Using image-based modelling (SfM-MVS) to produce a 1935 ortho-mosaic of the Ethiopian highlands

Approximately 34,000 aerial photographs covering large parts of Ethiopia and dating back to 1935-1941 have been recently recovered. These allow investigating environmental dynamics for a past period that until now is only accessible from terrestrial photographs or narratives. As the archive consists of both oblique and vertical aerial photographs that cover rather small areas, methods of image-based modelling were used to orthorectify the images. In this study, 9 vertical and 18 low oblique aerial photographs were processed as an ortho-mosaic, covering an area of 25 km(2), west of Wukro town in northern Ethiopia. Using 15 control points (derived from Google Earth), a Root Means Square Error of 28.5 m in X 35.4 m in Y were achieved. These values can be viewed as optimal, given the relatively low resolution and poor quality of the imagery, the lack of metadata, the geometric quality of the Google Earth imagery and the recording characteristics. Land use remained largely similar since 1936, with large parts of the land being used as cropland or extensive grazing areas. Most remarkable changes are the strong expansion of the settlements as well as land management improvements. In a larger effort, ortho-mosaics covering large parts of Ethiopia in 1935-1941 will be produced

Cardiac ochronosis: not so benign

A 78-year-old patient with ochronosis has developed symptomatic aortic stenosis. He has undergone an aortic valve replacement that was highly complicated by a severe aortic calcification. The right coronary artery was sacrificed and bypassed in order to control a massive aortic root haemorrhage. The patient has presented a sternal dehiscence that required surgical revision. The sternal frailty was related to chronic corticotherapy in a patient with chronic spondylarthrosis. Cardiac ochronosis in the elderly may be associated to surgical complications related to severe aortic root calcifications and chronic corticotherapy for arthropathies. © 2008 European Association for Cardio-Thoracic Surgery.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Obstructive teratoma in the right ventricle of a newborn: A case report

Background: A newborn was diagnosed by echocardiogram with an asymptomatic cardiac mass in the right ventricle after a systolic cardiac murmur was detected at birth. Case presentation: Nine days after birth, the newborn presented with three syncopal episodes and oxygen desaturation which required resuscitation. The mass induced a complete right ventricular outflow tract obstruction. The presence of a patent foramen oval and a patent ductus arteriosus explained the absence of symptoms at birth. Surgery was rapidly considered since the situation was life threatening. The tumor was successfully resected. The mass was a mature teratoma confirmed by microscopic examination, illustrated by pictures and video. Conclusions: This case was unique because of the absence of symptoms in the first 9 days of the newborn's life even though symptoms should have mounted due to the obstruction postpartum. The delay was correlated to the closure of the patent ductus arteriosus. It is recommended that newborns with any cardiac mass be followed up regularly due to hemodynamic changes at birth.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Ethiopia in the 1930s: historical aerial photographs and their fusion with current remotely sensed imagery for retrospective landscape analysis

The aerial photographs (APs) acquired by the 7a Sezione Topocartografica during the Italian occupation of Ethiopia (1935-1941) have recently been discovered, scanned and organised. The oldest APs of the country that are known so far were taken in the period 1958-1964. The APs over Ethiopia in 1935-1941 are presented as assemblages on approx. 50 cm x 20 cm cardboard tiles, each holding a label, one nadir-pointing photograph flanked by two low-oblique photographs and one high-oblique photograph. The four APs were exposed simultaneously and were taken across the flight line; the high-oblique photograph is presented alternatively at left and at right; there is approx. 60% overlap between subsequent sets of APs. One of Santoni’s glass plate multicameras was used, with focal length of 178 mm, flight height at 4000-4500 m a.s.l., which results in an approximate scale of 1:11 500 for the central photograph and 1:16 000 to 1:18 000 for the low-oblique APs. The surveyors oriented themselves with maps of Ethiopia at 1:400 000 scale, compiled in 1934. The flights present a dense AP coverage of Northern Ethiopia, where they were acquired in the context of upcoming battles with the Ethiopian army. Several flights preceded the later advance of the Italian army southwards towards the capital Addis Ababa. Further flights took place in central Ethiopia for civilian purposes. As of 1936, the APs were used to prepare highly detailed topographic maps at 1:100 000 scale. These APs (1935-1941) together with APs of 1958- 1964, 1994 and recent high-resolution satellite imagery are currently being used in spatially explicit change studies of land cover, land management and (hydro)geomorphology in Ethiopia over a time span of almost 80 years, the first results of which will be presented