bluuebunny/crossref_metadata_2025 huggingface dataset:
Die COVID-19 Pandemie und ihre Folgen für die Plastische Chirurgie und Handchirurgie
Authors: Giunta Riccardo E. , Frank Konstantin , Ehrl Denis , Schenck Thilo L. , Moellhoff Nicholas , Braig David , Haas Elisabeth M. , Ahmad Nura , Hagen Christine S. , Wiggenhauser Paul Severin , Frick Andreas , Koban Konstantin , Wachtel Nikolaus , Taha Sara
Published: April 2020

In Deutschland wurde der erste Patient mit SARS-Cov-2 Virus Infektion am 27. Januar 2020 in München bestätigt. Für uns als Plastische Chirurgen und Handchirurgen ist es von zentralerBedeutung, dass wir uns als verantwortungsbewusste Menschen und Ärzte dafür einsetzen, die Übertragung von Viren zu verringern und die Ressourcen zur Behandlung von Patienten, die an der Krankheit schwer erkrankt sind, frei geben. Die vorliegende Arbeit gibt einer Übersicht zu aktuellen Entwicklungen und Erkenntnissen für das Fachgebiet Plastische Chirurgie und für die Handchirurgie.

Gleichzeitig müssen wir über unsere Fachgesellschaften aktiv Kriterien und Regularien zur Versorgung von an COVID-19 erkrankten Patienten mitgestalten, den Erhalt unserer Notfallversorgung sichern und sinnvolle Exit-Strategien erarbeiten. Naturgemäß kann dabei gerade bei der rasanten Entwicklung der Erkenntnisse in der aktuellen Pandemie nur eine Momentaufnahme gegeben werden.
Learning Transanal Total Mesorectal Excision
Authors: McLemore Elisabeth C. , Lavi Peyman , Attaluri Vikram
Published: April 2020

A dynamic evolution is occurring in transanal surgery. Transanal techniques began with intraluminal surgical removal of rectal masses and have progressed to transanal total mesorectal excision (taTME) for rectal cancer. TaTME was first performed in 2009 by Sylla, Rattner, Delgado, and Lacy. This article documents the training pathway followed by pioneers in the taTME technique as well as consensus reports outlining the process of learning the taTME technique. A literature search was performed for taTME training, learning, and technique. Key elements in learning the taTME technique include appropriate indications, cadaver training, and outcomes reporting such as participating in a taTME registry. Consensus reports also agree on the following facets associated with improved outcomes: (1) appropriate case selection of mid and low rectal cancers, (2) prerequisite completion of an accredited training program in laparoscopic colorectal surgery and prior experience in transanal endoscopic surgery, (3) a two-team taTME approach from above and below is ideal, and (4) higher rectal cancer volume surgical practice. The unifying international recommendation for surgeons interested in learning the taTME technique conveys the following message: taTME is an advanced and complex technique that requires dedicated training and experience in TME surgery.
Anatomical Considerations and Procedure-Specific Aspects Important in Preventing Operative Morbidity during Transanal Total Mesorectal Excision
Authors: Atallah Sam
Published: April 2020

As transanal total mesorectal excision (taTME) becomes increasingly utilized, its technical challenges and potential pitfalls have become more clearly appreciated. This chapter explores the differences in how anatomy presents itself from the taTME vantage point as compared with traditional approaches to taTME, and how special problems unique to taTME pose a new set of operative challenges. Morbidity related, specifically, to the technique of taTME is also delineated with particular focus on male urethral injury.
Facile One-Pot Access to α-Diazo-β-ketosulfones from Sulfonyl Chlorides and α-Haloketones
Authors: Krasavin Mikhail , Dar’in Dmitry , Kantin Grigory , Bakulina Olga
Published: April 2020

A convenient one-pot approach to the preparation of α-diazo-β-ketosulfones from sulfonyl chlorides is described. It involves the conversion of the sulfonyl chloride to sodium sulfinate, alkylation of the latter with α-haloketones followed by diazo transfer using the ‘sulfonyl-azide-free’ (‘SAFE’) protocol in aqueous medium. The simple and expedient method relies on readily available starting materials and provides facile access to a wide variety of valuable diazo reagents for organic synthesis.
Structured Neonatal Point-of-Care Ultrasound Training Program
Authors: Kurepa Dalibor , Boyar Vitalya , Zaghloul Nahla , Beachy Joanna , Zaytseva Alla , Teng David , Cooper Rubin , Klewer Scott , Amodio John
Published: April 2020

Objective Point-of-care ultrasound (POC US) has been increasingly used by intensive care physicians. Growing use of POC US necessitates defining distinct clinical indications for its application, as well as structured POC US training programs. Homogeneous approach to POC US education combined with rigorous quality assurance should further enable POC US to become standard-of-care clinical tool. This study aimed to present the first, innovative, and structured POC US program in neonatal–perinatal medicine field. In addition, we reviewed the availability of the POC US training programs across different medical specialties.

Study Design Available English-language publications on POC US training programs in general and neonatal–perinatal medicine were reviewed in this study.

Discussion Mounting body of evidence suggests improved procedural completion rates, as well as clinical decision making with the use of POC US. However, limited research supported the existence of structured, comprehensive POC US programs. It was recognized that medical institutions need to develop syllabuses, teach, and credential increasing number of health care professionals in the use of POC US. We defined intuitive educational strategy that encompasses POC US clinical indications, educational curriculum, scanning protocols, competence evaluation, and finally credentialing process. In addition, we offered description of the imaging quality assurance, as well as POC US coding, and reimbursement.

Conclusion Future efforts need to be dedicated to the ongoing development of neonatal POC US as a clinical instrument. It should allow for eventual paradigm change and improved effectiveness in management of critically ill neonates.
Predictors of Early Preterm Birth Despite Vaginal Progesterone Therapy in Singletons with Short Cervix
Authors: Boelig Rupsa C. , Naert Mackenzie N. , Fox Nathan S. , Hennessy Sean , Chervoneva Inna , Berghella Vincenzo , Roman Amanda
Published: April 2020

Objective This study aimed to identify the incidence of and risk factors for early preterm birth (PTB) (delivery <34 weeks) in women without prior PTB and current short cervix (≤20 mm) prescribed vaginal progesterone.

Study Design Retrospective cohort study of singletons without prior PTB diagnosed with short cervix (≤20 mm) between 180/7 and 236/7 weeks. Women who accepted vaginal progesterone and had delivery outcomes available were included. Demographic/obstetric history, cervical length, and pregnancy characteristics compared between women with early PTB versus delivery ≥34 weeks. Multiple logistic regression analysis used to identify predictors; odds ratio for significant factors used to generate a risk score. Risk score and risk of early PTB assessed with receiver operating characteristic curve (ROCC). Perinatal outcomes compared by risk score.

Results Among 109 patients included, 29 (27%) had a spontaneous PTB <34 weeks. In univariate analysis, only gestational age at ultrasound, presence funneling, and mean cervical length were significantly different between those with and without early sPTB. With multiple logistic regression analysis, only gestational age at diagnosis (odds ratio [OR]: 0.66; 95% confidence interval [CI]: 0.46–0.96; p = 0.028) and index cervical length (OR: 0.84; 95% CI: 0.76–0.93; p = 0.001) remained significantly associated with early PTB. ROCC for the risk score incorporating cervical length and gestational age was predictive of early PTB with an AUC of 0.76 (95% CI: 0.67–0.86; p < 0.001). A high-risk score was predictive of early PTB with a sensitivity of 79%, specificity of 75%, positive predictive value of 54%, and negative predictive value of 91%. Women with a high-risk score had worse perinatal outcomes compared with those with low-risk score.

Conclusion A total of 27% of patients with short cervix prescribed vaginal progesterone will have a sPTB < 34 weeks. Patients at high risk for early PTB despite vaginal progesterone therapy may be identified using gestational age and cervical length at diagnosis of short cervix. Given the narrow window for intervention after diagnosis of short cervix, this has important implications for clinical care.
Adiabatic and non-adiabatic quantum charge and spin pumping in zigzag and armchair graphene nanoribbons
Authors: Bourbour Fatemeh , Esmaeilzadeh Mahdi , Elahi Seyed Mohammad , Eslami Leila
Published: April 2020

We propose a graphene nanoribbon pumping device and study its quantum charge and spin pumping properties for both adiabatic and non-adiabatic regimes by using the Keldysh non-equilibrium Green's function and renormalization procedure. We show that the adiabatic regime is suitable for the generation of high charge current, while the non-adiabatic regime is appropriate for the generation of fully spin polarized and pure spin currents. Also, it is shown that the proposed device can act as a perfect and controllable spin filter. Moreover, we investigate the effects of width and edge of graphene nanoribbons and show that the pumped charge current in the zigzag graphene nanoribbon (ZGNR) strongly depends on nanoribbon width so that the maximum pumped current for width with even numbers of carbon chains is about one order of magnitude larger than that with odd numbers. In contrast with ZGNR, in armchair graphene nanoribbon, the pumped currents with even and odd numbers have the same order of magnitude.
A spherical crystal diffraction imager for Sandia’s Z Pulsed Power Facility
Authors: Ao T. , Schollmeier M. , Kalita P. , Gard P. D. , Smith I. C. , Shores J. E. , Speas C. S. , Seagle C. T.
Published: April 2020

Sandia’s Z Pulsed Power Facility is able to dynamically compress matter to extreme states with exceptional uniformity, duration, and size, which are ideal for investigating fundamental material properties of high energy density conditions. X-ray diffraction (XRD) is a key atomic scale probe since it provides direct observation of the compression and strain of the crystal lattice and is used to detect, identify, and quantify phase transitions. Because of the destructive nature of Z-Dynamic Material Property (DMP) experiments and low signal vs background emission levels of XRD, it is very challenging to detect a diffraction signal close to the Z-DMP load and to recover the data. We have developed a new Spherical Crystal Diffraction Imager (SCDI) diagnostic to relay and image the diffracted x-ray pattern away from the load debris field. The SCDI diagnostic utilizes the Z-Beamlet laser to generate 6.2-keV Mn–Heα x rays to probe a shock-compressed material on the Z-DMP load. A spherically bent crystal composed of highly oriented pyrolytic graphite is used to collect and focus the diffracted x rays into a 1-in. thick tungsten housing, where an image plate is used to record the data.
The design of a line velocity interferometer for any reflector for inertial confinement experiments on the Z-machine
Authors: Datte P. , Baker J. , Bliss D. , Butler N. , Celliers P. , Cohen S. , Crosley M. , Edwards J. , Erskine D. , Fratanduono D. , Frieders G. , Galbraith J. , Hess M. , Johnson D. , Jones M. , LeChien K. , Lusk J. , Myers C. , McCarville T. , McDonald R. , Natoni G. , Olson M. , Raman K. , Robertson G. , Shelton R. , Shores J. , Speas S. , Spencer D. , de Dios E. Vergel , Wong N.
Published: April 2020

A line VISAR (Velocity Interferometer System for Any Reflector) has been designed and commissioned at the Sandia National Laboratory’s Z-machine. The instrument consists of an F/2 collection system, beam transport, and an interferometer table that contains two Mach–Zehnder type interferometers and an eight channel Gated Optical Imaging (GOI) system. The VISAR probe laser operates at the 532 nm wavelength, and the GOI bandpass is 540–600 nm. The output of each interferometer is passed to an optical streak camera with four selectable sweep speeds. The system is designed with three interchangeable optics modules to select a full field of view of 1 mm, 2 mm, or 4 mm. The optical beam transport system connects the target image plane to the interferometers and the gated optical imagers. The target is integrated into a sacrificial final optics assembly that is integral to the transport beamline.
An improved setup for radial diffraction experiments at high pressures and high temperatures in a resistive graphite-heated diamond anvil cell
Authors: Immoor J. , Marquardt H. , Miyagi L. , Speziale S. , Merkel S. , Schwark I. , Ehnes A. , Liermann H.-P.
Published: April 2020

We present an improved setup for the experimental study of deformation of solids at simultaneous high pressures and temperatures by radial x-ray diffraction. This technique employs a graphite resistive heated Mao–Bell type diamond anvil cell for radial x-ray diffraction in combination with a water-cooled vacuum chamber. The new chamber has been developed by the sample environment group at PETRA III and implemented at the Extreme Conditions Beamline P02.2 at PETRA III, DESY (Hamburg, Germany). We discuss applications of the new setup to study deformation of a variety of materials, including ferropericlase, calcium perovskite, bridgmanite, and tantalum carbide, at high-pressure/temperature.
Femtosecond imbalanced time-stretch spectroscopy for ultrafast gas detection
Authors: Zhang Zhen , Xia Haiyun , Yu Saifen , Zhao Lijie , Wei Tianwen , Li Manyi
Published: April 2020

Dual-comb spectroscopy is a promising method for precise optical spectrum analysis with fast data acquisition speed. Here, avoiding using a dual-comb source, femtosecond imbalanced time-stretch spectroscopy with a simple optical layout is proposed and demonstrated. Time-stretch interferometry from one femtosecond laser builds mapping from the optical frequency domain to the radio frequency regime. In experiment, the absorption line of a hydrogen cyanide cell is encoded in the probing arm of a Mach–Zehnder interferometer (MZI). The down-converted radio frequency comb is transformed from a periodically chirped waveform, which is the interferogram of the MZI with different dispersion values on two arms. In a single measurement, the optical frequency comb with a span of 112.5 GHz is down-converted to a range of about 20.8 GHz in the radio frequency domain with a comb spacing equal to the laser repetition frequency of 100 MHz. By turning the optical filter, a spectrum range around 2 THz is analyzed. The acquired optical spectrum resolution is 540 MHz.
Coherent white emission of graphene
Authors: Strek W. , Oleszko M. , Wiewiórski P. , Tomala R. , Hanulia T.
Published: April 2020

The coherence properties of broadband white light emitted by graphene foam after irradiation with intense light of laser diodes were investigated. The interference fringes assigned to spatial and temporal coherence were observed for graphene white-light emission excited by two different excitation wavelengths of 975 nm and 808 nm of laser diodes. Both light sources were spectrally filtered to a narrow bandwidth in order to exclude the effect of temporal coherence. It was found that the coherence degree of white light emission of graphene differs depending on the excitation wavelength; however, no excitation power effect on the coherence degree was observed. The origin of coherence of laser-induced white emission of graphene is the stimulated emission due to the inversion population.
Fracture toughness of sodium aluminosilicate hydrate (NASH) gels: Insights from molecular dynamics simulations
Authors: Lyngdoh Gideon A. , Nayak Sumeru , Kumar Rajesh , Anoop Krishnan N. M. , Das Sumanta
Published: April 2020

This paper evaluates the fracture toughness of sodium aluminosilicate hydrate (N-A-S-H) gel formed through alkaline activation of fly ash via molecular dynamics (MD) simulations. The short- and medium-range order of the constructed N-A-S-H structures shows good correlation with the experimental observations, signifying the viability of the N-A-S-H structures. The simulated fracture toughness values of N-A-S-H (0.4–0.45 MPa m0.5) appear to be of the same order as the available experimental values for fly ash-based geopolymer mortars and concretes. These results suggest the efficacy of the MD simulation toward obtaining a realistic fracture toughness of N-A-S-H, which is otherwise very challenging to obtain experimentally, and no direct experimental fracture toughness values are yet available. To further assess the fracture behavior of N-A-S-H, the number of chemical bonds formed/broken during elongation and their relative sensitivity to crack growth are evaluated. Overall, the fracture toughness of N-A-S-H presented in this paper paves the way for a multiscale simulation-based design of tougher geopolymers.
Effect of indium alloying on the charge carrier dynamics of thick-shell InP/ZnSe quantum dots
Authors: Freymeyer Nathaniel J. , Click Sophia M. , Reid Kemar R. , Chisholm Matthew F. , Bradsher Cara E. , McBride James R. , Rosenthal Sandra J.
Published: April 2020

Thick-shell InP/ZnSe III–V/II–VI quantum dots (QDs) were synthesized with two distinct interfaces between the InP core and ZnSe shell: alloy and core/shell. Despite sharing similar optical properties in the spectral domain, these two QD systems have differing amounts of indium incorporation in the shell as determined by high-resolution energy-dispersive x-ray spectroscopy scanning transmission electron microscopy. Ultrafast fluorescence upconversion spectroscopy was used to probe the charge carrier dynamics of these two systems and shows substantial charge carrier trapping in both systems that prevents radiative recombination and reduces the photoluminescence quantum yield. The alloy and core/shell QDs show slight differences in the extent of charge carrier localization with more extensive trapping observed in the alloy nanocrystals. Despite the ability to grow a thick shell, structural defects caused by III–V/II–VI charge carrier imbalances still need to be mitigated to further improve InP QDs.
Method developed for creating foam-free monodisperse bubbles as ultrasound contrast agents
Authors: Bandari Anashe
Published: April 2020

The efficient creation of uniform, ready-to-use bubbles improves ultrasound imaging sensitivity 15-fold.
Exploring non-equilibrium molecular dynamics of mobile protons in the solid acid CsH2PO4 at the micrometer and microsecond scale
Authors: Dreßler Christian , Kabbe Gabriel , Brehm Martin , Sebastiani Daniel
Published: April 2020

We explicitly compute the non-equilibrium molecular dynamics of protons in the solid acid CsH2PO4 on the micrometer length scale via a multiscale Markov model: The molecular dynamics/matrix propagation (MDM) method. Within the MDM approach, the proton dynamics information of an entire molecular dynamics simulation can be condensed into a single M × M matrix (M is the number of oxygen atoms in the simulated system). Due to this drastic reduction in the complexity, we demonstrate how to increase the length and time scales in order to enable the simulation of inhomogeneities of CsH2PO4 systems at the nanometer scale. We incorporate explicit correlation of protonation dynamics with the protonation state of the neighboring proton sites and illustrate that this modification conserves the Markov character of the MDM method. We show that atomistic features such as the mean square displacement and the diffusion coefficient of the protons can be computed quantitatively from the matrix representation. Furthermore, we demonstrate the application potential of the scheme by computing the explicit dynamics of a non-equilibrium process in an 8 μm CsH2PO4 system during 5 ms.
Enhanced magnetization in proton irradiated Mn3Si2Te6 van der Waals crystals
Authors: Martinez L. M. , Iturriaga H. , Olmos R. , Shao L. , Liu Y. , Mai Thuc T. , Petrovic C. , Hight Walker Angela R. , Singamaneni S. R.
Published: April 2020

van der Waals (vdW) engineering of magnetism is a topic of increasing research interest in the community at present. We study the magnetic properties of quasi-two-dimensional layered vdW Mn3Si2Te6 (MST) crystals upon proton irradiation as a function of fluences of 1 × 1015, 5 × 1015, 1 × 1016, and 1 × 1018 H+/cm2. We find that the magnetization is significantly enhanced by 53  % and 37  % in the ferrimagnetic phase (at 50 K) when the MST crystal was irradiated with the proton fluence of 5 × 1015, both in ab and c planes, respectively. The ferrimagnetic ordering temperature and magnetic anisotropy are retained even after proton irradiation. From the fluence dependence of magnetization, electron paramagnetic resonance spectral parameters (g-value and signal width), and Raman data, we show that the magnetic exchange interactions (Mn–Te–Mn) are significantly modified at this fluence. This work shows that it is possible to employ proton irradiation in tuning the magnetic properties of vdW crystals and provide many opportunities to design desired magnetic phases.
Energy release behavior of Al/PTFE reactive materials powder in a closed chamber
Authors: Xiao Jianguang , Nie Zhengyuan , Wang Zhao , Du Ye , Tang Enling
Published: April 2020

In order to investigate the energy release behavior of Al/polytetrafluoroethylene (Al/PTFE) reactive materials (RMS) more effectively, a closed chamber test system that could simultaneously examine the overpressure and the temperature is designed. The maximum overpressure with the range of 2.18–6.74 MPa and the temperature with the range of 1701–2756 K are obtained for 4–10 g RMS powder in a confined space of 8.8 l. The theoretical calculation is done for the internal energy of air (IEA), internal energy of gas product, internal energy of solid product, pressure potential energy of gas mixture (PPEGM), internal energy of chamber wall (IECW), total released energy (TRE), and specific energy (SE). The energy release events show a distinguished feature at different moments. PPEGM and IEA with a large percentage of SE are the main energy release at the beginning of the events while IECW and IEA play a more important part at the end instead, which corresponds to the energy transfer from PPEGM to IECW in essence. The maximum ratio of PPEGM and IECW to TRE is in the range of 40.76%–58.98% and 45.11%–64.56%, respectively. The obtained SE is very close to the energy content of RMS in theory, indicating that it is a competitive method to evaluate the released energy for RMS. This work is vital to understanding their damage mechanism clearly.
Negligible thermal contributions to the spin pumping signal in ferromagnetic metal–platinum bilayers
Authors: Noël Paul , Cosset-Cheneau Maxen , Haspot Victor , Maurel Vincent , Lombard Christian , Bibes Manuel , Barthelemy Agnès , Vila Laurent , Attané Jean-Philippe
Published: April 2020

Spin pumping by ferromagnetic resonance is one of the most common techniques to determine spin Hall angles, Edelstein lengths, or spin diffusion lengths of a large variety of materials. In recent years, there have been increasing concerns over the interpretation of these experiments, underlining that the signal could arise purely from thermoelectric effects rather than coherent spin pumping. Here, we propose a method to evaluate the presence or absence of thermal effects in spin pumping signals, by combining bolometry and spin pumping by ferromagnetic resonance measurements and comparing their timescale. Using a cavity to perform the experiments on Pt\permalloy and La0.7Sr0.3MnO3\Pt samples, we conclude on the absence at resonance of any measurable thermoelectric contribution such as the spin Seebeck and anomalous Nernst effects.
Large scale and linear scaling DFT with the CONQUEST code
Authors: Nakata Ayako , Baker Jack S. , Mujahed Shereif Y. , Poulton Jack T. L. , Arapan Sergiu , Lin Jianbo , Raza Zamaan , Yadav Sushma , Truflandier Lionel , Miyazaki Tsuyoshi , Bowler David R.
Published: April 2020

We survey the underlying theory behind the large-scale and linear scaling density functional theory code, conquest, which shows excellent parallel scaling and can be applied to thousands of atoms with diagonalization and millions of atoms with linear scaling. We give details of the representation of the density matrix and the approach to finding the electronic ground state and discuss the implementation of molecular dynamics with linear scaling. We give an overview of the performance of the code, focusing in particular on the parallel scaling, and provide examples of recent developments and applications.
Fast transformations between configuration state function and Slater determinant bases for direct configuration interaction
Authors: Fales B. Scott , Martínez Todd J.
Published: April 2020

A hybrid configuration state function (CSF) and Slater determinant (SD) basis full configuration interaction (CI) program was developed to simultaneously take advantage of fast SD basis algorithms for σ = Hc formation and the smaller CI vector length and more robust convergence offered by a CSF basis. Graphical processing unit acceleration of the direct CSF-SD and SD-CSF basis transformation algorithms ensures that the combined transformation time per iteration relative to σ formation is small (∼15%). In addition to the obvious benefits of reducing the memory footprint of the CI vector, additional computational savings are demonstrated that rely directly on the size of the CI basis, in one particular case reducing the CI time-to-solution of a HF-CAS-(16,16)-CI/6-31G calculation of ethylene from 1954.79 s to 956 s by using a CSF basis, a 2.0× speedup.
Subthermionic negative capacitance ion sensitive field-effect transistor
Authors: Bellando Francesco , Dabhi Chetan K. , Saeidi Ali , Gastaldi Carlotta , Chauhan Yogesh S. , Ionescu Adrian M.
Published: April 2020

One of the main advantages of Ion-Sensitive Field-Effect Transistor (ISFET) technology is the capability to exploit technological advancements initially developed for conventional FETs for logic applications, such as the employ of high-k dielectrics for the gate and the definition of fully depleted and gate all around structures. Negative Capacitance (NC) is an emerging concept exploiting ferroelectric materials integrated in field effect transistor gate stacks in order to decrease their subthreshold swing and improve the drain current (ID) overdrive in order to reach more energy efficient devices, operated at lower voltage. In this work, we investigate and experimentally demonstrate the application of this concept to enable subthermionic ISFETs with enhanced current sensitivity and low power operation. A physical model for the introduced NC ISFET is presented and optimized by fitting of the experimental results, providing further insights into the sensor parameters and a predictive tool for the design of future NC-based sensors.
Turbulence characteristics in the wake of a heliostat in an atmospheric boundary layer flow
Authors: Jafari Azadeh , Emes Matthew , Cazzolato Benjamin , Ghanadi Farzin , Arjomandi Maziar
Published: April 2020

The mean and spectral characteristics of turbulence in the wake flow of a flat plate model resembling a heliostat in the atmospheric boundary layer flow are investigated in a wind tunnel experiment. Mean velocity and turbulence kinetic energy were characterized in the wake of a heliostat model at three elevation angles up to a distance of eight times the characteristic dimension of the heliostat panel. An increase in turbulence intensity and kinetic energy was found in the wake flow, reaching a peak at a distance equal to approximately twice the characteristic dimension of the heliostat panel. Furthermore, spectral and wavelet analysis of velocity fluctuations in the wake showed that the dominant mechanism in the immediate downstream of the plate was the breakdown of large inflow turbulence structures to smaller scales. In the end, the wake-induced turbulence patterns and wind loads in a heliostat field were discussed. It was found that compared to a heliostat at the front row, the heliostats positioned in high-density regions of a field were subjected to a higher turbulence intensity and, consequently, larger dynamic wind loading. The results show that it is necessary to consider the increased unsteady wind loads for the design of a heliostat in high-density regions of a field, where the gap between the rows is less than three-times the characteristic length of the heliostat panel.
Studying polymer diffusiophoresis with non-equilibrium molecular dynamics
Authors: Ramírez-Hinestrosa S. , Yoshida H. , Bocquet L. , Frenkel D.
Published: April 2020

We report a numerical study of the diffusiophoresis of short polymers using non-equilibrium molecular dynamics simulations. More precisely, we consider polymer chains in a fluid containing a solute that has a concentration gradient and examine the variation of the induced diffusiophoretic velocity of the polymer chains as the interaction between the monomer and the solute is varied. We find that there is a non-monotonic relation between the diffusiophoretic mobility and the strength of the monomer–solute interaction. In addition, we find a weak dependence of the mobility on the length of the polymer chain, which shows clear difference from the diffusiophoresis of a solid particle. Interestingly, the hydrodynamic flow through the polymer is much less screened than for pressure driven flows.
Estimating geographic subjective well-being from Twitter: A comparison of dictionary and data-driven language methods
Authors: Jaidka Kokil , Giorgi Salvatore , Schwartz H. Andrew , Kern Margaret L. , Ungar Lyle H. , Eichstaedt Johannes C.
Published: April 2020

Researchers and policy makers worldwide are interested in measuring the subjective well-being of populations. When users post on social media, they leave behind digital traces that reflect their thoughts and feelings. Aggregation of such digital traces may make it possible to monitor well-being at large scale. However, social media-based methods need to be robust to regional effects if they are to produce reliable estimates. Using a sample of 1.53 billion geotagged English tweets, we provide a systematic evaluation of word-level and data-driven methods for text analysis for generating well-being estimates for 1,208 US counties. We compared Twitter-based county-level estimates with well-being measurements provided by the Gallup-Sharecare Well-Being Index survey through 1.73 million phone surveys. We find that word-level methods (e.g., Linguistic Inquiry and Word Count [LIWC] 2015 and Language Assessment by Mechanical Turk [LabMT]) yielded inconsistent county-level well-being measurements due to regional, cultural, and socioeconomic differences in language use. However, removing as few as three of the most frequent words led to notable improvements in well-being prediction. Data-driven methods provided robust estimates, approximating the Gallup data at up to
r
= 0.64. We show that the findings generalized to county socioeconomic and health outcomes and were robust when poststratifying the samples to be more representative of the general US population. Regional well-being estimation from social media data seems to be robust when supervised data-driven methods are used.
Amyloid assembly is dominated by misregistered kinetic traps on an unbiased energy landscape
Authors: Jia Zhiguang , Schmit Jeremy D. , Chen Jianhan
Published: April 2020

Atomistic description of protein fibril formation has been elusive due to the complexity and long time scales of the conformational search. Here, we develop a multiscale approach combining numerous atomistic simulations in explicit solvent to construct Markov State Models (MSMs) of fibril growth. The search for the in-register fully bound fibril state is modeled as a random walk on a rugged two-dimensional energy landscape defined by β-sheet alignment and hydrogen-bonding states, whereas transitions involving states without hydrogen bonds are derived from kinetic clustering. The reversible association/dissociation of an incoming peptide and overall growth kinetics are then computed from MSM simulations. This approach is applied to derive a parameter-free, comprehensive description of fibril elongation of Aβ
16–22
and how it is modulated by phenylalanine-to-cyclohexylalanine (CHA) mutations. The trajectories show an aggregation mechanism in which the peptide spends most of its time trapped in misregistered β-sheet states connected by weakly bound states twith short lifetimes. Our results recapitulate the experimental observation that mutants CHA19 and CHA1920 accelerate fibril elongation but have a relatively minor effect on the critical concentration for fibril growth. Importantly, the kinetic consequences of mutations arise from cumulative effects of perturbing the network of productive and nonproductive pathways of fibril growth. This is consistent with the expectation that nonfunctional states will not have evolved efficient folding pathways and, therefore, will require a random search of configuration space. This study highlights the importance of describing the complete energy landscape when studying the elongation mechanism and kinetics of protein fibrils.
Diachronous development of Great Unconformities before Neoproterozoic Snowball Earth
Authors: Flowers Rebecca M. , Macdonald Francis A. , Siddoway Christine S. , Havranek Rachel
Published: April 2020

Significance

Erosion below the Great Unconformity has been interpreted as a global phenomenon associated with Snowball Earth. Geological relationships and thermochronologic data provide evidence that the bulk of erosion below the Great Unconformity in Colorado occurred prior to Cryogenian glaciation. We suggest that there are multiple, regionally diachronous Great Unconformities that are tectonic in origin.
Aseismic transient slip on the Gofar transform fault, East Pacific Rise
Authors: Liu Yajing , McGuire Jeffrey J. , Behn Mark D.
Published: April 2020

Oceanic transform faults display a unique combination of seismic and aseismic slip behavior, including a large globally averaged seismic deficit, and the local occurrence of repeating magnitude (M)∼6earthquakes with abundant foreshocks and seismic swarms, as on the Gofar transform of the East Pacific Rise and the Blanco Ridge in the northeast Pacific Ocean. However, the underlying mechanisms that govern the partitioning between seismic and aseismic slip and their interaction remain unclear. Here we present a numerical modeling study of earthquake sequences and aseismic transient slip on oceanic transform faults. In the model, strong dilatancy strengthening, supported by seismic imaging that indicates enhanced fluid-filled porosity and possible hydrothermal circulation down to the brittle–ductile transition, effectively stabilizes along-strike seismic rupture propagation and results in rupture barriers where aseismic transients arise episodically. The modeled slow slip migrates along the barrier zones at speeds∼10 to 600 m/h, spatiotemporally correlated with the observed migration of seismic swarms on the Gofar transform. Our model thus suggests the possible prevalence of episodic aseismic transients in M∼6rupture barrier zones that host active swarms on oceanic transform faults and provides candidates for future seafloor geodesy experiments to verify the relation between aseismic fault slip, earthquake swarms, and fault zone hydromechanical properties.
Heart–brain interactions shape somatosensory perception and evoked potentials
Authors: Al Esra , Iliopoulos Fivos , Forschack Norman , Nierhaus Till , Grund Martin , Motyka Paweł , Gaebler Michael , Nikulin Vadim V. , Villringer Arno
Published: April 2020

Significance

Our brain continuously receives signals from the body and the environment. Although we are mostly unaware of internal bodily processes, such as our heartbeats, they can affect our perception. Here, we show two distinct ways in which the heartbeat modulates conscious perception. First, increased heartbeat-evoked neural activity before stimulation is followed by decreased somatosensory detection. This effect can be explained by subjects adopting a more conservative decision criterion, which is accompanied by changes in early and late somatosensory-evoked responses. Second, stimulus timing during the cardiac cycle affects sensitivity but not criterion for somatosensory stimuli, which is reflected only in late somatosensory-evoked responses. We propose that these heartbeat-related modulations are connected to fluctuations of interoceptive attention and (unconscious) predictive coding mechanisms.
Global control of bacterial nitrogen and carbon metabolism by a PTS
Ntr
-regulated switch
Authors: Sánchez-Cañizares Carmen , Prell Jürgen , Pini Francesco , Rutten Paul , Kraxner Kim , Wynands Benedikt , Karunakaran Ramakrishnan , Poole Philip S.
Published: April 2020

Significance

Bacteria have evolved intricate regulatory networks to coordinate their metabolism with internal and external signals of their status. The regulatory phosphotransferase systems (PTSs) constitute a key part of these intricate circuits, with their signal transduction cascades participating in multiple regulatory functions. Although two major systems have been described as being involved in regulating carbon and nitrogen pools, there is very little information on their physiological role in vivo under real-time conditions. In this work we demonstrate the role of PTS as an integrated system, widely conserved in proteobacteria, acting as a complex biological sensor-actuator device enabling bacterial cells to posttranslationally alter bacterial physiology and balance carbon and nitrogen availability.
Neonatal CSF vasopressin concentration predicts later medical record diagnoses of autism spectrum disorder
Authors: Oztan Ozge , Garner Joseph P. , Constantino John N. , Parker Karen J.
Published: April 2020

Significance

Autism is a poorly understood brain disorder of childhood onset. It is characterized by social impairments and diagnosed behaviorally. Early diagnosis fosters better developmental outcomes through behavioral intervention. However, long clinic wait times to undergo behavioral evaluation contribute to delayed diagnoses and treatments. Emerging evidence indicates that low cerebrospinal fluid concentration of the “social” neuropeptide vasopressin is a marker of social impairment in children with autism. Here we report that cerebrospinal fluid vasopressin concentration is significantly lower in newborns diagnosed with autism later in childhood. These preliminary findings suggest that a biomarker of autism may be present before behavioral symptoms emerge. If replicated, this approach could be useful for assessing autism risk and facilitating early intervention in high-risk individuals.
Airfoil-like mechanics generate thrust on the anterior body of swimming fishes
Authors: Lucas Kelsey N. , Lauder George V. , Tytell Eric D.
Published: April 2020

The anterior body of many fishes is shaped like an airfoil turned on its side. With an oscillating angle to the swimming direction, such an airfoil experiences negative pressure due to both its shape and pitching movements. This negative pressure acts as thrust forces on the anterior body. Here, we apply a high-resolution, pressure-based approach to describe how two fishes, bluegill sunfish (Lepomis macrochirusRafinesque) and brook trout (Salvelinus fontinalisMitchill), swimming in the carangiform mode, the most common fish swimming mode, generate thrust on their anterior bodies using leading-edge suction mechanics, much like an airfoil. These mechanics contrast with those previously reported in lampreys—anguilliform swimmers—which produce thrust with negative pressure but do so through undulatory mechanics. The thrust produced on the anterior bodies of these carangiform swimmers through negative pressure comprises 28% of the total thrust produced over the body and caudal fin, substantially decreasing the net drag on the anterior body. On the posterior region, subtle differences in body shape and kinematics allow trout to produce more thrust than bluegill, suggesting that they may swim more effectively. Despite the large phylogenetic distance between these species, and differences near the tail, the pressure profiles around the anterior body are similar. We suggest that such airfoil-like mechanics are highly efficient, because they require very little movement and therefore relatively little active muscular energy, and may be used by a wide range of fishes since many species have appropriately shaped bodies.
High-speed interferometric imaging reveals dynamics of neuronal deformation during the action potential
Authors: Ling Tong , Boyle Kevin C. , Zuckerman Valentina , Flores Thomas , Ramakrishnan Charu , Deisseroth Karl , Palanker Daniel
Published: April 2020

Neurons undergo nanometer-scale deformations during action potentials, and the underlying mechanism has been actively debated for decades. Previous observations were limited to a single spot or the cell boundary, while movement across the entire neuron during the action potential remained unclear. Here we report full-field imaging of cellular deformations accompanying the action potential in mammalian neuron somas (−1.8 to 1.4 nm) and neurites (−0.7 to 0.9 nm), using high-speed quantitative phase imaging with a temporal resolution of 0.1 ms and an optical path length sensitivity of <4 pm per pixel. The spike-triggered average, synchronized to electrical recording, demonstrates that the time course of the optical phase changes closely matches the dynamics of the electrical signal. Utilizing the spatial and temporal correlations of the phase signals across the cell, we enhance the detection and segmentation of spiking cells compared to the shot-noise–limited performance of single pixels. Using three-dimensional (3D) cellular morphology extracted via confocal microscopy, we demonstrate that the voltage-dependent changes in the membrane tension induced by ionic repulsion can explain the magnitude, time course, and spatial features of the phase imaging. Our full-field observations of the spike-induced deformations shed light upon the electromechanical coupling mechanism in electrogenic cells and open the door to noninvasive label-free imaging of neural signaling.
Collective decision-making by rational agents with differing preferences
Authors: Mann Richard P.
Published: April 2020

Significance

For animals choosing where to forage or sleep, or for humans choosing a restaurant, a hotel, or a career, the choices made by others can provide useful information. If a restaurant is consistently full of customers, we might assume it must be serving good-quality food. However, the choices that others make are only useful to us if they are made by agents with similar preferences; a vegan can learn very little from the popularity of a steak house. In this paper, I show how differences in preferences change how agents should respond to each other to maximize their personal fitness or utility, and thus how population structures might determine the interaction rules that evolve in social groups.
Observation of indentation-induced shear bands in a metal−organic framework glass
Authors: Stepniewska Malwina , Januchta Kacper , Zhou Chao , Qiao Ang , Smedskjaer Morten M. , Yue Yuanzheng
Published: April 2020

Significance

As a newly emerged glass family, the melt-quenched metal−organic framework (MOF) glasses have attracted considerable attention from scientists. Recently, several important breakthroughs have been achieved concerning their structure, glass formation, dynamics, and thermodynamic evolution. However, the fracture behavior of these glasses upon mechanical loading has not yet been reported. Here we obtained a fracture pattern of a MOF glass upon indentation, and revealed anomalous cracking behavior. We detected the occurrence of shear bands with a sliding extent of ∼35 nm. Both the fracture behavior and the deformation mechanism could be associated with the coordinative bonds in ZIFs. This work contributes to obtaining a general picture about the fracture mechanism of brittle glasses.
Cell atlas of aqueous humor outflow pathways in eyes of humans and four model species provides insight into glaucoma pathogenesis
Authors: van Zyl Tavé , Yan Wenjun , McAdams Alexi , Peng Yi-Rong , Shekhar Karthik , Regev Aviv , Juric Dejan , Sanes Joshua R.
Published: April 2020

Increased intraocular pressure (IOP) represents a major risk factor for glaucoma, a prevalent eye disease characterized by death of retinal ganglion cells; lowering IOP is the only proven treatment strategy to delay disease progression. The main determinant of IOP is the equilibrium between production and drainage of aqueous humor, with compromised drainage generally viewed as the primary contributor to dangerous IOP elevations. Drainage occurs through two pathways in the anterior segment of the eye called conventional and uveoscleral. To gain insights into the cell types that comprise these pathways, we used high-throughput single-cell RNA sequencing (scRNAseq). From ∼24,000 single-cell transcriptomes, we identified 19 cell types with molecular markers for each and used histological methods to localize each type. We then performed similar analyses on four organisms used for experimental studies of IOP dynamics and glaucoma: cynomolgus macaque (
Macaca fascicularis
), rhesus macaque (
Macaca mulatta
), pig (
Sus scrofa
), and mouse (
Mus musculus
). Many human cell types had counterparts in these models, but differences in cell types and gene expression were evident. Finally, we identified the cell types that express genes implicated in glaucoma in all five species. Together, our results provide foundations for investigating the pathogenesis of glaucoma and for using model systems to assess mechanisms and potential interventions.
Honey bee virus causes context-dependent changes in host social behavior
Authors: Geffre Amy C. , Gernat Tim , Harwood Gyan P. , Jones Beryl M. , Morselli Gysi Deisy , Hamilton Adam R. , Bonning Bryony C. , Toth Amy L. , Robinson Gene E. , Dolezal Adam G.
Published: April 2020

Anthropogenic changes create evolutionarily novel environments that present opportunities for emerging diseases, potentially changing the balance between host and pathogen. Honey bees provide essential pollination services, but intensification and globalization of honey bee management has coincided with increased pathogen pressure, primarily due to a parasitic mite/virus complex. Here, we investigated how honey bee individual and group phenotypes are altered by a virus of concern, Israeli acute paralysis virus (IAPV). Using automated and manual behavioral monitoring of IAPV-inoculated individuals, we find evidence for pathogen manipulation of worker behavior by IAPV, and reveal that this effect depends on social context; that is, within versus between colony interactions. Experimental inoculation reduced social contacts between honey bee colony members, suggesting an adaptive host social immune response to diminish transmission. Parallel analyses with double-stranded RNA (dsRNA)-immunostimulated bees revealed these behaviors are part of a generalized social immune defensive response. Conversely, inoculated bees presented to groups of bees from other colonies experienced reduced aggression compared with dsRNA-immunostimulated bees, facilitating entry into susceptible colonies. This reduction was associated with a shift in cuticular hydrocarbons, the chemical signatures used by bees to discriminate colony members from intruders. These responses were specific to IAPV infection, suggestive of pathogen manipulation of the host. Emerging bee pathogens may thus shape host phenotypes to increase transmission, a strategy especially well-suited to the unnaturally high colony densities of modern apiculture. These findings demonstrate how anthropogenic changes could affect arms races between human-managed hosts and their pathogens to potentially affect global food security.