Leaf functional traits of four evergreen species growing in Mediterranean environmental conditions

In this study, physiological and biochemical responses of native and introduced evergreens to the Mediterranean region, co-occurring under ambient conditions, are presented. Carbon and nitrogen compounds have been investigated in fully expanded leaves of the Mediterranean evergreens Laurus nobilis and Nerium oleander and introduced to the Mediterranean region Asian evergreens Ligustrum japonicum and Pittosporum tobira in May (end of the growing season), July (middle of the drought season), October (beginning of the wet season), and January (middle of the cold season). The above-mentioned species are subjected to seasonal fluctuations of climatic stimuli, in the eastern Mediterranean region. During the most vigorous vegetative growth in spring, the species maintained elevated chlorophyll, soluble sugar, and starch content, at rising water potential and CO2 assimilation. Leaf proline content increased during unfavourable drought conditions, concomitantly with reduced leaf osmotic potential; in addition, declining water availability, during the dry season, had a significant impact on leaf water potential and turgor. Total lipid and nitrogen content increased during the wet and cold seasons. In general, lipid content was higher in mature leaves of the Mediterranean evergreens (L. nobilis and N. oleander) throughout the year, in comparison with that of the introduced evergreens (L. japonicum and P. tobira), while fatty acid composition seems to be species specific. Although differences in leaf attributes have been investigated between native and introduced species in the Mediterranean region, fully expanded leaves of the studied species did not appear to respond differently to the seasonality of the Mediterranean ecosystem. © 2016, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków

Leaf surface wettability and fatty acid composition of Arbutus unedo and Arbutus andrachne grown under ambient conditions in a natural macchia

Features of the adaxial and abaxial surface microstructure of Arbutus unedo L. and Arbutus andrachne L. are evaluated as possible consistent parameters contributing to the wetness of leaves. The abaxial leaf surface of A. andrachne and A. unedo was determined to be more hydrophobic than the adaxial leaf surface. Hydrophobicity may be of particular importance for the ecophysiological status of the hypostomatic leaves of both Arbutus species, which exhibit a long lifespan and are exposed to various environmental stimuli. Water repellence may also be correlated to the increased presence of surface wax. Lipid analysis of the leaves of both plant species revealed an abundance of α-linolenic acid, with palmitic acid as the second major contributor, followed by linoleic and oleic acid. Oleic and linoleic acid were present in slightly larger percentages in A. andrachne compared with A. unedo, whereas myristic, palmitic and α-linolenic acids were found in elevated percentages in A. unedo. The fatty acid composition analysis of the leaf wax of A. andrachne and A. unedo ranged from C16 to C26, with fatty acids of an even longer chain length detected in the case of A. andrachne. Despite the similar fatty acid composition of total lipids, the composition of the wax fraction showed differences between the two Arbutus species, which may partly contribute to the foliar surface properties of the two species. © 2015 Société botanique de France

Learning object farms and learning design in science education

A Learning Object (LO) is a collection of digital pieces representing a minimal, independent and standalone educational unit. By combining XML and MathML technologies, together with the computing power of server based Computer Algebra Systems (CAS), it is possible to design new web-based information services where teachers and learners in parallel on the fly might easily design, produce/reproduce, explore and terminate various classes of digital LOs. Such an approach offers through Web large-scale production and harvesting of classes of graphical LOs, i.e. Learning Object Farms (LOF), that are adapted and dedicated to various training and learning scenarios targeting mathematics, statistics and natural science education. LOF offer homogenous and easy to use mechanisms for interactive heterogeneous mathematical, statistical and natural science presentations to be displayed through digital blackboards or a PC that is interconnected to a projector. Standard mathematical and scientific notation is obtained in both static and dynamical text based XHTML presentations, and in graphical presentations exploring Scalable Vector Graphics (SVG). A LOF might easily be included into LCMS

Abstract The Discrete Logarithm Problem as an Optimization Task: A First Study

Most of the contemporary cryptographic systems are based on mathematical problems whose solutions are generally intractable in polynomial time; such problems are the discrete logarithm problem and the integer factorization problem. In this contribution we consider the discrete logarithm problem as an Integer Programming Problem. Two Evolutionary Computation methods, namely the Particle Swarm Optimization and the Differential Evolution algorithm, as well as the Random Search technique, are employed as a first approach to tackle this new Integer Programming Problem. Results indicate that this new approach is promising.

Seasonal functional partitioning of carbohydrates and proline among plant parts of the sand daffodil

The sand daffodil (Pancratium maritimum) is a perennial geophyte, widely distributed and grown in a wild stage along the Mediterranean seashores. The aboveground tissues of this geophyte are exposed to harsh, ambient conditions and its large inflorescences of remarkable beauty and fragrance expand during the drought season and carry particular ornamental worth. The ecophysiological principles underlining metabolic processes of this geophyte are poorly understood. The seasonal variation of soluble sugars, starch, and proline was investigated in individuals collected from patches of P. maritimum, therefore, monthly measurements were performed in bulbs, leaves, scapes, and petals during a year. It was found that (a) sugar content showed similar seasonal trends between bulbs and leaves, as well as between petals and scapes, (b) bulbs contained enhanced starch concentrations irrespective of season, (c) proline accumulation exhibited substantial seasonal fluctuations among the considered tissues and pronounced differences were detected between maxima in petals and leaves. A substantial increase in both sugar and proline content was evident in petals during the drought season. In leaves, the accumulation of proline and, to a lesser extent, sugars was negatively correlated to the precipitation of the Mediterranean study site. It seems likely that the astonishing flowering of P. maritimum is supported by large leaf and bulb reserves. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)