Role of JAK3 in CD40-mediated signaling

Several constitutively activating mutations have been demonstrated in the sixth transmembrane helix of the human LH receptor (hLHR) in boys with gonadotropin-independent precocious puberty. In the current study, we examined two unrelated Brazilian boys with gonadotropin-independent precocious puberty caused by two different heterozygous activating mutations of the hLHR. Direct sequencing of the entire exon 11 of the hLHR revealed a heterozygous substitution of T for G at nucleotide 1370, that converts Leu 457 to Arg in the third transmembrane helix of the hLHR in one affected boy. His biological parents had a normal hLHR gene sequence, establishing the sporadic nature of this novel Leu457Arg mutation. Human embryonic 293 cells expressing hLHR mutant (L457R) or hLHR wild-type bound CG with high affinity. However, cells expressing hLHR(L457R) exhibited significantly higher basal levels of cAMP (7- to 14-fold) than cells expressing the wild-type receptor, indicating constitutive activation of hLHR(L457R). Basal levels of cAMP in hLHR(L457R)-expressing cells were, nonetheless, not as great as the levels of cAMP produced by hLHR wild-type-expressing cells incubated with a saturating concentration of CG. Furthermore, cells expressing hLHR(L457R) were unresponsive to further stimulation by CG. This finding was confirmed in the patient by lack of an increase in serum testosterone after CG stimulation. These results suggest that the conformation of hLHR(L457R) mutant represents a different activated receptor state (R*) than the agonist-occupied wild-type receptor. We also identified the previously described Ala568Val mutation in the third intracellular loop of the LHR in the other affected African-Brazilian boy and his normal prepubertal sister, suggesting the inherited form of precocious puberty in this boy. We conclude that the third transmembrane helix is a potential area for activating mutations of the hLHR that cause male precocious puberty.     

Resource allocation in communication networks using abstraction and constraint satisfaction

The fundamental issue of quality-of-service (QoS) routing has triggered a lot of research during the last few years. However, the proposed algorithms attempt to route communication demands only on a call by call basis, without taking into account future traffic. There are nonetheless cases where the traffic profile is known. In this paper, we address this related problem to QoS routing, more specifically, the off-line planning of bandwidth allocation to demands known in advance. Shortest-path routing is the traditional technique applied to this problem. However, this can lead to poor network utilization and even congestion. We show how an abstraction technique combined with systematic search algorithms and heuristics derived from artificial intelligence make it possible to solve this problem more efficiently and in much tighter networks, in terms of bandwidth usage. In addition, this abstraction technique also allows to explain during search why some allocation problems are indeed infeasible. Then, the network regions between which bandwidth must be added are then identified.     

A galerkin moment method for the analysis of insulated wires above a lossy half-space

In this paper, an efficient method is proposed for the analysis of insulated wires above a lossy half-space. The reaction concept is used to formulate the electromagnetic boundary value problem. The solution is a Galerkin moment method solution with piecewise sinusoids as basis and testing functions. The influence of lossy half-space is taken into account via equivalent images, and the currents of images are related to the source current. The dielectric coating is modeled by equivalent volume polarization currents, which are simply related to the conduction current distribution. In this way, the dielectric-coating and lossy half-space cause no new unknowns to the problem solution, the size of the impedance matrix for insulated wires above lossy ground is the same as that of bare wires in free space. The insulation is accounted for entirely through a modification of the symmetric impedance matrix. The results obtained exhibit excellent agreement with those by rigorous method or experiments.     

African histoplasmosis: report of four cases from north-eastern Nigeria

Four cases of African histoplasmosis with lesions of the skin, subcutaneous tissues and lymph nodes diagnosed histologically are described from the Borno State of Nigeria. Three of the cases were autochthonous to this State, whereas the fourth one originated from the Anambra State of Nigeria. These cases constitute the first record of African histoplasmosis from the arid zone of the north-eastern part of Nigeria.     

Efficient protocols for multimedia streams on WDMA networks

This paper introduces a new approach to integrate different types of medium access control (MAC) protocols into a single wavelength-division-multiplexing (WDM) network system. The WDM network is based on a passive star coupler, and the purpose of integrating different MAC protocols is to efficiently accommodate various types of multimedia traffic streams with different characteristics and quality of service demands. Our integrated MAC protocol is termed multimedia wavelength-division multiple-access (M-WDMA). Three types of multimedia traffic streams are considered in this paper: constant-bit-rate traffic and two classes of variable-bit-rate traffic. Accordingly, three tunable transmitters and one fixed home channel receiver are used in the design of each WDM node. The transmitters transmit the three types of multimedia traffic streams in a pipeline fashion so as to overcome the tuning time overhead and to support parallel transmissions of traffic streams that emerge simultaneously. We further incorporate a dynamic bandwidth allocation scheme that dynamically adjusts the portions of bandwidth occupied by the three types of traffic streams according to their demands. Consequently the M-WDMA protocol achieves high utilization and efficiently adapts to the demands of the multimedia streams so as to guarantee their QoS. The performance of the M-WDMA is evaluated through a simple analytical model and extensive discrete-event simulations. It is shown that the M-WDMA can satisfy the QoS requirements of various mixes of multimedia traffic streams even under very stringent requirements. Moreover, we show that the M-WDMA outperforms conventional MAC protocols for WDM networks. As a result, we expect M-WDMA to be a good multimedia MAC candidate protocol for future-generation WDM networks.     

On the application of the blocking island paradigm in all-optical networks

We investigate the problem of routing and wavelength assignment as well as the problem of the placement of wavelength converters in all-optical networks. In particular, we present a general framework, based on the blocking island (BI) paradigm, to illustrate how it can be used to solve these problems in a unified way. We first give a brief introduction about the BI graph network model, and then use this model to derive simple and general algorithms that can be used in various applications in optical networks. We discuss the implementation issues of our algorithms and present simulation results to evaluate and compare our solutions with other heuristic algorithms under both static and dynamic traffic assumptions.     

Adsorption studies of fatty acids on montmorillonite‐based filler clay

Surface coating of montmorillonite‐based filler clay with stearic and oleic (9‐octadecenoic acid) acids was presented. Sedimentation measurements showed that the sedimentation rate and the sediment volume decreased sharply with the adsorbed amount of the acid up to a certain concentration and then became constant. The chemical analysis showed that the adsorbed amount of either acid by montmorillonite clay increased with the equilibrium concentration of the acid in the solution. The adsorption isotherm indicated the formation of a monolayer on the clay surface at a lower concentration of the acids followed by formation of multilayers of the acids on the clay surfaces at higher concentrations. XRD analysis indicated no intercalation of either acid in the lamella of the clay. We concluded the possibility of surface coating of montmorillonite clay with a monolayer of fatty acids that render the clay organophilic. The adsorption of either acid improved the dispersibility of the clay particles in organic or polymeric media. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2574–2580, 2002     

A scalable video-on-demand system using multi-batch buffering techniques

A video-on-demand (VoD) system delivers videos on demand over an installed network. Due to the large size of digitized videos, expensive video servers with high I/O capability are needed in order to provide VoD services in metropolitan areas. In addition, there is a great need for efficient networking distribution/interaction schemes so that the video servers can serve as many clients as possible. In particular, because of scalability problems, the classical unicast VoD system is not suitable for large-scale deployments. In this paper, a highly scalable VoD system with a low per-user cost is described and evaluated. We first analyze the performance degradation problems using recently proposed VoD systems, namely batched and centralized-buffer VoD systems that occur during the handling of interactions. Then a new system called the multi-batch buffer (MBB) system, which attempts to solve these problems, is proposed. The proposed system handles a majority of interaction requests by scalable buffering techniques employed in the buffer of the local servers and the set-top boxes (STB). We have performed extensive simulation for the analysis and performance evaluation of our proposed VoD system. The simulation results demonstrate that our VoD system is very scalable and outperforms related state-of-the-art VoD systems.