Thermal Constant (thermal + constant)

Distribution by Scientific Domains

Selected Abstracts

Computational verification of anesthesia effect on temperature variations in rabbit eyes exposed to 2.45 GHz microwave energy

Akimasa Hirata
Abstract This paper computationally verifies the effect of anesthesia on temperature variations in the rabbit eye due to microwave energy. The main reason for this investigation is that our previous paper suggested a reduction in blood flow due to the administration of anesthesia, resulting in an overestimated temperature increase. However, no quantitative investigation has yet been conducted. The finite-difference time-domain (FDTD) method is used for calculating power absorption and temperature variation in rabbits. For this purpose, we used a computational rabbit phantom, which is comprised of 12 tissues (including 6 eye tissues) with a resolution of 1 mm. Thermal constants of the rabbit were derived by comparing measured and calculated temperatures. For intense microwave exposure to the rabbit eye, time courses of calculated and measured temperatures were in good agreement for cases both with and without the administration of anesthesia. The point to be stressed is that under anesthesia the thermoregulatory response was inactivated and blood flow and basal metabolism was reduced. Bioelectromagnetics 27:602,612, 2006. 2006 Wiley-Liss, Inc. [source]

Temperature-dependent development of the parasitoid Tachinaephagus zealandicus on five forensically important carrion fly species

The influences of temperature and host species on the development of the forensically important parasitoid Tachinaephagus zealandicus Ashmead (Hymenoptera: Encyrtidae) were studied at six constant temperatures in the range of 15,30C. T. zealandicus completed development successfully between 15C and 27C on five species of Calliphoridae, Calliphora albifrontalis Malloch, Calliphora dubia Macquart, Lucilia sericata Meigen, Chrysomya rufifacies Macquart and Chrysomya megacephala Fabricius. No adult parasitoids emerged from any of the host species reared at 30C. Temperature and host species significantly influenced development time, emergence success and progeny size. Development was significantly longer on Ch. megacephala and Ch. rufifacies at 18,24C and significantly longer on Ch. rufifacies and C. albifrontalis at 15C and 27C. Parasitoid emergence success was greatest at 21C, declined at the temperature extremes (15C and 27C) and was significantly lower on Ch. megacephala and Ch. rufifacies than on the three other host species. Progeny numbers per host pupa were highest at 21,24C, declined on either side of this temperature range and were significantly lower on L. sericata, Ch. rufifacies and Ch. megacephala than on either C. dubia or C. albifrontalis. An effect of host species on sex ratio was only observed at 27C, at which a higher proportion of T. zealandicus females emerged from Ch. megacephala and Ch. rufifacies than from the other host species. The thermal requirements for development (developmental thresholds, thermal constant, optimum temperature) of T. zealandicus in each host species were estimated using linear and non-linear models. Upper and lower developmental thresholds ranged between 29.90C and 31.73C, and 9.73C and 10.08C, respectively. The optimum temperature for development was estimated at between 25.81C and 27.05C. Given the significant effect of host species on development time, the use of parasitoid,host-specific developmental data in forensic application is recommended. [source]

Temperature-dependent development and distribution in the soil profile of pupae of greyback canegrub Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae) in Queensland sugarcane

David P Logan
Abstract, The temperature-dependent development rate of pupae of greyback canegrub, Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae), a major pest of sugarcane in central and northern Queensland, was determined under six constant temperature regimes: 18, 20, 23, 25, 27 and 30C, and for four geographically separated populations. Development rate increased significantly with increasing temperature. Parameters of the linear regression equation did not differ among populations and common coefficients were calculated. Developmental zero, at and below which no development occurs, for pupae was 12.0C and the thermal constant was 476 day-degrees (D). Minimum and maximum periods for pupal development were 26 days at 30C and 75 days at 18C, respectively. The phenology of pupae was determined in soil-filled cubicles in a shade house and in the field at Ayr (1935,S, 14725,E), north Queensland, using D. albohirtum field-collected as late-stage third-instar larvae and kept in containers. Pupation of D. albohirtum began in late August or early September and eclosion was complete by mid- to late October. The phenology data were used to validate the development model. Eclosion was predicted by summing hourly fractions of day-degrees until 476 D was reached and was close to actual eclosion. As temperature, and hence pupal development rate, varies with soil depth, the distribution of the third instars in pupal cells in the soil profile was determined in recently harvested fields of sugarcane in the Burdekin sugarcane district centred on Ayr. Numbers of late third instars in pupal cells peaked at 300,400 mm, with pupae found from 30 to 700 mm. Pupal development was simulated using hourly soil temperatures measured at depths of 200 and 400 mm at Ayr and at Sarina (2122,S, 14913,E). The pupal stage was predicted to take up to 2,10 days longer at 200 mm deep than at 400 mm depending on pupation site and date. When pupation was simulated in late August, as is likely in the field, pupal development at 400 mm deep took 48,56 days at Ayr and 58,62 days at Sarina. [source]

Development time and survival of Verrallina funerea (Theobald) (Diptera: Culicidae) immatures and other brackish water mosquito species in southeast Queensland, Australia

Jason A L Jeffery
Abstract,Verrallina funerea (Theobald) is a brackish water mosquito that is recognised as an important pest and vector in southeast Queensland, Australia. Immature development time and survival of Ve. funerea was defined in the laboratory in response to a range of temperatures (17,34C) and salinities (0,35 parts per thousand (p.p.t)). The expression of autogeny in this species was also assessed. Salinity only had a slight effect on mean development time from hatching to adult emergence (7.0,7.4 d at salinities of 0, 17.5 and 31.5 p.p.t) and survival was uniformly high (97.5,99.0%). Mean development times were shorter at 26, 29 and 32C (7.0, 6.8 and 6.8 d, respectively) and longest at 17C (12.2 d). The threshold temperature (t) was 5.8C and the thermal constant (K) was 142.9 degree-days above t. Survival to adulthood decreased from >95% (at 17,29C) to 78% (at 32C) and 0% (at 34C). No expression of autogeny was observed. Immature development times of Ve. funerea, Ochlerotatus vigilax (Skuse) and Oc. procax (Skuse) were then determined under field conditions at Maroochy Shire. Following tide and rain inundation, cohorts of newly hatched larvae were monitored daily by dipping, and time until pupation was noted. Tidal inundation triggered hatching of Ve. funerea and Oc. vigilax larvae whereas Oc. procax larvae were found only after rain inundation. Estimates of Ve. funerea and Oc. vigilax field development times were similar (8,9 d) while Oc. procax development time was slightly longer (9,10 d). Based on these survey results, control activities targeting Ve. funerea must be initiated 4 d (if using Bacillus thuringiensis var. israelensis de Barjac) or 5 d (if using s -methoprene) after inundation. However, Casuarina glauca Sieber canopy and branchlets covering breeding habitats may present a problem for the penetration of such treatments. [source]

Constant rate allocation in nymphal development in species of Hemiptera

Dionyssios CH.
Abstract., This study investigated the existence of rate isomorphy (the constant allocation of relative times to different stages of development under different abiotic conditions) in Macrolophus pygmaeus (Hemiptera: Miridae; a phytophagous and predatory insect). Replicated data were used from a range of temperatures regarding (i) the developmental period of each nymphal stage in relation to the total duration of nymph development, when feeding on three host plants either with different prey species or without prey, and (ii) its egg, total nymphal and preoviposition period, on two host plants, with different prey species. The proportion of time required for the development of each nymphal stage of M. pygmaeus is not different among the temperatures or the kind of food available. These proportions ranged among the different host plants, temperatures and prey presence/absence from 17.3,21.8% in the first, 14.5,18.8% in the second, 14.2,18.3% in the third, 16.5,21.0% in the fourth and from 25.4,30.6% in the fifth nymphal stage. Thus, temperature does not significantly affect the proportion of time spent in each nymphal stage and rate isomorphy exists in nymphal development. This phenomenon was also investigated using data from the literature, and it also occurs in several other Hemiptera species. Therefore, there appears to be a constant time allocation in the nymphal development of the higher taxonomic groups of insects. However, for M. pygmaeus, rate isomorphy does not hold when considering egg-to-egg development and the relative duration of times to egg hatch, total nymphal development and preoviposition period. The ecophysiological implications of this rate isomorphy phenomenon are discussed in relation to endocrinological mechanisms. Apart from its theoretical interest, the existence of rate isomorphy simplifies studies on the rate of development and the estimation of thermal constants of an insect, which are essential for the prediction of insect population dynamics. It is also proposed that the term ,rate isomorphy' does not strictly describe the phenomenon, and it is suggested that ,constant rate allocation' would be a more suitable term. [source]