The Measurements of Calcification Rates in Reef Corals Using Radioisotope 45Ca at Pongok Sea, South Bangka

Coral reef ecosystem is one of the most important ecological systems in the Indonesian coastal zone. The aim of this study which was undertaken between August - October 2006, is to measure the calcification of corals in a reef coral in the Pongok Sea, South Bangka using 45Ca. The steps in conducting this study were surveying of the site, preparation, transplanting, incubation in the 45Ca - solution, and analysis of the coral fragments. The results showed that at the depth of 5 m different counts per minute (cpm) trend occurred. For the samples taken from the transplantation of the Artificial Colony (Ac) the cpm showed that with the progress of time the cpm declined, reaching its lowest cpm at 5 hours after retransplanting of the coral fragments. On the other hand the samples obtained from the natural (Nc) colony showed that the cpm increased with time progress. At the 10 m depth where only the coral fragment of the natural colony (Nc) was observed a different pattern showed up. Here with the progress of time up to 3 hours the cpm increased and after that it declined to reach a low cpm at 5 hours of observation. The cpm values were then transformed to disintegrations per minute (dpm), μCi and at the end to 45Ca content. The same trend is shown for dpm, μCi/0.5 g sample and μg Ca/0.5 g sample. The 45Ca content (μg/0.5g sample) were used to show the calcification rates of coral fragments. It showed clearly that 45Ca could be used to calculate the magnitude of calcification. Received: 08 December 2009; Revised: 05 April 2011; Accepted: 05 April 201

The Measurements of Calcification Rates in Reef Corals Using Radioisotope 45Ca at Pongok Sea, South Bangka

Coral reef ecosystem is one of the most important ecological systems in the Indonesian coastal zone. The aim of this study which was undertaken between August - October 2006, is to measure the calcification of corals in a reef coral in the Pongok Sea, South Bangka using 45Ca. The steps in conducting this study were surveying of the site, preparation, transplanting, incubation in the 45Ca - solution, and analysis of the coral fragments. The results showed that at the depth of 5 m different counts per minute (cpm) trend occurred. For the samples taken from the transplantation of the Artificial Colony (Ac) the cpm showed that with the progress of time the cpm declined, reaching its lowest cpm at 5 hours after retransplanting of the coral fragments. On the other hand the samples obtained from the natural (Nc) colony showed that the cpm increased with time progress. At the 10 m depth where only the coral fragment of the natural colony (Nc) was observed a different pattern showed up. Here with the progress of time up to 3 hours the cpm increased and after that it declined to reach a low cpm at 5 hours of observation. The cpm values were then transformed to disintegrations per minute (dpm), μCi and at the end to 45Ca content. The same trend is shown for dpm, μCi/0.5 g sample and μg Ca/0.5 g sample. The 45Ca content (μg/0.5g sample) were used to show the calcification rates of coral fragments. It showed clearly that 45Ca could be used to calculate the magnitude of calcification. Received: 08 December 2009; Revised: 05 April 2011; Accepted: 05 April 201

On the Stereochemistry of the Cations in the Doping Block of Superconducting Copper-Oxides

Metal-oxygen complexes containing Cu,- Tl-, Hg-, Bi- and Pb-cations are electronically active in superconducting copper-oxides by stabilizing single phases with enhanced $T_c$, whereas other metal-oxygen complexes deteriorate copper-oxide superconductivity. Cu, Tl, Hg, Bi, Pb in their actual oxidation states are closed shell $d^{10}$ or inert $s^2$ pair ions. Their electronic configurations have a strong tendency to polarize the oxygen environment. The closed shell $d$ ions with low lying $nd^{10}\leftrightarrow nd^9(n+1)s$ excitations form linear complexes through $d_{z^2}-s$ hybridization polarizing the apical oxygens. Comparatively low $nd^9(n+1)s$ excitation energies distinguish $\rm Cu^{1+,3+}, Tl^{3+}, Hg^{2+}$ from other closed shell $d^{10}$ ions deteriorating copper-oxide superconductivity, {\it e.g.} $\rm Zn^{2+}$.Comment: 5 pages, uses REVTEX. To be published in: J. Superconductivity, Proc. Int. Workshop on "Phase Separation, Electronic Inhomogenities and Related Mechanisms for High T_c Superconductors", Erice (Sicily) 9-15 July 199

Current Distribution and random matrix ensembles for an integrable asymmetric fragmentation process

We calculate the time-evolution of a discrete-time fragmentation process in which clusters of particles break up and reassemble and move stochastically with size-dependent rates. In the continuous-time limit the process turns into the totally asymmetric simple exclusion process (only pieces of size 1 break off a given cluster). We express the exact solution of master equation for the process in terms of a determinant which can be derived using the Bethe ansatz. From this determinant we compute the distribution of the current across an arbitrary bond which after appropriate scaling is given by the distribution of the largest eigenvalue of the Gaussian unitary ensemble of random matrices. This result confirms universality of the scaling form of the current distribution in the KPZ universality class and suggests that there is a link between integrable particle systems and random matrix ensembles.Comment: 11 page

Binary reaction decays from 24Mg+12C

Charged particle and gamma decays in 24Mg* are investigated for excitation energies where quasimolecular resonances appear in 12C+12C collisions. Various theoretical predictions for the occurence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured 24Mg* excitation energy region. The inverse kinematics reaction 24Mg+12C is studied at E_lab(24Mg) = 130 MeV, an energy which enables the population of 24Mg states decaying into 12C+12C resonant break-up states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated gamma decays studied. Coincident events associated with inelastic and alpha-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body Q-values. The analysis of the binary reaction channels is presented with a particular emphasis on 24Mg-gamma, 20Ne-gamma and 16O-gamma coincidences. New information (spin and branching ratios) is deduced on high-energy states in 24Mg and 16O, respectively.Comment: 27 pages, 8 figures, 1 tabl

Clusters in Light Nuclei

A great deal of research work has been undertaken in the alpha-clustering study since the pioneering discovery, half a century ago, of 12C+12C molecular resonances. Our knowledge of the field of the physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. In this work, the occurence of "exotic" shapes in light N=Z alpha-like nuclei is investigated. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Results on clustering aspects are also discussed for light neutron-rich Oxygen isotopes.Comment: 12 pages, 5 figures. Invited Talk presented by C. Beck at the Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape" XLV in the series of Zakopane Schools of Physics - International Symposium - Zakopane, Poland, August 30 - September 5, 2010.To be publihed in Acta Physica Polonica B42 no 3, March 201

Reaction mechanisms in 24Mg+12C and 32S+24Mg

The occurence of "exotic" shapes in light N=Z alpha-like nuclei is investigated for 24Mg+12C and 32S+24Mg. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures with low spin are presented. For both reactions, exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility of Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated $\gamma$-decays studied. The analysis of the binary and ternary reaction channels is discussed.Comment: 7 pages, 4 figures, Paper presented at the Fusion08 International Conference on New Aspects of Heavy Ion Collisions Near the Coulomb Barrier, Chicago. Proceedings to be published by AIP Conference Proceedings Illinois, USA, September 22-26, 200

The Structure of Operators in Effective Particle-Conserving Models

For many-particle systems defined on lattices we investigate the global structure of effective Hamiltonians and observables obtained by means of a suitable basis transformation. We study transformations which lead to effective Hamiltonians conserving the number of excitations. The same transformation must be used to obtain effective observables. The analysis of the structure shows that effective operators give rise to a simple and intuitive perspective on the initial problem. The systematic calculation of n-particle irreducible quantities becomes possible constituting a significant progress. Details how to implement the approach perturbatively for a large class of systems are presented.Comment: 12 pages, 1 figure, accepted by J. Phys. A: Math. Ge

The spin-1/2 XXZ Heisenberg chain, the quantum algebra U_q[sl(2)], and duality transformations for minimal models

The finite-size scaling spectra of the spin-1/2 XXZ Heisenberg chain with toroidal boundary conditions and an even number of sites provide a projection mechanism yielding the spectra of models with a central charge c<1 including the unitary and non-unitary minimal series. Taking into account the half-integer angular momentum sectors - which correspond to chains with an odd number of sites - in many cases leads to new spinor operators appearing in the projected systems. These new sectors in the XXZ chain correspond to a new type of frustration lines in the projected minimal models. The corresponding new boundary conditions in the Hamiltonian limit are investigated for the Ising model and the 3-state Potts model and are shown to be related to duality transformations which are an additional symmetry at their self-dual critical point. By different ways of projecting systems we find models with the same central charge sharing the same operator content and modular invariant partition function which however differ in the distribution of operators into sectors and hence in the physical meaning of the operators involved. Related to the projection mechanism in the continuum there are remarkable symmetry properties of the finite XXZ chain. The observed degeneracies in the energy and momentum spectra are shown to be the consequence of intertwining relations involving U_q[sl(2)] quantum algebra transformations.Comment: This is a preprint version (37 pages, LaTeX) of an article published back in 1993. It has been made available here because there has been recent interest in conformal twisted boundary conditions. The "duality-twisted" boundary conditions discussed in this paper are particular examples of such boundary conditions for quantum spin chains, so there might be some renewed interest in these result