CONNECTIONS of the LIOUVILLE MODEL and XXZ SPIN CHAIN

The quantum theory of the Liouville model with imaginary field is considered using the quantum inverse scattering method. An integrable structure with nontrivial spectral parameter dependence is developed for lattice Liouville theory by scaling the $L$-matrix of lattice sine-Gordon theory. This $L$-matrix yields Bethe Ansatz equations for Liouville theory, by the methods of the algebraic Bethe Ansatz. Using the string picture of exited Bethe states, the lattice Liouville Bethe equations are mapped to the corresponding equations for the spin 1/2 XXZ chain. The well developed theory of finite size corrections in spin chains is used to deduce the conformal properties of the lattice Liouville Bethe states. The unitary series of conformal field theories emerge for Liouville couplings of the form \gam = \pi\frac{\nu}{\nu+1}, corresponding to root of unity XXZ anisotropies. The Bethe states give the full spectrum of the corresponding unitary conformal field theory, with the primary states in the \Kac table parameterized by a string length $K$, and the remnant of the chain length mod $(\nu+1)$.Comment: 25 pages, Late

A virtual spatial navigation task for multisensory discrimination

This study’s results help to explain the effects of multisensory visuotactile stimulation on animal behavior. The presented powerful task can capture complex behavioral aspects, while simultaneously accessing brain activity with imaging methods. Mice were head-fixed and placed in a very simple virtual visuotactile corridor in which they were free to run or moved automatically. They encountered different numbers of either visual, tactile or combined visuotactile events on the two walls of the tunnel and had to discriminate between those two and find the side with more events/higher frequency. Visual events were white bars of 1.2 cm width on a black background and tactile events were 40 ms short air puffs to the whiskers of the mouse. After reaching the end of the corridor, the mouse had to give an answer on either the left or the right side, according to the correct side (higher frequency), to obtain a reward. Mice were able to successfully discriminate between target-distractor differences of up to two events in the multisensory condition. Pure visual and tactile task performance was inferior to the visuotactile task performance, which means that there was an increase in performance when congruent visual and tactile information was present at the same time. The psychometric curves are shifted for the unisensory conditions, with higher differences between target and distractor stimulus as discrimination thresholds. The multisensory effect was biggest for medium task difficulty, represented by medium distractors. This means, that mice in a very hard or very easy task did not profit as much from the presence of multiple modalities. Running activity on the wheel had only slight effects on performance. While we found a clear increase in performance with running activity in a pure visual sinusoidal grating discrimination task, this effect is ambiguous in the multisensory experiment. Although there seems to be a trend, the difference in performance is not significant and further testing has to be done to find a possible effect. When we exposed the mice with a modality conflict task, where they were free to choose between equal visual or tactile targets, we found that some animals clearly preferred either visual or tactile cues. In line with these preferences, an analysis of the performance during sessions revealed that animals followed different strategies of relying more on one modality than on the other. This often also changes during a session, whilesome animals were more likely to switch their strategy than others. With the experimental setup shown here, it is possible to get a meaningful read out of animal behavior, which can be easily combined with imaging of neuronal activity, for example with calcium imaging under a 2-photon microscope or widefield macroscope. Those techniques have been successfully tested in the primary visual cortex and higher visual rostrolateral area RL

A simulative approach to efficient microstructure optimisation: identifying microstructural influences on the damage properties of dualphase steels

The optimisation of materials and processes has sped up the development of technologies, production and infrastructure tremendously. Steel is historically one of the most important materials, for the manufacturing of many components, reaching from infrastructure (e.g. railways, bridges), to intricate machinery. Thus, a lot of effort already went into optimizing steel as a material. From these improvements new material classes inside the overarching steel material were created; e.g. structural steels, advanced high strength steels (AHSS), medium manganese steels (MMnS), tool steels, to only name a few. In recent years the optimisation has expanded from simply adapting the mechanical properties for specific application towards including sustainability and ecological factors. For this reason, steels have become more specific towards their application field, as lightweight construction plays a very important role in the reduction of CO2 emission and therefore in the ecological impact components have. The optimisation process accelerated with the implementation of digital tools, such as computer based finite element simulations. They started out as simple elastic/plastic idealised simulations but became more sophisticated as computational power began to increase. This led to material models that describe the flow behaviour as well as the damage induced softening accurately. In recent years the microstructure of materials became a focus of optimisation, as it is extremely influential on mechanical and damage properties of a material. Again, the digitalisation of all processes showed to yield promising results and statistically representative volume elements (sRVE) became a key research topic that aimed at representing the microstructure digitally [1]. Even the 2021 elected German government realised the potential of the utilisation of digital twins or shadows, like the sRVEs are, of the material and has stipulated the promotion of these processes in the coalition agreement [2]. However, for these highly specialised steels, mentioned above, the microstructure has become increasingly complex, utilizing multiple different crystallographic phases, as well as specific heat treatments to reach the desired microstructure of the material and with it the desired usability and mechanical properties. So, to tailor the microstructure further for a specific process, it is imperative to first recreate the microstructure as a digital twin or shadow through the means of sRVE. These sRVEs are not accurate representations of images of the real microstructure, but instead apply statistical descriptions of the material to represent it virtually. Substantial progress was made in the precise recreation of the microstructures from the simple two-dimensional sRVE [3] towards more sophisticated approaches like newer versions of DREAM.3D (e.g. version 6.5.163) [4]. However even with the newer virtual microstructure construction algorithms lack the possibility to incorporate all features, as well as truly realistic grain shapes. Additionally, the input data for these statistically representative models has to be gathered from microstructure images. To then generate the input data necessary for a realistic sRVE, simple distribution functions are usually applied. However, this omits the fact that there are multiple interactions between the microstructure 2 parameters at work. In this work, these missing key components were developed to develop a method for accurate microstructure representation. The focus for this step was more on the input generation, while the microstructure representation was the key focus of a co-author. To allow for an optimization of the microstructure a coherent method must be developed. This is the aim of this work: To provide a method and pathway for efficient microstructure optimisation. Thus, the research hypothesis is as follows: For efficient microstructure optimisation, digital tools have to be applied and a thorough understanding of the microstructure and its effects has to be obtained. To develop and test the methods for microstructure optimisation, a use case was necessary. As the damage properties are of current interest to the field of material science the damage properties of a DP800 steel were examined. DP steel was chosen as this steel class has a complex enough microstructure to provide enough adjustable parameters, while being rather simple in regards of its mechanical properties and the way damage forms. This thesis then aims at filling in the gap of knowledge described before, by developing a method that is capable of quantifying the influence of individual parameters of a microstructure on the damage behaviour. To individually determine the influence of each separate microstructural feature it is mandatory to use a simulative approach. In this way, a method can be developed and tested that is suitable for efficient and effective microstructure design and optimisation. The clear-cut target is to describe the microstructure of the DP800 as accurately as possible and find influencing factors for the damage properties. In this way, the optimisation of steel microstructures for specific loading paths and use cases is supposed to be significantly enhanced and the advantages of the separate microstructures are then easily quantifiable

MazeMaster: an open-source Python-based software package for controlling virtual reality experiments

AbstractIn the last 15 years, virtual realities have revolutionized behavior experiments in particular for rodents. In combination with treadmills, running wheels, or air-floating balls, the implementation of a virtual reality (VR) provides not only the opportunity to simultaneously explore behavior and neuronal activity in head-fixed animals under nearly natural conditions, but also allows full control over the visual sensory input presented to the animal. Furthermore, VRs can be combined with other sensory modalities such as auditory, tactile or olfactory stimuli. Despite the power of using VRs in animal experiments, available software packages are very limited, expensive and lack the required flexibility to design appropriate behavior and neurophysiology experiments. For this reason, we have developed the versatile, adaptable and easy to use VR environment MazeMaster, an open-source, Python-based software package for controlling virtual reality setups and behavior experiments. The software package includes a graphical user interface (GUI) and can be integrated into standard electrophysiology and imaging setups even by non-programmers. Ready-made behavioral experiments such as multisensory discrimination in T-mazes are already implemented including full control for reward supply and bias correction. For more individual setup designs, the modularity of MazeMaster allows more programming-affine users to extend the software with potentially missing features. With MazeMaster, we offer a free and easy-to-use VR controller that will facilitate the implementation of VR setups in scientific laboratories. In addition, MazeMaster allows the design and control of common head-fixed rodent behavior paradigms with extensive acquisition of meta-data required for reproducible VR experiments. The MazeMaster VR package, therefore, offers a collaboration tool for reproducible research within and across neuroscience laboratories according to the FAIR principles.</jats:p

DMD-based excitation of transverse laser modes by spatial pump beam shaping

The excitation of transverse laser modes, can be achieved by a cavity-internal amplitude or phase modulation of the laser light. For this purpose typically additional cavity-internal components are applied, which can result in increased losses and a limited resonator internal power [1]. Therefore, gain shaping based methods [2], where the selective mode excitation is achieved via a cavity-external modulation of the pump beam are of great interest, as they require no modification of the laser cavity itself. However, the so far presented gain shaping methods are strongly limited with respect to the number of modes that can be excited, as they apply pump beams of a fixed spatial shape. Here, we present a spatial gain shaping method that applies a digital micromirror device (DMD) as a shaping tool for the pump beam, enabling a high degree of freedom for the gain distributions that can be generated. We demonstrate the advantage of our approach by exciting nearly 1000 different single Hermite-Gaussian (HG) modes in an end-pumped Nd:YVO4 laser, increasing the number of excitable HG modes by at least a factor of five in comparison to other excitation methods [2, 3]

Selective Hermite–Gaussian mode excitation in a laser cavity by external pump beam shaping

An improved gain-shaping method for selective mode excitation is presented and its application for the excitation of higher order Hermite–Gaussian modes is demonstrated in an end-pumped Nd:YVO4 laser. Using a digital micromirror device, the intensity distribution of the pump beam within the laser crystal could be shaped with a high degree of freedom. Thus, a broad variety of different gain distributions were achieved, enabling a highly selective mode excitation method based on gain shaping. In the presented experiment, the excitation of nearly 1000 different Hermite–Gaussian modes was demonstrated, increasing the number of excitable Hermite–Gaussian modes by at least a factor of five, compared to other excitation methods. The excited modes include Hermite–Gaussian modes of high orders as, for example, the HG25 , 27 mode. Furthermore, the electronic control of the gain profile, applied via the digital micromirror device, enabled automated measurements of the selective mode excitation. Here, a systematic study is presented to optimize the generated pump patterns with respect to the number of modes that could be excited

Pupillary Dilations of Mice Performing a Vibrotactile Discrimination Task Reflect Task Engagement and Response Confidence

International audiencePupillometry, the measure of pupil size and reactivity, has been widely used to assess cognitive processes. Changes in pupil size have been shown to correlate with various behavioral states, both externally and internally induced such as locomotion, arousal, cortical state, and decision-making processes. Besides, these pupillary responses have also been linked to the activity of neuromodulatory systems that modulate attention and perception such as the noradrenergic and cholinergic systems. Due to the extent of processes the pupil reflects, we aimed at further resolving pupillary responses in the context of behavioral state and task performance while recording pupillary transients of mice performing a vibrotactile two-alternative forced-choice task (2-AFC). We show that before the presentation of task-relevant information, pre-stimulus, pupil size differentiates between states of disengagement from task performance vs. engagement. Also, when subjects have to attend to task stimuli to attain a reward, post-stimulus, pupillary dilations exhibit a difference between correct and error responses with this difference reflecting an internal decision variable. We hypothesize that this internal decision variable relates to response confidence, the internal perception of the confidence the subject has in its choice. As opposed to this, we show that in a condition of passive performance, when the stimulus has no more task relevance due to reward being provided automatically, pupillary dilations reflect the occurrence of stimulation and reward provision but not decisional variables as under active performance. Our results provide evidence that in addition to reflecting attentiveness under task performance rather than arousal per se, pupil dilations also reflect the confidence of the subject in his ensuing response.This confidence coding is overlaid within a more pronounced pupil dilation that reflects post-decision components that are related to the response itself but not to the decision. We also provide evidence as to how different behavioral states, imposed by task demands, modulate what the pupil is reflecting, presumably showing what the underlying cognitive network is coding for

In Vitro Investigation of the Interaction of Avian Metapneumovirus and Newcastle Disease Virus with Turkey Respiratory and Reproductive Tissue

In poultry, several respiratory viral infections lead to a drop in egg production associated with high economic losses. While the virus–host interactions at the respiratory epithelium are well studied, less is known about these interactions in the oviduct. To investigate possible differences between virus infections at these epithelial structures, we compared the interactions of two important poultry viruses on turkey organ cultures. Two members of the order Mononegavirales, the Avian Metapneumovirus (AMPV) and the Newcastle disease virus (NDV), were selected to conduct the in vitro experiments since these viruses can infect both the trachea and oviduct. In addition, we used different strains of these viruses, a subtype A and a subtype B strain for AMPV and the NDV strains Komarow and Herts’33, to detect possible differences not only between the tissues but also between different viral strains. Turkey tracheal and oviduct organ cultures (TOC and OOC) were prepared to investigate viral replication, antigen localisation, lesion development, and the expression pattern of interferon-λ and importin-α isoforms. All viruses replicated more efficiently in the oviduct than in the tracheal epithelium (p < 0.05). In addition, we observed higher expression levels of both, IFN-λ and importin-α in OOCs compared to TOCs. Our results indicated strain-dependent differences, with the AMPV-B- and Herts’33 strains being more virulent in organ cultures than the AMPV-A- and Komarow strains, based on the higher viral genome loads, more severe histological lesions, and higher upregulation of IFN-λ. Overall, our findings reveal tissue- and virus strain-dependent differences, which may have consequences for disease development in the host tissue and, subsequently, possible treatment strategies