A Magnitude Effect in Temporal discounting with Hens

This study aimed to determine whether a magnitude effect could be obtained in temporal discounting with brown shaver hens. Subjects responded in a classic self-control situation for the choice between a smaller-sooner reward (1-s access to food, after a 2 s delay) or a larger-later reward (4.5-s access to food, after a 28 s delay). Hens responded in a multiple concurrent-chain procedure on concurrent variable-interval (VI-30s, VI 30-s) schedules in the choice phase (initial links), and a fixed interval (FI) schedule, ranging from FI 2-s to FI 28-s in the outcome phase (terminal links). The outcome phase then resulted in reinforcement of either 1-s access to grain or 4.5-s access to grain. The results replicated the findings of a previous study by Grace, Sargisson & White (2012), who obtained evidence of a magnitude effect in temporal discounting with pigeons, in which subjects demonstrated a greater preference for the larger reward compared to the small reward over increasing time delay. The findings indicate that the magnitude effect is not unique to humans, as previous studies have suggested. Data was applied the Generalized Matching Law (GML) and the Contextual Choice Model (CCM) equations to determine if the data was comparable with models of behavioural choice

Cloze probability in typed text: How predictability in cloze, copying and picture naming tasks affects response times

The cloze probability (CP) task is used to investigate the way in which sentences are processed. Participants’ task is to complete a sentence that is presented without the final word; however, sentences vary in levels of CP. High CP sentences have a highly anticipated completion word (e.g. Bradley prefers cats over dogs) whereas, low CP sentences can be completed with several different words, none of which are highly anticipated (e.g. In the distance they heard the kettle). These tasks have previously utilised spoken and hand-written forms of language production, but technological advances mean CP tasks need to be adapted to include typed language as a production modality. In the present study, sentences were presented online to be completed through typed text. Three tasks were included. A standard CP task in which participants completed sentences by freely producing the final word, a picture naming task where the final word of the sentence was presented in picture form, and a copying task. High CP sentences resulted in quicker reaction times of latency and duration compared to low CP sentences. Copying tasks gained the fastest responses, followed by picture naming and then cloze tasks. The effect of language processing, shown through CP tasks, remains present when utilising typed text as modality of language production. Copying task results suggested prediction may not be required in all language production. These results assist in relating CP tasks to modern methods of language production

Attractiveness of host banana leaf materials to the banana weevil, Cosmopolites sordidus in Ghana for development of field management strategies

The banana weevil, Cosmopolites sordidus, has been frequently cited as the most challenging constraint to banana and plantain production, particularly in small-scale (smallholder) farming. For the development of a new, low-cost weevil management technology based on attractive host plant material, we previously identified (2R,5S)-theaspirane as the active component of attractive senesced banana leaves. In this new study, we used behavioural (olfactometer) bioassays with adult weevils to compare the attractiveness of four different developmental stages of banana leaves, ie. unfolding (pale green), matured green (deep green), matured yellowing and senesced, to determine which leaf developmental stage would be most appropriate for use in weevil management. We also investigated the attractiveness of senesced leaf extracts prepared using different solvents to determine which solvent would be most appropriate for local production of leaf extracts. Coupled gas chromatography-electroantennography (GC-EAG) was then used with adult weevils to confirm the presence of (2R,5S)-theaspirane in attractive leaf extracts. Of the leaf materials tested, only the odour of senesced leaf material was significantly attractive to adult weevils (P<0.005). Furthermore, an extract of senesced material prepared using palm wine alcohol was significantly attractive (P<0.05). Using coupled GC-EAG with weevil antennae, (2R,5S)-theaspirane was identified as a minor component with strong EAG activity within the palm wine alcohol extract. The results suggest that palm wine alcohol extracts of senesced banana leaf material could be used to lure adult C. sordidus to traps in the field, as part of an ethnobotanical-based approach for C. sordidus management on smallholder farms

Hip contact forces in asymptomatic total hip replacement patients differ from normal healthy individuals: implications for preclinical testing

BACKGROUND Preclinical durability testing of hip replacement implants is standardised by ISO-14242-1 (2002) which is based on historical inverse dynamics analysis using data obtained from a small sample of normal healthy individuals. It has not been established whether loading cycles derived from normal healthy individuals are representative of loading cycles occurring in patients following total hip replacement. METHODS Hip joint kinematics and hip contact forces derived from multibody modelling of forces during normal walking were obtained for 15 asymptomatic total hip replacement patients and compared to 38 normal healthy individuals and to the ISO standard for pre-clinical testing. FINDINGS Hip kinematics in the total hip replacement patients were comparable to the ISO data and the hip contact force in the normal healthy group was also comparable to the ISO cycles. Hip contact forces derived from the asymptomatic total hip replacement patients were comparable for the first part of the stance period but exhibited 30% lower peak loads at toe-off. INTERPRETATION Although the ISO standard provides a representative kinematic cycle, the findings call into question whether the hip joint contact forces in the ISO standard are representative of those occurring in the joint following total hip replacement

Microorganisms from aphid honeydew attract and enhance the efficacy of natural enemies

Aphids are one of the most serious pests of crops worldwide, causing major yield and economic losses. To control aphids, natural enemies could be an option but their efficacy is sometimes limited by their dispersal in natural environment. Here we report the first isolation of a bacterium from the pea aphid Acyrthosiphon pisum honeydew, Staphylococcus sciuri, which acts as a kairomone enhancing the efficiency of aphid natural enemies. Our findings represent the first case of a host-associated bacterium driving prey location and ovipositional preference for the natural enemy. We show that this bacterium has a key role in tritrophic interactions because it is the direct source of volatiles used to locate prey. Some specific semiochemicals produced by S. sciuri were also identified as significant attractants and ovipositional stimulants. The use of this host-associated bacterium could certainly provide a novel approach to control aphids in field and greenhouse systems

Aphid and Plant Volatiles Induce Oviposition in an Aphidophagous Hoverfly

Episyrphus balteatus DeGeer (Diptera, Syrphidae) is an abundant and efficient aphid-specific predator. We tested the electroantennographic (EAG) response of this syrphid fly to the common aphid alarm pheromone, (E)-β-farnesene (EβF), and to several plant volatiles, including terpenoids (mono- and sesquiterpenes) and green leaf volatiles (C6 and C9 alcohols and aldehydes). Monoterpenes evoked significant EAG responses, whereas sesquiterpenes were inactive, except for the aphid alarm pheromone (EβF). The most pronounced antennal responses were elicited by six and nine carbon green leaf alcohols and aldehydes [i.e., (Z)-3-hexenol, (E)-2-hexenol, (E)-2-hexenal, and hexanal]. To investigate the behavioral activity of some of these EAG-active compounds, E. balteatus females were exposed to R-(+)-limonene (monoterpene), (Z)-3-hexenol (green leaf alcohol), and EβF (sesquiterpene, common aphid alarm pheromone). A single E. balteatus gravid female was exposed for 10 min to an aphid-free Vicia faba plant that was co-located with a semiochemical dispenser. Without additional semiochemical, hoverfly females were not attracted to this plant, and no oviposition was observed. The monoterpene R-(+)-limonene did not affect the females’ foraging behavior, whereas (Z)-3-hexenol and EβF increased the time of flight and acceptance of the host plant. Moreover, these two chemicals induced oviposition on aphid-free plants, suggesting that selection of the oviposition site by predatory hoverflies relies on the perception of a volatile blend composed of prey pheromone and typical plant green leaf volatiles

Desinfections-Anlagen und Desinfections-Apparate : für Stadt- und Landgemeinden, Krankenhäuser, Lazarethe u.s.w.

von W. Budenber

Role of honeydew in locating cereal aphids by their parasitoids

Imperial Users onl