Anatomic and MRI bases for medullary infarctions with patients' presentation

Objective: There is a low incidence of the medullary infarctions and sparse data about the vascular territories, as well as a correlation among the anatomic, magnetic resonance imaging (MRI) and neurologic signs. Materials and methods: Arteries of the 10 right and left sides of the brain stem were injected with India ink, fixed in formalin and microdissected. The enrolled 34 patients with medullary infarctions underwent a neurologic, MRI and Doppler examination. Results: Four types of the infarctions were distinguished according to the involved vascular territories. The isolated medial medullary infarctions (MMIs) were present in 14.7%. The complete MMIs comprised one bilateral infarction (2.9%), whilst the incomplete and partial MMIs were observed in 5.9% and 8.9%, respectively. The anterolateral infarctions (ALMIs) were very rare (2.9%). The complete and incomplete lateral infarctions (LMIs), noted in 35.3%, comprised 11.8% and 23.6%, respectively, that is, the anterior (5.9%), posterior (8.9%), deep (2.9%), and peripheral (5.9%). Dorsal ischemic lesions (DMIs) occurred in 11.8%, either as a complete (2.9%), or isolated lateral (5.9%) or medial infarctions (2.9%). The remaining ischemic regions belonged to various combined infarctions of the MMI, ALMI, LMI and DMI (35.3%). The infarctions most often affected the upper medulla (47.1%), middle (11.8%), or both (29.5%). Several motor and sensory signs were manifested following infarctions, including vestibular, cerebellar, ocular, sympathetic, respiratory and auditory symptoms. Conclusions: There was a good correlation among the vascular territories, MRI ischemia features, and neurologic findings regarding the medullary infarctions.Peer reviewe

Dynamic behaviour of a planetary reducer with double planet gears

Planetary reducers have a wide and significant application in modern machine industry. They are extremely compact and reliable, and they can achieve a wide range of gear ratios as well as high efficiency. Since they often operate in extremely changeable working conditions, such as often starting and stoping, it is both interesting and desirable to study their dynamic behaviour. This paper presents a dynamic model of a planetary reducer with double planet gears created by applying Lagrange's equations of the second kind. After a planetary gear reducer has been designed and a CAD model created, the dynamic model was made. Most of characteristic values needed for solution of the equations are taken from the CAD model. Due to their complexity, the equations are solved in math simulation software. A lot of interesting results concerning the dynamic behaviour of the model are obtained, which can be helpful in understanding the dynamic occurrences in the inside of a planetary gearbox. At the end of the paper, conclusions are drawn, and further research directions in this area are given

Dynamic Data Prioritization for Quality-of-Service Differentiation in Heterogeneous Wireless Sensor Networks

Abstract—In many applications of Wireless Sensor Networks (WSNs), heterogeneity is a common property in terms of different sensor types and different circumstances like node location, link quality, and local node density. In many applications, there are several different sensor types with entirely different Quality-of-Service (QoS) requirements. The requirements may also vary over time according to the application scenario and also due to network dynamics. Different requirements appeal different approaches while forwarding sensed data through a multi-hop communication network. This paper proposes a dynamic priority assignment strategy to be used for data routing in heterogeneous WSNs aiming to fairly propagate information according to its importance and requirements. To cope with heterogeneity and dynamics, nodes in the routing path dynamically compute priorities for individual data items according to the attached QoS requirements. We apply the proposed strategy for a healthcare monitoring application scenario which consists of an ambient network and several mobile clusters of nodes in the form of Wireless Body Area Networks (WBANs). The nodes have very different requirements and WBANs show a high mobility in the network with more stringent demands. The results show a large improvement in the achieved QoS for more demanding information. I

Fast Sink Placement for Gossip-based Wireless Sensor Networks

Abstract — In this paper we address the problem of sin

Efficiency analysis of new two-stage cycloid drive concept

© 2020 Published by Faculty of Engineering. A new generation of planetary speed reducers has a lot of various reducer concepts. One of the new type are cycloid drives. A massive appearance of cycloid drive reducers is related to the second half of the 20th century. This type of reducers represent a very interesting and attractive mechanical power transmission research field. The main reason for research interest is that cycloid reducers has a large potential in practice usage and they have very similar price related to conventional, planetary and other reducer types. Efficiency analysis of new two-stage cycloid drive concept is presented in this paper. The efficiency is determined based on losses due to friction in the bearing eccentric shaft surface, on the central gear rollers and the output rollers. New two-stage cycloid drive concept efficiency is done for 8 standard power values from 0.25kW to 15kW, with various input RPM and various transmission ratios. In order to evaluate the efficiency of new two-stage cycloid drive concept, the comparison with existing solutions in practice has been made. At the end of the paper are given conclusions with possible directions of research continuation

Configuring Multi-Objective Evolutionary Algorithms for Design-Space Exploration of Wireless Sensor Networks

Wireless sensor networks (WSNs) consist of numerous sensor nodes with several possible configurations for each node. As there are a lot of nodes in a typical WSN, each with its own set of configurations, the number of configurations for the network as a whole is huge and the design space is extremely large. The configuration of a WSN has a strong effect on the quality of services of running applications and the performance of the WSN. Multi-objective evolutionary algorithms (EAs) are well suited to explore the trade-offs in a WSN design space. However, an EA has many configuration parameters in itself. This paper presents several guidelines for configuring a multi-objective EA for design space exploration, given a specification of the WSN to be configured and a time budget available for analysis. We demonstrate the effectiveness of these guidelines on a specific type of WSN that uses a gossip strategy for disseminating data over the network

A Robust Protocol Stack for Multi-hop Wireless Body Area Networks with Transmit Power Adaptation ∗

Wireless Body Area Networks (WBANs) have characteristic properties that should be considered for designing a proper network architecture. Movement of on-body sensors, low quality and time-variant wireless links, and the demand for a reliable and fast data transmission at low energy cost are some challenging issues in WBANs. Using ultra low power wireless transceivers to reduce power consumption causes a limited transmission range. This implies that a multi-hop protocol is a promising design choice. This paper proposes a multi-hop protocol for human body health monitoring. The protocol is robust against frequent changes of the network topology due to posture changes, and variation of wireless link quality. A technique for adapting the transmit power of sensor nodes at run-time allows to optimize power consumption while ensuring a reliable outgoing link for every node in the network and avoiding network disconnection. Categories and Subject Descriptor