Dynamic measurements and simulations of airborne picolitre-droplet coalescence in holographic optical tweezers

We report studies of the coalescence of pairs of picolitre aerosol droplets manipulated with holographic optical tweezers, probing the shape relaxation dynamics following coalescence by simultaneously monitoring the intensity of elastic backscattered light (EBL) from the trapping laser beam (time resolution on the order of 100 ns) while recording high frame rate camera images (time resolution <10 µs). The goals of this work are to: resolve the dynamics of droplet coalescence in holographic optical traps; assign the origin of key features in the time-dependent EBL intensity; and validate the use of the EBL alone to precisely determine droplet surface tension and viscosity. For low viscosity droplets, two sequential processes are evident: binary coalescence first results from overlap of the optical traps on the timescale of microseconds followed by recapture of the composite droplet in an optical trap on the timescale of milliseconds. As droplet viscosity increases, the relaxation in droplet shape eventually occurs on the same timescale as recapture, resulting in a convoluted evolution of the EBL intensity that inhibits quantitative determination of the relaxation timescale. Droplet coalescence was simulated using a computational framework to validate both experimental approaches. The results indicate that time-dependent monitoring of droplet shape from the EBL potential of high frame rate imaging to examine the coalescence of dissimilar viscosity droplets is discussed

Cycling the City: Locating Cycling in the Continued (Re)Structuring of North American Cities

Bicycling is a growing mobility practice within contemporary U.S. cities that has multiple effects on the formation of the urban as &ldquo;We are surrounded by cycling&rdquo; (Horton et al, 2007, p. 1). This project investigates how cycling has shaped the city by analyzing the role that the governance and practice of cycling currently plays in the political, economic, social, spatial, and affective re-formation of the urban. Through the use of a combination of methods, working at various levels of analysis, the aim is to locate the impact of cycling policies and practices on the structural, discursive, and embodied dimensions of contemporary urban (re)structuring. It is an analysis of macro political processes, the formation of cycling communities, and the experiential dimension of riding in the city. Latham & McCormack (2010) state &ldquo;cities are constantly generating new forms of collective life, novel ways of being together&rdquo; (p.55). Thus, this project interrogates the various ways in which cycling impacts upon cities, and influences their (re)formation in potentially &ldquo;historically unprecedented ways&rdquo; (Wachsmuth et al, 2011, p. 741). Through studying cycling in Boston, Baltimore, and Washington DC this project provides a multi-sited analysis of how cycling is positioned within U.S. cities currently, as well as the complex and diverse processes that inform the contemporary organization of these urban spaces. U.S. cities currently exist within a broad &ldquo;climate of cuts, austerity and state retrenchment&rdquo; (Newman, 2013, p. 1) that has defined current patterns of urban governance. I have researched the ways in which cycling has underpinned and simultaneously challenged these broad shifts toward neoliberal governance. Cycling is both drawn into &ldquo;marketing of urban &ldquo;culture&rdquo; and history by entrepreneurial governance&rdquo; (Cherot and Murray, 2002, p. 432), but also underpins cities as entities that &ldquo;defy efforts to be classified into types, reduced to essential characteristics, and fixed by boundaries (intellectual or otherwise)&rdquo; (Prytherch, 2002, p. 772). As such this project investigates this simultaneously overlapping and contradictory impact of cycling on the city, mapping the multiple locations of cycling within the perpetual (re)formation of the urban

A MicroRNA Signature of Response to Erlotinib is Descriptive of TGFβ Behaviour in NSCLC

Our previous work identified a 13-gene miRNA signature predictive of response to the epidermal growth factor receptor (EGFR) inhibitor, erlotinib, in Non-Small Cell Lung Cancer cell lines. Bioinformatic analysis of the signature showed a functional convergence on TGFβ canonical signalling. We hypothesized that TGFβ signalling controls expression of the miRNA genes comprising an erlotinib response signature in NSCLC. Western analysis revealed that TGFβ signalling via Smad2/3/4 occurred differently between erlotinib-resistant A549 and erlotinib- sensitive PC9 cells. We showed that TGFβ induced an interaction between Smad4 and putative Smad Binding Elements in PC9. However, qRT-PCR analysis showed that endogenous miR-140/141/200c expression changes resulted from time in treatments, not the treatments themselves. Moreover, flow cytometry indicated that cells exited the cell cycle in the same manner. Taken together these data indicated that the miRNA comprising the signature are likely regulated by the cell cycle rather than by TGFβ. Importantly, this work revealed that TGFβ did not induce EMT in PC9 cells, but rather TGFβ-inhibition induced an EMT-intermediate. These data also show that growth/proliferation signals by constitutively-activated EGFR may rely on TGFβ and a possible relationship between TGFβ and EGFR signalling may prevent EMT progression in this context rather than promote it