A variable-gain radiating horn using groove guide

A radiating horn of continuously variable gain using groove-guide is proposed. The beam width in both planes is varied. Some experimental measurements at 100 GHz confirm the behaviour.Work carried out at the University of Wales Institute of Science and Technology, Cardiff, U.K.     

A High‐Quality Professional Development for Teachers of Grades 3–6 for Implementing Engineering into Classrooms

With the increasing emphasis on integrating engineering into K‐12 classrooms to help meet the needs of our complex and multidisciplinary society, there is an urgent need to investigate teachers' engineering‐focused professional development experiences as they relate to teacher learning, implementation, and student achievement. This study addresses this need by examining the effects of a professional development program focused on engineering integration, and how teachers chose to implement engineering in their classrooms as a result of the professional development. 198 teachers in grades 3–6 from 43 schools in 17 districts participated in a yearlong professional development program designed to help integrate the new state science standards, with a focus on engineering, into their teaching. Posters including lesson plans and student artifacts were used to assess teachers' engineering practices and the implementation in their classrooms. Results indicated that the majority of the teachers who participated in the professional development were able to effectively implement engineering design lessons in their classrooms suggesting that the teachers' success in implementing engineering lessons in their classroom was closely related to the structure of the professional development program.     

Open-cyclic warfarin isomerism: 5-hydroxywarfarin

Addition of a 5-hydroxy substituent to warfarin [3-(1-phenyl-3-oxobutyl)-4-hydroxycoumarin] shifts the solution equilibrium in chloroform to favor the open isomeric form over the two cyclic diastereomeric hemiketals. X-ray diffraction analysis reveals 5-hydroxywarfarin crystallizes as the open isomer in contrast to the more than 20 warfarin and analog structures which occur ascis ortrans hemiketal forms in the solid. The two peri hydroxyl groups in the structure of 3-(1-phenyl-3-oxobutyl)-4,5-dihydroxycoumarin are intramolecularly H-bonded. Methyl kctal derivatives of 5-hydroxywarfarin and a close analog effectively model the minor cyclic hemiketal forms in solution. Structures of bothcis andtrans cyclic methyl ketals of 3-(4-oxopent-2-yl)-4,5-dihydroxy-coumarin have been determined and the aryl hydroxyls H-bond to the dihydropyranyl ring oxygens of the cyclic ketals. Nuclear magnetic resonance studies suggest that these intramolecular H-bonds persist in chloroform solution. Infrared spectroscopy on the series of compounds in KBr pellets is consistent with the crystallographically determined structures and H-bonding schemes.     

The Development of Appropriate Upscaling Procedures

Permeability upscaling should be carried out with careful attention to the nature of rock heterogeneities. While there are many large-scale features which must be taken into account, there are also important heterogeneities at the small-scale. Many sedimentary structures contain laminae at the mm–cm scale, and beds at the m-scale, which give rise to strong contrasts in permeability. We use a 2D model derived from a photo-panel of an aeolian outcrop, along with permeability measurements from a North Sea oil field, to demonstrate the effects of small-scale heterogeneity. This model is similar in size to a typical cell of a reservoir geological model. We take imaginary probe and core plug measurements from the model, average them, and compare these with the effective permeability for the model computed from a finite difference flow calculation. Although this procedure is standard practice, we show that it can lead to biased estimates of the permeabilities used in flow simulation. As an alternative we suggest using models of representative beds, and performing flow simulation to calculate effective permeabilities for both single-phase and two-phase flow.     

Aryl-aryl bond formation by the fluoride-free cross-coupling of aryldisiloxanes with aryl bromides

The prevalence of the biaryl structural motif in biologically interesting and synthetically important molecules has inspired considerable interest in the development of methods for aryl-aryl bond formation. Herein we describe a novel strategy for this process involving the fluoride-free, palladium-catalysed cross-coupling of readily accessible aryldisiloxanes and aryl bromides. Using a statistical-based optimisation process, preparatively useful reaction conditions were formulated to allow the cross-coupling of a wide range of different substrates. This methodology represents an attractive, cost-efficient, flexible and robust alternative to the traditional transition-metal-catalysed routes typically used to generate molecules containing the privileged biaryl scaffold.     

Coordination complexes of silicon and germanium halides with neutral ligands

The coordination chemistry of silicon(IV) and (II) and germanium(IV) and (II) halides with neutral donor ligands from groups 15 (N, P or As) and 16 (O, S or Se) is reviewed; N-heterocyclic carbene complexes are also included. The focus is mainly on results published after 1990 and illustrates that significant recent developments have been made in the coordination chemistry of low-valent silicon and germanium halide complexes in particular; this is expected to pave the way for much new reaction chemistry both from a fundamental and application-driven perspective.     

Integrated STEM in practice: Learning from Montessori philosophies and practices

In theory, STEM (interdisciplinary science, technology, engineering and mathematics) is cross‐disciplinary and situated in real‐world problem‐solving contexts. In practice, STEM disciplines are often implemented separately using contrived contexts. This paper examines theoretical and empirical aspects of Montessori middle school science in the United States, and its alignment with the conceptual framework of integrated STEM. We selected Montessori adolescent environments because the Montessori philosophy involves interdisciplinary application contextualized in purposeful work and learning. Our research sought to investigate how Montessori middle schools have designed their science programs, and to situate these findings within the current landscape of STEM education and reform‐based science. Based on the results of our survey of 96 U.S. Montessori middle schools, we argue Montessori offers an integrated educational approach that meaningfully situates academic disciplines to mirror local and global challenges, well supported by theory and literature on STEM and situated learning theories. We assert that integrated STEM happens organically in many Montessori middle schools, and takes place through authentic work in communities of practice. Our research communicates the value of looking outside traditional school settings to examine alternative formal education spaces, like Montessori classrooms where integrated STEM happens organically.     

Diagnosis of suspicious breast lesions using an empirical mathematical model for dynamic contrast-enhanced MRI

The purpose of this study was to test whether an empirical mathematical model (EMM) of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can distinguish between benign and malignant breast lesions. A modified clinical protocol was used to improve the sampling of contrast medium uptake and washout. T(1)-weighted DCE magnetic resonance images were acquired at 1.5 T for 22 patients before and after injection of Gd-DTPA. Contrast medium concentration as a function of time was calculated over a small region of interest containing the most rapidly enhancing pixels. Then the curves were fitted with the EMM, which accurately described contrast agent uptake and washout. Results demonstrate that benign lesions had uptake (P<2.0 x 10(-5)) and washout (P<.01) rates of contrast agent significantly slower than those of malignant lesions. In addition, secondary diagnostic parameters, such as time to peak of enhancement, enhancement slope at the peak and curvature at the peak of enhancement, were derived mathematically from the EMM and expressed in terms of primary parameters. These diagnostic parameters also effectively differentiated benign from malignant lesions (P<.03). Conventional analysis of contrast medium dynamics, using a subjective classification of contrast medium kinetics in lesions as "washout," "plateau" or "persistent" (sensitivity=83%, specificity=50% and diagnostic accuracy=72%), was less effective than the EMM (sensitivity=100%, specificity=83% and diagnostic accuracy=94%) for the separation of benign and malignant lesions. In summary, the present research suggests that the EMM is a promising alternative method for evaluating DCE-MRI data with improved diagnostic accuracy.