β Scribed by P Van Elsacker; H Keppens; I Impens
No coin nor oath required. For personal study only.
A method for analyzing radiation interception by an individual tree is presented. The use of a whole set of expensive radiation instruments is eliminated, the work-intensive field ~experiments are reduced to half a day for a large tree (9 m), and neither clear sky conditions nor diffuse radiation data are necessary. It is assumed that for a given azimuth and solar elevation the shading caused by a tree can be estimated photographically by taking a slide in the opposite direction. From slides taken of the whole tree in different directions and from different distances (i.e., different view angles), gap frequencies for certain heights are measured. At each height, gap frequency decreases significantly with increasing solar elevation. By calculating the mean path length within the crown (s) corresponding with each gap frequency (g), a highly significant exponential relationship between both is obtained [g = exp(--0.42s)]. With this equation and by knowing the tree dimensions calculated from the slides, direct and diffuse radiation interception of the whole tree can be estimated. Total leaf area and leaf area density are also calculated. These values agree very well with direct measurements on similar cut trees.
π SIMILAR VOLUMES
Histamine, putrescine, spermidine, and spermine in rat tissues and human urine were separated on a CM-cellulose column (0.6 x 10 cm). These amines in the chromatographic eluate were determined by the reactions with o-phthalaldehyde (for histamine), fluorescamine, o-phthalaldehyde-mercaptoethanol, or
A method for quantifying the magnitude of higher order field modes radiated by an arbitrarily shaped antenna is presented. Numerically determined fields are equated with the general multipolar field expansion, allowing the relati¨e magnitude of each higher order component to be determined.
In this paper we prove that the system of generalized eigenvectors of the operator (I + Ξ΅K) -1 Γ d 4 /dx 4 forms a Riesz basis of L 2 (]-L, L[) where K is the integral operator with kernel the Hankel function of the first kind and order 0. This operator was introduced in J.