The trigger system of the KLOE experiment Adinolfi, M; Ambrosino, F; Antonelli, M ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2002, Volume:
492, Issue:
1
Journal Article
Peer reviewed
Open access
We present the design of the trigger system for the KLOE experiment at the Frascati
φ-factory DAΦNE. The detector consists of a large-volume drift chamber and a calorimeter both immersed in a
0.52
T
...solenoidal field. The trigger, structured with a first- and a second-decision level, is based on the multiplicity of energy deposits in the calorimeter and of hits in the drift chamber. The selection criteria are described and the efficiency for detecting
φ decays is evaluated using data.
Colonies of leaf-cutting ants of the genus
Atta
need to collect large quantities of vegetal substrate in their environment to ensure their growth. They do so by building and extending over time a ...foraging network that consists of several underground tunnels extending above ground by physical trails. This paper presents a longitudinal study of the foraging network of two mature colonies of the grass-cutting ant
Atta capiguara
(Gonçalves) located in a pasture in central Brazil. Specifically, we investigated whether the extension of the foraging area of the colonies required to reach new resources occurs by building new and longer underground tunnels or by building new and longer physical trails. Each nest was surveyed at intervals of approximately 15 days during 1 year. At each survey we mapped the position of the tunnel entrances and foraging trails at which activity was observed. In addition, we assessed the excavation effort of the colonies since the last survey by the number and distance to the nest of new tunnel entrances, and the physical trail construction effort by the number and length of newly built physical trails. Our study reveals that in
A. capiguara
the collection of new resources around the nest required to ensure the continuous growth of the colonies is achieved mainly through the excavation of new underground tunnels, opening at greater distance from the nest, not through the building of longer aboveground physical trails.
► We have described the kinetic behavior of alcohol (ADH) and aldehyde (AldDH) dehydrogenases in solution and immobilized onto carbon platform via polyamidoamine (PAMAM) dendrimers. ► The influence ...of pH, K+, thiol and temperature was evaluated. ► The results showed that PAMAM dendrimers provide a good environment for the immobilization of dehydrogenase enzymes. ► The employed anchoring methodology (layer-by-layer) required very low catalyst consumption, and the anchored enzymes were quite stable over a period of approximately 30 days.
This paper describes the kinetic behavior of alcohol (ADH) and aldehyde (AldDH) dehydrogenases in solution and immobilized onto carbon platform via polyamidoamine (PAMAM) dendrimers. All the kinetic constants achieved for soluble ADH and AldDH are in agreement with literature data. The influence of pH and temperature was evaluated. Results showed that physiological conditions and ambient temperature can satisfactorily be applied to systems containing dehydrogenase enzymes, so as to ensure an environment where both ADH and AldDH display good activity. It is noteworthy that the affinity between both ADH and AldDH and their substrates and coenzyme is retained after the immobilization process. Investigation of the influence of the storage time demonstrated that there was no appreciable reduction in enzymatic activity for 50 days. Results showed that the PAMAM dendrimers provide a good environment for immobilization of dehydrogenase enzymes and that the affinity observed between the enzymes and their substrates and coenzymes seems to be retained, despite the considerable loss of enzymatic activity after immobilization. Furthermore, the anchoring methodology employed herein, namely layer-by-layer (LbL), required very low catalyst consumption.
Toxic baits are the most efficient method to control leaf-cutter ants in eucalyptus forests for paper and cellulose production. For the proper use of these baits, insecticide compounds must reach ...workers and contaminate them. Thus, understanding how these baits are processed inside the nests is vital for a successful control, especially when it comes to genus
Acromyrmex
. Lack of information on toxic baits and on contamination of
Acromyrmex
workers raises the question: do workers from subspecies
Acromyrmex subterraneus
(Forel) prepare leaves and toxic baits in similar ways for their fungus garden? To answer it, this study described and analyzed the behavioral repertoire executed by
A. subterraneus
workers during the preparation of leaf disks and baits and their incorporation into the fungus garden. Results show that the act of licking the substrate was the most frequently executed behavior, regardless of subspecies or size categories. Moreover, additional behaviors have been observed when workers processed the baits, such as licking and scraping their jaws on the surface of the bait pellet, as well as licking and biting fragments of bait pellets, moistening them. Thus, it is concluded that the preparation of baits is different from that of leaves; baits are more processed and can therefore contribute to contaminating workers via insecticides.
Leaf-cutter ants perform a series of specialized behaviors in preparing plant substrates for their symbiotic fungus. This process may be related to contamination of workers by substances such as ...insecticides, leading us to hypothesize that substances are spread among workers through behaviors they perform to grow the fungus. To test this hypothesis, we analyzed the behavioral acts of workers during the processing of the pellets by using a fat-soluble tracing dye, since the active ingredient that composes toxic baits, used for control of leaf-cutter ants, is fat-soluble. The frequencies of performed behaviors were recorded and the number of dyed workers was assessed after fungus cultivation. The most frequent behavior is allogrooming and corresponds to 45.87% of the contamination process in workers, followed by holding, licking, and cutting pellets, which account for 40.22% of the process. After pellet processing, the workers had their external and internal morphological structures marked by the tracing dye—93.75% and 79.25%, respectively. These results confirm that behaviors performed during fungus cultivation contribute to dispersing substances such as insecticides, causing the contamination of workers.
? Forager ants search for adequate food sources in nature and, after their discovery, decide whether the source is suitable or not for the colony. However, we asked “How do workers seek out the ...substrate for cultivation of the symbiontic fungus on which they feed? To answer this question, we evaluated the distance traveled by individual workers in the search of food and the distance traveled to return to the nest, as well as the time and velocity necessary for these activities. The results showed that the distance traveled by the leaf cutting ant, Atta sexdens rubropilosa (Linneus, 1758), in the search of food was greater than the distance traveled to return with the substrate to the colony. On the other hand, the mean time and velocity were similar for food search and return to the colony. These results support the hypothesis of information transfer, according to which the worker needs to return to the nest at the beginning of foraging to transfer information to other workers and thus to establish the process of worker ant foraging. It can be concluded that workers travel large distances in a random manner until finding their substrate, but the return to the nest is efficient considering the shorter distance traveled.
Our study seeks to discover contamination routes of leaf-cutting worker ants during chemical control by formicide baits. To do so, toxic baits containing fat-soluble tracer dye were provided to ...colonies of three subspecies of
Acromyrmex
under laboratory conditions, in order to assess the proportion of dyed workers by size category, as well as dyed internal morphological structures. Results showed that nearly 50% of the workers come into contact with the active ingredient, since the internal structures of their bodies are dyed by the fat-soluble tracer dye within the first 24 h from contact with the toxic bait. In addition, the three subspecies of leaf-cutting ants present a similarity as to the contamination of their workers, probably due to their specialized behavior performed during the growth of the fungus garden with the baits. We conclude that the workers’ pattern of behavior during fungus garden growth was the main means for dispersion of a fat-soluble substance among approximately half of the nest mates in our experiments, serving as a model for further studies on contamination of worker ants with insecticides.
Atta laevigata and Atta capiguara are two species of leaf-cutting ants that are found in the pastures of Central Brazil and build huge underground nests linked to the outdoor environment by ...underground tunnels, which can reach several tens of meters and further extend through foraging trails to distant foraging grounds. The tunnels built by mature colonies of A. capiguara are usually longer and deeper than those built by mature colonies of A. laevigata. The physical trails are also shorter on average. We hypothesized that these differences could be related to differences in thermotolerance between the two species. To test this we collected ants on foraging trails and placed them individually in waterproof test tubes plunged in a thermostatic bath at 25 °C (control), 37 and 39 °C (test temperatures). The results showed that at both 37 and 39 °C, the survival time of A. laevigata was much more extended than that of A. capiguara. A possible explanation for the longer and deeper underground foraging tunnels, as well as the shorter foraging trails, built by A. capiguara may thus be their lower resistance to heat stress. The longer tunnels built by A. capiguara colonies may reduce the exposure to heat of the foraging workers that commute between their nest and the foraging grounds or act as a thermal refuge in which the workers can find temporary protection against high outdoor temperatures.
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