Shortest Path Problems on a Polyhedral Surface

We describe algorithms to compute edge sequences, a shortest path map, and the Fréchet distance for a convex polyhedral surface. Distances on the surface are measured by the length of a Euclidean shortest path. We describe how the star unfolding changes as a source point slides continuously along an edge of the convex polyhedral surface. We describe alternative algorithms to the edge sequence algorithm of Agarwal et al. (SIAM J. Comput. 26(6):1689–1713, 1997) for a convex polyhedral surface. Our approach uses persistent trees, star unfoldings, and kinetic Voronoi diagrams. We also show that the core of the star unfolding can overlap itself when the polyhedral surface is non-convex.     

An investigation and comparison of machine learning approaches for intrusion detection in IoMT network

The Journal of Supercomputing - Internet of Medical Things (IoMT) is network of interconnected medical devices (smart watches, pace makers, prosthetics, glucometer, etc.), software applications,...     

Second trimester abortion using prostaglandin E2 suppositories with or without intracervical Laminaria japonica: a randomized study

OBJECTIVE: To study cognitive function in an elderly population with persistent impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS: Fasting and postload 2-h plasma glucose and insulin levels were determined at baseline in a population-based sample of 1,300 people and repeated an average of 3.5 years later in 980 subjects. At follow-up, cognitive function was evaluated in subjects with persistent normal glucose tolerance (NGT; n = 506) and IGT (n = 80) with a brief neuropsychological test battery. RESULTS: Subjects with persistent IGT scored lower in the Mini-Mental State Examination (MMSE) and in the Buschke Selective Reminding Test long-term memory scores. Multiple linear regression analysis revealed that age, education, and insulin levels (either fasting or 2-h value) were associated with the MMSE score in subjects with persistent IGT. Other potential risk factors for impaired cognitive function were not significantly associated with the MMSE score. CONCLUSIONS: Our study showed that persistent IGT in the elderly is associated with mildly impaired cognitive function, and hyperinsulinemia may account for this association.     

Oblivious and fair server-aided two-party computation

We show efficient, practical (server-aided) secure two-party computation protocols ensuring privacy, correctness and fairness in the presence of malicious (Byzantine) faults. Our requirements from the server are modest. To ensure privacy and correctness, we only assume a circuit evaluation service, executing an initialisation program provided by both parties. To ensure fairness, we further assume a trusted-decryption service, providing decryption service using a known public key. Our fairness-ensuring protocol is optimistic, i.e., the decryption service is invoked only in case of faults.Both of these trusted services are feasible in practice, and may be useful for additional tasks; both can also be distributed, with linear overhead, for redundancy. We believe that the protocols are sufficiently efficient, to allow deployment, in particular for financial applications. We also propose applications which constitute natural candidates to benefit from our protocols.     

Real‐time density‐based crowd simulation

Virtual characters in games and simulations often need to plan visually convincing paths through a crowded environment. This paper describes how crowd density information can be used to guide a large number of characters through a crowded environment. Crowd density information helps characters avoid congested routes that could lead to traffic jams. It also encourages characters to use a wide variety of routes to reach their destination. Our technique measures the desirability of a route by combining distance information with crowd density information. We start by building a navigation mesh for the walkable regions in a polygonal two‐dimensional (2‐D) or multilayered three‐dimensional (3‐D) environment. The skeleton of this navigation mesh is the medial axis. Each walkable region in the navigation mesh maintains an up‐to‐date density value. This density value is equal to the area occupied by all the characters inside a given region divided by the total area of this region. These density values are mapped onto the medial axis to form a weighted graph. An A^* search on this graph yields a backbone path for each character, and forces are used to guide the characters through the weighted environment. The characters periodically replan their routes as the density values are updated. Our experiments show that we can compute congestion‐avoiding paths for tens of thousands of characters in real‐time. Copyright © 2012 John Wiley & Sons, Ltd.     

Self-organizing feature maps and hidden Markov models formachine-tool monitoring

Vibrations produced by the use of industrial machine tools can contain valuable information about the state of wear of tool cutting edges. However, extracting this information automatically is quite difficult. It has been observed that certain structures present in the vibration patterns are correlated with dullness. We present an approach to extracting features present in these structures using self-organizing feature maps (SOFMs). We have modified the SOFM algorithm in order to improve its generalization abilities and to allow it to better serve as a preprocessor for a hidden Markov model (HMM) classifier. We also discuss the challenge of determining which classes exist in the machining application and introduce an algorithm for automatic clustering of time-sequence patterns using the HMM. We show the success of this algorithm in finding clusters that are beneficial to the machine-monitoring application     

Quadratic detectors for energy estimation

The estimation of signal energy is an important part of physics and signal processing. A commonly used energy estimate in signal processing is instantaneous energy that is defined by the square of the signal magnitude at time t, i.e., |x(t)|². For a noisy signal, a standard energy detector, which consists of a linear time-invariant (LTI) filter followed by a magnitude-squared operator, is commonly used to reduce noise and extract signal energy in a certain frequency band. However, due to the temporal response of the LTI filtering, this energy estimate is smeared in time. In addition, it is unclear how this estimate relates to the physical energy in the system that produced the signal. e propose simple quadratic systems producing frequency-selective energy estimates and effective noise reduction with little or no smearing in time. We introduce the new concept of quadratic detectors, discuss desirable time and frequency resolution properties of a general quadratic detector, and study five different applications to demonstrate the simplicity of quadratic detector design and implementation     

Intracranial aneurysms: detection and characterization with MR angiography with use of an advanced postprocessing technique in a blinded-reader study

PURPOSE: To assess magnetic resonance (MR) angiography for the detection and characterization of angiographically proved intracranial aneurysms by using an advanced method of postprocessing, in a blinded-reader study. MATERIALS AND METHODS: One hundred fifty-eight vessels were examined with catheter angiography and three-dimensional time-of-flight MR angiography in 44 patients with 63 aneurysms and 15 patients with no aneurysm at catheter angiography. Postprocessing was performed off-line with an advanced multifeature-extraction, ray-tracing algorithm. MR angiograms were interpreted independently by three neuroradiologists blinded to the catheter angiographic results for presence, location, size, and morphology of the aneurysm. Proof of diagnosis was consensus reading of catheter angiograms. RESULTS: Mean sensitivity for detection of aneurysms was 75% (range, 70%-79%). As a screening tool (ie, detection of at least one aneurysm necessitating catheter angiography), mean sensitivity was 91% for all aneurysms and 95% for aneurysms larger than 3 mm. This method was not adequate for detection of lobulation or size of aneurysm. CONCLUSION: MR angiography with an advanced method of postprocessing can result in highly sensitive, specific studies for the diagnosis of intracranial aneurysms that are of sufficient size to be considered for surgical treatment, but it is inadequate for characterization of aneurysms.