Variation in host susceptibility and infectiousness generated by co-infection: the myxoma-Trichostrongylus retortaeformis case in wild rabbits.

One of the conditions that can affect host susceptibility and parasite transmission is the occurrence of concomitant infections. Parasites interact directly or indirectly within an individual host and often these interactions are modulated by the host immune response. We used a free-living rabbit population co-infected with the nematode Trichostrongylus retortaeformis, which appears to stimulate an acquired immune response, and the immunosuppressive poxvirus myxoma. Modelling was used to examine how myxoma infection alters the immune-mediated establishment and death/expulsion of T. retortaeformis, and consequently affects parasite intensity and duration of the infection. Simulations were based on the general TH1-TH2 immunological paradigm that proposes the polarization of the host immune response towards one of the two subsets of T helper cells. Our findings suggest that myxoma infections contribute to alter host susceptibility to the nematode, as co-infected rabbits showed higher worm intensity compared with virus negative hosts. Results also suggest that myxoma disrupts the ability of the host to clear T. retortaeformis as worm intensities were consistently high and remained high in old rabbits. However, the co-infection model has to include some immune-mediated nematode regulation to be consistent with field data, indicating that the TH1-TH2 dichotomy is not complete. We conclude that seasonal myxoma outbreaks enhance host susceptibility to the nematode and generate highly infected hosts that remain infectious for a longer time. Finally, the virus-nematode co-infection increases heterogeneities among individuals and potentially has a large effect on parasite transmission.     

Usage of SoS methodologies in production system design

Production systems design is a multifaceted task, due to a variety of aspects such as the mutual interdependency between the sub-systems, the variety of configurations and alternative system control strategies, the multiple managerial and “soft” aspects that cast an influence on the behavior of the system. A reasonable number of modeling tools can be applied to production system design, but they tend to divide the problem into unconnected sub-problems whose individual solutions may result in a poor global one. This is despite the fact that production design encompasses all aspects of manufacturing operations, and needs a systemic approach, as clearly shown in practitioner-oriented literature. This paper proposes to apply the “System of Systems” approach to production system design in order to represent their main aspects and support the rational definition of the path leading from corporate strategy to system (re)design.     

Role of Nitrate Species in the “NO2-SCR” Mechanism over a Commercial Fe-zeolite Catalyst for SCR Mobile Applications

The NO₂-SCR reaction is studied by transient reaction analysis over a Fe-zeolite commercial catalyst. It is proposed that the NO₂-SCR reaction occurs according to a mechanism wherein surface nitrates are first formed by NO₂ disproportionation, followed by their catalytic reduction to nitrogen by ammonia.     

Method for stakeholder identification in interorganizational environments

Stakeholders are the first emerging challenge in any software project. Their identification is a critical task for success. Nevertheless, many authors consider them as a default product of a non-explained identification process. Several aspects must be considered when the project is carried out in environments where multiple organizations interact. These complex contexts demand extremely hard efforts. Stakeholders must be identified taking into account their attributes (types, roles), which must be extended and defined for these environments. In general, there are no methodologies that allow performing this task in a systematic way for the development of interorganizational information systems. The paper proposes a method for carrying out stakeholder identification considering the diverse dimensions involved in interorganizational environments: organizational, interorganizational and external. It allows the systematic specification of all the people, groups and organizations whose interests and needs can affect or are affected by the interorganizational system. Also diverse stakeholders’ attributes such as types, roles, influence and interest are defined, analyzed, and included in the method. They are all important in later stages of any software project.     

Fluorescence line narrowing study of Cr ions in cordierite glass nucleating MgAl2O4 nanocrystals

The luminescence of Cr³⁺ ions in cordierite glass nucleating MgAl₂O₄ nanocrystallites has been investigated. The time resolved fluorescence line narrowing measurements and the temperature dependence of the homogeneous line width show that most Cr³⁺ ions are inside the nanocrystallites. Cr³⁺ ions occupy non-equivalent crystal sites, due to the Mg²⁺–Al³⁺ inversion effect. The values of the homogeneous line width compare well with those of previous studies in crystals. No surface effect has been observed due to the large size of the crystals.     

Using PV and QV curves with the meaning of static contingency screening and planning

This paper investigates the use of the QV and PV curves in the planning scenario, when some system reinforcements and contingency screening are analyzed. The idea is to employ the continuation method to obtain the system load margin and the QV curve to calculate the reactive power reserve associated with each bus. Combining these approaches enables one to identify the system critical area, the actual operating conditions, the most severe contingencies and the most important reinforcements. The methodology proposed may provide important signals to system planners, since the planning is focused under the voltage security point of view. The ideas are tested with the help of some academic systems and two real (a Brazilians and a Paraguayan) systems with all the system limits considered.     

Single thermoplastic pellet molding by means of diode laser for micromolding application

An innovative system for thermoplastic micromolding is presented. A completely transparent mold is used, and a diode laser is used as heating source. Laser heating is performed on a single thermoplastic pellet positioned inside the mold between two glass plates. A very low force is necessary for shaping. Molding tests were performed on commercial ABS and several process parameters were investigated such as laser power, interaction time, focalization condition, and support material properties. High pellet formability was observed in all the cases. Using nontransparent pellet supports it is possible to increase molding efficiency even if the risk of polymer degradation increases. A master curve can be fabricated for molding test results providing a correct comparison among the different process conditions. POLYM. ENG. SCI., 47:168–173, 2007. © 2007 Society of Plastics Engineers     

Pathogenic Mutations Shift the Equilibria of α‐Synuclein Single Molecules towards Structured Conformers

α‐synuclein (α‐Syn) is an abundant brain protein whose mutations have been linked to early‐onset Parkinson's disease (PD). We recently demonstrated, by means of a single‐molecule force spectroscopy (SMFS) methodology, that the conformational equilibrium of monomeric wild‐type (WT) α‐Syn shifts toward β‐containing structures in several unrelated conditions linked to PD pathogenicity. Herein, we follow the same methodology previously employed for WT α‐Syn to characterize the conformational heterogeneity of pathological α‐Syn mutants A30P, A53T, and E46K. Contrary to the bulk ensemble‐averaged spectroscopies so far employed to this end by different authors, our single‐molecule methodology monitored marked differences in the conformational behaviors of the mutants with respect to the WT sequence. We found that all the mutants have a much higher propensity than the WT to adopt a monomeric compact conformation that is compatible with the acquiring of β structure. Mutants A30P and A53T show a similar conformational equilibrium that is significantly different from that of E46K. Another class of conformations, stabilized by mechanically weak interactions (MWI), shows a higher variety in the mutants than in the WT protein. In the A30P mutant these interactions are relatively stronger, and therefore the corresponding conformations are possibly more structured. The more structured and globular conformations of the mutants can explain their higher propensity to aggregate with respect to the WT.