1,113 research outputs found

    Measurement of Blast Waves from Bursting Pressureized Frangible Spheres

    Get PDF
    Small-scale experiments were conducted to obtain data on incident overpressure at various distances from bursting pressurized spheres. Complete time histories of blast overpressure generated by rupturing glass spheres under high internal pressure were obtained using eight side-on pressure transducers. A scaling law is presented, and its nondimensional parameters are used to compare peak overpressures, arrival times, impulses, and durations for different initial conditions and sizes of blast source. The nondimensional data are also compared, whenever possible, with results of theoretical calculations and compiled data for Pentolite high explosive. The scaled data are repeatable and show significant differences from blast waves generated by condensed high-explosives

    Results of an experimental aerodynamic investigation to obtain static stability and control characteristics of the SSV configurations: The 2A(VL70-000089B) model 1 and 3(VL70-000139B) model 2 orbiter at Mach numbers of 2.5, 3.9 and 4.6 in the NASA LaRC 4 X 4-foot UPWT (OA44)

    Get PDF
    Investigation of space shuttle orbiter configurations 2A(VL70-000089B) and 3(VL70-000139B) was performed at the Langley Research Center Unitary Plan Wind Tunnel (UPWT) from June 1, 1973, to June 15, 1973, for 60 test hours. The primary test objectives were to obtain stability and control characteristics for Configurations 2A and 3 and an alternate forebody used with Configuration 3. In addition, hinge moments were measured on the elevons and rudder for Configuration 2A only. The configurations were tested at Mach numbers 2.5, 3.9 and 4.6. Pitch runs were made at angles of attack from -4 to 44 deg and sideslip angles from -4 to +6. Static pressures were measured at the fuselage base for use in force data correction

    Interferon γ and lymphotoxin or tumor necrosis factor act synergistically to induce macrophage killing of tumor cells and schistosomula of schistosoma mansoni

    Get PDF
    Macrophages play a crucial role in the defense against tumors and parasites. Activation of tumoricidal and microbicidal effector mechanisms requires stimulation of macrophages with macrophage-activating factors (MAF). One such MAF is interferon γ (IFN-γ). In some assays, substantial activity of IFN-γ on murine macrophages, however, is only observed in synergy with lipopolysaccharide (LPS) or other cytokines (1). In addition, certain cytokines have been shown to induce monocyte or macrophage activation in the absence of IFN-γ (2-5). We previously described lymphokines in the supernatant of a murine T cell clone that synergized with IFN-γ in the induction of tumoricidal and schistosomulicidal murine macrophages (1). We called this lymphokine(s) macrophage cytotoxicityinducing factor 2 (MCIF2)(1). A candidate for MCIF2 was lymphotoxin (LT), because the T cell clone supernatant contained high amounts of LT. LT is functionally homologous and structurally related to the macrophage product tumor necrosis factor (TNF). Therefore, we tested whether recombinant (r) LT or rTNF can function as MAF. We report here that rLT or rTNF synergize with rIFN-γ in the induction of tumoricidal and schistosomulicidal murine macrophages

    Abstract Interpretation with Unfoldings

    Full text link
    We present and evaluate a technique for computing path-sensitive interference conditions during abstract interpretation of concurrent programs. In lieu of fixed point computation, we use prime event structures to compactly represent causal dependence and interference between sequences of transformers. Our main contribution is an unfolding algorithm that uses a new notion of independence to avoid redundant transformer application, thread-local fixed points to reduce the size of the unfolding, and a novel cutoff criterion based on subsumption to guarantee termination of the analysis. Our experiments show that the abstract unfolding produces an order of magnitude fewer false alarms than a mature abstract interpreter, while being several orders of magnitude faster than solver-based tools that have the same precision.Comment: Extended version of the paper (with the same title and authors) to appear at CAV 201

    Exact Gap Computation for Code Coverage Metrics in ISO-C

    Full text link
    Test generation and test data selection are difficult tasks for model based testing. Tests for a program can be meld to a test suite. A lot of research is done to quantify the quality and improve a test suite. Code coverage metrics estimate the quality of a test suite. This quality is fine, if the code coverage value is high or 100%. Unfortunately it might be impossible to achieve 100% code coverage because of dead code for example. There is a gap between the feasible and theoretical maximal possible code coverage value. Our review of the research indicates, none of current research is concerned with exact gap computation. This paper presents a framework to compute such gaps exactly in an ISO-C compatible semantic and similar languages. We describe an efficient approximation of the gap in all the other cases. Thus, a tester can decide if more tests might be able or necessary to achieve better coverage.Comment: In Proceedings MBT 2012, arXiv:1202.582

    Economic Impact of the Sugarcane Aphid Outbreak in South Texas

    Get PDF
    The objective of this study was to estimate the economic impact of the sugarcane aphid (SCA) outbreak in the Rio Grande Valley (RGV), Texas. Local producers were surveyed to gather detailed information about crop production and pest control practices. Collected data were used to estimate the reduction in profit associated with the SCA infestation, as well as the monetary value of the prevented loss attributed to control efforts. Sorghum industry losses were then used to assess the overall economic impact of the SCA outbreak in the RGV economy

    Coherent control with shaped femtosecond laser pulses applied to ultracold molecules

    Full text link
    We report on coherent control of excitation processes of translationally ultracold rubidium dimers in a magneto-optical trap by using shaped femtosecond laser pulses. Evolution strategies are applied in a feedback loop in order to optimize the photoexcitation of the Rb2 molecules, which subsequently undergo ionization or fragmentation. A superior performance of the resulting pulses compared to unshaped pulses of the same pulse energy is obtained by distributing the energy among specific spectral components. The demonstration of coherent control to ultracold ensembles opens a path to actively influence fundamental photo-induced processes in molecular quantum gases
    corecore