bluuebunny/crossref_metadata_2025 huggingface dataset:
All-passive multiple-place optical phase noise cancellation
Authors: Hu Liang , Xue Ruimin , Tian Xueyang , Wu Guiling , Chen Jianping
Published: February 2021

We report on the realization of delivering coherent optical frequency to multiple places based on passive phase noise cancellation over a bus topology fiber network. This technique mitigates any active servo controller on the main fiber link and at arbitrary access places as opposed to the conventional technique, in which an active phase compensation circuit has to be adopted to stabilize the main fiber link. Although the residual fiber phase noise power spectral density in the proposed technique turns out to be a factor of seven higher than that of in the conventional multiple-access technique when the access place is close to the end of the fiber link, it could largely suppress the phase noise introduced by the servo bumps, improve the response speed and phase recovery time, and minimize hardware overhead in systems with many stations and connections without the need for active servo circuits including phase discriminators and active compensators. The proposed technique could considerably simplify future efforts to make precise optical frequency signals available to many users, as required by some large-scale science experiments.
Hybrid electro-optic modulator combining silicon photonic slot waveguides with high-k radio-frequency slotlines
Authors: Ummethala Sandeep , Kemal Juned N. , Alam Ahmed S. , Lauermann Matthias , Kuzmin Artem , Kutuvantavida Yasar , Nandam Sree H. , Hahn Lothar , Elder Delwin L. , Dalton Larry R. , Zwick Thomas , Randel Sebastian , Freude Wolfgang , Koos Christian
Published: February 2021

Electro-optic (EO) modulators rely on the interaction of optical and electrical signals with second-order nonlinear media. For the optical signal, this interaction can be strongly enhanced using dielectric slot–waveguide structures that exploit a field discontinuity at the interface between a high-index waveguide core and the low-index EO cladding. In contrast to this, the electrical signal is usually applied through conductive regions in the direct vicinity of the optical waveguide. To avoid excessive optical loss, the conductivity of these regions is maintained at a moderate level, thus leading to inherentRClimitations of the modulation bandwidth. In this paper, we show that these limitations can be overcome by extending the slot–waveguide concept to the modulating radio-frequency (RF) signal. Our device combines an RF slotline that relies onBaTiO3as a high-k dielectric material with a conventional silicon photonic slot waveguide and a highly efficient organic EO cladding material. In a proof-of-concept experiment, we demonstrate a 1 mm long Mach–Zehnder modulator that offers a 3 dB bandwidth of 76 GHz and a 6 dB bandwidth of 110 GHz along with a smallπvoltage of 1.3 V (UπL=1.3Vmm). We further demonstrate the viability of the device in a data-transmission experiment using four-state pulse-amplitude modulation (PAM4) at line rates up to 200 Gbit/s. Our first-generation devices leave vast room for further improvement and may open an attractive route towards highly efficient silicon photonic modulators that combine sub-1 mm device lengths with sub-1 V drive voltages and modulation bandwidths of more than 100 GHz.
Minimally dissipative all-coherent spin switching at terahertz clock rates
Authors: Schlauderer S. , Lange C. , Schmid C. P. , Zvezdin A. K. , Kimel A. V. , Mikhaylovskiy R. V. , Huber R.
Published: February 2021

Antenna-enhanced single-cycle terahertz transients ballistically switch spins in antiferromagnetic TmFeO3 between metastable states separated by a potential energy barrier. We directly trace the temporal and spectral fingerprints of this ultrafast and minimally dissipative dynamics.
Determination of spin-orbit splitting of Kr+ and Kr2+ by ultrafast motion of the valence electrons
Authors: Ando Toshiaki , Liu Alex , Iwasaki Atsushi , Yamanouchi Kaoru
Published: February 2021

We determine the spin-orbit splitting energies of Kr+ and Kr2+ with high precision by monitoring the yields of Kr2+ in real-time by the pump-probe measurements using few-cycle near-infrared laser pulses.
Phonon-Assisted Exciton Polarization to Population Transfer in a 2D Semiconductor
Authors: Trovatello Chiara , Katsch Florian , Selig Malte , Borys Nicholas , Yao Kaiyuan , Scotognella Francesco , Schuck P. James , Knorr Andreas , Cerullo Giulio , Dal Conte Stefano
Published: February 2021

Here we exploit transient reflectivity with sub-20fs temporal resolution to extract the exciton formation timescale from the build up of A/B exciton dynamics of 1L-MoS2. The timescale for this process ranges from ~15fs to ~35fs. © 2020 The Author(s)
Partially-Bright Triplet Excitons in CsPbI3 Perovskite Nanocrystals and their Coherent Dynamics
Authors: Cundiff Steven T. , Liu Albert , Almeida Diogo B. , Bonato Luiz G. , Nagamine Gabriel , Zagonel Luiz F. , Nogueira Ana F. , Padilha Lazaro A.
Published: February 2021

Multi-dimensional coherent spectroscopy is applied to CsPbI3 perovskite nanocrystals at cryogenic temperatures. Coherence times of the non-degenerate triplet state fine-structure are characterized. Evidence of a partially-bright level ordering is presented.
Picosecond time-resolved imaging using a single-pixel detector
Authors: Tan Xiaobo , Li Can , Zhou Yongzhuang , Chen Shaorong , Zhuang Zhaowen
Published: February 2021

We propose a single-pixel ultrafast imaging (SPUI) method based on single-pixel imaging and time-correlated-single-photon counting (TCSPC). Time-resolved imaging of laser pulse propagation, reflection and total internal reflection in water is demonstrated as an example.
Long-lived Excited States in 7- and 9-Methylpurine Probed by fs Time-Resolved Vibrational Absorption Spectroscopy
Authors: Holtmann Rebecca , Nimmrich Amke , Böhnke Hendrik , Temps Friedrich
Published: February 2021

Transient vibrational absorption spectroscopy elucidates common deactivation pathways after UV photoexcitation for 7- and 9-methylpurine. However, 9-methylpurine exhibits an additional relaxation channel revealed by indirect observation of the excited 1ππ* state
Gold Rush in Dynamics? Time-resolved Ion Spectroscopy Reveals Ultrafast Processes in Isomorphic, Ligated Ag/Au Coinage Metal Dimers
Authors: Kruppa S. V. , Schmitt M. , Israil R. , Bäppler F. , Grupe M. , Schüssler L. , Diller R. , Klopper W. , Riehn C.
Published: February 2021

Ultrafast electronic dynamics and UV absorption of phosphine–ligated (L) coinage metal complexes [Ag2(L)2]2, [AgAu(L)2]2+and [Au2(L)2]2+reveal the influence of intermetallic interaction on electronic states. Isomorphic exchange by AuIpresumably accelerates ISC rate.
Mapping out Photoprotective Dissipation in Green Plants Using Ultrabroadband 2D Electronic Spectroscopy
Authors: Son Minjung , Pinnola Alberta , Bassi Roberto , Schlau-Cohen Gabriela S.
Published: February 2021

Plants protect against photodamage by dissipating harmful excess sunlight. Using ultrabroadband 2D electronic spectroscopy, we directly resolve sub-ps chlorophyll-to-carotenoid energy transfer in LHCII, the major light-harvesting complex, a hypothesized but previously unobserved pathway for dissipation. © 2020 The Author(s)
Caged-Contact Pair Recombination Following Photolysis in Cooled Triiodide Solutions
Authors: Gao Frank Y. , Cheng Yu-Hsiang , Nelson Keith A.
Published: February 2021

The temperature-dependent recombination of caged-contact pairs following triiodide photolysis is investigated via ultrafast single-shot pump-probe spectroscopy. We find that the fraction of contact pairs formed increases at low temperature while the decays obey an Arrhenius relation.
Solvent Assisted Excited State Proton Transfer in Indigo Carmine Investigated by Two-Dimensional Electronic-Vibrational Spectroscopy
Authors: Roy P. P. , Shee J. , Arsenault E. A. , Yoneda Y. , Feuling K. , Head-Gordon M. , Fleming G. R.
Published: February 2021

The solvent dependent electronic excited state deactivation dynamics of Indigo Carmine is mapped by the two-dimensional electronic-vibrational spectroscopy (2DEV). The H-bonding ability of the solvent has been found to assist the excited state proton transfer.
Vibrational relaxation of water at the air/H2O interface revealed by time-resolved heterodyne-detected vibrational sum-frequency generation in the OH stretch hot-band region
Authors: Sung Woongmo , Inoue Ken-ichi , Nihonyanagi Satoshi , Tahara Tahei
Published: February 2021

Vibrational relaxation (T1) time of hydrogen-bonded OH of interfacial water was determined by TR-HD-VSFG spectroscopy to be 250 - 400 fs contrary to the previous report, while free-OH stretch shows noticeably slow (~1 ps) T1.
Attosecond spectral singularities in solid-state high-harmonic generation
Authors: Uzan Ayelet Julie , Orenstein Gal , Bruner Barry D. , Jiménez-Galán Á lvaro , McDonald Chris , Silva Rui E. F. , Klimkin Nikolai D. , Blanchet Valerie , Arusi-Parpar Talya , Krüger Michael , Rubtsov Alexey N. , Smirnova Olga , Ivanov Misha , Yan Binghai , Brabec Thomas , Dudovich Nirit
Published: February 2021

Using high-harmonic generation spectroscopy, we reveal the underlying at-tosecond dynamics in multi-band solid-state systems. We identify the mapping of spectral caustics into the high-harmonic spectrum, and probe the structure of multiple unpopulated high conduction bands.
Detecting electronic coherences by the multidimensionl HHG spectroscopy
Authors: Jiang Shicheng , Kowalewski Markus , Dorfman Konstantin E.
Published: February 2021

We propose an all-optical method based on pump-probe HHG to detect electronic coherence. Based on a new developed semi-perturbative approach, coherence between bound states is observed in Fourier transformed harmonic spectra using noncollinear geometry setup.
High-order Harmonic Generation in Femtosecond Laser Micromachined Devices for Ultrafast X-ray Spectroscopy
Authors: Ciriolo A. G. , Vázquez R. Martínez , Tosa V. , Frezzotti A. , Cinquanta E. , Crippa G. , Faccialà D. , Devetta M. , Osellame R. , Vozzi C. , Stagira S.
Published: February 2021

We demonstrate efficient high-order harmonic generation in fused-silica chips fabricated by femtosecond laser micromachining. This work provides a route toward the miniaturization of HHG beamlines and the implementation of X-ray spectroscopy with attosecond temporal resolution.
Phase matched high-harmonic generation in macroscopic single-layer graphene
Authors: Boyero-García Roberto , Zurrón-Cifuentes Óscar , Plaja Luis , Hernández-García Carlos
Published: February 2021

We study the macroscopic build-up of the high-harmonic signal in single-layer graphene. Our results show that the emission is dominated by a phase-matched ring.
Capturing Roaming Fragments in Real Time: A Molecular Road Movie
Authors: Endo Tomoyuki , Neville Simon P. , Wanie Vincent , Beaulieu Samuel , Qu Chen , Deschamps Jude , Lassonde Philippe , Schmidt Bruno E. , Fujise Hikaru , Fushitani Mizuho , Hishikawa Akiyoshi , Houston Paul L. , Bowman Joel M. , Schuurman Michael S. , Légaré François , Ibrahim Heide
Published: February 2021

“Roamers” are directly observed in the prototypical roaming reaction in the formaldehyde molecule. Despite their statistical nature, roaming is well discriminated from the radical- and molecular dissociation channels, using Coulomb explosion imaging and theoretical modeling.
Twist-angle-dependent photoresponse in MoS2-graphene van der Waals heterostructures probed by ultrafast electron diffraction
Authors: Luo Duan , Tang Jian , Shen Xiaozhe , Ji Fuhao , Yang Jie , Weathersby Stephen , Kozina Michael E. , Chen Zhijiang , Cao Ting , Zhang Guangyu , Wang Xijie , Lindenberg Aaron M.
Published: February 2021

The photophysics of MoS2-graphene heterostructures at different twist angles has been investigated by ultrafast electron diffraction. The structural response of MoS2 heterostructures show a twist-angle dependence and exhibit faster dynamics than pure monolayer MoS2.
Ultrafast Magnetization Dynamics Revealed by Terahertz Magnetometry
Authors: Zhang Wentao , Maldonado Pablo , Jin Zuanming , Seifert Tom S. , Arabski Jacek , Schmerber Guy , Beaurepaire Eric , Bonn Mischa , Kampfrath Tobias , Oppeneer Peter M. , Turchinovich Dmitry
Published: February 2021

We investigate ultrafast magnetization dynamics in encapsulated iron films, benefitting from their laser-induced terahertz emission. Combined with first-principles theoretical modeling, the experimental results provide quantitative insights into the observed magnetization dynamics.
Molecular Quantum Wakes for Clearing Fog
Authors: Schroeder Malte C. , Larkin Ilia , Produit Thomas , Rosenthal Eric W. , Milchberg Howard , Wolf Jean-Pierre
Published: February 2021

Fog is a major obstacle for free-space optical communication. Our work introduces a novel approach for clearing optically transparent paths through fog via the opto-mechanical displacement of droplets through molecular quantum wakes in air.
Exerting Coherent Control over a Surface Structural Phase Transition via Amplitude Modes
Authors: Horstmann Jan Gerrit , Böckmann Hannes , Wit Bareld , Kurtz Felix , Storeck Gero , Ropers Claus
Published: February 2021

We use ultrafast low-energy electron diffraction (ULEED) and multi-pulse optical excitation to demonstrate coherent control over the metal-insulator structural phase transition in atomic indium wires on the (111) surface of silicon.
Light-induced manipulation of the charge density wave in 1T-TaSe2
Authors: Shi Xun , You Wenjing , Zhang Yingchao , Tao Zhensheng , Zhong Yigui , Oppeneer Peter M. , Wu Xianxin , Thomale Ronny , Rossnagel Kai , Bauer Michael , Kapteyn Henry , Murnane Margaret
Published: February 2021

We observe new intermediate and inverted charge density wave states in 1T-TaSe2 using time- and angle-resolved photoemission spectroscopy. The results provide unique opportunities to understand and control the microscopic interactions and material properties.
Ultrafast Probing of the Dielectric Response of Nanoplasmonic Systems
Authors: Pápa Z. , Csontos J. , Dombi P. , Budai J.
Published: February 2021

We demonstrate results of plasmon-associated probing of the dielectric properties of metallic surface nanostructures utilizing ultrafast ellipsometry. Monitoring changes in the dielectric function allows for tracking plasmon related transitions and decay mechanisms.
Strain Effect on the Orientation-dependent Harmonic Spectrum of Monolayer Aluminum Nitride
Authors: Wang Ziwen , Yu Chao , Lu Ruifeng
Published: February 2021

In this study, we theoretically investigate the strain effect on the orientation-dependent high-order harmonic generation (HHG) of monolayer aluminum nitride (AlN) by solving the multiband semiconductor Bloch equations in strong laser fields. Our simulations denote that the odd-even feature in the orientation-dependent high harmonic spectra owing to the strain is considerably different when compared with that in the case without strain. The enhanced quantum interference between different energy bands in strained AlN around the Γ-M direction is responsible for the observed odd-even distributions of the orientation-dependent HHG.
On the absence of phonon bottleneck in lead selenide quantum dot
Authors: Yue Luye , Yang Lele , Li Jingjun , Liu Dong , Qi Yingpeng , Wang Xuan , Cao Jianming
Published: February 2021

We observed the ultrafast lattice dynamic in lead selenide (PbSe) quantum dots using ul-trafast electron diffraction. The electron-phonon coupling time constant is about 10 ps, showing no sign of phonon bottleneck.
Multielectron trace of back reaction in high-harmonic generation
Authors: de las Heras Alba , Hernández-García Carlos , Plaja Luis
Published: February 2021

We describe back-reaction as a novel correlation mechanism in the two-electron dynamics of helium atoms exposed to intense laser fields. The electron-electron correlation information is encoded as a high-energy secondary plateau in high-harmonic spectroscopy.
Generation of Continuously-Tunable, Narrowband THz Pulses from Phase-Locked Femtosecond Pulse Bursts
Authors: Stummer Vinzenz , Flöry Tobias , Kaksis Edgar , Pugžlys Audrius , Baltuška Andrius , Krizsán Gergő , Polónyi Gyula , Fülöp József
Published: February 2021

We demonstrate generation of continuously-tunable, narrowband THz pulses from phase-locked multi-millijoule femtosecond pulse bursts by optical rectification in a tilted-pulse-front setup. Experimental results indicate advances in both femtosecond pulse burst and high-energy THz source technology.
Fast Pulse Reconstruction from FROG Traces Using Only Three Time-Shift Steps
Authors: Mao Anjun , Liu Chengpu
Published: February 2021

The fast reconstruction of an ultrashort laser pulse can be realized from flexibly shaped cross-phase-modulated frequency-resolved optical gating (FROG) traces via ptychography algorithm, which are composed of only three time-shift steps.
Efficient THz generation by optical rectification of intense mid-infrared pulses in organic crystals
Authors: Gollner Claudia , Shalaby Mostafa , Astrauskas Ignas , Brodeur Corinne , Baltuska Andrius , Pugzlys Audrius
Published: February 2021

We report on efficient THz generation in DAST, driven by mid-infrared pump sources. Due to the suppression of multi-photon absorption, high pump fluences can be applied and outstanding optical to THz conversion efficiencies of more than 4% can be reached.
Ultrafast laser spectral reshaping and carrier-frequency control by intense terahertz fields in electro-optic materials
Authors: Giorgianni Flavio , Puc Uros , Jazbinsek Mojca , Koo Min-Jeong , Han Jae-Hyun , Kwon O-Pil , Vicario Carlo
Published: February 2021

Intense terahertz fields induce a time-varying phase modulation by Pockels and Kerr effects, which causes spectacular spectral modifications of a co-propagating near-infrared laser. The results open new prospects for light modulation at terahertz frequency. © 2020 The Author(s)
Integral Representation of Weak-Field Asymptotic Theory using Density Functional Orbitals and Potentials for an Efficient and Qualitatively Accurate Calculation of Angle Dependent Ionization Rate
Authors: Wahyutama Imam S. , Lopata Kenneth , Gaarde Mette B. , Schafer Kenneth J.
Published: February 2021

We explore the implementation of weak field asymptotic theory using orbitals and potentials calculated via Density Functional Theory. This provides a way to calculate strong field ionization rates by assuming that the field is constant.
Unipolar half-cycle pulses and their applications for efficient excitation and selective ultrafast control of atomic systems
Authors: Arkhipov Rostislav , Arkhipov Mikhail , Pakhomov Anton , Babushkin Ihar , Demircan Ayhan , Morgner Uwe , Rosanov Nikolay
Published: February 2021

In this talk, we discuss recently developed by us methods of unipolar half-cycle pulse generation having attosecond duration in optical range and femtosecond duration in terahertz frequency ranges. Such pulses contain a half period of electric field oscillation and weak decaying tail of opposite polarity (quasi unipolar pulse) or without tail (unipolar one). They can have nonzero electric field area. The common way for effective excitation and control of atomic populations is to excite them with resonant multi-cycle pulses. We demonstrate that half-cycle and unipolar pulses can be also used for effective excitation, charge acceleration and selective excitation of atomic level populations in spite of non-resonant interaction and broad spectrum.
High-power OPCPAs at 1.45 – 2.4 µm and up to 100 W power scalability
Authors: Buss Jan Heye , Grguras Ivanka , Golz Torsten , Prandolini Mark , Schulz Michael , Riedel Robert
Published: February 2021

A high-power optical parametric chirped-pulse amplifier (OPCPA) at 1.45 – 2.40 µm wavelength, pumped by Yb-based solid-state lasers with average power scalability up to 100 W and pulse durations in the few-cycle regime is presented.
Generation of CEP-stable half-cycle 10 µm pulses through two-color laser-induced filamentation
Authors: Huang Wei-Hong , Kumaki Fumitoshi , Luo Chih-Wei , Fuji Takao
Published: February 2021

We have experimentally demonstrated the generation of half-cycle pulses with the center wavelength of 10 µm through two-color filamentation in nitrogen with the duration of 12 fs, which corresponds to 0.36 cycles.
Attosecond resolution from free running interferometric measurements
Authors: Fuchs Jaco , Krüger Constantin , Cattaneo Laura , Keller Ursula
Published: February 2021

On the attosecond time scale even the smallest portion of timing jitter crucially affects the experimental time resolution. Here, we present a novel analysis technique of attosecond interferometric measurements, which overcomes the effects of jitter.
The ELI-ALPS HR2 Laser System: CEP-Stable Few-Cycle Pulses at 500W of Average Power
Authors: Hädrich Steffen , Walther Nico , Simon Peter , Nagy Tamas , Blumenstein Andreas , Shestaev Evgeny , Jójárt Péter , Várallyay Zoltán , Seres Imre , Börzsönyi Ádám , Eidam Tino , Limpert Jens
Published: February 2021

We present the latest development of the ELI-ALPS HR2 laser towards a 5mJ, 6fs CEP stable output, which will be enabled by post-compression of >1kW, >10mJ fiber CPA system in an 8m long stretched hollow-core fiber.
Ultrafast Optical Dynamics of a Nonlinearly Coupled Au Plasmon-ZnO Exciton Nanostructure
Authors: Zhong Jin-Hui , Yi Jue-Min , Wang Dong , Korte Anke , Chimeh Abbas , Schaaf Peter , Runge Erich , Lienau Christoph
Published: February 2021

By using interferometric frequency-resolved autocorrelation spectroscopy, we spectrally and temporally probe the coherent second-order nonlinear emission from hybrid Au (plasmon)/ZnO (exciton) nanosponges. The femtosecond coherence dynamics and quantum pathways of plasmon-enhanced nonlinear excitonic emission are revealed.
Imaging the Dynamics of Charge Transfer and Frenkel Excitons in Molecular Thin Films
Authors: Stadtmüller Benjamin , Hemm Ralf , Haag Florian , Mitkov Martin , Emmerich Sebastian , Hedwig Sebastian , Aeschlimann Martin
Published: February 2021

Using time- and momentum-resolved photoemission, we investigated the formation and ultrafast relaxation process of excitons in molecular materials. We uncovered stepwise transitions between charge transfer and Frenkel excitons with different charge character and spatial distributions.
Topographic Control of Light at the Quantum Level
Authors: Carbajo Sergio , Lemons Randy , Liu Wei , Frisch Josef C , Fry Alan , Robinson Joseph , Smith Steve
Published: February 2021

we present the synthesis of ultrashort laser bullets with real-time adaptive and programmable field topology, including field amplitude, and linear, spin angular, and orbital angular momenta.
Extreme Raman Spectral Broadening in Hollow-Core Fibers
Authors: Coccia G. , Piccoli R. , Carpeggiani P.A. , Fan G. , Kaksis E , Pugzlys A. , Jeong Y.-G. , Rovere A. , Morandotti R. , Razzari L. , Schmidt B. E. , Voronin A. A. , Zheltikov A. , Baltuška A.
Published: February 2021

Stimulated Raman Scattering over ~6-m-long nitrogen-filled hollow-core fibers enables the efficient generation of high-energy (mJ), few-cycle (~20-fs), shortwave-IR (1-1.73 µm) pulses. Full three-dimensional model is also required to predict the observed extremely asymmetric spectral broadening.
Sustainable cascading of the femtosecond supercontinuum generation in multi-plate media
Authors: Fu Z. , Zhang S. , Zhu B. , Fan G. , Wang S. , Baltuska A. , Tian C. , Tao Z.
Published: February 2021

We investigate the femtosecond supercontinuum generation and compression in layered Kerr media. The condition for extending the setup in a sustainable way is revealed, with characteristic spectral and temporal features. We demonstrate tenfold pulse compression in a single-stage multiplate setup by including 14 layers of the thin medium.
Extremely Non-Adiabatic Switching of Deep-Strong Light-Matter Coupling
Authors: Mornhinweg Joshua , Halbhuber Maike , Zeller Viola , Ciuti Cristiano , Bougeard Dominique , Huber Rupert , Lange Christoph
Published: February 2021

We observe a non-adiabatic switch-off of deep-strong light-matter coupling characterized by pronounced subcycle polarization oscillations. A quantum model verifies that light-matter decoupling occurs more than an order of magnitude faster than the optical cycle duration.
Adaptive social contact rates induce complex dynamics during epidemics
Authors: Arthur Ronan F. , Jones James H. , Bonds Matthew H. , Ram Yoav , Feldman Marcus W.
Published: February 2021

Epidemics may pose a significant dilemma for governments and individuals. The personal or public health consequences of inaction may be catastrophic; but the economic consequences of drastic response may likewise be catastrophic. In the face of these trade-offs, governments and individuals must therefore strike a balance between the economic and personal health costs of reducing social contacts and the public health costs of neglecting to do so. As risk of infection increases, potentially infectious contact between people is deliberately reduced either individually or by decree. This must be balanced against the social and economic costs of having fewer people in contact, and therefore active in the labor force or enrolled in school. Although the importance of adaptive social contact on epidemic outcomes has become increasingly recognized, the most important properties of coupled human-natural epidemic systems are still not well understood. We develop a theoretical model for adaptive, optimal control of the effective social contact rate using traditional epidemic modeling tools and a utility function with delayed information. This utility function trades off the population-wide contact rate with the expected cost and risk of increasing infections. Our analytical and computational analysis of this simple discrete-time deterministic strategic model reveals the existence of an endemic equilibrium, oscillatory dynamics around this equilibrium under some parametric conditions, and complex dynamic regimes that shift under small parameter perturbations. These results support the supposition that infectious disease dynamics under adaptive behavior change may have an indifference point, may produce oscillatory dynamics without other forcing, and constitute complex adaptive systems with associated dynamics. Implications for any epidemic in which adaptive behavior influences infectious disease dynamics include an expectation of fluctuations, for a considerable time, around a quasi-equilibrium that balances public health and economic priorities, that shows multiple peaks and surges in some scenarios, and that implies a high degree of uncertainty in mathematical projections.
Modulation of the dynamics of cerebellar Purkinje cells through the interaction of excitatory and inhibitory feedforward pathways
Authors: Tang Yuanhong , An Lingling , Yuan Ye , Pei Qingqi , Wang Quan , Liu Jian K.
Published: February 2021

The dynamics of cerebellar neuronal networks is controlled by the underlying building blocks of neurons and synapses between them. For which, the computation of Purkinje cells (PCs), the only output cells of the cerebellar cortex, is implemented through various types of neural pathways interactively routing excitation and inhibition converged to PCs. Such tuning of excitation and inhibition, coming from the gating of specific pathways as well as short-term plasticity (STP) of the synapses, plays a dominant role in controlling the PC dynamics in terms of firing rate and spike timing. PCs receive cascade feedforward inputs from two major neural pathways: the first one is the feedforward excitatory pathway from granule cells (GCs) to PCs; the second one is the feedforward inhibition pathway from GCs, via molecular layer interneurons (MLIs), to PCs. The GC-PC pathway, together with short-term dynamics of excitatory synapses, has been a focus over past decades, whereas recent experimental evidence shows that MLIs also greatly contribute to controlling PC activity. Therefore, it is expected that the diversity of excitation gated by STP of GC-PC synapses, modulated by strong inhibition from MLI-PC synapses, can promote the computation performed by PCs. However, it remains unclear how these two neural pathways are interacted to modulate PC dynamics. Here using a computational model of PC network installed with these two neural pathways, we addressed this question to investigate the change of PC firing dynamics at the level of single cell and network. We show that the nonlinear characteristics of excitatory STP dynamics can significantly modulate PC spiking dynamics mediated by inhibition. The changes in PC firing rate, firing phase, and temporal spike pattern, are strongly modulated by these two factors in different ways. MLIs mainly contribute to variable delays in the postsynaptic action potentials of PCs while modulated by excitation STP. Notably, the diversity of synchronization and pause response in the PC network is governed not only by the balance of excitation and inhibition, but also by the synaptic STP, depending on input burst patterns. Especially, the pause response shown in the PC network can only emerge with the interaction of both pathways. Together with other recent findings, our results show that the interaction of feedforward pathways of excitation and inhibition, incorporated with synaptic short-term dynamics, can dramatically regulate the PC activities that consequently change the network dynamics of the cerebellar circuit.
An epidemiological surveillance of hand foot and mouth disease in paediatric patients and in community: A Singapore retrospective cohort study, 2013–2018
Authors: Min Nyo , Ong Yasmin Hui Binn , Han Alvin X. , Ho Si Xian , Yen Emmerie Wong Phaik , Ban Kenneth Hon Kim , Maurer-Stroh Sebastian , Chong Chia Yin , Chu Justin Jang Hann
Published: February 2021

Background

While hand, foot and mouth disease (HFMD) is primarily self-resolving—soaring incidence rate of symptomatic HFMD effectuates economic burden in the Asia-Pacific region. Singapore has seen a conspicuous rise in the number of HFMD cases from 2010s. Here, we aims to identify the serology and genotypes responsible for such outbreaks in hospitals and childcare facilities.

Methods

We studied symptomatic paediatric HFMD cases from 2013 to 2018 in Singapore. Surveillance for subclinical enterovirus infections was also performed in childcares at the same time period.

Results

Genotyping 101 symptomatic HFMD samples revealed CV-A6 as the major etiological agent for recent outbreaks. We detected infections with CV-A6 (41.0%), EV-A71 (7%), CV-A16 (3.0%), coxsackievirus A2, CV-A2 (1.0%) and coxsackievirus A10, CV-A10 (1.0%). Phylogenetic analysis of local CV-A6 strains revealed a high level of heterogeneity compared against others worldwide, dissimilar to other HFMD causative enteroviruses for which the dominant strains and genotypes are highly region specific. We detected sub-clinical enterovirus infections in childcare centres; 17.1% (n = 245) tested positive for enterovirus in saliva, without HFMD indicative symptoms at the point of sample collection.

Conclusions

CV-A6 remained as the dominant HFMD causative strain in Singapore. Silent subclinical enteroviral infections were detected and warrant further investigations.
A multi-contextual examination of non-school friendships and their impact on adolescent deviance and alcohol use
Authors: Jose Rupa , Hipp John R. , Butts Carter T. , Wang Cheng , Lakon Cynthia M.
Published: February 2021

Despite decades of research on adolescent friendships, little is known about adolescents who are more likely to form ties outside of school. We examine multiple social and ecological contexts including parents, the school, social networks, and the neighborhood to understand the origins and health significance of out of school ties using survey data from the National Longitudinal Study of Adolescent to Adult Health (N= 81,674). Findings indicate that out of school (more than in-school) friendships drive adolescent deviance and alcohol use, and youth with such friends tend to be involved in school activities and are central among their peer group. This suggests that intervention efforts aimed at reducing deviance and underage drinking may benefit from engaging youth with spanning social ties.
Hepatitis C treatment strategies in prisons: A cost-effectiveness analysis
Authors: Kwon Jisoo A. , Chambers Georgina M. , Luciani Fabio , Zhang Lei , Kinathil Shamin , Kim Dennis , Thein Hla-Hla , Botha Willings , Thompson Sandra , Lloyd Andrew , Yap Lorraine , Gray Richard T. , Butler Tony
Published: February 2021

In Australian prisons approximately 20% of inmates are chronically infected with hepatitis C virus (HCV), providing an important population for targeted treatment and prevention. A dynamic mathematical model of HCV transmission was used to assess the impact of increasing direct-acting antiviral (DAA) treatment uptake on HCV incidence and prevalence in the prisons in New South Wales, Australia, and to assess the cost-effectiveness of alternate treatment strategies. We developed four separate models reflecting different average prison lengths of stay (LOS) of 2, 6, 24, and 36 months. Each model considered four DAA treatment coverage scenarios of 10% (status-quo), 25%, 50%, and 90% over 2016–2045. For each model and scenario, we estimated the lifetime burden of disease, costs and changes in quality-adjusted life years (QALYs) in prison and in the community during 2016–2075. Costs and QALYs were discounted 3.5% annually and adjusted to 2015 Australian dollars. Compared to treating 10% of infected prisoners, increasing DAA coverage to 25%, 50%, and 90% reduced HCV incidence in prisons by 9–33% (2-months LOS), 26–65% (6-months LOS), 37–70% (24-months LOS), and 35–65% (36-months LOS). DAA treatment was highly cost-effective among all LOS models at conservative willingness-to-pay thresholds. DAA therapy became increasingly cost-effective with increasing coverage. Compared to 10% treatment coverage, the incremental cost per QALY ranged from $497-$569 (2-months LOS), -$280–$323 (6-months LOS), -$432–$426 (24-months LOS), and -$245–$477 (36-months LOS). Treating more than 25% of HCV-infected prisoners with DAA therapy is highly cost-effective. This study shows that treating HCV-infected prisoners is highly cost-effective and should be a government priority for the global HCV elimination effort.
Revisiting soil bacterial counting methods: Optimal soil storage and pretreatment methods and comparison of culture-dependent and -independent methods
Authors: Lee Jeonggil , Kim Han-Suk , Jo Ho Young , Kwon Man Jae
Published: February 2021

Although a number of different methods have been used to quantify soil bacteria, identifying the optimal method(s) for soil bacterial abundance is still in question. No single method exists for undertaking an absolute microbial count using culture-dependent methods (CDMs) or even culture-independent methods (CIMs). This study investigated soil storage and pretreatment methods for optimal bacterial counts. Appropriate storage temperature (4°C) and optimal pretreatment methods (sonication time for 3 min and centrifugation at 1400g) were necessary to preserve bacterial cell viability and eliminate interference from soil particles. To better estimate soil bacterial numbers under various cellular state and respiration, this study also evaluated three CDMs (i.e., colony forming unit, spotting, and most probable number (MPN) and three CIMs (i.e., flow cytometry (FCM), epifluorescence microscopy (EM) count, and DNA quantitation). Each counting method was tested using 72 soil samples collected from a local arable farm site at three different depths (i.e., 10–20, 90–100, and 180–190 cm). Among all CDMs, MPN was found to be rapid, simple, and reliable. However, the number of bacteria quantified by MPN was 1–2 orders lower than that quantified by CIMs, likely due to the inability of MPN to count anaerobic bacteria. The DNA quantitation method appeared to overestimate soil bacterial numbers, which may be attributed to DNA from dead bacteria and free DNA in the soil matrix. FCM was found to be ineffective in counting soil bacteria as it was difficult to separate the bacterial cells from the soil particles. Dyes used in FCM stained the bacterial DNA and clay particles. The EM count was deemed a highly effective method as it provided information on soil mineral particles, live bacteria, and dead bacteria; however, it was a time-consuming and labor-intensive process. Combining both types of methods was considered the best approach to acquire better information on the characteristics of indigenous soil microorganisms (aerobic versus anaerobic, live versus dead).
A novel mouse model for checkpoint inhibitor-induced adverse events
Authors: Adam Kieran , Iuga Alina , Tocheva Anna S. , Mor Adam
Published: February 2021

Immune checkpoint inhibitors have demonstrated significant efficacy in the treatment of a variety of cancers, however their therapeutic potential is limited by abstruse immune related adverse events. Currently, no robust animal model exists of checkpoint inhibitor-induced adverse events. Establishing such a model will improve our mechanistic understanding of this process, which in turn will inform design of improved therapies. We developed a mouse model to determine inflammatory toxicities in response to dual checkpoint blockade in the presence of syngeneic tumors. Mice from susceptible genetic backgrounds received intraperitoneal injections of anti-mouse PD-1 and CTLA-4 antibodies. The mice were monitored for weight loss and histologic evidence of inflammation. Blood was collected for basic metabolic panels and titers of anti-nuclear antibodies. In parallel, mice were also treated with prednisolone, which is commonly used to treat immune related adverse events among cancer patients. Among all the genetic backgrounds, B6/lpr mice treated with anti-CTLA-4 and anti-PD-1 antibodies developed more substantial hepatitis, pancreatitis, colitis, and pneumonitis characterized by organ infiltration of immune cells. Mice that developed tissue infiltration demonstrated high serum levels of glucose and high titers of anti-nuclear antibodies. Finally, while administration of prednisolone prevented the development of the inflammatory adverse events, it also abrogated the protective anti-tumor effect of the checkout inhibitors. Genetic background and treatment modalities jointly modified the inflammatory adverse events in tumor bearing mice, suggesting a complex mechanism for checkpoint inhibitor-related inflammation. Future studies will assess additional genetic susceptibility factors and will examine possible contributions from the administration of other anti-inflammatory drugs.
COVID-19 ICU and mechanical ventilation patient characteristics and outcomes—A systematic review and meta-analysis
Authors: Chang Raymond , Elhusseiny Khaled Mossad , Yeh Yu-Chang , Sun Wei-Zen
Published: February 2021

Background

Insight into COVID-19 intensive care unit (ICU) patient characteristics, rates and risks of invasive mechanical ventilation (IMV) and associated outcomes as well as any regional discrepancies is critical in this pandemic for individual case management and overall resource planning.

Methods and findings

Electronic searches were performed for reports through May 1 2020 and reports on COVID-19 ICU admissions and outcomes were included using predefined search terms. Relevant data was subsequently extracted and pooled using fixed or random effects meta-analysis depending on heterogeneity. Study quality was assessed by the NIH tool and heterogeneity was assessed by I2 and Q tests. Baseline patient characteristics, ICU and IMV outcomes were pooled and meta-analyzed. Pooled odds ratios (pOR) were calculated for clinical features against ICU, IMV mortality. Subgroup analysis was carried out based on patient regions. A total of twenty-eight studies comprising 12,437 COVID-19 ICU admissions from seven countries were meta-analyzed. Pooled ICU admission rate was 21% [95% CI 0.12–0.34] and 69% of cases needed IMV [95% CI 0.61–0.75]. ICU and IMV mortality were 28.3% [95% CI 0.25–0.32], 43% [95% CI 0.29–0.58] and ICU, IMV duration was 7.78 [95% CI 6.99–8.63] and 10.12 [95% CI 7.08–13.16] days respectively. Besides confirming the significance of comorbidities and clinical findings of COVID-19 previously reported, we found the major correlates with ICU mortality were IMV [pOR 16.46, 95% CI 4.37–61.96], acute kidney injury (AKI) [pOR 12.47, 95% CI 1.52–102.7], and acute respiratory distress syndrome (ARDS) [pOR 6.52, 95% CI 2.66–16.01]. Subgroup analyses confirm significant regional discrepancies in outcomes.

Conclusions

This is a comprehensive systematic review and meta-analysis of COVID-19 ICU and IMV cases and associated outcomes. The significant association of AKI, ARDS and IMV with mortality has implications for ICU resource planning for AKI and ARDS as well as suggesting the need for further research into optimal ventilation strategies for COVID-19 patients in the ICU setting. Regional differences in outcome implies a need to develop region specific protocols for ventilatory support as well as overall treatment.
Short- and long-term memory of moving amoeboid cells
Authors: van Haastert Peter J. M.
Published: February 2021

Amoeboid cells constantly change shape and extend protrusions. The direction of movement is not random, but is correlated with the direction of movement in the preceding minutes. The basis of this correlation is an underlying memory of direction. The presence of memory in movement is known for many decades, but its molecular mechanism is still largely unknown. This study reports in detail on the information content of directional memory, the kinetics of learning and forgetting this information, and the molecular basis for memory usingDictyosteliummutants. Two types of memory were characterized. A short-term memory stores for ~20 seconds the position of the last pseudopod using a local modification of the branched F-actin inducer SCAR/WAVE, which enhances one new pseudopod to be formed at the position of the previous pseudopod. A long term memory stores for ~2 minutes the activity of the last ~10 pseudopods using a cGMP-binding protein that induces myosin filaments in the rear of the cell; this inhibits pseudopods in the rear and thereby enhances pseudopods in the global front. Similar types of memory were identified in human neutrophils and mesenchymal stem cells, the protistDictyosteliumand the fungusB.d.chytrid. The synergy of short- and long-term memory explains their role in persistent movement for enhanced cell dispersal, food seeking and chemotaxis.
Impact of iron fortification on anaemia and iron deficiency among pre-school children living in Rural Ghana
Authors: Tchum Samuel Kofi , Arthur Fareed Kow , Adu Bright , Sakyi Samuel Asamoah , Abubakar Latifatu Alhassan , Atibilla Dorcas , Amenga-Etego Seeba , Oppong Felix Boakye , Dzabeng Francis , Amoani Benjamin , Gyan Thomas , Arhin Emmanuel , Poku-Asante Kwaku
Published: February 2021

Anaemia in young sub-Saharan African children may be due to the double burden of malaria and iron deficiency. Primary analysis of a double-blind, cluster randomized trial of iron containing micronutrient powder supplementation in Ghanaian children aged 6 to 35 months found no difference in malaria risk between intervention and placebo groups. Here, we performed a secondary analysis of the trial data to assess the impact of long-term prophylactic iron fortificant on the risk of iron deficiency and anaemia in trial subjects. This population-based randomized-cluster trial involved 1958 children aged between 6 to 35 months, identified at home and able to eat semi-solid foods. The intervention group (n = 967) received a daily dose containing 12.5 mg elemental iron (as ferrous fumarate), vitamin A (400 μg), ascorbic acid (30 mg) and zinc (5 mg). The placebo group (n = 991) received a similar micronutrient powder but without iron. Micronutrient powder was provided daily to both groups for 5 months. At baseline and endline, health assessment questionnaires were administered and blood samples collected for analysis. The two groups had similar baseline anthropometry, anaemia, iron status, demographic characteristics, and dietary intakes (p > 0.05). Of the 1904 (97.2%) children who remained at the end of the intervention, the intervention group had significantly higher haemoglobin (p = 0.0001) and serum ferritin (p = 0.0002) levels than the placebo group. Soluble transferrin receptor levels were more saturated among children from the iron group compared to non-iron group (p = 0.012). Anaemia status in the iron group improved compared to the placebo group (p = 0.03). Continued long-term routine use of micronutrient powder containing prophylactic iron reduced anaemia, iron deficiency and iron deficiency anaemia among pre-school children living in rural Ghana’s malaria endemic area.
The temporal nature of social context: Insights from the daily lives of patients with HIV
Authors: Fix Gemmae M. , Dryden Eileen M. , Boudreau Jacqueline , Kressin Nancy R. , Gifford Allen L. , Bokhour Barbara G.
Published: February 2021

Background

Patients’ life contexts are increasingly recognized as important, as evidenced by growing attention to the Social Determinants of Health (SDoH). This attention may be particularly valuable for patients with complex needs, like those with HIV, who are more likely to experience age-related comorbidities, mental health or substance use issues. Understanding patient perceptions of their life context can advance SDoH approaches.

Objectives

We sought to understand how aging patients with HIV think about their life context and explored if and how their reported context was documented in their electronic medical records (EMRs).

Design

We combined life story interviews and EMR data to understand the health-related daily life experiences of patients with HIV. Patients over 50 were recruited from two US Department of Veterans Affairs HIV clinics. Narrative analysis was used to organize data by life events and health-related metrics.

Key results

EMRs of 15 participants documented an average of 19 diagnoses and 10 medications but generally failed to include social contexts salient to patients. In interviews, HIV was discussed primarily in response to direct interviewer questions. Instead, participants raised past trauma, current social engagement, and concern about future health with varying salience. This led us to organize the narratives temporally according to past-, present-, or future-orientation. “Past-focused” narratives dwelled on unresolved experiences with social institutions like the school system, military or marriage. “Present-focused” narratives emphasized daily life challenges, like social isolation. “Future-focused” narratives were dominated by concerns that aging would limit activities.

Conclusions

A temporally informed understanding of patients’ life circumstances that are the foundation of their individualized SDoH could better focus care plans by addressing contextual concerns salient to patients. Trust-building may be a critical first step in caring for past-focused patients. Present-focused patients may benefit from support groups. Future-focused patients may desire discussing long term care options.
Construction project risk prediction model based on EW-FAHP and one dimensional convolution neural network
Authors: Zhong Yawen , Li Hailing , Chen Leilei
Published: February 2021

In order to solve the problem of low accuracy of traditional construction project risk prediction, a project risk prediction model based on EW-FAHP and 1D-CNN(One Dimensional Convolution Neural Network) is proposed. Firstly, the risk evaluation index value of construction project is selected by literature analysis method, and the comprehensive weight of risk index is obtained by combining entropy weight method (EW) and fuzzy analytic hierarchy process (FAHP). The risk weight is input into the 1D-CNN model for training and learning, and the prediction values of construction period risk and cost risk are output to realize the risk prediction. The experimental results show that the average absolute error of the construction period risk and cost risk of the risk prediction model proposed in this paper is below 0.1%, which can meet the risk prediction of construction projects with high accuracy.