The number of catenoids connecting two coaxial circles in Lorentz-Minkowski space

In 3-dimensional Lorentz-Minkowski space we determine the number of catenoids connecting two coaxial circles in parallel planes. This study is separated according to the types of circles and the causal character (spacelike and timelike) of the catenoid.Comment: 16 pages, 3 figure

A note on the von Bertalanffy growth function concerning the allocation of surplus energy to reproduction

We propose an extended form of the von Bertalanffy growth function (VBGF), where the allocation of surplus energy to reproduction is considered. Any function can be used in our model to describe the ratio of energy allocation for reproduction to that for somatic growth. As an example, two models for energy allocation were derived: a step-function and a logistic function. The extended model can jointly describe growth in adult and juvenile stages. The change in growth rate between the two stages can be either gradual or steep; the latter gives a biphasic VBGF. The results of curve fitting indicated that a consideration of reproductive energy is meaningful for model extension. By controlling parameter values, our comprehensive model gives various growth curve shapes ranging from indeterminate to determinate growth. An increase in the number of parameters is unavoidable in practical applications of this new model. Additional information on reproduction will improve the reliability of model estimates

Viability of Hawaiian Forest Tree Seeds in Storage at Various Temperatures and Relative Humidities

Volume: 5Start Page: 36End Page: 4

Mamey (Mammea americana L.) in Martinique Island : un patrimonio para ser valorizados

Introduction. Mamey (Mammea americana L., Clusiaceae) was present in Martini-que before the Spanish colonization. Its distribution area includes tropical America and the Carib-bean. A significant phenotypical diversity is observed on the island, with fruits of very uneven quality as well as various agronomic, pomological and biochemical characteristics. The aim of our work was to localize, identify and characterize trees considered of superior quality. Materials and methods. A survey carried out between April and September 2005 allowed the selection of 10 trees renowned by the people as bearing high-quality fruits. These fruits present a small number of seeds and nonadhesive pulp, and develop a sweet taste as well as a strong flavor. During the year 2006, pomological description and biochemical analysis (total soluble solids and total titrable acidity) were carried out on the fruits. Results and discussion. The biometric and biochemical characteristics measured were generally better than those cited in the literature. Some accessions stand out and present great assets for their promotion for the fresh market as well as for processing. Moreover, some tendencies emerged from the variability observed for a few characters: thus, the variability of the biochemical characteristics measured within one accession, as well as between accessions originating from the same land, is low. It is null for the seed adhesion to the pulp for fruits belonging to the same accession. Conclusion and perspectives. Our work is one of the first relating to identification and characterization of phenotypical diversity of the M. americana L. species, especially in Martinique Island. Our results are likely to pro-mote the development of a diversification network. Some highlighted trends suggest new research to be able to distinguish the role of the environmental versus genetic components in the performance of the phenotypes observed