1,428 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

    Measuring and Managing the Performance of Territories as a hybrid field of study and practice: a System Dynamics Approach

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    The purpose of this paper is to illustrate how system dynamics (SD) modeling can be used to enrich performance management in local government and to foster a common shared view of the relevant system\u2019s structure and behavior among stakeholders for territorial strategic planning. This is a quite hybrid field of analysis in performance measurement/management. In fact, in this context, performance is not primarily related to the single institutions in a regional area; it is rather associated to the territory where they operate. We begin by showing how framing dynamic complexity through SD modeling can support consensus building among different stakeholders in a territory. This shifts the attention beyond the traditional view of strategic planning, which is focused on each single jurisdiction. As shown by the case-study in the paper, a Dynamic Performance Management (DPM) approach, may help different institutions to overcome collaboration barriers. In fact, such approach supports players to detect how pursuing a sustainable development of a territory impacts in the long run on the growth sustainability of each institution operating in the territory itself. This implies that territorial public agencies, e.g. municipalities, may understand and communicate to their stakeholders that long-term performance cannot be only assessed in financial terms or bounded to output measures, but also in relation to the outcomes that public services will generate, i.e. in terms of their value transferred to the territory. Likewise, enterprises operating in a given territory can be enabled to detect how their own performance will be sustainable in the long run if they will generate not only financial capital (i.e. profits), but also social capital to the benefit of the other players belonging to the territory. Therefore, a key to implement a DPM approach for each of the players is to combine an institutional (single-player) with an inter-institutional (i.e. multi-players or territory) perspective with a view to enhancing performance and pursuing sustainable development. An inter-institutional perspective frames the territory (rather than a single institution) as the relevant system where to comprise and manage the cause and effect relationships between performance factors and strategic resources. As shown by the case-study in the paper, a DPM approach may help different institutions to overcome collaboration barriers. In fact, such approach supports players to detect the drivers of sustainable development for both the territory and the organizations belonging to it

    Caracterização da madeira de Taxi-branco-da-terra-firme (Sclerolobium paniculatum Vogel) para energia.

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    Este trabalho analisa a qualidade da madeira, para fins energéticos, de árvores de Sclerolobium paniculatum Vogel, de ocorrência natural e de plantio experimental (cinco árvores cada). Não foram constatadas diferenças significativas entre as duas origens. A madeira possui características comparáveis às tradicionalmente utilizadas para energia no Sul do Brasil

    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

    The RCK2 domain of the human BKCa channel is a calcium sensor

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    Large conductance voltage and Ca2+-dependent K+ channels (BKCa) are activated by both membrane depolarization and intracellular Ca2+. Recent studies on bacterial channels have proposed that a Ca2+-induced conformational change within specialized regulators of K+ conductance (RCK) domains is responsible for channel gating. Each pore-forming α subunit of the homotetrameric BKCa channel is expected to contain two intracellular RCK domains. The first RCK domain in BKCa channels (RCK1) has been shown to contain residues critical for Ca2+ sensitivity, possibly participating in the formation of a Ca2+-binding site. The location and structure of the second RCK domain in the BKCa channel (RCK2) is still being examined, and the presence of a high-affinity Ca2+-binding site within this region is not yet established. Here, we present a structure-based alignment of the C terminus of BKCa and prokaryotic RCK domains that reveal the location of a second RCK domain in human BKCa channels (hSloRCK2). hSloRCK2 includes a high-affinity Ca2+-binding site (Ca bowl) and contains similar secondary structural elements as the bacterial RCK domains. Using CD spectroscopy, we provide evidence that hSloRCK2 undergoes a Ca2+-induced change in conformation, associated with an α-to-β structural transition. We also show that the Ca bowl is an essential element for the Ca2+-induced rearrangement of hSloRCK2. We speculate that the molecular rearrangements of RCK2 likely underlie the Ca2+-dependent gating mechanism of BKCa channels. A structural model of the heterodimeric complex of hSloRCK1 and hSloRCK2 domains is discussed

    RNA editing signature during myeloid leukemia cell differentiation

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    Adenosine deaminases acting on RNA (ADARs) are key proteins for hematopoietic stem cell self-renewal and for survival of differentiating progenitor cells. However, their specific role in myeloid cell maturation has been poorly investigated. Here we show that ADAR1 is present at basal level in the primary myeloid leukemia cells obtained from patients at diagnosis as well as in myeloid U-937 and THP1 cell lines and its expression correlates with the editing levels. Upon phorbol-myristate acetate or Vitamin D3/granulocyte macrophage colony-stimulating factor (GM-CSF)-driven differentiation, both ADAR1 and ADAR2 enzymes are upregulated, with a concomitant global increase of A-to-I RNA editing. ADAR1 silencing caused an editing decrease at specific ADAR1 target genes, without, however, interfering with cell differentiation or with ADAR2 activity. Remarkably, ADAR2 is absent in the undifferentiated cell stage, due to its elimination through the ubiquitin–proteasome pathway, being strongly upregulated at the end of the differentiation process. Of note, peripheral blood monocytes display editing events at the selected targets similar to those found in differentiated cell lines. Taken together, the data indicate that ADAR enzymes play important and distinct roles in myeloid cells

    Simulacral, genealogical, auratic and representational failure: Bushman authenticity as methodological collapse

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    This article engages with the concept of authenticity as deployed in anthropology. The first section critiques authenticity as a simple reference to cultural purity, a traditional isomorphism or historical verisimilitude or as an ‘ethnographic authenticity’. Demarcation of authenticity must take into account philosophical literature that argues that authenticity is an existential question of the ‘modern’ era. Thus, authenticity is offered to us as individuals as a remedy for the maladies of modernity: alienation, anomie and alterity. Authenticity is then discussed as a question of value within an economy of cultural politics that often draws on simulacra, creating cultural relics of dubious origin. The final section discusses various methodological failures and problematiques that are highlighted by the concern for, and scrutiny of, authenticity. The first is the simulacral failure. The subjects of anthropology are mostly real flesh-and-blood people-on-the-ground with real needs. In contrast is the simulacral subject, the brand, the tourist image, the media image or the ever-familiar hyper-real bushmen. Lastly, the article considers what Spivak calls ‘withholding’ – a resistance to authentic representation by the Other. Resistance suggests a need for a radically altered engagement with the Other that includes both a deepening, and an awareness, of anthropology as a process of common ontological unfolding

    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
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