Head trauma

Progress in research includes studies concerning the pathophysiology and outcome of pediatric head injury, the pathology of the hippocampus in fatal injury, and the use of multivariate statistics to predict outcome in survivors. Recent research has confirmed and extended findings regarding the differential effects of closed head injury, depending on the age of the individual. These studies indicate that the consequences of head injury are more severe in older adults and in children younger than 2 years. Neuroimaging findings include evidence for delayed brain injury as a major cause of mortality and disability. Functional brain imaging provides evidence for cerebral dysfunction that is not appreciated by structural brain imaging techniques and may have a stronger relationship to neurobehavioral sequelae. The neurobehavioral sequelae frequently implicate frontal dysfunction, even in the absence of structural findings on computed tomography or magnetic resonance imaging. Studies of mild head injury have expanded our knowledge concerning the pathogenesis of postconcussional symptoms, including a preinjury vulnerability based on recent life events. Persistent postconcussional symptoms after mild head injury are frequently associated with emotional disturbance of clinical proportions.     

Interleukin-8 expression in normal nasal epithelium and its modulation by infection with respiratory syncytial virus and cytokines tumor necrosis factor, interleukin-1, and interleukin-6

Inflammation in nasal and airway tissue caused by allergens, microbial infection, and air pollution are likely to be regulated by inflammatory mediators produced by airway epithelial cells. We have therefore investigated the baseline expression of a number of cytokine genes known to be important inducers and modulators of inflammation, in freshly isolated human nasal epithelium. Cells were obtained by superficial scraping of turbinate tissue, and cDNA for polymerase chain reaction (PCR) amplification was reverse-transcribed directly from lysates of 3 x 10(3) to 5 x 10(3) epithelial cells using random hexamers. Constitutive expression of relatively high levels of interleukin-8 (IL-8) mRNA but undetectable levels (< 1 mRNA copy/cell) of granulocyte/macrophage colony-stimulating factor (GM-CSF), IL-6, IL-1, or tumor necrosis factor (TNF) mRNA were found after PCR amplification of the cDNA. IL-8 protein, but not IL-6, was identified in the nasal epithelial cells by immunocytochemistry. Infection with respiratory syncytial virus (RSV) or stimulation of nasal epithelium for 4 h with TNF or IL-1 in vitro resulted in a 4- to 10-fold increase in IL-8 mRNA expression but not in the expression of detectable levels of mRNA for the other cytokines. IL-8 was secreted by RSV-, IL-1-, and TNF-stimulated as well as unstimulated nasal epithelial cells after 6 to 20 h of culture. Neither IL-6, GM-CSF, nor TNF activity/immunoreactivity was detectable in the culture supernatants. Thus, it appears that IL-8 is a major cytokine of human nasal epithelium, constitutively expressed and readily secreted upon virus infection or stimulation with IL-1 and TNF.     

A graphic approach to performance analysis of multistage linear interference canceller in long-code CDMA systems

The signal-to-interference-plus-noise-ratio performance of the multistage linear parallel and successive interference cancellers (LPIC and LSIC) in a long-code code-division multiple-access system is analyzed using a graphical approach. The decision statistic is modeled as a Gaussian random variable, whose mean and variance can be expressed as functions of moments of R for the LPIC and L for the LSIC, respectively, where R is the correlation matrix of signature sequences and L is the strict lower triangular part of R. Since the complexity of calculating these moments increases rapidly with the growth of the stage index, a graphical representation of moments is developed to facilitate the computation. Propositions are presented to relate the moment calculation problem to several well-known problems in graph theory, i.e., the coloring, the graph decomposition, the biconnected component finding, and the Euler tour problems. It is shown that the derived analytic results match well with simulation results.     

On the performance of the CREL system

This paper presents the performance results of a comprehensive approach to the parallel execution of rule systems. It describes the semantics of a Concurrent Rule Execution Language, CREL, and the architecture of the system that compiles and executes CREL programs. The system has been designed to avoid run-time overhead by performing extensive compile-time analysis and by parallelizing compilation. Static dependency analysis, based on serializability, coupled with a set of optimizing transforms, partitions the program into subsets, called clusters. Clusters execute independently of each other and communicate though asynchronous message passing. At run time two additional sources of parallelism are exploited—run-time consistency checking allowing multiple rules to fire, and match-level parallelism. The CREL system is implemented on a Sequent Symmetry shared-memory computer. This paper presents the results of a factorial experiment that isolates and evaluates each source of parallelism in the CREL system and each possible combination of those methods. The results suggest that multiple-rule firing is the single most important source of parallelism in CREL programs and that the use of static dependency analysis based on serializability is instrumental to effectively exploit parallelism.     

Bayesian Availability Using Gamma Distributed Priors

Classical statistical estimation techniques have limited usage in predicting system availability when a system, e.g., a computer or telecommunications system, is highly reliable. A Bayesian solution is suggested in this paper. Gamma priors, which are rich in shapes, are assigned to the scale parameters of a gamma distributed component on-time and off-time. Estimation of the gamma priors follows engineer's past experiences for reliability modeling. Both steady-state and instantaneous availabilities are derived using Bayes Theorem. An illustration highlights the assessment and evaluation of the proposed availability measure.     

Fabrication and properties of PLZT ceramics from spray-dried aqueous solution

PLZT ceramics with the composition of 9/62/38 (La/Zr/Ti) were fabricated from spraydried aqueous solution. Complete crystallization of the spray-dried powder is achieved after 1 hr calcination at 650‡ C as compared to 800‡ C, 1 hr for conventional mixedoxide method. Sintering environment plays an important role in the densification of PLZT ceramics. Densities of the atmosphere sintered samples are much higher than those of normal sintered ones. PLZT ceramics derived from spray-dried powders have properties comparable to those derived from sol-gel ones. The spray-dried method presents a less expensive and more effective approach in the synthesis of PLZT ceramics.     

Design of quasi-elliptic function filters with a dual-passband response

Compact miniaturized hairpin resonators are used to design cross-coupled filters with a dual-passband response of elliptic function type. The hairpin resonators are treated as a stepped impedance resonator (SIR) in analysis. In a filter, two different hairpin resonators are used to establish proper couplings required for the two design frequencies. Two filters are fabricated and measured. The results show a good agreement with the simulation.