bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cross-country evidence on the association between contact tracing and COVID-19 case fatality rates
Authors: Yalaman Abdullah , Basbug Gokce , Elgin Ceyhun , Galvani Alison P. 
Published: January 2021

AbstractThe coronavirus disease (COVID-19) outbreak has killed over a million people since its emergence in late 2019. However, there has been substantial variability in the policies and intensity of diagnostic efforts between countries. In this paper, we quantitatively evaluate the association between national contact tracing policies and case fatality rates of COVID-19 in 138 countries. Our regression analyses indicate that countries that implement comprehensive contact tracing have significantly lower case fatality rates. This association of contact tracing policy and case fatality rates is robust in our longitudinal regression models, even after controlling for the number of tests conducted and non-pharmaceutical control measures adopted by governments. Our results suggest that comprehensive contact tracing is instrumental not only to curtailing transmission but also to reducing case fatality rates. Contact tracing achieves the early detection and isolation of secondary cases which are particularly important given that the peak in infectiousness occurs during the presymptomatic phase. The early detection achieved by contact tracing accelerates the rate at which infected individuals receive medical care they need to maximize their chance of recovery. In addition, the combination of reduced transmission and more rapid recovery diminishes the burden on the healthcare system which in turn ensures that the resources remain available for individuals who do become infected.
Modelling the impact of tailored behavioural interventions on chlamydia transmission
Authors: van Wees Daphne A. , den Daas Chantal , Kretzschmar Mirjam E. E. , Heijne Janneke C. M. 
Published: January 2021

AbstractBehavioural interventions tailored to psychological characteristics of an individual can effectively achieve risk-reducing behaviour. The impact of tailored interventions on population-level chlamydia prevalence is unknown. We aimed to assess the impact on overall chlamydia prevalence five years after the introduction of an intervention aimed at increasing self-efficacy, social norms, attitudes and intentions towards condom use (i.e., condom intervention), and an intervention aimed at increasing health goals and decreasing impulsiveness (i.e., impulsiveness intervention). A pair model, informed by longitudinal psychological and behavioural data of young heterosexuals visiting sexual health centers, with susceptible-infected-susceptible structure was developed. The intervention effect was defined as an increased proportion of each subgroup moving to the desired subgroup (i.e., lower risk subgroup). Interventions tailored to subgroup-specific characteristics, assuming differential intervention effects in each subgroup, more effectively reduced overall chlamydia prevalence compared to non-tailored interventions. The most effective intervention was the tailored condom intervention, which was assumed to result in a relative reduction in chlamydia prevalence of 18% versus 12% in the non-tailored scenario. Thus, it is important to assess multiple psychological and behavioural characteristics of individuals. Tailored interventions may be more successful in achieving risk-reducing behaviour, and consequently, reduce chlamydia prevalence more effectively.
Restoration of breathing after opioid overdose and spinal cord injury using temporal interference stimulation
Authors: Sunshine Michael D. , Cassarà Antonino M. , Neufeld Esra , Grossman Nir , Mareci Thomas H. , Otto Kevin J. , Boyden Edward S. , Fuller David D. 
Published: January 2021

AbstractRespiratory insufficiency is a leading cause of death due to drug overdose or neuromuscular disease. We hypothesized that a stimulation paradigm using temporal interference (TI) could restore breathing in such conditions. Following opioid overdose in rats, two high frequency (5000 Hz and 5001 Hz), low amplitude waveforms delivered via intramuscular wires in the neck immediately activated the diaphragm and restored ventilation in phase with waveform offset (1 Hz or 60 breaths/min). Following cervical spinal cord injury (SCI), TI stimulation via dorsally placed epidural electrodes uni- or bilaterally activated the diaphragm depending on current and electrode position. In silico modeling indicated that an interferential signal in the ventral spinal cord predicted the evoked response (left versus right diaphragm) and current-ratio-based steering. We conclude that TI stimulation can activate spinal motor neurons after SCI and prevent fatal apnea during drug overdose by restoring ventilation with minimally invasive electrodes.
Chondroitin 6-sulfate represses keratinocyte proliferation in mouse skin, which is associated with psoriasis
Authors: Kitazawa Kazuyuki , Nadanaka Satomi , Kadomatsu Kenji , Kitagawa Hiroshi 
Published: January 2021

AbstractChondroitin sulfates are implicated in epidermal biology, but functional significance of chondroitin sulfates remains unclear. Here, we report that chondroitin 6-sulfate is important for the maintenance of epidermal homeostasis. Mice deficient in chondroitin 6-O-sulfotransferase-1 (C6st-1), which is involved in biosynthesis of chondroitin 6-sulfate, exhibited keratinocyte hyperproliferation and impaired skin permeability barrier function. Chondroitin 6-sulfate directly interacted with the EGF receptor and negatively controlled ligand-induced EGF receptor signaling. Normal function of hyperproliferative C6st-1-knockout mouse-derived keratinocytes was rescued by treatment with exogenous chondroitin 6-sulfate. Epidermal hyperplasia, induced using imiquimod, was more severe in C6st-1-knockout mice than in C6st-1 wild-type mice. Taken together, these findings indicate that chondroitin 6-sulfate represses keratinocyte proliferation in normal skin, and that the expression level of C6st-1 may be associated with susceptibility to psoriasis.
Porphyromonas gingivalis fimbrial protein Mfa5 contains a von Willebrand factor domain and an intramolecular isopeptide
Authors: Heidler Thomas V. , Ernits Karin , Ziolkowska Agnieszka , Claesson Rolf , Persson Karina 
Published: January 2021

AbstractThe Gram-negative bacterium Porphyromonas gingivalis is a secondary colonizer of the oral biofilm and is involved in the onset and progression of periodontitis. Its fimbriae, of type-V, are important for attachment to other microorganisms in the biofilm and for adhesion to host cells. The fimbriae are assembled from five proteins encoded by the mfa1 operon, of which Mfa5 is one of the ancillary tip proteins. Here we report the X-ray structure of the N-terminal half of Mfa5, which reveals a von Willebrand factor domain and two IgG-like domains. One of the IgG-like domains is stabilized by an intramolecular isopeptide bond, which is the first such bond observed in a Gram-negative bacterium. These features make Mfa5 structurally more related to streptococcal adhesins than to the other P. gingivalis Mfa proteins. The structure reported here indicates that horizontal gene transfer has occurred among the bacteria within the oral biofilm.
Design and optimisation of dendrimer-conjugated Bcl-2/xL inhibitor, AZD0466, with improved therapeutic index for cancer therapy
Authors: Patterson Claire M. , Balachander Srividya B. , Grant Iain , Pop-Damkov Petar , Kelly Brian , McCoull William , Parker Jeremy , Giannis Michael , Hill Kathryn J. , Gibbons Francis D. , Hennessy Edward J. , Kemmitt Paul , Harmer Alexander R. , Gales Sonya , Purbrick Stuart , Redmond Sean , Skinner Matthew , Graham Lorraine , Secrist J. Paul , Schuller Alwin G. , Wen Shenghua , Adam Ammar , Reimer Corinne , Cidado Justin , Wild Martin , Gangl Eric , Fawell Stephen E. , Saeh Jamal , Davies Barry R. , Owen David J. , Ashford Marianne B. 
Published: January 2021

AbstractDual Bcl-2/Bcl-xL inhibitors are expected to deliver therapeutic benefit in many haematological and solid malignancies, however, their use is limited by tolerability issues. AZD4320, a potent dual Bcl-2/Bcl-xL inhibitor, has shown good efficacy however had dose limiting cardiovascular toxicity in preclinical species, coupled with challenging physicochemical properties, which prevented its clinical development. Here, we describe the design and development of AZD0466, a drug-dendrimer conjugate, where AZD4320 is chemically conjugated to a PEGylated poly-lysine dendrimer. Mathematical modelling was employed to determine the optimal release rate of the drug from the dendrimer for maximal therapeutic index in terms of preclinical anti-tumour efficacy and cardiovascular tolerability. The optimised candidate is shown to be efficacious and better tolerated in preclinical models compared with AZD4320 alone. The AZD4320-dendrimer conjugate (AZD0466) identified, through mathematical modelling, has resulted in an improved therapeutic index and thus enabled progression of this promising dual Bcl-2/Bcl-xL inhibitor into clinical development.
PRMT3 interacts with ALDH1A1 and regulates gene-expression by inhibiting retinoic acid signaling
Authors: Verma Mamta , Khan Mohd. Imran K. , Kadumuri Rajashekar Varma , Chakrapani Baskar , Awasthi Sharad , Mahesh Arun , Govindaraju Gayathri , Chavali Pavithra L , Rajavelu Arumugam , Chavali Sreenivas , Dhayalan Arunkumar 
Published: January 2021

AbstractProtein arginine methyltransferase 3 (PRMT3) regulates protein functions by introducing asymmetric dimethylation marks at the arginine residues in proteins. However, very little is known about the interaction partners of PRMT3 and their functional outcomes. Using yeast-two hybrid screening, we identified Retinal dehydrogenase 1 (ALDH1A1) as a potential interaction partner of PRMT3 and confirmed this interaction using different methods. ALDH1A1 regulates variety of cellular processes by catalyzing the conversion of retinaldehyde to retinoic acid. By molecular docking and site-directed mutagenesis, we identified the specific residues in the catalytic domain of PRMT3 that facilitate interaction with the C-terminal region of ALDH1A1. PRMT3 inhibits the enzymatic activity of ALDH1A1 and negatively regulates the expression of retinoic acid responsive genes in a methyltransferase activity independent manner. Our findings show that in addition to regulating protein functions by introducing methylation modifications, PRMT3 could also regulate global gene expression through protein-protein interactions.
DFC: Device‐free human counting through WiFi fine‐grained subcarrier information
Authors: Jeong Jaehoon (Paul) , Shen Yiwen , Kim Seokhwa , Choe Daegeun , Lee Keuntae , Kim Yongserk 
Published: January 2021

AbstractA device‐free human counting (DFC) algorithm that uses fine‐grained subcarrier information from WiFi devices, called channel state information (CSI), to count the number of people in indoor environments is proposed. The DFC algorithm extracts the features of average attenuation and variation of CSI amplitudes caused by human motions, and puts the features into a training process to improve the counting accuracy. Through a bootstrapping process, the DFC can estimate the number of people standing in the middle of a WiFi link by constructing a probability model with the CSI signals at a receiver side. With this human counting capability, the DFC can support the efficient monitoring and automatic control of electrical devices (e.g. air conditioner, heater, bulb, and beam projector) indoors. Through a real implementation and experiments, it is shown that the DFC algorithm outperforms the state‐of‐the‐art DFC algorithm based on RSSI in indoor environments with human mobility. For a dynamic‐target case in a meeting room, for example, DFC can predict the number of people in an indoor space with an accuracy about 98% at best.
Image denoising based on BCOLTA: Dataset and study
Authors: Han Lili , Li Shujuan , Liu Xiuping 
Published: January 2021

AbstractRobot deburring is an effective method for improving the surface quality of the high‐voltage copper contact. The first step of robot deburring is to acquire the burr images. We propose a new burr mathematical model and build a real burr image dataset for burr image denoising. In order to improve burr image denoising effects of the high‐voltage copper contact, this study proposes an online burr image denoising algorithm, that is, block cosparsity overcomplete learning transform algorithm (BCOLTA). The penalty term and the condition number are affected by the burr parameter. The clustering and transform alternate minimisation algorithms are adopted to achieve lower computational cost and better denoising effect. In addition, BCOLTA also has a good adaptibility to inherent noise images, especially in Gaussian noise. Compared with other traditional and deep learning algorithms by no reference and full reference image quality assessment methods, BCOLTA has state‐of‐the‐art denoising effects and computational complexity on dealing with burr images. This research will play an important role in the intelligent manufacturing field.
An assessment of a unmanned aerial vehicle‐based broadcast scenario assuming random terrestrial user locations
Authors: Vaiopoulos Nicholas , Vavoulas Alexander , Sandalidis Harilaos G. 
Published: January 2021

AbstractWith the advent of the new decade, unmanned aerial vehicles (UAVs) will increasingly play an active role mainly as broadband transmission relays for broadcast applications. In the present study, we consider a feasible network where a transmitter, mounted on a hill, is connected through an optical wireless link with a UAV, hovering at a certain height above the earth. The UAV provides coverage over a circular geographic area and communicates through a radio frequency (RF) link with a ground user who is randomly located inside the circular region. In this context, a mixed optical/RF link is established where the performance is thoroughly investigated in terms of the outage probability. We assume that the optical wireless link is affected by a plethora of deteriorating factors, including the presence of fog, or the atmospheric scintillation, while the RF link is subject to small‐scale fading. Depending on the appearance of fog or turbulence, two different problems occur with a different mathematical formulation. For both cases, we extract closed‐form expressions for the signal‐to‐noise ratio statistics, which are the critical component towards determining the outage probability. Then, the impact of the impairments for some typical parameter values is properly depicted in appropriate graphs.
Semiconductor racetrack resonator coupled to an S‐bent waveguide: Influence of the coupling coefficients on the unidirectional operation
Authors: Giannuzzi Giuseppe , Bardella Paolo 
Published: January 2021

AbstractSemiconductor ring lasers have attracted remarkable interest as laser sources in photonic integrated circuits. They result in bidirectional laser owing to the rotation symmetry between the two counter‐propagating modes of the ring cavity. This symmetry can be broken embedding an S‐bend waveguide in the racetrack resonator, which generates an unbalanced loss mechanism and a non‐reciprocal gain between clockwise and counter‐clockwise direction beams. The propagating field along the resonator in the undesirable direction is evanescently coupled to the S element in correspondence of two coupling regions and converted into the preferred one. The authors examined how the field coupling coefficients of the couplers impact the resonator unidirectionality. In numerical simulations, the authors changed the coupler gap distance and the coupler length of the directional couplers to scan the full range of variability of the coefficients. The simulated performances of the resonator are discussed in terms of the extinction ratio between the clockwise and the counter‐clockwise modes as well as the power truly circulated in the two directions of the resonator net of all losses. The finite‐difference time‐domain method within Synopsys RSoft© suite was used to simulate the evolution of the counter‐propagating field along the racetrack.
Passive MIMO radar detection in the presence of clutter or multi‐path without reference channel
Authors: Fazlollahpoor Mohammad , Derakhtian Mostafa , Khorshidi Shapour 
Published: January 2021

AbstractTarget detection problem in a multiple‐input multiple‐output (MIMO) radar which includes non‐cooperative illuminators of opportunity (IOs) and spatially distributed receivers is discussed. The receivers utilize only one processing channel and discard the difficulties in providing an ideal version of the transmitted waveforms. The signal model, in addition to the receiver noise and the possible echo from the target of interest, considers the direct‐path and clutter/multi‐path interferences (DPI and MPI). A Rao test and an approximated GLR test detectors are proposed to solve the problem and an innovative recursive algorithm is proposed to simultaneously estimate the nuisance parameters in the test. Then, by regarding some matrix properties in the proposed Rao detector expression, a low complexity version of the Rao detector is proposed. Besides, two detectors based on Rao and GLR principles in the case of active MIMO radar are introduced as the performance upper‐bounds for the proposed detectors. The convergence and suitable performance of the proposed detectors are verified by numerical simulations.
Coherent compensation and high‐resolution technology of multi‐band inverse synthetic aperture radar fusion imaging
Authors: Zhu Xiaoxiu , Liu Limin , Guo Baofeng , Hu Wenhua , Ma Juntao , Shi Lin 
Published: January 2021

AbstractMulti‐band inverse synthetic aperture radar (ISAR) fusion imaging technology can effectively improve the range resolution without incurring high hardware cost. The coherent phase between sub‐bands is a prerequisite to achieve multi‐band ISAR fusion imaging. Here, a joint approach of coherent compensation and high‐resolution imaging is proposed to compensate the incoherent phase and obtain high‐resolution ISAR fusion images. First, an incoherent phase estimation model based on sparse representation is established, and the phase estimation accuracy is improved by a modified coherent dictionary in case of off‐grid. Then, a multi‐band ISAR fusion imaging model based on sparse representation is established. The complex Gaussian scale mixture priors and the complex Gaussian priors are imposed on the scatterers and noise, respectively. The solution is derived in the complex domain based on the variational Bayesian expectation maximization framework. The proposed method can not only achieve better incoherent phase compensation in the case of off‐grid, but also obtain high‐quality ISAR fusion images under low signal‐to‐noise ratio and low bandwidth sampling ratio. Experimental results verify the effectiveness and robustness of the proposed method based on both numerical simulations and real data.
APOGEE DR16: A multi-zone chemical evolution model for the Galactic disc based on MCMC methods
Authors: Spitoni E. , Verma K. , Silva Aguirre V. , Vincenzo F. , Matteucci F. , Vaičekauskaitė B. , Palla M. , Grisoni V. , Calura F. 
Published: January 2021

Context.The analysis of the latest release of the Apache Point Observatory Galactic Evolution Experiment project (APOGEE DR16) data suggests the existence of a clear distinction between two sequences of disc stars at different Galactocentric distances in the [α/Fe] versus [Fe/H] abundance ratio space: the so-called high-αsequence, classically associated with an old population of stars in the thick disc with high average [α/Fe], and the low-αsequence, which mostly comprises relatively young stars in the thin disc with low average [α/Fe].Aims.We aim to constrain a multi-zone two-infall chemical evolution model designed for regions at different Galactocentric distances using measured chemical abundances from the APOGEE DR16 sample.Methods.We performed a Bayesian analysis based on a Markov chain Monte Carlo method to fit our multi-zone two-infall chemical evolution model to the APOGEE DR16 data.Results.An inside-out formation of the Galaxy disc naturally emerges from the best fit of our two-infall chemical-evolution model to APOGEE-DR16: Inner Galactic regions are assembled on shorter timescales compared to the external ones. In the outer disc (with radiiR > 6 kpc), the chemical dilution due to a late accretion event of gas with a primordial chemical composition is the main driver of the [Mg/Fe] versus [Fe/H] abundance pattern in the low-αsequence. In the inner disc, in the framework of the two-infall model, we confirm the presence of an enriched gas infall in the low-αphase as suggested by chemo-dynamical models. Our Bayesian analysis of the recent APOGEE DR16 data suggests a significant delay time, ranging from ∼3.0 to 4.7 Gyr, between the first and second gas infall events for all the analysed Galactocentric regions. The best fit model reproduces several observational constraints such as: (i) the present-day stellar and gas surface density profiles; (ii) the present-day abundance gradients; (iii) the star formation rate profile; and (iv) the solar abundance values.Conclusions.Our results propose a clear interpretation of the [Mg/Fe] versus [Fe/H] relations along the Galactic discs. The signatures of a delayed gas-rich merger which gives rise to a hiatus in the star formation history of the Galaxy are impressed in the [Mg/Fe] versus [Fe/H] relation, determining how the low-αstars are distributed in the abundance space at different Galactocentric distances, which is in agreement with the finding of recent chemo-dynamical simulations.
Spectroscopy and polarimetry of the gravitationally lensed quasar Q0957+561
Authors: Popović L. Č. , Afanasiev V. L. , Shablovinskaya E. S. , Ardilanov V. I. , Savić Dj. 
Published: January 2021

Context. We present new spectroscopic and polarimetric observations of the first discovered gravitational lens, Q0957+561. The lensed quasar has been observed with the 6 m telescope of the Special Astrophysical Observatory (Russia) in polarimetric and spectroscopic modes.
Aims. We explore the spectropolarimetric parameters of the A and B components of Q0957+561 to investigate the innermost structure of gravitationally lensed quasars and explore the nature of polarization in lensed quasars. Additionally, we aim to compare their present-day spectral characteristics with previous observations in order to study long-term spectral changes.
Methods. We perform new spectral and polarization observations of the Q0957+561 A and B images. After observed data reduction, we analyse the spectral characteristics of the lensed quasar, comparing the spectra of the A and B images, as well as comparing previously observed image spectra with present-day ones. The polarization parameters of the two images are also compared. Furthermore, we model the macro-lens influence on the polarization of the images, representing the gravitational lens with a singular isothermal elliptical potential.
Results. We find that the brightness and the spectral energy distribution ratio of components A and B have changed over a long period. Polarization in the broad lines of components A and B show that equatorial scattering cannot be detected in this lensed quasar. We find wavelength-dependent polarization that may be explained as a combination of the polarization from the disc and the outflowing material. There is a significant difference between the polarization parameters of the A and B images: The B component shows a higher polarization rate and polarization angle. However, both polarization vectors are nearly perpendicular to the observed radio jet projection. This indicates that the polarization in the continuum comes from the accretion disc. Our simple lensing model of a polarized source shows that, in principle, macro lenses can cause the observed differences in the polarization parameters of the Q0957+561A and B images. Using the Mg II broad line and luminosity of component A, we estimate the Q0957+561 black hole mass to be MSMBH ≈ (4.8 − 6.1) × 108 M⊙.