631 research outputs found
Short Communication: Systems-based conservation and conflicts between species protection programs
Although the conflict between conservation efforts and economic growth is a
major topic of conservation science, the conflicts between different
conservation projects are much less documented and represented in the
literature. We provide an overview of some case studies where these conflicts
arise and discuss how to manage and solve them. We argue that conflicts are
unavoidable, and that we can find optimal and efficient solutions only by
studying the holistic, macroscopic properties of whole socio-ecological
systems. Novel computational solutions offer simple and efficient simulation
toolkits providing indicators that can support strategic and integrative
decisions from a systems perspective
Trophic fields
In complex, modern food webs, the analysis of pairwise interactions gives weak predictions of the behaviour of either single species or the whole community. Indirect effects call for explicit study and quantification. However, just as focusing only on pairwise interactions is incorrect, overemphasising the role of long, indirect pathways also seems to be unrealistic. Thus, a reasonable range of indirect trophic effects spreading through the food web is to be defined and quantified. I suggest a graph theoretical measure for quantifying this range, considering only network position (topology). I call this the trophic field of a species (or trophic group), recalling the idea that field theory could be a fruitful research programme in biology. Further, I propose a measure for the quantification of the indirect component of the trophic field. Finally, the use of introduced concepts and indices is illustrated by analysing the trophic flow network of the Schlei Fjord ecosystem (N. Germany)
Strong threads and weak chains? - a graph theoretical estimation of the power of indirect effects
Food webs inform about both direct trophic interactions (predation and food supply) and implicitly involved, indirect ones (e. g. exploitative competition). Traditionally, direct links between species are considered stronger and more important. However, as a body of experimental results suggests, indirect links may well be able to surpass their effects. In this paper, after shortly summarizing an interesting case study, I propose a simple structural approach to estimate the role of indirect vs. direct effect
Is the role of trophic control larger in a stressed ecosystem?
Macroscopic ecosystem studies often complete our knowledge based on population-level experiments and models. In this paper, the changed control of ecosystem functioning is reported by analyzing the structure of the energy flow network of a tidal marsh community (Crystal River, Florida). The positional importance of trophic components is characterized by a graph theoretical approach. Then, positional importance of points is compared to the magnitude of fitting carbon flows (i.e., the importance of links) and the congruency is expressed in percents. These results are presented for both an unperturbed (control) and a thermally stressed creek ecosystem of the river. The comparison of average congruency values for the two communities suggests that, first, trophic control may be stronger in the stressed community and, second, the reliability of carbon flows is also higher in the stressed ecosystem
A First Attempt into the Production of Acylglycerol Mixtures from Echium Oil
Enzymatic glycerolysis of Echium oil (Echium plantagineum) has been carried out in the presence of four commercial lipases. Different pretreatments of the reaction mixture, such as high pressure homogenization and addition of food grade monoolein as an emulsifier, were evaluated to test their influence on the glycerolysis reaction. In addition, the impact of reducing temperature and the utilization of a solvent generally recognized as safe as a flavoring agent, such as limonene, were also investigated. Conversion of ca. 60-70% of triacylglycerols and production of ca. 25-30% of monoacylglycerols (MAGs) were attained. Finally, at the best reaction conditions, the glycerolysis reaction was scaled up at pilot plant and the product mixture obtained was fractionated via molecular distillation. From this stage, two products were attained: a distillate containing 80% of MAGs and a residue containing approximately 50% of diacylglycerols and 50% of triacylglycerols. All these mixtures can be utilized as self-emulsifying vehicles for the formulation of bioactive substances and also as precursors for the production of structured bioactive lipidsThis work was supported by the Ministerio de Economía y Competitividad (INNSAOLI, project number IPT-2011-1248- 060000, subprograma INNPACTO) and the Comunidad de Madrid (ALIBIRD, project number S2013/ABI-2728
Simulating Food Web Dynamics along a Gradient: Quantifying Human Influence
Realistically parameterized and dynamically simulated food-webs are useful tool to explore the importance of the functional diversity of ecosystems, and in particular relations between the dynamics of species and the whole community. We present a stochastic dynamical food web simulation for the Kelian River (Borneo). The food web was constructed for six different locations, arrayed along a gradient of increasing human perturbation (mostly resulting from gold mining activities) along the river. Along the river, the relative importance of grazers, filterers and shredders decreases with increasing disturbance downstream, while predators become more dominant in governing eco-dynamics. Human activity led to increased turbidity and sedimentation which adversely impacts primary productivity. Since the main difference between the study sites was not the composition of the food webs (structure is quite similar) but the strengths of interactions and the abundance of the trophic groups, a dynamical simulation approach seemed to be useful to better explain human influence. In the pristine river (study site 1), when comparing a structural version of our model with the dynamical model we found that structurally central groups such as omnivores and carnivores were not the most important ones dynamically. Instead, primary consumers such as invertebrate grazers and shredders generated a greater dynamical response. Based on the dynamically most important groups, bottom-up control is replaced by the predominant top-down control regime as distance downstream and human disturbance increased. An important finding, potentially explaining the poor structure to dynamics relationship, is that indirect effects are at least as important as direct ones during the simulations. We suggest that our approach and this simulation framework could serve systems-based conservation efforts. Quantitative indicators on the relative importance of trophic groups and the mechanistic modeling of eco-dynamics could greatly contribute to understanding various aspects of functional diversity
Situación Actual del Empleo con Apoyo en España
The article presents a study on the quantitative status of Supported Employment in Spain. It has been developed by the Institute for Community Integration (INICO) of the University of Salamanca in collaboration with Spanish Association for Supported Employment (AESE). Every known program was contacted and relevant information was gathered using a questionnaire. The results of the study show that there are 35 programs in the whole of Spain which have supported 1,389 individuals. In the study, some other factors are analysed: evolution, autonomous community distribution, maintained jobs, persons integrated by type of disability, continuance in the job, support needs, job coaches per post, and participation in European Community funding. Eventually, the study is drawn to an end by a critical analysis of gathered data and some conclusions and suggestions are put forward so as to guide the development of Supported Employment programs
Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars
CONTEXT. Exoplanet searches have demonstrated that giant planets are
preferentially found around metal-rich stars and that their fraction increases
with the stellar mass. AIMS. During the past six years, we have conducted a
radial velocity follow-up program of 166 giant stars, to detect substellar
companions, and characterizing their orbital properties. Using this
information, we aim to study the role of the stellar evolution in the orbital
parameters of the companions, and to unveil possible correlations between the
stellar properties and the occurrence rate of giant planets. METHODS. Using
FEROS and CHIRON spectra, we have computed precision radial velocities and we
have derived atmospheric and physical parameters for all of our targets.
Additionally, velocities computed from UCLES spectra are presented here. By
studying the periodic radial velocity signals, we have detected the presence of
several substellar companions. RESULTS. We present four new planetary systems
around the giant stars HIP8541, HIP74890, HIP84056 and HIP95124. Additionally,
we find that giant planets are more frequent around metal-rich stars, reaching
a peak in the detection of = 16.7% around stars with
[Fe/H] 0.35 dex. Similarly, we observe a positive correlation of the
planet occurrence rate with the stellar mass, between M 1.0 -2.1
M, with a maximum of = 13.0%, at M = 2.1
M. CONCLUSIONS. We conclude that giant planets are preferentially
formed around metal-rich stars. Also, we conclude that they are more
efficiently formed around more massive stars, in the mass range of M
1.0 - 2.1 M. These observational results confirm previous
findings for solar-type and post-MS hosting stars, and provide further support
to the core-accretion formation model.Comment: Accepted for publication in A&
LAS LEYES DEL EMPERADOR HONORIO(395-423 d.C.): MISTICISMO Y ORATORIA. LA MAGIA DE LA PALABRA ESCRITA
In this article I intend to demonstrate, using a selection of laws, the philosophy and the mysticism of the Emperor in certain circumstances that took place in the period which coincides with the crises of the Roman State at the beginning of the fifth century A.C. The laws in the C. Th. and the information which they provide, are complemented by the data obtained from the historical sources of the epoch. At the same time a growing mysticism can be observed in the imperial legislation, an obsesion for the unity and a fear of the Final Judgement of God. History is converted into the reflection of the Divine Providence. (...
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