Allograft intervertebral disc transplantation in the sheep:an assessment of the potential for allograft disc replacement

STUDY DESIGN: An allograft intervertebral disc transplantation procedure was carried out in a total of twenty 2-year old Merino wethers. OBJECTIVE: The aims of this study were to test the viability and integrity of an intervertebral disc following transplantation from one animal to another, and to assess the safety and reliability of the transplant procedure. SUMMARY OF BACKGROUND DATA: Because of the unpredictable clinical results reported in the literature, the role of spinal fusion for chronic disabling back pain associated with degeneration of the intervertebral disc remains controversial. The challenge for the future will be to develop other forms ,,. of spinal stabilisation procedures that may produce better and more reliable results than spinal arthrodesis. Recently, prosthetic intervertebral disc replacement has been developed and trialled in a number of centres but concerns exist regarding the likely long term effects of these implants, particularly those related to loosening, wear particles and infection. Allograft intervertebral disc transplantation, however, may be able to overcome the inherent limitations of artificial disc replacement and may also be able to better withstand the normal physiological demands and restore the function of the motion segment. If successful, allograft disc replacement may become, in theory, an appealing alternative to fusion surgery. METHODS: The study was carried out in a total of twenty 2-year old Merino wethers. uni ts were harvested from which were sacrificed Donor intervertebral an additional eight within four hours disc sheep of transplantation. The disc units were harvested using an oscillating saw and comprised the entire intervertebral disc together with a thin plate of adjacent vertebral bone. A single intervertebral disc unit was inserted into the recipient lumbar spine via an antero-lateral approach under a general anaesthetic and with strict aseptic conditions. Attempted stabilisation of the allograft employing small screws inserted obliquely into the adjacent vertebral bodies proved to be unsatisfactory in the first group of sheep. Internal fixation of adjacent vertebrae with a lateral plate and screws was subsequently used in an attempt to prevent ventral displacement of the disc unit.Thesis (M.S.)--University of Adelaide, Dept. of Orthopaedics and Trauma, 199

The Impact of API Change- and Fault-Proneness on the User Ratings of Android Apps

The mobile apps market is one of the fastest growing areas in the information technology. In digging their market share, developers must pay attention to building robust and reliable apps. In fact, users easily get frustrated by repeated failures, crashes, and other bugs; hence, they abandon some apps in favor of their competition. In this paper we investigate how the fault-and change-proneness of APIs used by Android apps relates to their success estimated as the average rating provided by the users to those apps. First, in a study conducted on 5,848 (free) apps, we analyzed how the ratings that an app had received correlated with the fault-and change-proneness of the APIs such app relied upon. After that, we surveyed 45 professional Android developers to assess (i) to what extent developers experienced problems when using APIs, and (ii) how much they felt these problems could be the cause for unfavorable user ratings. The results of our studies indicate that apps having high user ratings use APIs that are less fault-and change-prone than the APIs used by low rated apps. Also, most of the interviewed Android developers observed, in their development experience, a direct relationship between problems experienced with the adopted APIs and the users\u27 ratings that their apps received

Transverse strength of railway tracks : Part 1. planning and experimental setup

© Gruppo Italiano Frattura 2014. This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: https://creativecommons.org/licenses/by/4.0/Several studies have been carried out until now by various Research Agencies and Railway Administrations to quantify the effects of the track-bed geometrical characteristics on the transverse strength of the track. Unfortunately, not all the possible scenarios in terms of track components, track-bed cross profile, operating conditions etc. have been investigated and not all the relevant variables have been directly measured. Therefore data available from the literature have different degrees of reliability. With the aim of enlarging the knowledge on the track stability and covering much of the possible relevant scenarios, an experimental research program has been developed in the framework of a cooperation between RFI, Italcertifer and DII. In order to perform the investigation under quite general conditions and to reduce the experimentation costs, n. 28 significant scenarios have been identified and reproduced on as many independent track segments. By applying on each track segment a transversal load, the strength of the ballast-sleeper interface has been determined. The results relative to the first four scenarios are presented in terms of applied load vs. lateral track displacement diagrams and in more synthetic numerical tables.Peer reviewe

Transverse strength of railway tracks : Part 3. Multiple scenarios test field

© Gruppo Italiano Frattura 2014. This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: https://creativecommons.org/licenses/by/4.0/In the present paper the design and construction choices of a test field for the ballast lateral resistance measurement, in order to produce data useful for the development of a numerical model able to simulate the service critical conditions of a continuous welded rail track, are described. Some construction details described herein allow to better understand the methodological approach followed in the design of experiments, the tests management philosophy as well as of the accuracy achieved in their implementation.Peer reviewe

Transverse strength of railway tracks: part 1. Planning and experimental setup

Several studies have been carried out until now by various Research Agencies and Railway Administrations to quantify the effects of the track-bed geometrical characteristics on the transverse strength of the track. Unfortunately, not all the possible scenarios in terms of track components, track-bed cross profile, operating conditions etc. have been investigated and not all the relevant variables have been directly measured.Therefore data available from the literature have different degrees of reliability. With the aim of enlarging the knowledge on the track stability and covering much of the possible relevant scenarios, an experimental research program has been developed in the framework of a cooperation between RFI, Italcertifer and DII.In order to perform the investigation under quite general conditions and to reduce the experimentation costs, n. 28 significant scenarios have been identified and reproduced on as many independent track segments. Byapplying on each track segment a transversal load, the strength of the ballast-sleeper interface has beendetermined. The results relative to the first four scenarios are presented in terms of applied load vs. lateral track displacement diagrams and in more synthetic numerical tables

On the ballast–sleeper interaction in the longitudinal and lateral directions

In service, railway tracks must withstand transverse and longitudinal forces arising from running vehicles and thermal loads. The mechanical design adopting any of the track models available in the technical literature requires that the strength of the track is fully characterized. In this paper, the results of an experimental research activity on the sleeper-ballast resistance along the lateral and the longitudinal directions are reported and discussed. In particular, the work is aimed at identifying the strength contributions offered by the base, the ballast between the sleepers, and the ballast shoulder to the global resistance of the track in the horizontal plane. These latter quantities were experimentally determined by means of an ad hoc system designed by the authors. Field tests were carried out on a series of track sections that were built to simulate scenarios in which the ballast was removed from the crib and/or the shoulder. The results of this study indicate that, as far as the scenarios here investigated are concerned, the strength percent contributions from the crib, the sleeper base and the shoulder are respectively equal to about 50%, 25%, and 25% in the lateral direction, and 60%, 30%, and 10% in the longitudinal one. Moreover, the comparison of the acquired data with literature results reveals that a detailed knowledge both of the testing conditions and the activated ballast failure mechanisms are needed in order to correctly use test data for design purpose

API Change and Fault Proneness: A Threat to the Success of Android Apps

During the recent years, the market of mobile software applications (apps) has maintained an impressive upward trajectory. Many small and large software development companies invest considerable resources to target available opportunities. As of today, the markets for such devices feature over 850K+ apps for Android and 900K+ for iOS. Availability, cost, functionality, and usability are just some factors that determine the success or lack of success for a given app. Among the other factors, reliability is an important criteria: users easily get frustrated by repeated failures, crashes, and other bugs; hence, abandoning some apps in favor of others. This paper reports a study analyzing how the fault- and change-proneness of APIs used by 7,097 (free) Android apps relates to applications ’ lack of success, estimated from user ratings. Results of this study provide important insights into a crucial issue: making heavy use of fault- and change-prone APIs can negatively impact these apps success. Categories and Subject Descriptor