Frank Weichert

Analysis of the Accuracy and Robustness of the Leap Motion Controller

The Leap Motion Controller is a new device for hand gesture controlled user interfaces with declared sub-millimeter accuracy. However, up to this point its capabilities in real environments have not been analyzed. Therefore, this paper presents a first study of a Leap Motion Controller. The main focus of attention is on the evaluation of the accuracy and repeatability. For an appropriate evaluation, a novel experimental setup was developed making use of an industrial robot with a reference pen allowing a position accuracy of 0.2 mm. Thereby, a deviation between a desired 3D position and the average measured positions below 0.2 mm has been obtained for static setups and of 1.2 mm for dynamic setups. Using the conclusion of this analysis can improve the development of applications for the Leap Motion controller in the field of Human-Computer Interaction.

Macrophages and bisphosphonate-related osteonecrosis of the jaw (BRONJ): evidence of local immunosuppression of macrophages in contrast to other infectious jaw diseases

ObjectivesBisphosphonates (BIP) are well established in bone diseases. A serious side effect is the bisphosphonate-related osteonecrosis of the jaw (BRONJ). Among different aetiology factors, local suppression of immune functions is gaining interest. The aim of this study was to analyze the function of macrophages in BRONJ in contrast to patients with osteoradionecrosis (ORN) and secondary chronic osteomyelitis (OM) of the jaws. Samples were also taken from patients with bisphosphonate medication (BP) without signs of infection, radiation therapy (RA), and osteoporosis (OP) as controls.Material and methodsOne hundred five patients with surgery to the jaw were included in this study: 33 patients with BRONJ, 17 with ORN, 11 with secondary chronic OM, 8 with RA, 25 with BP medication and 11 with OP. Samples were histologically analysed and monocytes/macrophages stained using CD14 and CD68. The number of positively marked cells was counted per view (pv), and the CD68/CD14 ratio was calculated. Statistically, the Naïve-Bayes and decision-tree classifier were used.ResultsThe number of CD14 positive cells was 10.3 cells/pv in the BRONJ-group in as compared to 5 in the ORN- and 3.8 in the OM-group respectively. The number of CD68 positive cells was 11.4/pv (BRONJ-group) as compared to 14/pv (ORN-group) and 12.7/pv (OM-group). With 0.89, the BRONJ-group showed a statistically different CD68/CD14 ratio than ORN-group with 3.39 and OM-group with 3.03.ConclusionsOur results indicate a different expression of CD14 and CD68 markers of monocytes/macrophages in BRONJ as compared to other jaw infections. This could be a sign of macrophage immunosuppression by BPs. In contrast, patients receiving BP medication without BRONJ showed no differences to other controls.Clinical relevanceThis is the first study that clinically indicates a compromised macrophage function at BRONJ sites in contrast to ORN or secondary OM sites. The BRONJ itself could be forwarded by this effect.

Virtual 3D IVUS vessel model for intravascular brachytherapy planning. I. 3D segmentation, reconstruction, and visualization of coronary artery architecture and orientation.

Intravascular brachytherapy (IVB) can significantly reduce the risk of restenosis after interventional treatment of stenotic arteries, if planned and applied correctly. To facilitate computer-based IVB planning, a three-dimensional vessel model has been derived from information on coronary artery segments acquired by intravascular ultrasound (IVUS) and biplane angiography. Part I describes the approach of model construction and presents possibilities of visualization. The vessel model is represented by a voxel volume. Polygonal information about the vessel wall structure is derived by segmentation from a sequence of IVUS images automatically acquired ECG gated during pull back of the IVUS transducer. To detect horizontal, vertical, and radial contours, modified Canny-Edge and Shen-Castan filters are applied on Cartesian and polar coordinate representations of the IVUS tomograms as edge detectors. The spatial course of the vessel wall layers is traced in reconstructed longitudinal IVUS scans. By resampling the sequence of IVUS frames the voxel volume is obtained. For this purpose the frames are properly located in space and augmented with additional intermediate frames generated by interpolation. Their spatial location and orientation is derived from biplane X-ray angiography which is performed simultaneously. For resampling, two approaches are proposed: insertion of the vertices of the rectangular goal grid into the cells of a deformed hexahedral mesh derived from the IVUS sequence, and insertion of the vertices of the hexahedral mesh into the cells of the rectangular grid. Finally, the vessel model is visualized by methods of combined volume and polygon rendering. The segmentation process is verified as being in good agreement with results obtained by manual contour tracing with a commercial system. Our approach of construction of the vessel model has been implemented into an interactive software system, 3D IVUS-View, serving as the basis of a future system for intracoronary brachytherapy treatment planning being currently under development (Part II).

Application of surface plasmon resonance imaging technique for the detection of single spherical biological submicrometer particles

Recent proof-of-principle studies demonstrated the suitability of the surface plasmon resonance imaging (SPRi) technique for the detection of individual submicrometer and nanoparticles in solutions. In the current study, we used the SPRi technique for visualization of the binding of round-shaped viruses (inactivated influenza A virus) and virus-like particles (human immunodeficiency virus (HIV)-based virus-like particles) to the functionalized sensor surface. We show the applicability of the SPRi technique for the detection of individual virus-like particles in buffers without serum as well as in buffers containing different concentrations of serum. Furthermore, we prove the specificity of visualized binding events using two different pseudotypes of HIV virus-like particles. We also demonstrate the applicability of the SPRi technique for the determination of relative particle concentrations in solutions. Moreover, we suggest a technical approach, which allows enhancing the magnitude of binding signals. Our studies indicate that the SPRi technique represents an efficient research tool for quantification and characterization of biological submicrometer objects such as viruses or virus-like particles, for example.

Concept of automated load detection for de-palletizing using depth images and RFID data

In this paper, we present a novel concept for the detection of loading positions of parcels or bins on a pallet to enable automated order picking using knowledge about the packing pattern model. The approach comprises (1) a new combination of pattern model data and PMD-camera-generated point clouds and (2) a novel concept of RFID data management using a Binary data on Tag / Schema on Net and semantic coding approach. The latter enables the use of additional services like storing of loading positions on auto-id devices (RFID-tags) in a wider concept of the Internet of Things, while the former presents an alternative approach in the context of contour check and position detection of unit loads for automated de-palletizing.

Computation of a finite element-conformal tetrahedral mesh approximation for simulated soft tissue deformation using a deformable surface model.

In this article, we present a new method for the generation of surface meshes of biological soft tissue. The method is based on the deformable surface model technique and is extended to histological data sets. It relies on an iterative adjustment towards polygonal segments describing the histological structures of the soft tissue. The generated surface meshes allow for the construction of volumetric meshes through a standard constrained Delaunay approach and, thus, for the application in finite element methods. The geometric properties of volumetric meshes have an immediate influence on the numerical conditioning and, therewith, on the stability of the finite element method and the convergence of iterative solvers. In this article, the influence of the surface meshes on the quality of the volumetric meshes is analysed in terms of the spectral condition number of the stiffness matrices, which are assembled within Newton’s method. The non-linear material behavior of biological soft tissue is modeled by the Mooney–Rivlin material law. The subject is motivated by the requirements of virtual surgery.

Tissue-plastinated vs. celloidin-embedded large serial sections in video, analog and digital photographic on-screen reproduction: a preliminary step to exact virtual 3D modelling, exemplified in the normal midface and cleft-lip and palate

This study analyses tissue‐plastinated vs. celloidin‐embedded large serial sections, their inherent artefacts and aptitude with common video, analog or digital photographic on‐screen reproduction. Subsequent virtual 3D microanatomical reconstruction will increase our knowledge of normal and pathological microanatomy for cleft‐lip‐palate (clp) reconstructive surgery. Of 18 fetal (six clp, 12 control) specimens, six randomized specimens (two clp) were BiodurE12‐plastinated, sawn, burnished 90 µm thick transversely (five) or frontally (one), stained with azureII/methylene blue, and counterstained with basic‐fuchsin (TP‐AMF). Twelve remaining specimens (four clp) were celloidin‐embedded, microtome‐sectioned 75 µm thick transversely (ten) or frontally (two), and stained with haematoxylin–eosin (CE‐HE). Computed‐planimetry gauged artefacts, structure differentiation was compared with light microscopy on video, analog and digital photography. Total artefact was 0.9% (TP‐AMF) and 2.1% (CE‐HE); TP‐AMF showed higher colour contrast, gamut and luminance, and CE‐HE more red contrast, saturation and hue (P < 0.4). All (100%) structures of interest were light microscopically discerned, 83% on video, 76% on analog photography and 98% in digital photography. Computed image analysis assessed the greatest colour contrast, gamut, luminance and saturation on video; the most detailed, colour‐balanced and sharpest images were obatined with digital photography (P < 0.02). TP‐AMF retained spatial oversight, covered the entire area of interest and should be combined in different specimens with CE‐HE which enables more refined muscle fibre reproduction. Digital photography is preferred for on‐screen analysis.

Automated detection of euro pallet loads by interpreting PMD camera depth images

In this study, a novel approach for the detection of parcel loading positions on a pallet is presented. This approach was realized as a substantial change in comparison with traditional system design of contour detection in de-palletizing processes. Complex 3D-vision systems, costly laser scanners or throughput decreasing local sensor solutions integrated in grippers are substituted by a low-cost photonic mixing device (PMD) camera. By combining PMD technology and a predetermined model of loading situations, stored during assembling the pallet, this approach can compensate for the drawbacks of each respective system. An essential part of the approach are computer-graphics methods specific to the given problem to both detect the deviation between the nominal and the actual loading position and if necessary an automated correction of the packaging scheme. From an economic point of view, this approach can decrease the costs of mandatory contour checking in automated de-palletizing processes.

Simulation of Intra-Aneurysmal Blood Flow by Different Numerical Methods

The occlusional performance of sole endoluminal stenting of intracranial aneurysms is controversially discussed in the literature. Simulation of blood flow has been studied to shed light on possible causal attributions. The outcome, however, largely depends on the numerical method and various free parameters. The present study is therefore conducted to find ways to define parameters and efficiently explore the huge parameter space with finite element methods (FEMs) and lattice Boltzmann methods (LBMs). The goal is to identify both the impact of different parameters on the results of computational fluid dynamics (CFD) and their advantages and disadvantages. CFD is applied to assess flow and aneurysmal vorticity in 2D and 3D models. To assess and compare initial simulation results, simplified 2D and 3D models based on key features of real geometries and medical expert knowledge were used. A result obtained from this analysis indicates that a combined use of the different numerical methods, LBM for fast exploration and FEM for a more in-depth look, may result in a better understanding of blood flow and may also lead to more accurate information about factors that influence conditions for stenting of intracranial aneurysms.

Marker-based tracking in support of RFID controlled material flow systems

In this study, we present a novel approach for continuous detection, localization, and identification of parcels and bins in automated facility logistics systems. It presents a distinct departure from the traditional system design: light barriers and barcode readers are substituted by low-cost cameras and few RFID readers. By combining vision-based systems and RFID systems, this approach can compensate for the drawbacks of each respective system. For example, only the vision system is used for localization. The main part of our paper describes computer-graphics methods specific to the given problem to both track and read visual markers attached to parcels or bins. In addition, we use information from the RFID system to narrow the decision space for detection and identification. From an economic point of view, this approach can lower the costs of changing a material flow system.