A Neural Model of Demyelination of the Mouse Spinal Cord

This paper presents a neural network model of demyelination of the mouse motor pathways, coupled to a central pattern generation (CPG) model for quadruped walking. Demyelination is the degradation of the myelin layer covering the axons which can be caused by several neurodegenerative autoimmune diseases such as multiple sclerosis. We use this model - to our knowledge first of its kind - to investigate the locomotion deficits that appear following demyelination of axons in the spinal cord. Our model meets several physiological and behavioral results and predicts that whereas locomotion can still occur at high percentages of demyelination damage, the distribution and location of the lesion are the most critical factors for the locomotor performance

A functional role of the sky’s polarization pattern for orientation in the greater mouse-eared bat

Animals can call on a multitude of sensory information to orient and navigate. One such cue is the pattern of polarized light in the sky, which for example can be used by birds as a geographical reference to calibrate other cues in the compass mechanism. Here we demonstrate that the female greater mouse-eared bat (Myotis myotis) uses polarization cues at sunset to calibrate a magnetic compass, which is subsequently used for orientation during a homing experiment. This renders bats the only mammal known so far to make use of the polarization pattern in the sky. Although there is currently no clear understanding of how this cue is perceived in this taxon, our observation has general implications for the sensory biology of mammalian vision

How Can Dolphins Recognize Fish According to Their Echoes? A Statistical Analysis of Fish Echoes

Echo-based object classification is a fundamental task of animals that use a biosonar system. Dolphins and porpoises should be able to rely on echoes to discriminate a predator from a prey or to select a desired prey from an undesired object. Many studies have shown that dolphins and porpoises can discriminate between objects according to their echoes. All of these studies however, used unnatural objects that can be easily characterized in human terminologies (e.g., metallic spheres, disks, cylinders). In this work, we collected real fish echoes from many angles of acquisition using a sonar system that mimics the emission properties of dolphins and porpoises. We then tested two alternative statistical approaches in classifying these echoes. Our results suggest that fish species can be classified according to echoes returning from porpoise- and dolphin-like signals. These results suggest how dolphins and porpoises can classify fish based on their echoes and provide some insight as to which features might enable the classification

The Voice of Bats: How Greater Mouse-eared Bats Recognize Individuals Based on Their Echolocation Calls

Echolocating bats use the echoes from their echolocation calls to perceive their surroundings. The ability to use these continuously emitted calls, whose main function is not communication, for recognition of individual conspecifics might facilitate many of the social behaviours observed in bats. Several studies of individual-specific information in echolocation calls found some evidence for its existence but did not quantify or explain it. We used a direct paradigm to show that greater mouse-eared bats (Myotis myotis) can easily discriminate between individuals based on their echolocation calls and that they can generalize their knowledge to discriminate new individuals that they were not trained to recognize. We conclude that, despite their high variability, broadband bat-echolocation calls contain individual-specific information that is sufficient for recognition. An analysis of the call spectra showed that formant-related features are suitable cues for individual recognition. As a model for the bat's decision strategy, we trained nonlinear statistical classifiers to reproduce the behaviour of the bats, namely to repeat correct and incorrect decisions of the bats. The comparison of the bats with the model strongly implies that the bats are using a prototype classification approach: they learn the average call characteristics of individuals and use them as a reference for classification

Urban bat pups take after their mothers and are bolder and faster learners than rural pups.

Background: Urbanization is rapidly changing our planet and animals that live in urban environments must quickly adjust their behavior. One of the most prevalent behavioral characteristics of urban dwelling animals is an increased level of risk-taking. Here, we aimed to reveal how urban fruitbats become risk-takers, and how they differ behaviorally from rural bats, studying both genetic and non-genetic factors that might play a role in the process. We assessed the personality of newborn pups from both rural and urban colonies before they acquired experience outdoors, examining risk-taking, exploration, and learning rates. Results: Urban pups exhibited significantly higher risk-taking levels, they were faster learners, but less exploratory than their rural counterparts. A cross-fostering experiment revealed that pups were more similar to their adoptive mothers, thus suggesting a non-genetic mechanism and pointing towards a maternal effect. We moreover found that lactating urban mothers have higher cortisol levels in their milk, which could potentially explain the transmission of some personality traits from mother to pup. Conclusions: Young bats seem to acquire environment suitable traits via post-birth non-genetic maternal effects. We offer a potential mechanism for how urban pups can acquire urban-suitable behavioral traits through hormonal transfer from their mothers

N-Glykosylierung von T Helfer Zell-Populationen bei Patienten mit Multipler Sklerose

Die Oberflächenglykosylierung beeinflusst wesentlich die Interaktion von Zellen des Immunsystems und deren Regulation. In der vorliegenden Arbeit wurde ihre Bedeutung in der Aktivierung und Differenzierung der T Zellen, welche eine zentrale Rolle in der Pathogenese der Multiplen Sklerose spielen näher untersucht. Dazu wurden Immunzellen aus dem Blut gesunder Probanden und von Patienten mit Multiple Sklerose durchflusszytometrisch mittels Fluoreszenzantikörpern spezifiziert. Anschließend wurde die Intensität verschiedener Glykosylierungen ihrer Oberflächenproteine mit Hilfe von Lektinen analysiert. Eine weitere Fragstellung war, inwieweit sich die Oberflächenglykosylierung durch in-vitro Stimulation verändert. Weiterhin wurde die Auswirkung auf die β 1,2 N-Oberflächenglykosylierung auf regulatorischen T Zellen durch spezifische Inhibition der α 1,2 Mannosidase untersucht. Bei der Untersuchung der Effektor T Zellen und regulatorischen T Zellen zeigte sich, dass sich die α2,3 und die α2,6 Sialylierung sowie auf Effektor T Zellen und regulatorischen T Zellen sowohl bei gesunden Probanden als auch bei Patienten unter Natalizumabtherapie nicht wesentlich unterscheidet. Anders verhält es sich bei der α1,2 Glykosylierung, die bei Patienten mit Multipler Sklerose unter Natalizumabtherapie deutlich erhöht ist. Im Gegensatz hierzu stellte sich heraus, dass die in dieser Arbeit erstmals auf humanen T Zellen untersuchte N-Oberflächenglykosylierung sich in ihrer Ausprägung signifikant auf den einzelnen T Zell Subpopulationen unterscheidet. So konnte gezeigt werden, dass aktivierte T Zellen und regulatorische T Zellen stärker n-glykosyliert sind, als nicht aktivierte T Helfer Zellen. T Helfer Typ 17 Zellen waren stärker n-glykosyliert als T Helfer Typ 2 Zellen. Die Ausprägung unterscheidet sich auf den vergleichbaren Subpopulationen zudem zwischen gesunden Probanden und MS Patienten unter Natalizumabtherapie. So ist die ß 1,6 N Glykosylierung auf T Helfer Typ 1 und T Helfer Typ 17 Zellen bei MS Patienten erniedrigt und auf T Effektor Zellen erhöht. In unseren in-vitro Versuchen konnten wir weiterhin nachweisen, dass die N-Oberflächenglykosylierung durch spezifische Stimulation zunimmt und eine Hemmung der intrazellulären n-glykosylierenden Prozesse die suppressive Funktion regulatorischer T Zellen steigert. Damit scheint eine effiziente Oberflächenglykosylierung kritisch für die immunregulatorische Funktion von regulatorischen T Zellen zu sein. In unseren Untersuchungen ergeben sich Hinweise darauf, dass die immunologische Funktion von T Zellen mit der Intensität ihrer Oberflächenglykosylierung korreliert und dass die Oberflächenglykosylierung von Immunzellen bei Patienten mit Multipler Sklerose verändert ist und sich unter Therapie mit dem Integrin-Inhibitor Natalizumab verändert

Ethereum: state of knowledge and research perspectives

Ethereum is a decentralized application platform that allows users to write, deploy, and interact with smart contracts -- programs that encode financial agreements. A peer-to-peer network of mutually distrusting nodes maintains a common view of the state of all accounts and executes smart contracts' code upon request. The global state is stored in a blockchain secured by a proof-of-work consensus mechanism similar to that in Bitcoin. The core value proposition of Ethereum is a Turing-complete programming language that enables implementing complex logic in smart contracts. Decentralized applications without a trusted third party are appealing in many areas, such as financial services, crowdfunding, and gambling. Smart contracts as a research topic contains many unsolved challenges and spans over areas ranging from cryptography, consensus algorithms, and programming languages to governance, ethical, and legal issues. This paper is the first to summarize the state of knowledge in this field. We provide a technical overview of Ethereum and outline open challenges along with proposed solutions. We also mention alternative blockchains with Turing complete programming capabilities

モンゴル ニオケル インシン ホトクト ノ シャビ ナル ノ ボクチ ニツイテ

Bats vocalizing in the daytime sleeping cluster. Wide-view footage from a distant corner of the cage