bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionospheric HF Heating Experiment With Frequency Ramping‐up Sweep: Approach for Artificial Ionization Layer Generation
Authors: Watkins Brenton , Kuo Spencer , Secan James , Fallen Christopher
Published: February 2020

An ionospheric high‐frequency (HF) heating experiment was conducted at the HAARP facility in Alaska by sweeping the heater frequency, near the third electron gyroharmonic, over a 145 kHz range with 4 min duration. A 446 MHz diagnostic radar was used to detect scattering from HF‐enhanced plasma waves corresponding to the HF‐enhanced ion lines (HFILs). Increasing frequency progressively moves the third gyroharmonic resonance layer downward, and this is evident in observations of both downgoing and upgoing HFILs dropping in height about 50 km. Artificial ionization was formed by the HF‐plasma interaction during this process and driven downward to about 150–155 km. Total electron content measurements oblique across the High Frequency Active Auroral Research Program transmit beam, above the altitude of primary ionization production, show variations that correspond to ionization production at lower heights. A theoretical interpretation of the experimental observations is presented to understand the HF‐plasma interaction process. It is shown that the double resonance condition enhances the excitation of the upper‐hybrid parametric decay instability (PDI). HF heater frequency ramping‐up sweep increases the spatial height span of the upper‐hybrid PDI generation region and the spectral width of generated upper‐hybrid waves, as well as provides a positive tuning frequency on the excited upper‐hybrid waves that keeps the continuous positive feedback on the Doppler‐shifted cyclotron harmonic resonance interaction. Resonant electrons gain energy from the upper‐hybrid waves and are generated in an extended spatial region; after a drift space, spatially distributed energetic electrons bunch together to build up a density structure.
Selective Acceleration of O+ by Drift‐Bounce Resonance in the Earth's Magnetosphere: MMS Observations
Authors: Oimatsu S. , Nosé M. , Le G. , Fuselier S. A. , Ergun R. E. , Lindqvist P.‐A. , Sormakov D.
Published: February 2020

We studied O+ drift‐bounce resonance using Magnetospheric Multiscale (MMS) data. A case study of an event on 17 February 2016 shows that O+ flux oscillations at ~10–30 keV occurred at MLT ~ 5 hr and L ~ 8–9 during a storm recovery phase. These flux oscillations were accompanied by a toroidal Pc5 wave and a high‐speed solar wind (~550 km/s). The azimuthal wave number (m‐number) of this Pc5 wave was found to be approximately −2. The O+/H+ flux ratio was enhanced at ~10–30 keV corresponding to the O+ flux oscillations without any clear variations of H+ fluxes, indicating the selective acceleration of O+ ions by the drift‐bounce resonance. A search for similar events in the time period from September 2015 to March 2017 yielded 12 events. These events were mainly observed in the dawn to the afternoon region at L ~ 7–12 when the solar wind speed is high, and all of them were simultaneously identified on the ground, indicating low m‐number. Correlation analysis revealed that the O+/H+ energy density ratio has the highest correlation coefficient with peak power of the electric field in the azimuthal component (Ea). This statistical result supports the selective acceleration of O+ due to the N = 2 drift‐bounce resonance.
Effects of Fluid Rheology and Pore Connectivity on Rock Permeability Based on a Network Model
Authors: Xiong Fansheng , Sun Weitao , Ba Jing , Carcione José M.
Published: February 2020

Permeability is an important rock property in exploration geophysics. Darcy's law assumes a steady‐state regime and constant permeability. However, recent studies showed that the effects of fluid viscosity and pore geometry on permeability cannot be neglected. The periodic variation of pore fluid pressure gradient due to elastic wave propagation induces the oscillated fluid flow. We consider a Maxwell fluid in a 3‐D pore network subject to harmonic oscillations. The network is based on the Voronoi method, which provides a realistic connectivity. The permeability of polyethylene oxide and cetylpyridinium chloride and sodium salicylate solution have been simulated. The results show that permeability is constant at frequencies less than several kHz and rapidly decreases to extremely low values as frequency tends to infinite. In addition, we find that fluid mainly flows in sparse‐large pore networks at low frequencies and in dense‐small pore networks at high frequencies. The Maxwell fluid shows significant permeability peaks related to the mean coordination number, indicating that there exists an optimal network connectivity at which fluid flow is maximum. These results have been central to understand how fluid flows in natural reservoir rocks. The permeability variations versus frequency, fluid rheology, and pore connectivity provide key information of reservoir fluid properties and pore network structure. The results indicate that it is questionable whether Darcy static permeability can be applied at high frequencies.
Long noncoding RNA NEAT1 is involved in the protective effect of Klotho on renal tubular epithelial cells in diabetic kidney disease through the ERK1/2 signaling pathway
Authors: Yang Yan-Lin , Xue Meng , Jia Yi-Jie , Hu Fang , Zheng Zong-Ji , Wang Ling , Si Ze-Kun , Xue Yao-Ming
Published: February 2020

Klotho, an antiaging protein, has been shown to play a protective role in renal tubular epithelial-mesenchymal transition (EMT) during the development of diabetic kidney disease (DKD). Long noncoding RNAs (lncRNAs) participate in the progression of EMT in many diseases. However, the effect of Klotho on lncRNAs during the development of DKD is still unknown. In this study, we found that Klotho overexpression in high-fat diet (HFD)- and streptozotocin (STZ)-induced DKD mice significantly inhibited the expression of lncRNA nuclear-enriched abundant transcript 1 (Neat1). We demonstrated that NEAT1 was significantly upregulated in both bovine serum albumin (BSA)-stimulated HK2 cells and mice with HFD- and STZ-induced diabetes. In addition, we observed that Klotho displays colocalization with NEAT1. Furthermore, overexpression of Klotho can inhibit the high expression of NEAT1 in BSA-stimulated HK2 cells, while silencing Klotho can further upregulate the expression of NEAT1. Silencing NEAT1 in HK2 cells resulted in inhibition of the EMT-related markers alpha smooth muscle actin (α-SMA) and vimentin (VIM) and the renal fibrosis-related markers transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF). The effect of NEAT1 on DKD was partly mediated by regulation of the ERK1/2 signaling pathway. Finally, we found that silencing NEAT1 can reverse the activation of EMT and fibrosis caused by Klotho silencing in a manner dependent on the ERK1/2 signaling pathway. These findings reveal a new regulatory pathway by which Klotho regulates ERK1/2 signaling via NEAT1 to protect against EMT and renal fibrosis, suggesting that NEAT1 is a potential therapeutic target for DKD.
Hyperfunctioning of the right posterior superior temporal sulcus in response to neutral facial expressions presents an endophenotype of schizophrenia
Authors: Yan Zhimin , Schmidt Stephanie N. L. , Frank Josef , Witt Stephanie H. , Hass Joachim , Kirsch Peter , Mier Daniela
Published: February 2020

Deficits in social cognition have been proposed as a marker of schizophrenia. Growing evidence suggests especially hyperfunctioning of the right posterior superior temporal sulcus (pSTS) in response to neutral social stimuli reflecting the neural correlates of social-cognitive impairments in schizophrenia. We characterized healthy participants according to schizotypy (n = 74) and the single-nucleotide polymorphism rs1344706 in ZNF804A (n = 73), as they represent risk variants for schizophrenia from the perspectives of personality traits and genetics, respectively. A social-cognitive fMRI task was applied to investigate the association of right pSTS hyperfunctioning in response to neutral face stimuli with schizotypy and rs1344706. Higher right pSTS activation in response to neutral facial expressions was found in individuals with increased positive (trend) and disorganization symptoms, as well as in carriers of the risk allele of rs1344706. In addition, a positive association between right–left pSTS connectivity and disorganization symptoms during neutral face processing was revealed. Although these findings warrant replication, we suggest that right pSTS hyperfunctioning in response to neutral facial expressions presents an endophenotype of schizophrenia. We assume that right pSTS hyperfunctioning is a vulnerability to perceive neutral social stimuli as emotionally or intentionally salient, probably contributing to the emergence of symptoms of schizophrenia.
Recommendations and guidelines for dentists using the basic erosive wear examination index (BEWE)
Authors: Aránguiz Vicente , Lara Juan Sebastián , Marró M. Loreto , O’Toole Saoirse , Ramírez Valeria , Bartlett David
Published: February 2020

This paper explains how to screen tooth wear in general practice using the Basic Erosive Wear Examination (BEWE) index. It explains how stakeholders in the UK acknowledged the convenience of the BEWE and that it could be recorded at the same time as the Basic Periodontal Examination (BPE). The article contains examples of anterior and posterior tooth wear for each BEWE score to help dentists in their evaluation.
Systematic selection between age and household structure for models aimed at emerging epidemic predictions
Authors: Pellis Lorenzo , Cauchemez Simon , Ferguson Neil M. , Fraser Christophe
Published: February 2020

Numerous epidemic models have been developed to capture aspects of human contact patterns, making model selection challenging when they fit (often-scarce) early epidemic data equally well but differ in predictions. Here we consider the invasion of a novel directly transmissible infection and perform an extensive, systematic and transparent comparison of models with explicit age and/or household structure, to determine the accuracy loss in predictions in the absence of interventions when ignoring either or both social components. We conclude that, with heterogeneous and assortative contact patterns relevant to respiratory infections, the model’s age stratification is crucial for accurate predictions. Conversely, the household structure is only needed if transmission is highly concentrated in households, as suggested by an empirical but robust rule of thumb based on household secondary attack rate. This work serves as a template to guide the simplicity/accuracy trade-off in designing models aimed at initial, rapid assessment of potential epidemic severity.
Schizophrenia-related microdeletion causes defective ciliary motility and brain ventricle enlargement via microRNA-dependent mechanisms in mice
Authors: Eom Tae-Yeon , Han Seung Baek , Kim Jieun , Blundon Jay A. , Wang Yong-Dong , Yu Jing , Anderson Kara , Kaminski Damian B. , Sakurada Sadie Miki , Pruett-Miller Shondra M. , Horner Linda , Wagner Ben , Robinson Camenzind G. , Eicholtz Matthew , Rose Derek C. , Zakharenko Stanislav S.
Published: February 2020

Progressive ventricular enlargement, a key feature of several neurologic and psychiatric diseases, is mediated by unknown mechanisms. Here, using murine models of 22q11-deletion syndrome (22q11DS), which is associated with schizophrenia in humans, we found progressive enlargement of lateral and third ventricles and deceleration of ciliary beating on ependymal cells lining the ventricular walls. The cilia-beating deficit observed in brain slices and in vivo is caused by elevated levels of dopamine receptors (Drd1), which are expressed in motile cilia. Haploinsufficiency of the microRNA-processing gene Dgcr8 results in Drd1 elevation, which is brought about by a reduction in Drd1-targeting microRNAs miR-382-3p and miR-674-3p. Replenishing either microRNA in 22q11DS mice normalizes ciliary beating and ventricular size. Knocking down the microRNAs or deleting their seed sites on Drd1 mimicked the cilia-beating and ventricular deficits. These results suggest that the Dgcr8–miR-382-3p/miR-674-3p–Drd1 mechanism contributes to deceleration of ciliary motility and age-dependent ventricular enlargement in 22q11DS.
Capsid protein structure in Zika virus reveals the flavivirus assembly process
Authors: Tan Ter Yong , Fibriansah Guntur , Kostyuchenko Victor A. , Ng Thiam-Seng , Lim Xin-Xiang , Zhang Shuijun , Lim Xin-Ni , Wang Jiaqi , Shi Jian , Morais Marc C. , Corti Davide , Lok Shee-Mei
Published: February 2020

Structures of flavivirus (dengue virus and Zika virus) particles are known to near-atomic resolution and show detailed structure and arrangement of their surface proteins (E and prM in immature virus or M in mature virus). By contrast, the arrangement of the capsid proteins:RNA complex, which forms the core of the particle, is poorly understood, likely due to inherent dynamics. Here, we stabilize immature Zika virus via an antibody that binds across the E and prM proteins, resulting in a subnanometer resolution structure of capsid proteins within the virus particle. Fitting of the capsid protein into densities shows the presence of a helix previously thought to be removed via proteolysis. This structure illuminates capsid protein quaternary organization, including its orientation relative to the lipid membrane and the genomic RNA, and its interactions with the transmembrane regions of the surface proteins. Results show the capsid protein plays a central role in the flavivirus assembly process.
Realization of all-optical vortex switching in exciton-polariton condensates
Authors: Ma Xuekai , Berger Bernd , Aßmann Marc , Driben Rodislav , Meier Torsten , Schneider Christian , Höfling Sven , Schumacher Stefan
Published: February 2020

Vortices are topological objects representing the circular motion of a fluid. With their additional degree of freedom, the vorticity, they have been widely investigated in many physical systems and different materials for fundamental interest and for applications in data storage and information processing. Vortices have also been observed in non-equilibrium exciton-polariton condensates in planar semiconductor microcavities. There they appear spontaneously or can be created and pinned in space using ring-shaped optical excitation profiles. However, using the vortex state for information processing not only requires creation of a vortex but also efficient control over the vortex after its creation. Here we demonstrate a simple approach to control and switch a localized polariton vortex between opposite states. In our scheme, both the optical control of vorticity and its detection through the orbital angular momentum of the emitted light are implemented in a robust and practical manner.
Structural basis of mammalian high-mannose N-glycan processing by human gut Bacteroides
Authors: Trastoy Beatriz , Du Jonathan J. , Klontz Erik H. , Li Chao , Cifuente Javier O. , Wang Lai-Xi , Sundberg Eric J. , Guerin Marcelo E.
Published: February 2020

The human gut microbiota plays a central role not only in regulating the metabolism of nutrients but also promoting immune homeostasis, immune responses and protection against pathogen colonization. The genome of the Gram-negative symbiont Bacteroides thetaiotaomicron, a dominant member of the human intestinal microbiota, encodes polysaccharide utilization loci PULs, the apparatus required to orchestrate the degradation of a specific glycan. EndoBT-3987 is a key endo-β-N-acetylglucosaminidase (ENGase) that initiates the degradation/processing of mammalian high-mannose-type (HM-type) N-glycans in the intestine. Here, we provide structural snapshots of EndoBT-3987, including the unliganded form, the EndoBT-3987-Man9GlcNAc2Asn substrate complex, and two EndoBT-3987-Man9GlcNAc and EndoBT-3987-Man5GlcNAc product complexes. In combination with alanine scanning mutagenesis and activity measurements we unveil the molecular mechanism of HM-type recognition and specificity for EndoBT-3987 and an important group of the GH18 ENGases, including EndoH, an enzyme extensively used in biotechnology, and for which the mechanism of substrate recognition was largely unknown.
Identifying Leadership Characteristics from Social Media Data during Natural Hazards using Personality Traits
Authors: Agarwal Amit , Toshniwal Durga
Published: February 2020

With the availability of smart devices and affordable data plans, social media platforms have become the primary source of information dissemination across geographically dispersed users/locations. It has shown great potential across different application domains including event detection, opinion analysis, recommendation, and prediction. However, the process of extracting useful information from the collected voluminous social media data during natural hazards is a standing problem that needs significant attention from the research community. The fine-grained knowledge detailing users’ participation in information spreading could be advantageous in developing a reliable social network for the adverse events (Natural Hazards, Man-made attacks etc.). However, there has been no such findings related to identification of leader and their leadership characteristics associated with natural hazards in previous studies. We have collected 20.6 million tweets which were posted by 5.3 million users, during distinct devastating hazards namely - Floods, Hurricane, Earthquake and Typhoons. To achieve the goal, we divided our work in to three parts. Firstly, classify the collected crises data into four domains i.e resource, causality, news, and sympathy by employing deeper recurrent neural network model. Secondly, we used statistical physics of complex network to recognize local as well as global prominent leaders. At last, we curate leadership characteristics in terms of their big five personality traits and emotional traits. Our experimental, results find evidence that local leadership behaviour characteristics are significantly different from global potentials. Where as we also finds that some behaviour traits were certain to classified domains (resource, causality, news, and sympathy) and some were certain to hazard divisions, though emotional characteristics remained consistent. Later, we conclude that local potentials leaders have comparatively higher emotional strength. Furthermore, when the complete local network structure is unavailable, we find that the dynamic rank is reliable indexing proxy for local potentials. The current study, provide useful insight to understand how leadership characteristics are influenced to hazards, domains and centrality of users.
Ultrashort-range, high-frequency communication by female mice shapes social interactions
Authors: Warren M. R. , Clein R. S. , Spurrier M. S. , Roth E. D. , Neunuebel J. P.
Published: February 2020

Animals engage in complex social encounters that influence social groups and resource allocation. During these encounters, acoustic signals, used at both short and long ranges, play pivotal roles in regulating the behavior of conspecifics. Mice, for instance, emit ultrasonic vocalizations, signals above the range of human hearing, during close-range social interactions. How these signals shape behavior, however, is unknown due to the difficulty in discerning which mouse in a group is vocalizing. To overcome this impediment, we used an eight-channel microphone array system to determine which mouse emitted individual vocal signals during 30 minutes of unrestrained social interaction between a female and a single male or female conspecific. Females modulated both the timing and context of vocal emission based upon their social partner. Compared to opposite-sex pairings, females in same-sex pairs vocalized when closer to a social partner and later in the 30 minutes of social engagement. Remarkably, we found that female mice exhibited no immediate changes in acceleration (movement) to male-emitted vocal signals. Both males and females, in contrast, modulated their behavior following female-emitted vocal signals in a context-dependent manner. Thus, our results suggest female vocal signals function as a means of ultrashort-range communication that shapes mouse social behavior.
Explicit Sequence Memory in Recall of Temporally-structured Episodes
Authors: Stern Yonatan , Katz Ron , Sadeh Talya
Published: February 2020

The order in which events unfold over time is an important scaffold aiding recollection. This study asks whether explicit order memory is enhanced for items sharing similar internally-driven temporal contexts. To tap internally-driven temporal context, we capitalized on the Temporal Contiguity Effect whereby recollection of one item promotes recall of adjacently-encoded items. We compared pairs encoded and retrieved contiguously (cont-enc-ret), whose items share internally-driven temporal contexts, to pairs retrieved, but not encoded, contiguously (cont-ret) and to pairs encoded, but not retrieved, contiguously (cont-enc). Cont-enc-ret pairs exhibited superior relative order over cont-ret pairs, supporting accounts emphasizing shared temporal context as opposed to temporal distinctiveness in driving sequence memory. No difference was found in absolute order between the pair types, in line with theories suggesting a dissociation between relative and absolute order. Additionally, cont-enc-ret and cont-enc pairs exhibited equivalent relative order, supporting the role of encoding as opposed to retrieval in the enhancement of relative order. Finally, cont-enc-ret pairs were perceived as closer than cont-enc pairs, supporting the claim that cont-enc-ret pairs constitute part of a temporally-coherent episode. Together, these results implicate internally-driven temporal context in the formation of temporally-structured episodes that enhances sequence memory of the items within the episode.
Seasonal simulated photoperiods influence melatonin release and immune markers of pike perch Sander lucioperca
Authors: Baekelandt Sébastien , Milla Sylvain , Cornet Valérie , Flamion Enora , Ledoré Yannick , Redivo Baptiste , Antipine Sascha , Mandiki Syaghalirwa N. M. , Houndji Alexis , El Kertaoui Najlae , Kestemont Patrick
Published: February 2020

Melatonin is considered as the time-keeping hormone acting on important physiological functions of teleosts. While the influence of melatonin on reproduction and development is well described, its potential role on immune functions has little been considered. In order to better define an immune modulation by the melatonin hormone, we hypothesized that natural variations of photoperiod and subsequent changes in melatonin release profile may act on immune status of pikeperch. Therefore, we investigated during 70 days the effects of two photoperiod regimes simulating the fall and spring in western Europe, on pikeperch physiological and immune responses. Samples were collected at 04:00 and 15:00 at days 1, 37 and 70. Growth, plasma melatonin levels, innate immune markers and expression of immune-relevant genes in head kidney tissue were assessed. While growth and stress level were not affected by the seasonal simulated photoperiods, nocturnal levels of plasma melatonin were photoperiod-dependent. Innate immune markers, including lysozyme, complement, peroxidase and phagocytic activities, were stimulated by the fall-simulated photoperiod and a significant correlation was made with plasma melatonin. In addition to bring the first evidence of changes in fish immunocompetence related to photoperiod, our results provide an additional indication supporting the immunomodulatory action of melatonin in teleosts.
Conformational perturbation, allosteric modulation of cellular signaling pathways, and disease in P23H rhodopsin
Authors: Woods Kristina N. , Pfeffer Jürgen
Published: February 2020

In this investigation we use THz spectroscopy and MD simulation to study the functional dynamics and conformational stability of P23H rhodopsin. The P23H mutation of rod opsin is the most common cause of human binding autosomal dominant retinitis pigmentosa (ADRP), but the precise mechanism by which this mutation leads to photoreceptor cell degeneration has not yet been elucidated. Our measurements confirm conformational instability in the global modes of the receptor and an active-state that uncouples the torsional dynamics of the retinal with protein functional modes, indicating inefficient signaling in P23H and a drastically altered mechanism of activation when contrasted with the wild-type receptor. Further, our MD simulations indicate that P23H rhodopsin is not functional as a monomer but rather, due to the instability of the mutant receptor, preferentially adopts a specific homodimerization motif. The preferred homodimer configuration induces structural changes in the receptor tertiary structure that reduces the affinity of the receptor for the retinal and significantly modifies the interactions of the Meta-II signaling state. We conjecture that the formation of the specific dimerization motif of P23H rhodopsin represents a cellular-wide signaling perturbation that is directly tied with the mechanism of P23H disease pathogenesis. Our results also support a direct role for rhodopsin P23H dimerization in photoreceptor rod death.
Complex System Analysis of Korean Peninsula Earthquake Data
Authors: Chae Sangwon , Jang Suyoung , Lee Sangmok , Lee Donghyun
Published: February 2020

Earthquakes are natural disasters that cause damage in a wide range of regions and represent a complex system that does not have a clear causal relationship with specific observable factors. This research analyzes the earthquake activities on the Korean Peninsula with respect to spatial and temporal factors. Using logarithmic regression analysis, we showed that the relationship between the location of the earthquake and its frequency in these locations follows a power law distribution. In addition, we showed that since 1998 the average earthquake magnitude has decreased from 3.0143 to 2.5433 and the frequency has risen by 3.98 times. Finally, the spatial analysis revealed significantly concentrated earthquake activities in a few particular areas and showed that earthquake occurrence points have shifted southeast. This research showed the change in earthquake dynamics and concentration of earthquake activities in particular regions over time. This finding implies the necessity of further research on spatially-derived earthquake policies on the change of earthquake dynamics.
Author Correction: Validation of the Sleep Regularity Index in Older Adults and Associations with Cardiometabolic Risk
Authors: Lunsford-Avery Jessica R. , Engelhard Matthew M. , Navar Ann Marie , Kollins Scott H.
Published: February 2020

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
A bis-vanadyl coordination complex as a 2-qubit quantum gate
Authors: Borilovic Ivana , Alonso Pablo J. , Roubeau Olivier , Aromí Guillem
Published: February 2020

A divanadyl complex anion is isolated through a new bis-hydroxyphenylpyrazolyl ligand and has optimal weak dipolar coupling and quantum coherence to implement electron-mediated nuclear quantum simulations in a 2-qubit molecular architecture.
The impact of intelligent cyber-physical systems on the decarbonization of energy
Authors: Inderwildi Oliver , Zhang Chuan , Wang Xiaonan , Kraft Markus
Published: February 2020

Assessing the impact of digital technologies and artificial intelligence, so-called intelligent cyber-physical systems, on emission reduction in the critical sector of energy provision.
Dynamic self-assembly of detonation nanodiamond in water
Authors: Chang Shery L. Y. , Reineck Philipp , Williams Dewight , Bryant Gary , Opletal George , El-Demrdash Samir A. , Chiu Po-Lin , Ōsawa Eiji , Barnard Amanda S. , Dwyer Christian
Published: February 2020

We use direct imaging and dynamic light scattering to reveal the previously unknown dynamic self-assembly of detonation nanodiamond dispersions in water which have been purified without additional surface modification.
Enzyme-mediated reversible deactivation radical polymerization for functional materials: principles, synthesis, and applications
Authors: Xiong Qingyun , Zhang Xiaoyuan , Wei Wenfeng , Wei Gang , Su Zhiqiang
Published: February 2020

Enzymes provide a potential and highly efficient way to mediate the formation of various functional polymer materials with wide applications.
Sappanone A alleviates hypoxia/reoxygenation-induced cardiomyocytes injury through inhibition of mitochondrial apoptosis and activation of PI3K–Akt–Gsk-3β pathway
Authors: Shi Xiaojing , Tao Guizhou , Ji Lili , Tian Ge
Published: February 2020

Myocardial ischemia reperfusion injury (MIRI) is a complex pathophysiological process involved with the activation of oxidative stress, inflammation and apoptosis. Sappanone A (SA), a homoisoflavanone isolated from the heartwood of Caesalpinia sappan L., could exhibit antioxidant, anti-inflammatory and anti-apoptotic activities. Therefore, we assumed that SA has a potential use for preventing against MIRI. The present study aimed to investigate the effect of SA treatment on MIRI and its mechanism. Cardiomyocytes (H9c2 cells) were treated with SA for 1 h, followed by 6 h of hypoxia/3 h of reoxygenation. Cell viability assay was detected by CCK-8 assay. Apoptosis was measured by flow cytometry and Hoechst staining. Mitochondrial permeability transition pore (mPTP) opening and mitochondrial transmembrane potential (ΔΨm) were measured by spectrophotometry and JC-1 staining. The changes of mitochondrial apoptosis-related proteins and PI3K–Akt–Gsk-3β signaling pathway were evaluated by Western blotting. The results showed that SA pretreatment enhanced the cell viability and decreased the activity of myocardial enzyme in a dose-dependent manner. Moreover, SA pretreatment significantly inhibited apoptosis, blocked mPTP opening, suppressed the release of ΔΨm, prevented the cytochrome c releasing from mitochondria into cytoplasm, and repressed the cleavage of caspase-9 and caspase-3. Furthermore, SA pretreatment increased the phosphorylation levels of Akt and Gsk-3β but not of Stat-3. Meanwhile, the protective effect of SA was abrogated by PI3K inhibitor (LY294002). In conclusion, our results demonstrate that SA could prevent hypoxia/reoxygenation-induced cardiomyocytes injury through inhibition of mitochondrial apoptosis and activation of PI3K–Akt–Gsk-3β pathway. Thus, SA may have a potential use for the prevention of MIRI.
Wnt/β-catenin signaling as an emerging potential key pharmacological target in cholangiocarcinoma
Authors: Zhang Guo-Feng , Qiu Ling , Yang Shu-Li , Wu Jia-Cheng , Liu Tong-Jun
Published: February 2020

Cholangiocarcinoma (CCA) is a fatal malignant tumor of biliary epithelial cells involving intra- or extra-hepatic bile ducts. The prognosis of CCA is generally poor due to its diagnosis at the late stages. The currently employed chemotherapeutic agents do not increase the survival rate in patients with unresectable CCA. Accordingly, there is a need to identify new therapeutic agents for the effective management of intra- and extra-hepatic CCA. Clinical as well as preclinical studies have suggested the key role of the activation of Wnt/β-catenin signaling pathway in the induction and progression of CCA. There is an up-regulation of different Wnt ligands including Wnt2, Wnt3, Wnt5, Wnt7 and Wnt10 along with redistribution of β-catenin (more expression in the nucleus and lesser on the cell surface due to nuclear translocation of β-catenin) in different types of malignant biliary tumors. Apart from the role of this pathway in the induction and progression of CCA, this pathway is also involved in inducing multidrug resistance by inducing the expression of P-glycoprotein efflux pump on the cancer cells. These deleterious effects of Wnt/β-catenin signaling are mediated in association with other signaling pathways involving microRNAs (miRNAs), PI3K/AKT/PTEN/GSK-3β, retinoic acid receptors (RARs), dickkopf-1 (DKK1), protein kinase A regulatory subunit 1 α (PRKAR1A/PKAI), (SLAP), liver kinase B1 (LKB1) and CXCR4. The selective inhibitors of Wnt/β-catenin signaling may be potentially employed to overcome multidrug-resistant, fatal CCA. The present review discusses the role of Wnt/β-catenin along with its relation with other signaling pathways in the induction and progression of CCA.
SLC39A7, regulated by miR-139-5p, induces cell proliferation, migration and inhibits apoptosis in gastric cancer via Akt/mTOR signaling pathway
Authors: Zhang Yanting , Bai Jie , Si Wangli , Yuan Shanshan , Li Yijun , Chen Xiaolu
Published: February 2020

As a zinc transporter, SLC39A7 (zip7) is vital in intestinal epithelial self-renewal, and recent studies suggested that SLC39A7 was related to cancer progression. Whereas, little is known about the role of SLC39A7 in gastric cancer (GC). In the present study, qRT-PCR analysis demonstrated that SLC39A7 mRNA level was increased in both GC tissues and cell lines. Overexpressing SLC39A7 boosted cell proliferation and migration, while inhibited apoptosis in GC. It was also found that si-SLC39A7 suppressed Akt/mTOR pathway and activation of Akt/mTOR pathway reversed the effects of si-SLC39A7 on GC development. Through prediction website, we found that SLC39A7 was directly regulated by miR-139-5p. miR-139-5p mimic had adverse effects on SLC39A7 expression and influence in the GC cell proliferation, migration and apoptosis by Akt/mTOR signaling pathway, while miR-139-5p inhibitor showed opposite effects. To conclude, our studies showed that SLC39A7 was negatively regulated by miR-139-5p. Besides, SLC39A7 positively regulated GC development through Akt/mTOR signaling pathway. These results indicate that SLC39A7 may be a candidate target gene for GC treatment.
Relative Fundamental Frequency in Children With and Without Vocal Fold Nodules
Authors: Heller Murray Elizabeth S. , Segina Roxanne K. , Woodnorth Geralyn Harvey , Stepp Cara E.
Published: February 2020

Purpose

Relative fundamental frequency (RFF) is an acoustic measure that is sensitive to functional voice differences in adults. The aim of the current study was to evaluate RFF in children, as there are known structural and functional differences between the pediatric and adult vocal mechanisms.

Method

RFF was analyzed in 28 children with vocal fold nodules (CwVN,
M
= 9.0 years) and 28 children with typical voices (CwTV,
M
= 8.9 years). RFF is the instantaneous fundamental frequency (
f
0
) of the 10 vocalic cycles during devoicing (vocal offset) and 10 vocalic cycles during the revoicing (vocal onset) of the vowels that surround a voiceless consonant. Each cycle's
f
0
was normalized to a steady-state portion of the vowel. RFF values for the cycles closest to the voiceless consonant, that is, Offset Cycle 10 and Onset Cycle 1, were examined.

Results

Average RFF values for Offset Cycle 10 and Onset Cycle 1 did not differ between CwVN and CwTV; however, within-subject variability of Offset Cycle 10 was decreased in CwVN. Across both groups, male children had lower Offset Cycle 10 RFF values as compared to female children. Additionally, Onset Cycle 1 values were decreased in younger children as compared to those of older children.

Conclusions

Unlike previous work with adults, CwVN did not have significantly different RFF values than CwTV. Younger children had lower RFF values for Onset Cycle 1 than older children, suggesting that vocal onset
f
0
may provide information on the maturity of the laryngeal motor system.
Iterative Development of a Home Review Program to Promote Preschoolers' Vocabulary Skills: Social Validity and Learning Outcomes
Authors: Soto Xigrid , Seven Yagmur , McKenna Meaghan , Madsen Keri , Peters-Sanders Lindsey , Kelley Elizabeth Spencer , Goldstein Howard
Published: February 2020

Purpose

This article describes the iterative development of a home review program designed to augment vocabulary instruction for young children (ages 4 and 5 years) occurring at school through the use of a home review component.

Method

A pilot study followed by two experiments used adapted alternating treatment designs to compare the learning of academic words taught at school to words taught at school and reviewed at home. At school, children in small groups were taught academic words embedded in prerecorded storybooks for 6 weeks. Children were given materials such as stickers with review prompts (e.g., “Tell me whatbravemeans”) to take home for half the words. Across iterations of the home intervention, the home review component was enhanced by promoting parent engagement and buy-in through in-person training, video modeling, and daily text message reminders. Visual analyses of single-subject graphs, multilevel modeling, and social validity measures were used to evaluate the additive effects and feasibility of the home review component.

Results

Social validity results informed each iteration of the home program. The effects of the home program across sites were mixed, with only one site showing consistently strong effects. Superior learning was evident in the school + home review condition for families that reviewed words frequently at home. Although the home review program was effective in improving the vocabulary skills of many children, some families had considerable difficulty practicing vocabulary words.

Conclusion

These studies highlight the importance of using social validity measures to inform iterative development of home interventions that promote feasible strategies for enhancing the home language environment. Further research is needed to identify strategies that stimulate facilitators and overcome barriers to implementation, especially in high-stress homes, to enrich the home language environments of more families.
Maximum likelihood identification of dual‐rate Hammerstein output‐error moving average system
Authors: Li Junhong , Zhang Jiali
Published: February 2020

This study discusses the parameter estimation of the Hammerstein output‐error moving average system using the dual‐rate sampled data. The polynomial transformation technique is used to obtain the identification model of the discussed dual‐rate sampled systems. The stochastic gradient optimisation method is an effective optimisation method. Compared with the Newton optimisation, it only needs to calculate the first derivative during the optimisation and the amount of calculation is relatively small. It is a good choice to use the stochastic gradient algorithm for the identification of Hammerstein dual‐rate model after using the polynomial transformation technique. In order to improve the convergence speed, a maximum likelihood forgetting factor stochastic gradient identification algorithm is proposed by combining the maximum likelihood principle and the gradient search method. The convergence of the algorithm is analysed by using the stochastic process theory. Furthermore, in order to improve the estimation accuracy of the identification algorithm, a maximum likelihood multi‐innovation forgetting factor stochastic gradient algorithm is proposed by using the multi‐innovation identification theory. The effectiveness of the proposed algorithms is illustrated by a numerical simulation example and a water tank system.
Polyhedral approximation method for reachable sets of linear delay systems
Authors: Hu Renhong , Shao Lizhen , Cong Yuhao
Published: February 2020

In this study, a polyhedral approximation method for reachable sets of linear delay systems is investigated. For a continuous linear system with multiple delays, the first Euler scheme combining with linear interpolation is used to transform it into a discrete one. Then a polyhedral approximation method based on optimisation techniques is proposed to compute the discrete reachable set. By specifying an approximation error and solving a finite number of convex optimisation problems, a polyhedron can be constructed as the approximation of the discrete reachable set. The approximation quality measured in Hausdorff distance can be directly controlled. Next, illustrated examples are given to demonstrate the effectiveness of the proposed method. Finally, the authors show some reachable sets of linear delay control systems, and they compare the proposed method with some other methods in the literature. Numerical results clearly show the superior performance of the proposed method.
Coherent track‐before‐detect with micro‐Doppler signature estimation in array radars
Authors: Kim Kimin , Üney Murat , Mulgrew Bernard
Published: February 2020

In this work, the authors consider joint micro‐Doppler signature estimation and track‐before‐detect for detecting and classifying manoeuvring and small rotary‐wing aircraft with a phased array radar receiver. Such aircraft induce low signal‐to‐noise ratio reflections which complicates their detection. These difficulties are exacerbated by the high manoeuvrability of such aircraft which results with resolution cell migrations in conventional detectors. The authors propose a novel track‐before‐detect algorithm which jointly estimates the micro‐Doppler signature, dominant reflectivity and kinematic trajectory of an object before the decision on its existence is made. These quantities are used in a Neyman‐Pearson test against a constant false alarm rate threshold which is equivalent to evaluating a coherent long time integration value. The authors demonstrate the efficacy of the proposed scheme in a real data experiment and compare it with conventional techniques.
Prediction‐discrepancy based on innovative particle filter for estimating UAV true position in the presence of the GPS spoofing attacks
Authors: Majidi Mohammad , Erfanian Alireza , Khaloozadeh Hamid
Published: February 2020

In this paper, a novel prediction‐discrepancy based on innovative particle filter (PDIPF) is proposed to solve the unmanned aerial vehicle (UAV) positioning problem in the presence of the global positioning system (GPS) spoofing attack, supposing that the GPS spoofing effects are in the form of unknown but bounded errors. To cope with the GPS spoofing attacks as unknown sudden changes of system state variables, the compensation of the GPS spoofing effects is adaptively done in two basic parts of PDIPF algorithm including particle weighting and covariance matrix adaption. In addition, a theorem is developed which verifies that the output estimation error is upper bounded by a given probability with the help of the adapted covariance matrix. Besides, the particle weight calculation in PDIPF is done with respect to the prediction discrepancy of generated particles from the GPS measurements. The proposed PDIPF is used to decrease the effects of any GPS spoofing errors with different probability density functions and estimate true position of UAV in the presence of the GPS spoofing attacks. The algorithm is applied to the inertial navigation system/GPS/Loran‐C integration systems. Simulation results demonstrate the effectiveness of the proposed PDIPF algorithm in terms of accuracy and redundancy.
Constraining the redshifts of unlocalised fast radio bursts
Authors: Walker Charles R. H. , Ma Yin-Zhe , Breton René P.
Published: February 2020

Context. The relationship between the dispersion measures (DMs) and redshifts of fast radio bursts (FRBs) is of scientific interest. Upcoming commensal surveys may detect and localise many FRBs to the sub-arcsecond angular resolutions required for accurate redshift determination. Meanwhile, it is important to exploit sources accumulated with more limited localisation to their maximum scientific potential.

Aims. We present techniques for the DM-redshift analysis of large numbers of unlocalised FRBs, accounting for uncertainties due to their extragalactic DM components, redshift dependences, and progenitor scenarios.

Methods. We reviewed the components comprising observed FRB DMs. We built redshift-scalable probability distribution functions for these components, which we combined in cases of multiple progenitor scenarios. Accounting for prior FRB redshift distributions we inverted these models, enabling FRB redshifts to be constrained.

Results. We illustrate the influence of FRB progenitors on their observed DMs, which may remain significant to redshift z ~ 3. We identify the FRB sample sizes required to distinguish between multiple progenitor scenarios. We place new, physically motivated redshift constraints on all catalogued FRBs to date and use these to reject potential host galaxies in the localisation area of an FRB according to various models. We identify further uses for DM-redshift analysis using many FRBs. We provide our code so that these techniques may be employed using increasingly realistic models as our understanding of FRBs evolves.
Tracing the anemic stellar halo of M 101
Authors: Jang In Sung , de Jong Roelof S. , Holwerda Benne W. , Monachesi Antonela , Bell Eric F. , Bailin Jeremy
Published: February 2020

Models of galaxy formation in a cosmological context predict that massive disk galaxies should have structured extended stellar halos. Recent studies in integrated light, however, report that a few galaxies, including the nearby disk galaxy M 101, have no measurable stellar halos to the detection limit. We aim to quantify the stellar content and structure of M 101’s outskirts by resolving its stars. We present the photometry of its stars based on deepF606WandF814Wimages taken withHubbleSpace Telescope (HST) as part of the GHOSTS survey. The HST fields are placed along the east and west sides of M 101 out to galactocentric distance (R) of ∼70 kpc. The constructed color-magnitude diagrams of stars reach down to two magnitudes below the tip of the red giant branch. We derived radial number density profiles of the bright red giant branch (RGB) stars. The mean color of the RGB stars atR ∼ 40−60 kpc is similar to those of metal-poor globular clusters in the Milky Way. We also derived radial surface brightness profiles using the public image data provided by the Dragonfly team. Both the radial number density and surface brightness profiles were converted to radial mass density profiles and combined. We find that the mass density profiles show a weak upturn at the very outer region, where surface brightness is as faint asμg ≈ 33 mag arcsec−2. An exponential disk + power-law halo model on the mass density profiles finds the total stellar halo mass ofMhalo= 8.2−2.2+3.5× 107M⊙. The total stellar halo mass does not exceedMhalo = 3.2 × 108 M⊙when strongly truncated disk models are considered. In combining the halo mass with the total stellar mass of M 101, we obtain the stellar halo mass fraction ofMhalo/Mgal= 0.20−0.08+0.10% with an upper limit of 0.78%. We compare the halo properties of M 101 with those of six GHOSTS survey galaxies as well as the Milky Way and M 31 and find that M 101 has an anemic stellar halo similar to the Milky Way.