical variables. Using a
random-effect
meta-analysis,
we then compared QoL
scores at follow-up
to scores either before admission, age-matched
population controls or younger ICU survivors. We
conducted sensitivity analyses to study heterogeneity and
bias and a qualitative synthesis of subscores.
Results We identified 2536 studies and included 22 for
qualitative synthesis and 18 for meta-analysis
(n=2326
elderly survivors). Elderly survivors’ QoL was significantly
worse than younger ICU survivors, with a small-to-
medium
effect size (d=0.35 (−0.53 and −0.16)). Elderly survivors’
QoL was also significantly greater when measured slightly
before ICU, compared with follow-up,
with a small effect
size (d=0.26 (−0.44 and −0.08)). Finally, their QoL was
also marginally significantly worse than age-matched
community controls, also with a small effect size (d=0.21
(−0.43 and 0.00)). Mortality rates and length of follow-up
partly explained heterogeneity. Reductions in QoL seemed
primarily due to physical health, rather than mental health
items.
Conclusions The results suggest that the proportionality
of age as a determinant of ICU resource allocation should
be kept under close review and that subjective QoL
outcomes should inform person-centred
decision -aking in
elderly ICU patients.
PROSPERO registration number CRD42020181181
- …