Micro-oxygenation is usually applied to red wines as a cheaper alternative to oak aging. It has been suggested, however, that micro-oxygenation can also be used to complement oak aging in order to improve the quality of very astringent and herbaceous red wines. In this paper we study how applying the micro-oxygenation technique before oak aging affects the composition and quality of astringent red wines. When this technique is applied prior to oak aging, the wines have a slightly less intense red color and significantly higher levels of combined and free anthocyanins and ethyl-bridged anthocyanin-flavanol pigments. On the other hand, no differences in other newly formed pigments are found. Applying micro-oxygenation before oak aging does not affect the total proanthocyanidin concentration, but it produces wines with a slightly (though significantly) higher mean degree of proanthocyanidin polymerization and a drastically lower astringency. These wines also present a clearer impact of wood aromas. 相似文献
Over the second half of the 20th century, conflicts within national boundaries became increasingly dominant. One-third of all countries experienced civil conflict. Many (if not most) such conflicts involved violence along ethnic lines. On the basis of recent theoretical and empirical research, we provide evidence that preexisting ethnic divisions do influence social conflict. Our analysis also points to particular channels of influence. Specifically, we show that two different measures of ethnic division--polarization and fractionalization--jointly influence conflict, the former more so when the winners enjoy a "public" prize (such as political power or religious hegemony), the latter more so when the prize is "private" (such as looted resources, government subsidies, or infrastructures). The available data appear to strongly support existing theories of intergroup conflict. Our argument also provides indirect evidence that ethnic conflicts are likely to be instrumental, rather than driven by primordial hatreds. 相似文献
Despite considerable current interest in biological invasions, the common life-history characteristics of successful invaders remain elusive. The widely held hypothesis that successful invaders have high reproductive rates has received little empirical support; however, alternative possibilities are seldom considered. Combining a global comparative analysis of avian introductions (>2700 events) with demographic models and phylogenetic comparative methods, we show that although rapid population growth may be advantageous during invasions under certain circumstances, more generally successful invaders are characterized by life-history strategies in which they give priority to future rather than current reproduction. High future breeding expectations reduce the costs of reproductive failure under uncertain conditions and increase opportunities to explore the environment and respond to novel ecological pressures. 相似文献
The orchestrated migration of T lymphocytes is important for generating immunity and maintaining immunological tolerance. T lymphocytes can be divided into two populations, αβ T cells and γδ T cells, on the basis of their expression of different forms of the T cell receptor (TCR). γδ T cells represent an innate subset of T lymphocytes that play an important role in early immune response against a variety of pathogens, including bacteria and viruses. γδ T cells are abundant in the epithelial tissues. In ruminants and pigs, they constitute a major proportion of the blood lymphocyte pool, unlike in rodents and humans. Although recent studies using large animals have suggested that epithelial γδ T cells are the major source of γδ T cells in peripheral blood, and that they recirculate between epithelial tissues and blood via lymphatics, the migration pattern of these cells is largely unknown. The aim of this review is to provide an overview of the current knowledge on γδ T cell migration under steady-state conditions. A deeper understanding of γδ T cell migration may enable therapeutic modulation of innate immune responses. 相似文献
Extract A great deal of evidence has now accumulated that immunity to helminth infection is acquired following natural exposure. Although this immunity is not absolute, animals that have been exposed to infection and survived are able to tolerate a much heavier intake of infective larvae than animals that have never been exposed. 相似文献
Precision Agriculture - Site-specific management strategies are usually dependant on the understanding of the underlying cause and effect relationships that occur at the within-field level. The... 相似文献
We measured the terpene concentration in pentane and water extracts from soil horizons (litter, organic, top and low mineral) and from roots growing in top and low mineral horizons on a distance gradient from Pinus halepensis L. trees growing alone on a grassland. Terpene concentrations in pentane were higher than in water extracts, although β-caryophyllene showed relatively high solubility in water. The litter and roots were important sources of terpenes in soil. Alpha-pinene dominated in roots growing in both “top” (A1) and “low” (B) mineral horizons (123 ± 36 μg g−1 or 14 ± 5 mg m−2) and roots in low mineral horizon (270 ± 91 μg g−1 or 7 ± 2 mg m−2). Beta-caryophyllene dominated in litter (1469 ± 331 μg g−1 or 2004 ± 481 mg m−2). Terpene concentration in soil decreased with increasing distance to the trunk. This is likely to be related to changes in litter and roots type on the distance gradient from pine to grass and herbs. The relative contributions of all compounds, except α-pinene, were similar in the mineral soils and litter. This suggests that litter of P. halepensis is probably the main source of major terpene compounds. However, long-term emissions of α-pinene from P. halepensis roots might also contribute to α-pinene concentrations in rhizosphere soils. 相似文献
It is known that land-use and land-cover (LULC) changes affect plant community assembly for decades. However, both the short- and the long-term effects of contrasting LULC change pathways on this assembly are seldom explored.
Objectives
To assess how LULC change pathways affect woody plant community parameters (i.e. species richness, diversity and evenness) and species’ presence and abundance, compared with environmental factors and neutral processes.
Methods
The study was performed in Mediterranean limestone scrublands in NE Spain. Cover of each woody species was recorded in 150 scrubland plots belonging to five LULC change pathways along the past century, identified using land-cover maps and fieldwork. For each plot, total woody and herbaceous vegetation cover, local environmental variables and geographical position were recorded. Effects of these pathways and factors on plant community parameters and on species presence and abundance were assessed, considering spatial effects potentially associated to neutral processes.
Results
Species richness and diversity were associated with LULC change pathways and elevation, while evenness was only associated with this last. Pathways and environmental variables explained similar variance in both species’ presence and cover. In general, while community parameters were affected by recent-past (1956) use, species presence and abundance were associated with far-past (pre-1900) cropping. No relevant spatial effect was detected for any studied factor.
Conclusions
Historical LULC changes and current environmental factors drive local-scale community assembly in Mediterranean scrublands to an equal extent, while contrasting time-scale effects are found at community and species level. Neutral, dispersal-based processes are found to be non-relevant.
The recent focus on a common movement ecology paradigm has increased awareness about the importance of distinguishing different movement patterns for understanding their specific impact on animal ecology and evolution. One specific form of movement is nomadism, where animals move between habitats in an arrhythmic fashion. Although not yet described in detail for freshwater fish, nomadism between lakes within drainage systems could affect local lake food webs in an otherwise unpredictable fashion. In this study, we used passive telemetry to describe inter‐lake movements of 1,280 individually tagged adult benthivorous bream (Abramis brama) over nine contiguous years in a drainage system with two paired lakes. The movements can best be described as partial nomadism, where a part of the population is neither resident nor migratory, but instead moves between lakes in a variable, arrhythmic fashion, often with long residency in one lake before moving to the other. We found extensive between‐year variation in the proportion and direction of bream moving, with higher movement propensity being partly associated with lower somatic condition. Notably, movements out of lakes were significantly more in direction of the neighbouring lake than away from the paired lakes, suggesting that at least direction was not random. Since bream are important ecosystem engineers, fluctuating densities of adult bream could affect ecological stability in lakes. Our study suggests that fish populations in interconnected lakes within drainages should not be treated as isolated units, and we discuss this in relation to lake ecology and the importance for lake ecosystem management. 相似文献