1,152 research outputs found

    Morphometric analysis of the sella turcica in Turkish individuals with different dentofacial skeletal patterns

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    Background: The aim of this study was to evaluate the morphometric analysis of sella turcica in a Turkish population according to gender, age, and dentofacial skeletal type and to investigate the prevalence of sella turcica shapes in different dentofacial skeletal types. Materials and methods: The lateral cephalometric radiographs of 362 patients (145 males, 217 females) were included and grouped by age, gender, and dentofacial skeletal patterns. Linear dimensions of sella turcica, which include the length, height, and diameter, were measured, and the shapes of sella turcica were evaluated. Results: The anatomical variants of the sella turcica in this study were normal morphology (39.0%), followed by pyramidal shape (15.5%), double contour of floor (14.6%), oblique anterior wall (14.4%), irregular dorsum sella (8.6%), and sella turcica bridge (8.0%). Significant differences were found between sella turcica shapes and dentofacial skeletal types (p < 0.01). Females had greater diameter size of sella turcica than males (p < 0.01). In addition, the subjects in the 15–21 age group had larger sella turcica depths and diameters than the subjects in the 9–14 age group (p < 0.05 and p < 0.01, respectively). However, no significant differences were found between age groups in terms of sella turcica lengths (p > 0.05). Conclusions: Results from this study showed that the sample had a higher rate of morphological variation (39% normal, 61% other types) in comparison with other populations or ethnic groups. The class III patients had more irregularity (notching) types in the posterior part of the dorsum sella and fewer oblique anterior wall types than the others. Linear dimensions and morphological types of sella turcica in this study can be used as reference for additional investigators, such as radiologists, orthodontists, maxillofacial surgeons, and neurosurgeons, to interpret and plan surgical procedures involving the sellar region

    Overlap Dirac Operator, Eigenvalues and Random Matrix Theory

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    The properties of the spectrum of the overlap Dirac operator and their relation to random matrix theory are studied. In particular, the predictions from chiral random matrix theory in topologically non-trivial gauge field sectors are tested.Comment: 3 pages latex with 1 postscript figure. Talk presented at LATTICE99(topology

    Efficiency of energy transfer in a light-harvesting system under quantum coherence

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    We investigate the role of quantum coherence in the efficiency of excitation transfer in a ring-hub arrangement of interacting two-level systems, mimicking a light-harvesting antenna connected to a reaction center as it is found in natural photosynthetic systems. By using a quantum jump approach, we demonstrate that in the presence of quantum coherent energy transfer and energetic disorder, the efficiency of excitation transfer from the antenna to the reaction center depends intimately on the quantum superposition properties of the initial state. In particular, we find that efficiency is sensitive to symmetric and asymmetric superposition of states in the basis of localized excitations, indicating that initial state properties can be used as a efficiency control parameter at low temperatures.Comment: Extended version of original paper. 7 pages, 2 figure

    Stabilizing sodium hypochlorite at high pH: effects on soft tissue and dentin

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    NaOH-stabilized NaOCl solutions have a higher alkaline capacity and are thus more proteolytic than standard counterparts

    Preparation of Ion Imprinted SPR Sensor for Real-Time Detection of Silver(I) Ion from Aqueous Solution

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    The aim of the submitted study is to develop molecular imprinting based surface plasmon resonance (SPR) sensor for real-time silver ion detection. For this purpose polymeric nanofilm layer on the gold SPR chip surface was prepared via UV polymerization of acrylic acid at 395 nm for 30 minutes. N-methacryloyl- L cysteine used as the functional monomer to recognize the silver(I) ions from the aqueous solutions and methylene bisacrylamide used as the crosslinker for obtaining structural rigidity of the formed cavities. Silver(I) solutions with different concentrations were applied to SPR system to investigate the efficiency of the imprinted SPR sensor in real time. For the control experiments, non-imprinted SPR sensor was also prepared as described above without addition of template “silver(I) ions”. Prepared SPR sensors were characterized with atomic force microscopy (AFM). In order to show the selectivity of the silver(I) imprinted SPR sensor, competitive adsorption of Cu(II), Pb(II), Ni(II) ions was investigated. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3489

    Determinants of the selective toxicity of alloxan to the pancreatic B cell.

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    Small eigenvalues of the staggered Dirac operator in the adjoint representation and Random Matrix Theory

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    The low-lying spectrum of the Dirac operator is predicted to be universal, within three classes, depending on symmetry properties specified according to random matrix theory. The three universal classes are the orthogonal, unitary and symplectic ensemble. Lattice gauge theory with staggered fermions has verified two of the cases so far, unitary and symplectic, with staggered fermions in the fundamental representation of SU(3) and SU(2). We verify the missing case here, namely orthogonal, with staggered fermions in the adjoint representation of SU(N_c), N_c=2, 3.Comment: 3 pages, revtex, 2 postscript figure

    Universality for orthogonal and symplectic Laguerre-type ensembles

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    We give a proof of the Universality Conjecture for orthogonal (beta=1) and symplectic (beta=4) random matrix ensembles of Laguerre-type in the bulk of the spectrum as well as at the hard and soft spectral edges. Our results are stated precisely in the Introduction (Theorems 1.1, 1.4, 1.6 and Corollaries 1.2, 1.5, 1.7). They concern the appropriately rescaled kernels K_{n,beta}, correlation and cluster functions, gap probabilities and the distributions of the largest and smallest eigenvalues. Corresponding results for unitary (beta=2) Laguerre-type ensembles have been proved by the fourth author in [23]. The varying weight case at the hard spectral edge was analyzed in [13] for beta=2: In this paper we do not consider varying weights. Our proof follows closely the work of the first two authors who showed in [7], [8] analogous results for Hermite-type ensembles. As in [7], [8] we use the version of the orthogonal polynomial method presented in [25], [22] to analyze the local eigenvalue statistics. The necessary asymptotic information on the Laguerre-type orthogonal polynomials is taken from [23].Comment: 75 page

    Distribution of entanglement in light-harvesting complexes and their quantum efficiency

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    Recent evidence of electronic coherence during energy transfer in photosynthetic antenna complexes has reinvigorated the discussion of whether coherence and/or entanglement has any practical functionality for these molecular systems. Here we investigate quantitative relationships between the quantum yield of a light-harvesting complex and the distribution of entanglement among its components. Our study focusses on the entanglement yield or average entanglement surviving a time scale comparable to the average excitation trapping time. As a prototype system we consider the Fenna-Matthews-Olson (FMO) protein of green sulphur bacteria and show that there is an inverse relationship between the quantum efficiency and the average entanglement between distant donor sites. Our results suggest that longlasting electronic coherence among distant donors might help modulation of the lightharvesting function.Comment: Version accepted for publication in NJ

    Pseudo-unitary symmetry and the Gaussian pseudo-unitary ensemble of random matrices

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    Employing the currently discussed notion of pseudo-Hermiticity, we define a pseudo-unitary group. Further, we develop a random matrix theory which is invariant under such a group and call this ensemble of pseudo-Hermitian random matrices as the pseudo-unitary ensemble. We obtain exact results for the nearest-neighbour level spacing distribution for (2 X 2) PT-symmetric Hamiltonian matrices which has a novel form, s log (1/s) near zero spacing. This shows a level repulsion in marked distinction with an algebraic form in the Wigner surmise. We believe that this paves way for a description of varied phenomena in two-dimensional statistical mechanics, quantum chromodynamics, and so on.Comment: 9 pages, 2 figures, LaTeX, submitted to the Physical Review Letters on August 20, 200
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