Investigation of the Summer Kara Sea Circulation Employing a Variational Data Assimilation Technique

[ 1] The summer circulations and hydrographic fields of the Kara Sea are reconstructed for mean, positive and negative Arctic Oscillation regimes employing a variational data assimilation technique which provides the best fit of reconstructed fields to climatological data and satisfies dynamical and kinematic constraints of a quasi-stationary primitive equation ocean circulation model. The reconstructed circulations agree well with the measurements and are characterized by inflow of 0.63, 0.8, 0.51 Sv through Kara Gate and 1.18, 1.1, 1.12 Sv between Novaya Zemlya and Franz Josef Land, for mean climatologic conditions, positive and negative AO indexes, respectively. The major regions of water outflow for these regimes are the St. Anna Trough (1.17, 1.21, 1.34 Sv) and Vilkitsky/ Shokalsky Straits (0.52, 0.7, 0.51 Sv). The optimized velocity pattern for the mean climatological summer reveals a strong anticyclonic circulation in the central part of the Kara Sea ( Region of Fresh Water Inflow, ROFI zone) and is confirmed by ADCP surveys and laboratory modeling. This circulation is well pronounced for both high and low AO phases, but in the positive AO phase it is shifted approximately 200 km west relatively to its climatological center. During the negative AO phase the ROFI locaion is close to its climatological position. The results of the variational data assimilation approach were compared with the simulated data from the Hamburg Shelf Ocean Model (HAMSOM) and Naval Postgraduate School 18 km resolution (NPS-18) model to validate these models

Control and measuring device for circulating systems of drilling equipment

Проектирование контрольно-измерительного оборудования предполагает анализ конструктивных особенностей изделия, его эксплуатационных характеристик, а также серийности изготовления и особенностей производстваThe design of control and measuring equipment involves the analysis of the design features of the product, its operating characteristics, as well as the serial production and characteristics of productio

Summer Transport Estimates of the Kamchatka Current Derived As a Variational Inverse of Hydrophysical and Surface Drifter Data

The quasistationary summer Bering Sea circulation is reconstructed as a variational inverse of the hydrographic and atmospheric climatologies, transport estimates through the Bering Strait, and surface drifter data. Our results indicate the splitting of the Kamchatka Current in the vicinity of the Shirshov Ridge. This branching is in agreement with independent ARGO drifter observations. It was also found, that transport of the Kamchatka Current gradually increases downstream from 14 Sv in the Olyutorsky Gulf to 24 Sv in the Kamchatka Strait, which is twice higher than previous estimates

Summer Transport Estimates of the Kamchatka Current Derived As a Variational Inverse of Hydrophysical and Surface Drifter Data

The quasistationary summer Bering Sea circulation is reconstructed as a variational inverse of the hydrographic and atmospheric climatologies, transport estimates through the Bering Strait, and surface drifter data. Our results indicate the splitting of the Kamchatka Current in the vicinity of the Shirshov Ridge. This branching is in agreement with independent ARGO drifter observations. It was also found, that transport of the Kamchatka Current gradually increases downstream from 14 Sv in the Olyutorsky Gulf to 24 Sv in the Kamchatka Strait, which is twice higher than previous estimates

Jake dvojne kaskade i shema γ-raspada složene jezge 118Sn

Transition energies and intensities of 453 two-step cascades following thermal neutron capture in 117Sn have been measured. The data allowed us to considerably extend previous decay scheme of the 118Sn nucleus and to achieve more precise results. Autocorrelation analysis of the excitation spectrum of intermediate levels of the most intense cascades allowed us to determine most probable period of their regularity. Besides, analysis showed the impossibility to reproduce quantitatively the total cascade intensities taking into account only excitations of the fermion type. The results lead to the conclusion that the excitations of vibrational type considerably influence the cascade g-decay process in 118Sn almost up to the neutron separation energy Sn.Mjerili smo energije i intenzitete 453 dvojne kaskada koje slijede uhvat termalnih neutrona u 117Sn. Podaci su omogućili određivanje znatno proširenje ranije sheme raspada jezgri 118Sn i točnije rezultate. Analiza autokorelacije uzbudnog spektra međustanja najjačih kaskada omogućila je određivanje vjerojatne periodičnosti. Pokazuje se da nije moguće kvantitativno objasniti ukupne jakosti kaskada ako se uzmu u obzir samo fermionske uzbude. Zaključuje se da vibracijske uzbude znatno utječu na γ-raspade u 118Sn sve do energije odvajanja neutrona Sn

Blood flow controls coagulation onset via the positive feedback of factor VII activation by factor Xa

<p>Abstract</p> <p>Background</p> <p>Blood coagulation is a complex network of biochemical reactions, which is peculiar in that it is time- and space-dependent, and has to function in the presence of rapid flow. Recent experimental reports suggest that flow plays a significant role in its regulation. The objective of this study was to use systems biology techniques to investigate this regulation and to identify mechanisms creating a flow-dependent switch in the coagulation onset.</p> <p>Results</p> <p>Using a detailed mechanism-driven model of tissue factor (TF)-initiated thrombus formation in a two-dimensional channel we demonstrate that blood flow can regulate clotting onset in the model in a threshold-like manner, in agreement with existing experimental evidence. Sensitivity analysis reveals that this is achieved due to a combination of the positive feedback of TF-bound factor VII activation by activated factor X (Xa) and effective removal of factor Xa by flow from the activating patch depriving the feedback of "ignition". The level of this trigger (i.e. coagulation sensitivity to flow) is controlled by the activity of tissue factor pathway inhibitor.</p> <p>Conclusions</p> <p>This mechanism explains the difference between red and white thrombi observed <it>in vivo </it>at different shear rates. It can be speculated that this is a special switch protecting vascular system from uncontrolled formation and spreading of active coagulation factors in vessels with rapidly flowing blood.</p