Spring exaltation of the parasites population in sheep.

Η εργασία αυτή έγινε για να βρεθεί ο κατάλληλος χρόνος χορήγησης ανθελμινθικού φαρμάκου, για την οικονομικώτερη αντιμετώπιση των παρασιτώσεων. Για το σκοπό αυτό χρησιμοποιήθηκαν 31 πρόβατα ως πειραματόζωα, από το Νοέμβριο του 1983 μέχρι τον Απρίλιο του 1984. Στα ζώα αυτά γίνονταν κοπρανολογικές εξετάσεις και, αφού θανατώνονταν, εξεταζόταν ο γαστρεντερικός τους σωλήνας για ενήλικα παράσιτα και υποβιούσες προνύμφες. Από αυτά απομακρύνθηκαν από τη βοσκή, σταυλίστηκαν επί ένα 15θήμερο και θανατώθηκαν 4 τον Νοέμβριο, 3 τον Δεκέμβριο, 3 τον Ιανουάριο, 3 τον Φεβρουάριο και τα υπόλοιπα 18 σταυλίστηκαν περί την 10η Μαρτίου. Από τα 18 αυτά τα 4 θανατώθηκαν στα τέλη Μαρτίου, 5 τον Απρίλιο και ένα πέθανε. Τα υπόλοιπα 8 ξαναγύρισαν στη βοσκή μετά από θεραπεία. Κατόπιν αυτών εφόσον η ανοιξιάτικη έξαρση του αριθμού τνω αυγών, με τις επικρατούσες καιρικές συνθήκες, συνέβη τη 16η - 4 - 84, συμπεραίνεται ότι η επαναδραστηριοποίηση των προνυμφών που βρίσκονταν σε κατάσταση υποβίωσης συνέβη περί τα τέλη Μαρτίου. Επομένως ο καταλληλότερος χρόνος, για τη χορήγηση ανθελμινθικού φαρμάκου, θεωρείται ότι είναι του πρώτου 10ημέρου του Απριλίου. Ο μέσος όρος των υποθιουσών προνυμφών που βρέθηκαν εμφανίστηκε αυξανόμενος μέχρι τον Φεβρουάριο και ακολούθως κατέβηκε στο μηδέν το δεύτερο 15θήμερο του Απριλίου. Πιο συγκεκριμένα το ποσοστό των υποθιουσών προνυμφών σε σχέσει με τα ενήλικα παράσιτα ήταν τον Νοέμβριο περίπου 7,5%, τον Δεκέμβριο 13%, τον Ιανουάριο 19%, τον Φεβρουάριο 41%, τον Μάρτιο 3% και το πρώτο 15θήμερο του Απριλίου 1%. Ο μέσος όρος των αυγών ανα g κοπράνων παρέμεινε σταθερός μέχρι τα τέλη Μαρτίου και παρουσίασε μια μικρή έξαρση (3171 αυγά/g) το πρώτο 15θήμερο του Απριλίου. Η μεγαλύτερη έξαρση του αριθμού των αυγών ανά g κοπράνων εμφανίστηκε στις 16 Απριλίου (9573 αυγά/ g). Η έξαρση αυτή των αυγών ταυτίζεται με την ανοιξιάτικη έξαρση. Αυτό συμπεραίνεται, εκτός από την απότομη αύξηση των αυγών και από τη μερική ή ελάχιστη παρουσία υποθιουσών προνυμφών στα θανατωθέντα ζώα του Μαρτίου (28 - 3) και του Απριλίου (12-4) και από το μεγάλο αριθμό των αώρων μορφών (ο αριθμός αυτών ήταν πολύ περιορισμένος στα θανατωθέντα τους προηγούμενους μήνες) των παρασίτων που βρέθηκαν στα θανατωθέντα ζώα του Μαρτίου (πάνω από 50%) και του Απριλίου (περίπου 20 %), ενώ δεν υπήρχε η δυνατότητα της εκ νέου μόλυνσης των ζώων.No abstract (available)

Optical properties of wurtzite GaN/AlN quantum dots grown on non-polar planes: the effect of stacking faults in the reduction of the internal electric field

The optical emission of non-polar GaN/AlN quantum dots has been investigated. The presence of stacking faults inside these quantum dots is evidenced in the dependence of the photoluminescence with temperature and excitation power. A theoretical model for the electronic structure and optical properties of non-polar quantum dots, taking into account their realistic shapes, is presented which predicts a substantial reduction of the internal electric field but a persisting quantum confined Stark effect, comparable to that of polar GaN/AlN quantum dots. Modeling the effect of a 3 monolayer stacking fault inside the quantum dot, which acts as zinc-blende inclusion into the wurtzite matrix, results in an additional 30% reduction of the internal electric field and gives a better account of the observed optical features

Structure Differentiation of Hydrophilic Brass Nanoparticles Using a Polyol Toolbox

Nano-brasses are emerging as a new class of composition-dependent applicable materials. It remains a challenge to synthesize hydrophilic brass nanoparticles (NPs) and further exploit them for promising bio-applications. Based on red/ox potential of polyol and nitrate salts precursors, a series of hydrophilic brass formulations of different nanoarchitectures was prepared and characterized. Self-assembly synthesis was performed in the presence of triethylene glycol (TrEG) and nitrate precursors Cu(NO3)2·3H2O and Zn(NO3)2·6H2O in an autoclave system, at different temperatures, conventional or microwave-assisted heating, while a range of precursor ratios was investigated. NPs were thoroughly characterized via X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmition electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and ζ-potential to determine the crystal structure, composition, morphology, size, state of polyol coating, and aqueous colloidal stability. Distinct bimetallic α-brasses and γ-brasses, α-Cu40Zn25/γ-Cu11Zn24, α-Cu63Zn37, α-Cu47Zn10/γ-Cu19Zn24, and hierarchical core/shell structures, α-Cu59Zn30@(ZnO)11, Cu35Zn16@(ZnO)49, α-Cu37Zn18@(ZnO)45, Cu@Zinc oxalate, were produced by each synthetic protocol as stoichiometric, copper-rich, and/or zinc-rich nanomaterials. TEM sizes were estimated at 20–40 nm for pure bimetallic particles and at 45–70 nm for hierarchical core/shell structures. Crystallite sizes for the bimetallic nanocrystals were found ca. 30–45 nm, while in the case of the core-shell structures, smaller values around 15–20 nm were calculated for the ZnO shells. Oxidation and/or fragmentation of TrEG was unveiled and attributed to the different fabrication routes and formation mechanisms. All NPs were hydrophilic with 20–30% w/w of polyol coating, non-ionic colloidal stabilization (−5 mV < ζ-potential < −13 mV) and relatively small hydrodynamic sizes (<250 nm). The polyol toolbox proved effective in tailoring the structure and composition of hydrophilic brass NPs while keeping the crystallite and hydrodynamic sizes fixed

Probing exciton localization in non-polar GaN/AlN Quantum Dots by single dot optical spectroscopy

We present an optical spectroscopy study of non-polar GaN/AlN quantum dots by time-resolved photoluminescence and by microphotoluminescence. Isolated quantum dots exhibit sharp emission lines, with linewidths in the 0.5-2 meV range due to spectral diffusion. Such linewidths are narrow enough to probe the inelastic coupling of acoustic phonons to confined carriers as a function of temperature. This study indicates that the carriers are laterally localized on a scale that is much smaller than the quantum dot size. This conclusion is further confirmed by the analysis of the decay time of the luminescence

Influence of Stacking Sequences and Lattice Parameter Differences on the Microstructure of Nonpolar AlN Films Grown on (11(2)over-bar0) 6H-SiC by Plasma-Assisted Molecular Beam Epitaxy

International audienceThanks to close crystalline structures and low lattice mismatches, nonpolar (11 (2) over bar0) 6H-SiC is expected to be a well- adapted substrate for the growth of nonpolar (11 (2) over bar0) III-nitride films. We demonstrate that the local reproduction of the basal planes stacking induces the presence of numerous planar defects (1.3 x 10(6) cm(-1)) in AlN films deposited on (11 (2) over bar0) 6H-SiC. Moreover, the tensile strain of AlN along the [0001] direction results in the cracking of the film for a thickness as low as 100 nm. This fragile plastic relaxation is favored because the only slip systems available for ductile plastic relaxation are pyramidal systems involving a + c dislocations which have a high activation energy

Anisotropic morphology of nonpolar a-plane GaN quantum dots and quantum wells

International audienc

Resonantly Driven Coherent Oscillations In A Solid-State Quantum Emitter

Single-quantum emitters emit only one photon at a time, but the properties of the photon depend on how the emitter is excited. Incoherent excitation is simple and broadly used with solid-state emitters such as quantum dots, but does not allow direct manipulation of the quantum state. Coherent, resonant excitation on the other hand is used in pump-probe techniques to examine the quantum state of the emitter, but does not permit collection of the single-photon emission. Coherent control with simultaneous generation of photons has been an elusive goal in solid-state approaches, where, because of strong laser scattering at the detection wavelength, measurement of resonant emission has been limited to cross-polarized detection or Stokes-shift techniques. Here we demonstrate that a semiconductor quantum dot in a microcavity can be resonantly driven and its single-photon emission extracted background free. Under strong continuous-wave excitation, the dot undergoes several Rabi oscillations before emitting, which are visible as oscillations in the second-order correlation function. The quantum-dot states are therefore dressed, resulting in a Mollow-triplet emission spectrum. Such coherent control will be necessary for future high-efficiency sources of indistinguishable single photons, which can be used for quantum key distribution or through post-selection to generate entangled photon pairs. © 2009 Macmillan Publishers Limited. All rights reserved

Assessment of high school textbooks addressing radiations

Exposure to different types of radiation is an integral part of everyday life (e.g. cosmic radiation, radon, medical applications, cell phones, etc.). Therefore, the general public should adequately be informed on the issue from an early age in order to develop a realistic understanding of the associated risks and the necessary safety culture. In this respect, the quality of the related information provided in the school textbooks is of great importance. The present work demonstrates a quantified assessment of high school textbooks regarding the information on different radiation-related topics provided to students. The assessment was carried out based on an anonymous online survey with the participation of a total of 347 high school teachers. According to the results of the survey, the high school textbooks address radiation issues in a sparse, occasional, and fragmentary manner. Moreover, the results indicate that the quality of information they provide was judged as unsatisfactory in terms of scientific correctness, completeness, clarity-comprehensiveness and objectivity. Radiation protection and applications of non-ionizing radiation are the topics that are covered to a lesser extent in the textbooks and curricula evaluated