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During migration, swimming in schools provides fish with a number of behavioural and ecological advantages, including increased food supply and reduced predation risk. Previous work shows that carangiform and tunniform swimming result in energetic advantages for individuals using a diamond swimming formation. However, little is known about the potential energetic advantage associated with schooling for anguilliform fish, such as European eel. European eels migrate over a long distance to their spawning area in the Sargasso Sea and may experience energetic advantages when swimming in schools. In this study the effect of group-wise swimming on the cost of transport was tested. In addition, the swimming pattern of eels swimming in groups was studied. Male silver eels were individually subjected to an increased velocity test (0.4–0.9 m s − 1 ) with increments of 0.1 m s − 1 every 2 h. Groups comprising of seven males were swum following the same protocol. Video recordings were obtained to analyse tail beat frequency at the various water speeds. At all swimming speeds the oxygen consumption was significantly lower in group-wise vs. individually swimming males. The cost of transport at the optimal swimming speed of group-wise swimming males was significantly lower than that of the individually swimming males (21.3 ± 3.2 vs. 32.0 ± 0.6 mg O 2 kg − 1 h − 1 , respectively). The optimal swimming speeds, however, were not significantly different (0.57 ± 0.02 and 0.52 ± 0.04 m s − 1 respectively). At speeds of 0.50 m s − 1 and above, tail beat frequency was lower in males swimming in groups than in males swimming individually (2.6 ± 0.1 and 3.8 ± 0.1, respectively). In contrast to the ‘diamond’ shape pattern of many group-wise swimming fish, eels tend to swim in a synchronized fashion parallel to each other, possibly reducing swimming costs by Karman gaiting. Although not an evidence, the present study provides support for the assumption of group migration in European eels.

Background Necrotizing enterocolitis (NEC) is an important cause of mortality and morbidity in preterm infants. Aims To evaluate the effect of maternal preeclampsia on the development and severity of NEC in premature infants. Study design Prospective observational study in a tertiary neonatal intensive care unit. Subjects The preterm infants of ≤ 37 gestational age who were consecutively hospitalized were enrolled. The study group contained preterm infants born to a preeclamptic mother and the comparison group contained preterm infants born to a normotensive mother. Outcome measures The primary outcome was to determine the association between preeclampsia and NEC. Results A total of 88 infants had NEC diagnosis. The incidence of NEC in infants born to preeclamptic mothers (22.9%) was significantly higher compared with those born to normotensive mothers (14.6%). According to NEC stages, NEC was more advanced in preeclamptic mother infants. NEC developed significantly earlier in infants with NEC in the study group. The duration of NEC was also significantly longer in infants born to preeclamptic mothers. In multiple logistic regression model, preeclampsia was found to be predictive of NEC with an odds ratio of 1.74 (95% confidence interval 0.64–0.92). Conclusions Maternal preeclampsia may be an important risk factor for the development of NEC in premature infants as NEC incidence and severity of NEC were found to be significantly higher in premature infants born to preeclamptic mothers. The onset of NEC was significantly earlier and duration of NEC was longer in these infants.

Neuronal computation is energetically expensive. Consequently, the brain's limited energy supply imposes constraints on its information processing capability. Most brain energy is used on synaptic transmission, making it important to understand how energy is provided to and used by synapses. We describe how information transmission through presynaptic terminals and postsynaptic spines is related to their energy consumption, assess which mechanisms normally ensure an adequate supply of ATP to these structures, consider the influence of synaptic plasticity and changing brain state on synaptic energy use, and explain how disruption of the energy supply to synapses leads to neuropathology.

In the last decades the Lattice Boltzmann method (LB) has been successfully used to simulate a variety of processes. The LB model describes the microscopic processes occurring at the cellular level and the macroscopic processes occurring at the continuum level with a unique function, the probability distribution function. Recently, it has been tried to couple deterministic approaches with probabilistic cellular automata (probabilistic CA) methods with the aim to model temporal evolution of tumor growths and three dimensional spatial evolution, obtaining hybrid methodologies. Despite the good results attained by CA-PDE methods, there is one important issue which has not been completely solved: the intrinsic stochastic nature of the interactions at the interface between cellular (microscopic) and continuum (macroscopic) level. CA methods are able to cope with the stochastic phenomena because of their probabilistic nature, while PDE methods are fully deterministic. Even if the coupling is mathematically correct, there could be important statistical effects that could be missed by the PDE approach. For such a reason, to be able to develop and manage a model that takes into account all these three level of complexity (cellular, molecular and continuum), we believe that PDE should be replaced with a statistic and stochastic model based on the numerical discretization of the Boltzmann equation: The Lattice Boltzmann (LB) method. In this work we introduce a new hybrid method to simulate tumor growth and immune system, by applying Cellular Automata Lattice Boltzmann (CA-LB) approach. (c) 2011 Elsevier B.V. All rights reserved.

Introduced Pacific oysters Crassostrea gigas have expanded rapidly in the Dutch Oosterschelde estuary, while stocks of native bivalves declined slightly. As a consequence, total filtration pressure increased significantly, which may affect the mortality of bivalve larvae. Better escape abilities in Pacific oyster larvae might be a contributing factor to their rapid geographic expansion. To study whether C gigas larvae are filtered less than larvae of native bivalves, we investigated filtration and ingestion of the larvae of the native Mytilus edulis and introduced C. gigas by the adults of C gigas and M. edulis as well as the native Cerastoderma edule.We measured filtration rates of C gigas and M. edulis larvae by the adult bivalves (C gigas, M. edulis and C. edule), and compared these to filtration rates of algae. Additionally, we studied the fate of filtered larvae. All three adult species filtered both C gigas and M. edulis larvae. M. edulis larvae were filtered by all three bivalve species with the same filtration rates as algae, whereas filtration rates of C gigas larvae were roughly 50% lower than filtration rates of algae. This suggests that C. gigas larvae can somehow reduce their filtration risk, whereas larvae of M. edulis cannot. The majority of filtered C. gigas and M. edulis larvae were ingested. (C) 2008 Elsevier B.V. All rights reserved.

The burning of two species of pine needles: Pinus halepensis and Pinus pinaster, was studied to characterize the behavior of the forest floor in wildland fires. These fuels are representative of the Mediterranean ecosystem and have very different shapes and surface-to-volume ratios. Calorimetry was performed using the FM-global fire propagation apparatus (FPA). To better understand the effects of transport in the fuel beds, the standard sample holder was replaced by a holder that allowed for the porous properties of the fuel to be studied in a systematic manner. These holders were designed with holes on the surface to allow for different air flow rates to pass through the holder and into the fuel sample. These characteristics created different internal fuel bed conditions and were the first such tests that could be identified that examined transport on this level in these types of wildland fuels. Tests were conducted under natural convection and forced flow. The test series results were analyzed with respect to the direct values of the measured variables and calculated values of heat release rate. Discrete variables of time to ignition, duration of flaming combustion and peak heat release rate were compared using an analysis of variance method. As the experiments were conducted under well-ventilated conditions, the heat release rate calculated by calorimetry was compared to mass loss rate and heat of combustion. CO concentration in time proved to be a good indicator of the combustion dynamics in the fuel bed. Heat release rate, time to ignition and time to reach peak heat release rate indicated a strong dependence on flow conditions and on fuel specie. It was shown that the transport processes in the fuel beds had a significant effect on the burning characteristics.

The determination of the appropriate energy and nutritional requirements of a newborn infant requires a clear goal of the energy and other compounds to be administered, valid methods to measure energy balance and body composition, and knowledge of the neonatal metabolic capacities. Providing an appropriate amount of energy to newborn infants remains a challenge considering the great number of newborn infants who suffer in-hospital growth retardation. The energy requirements of a newborn infant are influenced by several factors - basal metabolism, growth, energy expenditure, and energy losses - which change continuously during development. Calculating the energy requirements of preterm infants is subject to error if general recommendations are applied without recognition of the large variation in factors that influence, for example, energy expenditure. Therefore, energy recommendations should be individualized and preferably based on measurements of energy expenditure. In particular, extremely low birth-weight and very low birth-weight infants are prone to develop negative energy and nutrient balances, due to Low energy intake, low energy reserves and high energy demands. Early energy accretion is not only essential for growth but also influences neurodevetopmental outcome and physical health in the tong term, thereby underlining the importance of adequate neonatal nutrition. (c) 2006 Elsevier Ltd. All rights reserved.

Respiratory water loss in Starlings (Sturnus vulgaris) at rest and during flight at ambient temperatures (T-amb) between 6 and 25 degrees C was calculated from respiratory airflow and exhaled air temperature. At rest, breathing frequency f(1.4 +/- 0.3 Hz) and tidal volume V-t (1.9 +/- 0.4 ml) were independent of T-amb but negatively correlated with each other. Mean ventilation at rest was 156 +/- 28 ml min(-1) at all T-amb. Exhaled air temperature (T-exh) at rest increased with T-amb (T-exh=0.92 center dot T-amb+12.45). Respiratory water loss at rest averaged 0.18 +/- 0.09 ml h(-1) irrespective of T-amb. In flying Starlings f was 4.0 +/- 0.4 Hz and independent of T-amb. V-t during flight averaged 3.6 +/- 0.4 ml and increased with T-amb (V-t=0.06 center dot T-amb+2.83) as, correspondingly, did ventilation. T-exh during flight increased with T-amb (T-exh=0.85 center dot T-amb+17.29). Respiratory water loss during flight (average REWLf=0.74 +/- 0.22 ml h(-1)) was significantly higher than at rest and increased with T-amb. Our measurements suggest that respiratory evaporation accounts for most water loss in flying Starlings and increases more than cutaneous evaporation with rising ambient temperature. (c) 2006 Elsevier Inc. All rights reserved.