686 research outputs found
Why do dolphins form mixed-species associations in the Azores ?
Mixed-species associations are temporary associations between individuals of
different species that are often observed in birds, primates and cetaceans.
They have been interpreted as a strategy to reduce predation risk, enhance
foraging success and/or provide a social advantage. In the archipelago of the
Azores, four species of dolphins are commonly involved in mixed-species
associations: the common dolphin, Delphinus delphis, the bottlenose dolphin,
Tursiops truncatus, the striped dolphin, Stenella coeruleoalba, and the spotted
dolphin, Stenella frontalis. In order to understand the reasons why dolphins
associate, we analysed field data collected since 1999 by research scientists
and trained observers placed onboard fishing vessels. In total, 113
mixed-species groups were observed out of 5720 sightings. The temporal
distribution, habitat (water depth, distance to the coast), behaviour (i.e.
feeding, travelling, socializing), size and composition of mixed-species groups
were compared with those of single-species groups. Results did not support the
predation avoidance hypothesis and gave little support to the social advantage
hypothesis. The foraging advantage hypothesis was the most convincing. However,
the benefits of mixed-species associations appeared to depend on the species.
Associations were likely to be opportunistic in the larger bottlenose dolphin,
while there seemed to be some evolutionary constraints favouring associations
in the rarer striped dolphin. Comparison with previous studies suggests that
the formation of mixed-species groups depends on several environmental factors,
and therefore may constitute an adaptive response
On the stochastic mechanics of the free relativistic particle
Given a positive energy solution of the Klein-Gordon equation, the motion of
the free, spinless, relativistic particle is described in a fixed Lorentz frame
by a Markov diffusion process with non-constant diffusion coefficient. Proper
time is an increasing stochastic process and we derive a probabilistic
generalization of the equation . A
random time-change transformation provides the bridge between the and the
domain. In the domain, we obtain an \M^4-valued Markov process
with singular and constant diffusion coefficient. The square modulus of the
Klein-Gordon solution is an invariant, non integrable density for this Markov
process. It satisfies a relativistically covariant continuity equation
La influencia de la productividad en la consolidación de los grupos nacionales de la banca privada española (1900-1914)
Este trabajo analiza el fenómeno de la crisis y auge de los grupos regionales de la banca española con una nueva metodología que permite estudiar el nivel de eficiencia y la productividad de las entidades financieras. Se han obtenido dos resultados relevantes. En primer lugar, se ha confirmado la influencia de los niveles de productividad en la trayectoria más o menos exitosa de los diversos grupos regionales bancarios. En segundo lugar, se ha demostrado que el progreso general de la banca privada durante el período inmediatamente anterior a la Primera Guerra Mundial fue debido más a un incremento generalizado de la competición, que redundó en un acercamiento de cada vez más entidades a los máximos niveles de eficiencia, que al desarrollo o/y adopción de innovaciones financieras.DEA, Indice de Malmquist, Historia financiera de España
Cardiovascular and Metabolic Benefits of Extra Virgin Olive Oil Phenolic Compounds: Mechanistic Insights from In Vivo Studies
Extra virgin olive oil (EVOO) represents a significant source of monounsaturated fatty acids (MUFA) and vitamin E, but it is also considered a functional food, due to the content of peculiar bioactive molecules, such as phenolic compounds, being able to modulate various processes related to aging and the most common metabolic and degenerative diseases. A lot of experimental research has focused on some of these components, but in most cases, the studies were performed in vitro testing compounds at non-physiological concentrations and achieving results that cannot easily be translated in vivo. Recent clinical studies demonstrated that in vivo these compounds are able to regulate physiological functions and prevent several pathological events including metabolic and cardiovascular diseases (CVDs), which represent the main causes of death worldwide. This review aims to sum up the major evidence on the beneficial effects of EVOO phenolic compounds in vivo on these pathologies, describing and evaluating the efficacy in relation to the mechanisms of diseases of the whole phenolic fraction and some of its specific components
Olive Oil Phenolic Compounds’ Activity against Age-Associated Cognitive Decline: Clinical and Experimental Evidence
Epidemiological studies have shown that consuming olive oil rich in phenolic bioactive compounds is associated with a lower risk of neurodegenerative diseases and better cognitive performance in aged populations. Since oxidative stress is a common hallmark of age-related cognitive decline, incorporating exogenous antioxidants could have beneficial effects on brain aging. In this review, we firstly summarize and critically discuss the current preclinical evidence and the potential neuroprotective mechanisms. Existing studies indicate that olive oil phenolic compounds can modulate and counteract oxidative stress and neuroinflammation, two relevant pathways linked to the onset and progression of neurodegenerative processes. Secondly, we summarize the current clinical evidence. In contrast to preclinical studies, there is no direct evidence in humans of the bioactivity of olive oil phenolic compounds. Instead, we have summarized current findings regarding nutritional interventions supplemented with olive oil on cognition. A growing body of research indicates that high consumption of olive oil phenolic compounds is associated with better preservation of cognitive performance, conferring an additional benefit, independent of the dietary pattern. In conclusion, the consumption of olive oil rich in phenolic bioactive compounds has potential neuroprotective effects. Further research is needed to understand the underlying mechanisms and potential clinical applications
Seven new microendemic species of Brachycephalus (Anura:Brachycephalidae) from southern Brazil
Brachycephalus (Anura: Brachycephalidae) is a remarkable genus of miniaturized frogs of the Brazilian Atlantic Rainforest. Many of its species are highly endemic to cloud forests, being found only on one or a few mountaintops. Such level of microendemism might be caused by their climatic tolerance to a narrow set of environmental conditions found only in montane regions. This restriction severely limits the chance of discovery of new species, given the difficulty of exploring these inaccessible habitats. Following extensive fieldwork in montane areas of the southern portion of the Atlantic Rainforest, in this study we describe seven new species of Brachycephalus from the states of Paraná and Santa Catarina, southern Brazil. These species can be distinguished from one another based on coloration and the level of rugosity of the skin in different parts of their body. These discoveries increase considerably the number of described species of Brachycephalus in southern Brazil
Evidence for fungal infection in cerebrospinal fluid and brain tissue from patients with amyotrophic lateral sclerosis
Among neurogenerative diseases, amyotrophic lateral sclerosis (ALS) is a fatal illness characterized by a progressive motor neuron dysfunction in the motor cortex, brainstem and spinal cord. ALS is the most common form of motor neuron disease; yet, to date, the exact etiology of ALS remains unknown. In the present work, we have explored the possibility of fungal infection in cerebrospinal fluid (CSF) and in brain tissue from ALS patients. Fungal antigens, as well as DNA from several fungi, were detected in CSF from ALS patients. Additionally, examination of brain sections from the frontal cortex of ALS patients revealed the existence of immunopositive fungal antigens comprising punctate bodies in the cytoplasm of some neurons. Fungal DNA was also detected in brain tissue using PCR analysis, uncovering the presence of several fungal species. Finally, proteomic analyses of brain tissue demonstrated the occurrence of several fungal peptides. Collectively, our observations provide compelling evidence of fungal infection in the ALS patients analyzed, suggesting that this infection may play a part in the etiology of the disease or may constitute a risk factor for these patientsThe financial support of Fundación ONCE (Organización Nacional de Ciegos Españoles) is acknowledged. We acknowledge an institutional grant to Centro de Biología Molecular “Severo Ochoa” from the Fundación Ramón Arece
Achieving conservation through cattle ranching: the case of the Brazilian Pantanal.
Cattle ranching in the 140,000 km 2 Brazilian Pantanal is considered one of the most important cases of sustainable use of natural resources in the global south. The region has had a successful history of balancing environmental protection with the production of >3.8 million cattle. However, global change, infrastructure projects, and deforestation, threaten the sustainable use of the Pantanal. Here, using Ostrom's design principles as a framework, we interviewed 49 local stakeholders and conducted a review of secondary information aiming to evaluate the sustainability of cattle ranching practices across the region and the threats to it. We show that well-defined property boundaries, congruence between appropriation and provision rules through low-intensity cattle ranching, and co-management of resources, are all key components for achieving sustainability in the Pantanal. However, we documented shortcomings in satisfying critical aspects of Orstrom's design principles. Specifically, we argue that the Pantanal needs better biodiversity and behavior monitoring, the creation of platforms or mechanisms to solve local conflicts around resource access and use, recognition by governments and international bodies of the local efforts to promote local sustainability, and the creation of networks effectively connecting existing sustainability initiatives.Online First
Imobilização Articular: Efeitos Sobre O Tecido Muscular De Camundongos Obesos E Desnutridos
Although it is a widely used resource for the treatment of musculoskeletal injuries, immobilization causes deleterious effects in muscle tissue after a short period of time. This study aimed to evaluate the gastrocnemius and tibialis anterior muscles of obese and protein malnourished animals under joint immobilization condition. Overall, 28 adult male mice were used (C57/BL6), being divided into four groups (N = 7): Control Group (CG), Immobilized Control Group (ICG), Immobilized Obese Group (IOG) and Immobilized Malnourished Group (IMG). The immobilization protocol was performed by the use of adhesive tape and plaster. The conditions and obesity and protein malnutrition have been developed through the ingestion of diets specific for each group of animals. The histomorphometric analysis of muscles evaluated area and the diameter of muscle fibers. All immobilized groups showed reduction in the area and diameter of muscle fibers when compared to GC. Comparisons among immobilized groups showed that the area and diameter of muscle fibers of IOG and IMG were lower than ICG. The immobilization protocol caused reduction in muscle trophism in animals, and obese and malnourished animals suffered high losses under condition of muscle atrophy. © 2016, Universidade Federal de Santa Catarina. All rights reserved.18111
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