Центральная Азия в интересах Ирана, Китая, России и Турции: взгляд из США

Работа посвящена изучению реакции американских специалистов на внешнюю политику Ирана, Китая, России и Турции в Центральной Азии. В исследовании комплексно рассмотрена политика единственной сверхдержавы относительно отдельного региона в рамках общей стратегии США.Робота присвячена вивченню реакції американських фахівців на зовнішню політику Ірану, Китаю, Росії та Туреччини у Центральній Азії. У дослідженні комплексно розглянута політика єдиної наддержави щодо окремого регіону в рамках її загального стратегічного курсу.The thesis is focused on a study of the american specialists reactions toward foreign policy of China, Iran, Russia and Turkey in Central Asia. The research presents a complex investigation of the policy of the only superpower in the relation to a separate region in the frame of its general strategic course

Omega-3 polyunsaturated fatty acids: Their potential role in blood pressure prevention and management

Omega-3 polyunsaturated fatty acids (PUFAs) from fish and fish oils appear to protect against coronary heart disease: their dietary intake is in fact inversely associated to cardiovascular disease morbidity/mortality in population studies. Recent evidence suggests that at least part of their heart protective effect is mediated by a relatively small but significant decrease in blood pressure level. In fact, omega-3 PUFAs exhibit wide-ranging biological actions that include regulating both vasomotor tone and renal sodium excretion, partly competing with omega-6 PUFAs for common metabolic enzymes and thereby decreasing the production of vasocostrincting rather than vasodilating and anti-inflammatory eicosanoids. PUFAs also reduce angiotensin-converting enzyme (ACE) activity, angiotensin II formation, TGF-beta expression, enhance eNO generation and activate the parasympathetic nervous system. The final result is improved vasodilation and arterial compliance of both small and large arteries. Preliminary clinical trials involving dyslipidemic patients, diabetics and elderly subjects, as well as normotensive and hypertensive subjects confirm this working hypothesis. Future research will clarify if PUFA supplementation could improve the antihypertensive action of specific blood pressure lowering drug classes and of statins

Formal ratification of subseries for the Pleistocene Series of the Quaternary System

The Pleistocene Series/Epoch of the Quaternary System/ Period has been divided unofficially into three subseries/ subepochs since at least the 1870s. On 30th January, 2020, the Executive Committee of the International Union of Geological Sciences ratified two proposals approved by the International Commission on Stratigraphy formalizing: 1) the Lower Pleistocene Subseries, comprising the Gelasian Stage and the superjacent Calabrian Stage, with a base defined by the GSSP for the Gelasian Stage, the Pleistocene Series, and the Quaternary System, and currently dated at 2.58 Ma; and 2) the term Upper Pleistocene, at the rank of subseries, with a base currently undefined but provisionally dated at ~129 ka. Defining the Upper Pleistocene Subseries and its corresponding stage with a GSSP is in progress. The Middle Pleistocene Subseries is defined by the recently ratified GSSP for the Chibanian Stage currently dated at 0.774 Ma. These ratifications complete the official division of the Pleistocene into three subseries/ subepochs, in uniformity with the similarly subdivided Holocene Series/Epoch.</p

Evidence for phase-locked changes in climate between Scotland and Greenland during GS-1 (Younger Dryas) using micromorphology of glaciolacustrine varves from Glen Roy

There is a current need to develop annual/decadal chronologies from periods of rapid climate change in order to understand the rate and timing of climate events and identify how other proxies either lead or lag this climate forcing. Annually-laminated or varved sediments are key proxies for understanding environmental change at such a scale. This paper presents the results of microscale analysis of glaciolacustrine varve sediments from Scotland and develops a new index called varve group, which ranks the number of pulses of sediment observed in the summer component of the varve. The varve group index is compared with data from the Greenland ice-core record and correspondence can be observed between the oxygen isotope records from Greenland during the latter part of GS-1 and the 515-year Lochaber varve group index. The processes that control the number of sediment pulses into the lake basin are discussed and we examine how these factors might control both the isotopic composition of the ice cores and varve group formation. It is proposed that the position of the sea ice in the North Atlantic may provide such a mechanism

Volcanic synchronisation between the EPICA Dome C and Vostok ice cores (Antarctica) 0–145 kyr BP

This study aims at refining the synchronisation between the EPICA Dome C (EDC) and Vostok ice cores in the time interval 0–145 kyr BP by using the volcanic signatures. 102 common volcanic events were identified by using continuous electrical conductivity (ECM), di-electrical profiling (DEP) and sulfate measurements while trying to minimize the distortion of the glaciological chronologies. This is an update and a continuation of previous works performed over the 0–45 kyr interval that provided 56 tie points to the ice core chronologies (Udisti et al., 2004). This synchronisation will serve to establish Antarctic Ice Core Chronology 2012, the next synchronised Antarctic dating. A change of slope in the EDC-depth/Vostok-depth diagram is probably related to a change of accumulation regime as well as to a change of ice thickness upstream of the Lake Vostok, but we did not invoke any significant temporal change of surface accumulation at EDC relative to Vostok. No significant phase difference is detected between the EDC and Vostok isotopic records, but depth shifts between the Vostok 3G and 5G ice cores prevent from looking at this problem accurately. Three possible candidates for the Toba volcanic super-eruption �73 kyr ago are suggested in the Vostok and EDC volcanic records. Neither the ECM, DEP nor the sulfate fingerprints for these 3 events are significantly larger than many others in the records

Millennial-scale variability during the last glacial: the ice core record

The oxygen-isotope records from Greenland ice cores show a very strong, reproducible pattern of alternation between warm Greenland Interstadials (GI) and cold Greenland Stadials (GS) at millennial-scale during the last glacial period. Here we summarise what is known about this variability from ice core records. The typical cycle has a sawtooth pattern, with a very rapid warming event (occurring in a few decades), a slow cooling trend, and then a final fast cooling. 25 such events have been numbered in the last glacial. The recent GICC05 age scale provides the best available age scale that can be directly applied to this stratigraphy, and we summarise the timing of the warming events, and the length and strength of each event. The Greenland stratigraphy can be transferred to other records if we make assumptions about the contemporaneous nature of rapid events in different archives. Other parameters, such as the snow accumulation rate, and the concentration of terrestrial dust and sea salt recorded in the Greenland cores, also show a strong contrasting pattern between GI and GS. Methane concentrations are generally high during GI and lower during GS, with the increase from GS to GI occurring within a century. Antarctic ice cores show a different pattern: each GI has an Antarctic counterpart, but Antarctica appears to warm while Greenland is in a GS, and cool during GI. These changes are consistent with a mechanism involving ocean heat transport, but the rapid nature of warmings poses a challenge for modellers, while the rapid methane changes pose questions about the pattern of land biosphere emissions during the glacial that are also relevant for understanding glacial-interglacial methane variability

Revisiting the Faroe Marine Ash Zone III in two Greenland ice cores: Implications for marine-ice correlations

Nineteen new Icelandic tephra layers are identified in NGRIP and NEEM ice spanning Greenland Interstadial-9 (GI-9) and the early phase of GI-8 (∼38 000-40 500 b2k). Fourteen tephras are identified in the NGRIP record and five direct correlatives are identified in NEEM, thus indicating the occurrence of 14 separate volcanic events. With two exceptions, the tephras are tholeiitic basalt in composition and despite having very similar geochemical signatures can, in most cases, be discriminated from one another using their TiO2 values. All of these tephra layers fall within the compositional range of the Faroe Marine Ash Zone III (FMAZ III) deposit previously identified in ocean cores from the Faroes region and previously correlated to NGRIP 2066.95m by Davies et al. (). Thus, the FMAZ III in the marine realm is most likely a complex ash zone that represents a series of closely timed Grimsvötn eruptions that, as yet, can only be stratigraphically separated in the high-resolution ice-core records. The geochemical signatures and stratigraphic positions of the new ice-core layers means that the FMAZ III tephra deposit, as currently defined in the marine realm, cannot be correlated to NGRIP 2066.95m or any other ice-core tephra horizons preserved during this interval.</p

The synchronization of palaeoclimatic events in the North Atlantic region during Greenland Stadial 3 (ca 27.5 to 23.3kyr b2k)

Two high resolution marine sediment cores located 83 km apart in the NE Atlantic have been studied: MD95-2006 (Barra Fan; 57°01.82 N, 10°03.48 W; 2120 m water depth) and MD04-2822 (Rockall Trough; 56°50.54 N, 11°22.96 W; 2344 m water depth). The records are anchored to the NGRIP ice core stratigraphy and GICC05 chronology by the presence of geochemically characterized Fugloyarbanki tephra and further tested by radiocarbon age control. Replicated sea surface temperature (SST) records show evidence for an abrupt and short-lived warming within Greenland Stadial (GS)-3, to which we tentatively assign an age of ca 25.6–24.8 kyr GICC05 b2k. Based on these and another marine palaeoclimate record (LINK17) from the Faroe-Shetland Channel, we propose a new three-fold event stratigraphy for GS-3 within the North East Atlantic region. The recognition of this warming event within GS-3 in NE Atlantic SST records demonstrates that such events may not readily be identified within the coldest stadials of the Greenland ice cores, highlights the need for carefully constructed event stratigraphies (independently tested by the use of tephra isochrones and radiocarbon) and illustrates pervasive millennial-scale climate variability of the North Atlantic region (Dansgaard-Oeschger (D/O) events) is deeply embedded in the dynamics of Atlantic Meridional Overturning Circulation (AMOC)

Controls on the East Asian monsoon during the last glacial cycle, based on comparison between Hulu Cave and polar ice-core records

Previous studies have suggested a sound chronological correlation between the Hulu Cave record (East Asian monsoon) and Greenland ice-core records, which implies a dominant control of northern hemisphere climate processes on monsoon intensity. We present an objective, straightforward statistical evaluation that challenges this generally accepted paradigm for sub-orbital variability. We propose a more flexible, global interpretation, which takes into account a broad range of variability in the signal structures in the Hulu Cave and polar ice-core records, rather than a limited number of major transitions. Our analysis employs the layer-counted Greenland Ice-Core Chronology 2005 (GICC05), which was developed for Greenland records and has since been applied – via methane synchronisation – to the high-resolution ?18Oice series from EPICA Dronning Maud Land (EDML). The GICC05 chronology allows these ice-core records to be compared to the U–Th dated Hulu Cave record within relatively narrow (3%) bounds of age uncertainty. Following previous suggestions, our proposed interpretation suggests that the East Asian monsoon is influenced by a combination of northern hemisphere ‘pull’ (which is more intense during boreal warm periods), and southern hemisphere ‘push’ (which is more intense monsoon during austral cold periods). Our analysis strongly suggests a dominant control on millennial-scale monsoon variability by southern hemisphere climate changes during glacial times when the monsoon is weak overall, and control by northern hemisphere climate changes during deglacial and interglacial times when the monsoon is strong. The deduced temporally variable relationship with southern hemisphere climate records offers a statistically more plausible reason for the apparent coincidence of major East Asian monsoon transitions with northern hemisphere (Dansgaard–Oeschger, DO) climate events during glacial times, than the traditional a priori interpretation of strict northern hemisphere control.<br/

Lateglacial environmental variability from Swiss tree rings

Evidence of annually resolved environmental variations during the Aller\uf8d interstadial is presented using 81 fossil Scots pine tree-ring series from Gaenziloo and Landikon, near Zurich, Switzerland. The absolute age of the trees ranges between 11,920 and 10,61014C BP, which was determined by wiggle-matching radiocarbon ages to the Cariaco14C data set. From the two sites we created a composite floating Aller\uf8d chronology on the basis of their 632 years of overlap (r=0.57), after individual spline detrending. Merging both data sets resulted in a Lateglacial tree-ring chronology covering 1050 years. Regional curve standardization (RCS) was applied to preserve low-frequency information. Growth behavior of the fossil trees was compared with a recent composite pine data set from the central Swiss Alps and reveals distinct differences. The new Aller\uf8d RCS chronology reveals major Lateglacial variations, such as the Gerzensee oscillation, the abrupt climate shift towards the Younger Dryas and some short-term events. Radiocarbon ages agree well with those from other sites on the Swiss Plateau. For hemispheric comparisons we used the annual layer thickness record from the NGRIP ice core and the gray-scale varve record from the Cariaco basin. Even though the amplitudes are not yet fully understood, similarities on decadal-to-centennial scales are apparent. \ua9 2007 Elsevier Ltd. All rights reserved