Top PDF Polarization-based Navigation in Drosophila

Polarization-based Navigation in Drosophila

Polarization-based Navigation in Drosophila

Central place foragers such as bees and desert ants have been the subject of in- tensive investigation into the role of a celestial compass in insect navigation. Among other topics, the important concepts of time compensation (Dyer and Dickinson, 1994; Wehner, 1984), path integration (Collett et al., 2006; Wittlinger et al., 2006), and multisensory integration (Dyer, 1996; Müller and Wehner, 2007) have been ex- amined in detail in these organisms. A small specialized region of the eye called the dorsal rim area is thought to be critical for these behaviors in many species (Lab- hart and Meyer, 1999; Wehner and Strasser, 1985), although the evidence in ies is somewhat contradictory. Flies possess a dorsal rim area, which has been implicated in polarization responses (von Philipsborn and Labhart, 1990), but prior experiments using a tethered ight arena suggest that the rest of the eye may play a role in re- sponses to polarized light (Wolf et al., 1980). Our results do not bear directly on this discrepancy, because our sky stimulus was visible to ommatidia both within and outside the dorsal rim area. Within the dorsal rim area, photoreceptors R7 and R8, which have been proposed to underlie polarization vision, both express an opsin with a peak sensitivity in the ultraviolet. Thus, our observation of polarization-dependent responses to wavelengths longer than 400 nm provides further indirect evidence for the role of other photoreceptors besides R7 and R8 within the dorsal rim. We cannot, however, rule out their involvement because it is possible that they exhibit some small but functional sensitivity to the wavelengths used in our experiments. The possible existence of alternate, spectrally distinct pathways for detecting polarized light may have contributed to the variability we measured in experiments in which UV light was attenuated by lters.
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Celestial navigation in Drosophila

Celestial navigation in Drosophila

All evidence from experiments with both polarized light and a sun stimulus suggests that flies choose a heading at random and then maintain that orientation over time, but how they acquire their initial preference is enigmatic. Based on evidence from other insects, the possible explanations cluster around two extremes: (1) flies possess a developmentally or environmentally pre-programmed heading preference, or (2) flies choose a heading during the first few minutes of flight. Neither of these two hypotheses is entirely consistent with the experiments that we have reviewed thus far. Flies remember their heading preferences from one flight bout to the next for both patterns of polarized light and sun position (e.g. Fig. 5E); however, this result is consistent with both the pre-programmed and choice models, assuming that once a fly selects a heading, it remembers that choice for several hours. The observation that bout-to-bout heading fidelity for sun orientation is maintained for up to 6 h (Fig. 5E) seems to lend weight to the pre-programmed hypothesis. However, datasets for 5 min and 1 h gaps show a closer correspondence between first and second flights than datasets with longer inter-trial intervals. Whether this is reflective of a gradual memory decay or a consequence of the longer durations that flies remained tethered will require additional experiments – for example, testing flies repeatedly over many hours. As noted above, vector strength increases gradually at the beginning of a first closed-loop experiment with a pattern of polarized light – a phenomenon that might reflect a reinforcement process as a fly chooses its heading (Warren et al., 2018). However, this gradual rise in vector strength is not observed at the start of closed-loop experiments using a sun stimulus (Y.M.G., unpublished data). This difference could reflect important distinctions between the sun position and polarization pathways or might merely indicate more mundane differences in the two experimental paradigms. Although it seems imprudent to entirely rule out the pre-programmed hypothesis, the choice model is attractive because it is consistent with a recently described ‘ snapshot ’ mechanism by which dung beetles acquire their heading preference just before they begin to roll a newly formed dung ball (Baird et al., 2012; el Jundi et al., 2016).
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Multiple Roles for Egalitarian in Polarization of the Drosophila Egg Chamber

Multiple Roles for Egalitarian in Polarization of the Drosophila Egg Chamber

We first examined microtubule organization in these Egl- depleted egg chambers. As noted previously, the initiating event in reorganization of oocyte microtubules is the oocyte enrichment of grk mRNA and protein in stage 5 egg cham- bers. In contrast to what was observed using the early-stage driver, grk mRNA localization and Grk protein accumulation within the oocyte was unaffected upon expression of egl shRNA-1 using the midstage driver (Figure S5, A–E). Con- sistent with this finding, the overall microtubule organiza- tion in stage 10 egg chambers resembled wild type (Figure 8, F and G). Furthermore, microtubule plus ends were enriched at the posterior pole and microtubule minus ends were de- tected around the cortex in these Egl-depleted egg chambers (Figure 8, H and I). In addition, the cortical localization of BicD was restored and Dhc was enriched at the posterior pole in egg chambers expressing egl shRNA-1 using the midstage driver (Figure 8, J and K). Thus, despite the fact that these stage 10 egg chambers are significantly depleted of Egl, their micro- tubule organization appears unaffected. Based on these results, we conclude that Egl is required between stages 5 and 7 for establishing the proper organization of oocyte microtubules. However, once this organization has been established, Egl does not appear to be required for maintaining microtubule organi- zation in stage 10 egg chambers. One potential limitation of this conclusion, however, is that subtle defects might be present in the organization of oocyte microtubules that are not detected by our assays.
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A Cdc42 regulated actin cytoskeleton mediates Drosophila oocyte polarization

A Cdc42 regulated actin cytoskeleton mediates Drosophila oocyte polarization

clones displayed a mislocalized nucleus and mislocalized Staufen protein (25% mislocalization; supplementary material Fig. S3A,B). We also observed a lack of posterior accumulation of Vasa in 30% of the egg chambers analyzed (supplementary material Fig. S3C,D), a defect not reported previously (Genova et al., 2000). To further confirm that Cdc42 is also required at later stages, we constructed a miR-1 scaffold-based (Ni et al., 2008) small hairpin RNA (shRNA) against Cdc42 that we expressed in the germline using the strong maternal driver oskar-Gal4 (supplementary material Fig. S4). Expression of this construct led to an 80% reduction in Cdc42 protein levels on western blots (Fig. 3B) and loss of detectable Cdc42 signal from the anterolateral cortex of the oocyte (Fig. 3C,D). The early oocyte polarity marker Orb
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Feature-based Optical Navigation for Lunar Landings

Feature-based Optical Navigation for Lunar Landings

Another system for which closed-loop flight tests have been performed is Autonomous Terrain-based Op- tical Navigation (ATON) currently being developed by Deutsches Zentrum für Luft- und Raumfahrt (Germany Aerospace Center) (DLR). The navigation system is intended for landings on solar system bodies with no or very thin atmosphere [Theil et al., 2017]. The required landing accuracy is 100 m. This requirement translates to an accuracy of 1% and 0.5% of altitude for cross-range and height, respectively, during Descent Orbit (DO). Although the system is being developed for general use, a reference lunar mission has been defined, which has been used for the simulations and tests performed. The landing mission begins in a 100 × 100 km parking orbit, followed by a 100 × 10 km DO. The PD begins close to the pericenter and, for the final 100 s, the lander is almost vertically aligned with the surface. At an altitude of 1 m, the required velocity is of 1 m/s.
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Kinect based character navigation in VR Game

Kinect based character navigation in VR Game

VR game is a hot field because it provides practical experience for the player. However, in the game, players are usually required attaching special equipments. Those equipments are often very expensive. Moreover, many devices make players less flexible because they are attached to players. VR game using Kinect is a good choice because Kinect is a ff ordable and not attached directly to the player. In this paper, we propose a technique of Kinect based character navigation in VR Game. As environment is supported by Kinect, we implement character navigation by player’s hand actions. Besides, we use markers to increase the e ff ectiveness of hand action recognition. In our experiments, character’s rotations reaches 70% in accuracy. Straight movement and turning reach 98% in accuracy.
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VLC BASED INDOOR BLIND NAVIGATION SYSTEM

VLC BASED INDOOR BLIND NAVIGATION SYSTEM

LANDMARC is a location sensing prototype system to locate objects using Radio Frequency Identification (RFID) inside buildings. It has its own advantage of improving the total accuracy of locating objects by using the concept of reference tags. It is also feasible and cost-effective in sensing indoor locations. Automatic location sensing is a problem addressed in the emerging systems. To make RFID technology effective in indoor location sensing, three major features are added: triangulation, scene analysis and proximity. The well-known location-based system (GPS) is inefficient in determining the location of indoor objects as it is satellite dependent. The main intention is developing indoor location sensing system using easily accessible wireless devices so that existing infrastructures could be used. Infrared, 802.11, ultrasonic are some techniques that have their own advantages and disadvantages.
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Contact-based navigation for an autonomous flying robot

Contact-based navigation for an autonomous flying robot

In this paper, we suggest to augment the platform pictured in fig 1 with the sense of touch, and exploit collisions similarly to a flying insect that repeatedly collides with a window until it finds an escape route. Instead of falling to the ground when a collision is detected, we suggest that we can stay in the air most of the time and learn from the information collected during the collision to control the robot. Touch is commonly used on ground robots as sole sensors for 2D navigation [12] or as a complementary modality to additional positioning sensors [13]. Navigation strategies using only touch sensing include area coverage tasks, for example for vacuum cleaning [14], or obstacle following [15]. Some systems equipped with distance or positioning sensors use the sense of touch to detect unpredictable or moving obstacles that may not be detected by the other sensors [13], [16]. We suggest that several strategies that have been extensively researched for ground robots can be extended to flying robots navigating in 3D and that touch sensing will allow flying robots to perform certain navigation tasks or deal with hard- to-detect obstacles.
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Polarization of coalitions in an agent-based model of political discourse

Polarization of coalitions in an agent-based model of political discourse

Figure 3 validates the claims about the structure of the discourse in the final model by visualizing an exemplary simulation run. Different node shapes (circles and squares) reflect the two different ideologies. Governmental actors are represented by green nodes and interest groups by blue vertices. In the first panel, the actor co-occurrence network is in the early stages of the rewiring process from a random graph to a discourse network. There is no typical discourse structure yet. After 1,000 time steps, the rewiring pro- cess has been completed. There are two coalitions corresponding to the two ideologies, with several connections between the two factions. Governmental actors are particularly likely to cluster together and connect the two camps. This is also visible after 5,000 time steps. At time step 5,806, the two coalitions almost lose their last bit of overlap. Only one governmental actor serves as a bridge between the two coalitions. The polarization slightly decreases again soon after. After 7,500 time steps, one can see that discourse does not necessarily have to be one-dimensional. As can be observed in empirical discourse networks [2], coalitions can sometimes decompose into two or more subcoalitions with different aims and beliefs. The rectangles at time step 7,500 make up two or three sub- clusters within the rectangular advocacy coalition. Moreover, the circles are connected to the rectangles via two different brokers. It is also noteworthy that actors from one coali- tion may sometimes join the opponent and then come back - a feature of the discourse that is also occasionally observable in empirical discourse networks [2]. Finally, the sit- uation goes back to a somewhat polarized normal state with two relatively homogenous coalitions again after 10,000 time steps.
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Image Based Methods for Navigation of Intelligent Vehicles

Image Based Methods for Navigation of Intelligent Vehicles

Automated methods for self-position estimation of intelligent vehicles have progressed a lot. Each of the methods suffers from its own drawbacks. Combining many methods to give a hybrid approach to self-position estimation finds many applications. Among all the methods, image matching based methods are very accurate and efficient for self- position estimation. Some of the challenges in image based methods, for example, illumination changes among various images in the database can be handled using robust feature detectors and feature descriptors. This paper has surveyed various aspects of the advancements madeso far in machine vision field for estimating self-position of robotic and intelligent vehicles.
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Vision based Robot Navigation for Disaster Scenarios

Vision based Robot Navigation for Disaster Scenarios

Sockets are API used for interprocess communication based on TCP/IP [11] and RTP protocol for establishing communication. Once connection is established the video is being divided to frames and these frames are then transmitted from server to client in a continuous manner. These frames then keep on getting overwritten consequently so that when seen in a continuous manner it resembles a video at the user end.

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Aircraft navigation based on differentiation–integration observer

Aircraft navigation based on differentiation–integration observer

Abstract: In this paper, a generalized differentiation-integration observer is presented based on sensors selection. The proposed differentiation-integration observer can estimate the multiple in- tegrals and high-order derivatives of a signal, synchronously. The parameters selection rules are presented for the differentiation-integration observer. The theoretical results are confirmed by the frequency-domain analysis. The effectiveness of the proposed observer are verified through the numerical simulations on a quadrotor aircraft: i) through the differentiation-integration observer, the attitude angle and the uncertainties in attitude dynamics are estimated synchronously from the measurements of angular velocity; ii) a control law is designed based on the observers to drive the aircraft to track a reference trajectory.
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3D navigation system based on synthetic texturing

3D navigation system based on synthetic texturing

purpose on smart phones, is M-LOMA 3 [Nur] . This application which is programmed by C++, can be installed on smart phones for running VRML file. The visible part of the model can be rendered on the screen. Moreover lightweight geometry is sued for modeling. In this issue VRML parsing is the first step in implementation process for just visible area on the screen. Texture processing for different LODs comes afterwards which are created and stored separately. In the next step the visibility calculations Based on PVS 4 algorithm is done. Then visibility list encoding can be followed by geometry files packaging and compressing them in binary format.
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Identification of a Spheroid based on the First Order Polarization Tensor

Identification of a Spheroid based on the First Order Polarization Tensor

where k is a constant depending on the material of B. Equation (1) suggests that there exists a conductivity contrast between R 3 (conductivity equal to 1) and B (conductivity equal to k). According to Ammari and Kang [1], if there is an electrical field in R 3 with the presence of B, B are then described by the terminology called as the Generalized Polarization Tensor (GPT). GPT can be determined by solving system of integral equations and the simplest form of GPT denoted by M is called as the first order GPT (or simply the first order PT). Here, M for B at conductivity k, denoted by M (k, B) where 0     k 1 is a real 3 x 3 matrix and it is proven in [1] that M is symmetric. Moreover, [1] has also shown that M is positive definite if
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Navigation Ground Augmentation System Based on a Wireless Sensor

Navigation Ground Augmentation System Based on a Wireless Sensor

niques improve the navigation signal source [4]. Zhang et al. (2017) reported that major spaceflight circles compete seriously and several SBAS systems have been built around the world, such as the United States wide area augmentation system, the Russian system of differential correction and monitoring, and the European geosta- tionary navigation overlap service. Aldoumani et al. (2016) stated that the GBAS mainly uses the difference algorithm to improve the navigation precision of the global positioning system (GPS) satellite. According to the signal integrity algorithm, the integrity information of the GPS signal is obtained at a certain time, and the integrity, availability, and continuity of the GPS signal are improved [6]. Kumar et al. (2017) reported that the continuous operation reference station system is a widely used GBAS and belongs to the products of advanced science and technology, such as navi- gation satellite positioning technology, modern digital communication technology, and rapidly developed computer network technology [7]. Zhuang et al. (2016) sug- gested that ground-based pseudolite augmentation technology is also a GBAS. Pseu- dolite can broadcast the same or similar signals as GNSS navigation signals, provid- ing user positioning, navigation, and timing services [8].
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Development Of Navigation Mobile Robot Based On Digital Compass

Development Of Navigation Mobile Robot Based On Digital Compass

DEVELOPMENT OF NAVIGATION MOBILE ROBOT BASED ON DIGITAL COMPASS MUHAMMAD SYAHMI BIN MOHD HASAN B050710038 UNIVERSITI TEKNIKAL MALAYSIA MELAKA 2011... UIVERSITI TEKIKAL MALAYSIA MELAKA DE[r]

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Development of PLC based navigation system for mobile robot

Development of PLC based navigation system for mobile robot

A programmed machine called mobile robot has a skilled of movement in any controlled environment. It has the capabilities to move around in environments and does not fixed to one physical location as categorized as fixed robot. Most of the mobile robots developed before are based on PID and fuzzy control system to control their navigation. Although PID is known as the best controller for mobile robot, the difficulties of applying the PID as well as writing the program in it bring the attention of researches to look for easier controller such as PLC.
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Vision Based Maze Navigation Using Ni-myRIO

Vision Based Maze Navigation Using Ni-myRIO

In this century, there is a lot of navigation or line following mobile robots has been created. The issue is their mobile robots takes time in its decision so that it can’t move quick. In other word, we called as processing time. Processing time is measured from the information has identified until produce the output. One of the reasons it takes low reaction time is their algorithm or technique excessively perplexing where it needs a period to finish it despite the fact that its more dependable.

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An IoT based Vehicle Accident Detection, Reporting and Navigation

An IoT based Vehicle Accident Detection, Reporting and Navigation

Our proposed solution is a smart IoT system consisting of architecture, design, and implementation. This system provides instant automated vehicle accident detection and reporting. This method is applicable for any vehicle used in transportation and mainly for cars, bikes accidents. The primary users of this solution are the public safety organizations rescue teams (like Police, Red Cross, Emergency Management Agencies, Law Enforcement Agencies, Fire Departments, Rescue Squads, and Emergency Medical Services etc…). The main contributions of this system developing a new smart IoT solution which helps the community in reducing the death rate resulting from vehicle accidents. Ensuring that no person (injured) intervention is required during or after the accident. Transmitting automatically the basic medical information needed by the rescue teams to the PSO headquarter. Collecting geographical data which can be fed to a data mining engine to extract roads conditions, and to generate descriptive statistics reports about vehicle accidents. Implementing a navigation system to find the closest rescue team to the crash.
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Vision Navigation Based on the Fusion of Feature based Methods and Direct Methods

Vision Navigation Based on the Fusion of Feature based Methods and Direct Methods

Feature-based methods. The feature-based methods split the overall problem—estimating camera poses from images - into two sequential steps: First, extract a set of feature observations from the images; second, the camera pose is computed as a function of the extracted features only. While the decoupling simplifies the overall problem and can be accurate, robust and reliable in feature-rich environments, it has a limitation: only the information that conforms to the feature type can be used [8], so the large amount of information in images is discarded [12-15]. Thus feature-based methods rely on the set of feature observations and can’t be reliable in feature-less environments.
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