Hydrogen in plasma-nanofabrication : selective control of nanostructure heating and passivation

The possibility of independent control of the surface fluxes of energy and hydrogen-containing radicals, thus enabling selective control of the nanostructure heating and passivation, is demonstrated. In situ energy flux measurements reveal that even a small addition of H2 to low-pressure Ar plasmas leads to a dramatic increase in the energy deposition through H recombination on the surface. The heat release is quenched by a sequential addition of a hydrocarbon precursor while the surface passivation remains effective. Such selective control offers an effective mechanism for deterministic control of the growth shape, crystallinity, and density of nanostructures in plasma-aided nanofabrication. © 2010 American Institute of Physics.

Synthesis and characterization of ternary AL-C-N compound

Efficient hydrogenated diamond-like carbon (DLC) film deposition in a plasma reactor that features both the capacitive and inductively coupled operation regimes is reported. The hydrogenated DLC films have been prepared on silicon wafers using a low-frequency (500 kHz) inductively coupled plasma (LF ICP) chemical vapor deposition (CVD) system. At low RF powers, the system operates as an asymmetric capacitively coupled plasma source, and the film deposition process is undertaken in the electrostatic (E) discharge regime. The films deposited in the electrostatic mode feature graphite-like structure. Above the mode transition threshold, the high-density inductively coupled plasma is produced in the electromagnetic (H) discharge regime. Raman spectrometry suggests the possibility to control relative proportions of sp2 and sp3 hybridized carbon. Variation of the DC substrate bias results in dramatic modification of the film structure from the polymeric (unbiased substrates) to the diamond-like (optimized bias). It has been shown that the deposition rate and hardness of the DLC film are much higher in the H-mode deposition regime. For a 20 m Torr H-mode CH4+Ar gas mixture discharge, the DLC film exhibits mechanical hardness of 18 GPa, Young's modulus of 170 GPa, and compressive stress of 1.3 GPa.

The cultural economy in recession : Examining the US experience

Over the last two decades we have witnessed the global rise and spread of urban development policies aimed at stimulating the cultural economy. However, with the onset of the global financial crisis and recession, the cultural economy may experience a dramatic reorganization and even decline. Given the attention many cities place on the cultural sectors it is important to examine how they fare following this major economic event. To do so, this article examines the occupational distribution and geographic structure of the cultural economy in the 30 largest US metropolitan areas during recession and captures the changes that have occurred over the last decade. Based on this analysis, we identify a set of key trends, which highlight that while the boom period is generally characterized by widespread and, in some places, extreme growth in the cultural sectors, the recession is a period of selective growth and not a period of total decline. These findings have implications for determining the relevance of the arts and cultural sectors as targets of urban economic development policy in the post-recession era.

SWCNT networks on nanoporous silica catalyst support : morphological and connectivity control for nanoelectronic, gas-sensing, and biosensing devices

Effective control of morphology and electrical connectivity of networks of single-walled carbon nanotubes (SWCNTs) by using rough, nanoporous silica supports of Fe catalyst nanoparticles in catalytic chemical vapor deposition is demonstrated experimentally. The very high quality of the nanotubes is evidenced by the G-to-D Raman peak ratios (>50) within the range of the highest known ratios. Transitions from separated nanotubes on smooth SiO2 surface to densely interconnected networks on the nanoporous SiO2 are accompanied by an almost two-order of magnitude increase of the nanotube density. These transitions herald the hardly detectable onset of the nanoscale connectivity and are confirmed by the microanalysis and electrical measurements. The achieved effective nanotube interconnection leads to the dramatic, almost three-orders of magnitude decrease of the SWCNT network resistivity compared to networks of similar density produced by wet chemistry-based assembly of preformed nanotubes. The growth model, supported by multiscale, multiphase modeling of SWCNT nucleation reveals multiple constructive roles of the porous catalyst support in facilitating the catalyst saturation and SWCNT nucleation, consistent with the observed higher density of longer nanotubes. The associated mechanisms are related to the unique surface conditions (roughness, wettability, and reduced catalyst coalescence) on the porous SiO2 and the increased carbon supply through the supporting porous structure. This approach is promising for the direct integration of SWCNT networks into Si-based nanodevice platforms and multiple applications ranging from nanoelectronics and energy conversion to bio- and environmental sensing.

Absent interiors

Anuradha Mathur and Dilip da Cunha theorise in their work on cities and flooding that it is not the floodwaters that threaten lives and homes, the real cause of danger in natural disaster is the fixity of modern civilisation. Their work traces the fluidity of the boundaries between 'dry' and 'wet' land challenging the deficiencies of traditional cartography in representing the extents of bodies of water. Mathur and da Cunha propose a process of unthinking to address the redevelopment of communities in the aftermath of natural disaster. By documenting the path of floodwaters in non-Euclidean space they propose a more appropriate response to flooding. This research focuses on the documentation of flooding in the interior of dwellings, which is an extreme condition of damage by external conditions in an environment designed to protect from these very elements. Because the floodwaters don't discriminate between the interior and the exterior, they move between structures with disregard for the systems of space we have in place. With the rapid clean up that follows flood damage, little material evidence is left for post mortem examination. This is especially the case for the flood damaged interior, piles of materials susceptible to the elements, furniture, joinery and personal objects line curbsides awaiting disposal. There is a missed opportunity in examining the interior in the after math of flood, in the way that Mathur and Dilip investigate floods and the design of cities, the flooded interior proffers an undersigned interior to study. In the absence of intact flood damaged interior, this research relies on two artists' documentation of the flooded interior. The first case study is the mimetic scenographic interiors of a flood-damaged office exhibited in the Bangkok art gallery by the group _Proxy in 2011. The second case study is Robert Polidori's photographic exhibition in New Orleans, described by Julianna Preston as, 'a series of interiors undetected by satellite imaging or storm radar. More telling, more dramatic, more unnerving, more alarming, they force a disturbance of what is familiar'.

Organic non-fullerene acceptors for organic photovoltaics

Heterojunction organic photovoltaics have been the subject of intensive academic interest over the past two decades, and significant commercial efforts have been directed towards this area with the vision of developing the next generation of low-cost solar cells. Materials development has played a vital role in the dramatic improvement of organic solar cell performance in recent years, and this is driven primarily by the advancement of p-type semiconductors as donor materials. With the highest performing solar cells today dominated by acceptors based on members of the fullerene family, much less attention has been devoted to other classes of n-type acceptors. In this review, we will provide an overview of the progress in the synthesis, characterization and implementation of the various classes of non-fullerenebased n-type organic acceptors for photovoltaic applications.

Chroma Key Theatre : an examination of similarities and divergences in the use of Green Screen in two experimental theatre works

This paper examines the frame as it contributes to the debate on contemporary intermedial theatre and performance practices in light of increasing astriction between filmic and theatrical discourses. Informed by Auslander (1999), Lehmann (2006), and Giesekam (2007), and through an extrapolation of the tenets Eckersall, Gretchen and Scheer identify in the theory of New Media Dramaturgy, it will analyse two recent works of experimental theatre-making. RUFF (2013), a New York produced solo performance by one of the world’s leading female performers, explores her experiences of having a stroke. Total Dik! (2013), produced in Brisbane, Australia, is an interdisciplinary collaborative performance that examines aspects of dictatorship. They are clearly very different works yet there are a number of significant theatrical similarities in their use of Chroma Key technology and live compositing as material scenic devices. These works overtly and evocatively draw on the cinematic technique and technology of Chroma Key to augment and reveal the tensions and overlaps in their production processes.

What is the apparent angle of a Kelvin ship wave pattern?

While the half-angle which encloses a Kelvin ship wave pattern is commonly accepted to be 19.47 degrees, recent observations and calculations for sufficiently fast-moving ships suggest that the apparent wake angle decreases with ship speed. One explanation for this decrease in angle relies on the assumption that a ship cannot generate wavelengths much greater than its hull length. An alternative interpretation is that the wave pattern that is observed in practice is defined by the location of the highest peaks; for wakes created by sufficiently fast-moving objects, these highest peaks no longer lie on the outermost divergent waves, resulting in a smaller apparent angle. In this paper, we focus on the problems of free surface flow past a single submerged point source and past a submerged source doublet. In the linear version of these problems, we measure the apparent wake angle formed by the highest peaks, and observe the following three regimes: a small Froude number pattern, in which the divergent waves are not visible; standard wave patterns for which the maximum peaks occur on the outermost divergent waves; and a third regime in which the highest peaks form a V-shape with an angle much less than the Kelvin angle. For nonlinear flows, we demonstrate that nonlinearity has the effect of increasing the apparent wake angle so that some highly nonlinear solutions have apparent wake angles that are greater than Kelvin's angle. For large Froude numbers, the effect on apparent wake angle can be more dramatic, with the possibility of strong nonlinearity shifting the wave pattern from the third regime to the second. We expect our nonlinear results will translate to other more complicated flow configurations, such as flow due to a steadily moving closed body such as a submarine.

Controlling the surface roughness of epitaxial SiC on silicon

The surface of cubic silicon carbide (3C-SiC) hetero-epitaxial films grown on the (111) surface of silicon is a promising template for the subsequent epitaxial growth of III-V semiconductor layers and graphene. We investigate growth and post-growth approaches for controlling the surface roughness of epitaxial SiC to produce an optimal template. We first explore 3C-SiC growth on various degrees of offcut Si(111) substrates, although we observe that the SiC roughness tends to worsen as the degree of offcut increases. Hence we focus on post-growth approaches available on full wafers, comparing chemical mechanical polishing (CMP) and a novel plasma smoothening process. The CMP leads to a dramatic improvement, bringing the SiC surface roughness down to sub-nanometer level, though removing about 200 nm of the SiC layer. On the other hand, our proposed HCl plasma process appears very effective in smoothening selectively the sharpest surface topography, leading up to 30% improvement in SiC roughness with only about 50 nm thickness loss. We propose a simple physical model explaining the action of the plasma smoothening.

Scene signatures : localised and point-less features for localisation

This paper is about localising across extreme lighting and weather conditions. We depart from the traditional point-feature-based approach as matching under dramatic appearance changes is a brittle and hard thing. Point feature detectors are fixed and rigid procedures which pass over an image examining small, low-level structure such as corners or blobs. They apply the same criteria applied all images of all places. This paper takes a contrary view and asks what is possible if instead we learn a bespoke detector for every place. Our localisation task then turns into curating a large bank of spatially indexed detectors and we show that this yields vastly superior performance in terms of robustness in exchange for a reduced but tolerable metric precision. We present an unsupervised system that produces broad-region detectors for distinctive visual elements, called scene signatures, which can be associated across almost all appearance changes. We show, using 21km of data collected over a period of 3 months, that our system is capable of producing metric localisation estimates from night-to-day or summer-to-winter conditions.

Oncogenic BRAF induces melanoma cell invasion by downregulating the cGMP-specific phosphodiesterase PDE5A

We show that in melanoma cells oncogenic BRAF, acting through MEK and the transcription factor BRN2, downregulates the cGMP-specific phosphodiesterase PDE5A. Although PDE5A downregulation causes a small decrease in proliferation, its major impact is to stimulate a dramatic increase in melanoma cell invasion. This is because PDE5A downregulation leads to an increase in cGMP, which induces an increase in cytosolic Ca2+, stimulating increased contractility and inducing invasion. PDE5A downregulation also this leads to an increase in short-term and long-term colonization of the lungs by melanoma cells. We do not observe this pathway in NRAS mutant melanoma or BRAF mutant colorectal cells. Thus, we show that in melanoma cells oncogenic BRAF induces invasion through downregulation of PDE5A.

Metropolis: Part I–III

Video installation, Metrolpolis: Part I-III, using 1-channel HD video with surround sound. At the end of the first decade of the twenty–first century, contemporary culture appears increasingly seduced and absorbed by apocalyptic reveries. Scientists are racing to cryo-preserve genetic material from animals and plant matter in underground bunkers, while filmmakers use the spectacle of computer-generated imagery (CGI) to speculate on the outcomes from dramatic climate change, that we are not yet ready to confront in reality... Premier's new media art prize 2010: http://www.qagoma.qld.gov.au/exhibitions/past/2010/premier_of_queenslands_national_new_media_art_award_2010/chris_howlett

Structure and function of DsbA, a key bacterial oxidative folding catalyst

Since its discovery in 1991, the bacterial periplasmic oxidative folding catalyst DsbA has been the focus of intense research. Early studies addressed why it is so oxidizing and how it is maintained in its less stable oxidized state. The crystal structure of Escherichia coli DsbA (EcDsbA) revealed that the oxidizing periplasmic enzyme is a distant evolutionary cousin of the reducing cytoplasmic enzyme thioredoxin. Recent significant developments have deepened our understanding of DsbA function, mechanism, and interactions: the structure of the partner membrane protein EcDsbB, including its complex with EcDsbA, proved a landmark in the field. Studies of DsbA machineries from bacteria other than E. coli K-12 have highlighted dramatic differences from the model organism, including a striking divergence in redox parameters and surface features. Several DsbA structures have provided the first clues to its interaction with substrates, and finally, evidence for a central role of DsbA in bacterial virulence has been demonstrated in a range of organisms. Here, we review current knowledge on DsbA, a bacterial periplasmic protein that introduces disulfide bonds into diverse substrate proteins and which may one day be the target of a new class of anti-virulence drugs to treat bacterial infection. Antioxid. Redox Signal. 14, 1729–1760.

How many fake Sandy pictures were really shared on social media?

Many dramatic images of hurricane Sandy hitting the east coast of the US have been captured but which have been tweeted the most and which are real?

Institutionalization

During the 18th and 19th centuries, prostitution came to be understood as a potentially disruptive element in the management of society. New forms of social control developed that sought to transform the souls of prostitutes to better control their bodies. Institutions for managing prostitutes, such as Magdalen Homes and lock hospitals, were introduced or increased in number throughout the British Empire, North America, and Western Europe. Often these institutions had as their stated objective the physical purification and moral reform of prostitutes, appearing to make a dramatic break with earlier methods of social control that had relied on practices of physical punishment and spatial segregation. Emergent institutions for the social control of prostitutes used a regimen of religious training, hard labor, and medical expertise. The objective of the Magdalen Home was not to punish sin but to absolve it, while the function of the lock hospital was not simply to confine the ill, but to confine the ill to "cure" them. The role of these institutions was not only symbolic, mirroring in some way the operation of earlier forms of social control, but was also practical and transformative. The mass institutionalization of prostitutes that occurred during the 18th and 19th centuries produced and emphasized sexual, class, and gender boundaries, grounded in the broad distinction between "pure" and "impure" women. Because of its association with sin, prostitution before the 18th century had been constructed as a religious problem relating to salvation and penitence. Throughout Western Europe during the Middle Ages, prostitutes, like the medieval leper and the Jew, were subject to restrictions designed to distinguish and isolate them from other members of their communities. The repression of prostitution during the Middle Ages was neither systematic nor highly organized, although it reinforced the image of the prostitute as sinful "other".