Rapid diagnosis of tuberculous meningitis by polymerase chain reaction assay of cerebrospinal fluid

A polymerase chain reaction (PCR) method for the rapid diagnosis of tuberculous meningitis (TBM) was used to study prospectively 47 cerebrospinal fluid (CSF) samples from 45 patients. Twenty CSF samples were from patients with clinically suspected TBM and another 27 samples came from patients without clinically suspected TBM. Mycobacterial DNA was detected in 15 CSF samples (14 from patients with clinically suspected TBM and 1 from a patient not suspected of having TBM). Of the PCR-positive samples, 4 were also positive for mycobacterial culture. However, 32 PCR-negative samples were all culture-negative. All samples were negative for the acid-fast bacillus by direct smear. The single PCR-positive patient in the clinically unsuspected TBM group was initially diagnosed as suffering from aseptic meningitis on the basis of his clinical features. The mycobacterial culture of his CSF specimen was also positive and a revised diagnosis of an aseptic type of TBM was made. The estimations of specificity and sensitivity in this study were 100% and 70% respectively. The results showed that using a PCR to detect mycobacterial DNA in CSF for the early diagnosis of TBM is not only a rapid but also an accurate method.     

Effects of exit back-up on delamination in drilling composite materials using a saw drill and a core drill

Machining of composites has caught greater attention in manufacturing of structural parts in aerospace, automobile and sporting goods. Composite materials have advantageous features in strength and stiffness coupled with lightweight compared to the conventional metallic materials. Amongst all machining operations, drilling is the most commonly applied method for generating holes for riveting and fastening the structural assembly. Delamination is one of the serious concerns in drilling holes in composite materials at the bottom surface of the workpiece (drill exit). Quite a few references of the drilling of fiber-reinforced plastics report that the quality of cut is strongly dependent on drilling parameter as well as the drill geometry. Saw drills and core drills produce less delamination than twist drills by distributing the drilling thrust toward the hole periphery. Delamination can be effectively reduced or eliminated by slowing down the feed rate when approaching the exit and by using back-up plates to support and counteract the deflection of the composite laminate leading to exit side delaminations. The use of the back-up does reduce the delamination in practice, which its effects have not been well explained in analytical fashion. This paper predicts the effects of backup plate on delamination in drilling composite materials using saw drill and core drill. The critical drilling thrust force at the onset of delamination is calculated and compared with that without backup. The well known advantage of industrial use of backup can be understood fundamentally by the fact that the threshold thrust force at the onset of delamination is increased making the delamination less induced.     

Expression profile of senescence-associated beta-galactosidase and activation of telomerase in human ovarian surface epithelial cells undergoing immortalization

Senescence is a specific physiological stage of cells characterized by long population doubling time. It accounts for the inability of normal somatic cells to undergo indefinite cell division. As the number of population doublings increase, cell cycle regulatory mechanisms come into play and signal cells to exit the cell cycle and become senescent. Senescence has been implicated in the aging process and may function as a tumor suppressor mechanism in human cells. The ability to measure the degree of cellular senescence is important in understanding the biological processes regulating cell aging and immortalization. Senescent cells exhibit an enzyme termed senescence-associated histochemical staining. Cells immortalized by viral oncogenes often enter a stage of crisis at the early phase of immortalization. The cells at crisis have a long population doubling time. Cells at the crisis stage resemble senescent cells and the expression of SA- beta-Gal may be used to monitor the process of immortalization. In this study the expression profile of SA-beta-Gal was examined in human ovarian surface epithelial cells (HOSE 6-3) undergoing immortalization by the human papilloma viral oncogene E6 and E7 (HPV E6 and E7). Our results showed a low percentage (12.0%) of HOSE 6-3 cells expressing SA-beta-Gal activity at the pre-crisis stage. The percentage of HOSE 6-3 cells expressing SA-beta-Gal activity was highest (39.2%) at the crisis stage. When HOSE 6-3 cells achieved immortalized status there was a sharp decrease in cells (1. 3%) expressing SA-beta-Gal activity. In addition, an inverse relationship between the expression of SA-beta-Gal activity and telomerase activity was noted in cells undergoing immortalization. The results confirm that the SA-beta-Gal enzyme is a good marker for monitoring the population of cells undergoing senescence at different stages of immortalization and that telomerase activation is a characteristic feature of post-crisis cells.     

The optimization of spectrum analysis for digital signals

This paper provides a complete method to solve the defects of spectrum analysis for discrete signals. Many researches had issued to deal with the defects of fast Fourier transform (FFT). Those methods may cause the characteristics of original signal altered, or solve this problem in part only. The defects of spectrum analysis cannot be solved efficiently and completely by those methods. These defects result from that those frequency scales cannot match with signal characteristics. This paper is based on the concept to establish a complete solution, divided into three steps: First, this paper analyzes the signal characteristics to be the basis of spectrum adjustment. A simple and accurate algorithm is used to find the frequency and amplitude of each component. Next, this paper finds optimum spectrum parameters to make the new spectrum match with signal characteristics. Finally, this paper takes the parameters to reanalyze the original signal. The method will make spectrum analysis reach optimization. Every procedure in this paper compares with traditional ones to prove its benefits. Moreover, the authors verify the theory feasible by analyzing actual signals.     

Theorem and application of adjustable spectrum

This paper affords the theorem, procedures, and evaluation of ability of adjustable spectrum for signals. By mean of adjusting frequency resolution and frequency shift, we can adjust frequency scale. The paper evaluates every process of computation to verify accurate computation and fast response of adjustable spectrum. Since frequency scale of this spectrum is adjustable, it makes the spectrum analysis of signal reach optimization. The method eliminates the picket-fence effect and the leakage effect by fast Fourier transform (FFT). Since the procedures remain as the characteristic of fast computation that this method can be used for real-time analysis.     

A reliability model for real-time rule-based expert systems

This paper uses two modeling tools to analyze the reliability of real-time expert systems: (1) a stochastic Petri net (SPN) for computing the conditional response time distribution given that a fixed number of expert system match-select-act cycles are executed, and (2) a simulation search tree for computing the distribution of expert system match-select-act cycles for formulating a control strategy in response to external events. By modeling the intrinsic match-select-act cycle of expert systems and associating rewards rates with markings of the SPN, the response time distribution for the expert system to reach a decision can be computed as a function of design parameters, thereby facilitating the assessment of reliability of expert systems in the presence of real-time constraints. The utility of the reliability model is illustrated with an expert system characterized by a set of design conditions under a real-time constraint. This reliability model allows the system designers to: (1) experiment with a range of selected parameter values; and (2) observe their effects on system reliability     

Morphology and kinetics of discontinuous precipitation and dissolution in an Fe-8.5Al-27Mn-1.0Si-0.92C alloy

The morphology and growth kinetics of discontinuous precipitation (DP) and discontinuous dissolution (DD) in an Fe-8.5Al-27Mn-1.0Si-0.92C alloy are investigated. The results indicate that the solid-solution-treated austenite phase decomposes into lamellar DP after aging at temperatures ranging from 900 to 1050 K. After the specimens of a preaged DP structure go through further aging at temperatures ranging from 1118 to 1173 K, the lamellar DP falls into dissolution because of the DD reaction. The lamellar spacings of the DP structure, as well as the reaction-front migration rates during DP and DD reactions, are measured. Based on Aaronson and Liu’s simplified kinetics model, the grain-boundary diffusivities are estimated. They are found to be slightly lower than the grain-boundary diffusion data of Mn in Fe and Fe in Fe as reported by Aaronson and Liu.     

Reduction of sidelobe and speckle artifacts in microwave imaging:the CLEAN technique

Large random thin arrays provide a high angular resolution microwave images but are plagued with artifacts (false targets and target breakup or speckle) caused by high sidelobe levels. The CLEAN algorithm for reducing the sidelobe-induced artifacts is extended to the coherent radiation field and the theory placed on a quantitative basis. The CLEAN technique decomposes the received echoes of a coherent multiple-target scene by iterative cancellation of the largest target found. At each step, cancellation information is used to create a target image. The image includes target intensities, phases, and directions. The process is designed for an imaging instrument consisting of a random thinned array. A condition is derived which, when satisfied, guarantees that all proper targets will be preserved in the cleaned image and all false targets discarded. An algorithm involving moving thresholds is derived to extract the target coordinates. It is shown that targets much weaker than the sidelobe level can be detected and displayed without the hazard of artifacts. The target dynamic range and the image contrast can be increased by up to twice the signal-to-noise ratio per element     

Mutational analysis of human papillomavirus type 11 E5a oncoprotein

In this study, we investigated the structural basis of human papillomavirus type 11 (HPV-11) E5a transforming activity at the amino acid level. The effects of insertion, deletion , and substitution mutations on teh E5a transforming activity were determined by the assay of anchorage-independent growth. In the conserved Cys-X-Cys structure, substitution of Ser for Cys-73 resulted in indistinguishable transforming activity, whereas substitution of Ser for Cys-75 or Ser for both Cys-73 and Cys-75 retained 50 and 42% transformation, respectively. This suggests that Cys at position 75 may be important for transformation. Charge and structural changes at teh COOH termini of several mutants impaired transformation significantly, but those at the middle region did so only mildly. In addition, the 16,000-molecular-weight pore-forming protein (16K protein) is known to associate with BPV-1, HPV-6, and HPV-16 E5 proteins. In this study, we investigated the correlation between E5a-16K binding affinity and the transforming activity of E5a by the use of 11 E5a mutants. Results show that E5a and these 11 E5a mutants could bind to the 16K protein when these proteins were coexpressed in COS cells, suggesting that simple binding of the 16K protein by E5a may not be sufficient for cell transformation.