77 research outputs found
Germany's Agenda for the 90's.
No full textDraft of a speech at the 85th Annual Meeting of the American Jewish Committee, outlining the moral and material responsibilities of the new, united Germany to play a peaceful role in the world, to preserve and open the archives of the former GDR, and to participate constructively in efforts to reach peace in the Middle East.The author Michael Mertes (born 1953 in Bonn, Germany) was a German chief officer and political advisor to Chancellor Helmut Kohl from 1987, when Mertes became the chancellor’s chief speechwriter. After the fall of the Berlin Wall Mertes co-authored the „Ten Point Program for German and European Unity”
Colors 1981
No full textCONTENTS
Untitled, John I. C. Ramirez 2;
Love will fly, Tim Furness 3;
Untitled, Palmer Hoovestal 4;
The wave, Jerome Lightbourne 6;
The land*lord, R. Lea 7;
Song of the newborn, Heidi Muller 8;
Untitled, Mary Ostervold 9;
Good crops, Gina Larson 10;
Come, challenge the sea, Paula Schafer 12;
Untitled, Pat Dooris 14;
Untitled, Eric Peterson 16;
A flight of fancy, Tony Schaan 17;
Ode upon a london tube, Kit Warfield 18;
Sponge, Debbie Court 19;
Untitled, Debbie Court 20;
Untitled, John I. C. Ramirez 21;
Untitled, Joyce Lowry 21;
Untitled, Mary Taft 22;
Thank you, Lord [unidentified author] 23;
From generation to generation, Denise Marsh 24;
Untitled, S. M. 25;
Untitled, M. F. 26;
Brain Cramp, Francine Bergeron 27;
Untitled, Pat Dooris 28;
Untitled, Tom Mertes 30;
Untitled, John I. C. Ramirez 31;
Untitled, Dolores Bock 31;
Untitled, Christopher Perez 32;
Untitled, Pat Dooris 33;
Echoes of Innocence, Kelly Cosgrove 35;
Beloved, M. Bowen 36;
Untitled, Mary Ostervold 36
What makes a landmark a landmark? How active vision strategies help honeybees to process salient visual features for spatial learning
No full textMertes M. Primary sensory processing of visual and olfactory signals in the bumblebee brain. Bielefeld: Bielefeld University; 2013.Since decades honeybees are being used as an insect model system for answering scientific questions in a variety of areas. This is due to their enormous behavioural repertoire paired with their learning capabilities. Similar learning capabilities are also evident in bumblebees that are closely related to honeybees. As honeybees, they are central place foragers that commute between a reliable food source and their nest and,
therefore, need to remember particular facets of their environment to reliably find back to these places.
Via their flight style that consists of fast head and body rotations (saccades)interspersed with flight segments of almost no rotational movements of the head (intersaccades)
it is possible to acquire distance information about objects in the environment.
Depending on the structure of the environment bumblebees as well as honeybees can use these objects as landmarks to guide their way between the nest and a particular
food source. Landmark learning as a visual task depends of course on the visual input perceived by the animal’s eyes. As this visual input rapidly changes during head saccades,
we recorded in my first project bumblebees with high-speed cameras in an indoor flight arena, while they were solving a navigation task that required them to orient according to landmarks. First of all we tracked head orientation during whole flight periods that served to learn the spatial arrangement of the landmarks. Like this we
acquired detailed data on the fine structure of their head saccades that shape the visual input they perceive. Head-saccades of bumblebees exhibit a consistent relationship between their duration, peak velocity and amplitude resembling the human so-called
"saccadic main sequence" in its main characteristics. We also found the bumblebees’saccadic sequence to be highly stereotyped, similar to many other animals. This hints
at a common principle of reliably reducing the time during which the eye is moved by fast and precise motor control.
In my first project I tested bumblebees with salient landmarks in front of a background covered with a random-dot pattern. In a previous study, honeybees were trained with the same landmark arrangement and were additionally tested using landmarks that were camouflaged against the background. As the pattern of the landmark textures did not seem to affect their performance in finding the goal location, it had been assumed
that the way they acquire information about the spatial relationship between objects is independent of the objects texture.
Our aim for the second project of my dissertation was therefore to record the activity of motion sensitive neurons in the bumblebee to analyse in how far object
information is contained in a navigation-related visual stimulus movie. Also we wanted to clarify, if object texture is represented by the neural responses. As recording from neurons in free-flying bumblebees is not possible, we used one of the recorded bumblebee
trajectories to reconstruct a three-dimensional flight path including data on the head orientation. We therefore could reconstruct ego-perspective movies of a bumblebee
10 while solving a navigational task. These movies were presented to motion-sensitive neurons in the bumblebee lobula. We found for two different classes of neurons that
object information was contained in the neuronal response traces. Furthermore, during the intersaccadic parts of flight the object’s texture did not change the general response profile of these neurons, which nicely matches the behavioural findings. However, slight changes in the response profiles acquired for the saccadic parts of flight might allow to extract texture information from these neurons at later processing stages.
In the final project of my dissertation I switched from exploring coding of visual information to the coding of olfactory signals. For honeybees and bumblebees olfaction is approximately equally important for their behaviour as their vision sense. But whereas there is a solid knowledge base on honeybee olfaction with detailed studies on the
single stages of olfactory information processing this knowledge was missing for the bumblebee. In the first step we conducted staining experiments and confocal microscopy
to identify input tracts conveying information from the antennae to the first processing stage of olfactory information – the antennal lobe (AL ). Using three-dimensional reconstruction of the AL we could further elucidate typical numbers of single spheroidal
shaped subunits of the AL , which are called glomeruli. Odour molecules that the bumblebee perceives induce typical activation patterns characteristic of particular
odours. By retrogradely staining the output tracts that connect the AL to higher order processing stages with a calcium indicator, we were capable of recording the odourdependent activation patterns of the AL glomeruli and to describe their basic coding principles. Similarly as in honeybees, we could show that the odours’ carbon chain
length as well as their functional groups are dimensions that the antennal lobe glomeruli are coding in their spatial response pattern. Applying correlation methods underlined the strong similarity of the glomerular activity pattern between honeybees and bumblebees
Bumblebee Homing: The Fine Structure of Head Turning Movements
No full textBoeddeker N, Mertes M, Dittmar L, Egelhaaf M. Bumblebee Homing: The Fine Structure of Head Turning Movements. PLoS ONE. 2015;10(9): e0135020.Changes in flight direction in flying insects are largely due to roll, yaw and pitch rotations of their body. Head orientation is stabilized for most of the time by counter rotation. Here, we use high-speed video to analyse head- and body-movements of the bumblebee Bombus terrestris while approaching and departing from a food source located between three landmarks in an indoor flight-arena. The flight paths consist of almost straight flight segments that are interspersed with rapid turns. These short and fast yaw turns (“saccades”) are usually accompanied by even faster head yaw turns that change gaze direction. Since a large part of image rotation is thereby reduced to brief instants of time, this behavioural pattern facilitates depth perception from visual motion parallax during the intersaccadic intervals. The detailed analysis of the fine structure of the bees’ head turning movements shows that the time course of single head saccades is very stereotypical. We find a consistent relationship between the duration, peak velocity and amplitude of saccadic head movements, which in its main characteristics resembles the so-called "saccadic main sequence" in humans. The fact that bumblebee head saccades are highly stereotyped as in humans, may hint at a common principle, where fast and precise motor control is used to reliably reduce the time during which the retinal images moves
Visual motion-sensitive neurons in the bumblebee brain convey information about landmarks during a navigational task
No full textMertes M, Dittmar L, Egelhaaf M, Boeddeker N. Visual motion-sensitive neurons in the bumblebee brain convey information about landmarks during a navigational task. Frontiers in Behavioral Neuroscience. 2014;8:335.Bees use visual memories to find the spatial location of previously learnt food sites. Characteristic learning flights help acquiring these memories at newly discovered foraging locations where landmarks-salient objects in the vicinity of the goal location-can play an important role in guiding the animal's homing behavior. Although behavioral experiments have shown that bees can use a variety of visual cues to distinguish objects as landmarks, the question of how landmark features are encoded by the visual system is still open. Recently, it could be shown that motion cues are sufficient to allow bees localizing their goal using landmarks that can hardly be discriminated from the background texture. Here, we tested the hypothesis that motion sensitive neurons in the bee's visual pathway provide information about such landmarks during a learning flight and might, thus, play a role for goal localization. We tracked learning flights of free-flying bumblebees (Bombus terrestris) in an arena with distinct visual landmarks, reconstructed the visual input during these flights, and replayed ego-perspective movies to tethered bumblebees while recording the activity of direction-selective wide-field neurons in their optic lobe. By comparing neuronal responses during a typical learning flight and targeted modifications of landmark properties in this movie we demonstrate that these objects are indeed represented in the bee's visual motion pathway. We find that object-induced responses vary little with object texture, which is in agreement with behavioral evidence. These neurons thus convey information about landmark properties that are useful for view-based homing
Data set: Head movements in bumblebees
No full textBoeddeker N, Mertes M, Dittmar L, Egelhaaf M. Data set: Head movements in bumblebees. Bielefeld University; 2015.Changes in flight direction in flying insects are largely due to roll, yaw and pitch rotations of their body. Head orientation is stabilized for most of the time by counter rotation. Here, we use high-speed video to analyse head- and body-movements of the bumblebee Bombus terrestris while approaching and departing from a food source located between three landmarks in an indoor flight-arena. The flight paths consist of almost straight flight segments that are interspersed with rapid turns. These short and fast yaw turns (“saccades”) are usually accompanied by even faster head yaw turns that change gaze direction. Since a large part of image rotation is thereby reduced to brief instants of time, this behavioural pattern facilitates depth perception from visual motion parallax during the intersaccadic intervals. The detailed analysis of the fine structure of the bees’ head turning movements shows that the time course of single head saccades is very stereotypical. We find a consistent relationship between the duration, peak velocity and amplitude of saccadic head movements, which in its main characteristics resembles the so-called "saccadic main sequence" in humans. The fact that bumblebee head saccades are highly stereotyped as in humans, may hint at a common principle, where fast and precise motor control is used to reliably reduce the time during which the retinal images moves.
All raw data are available in the the binary matlab file “res.mat”. It contains two variables of the class struct. You can load the data using the command load('res.mat') in Matlab. The two variables “TBLFlight” “returnFlight” contain two fields: “yawAngle” and “HeadPos”. The values in yawAngle are given in degrees and HeadPos in Pixels. All data presented in the manuscript are derived from “yawAngle”
Airborne in-situ measurements of the aerosol absorption coefficient, aerosol particle number concentration and size distribution of cloud particle residuals and ambient aerosol particles during the ACLOUD campaign in May and June 2017
No full textThis data set consists of in-situ measurements of arctic ambient aerosol particle (outside cloud) and cloud particle residual (inside cloud) aerosol properties observed during the ACLOUD campaign which took place during May/June 2017, which was part of the AC3 project. These measurements were made using the CVI inlet and PSAP, CPC and UHSAS aerosol instruments of the Leibniz Institute for Tropospheric Research (TROPOS) in Leipzig, Germany. The CVI flag 0 or 1 denotes ambient aerosol or cloud particle residual measurements, respectively, accomplished by a change in the sampling behavior of the CVI inlet. Measurements just after switching from one mode to another should be treated with caution, especially for the absorption coefficient values which have a time resolution of 30 sec. The given data sets are already corrected for the CVI enrichment factor, which should also be applied for measurements of other groups behind the CVI. Another correction for cloud particle residual measurements only is the CVI aspiration and sampling efficiency, which can be inferred from the comparison with the in-situ cloud particle measurements. Contact the PI and contact person Stephan Mertes for more information. Use only measurement data after takeoff and before landing of the Polar 6 aircraft. CVI inlet heating broke 2017-06-14T15:43:08, so that inlet freezing could have been occurred thereafter. Those periods are tried to identified and data deleted. The UHSAS two dimensional size distribution data is given in size bin diameter Dp (nm) in the header and the dN/dlogDp (cm-3 nm-1) value starting from column 13. The UHSAS instrument broke 2017-06-17T11:41:12. From this point in time no size distribution data are provided anymore. There is one file per flight. A detailed description of the data processing will be done in an upcoming data paper
Out of the box: how bees orient in an ambiguous environment
No full textDittmar L, Stürzl W, Jetzschke S, Mertes M, Boeddeker N. Out of the box: how bees orient in an ambiguous environment. Animal Behaviour. 2014;89:13-21.How do bees employ multiple visual cues for homing? They could either combine the available cues using a view-based computational mechanism or pick one cue. We tested these strategies by training honeybees, Apis mellifera carnica, and bumblebees, Bombus terrestris, to locate food in one of the four corners of a box-shaped flight arena, providing multiple and also ambiguous cues. In tests, bees confused the diagonally opposite corners, which looked the same from the inside of the box owing to its rectangular shape and because these corners carried the same local colour cues. These 'rotational errors' indicate that the bees did not use compass information inferred from the geomagnetic field under our experimental conditions. When we then swapped cues between corners, bees preferred corners that had local cues similar to the trained corner, even when the geometric relations were incorrect. Apparently, they relied on views, a finding that we corroborated by computer simulations in which we assumed that bees try to match a memorized view of the goal location with the current view when they return to the box. However, when extra visual cues outside the box were provided, bees were able to resolve the ambiguity and locate the correct corner. We show that this performance cannot be explained by view matching from inside the box. Indeed, the bees adapted their behaviour and actively acquired information by leaving the arena and flying towards the cues outside the box. From there they re-entered the arena at the correct corner, now ignoring local cues that previously dominated their choices. All individuals of both species came up with this new behavioural strategy for solving the problem provided by the local ambiguity within the box. Thus both species seemed to be solving the ambiguous task by using their route memory, which is always available during their natural foraging behaviour. (C) 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved
Development of a Combinator Curve Generator
No full textOften, vessels have multiple operation modes that are specialised for a certain task. If a vessel is employed with a controllable pitch propeller(CPP), the blade pitch can be adjusted, adding a degree of freedom to the system. This advantage creates the possibility to increase the diversity of operation modes of the vessel and allows for flexibility, precision and specialisation for a certain task. Additionally, CPPs can be controlled such, that operational limits of the driving machinery are not exceeded.As vessels have become increasingly diverse with respect to their functional abilities, and complex with respect to their propulsion configurations, design of combinator curves becomes increasingly labour intensive. Earlier developed software applications, that aim to support the matching process or combinator settings, lack clear insight of important performance indicators and their impact on the combinator curve design. In this thesis, a Combinator Curve Generator(CCG) is developed to support the design of combinator curves for vessels that employ CPPs, in order to decrease the labour intensity of the combinator design process. Further, approaches are developed to optimise combinator curves for operation modes of a vessel in terms of four performance indicators; propeller efficiency, cavitation inception, engine efficiency and fuel consumption. The approaches are implemented in the CCG such that a combinator curve can be designed, optimised and evaluated. Additionally, a trip simulation tool is developed and added to the CCG, in order to determine and evaluate the total fuel consumption of a trip for different cruise speeds and a certain time duration, whilst taking into account the distance, the operational profile of the vessel, the combinator settings and the hotel load. Important recommendations for further development include extension of the database of inception diagrams for propellers with different blade area ratios, and the broadening of the propulsion configuration scope, such that different main engines and power supply systems can be considered. Finally, it is recommended to research the possibility to calibrate the effective angle of attack method on the basis of the optimisation approach proposed in this thesis.<br/
Análise bitemporal do Rio Solimões no trecho entre os municípios de Manacapuru e Codajás (Amazônia Ocidental) por meio de imagens Landsat-5/TM
No full textNas últimas décadas, as características geomorfológicas dos canais e áreas de planícies de inundação do sistema fluvial Solimões-Amazonas têm sido analisadas com base em produtos de sensores remotos e cartas de navegação. Em alguns trabalhos (Mertes et al. 1996, Nobre 2010), a análise multitemporal de trechos dos rios Solimões e Amazonas tem sido feita com base em dados de sensoriamento remoto, que mostram as modificações dos canais fluviais deste sistema, destacando as áreas de deposição e erosão. Em geral, a erosão nas barrancas do Rio Solimões, é marcada por desmoronamentos constantes, os quais tem sido associados ao fenômeno das terras caídas ou quedas de barranco , que causam transtornos sociais e econômicos à população ribeirinha. Esta terminologia popular característica da da região amazônica, serve para explicar fenômenos erosivos determinados pela dinâmica fluvial, onde a erosão está associada a instabilidade do material arenoso inconsolidado que compõe parte dos terraços fluviais que margeiam o canal, sendo também intensificada pela ondas dos banzeiros, devido ao transporte fluvial de cargas e pessoas. O fenômeno das terras caídas se intensifica na porção frontal das ilhas e nos meandros dos canais (principal e secundário), sendo intensificado no período das enchentes dos rios. Portanto, este projeto PIBIC visa estudar a dinâmica fluvial do Rio Amazonas, entre os municípios de Careiro da várzea e Autazes, por meio da análise bitemporal de imagens ópticas Landsat-5/TM obtidas nos últimos 24 anos, visando identificar as áreas de erosão e deposição.Voluntári
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