1,536 Works

Methods for intraoperative, sterile pose-setting of patient-specific microstereotactic frames

Benjamin Vollmann, Samuel Müller, Dennis Kundrat, Tobias Ortmaier & Lüder Alexander Kahrs
This work proposes new methods for a microstereotactic frame based on bone cement fixation. Microstereotactic frames are under investigation for minimal invasive temporal bone surgery, e.g. cochlear implantation, or for deep brain stimulation, where products are already on the market. The correct pose of the microstereotactic frame is either adjusted outside or inside the operating room and the frame is used for e.g. drill or electrode guidance. We present a patientspecific, disposable frame that allows...

Einstein@Home search for continuous gravitational waves from Cassiopeia A

Sylvia J. Zhu, Maria Alessandra Papa, Heinz-Bernd Eggenstein, Reinhard Prix, Karl Wette, Bruce Allen, Oliver Bock, David Keitel, Badri Krishnan, Bernd Machenschalk, Miroslav Shaltev & Xavier Siemens
We report the results of a directed search for continuous gravitational-wave emission in a broad frequency range (between 50 and 1000 Hz) from the central compact object of the supernova remnant Cassiopeia A (Cas A). The data come from the sixth science run of LIGO, and the search is performed on the volunteer distributed computing network Einstein@Home. We find no significant signal candidate and set the most constraining upper limits to date on the gravitational-wave...

Formation of Aliphatic and Aromatic α-Hydroxy Ketones by Zygosaccharomyces bisporus

Frauke Neuser, Holger Zorn & Ralf Günter Berger
The wild-type yeast strain Zygosaccharomyces bisporus CBS 702 produced a-hydroxy-ketones (acyloins) from amino acid precursors after transamination to the corresponding 2-oxo acids. The key enzyme of the subsequent decarboxylation and C-C bond forming reaction, pyruvate decarboxylase (PDC), was examined for its substrate- and stereo-specific-ity. A wide variety of saturated and unsaturated aliphatic and aromatic aldehydes was successfully converted to acyloins. 19 of the biotransformation products identified had not been reported as natural substances before. Product...

Implications of the Occurrence of Glitches in Pulsar Free Precession Candidates

D.I. Jones, G. Ashton & R. Prix
The timing properties of radio pulsars provide a unique probe of neutron star interiors. Recent observations have uncovered quasiperiodicities in the timing and pulse properties of some pulsars, a phenomenon that has often been attributed to free precession of the neutron star, with profound implications for the distribution of superfluidity and superconductivity in the star. We advance this program by developing consistency relations between free precession and pulsars glitches, and we show that there are...

Messenger ribonucleoprotein particles from plant cell cultures

J. Pfisterer
Messenger ribonucleoprotein particles were isolated from the polysomes of logarithmically growing plant cell cultures, pulse-labeled with [3H] adenosine for 30 min. More than 80% of the labeled RNP was present in particles sedimenting between 80 S and 30 S on sucrose density gradients, but was not associated with ribosomal subunits. The size distribution differs from those reported for polysomal mRNP particles to date. After fixation with glutaraldehyde the labeled RNP particles had a buoyant density...

L-amino acid oxidases with specificity for basic L-amino acids in cyanobacteria

Achim E. Gau, Achim Heindl, Anke Nodop, Uwe Kahmann & Elfriede K. Pistorius
The two closely related fresh water cyanobacteria Synechococcus elongatus PCC 6301 and Synechococcus elongatus PCC 7942 have previously been shown to constitutively express a FAD-containing L-amino acid oxidase with high specificity for basic L-amino acids (L-arginine being the best substrate). In this paper we show that such an enzyme is also present in the fresh water cyanobacterium Synechococcus cedrorum PCC 6908. In addition, an improved evaluation of the nucleotide/amino acid sequence of the L-amino acid...

On the Stereochemistry of the Lone-Pair Electrons in AX6E-Systems: Dynamically Distorted Anion in (NH4)2SeBr6, Statically Distorted Anion in l, 3-Propanediammonium-Hexabromoselenate(IV) (C3N2H12)SeBr6

Walter Abriel
Using 293 K diffractometer intensity data, the crystal structures of (NH4)2SeBr6 (1) and [H3N(CH2)3NH3]SeBr6 (2) have been determined by single crystal X-ray technique and refined to a final Rw of 0.049 and 0.040, respectively. The dark red crystals of 1 are cubic (space group Fm3m) with a = 10.478(2) Å and Z = 4. This structure contains SeBe62- octahedra (point symmetry m3̄m, distance Se-Br: 2.577(2) Å in an antifluorite type arrangement of cations and anions....

Oxidsulfidchloride der Lanthanide vom Typ M4OS4Cl2 (M = La–Nd)

Thomas Schleid & Falk Lissner
Oxysulfide chlorides, M4OS4Cl2, of the lanthanides (M = La - Nd) are obtained upon the oxidation of the metals with sulfur in the presence of MOCl (or M2O3) and MCl3 in appropriate molar ratios. Additional NaCl or an excess of MCl3 serving as a flux provide even single crystalline material after reactions at 850 °C for seven days in sealed tantalum capsules. The crystal structure of M4OS4Cl2 (hexagonal, P63mc, no. 186, Z = 2; M...

Oxygenated bisabolane fucosides from Carthamus lanatus L.

Bozhanka Mikhova, Helmut Duddeck, Rilka M. Taskova, Maya Mitova & Kalina Alipieva
The aerial parts of Carthamus lanatus (Asteraceae) afforded four new oxygenated bisabolane fucosides, 10-hydroperoxy-bisabola-2,11-diene 7-O-β-D-fucopyranoside, 11-hydroperoxy-bisabola-2,9-diene 7-O-β-D-fucopyranoside, 10-hydroxy-bisabola-2,11-diene 7-O-β-D- fucopyranoside and 11-hydroxy-bisabola-2,9-diene 7-O-β-D-fucopyranoside together with the known compounds α-bisabolol β-D-fucopyranoside, asperuloside, sitosterol 3-O-β-D-glucoside and stigmasterol 3-O-β-D-glucoside. Asperuloside appears to be the second representative of the iridoid monoterpene group found in the plant family Asteraceae, which until recently was considered to lack iridoids. The main constituent α-bisabolol fucoside exhibited noticeable antibacterial and cytotoxic activities.

On the maximum damping performance of piezoelectric switching techniques

Marcus Neubauer, Xu Han & Jörg Wallaschek
Synchronized switch damping on inductor offers a high damping performance in a broad frequency range. It consists of an inductor and resistor in a serial configuration, which are connected and disconnected from the piezoceramics in an alternating manner by a switch. When the switch is triggered by the vibration itself, it adapts to different excitation frequencies especially in the low frequency range. This article presents a detailed study of the damping performance of the synchronized...

Dynamics on supersingular K3 surfaces

M. Schütt
For any odd characteristic p ≡ 2 mod 3, we exhibit an explicit automorphism on the supersingular K3 surface of Artin invariant one which does not lift to any characteristic zero model. Our construction builds on elliptic fibrations to produce a closed formula for the automorphism's characteristic polynomial on second cohomology, which turns out to be an irreducible Salem polynomial of degree 22 with coefficients varying with p. © Swiss Mathematical Society.

Effects of degradable Mg-Ca alloys on dendritic cell function

K. Feser, M. Kietzmann, W. Bäumer, C. Krause & F.W. Bach
Degradable magnesium alloys are new materials for implants used in orthopedic and trauma surgery. The aim of this study was to investigate the influence of degradable magnesium alloys on the function of dendritic cells (DC) as these cells represent the major antigen presenting cells of the body. MgP (pure magnesium), MgCa 0.6 (0.6% calcium), MgCa 0.8 (0.8% calcium), MgCa 1.0 (1% calcium), and MgCa 1.2 (1.2% calcium) alloys were degraded in cell culture medium. In...

Investigation of the Transition Reaction of Tobermorite to Xonotlite under Influence of Additives

Andrea Hartmann, David Schulenberg & Josef-Christian Buhl
The objective of the present work was to investigate the transition reaction of the calcium silicate hydrate tobermorite into xonotlite under influence of additives. Tobermorite is the main binding agent in steam hardened building materials and the appearance of xonotlite indicates the progress of hardening and an overcuring of the material. Hydrothermal experiments under addition of sucrose, calcium formate and calcium chloride dihydrate to the main components quartz and lime were done using temperatures of...

Intake of Minerals from Food Supplements in a German Population - A Nationwide Survey

Janina Willers, Michaela Heinemann, Norman Bitterlich & Andreas Hahn
Introduction: Studies indicate that 17.9% - 60% of adults in Germany and Europe regularly use food supplements. Some reports suggest that their use might be responsible for excessive nutrient intake. The purpose of this survey was to examine the quantitative mineral intakes from food supplements: whether the tolerable upper intake levels (ULs) with supplements alone, or in combination with food was exceeded was checked. Methods: The survey was carried out by the Association for Consumer...

Explaining political attention allocation with the help of issue character: Evidence from the European Council

P. Alexandrova
Policy issues compete for the attention of political actors, and the size of the agenda an issue can occupy is largely determined by the way in which it is defined. This logic constitutes a simple agenda-setting model in which factors related to the participants in the policy process and their context influence the attention a single issue receives after being problematised. In order to be able to apply this model to the construction of a...

Expressing religious identities in the workplace: Analyzing a neglected diversity dimension

Diether Gebert, Sabine Boerner, Eric Kearney, James E. King, Kai Zhang & Lynda Jiwen Song
Responding to Jackson and Joshi's (2011) call for specific models of the effects of particular diversity types and against the backdrop of the rising desire for the public expression of religious identities in the workplace (Hicks, 2003), we develop a framework that systematically explores when and how the expression of diverse religious identities induces relational conflicts in organizational units. In developing this framework, we integrate the respective literatures on religion studies (e.g. Hicks, 2003), identity-disclosure...

Hele-Shaw flow in thin threads: A rigorous limit result

Bogdan-Vasile Matioc & Georg Prokert
We rigorously prove the convergence of appropriately scaled solutions of the 2D Hele-Shaw moving boundary problem with surface tension in the limit of thin threads to the solution of the formally corresponding Thin Film equation. The proof is based on scaled parabolic estimates for the nonlocal, nonlinear evolution equations that arise from these problems. © European Mathematical Society 2012.

Innovation in medicine through degeneration in law? A critical perspective on the Medical Innovation Bill

Nils Hoppe & José Miola
The current debate surrounding the Medical Innovation Bill purports to be aimed at improving the normative framework to the extent that innovation is more likely. A closer look at the mechanisms of the proposed legislation and a more detailed assessment of the reasons given for initiating the legislative process in this instance reveal that the Bill seem to rest on a significant misunderstanding of the current law of medical negligence. This article analyses the provisions...

In vivo testing of a bioabsorbable magnesium alloy serving as total ossicular replacement prostheses

Rebecca Lensing, Peter Behrens, Peter Paul Müller, Thomas Lenarz & Martin Stieve
Magnesium alloys have been investigated in different fields of medicine and represent a promising biomaterial for implants due to characteristics like bioabsorbability and osteoinduction. The objective of this study was to evaluate the usability of magnesium as implant material in middle ear surgery. Magnesium implants were placed into the right middle ear of eighteen New Zealand White rabbits. Nine animals were euthanized after four weeks and nine animals after three month. The petrous bones were...

Investment under company-level pacts before and during the Great Recession

Lutz Bellmann, Hans-Dieter Gerner & Olaf Hübler
Company-level pacts between the management and the works council are often preferred in comparison to agreements between employers’ association and unions because the former negotiating partners are better informed about the economic situation of a company and have fewer goal conflicts than the latter. Moreover, these company-level pacts might reduce the ‘hold-up’ problems which arise once specialized investment is made. Therefore, this article investigates whether such agreements affect firm-level investment. Based on the IAB Establishment...

Kerfless exfoliated thin crystalline Si wafers with Al metallization layers for solar cells

Raphael Niepelt, Jan Hensen, Verena Steckenreiter, Rolf Brendel & Sarah Kajari-Schröder
We report on a kerfless exfoliation approach to further reduce the costs of crystalline silicon photovoltaics making use of evaporated Al as a double functional layer. The Al serves as the stress inducing element to drive the exfoliation process and can be maintained as a rear contacting layer in the solar cell after exfoliation. The 50-70 μm thick exfoliated Si layers show effective minority carrier lifetimes around 180 μs with diffusion lengths of 10 times...

Non-negative global weak solutions for a degenerate parabolic system modelling thin films driven by capillarity

Bogdan-Vasile Matioc
We prove the global existence of non-negative weak solutions for a strongly coupled, fourth-order degenerate parabolic system governing the motion of two thin fluid layers in a porous medium when capillarity is the sole driving mechanism. © 2012 Royal Society of Edinburgh.

Process regulation in the problem-solving processes of fifth graders [Usmerjanje procesov resevanja problemov petosolcev]

Benjamin Rott
It is well known that the regulation of processes is an important factor in problem solving from Grade 7 to university level (cf. Mevarech & Kramarski, 1997; Schoenfeld, 1985). We do not, however, know much about the problem-solving competencies of younger children (cf. Heinze, 2007, p. 15). Do the results of studies also hold true for students below Grade 7? The study presented here strongly suggests that metacognition and process regulation is important in Grade...

Lasers and optics: Looking towards third generation gravitational wave detectors

Nergis Mavalvala, David E. McClelland, Guido Mueller, D.H. Reitze, Roman Schnabel & Benno Willke
Third generation terrestrial interferometric gravitational wave detectors will likely require significant advances in laser and optical technologies to reduce two of the main limiting noise sources: thermal noise due to mirror coatings and quantum noise arising from a combination of shot noise and radiation pressure noise. Increases in laser power and possible changes of the operational wavelength require new high power laser sources and new electro-optic modulators and Faraday isolators. Squeezed light can be used...

First international comparison of fountain primary frequency standards via a long distance optical fiber link

J. Guéna, S. Weyers, M. Abgrall, C. Grebing, V. Gerginov, P. Rosenbusch, Sebastien Bize, B. Lipphardt, H. Denker, N. Quintin, S.M.F. Raupach, D. Nicolodi, F. Stefani, N. Chiodo, S. Koke, A. Kuhl, F. Wiotte, F. Meynadier, E. Camisard, C. Chardonnet, Y. Le Coq, M. Lours, G. Santarelli, A. Amy-Klein, R. Le Targat … & G. Grosche
We report on the first comparison of distant caesium fountain primary frequency standards (PFSs) via an optical fiber link. The 1415 km long optical link connects two PFSs at LNESYRTE (Laboratoire National de métrologie et d'Essais-SYstème de Références Temps- Espace) in Paris (France) with two at PTB (Physikalisch-Technische Bundesanstalt) in Braunschweig (Germany). For a long time, these PFSs have been major contributors to accuracy of the International Atomic Time (TAI), with stated accuracies of around...

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