The effects of temperature on the growth, survival and biomass of different families of juvenile Penaeus japonicus Bate

Variation in the growth, survival and change in total biomass (termed biomass increase) of different families of juvenile Penaeus japonicus was investigated over a range of temperatures in controlled laboratory experiments. In the first experiment, the effects of temperature on six families of juveniles were examined over a broad range of temperatures (24 to 30 degreesC). In the second experiment, the effects of temperature on six more families of juveniles were examined over a narrower range of temperatures (27.5 to 31.2 degreesC). Over the broad temperature range, mean growth and biomass increase were highest at 27 degreesC and mean survival was highest at 24 degreesC. Mean growth was lowest at 24 degreesC, whilst survival and biomass increase were lowest at 30 degreesC. However, there was a significant interaction between family and temperature, with some families tolerating a broader range of temperatures than others. As a result, the ranking of families in relation to growth, survival and biomass increase changed at each temperature. This effect was more pronounced for survival than for growth. Over the narrower range, temperature significantly affected growth, survival and biomass increase, but there was no significant interaction between family and temperature. Growth, survival and biomass increase were significantly lower at 31.2 than at 27.5 and 29.2 degreesC. These results suggest that if grow-out conditions for P. japonicus vary by more than a few degrees, interactions between family and temperature could affect the efficiency of selection. The results also suggest that the family x temperature interaction may have a more pronounced effect on survival than on growth. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.

Temperature dependence of polaronic transport through single molecules and quantum dots

Motivated by recent experiments on electric transport through single molecules and quantum dots, we investigate a model for transport that allows for significant coupling between the electrons and a boson mode isolated on the molecule or dot. We focus our attention on the temperature-dependent properties of the transport. In the Holstein picture for polaronic transport in molecular crystals the temperature dependence of the conductivity exhibits a crossover from coherent (band) to incoherent (hopping) transport. Here, the temperature dependence of the differential conductance on resonance does not show such a crossover, but is mostly determined by the lifetime of the resonant level on the molecule or dot.

Interaction of temperature and vegetative flush maturity influences shoot structure and development of lychee (Litchi chinensis Sonn.)

Potted lychee trees (cv. Tai so) of varying vegetative flush maturity were grown under a range of temperature regimes and monitored for subsequent shoot structure and development. A combination of low temperature (15/17 or 18/13 degreesC day/night) and high vegetative flush maturity was necessary for floral initiation to occur, Exposure to high temperatures (28/23 degreesC) invariably resulted in the production of vegetative shoots, irrespective of flush maturity. Strong floral initiation was marked by the emergence of terminal particles and accompanying axillary particles. A decrea,;e in vegetative flush maturity or increase in temperature (e.g. 23/18 degreesC) resulted in a decrease in axillary shoot formation and the production of several intermediate shoot structures. These included leafy particles, stunted particles, partially emerged buds and non-emergent swollen buds, often produced on the same tree. At 23/18 degreesC, closer synchronisation of initial flush maturity was required for the production of a consistent shoot-type. Trees with synchronised mature flushes (I-2) at 23/18 degreesC resulted in the production of swollen terminal buds. Healthy trees were maintained in this state for at least 11 months. These results indicate that both temperature and flush maturity can influence subsequent shoot structure of lychee. In the absence of either a strong floral temperature (18/13 degreesC) or strong vegetative temperature (28/23 degreesC), slight differences in initial flush maturity have gteater impact on the type of emerging shoot formed. (C) 2002 Elsevier Science B.V. All rights reserved.

Development and survival of the diamondback moth (Lepidoptera : Plutellidae) at constant and alternating temperatures

Survival and development time from egg to adult emergence of the diamondback moth, Plutella xylostella (L.), were determined at 19 constant and 14 alternating temperature regimes from 4 to 40degreesC. Plutella xylostella developed successfully front egg to adult emergence at constant temperatures from 8 to 32degreesC. At temperatures from 4 to 6degreesC or from 34 to 40degreesC, partial or complete development of individual stages or instars was possible, with third and fourth instars having the widest temperature limits. The insect developed successfully from egg to adult emergence under alternating regimes including temperatures as low as 4degreesC or as high as 38degreesC. The degree-day model, the logistic equation, and the Wang model were used to describe the relationships between temperature and development rate at both constant and alternating temperatures. The degree-day model described the relationships well from 10 to 30degreesC. The logistic equation and the Wang model fit the data well at temperatures 32degreesC. Under alternating regimes, all three models gave good simulations of development in the mid-temperature range, but only the logistic equation gave close simulations in the low temperature range, and none gave close or consistent simulations in the high temperature range. The distribution of development time was described satisfactorily by a Weibull function. These rate and time distribution functions provide tools for simulating population development of P. xylostella over a wide range of temperature conditions.

Dopant extraction from scanning capacitance microscopy measurements of p-n junctions using combined inverse modeling and forward simulation

This article proposes a more accurate approach to dopant extraction using combined inverse modeling and forward simulation of scanning capacitance microscopy (SCM) measurements on p-n junctions. The approach takes into account the essential physics of minority carrier response to the SCM probe tip in the presence of lateral electric fields due to a p-n junction. The effects of oxide fixed charge and interface state densities in the grown oxide layer on the p-n junction samples were considered in the proposed method. The extracted metallurgical and electrical junctions were compared to the apparent electrical junction obtained from SCM measurements. (C) 2002 American Institute of Physics.

Vibration instability in rolling mills: Modeling and experimental results

Models for the occurrence of the vibrational instability during rolling known as third octave chatter are presented and discussed. An analysis of rolling mill chatter was performed for the purpose of identifying characteristics of the vibrations and to determine any dependency on the rolling schedule. In particular, a stability criterion for the critical rolling speed is used to predict the maximum rolling speed without chatter instability on schedules from a 5 stand tandem mill rolling thin steel product. The results correlate well with measurements of critical speed occurring on the mill using a vibration monitor: This research provides significant insights into the chatter phenomena and has been used to investigate control methods for suppression of the instability.

Structural and surface property changes of macadamia nut-shell char upon activation and high temperature treatment

Structural and surface property changes of macadamia nut-shell (MNS) char upon activation and high temperature treatment (HTT) were studied by high-resolution nitrogen adsorption, diffuse reflectance infra-red Fourier transform spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed desorption. It is found that activation of MNS char can be divided into the low extent activation which may involve the reactions of internal oxygen-containing groups and leads to the formation of comparatively uniform micropores, and the high extent activation which induces reactions between carbon and activating gas and produces a large amount of micropores. The surface functional groups (SFGs) basically increase with the increase of activation extent, but high extent activation preferentially increases the amount of -C-O and -C=O. HTT in air for a short tithe at a high temperature (1173 K) greatly increases the micropore volume and the amounts of SFGs. By appropriately choosing the activation and HTT conditions, it is possible to control both the textural structure and the type and amounts of SFG. (C) 2002 Published by Elsevier Science Ltd.

Ultra-high-temperature (UHT) treatment of milk: comparison of direct and indirect modes of heating

UHT processing of milk and its subsequent storage causes several changes which affect the shelf-life of UHT milk although it remains 'commercially sterile'. These changes include whey protein denaturation, protein-protein interaction, lactose-protein interaction, isomerisation of lactose, Maillard browning, sulphydryl compound formation, formation of a range of carbonyl and other flavoursome compounds, and formation of insoluble substances. They ultimately reduce the quality and limit the shelf life of UHT milk through development of off-flavours, fat separation, age gelation and sedimentation. The extent of these changes depends on many factors, a major one being the type of UHT heating. This review compares the effect heating milk by direct and indirect modes on various aspects of processing and quality of UHT milk.

Finite difference time domain (FDTD) method for modeling the effect of switched gradients on the human body in MRI

Numerical modeling of the eddy currents induced in the human body by the pulsed field gradients in MRI presents a difficult computational problem. It requires an efficient and accurate computational method for high spatial resolution analyses with a relatively low input frequency. In this article, a new technique is described which allows the finite difference time domain (FDTD) method to be efficiently applied over a very large frequency range, including low frequencies. This is not the case in conventional FDTD-based methods. A method of implementing streamline gradients in FDTD is presented, as well as comparative analyses which show that the correct source injection in the FDTD simulation plays a crucial rule in obtaining accurate solutions. In particular, making use of the derivative of the input source waveform is shown to provide distinct benefits in accuracy over direct source injection. In the method, no alterations to the properties of either the source or the transmission media are required. The method is essentially frequency independent and the source injection method has been verified against examples with analytical solutions. Results are presented showing the spatial distribution of gradient-induced electric fields and eddy currents in a complete body model.

Modeling of phase equilibrium and vapor adsorption on carbon black based on a combination of a lattice theory and equation of state

A thermodynamic approach is developed in this paper to describe the behavior of a subcritical fluid in the neighborhood of vapor-liquid interface and close to a graphite surface. The fluid is modeled as a system of parallel molecular layers. The Helmholtz free energy of the fluid is expressed as the sum of the intrinsic Helmholtz free energies of separate layers and the potential energy of their mutual interactions calculated by the 10-4 potential. This Helmholtz free energy is described by an equation of state (such as the Bender or Peng-Robinson equation), which allows us a convenient means to obtain the intrinsic Helmholtz free energy of each molecular layer as a function of its two-dimensional density. All molecular layers of the bulk fluid are in mechanical equilibrium corresponding to the minimum of the total potential energy. In the case of adsorption the external potential exerted by the graphite layers is added to the free energy. The state of the interface zone between the liquid and the vapor phases or the state of the adsorbed phase is determined by the minimum of the grand potential. In the case of phase equilibrium the approach leads to the distribution of density and pressure over the transition zone. The interrelation between the collision diameter and the potential well depth was determined by the surface tension. It was shown that the distance between neighboring molecular layers substantially changes in the vapor-liquid transition zone and in the adsorbed phase with loading. The approach is considered in this paper for the case of adsorption of argon and nitrogen on carbon black. In both cases an excellent agreement with the experimental data was achieved without additional assumptions and fitting parameters, except for the fluid-solid potential well depth. The approach has far-reaching consequences and can be readily extended to the model of adsorption in slit pores of carbonaceous materials and to the analysis of multicomponent adsorption systems. (C) 2002 Elsevier Science (USA).

Enhancement or modulation of the vector competence of ochlerotatus vigilax (Diptera : Culicidae) for Ross River virus by temperature

Two different doses of Ross River virus (1111) were fed to Ochlerotatus vigilax (Skuse), the primary coastal vector in Australia; and blood engorged females were held at different temperatures up to 35 d. After ingesting 10(4.3) CCID50/Mosquito, mosquitoes reared at 18 and 25degreesC (and held at the same temperature) had higher body remnant and head and salivary gland titers than those held at 32degreesC, although infection rates were comparable. At 18, 25, and 32degreesC, respectively, virus was first detected in the salivary glands on days 3, 2, and 3. Based on a previously demonstrated 98.7% concordance between salivary gland infection and transmission, the extrinsic incubation periods were estimated as 5, 4, and 3 d, respectively, for these three temperatures. When Oc. vigilax reared at 18, 25, or 32degreesC were fed a lower dosage of 10(3.3) CCID50 RR/mosquito, and assayed after 7 d extrinsic incubation at these (or combinations of these) temperatures, infection rates and titers were similar. However, by 14 d, infection rates and titers of those reared and held at 18 and 32degreesC were significantly higher and lower, respectively. However, this process was reversible when the moderate 25degreesC was involved, and intermediate infection rates and titers resulted. These data indicate that for the strains of RR and Oc. vigilax used, rearing temperature is unimportant to vector competence in the field, and that ambient temperature variations will modulate or enhance detectable infection rates only after 7 d: extrinsic incubation. Because of the short duration of extrinsic incubation, however, this will do little to influence RR epidemiology, because by this time some Oc. vigilax could be seeking their third blood meal, the latter two being infectious.