517 research outputs found
Molecular Weight Dependence of Polymersome Membrane Elasticity and Stability
Vesicles prepared in water from a series of diblock copolymers and termed
"polymersomes" are physically characterized. With increasing molecular weight
, the hydrophobic core thickness for the self-assembled bilayers
of polyethyleneoxide - polybutadiene (PEO-PBD) increases up to 20 -
considerably greater than any previously studied lipid system. The mechanical
responses of these membranes, specifically, the area elastic modulus and
maximal areal strain are measured by micromanipulation. As expected
for interface-dominated elasticity, ( 100 ) is found to be
independent of . Related mean-field ideas also predict a limiting
value for which is universal and about 10-fold above that typical of
lipids. Experiments indeed show generally increases with
, coming close to the theoretical limit before stress relaxation is
opposed by what might be chain entanglements at the highest . The
results highlight the interfacial limits of self-assemblies at the nano-scale.Comment: 16 pages, 5 figures, and 1 tabl
Gender and Optimism as Predictors of Novice ESOL Teaching Performance
Both current and past research examining novice ESOL teachers has focused on issues such as educational background and classroom demographics (Yeo et al., 2008), but little research has focused on potential variables that influences perceived teaching performance. Consequently, the aim of this study is to examine the relationship between gender, optimism, and perceived teaching performance amongst novice ESOL teachers. Graduates from two hybrid TESOL graduate programs (N=47) were sampled and surveyed. Optimism significantly predicted perceived teaching performance, t(43)= 3.17, p=.003 and there was an marginal association between gender and perceived teaching performance, t(43)= -1.92, p=.06. Further analyses indicated that the mean ratings of teaching performance were significantly different between men and women, F(1, 45)= 5.12, p=.03. In sum, our results suggest that gender and optimism are factors in perceptions of teacher efficacy amongst novice ESOL teachers. The findings of this study with optimism, gender, and teaching performance not only add empirical data for this group, but also provides a platform to further examine this unique population
An Examination of the First Years: Novice ESOL Teachers’ Experiences with Loneliness and Stress
The first years of work for new teachers can be particularly difficult; this is especially true for English to Speakers of Other Languages (ESOL) teachers (Brannan & Bleistein, 2012; Warford & Reeves, 2003). This study was designed to explore potential issues within this important group and specifically examined the relationship between loneliness and stress for novice ESOL teachers. Forty-seven novice ESOL teachers completed self-report measures assessing their levels of perceived stress and loneliness. The results revealed that loneliness significantly predicted perceived stress (β = .51, p \u3c .001.). Furthermore, exploratory analyses indicated that marital status influenced loneliness ratings but not stress levels. These findings indicate that for novice teachers that often teach abroad, feelings of loneliness are an important issue to consider
Introduction of new guest molecules into BEDT-TTF radical-cation salts with tris(oxalato)ferrate
Radical-cation salts of formula β′′-(BEDT-TTF)4[(H3O)Fe(C2O4)3]·guest have produced a large number of superconductors and provided a route to introduce magnetism and chirality into the same multifunctional material. A relationship has been found in these salts between the length of the b axis and the superconducting Tc. Increasing the b axis length by introducing larger guest molecules, such as benzonitrile and nitrobenzene, gives the highest superconducting Tcs in this family of salts. Smaller guests such as pyridine show no superconducting transition, whilst asymmetrical guests which are larger than nitrobenzene have given a different bilayered structure. Other potential guest molecules have been limited by their ability to be used as the solvent in which the crystals are grown via electrocrystallisation. This paper reports a method which introduces guest molecules into the crystal which are a solid or liquid additive within the crystal-growing solvent 1,2,4-trichlorobenzene:ethanol. We present the crystal structures of five new BEDT-TTF radical-cation salts with tris(oxalato)ferrate anions using guest molecules toluene, phenol, benzaldehyde, 4-bromobenzaldehyde, and kojic acid
Menelaus' theorem, Clifford configurations and inversive geometry of the Schwarzian KP hierarchy
It is shown that the integrable discrete Schwarzian KP (dSKP) equation which
constitutes an algebraic superposition formula associated with, for instance,
the Schwarzian KP hierarchy, the classical Darboux transformation and
quasi-conformal mappings encapsulates nothing but a fundamental theorem of
ancient Greek geometry. Thus, it is demonstrated that the connection with
Menelaus' theorem and, more generally, Clifford configurations renders the dSKP
equation a natural object of inversive geometry on the plane. The geometric and
algebraic integrability of dSKP lattices and their reductions to lattices of
Menelaus-Darboux, Schwarzian KdV, Schwarzian Boussinesq and Schramm type is
discussed. The dSKP and discrete Schwarzian Boussinesq equations are shown to
represent discretizations of families of quasi-conformal mappings.Comment: 26 pages, 9 figure
Revalidation and electronic cataract surgery audit: a Scottish survey on current practice and opinion
PURPOSE: To determine current knowledge and opinion on revalidation, and methods of cataract surgery audit in Scotland and to outline the current and future possibilities for electronic cataract surgery audit. METHODS: In 2010 we conducted a prospective, cross-sectional, Scottish-wide survey on revalidation knowledge and opinion, and cataract audit practice among all senior NHS ophthalmologists. Results were anonymised and recorded manually for analysis. RESULTS: In all, 61% of the ophthalmologists surveyed took part. Only 33% felt ready to take part in revalidation, whereas 76% felt they did not have adequate information about the process. Also, 71% did not feel revalidation would improve patient care, but 85% agreed that cataract surgery audit is essential for ophthalmic practice. In addition, 91% audit their cataract outcomes; 52% do so continuously. Further, 63% audit their subspecialist surgical results. Only 25% audit their cataract surgery practice electronically, and only 12% collect clinical data using a hospital PAS system. Funding and system incompatibility were the main reasons cited for the lack of electronic audit setup. Currently, eight separate hospital IT patient administration systems are used across 14 health boards in Scotland. CONCLUSION: Revalidation is set to commence in 2012. The Royal College of Ophthalmologists will use cataract outcome audit as a tool to ensure surgical competency for the process. Retrospective manual auditing of cataract outcome is time consuming, and can be avoided with an electronic system. Scottish ophthalmologists view revalidation with scepticism and appear to have inadequate knowledge of the process. However, they strongly agree with the concept of cataract surgery audit. The existing and future electronic applications that may support surgical audit are commercial electronic records, web-based applications, centrally funded software applications, and robust NHS connections between community and hospital
Prostaglandin E2 Prevents Hyperosmolar-Induced Human Mast Cell Activation through Prostanoid Receptors EP2 and EP4
Background: Mast cells play a critical role in allergic and inflammatory diseases, including exercise-induced bronchoconstriction (EIB) in asthma. The mechanism underlying EIB is probably related to increased airway fluid osmolarity that activates mast cells to the release inflammatory mediators. These mediators then act on bronchial smooth muscle to cause bronchoconstriction. In parallel, protective substances such as prostaglandin E2 (PGE2) are probably also released and could explain the refractory period observed in patients with EIB. Objective: This study aimed to evaluate the protective effect of PGE2 on osmotically activated mast cells, as a model of exercise-induced bronchoconstriction. Methods: We used LAD2, HMC-1, CD34-positive, and human lung mast cell lines. Cells underwent a mannitol challenge, and the effects of PGE2 and prostanoid receptor (EP) antagonists for EP1-4 were assayed on the activated mast cells. Beta-hexosaminidase release, protein phosphorylation, and calcium mobilization were assessed. Results: Mannitol both induced mast cell degranulation and activated phosphatidyl inositide 3-kinase and mitogen-activated protein kinase (MAPK) pathways, thereby causing de novo eicosanoid and cytokine synthesis. The addition of PGE2 significantly reduced mannitol-induced degranulation through EP2 and EP4 receptors, as measured by beta-hexosaminidase release, and consequently calcium influx. Extracellular-signal-regulated kinase 1/2, c-Jun N-terminal kinase, and p38 phosphorylation were diminished when compared with mannitol activation alone. Conclusions:Our data show a protective role for the PGE2 receptors EP2 and EP4 following osmotic changes, through the reduction of human mast cell activity caused by calcium influx impairment and MAP kinase inhibition
Influence of incubation, diet, and sex on avian uncoupling protein expression and oxidative stress in market age broilers following exposure to acute heat stress
Genetic selection for rapid growth in
broilers has inadvertently resulted in increased susceptibility to heat stress, particularly in male birds. Increased
oxidative stress associated with hyperthermia may be
reduced by avian uncoupling protein (avUCP), which
has been proposed to modulate free radical production.
However, the relationship between avUCP expression
and current heat stress management strategies is
unclear. Embryonic acclimation or thermal manipulation (TM) and dietary fat source are 2 heat stress interventions that may alter avUCP expression and
oxidative stress, but the literature is inconclusive. The
objective of this trial was to investigate the effect of TM
and dietary fat source on avUCP gene expression and
oxidative damage in the breast meat of market age
broilers before and after acute heat challenge. The influence of bird sex was also evaluated as broilers exhibit a
high degree of sexual dimorphism in growth and stress
susceptibility. Concentration of thiobarbituric acid reactive substances (TBARS) was measured as a marker of oxidative damage. Embryonic TM occurred from incubation d 7 to 16 for 12 h daily at 39.5°C. Dietary treatments were applied during the finisher period using
either poultry fat, soya oil, or olive oil supplemented at
4.5% in the diet. Acute heat stress (AHS) occurred on d
43 at 32°C for 4 h. Bird performance was decreased by
TM, but no significant differences were noted between
dietary fat source treatments. Neither avUCP nor
TBARS concentrations were significantly influenced by
TM or dietary fat source. Downregulation of avUCP
was observed following AHS, concurrent with an
increase in TBARS concentration. Male birds exhibited
higher levels of both avUCP expression and TBARS
compared to females and a significant interaction was
noted for heat stress by sex, with avUCP expression
being greatest in males prior to AHS. The increase in
avUCP expression and TBARS concentrations in male
birds may be associated with an increased susceptibility
to stress arising from the increased growth rate noted for
male broilers.https://www.journals.elsevier.com/poultry-sciencedm2022Animal and Wildlife Science
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