bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep emotion recognition based on audio–visual correlation
Authors: Hajarolasvadi Noushin , Demirel Hasan
Published: June 2020

Human emotion recognition is studied by means of unimodal channels over the last decade. However, efforts continue to answer tempting questions about how variant modalities can complement each other. This study proposes a multimodal approach using three‐dimensional (3D) convolutional neural networks (CNNs) to model human emotion through a modality‐referenced system while investigating the solution to such questions. The proposed modality‐referenced system selects the input data based on one of the modalities regarded as reference or master. The other modality which is referred to as a slave simply adjusts or attunes itself with the master in the temporal domain. In this context, the authors developed three multimodal emotion recognition system, namely, video‐referenced system, audio‐referenced system, and the audio–visual‐referenced system to explore the congruence impact of audio and video modalities on each other. Two pipelines of 3D CNN architectures are employed where k‐means clustering is used in the master pipeline and the slave pipeline adapts itself in a temporal sense. The outputs of the two pipelines are fused to improve recognition performance. In addition, canonical correlation analysis and t‐distributed stochastic neighbour embedding is used validating the experiments. Results show that temporal alignment of the data between two modalities improves the recognition performance significantly.
Using EVs as distributed energy resources for critical load restoration in resilient power distribution systems
Authors: Momen Hamidreza , Abessi Ahad , Jadid Shahram
Published: June 2020

Owing to the important role of the power system in modern societies, its resilience against natural disasters has become a top priority for power system operators and planners. Moreover, in recent years, due to the increasing number and severity of weather‐related events, several operational solutions have been proposed to increase the resilience of power systems. For instance, in the distribution part of power systems, dynamic micro‐grid (MG) formation can enhance resilience by means of distributed energy resources (DERs) when the main grid is unavailable. Following this concept, the capabilities of electric vehicles (EVs) such as vehicle‐to‐grid make it possible to use the energy stored inside them to restore critical loads. Therefore, the aggregation of EVs in the distribution system can be seen as a DER from the system operator viewpoint, and operators can benefit from this limited energy resource in MG formation. This study uses two types of EV aggregation for this purpose, i.e. a public parking lot and a residential parking. To improve system performance when using these resources, two steps should be taken: (i) employing a master–slave control technique in each MG and (ii) using a demand‐side management programme.
Stabilising influence of a synchronous condenser in low inertia networks
Authors: Arayamparambil Vinaya Mohanan Vishnu , Mareels Iven M.Y. , Evans Robin J. , Kolluri Ramachandra Rao
Published: June 2020

Power systems have to be reinforced to accommodate a high penetration of renewable energy sources. Recent research shows that the stability margin of the grid degrades with the penetration of grid‐tied photovoltaic generators into the grid. In the model presented in the study, the critical level of photovoltaic penetration is associated with a Hopf bifurcation in the field dynamics of the synchronous generators which severely limits the operating domain of the grid. It is shown that the judicious introduction of synchronous condensers in the modelled grid delays this dynamic instability. A small‐signal analysis is performed for a system where the reactive power and inertial response is supplemented using a synchronous condenser. The study shows that the modified network tolerates much higher participation of photovoltaic generation in the grid. It is shown that the modified network retains the classical power system control approach and also does not demand a change in the way the photovoltaic generation is injected, thereby making it a natural implementation. The synchronous condenser augments the operational domain of the system significantly, nearly eliminating the need for renewable energy curtailment. A case‐study approach is used to present results on improvements in damping ratio, feasibility domain and transient stability.
Implementation of storm‐time ionospheric forecasting algorithm using SSA–ANN model
Authors: Kumar Dabbakuti J. R. K. , Peesapati Rangababu , Yarrakula Mallika , Anumandla Kiran Kumar , Madduri Sasi Vardhan
Published: June 2020

Forecasting of total electron content (TEC)/global positioning system (GPS) signal delays in storm conditions is considered the most challenging task for accurate position estimation, especially in critical applications. Therefore, a storm‐time ionospheric model is proposed to forecast TEC based on the artificial neural network (ANN) using singular spectrum analysis (SSA). The study area covers four Global Navigation Satellite System (GNSS) stations located in the low‐latitude and two GNSS stations located in the mid‐latitude ionosphere. The geographical area extends between 11–43°N latitude and 77–93°E longitude. The selection of GPS–TEC data is based on the storm criterion of Dst ≤ −50 nT, and the storm day data sets from 2009 to 2017 period are used for model development. The proposed algorithm is tested with the GPS–TEC data sets of three geomagnetic storm days (i) severe, (ii) moderate storm and (iii) strong at low and mid‐latitudes. The average precision and mean absolute error of the proposed SSA‐ANN model is 1.41 and 1.06 TECU (strong storm), respectively. The prediction performance of the proposed SSA‐ANN model is compared with the standard principal component analysis‐ANN model. The improvement factor of the SSA‐ANN is improved by 43.82%.
Formation and dynamics of transequatorial loops
Authors: Ghosh Avyarthana , Tripathi Durgesh
Published: June 2020

Aims. We aim to study the dynamical evolution of transequatorial loops (TELs) using imaging techniques and spectroscopy.

Methods. We used the images recorded by the Atmospheric Imaging Assembly and the Helioseismic Magnetic Imager on board the Solar Dynamics Observatory together with spectroscopic observations taken from the Extreme-Ultraviolet Imaging Spectrometer on board Hinode.

Results. The data from the AIA 193 Å channel show that TELs are formed between AR 12230 and a newly emerging AR 12234, evolving between 10 and 14 December 2014. The xt-plots for 12 December 2014, obtained using AIA 193 Å data, reveal signatures of inflow and outflow towards an X-region. High-cadence AIA images also show recurrent intensity enhancements in close proximity to the X-region (P2), which is observed to have higher intensities for spectral lines that are formed at log T[K] = 6.20 and voids at other higher temperatures. The electron densities and temperatures in the X-region (and P2) are maintained steadily at log Ne= 8.5–8.7 cm−3 and log T[K] = 6.20, respectively. Doppler velocities in the X-region show predominant redshifts by about 5–8 km s−1 when they are closer to the disk center but blueshifts (along with some zero-velocity pixels) when away from the center. The full-width-half-maximum maps reveal non-thermal velocities of about 27–30 km s−1 for Fe XII, Fe XIII, and Fe XV lines. However, the brightest pixels have nonthermal velocities ∼62 km s−1 for Fe XII and Fe XIII lines. On the contrary, the dark X-region for Fe XV line have the highest non-thermal velocity (∼115 km s−1).

Conclusions. We conclude that the TELs are formed due to magnetic reconnection. We further note that the TELs themselves undergo magnetic reconnection, which leads to the re-formation of loops among individual ARs. Moreover, this study, for the first time, provides measurements of plasma parameters in X-regions, thereby providing essential constraints for theoretical studies.
Linear dust polarization during the embedded phase of protostar formation
Authors: Kuffmeier M. , Reissl S. , Wolf S. , Stephens I. , Calcutt H.
Published: June 2020

Context. Measuring polarization from thermal dust emission can provide important constraints on the magnetic field structure around embedded protostars. However, interpreting the observations is challenging without models that consistently account for both the complexity of the turbulent protostellar birth environment and polarization mechanisms.

Aims. We aim to provide a better understanding of dust polarization maps of embedded protostars with a focus on bridge-like structures such as the structure observed toward the protostellar multiple system IRAS 16293–2422 by comparing synthetic polarization maps of thermal reemission with recent observations.

Methods. We analyzed the magnetic field morphology and properties associated with the formation of a protostellar multiple based on ideal magnetohydrodynamic 3D zoom-in simulations carried out with the RAMSES code. To compare the models with observations, we postprocessed a snapshot of a bridge-like structure that is associated with a forming triple star system with the radiative transfer code POLARIS and produced multiwavelength dust polarization maps.

Results. The typical density in the most prominent bridge of our sample is about 10−16 g cm−3, and the magnetic field strength in the bridge is about 1 to 2 mG. Inside the bridge, the magnetic field structure has an elongated toroidal morphology, and the dust polarization maps trace the complex morphology. In contrast, the magnetic field strength associated with the launching of asymmetric bipolar outflows is significantly more magnetized (~100 mG). At λ = 1.3 mm, and the orientation of the grains in the bridge is very similar for the case accounting for radiative alignment torques (RATs) compared to perfect alignment with magnetic field lines. However, the polarization fraction in the bridge is three times smaller for the RAT scenario than when perfect alignment is assumed. At shorter wavelength (λ ≲ 200 μm), however, dust polarization does not trace the magnetic field because other effects such as self-scattering and dichroic extinction dominate the orientation of the polarization.

Conclusions. Compared to the launching region of protostellar outflows, the magnetic field in bridge-like structures is weak. Synthetic dust polarization maps of ALMA Bands 6 and 7 (1.3 mm and 870 μm, respectively) can be used as a tracer of the complex morphology of elongated toroidal magnetic fields associated with bridges.
Passive Immunity for Coronavirus Disease 2019: A Commentary on Therapeutic Aspects Including Convalescent Plasma
Authors: Lindholm Paul F. , Ramsey Glenn , Kwaan Hau C.
Published: June 2020

In the ongoing pandemic of coronavirus disease 2019 (COVID-19), the novel virus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is infecting a naïve population. The innate immunity of the infected patient is unable to mount an effective defense, resulting in a severe illness with substantial morbidity and mortality. As most treatment modalities including antivirals and anti-inflammatory agents are mostly ineffective, an immunological approach is needed. The mechanism of innate immunity to this viral illness is not fully understood. Passive immunity becomes an important avenue for the management of these patients. In this article, the immune responses of COVID-19 patients are reviewed. As SARS-CoV-2 has many characteristics in common with two other viruses, SARS-CoV that cause severe acute respiratory syndrome (SARS) and MERS-CoV (Middle East respiratory syndrome coronavirus) that causes Middle East respiratory syndrome (MERS), the experiences learned from the use of passive immunity in treatment can be applied to COVID-19. The immune response includes the appearance of immunoglobulin M followed by immunoglobulin G and neutralizing antibodies. Convalescent plasma obtained from patients recovered from the illness with high titers of neutralizing antibodies was successful in treating many COVID-19 patients. The factors that determine responses as compared with those seen in SARS and MERS are also reviewed. As there are no approved vaccines against all three viruses, it remains a challenge in the ongoing development for an effective vaccine for COVID-19.
Function of Large and Small Platelets Differs, Depending on Extracellular Calcium Availability and Type of Inductor
Authors: Handtke Stefan , Wesche Jan , Palankar Raghavendra , Greinacher Andreas , Thiele Thomas
Published: June 2020

It is widely anticipated that large platelets are more reactive than small platelets. This was mainly shown in Ca2+-poor media albeit extracellular Ca2+ is utilized by platelets for activation. We determined the impact of extracellular Ca2+ on functional differences between large and small platelets in response to thrombin receptor activating peptide 6 (TRAP-6), adenosine diphosphate (ADP), and epinephrine. In Ca2+-poor buffer, large platelets responded stronger to TRAP-6 which equalized in Ca2+ containing buffer. Large platelets contained and mobilized more Ca2+ from their intracellular stores upon TRAP-6 stimulation explaining their better reactivity in Ca2+-poor media. Stronger aggregation of large platelets in response to ADP also equalized in presence of Ca2+, whereas large platelets responded weaker to ADP in flow cytometry (CD62P-expression: 9.7 mean fluorescence intensity [MFI] [4.4–17.9] vs. 17.5 MFI [6.1–45.6], p = 0.0234) and PAC-1 binding (11.1 MFI [5.7–19.6] vs. 20.5 MFI [14.4–35.0], p = 0.0078). Epinephrine response was stronger in large platelets (CD62P-expression: 11.8 MFI [6.8–33.0] vs. 6.8 MFI [2.5–15.2], p = 0.0078; PAC-1 binding 18.9 MFI [13.6–38.4] vs. 13.0 MFI [6.8–22.4], p = 0.0234; max. aggregation 82.9% [58.7–94.8] vs. 77.2% [19.8–88.8], p = 0.0313), which expressed more α2A receptors. Epinephrine further increased phosphatidylserine (PS) exposure especially in large platelets. PS-positive platelets progressively divided into two subpopulations with high or basic intracellular Ca2+ dependent on extracellular Ca2+. Thrombin generation was faster with small, but accelerated by PS exposure and epinephrine-coactivated large platelets. We show that responses of large and small platelets differ depending on extracellular Ca2+ availability and the inductor. Careful control of extracellular Ca2+ is necessary in functional studies with large and small platelets.
Changes in Delivery Timing for High-Risk Pregnancies in the United States
Authors: Little Sarah E. , Robinson Julian N. , Zera Chloe A.
Published: June 2020

Objective This study was aimed to assess whether the “39-week” rule is being extended to high-risk pregnancies and if so whether this has led to changes in neonatal morbidity or stillbirth.

Study Design Birth certificate data between 2010 and 2014 from 23 states (55% of births in the United States) were used. Pregnancies were classified as high risk if they had any one of the following: maternal age greater than or equal to 40 years, prepregnancy body mass index (BMI) greater than or equal to 40 kg/m2, chronic (prepregnancy) hypertension, or diabetes (pregestational or gestational). Delivery timing changes for all pregnancies at term (37 weeks or greater) were compared with changes in the high-risk population. Neonatal morbidities (neonatal intensive care unit [NICU] admission, need for assisted ventilation, 5-minute Apgar score, and macrosomia), maternal morbidities (intensive care unit [ICU] admission, cesarean delivery, operative vaginal delivery, chorioamnionitis, and severe perineal laceration), and stillbirth rates were compared across time periods. Multivariate logistic regression was used to analyze whether gestational age–specific morbidity changes were due to shifts in delivery timing.

Results For the overall population, there was a shift in delivery timing between 2010 and 2014, a 2.5% decrease in 38-week deliveries, and a 2.3% increase in 39-week deliveries (p < 0.01). This gestational age shift was identical in the high-risk population (2.7% decrease in 38-week deliveries and 2.9% increase in 39-week deliveries). For the high-risk population, NICU admission increased from 5.4 to 6.3% in 2014 (p < 0.01) and assisted ventilation rates declined from 3.8 to 2.9% (p < 0.01). These changes, however, were independent of changes in delivery timing. There was no increase in the rate of stillbirth (0.23% in 2010 and 0.23% in 2014; p = 0.50).

Conclusion There was a significant shift in delivery timing for high-risk pregnancies in the United States between 2010 and 2014. This shift, however, did not result in statistically significant changes in either neonatal morbidity or stillbirth.

Key Points
Does the Presence of a Hernia Sac Improve Survival in Newborns with Congenital Diaphragmatic Hernia? A United Kingdom Single-Center Experience
Authors: Jawaid Wajid , Sampat Kit , Losty Paul D.
Published: June 2020

Introduction A developing body of literature suggests that the presence of a hernia sac in fetuses with congenital diaphragmatic hernia (CDH) may indicate improved prognosis. By examining a large cohort of CDH newborns admitted to a single United Kingdom specialist center, we aimed to establish if presence of hernia sac is a robust predictor of improved survival.

Materials and Methods All CDH patients admitted to a single center were recruited. Postneonatal presentations and Morgagni hernias were excluded. Demographics, defect type, laterality, survival, and hernia recurrence were recorded.

Results In this study, 192 CDH newborns were managed from 1997 to 2017; 39 were excluded (10 Morgagni and 29 postneonatal); 22 (14%) neonates had a hernia sac. Survival in patients with a hernia sac was 21/22 (95%) versus 107/124 (86%) in cases without hernia sac (p = 0.2). There was no difference in hernia sac proportion by gender (male:female 15 vs. 13.2%, p = 0.8).

Conclusion In contrast to studies showing a survival advantage, albeit with smaller patient numbers, we report a statistical nonsignificant benefit of hernia sac. Better survival outcomes at this specialist center with CDH patients without a hernia sac than reported in other published studies are likely responsible for the lack of statistical significance observed, despite a larger cohort. National and international CDH registries yielding “big data” may provide further answers on the utility of a CDH hernia sac as a new prognostic scoring tool.
Juggling Multiple Roles amidst Uncertainty: The Asian Father's Perspective of an Infant in Neonatal Intensive Care Unit
Authors: Lian Berenice Xueli , Amin Zubair , Aishworiya Ramkumar
Published: June 2020

Objective Parents of preterm, very low birthweight (VLBW) infants in neonatal intensive care units (NICU) undergo emotional turmoil. Studies on parent's experiences typically focus on the maternal perspective. The purpose of the study is to explore the emotional needs and experiences of fathers of VLBW neonates in the NICU and to identify ways to improve their experiences.

Study Design This was a qualitative descriptive design study undertaken at the NICU of a tertiary university hospital. Convenience sampling with predefined inclusion and exclusion criteria was used to identify prospective participants. Semi-structured interviews were conducted with 15 fathers of infants until data saturation was reached. The COREQ (Consolidated Criteria for Reporting Qualitative Studies) checklist was used.

Results Father's experiences were classified into the topics of concerns, roles, and perspectives. Uncertainty was a predominant theme in each of these. Fathers assume multiple roles toward the child, wife, self, and family. Their concerns were multifaceted involving the child, family, work, and finances; they experienced a myriad of emotions, but these evolved into resilience eventually.

Conclusion Fathers have unique concerns pertinent to having an infant in the NICU. They juggle multiple roles and transition to emotions of resilience. It is imperative to acknowledge the uncertainty and diverse roles of fathers, provide them with customized information, and develop more balanced parent-support groups.

Key Points
Magnetic anisotropies in oblique columnar growth of FeCoB films
Authors: Aldimassi A. M. , Chevalier A. , Ben Youssef J. , Laur V. , Rouvellou B.
Published: June 2020

We report on the evolution of anisotropies of FeCoB thin films deposited by magnetron sputtering with different oblique angles increasing from α = 0° to α = 75°. The oblique incidence deposition using the Fe43Co43B14 target leads, under chosen conditions, to columnar growth without bundling. This columnar structure results in a correlated increase in the anisotropy field and of the resonance frequency values, observed with an increasing oblique incidence angle from α = 0° to α = 45°. However, these values decrease from α = 45° to α = 75°. To get a better understanding of the reversal magnetization process, in plane angular distribution of different magnetic parameters was carried out, and the role of easy axis dispersion was especially investigated. The optimized conditions of deposition, leading to controlled high resonance frequencies, could be useful in the design of FeCoB-based microwave devices.
Carbon sources supporting Australia's most widely distributed freshwater fish, Nematalosa erebi (Günther) (Clupeidae: Dorosomatinae)
Authors: Pusey Bradley J. , Jardine Timothy D. , Beesley Leah S. , Kennard Mark J. , Ho Tsz Wai , Bunn Stuart E. , Douglas Michael M.
Published: June 2020

Both brown (detrital-based) and green (algal-based) food pathways support freshwater food webs, although the importance of either source may vary within species, regions and different phases of the flow regime. The bony bream (Nematalosa erebi Clupeidae: Dorosomatinae) is one of Australia’s most widely distributed freshwater fish species and is a key component of freshwater food webs, especially in northern Australia. We sought to better define the feeding habits of this species, previously classified as a detritivore, algivore or zooplanktivore (or combinations thereof), by undertaking meta-analyses of published accounts based on stomach content analysis and 13C and 15N stable isotope analysis. Stomach content analysis clearly indicated that detritus was the dominant food item, although benthic algae could be an important dietary component in some habitats (inland river flood plains) and during the wet season. Zooplankton were important for small fish (i.e. juveniles <100mm in length). When data were pooled across a large number of locations, stable isotope analysis indicated that detritus derived from terrestrial vegetation was better aligned isotopically with values for both adult and juvenile bony bream, whereas algae were comparatively 13C enriched, indicating the latter source was not the dominant contributor to the biomass of this species. However, using site-specific data and a regression approach, a significant relationship was revealed between algal carbon and that of large fish, suggesting that carbon derived from benthic algae contributed ~20% of the carbon of adult bony bream. Zooplankton contributed a similar amount. Zooplankton provided the majority of carbon for small fish. We contend that detritus derived from terrestrial vegetation is the likely remaining carbon source for large bony bream, and this interpretation was supported by the outcomes of multiple regression analyses. Although previous studies of aquatic food webs in northern Australia have emphasised the importance of high-quality algal basal resources, this study indicates that terrestrial sources may be important for some species and demonstrates the need to better consider the circumstances that cause biota to switch between different food sources.
Functional interplay of Epstein-Barr virus oncoproteins in a mouse model of B cell lymphomagenesis
Authors: Sommermann Thomas , Yasuda Tomoharu , Ronen Jonathan , Wirtz Tristan , Weber Timm , Sack Ulrike , Caeser Rebecca , Zhang Jingwei , Li Xun , Chu Van Trung , Jauch Anna , Unger Kristian , Hodson Daniel J. , Akalin Altuna , Rajewsky Klaus
Published: June 2020

Epstein-Barr virus (EBV) is a B cell transforming virus that causes B cell malignancies under conditions of immune suppression. EBV orchestrates B cell transformation through its latent membrane proteins (LMPs) and Epstein-Barr nuclear antigens (EBNAs). We here identify secondary mutations in mouse B cell lymphomas induced by LMP1, to predict and identify key functions of other EBV genes during transformation. We find aberrant activation of early B cell factor 1 (EBF1) to promote transformation of LMP1-expressing B cells by inhibiting their differentiation to plasma cells. EBV EBNA3A phenocopies EBF1 activities in LMP1-expressing B cells, promoting transformation while inhibiting differentiation. In cells expressing LMP1 together with LMP2A, EBNA3A only promotes lymphomagenesis when the EBNA2 target Myc is also overexpressed. Collectively, our data support a model where proproliferative activities of LMP1, LMP2A, and EBNA2 in combination with EBNA3A-mediated inhibition of terminal plasma cell differentiation critically control EBV-mediated B cell lymphomagenesis.
Engineering a potent receptor superagonist or antagonist from a novel IL-6 family cytokine ligand
Authors: Kim Jun W. , Marquez Cesar P. , Sperberg R. Andres Parra , Wu Jiaxiang , Bae Won G. , Huang Po-Ssu , Sweet-Cordero E. Alejandro , Cochran Jennifer R.
Published: June 2020

Significance

The interleukin-6 family of cytokines play an increasingly recognized role in inflammation, metabolism, and tissue regeneration. Cytokine binding to CNTFR triggers JAK-STAT, MAPK, and other associated pathways. From limited studies reported to date, CLCF1 has been implicated in lung cancer, osteoporosis, and atherosclerosis, identifying the CLCF1–CNTFR signaling axis as a therapeutic target for a number of diseases. To modulate multireceptor engagement to drive cell signaling, we used rational and combinatorial protein engineering methods to create two unique CLCF1 variants: one that promotes enhanced cell signaling in neuronal regeneration and one that blocks cell signaling to inhibit tumor progression. These studies highlight an approach of engineering cytokine activity to target the CLCF1–CNTFR signaling axis.
Exaggerated meta-perceptions predict intergroup hostility between American political partisans
Authors: Moore-Berg Samantha L. , Ankori-Karlinsky Lee-Or , Hameiri Boaz , Bruneau Emile
Published: June 2020

People’s actions toward a competitive outgroup can be motivated not only by their perceptions of the outgroup, but also by how they think the outgroup perceives the ingroup (i.e., meta-perceptions). Here, we examine the prevalence, accuracy, and consequences of meta-perceptions among American political partisans. Using a representative sample (
n
= 1,056) and a longitudinal convenience sample (
n
= 2,707), we find that Democrats and Republicans equally dislike and dehumanize each other but think that the levels of prejudice and dehumanization held by the outgroup party are approximately twice as strong as actually reported by a representative sample of Democrats and Republicans. Overestimations of negative meta-perceptions were consistent across samples over time and between demographic subgroups but were modulated by political ideology: More strongly liberal Democrats and more strongly conservative Republicans were particularly prone to exaggerate meta-perceptions. Finally, we show that meta-prejudice and meta-dehumanization are independently associated with the desire for social distance from members of the outgroup party and support for policies that harm the country and flout democratic norms to favor the ingroup political party. This research demonstrates that partisan meta-perceptions are subject to a strong negativity bias with Democrats and Republicans agreeing that the shadow of partisanship is much larger than it actually is, which fosters mutual intergroup hostility.
Complaint management on Twitter – evolution of interactional patterns on Polish corporate profiles
Authors: Tereszkiewicz Anna
Published: June 2020

The study concerns complaint management on Polish brand profiles on Twitter. The aim was to investigate selected language properties of corporate tweets and trace potential changes in the interactional patterns on the profiles occurring between 2015 and 2017. The study focuses on the structure and frequency of the respective strategies, as well as formality, the use of non-standard structures and emoticons. The study indicates the following directions of change: an increase in the use of address terms and explanations, a greater degree of language formality and indirectness, among others. The changes point to increased formulaicity and conventionalisation of expression, as well as an increased use of fixed patterns and templates. The changes constitute evidence of standardisation of the means of expression in customer encounters and a transfer of the conventions typical of other channels of interaction with consumers to the online context.
Emissaries of Enlightenment: Azeri Theater Troupes in Iran and Central Asia, 1906–44
Authors: Rice Kelsey
Published: June 2020

At the turn of the century, Azeri intellectuals embraced their unique position at the intersection of the Russian, Ottoman, and Iranian Empires by taking on the self-appointed role trans-imperial reformers. Moving with relative ease from Baku to Istanbul, Tabriz, Tehran, Bukhara, and beyond, Azeri reformist intellectuals were neither insular nor modest in their aspirations as they promoted social and cultural reform. This article explores Azeri efforts to promote their vision of progress to fellow Muslims in Iran and Central Asia through the most radical genre of cultural expression embraced by Azeri intellectuals: the theater. Using indigenous language sources to focus on these activities, this article demonstrates the far-reaching influence of Azeri cultural productions and the expansive ambitions of Azeri reformist intellectuals.
Legal norms or ad hoc fixes? International legal aspects of Russian military involvement in conflict settlements in the Caucasus
Authors: Nikitin Alexander
Published: June 2020

This article provides a comparative analysis of the legal grounds for the deployment of the Russian Armed Forces in a series of conflicts in the Caucasus, namely in the disengagement between North Ossetia and Ingushetia (1992–1994), South Ossetia/Georgia (1992–2008), Abkhazia/Georgia (1994–2008), and in the Russian– Georgian War of 2008. The difficulties in codifying certain actions from the point of view of international law are detailed. The article discusses whether the political and military actions of Moscow in various Caucasian conflicts were driven and interconnected by one and the same logic, or were purely ad hoc fixes. Cases where Russia’s actions have been legitimized by securing mandate from a regional intergovernmental organization are differentiated from cases where it has acted on the basis of intergovernmental agreements, as well as from the application in certain cases of Article 51 (“the right of individual or collective self-defence”) of the UN Charter. The legitimacy or illegitimacy of the deployment of the Russian Armed Forces abroad is considered in the context of, and in comparison with, a series of cases where force has been used in conflicts by coalitions under a UN mandate, as well as by NATO and some Western powers.
Rab18 regulates focal adhesion dynamics by interacting with kinectin-1 at the endoplasmic reticulum
Authors: Guadagno Noemi Antonella , Margiotta Azzurra , Bjørnestad Synne Arstad , Haugen Linda Hofstad , Kjos Ingrid , Xu Xiaochun , Hu Xian , Bakke Oddmund , Margadant Felix , Progida Cinzia
Published: June 2020

The members of the Rab family of small GTPases are molecular switches that regulate distinct steps in different membrane traffic pathways. In addition to this canonical function, Rabs can play a role in other processes, such as cell adhesion and motility. Here, we reveal the role of the small GTPase Rab18 as a positive regulator of directional migration in chemotaxis, and the underlying mechanism. We show that knockdown of Rab18 reduces the size of focal adhesions (FAs) and influences their dynamics. Furthermore, we found that Rab18, by directly interacting with the endoplasmic reticulum (ER)-resident protein kinectin-1, controls the anterograde kinesin-1–dependent transport of the ER required for the maturation of nascent FAs and protrusion orientation toward a chemoattractant. Altogether, our data support a model in which Rab18 regulates kinectin-1 transport toward the cell surface to form ER–FA contacts, thus promoting FA growth and cell migration during chemotaxis.
Double field inflation of generalized dilaton–axion models with a new Fayet–Iliopoulos (FI) term
Authors: Kwan Ellgan MAN Ping
Published: June 2020

We study the inflation dynamics of generalized dilaton–axion models with a new Fayet–Iliopoulos (FI) term, where both real and imaginary parts of the ‘dilaton–axion’ super-field evolve. We find that the turn rate per Hubble parameter is about

O

10

−
2

to

O

10

−
1

while the square of effective mass of entropic perturbation is about

O

10

−
1

. These results can be used for identifying the specific inflation pattern in the future observation.
Accuracy of volumetric flow rate inflow/outflow measurement by integrating PIV velocity fields
Authors: Cressall Rick , Schaap Robbie , Neal Douglas R , Mychkovsky Alex , Charonko John , Smith Barton L
Published: June 2020

In this paper, the usefulness of planar Particle Image Velocimetry (PIV) measurements to determine the volumetric flow rate from a rectangular or round jet exit is assessed. Both two-component PIV (2C–PIV) and through-plane three-component (3C) stereo PIV (SPIV) data sets were acquired at the exit of a turbulent, rectangular nozzle and a round nozzle with Reynolds numbers between 10 000 and 100 000. The PIV data sets were processed using a variety of algorithms. The time-averaged results were then spatially integrated across the jet exits and compared to a calibrated flow meter. Recommendations for each method are developed and discussed with potential drawbacks. The accuracy of the measurement was found to be a weak function of the Reynolds number of the flow. Two-component PIV was found to underestimate the volumetric flow rate by 1%–4% depending on the integration scheme and SPIV underestimated volumetric flow rate by 2%.
Characterization of vortex regeneration mechanism in the self-sustaining process of wall-bounded flows using resolvent analysis
Authors: Jane Bae H. , McKeon Beverley J.
Published: June 2020

The regeneration mechanism of streamwise vortical structures in the self-sustaining process of wall-bounded turbulence is investigated. Resolvent analysis [1] is used to identify the principal forcing mode which produces the maximum amplification of the response modes in the minimal channel for the buffer [2] and logarithmic layer [3]. The identified mode is then projected out from the nonlinear term of the Navier-Stokes equations at each time step from the direct numerical simulations (DNS) of the corresponding minimal channel. The results show that the removal of the principal forcing mode is able to significantly inhibit turbulence for the buffer and logarithmic layer while removing the subsequent modes instead of the principal one only marginally affects the flow. Analysis of the dyadic interactions in the nonlinear term shows that the contributions toward the principal forcing mode come from a limited number of wavenumber interactions. Using conditional averaging, the flow structures that are responsible for generating the principal forcing mode, and thus the nonlinear interaction to self-sustain turbulence, are identified to be spanwise rolls interacting with meandering streaks.
Effect of bubble size on Lagrangian pressure statistics in homogeneous isotropic turbulence
Authors: Bappy M H , Vela-Martin A , Buscaglia G C , Carrica P M , Freire L S
Published: June 2020

The study of bubble’s behavior in turbulent flows is fundamental to the understanding of many engineering applications that are concerned with bubbly/two-phase flow. In turbomachinery, for example, tiny gas nuclei present in the liquid may grow to macroscopic size if the instantaneous pressure dips below the vapor pressure for a time long enough to incite cavitation events. In this paper, the Lagrangian pressure statistics of finite sized bubbles in homogeneous isotropic turbulence is investigated using highly-resolved direct numerical simulations of the Navier-Stokes equations at Reλ
= 150. A modified Maxey-Riley equation is used for Lagrangian tracking of bubbles in the turbulence field. The Lagrangian pressure statistics (probability density function, frequency of low-pressure events and their duration) are analyzed as functions of the bubble size. The overall picture that emerges is consistent with finite-sized bubbles being driven towards vortex cores, resulting in an average pressure further below the mean value and longer and more frequent low-pressure events as the considered size is increased.
Reynolds shear-stress carrying structures in shear-dominated flows
Authors: Gungor Taygun R , Maciel Yvan , Gungor Ayse G
Published: June 2020

Four direct numerical simulation (DNS) databases are examined to understand the effect of the wall and near-wall turbulence on the Reynolds shear-stress carrying structures in shear-driven flows. The first DNS database is of a non-equilibrium adverse-pressure-gradient (APG) turbulent boundary layer (TBL) with momentum thickness Reynolds number (Reg) reaching 8000. The second one is the same flow as the previous, but turbulence activity in the inner layer (y/S < 0.1) is artificially eliminated. The last two DNS databases are homogeneous shear turbulence (HST) with Taylor microscale Reynolds numbers (Re\) are 104 and 248. Results show that outer layer turbulence in the APG TBLs with large velocity defect is only slightly affected by the near-wall region turbulence which suggests outer layer turbulence sustains itself without necessitating near-wall turbulence. The Corrsin length scale (Lc) scales the size of the Reynolds shear-stress carrying structures in both APG TBLs and HSTs. The streamwise length of these structures is 1LC or larger in all cases. The aspect ratio of the structures behaves similarly in both APG TBLs and HSTs when the size of the structures are normalized with Lc. Sweeps and ejections tend to form side-by-side pairs in both flow types. The spatial properties of sweeps and ejections, such as aspect ratios or relative positions are not affected by near-wall turbulence activity or presence of the wall. This suggests that the structures mostly dependent on the local mean strain rates.
Global modes and large-scale structures in an Ekman boundary layer
Authors: Ortiz-Tarin J L , Lee S , Flores O , Sarkar S
Published: June 2020

Motivated by the dynamics of the atmospheric boundary layer, the present work examines the influence of Coriolis acceleration on wall-bounded turbulence. The large-scale structures of an Ekman boundary layer are compared to those of a channel. The distribution of energy across scales is studied by looking into the spectra of the velocity fluctuations. Linear stability analysis reveals the existence of an unstable range of wavenumbers which sustain the turbulence and lead to transverse “roll” structures observed in instantaneous snapshots of the flow.
Analysis of the spanwise extent and time persistence of uniform momentum zones in zero pressure gradient and adverse pressure gradient turbulent boundary layers
Authors: Senthil Shevarjun , Atkinson Callum , Soria Julio
Published: June 2020

Time-resolved velocity fields from direct numerical simulations (DNS) are used to investigate the spanwise extent and the time persistence of uniform momentum zones (UMZs) in a zero pressure gradient turbulent boundary layer (ZPG-TBL) and a self-similar adverse pressure gradient turbulent boundary layer (APG-TBL) at the verge of separation. The instantaneous detection methodology introduced by Adrian et al. [1] is used to detect the UMZs and is extended to take into account the spanwise domain length and the temporal evolution of the UMZs. The Reynolds number based on friction velocity (Reτ) ranges from 1176 to 1277 for the ZPG-TBL and from 1652 to 1745 for the self-similar APG-TBL within the domain of interest. For both the TBL cases, probability density functions (PDFs) of the number of UMZs are computed as a function of the streamwise extent, spanwise extent and time extent. For the ZPG-TBL, when the streamwise length of the domain is greater than or equal to 3 boundary layer thickness, the probability of finding 4 UMZs becomes almost negligible. For the APG-TBL, even when the streamwise domain length is taken as large as 1.3 boundary layer thickness, the probability of finding 4 UMZs is still significant. The spanwise extent of the UMZs is found to be shorter than their streamwise extent regardless of the pressure gradient in the flow. In the ZPG-TBL flow, the majority of the UMZs have a spanwise extent of the order of one-tenth of a boundary layer thickness while for the APG-TBL, it is found to be on the order of one-hundredth of a boundary layer thickness. In the ZPG-TBL, the probability of finding 2 UMZs that persist over a time period of 2 integral time scale is around 50%. Similarly, for the APG-TBL, the probability of finding 2 UMZs with a time persistence of 0.4 integral time scale is over 50%. In the case of the ZPG-TBL, it is observed that some of the UMZs with higher persistence in time have higher streamwise momentum and are found to be closer to the free-stream in general. This result is consistent with the previous observations by Laskari et al. [2]. In contrast, for the APG-TBL, UMZs with longer time persistence are found closer to the wall with lower streamwise momentum.
Wall-bounded turbulence control: statistical characterisation of actions/states
Authors: Pastor R , Vela-Martín A , Flores O
Published: June 2020

The present paper reports the results of a Monte Carlo experiment using a turbulent channel flow. Different actions are proposed, varying the size, duration and sign of a localised volumetric force that acts near one wall of a turbulent channel flow, running at a small Reynolds (ReT
= 165) in a small computational domain. The effect of each action is evaluated comparing the evolution of the flow with and without the action, gathering statistics over 1700 repetitions of the experiment for each action. The analysis of the results show that small/short forcings are equally likely to increase or decrease the skin friction drag, independently of the sign of the forcing (i.e., towards or away from the wall). When the size or the duration of the forcing increases, so does the probability of increasing the skin friction. Then, an a priori analysis is performed, evaluating the state of the flow just before the action, conditioned to actions that result in a decrease of the skin friction over a period of one eddy turn-over time. The resulting fields of velocity, wall shear stresses and wall pressure are consistent with an opposition control strategy, where the forcing is opposing the vertical motions near the wall. Finally, a preliminary analysis of the performance of actuation triggered by pressure or wall shear stresses sensors is evaluated (i.e., a posteriori analysis). Our results show that the actuation triggered by a wall shear sensor seems to be more effective than the actuation triggered by a wall pressure sensor, at least for the preliminary definitions of sensors and thresholds used here.
Flow structures and shear-stress predictions in the turbulent channel flow over an anisotropic porous wall
Authors: Le Clainche Soledad , Rosti Marco , Brandt Luca
Published: June 2020

This article identifies the main coherent structures driving the flow dynamics in the turbulent channel flow over anisotropic porous walls. Two different cases have been analyzed where the drag increases or decreases with respect to a channel with isotropic porous walls. Higher order dynamic mode decomposition (HODMD) is applied to analyze these data, identifying 20 and 15 high amplitude modes in the drag increasing (DI) and drag reducing (DR) cases, respectively, which well reflects the largest flow complexity in the former case. The frequency of 13 modes and the three-dimensional structure of the modes are similar in the DR and DI cases, suggesting the need of using more complex analyses to deepen our physical insight of these flows. The spatio-temporal HODMD analysis identifies a periodic solution along the spanwise direction (as imposed by the boundary conditions). The wavenumbers related to the modes with highest amplitude are β = 0 and β = 3 (Lz = 2
3
π ). The rollers, groups of spanwise correlated structures, are mostly identified in the DI case near the wall, with β = 0, while the presence of the streaks, streamwise correlated structures are mostly identified in the DR case. Although, in areas far away from the wall it is possible to identify these two types of structures with β = 3 in both cases, depending on the temporal frequency of the DMD modes, the rollers and the streaks are related to high and low frequency DMD modes, respectively. Finally, a model is constructed to predict the temporal evolution of the wall shear, using the 6 most relevant DMD modes interacting near the channel wall: 6 low frequency modes for DR and 3 low and 3 high frequency modes for DI. In the DR case the wall shear is predicted for almost 300 time units with relative error ∼ 2%, however, this error is larger in the DI case, ∼ 6%, suggesting the need of using a larger number of modes to represent this more complex flow.
Effect of limited near-wall inlet data on the direct numerical simulation of turbulent channel flow
Authors: Ezhilsabareesh K. , Atkinson Callum , Lozano-Duran Adrian , Schimd Peter J. , Jimenez Javier , Soria Julio
Published: June 2020

Direct numerical simulation (DNS) of turbulent flows require a large computational domain and a long simulation time to capture and evolve the large-scale structures and attain a statistically stationary state. In contrast, experimental measurements can relatively easily capture the large-scale structures, but struggle to resolve the dissipative flow scales. This study investigates the spatial extent required for the DNS of a turbulent channel flow to recover turbulent fluctuations and energy when using experimental inlet data which is typically unable to capture fluctuations down to the viscous sub-layer. Synthetic experimental fields from streamwise periodic channel flow DNS at Reτ = 180 are used as an inlet for a channel flow DNS with inlet-outlet boundary conditions. The effect of limited near-wall data at the inlet is examined by removing the near-wall energy and fluctuations in all but the zeroth Fourier mode. The influence of limited near-wall data on the convergence of mean and streamwise fluctuating velocity profiles is less significant when the fluctuations are removed at the inlet up to y+ = 5. However, the spanwise fluctuations are slightly weakened. The spanwise energy spectra suggest that at 1/16 of the domain length (x/h ≍ π/4) the flow scales are recovered. When the fluctuations are removed up to y+ = 17 or greater, recovery of full range of flow scales requires a domain larger than x/h = 4π.