Geodesic length measurement in medical images: Effect of the discretization by the camera chip and quantitative assessment of error reduction methods

After interventions such as bypass surgeries the vascular function is checked qualitatively and remotely by observing the blood dynamics inside the vessel via Fluorescence Angiography. This state-of-the-art method has to be improved by introducing a quantitatively measured blood flow. Previous approaches show that the measured blood flow cannot be easily calibrated against a gold standard reference. In order to systematically address the possible sources of error, we investigated the error in geodesic length measurement caused by spatial discretization on the camera chip. We used an in-silico vessel segmentation model based on mathematical functions as a ground truth for the length of vessel-like anatomical structures in the continuous space. Discretization errors for the chosen models were determined in a typical magnitude of 6%. Since this length error would propagate to an unacceptable error in blood flow measurement, counteractions need to be developed. Therefore, different methods for the centerline extraction and spatial interpolation have been tested and compared against their performance in reducing the discretization error in length measurement by re-continualization. In conclusion, the discretization error is reduced by the re-continualization of the centerline to an acceptable range. The discretization error is dependent on the complexity of the centerline and this dependency is also reduced. Thereby the centerline extraction by erosion in combination with the piecewise Bézier curve fitting performs best by reducing the error to 2.7% with an acceptable computational time

N=4 Characters in Gepner Models, Orbits and Elliptic Genera

We review the properties of characters of the N=4 SCA in the context of a non-linear sigma model on $K3$, how they are used to span the orbits, and how the orbits produce topological invariants like the elliptic genus. We derive the same expression for the $K3$ elliptic genus using three different Gepner models ($1^6$, $2^4$ and $4^3$ theories), detailing the orbits and verifying that their coefficients $F_i$ are given by elementary modular functions. We also reveal the orbits for the $1^3 2^2$, $1^4 4$ and $1^2 4^2$ theories. We derive relations for cubes of theta functions and study the function ${1\over\eta} \sum_{n\in \Z} (-1)^n (6n+1)^k q^{(6n+1)^2 /24}$ for $k=1,2,3,4$.Comment: 39 pages; errors corrected in section 6, section 7 added (mixed Gepner models), ref adde

Mesons and Higgs branch in defect theories

We consider the defect theory obtained by intersecting D3- and D5-branes along two common spatial directions. We work in the approximation in which the D5-brane is a probe in the AdS_5xS^5 background. By adding worldvolume flux to the D5-brane and choosing an appropriate embedding of the probe in AdS_5xS^5, one gets a supersymmetric configuration in which some of the D3-branes recombine with the D5-brane. We check this fact by showing that the D5-brane can be regarded as a system of polarized D3-branes. On the field theory side this corresponds to the Higgs branch of the defect theory, where some of the fundamental hypermultiplet fields living on the intersection acquire a vacuum expectation value. We study the spectrum of mesonic bound states of the defect theory in this Higgs branch and show that it is continuous and gapless.Comment: 15 pages, LaTe

Limits and Degenerations of Unitary Conformal Field Theories

In the present paper, degeneration phenomena in conformal field theories are studied. For this purpose, a notion of convergent sequences of CFTs is introduced. Properties of the resulting limit structure are used to associate geometric degenerations to degenerating sequences of CFTs, which, as familiar from large volume limits of non-linear sigma models, can be regarded as commutative degenerations of the corresponding ``quantum geometries''. As an application, the large level limit of the A-series of unitary Virasoro minimal models is investigated in detail. In particular, its geometric interpretation is determined.Comment: 57 pages, no figures; minor clarifications and reference added; final version to appear in Commun. Math. Phy

Automated vessel centerline extraction and diameter measurement in OCT Angiography

Optical Coherence Tomography Angiography (OCTA) is a non-invasive imaging technique that enables the visualizationof perfused vasculature in vivo. In ophthalmology,it allows the physician to monitor diseases affecting the vascular networks of the retina such as age-related macular degeneration or diabetic retinopathy. Due to the complexity of the vasculature in the retina,it is of interest to automatically extract vascular parameters which describe the condition of the vessels. Suitable parameters could improve the diagnosis and the treatment during the course of therapy.We present an automated algorithm tocompute the diameters of the vessels in en face OCTA images. After segmentingthe images, the vessel centerlinewascomputed using a thinningalgorithm.The centerline wasrefined by detecting invalid pixelssuch as spursandbycontinuing the centerline until the endsof the vessels. Lastly, the diameter wascomputed by dilating a discrete circle at the position of the centerline or by measuring the distance between both borders of the vessels. The developed algorithms were applied to in vivo images of human eyes. Certainly, no ground truth was available. Hence, a plausibility check was performed by comparing the measured diameters of two different layers of the retina (Superficial Vascular Complex (SVC) and Deep Vascular Complex (DVC)). Each layer exhibits a different characteristic vasculature.The algorithm clearly reflectedthe differences from both retinal layers. The measured diameters demonstrate that the DVC consists of more capillaries and considerably smaller vessels compared to the SVC.The presented method enables automated analysis of the retinal vasculature and forms thereby the basis for monitoringdiseases influencing the vasculature of the retina. The validation of the method using an artificial ground truth is still neede

Fourier-Mukai and Nahm transforms for holomorphic triples on elliptic curves

We define a Fourier-Mukai transform for a triple consisting of two holomorphic vector bundles over an elliptic curve and a homomorphism between them. We prove that in some cases the transform preserves the natural stability condition for a triple. We also define a Nahm transform for solutions to natural gauge-theoretic equations on a triple -- vortices -- and explore some of its basic properties. Our approach combines direct methods with dimensional reduction techniques, relating triples over a curve with vector bundles over the product of the curve with the complex projective line.Comment: 39 pages, LaTeX2e, no figures; new proofs added, some arguments rewritten and typos corrected. Final version to appear in Journal of Geometry and Physic

A versatile biomaterial ink platform for the melt electrowriting of chemically-crosslinked hydrogels

In this study, we designed a novel biomaterial ink platform based on hydrophilic poly(2-ethyl-2-oxazine) (PEtOzi) specifically for melt electrowriting (MEW). This material crosslinks spontaneously after processing via dynamic Diels–Alder click chemistry. These direct-written microperiodic structures rapidly swell in water to yield thermoreversible hydrogels. These hydrogels are robust enough for repeated aspiration and ejection through a cannula without structural damage, despite their high water content of 84%. Moreover, the scaffolds retain functional groups for modification using click chemistry and therefore can be readily functionalized as demonstrated using fluorophores and peptides to facilitate visualization and cell attachment. The PEtOzi hydrogel developed here is compatible with confocal imaging and staining protocols for cells. In summary, an advanced material platform based on PEtOzi is reported that is compatible with MEW and results in functionalizable chemically crosslinked microperiodic hydrogels.Peer reviewe

End-of-Life Experiences: A Survey among Physicians and Nurses in a Hospital for Anthroposophically Extended Medicine

Hintergrund: Wissenschaftliche Studien zum mentalen Zustand sterbender Personen in den Wochen und Tagen vor dem Tod liegen bisher nur vereinzelt vor. Bekannt ist, dass die Spiritualität zum Lebensende hin eine wichtigere Rolle einnimmt als zuvor. In der Anthroposophie wird davon ausgegangen, dass sich im Sterbeprozess die Seele und der Geist vom physischen Körper lösen und in die geistige Welt eingehen. Methode: Wir führten eine retrospektive Umfrage unter Ärzten und Pflegenden der Klinik Arlesheim durch. Der schriftliche Fragebogen bestand aus 60 geschlossenen und 5 offenen Fragen zu Beobachtungen und Wahrnehmungen von Erfahrungen am Lebensende (ELE). Ergebnisse: Der Rücklauf betrug 18% (21 Fragebögen). Folgende Phänomene wurden von den Befragten bei Patienten in deren letzten Lebenswochen am häufigsten beobachtet: Patienten verfügten plötzlich über viel Zuversicht und Energie; belastende Emotionen nahmen zu; Patienten nahmen phasenweise eine andere Realitätsebene wahr. ELE wurden von den Antwortenden als Quelle spirituellen Trosts für Sterbende und Angehörige empfunden. Schlussfolgerung: Ärzte und Pflegende in einem Spital für anthroposophisch erweiterte Medizin in der Schweiz berichteten von ähnlichen ELE ihrer Patientinnen und Patienten wie in zuvor in England durchgeführten Studien. Um sich im Umgang mit ELE sicherer zu fühlen, wünschten sich Ärzte und Pflegende mehr Informationen im Rahmen entsprechender Aus- oder Weiterbildungen.Background: The perceptions of dying persons during the last weeks and days of their lives have rarely been investigated. It is known that spirituality becomes more important towards the end of life. In anthroposophy, it is assumed that during the process of dying the soul and spirit are detached from the physical body and enter the spiritual world. Method: We conducted a retrospective survey among physicians and nurses working at the Klinik Arlesheim. The written questionnaire consisted of 60 closed and 5 open questions on observations and perceptions of end-of-life experiences (ELE). Results: The response rate was 18% (21 questionnaires). The phenomena observed most frequently in patients during their last weeks of life were as follows: patients suddenly possessed much confidence and energy; burdensome emotions were increased; patients commuted back and forth between different realities. The respondents described ELE as a source of spiritual comfort for the dying as well as the relatives. Conclusion: Physicians and nurses working in a hospital for anthroposophically extended medicine in Switzerland reported ELE of their patients similar to those reported in studies conducted in England. Physicians and nurses wished for more information during their education in order to feel more confident when dealing with ELE.Peer Reviewe

28043 Roflumilast cream significantly improves chronic plaque psoriasis in patients with steroid-sensitive area involvement

Roflumilast cream is a nonsteroidal, selective phosphodiesterase-4 inhibitor in development for plaque psoriasis (PsO). A double-blind, phase 2b trial randomized adults with PsO to once daily roflumilast 0.3%, 0.15%, or vehicle for 12 weeks (NCT03638258).(1) Efficacy was assessed using Investigator Global Assessment (IGA), Worst Itch Numeric Rating Scale (WI–NRS), and Psoriasis Symptom Diary (PSD). This posthoc analysis reports efficacy and safety in patients with steroid-sensitive area involvement (plaques on the face, neck, or in intertriginous areas). Of 331 patients, 160 had steroid-sensitive area involvement. The primary endpoint in the study, IGA status clear/almost clear at Week 6 was met by 27.2% patients with steroid sensitive areas (P =.007 vs vehicle), 22.3% (P =.026), and 6.3% on roflumilast 0.3%, roflumilast 0.15%, and vehicle, respectively; relative to 30.1% (P =.026), 24.1% (P =.098), and 12.0% patients without steroid-sensitive areas. Among patients with baseline WI–NRS score ≥4, 73.5%, 55.6%, and 32.6% of those with steroid-sensitive areas and 45.9%, 72.7%, and 23.7% of those without steroid-sensitive areas achieved a 4-point reduction with roflumilast 0.3%, 0.15%, or vehicle at Week 12. PSD improvement from baseline at Week 12 for patients with steroid-sensitive areas was -48.3 (P ˂.001), -43.1 (P =.012), and -24.9, and for patients without steroid-sensitive areas -35.7 (P =.003), -44.6 (P ˂.001), and -17.1. Most treatment emergent adverse events were mild to moderate and there was no evidence of local irritation. Once-daily roflumilast cream was well tolerated with significant improvements in investigator and patient assessed PsO outcomes in patients with steroid-sensitive area involvement on the face, neck, or intertriginous areas