Ga+ beam lithography for suspended lateral beams and nanowires

The authors demonstrate the fabrication of suspended nanowires and doubly clamped beams by using a focused ion beam implanted Ga etch mask followed by an inductively coupled plasma reactive ion etching of silicon. This method will demonstrate how a two-step, completely dry fabrication sequence can be tuned to generate nanomechanical structures on either silicon substrates or silicon on insulator (SOI). This method was used to generate lateral nanowires suspended between 2 µm scaled structures with lengths up to 16 µm and widths down to 40 nm on a silicon substrate. The authors also fabricate 10 µm long doubly clamped beams on SOIs that are 20 nm thick and a minimum of 150 nm wide. In situ electrical measurements of the beams demonstrate a reduction of resistivity from > 37.5 Ω cm down to 0.25 Ω cm. Transmission electron microscopy for quantifying both surface roughness and crystallinity of the suspended nanowires was performed. Finally, a dose array for repeatable fabrication of a desired beam width was also experimentally determined

Multicritical behavior in models with two competing order parameters

We employ the nonperturbative functional Renormalization Group to study models with an O(N_1)+O(N_2) symmetry. Here, different fixed points exist in three dimensions, corresponding to bicritical and tetracritical behavior induced by the competition of two order parameters. We discuss the critical behavior of the symmetry-enhanced isotropic, the decoupled and the biconical fixed point, and analyze their stability in the N_1, N_2 plane. We study the fate of non-trivial fixed points during the transition from three to four dimensions, finding evidence for a triviality problem for coupled two-scalar models in high-energy physics. We also point out the possibility of non-canonical critical exponents at semi-Gaussian fixed points and show the emergence of Goldstone modes from discrete symmetries.Comment: 16 pages, 7 figures, 5 tables, minor changes in updated version, identical to published one in Phys. Rev.

Dynamic Dissemination and Accessibility of Global Responses: The IATUL Conference Proceedings and the Purdue e-Pubs Repository

The necessity of providing free global online access to emerging international responses relevant to librarianship in international technological universities has been a focus of the Library and Information Science community. The International Association of Scientific and Technological University Libraries (IATUL) describes itself as an international organization that “provides an international forum for the exchange of ideas relevant to librarianship by technological universities throughout the world. It also provides library directors and senior managers an opportunity to develop a collaborative approach to solving common problems.” Purdue e-Pubs (www.purdue.edu/epubs) is one of three institutional repositories at Purdue Universities and provides free global online access to research findings and scholarship from Purdue University and our partners. In 2010 the 31st annual IATUL conference was held at Purdue University. Since 2010, the proceedings of the annual conference have been deposited, disseminated, and made globally accessible through the Purdue e-Pubs Repository. Since 2010 the Purdue e-Pubs repository has worked to archive and showcase the research and ideas presented during the 40 year history of the IATUL conference resolving the inherent issues with gray literature. IATUL proceedings are now discoverable (e.g. through Google Scholar), citable, and preserved. Authors of presentations also receive credit that they may not have otherwise been through monthly download reports, and emerging altmetric statistics. This poster and electronic display will present the history, current state, and future possibilities of the relationship of the IATUL conference proceedings and the Purdue e-Pubs Repository, reconceived as a publishing platform

A Game of Spot the Difference: Librarians, Repository Managers, and Publishers

Many library publishing programs emerged from institutional repositories. This close relationship has led to the emergence of content platforms that are designed to operate under either use case, however, the missions and requirements of the two types of program differ. A repository for example, may be primarily concerned with the curation, preservation, and accessibility of their institution’s academic output whilst publishers must also concern themselves with external discoverability, search engine optimization, getting indexed in abstract databases and marketing their journals. In this session, you will hear from three successful library publishers who have embraced this external facing aspect of publishing. The overlaps and differences between repositories and publishers will be explored and the speakers will share their thoughts on how library publishers can best serve their patrons be disseminating work and helping researchers to meet funder mandates for open access and data management

Discovering and quantifying nontrivial fixed points in multi-field models

We use the functional renormalization group and the $\epsilon$-expansion concertedly to explore multicritical universality classes for coupled $\bigoplus_i O(N_i)$ vector-field models in three Euclidean dimensions. Exploiting the complementary strengths of these two methods we show how to make progress in theories with large numbers of interactions, and a large number of possible symmetry-breaking patterns. For the three- and four-field models we find a new fixed point that arises from the mutual interaction between different field sectors, and we establish the absence of infrared-stable fixed point solutions for the regime of small $N_i$. Moreover, we explore these systems as toy models for theories that are both asymptotically safe and infrared complete. In particular, we show that these models exhibit complete renormalization group trajectories that begin and end at nontrivial fixed points.Comment: 10 pages, 6 figures; minor changes, as published in EPJ

Optofluidic circular grating distributed feedback dye laser

We demonstrate an optically pumped surface emitting optofluidic dye laser using a second-order circular grating distributed feedback resonator. We present a composite bilayer soft lithography technique specifically developed for the fabrication of our dye laser and investigate a hybrid polymer material system [poly(dimethylsiloxane)/perfluoropolyether] to construct high-resolution Bragg gratings. Our lasers emit single frequency light at low lasing thresholds of 6 µJ/mm^2. These optofluidic dye lasers can serve as low-cost and compact coherent light sources that are fully integrated within microfluidic analysis chips and provide an efficient approach to construct compact spectroscopy systems

Mask pattern transferred transient grating technique for molecular-dynamics study in solutions

We have developed a mask pattern transferred transient grating (MPT-TG) technique by using metal grating films. Transient thermal grating is generated by an ultraviolet light pattern transfer to nitrobenzene in 2-propanol solution, and the subsequent effect is detected through its diffraction to a probe beam. The thermal diffusion coefficient is obtained by the relationship between the grating periods and the signal decay lifetime, and is well in agreement with the calculated value. This technique has many advantages, such as a simple setting, an easy alignment, accurate phase control, and high stability for molecular-dynamics study in solutions