Excimer laser fabrication of diffractive optical elements

Excimer lasers are well known for their ability to machine features on the micron scale. Recently, they have been used to fabricate diffractive optical elements (DOEs). These elements are patterns of pixels machined to the depth required, in order that a reconstructed pattern is formed in the image plane when the DOE is illuminated by a coherent source. The patterns are designed using computer phase retrieval code. These designs are used to create XY co-ordinate data files for conversion to machining routines where the pixels are machined individually. The laser used is an ArF excimer operating at 193 nm. We describe research undertaken on the fabrication and testing of some typical DOEs. The measurements include efficiency of reconstruction as well as the measurements of profile and surface roughness. The work compares the reconstruction results with the topographical measurements made on the DOE for 2, 4 and 8 phase-level designs. Newly developed simulation code was used to generate reconstructions without machining imperfections.     

Ultrasmall Integrin‐Targeted Silica Nanoparticles Modulate Signaling Events and Cellular Processes in a Concentration‐Dependent Manner

Cellular and molecular‐level interactions of nanoparticles with biological systems are a rapidly evolving field requiring an improved understanding of endocytic trafficking as the principal driver and regulator of signaling events and cellular responses. An understanding of these processes is vital to nanomedicine applications. Studies investigating the complex interplay of these processes and their relationship to targeted nanoparticles exploiting endocytic pathways are notably lacking. It is known that integrins traffic through the endosomal pathway and participate in diverse roles controlling signal transduction, cell migration, and proliferation. Here, it is shown that ultrasmall, nontoxic, core–shell silica nanoparticles (C‐dots), surface‐functionalized with cRGDY peptides, modestly activate integrin‐signaling pathways, in turn, promoting the enhancement of cellular functions. First, nanomolar concentrations, two orders of magnitude higher than clinical trial doses, internalize within αvβ3 integrin‐expressing melanoma and endothelial cells, predominantly through an integrin receptor‐dependent endocytic route. Second, integrin‐mediated activation of focal adhesion kinase (FAK) and downstream signaling pathways occurs, in turn, upregulating phosphorylated protein expression levels and promoting concentration‐dependent cellular migration and proliferative activity. Inhibiting FAK catalytic activity leads to decreased phosphorylation levels and cellular migration rates. These findings may inform the design of more effectively‐targeted nanomedicines and provide insights into endocytic regulation of signal transduction.     

Measuring the economic benefits of Saginaw Bay coastal marsh with revealed and stated preference methods

We estimate the economic benefits of Saginaw Bay coastal marsh with the travel cost and contingent valuation methods. The travel cost method is based on revealed preferences: actual recreation behavior. Using a sample of the general population of Michigan and Michigan hunting and fishing license holders we find that Saginaw Bay recreation site selection is negatively related to travel cost and positively related to wetland acreage. The contingent valuation method is based on stated preferences: answers to hypothetical survey questions. We find that willingness-to-pay is negatively related to marsh protection cost and positively related to income and environmental organization membership. Using a combination of theory and empirical results we argue that revealed and stated preference methods are complementary when estimating the total value of coastal marsh. The present value of each acre of coastal marsh is $1870 for the purpose of recreation. The present value to recreation nonusers adds $551 per acre. The total present value of each acre of coastal marsh could be as high as $2421.     

Enabling multitasking by designing for situation awareness within the vehicle environment

In the driving environment, competition exists between Driving Related Activities (DRAs) and Non-Driving Related Activities (NDRAs). This is a source of inattention and human error. Continual proliferation of in-vehicle information systems (IVIS) presents drivers with opportunities for distraction. Drivers simultaneously manage DRAs alongside unrelated but cognitively demanding NDRAs. Vehicle designers need ways of understanding human capability in such situations to provide solutions that accommodate these conflicting demands. This paper proposes a framework intended to address such challenges, rooted in the widely accepted construct of Situation Awareness (SA). However, SA theory does not presently accommodate disparate unrelated goal-driven tasks performed in parallel. This framework reconciles the present reality of drivers simultaneously devoting cognitive resources to attain SA for multiple activities by proposing a separate body of knowledge for each active goal. Additionally, the process of achieving SA is expanded to incorporate this concurrent development of separate bodies of goal-directed knowledge. The advantage of reconceptualising SA for driving allows consideration of interface design which minimises the impact of competing activities. The aim is a framework facilitating creation of IVIS that help drivers succeed in multi-goal multitasking situations. Implications of the proposed framework for theory, design and industry-driven automotive safety efforts are discussed.     

密苏里州立公园ADA指导委员会对公众参与有效性的评价

本文对美国州立公园设计过程中公众参与的有效性进行了探讨。通过国家公园密苏里分部的有关实例研究，讨论了依据《美国伤残人法》(ADA)，市民指导委员会在州立公园体系建设中的作用，以及对公众参与有效性产生影响的因素。     

ITA recommendations on contractual sharing of risks/AITES recommandations sur le partage contractuel des risques: ITA working group on contractual sharing of risks/ AITES groupe de travail partage contractuel des risques

This report summarizes two recommendations prepared by the International Tunnelling Association Working Group on Contratual Sharing of Risks. The recommendations have been officially approved by the ITA General Assembly.     

Asymmetric Communication Protocols via Hotlink Assignments

We exhibit a relationship between the asymmetric communication problem of Adler and Maggs and the hotlink assignment problem of Bose et al. By generalizing previous results on the hotlink problem and then exploiting this relationship we present a new asymmetric communication protocol with different performance bounds than previous protocols.