Study of sensoric properties of organic semiconductors

Látky na bázi diketopyrrolopyrrolu jsou organické pigmenty, které mají charakter polovodičů. Jejich analogy s pyridylovou boční skupinou jsou díky své citlivosti na vodík potenciálně využitelné jako vodíkové senzory. Cílem bakalářské práce bylo zkoumat vlastnosti senzorů s aktivní vrstvou z derivátů diketopyrrolopyrrolu. Testování senzorů probíhalo na aparatuře, která byla sestavena na FCH VUT v Brně. Konkrétně byly sledovány změny vodivosti senzorů v přítomnosti vodíku za různých podmínek.Compounds based on diketopyrrolopyrrole are organic pigments that behave as semi-conductors. Their analogues with pyridyl side group are due to their sensitivity to hydrogen potentially useful as hydrogen sensors. The aim of this work was to examine properties of sensors with an active layer of diketopyrollopyrolle derivatives. The sensors were tested on an apparatus built for this purpose at FCH VUT in Brno. More specifically, changes to conductivity of these sensors in the presence of hydrogen under various conditions were studied.

Sensoric properties of organic N-type semiconductors and their air stability

O vodíku se již delší dobu diskutuje jako o nástupci fosilních paliv, jejichž zásoby se neustále zmenšují. Jedním z nezbytných předpokladů pro možné využití vodíku jako nosiče energie je jeho spolehlivá detekce. V souvislosti s rozvojem organické elektroniky se naskytla možnost využití derivátů diketopyrrolopyrrolu jako aktivních látek vodíkových senzorů. Deriváty diketopyrrolopyrrolu jsou organické pigmenty, které mají charakter polovodičů. Jejich analogy s pyridinovou skupinou díky volným elektronovým párům atomu dusíku vykazují citlivost na vodík. Obecným problémem organických N-typových polovodičů je však jejich nestabilita na vzduchu. Tato práce je tedy zaměřena na testování vlastností vodíkových senzorů s aktivní vrstvou z derivátů diketopyrrolopyrrolu a posouzení jejich stability na vzduchu.Hydrogen has been for some time discussed as a successor to fossil fuels whose stocks are constantly running low. One of the crucial requirements for the possible usage of hydrogen as an energy carrier is our ability of reliable detection. In context with development of organic electronics there occurred a possibility to use derivatives of diketopyrrolopyrroles as sensing materials of hydrogen sensors. Derivatives of diketopyrrolopyrrole are organic pigments that behave as semiconductors. Their analogues with pyridyl side group are due to free electron pairs of nitrogen atoms sensitive to hydrogen. The problem of organic N-type semiconductors is in general their instability on the air. This thesis is focused on testing of hydrogen sensors with active layer made from derivatives of diketopyrrolopyrrole and judging their stability on the air.

The resilience of weed seedbank regulation by carabid beetles, at continental scales, to alternative prey

Carabids are generalist predators that contribute to the agricultural ecosystem service of seedbank regulation via weed seed predation. To facilitate adoption of this ecosystem services by farmers, knowledge of weed seed predation and the resilience of seedbank regulation with co-varying availability of alternative prey is crucial. Using assessments of the seedbank and predation on seed cards in 57 cereal fields across Europe, we demonstrate a regulatory effect on the soil seedbank, at a continental scale, by groups formed of omnivore, seed-eating (granivore+omnivore) and all species of carabids just prior to the crop-harvest. Regulation was associated with a positive relationship between the activity-density of carabids and seed predation, as measured on seed cards. We found that per capita seed consumption on the cards co-varied negatively with the biomass of alternative prey, i.e. Aphididae, Collembola and total alternative prey biomass. Our results underline the importance of weed seedbank regulation by carabids, across geographically significant scales, and indicate that the effectiveness of this biocontrol may depend on the availability of alternative prey that disrupt the weed seed predation

MRS Drone: A Modular Platform for Real-World Deployment of Aerial Multi-Robot Systems

This paper presents a modular autonomous Unmanned Aerial Vehicle (UAV) platform called the Multi-robot Systems (MRS) Drone that can be used in a large range of indoor and outdoor applications. The MRS Drone features unique modularity with respect to changes in actuators, frames, and sensory configuration. As the name suggests, the platform is specially tailored for deployment within a MRS group. The MRS Drone contributes to the state-of-the-art of UAV platforms by allowing smooth real-world deployment of multiple aerial robots, as well as by outperforming other platforms with its modularity. For real-world multi-robot deployment in various applications, the platform is easy to both assemble and modify. Moreover, it is accompanied by a realistic simulator to enable safe pre-flight testing and a smooth transition to complex real-world experiments. In this manuscript, we present mechanical and electrical designs, software architecture, and technical specifications to build a fully autonomous multi UAV system. Finally, we demonstrate the full capabilities and the unique modularity of the MRS Drone in various real-world applications that required a diverse range of platform configurations.Comment: 49 pages, 39 figures, accepted for publication to the Journal of Intelligent & Robotic System

Present and Future of SLAM in Extreme Underground Environments

This paper reports on the state of the art in underground SLAM by discussing different SLAM strategies and results across six teams that participated in the three-year-long SubT competition. In particular, the paper has four main goals. First, we review the algorithms, architectures, and systems adopted by the teams; particular emphasis is put on lidar-centric SLAM solutions (the go-to approach for virtually all teams in the competition), heterogeneous multi-robot operation (including both aerial and ground robots), and real-world underground operation (from the presence of obscurants to the need to handle tight computational constraints). We do not shy away from discussing the dirty details behind the different SubT SLAM systems, which are often omitted from technical papers. Second, we discuss the maturity of the field by highlighting what is possible with the current SLAM systems and what we believe is within reach with some good systems engineering. Third, we outline what we believe are fundamental open problems, that are likely to require further research to break through. Finally, we provide a list of open-source SLAM implementations and datasets that have been produced during the SubT challenge and related efforts, and constitute a useful resource for researchers and practitioners.Comment: 21 pages including references. This survey paper is submitted to IEEE Transactions on Robotics for pre-approva

Aphids (Homoptera: Aphididae) on Winter Wheat: Predicting Maximum Abundance of Metopolophium dirhodum

In Central Europe, the most abundant aphid infesting the leaves of small grain cereals is Metopolophium dirhodum (Walker) (Homoptera: Aphididae). Annual variation in its seasonal dynamics was evaluated using a 25-yr series of standardized weekly censuses of winter wheat plots. M. dirhodum made up >50 % of the aphids on the foliage. Date of immigration (8 May–3 July), length of period of population increase (0–9 wk), and date of attaining maximum abundance (28 May–22 July) varied greatly. For the prediction, we regressed maximum numbers/tiller on numbers recorded in the first week after heading. The regression of maximum abundance on nonzero aphid counts revealed a critical number of ≥1.50 aphids/tiller, which if exceeded resulted in a harmful maximum abundance of ≥10 aphids/tiller at the peak. Zero aphid counts resulted in 10% of cases with a harmful maximum abundance. Using this regression for prediction will result in 18% of the recorded cases being false negatives and 9% false positives. Parallel annual variation in the average maximum numbers of M. dirhodum, Sitobion avenae (Fabricius) (Homoptera: Aphididae), and Rhopalosiphum padi (Linné) (Homoptera: Aphididae) indicated the following factors that affected their abundance: temperature in winter and host plant quality. The predictions apply only in areas where M. dirhodum is holocyclic and aphids do not overwinter in wheat stands

Forty years of carabid beetle research in Europe - from taxonomy, biology, ecology and population studies to bioindication, habitat assessment and conservation

Volume: 100Start Page: 55End Page: 14

How to make a meta-analyst happy – what to report in your studies and how

Meta-analysis represents an approach of synthesizing many independent data sets, and is useful in situations when abundant literature provides no conclusive evidence. Besides the quality of the research itself, the value of an individual study for meta-analysis depends to the large extent also on the quality of data presentation. The literature based on carabid beetles (Coleoptera: Carabidae) as the study is enormous, therefore there is a great potential for the use in meta-analyses. In this paper I put together some notes which arose during my work on meta-analysis focused on the effects of field and crop management on populations of carabid beetles inside the crop fields of Europe and America north of Mexico. The aim of this contribution is to provide a set of recommendations which may potentially improve the use of each individual paper in future meta-analyses, and thus increase the impact of the original paper as well as the generality of conclusions drawn from future meta-analyses, hence based on larger sample size. Be accurate in describing the treatments. For example, “low” and “high intensity of management” is not enough. Mention also details that are constant across treatments, but may still provide useful information. E.g. “practice usual for the area” is not enough. Be precise with describing spatio-temporal structure in the study. Provide redundant information so everyone can check if he/she understood well the hierarchy of the experiment and the number of replications associated with each stratum. A scheme may be useful. Report the grand totals as well as treatment totals for both “abundance” and species richness. Text, tables or supplementary materials is preferred. If using mean values, always make it clear what is the number of replicates and provide standard errors. But, remember that total or treatment species richness cannot be reconstructed from the mean! Be explicit in stating what the means represent, also in figures. Expressions like “Mean abundance” are not enough. Provide species lists with the greatest resolution possible. Most journals allow for supplementary materials where this information can be provided.   Remember that data can also be extracted from figures. Provide high resolution and accurate figures. For example, large data points on a line make data extraction difficult.   With little extra effort during the preparation phase, the impact of your paper and the use of your data may considerably increase in the future

Some seed properties affecting seed choice by Poecilus cupreus

Seed predators are an integral part of agrocoenoses where they contribute to the reduction of weed populations. Although they are taking part in biological control of weed seeds, we still do not understand which properties of seeds are responsible for variable attractiveness of different species of seeds to carabids beetles.  Seed coat provides a physical barrier and hinders volatiles to be released from the seeds when these are dry. In this work, we focused on seed preferences of Taraxacum officinale and Stellaria media by a ground beetle (Coleoptera: Carabidae) species, Poecilus cupreus, which is known as an omnivorous species. The seeds were used in three different states - dry, imbibed and with crushed seed coat, and from two different origins. The seeds were presented simultaneously in an experimental arena. Seed consumption was assessed after 30 minutes, 24 hours and 48 hours of exposure. There was no statistically significant difference between seeds with different origin. The most preferred seeds were T. officinale with damaged seed coat. The total consumption of these seeds was was 0.1 % after 30 minutes, 13.8 % after 1 day and 71.5 % after 48 hours. The seeds of S. media were consumed less. This indicates that the consumption was enhanced by either an increase of volatile compounds from the damaged seeds that attracted the beetles, or from shorter handling time due to reduced physical barrier of the crushed coat

Preferences of carabid beetles (Coleoptera: Carabidae) for herbaceous seeds

Preferences of seed predators may be an important factor that introduces bias in the results of seed predation studies. In this paper, we report on the experimentally established preferences of carabid beetles for seeds of herbaceous plants. The standard arrangement of 28 species of seeds from 13 families was offered to 37 species of carabids belonging to 5 tribes. The overall consumption was affected by the body mass more than by the body length and showed a quadratic relationship with the dry body mass of the carabid. The number of preferred species of seeds varied from 1 to 16, and in unspecialized species the ordered standardized consumptions formed an almost straight line with negative slope, while in specialized to highly specialized species the standardized consumption exponentially declined with increasing order of species. The most preferred seeds were Taraxacum officinale, Capsella bursa-pastoris, Tripleurospermum inodorum and Descurainia sophia, which were preferred by 28, 20, 19 and 19 species of carabids, respectively, while Consolida regalis, Arctia lappa and Bidens tripartita were not preferred by any of the studied carabids. We pinpoint that choice for a model seed species for a seed predation experiment in the field shall reflect the attractiveness of the seed for predators as seed identity may bring bias in the results