Environment-human relationships in historical times: The balance between urban development and natural forces at Leptis Magna (Libya)

The relationships between human modification of the environment and natural events in the Roman city of Lepti Magna (UNESCO world heritage), western Libya, are analyzed. For the first time, the history of Leptis Magna is tested against a geomorphological and stratigraphical reconstruction and radiocarbon dating. Historical and archaeological interpretations or analyses indicate the occurrence of different extreme natural events as the cause of the town’s decline: earthquakes, flooding and tsunami. Geological and geomorphological surveys investigated the dynamics of the nearby Wadi Lebda, a major dryland stream that forms the depositional and erosional systems of the settlement area. Alluvial phases were studied by applying traditional stratigraphic analyses of outcrops and hand-cores. Additionally, the mapped flights of inset terrace surfaces provided insights into the human modifications of the natural depositional/erosional environment during historical times and the following alluvial phases affecting the Leptis Magna harbor. The results integrate the archaeological knowledge by providing some independent chronological constraints, and indicate that Leptis Magna history was tightly linked to the Wadi Lebda. Aware of the hazards related to devastating flooding, the Romans were able to cope with the threat posed by the wadi by performing engineering defensive hydraulic works around the town (dam and artificial channels). Once the economic decay began and the society could no longer guarantee the ongoing maintenance of these structures, the decline of the settlement started and the occurrence of destructive floods reclaimed the populated areas. Conversely, the occurrence of a large earthquake (365 CE), or of a tsunami that caused the disruption of the hydraulic systems and the infill of the harbor, has been discarded as primary cause of the decline of Leptis Magna

Environment-man relationships in historical times: the balance between urban development and natural forces at Leptis Magna (Libya).

We analyze the relationships between human modification of the environment and natural events in the Roman city of Leptis Magna (UNESCO world heritage), western Libya. For the first time the history of Leptis Magna is tested against a high resolution geo-morphological and stratigraphical reconstruction and absolute radiocarbon dating. Historical and archaeological sources indicate the occurrence of different natural events as the cause of the town decline: earthquakes, flooding, and tsunamis. Our data indicate that Leptis Magna was tightly linked to the nearby wadi. In fact, aware of the hazards related to violent flooding, the Romans were able to cope with the threat posed by the wadi by engineering defensive hydraulic works around the town. Once economic decay began and the society could no longer guarantee the ongoing maintenance of these structures, the decline of the settlement began and the occurrence of violent floods reclaimed the populated areas. The occurrence of large earthquakes, and the tsunami event that damaged the harbor have been discarded as playing a primary role in the decline of Leptis Magna

Update on tricuspid regurgitation

Although commonly detected by transthoracic echocardiography, tricuspid regurgitation (TR) has been somehow neglected, and recent data have emerged on the need for careful examination of the tricuspid valve. Functional or secondary TR is the most frequent etiology of tricuspid valve pathology in western countries and is related to tricuspid annular dilation and leaflet tethering. The prognostic role of TR associated with organic left-sided valvular heart disease is well known. However, the value of functional TR in outcome stratification of patients with advanced left ventricular dysfunction is less clear. Surgical tricuspid repair has been avoided for years, because of the misconception that TR should disappear once the primary left-sided problem is treated; this results in a large number of untreated patients with functional TR. Over the past few years, many investigators have reported evidence in favor of a more aggressive surgical approach to functional TR. Consequently, interest has been growing in the pathophysiology and treatment of functional TR. The purpose of this article is to provide a comprehensive review of TR incorporating a description of valve anatomy, etiological factors, pathophysiology, epidemiological data, natural history, clinical evaluation, along with a discussion of the important role in prognostic stratification and a summary of management guideline

Environment–human relationships in historical times: The balance between urban development and natural forces at Leptis Magna (Libya)

The relationships between human modification of the environment and natural events in the Roman city of Leptis Magna (UNESCO world heritage), western Libya, are analyzed. For the first time, the history of Leptis Magna is tested against a geomorphological and stratigraphical reconstruction and radiocarbon dating. Historical and archaeological interpretations or analyses indicate the occurrence of different extreme natural events as the cause of the town’s decline: earthquakes, flooding, and tsunami. Geological and geomorphological surveys investigated the dynamics of the nearby Wadi Lebda, a major dryland stream that forms the depositional and erosional systems of the settlement area. Alluvial phases were studied by applying traditional stratigraphic analyses of outcrops and hand-cores. Additionally, the mapped flights of inset terrace surfaces provided insights into the human modifications of the natural depositional/erosional environment during historical times and the following alluvial phases affecting the Leptis Magna harbor. The results integrate the archaeological knowledge by providing some independent chronological constraints, and indicate that Leptis Magna history was tightly linked to the Wadi Lebda. Aware of the hazards related to devastating flooding, the Romans were able to cope with the threat posed by the wadi by performing engineering defensive hydraulic works around the town (dam and artificial channels). Once the economic decay began and the society could no longer guarantee the ongoing maintenance of these structures, the decline of the settlement started and the occurrence of destructive floods reclaimed the populated areas. Conversely, the occurrence of a large earthquake (365 CE), or of a tsunami that caused the disruption of the hydraulic systems and the infill of the harbor, has been discarded as primary cause of the decline of Leptis Magn

The CarboMedics prosthetic heart valve: experience with 1,084 implants.

Background and aim of the study: The study aim was to evaluate our clinical experience with the CarboMedics heart valve prosthesis. Methods: Between October 1991 and December 2000, 942 consecutive patients (514 males, 428 females; mean age 58+/-11 years; range: 6-78 years) underwent mechanical valve implantation with the CarboMedics prosthesis. Preoperatively, 47% of patients were in NYHA class III and 22% in class IV; in addition, 134 patients (14.2%) had undergone a previous cardiac operation. Aortic valve replacement (AVR) was performed in 469 patients (49.8%), mitral valve replacement (MVR) in 330 (35.0%), double valve replacement (DVR) in 142 (15.1%), and isolated tricuspid valve replacement (TVR) in one patient. Eighty-eight patients (9.3%) underwent associated myocardial revascularization. Mean cardiopulmonary bypass and aortic cross-clamp times for the entire group were 107+/-39 min and 74+/-24 min, respectively. Results: Overall early mortality was 2.3% (6/469 AVR, 1.2%; 12/330 MVR, 3.6%; 4/142 DVR, 2.8%). Late mortality was 3.1% (n=29; including 17 cardiac deaths (10 were valve-related). Mean follow up was 66+/-31 months (range: 1-109 months), and was 98% complete yielding a total follow up of 4959 years. Actuarial survival at five years for the entire group was 89.3+/-1.6% (AVR 91.1%, MVR 86.4%, DVR 90.5%). Thromboembolism occurred in 26 patients (2.8%, 0.52%/pt-year) and major hemorrhagic events in 20 (2.1%, 0.4%/pt-year). Nine patients (0.9%) required a reoperation, in three cases (0.3%) after Staphylococcus epidermidis-mediated endocarditis. No structural deterioration occurred. Among 891 survivors, 94% of the patients are currently in NYHA classes I or II (p<0.05). Conclusion: This study confirmed the safety and reliability of the CarboMedics mechanical valve prosthesis, even in old age groups. This bileaflet prosthesis showed no structural deterioration, and a low incidence of overall complications

Environment-man relationships in historical times: the balance between urban development and natural forces at Leptis Magna (Libya).

We analyze the relationships between human modification of the environment and natural events in the Roman city of Leptis Magna (UNESCO world heritage), western Libya. For the first time the history of Leptis Magna is tested against a high resolution geo-morphological and stratigraphical reconstruction and absolute radiocarbon dating. Historical and archaeological sources indicate the occurrence of different natural events as the cause of the town decline: earthquakes, flooding, and tsunamis. Our data indicate that Leptis Magna was tightly linked to the nearby wadi. In fact, aware of the hazards related to violent flooding, the Romans were able to cope with the threat posed by the wadi by engineering defensive hydraulic works around the town. Once economic decay began and the society could no longer guarantee the ongoing maintenance of these structures, the decline of the settlement began and the occurrence of violent floods reclaimed the populated areas. The occurrence of large earthquakes, and the tsunami event that damaged the harbor have been discarded as playing a primary role in the decline of Leptis Magna.Submitted3.10. Storia ed archeologia applicate alle Scienze della TerraJCR Journalope