A New Metaheuristic Bat-Inspired Algorithm

Metaheuristic algorithms such as particle swarm optimization, firefly algorithm and harmony search are now becoming powerful methods for solving many tough optimization problems. In this paper, we propose a new metaheuristic method, the Bat Algorithm, based on the echolocation behaviour of bats. We also intend to combine the advantages of existing algorithms into the new bat algorithm. After a detailed formulation and explanation of its implementation, we will then compare the proposed algorithm with other existing algorithms, including genetic algorithms and particle swarm optimization. Simulations show that the proposed algorithm seems much superior to other algorithms, and further studies are also discussed.Comment: 10 pages, 2 figure

The use of sewage treatment works as foraging sites by insectivorous bats

Sewage treatment works with percolating filter beds are known to provide profitable foraging areas for insectivorous birds due to their association with high macroinvertebrate densities. Fly larvae developing on filter beds at sewage treatment works may similarly provide a valuable resource for foraging bats. Over the last two decades, however, there has been a decline in filter beds towards a system of “activated sludge”. Insects and bat activity were surveyed at 30 sites in Scotland employing these two different types of sewage treatment in order to assess the possible implications of these changes for foraging bats. Bat activity (number of passes) recorded from broad-band bat detectors was quantified at three points within each site. The biomass of aerial insects, sampled over the same period as the detector surveys, was measured using a suction trap. The biomass of insects and activity of Pipistrellus spp. was significantly higher at filter beds than at activated sludge sites. In addition, whilst foraging activity of Pipistrellus spp. at filter beds was comparable to that of adjacent “good” foraging habitat, foraging at activated sludge sites was considerably lower. This study indicates the high potential value of an anthropogenic process to foraging bats, particularly in a landscape where their insect prey has undergone a marked decline, and suggests that the current preference for activated sludge systems is likely to reduce the value of treatment works as foraging sites for bats

Evolutionary adaptation of muscle power output to environmental temperature: force-velocity characteristics of skinned fibres isolated from antarctic, temperate and tropical marine fish

1. Single fast fibres were isolated from the myotomal muscles of icefish (Chaenocephalus aceratus Lönnberg, Antarctica), North Sea Cod (Gadus morhua L.) and Pacific Blue Marlin (Makaira nigricans Wakiya, Hawaii). Fibres were chemically skinned with the non-ionic detergent Brij-58. 2. Maximum tensions (Po, kN m−2) developed at the characteristic body temperature of each species are 231 for icefish (−1°C), 187 for cod (8°C) and 156 for marlin (20°C). At 0°CPo is 7 times higher for fibres from the icefish than from the marlin. 3. Fibres from icefish and cod failed to relax completely following activations at temperatures above approximately 12°C. The resultant post-contraction force is associated with a proportional increase in stiffness, suggesting the formation of a population of Ca-insensitive cross bridges. 4. At 0°C there is little interspecific variation in unloaded contraction velocity (Vmax) among the three species.Vmax (muscle lengths s−1) at normal body temperatures are 0.9 for icefish (−1°C), 1.0 for cod (8°C) and 3.4 for marlin (20°C). 5. The force-velocity (P-V) relationship becomes progressively more curved with increasing temperature for all three species. 6. Maximum power output for the fast muscle fibres from the Antarctic species at −1°C is around 60% of that of the tropical fish at 20°C. Evolutionary temperature compensation of muscle power output appears largely to involve differences in the ability of cross bridges to generate force

Energy cost of contraction in fast and slow muscle fibres isolated from an elasmobranch and an Antarctic teleost fish

1. Single fast and small bundles of slow fibres were isolated from the muscles of an elasmobranch (dogfish, Scyliorhinus canicula) and an Antarctic teleost (Notothenia neglecta). A third fibre type present in the dogfish (superficial fibre) was also isolated. Fibres were chemically skinned with a non-ionic detergent. 2.2. Tension generation and ATPase activity were measured during isometric activations. ATPase activity was estimated by measuring the release of ADP into the experimental solutions using high performance liquid chromatography. 3.3. In the dogfish fibre types, both tension and ATPase activity increased in the order superficial < slow < fast, even after corrections were made for differences in myofibrillar density. The economy of isometric contraction (tension/ATPase activity) was 50–60% higher in the slow and superficial fibres than in the fast. 4.4. In the Antarctic species, both tension and ATPase activity of the fast fibres were higher than those of the slow fibres, and the slow fibres were 30% more economical than fast fibres. After correction for differences in myofibrillar density, tensions were very similar. 5.5. The results are discussed with reference to the energy supply, recruitment pattern and function of the various fibre types

Evolutionary adaptation to temperature in fish muscle cross bridge mechanisms: tension and ATP turnover

1. Force and ATPase activity were measured in skinned, fast muscle fibres isolated from the myotomes of Antarctic, temperate and tropical fish. 2. Maximum isometric tension was inversely related to normal environmental temperature, when measured at −5 to 0°C. When compared within the normal temperature range of each species, tensions were rather similar. 3. In contrast, the muscle fibres of all three species had similar cross bridge cycle times over the entire temperature range studied. This results in a more economical maintenance of force at normal body temperatures in muscle fibres from the Antarctic fish

Slow muscle power output of yellow- and silver-phase European eels (Anguilla anguilla L.) : changes in muscle performance prior to migration

Eels swim in the anguilliform mode in which the majority of the body axis undulates to generate thrust. For this reason, muscle function has been hypothesised to be relatively uniform along the body axis relative to some other teleosts in which the caudal fin is the main site of thrust production. The European eel (Anguilla anguilla L.) has a complex life cycle involving a lengthy spawning migration. Prior to migration, there is a metamorphosis from a yellow (non-migratory) to a silver (migratory) life-history phase. The work loop technique was used to determine slow muscle power outputs in yellow- and silver-phase eels. Differences in muscle properties and power outputs were apparent between yellow- and silver-phase eels. The mass-specific power output of silver-phase slow muscle was greater than that of yellow-phase slow muscle. Maximum slow muscle power outputs under approximated in vivo conditions were 0.24Wkg-1 in yellow-phase eel and 0.74Wkg-1 in silver-phase eel. Power output peaked at cycle frequencies of 0.3-0.5Hz in yellow-phase slow muscle and at 0.5-0.8Hz in silver-phase slow muscle. The time from stimulus offset to 90␛elaxation was significantly greater in yellow- than in silver-phase eels. The time from stimulus onset to peak force was not significantly different between life-history stages or axial locations. Yellow-phase eels shifted to intermittent bursts of higher-frequency tailbeats at a lower swimming speed than silver-phase eels. This may indicate recruitment of fast muscle at low speeds in yellow-phase eels to compensate for a relatively lower slow muscle power output and operating frequency

Fast muscle function in the European eel (Anguilla anguilla, L.) : during aquatic and terrestrial locomotion

Eels are capable of locomotion both in water and on land using undulations of the body axis. Axial undulations are powered by the lateral musculature. Differences in kinematics and the underlying patterns of fast muscle activation are apparent between locomotion in these two environments. The change in isometric fast muscle properties with axial location was less marked than in most other species. Time from stimulus to peak force (T(a)) did not change significantly with axial position and was 82 /-6 ms at 0.45BL and 93 /-3 ms at 0.75BL, where BL is total body length. Time from stimulus to 90 elaxation (T(90)) changed significantly with axial location, increasing from 203 /-11ms at 0.45BL to 239 /-9 ms at 0.75BL. Fast muscle power outputs were measured using the work loop technique. Maximum power outputs at /-5 train using optimal stimuli were 17.3 /-1.3W kg(-1) in muscle from 0.45BL and 16.3 /-1.5W kg(-1) in muscle from 0.75BL. Power output peaked at a cycle frequency of 2Hz. The stimulus patterns associated with swimming generated greater force and power than those associated with terrestrial crawling. This decrease in muscle performance in eels may occur because on land the eel is constrained to a particular kinematic pattern in order to produce thrust against an underlying substratum