UnRectDepthNet: Self-Supervised Monocular Depth Estimation using a Generic Framework for Handling Common Camera Distortion Models

In classical computer vision, rectification is an integral part of multi-view depth estimation. It typically includes epipolar rectification and lens distortion correction. This process simplifies the depth estimation significantly, and thus it has been adopted in CNN approaches. However, rectification has several side effects, including a reduced field of view (FOV), resampling distortion, and sensitivity to calibration errors. The effects are particularly pronounced in case of significant distortion (e.g., wide-angle fisheye cameras). In this paper, we propose a generic scale-aware self-supervised pipeline for estimating depth, euclidean distance, and visual odometry from unrectified monocular videos. We demonstrate a similar level of precision on the unrectified KITTI dataset with barrel distortion comparable to the rectified KITTI dataset. The intuition being that the rectification step can be implicitly absorbed within the CNN model, which learns the distortion model without increasing complexity. Our approach does not suffer from a reduced field of view and avoids computational costs for rectification at inference time. To further illustrate the general applicability of the proposed framework, we apply it to wide-angle fisheye cameras with 190$^\circ$ horizontal field of view. The training framework UnRectDepthNet takes in the camera distortion model as an argument and adapts projection and unprojection functions accordingly. The proposed algorithm is evaluated further on the KITTI rectified dataset, and we achieve state-of-the-art results that improve upon our previous work FisheyeDistanceNet. Qualitative results on a distorted test scene video sequence indicate excellent performance https://youtu.be/K6pbx3bU4Ss.Comment: Minor fixes added after IROS 2020 Camera ready submission. IROS 2020 presentation video - https://www.youtube.com/watch?v=3Br2KSWZRr

Fused Deposition Modeling of Microfluidic Chips in Transparent Polystyrene

Polystyrene (PS) is one of the most commonly used thermoplastic materials worldwide and plays a ubiquitous role in today’s biomedical and life science industry and research. The main advantage of PS lies in its facile processability, its excellent optical and mechanical properties, as well as its biocompatibility. However, PS is only rarely used in microfluidic prototyping, since the structuring of PS is mainly performed using industrial-scale replication processes. So far, microfluidic chips in PS have not been accessible to rapid prototyping via 3D printing. In this work, we present, for the first time, 3D printing of transparent PS using fused deposition modeling (FDM). We present FDM printing of transparent PS microfluidic channels with dimensions as small as 300 µm and a high transparency in the region of interest. Furthermore, we demonstrate the fabrication of functional chips such as Tesla-mixer and mixer cascades. Cell culture experiments showed a high cell viability during seven days of culturing, as well as enabling cell adhesion and proliferation. With the aid of this new PS prototyping method, the development of future biomedical microfluidic chips will be significantly accelerated, as it enables using PS from the early academic prototyping all the way to industrial-scale mass replication

The impact of agriculture on tropical mountain soils in the western Peruvian Andes: a pedo-geoarchaeological study of terrace agricultural systems in the Laramate region (14.5° S)

This integrated pedo-geoarchaeological study focuses on three abandoned pre-Hispanic terrace agricultural systems near Laramate in the southern Andes of Peru (14.5° S), aiming to unravel the pedological and land-use history of the region, which served as a significant agricultural hub during pre-Hispanic times. The key objectives of the investigation involved contextualizing the former agricultural management system within its geomorphological and palaeoecological framework and assessing the impact of agricultural practices on soil development and quality by comparing non-irrigated agricultural terrace soils with their undisturbed palaeo-pedological counterparts. The Laramate terrace complex, with its diverse terrace systems and varied geomorphological and geological settings, provided an ideal setting for the investigation. This comprehensive examination integrated a range of methodologies, including field surveys, digital mapping, and geomorphological analysis based on GIS and remote sensing applications, soil analysis (e.g. grain size, bulk chemistry, nutrient budget), plant microfossils (phytoliths and starch), and radiocarbon dating. In the Laramate region, the geomorphological setting of terrace agricultural systems promotes their optimal functioning. The terraces are often located in sun-sheltered areas with western exposure on middle and lower slopes or valley bottoms, which mitigate intense solar radiation, reduce evapotranspiration, increase soil moisture, and minimize erosion. The study identifies three soil groups in the Laramate region: Phaeozems, Andosols, and Anthrosols. Unique characteristics of Phaeozems challenge typical descriptions, influenced by factors such as climatic seasonality, vegetation, fauna, lithology, and aeolian inputs. The terrace soils in the Laramate region are classified as Terric Anthrosols, showing no significant degradation even after long-term use. Their balanced acidity and nutrient levels support Andean crop cultivation. Traditional non-mechanized tools, such as the chaquitaclla and rucana, likely minimized soil disruption. The terrace tillage horizons have high organic matter, indicating intentional organic manuring. Phytolith concentrations suggest intensive agricultural activity, particularly maize cultivation, with varying patterns suggesting changes in cultivation, fertilization, or mulching practices over time. Starch grain identification aligns with phytolith analyses, reinforcing maize's significance in the region. Although the use of animal-origin fertilizers requires further investigation, there is no evidence of nutrient maintenance through seasonal burning. Irrigation was minimal, and the abandonment of the pre-Hispanic cultivation system was unlikely due to soil exhaustion or terrace instability. Overall, the pre-Hispanic history of terrace agriculture in the Laramate region extends over four development phases, reflecting dynamic interactions between environmental, cultural, and agricultural factors. The initial phase, from the Formative Paracas period to the Early Nasca period (800 BCE–200 CE), witnessed the establishment of agricultural terraces with simple terrace architecture, while the Middle Horizon (600–1000 CE) saw systematic areal expansion influenced by the Wari culture. Adaptations to drier conditions included terrace agriculture on volcanic soils. The Late Intermediate period (1000–1450 CE) witnessed hydrological variability and further terrace expansion to lower altitudes and less agriculturally suitable locations. The final phase, marked by the onset of the Hispanic colonial period in 1535 CE, saw the gradual abandonment of terrace agricultural systems due to demographic shifts and reorganization of production systems. Despite this, the historical trajectory underscores the adaptability and resilience of pre-Hispanic communities in the Laramate region, showcasing innovative terrace agriculture as a means of coping with changing environmental conditions across diverse landscape units

Subacute degeneration of fibers after vertical parasagittal hemispherotomy

Purpose After vertical parasagittal hemispherotomy a restricted diffusion is often seen ipsilaterally and even distant from the adjacent resection margin. This retrospective cohort study analyses the anatomic site and the time course of the diffusion restriction after vertical parasagittal hemispherotomy. Methods Fifty-nine patients were included into this study, all of them having had one pre-operative and at least one post-operative MRI, including diffusion imaging at b‑values of 0 and 1000 s/mm2 with a calculated ADC. Results Diffusion restriction occurred exclusively on the operated site in all patients. In the basal ganglia, diffusion restriction was present in 37 of 38 patients at the first postoperative day with a duration of 38 days. In the midbrain, the posterior limb of the internal capsule and the thalamus, a restricted diffusion became postoperatively prominent at day 9 in all three localizations, with a duration of 36, 34 and 36 days, respectively. The incidence of thalamic lesions was lower if a preoperative damage had occurred. Conclusion The restricted diffusion in the basal ganglia resembles direct effects of the operation at its edges, whereas the later appearing diffusion restriction in the midbrain and the posterior limb of the internal capsule rather belong to a degeneration of the descending fibers being transected by the hemispherotomy in the sense of a Wallerian degeneration. The presence of preoperative hemispheric lesions influences the development of diffusion restriction at subacute fiber degeneration

Intrastriatal injection of interleukin-1 beta triggers the formation of neuromyelitis optica-like lesions in NMO-IgG seropositive rats

BACKGROUND: Neuromyelitis optica (NMO) is a severe, disabling disease of the central nervous system (CNS) characterized by the formation of astrocyte-destructive, neutrophil-dominated inflammatory lesions in the spinal cord and optic nerves. These lesions are initiated by the binding of pathogenic aquaporin 4 (AQP4)-specific autoantibodies to astrocytes and subsequent complement-mediated lysis of these cells. Typically, these lesions form in a setting of CNS inflammation, where the blood–brain barrier is open for the entry of antibodies and complement. However, it remained unclear to which extent pro-inflammatory cytokines and chemokines contribute to the formation of NMO lesions. To specifically address this question, we injected the cytokines interleukin-1 beta, tumor necrosis factor alpha, interleukin-6, interferon gamma and the chemokine CXCL2 into the striatum of NMO-IgG seropositive rats and analyzed the tissue 24 hours later by immunohistochemistry. RESULTS: All injected cytokines and chemokines led to profound leakage of immunoglobulins into the injected hemisphere, but only interleukin-1 beta induced the formation of perivascular, neutrophil-infiltrated lesions with AQP4 loss and complement-mediated astrocyte destruction distant from the needle tract. Treatment of rat brain endothelial cells with interleukin-1 beta, but not with any other cytokine or chemokine applied at the same concentration and over the same period of time, caused profound upregulation of granulocyte-recruiting and supporting molecules. Injection of interleukin-1 beta caused higher numbers of blood vessels with perivascular, cellular C1q reactivity than any other cytokine tested. Finally, the screening of a large sample of CNS lesions from NMO and multiple sclerosis patients revealed large numbers of interleukin-1 beta-reactive macrophages/activated microglial cells in active NMO lesions but not in MS lesions with comparable lesion activity and location. CONCLUSIONS: Our data strongly suggest that interleukin-1 beta released in NMO lesions and interleukin-1 beta-induced production/accumulation of complement factors (like C1q) facilitate neutrophil entry and BBB breakdown in the vicinity of NMO lesions, and might thus be an important secondary factor for lesion formation, possibly by paving the ground for rapid lesion growth and amplified immune cell recruitment to this site

Replicative manufacturing of metal moulds for low surface roughness polymer replication

Tool based manufacturing processes like injection moulding allow fast and high-quality mass-market production, but for optical polymer components the production of the necessary tools is time-consuming and expensive. In this paper a process to fabricate metal-inserts for tool based manufacturing with smooth surfaces via a casting and replication process from fused silica templates is presented. Bronze, brass and cobalt-chromium could be successfully replicated from shaped fused silica replications achieving a surface roughnesses of Rq 8 nm and microstructures in the range of 5 µm. Injection moulding was successfully performed, using a commercially available injection moulding system, with thousands of replicas generated from the same tool. In addition, three-dimensional bodies in metal could be realised with 3D-Printing of fused silica casting moulds. This work thus represents an approach to high-quality moulding tools via a scalable facile and cost-effective route surpassing the currently employed cost-, labour- and equipment-intensive machining techniques

Injection Molding of Magnesium Aluminate Spinel Nanocomposites for High‐Throughput Manufacturing of Transparent Ceramics

Transparent ceramics like magnesium aluminate spinel (MAS) are considered the next step in material evolution showing unmatched mechanical, chemical and physical resistance combined with high optical transparency. Unfortunately, transparent ceramics are notoriously difficult to shape, especially on the microscale. Therefore, a thermoplastic MAS nanocomposite is developed that can be shaped by polymer injection molding at high speed and precision. The nanocomposite is converted to dense MAS by debinding, pre-sintering, and hot isostatic pressing yielding transparent ceramics with high optical transmission up to 84 % and high mechanical strength. A transparent macroscopic MAS components with wall thicknesses up to 4 mm as well as microstructured components with single micrometer resolution are shown. This work makes transparent MAS ceramics accessible to modern high-throughput polymer processing techniques for fast and cost-efficient manufacturing of macroscopic and microstructured components enabling a plethora of potential applications from optics and photonics, medicine to scratch and break-resistant transparent windows for consumer electronics