Inference of Sequential Patterns for Neural Message Passing in Temporal Graphs

The modelling of temporal patterns in dynamic graphs is an important current research issue in the development of time-aware GNNs. Whether or not a specific sequence of events in a temporal graph constitutes a temporal pattern not only depends on the frequency of its occurrence. We consider whether it deviates from what is expected in a temporal graph where timestamps are randomly shuffled. While accounting for such a random baseline is important to model temporal patterns, it has mostly been ignored by current temporal graph neural networks. To address this issue we propose HYPA-DBGNN, a novel two-step approach that combines (i) the inference of anomalous sequential patterns in time series data on graphs based on a statistically principled null model, with (ii) a neural message passing approach that utilizes a higher-order De Bruijn graph whose edges capture overrepresented sequential patterns. Our method leverages hypergeometric graph ensembles to identify anomalous edges within both first- and higher-order De Bruijn graphs, which encode the temporal ordering of events. The model introduces an inductive bias that enhances model interpretability. We evaluate our approach for static node classification using benchmark datasets and a synthetic dataset that showcases its ability to incorporate the observed inductive bias regarding over- and under-represented temporal edges. We demonstrate the framework's effectiveness in detecting similar patterns within empirical datasets, resulting in superior performance compared to baseline methods in node classification tasks. To the best of our knowledge, our work is the first to introduce statistically informed GNNs that leverage temporal and causal sequence anomalies. HYPA-DBGNN represents a path for bridging the gap between statistical graph inference and neural graph representation learning, with potential applications to static GNNs

Experimental Investigation of Nonlinear Cyclic Flexural Behavior of Hollow and Concrete-Filled Aluminium Beams

This study presents an experimental program to characterize, for the first time, the nonlinear cyclic flexural behavior of hollow and concrete-filled aluminium tubular beams at large rotation levels up to 0.08 rad. Particularly, four different tubular cross sections, fabricated from two grades of structural aluminium alloys–6082-T6 and 6063-T6–with various cross-sectional slenderness were tested with and without concrete infill to establish their hysteretic flexural behavior. All tested specimens showed hysteretic loops without significant gradual strength and stiffness degradation under cyclic loading. The influence of aluminium alloy type, cross-sectional slenderness, and presence of concrete infill on the plastic hinge deformation, ultimate strength, failure mode, secant stiffness degradation, and energy dissipation capacity is thoroughly investigated. Analysis of the in-plane strain measurements from digital image correlation (DIC) suggest that under large cyclic loads the examined members can develop an average plastic hinge length equal to 1.5 times the largest cross-sectional dimension measured from the fixed end of the members. Overall, the experimental results demonstrate that hollow and concrete-filled aluminium beam members can sustain large deformations without any structural damage under large rotation levels

Experimental investigation of nonlinear cyclic flexural behaviour of hollow and concrete-filled aluminium beams

This study presents an experimental programme to characterise, for the first time, the nonlinear cyclic flexural behaviour of hollow and concrete-filled aluminium tubular beams at large rotation levels up to 0.08 rad. Particularly, four different tubular cross-sections, fabricated from two grades of structural aluminium alloys –6082-T6 and 6063-T6– with various cross-sectional slenderness were tested with and without concrete infill to establish their hysteretic flexural behaviour. All tested specimens showed hysteretic loops without significant gradual strength and stiffness degradation under cyclic loading. The influence of aluminium alloy type, cross-sectional slenderness and presence of concrete infill on the plastic hinge deformation, ultimate strength, failure mode, secant stiffness degradation and energy dissipation capacity is thoroughly investigated. Analysis of the in-plane strain measurements from Digital Image Correlation suggest that under large cyclic loads the examined members can develop an average plastic hinge length equal to 1.5 times the largest cross-sectional dimension measured from the fixed end of the members. Overall, the experimental results demonstrate that hollow and concrete-filled aluminium beam members can sustain large deformations without any structural damage under large rotation levels

Daedalus 2: Autorotation Entry, Descent and Landing Experiment on REXUS29

In recent years, interplanetary exploration has gained significant momentum, leading to a focus on the development of launch vehicles. However, the critical technology of edl mechanisms has not received the same level of attention and remains less mature and capable. To address this gap, we took advantage of the REXUS program to develop a pioneering edl mechanism. We propose an alternative to conventional, parachute based landing vehicles by utilizing autorotation. Our approach enables future additions such as steerability, controllability, and the possibility of a soft landing. To validate the technique and our specific implementation, we conducted a sounding rocket experiment on REXUS29. The systems design is outlined with relevant design decisions and constraints, covering software, mechanics, electronics and control systems. Furthermore, an emphasis will also be the organization and setup of the team entirely made up and executed by students. The flight results on REXUS itself are presented, including the most important outcomes and possible reasons for mission failure. We have not archived an autorotation based landing, but provide a reliable way of building and operating such vehicles. Ultimately, future works and possibilities for improvements are outlined. The research presented in this paper highlights the need for continued exploration and development of edl mechanisms for future interplanetary missions. By discussing our results, we hope to inspire further research in this area and contribute to the advancement of space exploration technology.Comment: 12 pages, 9 figure

Evolution of the major histocompatibility complex class I genes in cattle

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN016302 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Establishment of an in vitro photoassay using THP-1 cells and IL-8 to discriminate photoirritants from photoallergens

At present, there are no in vivo or in vitro methods developed which has been adopted by regulatory authorities to assess photosensitization induced by chemicals. Recently, we have proposed the use of THP-1 cells and IL-8 release to identify the potential of chemicals to induce skin sensitization. Based on the assumption that sensitization and photosensitization share common mechanisms, the aim of this work was to explore the THP-1 model as an in vitro model to identify photoallergenic chemicals. THP-1 cells were exposed to 7 photoallergens and 3 photoirritants and irradiated with UVA light or kept in dark. Non phototoxic allergens or irritants were also included as negative compounds. Following 24 h of incubation, cytotoxicity and IL-8 release were measured. At subtoxic concentrations, photoallergens produced a dose-related increase in IL-8 release after irradiation. Some photoirritants also produced a slight increase in IL-8 release. However, when the overall stimulation indexes of IL-8 were calculated for each chemical, 6 out of 7 photoallergens tested reached a stimulation index above 2, while the entire set of negative compounds had stimulation indexes below 2. Our data suggest that this assay may become a useful cell-based in vitro test for evaluating the photosensitizing potential of chemicals