bluuebunny/crossref_metadata_2025 huggingface dataset:
Word Retrieval Difficulties and Cognitive Control in Specific Language Impairment
Authors: Ladányi Enikő , Lukács Ágnes
Published: March 2019

Purpose

The study aims to test whether children with specific language impairment (SLI) show weaknesses in word retrieval and cognitive control and to find out whether impairments in the 2 domains are associated.

Method

Thirty-one children with SLI (age:
M
= 8;11 years;months,
SD
= 1;1) and 31 age- and IQ-matched typically developing children completed 2 word retrieval tasks and 3 cognitive control tasks. Word retrieval was assessed with a fluency task and a rapid automatized naming (RAN) task, whereas cognitive control was measured with a backward digit span, an
n
-back task, and a Stroop task.

Results

We found weaker performance in the SLI group than in the typically developing group in all the fluency conditions and in the size–color–shape RAN as well as on the backward digit span and
n
-back tasks. Performance on the letter fluency task was associated with backward digit span, whereas size–color–shape RAN performance was associated with backward digit span and
n
-back scores. Testing the relative contribution of the 3 cognitive control tasks together with verbal short-term memory span and vocabulary size showed that performance on both word retrieval tasks was best explained by nonword repetition and backward digit span measures.

Conclusions

These results suggest that both word retrieval and cognitive control are impaired in SLI and weaker cognitive control may contribute to word retrieval problems, although weaker short-term memory also has a crucial contribution to word retrieval difficulties during these tasks. If further research confirms this association with cognitive control, training of this ability should be included in the therapy of at least some children with SLI.
Consensus tracking control via iterative learning for singular multi‐agent systems
Authors: Gu Panpan , Tian Senping
Published: March 2019

This study considers the consensus tracking problem of singular multi‐agent systems by using an iterative learning control approach. Here, the communication among the followers is described by a directed graph, and only a portion of the followers can receive the leader's information. For such singular multi‐agent systems, a unified iterative learning algorithm is proposed in both continuous‐time domain and discrete‐time domain. Furthermore, the convergence condition of the algorithm is presented and analysed. In this study, the main contribution is to extend the iterative learning control theory from multi‐agent systems to singular multi‐agent systems. It is shown that the algorithm can guarantee the outputs of the followers converge to the leader's trajectory on a finite time interval along the iteration axis. Finally, the provided examples illustrate the effectiveness of the theoretical results.
Efficient and robust segmentation and tracking of sperm cells in microscopic image sequences
Authors: Mostajer Kheirkhah Fateme , Sadegh Mohammadi Hamid Reza , Shahverdi Abdolhossein
Published: March 2019

Sperm motility analysis is an important factor in male fertility diagnosis. This article presents a hybrid segmentation method to detect sperm cells, which is robust to density variation of the cells in the image sequences. In addition, a preprocessing scheme is employed to remove fixed sperm cells and debris, which facilitate and speed up the cells' tracking stage. The article also proposes an automated sperm‐tracking algorithm in semen samples image sequences. It is a multi‐step tracking scheme, which is an enhanced version of adaptive window average speed (AWAS) tracking algorithm. It retrieves lost sperm cells during the tracking stage in adjacent frames and alleviates the cells collide problem. The proposed tracking algorithm provides both superior accuracy and higher speed compared to those of the other competitive algorithms for image sequences regardless of their particle densities.
Dual‐frequency dual‐polarised shared‐aperture microstrip antenna array with suppressed higher order modes
Authors: Mathur Pratigya , Kumar Girish
Published: March 2019

Here, a dual‐frequency dual‐polarised shared aperture microstrip antenna (DFDP‐SA MSA) at S‐ and X‐bands with suppressed higher order mode is presented. The technique for higher order mode suppression comprises of a microstrip filter within the antenna, which eliminates the need of a separate RF filter in the transmitter/receiver chain. The antenna operates at two frequencies having high‐frequency ratio of 1:3.2 between them, which is utilised to its advantage by using cross‐shaped antenna at S‐band and 2 × 2 array of square patches at X‐band around it. This antenna gives measured bandwidth () of 7.4% from 2.6 to 2.8 GHz (S‐band) with measured gain of 8 dBi at 2.5 GHz and measured isolation better than 18 dB between the orthogonal ports at S‐band. It gives bandwidth of 8.7% from 7.7 to 8.5 GHz (X‐band) with measured gain of 11.5 dBi at 8 GHz and measured isolation better than 28 dB between the orthogonal ports at X‐band. The antenna is extended to 2 × 2 array for higher gain.
Platform for design, simulation, and experimental evaluation of small wind turbines
Authors: Mohammadi Ebrahim , Fadaeinedjad Roohollah , Naji Hamid Reza
Published: March 2019

Wind turbines are complicated systems with different aerodynamic and electromechanical aspects. An integrated platform which includes design, simulation, and experimental evaluation of wind energy conversion systems is very helpful to design, develop, and examine the performance of different wind turbine sub‐systems. The previous studies exclude such a platform and this study tries to fill this gap. In this study, the blades of a 5.5 kW fixed‐speed stall‐regulated wind turbine are initially designed then employed in simulation and emulation. The same as the simulation setup, the utilised emulator uses AeroDyn and FAST software tools to model the aerodynamic and mechanical aspects of the turbine in a laboratory environment. The emulator is capable of reproducing the static and dynamic behaviour of the turbine in a laboratory similar to the real turbines. For simulation, the electrical parts are implemented in MATLAB/Simulink, whereas the real electrical parts are used for the emulator. The performance of the turbine with the designed blades is investigated in simulation and emulation considering a simple hub‐height and turbulent wind profile, generated by TurbSim software tool based on the IEC standards. Moreover, the start‐up process of the wind turbine is evaluated using the wind turbine emulator and the results are discussed.
Optimal bidding strategy for wind farms considering local demand response resources
Authors: Zhao Shengnan , Wang Beibei , Yang Xuechun , Yang Shengchun
Published: March 2019

The negative impacts imposed by wind power on power systems can be decomposed into different time scales. Demand response (DR) can relieve these impacts by providing different auxiliary services. However, based on the current integration requirement, wind farms cannot earn more even if they try to provide power with less negative impacts. In this regard, three indicators are proposed for three different time scales to evaluate these efforts of wind power resources. The system operator sets the purchasing price of wind power by using these indicators. It aims to encourage wind farms to improve their output curves by purchasing the DR supporting services products. In the next step, a bi‐level optimisation model is developed to assist the wind farms in their bidding and DR purchasing strategies. The case studies show that the proposed model can reduce wind power curtailment and improve the power's features. Moreover, by using the indicators as the integration requirement, the revenue of wind farms and the economic benefit of system dispatch are improved.
Bi‐level model for generation expansion planning with contract pricing of renewable energy in the presence of energy storage
Authors: Rafiei Seyed Arash , Mohammadi‐ivatloo Behnam , Asadi Somayeh , Goldani Saeedreza , Falaghi Hamid
Published: March 2019

This study presents a bi‐level model for expansion planning of generation systems. The proposed model endogenously determines the incentive to invest (guaranteed purchase contract) for wind and storage units. In the upper level of the proposed model, wind turbines and compressed air storage systems focus on maximising their profits by presenting a strategic offering, while at the lower level, there is an independent system operator with the purpose of increasing social welfare run the market clearing equations. In solving the bi‐level model, the Karush–Kuhn–Tucker conditions are used to develop the mathematical program with equilibrium constraints. The problem was first linearised and then solved by GAMS software. The outputs of this problem are the installation time and capacity of the wind and storage units and the price of the purchase contract. The obtained results were compared with other existing studies for verification purposes.
An Investigation of Recovery Mechanisms for Oil Field Optimization by Three-Phase Core Flood and Simulation Studies
Authors: Jones C. , Brodie J. , Spearing M. , Lamb S. , Sadikoglu K.
Published: March 2019

Two potential recovery mechanisms are being considered for a major ﬁeld which required laboratory measurements to investigate the efﬁciency of the two scenarios: gas ﬂood followed by water ﬂood and water ﬂood followed by gas ﬂood. Although simply stated, the recovery scenarios involved complex three-phase processes which had to be replicated in the laboratory at reservoir conditions to provide reliable data upon which reservoir development decisions could be made. The ﬁrst sequence consisted of water displacing oil to residual oil saturation (Sorw), oil displacing water to residual water saturation (Swro) and gas displacing both oil and water to Sor3φ,g and Swr3φ,g. The second sequence consisted of gas displacing oil to residual oil saturation (Sorg), oil displacing gas to trapped gas saturation (Sgto) and water displacing both oil and gas to Sor3φ,w and Sgt3φ,w respectively. Composite cores of four well-matched plugs at Swi were used and all measurements were made at bubble point conditions. A vertical core holder was housed inside a reservoir condition facility equipped with gamma attenuation saturation monitoring (GASM). Temperature stability and the use of GASM were paramount for the accurate measurement of produced ﬂuids, especially trapped gas saturation. Oil, gas and water produced volumes were also measured using a separator housed inside the core ﬂood oven to provide optimum temperature stability. The laboratory results were modelled in a compositional simulator using an equation of state tuned to conventional PVT data and both swelling and multiple contact experiments. The objective was to build a three-phase predictive model from the constituent two-phase relative permeability data. The paper details the experimental methods and presents results for each section of the two sequences. The key conclusions are that Sorg>Sorw> Sor3φ,g> Sor3φ,w and Sgt3φ,w< Sgto.
Measurement of Spontaneous Imbibition Capillary Pressure, Saturation and Resistivity Index by Counter Current Technique at Net Reservoir Stress and Elevated Temperature
Authors: Pruno Stefano , Rodvelt Hans Erik , Skjæveland Ola
Published: March 2019

Capillary pressure and resistivity index spontaneous imbibition experiments by the porous plate method, in a core holder at elevated temperature and net reservoir stress, are both difficult and time consuming special core analysis measurements to perform. In this type of experiment, low capillary forces act against a low permeable porous plate and only one face of the cylindrical core sample is in capillary contact with the fluid saturated porous plate. In this paper, core samples having different lithology, petrophysical properties and wettability are analysed by counter current spontaneous imbibition, starting at initial water saturation (Swi), at net confining pressure and elevated temperature. Synthetic brine is used as the wetting phase and Isopar L mineral oil as the non-wetting phase. This methodology is applied to investigate and evaluate how to obtain more reliable, more efficient and faster saturation imbibition data combined with electrical measurements, during spontaneous imbibition measurements. Resistivity index (RI), saturation exponent (n) (by single saturation equilibrium point using Archie’s second law RI= Sw-n) and wettability information using representative fluids, confining pressure and temperature are also obtained by applying this specific counter current imbibition technique and improved procedural approach.
A fast method for trapped gas determination
Authors: Faurissoux Pierre , Lutui−Tefuka Moeata , Caubit Cyril , Lalanne Bruno , Nicot Benjamin
Published: March 2019

Gas reservoirs are mainly produced by depletion with an aquifer rise; reservoir simulation requires two main SCAL inputs: the amount of trapped gas by the aquifer (residual gas saturation: Sgr) and the relative permeability to water due to aquifer flooding. As it is quasi impossible to predict aquifer strength, the primary SCAL input for reservoir simulation is the Sgr. The recovery factor is directly defined by initial and residual gas saturations. In fact, the residual gas saturation Sgr highly depends on the initial gas saturation Sgi and there is no universal petrophysical parameter governing the shape of this curve. This relationship can be described by several different models (Land, Aissaoui…). While Land’s model is widely used, the Aissaoui model better fits the experimental results (Suzanne et al. 2003), at least for homogeneous sandstones. For a given threshold of initial gas saturation Sg0, this relationship typically exhibits a plateau at high Sgi>Sg0 and an increasing linear trend at low Sgi<Sg0. The challenge here is to properly estimate the value of the Sg0 threshold. Classical laboratory method would require one experiment per point in the Sgr/Sgi plot, and therefore can be achieved in a matter of months. Here we propose a laboratory method allowing the acquisition of the Sgr/Sgi curve in a few days. The proposed method combines centrifugation and capillary rise under imaging. First, the centrifuge allows creating a saturation profile along a sample; measured by NMR. Then, capillary rise is used to capture Sgr under NMR monitoring. By adding NMR imaging, this technique allows combining the benefits of centrifugation to explore a wide range of Sgi; and the ease and cost effectiveness of capillary rise to measure the resulting Sgr. Therefore, at a timescale close to a traditional capillary rise, the proposed technique avoids Land extrapolation and provides a direct measurement of Sgr in a wide range of Sgi. As an additional benefit, the combination of NMR and centrifuge can provide at the same time a direct measurement of capillary pressure, providing information on the gas in place and potential imbibition process in the reservoir.
Monitoring gas hydrate formation with magnetic resonance imaging in a metallic core holder
Authors: Shakerian Mojtaba , Afrough Armin , Vashaee Sarah , Marica Florin , Zhao Yuechao , Zhao Jiafei , Song Yongchen , Balcom Bruce J.
Published: March 2019

Methane hydrate deposits world-wide are promising sources of natural gas. Magnetic Resonance Imaging (MRI) has proven useful in previous studies of hydrate formation. In the present work, methane hydrate formation in a water saturated sand pack was investigated employing an MRI-compatible metallic core holder at low magnetic ﬁeld with a suite of advanced MRI methods developed at the UNB MRI Centre. The new MRI methods are intended to permit observation and quantiﬁcation of residual ﬂuids in the pore space as hydrate forms. Hydrate formation occurred in the water-saturated sand at 1500 psi and 4 °C. The core holder has a maximum working pressure of 4000 psi between -28 and 80 °C. The heat-exchange jacket enclosing the core holder enabled very precise control of the sample temperature. A pure phase encode MRI technique, SPRITE, and a bulk T1-T2 MR method provided high quality measurements of pore ﬂuid saturation. Rapid 1D SPRITE MRI measurements time resolved the disappearance of pore water and hence the growth of hydrate in the sand pack. 3D π-EPI images conﬁrmed that the residual water was inhomogeneously distributed along the sand pack. Bulk T1-T2 measurements discriminated residual water from the pore gas during the hydrate formation. A recently published local T1-T2 method helped discriminate bulk gas from the residual ﬂuids in the sample. Hydrate formation commenced within two hours of gas supply. Hydrate formed throughout the sand pack, but maximum hydrate was observed at the interface between the gas pressure head and the sand pack. This irregular pattern of hydrate formation became more uniform over 24 hours. The rate of hydrate formation was greatest in the ﬁrst two hours of reaction. An SE-SPI T2 map showed the T2 distribution changed considerably in space and time as hydrate formation continued. Changes in the T2 distribution are interpreted as pore level changes in residual water content and environment.
The role of ferrous clays in the interpretation of wettability – a case study
Authors: Velazco M.A , Bruce A. , Ferris M. , Reed J. , Kandasamy R.
Published: March 2019

Clean sandstone, with minimal clay content, is expected to be strongly water wet once the rock has been through an effective cleaning process. Even samples containing significant clay minerals are usually expected to be water wet after appropriate cleaning. However, tests carried out on core samples from Fields in three different global locations show mixed indices, even for clean state samples where no aging with crude oil has taken place. A few hypotheses for this behaviour considered herein are: whether the cleaning method was adequate, whether wettability was altered by an external factor, or if wettability was due to mineral composition. This paper presents the results obtained from wettability studies on fresh, clean and restored state core plug samples from three different Fields. Wettability indices were obtained by using the combined Amott-USBM method. Petrography was performed on sample end-trims to investigate the possible presence of halite or barite in the clean state samples, thought to be from drilling fluid infiltration, which should have been removed by the methanol cleaning cycle. This showed no organic material or salt (halite), negating wetting change from inefficient cleaning. From a reactive clays [1] model perspective, these rock samples are considered clean-sand (i.e. illite/ smectites- as total clay content), determined by XRD analysis, are lower than 10%. SEM and XRD results showed the presence of grain-coating chlorite in one sample set and glauconite grains in the others. Only once the unusual wettability indices were obtained was the grain-coating chlorite identified as chamosite by SEM/EDX, which is an iron-rich form of chlorite. The presence of chamosite or glauconite appears to influence the wetting tendency. In summary, USBM vs Amott wettability indices of the analysed samples are consistent between both methods, showing a mixed to oil-wet tendency for all samples where chamosite was identified, regardless of the initial test condition. Samples with glauconite appeared to be more mixed wet after wettability restoration. The results suggest that iron rich clay/mineral content is the main contributor to the oil wet tendency of the evaluated rocks.
Rheology-based method for calculating polymer inaccessible pore volume in core flooding experiments
Authors: Ferreira V. H. S. , Moreno R. B. Z. L.
Published: March 2019

Polymer flooding is an enhanced oil recovery (EOR) method that reduces the mobility ratio between the displaced oil and the displacing injected water. The flow of polymer solutions through porous media is subject to some process-specific phenomena, such as the inaccessible pore volume (IAPV). Due to IAPV, polymer molecules move faster through the porous medium than smaller ones. Thus the IAPV value needs to be accounted for in experiments and field projects. Recent reports found that polymer in-situ rheology correlates with the IAPV. The objective of this paper is to develop a method for estimating IAPV based on the in-situ rheology of polymers. The methodology proposed here can be used in both single- and two-phase experiments. The technique requires measurement of polymer resistance factor (RF) and residual resistance factor (RRF) at steady state conditions. Core permeability, porosity, and residual oil saturation, as well as water and polymer bulk viscosities, also need to be taken into account. Correlations for polymer in-situ viscosity and shear rate are solved simultaneously, to wield an estimative for the IAPV. Aiming at to prove the method, we report 16 core-flooding experiments, eight single- and eight two-phase experiments. We used a flexible polymer and sandstone cores. All the tests were run using similar rock samples. In the single-phase experiments, we compare the alternative method with the classic tracer method to estimate IAPV. The results show an average relative difference of 11.5% between the methods. The two-phase results display, on average, an 18% relative difference to the IAPV measured in the single-phase experiments. The difference between single- and two-phase results can be an effect of the higher shear rates experienced in the two-phase floodings since, in these cases, the aqueous phase shear rate is also dependent on the phase saturation. Additionally, temperature, core length, pore pressure, and iron presence on the core did not show any influence on the IAPV for our two-phase experiments. The method proposed in this paper is limited by the accuracy of the pressure drop measurements across the core. For flexible polymers, the method is valid only for low and mid shear rates, but, accoording to literature, for rigid polymers the method should be accurate for a broad range of shear rates. The method proposed here allows the measurement of polymer IAPV on two- and single- phase core-flooding experiments when a tracer is not used.
A novel experimental approach for studying spontaneous imbibition processes with alkaline solutions
Authors: Chevalier T. , Labaume J. , Delbos A. , Clemens T. , Waeger V. M. , Bourbiaux B. , Fleury M.
Published: March 2019

Spontaneous imbibition processes can play an important role in oil production. It can be enhanced or influenced by wettability changes generated by properly designed chemicals or by the natural surfactants resulting from reactive crude oils in the presence of alkaline solutions. The reaction of basic salts with some components of oil can, indeed, lead to the formation of natural soaps that reduces the interfacial tension between oil and brine. The latter scenario is studied herein on samples and oil from the St Ulrich oil field in the Vienna basin. To that end, spontaneous imbibition experiments were performed with two brines differing by the absence or presence of alkali. We first present a general novel technique to monitor saturation changes on small rock samples for the purpose of assessing the efficiency of a given recovery process. Samples of only 15 mm in diameter and 20 mm in length and set at irreducible saturation were fully immersed in the solution of interest, and the evolution of the samples’ saturation with time was monitored thanks to a dedicated NMR technique involving the quantification of the sole oil phase present within the sample. A fully-3D imbibition configuration was adopted, involving counter-current flows through all faces of the sample. The experimental method is fast for two reasons: (i) the kinetics of capillary imbibition process is proportional to the square of sample size, i.e. very rapid if accurate measurements can be acquired on tiny samples, (ii) the present 3D situation also involves faster kinetics than the 1D configuration often used. The NMR technique was crucial to achieve such conditions that cannot be satisfied with conventional volumetric methods. The kinetics of oil desaturation during spontaneous imbibition is interpreted with the help of an analytical 3D diffusion model. For the alkaline solution, the diffusion coefficient is reduced by a factor of only two compared to the non-alkaline brine, although the interfacial tension between the oil and the imbibing solution is reduced by a factor of 10. Hence, a wettability change to a more water wet state has to be assumed when the alkaline solution replaces the non-alkaline solution in the imbibition process. However, no significant impact on the final saturation was observed.
A digital rock physics approach to effective and total porosity for complex carbonates: pore-typing and applications to electrical conductivity
Authors: Arns Christoph H. , Jiang Han , Dai Hongyi , Shikhov Igor , Sayedakram Nawaf , Arns Ji-Youn
Published: March 2019

Recent advances in micro-CT techniques allow imaging heterogeneous carbonates at multiple scales and including voxel-wise registration of images at different resolution or in different saturation states. This enables characterising such carbonates at the pore-scale targeting the optimizing of hydrocarbon recovery in the face of structural heterogeneity, resulting in complex spatial fluid distributions. Here we determine effective and total porosity for different pore-types in a complex carbonate and apply this knowledge to improve our understanding of electrical properties by integrating experiment and simulation in a consistent manner via integrated core analysis. We consider Indiana Limestone as a surrogate for complex carbonate rock and type porosity in terms of macro- and micro-porosity using micro-CT images recorded at different resolution. Effective and total porosity fields are derived and partitioned into regions of macro-porosity, micro-porosity belonging to oolithes, and micro-porosity excluding oolithes’ rims. In a second step we use the partitioning of the micro-porosity to model the electrical conductivity of the limestone, matching experimental measurements by finding appropriate cementation exponents for the two different micro-porosity regions. We compare these calculations with calculations using a single cementation exponent for the full micro-porosity range. The comparison is extended to resistivity index at partial saturation, further testing the assignment of Archie parameters, providing insights into the regional connectivity of the different pore types.
A nobel cause: public engagement and outreach
Authors: Holmes Christopher , John Pearl , Stirling Callum
Published: March 2019

Showcasing cutting edge physics research to school children and the general public humanizes ‘the scientist’. This can help towards removing stereotypes and enabling greater diversity in physics. Here we share some of the lessons learnt and activities conducted at the University of Southampton to achieve this goal.
Combined face based and nodal based discretizations on hybrid meshes for non-isothermal two-phase Darcy flow problems
Authors: Beaude L. , Masson R. , Lopez S. , Samier P.
Published: March 2019

In the last 20 years many discretization schemes have been developed to approximate the Darcy fluxes on polyhedral cells in heterogeneous anisotropic porous media. Among them, we can distinguished cell based approaches like the Two Point Flux Approximation (TPFA) or the Multi Point Flux Approximation (MPFA) schemes, face based approaches like the Hybrid Finite Volume (HFV) scheme belonging to the family of Hybrid Mimetic Mixed methods and nodal based discretizations like the Vertex Approximate Gradient (VAG) scheme. They all have their own drawbacks and advantages which typically depend on the type of cells and on the anisotropy of the medium. In this work, we propose a new methodology to combine the VAG and HFV discretizations on arbitrary subsets of cells or faces in order to choose the best suited scheme in different parts of the mesh. In our approach the TPFA discretization is considered as an HFV discretization for which the face unknowns can be eliminated. The coupling strategy is based on a node to face interpolation operator at the interfaces which must be chosen to ensure the consistency, the coercivity and the limit conformity properties of the combined discretization. The convergence analysis is performed in the gradient discretization framework and convergence is proved for arbitrary cell or face partitions of the mesh. For face partitions, an additional stabilisation local to the cell is required to ensure the coercivity while for cell partitions no additional stabilisation is needed. The framework preserves at the interface the discrete conservation properties of the VAG and HFV schemes with fluxes based on local to each cell transmissibility matrices. This discrete conservative form allows to naturally extend the VAG and HFV discretizations of two-phase Darcy flow models to the combined VAG–HFV schemes. The efficiency of our approach is tested for single phase and immiscible two-phase Darcy flows on 3D meshes using a combination of the HFV and VAG discretizations as well as for non-isothermal compositional liquid gas Darcy flows on a vertical 2D cross-section of the Bouillante geothermal reservoir (Guadeloupe) using a combination of the TPFA and VAG discretizations.
A review on newer techniques in extraction of oleaginous flaxseed constituents
Authors: Sharma Mayuri , Dadhwal Kritika , Gat Yogesh , Kumar Vikas , Panghal Anil , Prasad Rasane , Kaur Sawinder , Gat Punam
Published: March 2019

Flaxseed is the chief oilseed crop that is grown in many regions of the world for medicinal and nutritional purposes. It has been used for oil and fiber since centuries. Flaxseed has an enormous role in functional foods for its nutritional and pharmaceutical values. Among the various components of flaxseed lignans, phenolic acids, proteins and oil are of the main interest. Oil and lignans have prime concentrations in the flaxseed. To study the extraction of these compounds, various extraction methods have been investigated. Oil has been extracted by mechanical pressing in ancient times but presently new techniques have been developed. These include microwave assisted extraction, supercritical CO2 extraction, ultrasonic assisted extraction, etc. Enzymes are also gaining importance in the extraction of oil, lignan and proteins as they give more yield of compounds and easily degrade the cell wall of the flaxseed. The need of these novel techniques lies in the fact that traditional methods have different shortcomings like low yield, more time, more energy and less environmental friendly. This review put on a view to different techniques which have been investigated for the extraction of different components of flaxseed. Quality evaluation and comparison of flaxseed oils and other bioactive components obtained by newer techniques with those produced by conventional extraction methods is also reported.
Digitale Kardiologie
Authors: Meder Benjamin , Radke Peter
Published: March 2019

Was ist neu?

Aktuelle Entwicklungen der modernen Medizin Künstliche Intelligenz, Big Data und mobile Sensorik transformieren derzeit die Kardiologie. Fortschrittliche digitale Konzepte spielen in vielen Bereichen der Kardiologie eine immer wichtigere Rolle und werden sich schnell als Partner von Arzt und Patient etablieren können.

Big Data und künstliche Intelligenz Künstliche Intelligenz (KI) hält Einzug in den digitalen Arztalltag und ist keine Science-Fiction mehr. Spezielle Algorithmen kommen heute bereits im Rahmen diagnostischer Prozesse zum Einsatz und bieten großes Potenzial für die Zukunft.

Smartphones, Apps und Co. Smartphones und Wearables können über die Anwendung von speziellen Apps im Bereich der Kardiologie eingesetzt werden. Die neue DSGVO erschwert die Entwicklung neuer Kommunikationskanäle unter Ärzten und zwischen Ärzten und Patienten. Neue Apps, Messenger und Verschlüsselungssysteme sollen die Sicherheit der sensiblen Daten gewährleisten.
Digitale Nephrologie
Authors: Becker Stefan , Budde Klemens , Tillmann Frank-Peter , Koisar Karoline , Wamprecht Laura , Müschenich Markus , Meister Sven , Roller Roland
Published: March 2019

Was ist neu?

Stand der Dinge Die Nephrologie steht vor erheblichen strukturellen Herausforderungen. Die Digitalisierung kann ein entscheidender Katalysator sein, um mit neuen Systemlösungen den Bedürfnissen von Patienten und ihren versorgenden Ärzten besser gerecht zu werden.

Digitalisierung als „Game Changer“ in der Medizin Der Durchbruch der digitalen Medizin steht noch bevor; digitale Lösungen haben das Potenzial, das Gesundheitswesen und die klinische Arbeit am Patienten grundlegend zu verändern.

Bedürfnis nach Kommunikation und gesundheitsbezogenen Mobilapplikationen (mHealth) Eine verbesserte Kommunikation ist der entscheidende Treiber. Über gesundheitsbezogene Mobilapplikationen können Behandlungsprozesse neu gedacht und gestaltet werden.

Big Data und maschinelles Lernen Durch maschinelle Unterstützungssysteme könnte die Diagnosestellung insgesamt sicherer und schneller gestaltet werden, sodass in der Folge dem Arzt mehr Zeit für eine bedarfsadaptierte individuelle Patientenberatung zur Verfügung stehen würde.

Natürliche Sprachverarbeitung Mithilfe künstlicher Intelligenz können Patientendaten besser analysiert und beispielsweise zur Früherkennung seltener Erkrankungen auf Grundlage von Symptomen schneller erkannt werden.
Strukturierte Karrierewege in der Universitätsmedizin
Authors: Thimme Robert , Pahl Heike , Werner Karin , Nagel Irene , Bruckner-Tuderman Leena
Published: March 2019

Scientifically active medical doctors are required for successful translation of novel basic findings into the clinic. However, there is an increasing tendency of young medical doctors to primarily follow a more clinically and not scientifically orientated career pathway. Therefore, the establishment of novel career education structures and career perspectives in university medicine are important to stop this development. Here, we will discuss the current situation and ongoing attempts to design novel structural programs that allow a better combination of clinical and scientific work by highlighting also current developments at the Faculty of Medicine at the University of Freiburg.
Neuroimaging in Dementias
Authors: Mahalingam Sowmya , Chen Ming-Kai
Published: March 2019

Dementia is a global health issue, the burden of which will worsen with an increasingly aging population. Alzheimer's disease (AD) is the most common dementia, with 50 to 60% of all dementias attributable to AD alone, while the rest are mostly due to frontotemporal lobar dementia, dementia with Lewy bodies, Parkinson's disease dementia, and vascular dementia. Diagnosis of dementias is made clinically with the aid of other testing modalities including neuroimaging. While the role of imaging has traditionally been to exclude reversible causes of dementia, positron emission tomography (PET) with 18-fluorine fluorodeoxyglucose and magnetic resonance imaging now are increasingly used more for definitive diagnosis of dementia in the prodromal stages and to aid with formulating the differential diagnoses. Introduction of molecular imaging modalities such as amyloid PET and tau PET have improved diagnostic certainty in the clinical trial setting and promise to find their way into the clinic in the near future. In this review, we will focus on the multimodality imaging of dementias especially AD and its differential diagnoses.
Vascular Cognitive Disorder
Authors: Paradise Matt , Sachdev Perminder
Published: March 2019

The term vascular cognitive disorder (VCD) refers to a heterogeneous group of disorders in which the primary feature is cognitive impairment attributable to cerebrovascular disease (CVD). This includes not only vascular dementia (VaD) but also cognitive impairment of insufficient severity to meet diagnostic criteria for dementia. VCD is recognized as the second most common cause of dementia after Alzheimer's disease (AD), but prevalence rates vary widely according to the diagnostic criteria employed. There have been recent attempts to standardize diagnostic criteria. VCD incorporates a range of neuropathological mechanisms including poststroke impairment, small and large vessel disease, and cases of mixed-pathology, with CVD interacting with AD and other neuropathologies. Recent neuroimaging data have improved our understanding of the etiology of VCD. Symptomatic treatments for VaD have modest benefit and there is increased focus on the primary and secondary preventative benefits of vascular risk factor control.
Interventional Radiology: A Potential Antidote to Physician Burnout
Authors: Knox Michael
Published: March 2019

Physician burnout affects more than half of U.S. physicians, is multifactorial in origin, and should be addressed at organizational, group, and individual levels. By examining the career of one private practice interventional radiologist, insight into lessons learned and strategies for promotion of a fulfilling career might apply to others. Priorities may vary depending on stage of career, but some common themes of meaning and purpose that most interventional radiology (IR) physicians embrace throughout their careers emerge. Recognizing and cultivating these might provide keys to mitigating professional burnout and promoting a fulfilling IR career.
Value of Interventional Radiology: Past, Present, and Future
Authors: Doherty Michael
Published: March 2019

Interventional radiology (IR) has had immense growth in importance and value over the last several decades from its founding in the mid-20th century. IR procedures have been widely adopted and an era of IR clinical expertise is upon us. Despite this, there is a perception that IR is simply an imaging study to be ordered and that IR physicians are expendable. This article attempts to explore that. Questionnaires were sent to other specialties and administrators asking key questions regarding the value of IR as a specialty, both for procedural and consultative expertise as well as their thoughts on the future of IR. Answers varied, but consistent opinions were observed that IR is extremely valuable, both procedurally and consultatively, and that expansion of IR services is likely. IR is extremely valuable given its impact on healthcare (lessening morbidity, decreasing length of stay, improving cost) and although there is some misperception of this value, other specialties and administrators understand it well. Newer generations of IR physicians are poised to become even more impactful if they continue to expand their clinical presence.
Alzheimer's Disease Including Focal Presentations
Authors: Villain Nicolas , Dubois Bruno
Published: March 2019

Alzheimer's disease (AD) is the commonest neurodegenerative disease and the most frequent cause of dementia. It affects 30 million people worldwide. Current research criteria focus on biomarkers' status for amyloid and tau using positron emission tomography and cerebrospinal fluid analysis, independent of clinical status. Current epidemiological data, which mostly rely on biomarker-undetermined AD cases, have highlighted ApoE4 and age as the main risk factors. Rare autosomal dominant mutations also account for a small fraction of early-onset AD. The main clinical phenotype at presentation is the amnestic phenotype targeting episodic memory. This is followed by rarer phenotypes such as posterior cortical atrophy, logopenic variant of primary progressive aphasia, frontal variant AD, corticobasal syndrome, and other even rarer presentations mimicking language variants of frontotemporal dementia. Main differential diagnoses include hippocampal sclerosis with TDP-43, primary age-related tauopathy, argyrophilic grain disease, frontotemporal lobar degeneration, Lewy body disease, chronic traumatic encephalopathy as well as nondegenerative disorders such as cerebrovascular disease, chronic alcohol consumption, limbic encephalitis, medial temporal lobe epilepsy, and others. Co-occurrence of AD pathology with other neurodegenerative and vascular diseases is common and increases with age. This presents a challenge in current clinical practice due to a lack of reliable biomarkers for non-AD neurodegenerative diseases.
A Comprehensive Update on Treatment of Dementia
Authors: Tisher Annya , Salardini Arash
Published: March 2019

Treatment of dementias represents an important but relatively neglected part of neurological care of the elderly population. Individual therapeutic interventions may make only small changes to the quality of life of individuals afflicted with dementia, but when used in combination these interventions synergize and can make a significant difference. Additionally, given the societal scale of the problem of dementia care, the overall impact, in economic and sociological terms, of such therapies is of consequence. Presently there are no disease-modifying treatments for any of the neurodegenerative dementias. Instead, the clinician has several therapeutic tools to mitigate cognitive and behavioral consequences of dementias. There are also strategies to minimize harm to patients with dementia. In this article, we aim to review these tools and place them in the greater context of dementia care.
A note on the velocity derivative flatness factor in decaying HIT
Authors: Djenidi L. , Danaila L. , Antonia R. A. , Tang S.
Published: March 2019

We develop an analytical expression for the velocity derivative flatness factor, F, in decaying homogenous and isotropic turbulence (HIT) starting with the transport equation of the third-order moment of the velocity increment and assuming self-preservation. This expression, fully consistent with the Navier-Stokes equations, relates F to the product between the second-order pressure derivative (∂2p/∂x2) and second-order moment of the longitudinal velocity derivative ((∂u/∂x)2), highlighting the role the pressure plays in the scaling of the fourth-order moment of the longitudinal velocity derivative. It is also shown that F has an upper bound which follows the integral of k*4Ep*(k*) where Ep and k are the pressure spectrum and the wavenumber, respectively (the symbol * represents the Kolmogorov normalization). Direct numerical simulations of forced HIT suggest that this integral converges toward a constant as the Reynolds number increases.
Dynamics of an adenine-adenine RNA conformational switch from discrete path sampling
Authors: Chakraborty Debayan , Wales David J.
Published: March 2019

The study of “rare event” dynamics can be challenging despite continuing advances in computer hardware. A wide variety of methods based on the master equation approach have been developed to tackle such problems, where the focus is on Markovian dynamics between appropriately defined states. In this contribution, we employ the discrete path sampling approach to characterize pathways and rates for an adenine-adenine RNA conformational switch. The underlying free energy landscape supports competing structures separated by relatively high barriers, with the two principal funnels leading to the major and minor conformations identified by NMR experiments. The interconversion time scale is predicted to be a few hundred seconds, consistent with the experimental lower bound estimates. We find that conformational switching occurs via stacked intermediates, through a sliding mechanism, in agreement with a previous simulation study. By retaining full dimensionality and avoiding low-dimensional projections, the mechanism can be described at an atomistic level of detail.
Comparison of free convection flow around an engineered porous fin with spherical connections and rigid fin under different positioning angles—An experimental and numerical analysis
Authors: Mesgarpour Mehrdad , Heydari Ali , Saedodin Seyfolah
Published: March 2019

In this paper, the free convective flow around an engineered porous fin with spherical connections is investigated experimentally and numerically. In addition, the effects of different positioning angles for different fin materials on thermal fin performance are analyzed. First, the copper, aluminum, and brass fins are made and their thermal performances under free convective flow are examined experimentally. Then, in order to extend the results, after validation the numerical analysis is carried out in steady and three-dimensional calculations. Then, at different positioning angles, the formed free convective flow around the porous fin is analyzed numerically and compared with the results of a rigid fin. The results show that the efficiency of the copper fins at all positioning angles is maximal. It was also found that the highest amount of Nusselt number occurs at the angle of 45°. In the numerical investigations, it is determined that the maximum increase in the Nusselt number of the engineered porous fins is about two times that of the rigid fin. Moreover, a relationship between the Nusselt number and the Rayleigh number is presented for a horizontal engineered porous fin in laminar free convection flow.
Theoretical insights into mechanisms of channel-facilitated molecular transport in the presence of stochastic gating
Authors: Davtyan Aram , Kolomeisky Anatoly B.
Published: March 2019

Molecular motion through pores plays a crucial role in various natural and industrial processes. One of the most fascinating features of biological channel-facilitated transport is a stochastic gating process, when the channels dynamically fluctuate between several conformations during the translocation. Although this phenomenon has been intensively investigated, many properties of translocation in a dynamically changing environment remain not well understood microscopically. We developed a discrete-state stochastic framework to analyze the molecular mechanisms of transport processes with stochastic gating by explicitly calculating molecular fluxes through the pores. Two scenarios are specifically investigated: (1) symmetry preserving stochastic gating with free-energy changes and (2) stochastic gating with symmetry changes but without modifications in the overall particle-pore interactions. It is found that stochastic gating can either accelerate or slow down the molecular translocation depending on the specific parameters of the system. We argue that biological systems might optimize their performance by utilizing conformational fluctuations of channels. Our theoretical analysis clarifies physical-chemical aspects of the molecular mechanisms of transport with stochastic gating.
Bi-directional transportation of micro-agents induced by symmetry-broken acoustic streaming
Authors: Mohanty Sumit , Siciliani de Cumis Ugo , Solsona Miguel , Misra Sarthak
Published: March 2019

We show that vibrating protrusions inside a microchannel are capable of steering fluid away from their relative orientation. This phenomenon is brought forth by symmetry-broken design of these protrusions. Vibration of these asymmetric protrusions is reciprocated in the streaming effect at the boundary layers of the channel thus inducing a net fluid flow. Additionally, we show that the flow direction is sensitive to switching acoustic frequencies. This acoustically-induced flow has the potential for transportation of nanoparticles as well as complex micro-structures. We hereby demonstrate this utility for contactless actuation of flagellar micro-agents as a foreground towards targeted drug release.
The seed energy fluctuation of hard X-ray self-seeding free electron laser
Authors: Yang C. , Wang X. , Tsai C.-Y. , Zhou G. , Zhang Z. , Krug E. D. , Li A. , Deng H. , He D. , Wu J.
Published: March 2019

Self-seeding free electron lasers (FELs) are capable of generating fully coherent X-ray pulses. However, the stability of output pulse energy of hard X-ray self-seeding (HXRSS) FEL is poor. This letter reports the seed energy stability investigation of HXRSS FEL. For the purpose of a more stable HXRSS FEL, this work suggests a relatively broad bandwidth ρt of crystal monochromator, a relatively long electron bunch with energy jitter (r.m.s.) down to a quarter of FEL Pierce parameter ρ, and a larger Bragg angle θB to improve the seed energy stability. Moreover, the angle jitter (r.m.s.) between the SASE pulse incident direction and the crystal surface should be less than (ρ tan θB)/2, and the relative time jitter (r.m.s.) between the electron bunch and the seed should be less than half of the seed bump duration Tt.