The mucosal cellular response to infection with Ancylostoma ceylanicum

Although hookworms are known to stimulate inflammatory responses in the intestinal mucosa of their hosts, there is little quantitative data on this aspect of infection. Here we report the results of experiments conducted in hamsters infected with Ancylostoma ceylanicum. Infection resulted in a marked increase in goblet cells in the intestinal mucosa, which was dependent on the number of adult worms present and was sustained as long as worms persisted (over 63 days) but returned to baseline levels within 7 days of the removal of worms by treatment with ivermectin. Increased mast cell responses were also recorded. Levels were again dependent on the intensity of worm burdens and lasted as long as 63 days after infection. When worms were eliminated, mast cell numbers took over 2 weeks to return to normal. Paneth cell numbers fell soon after infection, the degree of reduction being dependent on the worm burden. After clearance of worms, Paneth cell numbers returned to normal within a week, but then rebounded and numbers rose to higher levels than those in control naıve animals. The time course of the response was similar whether animals experienced a chronic low-intensity infection without loss of worms or a higher intensity infection during the course of which worm burdens were gradually reduced. Clearly, A. ceylanicum was able to induce a marked inflammatory response in its host’s intestine which was sustained for over 9 weeks after infection, and which hamsters appeared able to tolerate well. Our data draw attention to the resilience of hookworms which, unlike many other nematodes, are able to survive for many weeks in a highly inflamed intestinal tract

Space – time Kalman filtering of soil redistribution + erratum

Soil redistribution is the net result of erosion and sedimentation. Assessment of soil redistribution in a given landscape over a given period of time may be done using process-based and empirical approaches. Process-based approaches rely on knowledge of how environmental processes acting in the landscape cause soil to move from one place to another. Empirical approaches rely on measurements of soil redistribution, which may be interpolated in space and time using (geo)statistical methods. In this paper we use space¿time Kalman filtering to combine these two basic approaches. The Kalman filter operates recursively to predict forward one step at a time the soil redistribution from the predicted soil redistribution at the previous time and the measurements at the current time. The methodology is illustrated with a case study from a seven hectare segment site, located on the hummocky till plains of Saskatchewan, Canada. Tillage erosion causes soil to move downward along the steepest gradient, whereby the amount of soil loss per year is assumed linearly related to slope angle. Measurements of cumulative soil redistribution from 1963 to 2000 were derived using Cesium-137 as a tracer. In total 99 measurements were taken, using a regular sampling design with a grid mesh of 25 m. The soil redistribution measurements differed meaningfully from the deterministic model predictions (R2 = 0.389), causing the Kalman filter to make a marked adjustment to the soil redistribution map. The adjustment was particularly strong along the transportation route near the measurement locations. Use of the space¿time Kalman filter to predict soil redistribution is attractive because it makes optimum use of process knowledge and measurements, but routine use of the technique is hampered by the computational load and by parameterisation problems. Sensitivity analyses showed that the model results are most sensitive to the system noise. Future research must therefore be directed to realistic assessment of the errors inflicted by the assumptions and simplifications of the soil redistribution mode

Site assessment of multiple sensor approaches for buried utility detection

The successful operation and maintenance of buried infrastructure within urban environments is fundamental to the conservation of modern living standards. Breakdown in supply of utilities is quickly noticed and requires a swift response to repair the network. Open-cut methods are predominantly used, in preference to trenchless technology, to effect a repair, or replace or install a new section of the network. This is, in part, due to the inability to determine the position of all utilities below the carriageway, making open-cut methods desirable in terms of dealing with uncertainty since the buried infrastructure is progressively exposed during excavation. However, open cut methods damage the carriageway and disrupt society’s functions. This paper describes the progress of a research project that aims to develop a multi-sensor geophysical platform that can improve the probability of complete detection of the infrastructure buried beneath the carriageway. The multi-sensor platform is being developed in conjunction with a knowledge-based system that aims to provide information on how the properties of the ground might affect the sensing technologies being deployed. The fusion of data sources (sensor data and utilities record data) is also being researched to maximise the probability of location. The project has reached a stage where the majority of the sensing technologies being developed for the multi-sensor device have undergone initial testing on site and this has shown some interesting findings. This paper describes the outcome of the initial phase of testing along with the development of the knowledge-based system and the fusing of data to produce utility map

Self-Organizing Referral Networks: A Process View of Trust and Authority

Abstract. We are developing a decentralized approach to trust based on referral systems, where agents adaptively give referrals to one another to find other trustworthy agents. Interestingly, referral systems provide us with a useful and intuitive model of how links may be generated: a referral corresponds to a customized link generated on demand by one agent for another. This gives us a basis for studying the processes underlying trust and authority, especially as they affect the structure of the evolving social network of agents. We explore key relationships between the policies and representations of the individual agents on the one hand and the aggregate structure of their social network on the other.