Modifying instructional activities to promote desirable behavior: A conceptual and practical framework.

Summarizes a framework for conceptualizing and implementing a model to improve student behavior through individualized, assessment-based modifications of curricular activities. A summary of research documenting the influence of curricular variables is included, with particular focus on recent research on the assessment and utilization of student preferences. A practical model of functional assessment and curricular revision is presented, with examples to illustrate the process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spontaneous Clostridium septicum myonecrosis in congenital neutropaenia

Spontaneous Clostridium septicum myonecrosis is an uncommon disorder that has been described in association with malignancy, immunosuppression and neutropaenia. Typical clostridial myonecrosis develops without a visible portal of entry and mortality is high. The pathogenesis is not completely understood but the clostridia may gain access to the circulation via areas of ileo-caecal ulceration secondary to enterocolitis, antibiotics or neoplasms. A 5 year old boy with congenital neutropaenia presented with spontaneous Clostridium septicum myonecrosis in the thigh. Limb salvage was achieved using antibiotics, hyberbaric oxygenation and selective debridement. The portal of entry may have been the gastrointestinal tract as colonic ulceration may occur in neutropaenia, and pre-morbid clindamycin administration may have encouraged overgrowth of colonic clostridia.     

Anwendung eines hochfrequenten Hämmerverfahrens zur Optimierung von geschweißten Motorbauteilen bei MAN Diesel SE

Das hochfrequente Hämmerverfahren HiFIT (high frequency impact treatment) zur Lebensdauerverlängerung bestehender und neuer Stahlschweißkonstruktionen konnte bei MAN Diesel SE erfolgreich eingeführt werden. Ein wesentlicher Arbeitsschritt war dabei die Entwicklung eines neuartigen Bemessungskonzeptes auf Basis bruchmechanischer Methoden. Zum einen wurde das Nachbehandlungsverfahren in der Neukonstruktion einer Ölwanne eingesetzt, um die nötigen Sicherheitsfaktoren gegen Dauerbruch darstellen zu können. Zum anderen wurde es nachträglich eingeführt, nachdem durch Spannungsmessungen an einem Fundamentrahmen die Notwendigkeit einer Verbesserung deutlich wurde. Die Anwendungsbeispiele werden im folgenden Beitrag vorgestellt. In beiden Fällen wurde durch das hochfrequente Hämmerverfahren die Dauerfestigkeit erreicht und durch Betriebserfahrung bestätigt. Damit konnte ein weiterer Schritt in Richtung eines betriebssicheren Leichtbaus von Schweißkonstruktionen erfolgreich gegangen werden. Implementation of high‐frequent hammer‐peening as an optimisation step for welded engine components at MAN Diesel SE. The high‐frequent hammer‐peening called HiFIT (high frequency impact treatment) was introduced successfully at MAN Diesel SE. As an essential step, a new fatigue assessment procedure based on fracture mechanics was developed. On one hand, the after‐treatment procedure was used in the design phase of an oil pan to achieve sufficient safety factors against fatigue fracture. On the other hand, it was adopted in an existing design of a foundation frame because in‐situ measurements have revealed the need for improvement. This paper represents the both examples of application. In both cases, the fatigue requirements have been fulfilled with the high‐frequent hammer‐peening and are approved by field‐experience. Thus, another step towards a reliable light‐weight‐design of welded components could be taken     

Untersuchungen zum Ermüdungsverhalten von Konstruktionsteilen für Mobilkrane

Fatigue behaviour of component sections of mobile cranes out of high strength steel plates. High‐strength structural steels with 960 and/or 1100 MPa minimum yield strength allow a decrease of the investment and operating costs of mobile cranes through lightweight design. However, there still exists an uncertainity for stress resistance under cyclic loads and bearable stresses concerning fatigue behaviour of important crane components. This paper deals for the first time with the fatigue behaviour of crane components examined under realistic load‐time‐cycles derived from realistic crane operating conditions. The results supply important information on the service life. The service life depends in this case strongly from the tension level considerably. The influence of the here applied load‐time‐cycles appears on the other hand small. Additionally, this paper provides a new tool with which the fatigue behaviour of crane components under most different aspects and involved variable combinations can be estimated, consistent with measured values, through a fracture mechanically based model. There can be made important procedure recommendations and hints can be given for a more intense use of high‐strength structural steels for practical application in mobile crane engineering. Inspection intervals and contents can be newly determined. The usage of steels with more than 1100 MPa minimum yield strength in the mobile crane building is evaluated crucially.     

Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy

We present advances in experimental techniques of apertureless scanning near-field optical microscopy (aSNOM). The rational alignment procedure we outline is based upon a phase singularity that occurs while scanning polarizers around the nominal cross-polarized configuration of s-polarized excitation and p-polarized detection. We discuss the theoretical origin of this topological feature of the setup, which is robust against small deviations, such as minor tip misalignment or shape variations. Setting the polarizers to this singular configuration point eliminates all background signal, allowing for reproducible plasmonic eigenmode mapping with optimal signal-to-noise ratio.     

Tensile behavior and cyclic creep of continuous fiber-reinforced glass matrix composites at room and elevated temperatures

In this study we investigated the stress-strain behavior at room and elevated temperatures and the tensile creep and cyclic creep response of a unidirectional SiC fiber-reinforced aluminosilicate glass matrix composite. The interfacial condition of the as-received material was measured by a push-out indentation technique. The stress-strain behavior was that expected for this kind of composite, i.e. “pseudoductile” behavior with extensive fiber “pull-out” at room temperature and brittle failure at intermediate temperatures (750 °C) due to oxidation embrittlement. The stiffness of the composite at 750°C was analyzed for different loading rates, highlighing the influence of the loading rate on apparent composite stiffness, due to matrix softening. The creep studies were conducted at temperatures above and below the softening temperature of the glass (T _g, 745 °C) in air. The cyclic creep experiments showed the existence of extensive viscous strain recovery during the unloading period. The creep strain recovery was quantified using strain recovery ratios. These ratios showed a slight dependence on the temperatures investigated (700 and 750 °C). The crept composites retained their “graceful” fracture behavior only partially after testing, indicating that oxidation of the fiber/matrix interface due to oxygen diffusion through the matrix occurred in the peripheral area of the samples. Dr. Boccaccini is presently at the Institute for Mechanics and Materials, University of California, San Diego, CA 92093, USA.     

Testing the credit view with pooled data: dynamic links among state bank health, investment-oriented bank loans, and economic performance

This paper focuses on the “credit view” theory at the state level, which suggests that state-level banking sector health influences state-level real economic performance. Specifically, we extend typical analysis of the credit view theory, applying relevant state-level economic variables to consider whether the health of a state’s banking system affects capital investment loans and, in turn, whether growth of these loans affects a state’s economic performance. We develop a two-equation state-level model, use more refined measures of capital investment loans, and apply advanced dynamic pooled estimators to our panel of state data for the 1984–1993 period. Regression results support dynamic links among state bank health, state investment-oriented bank loans, and state economic performance, thus supporting existence of a state-level credit channel effect.

Key features of flexure hinges used as rotational joints

This article is supposed to serve as a guide for the design of flexure hinges that act as rotational joints. Firstly, flexure hinges with concentrated and distributed compliance are reviewed. They can be modeled by linear beam theories or by the theory of Elastica, respectively. Secondly, the transition between these limit cases is investigated by finite element methods (FEM). A planar symmetric flexure hinge with a circular notch serves as an exemplary geometry. By extending the notch the compliance is distributed. The deflection curves and the kinetics of desired and parasitic motions are chosen as key features to be studied. The corresponding results are compressed into a pseudo-rigid-body model (PRBM) approximation for a range of geometries. It turned out that the concentrated compliance matches best with an ideal rotational joint, but even for small displacements large stresses occur so that its range of operation is small. Distributing the compliance increases the range of operation, however stiffness within the task space decreases dramatically so that the design of a flexure hinge becomes a tradeoff between the two concurring goals large stiffness and large range of operation.     

Novel Zirconia–Alumina Nanocomposites Combining High Strength and Toughness

Alumina toughened zirconia (ATZ) composites, combining a matrix of tetragonal zirconia polycrystals (TZP) and an alumina dispersion, are known for their high strength, toughness, and abrasion resistance. Depending on the type of stabilizing oxide in TZP the materials can be tailored to be either extremely strong (Y–TZP) or extremely tough (Ce–TZP) with a considerable cutback in the complementary property. Novel nanocomposite ATZ materials consisting of TZP co‐stabilized by neodymium and yttrium oxide (Nd–Y–TZP) combined with a reinforcement of 0–40 vol% alumina were produced to achieve high bending strength of 1200–1500 MPa at a toughness of 8–12 MPa·√m. TZP was produced by coating monoclinic nanopowder with 1.5 mol% yttria and 1.5 mol% neodymia. The powder was then blended with submicron size alumina and consolidated by hot pressing. Mechanical and microstructural properties were investigated.