6,496 research outputs found
An exploratory study for the technological classification of egg white powders based on infrared spectroscopy
This work aims at the evaluation of FT-NIR and FT-IR spectroscopy as rapid, easy, and cost-effective tools for the classification of egg white powder (EWP) based on its technological properties. Up to 100 commercial spray-dried EWP samples with known gelling and foaming properties were used to acquire FT-NIR and FT-IR spectra. An appropriate data-splitting algorithm (Duplex) was applied in order to create, for each dataset, a calibration set and a representative validation test set for prediction. Different spectral pre-treatments and their combinations were investigated for the calculation of Partial Least Squares\u2013Discriminant Analysis models in order to classify samples according to gel strength, foam height, and foam instability. A variable selection strategy based on the so-called Variable Importance in Projection scores was also evaluated. Both FT-NIR and FT-IR spectroscopy showed good potential in discriminating EWP samples with different technological properties. Correct classification percentages in prediction ranging from 59% to 89% were obtained with the best models calculated with selected wavenumbers. These results show a promising industrial perspective, demonstrating the possibility of developing cheap and fast instruments spanning a limited spectral range, which can be implemented on the production lines for EWP sorting and quality control
Slavnov-Taylor Parameterization for the Quantum Restoration of BRST Symmetries in Anomaly-Free Gauge Theories
It is shown that the problem of the recursive restoration of the
Slavnov-Taylor (ST) identities at the quantum level for anomaly-free gauge
theories is equivalent to the problem of parameterizing the local approximation
to the quantum effective action in terms of ST functionals, associated with the
cohomology classes of the classical linearized ST operator. The ST functionals
of dimension <=4 correspond to the invariant counterterms, those of dimension
>4 generate the non-symmetric counterterms upon projection on the action-like
sector. At orders higher than one in the loop expansion there are additional
contributions to the non-invariant counterterms, arising from known lower order
terms. They can also be parameterized by using the ST functionals. We apply the
method to Yang-Mills theory in the Landau gauge with an explicit mass term
introduced in a BRST-invariant way via a BRST doublet. Despite being
non-unitary, this model provides a good example where the method devised in the
paper can be applied to derive the most general solution for the action-like
part of the quantum effective action, compatible with the fulfillment of the ST
identities and the other relevant symmetries of the model, to all orders in the
loop expansion. The full dependence of the solution on the normalization
conditions is given.Comment: 23 pages. Final version published in the journa
Effects of turbulence and rotation on protostar formation as a precursor to seed black holes
Context. The seeds of the first supermassive black holes may have resulted
from the direct collapse of hot primordial gas in K haloes,
forming a supermassive or quasistar as an intermediate stage.
Aims. We explore the formation of a protostar resulting from the collapse of
primordial gas in the presence of a strong Lyman-Werner radiation background.
Particularly, we investigate the impact of turbulence and rotation on the
fragmentation behaviour of the gas cloud. We accomplish this goal by varying
the initial turbulent and rotational velocities.
Methods. We performed 3D adaptive mesh refinement simulations with a
resolution of 64 cells per Jeans length using the ENZO code, simulating the
formation of a protostar up to unprecedentedly high central densities of
cm, and spatial scales of a few solar radii. To achieve this
goal, we employed the KROME package to improve modelling of the chemical and
thermal processes.
Results. We find that the physical properties of the simulated gas clouds
become similar on small scales, irrespective of the initial amount of
turbulence and rotation. After the highest level of refinement was reached, the
simulations have been evolved for an additional ~5 freefall times. A single
bound clump with a radius of AU and a mass of ~ M is formed at the end of each simulation, marking the onset
of protostar formation. No strong fragmentation is observed by the end of the
simulations, regardless of the initial amount of turbulence or rotation, and
high accretion rates of a few solar masses per year are found.
Conclusions. Given such high accretion rates, a quasistar of
M is expected to form within years.Comment: 18 pages, 7 figures, fixed typos, added references and clarified some
details; accepted for publication in A&
A UV flux constraint on the formation of direct collapse black holes
The ability of metal free gas to cool by molecular hydrogen in primordial
halos is strongly associated with the strength of ultraviolet (UV) flux
produced by the stellar populations in the first galaxies. Depending on the
stellar spectrum, these UV photons can either dissociate molecules
directly or indirectly by photo-detachment of as the latter
provides the main pathway for formation in the early universe. In
this study, we aim to determine the critical strength of the UV flux above
which the formation of molecular hydrogen remains suppressed for a sample of
five distinct halos at by employing a higher order chemical solver and a
Jeans resolution of 32 cells. We presume that such flux is emitted by PopII
stars implying atmospheric temperatures of ~K. We performed
three-dimensional cosmological simulations and varied the strength of the UV
flux below the Lyman limit in units of . Our findings show that the
value of varies from halo to halo and is sensitive to the
local thermal conditions of the gas. For the simulated halos it varies from
400-700 with the exception of one halo where .
This has important implications for the formation of direct collapse black
holes and their estimated population at z > 6. It reduces the number density of
direct collapse black holes by almost three orders of magnitude compared to the
previous estimates.Comment: 10 pages, 6 figures, matches the accepted version to ber published in
MNRAS, higher resolution version is available at
http://www.astro.physik.uni-goettingen.de/~mlatif/Jcrit.pd
In vitro activity of ozonated olive oil-based products against carious pathogen streptococcus mutans
Mouthwash based on ozonated olive oil in caries prevention: a preliminary in-vitro study
(1) Background: Ozone (O3) proved to oxidize organic and inorganic compounds, and its efficacy against bacteria, viruses and fungi plasma membranes was of interest. Ozone vehicle can be a gaseous form, ozonated water or ozonized oil. The aim of this in-vitro study was to evaluate the efficacy of ozonated olive oil against Streptococcus mutans. (2) Methods: Two different commercial mouthwashes were tested: Ialozon Blu (IB) (Gemavip, Cagliari, Italy), with ozonated olive oil, and Ialozon Rose (IR) (Gemavip, Cagliari, Italy), with ozonated olive oil, hyaluronic acid and vitamin E. All formulates were analyzed in a dilution range from 2-to 256-folds in saline solution, as to reproduce the salivary dilution. Streptococcus mutans CIP103220 strain was used for the antimicrobial susceptibility test, and the Kirby–Bauer inhibition method was performed to evaluate the Minimum Inhibitory (MIC), Minimum Bactericidal (MBC), and Minimum Biofilm Inhibitory Concentration (MBIC). (3) Results: Both formulates showed the same antimicrobial activity. MIC, MBC, and MBIC were observed for dilution factors of 1/32, 1/8 and 1/8, respectively. The mean value of inhibition zone diameter was 16.5 mm for IB, and 18 mm for IR. (4) Conclusions: The results suggested that ozonized olive oil formulates were able to inactivate Streptococcus mutans avoiding the salivary dilution effect in the oral cavity
Fluctuations of the Initial Conditions and the Continuous Emission in Hydrodynamic Description of Two-Pion Interferometry
Within hydrodynamic approach, we study the Bose-Einstein correlation of
identical pions by taking into account both event-by-event fluctuating initial
conditions and continuous pion emission during the whole development of the hot
and dense matter formed in high-energy collisions. Considerable deviations
occur, compared to the usual hydro calculations with smooth initial conditions
and a sudden freeze-out on a well defined hypersurface. Comparison with data at
RHIC shows that, despite rather rough approximation we used here, this
description can give account of the dependence of and and
improves considerably the one for with respect to the usual version.Comment: 5 pages, 4 figure
Importance of Granular Structure in the Initial Conditions for the Elliptic Flow
We show effects of granular structure of the initial conditions (IC) of
hydrodynamic description of high-energy nucleus-nucleus collisions on some
observables, especially on the elliptic-flow parameter v2. Such a structure
enhances production of isotropically distributed high-pT particles, making v2
smaller there. Also, it reduces v2 in the forward and backward regions where
the global matter density is smaller, so where such effects become more
efficacious.Comment: 4 pages, 5 figure
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