The pLysRS-Ap4A Pathway in Mast Cells Regulates the Switch from Host Defense to a Pathological State

The innate and adaptive immune systems play an essential role in host defense against pathogens. Various signal transduction pathways monitor and balance the immune system since an imbalance may promote pathological states such as allergy, inflammation, and cancer. Mast cells have a central role in the regulation of the innate/adaptive immune system and are involved in the pathogenesis of many inflammatory and allergic diseases by releasing inflammatory mediators such as histamines, proteases, chemotactic factors, and cytokines. Although various signaling pathways are associated with mast cell activation, our discovery and characterization of the pLysRS-Ap₄A signaling pathway in these cells provided an additional important step towards a full understanding of the intracellular mechanisms involved in mast cell activation. In the present review, we will discuss in depth this signaling pathway’s contribution to host defense and the pathological state.     

Tracking by Affine Kernel Transformations Using Color and Boundary Cues

Kernel-based trackers aggregate image features within the support of a kernel (a mask) regardless of their spatial structure. These trackers spatially fit the kernel (usually in location and in scale) such that a function of the aggregate is optimized. We propose a kernel-based visual tracker that exploits the constancy of color and the presence of color edges along the target boundary. The tracker estimates the best affinity of a spatially aligned pair of kernels, one of which is color-related and the other of which is object boundary-related. In a sense, this work extends previous kernel-based trackers by incorporating the object boundary cue into the tracking process and by allowing the kernels to be affinely transformed instead of only translated and isotropically scaled. These two extensions make for more precise target localization. A more accurately localized target also facilitates safer updating of its reference color model, further enhancing the tracker's robustness. The improved tracking is demonstrated for several challenging image sequences.     

A parallel implementation of Flat Concurrent Prolog

Flat Concurrent Prolog is a simple, practical, concurrent programming language which has an efficient uniprocessor implementation. This paper describes an initial parallel implementation of the language; it consists of an interpreter implemented on an Intel iPSC Hypercube. The parallel execution of concurrent logic programming languages involves many nontrivial implementation problems. Some of these problems are well known and have been treated extensively in the literature. The most difficult task is to integrate problem solutions in a coherent and efficient manner. The algorithm presented has been useful in providing insights into the major problems and includes a number of novel ideas to simplify implementation. It does not attempt to solve all the problems involved but rather provides a workable basis for current and future research. The algorithm is under ongoing refinement, simplification and improvement.     

Effectiveness evaluation of simulative workshops for newly licensed drivers

The current study set to examine the effects of simulator use in driving instruction on newly licensed drivers, comparing the road safety knowledge and reported intended behavior, as well as the actual driving performance of new drivers. Participants consisted of 280 newly licensed driver, of which 140 whose drivers license training included additional simulator-based lessons, and 140 drivers whose training precluded simulator-based lessons. All drivers answered questionnaires pertaining to their intended safe driving behaviors (according to Ajzen's (2000) theory of planned behavior), and to their traffic safety knowledge. Of the initial sample, 40 drivers received actual driving performance evaluation by an expert driving instructor, as well as by in-vehicle data recorders (IVDRs). We assumed that safer drivers report safer driving intentions, demonstrate greater traffic safety knowledge, evaluated as safer drivers by the driving instructor, and display lower and stable driving parameters on the IVDRs. We hypothesized that theoretical driving studies combined with practical training on simulators will elevate the safety level of novices driving. Hierarchical regression analyses on driving intentions indicated that drivers who did not receive simulator-based lessons demonstrated safer driving intentions compared to drivers who received simulator-based lessons. This pattern possibly indicating the drivers who received simulator-based lessons felt more confident in their driving abilities compared to drivers who did not receive simulated training. No significant difference was found in traffic safety knowledge, or in the evaluation of the expert driving instructor. IDVR data comparisons indicated drivers who received simulator-based lessons braked more often and were less prone to headway events, suggesting a more responsive driving style. These findings do not point to any significant advantage or disadvantage of the current simulator-based driving training over other driving training methods.     

Using Fourier/Mellin-based correlators and their fractional versions in navigational tasks

The navigational tasks of computing time to impact and controlling movements in specific range are addressed here. We show how time to impact can be obtained via the Mellin-based correlator, and we introduce the concept of fractional based correlators. The fractional Fourier/Mellin based correlators can be used in detecting or controlling specific range of movements. Also, both the conventional and the fractional-based correlators can be easily implemented optically in lenses, thus providing correlation images directly at image acquisition time. Lenses are considered cost-effective and therefore, the optical correlators are optimal in both senses, speed and cost.     

Permeabilities to salts and water of macrocyclic polyether–polyamide membranes

The polyether–polyamide (PC-6) strongly absorbs sodium salts from their aqueous solutions. Membranes based on PC-6 and on its polymeric alloys with poly(vinylpyrrolidone) (PVP) are, however, much more permeable to water than to salts. The membrane permselectivity is due to the low mobility of the absorbed salts. Desorption experiments were conducted to determine the values of the diffusion coefficients of the sodium ions in the investigated membranes. They were found to vary from 5 × 10^-12 cm²/sec in loose PC-6 membranes to 1.7 × 10^-9 cm²/sec in the polymeric alloy containing 30% PVP. Water permeation experiments with the alloy membranes yielded values of the diffusion coefficients in the range of 2–5 × 10^-7 cm²/sec. The apparent “energy of activation of the diffusion” of sodium ions in such membranes was found to be essentially indentical (～12 kcal) with the energy of activation of the decomplexation of the sodium–“crown” complex. The ramifications of the proposed “site to site jump” diffusion mechanism were discussed. The permeability characteristics of PC-6 membranes were found to be strongly affected by their “history.”. The observed phenomenon was explained in terms of reversible changes in the structure of the polymeric network, in the presence and in the absence of the absorbed salts. It has been found that PVP has a stabilizing effect on the permeability characteristics of the membranes. Reverse osmosis experiments indicated that their intrinsic osmotic characteristics seem to be superior to those of the commercially used materials. Their salt rejections are in the range of 95–99.5%, and their permeabilities to water are at least one order of magnitude higher than those of the unmodified aromatic polyamides.     

A stable finite element simulation of convective transport

A finite element simulation of the equations of momentum and energy transport in fluids has been implemented with triangular elements. An attempt is made to single out the reasons for numerical instabilities reported by other investigators for convection–diffusion transport operations in fluid mechanics when the ratio of the convective to the diffusive terms, measured by the Reynolds and Peclét numbers, is of the order of a hundred. To this end, the equations are solved for several problems to permit a direct comparison with results of other formulations. It is shown that the appearance of instability can be delayed by a proper choice of boundary conditions, and its intensity can be reduced through the use of triangular finite elements. Results agree very well with theoretical solutions for particular test problems including flows with large convection effects, large dissipation effects and fluids with temperature dependent properties.