We performed an experimental study on 46 male rats to evaluate the vitality of superficial inferior epigastric neurovenous flaps performed following different procedures.
Rats were divided into 5 ...groups: A (n=6), B (n=10), C (n=10), D (n=10) and E (n=10). On each rat a hemi-abdominal flap based on the superficial inferior epigastric pedicle was raised. In group A the flap was sutured into its original position, isolating it from underlying tissues by a latex glove patch. In group B an arteriectomy of the superficial inferior epigastric artery was performed. In group C the superficial inferior epigastric artery was sectioned at its origin, without dissecting it out of the pedicle. In group D and E the same procedures performed respectively in group B and C were followed, but the epigastric pedicles were immediately explanted for optic microscope observation. Flap vitality in groups A, B and C was checked after 7 days.
Flaps in group A appeared completely vital: the glove did not interfere with flap survival. All flaps in group B looked necrotic. In group C, 9 flaps survived completely and 1 flap underwent complete necrosis. Pedicle specimens of the viable flaps (group C) were explanted for observation under the optic microscope. Each specimen from groups C, D, E revealed a rich vascular plexus in the connective tissue around the pedicle. Seven days after surgery, neo-microangiogenesis was evident.
The results witness the importance of perivenous and perineural arterioles for neurovenous flaps survival, also considering the adaptive increase in capillary development in the days following surgery.
The rat is a good model for experimental studies on the haemodynamic patterns of free-flap transfer but models involving the superficial epigastric vein have not been supported by the demonstration ...of the anatomical presence or absence of valves inside it. We performed a morphological study to assess whether or not valves are present inside the superficial epigastric vein of the rat. Segments of superficial epigastric veins were explanted from fifteen Sprague-Dawley rats. The lumen was studied with scanning electron microscopy after longitudinal or transverse incision of the venous walls. No valves were detected and we saw no evidence of their accidental removal. As most human veins do have valves, the clinical implications of haemodynamic data on reverse-flow island flaps obtained in rats must be considered very carefully.
In the paper a multi-objective optimization model for distributed energy supply systems optimization is presented. The superstructure of the system comprehends a district heating network that ...connects the users to each other, small-scale CHP systems, large centralized solar plant and a thermal storage. The optimization has to determine the optimal structure of the system, the size of each component inside the optimal solution and the optimal operation strategy. The multi-objective optimization is based on a MILP (Mixed Integer Linear Programming) model and takes into account as objective function a linear combination of the annual cost for owning, maintaining and operating the whole system and the CO2 emissions associated to the system operation. The model allows to obtain different optimal solutions by varying the relative weight of the economic and the environmental objectives. In this way the Pareto Front is identified and the possible improvements in both economic and environmental terms can be highlighted. The model has been applied to a specific case study and it has been optimized for different superstructure configurations and for two different values of the electricity carbon intensity. The obtained results show that the solar plant, coupled with the optimal thermal storage, allows reaching both environmental and economic goals.
► Definition of a multi-objective optimization model for a distributed energy supply system. ► Linear model of a distributed cogeneration system, with a central solar field and a thermal storage. ► Optimization of an industrial area energy system from environmental and economic point of view. ► Investigation of the effects of the electricity carbon intensity variation on the optimal configuration.
Investigating eco‐evolutionary responses of populations to environmental changes requires a solid understanding of the spatial context in which they evolve. While the interplay between local ...adaptation and dispersal in guiding evolutionary outcomes has been studied extensively, it is often in a context of divergent selection and simplified spatial structure. Alternatively, we used a spatially‐explicit demo‐genetic agent‐based model to simulate a complex network of interconnected populations of Atlantic salmon facing a perturbation shifting their genetic composition to create diversity among populations. Our model allowed us to track emerging demographic, phenotypic, and evolutionary changes from the individual to the metapopulation in a single, spatially realistic framework. We analyzed the influence of the spatial structure of genetic diversity and populations on the evolutionary dynamics under convergent selection (toward a common optimum). Our simulations showed adaptation and demographic recovery of local populations was enhanced by dispersal between initially diverse populations, providing general support for the adaptation network theory. This was particularly true for increased dispersal rates and a random spatial genetic structure. Importantly, our spatially realistic model emphasized that the evolutionary and demographic trajectories of local populations are context‐dependent and can be heavily influenced by the spatial configuration of populations linked by dispersal. Overall, the adaptive capacity of the network depended on the ‘opportunity for adaptation' provided by immigration patterns that emerged from the connectivity structures of the scenarios tested. We highlight the importance of spatial diversity and population structure for the ability of species to respond to environmental change, with implications for management and conservation of spatially structured populations.
Recent research has highlighted interdependencies between dispersal and other life‐history traits, i.e. dispersal syndromes, thereby revealing constraints on the evolution of dispersal and ...opportunities for improved ability to predict dispersal by considering suites of dispersal‐related traits. This review adds to the growing list of life‐history traits linked to spatial dispersal by emphasising the interdependence between dispersal through space and time, i.e. life‐history diversity that distributes individuals into separate reproductive events. We reviewed the literature that has simultaneously investigated spatial and temporal dispersal to examine the prediction that traits of these two dispersal strategies are negatively correlated. Our results suggest that negative covariation is widely anticipated from theory. Empirical studies often reported evidence of weak negative covariation, although more complicated patterns were also evident, including across levels of biological organisation. Existing literature has largely focused on plants with dormancy capability, one or two phases of the dispersal process (emigration and/or transfer) and a single level of biological organisation (theory: individual; empirical: species). We highlight patterns of covariation across levels of organisation and conclude with a discussion of the consequences of dispersal through space and time and future research areas that should improve our understanding of dispersal‐related life‐history syndromes.
Dispersal and shared environmental conditions can both synchronize the dynamics of local populations, but disentangling their relative influence on dynamics is challenging. We used a Bayesian ...approach to estimate the synchrony of a metapopulation of Atlantic salmon (Salmo salar) composed of 18 populations in Brittany, France, including a 24-year time series of the abundances of juveniles. We estimated the spatial synchrony at a regional and local spatial scale over the study period. We found a strong regional synchrony despite spatiotemporal variability of local synchrony in the abundance of juveniles. We then explored the drivers of synchrony, including environmental conditions (aspects of river flow) and abundance of adult breeders. This revealed that summer low-flow conditions seemed to synchronize the abundances of juveniles more than the synchrony in the abundance of adult breeders, suggesting a Moran effect. Given that drought conditions are expected to become more common with climate change, our work highlights the potentially strong synchronizing effect of summer low flow on the dynamics of local salmon populations and the benefits of considering synchrony at multiple scales.
Precipitation drives global variation in natural selection Siepielski, Adam M.; Morrissey, Michael B.; Buoro, Mathieu ...
Science (American Association for the Advancement of Science),
03/2017, Letnik:
355, Številka:
6328
Journal Article
Recenzirano
Odprti dostop
Climate change has the potential to affect the ecology and evolution of every species on Earth. Although the ecological consequences of climate change are increasingly well documented, the effects of ...climate on the key evolutionary process driving adaptation—natural selection—are largely unknown. We report that aspects of precipitation and potential evapotranspiration, along with the North Atlantic Oscillation, predicted variation in selection across plant and animal populations throughout many terrestrial biomes, whereas temperature explained little variation. By showing that selection was influenced by climate variation, our results indicate that climate change may cause widespread alterations in selection regimes, potentially shifting evolutionary trajectories at a global scale.
PDF
