Experiments concerning resonance-enhanced multiphoton ionization probe measurements of flame-species profiles

Resonance-enhanced multiphoton ionization (REMPI) detection of radical species in low-pressure laboratory flames is a promising tool for the development and refinement of combustion models. For accurate REMPI species concentration measurements in flame zones with inherently high background ionization levels, an understanding of the influence of plasma sheaths on REMPI probe response is required. Proper probe response is found to depend on careful control of probe-biasing and laserfocusing conditions. Only negatively biased probes are suitable, because of the influences of secondary ionization on the response of positively biased probes. In situ probe calibration procedures with the (2 + 2) REMPI of N(2) at 270.6 nm are described. Detection of O atoms in a stoichiometric 20-Torr methane-oxygen flame permits a precise comparison of both laser-induced fluorescence and REMPI measurements with flame-modeling results.     

Calibration of the neutron detectors for the cluster fusion experiment on the Texas Petawatt Laser

Three types of neutron detectors (plastic scintillation detectors, indium activation detectors, and CR-39 track detectors) were calibrated for the measurement of 2.45 MeV DD fusion neutron yields from the deuterium cluster fusion experiment on the Texas Petawatt Laser. A Cf-252 neutron source and 2.45 MeV fusion neutrons generated from laser-cluster interaction were used as neutron sources. The scintillation detectors were calibrated such that they can detect up to 10(8) DD fusion neutrons per shot in current mode under high electromagnetic pulse environments. Indium activation detectors successfully measured neutron yields as low as 10(4) per shot and up to 10(11) neutrons. The use of a Cf-252 neutron source allowed cross calibration of CR-39 and indium activation detectors at high neutron yields (～10(11)). The CR-39 detectors provided consistent measurements of the total neutron yield of Cf-252 when a modified detection efficiency of 4.6×10(-4) was used. The combined use of all three detectors allowed for a detection range of 10(4) to 10(11) neutrons per shot.     

Time variance and defect prediction in software projects

It is crucial for a software manager to know whether or not one can rely on a bug prediction model. A wrong prediction of the number or the location of future bugs can lead to problems in the achievement of a project’s goals. In this paper we first verify the existence of variability in a bug prediction model’s accuracy over time both visually and statistically. Furthermore, we explore the reasons for such a high variability over time, which includes periods of stability and variability of prediction quality, and formulate a decision procedure for evaluating prediction models before applying them. To exemplify our findings we use data from four open source projects and empirically identify various project features that influence the defect prediction quality. Specifically, we observed that a change in the number of authors editing a file and the number of defects fixed by them influence the prediction quality. Finally, we introduce an approach to estimate the accuracy of prediction models that helps a project manager decide when to rely on a prediction model. Our findings suggest that one should be aware of the periods of stability and variability of prediction quality and should use approaches such as ours to assess their models’ accuracy in advance.     

Shading 3D-Images from CT Using Gray-Level Gradients

For the 3D-reconstruction of organ surfaces from tomograms, a shading method based on the partial volume effect is presented. In contrast to methods based on the depth and/or the angle of the voxel surface, here the gray-level gradient along the surface is used for shading. It is shown, that at least for bone and soft tissue surfaces, the results are superior to conventional shading. This is due to the high dynamic range of the gray levels within a small spatial neighborhood.     

Testing network management software

A fourth wave of computer-based network management systems is here. Experienced network managers worry about the reliability of software. This discussion provides ways of testing software to improve software and system reliability, and it proposes a reliability footprint in-process metric to monitor the effectiveness of a test program. Systematic ways of moving from debugging to assuring reliable network management systems are emphasized.     

Beneficial effects of sun exposure on cancer mortality

For more than 50 years, there has been documentation in the medical literature suggesting that regular sun exposure is associated with substantial decreases in death rates from certain cancers and a decrease in overall cancer death rates. Recent research suggests that this is a causal relationship that acts through the body's vitamin D metabolic pathways. The studies reviewed here show that (a) sunlight activation is our most effective source of vitamin D; (b) regular sunlight/vitamin D "intake" inhibits growth of breast and colon cancer cells and is associated with substantial decreases in death rates from these cancers; (c) metabolites of vitamin D have induced leukemia and lymphoma cells to differentiate, prolonged survival of leukemic mice, and produced complete and partial clinical responses in lymphoma patients having high vitamin D metabolite receptor levels in tumor tissue; (d) sunlight has a paradoxical relationship with melanoma, in that severe sunburning initiates melanoma whereas long-term regular sun exposure inhibits melanoma; (e) frequent regular sun exposure acts to cause cancers that have a 0.3% death rate with 2,000 U.S. fatalities per year and acts to prevent cancers that have death rates from 20-65% with 138,000 U.S. fatalities per year; (f) there is support in the medical literature to suggest that the 17% increase in breast cancer incidence during the 1991-1992 year may be the result of the past decade of pervasive anti-sun advisories from respected authorities, coinciding with effective sunscreen availability; and (g) trends in the epidemiological literature suggest that approximately 30,000 U.S. cancer deaths yearly would be averted by the widespread public adoption of regular, moderate sunning.(ABSTRACT TRUNCATED AT 250 WORDS)     

Integrated design support system

The integrated design support system (IDS) is a concept for capturing the critical technical engineering information necessary to perform the functions of maintenance, modification, repair, and reprocurement of Air Force weapon systems. The program will first construct an architecture to define the required information. Next, IDS will construct prototype software to acquire, store, distribute, and perform configuration management on the data. The program will conclude with software simulation of the full-scale IDS system operating in a production environment to determine performance characteristics together with development and operatonal costs for the system.     

Energy effect of the laser-induced vertical metallic link

In this paper, the energy effect of the laser vertical metallic link is investigated from a microscopic point of view through experimental observations and simulations. Sample structures that were irradiated under different laser energies were cross-sectioned and observed using a FIB/SEM dual-beam system. Failure criterion at the high energy level was defined by excessive material loss in the lower metal (metal 1) and passivation cracking. Micro-images also suggest that, for an optimal link metal (metal 2) opening should be larger than the lower metal linewidth considering the dielectric-step-induced lens effect. Taking into account both measured electrical resistance and observed voids in the lower metal, the normalized energy process window is defined to be the absolute energy range divided by the average energy. For the structures with 1-, 2-, 3-, and 4-μm lower metal linewidths, the relative process windows are 0.83, 0.87, 0.9, and 0.96, respectively. Simulations also revealed consistent results with the experimental observations, which is a monotonically decreasing trend of relative energy process windows for more scaled links. A simple equation to evaluate the spot size of the laser beam for various link structures is presented. These results demonstrate the application of commercially viable vertical linking technology to VLSI applications     

Technological characterization of kaolin: Study of the case of the Borborema–Seridó region (Brazil)

The technological characterization of kaolin from the Borborema–Seridó region has shown that it is predominantly kaolinitic, pseudoplastic and thixotropic; approximately 50% of its particles size is less than 2 μm. By using electronic paramagnetic resonance (EPR) and Mössbauer spectroscopy (ME), it was observed that Fe²⁺ and Fe³⁺ substitute Al³⁺ in octahedral sites of kaolinite. After magnetic separation followed by chemical bleaching, kaolin reached a brightness index of 87.72% ISO and an opacity index of 85.58% ISO, indicating that it can be used mainly as a filler and a coating in the paper industry, paint and pottery, among other industries.