RESUMO
Following recent tsunamis, most studies have focused on the onshore deposits, while the offshore backwash deposits, crucial for a better understanding of the hydrodynamic processes during such events and offering an opportunity for sedimentary archives of past tsunamis, have mostly been omitted. Here, we present a unique sedimentary record of the backwash from two historical tsunamis sampled in a sheltered bay in American Samoa, namely the 2009 South Pacific Tsunami and the 1960 Great Chilean Earthquake Tsunami. Although not always concomitant with a marked grain size change, backwash deposits are identified by terrestrial geochemical and mineralogical signatures, associated with basal soft sediment micro-deformations. These micro-deformations, including asymmetric flame structures, are described for the first time in historic shallow marine backwash deposits and lead us to propose an improved depositional mechanism for tsunami backflow based on hyperpycnal currents. Moreover, this study brings a potential new criterion to the proxy toolkit for identifying tsunami backwash deposits, namely the basal soft sediment micro-deformations. We suggest that further studies focus on these micro-deformations in order to test the representability of this criterion for tsunami backwash deposits. Sheltered shallow marine environments in areas repeatedly impacted by tsunamis have a higher potential for the reconstruction of paleo-tsunami catalogs and should be preferentially investigated for coastal risk assessment.
RESUMO
Calcium is vital to many biologic processes. In skin, it has a profound effect on keratinocyte proliferation, differentiation, and cell-cell adhesion. Serum calcium is tightly regulated by parathyroid hormone and 1,25(OH)2D3. Despite this careful regulation, calcification and ossification of cutaneous and subcutaneous tissues may occur. Cutaneous calcification may be divided into four major categories: dystrophic, metastatic, idiopathic, and iatrogenic. Dystrophic calcification occurs as a result of local tissue injury or abnormalities. Metastatic calcification results from abnormal calcium and/or phosphate metabolism. Virtually any process that calcifies may secondarily ossify. Primary ossification may rarely occur.
Assuntos
Humanos , Calcinose/etiologia , Calcinose/fisiopatologia , Calcinose/patologia , Cálcio/fisiologia , Dermatopatias/etiologia , Dermatopatias/fisiopatologia , Dermatopatias/patologiaRESUMO
KIE: Institute of Medicine members Alfred Gellhorn and Robert Lawrence visited El Salvador in January as observers for the American Association for the Advancement of Science, the National Academy of Sciences, the New York Academy of Sciences, and the International League for Human Rights. Their findings paralleled those of an earlier delegation--"a virtually complete breakdown of the health system" and continuing violence against health professionals. A number of scientific organizations in the U.S. are reported to be exploring ways to channel private aid from health professionals and to protect the rights of patients and health personnel without antagonizing the government of El Salvador.^ieng