bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of a bone filler scaffold for local antibiotic delivery to prevent Staphylococcus aureus infection in a contaminated bone defect
Authors: Beenken Karen E. , Campbell Mara J. , Ramirez Aura M. , Alghazali Karrar , Walker Christopher M. , Jackson Bailey , Griffin Christopher , King William , Bourdo Shawn E. , Rifkin Rebecca , Hecht Silke , Meeker Daniel G. , Anderson David E. , Biris Alexandru S. , Smeltzer Mark S. 
Published: May 2021

AbstractWe previously reported the development of an osteogenic bone filler scaffold consisting of degradable polyurethane, hydroxyapatite, and decellularized bovine bone particles. The current study was aimed at evaluating the use of this scaffold as a means of local antibiotic delivery to prevent infection in a bone defect contaminated with Staphylococcus aureus. We evaluated two scaffold formulations with the same component ratios but differing overall porosity and surface area. Studies with vancomycin, daptomycin, and gentamicin confirmed that antibiotic uptake was concentration dependent and that increased porosity correlated with increased uptake and prolonged antibiotic release. We also demonstrate that vancomycin can be passively loaded into either formulation in sufficient concentration to prevent infection in a rabbit model of a contaminated segmental bone defect. Moreover, even in those few cases in which complete eradication was not achieved, the number of viable bacteria in the bone was significantly reduced by treatment and there was no radiographic evidence of osteomyelitis. Radiographs and microcomputed tomography (µCT) analysis from the in vivo studies also suggested that the addition of vancomycin did not have any significant effect on the scaffold itself. These results demonstrate the potential utility of our bone regeneration scaffold for local antibiotic delivery to prevent infection in contaminated bone defects.
Learning deep features for dead and living breast cancer cell classification without staining
Authors: Pattarone Gisela , Acion Laura , Simian Marina , Mertelsmann Roland , Follo Marie , Iarussi Emmanuel 
Published: May 2021

AbstractAutomated cell classification in cancer biology is a challenging topic in computer vision and machine learning research. Breast cancer is the most common malignancy in women that usually involves phenotypically diverse populations of breast cancer cells and an heterogeneous stroma. In recent years, automated microscopy technologies are allowing the study of live cells over extended periods of time, simplifying the task of compiling large image databases. For instance, there have been several studies oriented towards building machine learning systems capable of automatically classifying images of different cell types (i.e. motor neurons, stem cells). In this work we were interested in classifying breast cancer cells as live or dead, based on a set of automatically retrieved morphological characteristics using image processing techniques. Our hypothesis is that live-dead classification can be performed without any staining and using only bright-field images as input. We tackled this problem using the JIMT-1 breast cancer cell line that grows as an adherent monolayer. First, a vast image set composed by JIMT-1 human breast cancer cells that had been exposed to a chemotherapeutic drug treatment (doxorubicin and paclitaxel) or vehicle control was compiled. Next, several classifiers were trained based on well-known convolutional neural networks (CNN) backbones to perform supervised classification using labels obtained from fluorescence microscopy images associated with each bright-field image. Model performances were evaluated and compared on a large number of bright-field images. The best model reached an AUC = 0.941 for classifying breast cancer cells without treatment. Furthermore, it reached AUC = 0.978 when classifying breast cancer cells under drug treatment. Our results highlight the potential of machine learning and computational image analysis to build new diagnosis tools that benefit the biomedical field by reducing cost, time, and stimulating work reproducibility. More importantly, we analyzed the way our classifiers clusterize bright-field images in the learned high-dimensional embedding and linked these groups to salient visual characteristics in live-dead cell biology observed by trained experts.
Dominant role of two-photon vertex in nonlinear response in two-dimensional Dirac systems
Authors: Rostami Habib , Cappelluti Emmanuele 
Published: May 2021

AbstractWe show that the standard concepts of nonlinear response to electromagnetic fields break down in two-dimensional Dirac systems, like graphene, in the quantum regime close to the Dirac point. We present a compelling many-body theory for nonlinear transport focusing on disorder scattering as a benchmark example. We show that, although the diamagnetic two-photon vertex is absent at the non-interacting level, disorder effects give rise to a self-generation of such two-photon vertex surviving even in the clean limit. We predict that the two-photon vertex self-generation is present only in two dimensions. The impact of such a striking scenario on the nonlinear quantum transport is discussed, predicting a huge enhancement of third-order dc conductivity comparing to the common models.
Measuring the effect of Non-Pharmaceutical Interventions (NPIs) on mobility during the COVID-19 pandemic using global mobility data
Authors: Snoeijer Berber T. , Burger Mariska , Sun Shaoxiong , Dobson Richard J. B. , Folarin Amos A. 
Published: May 2021

AbstractThe implementation of governmental Non-Pharmaceutical Interventions (NPIs) has been the primary means of controlling the spread of the COVID-19 disease. One of the intended effects of these NPIs has been to reduce population mobility. Due to the huge costs of implementing these NPIs, it is essential to have a good understanding of their efficacy. Using aggregated mobility data per country, released by Apple and Google we investigated the proportional contribution of NPIs to the magnitude and rate of mobility changes at a multi-national level. NPIs with the greatest impact on the magnitude of mobility change were lockdown measures; declaring a state of emergency; closure of businesses and public services and school closures. NPIs with the greatest effect on the rate of mobility change were implementation of lockdown measures and limitation of public gatherings. As confirmed by chi-square and cluster analysis, separately recorded NPIs like school closure and closure of businesses and public services were closely correlated with each other, both in timing and occurrence. This suggests that the observed significant NPI effects are mixed with and amplified by their correlated NPI measures. We observed direct and similar effects of NPIs on both Apple and Google mobility data. In addition, although Apple and Google data were obtained by different methods they were strongly correlated indicating that they are reflecting overall mobility on a country level. The availability of this data provides an opportunity for governments to build timely, uniform and cost-effective mechanisms to monitor COVID-19 or future pandemic countermeasures.
Denitrifying bacteria respond to and shape microscale gradients within particulate matrices
Authors: Smriga Steven , Ciccarese Davide , Babbin Andrew R. 
Published: May 2021

AbstractHeterotrophic denitrification enables facultative anaerobes to continue growing even when limited by oxygen (O2) availability. Particles in particular provide physical matrices characterized by reduced O2 permeability even in well-oxygenated bulk conditions, creating microenvironments where microbial denitrifiers may proliferate. Whereas numerical particle models generally describe denitrification as a function of radius, here we provide evidence for heterogeneity of intraparticle denitrification activity due to local interactions within and among microcolonies. Pseudomonas aeruginosa cells and microcolonies act to metabolically shade each other, fostering anaerobic processes just microns from O2-saturated bulk water. Even within well-oxygenated fluid, suboxia and denitrification reproducibly developed and migrated along sharp 10 to 100 µm gradients, driven by the balance of oxidant diffusion and local respiration. Moreover, metabolic differentiation among densely packed cells is dictated by the diffusional supply of O2, leading to distinct bimodality in the distribution of nitrate and nitrite reductase expression. The initial seeding density controls the speed at which anoxia develops, and even particles seeded with few bacteria remain capable of becoming anoxic. Our empirical results capture the dynamics of denitrifier gene expression in direct association with O2 concentrations over microscale physical matrices, providing observations of the co-occurrence and spatial arrangement of aerobic and anaerobic processes.
Magnetic equivalent of electric superradiance in yttrium-iron-garnet films
Authors: Weymann Lukas , Shuvaev Alexey , Pimenov Andrei , Mukhin Alexander A. , Szaller Dávid 
Published: May 2021

AbstractA dense system of independent oscillators, connected only by their interaction with the same cavity excitation mode, will radiate coherently, which effect is termed superradiance. In several cases, especially if the density of oscillators is high, the superradiant decay of the oscillators’ excited state may dominate the intrinsic relaxation processes. At low frequencies, this limit can be achieved with cyclotron resonance in two-dimensional electron gases. In those experiments, the cyclotron resonance is coupled to the electric field of light, while the oscillator density can be easily controlled by varying the gate voltage. However, in the case of magnetic oscillators, to achieve the dominance of superradiance is more tricky, as material parameters limit the oscillator density, and the magnetic coupling to the light wave is rather weak. Here we present quasi-optical magnetic resonance experiments on thin films of yttrium iron garnet. Due to the simplicity of experimental geometry, the intrinsic damping and the contribution of superradiance can be easily separated in the transmission spectra. We show that with increasing film thickness, the losses due to coherent radiation prevail the system’s internal broadening.
Wavelength scaling of electron collision time in plasma for strong field laser-matter interactions in solids
Authors: Nagar Garima C. , Dempsey Dennis , Shim Bonggu 
Published: May 2021

AbstractAlthough the dielectric constant of plasma depends on electron collision time as well as wavelength and plasma density, experimental studies on the electron collision time and its effects on laser-matter interactions are lacking. Here, we report an anomalous regime of laser-matter interactions generated by wavelength dependence (1.2–2.3 µm) of the electron collision time in plasma for laser filamentation in solids. Our experiments using time-resolved interferometry reveal that electron collision times are small (<1 femtosecond) and decrease as the driver wavelength increases, which creates a previously-unobserved regime of light defocusing in plasma: longer wavelengths have less plasma defocusing. This anomalous plasma defocusing is counterbalanced by light diffraction which is greater at longer wavelengths, resulting in almost constant plasma densities with wavelength. Our wavelength-scaled study suggests that both the plasma density and electron collision time should be systematically investigated for a better understanding of strong field laser-matter interactions in solids.
Graphdiyne@NiOx(OH)y heterostructure for efficient overall water splitting
Authors: Zhang Chao , Xue Yurui , Hui Lan , Fang Yan , Liu Yuxin , Li Yuliang 
Published: May 2021

A new GDY@NiOx(OH)y heterostructure was synthesized by creatively incorporating GDY with NiOx(OH)y for efficient water splitting. The mixed valence states and facilitated charge transfer behavior significantly improve the catalytic activity.
The dense warm ionized medium in the inner Galaxy
Authors: Langer W. D. , Pineda J. L. , Goldsmith P. F. , Chambers E. T. , Riquelme D. , Anderson L. D. , Luisi M. , Justen M. , Buchbender C. 
Published: May 2021

Context. Ionized interstellar gas is an important component of the interstellar medium and its lifecycle. The recent evidence for a widely distributed highly ionized warm interstellar gas with a density intermediate between the warm ionized medium (WIM) and compact H II regions suggests that there is a major gap in our understanding of the interstellar gas.
Aims. Our goal is to investigate the properties of the dense WIM in the Milky Way using spectrally resolved SOFIA GREAT [N II] 205 μm fine-structure lines and Green Bank Telescope hydrogen radio recombination lines (RRL) data, supplemented by spectrally unresolved Herschel PACS [N II] 122μm data, and spectrally resolved 12CO.
Methods. We observed eight lines of sight (LOS) in the 20° < l < 30° region in the Galactic plane. We analyzed spectrally resolved lines of [N II] at 205 μm and RRL observations, along with the spectrally unresolved Herschel PACS 122 μm emission, using excitation and radiative transfer models to determine the physical parameters of the dense WIM. We derived the kinetic temperature, as well as the thermal and turbulent velocity dispersions from the [N II] and RRL linewidths.
Results. The regions with [N II] 205 μm emission are characterized by electron densities, n(e) ~ 10−35 cm−3, temperatures range from 3400 to 8500 K, and nitrogen column densities N(N+) ~ 7 × 1016 to 3 × 1017 cm−2. The ionized hydrogen column densities range from 6 × 1020 to 1.7 × 1021 cm−2 and the fractional nitrogen ion abundance x(N+) ~ 1.1 × 10−4 to 3.0 × 10−4, implying an enhanced nitrogen abundance at a distance ~4.3 kpc from the Galactic Center. The [N II] 205 μm emission lines coincide with CO emission, although often with an offset in velocity, which suggests that the dense warm ionized gas is located in, or near, star-forming regions, which themselves are associated with molecular gas.
Conclusions. These dense ionized regions are found to contribute ≳50% of the observed [C II] intensity along these LOS. The kinetic temperatures we derive are too low to explain the presence of N+ resulting from electron collisional ionization and/or proton charge transfer of atomic nitrogen. Rather, these regions most likely are ionized by extreme ultraviolet (EUV) radiation from nearby star-forming regions or as a result of EUV leakage through a clumpy and porous interstellar medium.
Linking Neutrophil Extracellular Traps and Platelet Activation: A Composite Biomarker Score for Predicting Outcomes after Acute Myocardial Infarction
Authors: Hally Kathryn E. , Parker Olivia M. , Brunton-O'Sullivan Morgane M. , Harding Scott A. , Larsen Peter D. 
Published: May 2021

Abstract
Background Activation of both platelets and neutrophils can contribute to the risk of major adverse cardiovascular events (MACE) following acute myocardial infarction (AMI). Neutrophil extracellular traps (NETs) are an important product of the platelet–neutrophil axis and exaggerate vascular damage in cardiovascular disease. Additionally, activated platelets can drive NETosis and are directly linked to thromboembolic risk. Investigating the combined effect of biomarkers for NETosis and platelet activation represents a novel approach to risk prediction post-AMI. Here, we examined the utility of a composite biomarker score, inclusive of both pathways, for predicting MACE post-AMI.
Methods and Results In a case–control design, 100 case patients who experienced MACE within 1 year of index admission were matched in a 1:2 ratio with control patients. Serum levels of myeloperoxidase–DNA, neutrophil elastase–DNA, and citrullinated histone H3 were assayed by enzyme-linked immunosorbent assay (ELISA) as markers of NET burden. To measure platelet activation, soluble P-selectin was assayed by ELISA in parallel. Platelet and neutrophil counts were also recorded. Composite biomarker scores, inclusive of biomarkers for NETosis and platelet activation, were assessed using multivariate regression modeling. These composite biomarker scores were independent predictors of 1-year MACE. The strongest association with MACE was observed using a composite of platelet count, soluble P-selectin, and all NET markers (odds ratio: 1.94; 1.16–3.25).
Conclusion Here, we demonstrate the importance of combining biomarkers of NETosis and platelet activation for risk prediction in patients with AMI. Combining biomarkers from closely linked, but distinct, biological pathways was more effective than utilizing either type of biomarker alone.
Gigagauss magnetic field measurements using Zeeman broadening of Ne-like transitions in highly charged ions
Authors: Seely John F. 
Published: May 2021

The measurement of gigagauss magnetic fields using Zeeman broadening of Ne-like transitions in highly charged ions in high energy density plasmas is investigated. The transition in Xe44+ from the (2p51/23d3/2)J=1 level to the (2p6)J=0 ground level, designated 3C and having 4.858 keV transition energy, is considered in detail. Ne-like Xe spectra were previously recorded from compressed Xe-filled capsules, and the plasma conditions were determined from spectral line ratios and atomic code modeling. Using the Paschen–Back expression for Zeeman broadening produced by strong magnetic fields and the plasma conditions from the compressed Xe-filled capsule experiments to estimate the competing Stark, Doppler, and turbulence broadenings, it is found that &gt;0.34 GG fields can be determined from spectra recorded by a high-resolution spectrometer having 1 eV resolution (5000 resolving power). By scaling the plasma conditions to higher temperatures and densities, the minimum detectable magnetic field is determined for Zeeman broadening of the 3C transition in Ne-like ions up to U82+. Recently developed transmission-crystal spectrometers, employing a cylindrically bent crystal in the Cauchois configuration, have sufficient resolution to determine gigagauss magnetic fields from Zeeman broadening of Ne-like transitions in the 4–18 keV range in Xe44+ to U82+.
Experimental investigations on the post-arc current of the vacuum circuit breaker in an active mechanical DC circuit breaker
Authors: Jia Shenli , Tang Qiang , Shi Zongqian , Mo Yongpeng 
Published: May 2021

Vacuum circuit breakers (VCB) are commonly used in active mechanical direct current circuit breakers (DC CBs) to accomplish the interruption of the fault current. The post-arc current phenomenon of a VCB is related to the dielectric recovery process of the VCB. Thus, we performed experiments to investigate the influence on the post-arc current by taking the electrode separation, breaking current, and interruption of the bi-directional current with the injecting high frequency current in a fixed direction into account. To be in accordance with the practical interruption duty, the breaking current in the experiment ranges from 500 A to 20 kA. At the same time, the di/dt at current zero (CZ) varies between 200 and 1100 A/μs. The experiment results reveal that the peak value of the post-arc current in an active DC circuit breaker can reach more than 100 A with high di/dt at CZ. It is found that with a longer electrode separation, not only the residual charge increases but also the post-arc current increases. The arcing current before CZ can influence the post-arc current but the effective duration before CZ is short. This duration is the memory time and it is derived from the experiment results. The influence of the breaking current and interruption of the bi-directional current with the injecting current in a fixed direction are dependent on the relation of the current commutation time with the memory time.
Whole‐body kinematics during a simulated sprint in flat‐water kayakers
Authors: Bertozzi Filippo , Porcelli Simone , Marzorati Mauro , Pilotto Andrea M. , Galli Manuela , Sforza Chiarella , Zago Matteo 
Published: May 2021

ABSTRACTSuccess in sprint kayaking depends on the propulsive power generated by trunk, pelvis, shoulder and lower limb movements. However, no studies have examined whole‐body kinematics over a simulated distance. We aimed to study the changes in movement patterns of kayakers performing a 500‐m kayak sprint. Eleven young K1 sprint kayakers (three females; age: 16.5 ± 1.9 years, height: 174.1 ± 7.1 cm and weight: 66.1 ± 6.2 kg) performed an incremental test on a kayak ergometer to assess their Peak Oxygen Uptake (V̇O2peak). They then performed a 500‐m sprint trial on the same ergometer, and the positions of 40 reflective markers were recorded to assess whole‐body kinematics. Joint angles over time were computed for the trunk and right shoulder, hip, knee, and ankle. Changes of joint kinematics during the test were assessed with Statistical Parametric Mapping, calculating at each time node the linear regression between joint angles waveforms and the time of the rowing cycle, p < .05. Cardiometabolic responses confirmed that the participants achieved a maximal effort (V̇O2 and HR reached 99 ± 11% and 94 ± 6% of peak values, respectively). Paddle velocity negatively correlated with sprint time. The shoulder (elevation, rotation and flexion), trunk (lateral flexion and rotation) and hip (abduction) angles significantly changed over time in different phases of the stroke cycle during the simulated sprint. No significant differences over time were found for knee and ankle flexion. A high‐intensity sprint may affect the shoulder, trunk and hip kinematics of kayak paddling. The kinematic analysis of kayakers’ paddling during simulated metabolic‐demanding tasks can provide useful insights to coaches and athletes.
Design and 3D printing of paper-based shape memory polymer actuated for soft lightweight fingers
Authors: Chen Chin-Tai , Peng Ruo-Ciao 
Published: May 2021

Abstract
Smart materials and devices that possess multiple functions of sensing and actuation have been investigated over decades as being exploited for soft robots in various applications such as artificial muscles, biomimetic actuators, and surgical tools. One of critical requirements involved is the capability of dramatic change in shape and size to be adapted for different circumstances. Recent progress of the emerging materials has showed many remarkable properties to fabricate them in simple way. This paper reports a fused deposition modeling (FDM) method that can be simply implemented by three-dimensional (3D) printing shape memory polymer (SMP) on paper. Through 3D printing of a SMP filament on paper, the bilayer structures and grippers with a starfish shape were fabricated by exploiting the cost-effective and lightweight materials. By virtue of electrothermal actuation (Joule heating) with an electrical power supply, they showed remarkable and reversible change in shape during 100 cycles of movements. As a result, it demonstrated the capability of control over adaptive shape and size in design and fabrication of soft robots. The FDM-based method in the study is therefore beneficial to extend the flexibility in design and fabrication, as compared to the conventional ones particularly applied for rigid grippers. In the near future, a variety of multi-layer structures and materials fabricated by FDM method and 3D printing materials could be applied for applications such as soft actuators and sensors in versatile conditions.