99 research outputs found
Large Gravitational Wave Background Signals in Electroweak Baryogenesis Scenarios
The bubble wall velocity in an electroweak first order phase transition is a
key quantity both for electroweak baryogenesis and for the production of a
stochastic background of gravitational waves that may be probed in the future
through gravitational wave experiments like LISA or BBO. We show that, contrary
to the conclusion drawn from previous studies, it is actually possible to
generate a potentially large gravitational wave signal while satisfying the
requirements for viable electroweak baryogenesis, once the effects of the
hydrodynamics of bubble growth are taken into account. Then, the observation of
a large gravitational wave background from the electroweak phase transition
would not necessarily rule out electroweak baryogenesis as the mechanism having
generated the observed baryon asymmetry of the universe.Comment: 6 pages. References added. Accepted for publication in Phys. Rev.
Scalar Loops in Little Higgs Models
Loops of the scalar particles present in Little Higgs models generate
radiatively scalar operators that have been overlooked before in Little Higgs
analyses. We compute them using a technique, recently proposed to deal with
scalar fluctuations in non-linear sigma models, that greatly simplifies the
calculation. In particular models some of these operators are not induced by
loops of gauge bosons or fermions, are consistent with the Little Higgs
symmetries that protect the Higgs boson mass, and must also be included in the
Lagrangian. In general, scalar loops multiplicatively renormalize the
tree-level scalar operators, O_S -> O_S [1- N \Lambda^2/(4\pi f)^2] with large
N (e.g. N ~ 20 for the Littlest Higgs), suggesting a true UV cutoff \Lambda < 4
\pi f/\sqrt{N} significantly below the estimate 4\pi f of naive dimensional
analysis. This can have important implications for the phenomenology and
viability of Little Higgs models.Comment: 28 pages, LaTe
Hydrodynamic obstruction to bubble expansion
We discuss a hydrodynamic obstruction to bubble wall acceleration during a
cosmological first-order phase transition. The obstruction results from the
heating of the plasma in the compression wave in front of the phase transition
boundary. We provide a simple criterion for the occurrence of the obstruction
at subsonic bubble wall velocity in terms of the critical temperature, the
phase transition temperature, and the latent heat of the model under
consideration. The criterion serves as a sufficient condition of subsonic
bubble wall velocities as required by electroweak baryogenesis.Comment: 18 pages, 4 figures; comments and reference added, published versio
Energy Budget of Cosmological First-order Phase Transitions
The study of the hydrodynamics of bubble growth in first-order phase
transitions is very relevant for electroweak baryogenesis, as the baryon
asymmetry depends sensitively on the bubble wall velocity, and also for
predicting the size of the gravity wave signal resulting from bubble
collisions, which depends on both the bubble wall velocity and the plasma fluid
velocity. We perform such study in different bubble expansion regimes, namely
deflagrations, detonations, hybrids (steady states) and runaway solutions
(accelerating wall), without relying on a specific particle physics model. We
compute the efficiency of the transfer of vacuum energy to the bubble wall and
the plasma in all regimes. We clarify the condition determining the runaway
regime and stress that in most models of strong first-order phase transitions
this will modify expectations for the gravity wave signal. Indeed, in this
case, most of the kinetic energy is concentrated in the wall and almost no
turbulent fluid motions are expected since the surrounding fluid is kept mostly
at rest.Comment: 36 pages, 14 figure
Supersonic Electroweak Baryogenesis: Achieving Baryogenesis for Fast Bubble Walls
Standard electroweak baryogenesis in the context of a first order phase
transition is effective in generating the baryon asymmetry of the universe if
the broken phase bubbles expand at subsonic speed, so that CP asymmetric
currents can diffuse in front of the wall. Here we present a new mechanism for
electroweak baryogenesis which operates for supersonic bubble walls. It relies
on the formation of small bubbles of the symmetric phase behind the bubble
wall, in the broken phase, due to the heating of the plasma as the wall passes
by. We apply the mechanism to a model in which the Higgs field is coupled to
several singlets, and find that enough baryon asymmetry is generated for
reasonable values of the parameter space
Impact of the malaxation temperature on the phenolic profile of cv. Cobrançosa olive oils and assessment of the related health claim
Phenolic compounds contribute to the bioactive properties of olive oil. However, olive oils can only support a health claim concerning the protection against oxidative stress depending on the polyphenolic concentration, requiring effective measures during extraction to preserve/enhance their concentrations. The effect of the malaxation temperature (22, 28 and 34 °C) on the phenolic profile was studied for industrially extracted cv. Cobrançosa oils. Higher malaxation temperatures decreased the contents of the majority of the chromatographically detected compounds (P<0.05, one-way ANOVA), enabling oils differentiation. This decreasing trend was observed for hydroxytyrosol and tyrosol bound forms, determinant for the health claim, which were also negatively affected by temperature, despite revealing that all the industrially extracted oils tested supported the health claim. The observed constant free to bound forms ratio showed that the temperature range tested had a minor effect on bound-forms hydrolysis, being both free and bound forms equally affected by temperature.The authors are grateful to the Foundation for Science andTechnology (FCT, Portugal) forfinancial support by national fundsFCT/MCTES to CIMO (UIDB/00690/2020), to CEB (UIDB/04469/2020), to REQUIMTE-LAQV (UIDB/50006/2020) and to BioTecNorteoperation (NORTE‐01‐0145‐FEDER‐000004) funded by the EuropeanRegional Development Fund under the scope of Norte2020‐Programa Operacional Regional do Norte. Ítala Marx acknowledges the Ph.D.research grant (SFRH/BD/137283/2018) provided by FCT. NunoRodrigues thanks the National funding by FCT- Foundation for Scienceand Technology, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio
A taste sensor device for unmasking admixing of rancid or winey-vinegary olive oil to extra virgin olive oil
Electrochemical sensor devices have gathered great attention in food analysis namely for olive oil evaluation. The adulteration of extra-virgin olive oil with lower-grade olive oil is a common worldwide fraudulent practice, which detection is a challenging task. The potentiometric fingerprints recorded by lipid polymeric sensor membranes of an electronic tongue, together with linear discriminant analysis and simulated annealing meta-heuristic algorithm, enabled the detection of extra-virgin olive oil adulterated with olive oil for which an intense sensory defect could be perceived, specifically rancid or winey-vinegary negative sensations. The homemade designed taste device allowed the identification of admixing of extra-virgin olive oil with more than 2.5% or 5% of rancid or winey-vinegary olive oil, respectively. Predictive mean sensitivities of 84±4% or 92±4% and specificities of 79±6% or 93±3% were obtained for rancid or winey-vinegary adulterations, respectively, regarding an internal-validation procedure based on a repeated K-fold cross-validation variant (4 folds×10 repeats, ensuring that the dataset was forty times randomly split into 4 folds, leaving 25% of the data for validation purposes). This performance was satisfactory since, according to the legal physicochemical and sensory analysis, the intentionally adulterated olive oil with percentages of 2.510%, could still be commercialized as virgin olive oil. It could also be concluded that at a 5% significance level, the trained panelists could not distinguish extra-virgin olive oil samples from those adulterated with 2.5% of rancid olive oil or up to 5% of winey-vinegary olive oil. Thus, the electronic tongue proposed in this study can be foreseen as a practical and powerful tool to detect this kind of worldwide common fraudulent practice of high quality olive oil.This work was financially supported by Project POCI-01–0145FEDER-006984 – Associate Laboratory LSRE-LCM, Project UID/QUI/ 00616/2013 – CQ-VR, Project UID/BIO/04469/2013 – CEB and strategic project PEst-OE/AGR/UI0690/2014 – CIMO all funded by FEDER - Fundo Europeu de Desenvolvimento Regional through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundação para a Ciência e a Tecnologia, Portugal. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/BD/104038/2014). Souheib Oueslati is also grateful for the support of the Tunisian Ministry of Agriculture.info:eu-repo/semantics/publishedVersio
Increased Expression of AQP 1 and AQP 5 in Rat Lungs Ventilated with Low Tidal Volume is Time Dependent
Background and GoalsMechanical ventilation (MV) can induce or worsen pulmonary oedema. Aquaporins (AQPs) facilitate the selective and rapid bi-directional movement of water. Their role in the development and resolution of pulmonary oedema is controversial. Our objectives are to determine if prolonged MV causes lung oedema and changes in the expression of AQP 1 and AQP 5 in rats.Methods25 male Wistar rats were subjected to MV with a tidal volume of 10 ml/kg, during 2 hours (n = 12) and 4 hours (n = 13). Degree of oedema was compared with a group of non-ventilated rats (n = 5). The expression of AQP 1 and AQP 5 were determined by western immunoblotting, measuring the amount of mRNA (previously amplified by RT-PCR) and immunohistochemical staining of AQPs 1 and 5 in lung samples from all groups.ResultsLung oedema and alveolar-capillary membrane permeability did not change during MV. AQP-5 steady state levels in the western blot were increased (p<0.01) at 2 h and 4 h of MV. But in AQP-1 expression these differences were not found. However, the amount of mRNA for AQP-1 was increased at 2 h and 4 h of MV; and for AQP 5 at 4 h of MV. These findings were corroborated by representative immunohistochemical lung samples.ConclusionIn lungs from rats ventilated with a low tidal volume the expression of AQP 5 increases gradually with MV duration, but does not cause pulmonary oedema or changes in lung permeability. AQPs may have a protective effect against the oedema induced by MV
Latent tuberculosis infection, tuberculin skin test and vitamin D status in contacts of tuberculosis patients: a cross-sectional and case-control study
<p>Abstract</p> <p>Background</p> <p>Deficient serum vitamin D levels have been associated with incidence of tuberculosis (TB), and latent tuberculosis infection (LTBI). However, to our knowledge, no studies on vitamin D status and tuberculin skin test (TST) conversion have been published to date. The aim of this study was to estimate the associations of serum 25-hydroxyvitamin D<sub>3 </sub>(25[OH]D) status with LTBI prevalence and TST conversion in contacts of active TB in Castellon (Spain).</p> <p>Methods</p> <p>The study was designed in two phases: cross-sectional and case-control. From November 2009 to October 2010, contacts of 42 TB patients (36 pulmonary, and 6 extra-pulmonary) were studied in order to screen for TB. LTBI and TST conversion cases were defined following TST, clinical, analytic and radiographic examinations. Serum 25(OH)D levels were measured by electrochemiluminescence immunoassay (ECLIA) on a COBAS<sup>® </sup>410 ROCHE<sup>® </sup>analyzer. Logistic regression models were used in the statistical analysis.</p> <p>Results</p> <p>The study comprised 202 people with a participation rate of 60.1%. Only 20.3% of the participants had a sufficient serum 25(OH)D (≥ 30 ng/ml) level. In the cross-sectional phase, 50 participants had LTBI and no association between LTBI status and serum 25(OH)D was found. After 2 months, 11 out of 93 negative LTBI participants, without primary prophylaxis, presented TST conversion with initial serum 25(OH)D levels: a:19.4% (7/36): < 20 ng/ml, b:12.5% (4/32):20-29 ng/ml, and c:0%(0/25) ≥ 30 ng/ml. A sufficient serum 25(OH)D level was a protector against TST conversion a: Odds Ratio (OR) = 1.00; b: OR = 0.49 (95% confidence interval (CI) 0.07-2.66); and c: OR = 0.10 (95% CI 0.00-0.76), trends p = 0.019, adjusted for high exposure and sputum acid-fast bacilli positive index cases. The mean of serum level 25(OH)D in TST conversion cases was lower than controls,17.5 ± 5.6 ng/ml versus 25.9 ± 13.7 ng/ml (p = 0.041).</p> <p>Conclusions</p> <p>The results suggest that sufficient serum 25(OH)D levels protect against TST conversion.</p
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