Steady Phase Research Articles

Monetary policy under economic transformation in Ukraine

The research subject includes the theoretical basis and mechanisms of monetary policy formation and realization as an instrument of macroeconomic regulation. The aim of the study is to determine the features of domestic monetary policy and to systemize the policy’s stages under economic transformations. Methods. In order to achieve the appropriate tasks, we used a set of methods and approaches, that helped to ensure the conceptual unity of our investigation. The dialectical, systemic and structural approaches, methods of analysis and synthesis, comparison, generalization, scientific abstraction are applied. Results. The peculiarities of formation and realization of monetary policy of Ukraine under economic transformations are determined. The main stages of national monetary policy’s development are systemized. The dynamics of monetization, exchange rate and index of consumer price from 1992 to 2018 is investigated. Practical implications. Monetaryl policy and instruments of its implementation. Conclusions. Nowadays, the monetary policy has a formed institutional mechanism in order to reach the main goal and tasks. We identified the main phases of monetary policy of Ukraine. In the initial stage the main elements of monetary architectonics are established, also the powers and tasks of central bank are defined. The stage of functional improvement characterized by the restriction on central bank repayment of bonds on the primary market, decreasing the monetization of national economy, introducing the currency exchange corridor. At the steady development phase, we determined the exchange rate stability and gradual increasing of monetization level. Within the transitional stage of modification, the raising of monetization was continued, moreover, the combined using of methods on the currency market was carried out to stabilize it. Also, National bank defined the priority directions to enhance the bank system. The stage of institutional modernization is characterized by the monetary strategy formation, increasing the central bank institutional and financial independence, the adoption of inflation targeting regime, the improving of basic statements of currency transaction, the developing of macroprudential regulation to ensure financial stability.

Soluble P-Selectin Levels in Patients with Sickle Cell Disease Reflect Platelets' Activation Rather Than Endothelial Dysfunction

Background: Vascular occlusion is a major cause of the morbidity associated with sickle-cell disease (SCD). The tendency of sickle red blood cells to adhere to the vascular endothelium is believed to be a major contributor and possibly primary cause of the vaso-occlusive process. Therefore mediators of adhesion have become a potential new target for pharmacological therapy to combat the complications of SCD. One of the molecules involved in this process is P-Selectin or CD62P, a cell adherence molecule that is rapidly and chronically expressed on the surface of endothelial cells and platelets when activated. P-Selectin is found in the plasma of normal individuals at ng/mL concentrations. Circulating soluble P-Selectin (sP-Selectin) appears to be slightly smaller than native P-Selectin. An alternatively spliced mRNA encoding a form of human P-Selectin lacking the transmembrane anchoring domain has been reported for both megakaryocytes and endothelial cells, and evidence suggests that the majority of circulating sP-Selectin arises in this manner. We and others have reported elevated sP-Selectin levels in SCD even in steady phase. Recently, a humanized monoclonal antibody that binds to P-Selectin and blocks its interaction with P-selectin glycoprotein ligand 1 (PSGL-1) has been administered to patients with SCD, resulting in an amelioration of painful VOC. In this context we aimed to explore if sP-Selectin levels could be used to choose among the SCD patients those who might benefit from the new therapy. Patients and Methods: Eighty adult Caucasian patients with HbS/βthal at steady phase [40 patients under hydroxyurea (HU+) treatment and 40 patients without hydroxyurea (HU-) treatment] were included in this study, while 20 apparently healthy individuals of similar age and gender served as controls. Along with sP-Selectin levels, measured with the same method as reported previously (Human sP-Selectin/CD62P Immunoassay, R&D Systems, Minneapolis, MN, USA), other parameters of hemolysis, inflammation, endothelial dysfunction, iron accumulation and clinical features of the disease were evaluated. Results are expressed as median values ± SEM. Results: We found that sP-Selectin levels were elevated in 45/80 (56%) patients with HbS/βthal compared to controls (108.2±6.3 vs. 69.3±4.1ng/mL, respectively, p<0.001), independently of patients' βthal genotype and correlated strongly with PLT count (r=0.760, p<0.001). Regarding HU treatment, sP-Selectin levels did not differ between (HU+) and (HU-) patients (112.5±9.8 vs. 100.3±7.4ng/mL, respectively, p>0.07). No significance correlation was found between sP-Selectin levels and markers of: hemolysis (RPI: r=0.191, p>0.100); LDH: r=0.103, p>0.360 and bilirubin: r=0.171, p>0.130); inflammation (hs-CRP: r= 0.002, p>0.842); endothelial dysfunction (vWF:antigen: r=0.141, p>0.210 and ADAMTS-13: r=0.089, p>0.507). Regarding iron accumulation no correlation was found between sP-Selectin and ferritin levels (r=0.090, p>0.438), while a weak negative correlation was found with hepcidin-25 levels (r=-0.283, p=0.018). Furthermore, no correlation was found between sP-Selectin levels and history of clinical complications such as VOC (p>0.795), acute chest syndrome, venous and arterial thrombosis and mean pulmonary artery pressure values, (p>0.402). Conclusion: In this study, we proceeded with an external validation procedure of sP-Selectin determination in patients with HbS/βthal (keeping the same methodology in a different cohort of patients), and we found elevated levels of sP-Selectin with the evidence of PLTs' secretion origin, as no correlation found with other markers of endothelial dysfunction and inflammation. Interestingly, we failed to find a significant link of sP-Selectin levels with other markers of disease severity and/or clinical features of SCD. Thus, we consider that the use sP-Selectin as a biomarker of assessment and treatment of endothelial dysfunction in patients with SCD is of almost negligible importance. Disclosures Voskaridou: Genesis: Consultancy, Research Funding; Protagonist: Research Funding; Celgene Corporation: Consultancy, Research Funding; Acceleron: Consultancy, Research Funding; Addmedica: Membership on an entity's Board of Directors or advisory committees.

Phase division and transition modeling based on the dominant phase identification for multiphase batch process quality prediction

Batch processes are carried out from one steady phase to another one, which may have multiphase and transitions. Modeling in transitions besides in the steady phases should also be taken into consideration for quality prediction. In this paper, a quality prediction strategy is proposed for multiphase batch processes. First, a new repeatability factor is introduced to divide batch process into different steady phases and transitions. Then, the different local cumulative models that considered the cumulative effect of process variables on quality are established for steady phases and transitions. Compared with the reported modeling methods in transitions, a novel just-in-time model can be established based on the dominant phase identification. The proposed method can not only consider the dynamic characteristic in the transition but also improve the accuracy and the efficiency of transitional models. Finally, online quality prediction is performed by accumulating the prediction results from different phases and transitions. The effectiveness of the proposed method is demonstrated by penicillin fermentation process.

A Multiscale Agent-Based Model of Ductal Carcinoma In Situ.

Objective:we present a multiscale agent-based model of Ductal Carcinoma in Situ (DCIS) in order to gain a detailed understanding of the cell-scale population dynamics, phenotypic distributions, and the associated interplay of important molecular signaling pathways that are involved in DCIS ductal invasion into the duct cavity (a process we refer to as duct advance rate here).Methods:DCIS is modeled mathematically through a hybridized discrete cell-scale model and a continuum molecular scale model, which are explicitly linked through a bidirectional feedback mechanism.Results:we find that duct advance rates occur in two distinct phases, characterized by an early exponential population expansion, followed by a long-term steady linear phase of population expansion, a result that is consistent with other modeling work. We further found that the rates were influenced most strongly by endocrine and paracrine signaling intensity, as well as by the effects of cell density induced quiescence within the DCIS population.Conclusion:our model analysis identified a complex interplay between phenotypic diversity that may provide a tumor adaptation mechanism to overcome proliferation limiting conditions, allowing for dynamic shifts in phenotypic populations in response to variation in molecular signaling intensity. Further, sensitivity analysis determined DCIS axial advance rates and calcification rates were most sensitive to cell cycle time variation.Significance:this model may serve as a useful tool to study the cell-scale dynamics involved in DCIS initiation and intraductal invasion, and may provide insights into promising areas of future experimental research.

An Extended PEGASIS Protocol Based on Group Authentication with Merkle Tree in WSNs

With the constant improvement of Wireless Sensor Network, its application scenarios become more diverse. Due to the limited resources of sensor nodes, there are many researches devoted to the optimization of network structure and the prolongation of network life. The proposed extended protocol is based on the chain-based routing technique of PEGASIS. In a newly deployed network, intra-group trust is formed through the Group Authentication based on Merkle Tree, which can protect the node information and resist the deception of false message. In the steady phase, the whole network re-chain is replaced by re-chain within the group when any node dies. Simulation results show that the scheme proposed in this paper has obvious improvement in terms of residual energy and network life compared with PEGASIS.

Evaporation of ethanol-water sessile droplet of different compositions at an elevated substrate temperature

We experimentally investigate the evaporation dynamics of sessile droplets with different compositions of ethanol-water binary mixture at different substrate temperatures. At room temperature, a binary droplet undergoes two distinct evaporation stages unlike only the pinned stage evaporation for pure droplets. In the binary droplets, the more volatile ethanol evaporates faster leading to a nonlinear trend in the evaporation process. At elevated substrate temperature, we observed an early spreading stage, an intermediate pinned stage and a late receding stage of evaporation. Increasing the substrate temperature decreases the lifetime of binary droplets rapidly. At high substrate temperature, we found that the lifetime of the droplet exhibits a non-monotonic trend with the increase in ethanol concentration in the binary mixture, which can be attributed to the non-ideal behaviour of water-ethanol binary mixtures. Interestingly, the evaporation dynamics for different compositions at high substrate temperature exhibits a self-similar trend showing a constant normalised volumetric evaporation rate for the entire evaporation process. This indicates that the evaporation dynamics of a binary droplet of a given composition at high substrate temperature is equivalent to that of another pure fluid with a higher volatility at room temperature. The evaporation rates of pure and binary droplets at different substrate temperatures are compared against a theoretical model developed for pure and binary mixture droplets. The model predictions are found to be quite satisfactory for the steady evaporation phase of the droplet lifetimes.

Practicing anammox in a novel hybrid anaerobic-aerobic baffled reactor for treating high-strength ammonium piggery wastewater with low COD/TN ratio

A novel hybrid anaerobic-aerobic baffled reactor (HAOBR) with four compartments was constructed to treat manure-free piggery wastewater with an average COD/TN ratio as low as 0.98, without any supplement of external carbon source. Inoculated with aerobic activated sludge and operated at hydraulic retention time 36 h, 32 °C and reflux ratio 2.0, the reactor could perform steadily within 24 days. The removal of COD, NH4+-N and TN within the 21-days steady phase averaged 87.0%, 100% and 91.3%, respectively. Analysis of stoichiometry and results of high-throughput pyrosequencing revealed that the excellent nitrogen removal in the HAOBR was achieved by the cooperation of heterotrophic and autotrophic denitrification with anammox as the dominant approach. Compared with the previously developed microaerobic treatment processes and the recently reported modified A/O process, the HAOBR was more cost-efficient in treating manure-free piggery wastewater because of the less energy consumption, rapid startup process and efficient nutrients removal.

Spreading and oscillation induced by liquid drop impacting onto sessile drop

Abstract This study investigates interaction between an impact liquid drop and a sessile drop on both flat and cylindrical substrates, focusing mainly on the combined liquid spreading and oscillation under low impact velocity with aid of high-speed photography. Different from the coaxial interaction with spreading and recoiling one after another, the off-center interaction presents an asymmetric liquid motion featured by the concomitant spreading and recoiling. Rim thickness in recoiling decreases appreciably with increasing the offset distance. Results also show that the height of combined liquid is more representative of liquid oscillation than the diameter, based on which the interaction is grouped into four major phases: impingement phase, unsteady damped oscillation phase, steady damped oscillation phase, and static phase. Also presented in this study are maximum spreading diameter and minimum height of the combined liquid. This is followed by investigations of unsteady duration, oscillation period, and height profile with regards to Weber number and offset distance.

Steady and dynamic magnetic phase transitions in the open interacting quantum dots arrays

We apply the mean-field Hubbard model, non-equilibrium Green’s function (NEGF) theory and the hierarchical equations of motion (HEOM) method to investigate some magnetic phase transitions in the 1D interacting quantum dots arrays (QDA) sandwiched by non-interaction leads. We find that with a weak device-leads coupling, there exists a ferrimagnetic state in the uniform odd-numbered or the staggered-hopping QDA systems. With increasing the coupling strength, temperature or the bias potential, the extra spin-polarized electrons flow out of the QDA, which results in a magnetism-to-nonmagnetism phase transition. With the spin-resolved HEOM method, we also investigate the transient spin dissipation process in these phase transitions. When applying an abrupt large bias potential or a strong device-leads coupling, the spin polarized electrons decay with oscillations from the QDA into electrodes. We believe our results may be helpful in the future quantum computation devices.

The mineralization characteristics of organic carbon and particle composition analysis in reconstructed soil with different proportions of soft rock and sand.

The organic carbon mineralization process reflects the release intensity of soil CO2. Therefore, the study of organic carbon mineralization and particle composition analysis of soft rock and sand compound soil can provide technical support and a theoretical basis for soil organic reconstruction (soil structure, materials and biological nutrition). Based on previous research, four treatments were selected: CK (soft rock:sand=0:1), C1 (soft rock:sand=1:5), C2 (soft rock:sand=1:2) and C3 (soft rock:sand=1:1), respectively. Specifically, we analyzed the organic carbon mineralization process and soil particle composition by lye absorption, laser granulometer, and scanning electron microscope. The results showed that there was no significant difference in organic carbon content between C1, C2 , and C3 treatments, but they were significantly higher than in the CK treatment (P < 0.05). The organic carbon mineralization rate in each treatment accords with a logarithmic function throughout the incubation period (P < 0.01), which can be divided into a rapid decline phase in days 1 to 11 followed by a steady decline phase in days 11 to 30. The cumulative mineralization on the 11th day reached 54.96%–74.44% of the total mineralization amount. At the end of the incubation, the cumulative mineralization and potential mineralizable organic carbon content of the C1, C2 and C3 treatments were significantly higher than those of the CK treatment. The cumulative mineralization rate was also the lowest in the C1 and C2 treatment. The turnover rate constant of soil organic carbon in each treatment was significantly lower than that of the CK treatment, and the residence time increased. With the increase of volume fraction of soft rock, the content of silt and clay particles increased gradually, the texture of soil changed from sandy soil to sandy loam, loam , and silty loam, respectively. With the increase of small particles, the structure of soil appear ed to collapse when the volume ratio of soft rock was 50%. A comprehensive mineralization index and scanning electron microscopy analysis, when the ratio of soft rock to sand volume was 1:5–1:2, this can effectively increase the accumulation of soil organic carbon. Then, the distribution of soil particles was more uniform, the soil structure was stable (not collapsed), and the mineralization level of unit organic carbon was lower. Our research results have practical significance for the large area popularization of soft rock and sand compound technology.

T–S Fuzzy Modeling for Aircraft Engines: The Clustering and Identification Approach

This paper presents a data-based Takagi-Sugeno (T–S) fuzzy modeling approach for aircraft engines in the flight envelope. We propose a series of T–S fuzzy models for engines with flight conditions as premises and engine linear dynamic models as consequences. By engine dynamic clustering, we determine rough T–S fuzzy models to approximate the nonlinear dynamics of engines in the flight envelope. After that, the maximum–minimum distance-based fuzzy c-means (MMD-FCM) algorithm comes to refine the fuzzy rules and the least square method (LSM) comes to identify premise parameters for each single rough model. The proposed MMD-FCM algorithm guarantees the refined results are stable and reasonable, and the identification improves the accuracy of the steady and transient phases. The model verification showed that the T–S fuzzy models for engines had a high accuracy with a steady error less than 5%, and that the root mean squared error (RMSE) of transient errors was less than 8 × 10−4 with good generalization ability in the flight envelope.

Fully coupled free‐surface flow and sediment transport modelling of flash floods in a desert stream in the Mojave Desert, California

AbstractFor most of the year, a dry‐bed desert wash is void of water flow. Intensive rain events, however, could trigger significant flash floods that bring about highly complicated hydrodynamics and morphodynamics processes within a desert stream. We present a fully coupled three‐phase flow model of air, water, and sediment to simulate numerically the propagation of a flash flood in a field‐scale fluvial desert stream, the so‐called Tex Wash located in the Mojave Desert, California, United States. The turbulent flow of the flash flood is computed using the three‐dimensional unsteady Reynolds‐averaged Navier–Stokes equations closed with the shear stress transport k − ω model. The free surface of the flash flood at the interface of air and water phases is computed with the level‐set method, which enables instantaneous tracking of the water surface as the flash flood propagates over the dry bed of the desert stream. The evolution of the desert fluvial stream's morphology, due to the action of the propagating flash flood on the mobile bed, is calculated using a Eulerian morphodynamics model based on the curvilinear immersed boundary method. The capabilities of the proposed numerical framework are demonstrated by applying it to simulate a flash flood event in a 0.65‐km‐long reach of the Tex Wash, the intricate channel morphology of which is obtained using light imaging detection and ranging technology. The simulated region of the stream includes a number of bridge foundations. The simulation results of the model for the flash flood event revealed the formation of a highly complex flow field and scour patterns within the stream. Moreover, our simulation results showed that most scour processes take place during the steady phase of the flash flood, that is, after the flash flood fills the stream. The transient phase of the flash flood is rather short and contributes to a very limited amount of erosion within the desert stream.

Numerical Study on Thermal Design of a Large-Area Hot Plate with Heating and Cooling Capability for Thermal Nanoimprint Lithography

A numerical study is conducted on the thermal performance of a large-area hot plate specifically designed as a heating and cooling tool for thermal nanoimprint lithography processes. The hot plate has the dimensions 240 mm × 240 mm × 20 mm, in which a series of cartridge heaters and cooling holes are installed. Stainless steel has been selected to endure the high molding pressures. A numerical model based on ANSYS Fluent is employed to predict the thermal behavior of the hot plate in both the heating and cooling phases. The proportional–integral–derivative (PID) thermal control of the device is modeled by adding user defined functions. The results of the numerical computations demonstrate that the use of cartridge heaters provides sufficient heat-up performance and the active liquid cooling in the cooling holes provides the required cool-down performance. However, a crucial technical issue is raised, namely that the proposed design poses a large temperature non-uniformity in the steady heating phase and in the transient cooling phase. As a remedy, a new hot plate in which heat pipes are installed in the cooling holes is considered. The numerical results show that the installation of heat pipes could enhance the temperature uniformity both in the heating and cooling phases.

Generating intra-year metrics of wildfire progression using multiple open-access satellite data streams

The 2017 fire season was one of the largest on record for British Columbia (BC), Canada, in terms of total area burned (estimated 1.2 million ha), affecting the safety and air quality of numerous communities. Moreover, fires of this number and extent alter the wood supply for harvesting, the nature of habitat for wildlife, and can affect regional and national carbon budgets. As a result, it is important to map these fires accurately and to monitor within-year fire progression in order to quantify the resulting forest-disturbance impacts fully. The Bayesian Updating of Land Cover (BULC) algorithm was used to merge burned-area classifications of individual fires from a range of remote sensing sources such as Landsat-7, Landsat-8, Sentinel-2, and MODIS (MCD64A1) burned-area dataset. Together, these provisional classifications imaged each pixel within a known fire perimeter an average of 33.8 times between April 1 and December 1. The resulting 35-week time-series stack had updated weekly burned areas for each of the 89 fires in BC in 2017. Province-wide fire progression was variable throughout the period analyzed, characterized by a steady burn phase of 41,437 ha (5% of total area burned) over a two-week period in early July, an accelerated burn phase of 149,422 ha (17%) from mid-July to early August, another steady burn phase of 218,079 ha (24%) for one month until early September, and a second accelerated burn phase of 301,931 ha (34%) over two weeks in late September with subsequent steady growth of 180,119 ha (20%) over 1.5 months until containment in late October. Herein, we demonstrate how such temporally dense fire classification stacks can be used to analyze fire progression over the course of a fire season (both retrospectively and in near-real time) providing useful metrics to characterize and compare fire events. End-of-season burned-area estimates correspond with estimates derived from the National Burned Area Composite (NBAC) product that is generated retrospectively from fire best-available mapping approaches. This rapid interpretation of information enables the analysis of suppression success and potential drivers of fires spread while facilitating analyses of carbon budget consequences as well as impacts to communities and timber supply.

Assay-Guided Extraction and Kinetics of Radical Scavenging Activity of Curcumin from the Rhizome of Curcuma longa Linn

Extraction of phytoceuticals from medicinal plants need to be optimized to produce standardized, dose-dependent and reliable extracts to meet food or drug administration regulations for translation into approved nutraceutical or pharmaceutical products. Effect of selected limiting extraction variables on yield and antiradical activity of curcumin-rich extract from Curcuma longa rhizomes was investigated. Assay-guided response (free radical scavenging activity) was used to determine the optimized set of extraction parameters. Curcumin-rich extract was produced using solvent boiling process at 65 oC with absolute methanol of weight ratio 1:50 (w/v) within 1 h. Relative radical scavenging activity of the extract derived using the optimized set of parameters recorded an IC50 of 497 μg/ml and its total antiradical capacity determined within 6 h (76 - 85 % at a concentration of 400 – 600 μg/ml) was not significantly different from that of commercially available natural curcumin used as reference. Time-dependent kinetic analysis revealed an initial fast burst in rate of activity (2.27 – 7.77 min-1) followed by a slow reaction rate in a steady second phase (0.12 – 0.54 min-1). Conclusively, appreciable amount of curcumin-rich extract of enhanced antiradical activity was extracted from the rhizome of C. longa using assay-guided procedure.

Start-up Performance of Low-substrate Anaerobic Ammonium Oxidation Under Different COD Concentrations

An anaerobic sequencing batch reactor(ASBR)was used to treat low-substrate simulated wastewater with NH4+-N and NO2--N concentrations of (25.00±0.40) mg·L-1 and (33.00±0.60) mg·L-1, respectively. The COD concentrations were controlled at 5.00, 15.00, 30.00, and 50.00 mg·L-1 by adding sodium acetate, and its effects on start-up of anaerobic ammonia oxidation (ANAMMOX) were investigated under the temperature of 30℃. The results showed that ① The start-up of ANAMMOX could be achieved successfully after 74, 94, 106, and 129 days. The nitrogen removal efficiency was optimum when the COD concentration was between 15.00 and 30.00 mg·L-1. In the steady phase, the average effluent concentrations of NH4+-N were 1.98 and 1.89 mg·L-1, the average effluent concentrations of NO2--N were below 0.62 mg·L-1, and the average effluent concentrations of TN were 2.37 and 2.28 mg·L-1. ② The average contribution of heterotrophic denitrification to nitrogen removal decreased to 4.78%, 9.59%, 10.21%, and 36.50%, respectively, during start-up process. The average contribution of ANAMMOX to nitrogen removal gradually increased to 95.22%, 90.41%, 89.79%, and 63.50%, respectively. ③ The activities of ANAMMOX exceeded denitrification activities at 44, 76, 86, and 114 days, respectively, which finally reached 0.700, 0.690, 0.670, and 0.510 mg·(g·h)-1, and the denitrification activities were 0.110, 0.130, 0.240 and 0.410 mg·(g·h)-1, respectively. Thus, the research results have provided references for the application of ANAMMOX to engineering.

Probability-based modeling and wind tunnel test of snow distribution on a stepped flat roof

The complex drift movement of snow particles during snowfall weather can last for several hours or even days, thereby causing dynamic changes in snow distribution on a roof. A sufficient change in a snow boundary will affect the local flow field. In this study, a probability-based half-steady Eulerian–Lagrangian method was proposed to simulate snow change on a roof. The snowfall process was divided into N steady phases, and the snow boundary of each phase was updated according to the snow deposition probability on the roof in the previous phase. In the numerical simulation, the motion of particles was described using the Lagrangian method. Calculation time was effectively reduced by computing the deposition probability of snow particles on the roof. This method was used to calculate snow distribution on a stepped flat roof model under different wind velocities. In addition, a wind tunnel test of snowfall simulation was conducted by spraying high-density silica sand particles. Results of the numerical simulation and wind tunnel test exhibited good agreement with the measured results, which accurately reproduced the typical snow distribution on the lower roof.

The Growth Differentiation Factor-15 (GDF-15) levels are increased in patients with compound heterozygous sickle cell and beta-thalassemia (HbS/βthal), correlate with markers of hemolysis, iron burden, coagulation, endothelial dysfunction and pulmonary hypertension

The clinical manifestations of Sickle Cell Disease (SCD) include episodes of vascular occlusion, chronic hemolytic anemia and frequent infections. GDF-15, a multifactorial cytokine, is a member of the transforming growth factor- superfamily. Expression of the GDF-15 gene in cardiomyocytes, vascular smooth muscle cells, and endothelial cells is strongly upregulated in response to oxidative stress, inflammation and tissue injury, while high levels of serum GDF-15 associate with ineffective erythropoiesis and may reflect a certain type of bone marrow stress or erythroblast apoptosis. In this context we aimed to evaluate GDF-15 levels in 89 patients with HbS/βthal at steady phase and in 20 apparently healthy individuals, and correlate with clinical features of the disease and markers of hemolysis, iron burden, inflammation, coagulation and endothelial dysfunction. We found that: GDF-15 levels were elevated in patients with HbS/βthal compared to controls (1980.7 ± 159.8 vs 665.4 ± 50.9 pg/mL, p < 0.0001) and correlated significantly with LDH (p < 0.001), Hepcidin-25/Ferritin molar ratio (p = 0.002), vWF:antigen (p < 0.05), HbA% (p < 0.001) and Mean Pulmonary Artery Pressure (p < 0.001). These findings demonstrate for first time an important multifactorial role of GDF-15 in patients with HbS/βthal, however, prior to its clinical usefulness, this biomarker must undergo through rigorous validation in multiple cohorts.

Drag force on an accelerating submerged plate

We present results on the drag on, and the flow field around, a submerged rectangular normal flat plate, which is uniformly accelerated to a constant target velocity along a straight path. The plate aspect ratio is chosen to be$AR=2$to resemble an oar blade in (competitive) rowing, the sport which inspired this study. The plate depth, i.e. the distance from the top of the plate to the air–water interface, the plate acceleration and the plate target velocity are varied, resulting in a plate width based Reynolds number of$4\times 10^{4}\lesssim Re\lesssim 8\times 10^{4}$. In our analysis we distinguish three phases; (i) the acceleration phase during which the plate drag is enhanced, (ii) the transition phase during which the plate drag decreases to a constant steady value upon which (iii) the steady phase is reached. The plate drag force is measured as function of time which showed that the steady-phase plate drag at a depth of$1/5$plate height (20 mm depth for a plate height of 100 mm) increased by 45 % compared to the plate top at the surface (0 mm). Also, it is shown that the drag force during acceleration of the plate increases over time and is not captured by a single added mass coefficient for prolonged accelerations. Instead, an entrainment rate is defined that captures this behaviour. The formation of starting vortices and the wake development during the time of acceleration and transition towards a steady wake are studied using hydrogen bubble flow visualisations and particle image velocimetry. The formation time, as proposed by Gharibet al.(J. Fluid Mech., vol. 360, 1998, pp. 121–140), appears to be a universal time scale for the vortex formation during the transition phase.

New Mixed Finite Element Methods for Natural Convection with Phase-Change in Porous Media

This article is concerned with the mathematical and numerical analysis of a steady phase change problem for non-isothermal incompressible viscous flow. The system is formulated in terms of pseudostress, strain rate and velocity for the Navier–Stokes–Brinkman equation, whereas temperature, normal heat flux on the boundary, and an auxiliary unknown are introduced for the energy conservation equation. In addition, and as one of the novelties of our approach, the symmetry of the pseudostress is imposed in an ultra-weak sense, thanks to which the usual introduction of the vorticity as an additional unknown is no longer needed. Then, for the mathematical analysis two variational formulations are proposed, namely mixed-primal and fully-mixed approaches, and the solvability of the resulting coupled formulations is established by combining fixed-point arguments, Sobolev embedding theorems and certain regularity assumptions. We then construct corresponding Galerkin discretizations based on adequate finite element spaces, and derive optimal a priori error estimates. Finally, numerical experiments in 2D and 3D illustrate the interest of this scheme and validate the theory.