Structure of a liquid crystalline fluid around a macroparticle: Density functional theory study

The structure of a molecular liquid, in both the nematic liquid crystalline and isotropic phases, around a cylindrical macroparticle, is studied using density functional theory. In the nematic phase the structure of the fluid is highly anisotropic with respect to the director, in agreement with results from simulation and phenomenological theories. On going into the isotropic phase the structure becomes rotationally invariant around the macroparticle with an oriented layer at the surface.Comment: 10 pages, 6 figues. Submitted to Phys. Rev.

A high-precision near-infrared survey for radial velocity variable low-mass stars using CSHELL and a methane gas cell

We present the results of a precise near-infrared (NIR) radial velocity (RV) survey of 32 low-mass stars with spectral types K2-M4 using CSHELL at the NASA InfraRed Telescope Facility in the K band with an isotopologue methane gas cell to achieve wavelength calibration and a novel, iterative RV extraction method. We surveyed 14 members of young (≈25-150 Myr) moving groups, the young field star ϵ Eridani, and 18 nearby (<25 pc) low-mass stars and achieved typical single-measurement precisions of 8-15 m s-1with a long-term stability of 15-50 m s-1 over longer baselines. We obtain the best NIR RV constraints to date on 27 targets in our sample, 19 of which were never followed by high-precision RV surveys. Our results indicate that very active stars can display long-term RV variations as low as ∼25-50 m s-1 at ≈2.3125 μm, thus constraining the effect of jitter at these wavelengths. We provide the first multiwavelength confirmation of GJ 876 bc and independently retrieve orbital parameters consistent with previous studies. We recovered RV variabilities for HD 160934 AB and GJ 725 AB that are consistent with their known binary orbits, and nine other targets are candidate RV variables with a statistical significance of 3σ-5σ. Our method, combined with the new iSHELL spectrograph, will yield long-term RV precisions of ≲5 m s-1 in the NIR, which will allow the detection of super-Earths near the habitable zone of mid-M dwarfs

Interactive impact of ethnic distance and cultural familiarity on the perceived effects of free trade agreements

Past research on free trade agreements (FTAs) mostly uses an economic perspective to assess their impact on the level of trade and investments between nations. As a result, there is a distinct paucity of research on the perceptions of employees and managers in organizations affected by FTAs, towards the likely outcomes of those FTAs. We address this gap by using the context of recently signed China-Australia free trade agreement (ChAFTA) to develop a multidimensional scale for the perceived advantages and disadvantages of FTAs. Drawing on social identity theory and the similarly-attraction paradigm we also show direct and interactive effects of perceived ethnic distance (between home and partner country) and cultural familiarity (with the FTA partner country) on these perceived outcomes of FTAs. Our findings highlight the need to look beyond the economic perspective and consider a much broader range of perceived outcomes of FTAs

Jimmying the Back Door of Literature: Dashiell Hammett’s Blue-Collar Modernism

Noting Hammett novels in Hemingway’s library, Gray briefly compares narrative elements of “An Alpine Idyll” and “The Snows of Kilimanjaro” to Hammett’s Thin Man (1934) and The Maltese Falcon (1930)

Self-organization of nanoparticles - implications for interface biology

Cells bind to their surroundings via proteins displayed on the cell surface. These interactions support the cells and are important for many cellular processes, e.g. cell migration during morphogenesis, wound healing and cancer metastasis. There is a yet unmet need for simple and robust in vitro models mirroring the complex molecular organization found in natural tissue. In this thesis, protein-sized gold nanoparticles were used to introduce morphological and biochemical nanopatterns on material surfaces via nanoparticle self-assembly. These surfaces were used to explore the effect of protein organization and other nanoscopic parameters on cell response. In their simplest form, gold nanoparticles (in solution) are stabilized by negatively charged ions adsorbed onto their surfaces. It was shown that such nanoparticles, 10 nm in diameter, could self-organize on a dithiol modified gold surface under the influence of electrostatic double-layer forces. The distance between the adsorbed particles could be tuned by the ionic composition of the particle solution, which was described using classical DLVO-theory. A novel method to prepare surfaces with nanoparticle gradients, based on this mechanism, was introduced. Prepared surfaces were used as templates for the assembly of nanopatterns of chemical entities and proteins, with a periodicity in the sub 100 nm regime, by site-specific grafting of different molecules to the particle surfaces. Patterns with specific cell-binding proteins and peptides as well as synthetic polymers were realized and characterized with SEM, imaging SPR, QCM-D and TOF-SIMS. Gradient patterns were also assembled with multiple ligands, e.g. RGD-peptides and heparin, allowing the investigation of synergistic cell stimuli. Biochemical nanopatterns were evaluated in studies on human fibroblasts and endothelial cells, e.g. the cellular mobility was explored in response to different gradient stimuli. In a separate study, fimbria mediated adhesion of E. coli bacteria to nanoscopic adhesive domains was investigated. Surfaces decorated with gold nanoparticles were also shown to attenuate the complement protein cascade system via morphological alteration of adsorbed proteins. Altogether, concepts and methods presented in this thesis offer a route to systematically explore the interactions between biology and molecularly organized interfaces