Structure of transactinide nuclei with relativistic energy density functionals

A microscopic theoretical framework based on relativistic energy density functionals (REDFs) is applied to studies of shape evolution, excitation spectra, and decay properties of transactinide nuclei. Axially symmetric and triaxial relativistic Hartree-Bogoliubov (RHB) calculations, based on the functional DD-PC1 and with a separable pairing interaction, are performed for the even-even isotopic chains between Fm and Fl. The occurrence of a deformed shell gap at neutron number N=162 and its role on the stability of nuclei in the region around Z=108 is investigated. A quadrupole collective Hamiltonian, with parameters determined by self-consistent constrained triaxial RHB calculations, is used to examine low-energy spectra of No, Rf, Sg, Hs, and Ds with neutron number in the interval 158≤N≤170. In particular, we analyze the isotopic dependence of several observables that characterize the transitions between axially symmetric rotors, γ-soft rotors, and spherical vibrators. An interesting example of a possible occurrence of shape-phase transitions and critical-point phenomena in this mass region is explored

Relativistic Energy Density Functional Description of Shape Transition in Superheavy Nuclei

Relativistic energy density functionals (REDF) provide a complete and accurate, global description of nuclear structure phenomena. A modern semi-empirical functional, adjusted to the nuclear matter equation of state and to empirical masses of deformed nuclei, is applied to studies of shapes of superheavy nuclei. The theoretical framework is tested in a comparison of calculated masses, quadrupole deformations, and potential energy barriers to available data on actinide isotopes. Self-consistent mean-field calculations predict a variety of spherical, axial and triaxial shapes of long-lived superheavy nuclei, and their alpha-decay energies and half-lives are compared to data. A microscopic, REDF-based, quadrupole collective Hamiltonian model is used to study the effect of explicit treatment of collective correlations in the calculation of Q{\alpha} values and half-lives.Comment: 23 pages, 10 figure

Αξιολόγηση δυσφαγίας σε καρδιοχειρουργικούς ασθενείς στη ΜΕΘ

Τις τελευταίες δεκαετίες η εξέλιξη της ιατρικής επιστήμης και των μονάδων εντατικής θεραπείας (ΜΕΘ) έχει οδηγήσει στην αύξηση του προσδόκιμου επιβίωσης των ανθρώπων και στην βελτίωση της ποιότητας ζωής. Σύμφωνα όμως με μελέτες, οι ασθενείς που εισέρχονται στη ΜΕΘ, με την πάροδο του χρόνου, εμφανίζουν επιπλοκές που επιβαρύνουν την πρόγνωση τους. Σημαντική επιπλοκή που προκύπτει συνήθως είναι οι δυσφαγία ύστερα από παρατεταμένο χρόνο σε μηχανικό αερισμό. Η δυσφαγία είναι σοβαρή διαταραχή που οφείλεται σε μηχανική βλάβη και ατροφία των μυών του άνω αναπνευστικού-καταποτικού συστήματος. Όταν δεν έχει εντοπιστεί, είτε αντιμετωπιστεί κατάλληλα, μπορεί να προκαλέσει υποσιτισμό, κακή ενυδάτωση και σοβαρές αναπνευστικές λοιμώξεις. Η παρούσα μελέτη είχε σκοπό να διερευνήσει την ασφάλεια και εφαρμοσιμότητα ενός πρωτοκόλλου που στόχο είχε την αξιολόγηση δυσφαγίας σε ασθενείς μετά την καρδιοχειρουργική τους επέμβαση. Στην μελέτη εντάχθηκαν όσοι ήταν διασωληνωμένοι περισσότερο από 24 ώρες, ενώ αποκλείστηκαν άτομα με νευρολογικές διαταραχές, άτομα που είχαν υποβληθεί σε χειρουργεία που αφορούσαν την κεφαλή και τον τράχηλο, άτομα που είχαν υποβληθεί σε τραχειοστομία αλλά και όσοι είχαν προϋπάρχουσα δυσφαγία. Από τους 40 ασθενείς που ελέχθηκαν, μόνο οι 24 τελικώς μπόρεσαν να αξιολογηθούν. Οι υπόλοιποι 16 είτε δεν πληρούσαν τα κριτήρια εισαγωγής, είτε δεν κατάφεραν να αποσωληνωθούν λόγω θανάτου. Οι μελέτη μας είχε επίσης και αρκετούς περιορισμούς. Αρχικά, ένα μεγάλο μέρος του δείγματος αξιολογήθηκε μόνο 1 φορά και για αυτό δεν υπήρξε η παρακολούθηση των 7 ημερών όπως ήταν ο αρχικός στόχος. Επιπλέον το αρχικό πρωτόκολλο αξιολόγησης αποτελούταν από 3 βήματα και κατά την πορεία της έρευνας χρειάστηκε να το τροποποιήσουμε. Τελευταίος και πολύ σημαντικός περιορισμός της έρευνας ήταν ότι δεν υπήρχε δυνατότητα αξιολόγησης μέσω απεικονιστικών μεθόδων, όπως η εύκαμπτη ρινική βιντεοσκόπηση «FEES» και η βιντεοακτινοσκόπηση «VFSS», εξετάσεις που θα μπορούσαν να μας δώσουν σημαντικές πληροφορίες αλλά και να επηρεάσουν σημαντικά τα ευρήματά μας. Από τα αποτελέσματα της έρευνας παρατηρήσαμε ότι σε όλους σχεδόν τους ασθενείς μετά την αποσωλήνωσή τους υπήρχε μία ήπια οργανική βλάβη στον καταποτικό μηχανισμό. Ομοίως με άλλες έρευνες με καρδιοχειρουργικά δείγματα επιβεβαιώσαμε ότι ο παρατεταμένος χρόνος διασωλήνωσης σχετίζεται με την ύπαρξη δυσφαγίας. Επίσης στην αξιολόγηση χρησιμοποιήθηκε το 90ml « Timed Water Test», ένα τεστ που έχει χρησιμοποιηθεί και από άλλες έρευνες στο παρελθόν. Όπως αποδείχθηκε το «Timed Water Swallow Test» ήταν ασφαλές για το συγκεκριμένο εξεταζόμενο πληθυσμό. Δεν μπορούμε όμως να πούμε ότι μπορεί να χρησιμοποιηθεί από όλες τις κατηγορίες των ασθενών που εμφανίζουν δυσκολία στην κατάποση. Συμπερασματικά μπορούμε να πούμε ότι η αξιολόγηση της δυσφαγίας σε ασθενείς σε ΜΕΘ μετά από καρδιοχειρουργική επέμβαση είναι ασφαλής, εφικτή κι εφαρμόσιμη. Επίσης ο παρατεταμένος χρόνος διασωλήνωσης επηρεάζει τον καταποτικό μηχανισμό και συσχετίζεται με μεγαλύτερα ποσοστά δυσφαγίας ενώ τάση συσχέτισης εμφάνιζει και η διάρκεια αναισθησίας και καταστολής.In recent decades, the development of medical science and intensive care units (ICUs) has led to an increase in human survival and an improvement in the quality of life. However, according to studies, patients who enter the ICU, over time, develop complications that aggravate their prognosis. A major complication that usually occurs is dysphagia after prolonged time in mechanical ventilation. Dysphagia is a serious disorder due to mechanical damage and atrophy of the muscles of the upper respiratory tract. When it’s not detected or treated properly, it can cause malnutrition, poor hydration and severe respiratory infections. The aim of this study was to investigate the safety and feasibility of a protocol aimed at assessing dysphagia in patients after their cardiac surgery. The study included those who were intubated for more than 24 hours, while excluded people with neurological disorders, people who had undergone surgery on the head or neck, people who had undergone tracheostomy and pre-existing dysphagia. Of the 40 patients screened, only 24 were finally able to be evaluated. The remaining 16 either did not meet the admission criteria or excluded due to death. Like all surveys, ours was faced with limitations that may have affected the outcomes of the study. A large part of the sample was evaluated only once and therefore there was no follow-up of 7 days as was the original goal. In addition, the initial evaluation protocol consisted of 3 steps and during the course of the research we had to modify it. Last and very important limitation of the research was that there was no capability of evaluation through imaging methods such as fiberoptic endoscopic evaluation of swallowing «FEES» and videofluoroscopy «VFSS» that could give us important information and also significantly influence our findings. From the results of the research we noticed that in almost all patients after their extubation there was a mild organic damage to the swallowing mechanism. Similar to other studies with cardiac surgery samples, we confirmed that prolonged intubation time is associated with dysphagia. During assessment we also used the 90ml "Timed Water Swallow Test", a test that has been used by previous studies. We showed that the "Water Swallow Test" was safe for the target population. However, by the present study we cannot say that it can be used by all categories of patients who have swallowing disorder. In conclusion, we have shown that the evaluation of dysphagia in patients in ICU after cardiac surgery is safe, feasible and applicable. Also, the prolonged intubation time affects the swallowing mechanism and is associated with higher rates of dysphagia, while the duration of anesthesia and sedation is also correlated

Isospin Effects on Strangeness in Heavy-Ion Collisions

Kaon properties are studied within the framework of a fully covariant transport approach. The kaon-nucleon potential is evaluated in two schemes, a chiral perturbative approach and an effective One-Boson-Exchange model. Isospin effects are explicitly accounted for in both models. The transport calculations indicate a significant sensitivity of momentum distributions and total yields of $K^{0,+}$ isospin states on the choice of the kaon-nucleon interaction. Furthermore, isospin effects are rather moderate on absolute kaon yields, but appear on strangeness ratios. This is an important issue in determining the high density symmetry energy from studies of strangeness production in heavy-ion collisions.Comment: 15 papes, 5 figures. Accepted for publication in Nuclear Physic

Isospin Dynamics in Heavy Ion Collisions: from Coulomb Barrier to Quark Gluon Plasma

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this report we present a selection of new reaction observables in dissipative collisions particularly sensitive to the symmetry term of the nuclear Equation of State (Iso-EoS). We will first discuss the Isospin Equilibration Dynamics. At low energies this manifests via the recently observed Dynamical Dipole Radiation, due to a collective neutron-proton oscillation with the symmetry term acting as a restoring force. At higher beam energies Iso-EoS effects will be seen in Imbalance Ratio Measurements, in particular from the correlations with the total kinetic energy loss. For fragmentation reactions in central events we suggest to look at the coupling between isospin distillation and radial flow. In Neck Fragmentation reactions important $Iso-EoS$ information can be obtained from the correlation between isospin content and alignement. The high density symmetry term can be probed from isospin effects on heavy ion reactions at relativistic energies (few AGeV range). Rather isospin sensitive observables are proposed from nucleon/cluster emissions, collective flows and meson production. The possibility to shed light on the controversial neutron/proton effective mass splitting in asymmetric matter is also suggested. A large symmetry repulsion at high baryon density will also lead to an "earlier" hadron-deconfinement transition in n-rich matter. A suitable treatment of the isovector interaction in the partonic EoS appears very relevant.Comment: 18 pages, 12 figures, lecture at the 2008 Erice School on Nuclear Physics, to appear in Progress in Particle and Nuclear Physic

Constraining the Symmetry Energy: A Journey in the Isospin Physics from Coulomb Barrier to Deconfinement

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this work we present a selection of reaction observables in dissipative collisions particularly sensitive to the isovector part of the interaction, i.e. to the symmetry term of the nuclear Equation of State (EoS). At low energies the behavior of the symmetry energy around saturation influences dissipation and fragment production mechanisms. We will first discuss the recently observed Dynamical Dipole Radiation, due to a collective neutron-proton oscillation during the charge equilibration in fusion and deep-inelastic collisions. Important Iso-EOS effects are stressed. Reactions induced by unstable 132Sn beams appear to be very promising tools to test the sub-saturation Isovector EoS. New Isospin sensitive observables are also presented for deep-inelastic, fragmentation collisions and Isospin equilibration measurements (Imbalance Ratios). The high density symmetry term can be derived from isospin effects on heavy ion reactions at relativistic energies (few AGeV range), that can even allow a ``direct'' study of the covariant structure of the isovector interaction in the hadron medium. Rather sensitive observables are proposed from collective flows and from pion/kaon production. The possibility of the transition to a mixed hadron-quark phase, at high baryon and isospin density, is finally suggested. Some signatures could come from an expected ``neutron trapping'' effect. The importance of studying violent collisions with radioactive beams from low to relativistic energies is finally stressed.Comment: 15 pages, 5 figures, Int.Workshop on Nuclear Dynamics in Heavy Ion Reactions and Neutron Stars, Beijing Normal Univ. July 07, to appear in Int.Journ.Modern Physics E (2008

The Greek merchant fleet as a national navy during the war of independence 1800-1830

We analyse the emergence of the Greek merchant navy in the wider European context after the Treaty of Vienna, in particular that of the maritime islands - Hydra, Spetsai and Psara - during the end of the 18th to the beginning of the 19th century, when Greece was still a part of the Ottoman Empire. We examine the structure of the merchant fleet and the impetus it received after they could raise mainly the Russian flag as a flag of opportunity. We trace its history as blockade runners for France during the Napoleonic wars and the necessity to be armed in order to face the challenge of the Barbary corsairs (from Algiers, Tunis and Tripoli). These armed merchantmen and their crews, who had gained valuable experience during the Napoleonic Wars and by fighting against the Barbary corsairs, formed the nucleus of Greece’s navy during the War of Independence of 1821-1830. Combining superior naval skill and “terror weapons” as, for example, fireships, the Greek armed merchantmen achieved a number of astonishing victories against the Ottoman navy which was superior in numbers and tonnage (including dedicated ships of the line), thus contributing crucially to Greece’s independence