AN ECONOMIC, SQUARE-SHAPED FLAT-FIELD ILLUMINATION MODULE FOR TIRF-BASED SUPER-RESOLUTION MICROSCOPY

Super-resolution (SR) microscopy allows complex biological assemblies to be observed with remarkable resolution. However, the presence of uneven Gaussian-shaped illumination hinders its use in quantitative imaging or high-throughput assays. Methods developed to circumvent this problem are often expensive, hard-to-implement, or not applicable to total internal reflection fluorescence (TIRF) imaging. We herein demonstrate a cost-effective method to overcome these challenges using a small square-core multimodal optical fibre as the coupler. We characterise our method with synthetic, recombinant and cellular systems imaged under TIRF and highly inclined and laminated optical sheet (HILO) illuminations to demonstrate its ability to produce highly uniform images under all conditions.

Yield, Economic Benefit, Soil Water Balance, and Water Use Efficiency of Intercropped Maize/Potato in Responses to Mulching Practices on the Semiarid Loess Plateau

Increasing agricultural productivity without undermining further the integrity of the Earth’s environmental systems such as soil water balance are important tasks to ensure food security for an increasing global population in rainfed agriculture. The impact of intercropping maize (Zea mays L.) with potato (Solanum tuberosum L.) on yield, land equivalent ratios (LER), water equivalent ratio (WER), water use, energy output, and net economic return were examined under seven planting systems: potato grown solely or intercropped on the flat field without mulching, maize grown solely or intercropped with potato on ridges or flat field with or without plastic film mulched. The three intercropping systems had 3–13% less water use than the monocropping. Among the intercropped systems, flat field caused more depletion of soil water than ridged field for both years. Compared to monocultures, intercropping with plastic film mulching and ridging significantly increased LER and WER. Meanwhile, intercropping with mulching and ridging significantly increased net economic return and energy output by 8% and 24%, respectively, when compared to monocropping. These results suggest that maize under plastic film mulched ridge-furrow plot intercropped with potato under flat plot without mulching increased energy output, net economic return, and water use efficiency without increasing soil water depletion, which could be an optimal intercropping system for the semiarid farmland on the western Loess Plateau.

SPECIFICATION OF THE ABSOLUTE SPEED OF THE SOIL DISPLACED BY THE SPHERICAL DISC OF THE RIDGE SEEDER ROLLER

Heuristic and technical analysis of various designs of tillage rollers of row-crop seeders has led to the conclusion that they are mainly intended for destruction of lumps and soil compaction before and after sowing on a flat field surface. When studying the available methods for assessing the impact on improvement criteria of the design parameters and surface features of individual working elements of the ridge-forming rollers, it was revealed that, currently, there are unresolved issues, in particular, the method for specification of the absolute speed of the soil displaced by the spherical discs of the ridge seeder roller. Thus, it is necessary to substantiate theoretically this parameter of the tillage roller, which directly affects the distance between the spherical discs of the roller of the ridge seeder. For the finishing operation of formation of the soil ridge of the required parameters and density simultaneously with sowing, a roller was developed, the novelty of which is confirmed by the patents of the Russian Federation № 194330, № 194348, № 196712. The design of the roller includes regulation of the angles of attack of the spherical discs and the degree of compression of the spring, because these parameters have a significant effect on the geometric dimensions of the formed ridge and the density of the soil inside it. The proposed roller is mounted on the rear beam holder of the sowing section of the ridge seeder. Moving on the surface of the field, the ridge seeder colters sow seeds on a wet compacted bed, the ridge formers form a loose soil hill above the sown seeds and the rollers compact the soil hill. The speeds and forces acting on the spherical disc of the roller have been determined. It was theoretically revealed that the absolute speed of soil particles thrown by the edge of the spherical disc towards the symmetry longitudinal axis of the soil ridge is maximum and depends on the angular velocity of the spherical disc, its radius and angle of attack, as well as the frictional properties of the soil. As moving to the center of the spherical disc, the absolute speed of soil particles thrown from a specific point of the studied roller working body decreases

Tuneable wide-field illumination and single-molecule photoswitching with a single MEMS mirror

Homogeneous illumination in single-molecule localization microscopy (SMLM) is key for the quantitative analysis of super-resolution images. Therefore, different approaches for flat-field illumination have been introduced as alternative to the conventional Gaussian illumination. Here, we introduce a single microelectromechanical systems (MEMS) mirror as a tuneable and cost-effective device for adapting wide-field illumination in SMLM. In flat-field mode the MEMS allowed for consistent SMLM metrics across the entire field of view. Employing single-molecule photoswitching, we developed a simple yet powerful routine to benchmark different illumination schemes on the basis of local emitter brightness and ON-state lifetime. Moreover, we propose that tuning the MEMS beyond optimal flat-field conditions enables to study the kinetics of photoswitchable fluorophores within a single acquisition.

PROCESSAMENTO DIGITAL DA GALÁXIA M83 OBSERVADA COM O TELESCÓPIO CDK20

Com o avanço da tecnologia e a melhora da eficiência quântica (parâmetro físico que caracteriza detectores de radiação eletromagnética) dos equipamentos, no final do século XX, a Astronomia observacional atingiu novos patamares, podendo investigar mais longe e com mais precisão. A CCD (Charge-Coupled-Device) é o dispositivo acoplado a telescópios que possibilitou este avanço. Este equipamento consiste de uma matriz de pixels com a funcionalidade de capturar fótons de luz que são emitidos pelos objetos astronômicos. Porém, como se trata de um sistema eletrônico, ruídos indesejáveis acabam sendo somados (bias e darks) e multiplicados (flat-field) nas imagens adquiridas em função do tempo de exposição. No entanto, tais contribuições instrumentais podem ser eliminadas envolvendo operações aritméticas simples. Tais elementos serão detalhados na metodologia usada.

A first look at the SuperCam RMI images aboard Perseverance

<p>Starting in February 2021, the <strong>Perseverance rover</strong> will characterize a new landing site, the Jezero crater on Mars, and assemble a returnable cache of samples [1]. Among the remote sensing instruments, SuperCam combines chemical, mineralogical and organic spectroscopy, sound recording and imaging [2, 3, 4]. SuperCam’s <strong>RMI (Remote Micro-Imager)</strong> provides pictures for local context and site imaging at high-resolution.</p><p><br>The 110-mm SuperCam telescope with a focal length of 563 mm allows to take color images of 2048x2048 pixels with a CMOS camera on a bandwidth from ~375 to ~655 nm. The images will be divided by a reference flat-field to correct the attenuation factor of ~5 due to vignetting. The diameter of the circular field-of-view is ~18.8 mrad. The angular size of the RMI pixels is slightly less than 10 microrads, and the effective image resolution is better than 80 microrads, which represents 0.24 mm at 3 m.</p><p><br>Images will be taken at the start and end of the SuperCam raster observations [3] and assembled into annotated mosaics, which will provide information on the nature of the targets at the scale of the SuperCam investigation. Images will also be taken to study remote outcrops. At the time of the conference, Perseverance will have been on Mars for 2 months. Although the first images of the RMI will be used to check the health of the instrument, we also hope to have a first view of the landing site by then.</p><p><br><strong>References:</strong> [1] Farley K.A. et al. (2020) SSR, 216, 142. [2] Maurice S. et al. (in revision) SSR. [3] Wiens R.C. et al. (2021) SSR, 217, 4. [4] Maurice S. et al. (this issue). </p>