Sedimentological, geomorphological and geochronological studies on Holocene tsunamis in the Lefkada / Preveza area (NW Greece) and their implications for coastal evolution

Research on palaeo-tsunami and palaeo-extreme wave events aims to provide new data about former events and is of remarkable importance in the eastern Mediterranean. In general, coastal geomorphology and fine-grained near-coast geological archives store information about coastal changes over medium to long timescales, as well as short, episodic processes such as palaeo-tsunami events. In the eastern Mediterranean and particularly for the Ionian Sea and the Lefkada / Preveza coastal zone (NW Greece), strong seismic activity and a high tsunamigenic potential are evident. Thus, comprehensive geo-scientific investigations were carried out in the Lefkada / Preveza coastal zone in order to decipher coastal change throughout time, and thereby detect, verify and date the influence of tsunami events on the coastal system and coastal evolution. Herein, particular focus was set on the distinguishability of event deposits in the geological record and the evaluation of event recurrence rates - an issue of major importance in extreme wave event research. In a first step, detailed analysis of the geomorphological and geomorphodynamic situation in the study area revealed several major disturbances of the coastal system, which mark episodically occurring major impulses of coastal evolution, entailing the recurrent reorganization of coastal balance. In a second step, comprehensive geo-scientific investigations on the main near-coast geological archives provided insight into the palaeogeographical evolution and the palaeo-event history of the Lefkada / Preveza area. In the sedimentary record of the Phoukias sand spit and the washover-dominated northern Lefkada Lagoon, distinct event deposits were identified. These event deposits provide a linkage to the inferred disturbances of the coastal system and allow the dating of the main impulses in coastal evolution. Detailed analyses of the event deposits - comprising sedimentological, microfaunal and geochemical investigations as well as the interpretation of the regional geomorphologic and geographic context - strongly suggest a tsunamigenic origin of the encountered event deposits, proving the significant impact of tsunamis on the coastal system. Moreover, numerous block and boulder fields were mapped along the coastline and equally point to the impact of high energy wave events. Altogether, four major tsunamigenic disturbances were identified throughout the late Holocene. These disturbances were dated to ~1000 BC, to at around or after 300 BC and, for the main washover structures in the northern Lagoon of Lefkada, to at around or after 300 AD, the latter event most likely triggered by the 365 AD earthquake off western Crete and the related tsunami. During the younger history of coastal evolution a fourth disturbance occurred sometime before 1850 AD. In addition to the detected 365 AD event, the presented findings fit well to previous investigations in adjacent coastal zones. From a geomorphological and geomorphodynamic point of view, the major tsunami events involved the breakdown of former coastlines (the Plaka), the formation of the Phoukias sand spit and the onset of intense coastal erosion in western Aktium Headland. Moreover, the inferred tsunami events contributed to the formation of block and boulder fields, induced the evolution of ridge structures in the northern part of the Phoukias sand spit and triggered the formation of at least one, probably two washover generations in the northern Lefkada Lagoon. The episodic occurrence of tsunami events was thus responsible for the formation of major geomorphological structures and modifications of the coastal system, which are recurrently masked and mimicked by long term, gradually operating coastal processes. These marked geomorphic changes provide clear evidence that tsunami-induced disturbances exert a major control on the evolution of the coastal system in the study area. In conclusion, this study presents new geo-scientific evidence of extreme wave event deposits and will thereby expand the regional and global data pool of palaeo-event and particularly palaeo-tsunami deposits. Moreover, it contributes to ongoing research concerned with the detection of extreme wave event deposits in near-coast geological archives, ultimately enabling an improved understanding of type and degree of their impact on the evolution of coastal systems

Testing the accuracy of feldspar single grains to date late Holocene cyclone and tsunami deposits

Quartz is the preferred dosimeter for luminescence dating of Holocene sediments as optically stimulated luminescence (OSL) signals reset rapidly upon light exposure, and are stable over time. However, feldspar is required where quartz luminescence properties are inappropriate for dating, as is often the case in geologically young mountain ranges and areas with young volcanism. Here we aim to evaluate the potential of single grain feldspar luminescence dating applied to late Holocene cyclone and tsunami deposits, for which complete signal resetting can a priori not be guaranteed. To address potential problems of feldspar dating of such deposits associated with heterogeneous bleaching, remnant doses and anomalous fading, we use a low-temperature post infrared infrared stimulated luminescence protocol (pIRIR150) on single grains. For most samples, good agreement between fading corrected IR50 and non-fading corrected pIRIR150 ages is observed. Both feldspar ages generally also show good agreement with age control provided by historical data and quartz luminescence ages. pIRIR150 remnant ages in modern analogue samples are shown to be 150, IR50 and quartz ages, indicates that a significant number of grains must have experienced relatively complete signal resetting during or immediately prior to transport, as the three signals are known to bleach at different rates. Since light exposure during the event is expected to be limited, we deduce that a significant portion of the grains in the cyclone and tsunami deposits was already bleached prior to the event of interest. These well-bleached grains were likely eroded at the beach, while other grains with larger remnant ages probably originate from the shallow subtidal, coastal barriers or even further inland sources. Additional signal resetting during storm and tsunami transport is indicated by slightly younger quartz than feldspar ages for grains with incomplete pre-transport resetting that were eroded at the Holocene coastal barrier.</p

Holocene coastal stratigraphy, coastal changes and potential palaeoseismological implications inferred from geo-archives in Central Chile (29–32° S)

Coastal geomorphology and the stratigraphy of coastal geoarchives record past coastal and fluctuations of coastal environments. In addition, these archives potentially store traces of past extreme events such as earthquakes and tsunamis, severe storms, and major flfl oodings of the coastal hinterland, e.g. due to El Niño conditions. Studying their characteristics may thus improve the knowledge of past frequency and magnitude patterns of such extreme events. For instance, large scaled spatial information about past earthquakes is needed for the understanding and estimation of seismo-tectonic processes. Misinterpretations in the size of preceding earthquakes may lead to incorrect strain balance estimations along megathrusts. Thus, fundamental research on the occurrence of past earthquakes is needed, which can be reflected in sudden or long-term coastal changes. Using sedimentological, geomorphological and microfaunal evidence, coeval geomorphodynamic and palaeoenvironmental changes at four different locations between 29° 50′ and 32° 20′ S in Central Chile were identififi ed in estuary systems, coastal swamps and coastal plains. The results may represent possible indirect evidence for palaeoseismicity, affecting the coastal system by vertical tectonic movements. Changes of coastline elevation, morphodynamic activity and/or coastal environments, as well as the formation of a liquefaction layer took place during the last c. 400 years. Moreover, major flfl ooding events related to strong El Niño conditions are assumed to have influenced the coastal stratigraphy by depositing high energy fluvial deposits. Our results suggest that the coastal environment, geomorphology and stratigraphy are considerably inflfl uenced by tectonic processes in the study area; a relation of the presented fifi ndings to the 1730 Great Valparaíso Earthquake is assumed. In general, the findings may encourage the implementation of comparable detailed studies, which may ultimately contribute to a better understanding of the Holocene coastal evolution and its relation to palaeoseismicity in Central Chile

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Quantitative T2 Mapping Shows Increased Degeneration in Adjacent Intervertebral Discs Following Kyphoplasty

Objective A minimally invasive treatment of osteoporotic and nonosteoporotic thoracic and lumbar spine fractures is cement augmentation (kyphoplasty). Little is known about the impact on adjacent intervertebral discs. A quantitative magnetic resonance imaging (MRI) approach in addition to morphological MRI is desirable to evaluate changes in the intervertebral disc. Our study aims to evaluate the feasibility of T2 mapping for the detection of subtle changes in the intervertebral discs in spines after kyphoplasty. Design Intervertebral discs were assessed by quantitative MRI (3.0 T) using T2 relaxation time mapping. Region of interest (ROI; 6 per disc) analyses were performed. The ROIs at the anterior and posterior edges were interpreted as annulus fibrosus (AF). The 2 very inner zones were regarded as nucleus pulposus (NP) and the regions in between as intermediate transition zone. We compared T2 relaxation time values of intervertebral discs adjacent to the vertebrae after kyphoplasty with those nonadjacent to vertebrae after kyphoplasty, especially in the NP. Results The analysis of the ROIs showed that the intervertebral discs of the adjacent vertebral segments are associated with reduced T2 values compared to those that are nonadjacent to the affected vertebrae. Conclusion This study is to our knowledge the first investigation of intervertebral discs after kyphoplasty by quantitative MRI. Quantitative T2 mapping shows increased degeneration in adjacent intervertebral discs following kyphoplasty. Besides its contribution to a broader knowledge of postoperative changes after kyphoplasty, our findings may help to improve differentiation between healthy and degenerated intervertebral discs using these techniques

The Bronze Age occupation of the Black Sea coast of Georgia—New insights from settlement mounds of the Colchian plain

Along the lower course of the Rioni and several minor rivers, more than 70 settlement mounds (local name: Dikhagudzuba) have been identified by field surveys and remote sensing techniques. They give evidence of a formerly densely populated landscape in the coastal lowlands on the Colchian plain (western Georgia) and have been dated to the Bronze Age. As yet, limited information is available on their internal architecture, the chronology of the different layers and their palaeoenvironmental context. Based on archaeological sources, remote sensing measurements of three mounds and sediment cores from one mound and its closer surroundings, our study presents a review of the relevant literature and reveals the internal structure, distribution and spatial extent of the mounds. Geochemical and sedimentological analyses of element contents (X‐ray fluorescence) and granulometry helped to identify different stratigraphical layers and differentiate between natural facies and anthropogenic deposits; using the Structure‐from‐Motion technique the mounds' dimensions were calculated. The studied settlement mounds had relatively small dimension (varying from 30 to 100 m in diameter) and were similar in their stratigraphy. Measurement of elements that can identify types of human activity, notably metals and phosphorus, suggest changing intensities of human occupation, pastoral agriculture and metalworking through the occupation sequence. According to the 14C chronology, the formation of the settlements occurred during the first half of the second millennium B.C., which confirms the archaeological interpretation of their Bronze Age origin. The narrow age difference between the lowermost and uppermost anthropogenic layers indicates an intentional construction of the mounds, rather than a successive accumulation of construction debris due to the disintegration of loam bricks by weathering. Therefore, they are indeed mounds and not tells. It is most likely that the characteristic circular moats that surround them were the source of their construction material. Fluvial and alluvial processes in a warm and humid climate dominated the environment of the mounds

Mutations and Deregulation of Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR Cascades Which Alter Therapy Response

The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Certain components of these pathways, RAS, NF1, BRAF, MEK1, DUSP5, PP2A, PIK3CA, PIK3R1, PIK3R4, PIK3R5, IRS4, AKT, NFKB1, MTOR, PTEN, TSC1, and TSC2 may also be activated/inactivated by mutations or epigenetic silencing. Upstream mutations in one signaling pathway or even in downstream components of the same pathway can alter the sensitivity of the cells to certain small molecule inhibitors. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of components of these cascades can contribute to: resistance to other pathway inhibitors, chemotherapeutic drug resistance, premature aging as well as other diseases. This review will first describe these pathways and discuss how genetic mutations and epigenetic alterations can result in resistance to various inhibitors

Classification of Salmonella enterica of the (Para-)Typhoid Fever Group by Fourier-Transform Infrared (FTIR) Spectroscopy

Typhoidal and para-typhoidal Salmonella are major causes of bacteraemia in resource-limited countries. Diagnostic alternatives to laborious and resource-demanding serotyping are essential. Fourier transform infrared spectroscopy (FTIRS) is a rapidly developing and simple bacterial typing technology. In this study, we assessed the discriminatory power of the FTIRS-based IR Biotyper (Bruker Daltonik GmbH, Bremen, Germany), for the rapid and reliable identification of biochemically confirmed typhoid and paratyphoid fever-associated Salmonella isolates. In total, 359 isolates, comprising 30 S. Typhi, 23 S. Paratyphi A, 23 S. Paratyphi B, and 7 S. Paratyphi C, respectively and other phylogenetically closely related Salmonella serovars belonging to the serogroups O:2, O:4, O:7 and O:9 were tested. The strains were derived from clinical, environmental and food samples collected at different European sites. Applying artificial neural networks, specific automated classifiers were built to discriminate typhoidal serovars from non-typhoidal serovars within each of the four serogroups. The accuracy of the classifiers was 99.9%, 87.0%, 99.5% and 99.0% for Salmonella Typhi, Salmonella Paratyphi A, B and Salmonella Paratyphi C, respectively. The IR Biotyper is a promising tool for fast and reliable detection of typhoidal Salmonella. Hence, IR biotyping may serve as a suitable alternative to conventional approaches for surveillance and diagnostic purposes