A simple technique for estimating operative environmental temperature

• 1.1.|Operative environmental temperature (T_c) is commonly measured using a taxidermic mount consisting of a hollow copper cast of an animal's body covered by the animal's integument. We compare estimates of T_c made using such mounts with those derived from use of painted metal sphere thermometers, which are easier to construct and more rugged than taxidermic mounts.
• 2.2.|Comparison of data for 4 bird species indicates that metal spheres may be acceptable T_c-thermometers for analyses involving multiple measurements over moderately long time-scales (e.g. several hours).
• 3.3.|In this case, positive and negative differences between operative temperature estimated from use of taxidermic mounts and painted spheres tend to compensate and the average difference is usually less than 2°C. This difference is similar to that resulting from postural variation of taxidermic mounts or variation among individual mounts in identical postures.
• 4.4.|Sensitivity analysis indicates that use of painted spheres is unlikely to be an important source of error in estimates of total daily energy expenditure.
• 5.5.|In contrast, use of painted sphere thermometers in analyses involving fewer measurements over shorter-time scales can produce unacceptable discrepancies from values obtained from taxidermic mounts (i.e. up to 6.3°C).

     

Foraging rate of ants collecting honeydew or extrafloral nectar, and some possible constraints

ABSTRACT.

• 1 In a given ant species, the number of ants collecting honeydew in an aphid colony or extrafloral nectar on a plant is proportional to the productivity of the colony or plant. Thus, the number of ants per resource unit and the ingestion rate per ant are constant for a species.
• 2 Mean number of ants per resource unit and ingestion rate per ant differed considerably between the investigated species. The ingestion rate increases with the body size of the species and decreases with an increase of the mean number of ants per resource unit.
• 3 Ingestion rates were higher in ants foraging singly at the resource than in ants foraging in the normal way in a group.
• 4 It is suggested that the ingestion rate per ant is reduced below a maximum level by the number of ants present per resource unit because a certain number of ants is needed to defend the resource against alien ants. Small species need more individuals for this purpose than large species, and consequently suffer a larger reduction of their ingestion rate.

     

A simple technique for estimating deuterium incorporation levels in macromolecules.

A technique is described for estimating the levels of incorporation of deuterium into partially deuterated protein and RNA using NMR. The method provides accurate information about deuterium incorporation into nonexchangeable hydrogen positions for the macromolecular species in question.     

A rapid gravimetric method for estimating calcium carbonate in soils

Summary A simple gravimetric procedure is offered for determining carbonates in soil.     

A technique for estimating fine root production in the forest ecosystems

Summary The soil-block technique was developed to estimate fine root production in forest ecosystems. This technique produced estimates similar to conventional soil coring but required less labor and reduced disturbance to the soil-root environment.     

A simple method for estimating cytoplasmic diffusion coefficients

The diffusion coefficients of radioactively labelled substances in cytoplasm or other fluids are determined in vitro. The fluid containing the labelled substance is filled into a cylinder with one open end, through which the labelled substance diffuses out into a stirred outer medium. The diffusion coefficient is calculated by a one-dimensional diffusion equation from the rate of loss from the cylinder, and the length of the cylinder. The diffusion coefficients of tritiated water in several fluids have been determined. The results are in good agreement with those obtained by other methods.     

A fast and simple micromethod for estimating proteins

The assay is based on the property of proteins to form a complex with bromophenol blue. In alkaline solution this complex shows an intensive blue colour which is well measurable at 598 nm. The method is especially useful for small volumes (5-50 microliter) with a content of 5-30 micrograms of protein. By modification the test can be also used for the measurement of higher amounts of protein.     

A simple egg box planting technique for estimating the survival of eggs deposited in stream gravel

A simple technique for estimating the survival of eggs during their incubation in stream gravels by planting eggs in specially designed egg boxes is described. This technique ensures that all the live eggs and alevins present in the gravel at the time of sampling can be recovered. Survival can be calculated accurately from the ratio of the number of live recovered to the number of eggs originally planted and the errors caused by the loss of dead eggs and escape of live alevins from the sample area are avoided.     

A simple procedure for estimating the false discovery rate

MOTIVATION: The most used criterion in microarray data analysis is nowadays the false discovery rate (FDR). In the framework of estimating procedures based on the marginal distribution of the P-values without any assumption on gene expression changes, estimators of the FDR are necessarily conservatively biased. Indeed, only an upper bound estimate can be obtained for the key quantity pi0, which is the probability for a gene to be unmodified. In this paper, we propose a novel family of estimators for pi0 that allows the calculation of FDR. RESULTS: The very simple method for estimating pi0 called LBE (Location Based Estimator) is presented together with results on its variability. Simulation results indicate that the proposed estimator performs well in finite sample and has the best mean square error in most of the cases as compared with the procedures QVALUE, BUM and SPLOSH. The different procedures are then applied to real datasets. AVAILABILITY: The R function LBE is available at http://ifr69.vjf.inserm.fr/lbe CONTACT: broet@vjf.inserm.fr.     

Age-specific patterns in honeydew production and honeydew composition in the aphid Metopeurum fuscoviride: implications for ant-attendance

The intensity of the mutualistic relationship between aphids and ants depends mainly on the composition and amount of honeydew. We used the model system Tanacetum vulgare-Metopeurum fuscoviride to study age-related differences in honeydew production and composition and its effect on the mutualism between M. fuscoviride and the ant Lasius niger. First and second instar larvae of M. fuscoviride produced only half of the amount of honeydew as older larvae or adults. There were, however, no differences between age classes in the total honeydew sugar concentration, which averaged approx. 80 μg sugar/μl honeydew. Honeydew sugar composition also did not differ between age classes, and melezitose was the dominant sugar (59% in all classes). The amino acid concentration, by contrast, increased significantly with aphid age, reaching 22.6 nmol per μl honeydew in adult M. fuscoviride. This increase was mainly caused by asparagine and glutamine, while there were no differences in the concentrations of the five other regularly detected amino acids and cystine, respectively. The intensity of ant-attendance was significantly lower in colonies of first and second instar larvae than in colonies of older age classes. Ant-attendance correlated with the amount of honeydew produced, and not with the total amino acid concentration.