466 research outputs found

    Cluster Transformation Coefficients for Structure and Dynamics Calculations in n-Particle Systems: Atoms, Nuclei, and Quarks

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    The structure and dynamics of an n-particle system are described with coupled nonlinear Heisenberg's commutator equations where the nonlinear terms are generated by the two-body interaction that excites the reference vacuum via particle-particle and particle-hole excitations. Nonperturbative solutions of the system are obtained with the use of dynamic linearization approximation and cluster transformation coefficients. The dynamic linearization approximation converts the commutator chain into an eigenvalue problem. The cluster coefficients factorize the matrix elements of the (n)-particles or particle-hole systems in terms of the matrix elements of the (n-1)-systems coupled to a particle-particle, particle-hole, and hole-hole boson. Group properties of the particle-particle, particle-hole, and hole-hole permutation groups simplify the calculation of these coefficients. The particle-particle vacuum-excitations generate superconductive diagrams in the dynamics of 3-quarks systems. Applications of the model to fermionic and bosonic systems are discussed.Comment: 13 pages, 5 figures, Wigner Proceedings for Conference Wigner Centenial Pecs, July 8-12, 200

    Transition energy and lifetime for the ground state hyperfine splitting of high Z lithiumlike ions

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    The ground state hyperfine splitting values and the transition probabilities between the hyperfine structure components of high Z lithiumlike ions are calculated in the range Z=4983Z=49-83. The relativistic, nuclear, QED and interelectronic interaction corrections are taken into account. It is found that the Bohr-Weisskopf effect can be eliminated in a combination of the hyperfine splitting values of the hydrogenlike and lithiumlike ions of an isotope. This gives a possibility for testing the QED effects in a combination of the strong electric and magnetic fields of the heavy nucleus. Using the experimental result for the 1s1s hyperfine splitting in ^{209}Bi^{82+}, the 2s hyperfine splitting in ^{209}Bi^{80+} is calculated to be \Delta E=0.7969(2) eV.Comment: The nuclear charge distribution correction \delta is corrected, 14 pages, Late

    Comparing the performance of flat and hierarchical Habitat/Land-Cover classification models in a NATURA 2000 site

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    The increasing need for high quality Habitat/Land-Cover (H/LC) maps has triggered considerable research into novel machine-learning based classification models. In many cases, H/LC classes follow pre‐defined hierarchical classification schemes (e.g., CORINE), in which fine H/LC categories are thematically nested within more general categories. However, none of the existing machine-learning algorithms account for this pre-defined hierarchical structure. Here we introduce a novel Random Forest (RF) based application of hierarchical classification, which fits a separate local classification model in every branching point of the thematic tree, and then integrates all the different local models to a single global prediction. We applied the hierarchal RF approach in a NATURA 2000 site in Italy, using two land-cover (CORINE, FAO-LCCS) and one habitat classification scheme (EUNIS) that differ from one another in the shape of the class hierarchy. For all 3 classification schemes, both the hierarchical model and a flat model alternative provided accurate predictions, with kappa values mostly above 0.9 (despite using only 2.2–3.2% of the study area as training cells). The flat approach slightly outperformed the hierarchical models when the hierarchy was relatively simple, while the hierarchical model worked better under more complex thematic hierarchies. Most misclassifications came from habitat pairs that are thematically distant yet spectrally similar. In 2 out of 3 classification schemes, the additional constraints of the hierarchical model resulted with fewer such serious misclassifications relative to the flat model. The hierarchical model also provided valuable information on variable importance which can shed light into “black-box” based machine learning algorithms like RF. We suggest various ways by which hierarchical classification models can increase the accuracy and interpretability of H/LC classification maps

    Comparing the performance of flat and hierarchical Habitat/Land-Cover classification models in a NATURA 2000 site

    Get PDF
    The increasing need for high quality Habitat/Land-Cover (H/LC) maps has triggered considerable research into novel machine-learning based classification models. In many cases, H/LC classes follow pre‐defined hierarchical classification schemes (e.g., CORINE), in which fine H/LC categories are thematically nested within more general categories. However, none of the existing machine-learning algorithms account for this pre-defined hierarchical structure. Here we introduce a novel Random Forest (RF) based application of hierarchical classification, which fits a separate local classification model in every branching point of the thematic tree, and then integrates all the different local models to a single global prediction. We applied the hierarchal RF approach in a NATURA 2000 site in Italy, using two land-cover (CORINE, FAO-LCCS) and one habitat classification scheme (EUNIS) that differ from one another in the shape of the class hierarchy. For all 3 classification schemes, both the hierarchical model and a flat model alternative provided accurate predictions, with kappa values mostly above 0.9 (despite using only 2.2–3.2% of the study area as training cells). The flat approach slightly outperformed the hierarchical models when the hierarchy was relatively simple, while the hierarchical model worked better under more complex thematic hierarchies. Most misclassifications came from habitat pairs that are thematically distant yet spectrally similar. In 2 out of 3 classification schemes, the additional constraints of the hierarchical model resulted with fewer such serious misclassifications relative to the flat model. The hierarchical model also provided valuable information on variable importance which can shed light into “black-box” based machine learning algorithms like RF. We suggest various ways by which hierarchical classification models can increase the accuracy and interpretability of H/LC classification maps

    Steps towards the hyperfine splitting measurement of the muonic hydrogen ground state: pulsed muon beam and detection system characterization

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    The high precision measurement of the hyperfine splitting of the muonic-hydrogen atom ground state with pulsed and intense muon beam requires careful technological choices both in the construction of a gas target and of the detectors. In June 2014, the pressurized gas target of the FAMU experiment was exposed to the low energy pulsed muon beam at the RIKEN RAL muon facility. The objectives of the test were the characterization of the target, the hodoscope and the X-ray detectors. The apparatus consisted of a beam hodoscope and X-rays detectors made with high purity Germanium and Lanthanum Bromide crystals. In this paper the experimental setup is described and the results of the detector characterization are presented.Comment: 22 pages, 14 figures, published and open access on JINS

    Alnus glutinosa Riparian Woodlands of Italy and Corsica: Phytosociological Classification and Floristic Diversity

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    A comparative analysis of the riparian vegetation dominated by Alnus glutinosa in Italy and Tyrrhenian islands, based on literature data and unpublished releves, is presented. A total of 456 phytosociological releves were processed. For the definition of plant communities and alliances, hierarchical clustering was performed by using Bray-Curtis coefficient and Detrended Correspondence Analysis ordination methods. Identification of diagnostic species of the vegetation units was performed by means of the phi fidelity index. Quantum GIS software version 3.6 was used for the interpolation of the bioclimatic variables and A. glutinosa communities. Overall, a total of 18 A. glutinosa-riparian wood communities were distinguished for Italy and Tyrrhenian islands, of which two new associations and one new subassassociation are described. The classification of the releves showed two main vegetation groups: the first one including the plant communities of the Osmundo-Alnion alliance, and the other including the vegetation of the Ligustro vulgaris-Alnion glutinosae alliance. This latest includes the riparian meso-thermophilous communities of central and northern Italy. Within the Osmundo-Alnion alliance, two subgroups can be recognized: the first one includes the thermophilous communities of the Hyperico hircini-Alnenion glutinosae sub-alliance, mainly spread in the Tyrrhenian islands, while the second group includes the mesophilous communities attributed to the new suballiance Struthioptero-Alnenion glutinosae, widespread in central Italy and the Corsican mountains. The present paper provides the first comprehensive and exhaustive scheme of the A. glutinosa riparian woodlands diversity in Italy and Corsica

    New national and regional Annex I Habitat records: From #45 to #59

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    New Italian data on the distribution of Annex I Habitats are reported in this contribution. Specifically, 8 new occurrences in Natura 2000 sites are presented and 27 new cells are added in the EEA 10 km × 10 km reference grid. The new data refer to the Italian administrative regions of Apulia, Campania, Calabria, Lazio, Tuscany, Umbria, Sardinia, and Sicily

    Human RSPO1/R-spondin1 Is Expressed during Early Ovary Development and Augments β-Catenin Signaling

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    Human testis development starts from around 42 days post conception with a transient wave of SRY expression followed by up-regulation of testis specific genes and a distinct set of morphological, paracrine and endocrine events. Although anatomical changes in the ovary are less marked, a distinct sub-set of ovary specific genes are also expressed during this time. The furin-domain containing peptide R-spondin1 (RSPO1) has recently emerged as an important regulator of ovary development through up-regulation of the WNT/β-catenin pathway to oppose testis formation. Here, we show that RSPO1 is upregulated in the ovary but not in the testis during critical early stages of gonad development in humans (between 6–9 weeks post conception), whereas the expression of the related genes WNT4 and CTNNB1 (encoding β catenin) is not significantly different between these tissues. Furthermore, reduced R-spondin1 function in the ovotestis of an individual (46,XX) with a RSPO1 mutation leads to reduced β-catenin protein and WNT4 mRNA levels, consistent with down regulation of ovarian pathways. Transfection of wild-type RSPO1 cDNA resulted in weak dose-dependent activation of a β-catenin responsive TOPFLASH reporter (1.8 fold maximum), whereas co-transfection of CTNNB1 (encoding β-catenin) with RSPO1 resulted in dose-dependent synergistic augmentation of this reporter (approximately 10 fold). Furthermore, R-spondin1 showed strong nuclear localization in several different cell lines. Taken together, these data show that R-spondin1 is upregulated during critical stages of early human ovary development and may function as a tissue-specific amplifier of β-catenin signaling to oppose testis determination
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