7,722 research outputs found
Unified formalism for higher-order non-autonomous dynamical systems
This work is devoted to giving a geometric framework for describing
higher-order non-autonomous mechanical systems. The starting point is to extend
the Lagrangian-Hamiltonian unified formalism of Skinner and Rusk for these
kinds of systems, generalizing previous developments for higher-order
autonomous mechanical systems and first-order non-autonomous mechanical
systems. Then, we use this unified formulation to derive the standard
Lagrangian and Hamiltonian formalisms, including the Legendre-Ostrogradsky map
and the Euler-Lagrange and the Hamilton equations, both for regular and
singular systems. As applications of our model, two examples of regular and
singular physical systems are studied.Comment: 43 pp. We have corrected and clarified the statement of Propositions
2 and 3. A remark is added after Proposition
Selection of lactic bacteria to induce malolactic fermentation in red wine of cv. Cencibel
This paper describes the procedure for the selection of three lactic acid bacteria strains from 40 indigenous strains isolated in two cellars of theSpanish region of Castilla-LaMancha.The isolates were identified by classical microbiological and molecular techniques: Pulsed-Field Gel Electrophoresis (pFGE) of bacterial chromosome fragments obtained from restriction enzymes.Selection was carried out considering the capacity to perform malolactic fermentation (MLF) in wine and the resistance to high alcoholic percentages and low pH levels. Three isolates (two Lactobacillus planta Tum and one Oenococcus oeni) which were able to pass the above mentioned tests were selected. These isolates produced low volatile acidity, showed a moderate resistance to SO2 and did not cause any degradation of residual sugars
Higher-order Mechanics: Variational Principles and other topics
After reviewing the Lagrangian-Hamiltonian unified formalism (i.e, the
Skinner-Rusk formalism) for higher-order (non-autonomous) dynamical systems, we
state a unified geometrical version of the Variational Principles which allows
us to derive the Lagrangian and Hamiltonian equations for these kinds of
systems. Then, the standard Lagrangian and Hamiltonian formulations of these
principles and the corresponding dynamical equations are recovered from this
unified framework.Comment: New version of the paper "Variational principles for higher-order
dynamical systems", which was presented in the "III Iberoamerican Meeting on
Geometry, Mechanics and Control" (Salamanca, 2012). The title is changed. A
detailed review is added. Sections containing results about variational
principles are enlarged with additional comments, diagrams and summarizing
results. Bibliography is update
Comparison of aromatic composition of an endangered variety ('Albilla Dorada') with other recognized aromatic varieties
'Albilla Dorada' is a local and endangered grape variety. It was correctly identified beforehand by analysing six microsatellite regions recommended by the GENRES 081 project plus six other additional regions, resulting in one new genotype not described for any variety according to the literature consulted. The object of this paper is to characterize the aromatic composition of this grape vine genotype not previously described. The minority volatile compounds in the grapes were analysed by gas chromatography-mass spectroscopy (GC-MS) and compared with those of eight known aromatic cultivars: 'Albillo Real', 'Macabeo', 'Malvasía Aromática', 'Gewürztraminer', 'Viognier', 'Malvasía Riojana', 'Riesling' and 'Moscatel de Grano Menudo'. Statistically significant differences between varieties were found as regards the different fractions making up the aromatic composition. 'Albilla Dorada' differed from the rest in that it had higher proportions of alcohols, benzene alcohols and norisoprenoids. In the case of the terpene fraction, it was the variety with the highest proportions of citronellol and terpene hydroxides. Results of this work point out 'Albilla Dorada' is a variety with a singular aromatic identity and highlight the necessity of recovering it before its total disappearance.
Porosity enhancement by the utilization of screening patterns in electro-perforated paper webs
In this work, a technique to enhance the porosity of electro-perforated paper webs using screening matrices is described. The proposed approach relies on the confining effect that acts on a train of sparks when forced to pass through a small hole pierced through a ceramic substrate located in-between two needle-like electrodes. It is shown how the maximum porosity level achievable by the electro-perforation process depends on the drag distance parameter. Since the proposed method is aimed at reducing the latter, an eventual enhancement of the number of perforations per unit area can be obtained. The method has been experimentally tested. It is worth mentioning the suitability of the matrix-aided paper perforation process for its use in industrial environments.Publicad
Glicerólisis de oleínas de cacao con lipasa Candida antarctica en un sistema libre de solventes
In this paper we present the valorization of cocoa olein obtained from the acid fat-splitting of soapstocks. The aim is to develop a solvent free process (enzymatically catalyzed) to maximize the production of a final product with high content of monoglycerides (MAG) and diglycerides (DAG). The effect of the enzyme dose, glycerol content, reaction times as well as the modification of the raw material and pressure were studied. The yield of the reaction increased up to 90-95% when using a vacuum of 2-3 mbar at 65 °C, enough to evaporate the water which is generated as a by-product, an enzyme dose of 1% and molar ratio oil:glycerol of 1:2. The highest yield in terms of MAG and DAG production was obtained by starting from a raw material which was rich in free acidity (FFA), rendering oil with 33.4 and 44.2% MAG and DAG, respectively. Short reaction times (6-8 h) were observed compared to previously reported results (24 h).En el presente trabajo se pretende valorizar la oleína vegetal de cacao procedente de la ruptura ácida de las pastas de refinación química. El objetivo es poner a punto un proceso de glicerólisis enzimática en un sistema libre de solventes maximizando la producción de monoglicéridos (MAG) y diglicéridos (DAG). Se ha estudiado el efecto de la dosis de enzima, el contenido de glicerol y el tiempo de reacción, la modificación de la presión de reacción y la composición de la materia prima. Se concluye que el rendimiento de la reacción aumenta hasta el 90-95% cuando se aplica un vacío de 2-3 mbar a 65 ºC suficiente para evaporar el agua que se va generando como producto, una dosis de enzima del 1% y una relación molar aceite:glicerol 1:2. El mayor rendimiento en cuanto a la producción de MAG y DAG se ha conseguido partiendo de una materia prima rica en acidez libre (FFA), obteniéndose un aceite con un 33.4 y 44.2% de MAG y DAG, respectivamente. Se observa que los tiempos de reacción son cortos (6-8h) comparados con los descritos en la bibliografía encontrada (24h)
Wildlife and Antibiotic Resistance
Antibiotic resistance is a major human health problem. While health care facilities are main contributors to the emergence, evolution and spread of antibiotic resistance, other ecosystems are involved in such dissemination. Wastewater, farm animals and pets have been considered important contributors to the development of antibiotic resistance. Herein, we review the impact of wildlife in such problem. Current evidence supports that the presence of antibiotic resistance genes and/or antibiotic resistant bacteria in wild animals is a sign of anthropic pollution more than of selection of resistance. However, once antibiotic resistance is present in the wild, wildlife can contribute to its transmission across different ecosystems. Further, the finding that antibiotic resistance genes, currently causing problems at hospitals, might spread through horizontal gene transfer among the bacteria present in the microbiomes of ubiquitous animals as cockroaches, fleas or rats, supports the possibility that these organisms might be bioreactors for the horizontal transfer of antibiotic resistance genes among human pathogens. The contribution of wildlife in the spread of antibiotic resistance among different hosts and ecosystems occurs at two levels. Firstly, in the case of non-migrating animals, the transfer will take place locally; a One Health problem. Paradigmatic examples are the above mentioned animals that cohabit with humans and can be reservoirs and vehicles for antibiotic resistance dissemination. Secondly, migrating animals, such as gulls, fishes or turtles may participate in the dissemination of antibiotic resistance across different geographic areas, even between different continents, which constitutes a Global Health issue. Copyright © 2022 Laborda, Sanz-García, Ochoa-Sánchez, Gil-Gil, Hernando-Amado and Martínez
Light yield determination in large sodium iodide detectors applied in the search for dark matter
Application of NaI(Tl) detectors in the search for galactic dark matter
particles through their elastic scattering off the target nuclei is well
motivated because of the long standing DAMA/LIBRA highly significant positive
result on annual modulation, still requiring confirmation. For such a goal, it
is mandatory to reach very low threshold in energy (at or below the keV level),
very low radioactive background (at a few counts/keV/kg/day), and high
detection mass (at or above the 100 kg scale). One of the most relevant
technical issues is the optimization of the crystal intrinsic scintillation
light yield and the efficiency of the light collecting system for large mass
crystals. In the frame of the ANAIS (Annual modulation with NaI Scintillators)
dark matter search project large NaI(Tl) crystals from different providers
coupled to two photomultiplier tubes (PMTs) have been tested at the Canfranc
Underground Laboratory. In this paper we present the estimates of the NaI(Tl)
scintillation light collected using full-absorption peaks at very low energy
from external and internal sources emitting gammas/electrons, and
single-photoelectron events populations selected by using very low energy
pulses tails. Outstanding scintillation light collection at the level of
15~photoelectrons/keV can be reported for the final design and provider chosen
for ANAIS detectors. Taking into account the Quantum Efficiency of the PMT
units used, the intrinsic scintillation light yield in these NaI(Tl) crystals
is above 40~photoelectrons/keV for energy depositions in the range from 3 up to
25~keV. This very high light output of ANAIS crystals allows triggering below
1~keV, which is very important in order to increase the sensitivity in the
direct detection of dark matter
TGF-β antagonist attenuates fibrosis but not luminal narrowing in experimental tracheal stenosis.
Introduction/Objective: Acquired tracheal stenosis (ATS) is an unusual disease
often secondary to prolonged mechanical trauma. ATS pathogenesis involves
inflammation and subsequent fibrosis with narrowing of the tracheal lumen. TGF-β
represents a pivotal factor in most fibrotic processes and therefore, a potential target
in this context. The aim of this study is to analyze the role of TGF-β as a target for
anti-fibrotic interventions in tracheal stenosis.
Methods: Human stenotic tracheobronchial tissues from patients with benign airway
stenosis and normal controls from pneumonectomy specimens were analyzed.
Tracheal stenosis was induced in adult NZ rabbits by a circumferential thermal injury
to the mucosa during open surgery and re-anastomosis. Rabbits were treated
postoperatively with a peritracheal collagen sponge containing a TGF-β peptide
antagonist (p17) or vehicle. Fibrosis was determined by Masson’s trichrome staining,
and α-SMA+
Results: Human and rabbit stenotic tissues showed extensive submucosal fibrosis,
characterized by significantly increased α-SMA
myofibroblasts, CTGF and p-Smad2/3 expression by
immunohistochemistry.
+ myofibroblasts and CTGF
expression. In human stenotic lesions, increased p-Smad2/3+ nuclei were also
observed. p17 treatment significantly reduced the fibrotic thickness as well as the
density of α-SMA+ myofibroblasts and CTGF+
Conclusion: ATS is characterized by a TGF-β dependent fibrotic process but
reduction of the fibrotic component by TGF-β1 antagonist therapy was not sufficient
to improve tracheal narrowing, suggesting that fibrosis may not be the main
contributor to luminal stenosis.
cells in rabbit stenotic lesions but failed
to improve the luminal area.pre-print1304 K
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