HashSDF: Accurate Implicit Surfaces with Fast Local Features on Permutohedral Lattices

Neural radiance-density field methods have become increasingly popular for the task of novel-view rendering. Their recent extension to hash-based positional encoding ensures fast training and inference with state-of-the-art results. However, density-based methods struggle with recovering accurate surface geometry. Hybrid methods alleviate this issue by optimizing the density based on an underlying SDF. However, current SDF methods are overly smooth and miss fine geometric details. In this work, we combine the strengths of these two lines of work in a novel hash-based implicit surface representation. We propose improvements to the two areas by replacing the voxel hash encoding with a permutohedral lattice which optimizes faster in three and higher dimensions. We additionally propose a regularization scheme which is crucial for recovering high-frequency geometric detail. We evaluate our method on multiple datasets and show that we can recover geometric detail at the level of pores and wrinkles while using only RGB images for supervision. Furthermore, using sphere tracing we can render novel views at 30 fps on an RTX 3090

All-Path Reachability Logic

This paper presents a language-independent proof system for reachability properties of programs written in non-deterministic (e.g., concurrent) languages, referred to as all-path reachability logic. It derives partial-correctness properties with all-path semantics (a state satisfying a given precondition reaches states satisfying a given postcondition on all terminating execution paths). The proof system takes as axioms any unconditional operational semantics, and is sound (partially correct) and (relatively) complete, independent of the object language. The soundness has also been mechanized in Coq. This approach is implemented in a tool for semantics-based verification as part of the K framework (http://kframework.org

Role of the Electrophysiologist in the Treatment of Tachycardia-Induced Cardiomyopathy

Tachycardia-induced cardiomyopathy is a systolic cardiac dysfunction given by prolonged elevated heart rates in patients with incessant or frequent tachyarrhythmias. Arrhythmias associated with tachycardiomyopathy can be either supraventricular (atrial tachycardia, atrial flutter, atrial fibrillation, AVNRT, permanent junctional reciprocating tachycardia, high rates of atrial pacing) or ventricular (frequent premature ventricular complexes, right ventricular outflow tract tachycardia, LVOT, left ventricular fascicular tachycardia, bundle-branch reentry or high rate of ventricular pacing). Electrophysiological study confirms the clinical diagnosis of tachycardia-induced cardiomyopathy, reveals the arrhythmia mechanism and facilitates catheter ablation that results in complete recovery of ventricular function. This chapter has two parts: 1. Theoretical insight into the pathogenesis of tachycardia-induced cardiomyopathy, clinical manifestations and therapy. 2. Practical issues: we describe our EP lab’s experience on electrophysiological study and ablation in patients with tachycardia-induced cardiomyopathy. We will present five cases of ablation: PVCs >30,000/24 h, antidromic tachycardia, 2:1 atrial flutter, persistent atrial fibrillation and RVOT PVCs with nonsustained VT

ICD Electrograms in Patients with Brugada Syndrome

In patients with Brugada syndrome, implantable cardioverter‐defibrillator (ICD) is the only demonstrated treatment that prevents sudden cardiac death. The progress in ICD technology improved the diagnosis and efficacy of implantable devices in the management and treatment of ventricular tachycardia (VT) and ventricular fibrillation (VF). Recording of electrical events just before and after a delivered or aborted ICD therapy permits a more accurate characterization of the rhythm but also provides information on the electrical events preceding the arrhythmia. This chapter aims to gain insight into the mechanism of initiation and termination of spontaneous VF by analyzing intracardiac electrograms (IEGM) in Brugada patients implanted with ICDs. It has two parts: (1) update on ICD electrograms in Brugada syndrome patients, where we review the medical literature on ICD electrograms and their use for detecting electrical manifestations of Brugada syndrome, and (2) examples of ICD electrograms, from our own database of patients affected by Brugada syndrome

Cardiac Anatomy for the Electrophysiologist with Emphasis on the Left Atrium and Pulmonary Veins

This chapter aims to provide basic anatomical knowledge for the interventional electrophysiologists to understand catheter placement and ablation targets. We begin with the location of the heart inside the mediastinum, position of cardiac chambers, pericardial space and neighboring structures of the heart. We continue with the right atrium and important structures inside it: sinus node, cavotricuspid isthmus, Koch’s triangle and interatrial septum with fossa ovalis. A special part of this chapter is dedicated to the left atrium and pulmonary veins with the venoatrial junction, important structures for catheter ablation of atrial fibrillation. We finish our description with both ventricles with outflow tracts and the coronary venous system

The effect of glucosamine, chondroitin and harpagophytum procumbens on femoral hyaline cartilage thickness in patients with knee osteoarthritis– An MRI versus ultrasonography study

Background: the evaluation of cartilage thickness has become possible with new techniques such as musculoskeletal ultrasonography (US) and magnetic resonance imagining (MRI), making the evaluation of the treatment response and the progression of the disease more accurate. Objective: to evaluate the efficacy of a Symptomatic Slow Acting Drug for Osteoarthritis using both US and MRI for measuring cartilage thickness at baseline and after 1 year. Methods: The study included the clinical evaluation of 20 patients at baseline, at 6 and 12 months as well as imaging exams (US and MRI) at baseline and after 1 year. Measurements were performed in both knees, in lateral and medial condyles, and in the intercondylar area. After the baseline visit, patients underwent a SYSADOA treatment which included Harpagophytum procumbens (HPc) administered on a daily basis, in a specific regimen. Results and discussions: The US examination permitted the detailed evaluation of the femoral hyaline cartilage thickness, with statistically significant differences before and after treatment at the level of the medial compartment, both in the dominant (1.59±0.49 vs. 1.68±0.49, p=0.0013) and non-dominant knee (1.73±0.53 vs. 1.79±0.52, p=0.0106). The US and the MRI correlated well (r=0.63) and showed no radiographic progression in knee osteoarthritis after one year of treatment with specific SYSADOA. Moreover, the US showed improvement in the cartilage thickness of the medial compartment. Conclusions: The combination with HPc could increase the delay in the radiographic progression of the knee osteoarthritis, with improvement of femoral hyaline cartilage thickness in the medial and lateral compartment. The US might be an important tool in OA evaluation and monitoring

Preliminary design of aeroelastically tailored wing box structures with bend-twist coupling

Nowadays the composite materials have become the materials of choice to be used in the new aerospace structures that need to be not only larger and larger in size but also to be better performing in terms of aeroelastic responses inherent to thin-walled, slender structures. The advantage of composite materials airframes stems from their low structural weight which determines lower fuel consumption while preserving at the same time the airworthiness of the designed aircraft. But more important than the fuel consumption, the composite materials allow for the optimal tailoring of its layers in terms of specific design objectives. The paper presents such an aeroelastically tailored load carrying wing model which can passively control specific aeroelastic effects. The article focuses on the bend-twist coupling of the structural response to aerodynamic forces and on the parameter estimation/model updating techniques used to characterize the finite element model of the composite wing. Results are compared and validated with analytical, numerical and experimental data available in published literature