Scalable and distributed constrained low rank approximations

Low rank approximation is the problem of finding two low rank factors W and H such that the rank(WH) << rank(A) and A ≈ WH. These low rank factors W and H can be constrained for meaningful physical interpretation and referred as Constrained Low Rank Approximation (CLRA). Like most of the constrained optimization problem, performing CLRA can be computationally expensive than its unconstrained counterpart. A widely used CLRA is the Non-negative Matrix Factorization (NMF) which enforces non-negativity constraints in each of its low rank factors W and H. In this thesis, I focus on scalable/distributed CLRA algorithms for constraints such as boundedness and non-negativity for large real world matrices that includes text, High Definition (HD) video, social networks and recommender systems. First, I begin with the Bounded Matrix Low Rank Approximation (BMA) which imposes a lower and an upper bound on every element of the lower rank matrix. BMA is more challenging than NMF as it imposes bounds on the product WH rather than on each of the low rank factors W and H. For very large input matrices, we extend our BMA algorithm to Block BMA that can scale to a large number of processors. In applications, such as HD video, where the input matrix to be factored is extremely large, distributed computation is inevitable and the network communication becomes a major performance bottleneck. Towards this end, we propose a novel distributed Communication Avoiding NMF (CANMF) algorithm that communicates only the right low rank factor to its neighboring machine. Finally, a general distributed HPC- NMF framework that uses HPC techniques in communication intensive NMF operations and suitable for broader class of NMF algorithms.Ph.D

Diagnosis and treatment of neurogenic dysphagia - S1 guideline of the German Society of Neurology.

INTRODUCTION Neurogenic dysphagia defines swallowing disorders caused by diseases of the central and peripheral nervous system, neuromuscular transmission, or muscles. Neurogenic dysphagia is one of the most common and at the same time most dangerous symptoms of many neurological diseases. Its most important sequelae include aspiration pneumonia, malnutrition and dehydration, and affected patients more often require long-term care and are exposed to an increased mortality. Based on a systematic pubmed research of related original papers, review articles, international guidelines and surveys about the diagnostics and treatment of neurogenic dysphagia, a consensus process was initiated, which included dysphagia experts from 27 medical societies. RECOMMENDATIONS This guideline consists of 53 recommendations covering in its first part the whole diagnostic spectrum from the dysphagia specific medical history, initial dysphagia screening and clinical assessment, to more refined instrumental procedures, such as flexible endoscopic evaluation of swallowing, the videofluoroscopic swallowing study and high-resolution manometry. In addition, specific clinical scenarios are captured, among others the management of patients with nasogastric and tracheotomy tubes. The second part of this guideline is dedicated to the treatment of neurogenic dysphagia. Apart from dietary interventions and behavioral swallowing treatment, interventions to improve oral hygiene, pharmacological treatment options, different modalities of neurostimulation as well as minimally invasive and surgical therapies are dealt with. CONCLUSIONS The diagnosis and treatment of neurogenic dysphagia is challenging and requires a joined effort of different medical professions. While the evidence supporting the implementation of dysphagia screening is rather convincing, further trials are needed to improve the quality of evidence for more refined methods of dysphagia diagnostics and, in particular, the different treatment options of neurogenic dysphagia. The present article is an abridged and translated version of the guideline recently published online ( https://www.awmf.org/uploads/tx_szleitlinien/030-111l_Neurogene-Dysphagie_2020-05.pdf )

Anthropomorphic surgical system for soft tissue robot-assisted surgery

Over the past century, abdominal surgery has seen a rapid transition from open procedures to less invasive methods such as laparoscopy and robot-assisted minimally invasive surgery (R-A MIS). These procedures have significantly decreased blood loss, postoperative morbidity and length of hospital stay in comparison with open surgery. R-A MIS has offered refined accuracy and more ergonomic instruments for surgeons, further minimising trauma to the patient.This thesis aims to investigate, design and prototype a novel system for R-A MIS that will provide more natural and intuitive manipulation of soft tissues and, at the same time, increase the surgeon's dexterity. The thesis reviews related work on surgical systems and discusses the requirements for designing surgical instrumentation. From the background research conducted in this thesis, it is clear that training surgeons in MIS procedures is becoming increasingly long and arduous. Furthermore, most available systems adopt a design similar to conventional laparoscopic instruments or focus on different techniques with debatable benefits. The system proposed in this thesis not only aims to reduce the training time for surgeons but also to improve the ergonomics of the procedure.In order to achieve this, a survey was conducted among surgeons, regarding their opinions on surgical training, surgical systems, how satisfied they are with them and how easy they are to use. A concept for MIS robotic instrumentation was then developed and a series of focus group meetings with surgeons were run to discuss it. The proposed system, named microAngelo, is an anthropomorphic master-slave system that comprises a three-digit miniature hand that can be controlled using the master, a three-digit sensory exoskeleton. While multi-fingered robotic hands have been developed for decades, none have been used for surgical operations. As the system has a human centred design, its relation to the human hand is discussed. Prototypes of both the master and the slave have been developed and their design and mechanisms is demonstrated. The accuracy and repeatability of the master as well as the accuracy and force capabilities of the slave are tested and discussed

A Time of Flight on-Robot Proximity Sensing System for Collaborative Robotics

The sensor system presented in this work demonstrates the results of designing an industrial grade exteroceptive sensing device for proximity sensing for collaborative robots. The intention of this design\u27s application is to develop an on-robot small footprint proximity sensing device to prevent safety protected stops from halting a robot during a manufacturing process. Additionally, this system was design to be modular and fit on an size or shape robotic link expanding the sensor system\u27s use cases vastly. The design was assembled and put through a number of benchmark tests to validate the performance of the time of flight (ToF) sensor system when used in proximity sensing: Single Sensor Characterization, Sensor Overlap Characterization, and Sensor Ranging Under Motion. Through these tests, the ToF sensor ring achieves real time data throughput while minimizing blind spots. Lastly, the sensor system was tested at a maximum throughput load of 32 ToF sensors and maintained a stable throughput of data from all sensors in real time

The potential of LIDAR as an antisubmarine warfare sensor

Traditionally, antisubmarine warfare (ASW) has been dominated by acoustic sensors, active and passive. Ending the Cold War, the ASW forces have refocused towards a theatre of war in the littorals, and the traditional acoustic sensors do not perform very well in such an environment. The sensors are working much closer to the surface, and there is a lot more surface traffic to disturb the acoustic environment. Environmental and topographic factors also play a major role. Removing or significantly reducing the acoustic capability, one forces the ASW forces to look to other technologies and sensors to compliment or replace the acoustic ones. This is where the interest of LIDAR as an aerial ASW sensor comes into play. The aim of this thesis is to evaluate “the potential for using LIDAR technology for aerial ASW on Norwegian ASW platforms”. In addition to this main research question, the history of LIDAR has been researched, in order to find historical and existing LIDAR projects for ASW purposes. Antisubmarine warfare is a complicated business, but speed of reaction, flexibility to change operating areas quickly and efficiently, and the ability to deploy sophisticated buoys are all in the advantage to the aerial ASW platform. But as the submarines get quieter and quieter, new means of detection must be found to cover the complicated upper layers of the water column. The signal components of LIDAR and the increasing processing capability have made LIDAR technology somewhat mature, but limitations such as scattering and attenuation of light in water are severely hampering. After a decline in ASW focus after the Cold War, the Western world is finding itself in a littoral submarine threat scenario, and do not have the sensors to sufficiently meet this threat. Several LIDAR programs have been initiated and carried through, but most have been directed towards finding and neutralizing mines. Lately, a new interest of applying LIDAR-technology in the search for submarines has risen. But LIDAR itself does not seem to be able to cover the upper layers of the water column consistently enough, and other technologies might be able to compliment LIDAR in a multi-sensor solution. Synthetic Aperture Radar (SAR) and Hyperspectral Imagery seem to be the most applicable of these. A recommendation is given to military commanders to pursue a multi-sensor pod for several areas of use by Maritime Patrol Aircraft and military helicopters

Patterns of injury and violence in Yaoundé Cameroon: an analysis of hospital data.

BackgroundInjuries are quickly becoming a leading cause of death globally, disproportionately affecting sub-Saharan Africa, where reports on the epidemiology of injuries are extremely limited. Reports on the patterns and frequency of injuries are available from Cameroon are also scarce. This study explores the patterns of trauma seen at the emergency ward of the busiest trauma center in Cameroon's capital city.Materials and methodsAdministrative records from January 1, 2007, through December 31, 2007, were retrospectively reviewed; information on age, gender, mechanism of injury, and outcome was abstracted for all trauma patients presenting to the emergency ward. Univariate analysis was performed to assess patterns of injuries in terms of mechanism, date, age, and gender. Bivariate analysis was used to explore potential relationships between demographic variables and mechanism of injury.ResultsA total of 6,234 injured people were seen at the Central Hospital of Yaoundé's emergency ward during the year 2007. Males comprised 71% of those injured, and the mean age of injured patients was 29 years (SD = 14.9). Nearly 60% of the injuries were due to road traffic accidents, 46% of which involved a pedestrian. Intentional injuries were the second most common mechanism of injury (22.5%), 55% of which involved unarmed assault. Patients injured in falls were more likely to be admitted to the hospital (p &lt; 0.001), whereas patients suffering intentional injuries and bites were less likely to be hospitalized (p &lt; 0.001). Males were significantly more likely to be admitted than females (p &lt; 0.001)DiscussionPatterns in terms of age, gender, and mechanism of injury are similar to reports from other countries from the same geographic region, but the magnitude of cases reported is high for a single institution in an African city the size of Yaoundé. As the burden of disease is predicted to increase dramatically in sub-Saharan Africa, immediate efforts in prevention and treatment in Cameroon are strongly warranted