117 research outputs found
Die Fragilität institutioneller Kooperation
Das vorliegende Buch ist in vierjähriger Forschungsarbeit und zwei Jahrzehnten praktischer Beratungs- und Projektarbeit in verschiedenen Organisationen entstanden. Es geht der Frage nach, warum Kooperation in Institutionen, also in Unternehmen, Parteien, Verwaltungen, Schulen, Spitälern oder Vereinen, oft vom Scheitern bedroht ist.
Institutionelle Kooperation ist unverzichtbar, um gewichtige Ziele zu erreichen: Sowohl die Ziele der jeweiligen Organisation als auch die Ziele der darin tätigen Mitarbeitenden und Führungspersonen. Deren Zusammenspiel, Wohlbefinden und Erfolg werden von der Verpflichtung zur Kooperation wie auch ihrem potenziell konfliktbehafteten Scheitern tangiert. Doch was ist überhaupt institutionelle Kooperation? Was meinen Menschen, wenn sie von Kooperation sprechen, und warum unterscheiden sich ihre Vorstellungen erfahrungsgemäss beträchtlich? Und wie sind die von den Beteiligten vielfach als unüberschaubar oder sogar irritierend wahrgenommenen Vorgänge in der alltäglichen Zusammenarbeit erklärbar?
Diese Fragen werden aus der Perspektive der praktischen Philosophie in den Blick genommen. Es werden unter anderem drei Prototypen von Kooperation unterschieden und anhand ihrer Merkmale herausgearbeitet. Die drei Typen werden dann in ein interaktives Kooperationsmodell eingebettet, welches die soziale Tiefenstruktur kommunikativer Vorgänge im wechselhaften Verlauf einer Zusammenarbeit erhellt. Das Buch trägt damit zu einem vertieften Verständnis der Gelingensbedingungen verschiedener Kooperationsarrangements bei und begründet zugleich, warum Kooperation je nachdem situativ wie auch stets immanent fragil bleibt.
Die Untersuchung ist – wie für eine Forschungsarbeit üblich – theoretisch angelegt, sie wurde allerdings ebenso für interessierte Praktikerinnen und Praktikern geschrieben und soll für deren Arbeit neue Gedankenanstösse geben. Angesprochen sind vor allem Menschen, die Kooperationsdesigns entwerfen müssen und es leid sind, dass Kooperation meist lapidar als Selbstverständlichkeit dargestellt und simplifiziert wird. Der Leitgedanke, der diese Menschen und die vorliegende Arbeit verbindet: Die dringenden und drängenden Herausforderungen und Probleme der Welt können in Wirtschaft, Verwaltung, Politik, Gesundheitswesen, Forschung oder Bildung nur kooperativ angegangen und gelöst werden. Ein vertieftes Verständnis von Kooperation ist dafür nicht nur hilfreich, sondern unverzichtbar
Superior flow for bridge to life with self-expanding venous cannulas
Background: Recently, a compact cardiopulmonary support (CPS) system designed for quick set-up for example, during emergency cannulation, has been introduced. Traditional rectilinear percutaneous cannulas are standard for remote vascular access with the original design. The present study was designed to assess the potential of performance increase by the introduction of next-generation, self-expanding venous cannulas, which can take advantage of the luminal width of the venous vasculature despite a relatively small access orifice. Methods: Veno-arterial bypass was established in three bovine experiments (69 ± 10 kg). The Lifebridge® (Lifebridge GmbH, Munich, Germany) system was connected to the right atrium in a trans-jugular fashion with various venous cannulas; and the oxygenated blood was returned through the carotid artery with a 17 F percutaneous cannula. Two different venous cannulas were studied, and the correlation between the centrifugal pump speed (1500-3900 RPM), flow and the required negative pressure on the venous side was established: (A) Biomedicus 19 F (Medtronic, Tolochenaz, Switzerland); (B) Smart canula 18 F/36 F (Smartcanula LLC, Lausanne, Switzerland). Results: At 1500 RPM, the blood flow was 0.44 ± 0.26 l min−1 for the 19 F rectilinear cannula versus 0.73 ± 0.34 l min−1 for the 18/36 F self-expanding cannula. At 2500 RPM the blood flow was 1.63 ± 0.62 l min−1 for the 19 F rectilinear cannula versus 2.13 ± 0.34 l min−1 for the 18/36 F self-expanding cannula. At 3500 RPM, the blood flow was 2.78 ± 0.47 l min−1 for the 19 F rectilinear cannula versus 3.64 ± 0.39 l min−1 for the 18/36 F self-expanding cannula (p ≪ 0.01 for 18/36 F vs 19 F). At 1500 RPM, the venous line pressure was 18 ± 8 mmHg for the 19 F rectilinear cannula versus 19 ± 5 mmHg for the 18/36 F self-expanding cannula. At 2500 RPM the venous line pressure accounted for −22 ± 32 mmHg for the 19 F rectilinear cannula versus 2 ± 5 mmHg for the 18/36 F self-expanding cannula. At 3500 RPM, the venous line pressure was −112 ± 42 mmHg for the rectilinear cannula versus 28 ± 7 mmHg for the 18/36 F self-expanding cannula (p ≪ 0.01 for 18 F/36 F vs 19 F). Conclusions: The negative pressure required to achieve adequate venous drainage with the self-expanding venous cannula accounts for approximately 31% of the pressure necessary with the 19 F rectilinear cannula. In addition, a pump flow of more than 4 l min−1 can be achieved with the self-expanding design and a well-accepted negative inlet pressure for minimal blood trauma of less than 50 mmH
Insulator-to-metal crossover induced by local spin fluctuations in strongly correlated systems
We study the simplified Hubbard (SH) model in the presence of a transverse
field in the infinite dimension limit. The relevant one-particle Green's
functions of the model are obtained by means a perturbative treatment of the
hopping and of the transverse field around the atomic limit. We consider an
analytical solution for the impurity problem. It is shown that this solution is
very accurate in describing the spectral properties of the heavy-particles of
the SH for intermediate and strong values of the on-site Coulomb interaction
. We find that for large values of an insulator-metal transition takes
place as a function of the transverse field. We analyze the metallic phase
through the behavior of the density of states and of the optical conductivity
and static resistivity. Our results for the latter quantity agree with what is
observed in experiments on .Comment: 6 pages, 5 figures, to appear in Journal of Physics: Condensed Matte
A new self-expanding aortic stent valve with annular fixation: in vitro haemodynamic assessment
Objective: Balloon-expandable stent valves require flow reduction during implantation (rapid pacing). The present study was designed to compare a self-expanding stent valve with annular fixation versus a balloon-expandable stent valve. Methods: Implantation of a new self-expanding stent valve with annular fixation (Symetis®, Lausanne, Switzerland) was assessed versus balloon-expandable stent valve, in a modified Dynatek Dalta® pulse duplicator (sealed port access to the ventricle for transapical route simulation), interfaced with a computer for digital readout, carrying a 25 mm porcine aortic valve. The cardiovascular simulator was programmed to mimic an elderly woman with aortic stenosis: 120/85 mmHg aortic pressure, 60 strokes/min (66.5 ml), 35% systole (2.8 l/min). Results: A total of 450 cardiac cycles was analysed. Stepwise expansion of the self-expanding stent valve with annular fixation (balloon-expandable stent valve) resulted in systolic ventricular increase from 120 to 121 mmHg (126 to 830 ± 76 mmHg)*, and left ventricular outflow obstruction with mean transvalvular gradient of 11 ± 1.5 mmHg (366 ± 202 mmHg)*, systolic aortic pressure dropped distal to the valve from 121 to 64.5 ± 2 mmHg (123 to 55 ± 30 mmHg) N.S., and output collapsed to 1.9 ± 0.06 l/min (0.71 ± 0.37 l/min* (before complete obstruction)). No valve migration occurred in either group. (* = p < 0.05). Conclusions: Implantation of this new self-expanding stent valve with annular fixation has little impact on haemodynamics and has the potential for working heart implantation in vivo. Flow reduction (rapid pacing) is not necessar
Discovery of a dual SENP1 and SENP2 inhibitor
SUMOylation is a reversible post-translational modification (PTM) involving covalent attachment of small ubiquitin-related modifier (SUMO) proteins to substrate proteins. Dysregulation of SUMOylation and deSUMOylation results in cellular malfunction and is linked to various diseases, such as cancer. Sentrin-specific proteases (SENPs) were identified for the maturation of SUMOs and the deconjugation of SUMOs from their substrate proteins. Hence, this is a promising target tackling the dysregulation of the SUMOylation process. Herein, we report the discovery of a novel protein-protein interaction (PPI) inhibitor for SENP1-SUMO1 by virtual screening and subsequent medicinal chemistry optimization of the hit molecule. The optimized inhibitor ZHAWOC8697 showed IC50 values of 8.6 μM against SENP1 and 2.3 μM against SENP2. With a photo affinity probe the SENP target was validated. This novel SENP inhibitor represents a new valuable tool for the study of SUMOylation processes and the SENP-associated development of small molecule-based treatment options
From ferromagnetism to spin-density wave: Magnetism in the two channel periodic Anderson model
The magnetic properties of the two-channel periodic Anderson model for
uranium ions, comprised of a quadrupolar and a magnetic doublet are
investigated through the crossover from the mixed-valent to the stable moment
regime using dynamical mean field theory. In the mixed-valent regime
ferromagnetism is found for low carrier concentration on a hyper-cubic lattice.
The Kondo regime is governed by band magnetism with small effective moments and
an ordering vector \q close to the perfect nesting vector. In the stable
moment regime nearest neighbour anti-ferromagnetism dominates for less than
half band filling and a spin density wave transition for larger than half
filling. is governed by the renormalized RKKY energy scale \mu_{eff}^2
^2 J^2\rho_0(\mu).Comment: 4 pages, RevTeX, 3 eps figure
Infrared spectra of one- and two-dimensional fullerene polymer structures: RbC60 and rhombohedral C-60
We compare the infrared spectra of two types of fullerene polymers: the linear-chain RbC60 and the two-dimensional pressure-polymerized rhombohedral C-60. Both the splitting of the F-1u modes and the structure of newly activated Lines are in agreement with fully ordered structures of molecular symmetry D-2h and D-3d, respectively
Theory of Distinct Crystal Structures of Polymerized Fullerides AC60, A=K, Rb, Cs: the Specific Role of Alkalis
The polymer phases of AC60 form distinct crystal structures characterized by
the mutual orientations of the (C60-)n chains. We show that the direct electric
quadrupole interaction between chains always favors the orthorhombic structure
Pmnn with alternating chain orientations. However the specific quadrupolar
polarizability of the alkali metal ions leads to an indirect interchain
coupling which favors the monoclinic structure I2/m with equal chain
orientations. The competition between direct and indirect interactions explains
the structural difference between KC60 and RbC60, CsC60.Comment: 4 pages, 2 figures, 1 tabl
Evidence for distinct polymer chain orientations in KC60 and RbC60
The KC60 and RbC60 polymer phases exhibit contrasting electronic properties
while powder diffraction studies have revealed no definite structural
difference. We have performed single crystal X-ray diffraction and diffuse
scattering studies of these compounds. It is found that KC60 and RbC60 possess
different chain orientations about their axes, which are described by distinct
space groups Pmnn and I2/m, respectively. Such a structural difference will be
of great importance to a complete understanding of the physical properties.Comment: To be published in Phys. Rev. Let
Electronic response of aligned multishell carbon nanotubes
We report calculations of the effective electronic response of aligned
multishell carbon nanotubes. A local graphite-like dielectric tensor is
assigned to every point of the multishell tubules, and the effective transverse
dielectric function of the composite is computed by solving Maxwell's
equations. Calculations of both real and imaginary parts of the effective
dielectric function are presented, for various values of the filling fraction
and the ratio of the internal and external radii of hollow tubules. Our full
calculations indicate that the experimentally measured macroscopic dielectric
function of carbon nanotube materials is the result of a strong electromagnetic
coupling between the tubes, which cannot be accounted for with the use of
simplified effective medium theories. The presence of surface plasmons is
investigated, and both optical absorption cross sections and energy-loss
spectra of aligned tubules are calculated.Comment: 4 pages, 4 figures, to appear in Phys. Rev.
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