bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuous body 3-D reconstruction of limbless animals
Authors: Fu Qiyuan , Mitchel Thomas W. , Kim Jin Seob , Chirikjian Gregory S. , Li Chen
Published: February 2021

Limbless animals such as snakes, limbless lizards, worms, eels and lampreys move their slender, long bodies in three dimensions to traverse diverse environments. Accurately quantifying their continuous body's 3-D shape and motion is important for understanding body–environment interactions in complex terrain, but this is difficult to achieve (especially for local orientation and rotation). Here, we describe an interpolation method to quantify continuous body 3-D position and orientation. We simplify the body as an elastic rod and apply a backbone optimization method to interpolate continuous body shape between end constraints imposed by tracked markers. Despite over-simplifying the biomechanics, our method achieves a higher interpolation accuracy (∼50% error) in both 3-D position and orientation compared with the widely used cubic B-spline interpolation method. Beyond snakes traversing large obstacles as demonstrated, our method applies to other long, slender, limbless animals and continuum robots. We provide codes and demo files for easy application of our method.
Olfactory tracking strategies in a neotropical fruit bat
Authors: Brokaw Alyson F. , Smotherman Michael
Published: February 2021

Many studies have characterized olfactory-tracking behaviors in animals, and it has been proposed that search strategies may be generalizable across a wide range of species. Olfaction is important for fruit- and nectar-feeding bats, but it is uncertain whether existing olfactory search models can predict the strategies of flying mammals that emit echolocation pulses through their nose. Quantitative assessments of how well echolocating bats track and localize odor sources are lacking, so we developed a behavioral assay to characterize the olfactory detection and tracking behavior of crawling northern yellow-shouldered bats (Sturnira parvidens), a common neotropical frugivore. Trained bats were presented with a choice between control and banana-odor-infused solutions in a series of experiments that confirmed that bats are able to locate a reward based on odor cues alone and examined the effect of odor concentration on olfactory search behaviors. Decision distance (the distance from which bats made their change in direction before directly approaching the target) was distinctly bimodal, with an observed peak that coincided with an inflection point in the odor concentration gradient. We observed two main search patterns that are consistent with both serial sampling and learned route-following strategies. These results support the hypothesis that bats can combine klinotaxis with spatial awareness of experimental conditions to locate odor sources, similar to terrestrial mammals. Contrary to existing models, bats did not display prominent head-scanning behaviors during their final approach, which may be due to constraints of nasal-emitted biosonar for orientation.
Accounting for body mass effects in the estimation of field metabolic rates from body acceleration
Authors: Byrnes Evan E. , Lear Karissa O. , Brewster Lauran R. , Whitney Nicholas M. , Smukall Matthew J. , Armstrong Nicola J. , Gleiss Adrian C.
Published: February 2021

Dynamic body acceleration (DBA), measured through animal-attached tags, has emerged as a powerful method for estimating field metabolic rates of free-ranging individuals. Following respirometry to calibrate oxygen consumption rate (ṀO2) with DBA under controlled conditions, predictive models can be applied to DBA data collected from free-ranging individuals. However, laboratory calibrations are generally performed on a relatively narrow size range of animals, which may introduce biases if predictive models are applied to differently sized individuals in the field. Here, we tested the mass dependence of the ṀO2–DBA relationship to develop an experimental framework for the estimation of field metabolic rates when organisms differ in size. We performed respirometry experiments with individuals spanning one order of magnitude in body mass (1.74–17.15 kg) and used a two-stage modelling process to assess the intraspecific scale dependence of the ṀO2–DBA relationship and incorporate such dependencies into the coefficients of ṀO2 predictive models. The final predictive model showed scale dependence; the slope of the ṀO2–DBA relationship was strongly allometric (M1.55), whereas the intercept term scaled closer to isometry (M1.08). Using bootstrapping and simulations, we evaluated the performance of this coefficient-corrected model against commonly used methods of accounting for mass effects on the ṀO2–DBA relationship and found the lowest error and bias in the coefficient-corrected approach. The strong scale dependence of the ṀO2–DBA relationship indicates that caution must be exercised when models developed using one size class are applied to individuals of different sizes.
Temperature adaptations of the thermophilic snail Echinolittorina malaccana: insights from metabolomic analysis
Authors: Chen Ya-qi , Wang Jie , Liao Ming-ling , Li Xiao-xu , Dong Yun-wei
Published: February 2021

The periwinkle snail Echinolittorina malaccana, for which the upper lethal temperature is near 55°C, is one of the most heat-tolerant eukaryotes known. We conducted a multi-level investigation – including cardiac physiology, enzyme activity, and targeted and untargeted metabolomic analyses – that elucidated a spectrum of adaptations to extreme heat in this organism. All systems examined showed heat intensity-dependent responses. Under moderate heat stress (37–45°C), the snail depressed cardiac activity and entered a state of metabolic depression. The global metabolomic and enzymatic analyses revealed production of metabolites characteristic of oxygen-independent pathways of ATP generation (lactate and succinate) in the depressed metabolic state, which suggests that anaerobic metabolism was the main energy supply pathway under heat stress (37–52°C). The metabolomic analyses also revealed alterations in glycerophospholipid metabolism under extreme heat stress (52°C), which likely reflected adaptive changes to maintain membrane structure. Small-molecular-mass organic osmolytes (glycine betaine, choline and carnitine) showed complex changes in concentration that were consistent with a role of these protein-stabilizing solutes in protection of the proteome under heat stress. This thermophilic species can thus deploy a wide array of adaptive strategies to acclimatize to extremely high temperatures.
Aversive operant conditioning alters the phototactic orientation of the marbled crayfish
Authors: Okada Shione , Hirano Natsumi , Abe Toshiki , Nagayama Toshiki
Published: February 2021

Aversive learning was applied to affect the phototactic behaviour of the marbled crayfish. Animals initially showed negative phototaxis to white light and positive taxis to blue light. Using an aversive learning paradigm, we investigated the plasticity of innate behaviour following operant conditioning. The initial rate of choosing a blue-lit exit was analysed by a dual choice experiment between blue-lit and white-lit exits in pre-test conditions. During training, electrical shocks were applied to the animals when they oriented to the blue-lit exit. Memory tests were given to analyse the orientation rate to the blue-lit exit in trials 1 and 24 h after training and these rates were compared with the pre-test. In general, animals avoided the blue-lit exit in the memory tests. When training was carried out three times, the long-term memory was retained for at least 48 h, although a single bout of training was also enough to form a long-term memory. Cooling animals at 4°C or injection of cycloheximide immediately after training altered the formation of long-term memory, but had no effect on short-term memory formation. Administration of the adenylate cyclase inhibitor SQ22536, the PKA inhibitor H89 or the CREB inhibitor KG-501 immediately after training also blocked the formation of long-term memory, but had no effect on short-term memory formation. Thus, our pharmacological behavioural analyses showed that new protein synthesis was necessary to form long-term memories and that the cAMP/PKA/CREB pathway is the main signal cascade for long-term memory formation in the marbled crayfish.
Staffing the Higher Education Classroom
Authors: Figlio David , Schapiro Morton
Published: February 2021

We discuss some centrally important decisions faced by colleges and universities regarding how to staff their undergraduate classrooms. We describe the multitasking problem faced by research-intensive institutions and explore the degree to which there may be a trade-off between research and teaching excellence using matched student-faculty-level data from Northwestern University. We present two alternative measures of teaching effectiveness—one capturing “deep learning” and one capturing “inspiration”—and demonstrate that neither is correlated with measures of research success. We discuss the move toward contingent faculty in US universities and show that on average, contingent faculty outperform tenure-line faculty in the introductory classroom, a pattern driven by the lowest-performing instructors according to our measures. We also present some of the ways in which instructor gender, race, and ethnicity might matter. Together, these pieces of evidence show that several institutional objectives associated with staffing undergraduate classrooms may be in tension with one another.
How Do Firms Respond to Minimum Wage Increases? Understanding the Relevance of Non-Employment Margins
Authors: Clemens Jeffrey
Published: February 2021

This paper discusses non-employment margins through which firms may respond to minimum wage increases. Margins of interest include evasion, output prices, noncash compensation, job attributes including effort requirements, the firm’s mix of low- and high-skilled labor, and the firm’s mix of labor and capital. I discuss the basic theory behind each margin’s potential importance as well as findings from empirical research on their real-world relevance. Additionally, I present a set of pedagogical diagrams that show how supply and demand analyses of labor markets can be extended to bring additional nuances of real-world markets into the classroom.
An investigation of psychological responses to COVID-19 in Irish healthcare workers: longitudinal quantitative and nested qualitative study
Authors: Fortune Donal G. , Richards Helen L. , Wormald Andrew , O Connor Kieran , McKiernan Margaret , Najt Pablo , O Dwyer Amanda , O Dea Edmond , Burke Paul , Eustace Joseph
Published: February 2021

COVID-19 is an unprecedent occurrence in modern times and individuals who work within healthcare settings, face a broad array of challenges in responding to this worldwide event. Key information on the psychosocial responses of such healthcare workers (HCWs) in the context of COVID-19 is limited and in particular there is a need for studies that utilise longitudinal methods, an overarching theoretical model, and use of a cohort of participants within a defined geographical area across acute and community settings. The work packages making up the current research project use quantitative and qualitative methods to examine the psychological sequelae for HCWs in the context of COVID-19 in geographically adjacent healthcare areas (South and Mid-West of Ireland) across four time points (induction, 3 months, 6 months, and 1 year follow-up). The quantitative arm of the project (WP 1) utilises the Common-Sense Model of Self-Regulation (CSM-SR) and examines a number of key psychological factors pertinent to this model including perceptions about COVID-19 and infection more generally, coping, formal and informal support and a number of impact variables including mood, sleep quality, and perceptions of stigma. The qualitative study (WP 2) will address HCWs experiences of working during the pandemic, ascertain any additional areas of psychological functioning, environmental and workplace factors and resources that may be utilised by HCWs and that are not assessed by the quantitative study protocol, focusing particularly on those staff groups typically underrepresented in previous studies.
Foreword
Authors: Klumpp Gerson , Gusev Valentin
Published: February 2021

Foreword
High mountain community in a changing climate: a study of agropastoral adaptation in mustang district, Nepal
Authors: Upadhyay Prakash
Published: February 2021

This paper explores the changing climate, its impact, and the diversified practices of agropastoral adaption by a mountain community of Nepal. The findings reveal that there is an unswerving link between the changes in climate and their impact on the community and its adaptation options. The vulnerability and risk induced by the climate change has threatened the agropastoral subsistence, the sociocultural and economic structure, and the food sovereignty of the Loba community of Mustang district of Nepal and made them experience unanticipated complications in livelihood. In a changing climate, the community has attuned and restructured its adaptive strategy with diversified practices of collective labour in a traditional agropastoral system of landholding, mystical connectivity and seasonal relocation as an adaptive response ensuring the shared sustenance of the com munity. The challenge of climate change began long ago; it will persevere and be long- lasting. Hence, this paper argues for the need for a prudent adoption of measures to maintain an environmentally suitable agropastoral system of liveli hood well-being. Beyond enhancing community capacity and climate resilience, it is necessary to streamline and readjust indigenous sociocultural institutions by expanding their adaptive capacity, while recognizing the cultural dimensions grounded in systems of meanings and relationships and the way people and their culture experience and respond to exceptional climatic changes.
Early preventive respiratory support in the complex treatment of patients with reduced motor activity on an outpatient and inpatient basis
Authors: Fedorov S. , Sobolenkova V. , Fedorov S. , Nikanorov B.
Published: February 2021

Physical inactivity is an urgent problem of modern medicine and society, characterized by a number of serious systemic disorders and claiming more than 5 million human lives every year. A timely increase in physical activity is obvious, however, there is a risk of developing tissue hypermetabolic syndrome associated with uncontrolled consumption of energy factors by the muscular system and possible damage to vital organs. In this regard, justified and proposed a system cardiorespiratory training, previous physical activation, by means of peak pressure in respiratory tract, through a portable device designed for individual use with a metered level of resistivity to reduce the risk of tissue hypermetabolism syndrome and increase in the future, the possibility of physical rehabilitation
The Variance Learning Curve
Authors: Bavafa Hessam , Jónasson Jónas Oddur
Published: February 2021

The expansive learning curve literature in operations management has established how various facets of prior experience improve average performance. In this paper, we explore how increased cumulative experience affects performance variability or consistency. We use a two-stage estimation method of a heteroskedastic learning curve model to examine the relationship between experience and performance variability among paramedics at the London Ambulance Service. We find that, for paramedics with lower experience, an increase in experience of 500 jobs reduces the variance of task completion time by 8.7%, in addition to improving average completion times by 2.7%. Similar to prior results on the average learning curve, we find a diminishing impact of additional experience on the variance learning curve. We provide an evidence base for how to model the learning benefits of cumulative experience on performance in service systems. Our findings imply that the benefits of learning are substantially underestimated if the consistency effect is ignored. Specifically, our estimates indicate that queue lengths (or wait times) might be overestimated by as much as 4% by ignoring the impact of the variance learning curve in service systems. Furthermore, our results suggest that previously established drivers of productivity should be revisited to examine how they affect consistency, in addition to average performance.

This paper was accepted by Charles Corbett, operations management.
The Calendar Effects of the Idiosyncratic Volatility Puzzle: A Tale of Two Days?
Authors: Cao Jie , Chordia Tarun , Zhan Xintong
Published: February 2021

The idiosyncratic volatility (IVOL) anomaly exhibits strong calendar effects. The negative relation between IVOL and the next-month return obtains mainly in the third week of the month. The IVOL-return relation is generally negative on Mondays and positive on Fridays. However, the positive impact is absent on the third Friday because of selling pressure from stocks delivered at option expiration. This imbalance between the negative and positive returns during the third week of the month has a large impact on the IVOL-return relation. Removing the third Friday and subsequent Monday return reduces the monthly IVOL effect by at least 40%.

This paper was accepted by Karl Diether, finance.
Surge Pricing and Two-Sided Temporal Responses in Ride Hailing
Authors: Hu Bin , Hu Ming , Zhu Han
Published: February 2021

Problem definition: We investigate surge pricing in ride-hailing platforms from a temporal perspective, highlighting strategic behavior by riders and drivers and that drivers respond to surge pricing much more slowly than riders do. Academic/practical relevance: Surge pricing in ride-hailing platforms is a pivotal and controversial subject. Despite abundant anecdotal evidence, strategic behavior by riders and drivers has not been formally studied in the literature. Methodology: We adopt and analyze a classic two-period, game-theoretical model as in the strategic consumer literature. Results: We identify two types of equilibrium pricing strategies. The first consists of a short-lived, sharp price surge followed by a lower price, which we refer to as skimming surge pricing (SSP). The second consists of a low initial price followed by a higher price, which we refer to as penetration surge pricing (PSP). We find that PSP equilibria are generally superior to SSP equilibria when both exist but require platforms to share demand–supply information with drivers. Managerial implications: The SSP equilibrium rationalizes the controversial sharp surge-pricing practice: the short-lived sharp price surge causes many high-value riders to voluntarily wait out the initial surge period, which attracts additional drivers to the region to serve riders at a much lower price than the initial surge price. The theoretically superior PSP equilibrium suggests that a vastly different approach may improve surge pricing and highlights the potential value and importance for platforms to share demand–supply information with drivers.
Economies of Scope and Optimal Due Diligence in Corporate Acquisitions
Authors: Reuer Jeffrey J. , Sakhartov Arkadiy V.
Published: February 2021

This study develops a theory of due diligence in corporate acquisitions. Using a formal model, the study situates due diligence in the context of economies of scope, which are often sought by acquiring organizations that have incomplete information about such economies. Relatedness, the key determinant of economies of scope, and ambiguity, the key determinant of incomplete information, are used to derive the optimal due diligence effort and the returns to an acquiring organization that result from that effort. The derived predictions qualify both the general appeal to extensive due diligence and the general recognition of the costliness of due diligence. These predictions can be tested in future empirical research on corporate acquisitions and may guide corporate acquirers on the optimal allocation of their due diligence efforts in the mergers and acquisitions market.
Increasing the Level of Abstraction as a Strategy for Accelerating the Adoption of Complex Technologies
Authors: Shih Willy C.
Published: February 2021

Many new technologies are complex and embody high levels of technical sophistication, and applying them should require significant knowledge and experience. Yet, the rapid adoption and incorporation of these technologies into other innovations seems inconsistent with the expertise needed to make them work. In this paper, we propose increasing levels of abstraction as a strategy for speeding the adoption of new technologies. Higher-level abstractions package complexity in ways that makes them easier to understand and recombine, and they decrease the resources needed by firms to deploy sophisticated technical know-how. Increasing the level of abstraction is a way to push forward the innovative frontier by making such difficult-to-use technologies readily accessible to other innovators. Although this framing has been used in engineering and software development to describe modular encapsulation and cumulative innovation, we propose its use in the management literature to describe more broadly the uptake of new technologies and their facile recombination. This framing casts a different light on cumulative innovation and exposes new managerial questions to explore
DC Motor Speed Regulation Using Speech Recognition
Authors: Andriyan Firda Andriyan , Aji Wahyu Sapto
Published: February 2021

One of the uses of this sound technology is controlling the speed of a DC motor. Sound in the form of a spectrum signal can be converted to digital. Digital signals can be used as a microcontroller input to adjust the speed of a DC motor using the PWM (pulse width modulation) method. The design of the tool uses the V3 voice recognition module to convert the voice into digital. A microcontroller as a voice data processor by changing the input voltage to a DC motor. Voice command to set DC motor speed. Based on the results of tests carried out in good environmental conditions, 90% of voice commands can be recognized. Meanwhile, in bad environmental conditions by 50%. Manual measurement is done by entering the input voltage from 1 volt to 10 volts. The results of the comparison show that the speed is almost the same, namely 2727 rpm for manual calculation and 2915 rpm for the whole tool. This difference occurs because the test when manually inputting the tension is not very accurate. It can be concluded that the tool is working properly and as desired. If the environmental conditions are bad only 50% can be recognized from 30 voice commands, then there is a difference in voice intonation during the training process.
Fire Extinguisher Wheel Robot Based on Arduino Mega 2560 R3 with Android Smartphone Control
Authors: Nugroho Herry Setyo , Sutikno Tole
Published: February 2021

The development of technology in the smartphone sector is currently developing very rapidly which results in smartphones becoming one of the primary needs. Judging from the ability of a smartphone that is able to run various applications, one of which is to use it as a control tool. Through this research, a fire extinguisher wheeled robot prototype will be built with the control of an Android smartphone based on the Arduino Mega 2560 via Bluetooth wireless communication. The results showed that the robot can function properly controlled via an Android smartphone with a maximum distance of 10 meters, the robot is able to respond and extinguish the fire with a maximum range of 60 cm, and the robot is able to know the distance of the barrier around it (in cm) with an accuracy of up to 97%. To extinguish the fire the robot can move with an average speed of movement of the robot of 22.2 seconds per extinguishing phase.
Direct Seeding of Basmati Rice through Improved Drills: Potential and Constraints in Pakistani Farm Settings
Authors: Cheema Muhammad Jehanzeb Masud , Nauman Muhammad Hafiz , Ghafoor Abdul , Farooque Aitazaz Ahsan , Haydar Zeeshan , Ashraf Muhammad Umair , Awais Muhammad
Published: February 2021

Abstract.

In Pakistan, rice is an important cash crop and is cultivated over 2.75 mha, generally as traditionally transplanted rice (TTPR). High labor costs and water requirements, time intensiveness, low plant populations, and increased methane emissions are problems associated with TTPR. Alternatively, direct seeded rice (DSR) is now being adopted by rice growers for saving of labor cost (1-2 compared to 50-60 person-days/ha for TTPR), for time and water saving (10% to 30%), and most importantly for achieving the optimal plant population. Technical issues in machine design, and direct seeding, lack of farmers’ awareness about the technology, and social issues are the major hurdles in wide scale adoption of this effective intervention. To identify and address these issues, a testing and calibration activity was conducted during 2017 in the eight major basmati rice producing districts of Punjab, Pakistan. Twenty-one DSR drills (model 2017) being used in the field were tested to determine efficiency and farmers’ perceptions of the technology were noted. Plant germination percentage and vegetation vigor were also measured. The drawbacks in design, manufacturing, and assembling were identified in the DSR drills and modifications were made in the new model to improve efficiency. Fifty-three randomly selected modified DSR drills (model 2018) were calibrated in 2018 before the start of the rice-sowing season. In 2017 the study showed large variability in the row-to-row distance, seed rate and distances of individual drills, and resulting seed germination ranged from 20% to 90% sown at different sites. In 2018, the standard deviation (SD) of seed rate was improved from SD = 19.7 to 6.6 g/40 rev/tine while SD of row-to-row distance was reduced from 0.81 to 0.61 cm as compared to 2017 drill. The plant vigor measured in terms of the Normalized Difference Vegetation Index (NDVI) showed a good relationship with the plant population (R2 = 0.66) except at a few locations where weeds dominated. Important social issues identified were farmer’s lack of interest in preparing the land, precision land leveling, seed treatment, timely inputs, and farmer’s traditional thinking. However, farmers were motivated to consider adopting the DSR technology by demonstration plots established in 2017 by the Nuclear Institute for Agriculture & Biology (NIAB) and the Rice Research Institute (RRI), Kala Shah Kaku. Increased DSR machine sales in 2018 indicate the technology is being more widely adopted. Keywords: Direct seeded rice drills, Normalized Difference Vegetation Index (NDVI), Plant population, Precision planting, Traditionally transplanted rice.
An Automatic Detector for Fungal Spores in Microscopic Images Based on Deep Learning
Authors: Zhang Ying , Li Jiangtao , Tang Fang , Zhang Haiyang , Cui Zhaojun , Zhou Huiling
Published: February 2021

Highlights

A fungal spore dataset with microscopic images was established.

A fungal spore detector, FSNet, based on deep learning was proposed to automatically recognize and count fungal spores in microscopic images.

A framework based on a CNN for feature extraction was designed to enrich feature maps.

A loss was formulated to decrease the number of missed detections due to clustered spores.

Abstract. The most common cause of spoiled grain in storage is the growth of fungi on the grain. In China, the level of fungal infection is indicated by the quantity and the categories of fungal spores in grain samples. In most Chinese grain depots, the recognition and counting of fungal spores in grain samples are conducted with microscopes, which are mainly operated manually by professionals. This method is time-consuming, laborious and error-prone. In this article, a fungal spore detector, named FSNet, was proposed to automatically recognize and count fungal spores in microscopic images. To enrich the features in feature maps, a multi-layer fusion structure based on convolutional neural network for feature extraction was designed using deep, intermediate and shallow layers. Moreover, the detection performance of FSNet was further improved by a designed loss for clustered spores, an anchor optimization and region sampling strategy. Our method achieved 91.6% mean average precision [intersection-over-union (IoU) > 0.6]. The experimental results indicated that our method was capable of recognizing and counting fungal spores in microscopic images, and it is very effective for the early detection of fungal infection. Keywords: Fungal spore detection, Deep learning, Microscopic images.
Growth Characteristics of Summer Cover Crop Grasses and their Relation to Soil Aggregate Stability and Wind Erosion Control in Arid Southwest
Authors: Darapuneni Murali K. , Idowu Omololu J. , Sarihan Bilgi , DuBois David , Grover Kulbhushan , Sanogo Soum , Djaman Koffi , Lauriault Leonard , Omer Mohammed , Dodla Syam
Published: February 2021

Highlights

Four summer cover crops under two irrigation regimes were tested for soil wind erosion control.

Soil aggregate stability and wind erosion losses were improved with plant cover in the peak summer.

Sorghum sudan is a prominent summer species for wind erosion control in the arid southwest.

Abstract. Cover crops can have significant impacts on minimizing soil erosion by wind, which is a common problem in the arid southwest. A study was conducted at NMSU Leyendecker Plant Science Center, Las Cruces, New Mexico, to evaluate the impacts of selected summer cover crops on soil loss during wind erosion events. Four summer grass species [Japanese millet (Echinochloa esculenta), pearl millet (Pennisetum glaucum), brown top millet (Urochloa ramosa (L.) Nguyen), and sorghum sudangrass (Sorghum bicolor × S. bicolor var. Sudanese)] were randomly assigned to four blocks under two irrigation regimes (full-irrigation and deficit-irrigation). Results showed significant effect of grasses on horizontal soil flux compared to control under both irrigation regimes. When comparing the grasses, sorghum sudan grass performed better than the other tested summer cover crops for soil surface protection from wind erosion with its higher ground coverage, higher plant density, taller plant height and higher amount of biomass, while brown top millet was least effective in terms of plant and erosion control characteristics (P=0.05). Pearl millet and Japanese millet performed better than brown top millet, but was as effective as sorghum sudan as barriers against the wind erosion. Therefore, sorghum sudan is a prominent cover crop for summer in the arid zones of desert southwest. Producers of this region can be significantly benefited from the current research recommendations about cover crops choices for summer season. Keywords: Arid climates, Cover cropping, Summer grasses, Wind erosion control.
Granular Fertilizer Mass Flow Measurement and Vehicle Experiments Based on Microwave Doppler Method
Authors: Huang Jiayun , Yang Liwei , Zhang Jiqin , Hu Hao
Published: February 2021

Highlights

A microwave Doppler-based fertilizer mass flow measurement system was developed.

The measurement system was applied in vehicle experiments.

Power spectra of mass flow signal and vibration signal were obtained and analyzed.

Interference suppression algorithm based on CA-CFAR reduced vibration interference.

Fertilizer mass flow measurement accuracy was improved by interference suppression.

Abstract. The fertilizer mass flow measurement system is typically installed on the fertilizer applicator. However, vehicle vibrations are inevitable during field operation of fertilizing equipment, and can interfere with mass flow signals, thereby affecting the accuracy of mass flow measurements. In this article, a mass flow measurement system based on the microwave Doppler method was introduced. The dominant frequency (fdot) related to fertilizer velocity and the power spectral density (PSD) related to fertilizer concentration were obtained from the Doppler signal of the granular fertilizer processed using fast Fourier transform. The product of fdot and PSD is defined as the sensor output value (SOV). The relationship between SOV, PSD, and fertilizer mass flow (FMF) was studied under vehicle conditions. The linear regression models of 22-8-10 (MOP) high-nitrogen poly-?-glutamic acid fertilizer were established using the least squares method, and the vibration signals were measured. Based on analysis of the power spectra of the mass flow and vibration signals, an interference suppression algorithm based on cell average constant false alarm rate (CA-CFAR) was presented to reduce vibration interference. To verify the performance of the novel vibration interference reduction algorithm, vehicle experiments were conducted at different tractor velocities. The results show that mass flow measurements ranged from 1300 to 3000 g min-1. It was found that using only the PSD related to concentration for flow measurement gave better measurement accuracy compared with SOV, and relative errors of the system were within 8.1%. Correlation between the PSD and FMF improved with interference suppression algorithm based on CA-CFAR. The determination coefficient increased from 0.01 to 0.92, 0.97 to 0.99, and 0.96 to 0.98 at three different tractor velocities, respectively. From the results, it was evident that the algorithm effectively eliminated vibration interference signals in vehicle conditions. In future work, the conditions of the soil will be considered and the performance of the mass flow measurement system will be tested in the field. Keywords: Fertilizer mass flow, Microwave Doppler radar, Tractor vibration, Vehicle experiment, Vibration interference suppression.
Detection and Test of Rind-Pith Adhesive Strength of Corn Stalks
Authors: Huang Wanyuan , Gong Yuanjuan , Bai Xuewei
Published: February 2021

Highlights

A detection clamp for the rind-pith adhesive strength of corn stalks based on peeling method was designed.

A rind-pith adhesive strength detection method was proposed taking average peeling strength as the test index.

The characteristics of rind-pith adhesive strength were analyzed, and a mathematical model between average peeling strength and influencing factors was established.

Abstract. Rind-pith separation of corn stalks is one of the effective measures for realizing high-value utilization of stalks. Therefore, it is necessary to study rind-pith adhesive strength of stalks and its influencing factors to determine effective separation methods. In this study, a peeling method was put forward and single factor and multi-factor tests were carried out to explore the rind-pith adhesive strength. The analysis of single factor tests showed that sampling location, moisture content, and peeling speed were all significant on the average rind-pith peeling strength and the Fp = 25.70 > F0.05 (4, 20) = 2.87, Fm = 112.46 > F0.05 (4, 20) = 2.87 and Fs = 231.21 > F0.05 (6, 28) = 2.45. The mathematical model between average peeling strength and influencing factors was established through multi-factor tests. The model was analyzed and optimized, and the significance sequence of influencing factors is sampling location > moisture content > peeling speed, and the effect of interaction between moisture content and sampling location was significant (P<0.05). It can be concluded that the rind-pith peeling strengths of internode sections among 1st-7th internodes of corn stalks were 360.09-450.01 N/m, which are smaller and more favorable for mechanical separation for stalks with moisture content of 15%-20% and at peeling speed of 30-40 mm/min. The results of this study may provide a theoretical reference for the modeling of corn stalks and the subsequent simulation and optimization of rind-pith separation machines. Keywords: Average peeling strength, Adhesive strength, Corn stalks, Rind-pith Separation.
Systematic Water-Saving Management for Strawberry in Basic Greenhouses Based on the Internet of Things
Authors: Li Qun , Cao Bing , Wang Xing , Wu Jiu Jiang , Wang You Ke
Published: February 2021

A new application of the internet of things in a low-cost greenhouse with no networked intelligent control equipment.

The systematic water-saving management focused over the whole growth stage of crops, and it can effectively increase yield and quality.

Replace some chemical fertilizer with fully-decomposed organic fertilizer and new types of fertilizer to reduce negative impact on soil and the environment.

Regarding pesticide usage, we advocate prevention first and treatment second.

Improve systematic water-saving management with regard decreases in crop yield and quality.

Abstract. A basic greenhouse is an inexpensive type of greenhouse, which lacks networked intelligent control equipment; it is currently the most common type of greenhouse used in China. To manage planting activities intelligently and improve water use efficiency in these greenhouses, an intelligent planting management platform for strawberry based on the internet of things (IoT) is developed. On the platform, human-computer interaction occurs through the WeChat app on a mobile phone so that manual control of the strawberry environment in the greenhouse can be conducted. In this study, we add a user module in the perception layer of the IoT to obtain the information and manually control the environment in a basic greenhouse. The network layer uses narrowband IoT wireless transmission technology based on 4G. The application layer is designed with a systematic water-saving management knowledge base for strawberry. The systematic water-saving management feature includes seven parts: strawberry variety selection, planting seedlings, flower and fruit thinning, environmental control, disease and pest prevention and treatment, fertilizer management, and water-saving irrigation. Through the human–computer interaction platform, growers can receive decision-making options, planting management evaluation, query information retrieval, and regular relevant planting information. The application results of the platform showed the following: compared with management experience of growers, the water use efficiency of yield (WUEy) increased by 128.55%, the water use efficiency of production value (WUEpy) increased by 226.31%; the amount of chemical fertilizer decreased by 40%, the amount of pesticide decreased by 61.67%, and the cost of pesticide decreased by 32.48%; thus a decrease in the use of both fertilizer and pesticide was achieved. This study can directly provide technical support for strawberry intelligent management in basic greenhouses, and can also be used as a basic platform intelligent management systems for other crops grown in basic greenhouses. Keywords: Basic greenhouse, Intelligent agriculture, Internet of things, Sensor network , Systematic water-saving management, Water-use efficiency.
Deep THz modulation at Fabry-Perot resonances using graphene in periodic microslits
Authors: Liu Xudong , Jia Mingyang , Fan Shuting , Stantchev Rayko Ivanov , Chen Xuequan , Pickwell-Macpherson Emma , Sun Yiwen
Published: February 2021

Potential applications of terahertz (THz) radiation are constantly being investigated for high-speed communication due to its large bandwidth. For example, frequency hopping communication technology would benefit from the large bandwidth. To attach the information to the carrier wave, THz modulators with deep and stable modulation at different frequencies are crucial, yet are still lacking. Here a THz modulator, designed by integrating a non-resonant field enhancement effect of periodic metal microslits to assist a Fabry-Perot resonance structure (MS-FP) is proposed and demonstrated. New equations are developed to describe the superior performance of the novel design. The >95% modulation depth is achieved by a SiO2/Si gated graphene device at 14 Fabry-Perot resonant frequencies across 1.4 THz bandwidth, outperforming the recently reported 75% modulation depth THz modulator with a similar Fabry-Perot structure.
Shape effect on the electronic state and nonlinear optical properties in the regulable Y-shaped quantum dots under applied electric field
Authors: Li Keyin , Zhu Siqi , Dai Shibo , Li Zhen , Yin Hao , Chen Zhenqiang
Published: February 2021

The electronic state and nonlinear optical properties in the Y-shaped quantum dots has been theoretically investigated by adjusting the shape with the applied electric field. Within the effective-mass approximation, the energy levels and the wave functions of the system are obtained by means of the finite difference method. The results show that both the strength or the in-plane orientation of external electric field and the shape of regulable Y-shaped quantum dots have a significant influence on the electronic state, optical absorption coefficients and the refractive index changes.
Radiation pattern of planar optoelectronic antennas for broadband continuous-wave terahertz emission
Authors: Nellen Simon , Lauck Sebastian , Schwanke Garrit , Deumer Milan , Kohlhaas Robert B. , Liebermeister Lars , Schell Martin , Globisch Bjoern
Published: February 2021

In future wireless communication networks at terahertz frequencies, the directivity and the beam profile of the emitters are highly relevant since no additional beam forming optics can be placed in free-space between the emitter and receiver. We investigated the radiation pattern and the polarization of broadband continuous-wave (cw) terahertz emitters experimentally and by numerical simulations between 100 GHz and 500 GHz. The emitters are indium phosphide (InP) photodiodes with attached planar antenna, mounted on a hyper-hemispherical silicon lens and integrated into a fiber-pigtailed module. As both packaging and material of the emitter was identical for all devices, similarities and differences can be directly linked to the antenna structure. We found that the feeding point structure that connects photodiode and antenna has a large influence on the radiation pattern. By optimizing the feeding point, we could reduce side lobes from −2 dB to −13 dB and narrow the 6dB beam angle from ±14° to ±9° at 300 GHz.
Extended field of view of light-sheet fluorescence microscopy by scanning multiple focus-shifted Gaussian beam arrays
Authors: Liu Chao , Bai Chen , Yu Xianghua , Yan Shaohui , Zhou Yuan , Li Xing , Min Junwei , Yang Yanlong , Dan Dan , Yao Baoli
Published: February 2021

Light-sheet fluorescence microscopy (LSFM) facilitates high temporal-spatial resolution, low photobleaching and phototoxicity for long-term volumetric imaging. However, when a high axial resolution or optical sectioning capability is required, the field of view (FOV) is limited. Here, we propose to generate a large FOV of light-sheet by scanning multiple focus-shifted Gaussian beam arrays (MGBA) while keeping the high axial resolution. The positions of the beam waists of the multiple Gaussian beam arrays are shifted in both axial and lateral directions in an optimized arranged pattern, and then scanned along the direction perpendicular to the propagation axis to form an extended FOV of light-sheet. Complementary beam subtraction method is also adopted to further improve axial resolution. Compared with the single Gaussian light-sheet method, the proposed method extends the FOV from 12 μm to 200 μm while sustaining the axial resolution of 0.73 μm. Both numerical simulation and experiment on samples are performed to verify the effectiveness of the method.
Dual-modal imaging with non-contact photoacoustic microscopy and fluorescence microscopy
Authors: Zhou Jiasheng , Wang Wei , Jing Lili , Chen Sung-Liang
Published: February 2021

Simultaneous imaging of complementary absorption and fluorescence contrasts with high spatial resolution is useful for biomedical studies. However, conventional dual-modal photoacoustic (PA) and fluorescence imaging systems require the use of acoustic coupling media due to the contact operation of PA imaging, which causes issues and complicates the procedure in certain applications such as cell imaging and ophthalmic imaging. We present a novel dual-modal imaging system which combines non-contact PA microscopy (PAM) based on PA remote sensing and fluorescence microscopy (FLM) into one platform. The system enables high lateral resolution of 2 and 2.7 µm for PAM and FLM modes, respectively. In vivo imaging of a zebrafish larva injected with a rhodamine B solution is demonstrated, with PAM visualizing the pigment and FLM revealing the injected rhodamine B.
Four families of folate-independent methionine synthases
Authors: Price Morgan N. , Deutschbauer Adam M. , Arkin Adam P.
Published: February 2021

Although most organisms synthesize methionine from homocysteine and methyl folates, some have “core” methionine synthases that lack folate-binding domains and use other methyl donors. In vitro, the characterized core synthases use methylcobalamin as a methyl donor, but in vivo, they probably rely on corrinoid (vitamin B12-binding) proteins. We identified four families of core methionine synthases that are distantly related to each other (under 30% pairwise amino acid identity). From the characterized enzymes, we identified the families MesA, which is found in methanogens, and MesB, which is found in anaerobic bacteria and archaea with the Wood-Ljungdahl pathway. A third uncharacterized family, MesC, is found in anaerobic archaea that have the Wood-Ljungdahl pathway and lack known forms of methionine synthase. We predict that most members of the MesB and MesC families accept methyl groups from the iron-sulfur corrinoid protein of that pathway. The fourth family, MesD, is found only in aerobic bacteria. Using transposon mutants and complementation, we show that MesD does not require 5-methyltetrahydrofolate or cobalamin. Instead, MesD requires an uncharacterized protein family (DUF1852) and oxygen for activity.
Substitutional landscape of a split fluorescent protein fragment using high-density peptide microarrays
Authors: Antonescu Oana N. , Rasmussen Andreas , Damm Nicole A. M. , Heidemann Ditte F. , Popov Roman , Nesterov-Mueller Alexander , Johansson Kristoffer E. , Winther Jakob R.
Published: February 2021

Split fluorescent proteins have wide applicability as biosensors for protein-protein interactions, genetically encoded tags for protein detection and localization, as well as fusion partners in super-resolution microscopy. We have here established and validated a novel platform for functional analysis of leave-one-out split fluorescent proteins (LOO-FPs) in high throughput and with rapid turnover. We have screened more than 12,000 variants of the beta-strand split fragment using high-density peptide microarrays for binding and functional complementation in Green Fluorescent Protein. We studied the effect of peptide length and the effect of different linkers to the solid support. We further mapped the effect of all possible amino acid substitutions on each position as well as in the context of some single and double amino acid substitutions. As all peptides were tested in 12 duplicates, the analysis rests on a firm statistical basis allowing for confirmation of the robustness and precision of the method. Based on experiments in solution, we conclude that under the given conditions, the signal intensity on the peptide microarray faithfully reflects the binding affinity between the split fragments. With this, we are able to identify a peptide with 9-fold higher affinity than the starting peptide.