85 research outputs found
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Sedimentary and environmental characteristics of the Gilan-Mazenderan plain, northern Iran: Influence of long- and short-term Caspian water level fluctuations on geomorphology
The south-southwestern Caspian coastal lowland in Iran, or the Gilan-Mazenderan plain, is a relatively narrow but long, composite depositional area of late Quaternary age. The Sefid Rud delta, the Anzali Lake (connected to the Caspian Sea by a meandering outlet 3.5 km long) and storm-dominated beaches are its prominent sedimentary features. They are controlled by the present water level of the Caspian Sea at -26.36 m in 2000. The Late Pleistocene-Holocene deposits of the lowland, which are covered commonly by a modern loess-origin soil, mainly consist of alternations of marine and non-marine sediments. The marine units form coastal terraces at 19-20 m (I), 2-0 m (II) and –6/-8 m (III) corresponing to the Late Khvalinian and Neocaspian transgressions. The deposits of the youngest terrace (terrace III) that represents a prograding beach-ridge complex are a consequence of several medium-term, cyclic water level oscillations in Late Holocene. Just after the initiation of the beach-ridge complex, Lake Anzali formed by damming of rivers and then by progradation of the complex in time forced to form the outlet of the lake. The nearest medium-term cycle lasted c. 65 years between 1930-1995 and the records showed that it included a lot of short-term (c. 4-5 yrs) and very short-term (week to months) water level oscillations. During the last erratic rise of sea level (1977-1996), the area of Lake Anzali doubled; the delta and the coastal sands including modern beaches were eroded on c. 30-100 m. Overall, a step-like morphology, repetition of marine and non-marine facies and also water level records of the last 75 years indicate that the ancient and recent deposition on the coastal lowland has been controlled by long- medium- and short-term fluctuations of the Caspian Sea level
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Late Holocene erosion in NW Anatolia from sediments of Lake Manyas, Lake Ulubat and the southern shelf of the Marmara Sea, Turkey
This paper deals with modern and ancient sedimentation in fresh water lakes and the marine shelf of the southern Marmara region, NW Anatolia, Turkey. Most of the information has been obtained from monitoring of suspended load discharged into two lakes (Manyas and Ulubat) in the last 45 years and from 8-11 m thick lacustrine sediments, in addition to radiocarbon-dated shelf sediments. This allows a holistic approach to the drainage basin denudation over time. The results show that the sedimentation rates in the lakes were low 0. 22 cm.yr-1, from 4000-2000 yr BP and then they increased (0.29 cm.yr-1) up to sub-recent times and reached 0.44 cm.yr-1 in the last century. It is suggested that deforestation created high rates of sedimentation in the basins and/or strong denudation of the region during the Late Holocene. This study also shows that for shallow freshwater lakes the calculation of sedimentation rates must include fine particles lost by the outlets and coarse-grained bed load deposited on their shores. In addition, a high rate of sedimentation has been created by short, but repetitive intense depositions. During the last century particularly during the last 45 years the rate of sedimentation or denudation has increased dramatically in NW Turkey. The two World Wars and mismanagement of the land had important local effects by increasing deforestation and resulting in the present erosive conditions
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Boron content of Lake Ulubat sediment: A key to interpret the morphological history of NW Anatolia, Turkey
Freshwater Lake Ulubat (c. 1.5 m deep and c. 138 km2) receives sediment from a 10.414 km2 area in the seismically active Susurluk Drainage Basin (SDB) of NW Turkey. The B and trace element contents of the lake infill seem to be a link between the fresh landforms of the SDB and the lacustrine sediment. Deposition in Lake Ulubat has been 1.60 cm.a-1 for the last 50 a according to radionucleides; however the sedimentation rate over the last millennium was 0.37 cm.a-1 based on 14C dating. The B content of the lacustrine infill displays a slight increase at 0.50 m and a drastic increase at 4 m depth occurring c. 31 a and c. 1070 a ago respectively. Probably the topmost change corresponds to the start of open mining in the SDB and the second one to the natural trenching of borate ore-deposits. These dates also show indirectly a 1.4 cm.a-1 erosion rate during the last millennium as the borate beds were trenched up to 15 m. By extrapolation, it is possible to establish that the formation of some of the present morphological features of the southern Marmara region, especially river incision, began in the late Pleistocene, and developed especially over the last 75 ka
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Wind control on the accumulation of heavy metals in sediment of Lake Ulubat, Anatolia, Turkey
Freshwater Lake Ulubat (zmean = 1.5-2.0 m and Area = ~138 km2), NW Anatolia, Turkey was filled in by fine-to-medium-grain silts during the late Holocene. Deposition in Lake Ulubat has been 1.6 cm yr-1 for the last 50 years, but the sedimentation rate over the last ~1,600 years was lower (0.37 mm yr-1). The organic matter and carbonate contents of the infill show cyclic changes that reflect environmental fluctuations. The silt-dominated lithology and the vertically uniform heavy metal distributions are probably due to wind-controlled sedimentation in the lake. Heterogeneous mud, derived from a large, mountainous drainage basin, is deposited in the lake mostly during summer, June to October, when conditions are hot and calm. Winter months are stormier and sediments are re-suspended due to the shallow water depth and the effect of waves on the lake bottom. It is likely that re-suspended sediments, particularly fine-grained particles, together with the heavy metals, are transported out of the lake via the outlet, especially during periods of high lake level. This resuspension and removal process probably caused the lake sediments to become silt-dominated and depleted in heavy metals. The role of broad shallow lakes in sequestering sediments and heavy metals can be described more accurately when wind data are considered. Such information may also be helpful for land-use planning in downstream areas
Para politikası araçları ve makro ihtiyati tedbirlerin kredi büyümesi üzerine etkileri: banka büyüklüğü ve kredi türünün önemi
Bu çalışmada, Türk bankacılık sektörü bilanço verisi kullanılarak, 2002Ç4-2015Ç1 döneminde uygulanan para politikası araçları ve makro ihtiyati politikaların kredi büyümesi üzerindeki etkileri panel veri tahmin yöntemiyle incelenmektedir. Söz konusu etkiler, önceki çalışmalardan farklı olarak, banka büyüklüğü ve kredi türü ayrımında ele alınmaktadır. Çalışmanın bu ayrım gözetilerek yapılmasının nedeni, uygulanan para politikası araçları ve makro ihtiyati tedbirlerin, büyük ve küçük bankaların aktif ve pasif kompozisyonunda görülen farklılıklar nedeniyle, kredi türüne de bağlı olarak, kredi büyüme oranları üzerinde asimetrik bir etki yaratma olasılığıdır. Tahmin sonuçları, politika faizindeki 1 yüzde puan artışla ifade edilebilecek daha sıkı bir para politikası duruşunun, büyük bankaların toplam kredi büyümesini 0,46-0,49 yüzde puan, bireysel kredi büyümesini ise 0,88-0,94 yüzde puan azalttığını göstermektedir. Buna karşılık, bulgular, daha sıkı bir makro ihtiyati politika duruşunun, küçük bankaların toplam, bireysel ve ticari kredi büyüme oranlarını yavaşlattığına, büyük bankaların ise sadece bireysel kredi büyüme oranlarında düşüşe neden olduğuna işaret etmektedir.This study analyzes the effects of monetary policy tools and macro prudential measures on credit growth during 2002Q4-2015Q period by using Turkish banking sector balance sheet data and panel data estimation methods. Unlike earlier studies, these effects are examined with an asset size and credit type breakdown. This breakdown is necessary as the differences observed between big and small banks with respect to their asset and liability composition can cause monetary and macro prudential policies to have asymmetric effects on credit growth rates, depending on the credit type. The estimation results show that a tighter monetary policy manifested by 1 percentage point increase in the policy rate reduces total credit growth rate of big banks by 0.46-0.49 percentage points while the consumer credit growth of big banks declines by 0.88-0.94 percentage points. On the other hand, a tighter macro prudential policy slows down credit growth of small banks for all credit types, whereas for big banks, the deceleration is observed only in consumer credits
Changes in hemostasis parameters in nonfatal methicillin-sensitive Staphylococcus aureus bacteremia complicated by endocarditis or thromboembolic events : a prospective gender-age adjusted cohort study
The aim of this study was to examine the changes in hemostasis parameters in endocarditis and thromboembolic events in nonfatal methicillin-sensitive Staphylococcus aureus bacteremia (MS-SAB) - a topic not evaluated previously. In total, 155 patients were recruited and were categorized according to the presence of endocarditis or thromboembolic events with gender-age adjusted controls. Patients who deceased within 90 days or patients not chosen as controls were excluded. SAB management was supervised by an infectious disease specialist. Patients with endocarditis (N = 21), compared to controls (N = 21), presented lower antithrombin III at day 4 (p <0.05), elevated antithrombin III at day 90 (p <0.01), prolonged activated partial thromboplastin time at days 4 and 10 (p <0.05), and enhanced thrombin-antithrombin complex at day 4 (p <0.01). Thromboembolic events (N = 8), compared to controls (N = 34), significantly increased thrombin-antithrombin complex at day 4 (p <0.05). In receiver operating characteristic analysis, the changes in these hemostasis parameters at day 4 predicted endocarditis and thromboembolic events (p <0.05). No differences in hemoglobin, thrombocyte, prothrombin fragment, thrombin time, factor VIII, D-dimer or fibrinogen levels were observed between cases and controls. The results suggest that nonfatal MS-SAB patients present marginal hemostasis parameter changes that, however, may have predictability for endocarditis or thromboembolic events. Larger studies are needed to further assess the connection of hemostasis to complications in SAB.Peer reviewe
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