New integrated buried laser-ridge modulator with identical active layer

Integrated laser modulators are attractive devices for wavelength-division-multiplexing optical systems due to their compactness, high output power, and low cost. Their fabrication simplicity is a way to decrease further the transmitter cost and address new opening markets of short range and metropolitan networks. We report a new integration scheme electroabsorption-modulator distributed feedback (DFB) laser based on well-established industrial solutions for discrete buried ridge (BRS) DFB lasers and discrete shallow ridge modulators. Processing simplification with an identical active layer has been possible due to a good behavior of strongly positively detuned BRS lasers. The integrated devices demonstrated 30-dB extinction ratio with 10-GHz bandwidth and P/sub out/=10 dBm for emission in 1.55-/spl mu/m range.     

Pedestrian Reactive Navigation for Crowd Simulation: a Predictive Approach

This paper addresses the problem of virtual pedestrian autonomous navigation for crowd simulation. It describes a method for solving interactions between pedestrians and avoiding inter-collisions. Our approach is agent-based and predictive: each agent perceives surrounding agents and extrapolates their trajectory in order to react to potential collisions. We aim at obtaining realistic results, thus the proposed model is calibrated from experimental motion capture data. Our method is shown to be valid and solves major drawbacks compared to previous approaches such as oscillations due to a lack of anticipation. We first describe the mathematical representation used in our model, we then detail its implementation, and finally, its calibration and validation from real data.     

Thermodynamic equations of state for hydrazine and monomethylhydrazine

Thermodynamic equations of state are evaluated for the aerospace fuels hydrazine and monomethylhydrazine using Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) formulations. The PR formulation is shown to be the best fit for hydrazine, and the SRK formulation to be the best fit for monomethylhydrazine, based on available critical property data and evaluations of thermodynamic consistency. The adequacy of the differing property data for these fuels in the literature is discussed, and the methodology used to validate the formulations is outlined. The importance of using appropriate real fluid equations of state in thermodynamic safety and hazards analysis of fuel systems is demonstrated by considering an adiabatic compression of gaseous fuels previously postulated in accident scenarios of aerospace propulsion systems. Calculation of isentropic compression temperatures for pure components using ideal gas constant heat capacity, ideal gas with variable heat capacity, and real fluid equations of state are compared to illustrate the need for real fluid equations of state. In addition, three separate approaches are used for estimating isentropic compression temperatures for mixtures involving these fuels, again illustrating the importance of treating these mixtures as real fluids for design and safety analysis.     

Interactive quadrangulation with Reeb atlases and connectivity textures

Creating high-quality quad meshes from triangulated surfaces is a highly nontrivial task that necessitates consideration of various application specific metrics of quality. In our work, we follow the premise that automatic reconstruction techniques may not generate outputs meeting all the subjective quality expectations of the user. Instead, we put the user at the center of the process by providing a flexible, interactive approach to quadrangulation design. By combining scalar field topology and combinatorial connectivity techniques, we present a new framework, following a coarse to fine design philosophy, which allows for explicit control of the subjective quality criteria on the output quad mesh, at interactive rates. Our quadrangulation framework uses the new notion of Reeb atlas editing, to define with a small amount of interactions a coarse quadrangulation of the model, capturing the main features of the shape, with user prescribed extraordinary vertices and alignment. Fine grain tuning is easily achieved with the notion of connectivity texturing, which allows for additional extraordinary vertices specification and explicit feature alignment, to capture the high-frequency geometries. Experiments demonstrate the interactivity and flexibility of our approach, as well as its ability to generate quad meshes of arbitrary resolution with high-quality statistics, while meeting the user’s own subjective requirements.     

Hyperhomocysteinemia and Cardiovascular Disease: Is the Adenosinergic System the Missing Link?

The influence of hyperhomocysteinemia (HHCy) on cardiovascular disease (CVD) remains unclear. HHCy is associated with inflammation and atherosclerosis, and it is an independent risk factor for CVD, stroke and myocardial infarction. However, homocysteine (HCy)-lowering therapy does not affect the inflammatory state of CVD patients, and it has little influence on cardiovascular risk. The HCy degradation product hydrogen sulfide (H₂S) is a cardioprotector. Previous research proposed a positive role of H₂S in the cardiovascular system, and we discuss some recent data suggesting that HHCy worsens CVD by increasing the production of H₂S, which decreases the expression of adenosine A_2A receptors on the surface of immune and cardiovascular cells to cause inflammation and ischemia, respectively.     

Complement-Opsonized Nano-Carriers Are Bound by Dendritic Cells (DC) via Complement Receptor (CR)3, and by B Cell Subpopulations via CR-1/2, and Affect the Activation of DC and B-1 Cells

The development of nanocarriers (NC) for biomedical applications has gained large interest due to their potential to co-deliver drugs in a cell-type-targeting manner. However, depending on their surface characteristics, NC accumulate serum factors, termed protein corona, which may affect their cellular binding. We have previously shown that NC coated with carbohydrates to enable biocompatibility triggered the lectin-dependent complement pathway, resulting in enhanced binding to B cells via complement receptor (CR)1/2. Here we show that such NC also engaged all types of splenic leukocytes known to express CR3 at a high rate when NC were pre-incubated with native mouse serum resulting in complement opsonization. By focusing on dendritic cells (DC) as an important antigen-presenting cell type, we show that CR3 was essential for binding/uptake of complement-opsonized NC, whereas CR4, which in mouse is specifically expressed by DC, played no role. Further, a minor B cell subpopulation (B-1), which is important for first-line pathogen responses, and co-expressed CR1/2 and CR3, in general, engaged NC to a much higher extent than normal B cells. Here, we identified CR-1/2 as necessary for binding of complement-opsonized NC, whereas CR3 was dispensable. Interestingly, the binding of complement-opsonized NC to both DC and B-1 cells affected the expression of activation markers. Our findings may have important implications for the design of nano-vaccines against infectious diseases, which codeliver pathogen-specific protein antigen and adjuvant, aimed to induce a broad adaptive cellular and humoral immune response by inducing cytotoxic T lymphocytes that kill infected cells and pathogen-neutralizing antibodies, respectively. Decoration of nano-vaccines either with carbohydrates to trigger complement activation in vivo or with active complement may result in concomitant targeting of DC and B cells and thereby may strongly enhance the extent of dual cellular/humoral immune responses.     

PGRP-LB: An Inside View into the Mechanism of the Amidase Reaction

Peptidoglycan recognition proteins (PGRPs) are ubiquitous among animals and play pivotal functions in insect immunity. Non-catalytic PGRPs are involved in the activation of immune pathways by binding to the peptidoglycan (PGN), whereas amidase PGRPs are capable of cleaving the PGN into non-immunogenic compounds. Drosophila PGRP-LB belongs to the amidase PGRPs and downregulates the immune deficiency (IMD) pathway by cleaving meso-2,6-diaminopimelic (meso-DAP or DAP)-type PGN. While the recognition process is well analyzed for the non-catalytic PGRPs, little is known about the enzymatic mechanism for the amidase PGRPs, despite their essential function in immune homeostasis. Here, we analyzed the specific activity of different isoforms of Drosophila PGRP-LB towards various PGN substrates to understand their specificity and role in Drosophila immunity. We show that these isoforms have similar activity towards the different compounds. To analyze the mechanism of the amidase activity, we performed site directed mutagenesis and solved the X-ray structures of wild-type Drosophila PGRP-LB and its mutants, with one of these structures presenting a protein complexed with the tracheal cytotoxin (TCT), a muropeptide derived from the PGN. Only the Y78F mutation abolished the PGN cleavage while other mutations reduced the activity solely. Together, our findings suggest the dynamic role of the residue Y78 in the amidase mechanism by nucleophilic attack through a water molecule to the carbonyl group of the amide function destabilized by Zn²⁺.     

The influence of demineralisation and ammoxidation on the adsorption properties of an activated carbon prepared from a Polish lignite

The preparation of cheap nitrogen-enriched materials with large adsorptive capacities and selectivity towards volatile organic compounds remains a challenge. Ammoxidation has been used to prepare nitrogen-enriched activated carbons using a demineralised Polish lignite. The lignite samples were demineralised by two different methods before nitrogen-enrichment by ammoxidation and physical activation in steam. The surface chemistry was investigated by elemental analysis, Boehm titration, infrared and XPS spectroscopies and adsorptive properties by a linear solvation energy relationship approach. Results show a quasi-total demineralisation and a higher reactivity towards nitrogen for the demineralised samples. The BET surface is also higher than for the non-demineralised lignite. Active carbons previously ammoxidated and demineralised are more interesting in terms of selective removal of gaseous pollutants.     

A 3D analysis of the joint torques developed during driver's ingress–egress motion

Providing an easy ingress–egress (I/E) movement remains a challenge for car designers. I/E has been largely studied in kinematics, but not in dynamics. This study proposes: (1) to evaluate and describe the motor torques developed in the lower limbs and lumbar joints during I/E motions and (2) to analyse the influence of the car geometry and subject anthropometry. An experiment was performed to observe 15 subjects of three anthropometrical groups getting in and out of a car mock-up simulating three different vehicle configurations. Motor torques were extracted using an inverse dynamics analysis. Both ingress and egress motions were primarily characterised by large torques. Overall, the taller a subject and the lower the seat of the vehicle were, the larger the peak torques were. Moreover, peak torques were higher for egress than ingress. These results are discussed in regard to the current knowledge on I/E ergonomics.     

Copolymerization of norbornene with norbornene terminated polystyrene macromonomer in the presence of Ni-based/MAO catalytic systems

Copolymerization of -norbornenyl polystyrene macromonomer (NBE-PS) with norbornene (NBE) using Ni-based catalysts in combination with methylaluminoxane (MAO) was investigated. The nature of the catalyst, the of the polystyrene macromonomer as well as the [NBE-PS]/[NBE] ratio have been shown to be important parameters to obtain graft copolymers with high NBE-PS incorporation (up to 43 wt%). The compatibilization ability of these graft copolymers has been checked for PS/PNBE blends. The length of the grafts was proved not to be an important parameter to consider compatibilization of the PS/PNBE blend.