Polarization state of the optical near-field

The polarization state of the optical electromagnetic field lying several nanometers above complex dielectric structures reveals the intricate light-matter interaction that occurs in this near-field zone. This information can only be extracted from an analysis of the polarization state of the detected light in the near-field. These polarization states can be calculated by different numerical methods well-suited to near--field optics. In this paper, we apply two different techniques (Localized Green Function Method and Differential Theory of Gratings) to separate each polarisation component associated with both electric and magnetic optical near-fields produced by nanometer sized objects. The analysis is carried out in two stages: in the first stage, we use a simple dipolar model to achieve insight into the physical origin of the near-field polarization state. In the second stage, we calculate accurate numerical field maps, simulating experimental near-field light detection, to supplement the data produced by analytical models. We conclude this study by demonstrating the role played by the near-field polarization in the formation of the local density of states.Comment: 9 pages, 11 figures, accepted for publication in Phys. Rev.

Modern rhodolith-dominated carbonates at Punta Chivato, Mexico

Rhodolith-dominated carbonate environments, characterized by high abundances of free-living coralline algae, have been described globally from a wide range of Recent and fossil shallow marine settings. In the present-day warm-temperate Gulf of California, Mexico, rhodolith-dominated systems are important contributors to carbonate production. One of the most prolific rhodolith factories is located on the Punta Chivato shelf, in the central Gulf of California, where due to a lack of input of terrigenous material from the arid hinterland, carbonate content averages 79%. Punta Chivato rhodoliths thrive above the shallow euphotic zone under normal saline, warm-temperate and meso- to eutrophic conditions. A detailed sedimentologic study combined with acoustic seafloor mapping indicates the presence of extensive rhodolith-dominated facies at subtidal water depth covering an area of \u3e17 km2. Additional facies, surrounding the rhodolith-dominated facies include a fine-grained molluscan, a transitional bivalve-rhodolith and a bivalve facies. While the Punta Chivato shelf yields average abundances of 38% rhodolith-derived coralline algal components in the gravel-sized sediment fraction, the rhodolith facies itself is characterized by more than 60% coralline algal components. Other important carbonate producers at Punta Chivato include bivalves (35%), bryozoa (11%) and gastropods (8%). The present study shows that acoustic sediment mapping yields highly resolved continuous coverage of the seafloor and can distinguish modern rhodolith facies from surrounding sediment. This has important implications for quantifying rhodolith-dominated settings globally, as well as for ecological and conservation studies. © Publications Scientifiques du Muséum national d\u27Histoire naturelle, Paris

The open innovation research landscape: established perspectives and emerging themes across different levels of analysis

This paper provides an overview of the main perspectives and themes emerging in research on open innovation (OI). The paper is the result of a collaborative process among several OI scholars – having a common basis in the recurrent Professional Development Workshop on ‘Researching Open Innovation’ at the Annual Meeting of the Academy of Management. In this paper, we present opportunities for future research on OI, organised at different levels of analysis. We discuss some of the contingencies at these different levels, and argue that future research needs to study OI – originally an organisational-level phenomenon – across multiple levels of analysis. While our integrative framework allows comparing, contrasting and integrating various perspectives at different levels of analysis, further theorising will be needed to advance OI research. On this basis, we propose some new research categories as well as questions for future research – particularly those that span across research domains that have so far developed in isolation

Recurrent Signature Patterns in HIV-1 B Clade Envelope Glycoproteins Associated with either Early or Chronic Infections

Here we have identified HIV-1 B clade Envelope (Env) amino acid signatures from early in infection that may be favored at transmission, as well as patterns of recurrent mutation in chronic infection that may reflect common pathways of immune evasion. To accomplish this, we compared thousands of sequences derived by single genome amplification from several hundred individuals that were sampled either early in infection or were chronically infected. Samples were divided at the outset into hypothesis-forming and validation sets, and we used phylogenetically corrected statistical strategies to identify signatures, systematically scanning all of Env. Signatures included single amino acids, glycosylation motifs, and multi-site patterns based on functional or structural groupings of amino acids. We identified signatures near the CCR5 co-receptor-binding region, near the CD4 binding site, and in the signal peptide and cytoplasmic domain, which may influence Env expression and processing. Two signatures patterns associated with transmission were particularly interesting. The first was the most statistically robust signature, located in position 12 in the signal peptide. The second was the loss of an N-linked glycosylation site at positions 413–415; the presence of this site has been recently found to be associated with escape from potent and broad neutralizing antibodies, consistent with enabling a common pathway for immune escape during chronic infection. Its recurrent loss in early infection suggests it may impact fitness at the time of transmission or during early viral expansion. The signature patterns we identified implicate Env expression levels in selection at viral transmission or in early expansion, and suggest that immune evasion patterns that recur in many individuals during chronic infection when antibodies are present can be selected against when the infection is being established prior to the adaptive immune response

A Redesigned Engagement and Recruitment Strategy forEngineering Technology Programs at a Regional Campus

While enrollment in engineering programs is generally strong nationwide, maintaining or increasing enrollment in Engineering Technology programs at smaller regional campuses can be challenging. The problem appears to be multi-faceted, with the rising cost of education and a strong regional job market two of the likely factors that are keeping students from pursuing a college education. This paper presents a summary of the initial work done at a Statewide location of a large national university to redesign how we engage and recruit students from our surrounding counties. Our eventual goal in redesigning the processes is to leverage our ability to connect directly with local high schools, prospective students, and the parents of prospective students. In the paper, we briefly describe our prior recruitment activities, provide an overview of our newly-developed recruitment model and the philosophy that underpins our redesigned strategy for outreach and recruitment as a whole, and present an initial review of data that are being collected for assessing the effectiveness of our efforts. The central element of this initial work is the redesigned recruitment event aimed at helping us better connect with prospective students. The event emphasizes the importance of campus visits by local high school students, informative hands-on activities, and relationship-building with local high school staff and administrators. The goal of this initial work is to test the approach of direct engagement and to gauge interest in our programs, our location, and overall interest in attending college for the students who participate in the events. This initial assessment will in turn inform us how to continue to improve the overall strategy over the next two to four years

The COral-REef Front (COREF) Project

The First International Workshop on the COral-REef Front (COREF) project was held on 14−19 January 2007 in Okinawa-jima, southwestern Japan to discuss objectives, required laboratory analyses and techniques, potential drilling sites, and scientific proposals for the Integrated Ocean Drilling Program (IODP) and the International Continental Scientific Drilling Program (ICDP). This article briefly introduces the project and reports the outcome of the First International Workshop on the COREF Project

In vitro cell compatibility study of rose bengal-chitosan adhesives

Background and Objectives: Photochemical tissue bonding (PTB) using rose bengal (RB) in conjunction with light is an alternative technique to repair tissue without suturing. It was recently demonstrated that laser-irradiated chitosan films, incorporating RB, bonded firmly to calf intestine in vitro. It is thus required to investigate the possible cytotoxic effects of the RB-chitosan adhesive on cells before testing its application to in vivo models. Materials and Methods: Adhesive films, based on chitosan and containing ~0.1 wt% RB were fabricated. Their cytotoxicity was assessed by growing human and murine fibroblasts either in media in which adhesive strips had been incubated, or directly on the adhesive. The adhesive was either laser-irradiated or not. Cells were stained after 48 hours with Trypan blue and the number of live and dead cells was recorded for cell viability. Results: Murine and human fibroblasts grew confluent on the adhesives with no apparent morphological changes or any exclusion zone. Cell numbers of murine fibroblasts were not significantly different when cultured in media that was extracted from irradiated (86 ± 7%) and non-irradiated adhesive (89 ± 4%). A similar result was obtained for the human fibroblasts. Conclusions: These findings support that the RB-chitosan films induced negligible toxicity and growth retardation in murine and human fibroblasts