1,506 research outputs found

    Tumor angiogenesis and anti-angiogenic therapy in malignant gliomas revisited

    Get PDF
    The cellular and molecular mechanisms of tumor angiogenesis and its prospects for anti-angiogenic cancer therapy are major issues in almost all current concepts of both cancer biology and targeted cancer therapy. Currently, (1) sprouting angiogenesis, (2) vascular co-option, (3) vascular intussusception, (4) vasculogenic mimicry, (5) bone marrow-derived vasculogenesis, (6) cancer stem-like cell-derived vasculogenesis and (7) myeloid cell-driven angiogenesis are all considered to contribute to tumor angiogenesis. Many of these processes have been described in developmental angiogenesis; however, the relative contribution and relevance of these in human brain cancer remain unclear. Preclinical tumor models support a role for sprouting angiogenesis, vascular co-option and myeloid cell-derived angiogenesis in glioma vascularization, whereas a role for the other four mechanisms remains controversial and rather enigmatic. The anti-angiogenesis drug Avastin (Bevacizumab), which targets VEGF, has become one of the most popular cancer drugs in the world. Anti-angiogenic therapy may lead to vascular normalization and as such facilitate conventional cytotoxic chemotherapy. However, preclinical and clinical studies suggest that anti-VEGF therapy using bevacizumab may also lead to a pro-migratory phenotype in therapy resistant glioblastomas and thus actively promote tumor invasion and recurrent tumor growth. This review focusses on (1) mechanisms of tumor angiogenesis in human malignant glioma that are of particular relevance for targeted therapy and (2) controversial issues in tumor angiogenesis such as cancer stem-like cell-derived vasculogenesis and bone-marrow-derived vasculogenesis

    Report on balloon shelter tests

    Get PDF
    CER68-69EJP44.For National Center of Atmospheric Research.Includes bibliographical references (page 11).March 1969

    Drag on a smooth flat plate with a fence

    Get PDF
    CER63EJP66.December 1963.Includes bibliographical references.Submitted to the Society of Mechanical Engineers for presentation at the Symposium on fully separated flow, Philadelphia, Pennsylvania, April 1964.A method is presented which permits the determination of the drag on a smooth flat plate when the boundary layer along it is disturbed by a two dimensional, sharp edged fence. This method depends on the knowledge of the drag coefficient of a fence immersed in a boundary layer, and on the friction along the smooth plate in the disturbed boundary layer. The drag coefficient for the fence is calculated using arguments of free streamline theory. The friction along the smooth plate is determined approximately from experimental data. The results are applied to experimental findings of Wieghardt and satisfactory agreement was found

    Modeling of velocity distributions inside and above tall crops

    Get PDF
    Reprinted from Journal of Applied Meteorology v. 7, no. 3, June 1965, pages 400-408.CER64EJP-AAQ-2.Includes bibliographical references.Velocity distributions inside and above a model crop were investigated. The model crop consisted of flexible plastic strips fastened to the floor of a low speed wind tunnel. The experimental results indicated that at some distance xo downstream from the edge of the roughness cover the velocity profiles were similar inside and also above the cover. The length xo is discussed. The experimental results for the velocity distribution inside the plant cover were compared with field data obtained from different sources. A presentation of the velocity profiles inside the canopy in nondimensional form collapsed all field and laboratory data for a given crop type on one curve. The laboratory flow above the crop cover was analyzed using a power law form and using the logarithmic velocity distribution law. On the basis of the experimental results it is recommended that a two-tower arrangement of wind velocity measuring devices be used both for the evaluation of the surface shear stress and for checking the establishment of similarity profiles in the field

    Evaporation from small wind waves

    Get PDF
    CER68-69JRL35.June 1969.Prepared for the National Science Foundation.Includes bibliographical references.The evaporation rates from small wind-waves by forced convection in a range where the spray of water by strong wind action is not important has been studied in the laboratory. The effects of free stream velocity, wave conditions, and temperature difference between air and water (either inversion conditions or lapse conditions) on evaporation were investigated, and the results were compared with previous work. The experimental data were correlated in terms of dimensionless groups, which were based on well-known theories for exchange processes in forced convection over solid surface. The transitional phenomenon was analyzed for evaporation as the wind blew over the solid surface onto the water surface. For the lapse condition, the temperature difference was found to cause larger growth rates of the waves as well as increased evaporation rates. The stratification of air velocity above the water surface was calculated, based on the Richardson criterion. No significant change was detected based on this criterion in this study.Under NSF grant no. GK

    Experimental study of turbulent boundary layer structure, An

    Get PDF
    CER64EJP-VAS37.December 1964.Includes bibliographical references.Final Report on U.S. Army Research Grant with Meteorology Department U.S. Army Electronic Research and Development Activity, Fort Huachuca, Arizona.Under U.S. Army Research Grant DA-SIG-36-039-62-G24

    Wind action on water standing in a laboratory channel

    Get PDF
    CEP6566-GMHEJP14a, CER65GMH-EJP40a.NCAR preprint-memo, PM # 135.Includes bibliographical references.The processes of wave and current development resulting from wind action on initially standing water have been investigated in a wind-water tunnel. The mean air flow over wavy water was examined along with the variation of several properties of the water motion with fetch, water depth, and wind speed. Measurements of phase speed and length of significant waves, the standard deviation of the water sur face, the average surface drift, the autocorrelation of surface displacement and the frequency spectra of the wind waves are reported. The experimental results indicate that (a) the air motion in the channel follows a three dimensional pattern characteristic of wind tunnels of rectangular cross-section; (b) the wind waves generated in the channel travel downstream at approximately the same phase speed as gravity waves of small amplitude, provided the effect of the drift current is taken into account; (c) the average drag coefficients for the action of the wind on the water surface increase with increasing wind speed, and these data are essentially the same as the results of previous investigators; (d) the autocorrelations of surface displacement and frequency spectra are consistent with the visual observations that the wind waves in the channel consist of nearly regular primary waves on which are superimposed smaller ripples; (e) energy in the high frequency range in the spectra tends to approach an equilibrium distribution rather quickly while the lower frequency components initially grow exponentially with increasing fetch but, later, tend to reach a state of equilibrium; and (f) a similarity shape for the frequency spectra developed

    Micrometeorological wind tunnel facility: description and characteristics

    Get PDF
    CER63EJP-JEC9.Includes bibliographical references (pages 39).February 1963

    R&D ERL: HTS Solenoid

    Get PDF
    An innovative feature of the ERL project is the use of a solenoid made with High Temperature Superconductor (HTS) with the Superconducting RF cavity. The HTS solenoid design offers many advantages because of several unique design features. Typically the solenoid is placed outside the cryostat which means that the beam gets significantly defused before a focusing element starts. In the current design, the solenoid is placed inside the cryostat which provides an early focusing structure and thus a significant reduction in the emittance of the electron beam. In addition, taking full advantage of the high critical temperature of HTS, the solenoid has been designed to reach the required field at {approx}77 K, which can be obtained with liquid nitrogen. This significantly reduces the cost of testing and allows a variety of critical pre-tests which would have been prohibitively expensive at 4 K in liquid helium because of the additional requirements of cryostat and associated facilities

    Advances in Control of Onion Thrips (Thysanoptera: Thripidae) in Cabbage

    Get PDF
    Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), feeding injury results in discoloration and a rough texture on cabbage, Brassica oleracea capitata (L.), leaves, and damage may occur deep inside the head. It has become a key pest of cabbage in the United States and many other countries. Previous studies have indicated poor control using insecticides. The present study identified imidacloprid drenches and sprays of acetamiprid, dimethoate, spinosad, and imidacloprid as insecticides that performed better than the industry standard, lambda-cyhalothrin. However, additional tests with foliar sprays of dimethoate and acetamiprid indicated there was not an ideal crop stage (precupping, cupping, or postcupping) at which either insecticide could be applied for reliable control of T. tabaci, possibly because of multiple flights of thrips into the crop or the asynchrony of flights and susceptible crop stages. In tests in a commercial field, a soil drench of imidacloprid 4 wk after transplanting reduced the number of damaged leaves in the head by 32%, whereas five sprays of acetamiprid reduced damage by 51%. Combining both insecticide regimes reduced damage by 85%, but resulted in a very costly management program. Cabbage varieties varied considerably in susceptibility with some having negligible thrips injury, regardless of being treated with an insecticide. Planting date affected susceptibility of cabbage to some degree, but not as much as other tactics. Overall, these studies indicate that increased emphasis should be placed on breeding cabbages to be resistant to T. tabaci as the foundation for its managemen
    • …
    corecore