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  • 1
    Electronic Resource
    Electronic Resource
    Biomanipulation of lake ecosystems: an introduction (2002)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 47 (2002), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. This paper is an introduction to a special issue of Freshwater Biology containing selected papers from an international symposium on Food Web Effects of Fish in Lake Ecosystems: Research Progress, Water Quality and Fisheries Management held from 31 May to 3 June 2000 in Rheinsberg, Germany. The primary goal of the workshop was to enlarge the current view of fish-induced effects on lake ecosystems. An additional goal was to promote biomanipulation as a multiple-use tool for managing freshwater ecosystems.2. The three main topics addressed at the workshop were: (i) mechanisms involved in biomanipulation, (ii) whole-lake case studies and (iii) management aspects in water quality and fisheries.3. Mortality of Daphnia, nutrient recycling, habitat selection and fish predation are reported as important mechanisms governing food-web effects as a result of biomanipulation.4. Whole-lake case studies indicate that repeated fish removal can help improve water quality of shallow lakes, but successful biomanipulation of deep, thermally stratifying lakes remains difficult.5. In many cases, biomanipulation of lakes has proved to provide benefits in addition to improving water quality. As all lake users are potentially affected when biomanipulation is used as a lake management tool, their concerns need to be clearly recognised if biomanipulation is to be successful in practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2002.01001.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Karotisendarteriektomie und Karotisstenting Pilotstudie eines prospektiven, randomisierten und kontrollierten Vergleichs (2000)
    Springer
    Der Radiologe 40 (2000), S. 813-820 
    Details
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Karotisstenose ; Karotisstenting ; Endarteriektomie ; Prospektive, randomisierte und kontrollierte Studie ; Keywords Carotid artery stenosis ; Carotid stenting ; Endarterectomy ; Prospective, randomized and controlled study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Introduction. A prospective, randomized and controlled trial is conducted to compare carotid endarterectomy and carotid stenting in high grade symptomatic carotid artery stenoses. Methods. According to the study design symptomatic patients with a angiographically highgrade (≥70%) internal carotid artery stenosis are included. Pre- and postinterventional diagnostics during the hospitalization period includes neurological assessment, duplex sonography of the cervical and cerebral arteries and magnetic resonance imaging of the brain. Follow-up examinations are scheduled after 1, 6 and 12 months and consist of a neurological assessment and duplex sonography. After 12 months selective angiography and magnetic resonance imaging of the brain will be performed additionally. During a period of 9 months up to now 23/137 patients treated for a carotid artery stenosis were included in the study, 11 patients underwent surgery and 12 patients carotid stenting. Results. Carotid stenting and endarterectomy was primarily successful without residual stenosis 〉30% in each patient without the occurence of stroke or death. In 18 follow-up examinations (neurological assessment including duplex sonography) of 13 patients (13 follow-up examinations after 30 days, 5 after 6 months) no relevant restenosis and no stroke occured. Conclusion. As of yet, carotid stenting was a safe procedure. Due to the small number of patients a definitive conclusion can not be drawn.
    Notes: Zusammenfassung Fragestellung. In einer prospektiven, randomisierten und kontrollierten Pilotstudie werden die Karotisendarteriektomie und die Stenttherapie an einem Patientenkollektiv mit hochgradigen, symptomatischen Stenosen der extrakraniellen A. carotis interna miteinander verglichen. Methodik. Das Design der Studie sieht vor, dass symptomatische Patienten mit der Diagnose einer hochgradigen Stenose (≥70%) der A. carotis interna, die auf dem Boden einer DSA gesichert wurde, eingeschlossen werden. Vor und nach der Therapie finden während der Hospitalisationsphase jeweils eine klinisch-neurologische Untersuchung, eine Duplexsonographie der Hals- und Hirngefäße und eine MRT des Hirns statt. Das Nachsorgeprotokoll nach 1, 6 und 12 Monaten beinhaltet jeweils eine klinisch-neurologische Untersuchung und eine Duplexsonographie sowie nach 12 Monaten zusätzlich eine selektive Angiographie der behandelten Seite und eine weitere MRT des Hirns. Während eines Zeitraums von 9 Monaten wurden bisher 23 von 137 wegen einer Karotisstenose behandelten Patienten in die Studie eingeschlossen, wobei 11 Patienten dem operativen Arm und 12 Patienten dem interventionellen Arm der Studie zugeführt wurden. Ergebnisse. Bei allen 23 Patienten wurde ein Primärerfolg ohne residuelle Stenose 〉30% erzielt, eine zerebrale Ischämie oder Todesfall traten nicht auf. Die bislang durchgeführten 18 Nachuntersuchungen (neurologische Untersuchung einschließlich Duplexsonographie) bei insgesamt 13 Patienten (13 Kontrollen nach 30 Tagen, 5 Kontrollen nach 6 Monaten) ergaben keine relevante Restenosierung und keine zerebrale Ischämie. Schlussfolgerung. Bislang erwies sich die Stenttherapie in unserer Studie als komplikationsarmes Therapieverfahren. Aufgrund der geringen Patientenzahl kann zum jetzigen Zeitpunkt jedoch noch keine endgültige Bewertung erfolgen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050828
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  • 3
    Electronic Resource
    Electronic Resource
    70. Morbidität und Mortalität nach der Resektion des Aortenaneurysmas im Alter (1986)
    Springer
    Langenbeck's archives of surgery 369 (1986), S. 349-353 
    Details
    ISSN: 1435-2451
    Keywords: Aortic aneurysm ; High age ; Mortality ; Morbidity ; Aortenaneurysma ; Hohes Alter ; Mortalität ; Morbidität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Von August 1984–August 1985 wurden am Klinikum Nürnberg 118 abdominelle Aortenaneurysmen operiert. Das Durchschnittsalter betrug 68,9 Jahre, 26,3% der Patienten waren über 75 Jahre. Die Elektivoperationen waren in der höchsten Altersgruppe deutlich rückläufig; kardiale Rhythmusstörungen und renale Insuffizienz waren die häufigsten Risikofaktoren. Die Letalität bei Elektiveingriffen war 0%, 50% bei symptomatischen and 〉 50% bei perforierten Aneurysmen im hohen Alter. Die hohe Letalität im Stadium der Ruptur rechtfertigt den Elektiveingriff bei Aortenaneurysmen im hohen Alter.
    Notes: Summary From August 1984–August 1985 118 abdominal aortic aneurysms were treated surgically in the City Hospital Nuremberg. The mean age was 68.9 years, with 26.3% being over 75 y.; and there was a notable decline of elective procedures in this group, which was particularly jeopardized by cardial arrhythmias and renal insufficiency. The lethality was 0 in elective procedures, but reached 50% for symptomatic and over 50% for perforated aneurysms in the old age group. The high lethality of ruptured aortic aneurysms justify elective operation of aortic aneurysms in high age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01274387
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  • 4
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    Assessing resilience in long-term ecological data sets (2016)
    ELSEVIER SCIENCE BV
    In:  EPIC3Ecological Indicators, ELSEVIER SCIENCE BV, 65, pp. 10-43, ISSN: 1470-160X
    Details
    Publication Date: 2016-03-17
    Description: In this paper the concept of resilience is discussed on the base of 13 case studies from the German branch of the International Long-Term Ecological Research Program. In the introduction the resilience approach is presented as one possibility to describe ecosystem dynamics. The relations with the concepts of adaptability and ecological integrity are discussed and the research questions are formulated. The focal research objectives are related to the conditions of resilient behaviour of ecosystems, the role of spatio-temporal scales, the differences between short- or long-term dynamics, the basic methodological requirements to exactly define resilience, the role of the reference state and indicators and the suitability of resilience as a management concept. The main part of the paper consists of 13 small case study descriptions, which demonstrate phase transitions and resilient dynamics of several terrestrial and aquatic ecosystems at different time scales. In the discussion, some problems arising from the interpretation of the time series are highlighted and discussed. The topics of discussion are the conceptual challenges of the resilience approach, methodological problems, the role of indicator selection, the complex interactions between different disturbances, the significance of time scales and a comparison of the case studies. The article ends with a conclusion which focuses on the demand to link resilience with adaptability, in order to support the long-term dynamics of ecosystem development.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Monitoring of Calcite Precipitation in Hardwater Lakes with Multi-Spectral Remote Sensing Archives (2017)
    In:  Water
    Details
    Publication Date: 2020-02-12
    Description: Calcite precipitation is a common phenomenon in calcium-rich hardwater lakes during spring and summer, but the number and spatial distribution of lakes with calcite precipitation is unknown. This paper presents a remote sensing based method to observe calcite precipitation over large areas, which are an important prerequisite for a systematic monitoring and evaluation of restoration measurements. We use globally archived satellite remote sensing data for a retrospective systematic assessment of past multi-temporal calcite precipitation events. The database of this study consists of 205 data sets that comprise freely available Landsat and Sentinel 2 data acquired between 1998 and 2015 covering the Northeast German Plain. Calcite precipitation is automatically identified using the green spectra and the metric BGR area, the triangular area between the blue, green and red reflectance value. The validation is based on field measurements of CaCO3 concentrations at three selected lakes, Feldberger Haussee, Breiter Luzin and Schmaler Luzin. The classification accuracy (0.88) is highest for calcite concentrations ≥0.7 mg/L. False negative results are caused by the choice of a conservative classification threshold. False positive results can be explained by already increased calcite concentrations. We successfully transferred the developed method to 21 other hardwater lakes in Northeast Germany. The average duration of lakes with regular calcite precipitation is 37 days. The frequency of calcite precipitation reaches from single time detections up to detections nearly every year. False negative classification results and gaps in Landsat time series reduce the accuracy of frequency and duration monitoring, but in future the image density will increase by acquisitions of Sentinel-2a (and 2b). Our study tested successfully the transfer of the classification approach to Sentinel-2 images. Our study shows that 15 of the 24 lakes have at least one phase of calcite precipitation and all events occur between May and September. At the lakes Schmaler Luzin and Feldberger Haussee, we illustrated the influence of ecological restoration measures aiming at nutrient reduction in the lake water on calcite precipitation. Our study emphasizes the high variance of calcite precipitation in hardwater lakes: each lake has to be monitored individually, which is feasible using Landsat and Sentinel-2 time series.
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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