EAS Annals Online Edition
ISSN 1784-357X
Annals 2006-2007
BIOLOGY AND LIFE SCIENCES
The supramolecular organization of Porphyra membranes and their participation
in the biosynthesis and secretion of cellulose microfibrils
Ioannes Tsekos, Hans-Dieter Reiss and Arete Dimopoulou, Institute of Botany, School of Biology,
Aristotle University of Thessaloniki, Macedonia, Greece
Abstract: The supramolecular organization of the membranes of the red algae Porphyra yezoensis and Porphyra leucosticta and their participation in the biosynthesis and secretion of cellulose microfibrils was studied in replicas of rapidly frozen and fractured cells. The ribbon-like cellulose fibrils of P. yezoensis and P. leucosticta are synthesized by terminal complexes (TCs) which are composed of repeating transverse rows formed of three or two particles, the TC subunits. About 11-25 in P. yezoensis, and 6-24 in P. leucosticta subunits constitute a TC. They are apparently more strongly interconnected in transverse than in longitudinal directions. Large globular particles (globules) seem to function as precursors units in the assembly and maturation of the TCs. The typical intramembranous particles observed in P. yezoensis and P. leucosticta are 9.2±0.2 nm in diameter, whereas those of a TC have an average diameter of 9.4±0.3 nm. During cell wall synthesis membranes of vesicles originating from the Golgi apparatus and which seem to fuse with the plasma membrane contain large globules, 15-21 nm in diameter. Polar differentiation of the plasma membrane in apical shoot cells of Porphyra, clearly manifested in the distribution and frequency of linear TCs, reflects tip growth (polar growth). Cellulose is synthesized and secreted at the poles (polar cell wall formation). Presence of lomasome-like bodies at the poles and formation of numerous TCs surrounding them reinforces the above view. The corss linked protein composite granule bands (GBs) seem ideally suited to resist the stresses in the cell wall due to turgor pressure. [Read More]
COMPUTER SCIENCES
Membrane Computing: A General View
Oscar H. Ibarra, Department of Computer Science, University of California, Santa Barbara, USA
Gheorge Paun, Institut of Mathematics of the Romanian Academy,Bucuresti, Romania
Abstract: We give an informal
presentation of the basic ideas, results, and applications
of membrane computing, a branch of natural computing
inspired by the structure and the functioning of biological
cells, cell tissues, or colonies of cells. Membrane
computing has given rise to computing models (called P
systems) that are distributed and parallel, which process
multisets of objects in compartments defined by membranes.
After introducing the main classes of P systems, illustrated
with some simple examples, we recall some results,
especially those that concern their computing power and
computing efficiency: the equivalence with Turing machines
for many classes of P systems, and the possibility of designing
devices which are capable of solving computationally
intractable problems in feasible time. We then briefly
discuss some applications (to biology, bio-medicine,
economics, etc.), giving a typical example to illustrate
this research direction. Finally, we report on some software
simulators and hardware implementations of P systems that
have been developed.
[Read More]
EARTH SCIENCES
An Integrated Ecosystem Theory
Sven Erik Jørgensen, Copenhagen University, Institute A,
Environmental Chemistry, Copenhagen, Denmark
Abstract: The paper presents an ecosystem theory based on ten propositions. The ecosystem theory is an integration of several contributions from a number of system ecologists. It is of importance to apply this theory to explain ecological observations and use it environmental management because the alternative is to rely entirely on observations which is very time consuming, costly and cumbersome. The presented integrated ecosystem theory is consistent with a recent published book A New Ecology, A System Approach, that is using some basic ecosystem properties to explain ecological observations.[Read More]
MATERIALS SCIENCES
On study of nonclassical problems of fracture and failure mechanics and related mechanisms
Alexander N. Guz, Institute of Mechanics, National Academy of Sciences of Ukranie, Kiev, Ukraine.
Abstract: Nonclassical problems of fracture and failure mechanics that have been analysed by the author and his collaborators at the SPTimoshenko Institute of Mechanics (Kiev, National Academy of Sciences of Ukraine) during the past thirty five years are considered in brief. Results of analysis are presented in form that would be quite informative for the majority of experts interested in various fundamental and applied aspects of the fracture and failure problems including the identification of the related mechanisms. This paper was prepared on invitation of the Editorial Board of the journal "Annals - The European Academy of Sciences" and may be considered as the Extended Pascal Medal Lecture (the 2007 Blaise Pascal Medal in Materials Sciences of the EAS).[Read More]
MATHEMATICS
Functional equation in the fundamental class of functions and the type of explicit formula
Muharem Avdispahic and Lejla Smajlovic, Department of mathematics,
University of Sarajevo, Sarajevo, Bosnia and Herzegovina
Abstract: The Jorgenson-Lang fundamental class of functions encompass most of zeta and L-functions of modern number theory. We highlight the role of conditions at zero and at infinity on test functions in the corresponding explicit formulas, depending on the form of a triple (Z,Z(tilde),Phi) belonging to this fundamental class. The advance in explicit formulas presented here consists in enlarging the class of test functions to which these formulas can be applied. [Read More]
PHYSICS
Basic Problem of the Calibration of Measuring Systems Intended for Dynamic Measurements
Edward Layer, Cracow University of Technology, Cracow, Poland.
Abstract: This paper deals with signals for the calibration of measuring systems which have at their input dynamic signals of unknown shape and unknown spectral distribution. It presents chosen solutions referring to the existence and attainability of signals maximizing the integral square error and the absolute value of error with one and two constraints imposed on them. These constraints refer to magnitude as well as to maximum rate of signal change. The last constraint is applied in order to match the dynamic properties of the signal to the dynamic properties of the calibrated system. [Read More]
Particle Physics and Medicine: a spin-off story
P. Lecoq, CERN, Geneva, Switzerland.
Abstract:
In-vivo molecular imaging is going to encounter a
spectacular development in the coming years as it will allow
to bridge post-genomics research activities with new
diagnostics and therapeutic strategies for major diseases.
In particular the molecular profiling of tumors and gene
expression can lead to tailored therapies and therapeutic
monitoring of major diseases like cancer, degenerative and
genetic diseases. Moreover the repeatability of non-invasive
approaches allows more precise evaluation of drug targeting
and pharmacokinetics studies on small animals, as well as
precise screening and treatment follow-up of patients.
At the same time the
impressive technological developments in several areas of
applied physics, in particular to answer the challenge of a
new generation of particle physics detectors and of the
development of an information based society open the way to
a major breakthrough in the performance of presently
available imaging tools. This paper will explain what are
the critical parameters of modern medical imaging and what
are the conditions for a significant breakthrough in
sensitivity, spatial resolution and multimodality capability
compared to presently available devices.
Special emphasis will be
put on the need for a globalization of technology research
and development as modern instrumentation in a vast range of
applications has similar requirements and spin-off should be
more and more understood as cross-fertilization between
different disciplines.[Read More]
SOCIAL AND HUMAN SCIENCES
Le cadastre des savoirs Figures de connaissances et prises de réel
Mapping knowledge: an epistemological challenge for human sciences
Claude Imbert, Ecole Normale Supérieure, Paris, France
Abstract:
The specificity of human sciences is argued from their own
epistemological point of view. After reminding of two
decisive epistemic decisions, which eliminated in the
fifties a first order empiricism (Merleau-Ponty and
Wittgenstein), the background is anthropological. Here is
the alternative to the culturalism and the relativism of
social constructivism.
Before any question of
truth, decision and action is settled, the contemporary
challenge is not the real as a metaphysical entity, but to
delineate an access to, and treatment of, what is real
according to some specific need, investigation, moment and
situation. Here as elsewhere, understanding does not
anticipate the production of the means of intelligibility.
Taking account of the XXth century, we focus on a process of
modernism in the making.
Human sciences are
patterned through path-breaking inquiries on typical cases
which require an extensive panel of knowledges.
Multidisciplinary case study is presently a most promising
framing. It offers an experimental place to observe a new
shaping of subjectivity. Human sciences are, by their very
nature, an essential nevertheless changing and metastable
production of consciousness. As such, it also affects at the
deepest level the map of scientific knowledge, as soon as
its cognitive, environmental and historical determinations
are not ignored. [Read More]
