Wind-related orientation patterns in diurnal, crepuscular and nocturnal high-altitude insect migrants

Most insect migrants fly at considerable altitudes (hundreds of meters above the ground) where they utilize fast-flowing winds to achieve rapid and comparatively long-distance transport. The nocturnal aerial migrant fauna has been well studied with entomological radars, and many studies have demonstrated that flight orientations are frequently grouped around a common direction in a range of nocturnal insect migrants. Common orientation typically occurs close to the downwind direction (thus ensuring that a large component of the insects' self-powered speed is directed downstream), and in nocturnal insects at least, the downwind headings are seemingly maintained by direct detection of wind-related turbulent cues. Despite being far more abundant and speciose, the day-flying windborne migrant fauna has been much less studied by radar; thus the frequency of wind-related common orientation patterns and the sensory mechanisms involved in their formation remain to be established. Here, we analyze a large dataset of >600,000 radar-detected "medium-sized" windborne insect migrants (body mass from 10 to 70 mg), flying hundreds of meters above southern UK, during the afternoon, in the period around sunset, and in the middle of the night. We found that wind-related common orientation was almost ubiquitous during the day (present in 97% of all “migration events” analyzed), and was also frequent at sunset (85%) and at night (81%). Headings were systematically offset to the right of the flow at night-time (as predicted from the use of turbulence cues for flow assessment), but there was no directional bias in the offsets during the day or at sunset. Orientation "performance” significantly increased with increasing flight altitude throughout the day and night. We conclude by discussing sensory mechanisms which most likely play a role in the selection and maintenance of wind-related flight headings

Long-term seasonal forecasting of a major migrant insect pest: the brown planthopper in the Lower Yangtze River Valley

Rice planthoppers and associated virus diseases have become the most important pests threatening food security in China and other Asian countries, incurring costs of hundreds of millions of US dollars annually in rice losses, and in expensive, environmentally harmful, and often futile control efforts. The most economically damaging species, the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae), cannot overwinter in temperate East Asia, and infestations there are initiated by several waves of windborne spring or summer migrants originating from tropical areas in Indochina. The interaction of these waves of migrants and synoptic weather patterns, driven by the semi-permanent western Pacific subtropical high-pressure (WPSH) system, is of critical importance in forecasting the timing and intensity of immigration events and determining the seriousness of subsequent planthopper build-up in the rice crop. We analysed a 26-year data set from a standardised light trap network in Southern China, showing that planthopper aerial transport and concentration processes are associated with the characteristics (strength and position) of the WPSH in the year concerned. Then, using N. lugens abundance in source areas and indices of WPSH intensity or related sea surface temperature anomalies, we developed a model to predict plan-thopper numbers immigrating into the key rice-growing area of the Lower Yangtze Valley. We also demonstrate that these WPSH-related climatic indices combined with early-season planthopper catches can be used to forecast, several months in advance, the severity of that season’s N. lugens infestations (the correlation between model predictions and outcomes was 0.59), thus allowing time for effective control measures to be implemented

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Design And Development Of L-Band Slotted Waveguide Antenna

The goal of this research is to gain more insight in the design and development of slotted waveguide antenna. A post slot waveguide antenna consists of centerline longitudinal slot with a tuning post is considered due to its numerous advantages in broadcasting industry. Slot antenna arrays allow accurate control of aperture excitation amplitude and phase

Design and Development of Ground Based Radar Systems for Vegetation Studies

In this research work, two ground-based radar systems have been developed namely the near real-time automated C-band scatterometer system (NRT-SCATT) and the wideband VNA ground-based radar system with real and synthetic aperture radar (WRSAR). They have been constructed to surmount the challenges and provide alternative solution to the existing systems

Design and construction of a near real-time advanced automated C-band scatterometer system

This paper presents the design and construction of a complete near real-time scatterometer system for in-situ measurement. The full polarimetric system is comprised of inexpensive Frequency Modulated Continuous Wave (FMCW) radar that is efficiently constructed from a combination of commercially available components and in-house fabricated circuitry. An automated advanced antenna positioning system (AAPS) is included in the development of the system, giving rise for a more practical measurement. The backscattering matrices of a 4 '' x 8 '' dihedral corner reflector are rotated and measured at different angles to provide different sets of polarimetric data. The backscattering matrices of 8 '' sphere, 12 '' sphere and 16.5 '' trihedral are also measured and the results are presented in this paper. In order to verify the effectiveness of the calibration technique, the results are compared with the theoretical values. Consideration on the challenges of measurement in outdoor environment is countered with external and internal calibration. As a result, the proposed scatterometer system has shown good correlation between measurement and theoretical results

Multi-angular scatterometer measurements for various stages of rice growth

This paper presents comprehensive measurements of radar backscatter from rice crops using a ground-based 6 GHz C-band scatterometer system. The measurements were conducted over an entire season from the early vegetative stage of the plants to the ripening stage with full polarization combinations of HH, VV, HV and VH at the incident angle range from 0 degrees. to 60 degrees.. The objective of this paper is to access the use of the ground-based scatterometer data for the investigation of temporal variation of different incident angle in the rice growth monitoring application. A further study on the angular response for different rice growth stages was also performed in order to have a better understanding of the backscattering behavior of the rice crops and therefore, monitoring of rice crops growth using operational scatterometer system

Analysis of novel slotted waveguide structure for antenna arrays application

Summary form only given. A number of approaches have been suggested for analyzing the performance of slotted waveguide antennas. In this study, a well-known technique called the method of moments (MoM) is used to design slotted waveguide antenna arrays. Novel types of slotted waveguide structure namely centerline slot with tuning screw are presented. Generally, the performance of the slotted arrays depends on the choice of physical dimension, width, and displacement of the tuning screw, number of slots and their overall arrangements. The results from the numerical simulation are compared to the widely used finite element code (high frequency structure simulator) HFSS

Classification of multi-temporal SAR images for rice crops using combined Entropy Decomposition and Support Vector Machine technique

This paper presents a combined Entropy Decomposition and Support Vector Machine (EDSVM) technique for Synthetic Aperture Radar (SAR) image classification with the application on rice monitoring. The objective of this paper is to assess the use of multi-temporal data for the supervised classification of rice planting area based on different schedules. Since adequate priori information is needed for this supervised classification, ground truth measurements of rice fields were conducted at Sungai Burung, Selangor, Malaysia for an entire season from the early vegetative stage of the plants to the ripening stage. The theoretical results of Radiative Transfer Theory based on the ground truth parameters are used to de. ne training sets of the different rice planting schedules in the feature space of Entropy Decomposition. The Support Vector Machine is then applied to the feature space to perform the image classification. The effectiveness of this algorithm is demonstrated using multi-temporal RADARSAT-1 data. The results are also used for comparison with the results based on information of training sets from the image using Maximum Likelihood technique, Entropy Decomposition technique and Support Vector Machine technique. The proposed method of EDSVM has shown to be useful in retrieving polarimetric information for each class and it gives a good separation between classes. It not only gives significant results on the classification, but also extends the application of Entropy Decomposition to cover multi-temporal data. Furthermore, the proposed method offers the ability to analyze single-polarized, multi-temporal data with the advantage of the unique features from the combined method of Entropy Decomposition and Support Vector Machine which previously only applicable to multi-polarized data. Classification based on theoretical modeling is also one of the key components in this proposed method where the results from the theoretical models can be applied as the input of the proposed method in order to de. ne the training sets