bluuebunny/crossref_metadata_2025 huggingface dataset:
Ordered Mesoporous α‐Fe2O3 (Hematite) Thin‐Film Electrodes for Application in High Rate Rechargeable Lithium Batteries
Authors: Brezesinski Kirstin , Haetge Jan , Wang John , Mascotto Simone , Reitz Christian , Rein Alexander , Tolbert Sarah H. , Perlich Jan , Dunn Bruce , Brezesinski Torsten
Published: December 2010

Herein is reported the synthesis of ordered mesoporous α‐Fe2O3 thin films produced through coassembly strategies using a poly(ethylene‐co‐butylene)‐block‐poly(ethylene oxide) diblock copolymer as the structure‐directing agent and hydrated ferric nitrate as the molecular precursor. The sol–gel derived α‐Fe2O3 materials are highly crystalline after removal of the organic template and the nanoscale porosity can be retained up to annealing temperatures of 600 °C. While this paper focuses on the characterization of these materials using various state‐of‐the‐art techniques, including grazing‐incidence small‐angle X‐ray scattering, time‐of‐flight secondary ion mass spectrometry, X‐ray photoelectron spectroscopy, and UV–vis and Raman spectroscopy, the electrochemical properties are also examined and it is demonstrated that mesoporous α‐Fe2O3 thin‐film electrodes not only exhibit enhanced lithium‐ion storage capabilities compared to bulk materials but also show excellent cycling stabilities by suppressing the irreversible phase transformations that are observed in microcrystalline α‐Fe2O3.
Hydrogen Solubility and Diffusion in Austenitic Stainless Steels Studied with Thermal Desorption Spectroscopy
Authors: Yagodzinskyy Y. , Todoshchenko O. , Papula S. , Hänninen H.
Published: December 2010

Hydrogen solubility and diffusion in austenitic stainless steels, namely AISI 310, AISI 301LN and AISI 201, are studied with thermal desorption spectroscopy (TDS) after electrochemical potentiostatic hydrogen pre‐charging. Temperature dependencies of hydrogen desorption for all studied steels manifest a complex main peak caused by hydrogen releasing from the steel lattice by diffusion. Depending on the steel and heating rate the peak is situated from 350 to 500 K and its shape reflects a specific of hydrogen diffusion in stainless steels, which are multicomponent alloys. Analysis of the TDS curves is based on the hydrogen diffusion model taking into account trapping of hydrogen atoms in the energetically deep interstitial positions in the steel crystal lattice. Diffusion coefficient of hydrogen and its total content after the same charging procedure are obtained from the TDS curves and compared for the studied steels.
Carbon‐Induced Ordering in Manganese‐Rich Austenite — A Density‐Functional Total‐Energy and Chemical‐Bonding Study
Authors: von Appen Jörg , Dronskowski Richard
Published: December 2010

Density‐functional theory‐based total‐energy calculations have been performed in order to discover possible local atomic ordering effects in manganese‐rich austenite phases. For manganese contents of 25 and 50% we found a thermochemical driving force that should lead to a manganese enrichment of the immediate proximity of the carbon atom. The energy lowers almost linearly from a pure iron‐ to a pure manganese‐coordinated carbon atom with an energy difference between the two M6 octahedra (M = Fe, Mn) of ca. 0.34 eV (33 kJ/mol) for both antiferromagnetic and nonmagnetic structures. This very effect and the energy differences are almost independent of (a) the manganese concentration, (b) the carbon concentration, and (c) the magnetic state. A comprehensive bonding analysis yields that the effect is caused by the destabilization of the carbon atom's surrounding metal–metal bonds which come out larger for iron than for manganese. The size of the energy differences indicate a strong tendency for carbon‐induced short‐range ordering.
Experimental Determination and Simulation of Annealing Textures in Cold Rolled TWIP and TRIP Steels
Authors: Barrales‐Mora L.A. , Lü Y. , Molodov D.A.
Published: December 2010

The annealing textures of a Fe‐0.3%C‐22%Mn TRIP steel and a Fe‐0.6%C‐22%Mn TWIP steel were experimentally determined. The results showed that these alloys have an almost identical texture after recrystallization. In general, the recrystallization textures showed low intensities and a dependency on annealing temperature. The samples annealed at high temperatures exhibited a random texture whereas samples annealed at lower temperature showed at least a weak texture. Due to the low SFE of the metals, we surmise that the nucleation at shear bands contributed to the randomization of the recrystallization texture. It was found that grains with Q orientation grow in volume by a factor of 30 compared to deformed state. A 3D cellular automaton was utilized for the simulation of recrystallization in order to study the impact of different nucleation mechanisms on annealing texture. The simulations showed that at least 70% of nucleation has to occur at shear bands to account for the observed randomization of the texture. In order to reproduce the weak texture of samples annealed at lower temperatures, 30% of the nuclei at shear bands needed to be either Q or Goss oriented. A more detailed analysis is necessary to also reproduce the minor texture components.
PRC2 Complexes with JARID2, MTF2, and esPRC2p48 in ES Cells to Modulate ES Cell Pluripotency and Somatic Cell Reprograming
Authors: Zhang Zhuo , Jones Amanda , Sun Chiao-Wang , Li Chao , Chang Chia-Wei , Joo Heui-Yun , Dai Qian , Mysliwiec Matthew R. , Wu Li-Chen , Guo Yahong , Yang Wei , Liu Kaimao , Pawlik Kevin M. , Erdjument-Bromage Hediye , Tempst Paul , Lee Youngsook , Min Jinrong , Townes Tim M. , Wang Hengbin
Published: December 2010

Polycomb repressive complex two (PRC2) has been implicated in embryonic stem (ES) cell pluripotency; however, the mechanistic roles of this complex are unclear. It was assumed that ES cells contain PRC2 with the same subunit composition as that identified in HeLa cells and Drosophila embryos. Here, we report that PRC2 in mouse ES cells contains at least three additional subunits: JARID2, MTF2, and a novel protein denoted esPRC2p48. JARID2, MTF2, and esPRC2p48 are highly expressed in mouse ES cells compared to differentiated cells. Importantly, knockdowns of JARID2, MTF2, or esPRC2p48 alter the level of PRC2-mediated H3K27 methylation and result in the expression of differentiation-associated genes in ES cells. Interestingly, expression of JARID2, MTF2, and esPRC2p48 together, but not individually, enhances Oct4/Sox2/Klf4-mediated reprograming of mouse embryonic fibroblasts (MEFs) into induced pluripotent stem cells, whereas knockdown or knockout of JARID2, MTF2, or esPRC2p48 significantly inhibits reprograming. JARID2, MTF2, and esPRC2p48 modulate H3K27 methylation and facilitate repression of lineage-associated gene expression when transduced into MEFs, and synergistically stimulate the histone methyltransferase activity of PRC2 in vitro. Therefore, these studies identify JARID2, MTF2, and esPRC2p48 as important regulatory subunits of PRC2 in ES cells and reveal critical functions of these subunits in modulating PRC2's activity and gene expression both in ES cells and during somatic cell reprograming.
Adult Human Müller Glia Cells Are a Highly Efficient Source of Rod Photoreceptors
Authors: Giannelli Serena G. , Demontis Gian Carlo , Pertile Grazia , Rama Paolo , Broccoli Vania
Published: December 2010

There is growing evidence that Müller glia cells (MGCs) might act as regenerative elements in injured retinas of fishes and amniotes. However, their differentiation potential in humans is yet unknown. We isolated Müller glia from adult human retinas and propagated them in vitro revealing for the first time their ability to differentiate into rod photoreceptors. These results were also confirmed with mice retinas. Here, we describe conditions by which human MGCs adopt a rod photoreceptor commitment with a surprising efficiency as high as 54%. Functional characterization of Müller glia-derived photoreceptors by patch-clamp recordings revealed that their electrical properties are comparable to those of adult rods. Interestingly, our procedure allowed efficient derivation of MGC cultures starting from both injured and degenerating and postmortem human retinas. Human transplanted Müller glia-derived photoreceptors integrate and survive within immunodeficient mouse retinas. These data provide evidence that Müller glia retains an unpredicted plasticity and multipotent potential into adulthood, and it is therefore a promising source of novel therapeutic applications in retinal repair.
Concise Review: Vascular Stem Cells and Tumor Angiogenesis
Authors: Melero-Martin Juan M. , Dudley Andrew C.
Published: December 2010

Solid tumors are complex “organs” of cancer cells and a heterogeneous population of hematopoietic cells, mesenchymal cells, and endothelial cells. The cancer stem cell model proposes that tumor growth and progression is driven by rare populations of cancer stem cells; however, nontumor-forming stem and progenitor cells are also present within the tumor microenvironment. These adult stem cells do not form tumors when injected into experimental animals, but they may augment tumor growth through juxtacrine and paracrine regulation of tumor cells and by contributing to neovascularization. Thus, cancer cells may actively co-opt nontumor-forming stem cells distally from the bone marrow or proximally from nearby tissue and subvert their abilities to differentiate and maintain tissue growth, repair, and angiogenesis. This review will cover the roles of nontumor-forming vascular stem cells in tumor growth and angiogenesis.
Production of Mouse Embryonic Stem Cell Lines from Maturing Oocytes by Direct Conversion of Meiosis into Mitosis
Authors: Fulka Helena , Hirose Michiko , Inoue Kimiko , Ogonuki Narumi , Wakisaka Noriko , Matoba Shogo , Ogura Atsuo , Mosko Tibor , Kott Tomas , Fulka Josef
Published: December 2010

ESCs are most commonly derived from embryos originating from oocytes that reached metaphase II. We describe here a novel approach where ESCs with all pluripotency parameters were established from oocytes in which metaphase I was converted, from the cell cycle perspective, directly into metaphase II-like stage without the intervening anaphase to telophase I transition. The resulting embryos initiate development and reach the blastocyst stage from which the ESC lines are then established. Thus, our approach could represent an ethically acceptable method that can exploit oocytes that are typically discarded in in vitro fertilization clinics. Moreover, our results also indicate that the meiotic cell cycle can be converted into mitosis by modulating chromosomal contacts that are typical for meiosis with subsequent licensing of chromatin for DNA replication.
Sur8/Shoc2 Involves Both Inhibition of Differentiation and Maintenance of Self-Renewal of Neural Progenitor Cells via Modulation of Extracellular Signal-Regulated Kinase Signaling
Authors: Moon Byoung-San , Kim Hyun-Yi , Kim Mi-Yeon , Yang Dong-Hwa , Lee Jong-Min , Cho Kyoung-Won , Jung Han-Sung , Choi Kang-Yell
Published: December 2010

Sur8/Shoc2 is a scaffold protein that regulates the Ras-extracellular signal-regulated kinase (ERK) pathway. However, the roles of Sur8 in cellular physiologies are poorly understood. In this study, Sur8 was severely repressed in the course of neural progenitor cell (NPC) differentiation in the cerebral cortex of developing rat embryos. Similarly, Sur8 was also critically reduced in cultured NPCs, which were induced differentiation by removal of basic fibroblast growth factor (bFGF). Sur8 regulation occurs at the protein level rather than at the mRNA level as revealed by both in situ hybridization and reverse transcriptase polymerase chain reaction analyses. The role of Sur8 in NPC differentiation was confirmed by lentivirus-mediated Sur8 knockdown, which resulted in increased differentiation, whereas exogenous expression of Sur8 inhibited differentiation. Contrastingly, NPC proliferation was promoted by overexpression, but was suppressed by Sur8 knockdown. The role of Sur8 as an antidifferentiation factor in the developing rat brain was confirmed by an ex vivo embryo culture system combined with the lentivirus-mediated Sur8 knockdown. The numbers and sizes of neurospheres were reduced, but neuronal outgrowth was enhanced by the Sur8 knockdown. The Ras-ERK pathway is involved in Sur8-mediated regulations of differentiation, as the treatment of ERK kinase (MEK) inhibitors blocks the effects of Sur8. The regulations of NPCs' differentiation and proliferation by the Ras-ERK pathway were also shown by the rescues of the effects of bFGF depletion, neuronal differentiation, and antiproliferation by epidermal growth factor. In summary, Sur8 is an antidifferentiation factor that stimulates proliferation for maintenance of self-renewal in NPCs via modulation of the Ras-ERK pathway.
History of climate modeling
Authors: Edwards Paul N.
Published: December 2010

The history of climate modeling begins with conceptual models, followed in the 19th century by mathematical models of energy balance and radiative transfer, as well as simple analog models. Since the 1950s, the principal tools of climate science have been computer simulation models of the global general circulation. From the 1990s to the present, a trend toward increasingly comprehensive coupled models of the entire climate system has dominated the field. Climate model evaluation and intercomparison is changing modeling into a more standardized, modular process, presenting the potential for unifying research and operational aspects of climate science.WIREs Clim Change2011 2 128–139 DOI: 10.1002/wcc.95

This article is categorized under:

Climate, History, Society, Culture > Technological Aspects and Ideas

Climate Models and Modeling > Knowledge Generation with Models
The closed‐loop implementation of the open‐loop stackelberg solution in the linear quadratic problems
Authors: Tecuceanu G. , Popeea C.
Published: December 2010

The present paper deals with the Stackelberg solution of the basic LQ bicriteria dynamic optimization problem. It is shown that the two‐point boundary value problem involved in the LQ Stackelberg optimization problem has a Hamiltonian structure. Considering this remarkable structural property, an efficient numerical method for solve it, is presented.

The closed‐loop implementation of the open‐loop Stackelberg strategies is obtained by solving a standard differential Riccati equation associated to an extended ordinary LQ optimization problem (by increasing the system state with an additional multiplier). The proper closed‐loop implementation depending only on the system state is possible if a certain differential matrix equation has a continuous solution.
Topological index‐calculation of DAEs in circuit simulation
Authors: Tischendorf C.
Published: December 2010

In electric circuit simulation we are confronted with highly nonlinear DAEs with low smoothness properties. They may have index 2 but they do not belong to the class of Hessenberg form systems that are well understood. The classic and the charge‐oriented modified analysis are shown to lead to the same DAE‐index if the circuit models satisfy some natural assumptions.

We present a topological criteria for calculating the index. This makes it possible to determine the index also for high‐dimensional circuit equation systems.
Optimal control of multibody systems in minimal coordinates
Authors: Von Stryk O.
Published: December 2010

The present paper deals with numerical methods for optimal control of mechanical multibody systems, such as many industrial robots, whose dynamical behavior can be described in minimal coordinates by a system of semi‐explicit second order differential equations: M(q(t))q̈(t) = u(t) + h(q(t), q̇(t), t), 0 ⩽ t ⩽ tf, where q denotes the state variables, u the control variables, and M(q) the positive definite mass matrix. Numerical methods are addressed for computing an approximation of the optimal control u*(t), 0 ⩽ t ⩽ tf, which steers the system from an initial to a final position minimizing a performance index, such as time or energy, subject to bounds or nonlinear constraints on q, q̇, and u. A method is investigated in more detail which is based on piecewise polynomial approximations of state variables and utilizes the structure of the dynamical equations as well as the structure in the resulting large and sparse, nonlinearly constrained optimization problems. Results for an industrial robot with six joints demonstrate that tailored optimization methods are very well suited for fast off‐line optimization of robot trajectories.
Some radial solutions of the equation Δu + K(|x|) u9 = 0 in ℛn
Authors: Vrdoljak B.
Published: December 2010

The present paper deals with the existence, behaviour and approximation of some positive radial solutions u (|x|) of the equation Δu + K (|x|) up = 0. The errors of the approximations for solutions u and the first derivative u′ are defined by the functions which can be sufficiently small A |x| ⩾ 1. The qualitative analysis theory and the topological retraction method are used.
Interpolation with tensor product splines subject to derivative constraints
Authors: Walther Marion
Published: December 2010

In this paper restricted interpolations of data sets (xi, yj, zi, j), i = 0,…, n, j = 0,…, m, on the rectangular grid Δ × Σ = {x0 <… < xn} × {yo <… < ym} are handled using biquadratic C1 and bicubic C2 splines on refined grids. The constraints on the first order derivatives are piecewise constant with respect to the original grid Δ × Σ. If the refinement of the grids are chosen adaptively, the existence of restricted interpolants can be assured for bounds strictly compatible with the data.
Preconditioning for special nonsymmetric systems
Authors: Zítko J.
Published: December 2010

The paper presents an algorithm for solving nonsymmetric linear systems arising from a two‐cyclic discretization of non‐selfadjoint two‐dimensional elliptic partial differential equations. The algorithm consists of a cyclic reduction repetition using red black ordering. The restarted and preconditioned GMRES method with pre‐iterations is used for solving the final reduced system. Numerical experiments have shown that this procedure accelerates the convergence several‐times.
On effective solution for some class of vector boundary Riemann problem and corresponding algebraic equations
Authors: Dmitriyeva I.
Published: December 2010

The special class of homogeneous vector boundary Riemann problem on the finite sequence of compact Riemann surfaces is investigated completely. Its coefficients are noncommutative permutation matrices of the arbitrary but not prime order, and boundary conditions are given on the system of open contours. The constructive algorithm and definite structure of the canonical solution matrix are obtained explicitly and present the considerable generalization of paper [1]. Simultaneously the corresponding class of algebraic equations for the appropriate covering surfaces is formed in obvious way too. The suggested applications concern mostly the solitary waves' theory and inverse scattering problem in particular (e. g. see [2]).
Semiaktive Dämpfung einer schwimmenden Offshorestruktur
Authors: Ehlers J. , Mahrenholtz O.
Published: December 2010

Schwimmende Offshoreplattformen werden durch Seegang zu Bewegungen angeregt. Eine aktive Dämpfung der Bewegung ist aufgrund der erforderlichen Leistung nicht praktikabel. Hier wird eine semiaktive Dämpfung vorgeschlagen, der eine einfache, heuristisch gefundene Strategie zugrunde liegt. Die Wirksamkeit der semiaktiven Dämpfung wird durch Experimente im Wellenkanal demonstriert.
Uniqueness of solution of boundary value problems for the biharmonic equation
Authors: Eidelman S.
Published: December 2010

It is known that in order for a solution of a boundary value problems for elliptic equations in unbounded domains to be unique, it is necessary to impose additional constraints on the behavior, of solutions at infinity. Such constrains may be qualitatively different.

In [1] it was noticed that the assumption that the solutions should be positive for sufficiently large arguments may also serve as a condition that guarantees the uniqueness of solutions. The present report explains an investigation of the conditions on boundary value problems whose fulfillment guarantees the validity of such uniqueness theorems for the biharmonic equation. For harmonic functions that satisfy the Dirichlet or Neumann boundary conditions, there are no such uniqueness theorems. But they can exist for simplest nonlocal boundary value problems for harmonic functions.
Hierarchic Models of Vibration Problems on Thin Domains
Authors: Gerdes K. , Schwab C.
Published: December 2010

The Helmholtz equation in a three‐dimensional plate is approximated by a hierarchy of two‐dimensional models. The necessity of including, besides polynomials, a certain number of trigonometric director functions into the Ansatz, in order to prevent pollution effects at high wave numbers is demonstrated for exponentially weighted norms.
Locally Supported Wavelets on the Sphere
Authors: Göttelmann Jochen
Published: December 2010

We construct explicitly wavelets on the sphere that provide a locally supported and stable basis for the Sobolev spaces H2,0 ⩽ s < 1. We get at hand at fast wavelet transform with almost optimal complexity. This basis can be easily implemented in numerical schemes. We apply the wavelet transform to singularity detection and data compression. This contribution summarizes the results of [1].
On Behavior of the Extended Spectral Function of a Selfadjoint Operator at Infinity
Authors: Gorbachuk V.
Published: December 2010

This paper is devoted to studying the relationship between the growth rate at infinity of the so called extended spectral function of a selfadjoint operator on a fixed element and rhe degree of singularity of this element.
Einige Eigenschaften linearer und quasilinearer dynamischer Systeme mit rückläufigen Störungen nach dem Durchgang durch die Resonanzstellen
Authors: Hartung A.
Published: December 2010

Betrachtet werden lineare und quasilineare dynamische Systeme mit Störungen, die als lineare Kombinationen der Funktionen sin und cos von Polynome dargestellt sind. Diese Modelle verwendet man zum Durchgang durch die Resonanzstellen. Es werden die Eigenschaften beschränkter Lösungen von o. g. Systemen untersucht, darunter der Art deren Strebung gegen null, wenn die Zeit gegen unendlich geht.
Anwendung eines RSM gestützten stochastischen Gradientenverfahrens in der stochastischen Strukturoptimierung flexibler Roboter
Authors: Haubach‐Lippmann C.
Published: December 2010

In vielen Problemstellungen der stochastischen Strukturoptimierung ist es von besonderem Interesse, die Zuverlässigkeit einer Struktur zu maximieren, oder mit anderen Worten die Wahrscheinlichkeit des Versagens zu minimieren. Das robuste Design flexibler Roboterstrukturen ist eine aktuelle Anwendung hierfür. Anhand eines Roboterbeispiels wird die Anwendbarkeit eines stochastischen Gradienten‐Verfahrens mit adaptiver Schrittweitensteuerung, dessen Suchrichtungen durch die response surface method (RSM) bestimmt werden, untersucht.
Eine Finite Element Schalenformulierung ohne Rotationsfreiheitsgrade
Authors: Hauptmann R. , Schweizerhof K.
Published: December 2010

Vielen effizienten Schalenelementen für FE‐Anwendungen liegt das Degenerationskonzept zugrunde, dessen wesentliche Merkmale eine Kinematik mit Rotationsfreiheitsgraden und die Beschränkung auf einen ebenen Spannungszustand sind. Somit erfordern bereits geometrisch nichtlineare Berechnungen aufgrund der Verdrehungsfreiheitsgrade relativ aufwendige Formulierungen, die bei materiell nichtlinearen Berechnungen durch die Forderung nach einem ebenen Spannungszustand wesentlich komplexer werden. Ziel der Studie ist, eine Schalenformulierung vorzustellen, die diese nicht Nachteile aufweist.
Stability for ROW‐methods adapted to circuit simulation
Authors: Hoschek Markus
Published: December 2010

Automatic generation and numerical integration of network equations are the core of industrial TCAD packages for analog simulation of highly integrated circuits [1]. Many packages supply the Jacobian with every function evaluation at very low additional costs: it is about only 1.4 times more expensive to evaluate both right‐hand side and Jacobian than right‐hand side alone.

In this paper we discuss four different approaches to use the cheap Jacobian information within a ROW‐type integration scheme, mainly with respect to stability.
Spectral Analysis of Differential Operators of Mixed Order
Authors: Konstantinov A. Yu.
Published: December 2010

We study the spectral properties of some self‐adjoint matrix differential operators.
Multigrid Schur Complement Preconditioning in BE‐DD Methods
Authors: Kuhn M.
Published: December 2010

We consider Domain Decomposition (DD) Boundary Element (BE) equations and analyze a multigrid preconditioner, derived from the hypersingular operator, for the Schur complement. The robustness of the preconditioner with respect to the number of subdomains is being investigated.
Unbounded Solutions in Non‐Smooth Dynamical Systems at Resonance
Authors: Kunze M.
Published: December 2010

We consider periodically forced non‐smooth dynamical systems at resonance, described by differential inclusions, and we show that analogously to the case of ODEs all solutions are unbounded in the (x)‐phase plane, if the first Fourier coefficient of the forcing is large compared to a certain quantity related to the nonlinearity.
The Central Two‐Point Connection Problem in Quantum Mechanics
Authors: Lay W.
Published: December 2010

Exponentially small effects in physical systems have attained much attention in recent literature. They not only are difficult to understand from the viewpoint of classical (Poincaré) asymptotics but also are hard to calculate. In the following we give a brief account of an approach to the central two‐point connection problem of the triconfluent case of Heun's differential equation. It does not seem to be recognized that the solution of this problem opens the possibility to calculate exponentially small effects. A famous example in mathematical physics is the effect of avoided crossings of eigenvalue curves in the case of the double‐well quartic oscillator in quantum mechanics. On the basis of the above‐mentioned singularity‐analytical approach we have carried out the numerical calculation of the effect with a rather low calculatory effort.
Zur Existenz von Spektrallücken bei periodischen Operatoren vom Divergenztyp
Authors: Lienau K.
Published: December 2010

Wir betrachten Spektraleigenschaften periodischer Divergenztyp‐Operatoren‐Δ· A(x)Δ mit elliptischer Koeffizientenmatrix A(x). Das Hauptinteresse gilt hierbei der Existenz von Spektrallücken bei “typischen” Operatoren, also im generischen Fall. Eine ausführliche Darstellung findet sich in der Arbeit von R. Hempel und K. Lienau [2], in der auch weiterführende Resultate zur Zustandsdichte der betrachteten Operatoren vorgestellt werden.
Optimierung der elastisch gebetteten Träger
Authors: Mikulski L.
Published: December 2010

Es werden folgende Optimalsteuerungsprobleme gelöst: Minimierung der maximalen Verschiebung und optimale verteilung der zusätzlichen Belastung. Die zugehörige Optimalsteuerungsaufgabe führt auf ein Mehrpunktrandwertproblem. Für die Lösung der gestellten Aufgaben, steht ein leistungsfähiges Verfahren zur Verfügung, das auf der Mehrzielmethode beruht. Als Ergebnis erhält man einen Träger mit optimalem Querschnittsverlauf sowie optimaler Lastverteilung, dessen maximale Verschiebung bis zu 40% geringer ist.
On robustness of nonlinear systems
Authors: Paice A. , Wirth F.
Published: December 2010

We study the problem of measuring the robustness of stability for a perturbed discrete time nonlinear system. Various stability radii are introduced and their values for the nonlinear system and its linearization are compared. For the time‐invariant case the nonlinear and the linear version of the stability radius coincide generically. In the case of time‐varying perturbations we may again use the linearization to obtain genericity results on the nonlinear stability radius.
Computing Multiple Turning Points
Authors: Pönisch G. , Schnabel U. , Schwetlick H.
Published: December 2010

A point (x*,λ*) is called a turning point of multiplicity p ≥ 1 of the nonlinear system F(x,δ) = 0, F:ℛn × IR1 → ℛn if rank δx F(x*, λ*) = n ‐ 1, rank [δx F(x*, λ*)|λ F (x*, λ*)] = n, and if the Ljapunov‐Schmidt reduced function has the normal form g(ζ,μ) = ζp+1 ± μ, g : ℛ1 × ℛ1 → ℛ1. A minimally extended system F(x,λ) = 0, H(x, λ) = 0 is proposed for defining turning points of multiplicity p, where H : ℛn × ℛ1 → ℛ1 is a scalar function which is related to the p‐th order partial derivatives of g with respect to ζ. When F depends on m ⩽ p ‐‐ 1 additional parameters α ϵ ℛm, the system F(x,λ,α) = 0 can be inflated by m + 1 scalar equations H1 (x,λ, α) = 0,…, Hm+1 (x,λ, α) = 0. The functions H1, : ℛn × ℛ1 × ℛm × ℛ1 depend on certain partial derivatives of g with respect to ζ where Hm+1 corresponds to H in the case m = 0. The regular solution (x*, λ*, α*) of the extended system of n+m+1 equations delivers the desired turning point (x*, λ*) as first part. For numerically solving these systems, two‐stage Newton‐type methods are proposed. They require to compute higher order partial derivatives of F with respect to low dimensional subspaces as well as derivatives of implicitly defined related functions. Both tasks are realized via automatic differentiation. The behavior of the algorithms has been tested in case of turning points of multiplicity p = 2, 3.
Nonlinear Extensions of Classical Controllers Using Symbolic Computation Techniques: A Dynamical Systems Unifying Approach
Authors: Rodriguez‐Millan Jesus , Bokor Jozsef
Published: December 2010

In previous works we reported the development of symbolic computation tools to automate the design of nonlinear state feedback controllers [1], nonlinear PID controllers [2], nonlinear lag‐lead compensators [3], and nonlinear obsevers [4] using the extended linearization method [5]. In this paper we show that a careful analysis of the state variables representation of these classical controllers indicates that all of them are particular cases of the nonlinear extension of a mth order linear filter, consisting of a kth order input derivative operator followed by an output mth order linear dynamical system. Using this two blocks decomposition approach, the design of nonlinear extensions of nth order controllers can be decomposed into two independent subalgorithms: a kth order PD controller algorithm, and a mth order state vector feedback algorithm. Hence, an appropriate, assembly of our symbolic computation tools NL Feedback and NLPID could, in principle, allow to use the extended linearization method to synthesize nonlinear extension of arbitrary nth order linear filter (controllers).
Bounds on Eigenvalues of Interval Matrices
Authors: Rohn J.
Published: December 2010

We describe a rectangle in the complex plane enclosing all eigenvalues of an interval matrix. We give theoretical bounds (Theorem 1) that are exact for symmetric or skew‐symmetric matrices, and practical bounds (Theorem 2) requiring evaluation of 4 minimal or maximal eigenvalues and 2 spectral radii of symmetric matrices.
First captive breeding of the imperial parrot (Amazona imperialis)
Authors: Reillo Paul R. , Durand, Stephen , Burton Minchinton
Published: December 2010

We describe the rearing and development of the first imperial parrot (Amazona imperialis) hatched and raised in captivity. A single egg was hen‐incubated for 28 days, and the chick was parent‐fed for ∼14 days, after which it was removed for hand‐rearing. Similar to wild, parent‐reared imperial nestlings, the chick developed fully within 12 weeks, weaning at 540 g body weight. Endangered and endemic to Dominica, the imperial is a vital flagship for oceanic rainforest conservation. Chronicling the neonatal development of A. imperialis helps illuminate the natural history of this enigmatic species, whose secretive nesting habits and low population density have frustrated a detailed understanding of its ecology and reproduction. Zoo Biol 30:328–341, 2011. © 2010 Wiley‐Liss, Inc.
Observation of reproductive cycle of female yellow‐margined box turtle (Cuora flavomarginata) using radiography and ultrasonography
Authors: Chen Ting‐Yu , Lee Yen‐Tao , Chi Chau‐Hwa
Published: December 2010

This study presents a combination of radiography and ultrasonography to observe the reproductive cycle of 24 captive female yellow‐margined box turtles in Taiwan. Radiography was mainly used to monitor clutch size, whereas ultrasonography was applied to detect changes in the follicles throughout the year. The observation of the 24 female turtles was performed from April 2007 to June 2008. Their average carapace length was 16.62 ± 1.66 cm and their average body weight was 812 ± 164.98 g. The mean clutch size was three (87 eggs/29 clutches) and the reproductive frequency was 95.83% (23/24). Double clutches were detected in 79.2%, and 20.8% had single clutches. Ovulation occurred from March through August, and the average follicular diameter was 2.16 ± 0.18 cm. Follicles entered the latent period in October (at 1.54 ± 0.26 cm), and vitellogenesis of the next reproductive cycle began in November. Using radiography, the eggshell could be detected on the ninth day after ovulation. The average period of the single clutch group was 6.9 weeks (range 5.1–8.5 weeks). In the double clutch group, the average period of the first clutch was 5.5 weeks (range 4–7.8 weeks) and that of the second clutch was 5.2 weeks (range 4–7.8 weeks). This study has advanced the understanding of reproductive physiology of yellow‐margined box turtle and established a valuable and practical model for comparative study of the reproductive physiology of other chelonians. Zoo Biol 30:689–698, 2011. © 2010 Wiley Periodicals, Inc.
Laparoscopic Repeat Resection of Recurrent Hepatocellular Carcinoma
Authors: Hu Minggen , Zhao Guodong , Xu Dabin , Liu Rong
Published: December 2010

Background

The present study was designed to explore the safety and feasibility of laparoscopic re‐resection of recurrent liver tumors.

Methods

Among 120 hepatocellular carcinoma patients who received laparoscopic hepatectomy, six were carefully selected to receive laparoscopic re‐resection. Surgical indications were evaluated by specific selection criteria for tumor location, size, metastases, vessel invasion, and liver function. Four patients received laparoscopic partial hepatectomy, and two received laparoscopic anatomical left lateral lobe resection. Results were analyzed retrospectively.

Results

The six surgeries (four laparoscopic partial hepatectomies, two laparoscopic anatomical left lateral lobe resections) were successfully performed with no intraoperative complications. Mean operative time was 140.83 ± 35.69 min, mean blood loss was 283.33 ± 256.25 ml, and mean hospital stay was 5.67 ± 1.63 days.

Conclusions

Our experience with carefully selected cases meeting specific criteria suggests that laparoscopic hepatic re‐resection is a safe, feasible procedure that may offer multiple benefits for treating recurrent hepatocellular carcinoma.
Endarterectomy of the Aneurysm Sac in Open Abdominal Aortic Aneurysm Repair Reduces Perigraft Seroma and Improves Graft Incorporation
Authors: Wolff Thomas , Koller Michael T. , Eugster Thomas , Rouden Christophe , Marti Regula , Gürke Lorenz , Stierli Peter
Published: December 2010

Background

Fluid around the graft in the original aneurysm sac after open abdominal aortic aneurysm (AAA) repair is a poorly researched phenomenon. If large, such perigraft seroma can cause symptoms of compression, and cases of rupture have even been described. We assessed whether endarterectomy of the aneurysm sac reduces the incidence of perigraft fluid and improves graft incorporation.

Design and methods

Starting in July 2005, all patients with elective open AAA repair were alternately treated either with conventional thrombectomy or thrombectomy plus endarterectomy of the aneurysm sac. All patients were treated with a polytetrafluoroethylene (PTFE) graft. The maximum axial width of the perigraft fluid collection was measured on computed tomography (CT) scans 1 year after operation.

Results

The CT scans of 115 patients were available; 56 had endarterectomy of the aneurysm sac and 59 did not. Fluid collections were significantly smaller in patients with endarterectomy (median width 4.0 versus 8.0 mm; P = 0.0001). Eight patients with endarterectomy had a fluid collection wider than 10 mm compared to 28 patients without endarterectomy (OR 0.18, 95% CI 0.07–0.46). After endarterectomy, 17 patients had radiological signs of complete graft incorporation in comparison to only 6 patients without endarterectomy (OR 3.85, 95% CI 1.39–10.66). No patients were symptomatic or reoperated for perigraft seroma.

Conclusions

Endarterectomy of the aneurysm sac in open AAA repair appears to improve graft incorporation. The high rate of asymptomatic perigraft seroma is surprising, and its clinical significance is unknown. Ultrafiltration of PTFE grafts may be an underlying mechanism.
Hyperbaric Oxygen Therapy: Solution for Difficult to Heal Acute Wounds? Systematic Review
Authors: Eskes Anne M. , Ubbink Dirk T. , Lubbers Maarten J. , Lucas Cees , Vermeulen Hester
Published: December 2010

Background

Hyperbaric oxygen therapy (HBOT) is used to treat various wound types. However, the possible beneficial and harmful effects of HBOT for acute wounds are unclear.

Methods

We undertook a systematic review to evaluate the effectiveness of HBOT compared to other interventions on wound healing and adverse effects in patients with acute wounds. To detect all available randomized controlled trials (RCTs) we searched five relevant databases up to March 2010. Trial selection, quality assessment, data extraction, and data synthesis were conducted by two of the authors independently.

Results

We included five trials, totaling 360 patients. These trials, with some methodologic flaws, included different kinds of wound and focused on different outcome parameters, which prohibited meta‐analysis. A French trial (n = 36 patients) reported that significantly more crush wounds healed with HBOT than with sham HBOT [relative risk (RR) 1.70, 95% confidence interval (CI) 1.11–2.61]. Moreover, there were significantly fewer additional surgical procedures required with HBOT (RR 1.60, 95% CI 1.03–2.50), and there was significantly less tissue necrosis (RR 1.70, 95% CI 1.11–2.61). In one of two American trials (n = 141) burn wounds healed significantly quicker with HBOT (P < 0.005) than with routine burn care. A British trial (n = 48) compared HBOT with usual care. HBOT resulted in a significantly higher percentage of healthy graft area in split skin grafts (RR 3.50, 95% CI 1.35–9.11). In a Chinese trial (n = 145) HBOT did not significantly improve flap survival in patients with limb skin defects.

Conclusions

HBOT, if readily available, appears effective for the management of acute, difficult to heal wounds.
Pea (Pisumsativum L.) Seeds as an Alternative Dietary Protein Source for Broilers: Influence on Fatty Acid Composition, Lipid and Protein Oxidation of Dark and White Meats
Authors: Laudadio V. , Tufarelli V.
Published: December 2010

An experiment was conducted to evaluate the production parameters, breast and leg muscle fatty acid composition and lipid and protein oxidative stability of broilers fed peas (Pisum sativum L.). The trial involved 120 birds (Hubbard strain) allotted to two groups: group I—control group, fed a basal diet containing soybean meal (195 g kg−1) as the main protein source; whereas group II—experimental group fed diet containing peas (400 g kg−1) as a substitute for conventional soybean. No significant differences were observed for body weight, feed intake or feed conversion ratio (P > 0.05). The total lipids were lower (P < 0.05) in the breast and leg muscles of broilers fed peas. The content of total n‐3 polyunsaturated fatty acids were higher (P < 0.05) in the white and dark meat of birds fed the pea diet compared with soybean control diet. After 7 days of refrigerated storage, the levels of thiobarbituric acid‐reactive substances, lipid hydroperoxides and carbonyl proteins expressed as dinitrophenylhydrazine were similar (P > 0.05) in white and dark meat of chicks fed either diet. The data indicates that dietary pea inclusion does not cause detrimental changes in lipid and protein oxidation of poultry dark and white meats, suggesting the possibility of replacing soybean meal with peas.
“He cheated on me, I cheated on him back”: Mexican American and White adolescents’ perceptions of cheating in romantic relationships
Authors: Williams Lela Rankin , Hickle Kristine E.
Published: December 2010

A qualitative approach was used to explore the meaning and perceptions of cheating in adolescent romantic relationships. Mexican American and White adolescents (N = 75; 53.3% girls; 56.1% Mexican American), separated by gender and ethnicity into 12 focus groups (three groups per type), discussed personal and peer experiences of cheating in dating relationships as both the victim and perpetrator. Dialogue was coded using inductive content analysis; two broader cheating themes encompassing six sub‐themes emerged 1) perceptions of cheating (individual‐oriented, peer‐oriented, and frequency of occurrence) and 2) consequences of cheating (commitment, emotional responses, and relationship outcomes). Mexican American girls spoke most frequently and strongly about cheating, followed by White girls. The meaning and contexts of cheating by ethnicity and gender has important implications for promoting healthy dating behavior during adolescence.
Mycoplasma felis-associated meningoencephalomyelitis in a cat
Authors: Beauchamp Dustin J. , da Costa Ronaldo C. , Premanandan Christopher , Burns Colby G. , Cui Jing , Daniels Joshua B.
Published: December 2010

Mycoplasmas are frequently isolated from many animal species. In domestic cats, mycoplasmas may be isolated from respiratory and ocular mucosae, but other sites are also occasionally colonized by these organisms. No cases of Mycoplasma species-associated neurologic disease have been reported in cats. We describe a case of Mycoplasma felis-associated meningoencephalitis in a 10-month-old domestic shorthair cat.
Unerwünschte Wirkungen und Wechselwirkungen in der Analgetikatherapie
Authors: Bertsche Thilo , Mikus Gerd
Published: December 2010

In der Schmerztherapie stehen heute zahlreiche medikamentöse Therapieoptionen zur Verfügung. Die verfügbaren Analgetika unterscheiden sich dabei nicht nur im Wirkmechanismus, in Potenz und Effektivität sondern auch im Spektrum unerwünschter Wirkungen und Wechselwirkungen. Die Kenntnis klinisch relevanter Aspekte in diesem Bereich ermöglicht es, die Schmerztherapie auf den individuellen Patienten abzustimmen. Nicht-Opioide wie Paracetamol sind in hohen Dosen hepatotoxisch oder besitzen wie Metamizol das Risiko einer Agranulozytose. Nicht-steroidale Antiphlogistika (zum Beispiel Diclofenac) gehen mit einem hohen Risiko für toxische Effekte auf Magen-Darm-Trakt und Nieren einher. Vor allem die sinnvolle Kombination mit anderen in der Schmerztherapie häufiger verwandten Wirkstoffen wie Glucocorticoiden kann zu gastrointestinaler Toxizität und Blutungen führen. Auch in der Anwendung von Opioiden der WHO-Stufe II (zum Beispiel Tramadol) sollte sorgfältig auf Arzneimittel-bezogene Probleme geachtet werden. Dies ist bedingt zum einen durch ihre von der individuellen Metabolisierung abhängigen Pharmakokinetik und zum anderen durch Interaktionen über Cytochrom-P-450-Isoenzyme mit anderen Arzneistoffen. Diese verursachen wie die stark wirksamen Opioide der WHO-Stufe III (zum Beispiel Morphin) Obstipation, Übelkeit und Hautreaktionen (insbesondere Rötung) als klinisch besonders relevante unerwünschte Wirkungen. Eine geeignete Supportivtherapie insbesondere mit auf die Behandlungssituation abgestimmten Laxantien ist dabei unerlässlich.
Unerwünschte Arzneimittelwirkungen bei Kindern
Authors: Jaffan Linda , Läer Stephanie
Published: December 2010

Unerwünschte Arzneimittelwirkungen sind bei Kindern bisher nicht weitreichend genug untersucht worden. Meldungen von UAWs bei Kindern sind besonders wichtig, da diese Patientengruppe bei klinischen Prüfungen bislang selten im Fokus stand und somit viele UAWs in dieser Patientengruppe nicht bekannt sind. Insofern hilft jede einzelne Meldung einer UAW bei Kindern die Datenlage zu verbessern. Wichtig ist, dass nur durch eine sorgfältige Anamnese von klinischem Ereignis und Arzneimitteleinnahme sowie der gezielten Dokumentation ein Zusammenhang abgeleitet werden kann.
Pruritus – eine wichtige unerwünschte Arzneimittelreaktion
Authors: Weisshaar Elke
Published: December 2010

Pruritus kann medikamentös verursacht sein, wobei chronischer Pruritus von akutem Pruritus zu unterscheiden ist. Letztgenannter kann eine Nebenwirkung von Medikamenten wie z. B. Antibiotika sein und sistiert üblicherweise binnen weniger Tage nach Absetzen des Medikaments. Als chronischer Pruritus ist das Bestehen von Juckempfindungen von über sechs Wochen definiert. Chronischer Pruritus stellt diagnostisch und therapeutisch eine große Herausforderung dar. Im Hinblick auf die demographische Entwicklung der Bevölkerung und der Polypharmazie insbesondere alter Menschen sollten Medikamente als mögliche Ursache von chronischem Pruritus stets berücksichtigt werden.
Phytopharmaka als Ursache von unerwünschten Arzneimittelwirkungen
Authors: Hafner-Blumenstiel Verena
Published: December 2010

Phytotherapeutika haben wie alle zur Behandlung am Menschen eingesetzten Stoffe auch unerwünschte Wirkungen. So führt Johanniskraut über die Aktivierung des nukleären Pregnan-X-Rezeptors zu einer vermehrten Enzymsynthese von CYP3A4, was zu einer verminderten Plasmakonzentration einer Reihe von CYP3A4-Substraten führt. Echinacea kann die Wirkung von Immunsupressiva vermindern. Ginseng und Ginkgo biloba sollten nicht zusammen mit gerinnungshemmenden Arzneimitteln eingesetzt werden. Baldrian kann in Kombination mit Barbituraten zu exzessiver Sedierung führen.
Unerwünschte Arzneimittelwirkungen (UAW) und Arzneimittel-Interaktionen – Definition und Einteilung
Authors: Mikus Gerd
Published: December 2010

Unerwünschte Arzneimittelwirkungen treten in der Regel bei allen Arzneimitteltherapien auf, bei denen systemische Konzentrationen erreicht werden. Die meisten dieser Nebenwirkungen sind jedoch als leicht bis moderat einzustufen. Schwerwiegende Nebenwirkungen führen häufig zu Krankenhauseinweisungen und Intensivaufenthalten und sollten deshalb unbedingt vermieden werden. Arzneimittelinteraktionen können beispielsweise durch Enzymhemmung zu einer Akkumulation der Wirksubstanz und damit erhöhter Inzidenz und Schwere von unerwünschten Arzneimittelwirkungen führen oder durch eine Enzyminduktion eine Wirkabschwächung bis hin zum Wirkverlust hervorrufen. Die Kenntnis der Mechanismen trägt zu einer Verminderung oder Vermeidung der unerwünschten Arzneimittelwirkungen bei.