Multicomponent frequency shifting self-aligning laser velocimeters.
A design using simple lenses and frequency shift by scattering disk has been developed, which allows easy construction, and alignment of one-, two-, and three-orthogonal-component, frequency shifting laser Doppler velocimeters. A series of instruments designed on this basis have proved to be inexpensive to construct, precise and accurate to use, adaptable to a wide range of applications, and have proven particularly advantageous in studies of turbulent phenomena and complex flows. In this paper the design concept is explained, construction and alignment procedures are outlined for the simplest assembly of the one and two component versions, and performance and application examples are presented. The extension of the system to measure the third orthogonal component is discussed.
Perturbations of Charged-Droplet Trajectories Caused by Induced Target Corona: LDA Analysis
During electrostatic spraying, droplet deposition can inherently become limited by gaseous discharges induced to flow between earthed target points and the nearby charged-spray cloud as a result of electric-field intensification at the points caused by the cloud's space charge (c. 25 ¿ZC/m3). This problem is distinct from back ionization, and it has profound consequences for electrostatic crop spraying of foliar tips. Laser Doppler anemometry was developed to determine the spatial extent to which the counter-flow of ions from earthed points interacts with the spray cloud and how the trajectories of approaching charged droplets are consequently altered. In the vicinity of cylindrical, spherical, and disk targets the two-dimensional velocity fields were measured for conductive droplets of 30-50 Atm diameter of up to -6 mC/kg charge level, delivered by aerodynamic entrainment at 3 m/s. While electrostatic forces were shown to enhance droplet motion toward the various smooth targets, introduction of a 2-cm target point not only negated the electrostatic deposition benefit, but its action in some locations increased droplet repulsion from the targets.
X-rays and photocarcinogenesis in hairless mice
It is well known that excessive X-ray radiation can cause non-melanoma skin cancers. With the increased incidence of sun-related skin cancer there is a need to investigate the combination of sunlight and X-rays. Immunocompetent C3.Cg/TifBomTac mice (n = 298) were divided into 12 groups. Mice were irradiated with 12, 29 or 50 kV X-rays. The mice received a total dose of 45 Gy. They were irradiated with 3 SED simulated solar radiation (SSR) either before or after irradiation with X-rays. The groups irradiated with X-rays alone, 0, 3, 9 and 10 mice (0, 12, 29 and 50 kV, respectively) developed squamous cell carcinoma. In the groups irradiated with SSR after X-rays the development of tumours was significantly faster in the 50 kV group than in the corresponding control group (175 vs. 194 days, p < 0.001). In the groups irradiated with SSR prior to the X-ray radiation the development of tumours was significantly faster in the 29 and the 50 kV groups than in the corresponding control group (175 vs. 202 days, p < 0.001 and 158 vs. 202 days, p < 0.001, respectively). In conclusion, X-ray radiation alone is a weak carcinogen in hairless mice. There is an added carcinogenic effect if X-ray radiation is given on prior sun-exposed skin or if the skin is sun-exposed after X-rays. We still believe that X-ray radiation is a safe and effective therapy for various dermatological diseases but caution should be observed if a patient has severely sun-damaged skin or has a high-risk sun behaviour.