497 research outputs found
Extensive reuse of soda-lime waste glass in fly ash-based geopolymers
The possibility of extensive incorporation of soda-lime waste glass in the synthesis of fly ash-based geopolymers was investigated. Using waste glass as silica supplier avoids the use of water glass solution as chemical activator. The influence of the addition of waste glass on the microstructure and strength of fly ash-based geopolymers was studied through microstructural and mechanical characterization. Leaching analyses were also carried out. The samples were developed changing the SiO2/Al2O3 molar ratio and the molarity of the sodium hydroxide solution used as alkaline activator. The results suggest that increasing the amount of waste glass as well as increasing the molarity of the solution lead to the formation of zeolite crystalline phases and an improvement of the mechanical strength. Leaching results confirmed that the new geopolymers have the capability to immobilize heavy metal ions
Hemodynamic responses during and after multiple sets of stretching exercises performed with and without the Valsalva maneuver
OBJECTIVE: This study investigated the acute hemodynamic responses to multiple sets of passive stretching exercises performed with and without the Valsalva maneuver. METHODS: Fifteen healthy men aged 21 to 29 years with poor flexibility performed stretching protocols comprising 10 sets of maximal passive unilateral hip flexion, sustained for 30 seconds with equal intervals between sets. Protocols without and with the Valsalva maneuver were applied in a random counterbalanced order, separated by 48-hour intervals. Hemodynamic responses were measured by photoplethysmography pre-exercise, during the stretching sets, and post-exercise. RESULTS: The effects of stretching sets on systolic and diastolic blood pressure were cumulative until the fourth set in protocols performed with and without the Valsalva maneuver. The heart rate and rate pressure product increased in both protocols, but no additive effect was observed due to the number of sets. Hemodynamic responses were always higher when stretching was performed with the Valsalva maneuver, causing an additional elevation in the rate pressure product. CONCLUSIONS: Multiple sets of unilateral hip flexion stretching significantly increased blood pressure, heart rate, and rate pressure product values. A cumulative effect of the number of sets occurred only for systolic and diastolic blood pressure, at least in the initial sets of the stretching protocols. The performance of the Valsalva maneuver intensified all hemodynamic responses, which resulted in significant increases in cardiac work during stretching exercises
On the variability of spore-ornamentation in Laccaria tortilis (Basidiomycota, Agaricomycetes)
Исследование возможности применения технологии сохранения трехмерных объектов для ракетно-космической промышленности
Recommended from our members
TRAJECTORY CLUSTERING USING LATENT CLASS MODELS FOR UNSUPERVISED TBI BIOMARKER TEMPORAL PHENOTYPE DISCOVER
Background: TBI biomarkers display population-level time-varying
kinetics [1] which may be a rich source of pathobiological information
[2]. At an individual level, deviations from stereotypical trajectories
may represent different pathological processes or secondary insults.
A method for discovering such phenotypes may be useful in in-
dividualising treatments in real-time.
Methods: Serial blood (12hourly) and CSF (6hourly) samples were
obtained from seventeen adult patients with severe TBI (Stockholm
ethics committee approval #2009/1112-31). S100B and neuron-specific
enolase (NSE) concentrations were measured along with blood:CSF
albumin quotient Qa as a measure of blood-brain-barrier (BBB) integrity.
S100B and NSE concentrations were log-transformed: Equivalent to the
assumption of baseline exponential decay. We used trajectory modeling
combining a quadratic mixed effects model with latent group analysis to
search for characteristic trajectories in the measured parameter.
Results: For serum S100B, we discovered two phenotypes with fast
and slow kinetics. The fast group corresponded with patients with
more severe extracranial injury. For serum NSE, again two phenotypes
were discovered; a time-decaying group and another with a peak
around day 4. CSF analysis yielded two latent groups for both S100B
and NSE: a time-decaying group and another displaying prolonged
elevation over several days. Qa data clustered into three groups: two
with fast, slow decay and another with prolonged elevation. The group
with prolonged BBB permeability had corresponding poorer outcomes.
Conclusions: Small numbers prevent statistical comparison, but
trajectory modeling identified a number of phenotypes with plausible
pathobiological significance. In particular the technique revealed a
group of patients with secondary serum NSE release and another with
sustained BBB permeability. Such groups seem to relate to injury
profile and outcome suggesting biological relevance. To our knowledge
this is the first use of an unsupervised clustering technique in kinetic
phenotype discovery.
References:
[1] Ercole A, Thelin EP, Holst A, Bellander BM, Nelson DW.
Kinetic modelling of serum S100b after traumatic brain injury. BMC
Neurol. 2016;16:93.
[2] Thelin EP, Zeiler FA, Ercole A, Mondello S, Büki A, Bellander
BM, Helmy A, Menon DK, Nelson DW. Serial Sampling of Serum
Protein Biomarkers for Monitoring Human Traumatic Brain Injury
Dynamics: A Systematic Review. Front Neurol. 2017;8:300
Cinema Heritage in Europe: Preserving and Sharing Culture by Engaging with Film Exhibition and Audiences
Editoria
Computing the first eigenpair of the p-Laplacian via inverse iteration of sublinear supersolutions
We introduce an iterative method for computing the first eigenpair
for the -Laplacian operator with homogeneous Dirichlet
data as the limit of as , where
is the positive solution of the sublinear Lane-Emden equation
with same boundary data. The method is
shown to work for any smooth, bounded domain. Solutions to the Lane-Emden
problem are obtained through inverse iteration of a super-solution which is
derived from the solution to the torsional creep problem. Convergence of
to is in the -norm and the rate of convergence of
to is at least . Numerical evidence is
presented.Comment: Section 5 was rewritten. Jed Brown was added as autho
- …