ENVIRONMENTAL AUDITING: Use of Landsat Thematic Mapper Data to Assess Seasonal Rangeland Changes in the Southeast Kalahari, Botswana.

/ Management problems arise in semiarid rangeland that are characterized by marked wet and dry seasons because of forage deficiencies in the dry season. These natural vegetation rangelands can sustain livestock all year long when forage and senesced grass are available into the dry season. Seasonal range condition data are required to provide a basis for pasture management to help locate dry season cover and thereby minimize overstocking and degradation. The generation of seasonal data using Thematic Mapper (TM) imagery was undertaken to assess changes in natural vegetation cover in the southern Botswana Kalahari. Visual analysis of spectral reflectance curves, the development of spectral separability indexes, and conventional classification analysis techniques were used to identify and differentiate rangeland features. Results from reflectance curves indicated that most rangeland cover types could be preferentially distinguished using mainly wet season data, especially on the longer TM wavebands, and that range feature differentiation was more problematic on darker soils than on lighter soils. Spectral separability indexes (SSIs) confirmed that range feature separation varied considerably as a function of waveband and was more effective in the wet than the dry season. The SSIs also showed that range feature differentiation in both seasons was most effective using a combination of the chlorophyll absorpance band (TM3) and two mid-infrared bands (TM5 and TM7). Wet season data were more effectively classified in terms of range features than dry season data although some class similarity was inferred across the two classified data sets. The work shows that overall trends may be generated by comparing seasonal data sets, thereby providing an overall basis for dry season decision making. However, particular problems arise within the dry season data sets probably because of spectral similarities between shadow and darkened vegetation cover, thereby implying that further work is needed. KEY WORDS: Semiarid rangelands; Botswana; Kalahari; Spectral differentiation; Seasonal change; Darkened vegetation cover

[Protein glaucoma, a formerly unknown form of glaucoma]. / Protein-Glaukom, eine bisher unbekannte Glaukomform.

As a possible reason for a secondary glaucoma generally an unphysiological aggregation of proteins or blood in the aqueous humor is discussed. A positive Tyndall-phenomenon shows an increase of proteins in aqueous humor. We were able to demonstrate earlier that a negative Tyndall-phenomenon does not exclude this as well. In this contribution examples are given that disruption of vessel-membranes in retina and uvea lead to an increase of low molecular proteins in aqueous humor. Contrary to current knowledge we found that an overtaxing of active flow mechanisms by these additional proteins can cause a so-called protein-glucoma.

[Protein concentrations in the aqueous humor in Coats' disease (author's transl)]. / Klinische Relevanz immunochemischer Untersuchungen des Kammerwassers bei Morbus Coats.

Elevated protein concentrations in the aqueous humor, without Tyndall phenomenon, were found in a case of Coats' Disease. In particular, proteins of smaller size were involved. The permeability of the retinal vessels was presumed to be impaired. The resulting increase in protein concentrations in the aqueous humor could be the cause of the secondary glaucoma in Coats' Disease.

[A new finding concerning the secretory behavior of the lacrimal gland]. / Ein neuer Aspekt beim sekretorischen Verhalten der Tränendrüse.

Volume produced and concentrations are the most important parameters in the investigation of lacrimal fluid. Information about the secretory behavior of the lacrimal gland can only be obtained by collecting the lacrimal fluid at its point of origin. When the lacrimal fluids of locally anesthetized and untreated eyes are compared, correlating albumin concentrations and the time elapsing until a certain volume is obtained, it appears that equal quantities of such contents are produced during equal periods of time.

[Effect of aristolochic acid on herpes simplex infection of the rabbit eye]. / Experimentelle Beeinflussing der Herpes-simplex-Infektion des Kaninchen-Auges durch Aristolochiasäure.

Using the model of rabbit eye infected by Herpes simplex viruses type 1, the protective action of aristolochic acid which increases the defence mechanism against virus infections is demonstrated in comparative experiments. With an ID50 of 10(4,4)/ml the Herpes-affected epithelial lesion rate of the cornea in the treated group of animals is clearly lower than that of the group not treated. The application of aristolochic acid leads also to a more rapid healing of the lesions. The increase of the protein content in the aqueous humor which corresponds to the rise in the irritation of the iris, is significantly more pronounced in the untreated group of animals as opposed to the treated ones. The animals treated with aristolochic acid, show a clearly increased number of micro- and macrophages in the cornea and in the vitreous body, respectively.