Helminths in the hygiene hypothesis:Sooner or later?

There is increasing recognition that exposures to infectious agents evoke fundamental effects on the development and behaviour of the immune system. Moreover, where infections (especially parasitic infections) have declined, immune responses appear to be increasingly prone to hyperactivity. For example, epidemiological studies of parasite-endemic areas indicate that prenatal or early-life experience of infections can imprint an individual's immunological reactivity. However, the ability of helminths to dampen pathology in established inflammatory diseases implies that they can have therapeutic effects even if the immune system has developed in a low-infection setting. With recent investigations of how parasites are able to modulate host immune pathology at the level of individual parasite molecules and host cell populations, we are now able to dissect the nature of the host–parasite interaction at both the initiation and recall phases of the immune response. Thus the question remains – is the influence of parasites on immunity one that acts primarily in early life, and at initiation of the immune response, or in adulthood and when recall responses occur? In short, parasite immunosuppression – sooner or later

Transcritical shallow-water flow past topography: finite-amplitude theory

We consider shallow-water flow past a broad bottom ridge, localized in the flow direction, using the framework of the forced SuGardner (SG) system of equations, with a primary focus on the transcritical regime when the Froude number of the oncoming flow is close to unity. These equations are an asymptotic long-wave approximation of the full Euler system, obtained without a simultaneous expansion in the wave amplitude, and hence are expected to be superior to the usual weakly nonlinear Boussinesq-type models in reproducing the quantitative features of fully nonlinear shallow-water flows. A combination of the local transcritical hydraulic solution over the localized topography, which produces upstream and downstream hydraulic jumps, and unsteady undular bore solutions describing the resolution of these hydraulic jumps, is used to describe various flow regimes depending on the combination of the topography height and the Froude number. We take advantage of the recently developed modulation theory of SG undular bores to derive the main parameters of transcritical fully nonlinear shallow-water flow, such as the leading solitary wave amplitudes for the upstream and downstream undular bores, the speeds of the undular bores edges and the drag force. Our results confirm that most of the features of the previously developed description in the framework of the unidirectional forced Kortewegde Vries (KdV) model hold up qualitatively for finite amplitude waves, while the quantitative description can be obtained in the framework of the bidirectional forced SG system. Our analytic solutions agree with numerical simulations of the forced SG equations within the range of applicability of these equations

The constitution of supply chain relationships: A post-failure case study

This study aims to investigate how relationships between main contractors and second-tier subcontractors are constituted, particularly after project experiences that deteriorated relationships. Trust is regarded as a structural property of relationship and the duality of trust provides an analytical perspective of investigating the constitution of relationship. This process-based research used case study method and collected data from semi-structured interviews with actors from both main contractor and subcontractor companies. Findings reveal five processes, learning, relating, collaborating, controlling and routinising, that helped constitute trust and thus supply chain relationships. It reveals that relationship failure had strong impacts on initial trust and practices at the front end. The research also shows that constituting relationship and trust is an intended but also an unintended consequence of project organising enabled and constrained by structures of project ecologies. This study contributes to knowledge in that it 1) provides an analytical approach, from the perspective of structuration theory, and relational approach to understanding construction supply chains, 2) empirically demonstrates the dynamics of trust, in the shadow of the past as well as contemporary lifecycle of the construction project, and 3) links construction project management field with the wider field of social science

Multiresolution pattern recognition of small volcanos in Magellan data

The Magellan data is a treasure-trove for scientific analysis of venusian geology, providing far more detail than was previously available from Pioneer Venus, Venera 15/16, or ground-based radar observations. However, at this point, planetary scientists are being overwhelmed by the sheer quantities of data collected--data analysis technology has not kept pace with our ability to collect and store it. In particular, 'small-shield' volcanos (less than 20 km in diameter) are the most abundant visible geologic feature on the planet. It is estimated, based on extrapolating from previous studies and knowledge of the underlying geologic processes, that there should be on the order of 10(exp 5) to 10(exp 6) of these volcanos visible in the Magellan data. Identifying and studying these volcanos is fundamental to a proper understanding of the geologic evolution of Venus. However, locating and parameterizing them in a manual manner is very time-consuming. Hence, we have undertaken the development of techniques to partially automate this task. The goal is not the unrealistic one of total automation, but rather the development of a useful tool to aid the project scientists. The primary constraints for this particular problem are as follows: (1) the method must be reasonably robust; and (2) the method must be reasonably fast. Unlike most geological features, the small volcanos of Venus can be ascribed to a basic process that produces features with a short list of readily defined characteristics differing significantly from other surface features on Venus. For pattern recognition purposes the relevant criteria include the following: (1) a circular planimetric outline; (2) known diameter frequency distribution from preliminary studies; (3) a limited number of basic morphological shapes; and (4) the common occurrence of a single, circular summit pit at the center of the edifice

Cultivating a ‘just’ culture in construction industry to improve Health and Safety management systems

Within the last decades,safety statistics in the UK construction industry have reached a plateau and cultural changes are required for further improvement of occupational health and safety (H&S) management systems. The aim of this research is to understand how the UK construction industry can improve H&S reporting to learn from failures and near misses based on experience of aviation and aerospace industries that made a successful shift from a ‘blame’ to a ‘just’ culture. The reason is that H&S culture remains undeveloped within the industry. Cultivation of a culture that can facilitate bottom-up reporting and learning from failures and near misses is difficult due to fragmented nature and the complexity of construction programme and project operations. The industry that is criticised for being inward looking and slow in learning could benefit from safety practices of other safety-critical industries, rather than take a position of its uniqueness. An interpretative methodology is applied in this research. Thematic analysis is supported by cognitive mapping technique. The findings revealed that H&S practices in the construction industry are affected by the lack of consistency across construction sites due to fragmented supply chain, ‘silo’ project culture and a tendency to blame individuals for human error. The levels of engagement with bottom-up reporting are quite low and the most frequently mentioned reasons are transactional approach to H&S by the management, figure-pointing behaviours, lack of robust follow-up processes and lack of trust. H&S regulations, norms and guidelines do not include all possible safety issues specific to unique project environments. Cultivation of a ‘just’ culture could help the industry to go beyond H&S legal compliance and change attitude to safety reporting. Despite the differences, construction organisations can learn from aviation and aerospace industries’ accountability for the systems they design and from their proactive approaches to dealing with human error and encouraging and facilitating self-reporting

On Certain Kähler Quotients of Quaternionic Kähler Manifolds

We prove that, given a certain isometric action of a two-dimensional Abelian group A on a quaternionic Kähler manifold M which preserves a submanifold N ⊂ M, the quotient M′ =N/A has a natural Kähler structure. We verify that the assumptions on the group action and on the submanifold N ⊂ M are satisfied for a large class of examples obtained from the supergravity c-map. In particular, we find that all quaternionic Kähler manifolds M in the image of the c-map admit an integrable complex structure compatible with the quaternionic structure, such that N ⊂ M is a complex submanifold. Finally, we discuss how the existence of the Kähler structure on M′ is required by the consistency of spontaneous $${\mathcal{N} = 2}$$ to $${\mathcal{N} = 1}$$ supersymmetry breakin

Interação de micorriza vesicular-arbuscular com leguminosas em solos ácidos.

Este trabalho apresenta uma abordagem para MVA e acidez do solo; Simbiose MVA ? Rhizobium-leguminosa; Dependência de MVA e Micorrizas e pesquisa na região amazônica.bitstream/item/60903/1/Doc55-micorrizaarbuscular.pd