bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation of photon antibunching with only one standard single-photon detector
Authors: Liu Shaojie , Lin Xing , Liu Feng , Lei Hairui , Fang Wei , Jin Chaoyuan 
Published: January 2021

The second-order photon correlation function g2(τ) is of great importance in quantum optics. g2(τ) is typically measured with the Hanbury Brown and Twiss (HBT) interferometer, which employs a pair of single-photon detectors and a dual-channel time acquisition module. Here, we demonstrate a new method to measure and extract g2(τ) with a standard single-photon avalanche photodiode (dead-time = 22 ns) and a single-channel time acquisition module. This is realized by shifting the coincidence counts of interest to a time window not affected by the dead-time and after-pulse of the detection system using a fiber-based delay line. The new scheme is verified by measuring g2(τ) from a single colloidal nanocrystal. Photon antibunching is unambiguously observed and agrees well with the result measured using the standard HBT setup. Our scheme simplifies the higher-order correlation technique and might be favored in cost-sensitive circumstances.
Photopharmacological compounds based on azobenzenes and azoheteroarenes: principles of molecular design, molecular modelling, and synthesis
Authors: Ryazantsev Mikhail N. , Strashkov Daniil M. , Nikolaev Dmitrii M. , Shtyrov Andrey A. , Panov Maxim S. 
Published: January 2021

Photopharmacology is a field of medicine and pharmacology that uses light to selectively activate or deactivate pharmaceutical agents. This approach significantly enhances and localizes the drug action and, therefore, reduces its side effects. Apart from the bioactive moiety, any photopharmacological compound should contain a photoactive group that must absorb light at the desired wavelength and reorganize the molecular structure after photoactivation. The design of an effective photopharmacological compound requires careful tuning of physical, chemical, and biological properties. The present review summarizes and analyzes the main approaches to the molecular design of photopharmacological drugs based on azobenzene or azoheteroarenes. The main ideas and methods used for tuning spectral and photochemical properties of compounds of this class are discussed. A comparative analysis of main computational methods for theirin silicoscreening is carried out; the most common approaches to the synthesis of azobenzenes and azoheteroarenes derivatives are systematized. Special attention is given to the methods and approaches that are specific to the molecular design of photopharmacological compounds with required physicochemical and photochemical properties.The bibliography includes 212 references.
Irrigation.
Authors: Morgan Lynette 
Published: January 2021

Abstract

Crop production in many regions has been reliant on irrigation for almost as long as man has been cultivating plant life. For 6000 years, irrigation has ranked among the most powerful tools of human advancement (Postel, 1999), and by the start of the 21st century no less than 75% of the world's fresh water was in use for agricultural production (Levy and Coleman, 2014). In 2012, twenty percent of total cultivated land was under irrigation, contributing forty percent of the total food production worldwide, this represented 275 million hectares under actual irrigation with a total of 324 million hectares equipped for irrigation (FAO, 2016). Irrigation, which can be defined as 'the artificial application of water to land, soil or other growing medium for the purposes of crop growth', has become a global issue in more recent times as the increasing demand for fresh water has seen problems develop with water scarcity, quality issues and conflict over usage.
Food safety.
Authors: Morgan Lynette 
Published: January 2021

Abstract

Food that is safe, nutritious and free from contamination concerns all who grow, produce, process, store, package, market and consume plant products. Severe implications can result from ingesting produce that is harbouring any one of a wide and diverse range of bacterial, fungal, parasitic or viral pathogenic organisms, heavy metals, pesticides, naturally-occurring or synthetic contaminants or toxins, or allergens. Food safety-related deaths are recorded each year and a vast number of milder, unreported or undiagnosed illnesses also occur. Food safety regulations, controls, testing and monitoring are continuing to develop in most countries, helping to ensure an increasingly safe food supply. However, many under-developed nations still suffer extensive foodborne illness where food may be scarce and regulations limited.
Pollination.
Authors: Cottrell Vicki 
Published: January 2021

Abstract

Pollination of flowers is the transfer of pollen grains (haploid male spores) from the anther (part of the androecium) to the stigma (part of the gynoecium) by biotic or abiotic factors (Sliwinska and Bewley, 2014). For seed and fruit production of agricultural crops the main pollinating agents are wind and insects (George, 2011). After a pollen grain is transferred to a receptive stigma, it absorbs water from the stigma surface and germinates. A pollen tube then grows down into the stigma, through the gynoecium and through the apical micropyle; from there it grows into an ovule in the ovary and double fertilisation then takes place. Two sperm are released into the embryo sac; one fertilises the ovule to produce a diploid zygote, and the other joins with two polar nuclei in the ovule to produce a triploid nucleus that will then develop into the nutrient-rich endosperm (Willmer, 2011). Pollen grain diameter is usually in the range 20-70 μm, and the surface structure and morphology varies considerably between plant species and dispersal mechanism (Wiltshire, 2010). Air temperature can have an effect on pollen formation and viability, with high temperatures potentially leading to sterile pollen (Bosland and Votava, 2012). Irradiated pollen grains are still able to germinate and produce pollen tubes that reach the ovule (Germana, 2012). Although they are unable to fertilise the egg cell, this process induces parthenogenesis and has been widely used to produce haploid fruits (Germana, 2012).
Urban horticulture.
Authors: Geoffriau E. , Cannovo P. , Beaudet L. , Galopin G. , Chantoiseau E. , Bournet P. E. , Coisnon T. , Rousselière D. , de Bon Hubert 
Published: January 2021

Abstract

At the beginning of the 19th century Heinrich von Thunen developed a model on agricultural land usage. The model generated four concentric rings of agricultural activity with dairy and intensive farming being closest to the city centre. The use of a piece of land is affected by the physical potentialities of the soil, but mainly depends on the cost of transport to market. Dairy and intensive farming are closest to the city centre since vegetables, fruit, milk and other dairy products must get to the market quickly. This is one reason for the development of peri-urban vegetable farms in the 19th century that produced high value products with high perishability. Due to its intensive character and important role for feeding people, horticulture in and around the city is widespread and its development is growing in relation to increasing city sizes. Cities of the developing world are somewhat more advanced in the development of multifunctional urban horticulture, as described by de Bon et al. (2015), but very diverse new forms are emerging in Northern hemisphere countries. One challenge of urban production is to produce safe food in an urban, often-polluted environment. In this article, following a description of urban horticulture, some main components are discussed in relation to current concerns and evolutions: the diverse cropping systems and the business models associated with that form of horticulture; the provided ecosystem services; the evolution of technologies in relation with soil and product quality; the diversity of crops; economic values and organizational forms.
Kepler’s shaping of Mars’ orbit or astronomy on a tabletop
Authors: Buendia-Rios Tania M , Fabián Felipe E , Guzmán Elda , Molina Angel M , Núñez-Yépez H N , Salas-Brito A L 
Published: January 2021

Abstract
We describe a method that could have been used by Kepler to determine the shape and dimensions of Mars’ orbit around the Sun, starting from observations of its path across the night sky. Though we use Kepler’s work as a motivation, our approach does not intend to suggest that this method was actually used by him. Rather, it is only intended to show beginning undergraduate students what may be discovered about the planets using basic observational data together with simple geometric methods. We employ publicly available Harvard sky patrol (HSP) photographs of Mars at different moments in the Earth’s year to get its ecliptic coordinates, locate them on a Sun-centered coordinate system, and finally plot them on a sheet of paper. From this orbital graph, we obtain the shape and dimensions of Mars’ orbit around the Sun, using the radius of the Earth’s orbit to set the scale. By generalizing this orbital shape to the other planets in the Solar System, students may be led to conclude Kepler’s first and second laws. Other features of the scaled-down Martian orbit may be directly measured from the paper orbit. To obtain the actual values for such features, we only need to scale them up. The quantities thus determined agree well (within a surprising 5%) with those reported by NASA.
A measuring system for monitoring multi-nozzle spraying tools
Authors: Schulz Florian , Reincke Franziska , Mrochen Matthias , Beyrau Frank 
Published: January 2021

Abstract
Spray tools with multi-nozzle-arrays are used in a wide variety of applications. Monitoring the functionality of complex spraying tools with a large number of individual nozzles is a great challenge. For this purpose, we have developed a measurement technique based on the wetting pattern, which forms on a surface during spray impingement. To investigate the performance of this measurement technique we applied a spraying tool with nine external mixing air-water nozzles, the geometric alignment of which can be freely adjusted. In the first test series, the precision of the evaluation of the nozzle alignment is determined. The second test series focuses on the individual sizes of the wetted areas. Here the reproducibility, the influences of the operating modes and the nozzle type were evaluated. Subsequently, the functionality is tested in an exemplary test case in which two of nine nozzles were readjusted in a defined manner. Finally, the wetting pattern resulting from injecting a full spray is discussed and the necessary image processing steps are provided. In summary, this measuring system allows efficient, fast and cost-effective control and documentation of the alignment and functionality of spraying tools, thereby avoiding production downtime and related costs.
The effects of cesium lead bromide quantum dots on the performance of copper phthalocyanine-based organic field-effect transistors
Authors: Shukla Preeti , Yadav Sarita , Patel M S , Kumar Pramendra , Kumar Naresh , Kumar Lokendra 
Published: January 2021

Abstract
Highly luminescent all-inorganic cesium lead bromide (CsPbBr3) perovskite quantum dots (QDs) have been extensively used as a photosensitizer in optoelectronic devices, while p-type small-organic-molecule copper phthalocyanine (CuPc) is also widely used as a photoactive material in solar cells, organic field-effect transistors (OFETs), etc. In this paper, we report the preparation of a CsPbBr3-QDs/CuPc heterostructure to study the effect of CsPbBr3-QDs on CuPc. The optical properties of both CuPc and the QDs/CuPc heterostructure were compared and contrasted using UV–vis absorbance and photoluminescence (PL) measurements. Furthermore, to study their electronic and charge transfer features, we fabricated field-effect transistors (FETs) on both pristine CuPc and QDs/CuPc heterostructure thin films and studied their photoresponsive electrical characteristics. Both pristine and QDs/CuPc-based FETs showed an enhancement in current and carrier mobility under illumination. The enhancement in the current and carrier mobility of the QDs/CuPc-based FETs is due to a large number of photoexcited charge carriers. We also observed that the current and carrier mobility in the QDs/CuPc heterostructure-based FET were lower than those of the pristine CuPc-based FET. This can be explained by the n-type doping effect of CsPbBr3 QDs on CuPc, which reduces the accumulation of holes in the active p-channel near the insulating layer and causes charge to be transferred from the QDs to the CuPc. Thus, we have observed a charge transfer effect in the CsPbBr3 QDs/CuPc heterostructure, which can be used in optoelectronic devices.
Algebraic bounds on the Rayleigh–Bénard attractor
Authors: Cao Yu , Jolly Michael S , Titi Edriss S , Whitehead Jared P 
Published: January 2021

Abstract
The Rayleigh–Bénard system with stress-free boundary conditions is shown to have a global attractor in each affine space where velocity has fixed spatial average. The physical problem is shown to be equivalent to one with periodic boundary conditions and certain symmetries. This enables a Gronwall estimate on enstrophy. That estimate is then used to bound the L
2 norm of the temperature gradient on the global attractor, which, in turn, is used to find a bounding region for the attractor in the enstrophy–palinstrophy plane. All final bounds are algebraic in the viscosity and thermal diffusivity, a significant improvement over previously established estimates. The sharpness of the bounds are tested with numerical simulations.
Commercial virtual reality headsets for developing augmented reality setups to track three-dimensional motion in real time
Authors: Rosi Tommaso , Perini Marica , Onorato Pasquale , Oss Stefano 
Published: January 2021

Abstract
We designed and tested a 3D motion tracking system which displays acquired and derived data using augmented reality. This setup, based on a virtual reality headset and its controllers, is a relatively low-cost, high-precision, six degrees of freedom, high-speed, multiple-objects tracking device. This apparatus proves to be a very high-quality motion sensor which can be used in the physics laboratory for motion tracking. Stereo cameras may also be attached to the headset in order to achieve augmented reality, which can be a winning addition in order to effectively use these devices in the physics laboratory. In view of its characteristics, this system can be adopted in the study of motion both at high school and undergraduate physics laboratories.
Analyzing the rotational motion of a rectangular board via smartphone sensors: a conservation-of-mechanical-energy approach
Authors: Puttharugsa Chokchai , Pimanpang Samuk 
Published: January 2021

Abstract
This paper describes the use of a smartphone’s motion sensors in investigating the rotational motion of a rectangular board rotating around a fixed axis. The smartphone’s motion, orientation, rotational rate, and acceleration are simultaneously recorded across the x-, y-, and z-axes. In the experiment, the experimental data (angular position and angular speed of the rotating board) were recorded and were processed to demonstrate the conservation of mechanical energy during rotation. We expect that this article gives an idea of how smartphone-based physics experiments can be useful for physics teachers. Moreover, this experiment helps students better understand the rotational motion of a rectangular board in relation to the conservation of energy.
Short-term solar irradiance forecasting using convolutional neural networks and cloud imagery
Authors: Choi Minsoo , Rachunok Benjamin , Nateghi Roshanak 
Published: January 2021

Abstract
Access to accurate, generalizable and scalable solar irradiance prediction is critical for smooth solar-grid integration, especially in the light of the accelerated global adoption of solar energy production. Both physical and statistical prediction models of solar irradiance have been proposed in the literature. Physical models require meteorological forecasts—generated by computationally expensive models—to predict solar irradiance, with limited accuracy in sub-daily predictions. Statistical models leverage in-situ measurements which require expensive equipment and do not account for meso-scale atmospheric dynamics. We address these fundamental gaps by developing a convolutional global horizontal irradiance prediction model, using convolutional neural networks and publicly accessible satellite cloud images. Our proposed model predicts solar irradiance in 12 different locations in the US for various prediction time horizons. Our model yields up to 24% improvement in an hour-ahead predictions and 26% in a day-ahead predictions compared to a persistence forecast. Moreover, using saliency maps and target-location-focused cropping, we demonstrate the benefits of incorporating meso-scale atmospheric dynamics for prediction performance. Our results are critical for energy systems planners, utility managers and electricity market participants to ensure efficient harvesting of the solar energy and reliable operation of the grid.
Invited Commentary: Quantitative Bias Analysis Can See the Forest for the Trees
Authors: Gustafson Paul 
Published: January 2021

Abstract
The accompanying article by Jiang et al. (Am J Epidemiol. 2021;190(9):1830–1840) extends quantitative bias analysis from the realm of statistical models to the realm of machine learning algorithms. Given the rooting of statistical models in the spirit of explanation and the rooting of machine learning algorithms in the spirt of prediction, this extension is thought-provoking indeed. Some such thoughts are expounded upon here.
Invited Commentary: Do Small Cause-of-Death Correlations Throw Into Question the Notion of a Collective “Deaths of Despair” Phenomenon?
Authors: Siddiqi Arjumand , Sod-Erdene Odmaa 
Published: January 2021

AbstractSince the turn of the 21st century, during which White mortality has been rising, there has been a sharp increase in only 3 causes of death: drug use, alcohol use, and suicide. Because all 3 of these causes conjure notions of anguish and hopelessness, they have been conceptualized as a collective “deaths of despair” phenomenon. Simon and Masters (Am J Epidemiol. 2021;190(6)1169-1171) challenge this conceptualization by asking whether these 3 causes are empirically associated with each other. Their analyses produce small correlations, which lead them to call into question that the 3 causes are part of a unified phenomenon. We contest their work on several grounds. Their analyses suffer from several technical problems, including the fact that, for any given year and cause of death, 65.8%–97.6% of counties examined have death counts under 10. More fundamentally, it is unclear that we should expect these causes of death to rise and fall together, even if they are connected to a singular phenomenon. Instead, “despair” might manifest differently in different places (i.e., these causes might be substitutes for each other). We argue that the best answer to the authors’ important question comes from assessing whether there is a common, despair-based causal mechanism underlying all 3 of them.
The Impact of Vaccination on Coronavirus Disease 2019 (COVID-19) Outbreaks in the United States
Authors: Moghadas Seyed M , Vilches Thomas N , Zhang Kevin , Wells Chad R , Shoukat Affan , Singer Burton H , Meyers Lauren Ancel , Neuzil Kathleen M , Langley Joanne M , Fitzpatrick Meagan C , Galvani Alison P 
Published: January 2021

Abstract

Background
Global vaccine development efforts have been accelerated in response to the devastating coronavirus disease 2019 (COVID-19) pandemic. We evaluated the impact of a 2-dose COVID-19 vaccination campaign on reducing incidence, hospitalizations, and deaths in the United States.

Methods
We developed an agent-based model of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission and parameterized it with US demographics and age-specific COVID-19 outcomes. Healthcare workers and high-risk individuals were prioritized for vaccination, whereas children under 18 years of age were not vaccinated. We considered a vaccine efficacy of 95% against disease following 2 doses administered 21 days apart achieving 40% vaccine coverage of the overall population within 284 days. We varied vaccine efficacy against infection and specified 10% preexisting population immunity for the base-case scenario. The model was calibrated to an effective reproduction number of 1.2, accounting for current nonpharmaceutical interventions in the United States.

Results
Vaccination reduced the overall attack rate to 4.6% (95% credible interval [CrI]: 4.3%–5.0%) from 9.0% (95% CrI: 8.4%–9.4%) without vaccination, over 300 days. The highest relative reduction (54%–62%) was observed among individuals aged 65 and older. Vaccination markedly reduced adverse outcomes, with non-intensive care unit (ICU) hospitalizations, ICU hospitalizations, and deaths decreasing by 63.5% (95% CrI: 60.3%–66.7%), 65.6% (95% CrI: 62.2%–68.6%), and 69.3% (95% CrI: 65.5%–73.1%), respectively, across the same period.

Conclusions
Our results indicate that vaccination can have a substantial impact on mitigating COVID-19 outbreaks, even with limited protection against infection. However, continued compliance with nonpharmaceutical interventions is essential to achieve this impact.
Absence of Vaccine-enhanced Disease With Unexpected Positive Protection Against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by Inactivated Vaccine Given Within 3 Days of Virus Challenge in Syrian Hamster Model
Authors: Li Can , Chen Yan-Xia , Liu Fei-Fei , Lee Andrew Chak-Yiu , Zhao Yan , Ye Zhan-Hong , Cai Jian-Piao , Chu Hin , Zhang Rui-Qi , Chan Kwok-Hung , Chiu Kelvin Hei-Yeung , Lung David Christopher , Sridhar Siddharth , Hung Ivan Fan-Ngai , To Kelvin Kai-Wang , Zhang Anna Jin-Xia , Chan Jasper Fuk-Woo , Yuen Kwok-Yung 
Published: January 2021

Abstract

Background
Mass vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is ongoing amidst widespread transmission during the coronavirus disease-2019 (COVID-19) pandemic. Disease phenotypes of SARS-CoV-2 exposure occurring around the time of vaccine administration have not been described.

Methods
Two-dose (14 days apart) vaccination regimen with formalin-inactivated whole virion SARS-CoV-2 in golden Syrian hamster model was established. To investigate the disease phenotypes of a 1-dose regimen given 3 days prior (D-3), 1 (D1) or 2 (D2) days after, or on the day (D0) of virus challenge, we monitored the serial clinical severity, tissue histopathology, virus burden, and antibody response of the vaccinated hamsters.

Results
The 1-dose vaccinated hamsters had significantly lower clinical disease severity score, body weight loss, lung histology score, nucleocapsid protein expression in lung, infectious virus titers in the lung and nasal turbinate, inflammatory changes in intestines, and a higher serum neutralizing antibody or IgG titer against the spike receptor-binding domain or nucleocapsid protein when compared to unvaccinated controls. These improvements were particularly noticeable in D-3, but also in D0, D1, and even D2 vaccinated hamsters to varying degrees. No increased eosinophilic infiltration was found in the nasal turbinate, lung, and intestine after virus challenge. Significantly higher serum titer of fluorescent foci microneutralization inhibition antibody was detected in D1 and D2 vaccinated hamsters at day 4 post-challenge compared to controls despite undetectable neutralizing antibody titer.

Conclusions
Vaccination just before or soon after exposure to SARS-CoV-2 does not worsen disease phenotypes and may even ameliorate infection.