Avoidance of Catastrophic Structural Failure as an Evolutionary Constraint: Biomechanics of the Acorn Weevil Rostrum

The acorn weevil (Curculio Linnaeus, 1758) rostrum (snout) exhibits remarkable flexibility and toughness derived from the microarchitecture of its exoskeleton. Modifications to the composite profile of the rostral cuticle that simultaneously enhance the flexibility and toughness of the distal portion of the snout are characterized. Using classical laminate plate theory, the effect of these modifications on the elastic behavior of the exoskeleton is estimated. It is shown that the tensile behavior of the rostrum across six Curculio species with high morphological variation correlates with changes in the relative layer thicknesses and orientation angles of layers in the exoskeleton. Accordingly, increased endocuticle thickness is strongly correlated with increased tensile strength. Rostrum stiffness is shown to be inversely correlated with work of fracture; thus allowing a highly curved rostrum to completely straighten without structural damage. Finally, exocuticle rich invaginations of the occipital sutures are identified both as a likely site of crack initiation in tensile failure and as a source of morphological constraint on the evolution of the rostrum in Curculio weevils. It is concluded that avoidance of catastrophic structural failure, as initiated in these sutures under tension, is the driving selective pressure in the evolution of the female Curculio rostrum.     

Development of superconducting absorbers for CRESST light detectors

An important aspect of dark matter search experiments is the active background reduction by identification of the type of particle interacting in the detector. In CRESST this is achieved by a simultaneous detection of heat and light produced by an interaction in a scintillating crystal. The overall light collection efficiency is a crucial parameter in order to achieve enough sensitivity to measure the small fraction of the deposited energy that is emitted as scintillation light. For this purpose, a thin superconducting lead film deposited on sapphire substrates has been tested as an alternative light absorber to a silicon absorber. The first results already show a better light absorption of the lead film. Other superconducting films are also being analyzed.     

Development and manufacturing of CIS thin film solar modules

Thin film modules based on CIS-technology with power outputs ranging between 5 and 40 W and corresponding circuit aperture area efficiencies between 9.6% and 11% have been introduced recently by Siemens Solar. Current status of production yield and performance is presented demonstrating significantly higher performance than alternative thin film technologies. Further developments have resulted in new champion efficiencies of 12.1% for a large commercial size modules and 14.7% for a small laboratory module.     

Berechnung und Konstruktion von Oszillographenschleifen

Zusammenfassung Nach einer genauen, theoretischen Behandlung der elektrodynamisch erregten Oszillographenschleife werden einfache Näherungsformeln abgeleitet und mit den Ergebnissen der strengen Rechnung verglichen. Da sich hinreichende Übereinstimmung zwischen den beiden Lösungen ergibt, kann die Näherungsrechnung dazu benutzt werden, um eine Reihe von Konstruktionsregeln abzuleiten, die es gestatten, die wichtigsten Eigenschaften und günstigsten Abmessungen einer Oszillographenschleife zu berechnen. Ein Anwendungsbeispiel erläutert die Anwendung der Formeln und beweist ihre Richtigkeit.Als wichtigstes Ergebnis ist hervorzuheben, daß — auch bei günstigster Bemessung — die Stromempfindlichkeit einer Schleifentype mit der dritten Potenz der Eigenfrequenz abnimmt, weshalb eine wesentliche Erhöhung von f₀ über die heute erreichten Werte von 10000 bis 20000 Hz nicht zu erwarten ist. Das Gebiet oberhalb der hohen Tonfrequenzen wird also den praktisch trägheitslosen Oszillographen, vor allem den Kathodenstrahloszillographen, vorbehalten bleiben.     

Rational general solutions of planar rational systems of autonomous ODEs

In this paper, we provide an algorithm to compute explicit rational solutions of a rational system of autonomous ordinary differential equations (ODEs) from its rational invariant algebraic curves. The method is based on the proper rational parametrization of these curves and the fact that by linear reparametrizations, we can find the rational solutions of the given system of ODEs. Moreover, if the system has a rational first integral, we can decide whether it has a rational general solution and compute it in the affirmative case.     

Microfluidic Biosensing Systems Using Magnetic Nanoparticles

In recent years, there has been rapidly growing interest in developing hand held, sensitive and cost-effective on-chip biosensing systems that directly translate the presence of certain bioanalytes (e.g., biomolecules, cells and viruses) into an electronic signal. The impressive and rapid progress in micro- and nanotechnology as well as in biotechnology enables the integration of a variety of analytical functions in a single chip. All necessary sample handling and analysis steps are then performed within the chip. Microfluidic systems for biomedical analysis usually consist of a set of units, which guarantees the manipulation, detection and recognition of bioanalytes in a reliable and flexible manner. Additionally, the use of magnetic fields for performing the aforementioned tasks has been steadily gaining interest. This is because magnetic fields can be well tuned and applied either externally or from a directly integrated solution in the biosensing system. In combination with these applied magnetic fields, magnetic nanoparticles are utilized. Some of the merits of magnetic nanoparticles are the possibility of manipulating them inside microfluidic channels by utilizing high gradient magnetic fields, their detection by integrated magnetic microsensors, and their flexibility due to functionalization by means of surface modification and specific binding. Their multi-functionality is what makes them ideal candidates as the active component in miniaturized on-chip biosensing systems. In this review, focus will be given to the type of biosening systems that use microfluidics in combination with magnetoresistive sensors and detect the presence of bioanalyte tagged with magnetic nanoparticles.     

A plan analysis view of the case of David.

A Plan Analytic conceptualization of depression is presented. It concentrates on the instrumental perspective: What are the conscious and non conscious motives directing David’s overt and covert functioning and determining his behavior and experiencing? (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Localization Events and Microstructural Evolution in Ultra‐Fine Grained NiTi Shape Memory Alloys during Thermo‐Mechanical Loading

Subjecting a thin NiTi specimen to uniaxial tension often leads to a localized martensitic transformation: macroscopic transformation bands form and propagate through the specimen, separating it into regions of fully transformed martensite and original austenite. In the present study, the alternating current potential drop (ACPD) technique is used to analyze the change in electrical resistance of ultra‐fine grained NiTi wires subjected to a broad range of thermo‐mechanical load cases: (i) uniaxial tensile straining at constant temperatures (pseudoelastic deformation); (ii) cooling and heating through the transformation range at constant load (actuator load case); (iii) a combination of mechanical and thermal loading. We monitor the ACPD signals in several zones along the gauge length of specimens, and we demonstrate that a localized type of transformation is a generic feature of pseudoelastic as well as of shape memory deformation. Moreover, the ACPD signals allow to differentiate between temperature‐induced martensite (formed during cooling at no or relatively small loads), stress‐induced martensite, and reoriented martensite (formed under load at low temperatures).