bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of pneumococcal conjugate vaccine uptake on childhood pneumonia mortality across income levels in Brazil, Colombia, and Peru
Authors: Shioda Kayoko , Toscano Cristiana M. , Valenzuela Maria Tereza , Huarcaya William Valdez , Warren Joshua L. , Weinberger Daniel M. , de Oliveira Lucia H.
Published: September 2020

Background: Pneumococcal conjugate vaccines (PCVs) have prevented deaths due to pneumonia among children. The effect may differ between higher- and lower-income populations due to various factors, such as differences in the distribution of pneumococcal serotypes, healthcare access, and PCV uptake. This study aims to evaluate an association between increasing PCV coverage and population-level declines in death due to pneumonia and its variation by socioeconomic status of subnational regions.

Methods: We analyzed municipality-level mortality data from 2005 and 2015 for children aged 2-23 months in Brazil, Colombia, and Peru. We fit Poisson regression models to estimate the relationship between changes in PCV uptake and deaths due to all-cause pneumonia among subnational regions with different income levels. We controlled for changes unrelated to PCV by using data on non-respiratory deaths over time.

Results: Uptake of the third dose of PCV varied across subnational regions and was higher in high-income regions. Higher uptake of PCV was associated with larger declines in pneumonia mortality. This association did not differ by income level of the region in Brazil and Colombia. In Peru, low-income regions observed larger declines in pneumonia deaths, but there was large uncertainty in the difference between the low- and high-income regions. We estimated that, with 90% coverage, there would be 4-38% declines in all-cause pneumonia mortality across income levels and countries.

Conclusions: Regions with higher PCV coverage experienced larger declines in pneumonia deaths, regardless of the income level. Having more reliable data on mortality records and vaccine uptake would improve the reliability of vaccine impact estimates.
Rapid response and learning for later: establishing high quality information networks and evaluation frameworks for the National Ambulance Service response to COVID-19 – the ENCORE COVID Project Protocol
Authors: Masterson Siobhán , Heffernan Eithne , Keegan Dylan , Clarke Bridget , Deasy Conor , O'Donnell Cathal , Crowley Philip , Breen Roisin , Kelly Maureen E , Murphy Andrew W
Published: September 2020

Background: The National Ambulance Service (NAS) is at the forefront of Ireland’s response to the COVID-19 pandemic. As directed in Ireland’s National Action Plan, NAS significantly expanded prehospital services, including provision of a novel home and community COVID-19 testing service. Additionally, other health services rely on NAS’s capacity to assess, transport and/or treat COVID-19 patients. In a climate of innovation and adaptation, NAS needs to learn from international ambulance services and share experience. Evaluation of the NAS response to COVID-19 is required to facilitate evidence-based planning for subsequent waves or future pandemics, and to identify innovative practice for mainstreaming into routine service provision.

Aims: This project aims to provide information networks and evaluation tools that will help NAS meet these requirements.

Methods: The first aim will be to produce ambulance-specific research and information updates for NAS. Secondly, an international network of senior ambulance and research personnel will be established (‘AMBULANCE+COVID19’ network) and a short-survey instrument, the Emergency Medical Services Five Question Survey (EMS-5QS), will be developed. The EMS-5QS will enable AMBULANCE+COVID19 participants to nominate a topic for which they would like to hear about the experience and practice of other ambulance services. Multiple surveys covering a range of topics will be carried out. Finally, an evaluation framework will be developed to enable NAS determine innovations: (1) for reactivation in another wave or new pandemic; (2) to be sustained as part of routine service. The framework will be developed in collaboration with NAS and the Health Service Executive National Quality Improvement Team. The Research Team includes expertise from academia, ambulance services and the National Public Health Emergency Team.

Conclusions: Ability to mobilise resources quickly and utilise ready-made international networks will ensure a successful project than can inform future information sharing methodologies and pandemic planning for ambulance services internationally.
Tracking online searches for emotional wellbeing concerns and coping strategies in the UK during the COVID-19 pandemic: a Google Trends analysis
Authors: Knipe Duleeka , Evans Hannah , Sinyor Mark , Niederkrotenthaler Thomas , Gunnell David , John Ann
Published: September 2020

Background: The coronavirus disease 2019 (COVID-19) pandemic is the largest acute public health emergency of this century. Government intervention to contain the virus focuses on non-pharmacological approaches such as physical distancing/lockdown (stay-at-home orders). As the situation develops, the impact of these measures on mental health and coping strategies in individuals and the population is unknown.

Methods: We used Google Trends data (01 Jan 2020 to 09 Jun 2020) to explore the changing pattern of public concern in the UK to government measures as indexed by changes in search frequency for topics related to mental distress as well as coping and resilience. We explored the changes of specific topics in relation to key dates during the pandemic. In addition, we examined terms whose search frequency increased most.

Results: Following lockdown, public concerns - as indexed by relative search trends - were directly related to COVID-19 and practicalities such as ‘furlough’ (paid leave scheme for people in employment) in response to the pandemic. Over time, searches with the most substantial growth were no longer directly or indirectly related to COVID-19. In contrast to relatively stable rates of searches related to mental distress, the topics that demonstrated a sustained increase were those associated with coping and resilience such as exercise and learning new skills.

Conclusions: Google Trends is an expansive dataset which enables the investigation of population-level search activity as a proxy for public concerns. It has potential to enable policy makers to respond in real time to promote adaptive behaviours and deliver appropriate support.
Occupational Risk Model Application in Information Systems for Open-Pit Coal Mining Organizations
Authors: Kuleckiy K. , Zhunda S. , Rudakov M. , Sobyanin D.
Published: September 2020

Statistics and analysis related to industrial injuries at the enterprises for open-pit coal mining have been presented in this article. A method for formation a hazard register with an increased and critical risk levels during technological operations has been proposed. The necessity of digitalization for the industrial safety and labor protection system has been demonstrated.
LOW-POWER SOLAR FLARES OF OPTICAL AND X-RAY WAVELENGTHS FOR SOLAR CYCLES 21–24
Authors: Borovik Aleksandr , Zhdanov Anton
Published: September 2020

Using data obtained in optical and X-ray wavelengths, we have analyzed solar flare activity for cycles 21–24. Over the last three cycles, solar activity is shown to decrease significantly. As compared to solar cycle 21 (the most active over the last 50 years), in cycle 24 2–4-class large optical flares are 4.4 times rarer; 1-class flares, 8.2 times; and S-class small flares, 4.1 times. The number of X-class flares decreased 3.7 times; M-class flares, 3.2 times. This confirms that secular solar activity trends affect peak values of 11-year cycles. It is shown that optical low-power flares can be accompanied by proton fluxes and X-ray bursts of different intensity, including X-class ones. Ranges of small flare emission in soft X-rays largely overlap with emission ranges of flares of high optical classes. We have confirmed that X-ray emission from solar flares appears on average 2 min before the optical emission. The X-ray maximum for small optical flares and 1-class flares occurs approximately 1 min later; for 2–4-class flares, 2 min.
AMPLITUDE VARIATIONS OF THE REFLECTED SIGNAL DURING VERTICAL SOUNDING OF THE IONOSPHERE AT MIDDLE LATITUDES
Authors: Yusupov Kamil , Mathews John , Maruyama Takashi , Akchurin Adel , Tolstikov Maksim , Sherstyukov Oleg , Filippova Elena , Safiullin Anvar
Published: September 2020

In this paper, we discuss the main types of quasiperiodic variations in amplitudes of a reflected signal during vertical sounding of the ionosphere at middle latitudes. The initial experimental data is vertical sounding ionograms obtained by the Cyclone ionosonde. The ionosonde is located in Kazan (59°, 49°) and in standard mode allows us to receive one ionogram per minute. In the analysis, methods are used to visualize a large flow of ionograms in the form of final summary maps of the state of the ionosphere (A-, H-, As-maps). We give typical examples of quasiperiodic variations in amplitudes of a reflected signal in ionograms and on A-maps for various types of multipath beatings (polarization and due to signal scattering by ionospheric irregularities). Frequency properties of such beatings are used to estimate the difference in virtual reflection heights between modes of different polarizations with high accuracy, which makes it possible to refine the form of the electron density profile of the lower ionosphere. We have detected a phenomenon rare for the mid-latitude Es layer — beatings of two O modes with different virtual reflection heights. We also present features of quasiperiodic variations in amplitudes of a reflected signal on traces of the transient Es layer. We study possible causes of the appearance of such beatings.
Coronal jets as a cause of microwave negative bursts
Authors: Kuzmenko Irina
Published: September 2020

We have investigated the cause of three “isolated” negative radio bursts recorded one after another at several frequencies in the 1–17 GHz range at the Nobeyama Radio Observatory, Ussuriysk Astrophysical Observatory, and Learmonth Solar Observatory on April 10–11, 2014. The cause of the rarely observed “isolated” negative bursts is the absorption of radio emission from the quiet Sun’s regions or a radio source in the material of a large eruptive filament. Analysis of observations in different spectral ranges using images from the Nobeyama radioheliograph and the Solar Dynamics Observatory/Atmospheric Imaging Assembly has shown that the cause of all the three radio emission depressions was the screening of the limb radio source by the material of recurrent coronal jets. Parameters of the absorbing material were estimated using a previously developed model. These estimates confirmed the absorption of solar radio emission in cold material with a temperature of ~104 K at the bottom of the jets.
Disturbed magnetosphere on November 7–8, 2004 and variations of cosmic ray cutoff rigidity: Latitude effects
Authors: Danilova Olga , Ptitsyna Natalia , Tyasto Marta , Sdobnov Valeriy
Published: September 2020

We have studied the latitude behavior of cosmic ray cutoff rigidity and their sensitivity to Bz and By components of the interplanetary magnetic field and geomagnetic activity indices Dst and Kp for different phases of the November 7–8, 2004 strong magnetic storm. Cutoff rigidities have been calculated using two methods: the spectrographic global survey method in which the cutoff rigidity is determined from observational data, acquired by the neutron monitor network, and the method in which particle trajectories are calculated numerically in a model magnetic field of the magnetosphere. We have found that the sensitivity of observed cutoff rigidities to Dst changes with latitude (threshold rigidity of stations) is in antiphase with changes in the sensitivity to By. During the recovery phase of the storm, the Dst correlation with By is significantly greater than that with Bz, and the Kp correlation with Bz is greater than that with By. The By component is shown to be a predominant driver of the current systems that determine the Dst evolution during the recovery phase.
Ultra low frequency emissions ranging from 0.1 to 3 Hz in circumpolar areas
Authors: Potapov Alexander , Guglielmi Anatol , Dovbnya Boris
Published: September 2020

We examine the characteristics of oscillations of two types in the high-frequency edge of the ULF range (0.1–3 Hz), serpentine emission (SE), and discrete frequency dispersed signals (DS). Oscillations of both the types are observed in the polar caps exclusively with induction magnetometers. Since these instruments are currently practically absent at high latitudes, the analysis has been carried out from records obtained at the stations Vostok and Thule close to the geomagnetic poles in 1968–1971. The DS occurrence rate is shown to have a sharp peak at local magnetic noon. This fact indicates that DS emergence is rigidly tied to the geomagnetic field line passing through the observation station. At the same time, the seasonal variation in the frequency of DS occurrence has a main peak in local summer and an additional peak in local winter. We have revealed before that at least a part of DS is excited in the foreshock region. Taking this into account, we can assume that the wave packets incident to the magnetopause fall on the external field lines mainly in the noon region and propagate along these lines in both directions, eventually reaching Earth’s surface in the polar regions. Unlike DS, the SE occurrence rate has neither a daily nor a seasonal variation. We have tested and confirmed indirectly the hypothesis put forward earlier about the excitation of SE by cyclotron instability of protons in the solar wind, simulating frequency variations in ion-cyclotron waves at different levels of interplanetary plasma perturbation and comparing the results with the SE frequency variations observed under similar conditions. We conclude that it is necessary to resume continuous observations of ULF emissions, using induction magnetometers installed in polar caps near the projections of cusps and near geomagnetic poles.
Lone Mothers' Employment Trajectories: A Longitudinal Mixed-method Study
Authors: Struffolino Emanuela , Bernardi Laura , Larenza Ornella
Published: September 2020

Using a mixed-method design, this study explores the heterogeneity in employment trajectories before and after the transition to lone parenthood in Switzerland. First, we perform sequence and cluster analysis on data from the Swiss Household panel to identify typical employment trajectories around the transition to lone parenthood, and then estimate their association with individual and household characteristics (N=462). Finally, we contrast these results with findings from a content analysis of narrative interviews with lone mothers residing in Switzerland (N=38), focusing on values and norms concerning work and care. We identify five employment patterns characterized by either an increase in labor supply (especially for those with more/older children) or by stability in or outside the labor market (for highly educated or younger mothers respectively). The analyses of the interviews provide insights on how employment opportunities and decisions differ by entry mode into lone parenthood, the post-separation relationship with the children’s father, and the ability to mobilize individual, social and institutional resources. The heterogeneity of employment trajectories calls for more attention to within-group differences rather than focusing exclusively on the divide between lone and coupled mothers. By identifying the multiplicity of factors shaping lone mothers’ decisions on their labor market participation, this work feeds into the literature suggesting that effective policies encouraging lone mothers’ labor-market participation should consider: (i) their normative priorities when facing work and care trade-offs, and (ii) the availability of informal and formal support.
Entre balões cheios e vazios: processos de subjetivação tecidos pelas relações de poder-saber no contexto universitário
Authors: Cruz Edileuza Santos do Nascimento , Ferreri Marcelo De Almeida
Published: September 2020

O objetivo deste artigo é abordar processos de subjetivação tecidos pelas relações de poder-saber no contexto universitário, no recorte da assistência estudantil, seguindo as pistas da experiência de si. Para tal, compartilhamos uma situação de vivência universitária, Entre balões cheios e vazios, narrativa tecida na rede de relações institucionais, e historiada com recursos da linguagem literária. A partir dela, acionamos a discussão de produção de subjetividade com as ideias de Michel Foucault sobre poder, tomado em sua positividade. A narrativa expõe modos de ser que se produzem marcados por entendimentos individualizantes, num processo de assujeitamento, pelas relações de poder-saber, as quais se situam numa dimensão que é coletiva, social e institucional.
Cuidado de si e formação ético-estético-política: contribuições foucaultianas a um processo de pesquisa
Authors: Castro Roney Polato de
Published: September 2020

O artigo tem como objetivo apresentar alguns dos modos como as teorizações foucaultianas afetaram um processo de pesquisa de doutorado em educação, com foco na formação docente, em uma disciplina do curso de Pedagogia que discute e problematiza as relações de gênero e sexualidades. A centralidade da argumentação apresenta as tentativas de aproximação com os últimos estudos de Michel Foucault sobre a ética e o cuidado de si. A noção foucaultiana de sujeito ético, que se constitui em práticas de si, de ação moral sobre si mesmo, foi uma ferramenta inquietante para pensar a formação docente com as atividades da disciplina, funcionando como um campo de constituição de sujeitos, ao instaurar relações das estudantes consigo mesmas, produzindo múltiplas subjetividades.
Análise arqueológica do discurso dos participantes: contribuições para a avaliação do plano estadual de educação no sistema penitenciário do Paraná
Authors: Bonatto Bruna Mayara , Brandalise Mary Ângela Teixeira
Published: September 2020

O objetivo deste artigo consiste na exposição da contribuição da Análise Arqueológica do Discurso – AAD, fundamentada em Foucault (2012), no processo de avaliação do Plano Estadual de Educação no Sistema Prisional do Paraná (PARANÁ, 2012; 2015) no contexto das penitenciárias femininas de regime fechado. O emprego da análise arqueológica demonstra-se pertinente quando aplicado às pesquisas de avaliação de políticas educacionais centradas nos participantes ao possibilitar a aferição da influência da atuação dos sujeitos na atribuição social da política, bem como ao gerar reflexões capazes de aperfeiçoá-la de acordo com as especificidades do contexto e da população às quais se destinam, lhes atribuindo um caráter democrático.
Narrar experiência(s): Construir sentidos sobre o formar-se professor
Authors: Guimarães Heriédna Cardoso
Published: September 2020

Neste texto apresento um relato de experiência que intenciona ratificar a potencialidade das narrativas de histórias de vida e formação no desenvolvimento de processos de formação de professores e na construção de pesquisas que investigam os modos como os sujeitos professores se formam. Inicio propondo que as narrativas de experiências de vida e formação são potentes para a emersão dos imbricamentos entre vida e formação e desse modo recorro as contribuições da Pesquisa (Auto)Biográfica como modo de conexão entre as narrativas e os processos de formação. Sequencio apresentando a narrativa de uma experiência que vivi ao cursar uma disciplina eletiva ofertada por um Programa de Pós-Graduação em Educação de uma universidade federal, localizada no estado do Rio de Janeiro. Emergem desta escrita/narrativa reflexões que nos possibilitam olhar os formatos engessados de formação que experienciamos e como estes se perpetuam no nosso modo de produzir conhecimento e ser professor, identificado, neste texto, como o escrito-repetido-do-lido.
Apophatic Language, the Aesthetic, and the Sensus Divinitatis
Authors: Chung Julianne N.
Published: September 2020

Across a variety of religious and philosophical traditions, it is common to think that it is possible that God defies all description. This presents a problem, however, as the claim that God defies all description itself appears to describe God. Drawing on multiple religious and philosophical traditions, this paper proposes an addition to the pragmatic stock of approaches to this problem. The proposal is that apophatic utterances are best interpreted—at least in the first instance—as invitations to engage the world aesthetically and creatively, as an act of faith. Their goal is principally to motivate us to act in ways that will allow us to appreciate the extraordinary or divine, rather than to, say, believe that some proposition regarding the extraordinary or divine is true (even if we might come to accept, and perhaps even believe, propositions as a result of our appreciative actions).
Michael W. Austin. Humility and Human Flourishing: A Study in Analytic Moral Theology
Authors: Dunnington Kent
Published: September 2020

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Design and Test of a Double-Curved Guiding Groove for a High-Speed Precision Seed-Metering Device
Authors: Xue Pan , Hao Yujun , Jiao Wan , Ren Jie , Yang Feifei , Ren Di , Zhang Wenhui , Rong Hao , Hu Bin , Huang Yuxiang
Published: September 2020

Highlights

The instability of the seed release point in a seed-metering device is proved theoretically.

A double-curved guiding groove at the seed-release point improves the seed-metering uniformity.

A discrete element model was used to examine effects of the design parameters on the metering performance.

The critical parameters for the double-curved guiding groove design were determined.

Abstract. The instability of the seed release point in a seed-metering device is one of the main causes of the non-uniformity of seed spacing. To improve the seed spacing uniformity, a double-curved guiding groove (DGG) was designed based on the prerelease adaptive principle. The DGG was used at the seed release point of an existing high-speed precision soybean seed-metering device with a double-setting plate. The results showed that the prerelease curved surface of the DGG was capable of guiding seeds to be released at the same seed release point at all times, and the adaptive curved surface of the DGG prevented any changes in seed velocity caused by friction or collisions between seeds and the meter, thereby improving the seed spacing uniformity significantly. A discrete element model was developed and validated with laboratory tests. Through simulations using the model, the primary and secondary factors of the DGG impacting the qualified rate of seed metering (QRM) and the coefficient of variation of the seed spacing uniformity (CVU) were identified and were, in descending order, the spacing of prerelease (SPR), the starting position of prerelease (SPP), the inclination angle of the seed outlet (ASO), and the inclination angle of the receiving cup (ABR). Regression equations of the QRM and CVU with the two main impacting factors were then established. For a planter travel speed of 10 km h-1, the optimal SPR was 10 mm, and the optimal SPP was 40°, where the QRM was 100% and the CVU was 16.61%. When compared to seed metering without the DGG, the CVU was reduced by 2.55%, showing that the DGG significantly improved the uniformity of seed spacing. Keywords: Double-curved guiding groove, Discrete element method, Seed-metering device, Travel speed, Uniformity.
Evaluation of Two Recurrent Neural Network Methods for Prediction of Irrigation Rate and Timing
Authors: Jiménez Andrés F. , Ortiz Brenda V. , Bondesan Luca , Morata Guilherme , Damianidis Damianos
Published: September 2020

Highlights

NARX and LSTM recurrent neural networks were evaluated for prediction of irrigation prescriptions.

LSTM neural networks presented the best performance for irrigation scheduling using soil matric potential sensors.

NARX neural networks had the best performance for predicting irrigation prescriptions using weather data.

High performance for several time-ahead predictions using both recurrent neural networks, with R2 > 0.94.

The results can be adopted as a decision-support tool in irrigation scheduling for fields with different types of soils.

Abstract. The implementation of adequate irrigation strategies could be done through real-time monitoring of soil water status at several soil depths; however, this could also represent a complex nonlinear problem due to the plant-soil-weather relationships. In this study, two recurrent neural network (RNN) models were evaluated to estimate irrigation prescriptions. Data for this study were collected from an on-farm corn irrigation study conducted between 2017 and 2019 in Samson, Alabama. The study used hourly data of weather and soil matric potential (SMP) monitored at three soil depths from 13 sensor probes installed on a loamy fine sand soil and a sandy clay loam soil. Two neural network methods, i.e., a nonlinear autoregressive with exogenous (NARX) input system and long short-term memory (LSTM), were trained, validated, and tested with a maximum dataset of 20,052 records and a maximum of eight categorical attributes to estimate one-step irrigation prescriptions. The performance of both methods was evaluated by varying the model development parameters (neurons or blocks, dropout, and epochs) and determining their impact on the final model prediction. Results showed that both RNN models demonstrated good capability in the prediction of irrigation prescriptions for the soil types studied, with a coefficient of determination (R2) > 0.94 and root mean square error (RMSE) < 1.2 mm. The results of this study indicate that after training the RNNs using the dataset collected in the field, models using only SMP sensors at three soil depths obtained the best performance, followed by models that used only data of solar radiation, temperature, and relative humidity in the prediction of irrigation prescriptions. For future applicability, the RNN models can be extended using datasets from other places for training, which would allow the adoption of a unique data-driven soil moisture model for irrigation scheduling useful in a wide range of soil types. Keywords: Corn, Irrigation scheduling, Machine learning, Modeling, Soil matric potential sensor.
Moving toward Sustainable Irrigation in a Southern Idaho Irrigation Project
Authors: Bjorneberg David L. , Ippolito James A. , King Bradley A. , Nouwakpo S. Kossi , Koehn Anita C.
Published: September 2020

Highlights

Private and public irrigation development was important for expanding agricultural production in the western U.S.

The Twin Falls Canal Company is an excellent example of a successful Carey Act project.

Cooperative efforts during the last 30 years have dramatically improved the water quality of irrigation return flow.

Electricity generated by six hydroelectric facilities improves the sustainability of the irrigation project.

Abstract. Private and public irrigation development projects were fundamental to bringing irrigation to arid regions of the western U.S. The Twin Falls Canal Company in southern Idaho provides a case study of private and public irrigation development because the project was developed by private investors under the Carey Act and receives a portion of its irrigation water supply from U.S. Bureau of Reclamation reservoirs. The project survived initial financial struggles and waterlogged soil to focus on sustaining crop production by reducing chronic furrow irrigation erosion and nutrient losses in irrigation return flow. Average sediment loss from the project was 460 kg ha-1 in 1970. A cooperative effort by the canal company, state and federal agencies, and farmers improved water quality by installing sediment ponds on fields, applying polyacrylamide with furrow irrigation, converting from furrow to sprinkler irrigation, and constructing water quality ponds on irrigation return flow streams. From 2006 to 2018, more sediment and total phosphorus flowed into the watershed than returned to the Snake River, and the project removed 13,000 Mg of sediment and 30 Mg of total phosphorus from the Snake River each year. However, nitrate-N from subsurface drainage was lost at 10 kg ha-1 each year, or 800 Mg year-1, for the entire watershed. While sediment and phosphorus concentrations in irrigation return flow have decreased, these concentrations were still greater than the irrigation water, indicating that more can be done to reduce the project’s influence on water quality in the Snake River. Keywords: Nitrogen, Phosphorus, Sediment, Soluble salts, Water quality.
Ultra-high birefringent low loss suspended elliptical core photonic
crystal fiber for terahertz applications
Authors: Sadath Md. Anwar , Saiful Islam Mohammad , Hossain Md. Sanwar , Faisal Mohammad
Published: September 2020

This paper presents a low loss suspended core microstructured fiber
with ultra-high birefringence for terahertz wave guidance. The finite
element method (FEM) with a perfectly matched layer is applied to
investigate different important properties including effective
material loss (EML), birefringence, dispersion, confinement loss, and
percentage of power flow through the core. The suspended elliptical
core in the design creates asymmetry and results in an unprecedented
value of birefringence. The simulated results using FEM at 1 THz show
an extremely ultra-high birefringence (the highest, to the best of our
knowledge) of 0.1116, a nominal EML of , a negligible confinement loss of , a higher power fraction in the core
air of 35%, and an effective modal area of . The advancement in technology makes
the fabrication possible. The proposed fiber could be used
satisfactorily in the terahertz regime for various
polarization-preserving applications and coherent communication.
Enhanced terahertz modulation using a plasmonic perfect absorber based on black phosphorus
Authors: Wang Shuqi , Li Shuangluan , Zhou Yuanguo , Huang Jianping , Ren Qiang , Zhuo Jianming , Cai Yijun
Published: September 2020

In this paper, we design a plasmonic perfect absorber based on black phosphorus (BP) with enhanced terahertz modulation. By tuning the chemical potential (

μ
c

) of BP, the modulation depth can reach up to 95%. The influence of geometric size and bandgap of BP on reflection spectra is also investigated. Moreover, the effect of the incident angle on the reflectance is discussed with different values of

μ
c

. Our results show that the plasmonic nanoslit mode contributes to the enhancement of the modulation effect. This simple periodical structure provides a potential route to design a tunable plasmonic BP-based modulator in the THz range.
Numerical analysis on a viewing angle enhancement of a digital hologram by attaching a pixelated random phase mask
Authors: Choi Woo-Young , Lee Chang-Joo , Kim Bum-Su , Oh Kwan-Jung , Hong Keehoon , Choo Hyon-Gon , Park Jisun , Lee Seung-Yeol
Published: September 2020

In a digital hologram, the maximum viewing angle of a
computer-generated hologram (CGH) is limited by pixel pitch due to the
diffraction grating equation. Since reducing pixel size of display
panel is challenging and costly, we propose a method to expand the
viewing angle of a digital hologram by attaching an aligned pixelated
random phase mask (PRPM) onto the CGH pattern based on analysis of
simulation results. By introducing a phase-averaging process to the
widely used iterative Fourier transform algorithm, an optimized CGH
pattern can be obtained in conjunction with a PRPM. Based on scalar
diffraction theory, viewing angle enhancement characteristics were
verified by comparing the perspective views of a two-plane hologram
using a virtual eye model. In addition, we performed full
electromagnetic simulations that included effects due to potential
fabrication errors such as misalignment, thickness variation, and
internal reflections and diffractions between the CGH and random mask
patterns. From the simulation results, by attaching a 1.85 µm-sized
pixel pitch PRPM to a 3.7 µm CGH, the viewing angle can be easily
expanded almost identical to that of a CGH with 1.85 µm-pixel
pitch.
Dark soliton steering in PT-symmetric couplers with third-order and intermodal dispersions
Authors: Mahato Dipti Kanika , Govindarajan A. , Sarma Amarendra K.
Published: September 2020

We demonstrate steering dynamics of dark solitons in a parity–time (

P

T

)-symmetric nonlinear directional coupler (NLDC) in the presence of third-order dispersion (TOD) and intermodal dispersion (IMD). A complete switch with an excellent efficiency at a very low critical power, even lower compared to the bright soliton switching, has been observed. The numerical results show that both TOD and IMD have no effect on soliton steering in

P

T

-symmetric couplers with coupling length

π

/

2

. But, as we increase the coupling length to

2
π

, IMD shows marginal effects for dark soliton steering in

P

T

-symmetric couplers, while TOD shows no impact. Additionally, we have also studied the phase-controlled switching in

P

T

-symmetric couplers with two different coupling lengths and demonstrated its advantage over the power-controlled one.
Hyperbolic metamaterial-based metal–dielectric resonator-antenna designs for GHz photon collection rates from wide-range solid-state single-photon sources
Authors: Ahmed Nadeem , Akhtar Saba , Inam Faraz A.
Published: September 2020

Solid-state single-photon sources (SPS) based on quantum dots as well as color centers in diamonds and silicon-carbide have promise for application in emerging quantum technologies. Many of these technologies, however, demand photon rates in the GHz range, thereby hindering the use of these SPS, for which the maximum observed count rates are limited to a few tens of MHz. Here we first study the performance of hyperbolic metamaterial-based 5-layered metal–dielectric resonator antenna structures with metallic as well as hybrid metal–dielectric antennas in the wavelength range of 600 to 1000 nm. The performance of these resonator-antenna structures was analyzed for the Purcell enhancement, quantum efficiency (QE), collection efficiency (CE), and normalized collected photon counts (NCPC). The hybrid metal–dielectric antenna helps in providing the directivity to the dipole emission, thereby significantly improving the collection efficiency. We then present the novel design of a 5-layered metal–dielectric pillar resonator. This resonator structure with a metallic cylindrical antenna over the top showed significantly large fluorescence enhancement values. The Purcell factor was observed to reach close to 1600 at 680 nm corresponding to the central peak of the nitrogen vacancy center spectrum. The NCPC value reached close to 550 at 680 nm. The maximum CE from the structure was observed to be around 60%, with the maximum QE reaching close to 80%. With the above performance, the detected photon count rates for a solid-state SPS is expected to be well into the GHz range. Our designs show a state-of-the-art improvement in the antenna performance for SPS with properties very close to a practical SPS.
Method for reconstructing a high dynamic range image based on a single-shot filtered low dynamic range image
Authors: Liang Bin , Weng Dongdong , Bao Yihua , Tu Ziqi , Luo Le
Published: September 2020

Traditional cameras are limited by sensors and cannot directly capture single-shot high dynamic range (HDR) images. We propose an improved single-shot HDR image reconstruction method that uses a single-exposure filtered low dynamic range (FLDR) image. First, by adding an optical filter in front of the camera lens, a FLDR image with different RGB channel exposure states and luminance ranges can be captured in a single-shot, unlike the traditional LDR image. Second, a deep inverse tone mapping network (DITMnet) with multibranch features extraction and multioutput images synthesis is designed to reconstruct an HDR image from a single FLDR image. Experimentally, under different exposure states and color spaces, our method outperforms similar algorithms.
Post-processing method for the removal of mixed ring artifacts in CT images
Authors: Yang Yafei , Zhang Dinghua , Yang Fuqiang , Teng Mingxuan , Du You , Huang Kuidong
Published: September 2020

Ring artifacts seriously deteriorate the quality of CT images. Intensity-dependence of detector responses will result in intensity-dependent ring artifacts and time-dependence of CT hardware systems will result in time-dependent ring artifacts. However, only the intensity-dependent ring artifacts are taken into consideration in most post-processing methods. Therefore, the purpose of this study is to propose a general post-processing method, which has a significant removal effect on the intensity-dependent ring artifacts and the time-dependent ring artifacts. First in the proposed method, transform raw CT images into polar coordinate images, and the ring artifacts will manifest as stripe artifacts. Secondly, obtain structure images by smoothing the polar coordinate images and acquire texture images containing some details and stripe artifacts by subtracting the structure images from the polar coordinate images. Third, extract the stripe artifacts from the texture images using mean extraction and texture classification, and obtain the extracted ring artifacts by transforming the extracted stripe artifacts from polar coordinates into Cartesian coordinates. Finally, obtain corrected CT images by subtracting the extracted ring artifacts from the raw CT images, and iterate the corrected CT images in above steps until the ring artifacts extracted in the last iteration are weak enough. Simulation and real data show that the proposed method can remove the intensity-dependent ring artifacts and the time-dependent ring artifacts effectively while preserving image details and spatial resolution. In particular, real data prove that the method is suitable for new CT systems such as the photon counting CT.
Correlation plenoptic imaging between arbitrary planes
Authors: Di Lena Francesco , Massaro Gianlorenzo , Lupo Alessandro , Garuccio Augusto , Pepe Francesco V. , D’Angelo Milena
Published: September 2020

We propose a novel method to perform plenoptic imaging at the diffraction limit by measuring second-order correlations of light between two reference planes, arbitrarily chosen, within the tridimensional scene of interest. We show that for both chaotic light and entangled-photon illumination, the protocol enables to change the focused planes, in post-processing, and to achieve an unprecedented combination of image resolution and depth of field. In particular, the depth of field results larger by a factor 3 with respect to previous correlation plenoptic imaging protocols, and by an order of magnitude with respect to standard imaging, while the resolution is kept at the diffraction limit. The results lead the way towards the development of compact designs for correlation plenoptic imaging devices based on chaotic light, as well as high-SNR plenoptic imaging devices based on entangled photon illumination, thus contributing to make correlation plenoptic imaging effectively competitive with commercial plenoptic devices.
Enhancement of the energy resolution of CsI(Na) scintillators by photonic crystals prepared with dry-transfer technique
Authors: Ouyang Xiao , Liu Bo , Xiang Xincheng , Zhu Zhichao , Chen Liang , Song Xiaojing , Yuan Di , Chen Chuanxiang
Published: September 2020

Photonic crystals coated on the surface of scintillators can be used to improve the light extraction efficiency by partially eliminating the total internal reflection. However, the traditional self-assembly technique is not applicable to the hygroscopic scintillators. In the present investigation, we have proposed an efficient method to prepare the photonic crystals on the surface of CsI(Na) hygroscopic scintillators by a combination of the self-assemble of polystyrene (PS) microspheres and the subsequent dry-transfer procedure. For obtaining optimal parameters of photonic crystals, the light output of the CsI(Na) sample is enhanced by 43.2% compared to the reference sample without photonic crystals under the excitation of alpha particles from 241Am source. The energy resolution is improved from 11.2% to 7.8%. This technique based on the dry-transfer procedure has a promising prospect in the preparation of photonic crystals for hygroscopic scintillators.
Localized structures formed through domain wall locking in cavity-enhanced second-harmonic generation
Authors: Mas Arabí C. , Parra-Rivas P. , Hansson T. , Gelens L. , Wabnitz S. , Leo F.
Published: September 2020

We analyze the formation of localized structures in cavity-enhanced second-harmonic generation. We focus on the phase-matched limit, and consider that fundamental and generated waves have opposite signs of group velocity dispersion. We show that these states form due to the locking of domain walls connecting two stable homogeneous states of the system, and undergo collapsed snaking. We study the impact of temporal walk-off on the stability and dynamics of these localized states.
Chirp-compensated pulsed titanium–sapphire laser system for precision spectroscopy
Authors: Hussels J. , Cheng C. , Salumbides E. J. , Ubachs W.
Published: September 2020

Active frequency-chirp control for a narrowband pulsed titanium–sapphire laser oscillator–amplifier laser system is demonstrated using an intra-cavity electro-optic modulator, resulting in improved spectral resolution and stability. Beat-note measurements of its output to a continuous-wave laser locked to an optical frequency comb yields an Allan deviation of

5
×

10

−
11

(at 10 s). Correction of residual chirp from a comparison with the fourth-harmonic upconverted pulsed output to a molecular

H

2

two-photon resonance delivers a value for the uncertainty contribution due to frequency chirp below the

1.5
×

10

−
10

level.
High-quality-factor microring resonator for strong atom–light interactions using miniature atomic beams
Authors: Eshaghian Dorche Ali , Wei Bochao , Raman Chandra , Adibi Ali
Published: September 2020

An integrated photonic platform is proposed for strong interactions between atomic beams and annealing-free high-quality-factor

(

Q
)

microresonators. We fabricated a thin-film, air-clad SiN microresonator with a loaded

Q

of

1.55
×

10
6

around the optical transition of 

87

R
b

at 780 nm. This

Q

is achieved without annealing the devices at high temperatures, enabling future fully integrated platforms containing optoelectronic circuitry. The estimated single-photon Rabi frequency (2g) is

2
π
×
64

M
H
z

100 nm above the resonator. Our simulation result indicates that miniature atomic beams with a longitudinal speed of 0.2 m/s to 30 m/s will interact strongly with our resonator, allowing for the detection of single-atom transits and realization of scalable single-atom photonic devices. Interactions between racetrack resonators and thermal atomic beams are also simulated.
Dynamic polarization control for free-space continuous-variable quantum key distribution
Authors: Wang Shiyu , Huang Peng , Wang Tao , Zeng Guihua
Published: September 2020

Free-space quantum key distribution (QKD) is attractive for the establishment of future global-scale quantum networks. However, it can be quite difficult for dynamic polarization control required in continuous-variable QKD systems to work properly in the presence of channel fading. Here we propose a dynamic polarization control scheme and verify its validity via simulations and an experiment performed over a 150 m free-space channel. The results indicate the capability of the scheme to effectively control the states of polarization for free-space continuous-variable quantum communication.
High-speed dual-view band-limited illumination profilometry using temporally interlaced acquisition
Authors: Jiang Cheng , Kilcullen Patrick , Lai Yingming , Ozaki Tsuneyuki , Liang Jinyang
Published: September 2020

We report dual-view band-limited illumination profilometry (BLIP) with temporally interlaced acquisition (TIA) for high-speed, three-dimensional (3D) imaging. Band-limited illumination based on a digital micromirror device enables sinusoidal fringe projection at up to 4.8 kHz. The fringe patterns are captured alternately by two high-speed cameras. A new algorithm, which robustly matches pixels in acquired images, recovers the object’s 3D shape. The resultant TIA–BLIP system enables 3D imaging over 1000 frames per second on a field of view (FOV) of up to 180 mm × 130 mm (corresponding to

1180
×
860
  
pixels

) in captured images. We demonstrated TIA–BLIP’s performance by imaging various static and fast-moving 3D objects. TIA–BLIP was applied to imaging glass vibration induced by sound and glass breakage by a hammer. Compared to existing methods in multiview phase-shifting fringe projection profilometry, TIA–BLIP eliminates information redundancy in data acquisition, which improves the 3D imaging speed and the FOV. We envision TIA–BLIP to be broadly implemented in diverse scientific studies and industrial applications.
Modeling the degradation mechanisms of AlGaN-based UV-C LEDs: from injection efficiency to mid-gap state generation
Authors: Piva F. , De Santi C. , Deki M. , Kushimoto M. , Amano H. , Tomozawa H. , Shibata N. , Meneghesso G. , Zanoni E. , Meneghini M.
Published: September 2020

In this work, we analyze and model the effect of a constant current stress on an ultraviolet light-emitting diode with a nominal wavelength of 285 nm. By carrying out electrical, optical, spectral, and steady-state photocapacitance (SSPC) analysis during stress, we demonstrate the presence of two different degradation mechanisms. The first one occurs in the first 1000 min of stress, is ascribed to the decrease in the injection efficiency, and is modeled by considering the defect generation dynamics related to the de-hydrogenation of gallium vacancies, according to a system of three differential equations; the second one occurs after 1000 min of stress and is correlated with the generation of mid-gap defects, for which we have found evidence in the SSPC measurements. Specifically, we detected the presence of deep-level states (at 1.6 eV) and mid-gap states (at 2.15 eV), indicating that stress induces the generation of non-radiative recombination centers.