Cloning and identification of human Sca as a novel inhibitor of osteoclast formation and bone resorption

Increased osteoclast activity is responsible for the enhanced bone destruction in postmenopausal osteoporosis, Paget's disease, bone metastasis, and hypercalcemia of malignancy. However, the number of known inhibitory factors that block osteoclast formation and bone resorption are limited. Therefore, we used an expression-cloning approach to identify novel factors produced by osteoclasts that inhibit osteoclast activity. A candidate clone was identified and isolated from a human osteoclast-like multinucleated cell (MNC) cDNA library, named osteoclast inhibitory peptide-1 (OIP-1), and the cDNA sequence was determined. This sequence matched that of the recently identified human stem cell antigen, was structurally similar to the mouse Ly-6 gene family, and the sequence predicted it was a glycosyl phosphatidyl inositol (GPI)-anchored protein that had a cleavable COOH-terminal peptide. Western blot analysis of conditioned media from 293 cells transfected with the OIP-1 cDNA clone confirmed that OIP-1 was released into the media as a membrane-bound GPI-linked protein. Interestingly, both recombinant OIP-1 expressed in Escherichia coli (which does not have GPI linker) and OIP-1 expressed by mammalian cells significantly reduced osteoclast-like MNC formation induced by 1,25-dihydroxyvitamin D3 or PTH-related protein in mouse and human bone marrow cultures, and inhibited 45Ca release from prelabeled bone in fetal rat organ cultures. In contrast, recombinant OIP-1 did not inhibit the growth of a variety of other cell types. These data indicate that OIP-1 is a novel, specific inhibitor of osteoclast formation and bone resorption.     

A formal framework for multi-agent systems analysis and design

Agent based computing is generally intended for modeling and implementation of distributed complex problems. Despite the existence of many applications, the problem of rational engineering of multi-agent systems remains complex and difficult. The purpose of this paper can be summarized within two claims. First, we aim at providing an approach that gives some guidelines for specifying and designing multi-agent systems. Secondly, we focus on the formalisms as a language for describing the models produced in each development process phases. These seem to be straightforward, while the development of multi-agent systems is still done, in most cases, without using methods and formal modeling such as those generally used in object oriented software. We illustrate this approach by specifying an example based upon a specific agent architecture.     

Modified error decentralized control with observer backstepping

In this paper, an output feedback version of the modified error method is presented, for linear coupled plants. The novelty lies in the combination of a modified control function of Lyapunov with the observer backstepping technique to obtain a totally decentralized output feedback scheme. Furthermore, the design algorithm is presented in a new recursive form that goes beyond the general expressions yielded by the backstepping. The decentralization, i.e. the elimination of the cross-terms from the obtained multivariable controller, is rendered possible by a new choice of the regulated errors in the backstepping procedure. The internal stability and the tracking performances of the closed-loop system are still preserved, as long as the observer convergence is guaranteed and the H X -norm of the plant interaction quotient is less than one. The developed scheme is successfully applied to the control of a rougher flotation phenomenological simulator.     

On the Effects of Subgrade Erosion on the Contact Pressure Distribution under Rigid Surface Structures

The performance of rigid surface structures such as concrete pavements and slabs-on-grade supported by a deteriorated subgrade and experiencing local contact loss is investigated experimentally and numerically in this study. A laboratory setup has been designed to facilitate the simulation of subsurface erosion and measure the changes in contact pressure at selected locations under a slab-on-grade supported on granular material. The presence of erosion voids under a slab-on-grade can lead to rapid increase in the contact pressure in the immediate vicinity of the void in addition to an increase in tensile stresses at the outermost fibers of the slab. This preliminary study suggests that efforts to detect and arrest the growth of erosion voids under slabs-on-grade should be made before the voids reach the size where significant loss of support develops and the tensile strength of the slab material is exceeded.     

Statistical analysis technique on Ad Hoc network topology dynamic characteristics: Markov stochastic process

On the basis of analysis on the scene files of mobility models in Ad Hoc network, the paper presents a network topology snapshots capturing method to obtain the Ad Hoc network topology architecture at any moment. Through analyzing on the Ad Hoc network topology snapshots, some dynamic characteristic parameters of Ad Hoc network, such as the number of network topology in steady state or unsteady state appearing during a certain time, as well as the durative time of network topology in steady state or unsteady state, could be obtained statistically. Furthermore, the probability of the network topology invariability and variability event could be predicated by adopting the discrete time and continuous time Markov stochastic process theory. The simulation result shows that the statistical analysis technique on Ad Hoc network topology dynamic characteristic not only is effective, but also has the general attribute, which could be used in the statistical analysis technique on Ad Hoc network topology dynamic characteristic under any mobility models.