bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of double-diffusive convection in basal melting of Antarctic ice shelves
Authors: Rosevear Madelaine Gamble , Gayen Bishakhdatta , Galton-Fenzi Benjamin Keith
Published: February 2021

Significance

Ocean-driven melting of ice shelves is a leading cause of mass loss from Antarctica. However, the small-scale ocean processes responsible for melting are poorly understood due to the difficulty of making direct measurements in these hard to reach environments. Here, we use a high-resolution ocean model to fill this knowledge gap. At low current speeds and relatively warm ocean temperatures, we show that a small-scale ocean process called double-diffusive convection controls ice shelf melt rates and turbulent mixing, forming a unique “staircase” structure beneath the ice. This process is currently missing from ocean–climate models, which consider only turbulent melting due to ocean currents.
Neural divergence and hybrid disruption between ecologically isolatedHeliconiusbutterflies
Authors: Montgomery Stephen H. , Rossi Matteo , McMillan W. Owen , Merrill Richard M.
Published: February 2021

Significance

Although previous studies highlight the importance of ecological variation in driving divergence in brain morphology, whether these changes accumulate after ecological transitions or play a significant role in facilitating them is unclear. We show that divergent selection associated with microhabitat partitioning drove heritable divergence in brain composition and neural gene expression between sister clades ofHeliconiusbutterflies. Neuroanatomical divergence is restricted to visual structures and reflect adaptations to contrasting sensory niches. We show how divergent neural traits can act as barriers to gene flow by demonstrating that hybrids have intermediate traits and by presenting evidence that genes with adaptive patterns of expression divergence are more likely to occur in regions of the genome that are resistant to interspecific gene flow.
Shared partisanship dramatically increases social tie formation in a Twitter field experiment
Authors: Mosleh Mohsen , Martel Cameron , Eckles Dean , Rand David G.
Published: February 2021

Americans are much more likely to be socially connected to copartisans, both in daily life and on social media. However, this observation does not necessarily mean that shared partisanship per se drives social tie formation, because partisanship is confounded with many other factors. Here, we test the causal effect of shared partisanship on the formation of social ties in a field experiment on Twitter. We created bot accounts that self-identified as people who favored the Democratic or Republican party and that varied in the strength of that identification. We then randomly assigned 842 Twitter users to be followed by one of our accounts. Users were roughly three times more likely to reciprocally follow-back bots whose partisanship matched their own, and this was true regardless of the bot’s strength of identification. Interestingly, there was no partisan asymmetry in this preferential follow-back behavior: Democrats and Republicans alike were much more likely to reciprocate follows from copartisans. These results demonstrate a strong causal effect of shared partisanship on the formation of social ties in an ecologically valid field setting and have important implications for political psychology, social media, and the politically polarized state of the American public.
The Myc-associated zinc finger protein (MAZ) works together with CTCF to control cohesin positioning and genome organization
Authors: Xiao Tiaojiang , Li Xin , Felsenfeld Gary
Published: February 2021

Significance

The protein CTCF plays a major role in large-scale organization of the genome. Binding sites for the protein MAZ are found adjacent to many CTCF sites. We show that, at such double sites, MAZ stabilizes CTCF binding. MAZ, like CTCF, acts independently as an “insulator” element to block the effects of a distal enhancer on a promoter, and, like CTCF, it can block the advance of a transcribing RNA polymerase II, leading to alternative RNA splicing patterns. Depletion of MAZ causes loss of short-range interactions within the nucleus and disruption of some longer-range interactions. Thus, MAZ plays a complementary role to CTCF in the nucleus, enhancing the organizational properties of CTCF and displaying many functions related to genome organization.
Spin stiffness of chromium-based van der Waals ferromagnets
Authors: Shu Zhixue , Kong Tai
Published: February 2021

Low temperature magnetization of CrI3, CrSiTe3 and CrGeTe3 single crystals were systematically studied. Based on the temperature dependence of extrapolated spontaneous magnetization from magnetic isotherms measured at different temperatures, the spin stiffness constant (D) and spin excitation gap (Δ) were extracted according to Bloch’s law. For spin stiffness, D is estimated to be 27 ± 6 meV Å2, 20 ± 3 meV Å2 and 38 ± 7 meV Å2 for CrI3, CrSiTe3 and CrGeTe3 respectively. Spin excitation gaps determined via Bloch’s formulation have larger error bars yielding 0.59 ± 0.34 meV (CrI3), 0.37 ± 0.22 meV (CrSiTe3) and 0.28 ± 0.19 meV (CrGeTe3). Among all three studied compounds, larger spin stiffness value leads to higher ferromagnetic transition temperature.
An affibody-conjugated nanoprobe for IGF-1R targeted cancer fluorescent and photoacoustic dual-modality imaging
Authors: Sun Ran , Zhao Yuyang , Wang Yanan , Zhang Qian , Zhao Ping
Published: February 2021

Dual-modal molecular imaging that combines photoacoustic imaging with near-infrared fluorescence imaging integrates the benefits of both imaging modalities and may achieve more precise detection of disease. In this study, silver sulfide quantum dots (Ag2S QDs) with superior photoacoustic properties and a strong fluorescent emission in the NIR region were successfully synthesized. They were further modified with the insulin-like growth factor 1 receptor (IGF-1R) targeted small scaffold protein, Affibody (ZIGF-1) to achieved targeted photoacoustic/fluorescent dual-modal imaging of cancer. Our results showed that the prepared nanoprobe had good tumor targeting properties in vivo, and the probe also showed good biocompatibility without any significant toxicity.
Amorphous gallium oxide (a-Ga2O3)-based high-temperature bendable solar-blind ultraviolet photodetector
Authors: Xiong Lingxing , Zhang Lei , Lv Qipu , Li Tao , Song Wenqing , Si Jiawei , Zhu Wenhui , Wang Liancheng
Published: February 2021

A bendable and thermally stable solar-blind ultraviolet (UV) photodetector has been demonstrated based on Ni/amorphous Ga2O3 (a-Ga2O3)/a-AlN/Cu foil structure. Here, Cu foil can simultaneously act as a bendable substrate and withstand a high-temperature environment. The ultra-wide bandgap a-AlN insulating layer can withstand mechanical tensile stress and effectively act as an insulating layer between a-Ga2O3 and Cu. Thus, the a-Ga2O3-based photodetector shows stable UV response characteristics with different bending radii and temperatures. The photodetector has high responsivity of 0.518 A W−1 and a fast response time of 0.17 s under 200 °C temperature with a 1.46 cm bending radius. With exceptional bendability and thermal stability, this a-Ga2O3-based photodetector has potential applications in harsh environments such as high-power bendable electron devices, flame detection, etc.
Corrigendum: “Design and operation of the ATLAS Transient Science Server” (2020, PASP, 132, 085002)
Authors: Smith K. W. , Smartt S. J. , Young D. R. , Tonry J. L. , Denneau L. , Flewelling H. , Heinze A. N. , Weiland H. J. , Stalder B. , Rest A. , Stubbs C. W. , Anderson J. P. , Chen T.-W , Clark P. , Do A. , Förster F. , Fulton M. , Gillanders J. , McBrien O. R. , O’Neill D. , Srivastav S. , Wright D. E.
Published: February 2021

In Smith et al. we published estimates of the volumetric rate of supernovae within 100 Mpc. These were incorrect and we present the correct values in this corrigendum.
Terahertz radiation enhancement based on LT-GaAs by optimized plasmonic nanostructure
Authors: Jiang Rui , Cheng Shuang , Li Quanyong , Wang Qishu , Xin Yinjie
Published: February 2021

Terahertz waves have unique penetrability, safety, spectral resolution, and many other useful properties. Therefore, terahertz waves are widely employed in medical treatment, detection, imaging, security, and spectroscopy. They also possess great development prospects in photoconductive antennas (PCAs) for telecommunication and other devices. However, terahertz PCAs are still limited by the weak photocurrents and small light absorption rates, making the development of PCAs with improved conversion efficiencies highly desirable. In this study, a new type of plasmonic PCAs with high photoelectric conversion efficiency was proposed. The interaction between the 800 nm fs laser and staggered nanorods was studied by the finite difference time domain (FDTD) method. The geometric parameters of the nanorods arrays were optimized. Compared to conventional photoconductive antennas without nanostructures, the PCAs with optimized nano-plasmonic structure I showed threefold higher electric field radiations under 800 nm fs laser irradiation. Optimized plasmonic nanostructure II increases photocurrent up to 335.553 nA that indicates 10 times enhancement in comparison with conventional structure. Hence, the developed structures greatly enhanced the light absorption of the photosensitive layer based on low-temperature-grown gallium arsenide. In sum, the proposed staggered hexagonal plasmonic structures (structure II) could effectively improve the light-terahertz conversion efficiencies of PCAs.
Ablation study in gold irradiated by single femtosecond laser pulse with electron temperature dependent interatomic potential and electron–phonon coupling factor
Authors: Yuan Weirong , Sizyuk Tatyana
Published: February 2021

The interactions of femtosecond lasers with gold targets are investigated with a numerical method combining molecular dynamics and two-temperature model and temperature dependent thermodynamic parameters. The influence of the electron temperature dependent (ETD) interatomic potential on ablation processes was analyzed. We also adopted an ETD electron–phonon coupling factor and further analyzed different ablation mechanisms under absorbed fluences ranging from

40

mJ

c

m

−

2

to

150

mJ

c

m

−

2

.

Our simulation results showed good agreements on melting and ablation depth with both experiments and other simulations. Three ablation mechanisms were identified: nonthermal ablation caused by electronic pressure from the ETD interatomic potential, spallation by stresses from a rapid heating of the target and phase explosion due to explosive boiling. With a continuously updated ETD potential in accordance with electron temperature, one can explain the unique U shape profile of plume atomization degree as a function of laser fluence found in experiments.
Fast dissipative preparation of three-dimensional entangled states for two Rydberg atoms via Lyapunov control
Authors: Ding Zong-Xing , Hu Chang-Sheng , Shen Li-Tuo , Su Wan-Jun , Wu Huaizhi , Zheng Shi-Biao
Published: February 2021

By using the Lyapunov control approach—an optimization algorithm, we propose a dissipative scheme for efficiently preparing the three-dimensional entangled state of two Rydberg atoms, which subject to Rydberg–Rydberg interactions at the antiblockade regime. The steady target state is the unique dark state of the two-atom system, and is achieved with high fidelity under the Rydberg pumping and the atomic spontaneous emission. The time required to settle into the high-fidelity steady state is greatly accelerated by the help of Lyapunov control, which takes effects while the system is initially prepared in the states containing coherence between the dark state and decoherence-sensitive bright states. The numerical results show that a fidelity of the steady three-dimensional entangled state above 0.99 can be achieved around 2.2 ms with the current experimental conditions. We study in detail the optimal control parameters and show the robustness of the scheme against random noises. The scheme may be generalized for preparation of more complicate multi-atom entangled states.
A simple method to synthesize worm-like AlN nanowires and its field emission studies*
Authors: Liang Qi , Yang Meng-Qi , Wang Chang-Hao , Wang Ru-Zhi
Published: February 2021

The worm-like AlN nanowires are fabricated by the plasma-enhanced chemical vapor deposition (PECVD) on Si substrates through using Al powder and N2 as precursors, CaF2 as fluxing medium, Au as catalyst, respectively. The as-grown worm-like AlN nanowires each have a polycrystalline and hexagonal wurtzite structure. Their diameters are about 300 nm, and the lengths are over 10 μm. The growth mechanism of worm-like AlN nanowires is discussed. Hydrogen plasma plays a very important role in forming the polycrystalline structure and rough surfaces of worm-like AlN nanowires. The worm-like AlN nanowires exhibit an excellent field-emission (FE) property with a low turn-on field of 4.5 V/μm at a current density of 0.01 mA/cm2 and low threshold field of 9.9 V/μm at 1 mA/cm2. The emission current densities of worm-like AlN nanowires each have a good stability. The enhanced FE properties of worm-like AlN nanowires may be due to their polycrystalline and rough structure with nanosize and high aspect ratio. The excellent FE properties of worm-like AlN nanowires can be explained by a grain boundary conduction mechanism. The results demonstrate that the worm-like AlN nanowires prepared by the proposed simple and the PECVD method possesses the potential applications in photoelectric and field-emission devices.
Structure and magnetic properties of RAlSi (R = light rare earth)*
Authors: Wang Tai , Guo Yongquan , Wang Cong
Published: February 2021

We prepared the semimetals RAlSi (R = light rare earth), and systematically study their crystal structures and magnetic properties. X-ray diffractions confirm the coexistence of the site-disordered phase with group space of I41/amd and the noncentrosymmetrically ordered phase with space group of I41
md in RAlSi alloy. The ordered phase is the main phase in RAlSi alloy. RAlSi alloys show nonmagnetic character for R = La, low temperature ferromagnetic order for R = Ce, Pr, and paramagnetic character for R = Nd, respectively. SmAlSi shows metamagnetic transition at 10 K and ferromagnetic order at 143 K, respectively. SmAlSi follows the van Vleck paramagnetic model in its paramagnetic region. The magnetization curves of RAlSi (R = Ce, Pr, Sm) follow the mixed model of ferromagnetism and paramagnetism, and the fitted saturation moment M
S depends on the moment of trivalent rare earth. The paramagnetic susceptibility χ of RAlSi is going up with increasing the atomic order numbers of rare earth elements. This reveals that the magnetic property of RAlSi originates from the rare earth.
Determination of fungaltoxin residues in bergamot pear by UPLC-MS/MS
Authors: Lin Ling , Ye Jianzhi , Yang Chunliang , Liu Yuanjing , Guo Hongbin , Zeng Shaodong , Ma Huifang , Lin Liyun
Published: February 2021

The aim of this work was to establish a method that the residues of fungaltoxin including citrinin, alternariol and alternariolmethylether in bergamot pears were determined by UPLC-MS/MS. Samples were extracted by acetonitrile, using NaCl and anhydrous Magnesium Sulfate to remove the water, and C18 powder was used to purify and get rid of miscellaneous, then used organic membrane to filter the samples. Results showed that the detection limits of citrinin alternariol, and alternariolmethylether were 0.3 μg/kg, 0.5 μg/kg and 0. 2 μg/kg respectively. The average recovery rates of alternariolmethylether, alternariol, citrinin were 79%∼ 101%, and the relative standard deviations were between 0.3%∼4.5%.
Prediction of Unburned Carbon in Flue Dust based on Teacher-student Ensemble Method
Authors: Lu Kuan , Yang Xingsen , Wang Haichao , Liu Ke , Zhang Xuhui , Meng Xiangrong , Li Jun
Published: February 2021

Based on the idea of knowledge distillation, a teacher-student ensemble method is proposed for UCFD (Unburned Carbon in Flue Dust) prediction when influencing factors have different sampling frequency. First, a multi-layer feed forward network is built as the teacher model. Loss function is customized to account for the sampling period discrepancy between outputs and inputs. With this teacher model, UCFD could have the same rate with its influencing factors. Second, Xgboost and Adaboost are used to form an ensemble student model to improve the training process and prediction robustness. Third, a power plant in Shandong province is chosen to make data experiment. Results illustrate that the teacher-student ensemble method can give a more accurate forecast.
Multiple Resources Planning in Microgrid Based on Modeling Demand Response of User Side
Authors: Wang Si-cong , Wang Qi-xin , Sang Zi-xia , He Ji-feng , Huang Jia-qi , Yan Jiong , Fang Reng-cun
Published: February 2021

According to the characteristics and development trend of microgrid, instead of being the pure load, demand-side is treated as a kind of possible power supply (equivalent effect of reduction of the load) which can actively participate in the planning and operation in microgrid. An integrated resources planning model considering direct load control (one of demand responses) in microgrid was proposed. The validity of the proposed model was proved. It can be achieved to minimize the total cost of system planning by using demand response to actively participate in the planning. Depth discussions for the case were done to give comparative analysis of different control strategies, parameters and costs and more planning proposals were given.
Research on interruptible load supply curve simulation based on industrial classification
Authors: Feng Junshu , Jiao Bingqi , Zhao Jiujin
Published: February 2021

Recently, with the adjustment of industrial structure, peak power load is getting sharper in China. Interruptible Load Management (ILM) enables power system to gain deterministic access to Interruptible Load (IL) provided by power consumers, which can use a more economical way to ensure real-time balance and safe operation of power system. This paper proposes a simulation method of interruptible load supply curve of lager industrial power consumers based on industrial classification, which can predict capacity of interruptible load that lager industrial power consumers are willing to provide under different interruptible load prices. An example towards a China’s eastern province shows that, if government wants to acquire interruptible load capacity of 10 million kW, the interruptible price should be priced higher than 0.7 RMB/kWh.
Protection and Maintenance of Historical Buildings Based on Virtual Reality Technology
Authors: Wang Bin , Luo Lei , Wang Feiran
Published: February 2021

The continuous development of virtual reality technology has improved the production efficiency of various industries. The application of virtual reality technology in the protection and maintenance of historical buildings can provide relevant practitioners with new work directions. Based on previous work experience, this article summarizes the content of historical building protection based on virtual reality technology. Moreover, the author also discusses the protection and maintenance of historical buildings based on virtual reality technology from the following four aspects. It includes the maintenance characteristics, the specific conditions of the project, reasonable maintenance plans formulation, and three-dimensional virtual environment modeling.
Study on support Design of 2220 roadway in Majiliang Coal Mine based on FLAC3D
Authors: Renliang SHAN , Yongsheng BAO , Shengchao XIAO , Dali WANG , Jiaxin HAN
Published: February 2021

In view of the serious deformation of roadway 2220 in Majiliang Coal Mine after excavation, the surrounding rock deformation characteristics and stress redistribution of the roadway are studied and analyzed by numerical simulation technology, and the support optimization is carried out. The research results show that the original support scheme can not effectively reduce the roadway deformation and the area of plastic zone and stress concentration area after roadway excavation. After the optimization of the support scheme, the shape variables of the roof and floor and the two sides are obviously reduced, and the plastic zone and stress concentration area are also greatly reduced, which significantly improves the overall stability of the roadway.
The use of Hydrazine-based Derivatization technique to characterize glycosyl esters of crocetin from Saffron
Authors: Aiello Donatella
Published: February 2021

Saffron is one of the oldest natural dyestuffs and is obtained from the dried stigmata of Crocus sativus L. The yellowness of saffron results from the presence of crocins (glycosyl esters of crocetin). In this report we present the identification and characterization of multiple forms of crocins from whole saline saffron extracts using direct MALDI MS and MS/MS of glycosyl esters of crocetin and of their corresponding Hydrazine tagged products.
Latest developments in adhesive anchoring technology
Authors: Mahrenholtz P , Hsieh CW , Yu K
Published: February 2021

Adhesive anchoring is used to connect steel and concrete elements and to connect new to existing reinforced concrete structures. For this, threaded rods or reinforcing bars are bonded to the hardened concrete by adhesives. Internationally recognized qualification guidelines and design codes form the regulative basis for all approved products and ensures a high level of safety. This paper introduces the context of adhesive anchoring systems. An overview of relevant international regulations is provided, and the difference between post-installed anchor and post-installed rebar applications is explained. The latest developments in adhesive anchoring in regard to qualification and design is presented. The contribution aims at bringing the adhesive anchoring technology to the attention of a broader audience of the engineering and research community.
Identification and isolation of homoserine lactones (HSLs) produced by Pseudomonas aeruginosa and the effects on Legionella pneumophila growth
Authors: Materazzi S. , De Giusti M. , Marinelli L.
Published: February 2021

Risk for infections from Legionella pneumophila represents a critical issue for immunocompromised individuals, especially when this species is present within the biofilm of the water distribution systems of hospitals or other health facilities where the complex ancient water network creates environmental conditions that are suitable for Legionella persistence and multiplication. The shock hyperchlorination and subsequent systemic continuous chlorination is a disinfection treatment reported in the Italian Guideline for prevention and control of nosocomial legionellosis as an effective procedure to reduce L. pneumophila colonization of hospital water sources. Although this disinfection strategy has been proven to be effective in the short-term, eradication of Legionella from water networks is usually not achieved. The objective of this study is the identification and purification of P. aeruginosa bacteriocins, such as homoserine lactones (HSLs), by the development of an experimental method by High performance-liquid chromatography (HPLC), coupled to diode array detection (DAD) and the evaluation of the effectiveness of these molecules in the managing of the persistence of L. pneumophila in experimental cocultures.
A novel, structurally coloured coating for aluminium alloys
Authors: Mardon Ian J , Hou Fengyan , Goode Chris
Published: February 2021

Current approaches to coat aluminium surfaces that use paints and organic coatings to protect them from corrosion and provide an aesthetic finish, are also energy intensive and involve high emissions of VOCs. The use of these coatings is becoming increasingly restricted by global efforts towards more environmentally sustainable surface finishing technologies. A recent development based on porous anodised aluminium (PAA) and metal nanowire deposits is presented here, which may become a competitive alternative to paint and organic coatings. Anodising and electrodeposition do not emit VOCs and are less energy intensive. By controlling the conditions for anodising and metal electrodeposition, coatings in a wide spectrum of colours can be produced, including greys, black, blues, purples, and greens. Characterisation of the coating morphologies and corresponding colours agrees with simulated results based on the Fresnel equations and Bruggeman Mixed Media Approximations.
Effects of the Carbon Fiber Orientations for the Strengthening of Thin-Walled Steel Cylinders under Compressive Loads and Bending Shear Loads
Authors: Nhut P V , Matsumoto Y , Matsui T , Nakamura H
Published: February 2021

In this study, the effects of carbon fiber orientations on the strengthening of small-scale thin-walled steel cylinders (TSCs) under axial compression were experimentally and numerically investigated. Besides, the strengthening effects of various types of carbon fiber reinforced polymers (CFRPs) on the load-carrying capacity of full-scale TSCs were numerically investigated. The results showed that circumferential CFRP layers (0°) have significant effects on the increased load-carrying capacity of TSCs under axial compression, whereas, only 90° CFRP layers had small strengthening effects for TSCs under axial compression. When the TSCs subjected to bending shear loads with high values of internal pressures, the appearances of circumferential fibers also brought better strengthening effects than only the angled fibers for TSCs.
2DEG and 2DHG in NaTaO3 polar thin films: thickness and strain dependency
Authors: Portugal Guilherme Ribeiro , Teodoro Arantes Jeverson
Published: February 2021

Two-dimensional (2D) carrier gases in perovskite surfaces and interfaces have been intensely studied since their properties are attractive to many functional devices and applications. Here, we demonstrate through ab initio DFT calculations that surface 2D carries gases can be found in NaTaO3 ultrathin films. Furthermore, we show the thickness dependence of such phenomenon and how it can be tuned when biaxial in-plane strain is applied. Tensile does not alter the valence and conduction character of the films but promotes 2D electron and hole gases in the (TaO2)+ and (NaO)− surfaces, respectively. Because of the competition between surface and strain effects to deal with the cleavage-induced polarity, biaxial compression is able to generate 2D hole gases in the (TaO2)+ surface instead. Such carrier-type and layer switching are explained through changes in the electrostatic potential balancing along the [001] direction and (Na,Ta) cations displacements. The presented results concern not only nanoelectronics but also catalytic applications where modulating bandgap and valence/conduction states is desired.
Invited Commentary: Treatment Drop-in—Making the Case for Causal Prediction
Authors: Sperrin Matthew , Diaz-Ordaz Karla , Pajouheshnia Romin
Published: February 2021

Clinical prediction models (CPMs) are often used to guide treatment initiation, with individuals at high risk offered treatment. This implicitly assumes that the probability quoted from a CPM represents the risk to an individual of an adverse outcome in absence of treatment. However, for a CPM to correctly target this estimand requires careful causal thinking. One problem that needs to be overcome is treatment drop-in: where individuals in the development data commence treatment after the time of prediction but before the outcome occurs. In this issue of the Journal, Xu et al. (Am J Epidemiol. 2021;190(10):2000–2014) use causal estimates from external data sources, such as clinical trials, to adjust CPMs for treatment drop-in. This represents a pragmatic and promising approach to address this issue, and it illustrates the value of utilizing causal inference in prediction. Building causality into the prediction pipeline can also bring other benefits. These include the ability to make and compare hypothetical predictions under different interventions, to make CPMs more explainable and transparent, and to improve model generalizability. Enriching CPMs with causal inference therefore has the potential to add considerable value to the role of prediction in healthcare.
Brain Volumes in Mice are Smaller at Birth After Term or Preterm Cesarean Section Delivery
Authors: Chiesa Morgane , Rabiei Hamed , Riffault Baptiste , Ferrari Diana Carolina , Ben-Ari Yehezkel
Published: February 2021

The rate of cesarean section (CS) delivery has steadily increased over the past decades despite epidemiological studies reporting higher risks of neonatal morbidity and neurodevelopmental disorders. Yet, little is known about the immediate impact of CS birth on the brain, hence the need of experimental studies to evaluate brain parameters following this mode of delivery. Using the solvent clearing method iDISCO and 3D imaging technique, we report that on the day of birth, whole-brain, hippocampus, and striatum volumes are reduced in CS-delivered as compared to vaginally-born mice, with a stronger effect observed in preterm CS pups. These results stress the impact of CS delivery, at term or preterm, during parturition and at birth. In contrast, cellular activity and apoptosis are reduced in mice born by CS preterm but not term, suggesting that these early-life processes are only impacted by the combination of preterm birth and CS delivery.
Mitral valve prolapse: American versus European guidelines - which one is better
Authors: Brito J , Rigueira J , Rodrigues T , Aguiar-Ricardo I , Santos R , Nunes-Ferreira A , Cunha N , Pereira S , Antonio PS , Morais P , Alves Silva P , Valente Silva B , Pinto FJ , Almeida AG
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Introduction

According to the most recent recommendations of AHA, mitral valve prolapse (MVP) is defined as systolic displacement of the mitral leaflet into the left atrium (LA) of at least 2 mm from the mitral annular plane. The ESC recommendations define MVP, flail and billowing, according to the location of the leaflet tips in relation to the coaptation plan. Differences in outcomes considering these classifications are not established.

Purpose

To evaluate the differences in clinical presentation and outcomes of MVP considering AHA and ESC classifications.

Methods

Single-center retrospective study of consecutive patients with MVP (defined according to the AHA classification) documented in transthoracic echocardiogram between January 2014 and October 2019. Demographic, clinical, echocardiographic and electrocardiographic data were collected. The results were obtained using Chi-square and ANOVA tests.

Results

We included 247 patients (mean age 62.9 ± 18 years, 61% males) according to AHA classification; considering the ESC classification: 147 (59%) had prolapse, 30 (12%) flail and 67 (39%) billowing.

In comparison to patients with flail and billowing, patients with MVP had less cordae rupture (p = 0.02). Prolapse was associated with better survival (p = 0.037) and was an independent predictor of survival (OR = 0.372, CI95% [0.148-0.935], p = 0.035) Patients with flail were older in comparison to the ones with prolapse and billowing (71 ± 14 vs 63 ± 17 vs 60 ± 21 years, respectively, p = 0.022). Patients with flail were mostly men (80%, p = 0.028), with more significant mitral regurgitation (p = 0.003) and higher NYHA class (p = 0.018). They also had higher systolic pulmonary artery pressure (SPAP) (48 ± 23 vs 38 ± 18 vs 36 ± 12mmHg, p = 0.015) and higher values of LV mass and posterior wall thickness (144 ±32 vs 125 ± 44 vs 114 ± 37g/m2, p = 0.005 and 11 ± 1,5 vs 10 ± 1,7 vs 9 ± 1.9 mm, p = 0.009, respectively). Women had more billowing (p = 0.04) than prolapse and flail.

Conclusion

The ESC classification adds information to the AHA classification in what concerns to clinical presentation and prognosis of mitral valve prolapse, so both classifications should be used in daily practice.
Echocardiographic features and behavior of cardiac structural abnormalities in mucopolysaccharidosis
Authors: Saba S , Al Sergani A , Vriz O , Kholaif N , Ramzan K , Jawad Shah S , Ahmad O , Albayyat R , Di Michele S , Pergola V , Di Giannuario G , Elmahi I , Ibrahim S , Galzerano D , Di Salvo G
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Mucopolysaccharidosis (MPS) is a rare genetic lysosomal storage disorder with a wide variability of phenotype. A systematic descriptive study dealing with the echocardiographic (E) features of valvular involvement and their evolution over the time in adolescent and adult patients, whose number is growing up in adult echocardiographic laboratory, is lacking in the medical literature.

Purpose

To detect the E features of valvular involvement and their evolution in adolescent and adult patients.

Method

Study design: observational descriptive retrospective. Study group: 142 E studies in 17 adolescent and adult patients with diagnosis of MPS from 2001 until 2020. Mitral (M), aortic (A), tricuspid (T) valves (V) E features (thickness, mobility, calcification, and function), their evolution over the time and the behaviour with Enzyme replacement therapy (ERT) or bone marrow transplant (BMT) were assessed.

Result

52% male, mean age 21 yrs ranges 16 to 48 yrs. 5% of the patient had MPS type I, 11% MPS type II, 29% MPS type IV, and 52% MPS type VI. 70% received ERT and 11% BMT.

In the severe case all the valves were involved (panel A, B, C; white arrows point to valve leaflets; yellow arrows MV apparatus) the whole MV apparatus was involved since the earlier stage and in the latest stage the calcification was massive (panel C). The predominant valvular dysfunction was the regurgitation followed by mixed disorder while the most frequent severe lesion was the stenosis; the echocardiographic pattern differs from the classical hockey stick appearance of the early phase of rheumatic MV and the thickening is different from the myxomatous MV for the reduced mobility and the presence of calcification. The reduced mobility of the TV (panel C) also differs from the Loeffler syndrome because of the restriction of the leaflets and the association with thickening and calcification. Under treatment, the MV thickening was found to have a slow progression of less than 1 mm yearly in 61% cases.

Conclusion

Our results showed that all the valves are affected mainly the MV; the echocardiographic pattern of MPS, different from other valvular diseases of adolescent and adult age, can help in avoiding misdiagnose. Our observations also suggest that the cardiac involvement show slow rate of progression after the initiation of the therapy. Further studies are required to confirm our results.

Type of valve % of valve thickness % of reduced mobility % calcification diffuse % valve lesion Mitral valve 88% 65% 47% 75% Aortic valve 76% 23% 41% 57% Tricuspid valve 82% 47% 17% 52% Abstract Figure. Echocardiographic features
Presence and significance of mid-systolic notch on right ventricular outflow tract velocity envelopes in pulmonary hypertension due to heart failure
Authors: Chiba Y , Iwano H , Murayama M , Kaga S , Motoi K , Ishizaka S , Tsujinaga S , Kamiya K , Nagai T , Anzai T
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background

 A mid-systolic notch (MSN) of the right ventricular outflow tract (RVOT) pulsed-wave Doppler envelope, which is recognized as a characteristic finding in pre-capillary pulmonary hypertension (PH), is often observed in heart failure (HF) patients. However, clinical significance of MSN formation in HF has not been elucidated.

Methods

 Consecutive 233 HF patients who underwent right heart catheterization and echocardiography within 24 hours were enrolled. Isolated post-capillary PH (IpcPH) was defined as mean pulmonary arterial pressure (mPAP) >20 mmHg, mean pulmonary artery wedge pressure (mPAWP) >15 mmHg, and pulmonary vascular resistance (PVR) <3 Wood units and combined pre- and post-capillary PH (CpcPH) was as mPAP >20 mmHg, mPAWP >15 mmHg, and PVR ≥3 Wood units. Pulmonary arterial capacitance (PAC) was calculated as stroke volume / pulmonary arterial pulse pressure [mL/mmHg]. MSN was defined as formation of notch within first half of the RVOT pulsed-wave Doppler envelope.

Results

 Prevalence of IpcPH, CpcPH, and without PH were 87 (37%), 45 (19%), and 101 (43%), respectively and MSN was observed in 8 (9%) of IpcPH, 17 (38%) of CpcPH, and 1 (1%) of patients without PH. Among the hemodynamic and echocardiographic parameters, mPAP and PAC independently determined occurrence of MSN in all the multivariable models (Table). Interestingly, when the PH patients were dimidiated according to median PAC (3.2 mL/mmHg), 25 out of 102 PH patients (25%) with low PAC showed MSN whereas any of PH patients with high PAC did not (Figure).

Conclusion

 MSN was frequently observed in HF patients showing CpcPH. Combination of elevated pressure and reduced compliance of the pulmonary circulation could determine occurrence of MSN in HF.

Determinants of MSN occurrence Univariable analysis Multivariable analysis Model 1 Model 2 Model 3 Model 4 variables OR (95% CI) p OR (95% CI) p OR (95% CI) p OR (95% CI) p OR (95% CI) p LV ejection fraction 0.97 (0.94-0.99) 0.007 1.00 (0.96-1.03) 0.795 LV mass index 1.00 (1.00-1.02) 0.143 PAW pressure 1.13 (1.08-1.18) <0.001 0.92 (0.82-1.03) 0.135 Mean PA pressure 1.14 (1.09-1.19) <0.001 1.08 (1.02-1.14) 0.006 1.15 (1.04-1.27) 0.004 1.08 (1.00-1.17) 0.030 1.07 (1.01-1.14) 0.025 Mean RA pressure 1.14 (1.06-1.22) <0.001 1.00 (0.90-1.11) 0.978 Pulmonary vascular resistance 1.97 (1.45-2.67) <0.001 1.20 (0.88-1.63) 0.225 Pulmonary arterial capacitance 0.27 (0.15-0.48) <0.001 0.49 (0.26-0.92) 0.010 0.44 (0.23-0.85) 0.004 0.47 (0.24-0.93) 0.011 0.49 (0.26-0.93) 0.011 Abstract Figure.
Circulating biomarkers of cardiac fibrosis: do they correlate with the echocardiographic parameters of the myocardial mechanics in systemic sclerosis?
Authors: Vertes V , Tokes-Fuzesi M , Porpaczy A , Nogradi A , Czirjak L , Komocsi A , Faludi R
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background

In systemic sclerosis (SSc) myocardial fibrosis contributes to the impairment of the myocardial function resulting in manifest diastolic and subclinical systolic dysfunction of the left ventricle (LV) and impaired left atrial (LA) function. The pathophysiology of this connective tissue disease is still not fully elucidated. Recently, however, elevated serum levels of galectin-3 and soluble suppression of tumorigenicity 2 (sST2) have been reported in SSc patients suggesting that these fibrotic markers may participate in the fibrotic process in this disease. Thus we aimed to investigate the potential associations between galectin-3 and sST2 levels and the echocardiographic markers of the LV and LA function in SSc patients.

Methods

Forty patients (57.3 ± 13.7 years, 36 female) were enrolled into the study. In addition to the conventional echocardiography, tissue Doppler and speckle-tracking-derived strain techniques were used to estimate the LV systolic and diastolic function as well as the LA size and function. To assess the correlations between galectin-3 and sST2 levels and the echocardiographic variables, partial correlation method was used with age as correcting factor.

Results

In age adjusted analysis galectin-3 level showed significant correlation with LV global longitudinal strain (r = 0.460, p = 0.005); grade of LV diastolic dysfunction (r = 0.394, p = 0.013); septal e’ (r=-0.369, p = 0.021); septal E/e’ (r = 0.380, p = 0.017) and with the grade of mitral regurgitation (r = 0.323, p = 0.048) (Figure 1). No significant correlation was found between sST2 levels and the echocardiographic variables.

Conclusions

Galectin-3 levels, but not sST2 levels show significant correlation with the parameters of the LV diastolic function and with LV global longitudinal strain, a parameter reflecting the subclinical impairment of the LV systolic function. Galectin-3 may be a useful biomarker for identifying SSc patients with high risk for cardiac involvement.

Abstract Figure 1
The prediction of atrial fibrillation development in patients treated with transcatheter aortic valve implantation
Authors: Karakulak UN , Sahiner ML , Sener YZ , Kaya EB , Aytemir K
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Backround

Atrial fibrillation (AF) is associated with poor outcomes after transcatheter aortic valve implantation (TAVI). 

Purpose

This study aimed to investigate whether prolonged total atrial conduction time (PA-TDI) predicts the development of AF in TAVI-treated patients. 

Methods

A total of 307 TAVI-treated patients were enrolled. PA-TDI was defined as the duration from P wave onset on electrocardiography to peak A′ wave on tissue Doppler imaging echocardiography. 

Results

The study was conducted with 263 patients because 44 patients had pre-existing AF. Of 263, 47 (17.8%) had new-onset AF after TAVI procedure. Age, mortality and the frequency of PM implantation were higher in the AF group. LVEDD, LVEF, aortic gradients, and AVA were similar between AF and sinus rhythm groups; however, LVESD, LA diameter, and PA-TDI duration were increased in the AF group. In Kaplan–Meier analysis (Panel A), there was an increase in risk of AF with each incremental percentile of the PA-TDI duration. In multivariate analysis, age (p = 0.005) and PA-TDI duration (p = 0.002) were found to be independent risk factors for the development of AF after TAVI. AUC was 0.630 (p = 0.005), and the sensitivity and specificity were 70% and 51% respectively at a cut-off point of 123.5 ms for PA-TDI duration (Panel B). 

Conclusion

In patients treated with TAVI, post-procedural new-onset AF may lead to significant risk for morbidity and mortality. PA-TDI duration can be used for the detection of the patients with high risk of AF development.

Total (n = 263) Sinus (n = 216) AF (n = 47) p value Age (years) 78.0 ± 10.8 77.5 ± 11.2 80.6 ± 8.4 0.032 Gender (F/M) 144/119 118/98 26/21 0.932 Follow-up time (months) 2 [1-77] 2 [1-77] 1 [1-51] 0.095 Death 82 (31.2%) 59 (27.3%) 23 (48.9%) 0.004 Pacemaker implantation 44 (16.7%) 32 (14.8%) 12 (25.5%) 0.075 LV end-diastolic diameter (mm) 48.2 ± 3.5 47.9 ± 5.3 49.3 ± 5.4 0.202 LV end-systolic diameter (mm) 32.2 ± 5.5 31.7 ± 5.0 35.0 ± 6.8 0.030 LV ejection fraction (%) 55.2 ± 10.9 55.4 ± 10.9 54.2 ± 11.1 0.515 LA diameter (mm) 42.9 ± 6.5 41.9 ± 6.6 44.7 ± 6.1 0.049 Peak aortic gradient (mmHg) 78.6 ± 20.5 79.2 ± 20.5 77.2 ± 20.7 0.660 Mean aortic gradient (mmHg) 46.8 ± 13.5 46.6 ± 13.2 47.2 ± 14.3 0.838 Aortic valve area (cm2) 0.73 ± 0.15 0.73 ± 0.15 0.74 ± 0.14 0.734 PA-TDI duration (ms) 127.0 ± 26.7 125.4 ± 26.2 137.0 ± 27.2 0.009 Abstract Figure.
Heterogeneous pattern of improvement in right ventricular mechanics following hematopoietic stem cell transplant in patients with systemic sclerosis
Authors: Chen C , Nishtala A , Groenendyk JW , Schultz WM , Li E , Shah SJ , Burt RK , Freed BH
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Introduction

Systemic sclerosis (SSc) is an autoimmune disorder that causes fibrosis in the skin and internal organs, including the heart. Patients with SSc can have right ventricular (RV) systolic dysfunction in the absence of pulmonary hypertension. Studies have shown a predilection for impairment of the mid and apical segments of the RV free wall compared to controls. The effect of hematopoietic stem cell transplant (HSCT) – a disease modifying treatment for SSc – on RV mechanics is not known.

Aim

To study the effect of HSCT on RV mechanics using speckle-tracking echocardiography.

Methods

Patients with SSc who underwent comprehensive 2D echocardiographic evaluation pre- and post-HSCT were identified. The modified Rodnan skin score (mRSS) was evaluated for each patient pre- and post-HSCT. Speckle tracking software was utilized to measure myocardial strain (TomTec, Unterschleissheim, Germany). RV strain was measured from the RV focused apical 4-chamber view. Paired student’s t-test and linear regression analysis were used in data analysis.

Results

Among 89 patients with SSc (average age 46 ± 11 years, 75% female) who underwent HSCT, the mRSS significantly improved after HSCT. The mean pulmonary arterial pressure measured by right heart catheterization prior to HSCT was 18.5 ± 4.5 mmHg. There was a significant improvement in RV global longitudinal strain (GLS) and free wall strain (FWS) following HSCT. The improvement in strain was significant in the mid and apical segments of the RV free wall, but not so in the basal segment. The change in RV strain was linearly related to pre-HSCT strain. The lower the RV GLS and FWS, the greater the improvement in strain after HSCT.

Conclusions

There was a significant improvement in RV strain in patients undergoing HSCT, specifically within the mid and apical segments of the RV free wall. The improvement in strain after HSCT was directly related to the baseline strain. This suggests that HSCT may directly improve RV mechanics with the preferential enhancement of the less robust mid and apical RV free wall segments.

Key clinical and echo characteristics Pre-HSCT Post-HSCT P value Median mRSS (25th - 75th percentile) 20 (13-34) 9 (4-20) <0.01 RV GLS (%) -18.13 ± 3.88 -20.06 ± 4.51 <0.01 RV FWS (%) -20.79 ± 5.30 -23.21 ± 5.61 <0.01 RV basal free wall (%) -27.97 ± 9.33 -27.84 ± 7.94 0.93 RV mid free wall (%) -20.68 ± 9.61 -23.75 ± 7.91 0.05 RV apical free wall (%) -15.26 ± 8.57 -20.84 ± 8.92 <0.01 All values are presented as mean ± SD unless indicated otherwise. Abstract Figure. Pre-HSCT RV strain vs change in strain