Relativistic O(q4)O(q^4) two-pion exchange nucleon-nucleon potential: configuration space

We have recently performed a relativistic $O(q^4)$ chiral expansion of the two-pion exchange $NN$ potential, and here we explore its configuration space content. Interactions are determined by three families of diagrams, two of which involve just $g_A$ and $f_{\pi}$, whereas the third one depends on empirical coefficients fixed by subthreshold $\pi N$ data. In this sense, the calculation has no adjusted parameters and gives rise to predictions, which are tested against phenomenological potentials. The dynamical structure of the eight leading non-relativistic components of the interaction is investigated and, in most cases, found to be clearly dominated by a well defined class of diagrams. In particular, the central isovector and spin-orbit, spin-spin, and tensor isoscalar terms are almost completely fixed by just $g_A$ and $f_{\pi}$. The convergence of the chiral series in powers of the ratio (pion mass/nucleon mass) is studied as a function of the internucleon distance and, for $r>$ 1 fm, found to be adequate for most components of the potential. An important exception is the dominant central isoscalar term, where the convergence is evident only for $r>$ 2.5 fm. Finally, we compare the spatial behavior of the functions that enter the relativistic and heavy baryon formulations of the interaction and find that, in the region of physical interest, they differ by about 5%.Comment: 27 pages, 33 figure

Entropic Entanglement Criteria for Continuous Variables

We derive several entanglement criteria for bipartite continuous variable quantum systems based on the Shannon entropy. These criteria are more sensitive than those involving only second-order moments, and are equivalent to well-known variance product tests in the case of Gaussian states. Furthermore, they involve only a pair of quadrature measurements, and will thus should prove extremely useful the experimental identification of entanglement.Comment: 4 pages, 2 figure

Study on unsteady cavitating flow simulation around marine propeller using a RANS CFD code.

The authors have been investigating the possibility of the application of CFD to the propeller performance evaluation and optimization. In these previous papers [1,2], the authors presented CFD simulation of non-cavitating and cavitating flow around a marine propeller using a commercial CFD code. A good agreement with the experiment was confirmed for the non-cavitating flow. Various validations were also carried out for the cavitating flow, and the followings were revealed. First, we confirmed that the cavity shape in a uniform flow was qualitatively well estimated, but the difference between two propellers, of which the blade sections were somewhat different, were not reproduced. Secondary, the cavity pattern in the non-uniform flow was also qualitatively well estimated, but the resulting pressure fluctuation was not validated. In this paper, the systematic experiment was carried out using two propellers, whose dimensions were very similar, to study the above issues, and simulation was carried out for the same cases. In the uniform cavitating flow simulation, the discrepancy of cavity shape around two propellers, whose dimension were very similar, was reproduced, and the quantitative validation of the fluid force such as thrust was done. In the non-uniform cavitating flow simulation, the comparison of the cavity pattern with the experiment and the quantitative validation of the fluctuating pressure on the wall of the cavitation tunnel were done.http://deepblue.lib.umich.edu/bitstream/2027.42/84265/1/CAV2009-final68.pd

Dynamic of microbial community during distinct stages of organic matter decomposition in sediments from mangroves of São Paulo state.

Abstract: Mangroves are ecosystems located at coastline areas in tropical and subtropical conditions that are under tide influences. They are recognized as productive regions and have a high export of organic matter (OM) for the adjacent coastal waters. Bacterial communities present in these environments perform primordial functions on the cycling of nutrients and thereby on maintaining your important processes. Therefore, the purpose of this study was to assess the dynamics and phylogenetic diversity of the bacterial community in threes of São Paulo mangroves, during different stages of decomposition plant material. At the same time, the intention was to correlate this event with the emission of greenhouse gases (GHG). Microcosms were constructed with leaf discs of Avicennia schaueriana (A), Laguncularia racemosa (L), Rhizophora mangle (R) were arranged on sediment and water, which were collected from the following Mangroves: Bertioga with contamination (BC), Bertioga (B) and Cananeia (C). These microenvironments were stored at 24 °C and monitored for 60 days. The measurements of gases and DNA extraction were performed at the 7, 15, 30 and 60 days. The collected air samples were analyzed in triplicate in chromatograph model GC-2014 greenhouse gas. The obtained DNA was subjected to PCR reactions aiming the sequencing in large scale of the gene that encoding the ribosomal rRNA Domain Bacteria by Ion Torrent. The assessment of communities dynamics was made with Qiime. Regarding CO2 emissions, the values observed for AB7, RB7 and RBC7 were higher than the other treatments. For N2O the samples AB, ABC7 and RBC7 showed the higher rates. The CH4 gas obtained a homogeneous result for all samples, seeing no significant difference. The bacterial community dynamics showed that treatments: Bertioga, Avicennia schaueriana and decomposition time 60 days, presented a higher clustering within their samples, according to the standard of similarity observed in them

The π−\pi-Gluon Exchange Interaction Between Constituent Quarks

The interaction mediated by irreducible pion and gluon exchange between constituent quarks is calculated and shown to have a strong tensor component, which tends to cancel the pion exchange tensor interaction between quarks. Its spin-spin component is somewhat weaker than the pion exchange spin-spin interaction, while its central and spin-orbit components are small in comparison to the corresponding single gluon exchange interactions. The combination of the $\pi-$gluon exchange interaction with the single pion exchange interaction and a weak gluon exchange interaction between constituent quarks has the qualitative features required for understanding the hyperfine splittings of the spectra of the nucleon and the $\Delta$ resonances.Comment: LaTeX, 17 pages, 5 Postscript figure