The use of terrestrial laser scanning for measurements in shallow-water : correction of the 3D coordinates of the point cloud

Although acoustic measurements are a wide-spread technique in the field of bathymetry, most systems require a water depth of at least 2 m. Furthermore, mapping shallow-water depths with acoustic techniques is expensive and complicated. Over the last decades, the use of laser scanning for mapping riverbeds has increased. However, the level of accuracy and the point density which can be obtained by Airborne Laser Scanning (ALS), and Airborne Laser Bathymetry (ALB) in particular, are not as high as those of terrain measurements originating from ALS. Moreover, ALS and ALB are not yet suited for mapping shallow-water beds. Therefore, more recent research focuses on the use of Terrestrial Laser Scanning (TLS) from either a fixed or static position (STLS) or from a mobile platform (MTLS). An obvious advantage of using STLS and MTLS is that both the river beds and the river banks can be modelled by means of the same data acquisition system. This ensures a seamless integration of data sets describing both dry and wet surfaces, and thus of topography and bathymetry. However, although STLS and MTLS have the potential to produce high resolution point clouds of shallow-water riverbeds and - banks, the resulting point clouds have to be corrected for the systematic errors in depth and distance that are caused by the refraction of the laser beam at its transition through the boundary of air and water. In this research a procedure was implemented to adjust the coordinates of every point situated beneath the water surface, based on the refractive index. The refractive index depends on the wavelength of the laser beam and the properties of the media the beam travels through. The refractive index for a laser beam with a wavelength of 532 nm varies by less than 1% for a wide range of temperature and salinity conditions. Nevertheless, during the case studies, it became clear that it is important to use an estimate of the refractive index which approaches the actual value as closely as possible in order to obtain accuracies of less than 1 to 2 cm. Therefore, the refractive index was determined for each specific case by using water samples

Immunofluorescent technique and long acting thyroid stimulator in human serum

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

EPR spectrum of the oxygen vacancy in single crystals V2O5

A new EPR spectrum of V2O5 is reported which is related to the non-stoichiometry of the crystals. Its intensity increases on reduction and decreases on reoxidation. The spectrum is labelled El. El can be described by an S = 1 spin Hamiltonian with parameters gx = 1.33, gy = 2.51, gz = 1.01 (y ‖ b, x and z at angles of 25° to c and a), and D = 200 × 10−20 erg, E = −40 × 10−20 erg. E1 and the near-infrared spectrum F1 (absorption bands at 1.25 and 1.52 eV with E ‖ a) are assigned to the two donor electrons from the oxygen vacancy in V2O5. The electrons are localized on nearest vanadium neighbours of the vacancy

Temperature dependence of the EPR and optical spectra in V++- doped alkali halides

Analysis of EPR spectra shows that RbCl as well as NaCl and KCl contains V++ centres with a cation vacancy along the [100] axis. The temperature dependence of the spin-Hamiltonian parameters is reported for the three chlorides. The fine structure parameter Burn:x-wiley:03701972:media:PSSB2220780214:tex2gif-stack-1 decreases with temperature. A theoretical explanation based on crystal field theory is presented and correlated with the optical absorption spectrum in the NaCl case

Spin-lattice relaxation of the O-2 centre in RbI and RbBr

Pulse saturation measurements of spin-lattice relaxation rates of Ourn:x-wiley:03701972:media:PSSB2220770124:tex2gif-stack-3 centres in rubidium bromide and iodide are reported. A theoretical calculation for the direct process in these salts is summarised. Phonon integrals appearing in the theoretical formulas are calculated numerically using an anisotropic continuum model, thus improving agreement with experiment. The significance of an unexpected anisotropy for two principal directions, perpendicular to the molecular axis, is discussed in the RbBr case

Asymptomatic atrophic thyroiditis

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Pituitary TSH in normal subjects and in patients with asymptomatic atrophic thyroiditis: evidence for its immunological heterogeneity

SCOPUS: ar.jinfo:eu-repo/semantics/publishe