3,477 research outputs found
Seagrass Patch Complexity Affects Macroinfaunal Community Structure in Intertidal Areas: An In Situ Experiment Using Seagrass Mimics
[EN] Seagrasses, as key ecosystem engineers in coastal ecosystems, contribute to enhancing diversity in comparison with nearby bare areas. It has been proved mainly for epifauna, but data on infauna are still scarce. The present study addresses how seagrass structural complexity (i.e., canopy properties) affects the diversity of infaunal organisms inhabiting those meadows. Canopy attributes were achieved using seagrass mimics, which were used to construct in situ vegetation patches with two contrasting canopy properties (i.e., shoot density and morphology) resembling the two seagrass species thriving in the inner Cadiz Bay: Zostera noltei and Cymodocea nodosa. After three months, bare nearby areas, two mimicked seagrass patches (‘Zostera’ and ‘Cymodocea’), and the surrounding natural populations of Zostera noltei were sampled in a spatially explicit way. Shifts in organism diets were also determined using15N and13C analyses in available food sources and main infaunal organisms, mixing models, and niche metrics (standard ellipse area). Seagrass-mimicked habitats increased the species richness (two-fold), organism abundance (three to four times), and functional diversity compared with bare nearby areas. The clam Scrobicularia plana (deposit/filter feeder) and the worm Hediste diversicolor (omnivore) were dominant in all of the samples (> 85%) and showed an opposite spatial distribution in the reconstructed patches: whilst S. plana accumulated in the outer-edge parts of the meadow, H. diversicolor abounded in the center. Changes in the isotopic signature of both species depending on the treatment suggest that this faunal distribution was associated with a shift in the diet of the organisms. Based on our results, we concluded that facilitation processes (e.g., reduction in predation and in bioturbation pressures) and changes in food availability (quality and quantity) mediated by seagrass canopies were the main driving forces structuring this community in an intertidal muddy area of low diversitySIThis work was supported by the Spanish Project PAVAROTTI (CTM2017-85365-R) from the Ministry of Science and Innovation and by the Junta de Andalucía Excellence Project PAMBIO (P08-RNM-03783
Linear approach to the orbiting spacecraft thermal problem
We develop a linear method for solving the nonlinear differential equations
of a lumped-parameter thermal model of a spacecraft moving in a closed orbit.
Our method, based on perturbation theory, is compared with heuristic
linearizations of the same equations. The essential feature of the linear
approach is that it provides a decomposition in thermal modes, like the
decomposition of mechanical vibrations in normal modes. The stationary periodic
solution of the linear equations can be alternately expressed as an explicit
integral or as a Fourier series. We apply our method to a minimal thermal model
of a satellite with ten isothermal parts (nodes) and we compare the method with
direct numerical integration of the nonlinear equations. We briefly study the
computational complexity of our method for general thermal models of orbiting
spacecraft and conclude that it is certainly useful for reduced models and
conceptual design but it can also be more efficient than the direct integration
of the equations for large models. The results of the Fourier series
computations for the ten-node satellite model show that the periodic solution
at the second perturbative order is sufficiently accurate.Comment: 20 pages, 11 figures, accepted in Journal of Thermophysics and Heat
Transfe
Solution-phase racemization in the presence of an enantiopure solid phase.
Solution-phase racemization
drives the evolution of single chirality
in the solid phase by the "chiral amnesia"
process first described by Viedma.
The current investigations lay the basis
for a better understanding of the mechanism
of the solid-phase deracemization
by uncoupling the chemical rate
processes associated with the interconversion
of enantiomers in the solution
phase from the physical processes associated
with solution-solid phase transfer
via dissolution and reaccretion of
molecules onto crystals. In addition,
the enantiomer concentration profiles
presented in this work, together with
an analytical treatment of the racemization
process in the presence of excess
enantiopure solid, unequivocally reconfirm
the validity of the Meyerhoffer
double solubility rule for systems
under solution racemization conditions
Driving-induced crossover: from classical criticality to self-organized criticality
We propose a spin model with quenched disorder which exhibits in slow driving
two drastically different types of critical nonequilibrium steady states. One
of them corresponds to classical criticality requiring fine-tuning of the
disorder. The other is a self-organized criticality which is insensitive to
disorder. The crossover between the two types of criticality is determined by
the mode of driving. As one moves from "soft" to "hard" driving the
universality class of the critical point changes from a classical
order-disorder to a quenched Edwards-Wilkinson universality class. The model is
viewed as prototypical for a broad class of physical phenomena ranging from
magnetism to earthquakes.Comment: 4 pages, 4 figure
Effect of pasteurization and lactic acid bacteria on physicochemical, microbiological and sensorial characteristics of costeño cheese
The effect of pasteurization and starter cultures on physicochemical, microbiological and sensorial characteristics of costeño cheese was determined. A completely randomized design was conducted, three treatments (T) and three replicates: Treatment 1 (T1): cheese manufactured with pasteurized milk without starter cultures, Treatment 2 (T2): cheese manufactured with pasteurized milk with Lactococcus lactis and Lactococcus cremoris (1:1) and treatment 3 (T3): cheese manufactured with pasteurized milk with Lactococcus lactis, Lactococcus cremoris and Streptococcus thermophillus (0.5:0.5:1). Treatments were compared to a control sample that was prepared with raw milk without starter cultures. Concentration of 1.5% (v/v) of culture was used in relation to the amount of used milk in each treatment. Moisture content was higher in all treatments compared to the control and protein and fat content were significantly lower. Acidity was significantly higher in samples from T2 y T3 compared to T1 and control, due to the metabolism of starter cultures. Total coliforms, yeast and mold counts showed a significant reduction due to pasteurization process in all treatments. Regarding sensorial analysis, hedonic test showed a greater preference in cheese manufactured with T2 (P0.05). There were no significant preferences between T1, T3 and control. Additionally, yield was significantly higher with T1 (22%) and T3 (23%) compared to control
Effect of Grazing Management on Herbage Accumulation of Lucerne-Orchard Grass Sward
Throughout most of México, lucerne (Medicago sativa) is the primary forage legume used in the dairy industry. Unfortunately, lucerne does not grow in late autumn and winter due to adverse weather. Recent studies with lucerne have suggested that the inclusion of a companion grass will invariably increase the seasonal distribution and total annual yield of swards (Laidlaw & Teuber, 2001). However the management of mixed swards containing lucerne is difficult as a grazing frequency or intensity which suits one species may be detrimental to the other. Changes in balance between grass and legume, especially in grazed swards, have been observed. In México mixtures of lucerne-orchard grass have a good persistence and productivity. However the explanation for this is unclear. This study examined the effects of different grazing management practices on lucerne-orchard grass production and seasonal distribution
Detoxifying enzymes at the cross-roads of inflammation, oxidative stress, and drug hypersensitivity: role of glutathione transferase P1-1 and aldose reductase
9 p.-2 figPhase I and II enzymes are involved in the metabolism of endogenous reactive
compounds as well as xenobiotics, including toxicants and drugs. Genotyping studies
have established several drug metabolizing enzymes as markers for risk of drug
hypersensitivity. However, other candidates are emerging that are involved in drug
metabolism but also in the generation of danger or costimulatory signals. Enzymes
such as aldo-keto reductases (AKR) and glutathione transferases (GST) metabolize
prostaglandins and reactive aldehydes with proinflammatory activity, as well as drugs
and/or their reactive metabolites. In addition, their metabolic activity can have important
consequences for the cellular redox status, and impacts the inflammatory response
as well as the balance of inflammatory mediators, which can modulate epigenetic
factors and cooperate or interfere with drug-adduct formation. These enzymes are, in
turn, targets for covalent modification and regulation by oxidative stress, inflammatory
mediators, and drugs. Therefore, they constitute a platform for a complex set
of interactions involving drug metabolism, protein haptenation, modulation of the
inflammatory response, and/or generation of danger signals with implications in drug
hypersensitivity reactions. Moreover, increasing evidence supports their involvement in
allergic processes. Here, we will focus on GSTP1-1 and aldose reductase (AKR1B1) and provide a perspective for their involvement in drug hypersensitivityThis work has been supported by grants SAF2012-36519 from MINECO and SAF-2015-68590-R from MINECO/FEDER and ISCIII RETIC RIRAAF RD12/0013/0008 to DP,and RD12/0013/0002 to J A.Peer reviewe
The C-terminal peptide of H-Ras as a target for the covalent binding of drugs modulating ras-dependent pathways
Comunicaciones a congreso
Evidencias do cambio climático na hidrografía e a dinámica das rías e da plataforma galega
16 páginas, 9 figuras, 3 tablas[EN] This study is focused on multidecadal-scale variations of the hydrographic and hydrodynamic features
of Rías and shelf waters off Galicia. Water masses take, through their thermohaline characteristics,
a footprint of the climatic variability, mainly caused by changes either in the hydrological budget
(precipitation, evaporation, runoff), in heat exchange and wind stress. In this study we focus in the
evidences of change in the surface and sub-surface water mass characteristics. Regarding surface
water masses, a significant warming during the last 45 years has been noticed, at a rate of 0.17 ºC/
decade. This warming was especially intense from the 1970’s, 0.27 ºC/decade. The tendency is
opposite in subsurface waters, but it only takes into account data from the last 15 years. Regarding
hydrodynamics, because of its strong influence in the renewal time of the Rías and consequently in
their living resources, a study of decadal changes in the estuarine circulation of the Rías de Vigo
and Arousa has been made. Results showed a progressive decay in the estuarine circulation, which causes an increase of renewal times. On the other hand, indirect evidence of a possible deceleration
of the winter Iberian Poleward Current (IPC) are reported. This slow down is partially caused by a
decrease in the meridional (N-S) temperature gradient off the Iberian coast. Nevertheless, the fall of
the meridional gradient is not clear because it has been inferred from surface waters. On the contrary,
IPC seems to be intensified by the increasing southerly autumn winds, although it appears weakened
by the decreasing southerly winter winds. Thus, the overall effect of the CIP is still uncertain. Finally, a
study of sea level and wave changes on the Galician coast has been made. An increase of (2-2.5 cm/
decade) in the sea level as well as a decrease in the wave height (3 cm/decade) has been reported,
but in this last topic results are not significant[GA] Este estudo centrarase en determinar as variacións que ocorren a escalas multidecadais nas características
hidrográficas e hidrodinámicas das augas das rías e da plataforma fronte a Galicia. As
masas de auga reciben a través das súas características termohalinas unha pegada das alteracións
climáticas, principalmente a causa de cambios no balance hidrolóxico (precipitación, evaporación,
achegas continentais), do intercambio de calor e da acción do vento. Neste estudo analizaremos
as evidencias de cambio nas características das masas de auga superficiais e subsuperficiais. Nas
primeiras detectouse quentamento de xeito significativo nos últimos 45 anos a unha taxa media de
0,17 ºC por década, especialmente intenso desde hai 30 anos, 0,27 ºC por década. Nas augas
subsuperficiais a tendencia é a inversa, aínda que só se conta con datos dos últimos 15 anos. En
canto á hidrodinámica, e pola súa forte implicación nos tempos de renovación da ría e, polo tanto,
nos recursos mariños que viven nela, fíxose un estudo sobre os cambios na circulación estuárica das
rías de Vigo e Arousa nas últimas décadas. Os resultados amosan un descenso paulatino a longa
escala temporal da circulación que causa un aumento dos tempos de renovación. Por outra banda,
achéganse evidencias indirectas dunha posible ralentización da corrente invernal cara ao Polo (CIP)
causada por un descenso no gradiente meridional (N-S) de temperatura fronte ás costas ibéricas.
Non obstante, o descenso do gradiente meridional non está claro, pois induciuse só a partir de datos
superficiais. Ademais, a propia CIP amosa estar intensificada pola maior intensidade dos ventos sur
no outono e debilitada polo descenso dos ventos do sur no inverno, polo que o efecto global na CIP
é aínda incerto. Por último, faise un estudo dos cambios do nivel do mar e da ondada nas costas
galegas que amosa un aumento daquel (2-2,5 cm/década) e un descenso desta (3 cm/década),
aínda que no caso da ondada os resultados non son concluíntesPeer reviewe
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