Failure of classical elasticity in auxetic foams

A recent derivation [P.H. Mott and C.M. Roland, Phys. Rev. B 80, 132104 (2009).] of the bounds on Poisson's ratio, v, for linearly elastic materials showed that the conventional lower limit, -1, is wrong, and that v cannot be less than 0.2 for classical elasticity to be valid. This is a significant result, since it is precisely for materials having small values of v that direct measurements are not feasible, so that v must be calculated from other elastic constants. Herein we measure directly Poisson's ratio for four materials, two for which the more restrictive bounds on v apply, and two having values below this limit of 0.2. We find that while the measured v for the former are equivalent to values calculated from the shear and tensile moduli, for two auxetic materials (v < 0), the equations of classical elasticity give inaccurate values of v. This is experimental corroboration that the correct lower limit on Poisson's ratio is 0.2 in order for classical elasticity to apply.Comment: 9 pages, 2 figure

Co-Clustering Network-Constrained Trajectory Data

Recently, clustering moving object trajectories kept gaining interest from both the data mining and machine learning communities. This problem, however, was studied mainly and extensively in the setting where moving objects can move freely on the euclidean space. In this paper, we study the problem of clustering trajectories of vehicles whose movement is restricted by the underlying road network. We model relations between these trajectories and road segments as a bipartite graph and we try to cluster its vertices. We demonstrate our approaches on synthetic data and show how it could be useful in inferring knowledge about the flow dynamics and the behavior of the drivers using the road network

Scholarly Publishing Education for Academic Authors: Reframing the Library’s Instruction Role

Scholarly publishing has made great strides in fulfilling the vision of open access, with more journals and papers now freely available to read and reference on the Internet. Yet that achievement falls short of a truly global open, trusted, and reuseable scholarly record. What are the next steps in openness and the pain points in providing completely open scholarship? Education about the publishing process is still developing, particularly when the publishing infrastructure includes the same colonial systems and biases in academic research and publishing that persist throughout academia. These biases influence what gets published, who gets tenure, what research gets funded, and what scholarship and knowledge is prioritized in the world. The University of San Francisco has an explicitly social justice mission, and addresses its scholarly communication efforts directly at the intersection of social justice and scholarly communication. To address this intersection, librarians can work to help researchers build new competencies to understand and evaluate the diversity of innovative authoring and publishing choices and requirements; choose those that best meet their needs; and implement the changes required in other parts of their work. At Caltech, efforts are made to make research more transparent, reusable, and repeatable through the Author Carpentry program, a campus researcher training initiative focusing on 21st century authoring and publishing skills, practices and tools. Adapted from the highly successful and globally-engaging Software and Data Carpentry researcher training program, Author Carpentry develops, maintains, and delivers high-quality lessons and training sessions for researchers that offer high impact, interactive learning opportunities for researchers at all career stages

A Proposal for a Multi-Drive Heterogeneous Modular Pipe- Inspection Micro-Robot

This paper presents the architecture used to develop a micro-robot for narrow pipes inspection. Both the electromechanical design and the control scheme will be described. In pipe environments it is very useful to have a method to retrieve information of the state of the inside part of the pipes in order to detect damages, breaks and holes. Due to the di_erent types of pipes that exists, a modular approach with di_erent types of modules has been chosen in order to be able to adapt to the shape of the pipe and to chose the most appropriate gait. The micro-robot has been designed for narrow pipes, a _eld in which there are not many prototypes. The robot incorporates a camera module for visual inspection and several drive modules for locomotion and turn (helicoidal, inchworm, two degrees of freedom rotation). The control scheme is based on semi-distributed behavior control and is also described. A simulation environment is also presented for prototypes testing

Transparent and soft elastomeric composites and oil/water biphasic systems with stimuli-triggered release of “invisible” liquid

The synthesis, principles, and properties of a new class of stimuli-responsive soft matter biphasic composites will be introduced. The soft composite consists of more than 30% of aqueous solution emulsion (of micron-sized droplets) optically hidden in a matrix of silicone or hydrocarbon gel. Through delicate adjustment of the refractive index (RI) of the internal aqueous phase, the composite is completely transparent to visible light and the internally dispersed aqueous droplet phase is invisible to the naked eye. Multiple phases can be included in the form of gelled multiple emulsion. The composite exhibits unique stimuli-response capabilities, such as changing its optical transmittance upon mechanical, thermal, osmotic and other stresses. Intrusion damage causes the composite to release the RI matched aqueous phase, which causes change in transparency of color. In addition, when the composite is present in an aqueous medium where salinity is different from the dispersed phase, the osmotic pressure in the droplets causes instantaneous transparency change triggered by osmotic pressure. This enables us to measure osmotic pressure of the aqueous medium quickly. The new composites and gels could find many applications including a number of cosmetics and other consumer products with attractive and unusual appearance and stimulus-triggered active ingredients delivery. Please click Additional Files below to see the full abstract

Utility of PAX8 and PAX2 immunohistochemistry in the identification of renal cell carcinoma in diagnostic cytology

The diagnosis of metastatic renal cell carcinoma (RCC) in cytology specimens may be difficult to confirm on the basis of cytomorphology alone. Often, immunohistochemistry serves as an important adjunct in confirming this diagnosis. Recently, PAX2 was shown to be useful in this regard. In this study, we sought to compare the utility of PAX8 to that of PAX2 immunohistochemistry in the diagnosis of RCC in cytology specimens. First, we verified the performance of PAX8 immunohistochemistry on a tissue microarray (TMA) composed of 54 cases of RCC; PAX8 immunoreactivity was seen in at least 10% of the tumor cells in all cases. Next, we applied PAX8 immunohistochemistry to cell block sections prepared from 24 cases of RCC, obtained from fine‐needle aspirates and effusion specimens. PAX2 immunohistochemistry was performed for comparison. Immunopositivity was defined as the presence of nuclear staining in at least 10% of tumor cell nuclei. Immunoreactivity for PAX8 and PAX2 was seen in 21 (88%) and 20 (83%) of the 24 cases, respectively. The presence of either PAX8 or PAX2 immunostaining was present in 22 of 24 cases, thus showing a total sensitivity of 92%. Overall, the results indicate that PAX8 and PAX2 are diagnostically useful adjuncts in confirming the diagnosis of RCC in cytology specimens. Diagn. Cytopathol. 2012. © 2010 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92391/1/21590_ftp.pd

Electronic Structure of Electron-doped Sm1.86Ce0.14CuO4: Strong `Pseudo-Gap' Effects, Nodeless Gap and Signatures of Short Range Order

Angle resolved photoemission (ARPES) data from the electron doped cuprate superconductor Sm$_{1.86}$Ce$_{0.14}$CuO$_4$ shows a much stronger pseudo-gap or "hot-spot" effect than that observed in other optimally doped $n$-type cuprates. Importantly, these effects are strong enough to drive the zone-diagonal states below the chemical potential, implying that d-wave superconductivity in this compound would be of a novel "nodeless" gap variety. The gross features of the Fermi surface topology and low energy electronic structure are found to be well described by reconstruction of bands by a $\sqrt{2}\times\sqrt{2}$ order. Comparison of the ARPES and optical data from the $same$ sample shows that the pseudo-gap energy observed in optical data is consistent with the inter-band transition energy of the model, allowing us to have a unified picture of pseudo-gap effects. However, the high energy electronic structure is found to be inconsistent with such a scenario. We show that a number of these model inconsistencies can be resolved by considering a short range ordering or inhomogeneous state.Comment: 5 pages, 4 figure