PRELIMINARY STUDIES ON SEDIMENT CORE FROM THE TYRO BASIN

Η παρούσα εργασία παρουσιάζει τα προκαταρκτικά αποτελέσματα της ορυκτολογικής και μικροπαλαιοντολογικής ανάλυσης που πραγματοποιήθηκε σε δείγματα ιζημάτων από τον πυρήνα TYR05 που συλλέχθηκε από την ανοξική και υπεράλμυρη λεκάνη Τύρου στην ανατολική Μεσόγειο. Ο πυρήνας αποτελεί μία σύνθετη λιθοστρωματογραφική ακολουθία που αποδίδεται στο ισχυρό γεωδυναμικό καθεστώς της περιοχής. Οι συγκεντρώσεις πλαγκτονικών τρηματοφόρων παρουσιάζουν διακυμάνσεις οι οποίες συμπίπτουν με αλλαγές στη λιθολογία του πυρήνα. Η ορυκτολογική σύσταση των ιζημάτων δείχνει επίδραση από τους εβαπορίτες που δημιουργούνται στον πυθμένα της λεκάνης. Τα ορυκτά συστατικά σε σχέση με τις συγκεντρώσεις της μικροπανίδας δείχνουν ότι τα ιζήματα περιλαμβάνουν σαπροπηλικά στρώματα. Χρειάζονται επιπλέον αναλύσεις για τον ασφαλή προσδιορισμό των σαπροπηλικών αποθέσεων.The present paper summarizes the preliminary results of the mineralogical and micropaleontological analysis conducted on sediment samples from core TYR05 retrieved from the anoxic and hypersaline Tyro basin in the eastern Mediterranean Sea. The core comprises a complex lithostratigraphic sequence attributed to the strong geodynamic regime of the area. The planktonic foraminifera associations present fluctuations which coincide with changes in the lithology of the core. The mineralogical composition of the sediments shows influence from the evaporites developed on the bottom of the basin. The mineral constituents in association to the microfauna assemblages suggest that the sediments include sapropelic layers. Further analyses are needed in order to determine safely the sapropelic deposits

Metabolomic analysis of salmonella enterica cells in vitro and in situ

In the present study a comparison of metabolomics, on laboratory medium, on rocket extract, of S. Tymphimurium (ST) CDC 6516-60, as well as on the developed biofilm on rocket tissue was investigated

Investigation of heaterless hollow cathode breakdown

The development of long life high powered (>50A) hollow cathodes is of importance to meet the demand of increasingly powerful Gridded Ion engines and Hall Effect thrusters. High power cathodes typically operate at greater temperature ranges, which poses a significant challenge to maintain heater reliability. The heater component commonly used to raise the insert to emissive temperatures, has inherent reliability issues from thermal fatigue caused by thermal cycling with large temperature variations. A self-heating hollow cathode allows for potentially higher reliability through design simplicity of removing the heater component, and in addition there can be savings in mass, volume, ignition time and power. This study characterizes the initiation of the start-up process for a heaterless hollow cathode. As such the study analyses conditions of the initiation as a function of detailed geometrical and physical parameters. The Paschen curve can be seen to give a qualitative explanation for the breakdown voltage variance. The quantitative variations between the empirical results and Paschen curve are discussed in relation to non-uniform pressure simulations

Standardisation of elemental analytical techniques applied to provenance studies of archaeological ceramics: an inter laboratory calibration study

Chemical analysis is a well-established procedure for the provenancing of archaeological ceramics. Various analytical techniques are routinely used and large amounts of data have been accumulated so far in data banks. However, in order to exchange results obtained by different laboratories, the respective analytical procedures need to be tested in terms of their inter-comparability. In this study, the schemes of analysis used in four laboratories that are involved in archaeological pottery studies on a routine basis were compared. The techniques investigated were neutron activation analysis (NAA), X-ray fluorescence analysis (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). For this comparison series of measurements on different geological standard reference materials (SRM) were carried out and the results were statistically evaluated. An attempt was also made towards the establishment of calibration factors between pairs of analytical setups in order to smooth the systematic differences among the results

One-loop effective action around de Sitter space

The non-local one-loop contribution to the gravitational effective action around de Sitter space is computed using the background field method with pure trace external gravitational fields and it is shown to vanish. The calculation is performed in a generic covariant gauge and the result is verified to be gauge invariant.Comment: 19 pages, uses phyzzx.tex inpu

Nonlinear optical studies of Oligomers dyades of polyphenylene using Open aperture z-scan technique

National audienc

Nonlinear optical studies of Oligomers Anisole dyades by Open-aperture z-scan technique

International audienc

Enhancement of linear and nonlinear optical properties of deoxyribonucleic acid-silica thin films doped with rhodamine

In this work, we present the linear and nonlinear optical properties of DNA as functional material, incorporated into a silica material matrix with rhodamine organic dye. We observed that even low concentration of DNA affects the aggregate behavior of the dyes in silica films. The samples with DNA showed higher transmittance and fluorescence efficiency. Moreover, the presence of DNA has been found to significantly enhance the nonlinear optical response of the systems. In this way, we prove that silica materials can provide suitable matrices for hybridization with functional molecules and can be utilized as active optical waveguide materials with enhanced nonlinear optical properties

Third-order nonlinear optical response of push-pull azobenzene polymers

The nonlinear optical response of a series of azo-containing side-chain polymers is investigated using Z-scan technique, employing 35 ps and 4 ns laser pulses, at 532 nm. The systems were found to exhibit strong nonlinear optical response, dominated by nonlinear refraction. In all cases, the nonlinear absorption and refraction have been determined and are compared with those of disperse red 1 considered as reference. The corresponding third-order susceptibilities chi((3)) were determined to be as large as 10 (7) and 10 (5) esu under ps and ns laser excitation, respectively. Finally, the results are discussed and compared with other reported data

Polaron Variational Methods In The Particle Representation Of Field Theory : II. Numerical Results For The Propagator

For the scalar Wick-Cutkosky model in the particle representation we perform a similar variational calculation for the 2-point function as was done by Feynman for the polaron problem. We employ a quadratic nonlocal trial action with a retardation function for which several ans\"atze are used. The variational parameters are determined by minimizing the variational function and in the most general case the nonlinear variational equations are solved numerically. We obtain the residue at the pole, study analytically and numerically the instability of the model at larger coupling constants and calculate the width of the dressed particle.Comment: 25 pages standard LaTeX, 9 uuencoded postscript figures embedded with psfig.st