Initial Results from a Stacked Ring Apparatus for Simulation of a Soil Profile

A stack of 48 rings, lined with a latex membrane, is used to confine a column of soil 12 inches high by 12 inches in diameter (300 mm x 300 mm). Both dry and saturated columns of fine sand are shaken at their base, at a centrifugal acceleration of 35.5 g. Measurements of the settlement of the surface, horizontal displacement and pore pressures show that the columns of soil are behaving essentially (although not exactly) as one-dimensional shear beams

Assessing Technological Literacy of Middle School Students

Project Lead the Way (PLTW) is a rigorous and relevant pre-engineering curriculum implemented in middle schools and high schools throughout the United States. PLTW has a hands-on approach using activities and project-based learning. The College of Engineering at Wichita State University has partnered with three local school districts to implement the PLTW program to increase interest in Science, Technology, Engineering and Mathematics (STEM). This study begins to assess the impact of the PLTW program on student perceptions and attitudes toward engineering and technology as part of an ongoing three-year assessment. A pre- and post-assessment were administered to middle school students (N=1063 and N=800, respectively) at the beginning and end of the 2010-2011 academic school year. The assessment consisted of 67-questions addressing students’ attitudes toward engineering and technology. This assessment was a combination of subscales from the Pupils’ Attitude Toward Technology (PATT-USA) and the Middle School Attitudes to Engineering, Science & Mathematics survey. Dependent variables of interest included attitude differences between PLTW students and nonPLTW students, gender differences, and differences attributed to length of involvement in the PLTW program. Results indicated PLTW students have a greater interest in technology, however there were notable gender differences and differences attributed to length of involvement in the program. Males had a greater interest in technology and longer involvement (0-3 years) in the program resulting in more positive attitudes. Females tended to have more negative opinions about technology at both pre- and post-assessment

A Multi-Functional View of Moral Disengagement: Exploring the Effects of Learning the Consequences

This paper takes us beyond the unethical act and explores the use of moral disengagement as a multi-stage, multi-functional regulatory, and coping mechanism that not only allows individuals to engage in unethical behavior, but also manage the negative emotions (i.e., guilt and shame) from learning the consequences of such behavior. A resource-based lens is applied to the moral disengagement process, suggesting that individuals not only morally disengage prior to committing an unethical act in order to conserve their own resources, but also morally disengage as a coping mechanism to reduce emotional duress upon learning of the consequences of their actions, which we describe as post-moral disengagement. These assertions are tested using a scenario-based laboratory study consisting of 182 respondents. Findings indicate that individuals will morally disengage in order to commit an unethical act, will experience negative emotions from having learned of the consequences, and then will engage in post-moral disengagement as a coping mechanism. In addition, the findings suggest that guilt and shame relate differently to moral disengagement

A Richness Study of 14 Distant X-ray Clusters From the 160 Square Degree Survey

We have measured the surface density of galaxies toward 14 X-ray-selected cluster candidates at redshifts greater than z=0.46, and we show that they are associated with rich galaxy concentrations. We find that the clusters range between Abell richness classes 0-2, and have a most probable richness class of one. We compare the richness distribution of our distant clusters to those for three samples of nearby clusters with similar X-ray luminosities. We find that the nearby and distant samples have similar richness distributions, which shows that clusters have apparently not evolved substantially in richness since redshift z =0.5. We compare the distribution of distant X-ray clusters in the L_x--richness plane to the distribution of optically-selected clusters from the Palomar Distant Cluster Survey. The optically-selected clusters appear overly rich for their X-ray luminosities when compared to X-ray-selected clusters. Apparently, X-ray and optical surveys do not necessarily sample identical mass concentrations at large redshifts. This may indicate the existence of a population of optically rich clusters with anomalously low X-ray emission. More likely, however, it reflects the tendency for optical surveys to select unvirialized mass concentrations, as might be expected when peering along large-scale filaments.Comment: The abstract has been abridged. Accepted for publication in the Astrophysical Journa

Finitely generated free Heyting algebras via Birkhoff duality and coalgebra

Algebras axiomatized entirely by rank 1 axioms are algebras for a functor and thus the free algebras can be obtained by a direct limit process. Dually, the final coalgebras can be obtained by an inverse limit process. In order to explore the limits of this method we look at Heyting algebras which have mixed rank 0-1 axiomatizations. We will see that Heyting algebras are special in that they are almost rank 1 axiomatized and can be handled by a slight variant of the rank 1 coalgebraic methods

Engineering electron and hole tunneling with asymmetric InAs quantum dot molecules

Most self-assembled quantum dot molecules are intrinsically asymmetric with inequivalent dots resulting from imperfect control of crystal growth. We have grown vertically-aligned pairs of InAs/GaAs quantum dots by molecular beam epitaxy, introducing intentional asymmetry that limits the influence of intrinsic growth fluctuations and allows selective tunneling of electrons or holes. We present a systemic investigation of tunneling energies over a wide range of interdot barrier thickness. The concepts discussed here provide an important tool for the systematic design and characterization of more complicated quantum dot nanostructures.Comment: 9 pages, 4 figures. To be published in Applied Physics Letters. version 2: Typographical corrections and reference format for journa

Modelling from the past: the leaning southwest tower of Caerphilly Castle 1539-2015

Caerphilly Castle (1268-70) is the first concentric castle in Britain and the second largest in the UK. The dramatic inclination of its ruinous south west tower has been noted since 1539. Comparing data from historical surveys and a terrestrial laser scan undertaken in 2015, this paper seeks to review evidence for the long-term stability of the tower. Digital documentation and archival research by architects is collated to provide data for structural analysis by engineers. A terrestrial laser scan was used to create a detailed three dimensional finite element model to enable structural analysis of the current shape of the tower made by tetrahedral elements. An automated strategy has been implemented for the transformation of the complex three dimensional point cloud into a three dimensional finite element model. Numerical analysis has been carried out aiming at understanding the main structural weaknesses of the tower in its present condition. Comparisons of four sets of data: 1539, 1830, 1870 and 2015 enabled us to determine change albeit between very different methods of measurement

Zone Melting of Uranium

ABSTRACT A study was made of the possible application of the zone melting technique to the separation of u r a n i u m from fission products and other impurities. Bar specimens of U having various aRoying elements were zone purified in thoriacoated alumina boats. U r a n i u m bars previously irradiated in the Brookhaven pile were also zone melted. Zone melting has potential application in the removal of such impurities as B, Fe, Si, Ni, and Co from ordinary U. In the reprocessing of irradiated U, zone melting offers a method for removing such fission products as Zr, Nb, Ru. However, as employed here, it shows little promise as a method for complete decontamination of irradiated U from fission products, primarily because of concurrent slagging effects. Zone m e l t i n g is a purification t e c h n i q u e which has b e e n used to p r e p a r e v e r y p u r e Ge m e t a l in w h i c h the q u a n t i t y of i m p u r i t i e s p r e s e n t is of the order of parts per billion. The :;uccess of this t e c h n i q u e w i t h Ge suggested an i n v e s t i g a t i o n of its possible application to the purification of U f r o m fission products a n d other impurities. This r e p o r t p r e s e n t s the results of such a n investigation. In the zone m e l t i n g process a n a r r o w m o l t e n zone, p r o d u c e d b y i n d u c t i o n or resistance heating, is m a d e to t r a v e r s e t h e solid m e t a l by m o v e m e n t either of the heater or of the metal, as s h o w n in t i m a t e d i s t r i b u t i o n " is r e a c h e d after w h i c h a d d itional passes h a v e no effect. A m e a s u r e of the t e n d e n c y of the i m p u r i t y to m i g r a t e is given by the d i s t r i b u t i o n coefficient k, which is defined as the ratio of the solute c o n c e nt r a t i o n in the solid to that in the liquid at e q u il i b r i u m . The g r e a t e r the factor b y w h i c h k differs from unity, the m o r e r e a d i l y i m p u r i t i e s migrate. A simple t h e o r y of zone m e l t i n g has b e e n developed by P f a n n (1), in w h i c h it is a s s u m e d that solute diffusion in the liquid is sufficiently r a p i d that the i m p u r i t y c o n c e n t r a t i o n is u n i f o r m in the m o l t e n zone while diffusion in the solid phase is negligible. F r o m this theory it is possible to calculate the effect of repeated zone passes if the d i s t r i b u t i o n coefficient is k n o w n . In practice, one expects less m i g r a t i o n t h a n that calculated, because the a s s u m p t i o n s of complete e q u i l i b r i u m on which the c a l c u l a t i o n is based are not strictly true. In a n y case, the p u r ification a t t a i n e d depends on the n u m b e r of passes, the ratio of m o l t e n zone l e n g t h to b a r length, the e q u i l i b r i u m d i s t r i b u t i o n coefficient k, a n d the rate of zone travel. I n T a b l e I are given k v a l u e s for some metals in U, e s t i m a t e d f r o m the p a r t i c u l a r u r a n i u m -m e t a l phase d i a g r a m s (2). It should be n o t e d t h a t these k values are at best a p p r o x i m a t e since g e n e r a l l y the phase d i a g r a m s h a v e not b e e n a c c u r a t e l y d e t e r m i n e d in the region of low i m p u r i t y c o n c e n t r a t i o n . The theoretical ratio of i m p u r i t y c o n c e n t r a t i o n at the low c o n c e n t r a t i o n end of the b a r before a n d afte