bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical Application of Ultrasound in Intensive Care Unit-Acquired Weakness
Authors: Patel Sunil , Bear Danielle , Patel Brijesh , Puthucheary Zudin
Published: April 2020

Intensive care unit-acquired weakness (ICUAW) is common and prolongs the duration of mechanical ventilation and ICU length of stay and is also a leading cause of physical restriction up to five years later. Developing diagnostic tools that allow early identification and risk stratification in all critically ill patients is vital. Ultrasound is a cheap, reproducible and noninvasive imaging modality that can be used to assess multiple muscle groups. It has advantages over other imaging techniques that entail risks of radiation as well as the logistical concerns of moving critically ill patients. Ultrasound muscle indices can be monitored over time and may serve as predictors for ventilatory weaning and long-term outcomes. The diaphragm is frequently perturbed during critical illness, specifically when mechanical ventilation is initiated. Diaphragm thickness and excursion have been shown to support extubation strategy with the former serving as a marker of inspiratory effort in the absence of more specialist tests. The techniques are reproducible with appropriate training and practice and have been applied in clinical trials. Peripheral skeletal muscle ultrasound has been the subject of intense research in ICU-acquired muscle weakness. The technique has also been found to be reproducible and can serve as a surrogate marker to current volitional and non-volitional tests in the assessment of muscle ICUAW. This article outlines the application of musculoskeletal ultrasound and its role in the early recognition of ICUAW in three distinct muscle groups: (1) diaphragm (2) rectus femoris and introduces the potential of (3) parasternal muscles.
Prävention von Schlaganfall und Demenz in der Hausarztpraxis: Evaluation des Projektes INVADE
Authors: Bickel Horst , Block Marc , Gotzler Othmar , Hartmann Julia , Pürner Klaus , Sander Dirk , Förstl Hans
Published: April 2020

Einleitung Schlaganfall und Demenz haben zahlreiche modifizierbare Risikofaktoren gemeinsam. Im hausärztlichen Präventionsprojekt INVADE (INterventionsprojekt VAskuläre Hirnerkrankungen und Demenz im Landkreis Ebersberg) wurden diese vaskulären Risikofaktoren systematisch erfasst und evidenzbasiert behandelt.

Methoden Alle über 50-jährigen Versicherten der AOK Bayern mit Wohnsitz im oberbayerischen Landkreis Ebersberg erhielten das Angebot zur Teilnahme an INVADE, rund 1 Drittel schrieb sich in das Programm ein. Durch hausärztliche Untersuchungen, Selbstauskünfte der Versicherten, Laboranalysen und eine Duplexsonografie der extrakraniellen Halsgefäße wurden individuelle Risikoprofile erstellt, aus denen sich die Interventionsmaßnahmen ableiteten. In jedem Quartal dokumentierten die Hausärzte Behandlung und Gesundheitszustand der Teilnehmer, nach jeweils 2 Jahren wurde das gesamte Untersuchungsprogramm wiederholt. Der Erfolg der Intervention wurde am Landkreis Dachau bemessen, wo die Versicherten die übliche hausärztliche Versorgung erhielten. Als Endpunkte wurden administrative Daten der Kranken- und Pflegekasse für den Zeitraum von 2013 bis 2016 verwendet. Primäre Endpunkte bestanden in der Mortalität und im Eintritt von Pflegebedürftigkeit, sekundäre Endpunkte in den stationären Behandlungen infolge von zerebrovaskulären Erkrankungen.

Ergebnisse Der Vergleich zwischen den Versicherten im Landkreis Ebersberg (n = 10 663) und im Landkreis Dachau (n = 13 225) fiel sowohl in den primären klinischen Endpunkten als auch im kombinierten sekundären Endpunkt zugunsten des Präventionsprogramms aus. Mortalitätsrisiko (HR = 0,90; 95 %-Konfidenzintervall: 0,84–0,97), Pflegebedürftigkeitsrisiko (HR = 0,88; 95 %-KI 0,81–0,96) und die Wahrscheinlichkeit einer stationären Behandlung aufgrund zerebrovaskulärer Erkrankungen (OR = 0,87; 95 %-KI 0,77–0,97) waren signifikant reduziert.

Diskussion Die Ergebnisse stützen die Annahme, dass durch eine intensivierte hausärztliche Identifikation und Behandlung vaskulärer Risikofaktoren das Auftreten von zerebrovaskulären Erkrankungen und Demenzen gesenkt werden kann und sich damit Lebenserwartung und von Pflegebedürftigkeit freie Lebenserwartung erhöhen lassen. Registrierung clinicaltrials.gov, NCT1107548, Registrierungsdatum: 21.04.2010, drks.de, DRKS00 011348, Registrierungsdatum: 29.12.2016
Clinical and Molecular Update on Genetic Causes of Pituitary Adenomas
Authors: Vasilev Vladimir , Daly Adrian F. , Zacharieva Sabina , Beckers Albert
Published: April 2020

Pituitary adenomas are benign tumors with variable functional characteristics that can have a significant impact on patients. The majority arise sporadically, but an inherited genetic susceptibility is increasingly being recognized. Recent advances in genetics have widened the scope of our understanding of pituitary tumorigenesis. The clinical and genetic characteristics of pituitary adenomas that develop in the setting of germline-mosaic and somatic GNAS mutations (McCune–Albright syndrome and sporadic acromegaly), germline MEN1 mutations (multiple endocrine neoplasia type 1), and germline PRKAR1A mutations (Carney complex) have been well described. Non-syndromic familial cases of isolated pituitary tumors can occur as familial isolated pituitary adenomas (FIPA); mutations/deletions of the AIP gene have been found in a minority of these. Genetic alterations in GPR101 have been identified recently as causing X-linked acro-gigantism (X-LAG) leading to very early-onset pediatric gigantism. Associations of pituitary adenomas with other tumors have been described in syndromes like multiple endocrine neoplasia type 4, pheochromocytoma-paraganglioma with pituitary adenoma association (3PAs) syndrome and some of their genetic causes have been elucidated. The genetic etiologies of a significant proportions of sporadic corticotropinomas have recently been identified with the discovery of USP8 and USP48 mutations. The elucidation of genetic and molecular pathophysiology in pituitary adenomas is a key factor for better patient management and effective follow-up.
Ruthenium(II)-Complex-Catalyzed Acceptorless Double Dehydrogenation of Primary Amines to Nitriles
Authors: Muthaiah Senthilkumar , Kannan Muthukumar
Published: April 2020

Acceptorless dehydrogenative oxidation of primary amines into nitriles using an in situ complex derived from commercially available dichloro(1,5-cyclooctadiene) ruthenium(II) complex and simple hexamethylenetetramine has been demonstrated. The synthetic protocol is highly selective and yields the nitrile compounds in moderate to excellent yields and produces hydrogen as the sole byproduct.
Three-Component Reaction of Homophthalic Anhydride with Carbonyl Compounds and Ammonium Acetate: New Developments
Authors: Krasavin Mikhail , Safrygin Alexander , Bakulina Olga , Dar’in Dmitry
Published: April 2020

The earlier described reaction of homophthalic anhydrides with aromatic ketones and ammonium acetate was tested for cyclic ketones (yielding spirocyclic motifs) and aliphatic aldehydes. In contrast to previous findings, the reaction was found to require no catalyst at all and to be applicable, in the non-catalyzed format, to these new carbonyl substrates as well as aromatic ketones. The reaction typically proceeds with high diastereoselectivity; if not, the initial diastereomeric mixture can be quantitatively equilibrated into a single, trans-diastereomer on treatment with aqueous base.
Role of Phosphodiesterase Inhibitors in Improving Urodynamic Parameters in Patients with Spinal Cord Injury: A Preliminary Report
Authors: Iqbal Muzzain , Chhiber Sarbjit Singh , Wazir Baldev Singh , Ramzan Altaf Umar , Wani Mohammad Saleem
Published: April 2020

Objective To analyze role of phosphodiesterase 5 (PDE5) inhibitors on urodynamic parameters in patients with suprasacral spinal cord injury.

Materials and Methods This was a prospective observational hospital-based study conducted on a cohort of patients, aged between 18 and 65 years with suprasacral spinal cord injury, who were registered in Department of Neurosurgery/Urology. Cutoff period since injury was 2 years. After taking consent, baseline urodynamic study was performed, which was repeated 2 hours after taking single oral dose of 20 mg tadalafil. Urodynamic parameters such as maximum detrusor filling/voiding pressures, maximum bladder capacity, and bladder compliance before and after taking drug were compared for final results and conclusion.

Results Following administration of 20 mg of tadalafil, maximum bladder capacity in mL showed statistically significant improvement from 268.39 ± 130.0 to 298.55 ± 112.0.(p < 0.05). Bladder compliance improved from 18.68 ± 6.4 to 20.25 ± 7.5 mL/cm H2O (p > 0.05). Maximum detrusor filling pressure improved from 36.03 ± 20.54 to 32.90 ± 16.47 cm H2O (p > 0.05). Maximum detrusor voiding pressure improved from 64.65 ± 33.19 to 58.13 ± 20.7 cm H2O (0 > 0.05). In patients with injury above D6 spinal cord level, statistically significant improvement was seen in maximum bladder capacity and bladder compliance after 2 hours of single oral dose of tadalafil (p < 0.05).

Conclusion Our study suggests a positive role of PDE inhibitors in improving urodynamic parameters in patients with suprasacral spinal cord injury with improvement in parameters such as bladder capacity, detrusor pressures, and bladder compliance. Because this is a small study group, more studies such as this are required to reach to final conclusion.
When does turbulence spreading matter?
Authors: Singh Rameswar , Diamond P. H.
Published: April 2020

Few, if any, of the many papers on turbulence spreading address the key question of how turbulence spreading actually affects the profile structure. Here, we are using a reduced model to answer that question. Turbulence spreading is most relevant near regions where the profiles support a strong intensity gradient ∇I. One such case is at the edge of an L mode discharge, near a source of turbulence [i.e., either a localized source of edge turbulence or an influx of turbulence from the scrape-off layer (SOL)]. Another is in “No Man's Land” (NML), which connects the pedestal to the stiff core in H mode. In the case of L mode, without an edge intensity source, the turbulence intensity profile is nearly flat and spreading has a weak effect. An edge localized source increases the edge ∇I, which then drives inward spreading. Invasion of turbulence from the SOL to the edge softens the edge pressure gradient. In H mode, the strong shear suppression of pedestal turbulence necessarily forces a sharp ∇I in NML. This sharp ∇I drives a significant flux of turbulence from the core to the pedestal, where it is ultimately dissipated by shearing. Counter-intuitively, the results indicate that spreading actually increases the pedestal height and width and hence the energy content in H mode. This suggests that models of the pedestal structure should include NML turbulence spreading effects. The relation of avalanches to spreading is studied. Spreading weakly affects the avalanche distribution, but the spatiotemporal correlation of intensity increases with spreading.
Effect of a tightly focused chirped Gaussian laser pulse on electron acceleration in helical undulator
Authors: Kumar Sandeep , Gupta D. N. , Malik H. K. , Singh Devi , Lee Jaeyu , Yoon Moohyun
Published: April 2020

The chirped-pulse inverse free electron laser (CIFEL) interaction has been investigated by considering a tightly focused chirped Gaussian laser pulse and a helical undulator in vacuum. We consider the more realistic description of a laser, i.e., seventh-order calculation in the spatial term and first-order calculation in the temporal term. Numerical calculations show that better electron acceleration can be achieved using a tightly focused chirped Gaussian laser pulse in the CIFEL scheme. The investigation shows that a 10 MeV electron can be accelerated up to a few giga-electron volts energy with the present available laser parameters.
Effect of the Pfirsch–Schlüter flow on the inboard/outboard asymmetry of the toroidal flow in LHD
Authors: Yamamoto Y. , Murakami S. , Takahashi H. , Ida K. , Yoshinuma M. , Chen J.
Published: April 2020

Inboard/outboard asymmetry of the toroidal flow has been observed in the large helical device (LHD), especially when the radial electric field is large. We investigate the effect of the Pfirsch–Schlüter flow on the toroidal flow in LHD plasma. As a result, we find that the Pfirsch–Schlüter flow can be significantly large when the electron root solution of the neoclassical ambipolarity condition is achieved with a large radial electric field. We show that the Pfirsch–Schlüter flow can explain the asymmetry of toroidal flow in the electron cyclotron heating plasma and the perpendicular neutral beam injection plasma of LHD. Furthermore, we estimate the electrostatic potential from the flow asymmetry and obtain a relatively good agreement with experimental results by charge exchange recombination spectroscopy.
In situ multimodal imaging for nanoscale visualization of tribofilm formation
Authors: Pawlicki Alison A. , Bansal Dinesh G. , Borodinov Nikolay , Belianinov Alex , Cogen Kerry , Clarke Dean , Sumpter Bobby G. , Ovchinnikova Olga S.
Published: April 2020

A third of the energy from fuel combustion in passenger car gasoline engines is lost due to friction. Carefully designed engine lubricants can recover some of these losses by reducing friction and wear by forming a nanometer-scale chemico-physico tribofilm between surfaces. Accordingly, attention has focused on developing oil formulations that form low-friction tribofilms. However, analyses of resultant tribofilms are typically conducted after tribo-tests with conventional characterization tools and do not offer insights into tribofilm formation and evolution, precluding information critical to tuning tribofilm properties. In this work, we developed a unique multimodal methodology based on Atomic Force Microscopy (AFM) with local probe heating for in situ tribological studies that activates friction modifiers and simultaneously captures the evolution of friction and surface roughness, with nanometer resolution. As a platform to demonstrate the ability of this methodology to visualize dynamics of tribofilm formation in situ, we apply it to molybdenum-based friction modifiers to distinguish key factors in their functionality and correlate nanoscale AFM and Friction Force Microscopy data to bench tribo-tests used in the industry. To decode the formation mechanisms observed in situ and underlying chemistry of tribofilms, we performed ab initio Molecular Dynamics (AIMD) simulations at comparable conditions. AIMD simulations confirmed both nanoscale and bench tribo-test results and showed deviations in molecular organization in tribofilms that are formed from different molybdenum-based friction modifiers that corroborates with surface functionality. With this innovative methodology, we demonstrate proof-of-principle in situ formation of molybdenum-based tribofilms directly on steel surfaces that could be applied generally to studying tribofilm formation.
Evolution of quasiperiodicity in quorum-sensing coupled identical repressilators
Authors: Stankevich N. , Volkov E.
Published: April 2020

The dynamics of three three-dimensional repressilators globally coupled by a quorum sensing mechanism was numerically studied. This number (three) of coupled repressilators is sufficient to obtain such a set of self-consistent oscillation frequencies of signal molecules in the mean field that results in the appearance of self-organized quasiperiodicity and its complex evolution over wide areas of model parameters. Numerically analyzing the invariant curves as a function of coupling strength, we observed torus doubling, three torus arising via quasiperiodic Hopf bifurcation, the emergence of resonant cycles, and secondary Neimark–Sacker bifurcation. A gradual increase in the oscillation amplitude leads to chaotizations of the tori and to the birth of weak, but multidimensional chaos.
Comment on “Damage evolution in LiNbO3 due to electronic energy deposition below the threshold for direct amorphous track formation” [J. Appl. Phys. 126, 125105 (2019)]
Authors: Szenes G.
Published: April 2020

In their article, Wesch et al. deal with defect formation and amorphization in LiNbO3 after irradiation close to the threshold conditions. It is problematic that two thermal spike models are applied in the analysis, which are not compatible with each other. The key parameter of the authors' model—efficiency γ—is derived erroneously in the paper. Formal agreement with the experiments is achieved for point defect production using four parameters for reducing the deviations. It is assumed that amorphization proceeds with the growth of amorphous pockets. However, the conditions of the formation of these pockets are calculated using the inelastic thermal spike model beyond the range of its validity, and this model rejects the basic assumptions of the authors' exciton model. In pursuance of the above criticism, the paper of Wesch et al. is not well thought-out and the experimental results would require a more consequent and closely reasoned analysis.
Magnetohydrodynamic wave modes in relativistic anisotropic quantum plasma
Authors: Patidar Archana , Sharma Prerana
Published: April 2020

This paper presents an overview of waves and instabilities in relativistic degenerate plasma using magnetohydrodynamic double polytropic laws. The model equations are closed by the double polytropic laws. The general dispersion relation has been derived using the normal mode analysis, which consists of two interesting modes, i.e., shear Alfvén mode and modified magnetosonic modes (both slow and fast). The shear Alfvén mode is significantly modified by anisotropic pressure and relativistic effects and remains unaffected from quantum effects. The shear Alfvén mode develops the firehose instability, which is free from the relativistic factor. The obtained slow and fast magnetosonic modes are further discussed in parallel, perpendicular, and oblique modes of propagation. The Alfvén and sound waves propagate in parallel mode, while only the magnetosonic mode propagates in perpendicular mode. The sound wave and magnetosonic wave modes are found to be modified by relativistic and quantum effects. The oblique wave propagation provides fast and slow modes, which propagate with the combined force of anisotropic pressure, Bohm force, magnetic field, and exchange potential. The applicability of the results obtained from the dispersion relation in the relativistic degenerate anisotropic magnetohydrodynamic model can be to the pulsar magnetosphere environment.
Asymptotic stability of multi-soliton solutions for nonlinear Schrödinger equations with time-dependent potential
Authors: Deng Qingquan , Yao Xiaohua
Published: April 2020

In this paper, we consider the nonlinear Schrödinger equation i∂tψ=−12Δψ+V(t,x)ψ−F(|ψ|2)ψ with time-dependent potential in R3. We prove that the weakly interacting N-soliton is asymptotically stable in a Sobolev space H1(R3) under certain assumptions on the time dependent potential V(t, x) and the spectral structures of the linearized Hamiltonian.
Phonon-assisted proton tunneling in the hydrogen-bonded dimeric selenates of Cs3H(SeO4)2
Authors: Matsui Hiroshi , Shimatani Kazuki , Ikemoto Yuka , Sasaki Takahiko , Matsuo Yasumitsu
Published: April 2020

In phases III and IV of Cs3H(SeO4)2, the vibrational state and intrabond transfer of the proton in the dimeric selenates are systematically studied with a wide range of absorbance spectra, a spin–lattice relaxation rate of 1H-NMR (T1−1), and DFT calculations. The OH stretching vibrations have extremely broad absorption at around 2350 (B band) and 3050 cm−1 (A band), which originate from the 0–1 and 0–2 transitions in the asymmetric double minimum potential, respectively. The anharmonic-coupling calculation makes clear that the A band couples not only to the libration but also to the OH bending band. The vibrational state (nano-second order) is observed as the response of the proton basically localized in either of the two equivalent sites. The intrabond transfer between those sites (pico-second order) yields the protonic fluctuation reflected in T1−1. Together with the anomalous absorption [νp2 phonon, libration, tetrahedral deformation (δ440), and 610-cm−1 band], we have demonstrated that the intrabond transfer above 70 K is dominated by the thermal hopping that is collectively excited at 610 cm−1 and the phonon-assisted proton tunneling (PAPT) relevant to the tetrahedral deformation [PAPT(def)]. Below 70 K, T1−1 is largely enhanced toward the antiferroelectric ordering and the distinct splitting emerges in the libration, which dynamically modulates the O(2)–O′(2) distance of the dimer. The PAPT(lib) associated with the libration is confirmed to be a driving force of the AF ordering.
RF current condensation in the presence of turbulent enhanced transport
Authors: Rodríguez E. , Reiman A. H. , Fisch N. J.
Published: April 2020

Sharp temperature gradients in a magnetically confined plasma can lead to turbulent motion of the plasma. This turbulence in turn enhances the transport of heat across magnetic field lines. The enhanced transport impacts the temperature differential that can be sustained in magnetic islands between the island center and its periphery. It is shown here that, by limiting this temperature differential, this enhanced transport can have a profound influence on the extent to which the RF current condensation effect stabilizes the island growth. Interestingly, because the heat transport is no longer simply linear in the temperature gradient, the RF current condensation effect also exhibits entirely new hysteresis phenomena.
Ignition criteria for x-ray fast ignition inertial confinement fusion
Authors: Lee J. G. , Robinson A. P. L. , Pasley J.
Published: April 2020

The derivation of the ignition energy for fast ignition inertial confinement fusion is reviewed and one-dimensional simulations are used to produce a revised formula for the ignition energy of an isochoric central hot-spot, which accounts for variation in the radius of the hot-spot rh as well as the density ρ. The required energy may be as low as 1 kJ when ρrh≈0.36 g cm−2, T≈20 keV, and ρ≥700 g cm−2. Although there are many physical challenges to creating these conditions, a possible route to producing such a hot-spot is via a bright source of non-thermal soft x-rays. Further one-dimensional simulations are used to study the non-thermal soft x-ray heating of dense DT and it is found to offer the potential to significantly reduce hydrodynamic losses as compared to particle driven fast ignition due to the hotspot being heated supersonically in a layer-by-layer fashion. A sufficiently powerful soft x-ray source would be difficult to produce, but line emission from laser-produced-plasma is the most promising option.
Recent developments in the general atomic and molecular electronic structure system
Authors: Barca Giuseppe M. J. , Bertoni Colleen , Carrington Laura , Datta Dipayan , De Silva Nuwan , Deustua J. Emiliano , Fedorov Dmitri G. , Gour Jeffrey R. , Gunina Anastasia O. , Guidez Emilie , Harville Taylor , Irle Stephan , Ivanic Joe , Kowalski Karol , Leang Sarom S. , Li Hui , Li Wei , Lutz Jesse J. , Magoulas Ilias , Mato Joani , Mironov Vladimir , Nakata Hiroya , Pham Buu Q. , Piecuch Piotr , Poole David , Pruitt Spencer R. , Rendell Alistair P. , Roskop Luke B. , Ruedenberg Klaus , Sattasathuchana Tosaporn , Schmidt Michael W. , Shen Jun , Slipchenko Lyudmila , Sosonkina Masha , Sundriyal Vaibhav , Tiwari Ananta , Galvez Vallejo Jorge L. , Westheimer Bryce , Włoch Marta , Xu Peng , Zahariev Federico , Gordon Mark S.
Published: April 2020

A discussion of many of the recently implemented features of GAMESS (General Atomic and Molecular Electronic Structure System) and LibCChem (the C++ CPU/GPU library associated with GAMESS) is presented. These features include fragmentation methods such as the fragment molecular orbital, effective fragment potential and effective fragment molecular orbital methods, hybrid MPI/OpenMP approaches to Hartree–Fock, and resolution of the identity second order perturbation theory. Many new coupled cluster theory methods have been implemented in GAMESS, as have multiple levels of density functional/tight binding theory. The role of accelerators, especially graphical processing units, is discussed in the context of the new features of LibCChem, as it is the associated problem of power consumption as the power of computers increases dramatically. The process by which a complex program suite such as GAMESS is maintained and developed is considered. Future developments are briefly summarized.
Influence of saturable absorber saturation power, modulation depth and relaxation time on pulse parameters of a soliton fibre laser
Authors: Mastin A.A. , Ryabochkina P.A.
Published: April 2020

The influence of the saturable absorber saturation power, modulation depth and relaxation time on the energy and shape of fibre soliton laser pulses has been studied by numerical simulation. The results suggest that the use of a saturable absorber with a lower saturation power in a fibre laser ensures pulsed lasing onset at a lower gain. The fibre laser pulse energy decreases as the saturation power of the absorber or the relaxation time of its open state increases at a constant gain coefficient. In addition, increasing the absorber saturation modulation depth at a constant gain coefficient has been shown to reduce the pulse peak power and energy.
Laser and thermooptical characteristics of a laser head based on a thin Yb : YAG slab
Authors: Starobor A.V. , Kuznetsov I.I. , Mukhin I.B. , Palashov O.V.
Published: April 2020

Amplification and thermally induced phase distortions in a cw pumped laser head with an active element in the form of a thin Yb : YAG slab are experimentally studied. Lasing characteristics of an emitter based on this laser head are examined. Laser radiation is obtained with an average power of 32 W and a slope efficiency with respect to the absorbed pump powerη= 68 %.
Generation of gamma radiation by a subterawatt ultrashort laser pulse: optimisation of preplasma and pulse duration
Authors: Shulyapov S.A. , Tsymbalov I.N. , Ivanov K.A. , Gospodinov G.A. , Volkov R.V. , Bychenkov V.Yu. , Savel’ev A.B.
Published: April 2020

We report an experimental and numerical study of the acceleration of electrons in a plasma interacting with a subterawatt laser pulse (intensity of ∼3 × 1018 W cm−2 at a pulse duration of 50 fs). A preplasma layer on the surface of a molybdenum target is formed by an additional laser pulse with a duration of 8 ns and an intensity of ∼2 × 1012 W cm−2. It is shown that an increase in the laser pulse duration to 1700 fs at a constant energy (and a proportional decrease in intensity) leads to an increase in the yield of bremsstrahlung γ-radiation by more than an order of magnitude when the nanosecond pulse is ahead of the femtosecond one by 15 − 25 ns. Interferometry data and results of diagnostics of optical and γ-radiation of a plasma demonstrate that the collisional ionisation of atoms by electrons oscillating in the field of such a laser pulse plays an essential role in the formation of electron density profile. The sensitivity of the described effect to the level of amplified spontaneous emission is determined, despite the nanosecond pulse impact. Numerical simulations show that at a large pulse duration, the acceleration of electrons is stipulated by the beaking of plasma waves excited during stimulated Raman scattering of laser radiation.
Numerical simulation of dispersion and nonlinear characteristics of microstructured silica fibres with a thin suspended core in a wide range of their parameters
Authors: Anashkina E.A. , Andrianov A.V. , Leuchs G.
Published: April 2020

Dispersion and nonlinear characteristics of microstructured silica fibres with a thin suspended core surrounded by three, four or six air holes have been studied theoretically in the wavelength range 1 – 2 μm. It has been shown that, owing to strong fundamental mode confinement near the core, the Kerr nonlinearity coefficient can exceed the nonlinearity coefficient of standard telecom fibre SMF28e by two orders of magnitude. The large waveguide contribution allows for effective group velocity dispersion management. Estimates are presented that demonstrate the feasibility of using suspended core fibre exhibiting Kerr nonlinearity for generating non-classical light: a state with squeezed quantum fluctuations in one of the quadrature components of a cw laser signal at a wavelength near 1.55 μm.
Two-stage nonlinear compression of high-power femtosecond laser pulses
Authors: Ginzburg V.N. , Yakovlev I.V. , Zuev A.S. , Korobeynikova A.P. , Kochetkov A.A. , Kuzmin A.A. , Mironov S.Yu. , Shaykin A.A. , Shaikin I.A. , Khazanov E.A.
Published: April 2020

Two-stage compression of laser pulses with a power of 250 TW is experimentally realised by broadening their spectrum during self-phase modulation in fused silica and subsequent dispersion compensation upon reflection from chirping mirrors. A five-fold decrease in the duration is demonstrated, from 75 to 15 fs, with a B-integral value of about 5 at each stage. It is possible to avoid small-scale self-focusing due to self-filtering of the laser beam during free propagation in vacuum. With optimal parameters of the dispersive mirror, the pulse can be compressed to a duration of less than 5 fs.
Interference effects in the formation of the light bullet spectrum under axicon focusing
Authors: Zaloznaya E.D. , Kompanets V.O. , Chekalin S.V. , Dormidonov A.E. , Kandidov V.P.
Published: April 2020

Specific features of the anti-Stokes band of the light bullet supercontinuum spectrum under filamentation of 1900-nm femtosecond pulses, focused by an axicon in fused silica and calcium fluoride, have been experimentally, numerically, and analytically investigated. It is found that the formation of two or more light bullets in a filament leads to modulation of spectral components’ intensity. The oscillation period of spectral components, defined as the wavelength interval between adjacent intensity minima, decreases with decreasing their wavelength. On a logarithmic scale, the relative change in the oscillation period in the spectrum is proportional to the spectral component wavelength and is independent of the pulse energy and the position of the light bullet formation region in the filament. It is established that the modulation in the spectrum is due to the interference of the broadband supercontinuum emitted by light bullets, and its period decreases with increasing interval between them.
Dependence of emittance on the length of an electron bunch during laser-plasma acceleration in guiding structures
Authors: Veisman M.E. , Andreev N.E.
Published: April 2020

We report a theoretical analysis and numerical simulation of the dynamics of transverse emittance of an electron bunch during its acceleration in wake fields generated by a laser pulse in a weakly nonlinear mode. Analytical expressions are obtained for the main factors affecting the emittance growth during acceleration and the case is considered when the characteristic transverse size of the injected bunch exceeds the matched radius determined by the focusing force at the injection point, the initial emittance and the electron bunch energy, and the resulting value of emittance is much larger than the initial one. The dynamics of the emittance growth during acceleration as a function of the length of the electron bunch is described, and the length of the bunch is found at which there occurs a complete phase mixing of betatron oscillations of electrons and the emittance increases to its maximum value determined by the bunch parameters and the focusing force at the injection point. Analytical expressions are in good agreement with the results of numerical simulation.
Generation of few-cycle pulses in media with alternating sign of effective cubic nonlinearity
Authors: Frolov S.A. , Trunov V.I. , Bagayev S.N.
Published: April 2020

An original technique is developed for spectral broadening of femtosecond pulses with compensation for the nonlinear spatial phase during the propagation through nonlinear media with effective cubic nonlinearity of different signs. It was shown that in the region of 1.5 μm, the proposed scheme with BBO crystals at the first stage and NaCl at the second stage allows, using chirped mirrors, the formation of few-cycle pulses of about 7 fs duration with a small B-integral. The possibility of focusing of pulses compressed in the proposed scheme with a large Strehl ratio is demonstrated.
Identifying evolutionary lineages in the Elaeocarpus obovatus complex: population genetics and morphometric analyses support a new subspecies, Elaeocarpus obovatus subsp. umbratilis, from northern Queensland, Australia
Authors: Baba Yumiko , Rossetto Maurizio , Crayn Darren M.
Published: April 2020

With the aim to solve long-standing problems of taxonomic delimitation within the E. obovatus species complex (E. obovatus G.Don, E. arnhemicus F.Muell., E. sp. Mt Bellenden Ker (L.J.Brass 18336) Qld Herbarium and E. coorangooloo J.F.Bailey & C.T.White), diversity and relatedness were assessed using a combined population genetics and morphometric approach among 181 and 102 individuals respectively. Simple sequence-repeat (SSR) markers were analysed with clustering methods, analysis of molecular variance (AMOVA) and STRUCTURE. The morphometric data were analysed using cluster and classification and regression tree (CART) methods. The morphometric and genetic analyses together resolve discrete groups corresponding to E. arnhemicus, E. coorangooloo, E. obovatus and E. sp. Mt Bellenden Ker. Elaeocarpus arnhemicus is clearly distinct from all other entities on most of the morphometric and genetic analyses. By contrast, E. sp. Mt Bellenden Ker and E. obovatus were not clearly separated from each other in many morphometric analyses, but can be distinguished clearly by the strongly curved pedicels in early bud and hairy ovary, and, to a lesser extent, by the frequent occurrence of two racemes per axil and cuneate leaf bases, and on the results of the genetic analyses. Elaeocarpus coorangooloo exhibits considerable genetic admixture with the other entities, but it is morphologically distinct. SSR profiles suggested that E. arnhemicus and E. obovatus may be tetraploid, whereas the other entities are diploid. This study has clarified the taxonomic limits of the currently recognised species E. arnhemicus, E. obovatus and E. coorangooloo and supports recognition of E. sp. Mt Bellenden Ker at subspecies rank, described herein as E. obovatus subsp. umbratilis Y.Baba & Crayn. A key to all taxa and revised accounts of E. arnhemicus, E. obovatus subsp. obovatus and E. coorangooloo are provided.
A minor population of macrophage-tropic HIV-1 variants is identified in recrudescing viremia following analytic treatment interruption
Authors: Andrade Viviane M. , Mavian Carla , Babic Dunja , Cordeiro Thaissa , Sharkey Mark , Barrios Labelle , Brander Christian , Martinez-Picado Javier , Dalmau Judith , Llano Anuska , Li Jonathan Z. , Jacobson Jeffrey , Lavine Christy L. , Seaman Michael S. , Salemi Marco , Stevenson Mario
Published: April 2020

HIV-1 persists in cellular reservoirs that can reignite viremia if antiretroviral therapy (ART) is interrupted. Therefore, insight into the nature of those reservoirs may be revealed from the composition of recrudescing viremia following treatment cessation. A minor population of macrophage-tropic (M-tropic) viruses was identified in a library of recombinant viruses constructed with individual envelope genes that were obtained from plasma of six individuals undergoing analytic treatment interruption (ATI). M-tropic viruses could also be enriched from post-ATI plasma using macrophage-specific (CD14) but not CD4+ T cell-specific (CD3) antibodies, suggesting that M-tropic viruses had a macrophage origin. Molecular clock analysis indicated that the establishment of M-tropic HIV-1 variants predated ATI. Collectively, these data suggest that macrophages are a viral reservoir in HIV-1–infected individuals on effective ART and that M-tropic variants can appear in rebounding viremia when treatment is interrupted. These findings have implications for the design of curative strategies for HIV-1.
A viral toolkit for recording transcription factor–DNA interactions in live mouse tissues
Authors: Cammack Alexander J. , Moudgil Arnav , Chen Jiayang , Vasek Michael J. , Shabsovich Mark , McCullough Katherine , Yen Allen , Lagunas Tomas , Maloney Susan E. , He June , Chen Xuhua , Hooda Misha , Wilkinson Michael N. , Miller Timothy M. , Mitra Robi D. , Dougherty Joseph D.
Published: April 2020

Transcription factors (TFs) enact precise regulation of gene expression through site-specific, genome-wide binding. Common methods for TF-occupancy profiling, such as chromatin immunoprecipitation, are limited by requirement of TF-specific antibodies and provide only end-point snapshots of TF binding. Alternatively, TF-tagging techniques, in which a TF is fused to a DNA-modifying enzyme that marks TF-binding events across the genome as they occur, do not require TF-specific antibodies and offer the potential for unique applications, such as recording of TF occupancy over time and cell type specificity through conditional expression of the TF–enzyme fusion. Here, we create a viral toolkit for one such method, calling cards, and demonstrate that these reagents can be delivered to the live mouse brain and used to report TF occupancy. Further, we establish a Cre-dependent calling cards system and, in proof-of-principle experiments, show utility in defining cell type-specific TF profiles and recording and integrating TF-binding events across time. This versatile approach will enable unique studies of TF-mediated gene regulation in live animal models.
Regulatory mechanism for the transmembrane receptor that mediates bidirectional vitamin A transport
Authors: Zhong Ming , Kawaguchi Riki , Costabile Brianna , Tang Yuyan , Hu Jane , Cheng Guo , Kassai Miki , Ribalet Bernard , Mancia Filippo , Bok Dean , Sun Hui
Published: April 2020

Significance

Vitamin A has diverse biological functions and is transported to target tissues through the specific interaction between its blood transport protein (RBP) and its multitransmembrane domain receptor. However, how this receptor is regulated was completely unknown. Both insufficient or excessive vitamin A uptake has deleterious effects. Through unbiased mass spectrometry analysis and mechanistic studies, this study identified a cellular mechanism that profoundly influences receptor-mediated cellular vitamin A influx and efflux and may point to new directions to treat diseases associated with vitamin A imbalance.
Electrochemically scrambled nanocrystals are catalytically active for CO
2
-to-multicarbons
Authors: Li Yifan , Kim Dohyung , Louisia Sheena , Xie Chenlu , Kong Qiao , Yu Sunmoon , Lin Tom , Aloni Shaul , Fakra Sirine C. , Yang Peidong
Published: April 2020

Significance

The electrocatalytic conversion of CO
2
to value-added products, especially valuable multicarbon products, is a pathway toward sustainable formation of chemicals and fuels typically derived from fossil fuels, while mitigating CO
2
emissions. Fundamental understanding and development of more efficient catalysts for this reaction require deep investigation into structures with high intrinsic activity, which are limited at present. This work comprehensively investigates a dynamic copper nanoparticle ensemble catalyst that significantly improves intrinsic activity of copper for multicarbon formation. Through concerted ex situ and in situ characterization techniques, it illustrates an electrochemically induced fusion of copper nanoparticles that result in a catalytically active disordered structure, motivating closer study of disordered metal nanostructures for C–C coupling electrocatalysis.
RepeatModeler2 for automated genomic discovery of transposable element families
Authors: Flynn Jullien M. , Hubley Robert , Goubert Clément , Rosen Jeb , Clark Andrew G. , Feschotte Cédric , Smit Arian F.
Published: April 2020

The accelerating pace of genome sequencing throughout the tree of life is driving the need for improved unsupervised annotation of genome components such as transposable elements (TEs). Because the types and sequences of TEs are highly variable across species, automated TE discovery and annotation are challenging and time-consuming tasks. A critical first step is the de novo identification and accurate compilation of sequence models representing all of the unique TE families dispersed in the genome. Here we introduce RepeatModeler2, a pipeline that greatly facilitates this process. This program brings substantial improvements over the original version of RepeatModeler, one of the most widely used tools for TE discovery. In particular, this version incorporates a module for structural discovery of complete long terminal repeat (LTR) retroelements, which are widespread in eukaryotic genomes but recalcitrant to automated identification because of their size and sequence complexity. We benchmarked RepeatModeler2 on three model species with diverse TE landscapes and high-quality, manually curated TE libraries:
Drosophila melanogaster
(fruit fly),
Danio rerio
(zebrafish), and
Oryza sativa
(rice). In these three species, RepeatModeler2 identified approximately 3 times more consensus sequences matching with >95% sequence identity and sequence coverage to the manually curated sequences than the original RepeatModeler. As expected, the greatest improvement is for LTR retroelements. Thus, RepeatModeler2 represents a valuable addition to the genome annotation toolkit that will enhance the identification and study of TEs in eukaryotic genome sequences. RepeatModeler2 is available as source code or a containerized package under an open license (
https://github.com/Dfam-consortium/RepeatModeler
,
http://www.repeatmasker.org/RepeatModeler/
).
Demographic science aids in understanding the spread and fatality rates of COVID-19
Authors: Dowd Jennifer Beam , Andriano Liliana , Brazel David M. , Rotondi Valentina , Block Per , Ding Xuejie , Liu Yan , Mills Melinda C.
Published: April 2020

Governments around the world must rapidly mobilize and make difficult policy decisions to mitigate the coronavirus disease 2019 (COVID-19) pandemic. Because deaths have been concentrated at older ages, we highlight the important role of demography, particularly, how the age structure of a population may help explain differences in fatality rates across countries and how transmission unfolds. We examine the role of age structure in deaths thus far in Italy and South Korea and illustrate how the pandemic could unfold in populations with similar population sizes but different age structures, showing a dramatically higher burden of mortality in countries with older versus younger populations. This powerful interaction of demography and current age-specific mortality for COVID-19 suggests that social distancing and other policies to slow transmission should consider the age composition of local and national contexts as well as intergenerational interactions. We also call for countries to provide case and fatality data disaggregated by age and sex to improve real-time targeted forecasting of hospitalization and critical care needs.
Constructionalization and the Sorites Paradox
Authors: Flach Susanne
Published: April 2020

This article discusses the relationship between
“constructionalization” and
“constructional change” (Traugott & Trousdale, 2013). Expanding
on recent critical reviews, the paper argues that the problems with
constructionalization arise from the ambiguity of the concept: it
refers simultaneously to processes leading to the creation of a new
node and to the point of node creation itself. The issues are
illustrated by tracking the emergence of the
into-causative: the data show that a series of
interrelated changes in multiple parts of the network provided
necessary and facilitating conditions, some of which predate the
into-causative by several generations. The
suggestion is that constructionalization should be reserved for its
point reading, while aspects of its process reading are better
captured by “constructional emergence”.
Constructionalization, constructional competition and
constructional death
Authors: Sommerer Lotte
Published: April 2020

This paper revisits POSS DEM constructions in Old
English (OE) by analyzing 13 OE prose texts from the
York-Toronto-Helsinki Parsed Corpus of Old English
Prose (YCOE). It aims to explain the marginalization
and ultimate demise of this constructional family by discussing how
the emergence of a new node (“constructionalization”) but also the
reorganization of node-external, vertical and horizontal links can
lead to constructional competition and ultimately to the
disappearance of (a) node(s) in the network. It will especially
discuss frequency effects and cognitive factors like strong/weak
entrenchment or analogical thinking as driving forces of network
change, especially constructional loss. Additionally, this paper
makes some suggestions on how constructions should be annotated and
sketched in networks.
Allostructions, homostructions or a constructional
family?
Authors: Percillier Michael
Published: April 2020

The network of prepositional secondary predicate
constructions has undergone massive changes throughout the history
of English. While in Old English forms marked with to (e.g. crown someone as king) used to dominate, forms marked with as dominate
in Present-Day English (e.g. crown someone as king). The present
paper studies the changes in the network of such constructions
marked with as, for, into, and to in the Middle English
period by analysing changes in frequency and semantic similarity. A
corpus study in the PPCME2 was conducted, based on a Distributional
Semantic Model. The results indicate a sudden turning point in the
early Middle English period whereby to-marked forms
quickly lost their importance. In addition to providing insights
into the (changing) nature of polysemic links and allostructions,
the description of constructions copied from Anglo-Norman introduces
a language contact component to the framework of Diachronic
Construction Grammar.
Noun phrase complexity in young Spanish EFL learners’ writing
Authors: Díez-Bedmar María Belén , Pérez-Paredes Pascual
Published: April 2020

The research reported in this article examines Noun Phrase (NP) syntactic complexity in the writing of Spanish EFL
secondary school learners in Grades 7, 8, 11 and 12 in the International Corpus of Crosslinguistic Interlanguage. Two
methods were combined: a manual parsing of NPs and an automatic analysis of NP indices using the Tool for the
Automatic Analysis of Syntactic Sophistication and Complexity (TAASSC). Our results revealed that it
is in premodifying slots that syntactic complexity in NPs develops. We argue that two measures, (i) nouns and modifiers (a
syntactic complexity index) and (ii) determiner + multiple premodification + head (a NP type obtained as a result of a
corpus-driven analysis), can be used as indices of syntactic complexity in young Spanish EFL learner language development. Besides
offering a learner-language-driven taxonomy of NP syntactic complexity, the paper underscores the strength of using combined
methods in SLA research.
The role of L1 use by high-proficiency learners in L2 vocabulary
development
Authors: Sato Masatoshi , Angulo Isidora
Published: April 2020

This study investigated second language (L2)
learners’ use of first language (L1) as a means to resolve lexical
issues during collaborative writing tasks (i.e., L1 languaging).
Participants were 34 8th grade high-proficiency English learners in
Chile who shared their L1 (Spanish). Their vocabulary development
was tested via the vocabulary knowledge scale (VKS). Their
interactions during the collaborative writing tasks were
audio-recorded. The transcripts were first analysed in light of L1
focus such as content, language, and task management. Then, lexical
language-related episodes (LREs) involving L1 were examined. The
regression models of the VKS and LRE scores showed that L1
languaging was associated with higher gains in vocabulary
knowledge.