An ecological study of Phaenocora unipunctata (Örsted) (Turbellaria; Rhabdocoela): predator-prey interrelationships

The diet of P. unipunctata living in an English pond was investigated by examination of the gut contents of field-collected specimens, by a serological method and by laboratory experiments. Tubificids, and to a lesser extent lumbriculids, are the preferred food of small and large flatworms. In the laboratory damaged Cladocera and Chironomidae were fed upon to a very limited extent and in the serological tests a few flatworms gave a positive reaction with anti-Cladocera and anti-Chironomidae sera, but it is unlikely that these taxa are preyed upon extensively in the field. Communal feeding occurs. Algae and Protozoa are not eaten. P. unipunctata has no competitors for the oligochaete resource in the pond.Predators of the flatworm were determined mainly by laboratory experiments. Only the larvae and adults of Dytiscus attacked a few specimens. It is unlikely that flatworm and its cocoons have any serious predators in the pond.     

A New Nonparametric Approach to the Comparison of K Independent Samples of Response Curves

Two simultaneous distribution free test procedures to test the homogeneity of K samples of response curves measured at T points of time each are proposed which react upon the shape of the response curve. One procedure is based on the comparison of K T-tupels of FRIEDMAN-rank sums, the other on the comparison of K T × T-incidence tables, which first were introduced by KANNEMANN (1976). The application of the two procedures is illustrated by a numerical example. In the discussion the tests are compared with each other and with concurring tests.     

Designs for restricted exploration in mixture experiments

Extreme Vertices designs were developed by MCLEAN and ANDERSON (1966) for situations where components of a mixture are restricted by lower and upper bounds, SNEE and MARQUARDT (1974) and SNEE (1975) gave algorithms to construct optimum designs in these situations. SAXENA and NIGAM (1975) evolved a transformation which provides designs for restricted exploration using Symmetric Simplex designs. In this paper a procedure has been given which provides alternative designs with uniform exploration in constrained mixture experiments. The procedure is illustrated by an example.     

Crystallization and preliminary crystallographic study of human lithostathine

Crystals of human lithostathine, a pancreatic glycoprotein which inhibits the growth and nucleation of calcium carbonate crystals, were grown using PEG 4000 as the precipitating agent. The crystals belong to the hexagonal space group P6₁ (or its enantiomorph P6₅) and diffract to 1.55 Å resolution. There is one molecule in the asymmetric unit and the crystals have 39% solvent. © 1995 Wiley-Liss, Inc.     

Resource allocation and compensation during development in holometabolous insects

We provide an extensive review on current knowledge and future research paths on the topic of resource allocation and compensation during development in holometabolous insects, emphasizing the role of resource management during development, and how compensatory mechanisms may be acting to remediate nutritional deficiencies carried over from earlier stages of development. We first review resource allocation in “open” and “closed” developmental stages and then move on to the topic of modelling resource allocation and its trade-offs. In doing so, we review novel methodological developments such as response-surface methods and mixture experiments as well as nutritional geometry. We also dwell on the fascinating topic of compensatory physiology and behavior. We finish by discussing future research paths, among them the emerging field of nutrigenomics and gut microbiome, which will shed light into the yet poorly understood role of the symbiotic microbiota in nutrient compensation or assimilation.     

Sequential Exploration in Mixture Experiments

In this paper sequential exploration of response surfaces for mixture experiments has been studied. The plan and the estimation and testing procedures for some of the well known models have been given.     

Improved resolution in triple-resonance spectra by nonlinear sampling in the constant-time domain

Summary Nonlinear sampling along the constant-time dimension is applied to the constant-time HNCO spectrum of the dimerization domain of Ga14. Nonlinear sampling was used for the nitrogen dimension, while the carbon and proton dimensions were sampled linearly. A conventional ct-HNCO spectrum is compared with a nonlinearly sampled spectrum, where the gain in experiment time obtained from nonlinear sampling is used to increase the resolution in the carbonyl dimension. Nonlinearly sampled data are processed by maximum entropy reconstruction. It is shown that the nonlinearly sampled spectrum has a higher resolution, although it was recorded in less time. The constant intensity of the signal in the constant-time dimension allows for a variety of sampling schedules. A schedule of randomly distributed sampling points yields the best results. This general method can be used to significantly increase the quality of heteronuclear constant-time spectra.     

How can an agri-environmental scheme be designed for farmland bird protection,and what does it mean for the CAP 2023–2027?

Biodiversity loss is recognized as a major global threat. The European Commission has addressed this issue with vigour in its current strategy papers. Farmland birds, such as the lapwing (Vanellus vanellus), whose population has been rapidly declining in Germany, have been particularly affected. To date, the European Union has tried to tackle the problem of biodiversity loss mainly with voluntary agri-environmental schemes (AESs), which are financed by the European Agricultural Fund for Rural Development (EAFRD). However, only a small fraction of agricultural land is enrolled in such programs. We identify the possible drivers and inhibitors of farmers’ acceptance of a potential AES that, if introduced, could contribute to lapwing conservation. Our analysis is based on a discrete choice experiment conducted with 252 arable farmers in Germany. The results suggest that scheme attributes tied with EAFRD compliance, i.e., a minimum participation period of five years and the nature of the relevant sanctions regime, reduce farmers’ potential acceptance of the proposed AES. Furthermore, farmers and farm characteristics have an influence on preferences for specific AES attributes. Finally, this article outlines how the identified weaknesses of AES may be addressed in the new “Green Architecture” of the Common Agricultural Policy 2023–2027.     

The implication of survival rates in natural populations of Drosophila: capture-recapture experiments on domestic species

Adult survival rates were estimated in field populations of domestic Drosophila species by means of multiple capture-recapture experiments. Micronized fluorescent dusts were used as marking agents and analysis used the Fisher-Ford model: the assumptions of this model are justified using evidence from this study and the literature. Survival rates were commonly 0.45-0.85 per day, suggesting that mean life expectancy for adult flies is from 1.3 to 6.2 days in natural populations. No consistent differences in survival between sexes or seasons were demonstrated. The implications of low natural survival rates are discussed.