20,581 research outputs found
Observational Constraints on Silent Quartessence
We derive new constraints set by SNIa experiments (`gold' data sample of
Riess et al.), X-ray galaxy cluster data (Allen et al. Chandra measurements of
the X-ray gas mass fraction in 26 clusters), large scale structure (Sloan
Digital Sky Survey spectrum) and cosmic microwave background (WMAP) on the
quartessence Chaplygin model. We consider both adiabatic perturbations and
intrinsic non-adiabatic perturbations such that the effective sound speed
vanishes (Silent Chaplygin). We show that for the adiabatic case, only models
with equation of state parameter are allowed: this
means that the allowed models are very close to \LambdaCDM. In the Silent case,
however, the results are consistent with observations in a much broader range,
-0.3<\alpha<0.7.Comment: 7 pages, 12 figures, to be submitted to JCA
Finitely generated ideal languages and synchronizing automata
We study representations of ideal languages by means of strongly connected
synchronizing automata. For every finitely generated ideal language L we
construct such an automaton with at most 2^n states, where n is the maximal
length of words in L. Our constructions are based on the De Bruijn graph.Comment: Submitted to WORDS 201
Extracellular matrix mimics using hyaluronan-based biomaterials
Hyaluronan (HA) is a critical element of the extracellular matrix (ECM). The regulated synthesis and degradation of HA modulates the ECM chemical and physical properties that, in turn, influence cellular behavior. HA triggers signaling pathways associated with the adhesion, proliferation, migration, and differentiation of cells, mediated by its interaction with specific cellular receptors or by tuning the mechanical properties of the ECM. This review summarizes the recent advances on strategies used to mimic the HA present in the ECM to study healthy or pathological cellular behavior. This includes the development of HA-based 2D and 3D in vitro tissue models for the seeding and encapsulation of cells, respectively, and HA particles as carriers for the targeted delivery of therapeutic agents.The authors acknowledge thefinancial support from the European Commission’s H2020 programme, under grantagreements H2020-WIDESPREAD-2014-668983-FORECAST, and H2020-MSCA-RISE-2019-872648-MEPHOS. S.A.acknowledges the Portuguese Foundation for Science and Technology (FCT) for her PhD grant (SFRH/BD/112075/2015)
Encapsulation of alpha-amylase into starch-based biomaterials : an enzymatic approach to tailor their degradation rate
This paper reports the effect of a-amylase encapsulation on the degradation rate of a starch-based biomaterial. The encapsulation
method consisted in mixing a thermostable a-amylase with a blend of corn starch and polycaprolactone (SPCL), which were processed
by compression moulding to produce circular disks. The presence of water was avoided to keep the water activity low and consequently
to minimize the enzyme activity during the encapsulation process. No degradation of the starch matrix occurred during processing and
storage (the encapsulated enzyme remained inactive due to the absence of water), since no significant amount of reducing sugars was
detected in solution. After the encapsulation process, the released enzyme activity from the SPCL disks after 28 days was found to be
40% comparatively to the free enzyme (unprocessed). Degradation studies on SPCL disks, with a-amylase encapsulated or free in solution,
showed no significant differences on the degradation behaviour between both conditions. This indicates that a-amylase enzyme was
successfully encapsulated with almost full retention of its enzymatic activity and the encapsulation of a-amylase clearly accelerates the
degradation rate of the SPCL disks, when compared with the enzyme-free disks. The results obtained in this work show that degradation
kinetics of the starch polymer can be controlled by the amount of encapsulated a-amylase into the matrix.This work was partially supported by Portuguese Foundation for Science and Technology (FCT) through funds from the POCTI and/or FEDER Programmes. This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283)
Angular Correlation Function from sample covariance with BOSS and eBOSS LRG
The Baryon Acoustic Oscillations (BAO) are one of the most used probes to
understand the accelerated expansion of the Universe. Traditional methods rely
on fiducial model information within their statistical analysis, which may be a
problem when constraining different families of models. The aim of this work is
to provide a method that constrains through a model-independent
and compare parameter estimation of the angular correlation function polynomial
approach, using the covariance matrix from the galaxy sample from thin redshift
bins, with the usual mock sample covariance matrix. We proposed a different
approach to finding the BAO angular feature revisiting previous work in the
literature, we take the bias between the correlation function between the bins
and the whole sample. We used widths of separation for all
samples as the basis for a sample covariance matrix weighted by the statistical
importance of the redshift bin. We propose a different weighting scheme based
only on random pair counting. We also propose an alternate shift parameter
based only on the data. Each sample belongs to the Sloan Digital Sky Survey
Luminous Red Galaxies (LRG): BOSS1, BOSS2, and eBOSS, with effective redshift
: 0.35, 0.51, 0.71, respectively, and different numbers of bins with
50, 100, and 200 respectively. In addition, we correct the angular separation
from the polynomial fit () that encodes the BAO feature with a
bias function obtained by comparing each bin correlation function with the
correlation function of the whole set. We also tested the same correction
choosing the bin at and found that for eBOSS is in agreement with the Planck 18 model. BOSS1 and BOSS2
agreed in with the Pantheon+ & SES FlatCDM model, in
tension with Planck 18.Comment: 18 page
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