scholarly journals Loading Effect of Prosthetic Feet’s Anthropomorphicity on Transtibial Osseointegrated Implant

2021 ◽  
Vol 186 (Supplement_1) ◽  
pp. 681-687
Author(s):  
Mark Pitkin ◽  
Laurent Frossard
Keyword(s):  
Free Flow ◽  
Convex Shape ◽  
Bone Implant ◽  
Concave Shape ◽  
Early Loosening ◽  
Osseointegrated Implants ◽  
Osseointegrated Implant ◽  
Quantitative Characteristics ◽  
The Difference ◽  
The Moment

ABSTRACT Introduction Osseointegrated implants for direct skeletal attachment of transtibial prosthesis carry risks that are yet to be fully resolved, such as early loosening, mechanical failure of percutaneous and medullar parts of implant, periprosthetic issues, and infections. Underloading could lead to early loosening and infection. Overloading might compromise the bone–implant interface. Therefore, Goldilocks loading regimen applied by transtibial bone-anchored prostheses is critical for safe and efficient development of osseointegration around the implant during rehabilitation and beyond. We hypothesized that Goldilocks loading could be achieved when ambulating with a so-called anthropomorphic prosthetic ankle showing moment–angle relationship similar to a sound ankle. Materials and Methods Quantitative characteristics of the moment–angle curve of the sound ankle during dorsiflexion phase of a free-pace walking were extracted for 4 able-bodied participants (experiment 1). A slope of the moment–angle curve (stiffness) was calculated twice: for the first half and for the second half of the moment–angle curve. The difference of stiffnesses (those at the second half minus at the first half) was called the index of anthropomorphicity (IA). By definition, positive IA is associated with concave shape of the moment–angle curve, and the negative IA is associated with convex shape. In experiment 2, the same recordings and calculations were performed for 3 participants fitted with transtibial osseointegrated fixation during walking with their usual feet and the Free-Flow Foot (Ohio Willow Wood). The Free-Flow Foot was selected for its anthropomorphicity demonstrated in the previous studies with amputees using traditional socket attachment. Results The IA was 5.88 ± 0.93 for the able-bodied participants, indicating that the stiffness during the first part of the dorsiflexion phase was substantially fewer than during the second parts, as the calf muscles resisted to angulation in ankle substantially less than during the second part of dorsiflexion phase. For amputees fitted with Free-Flow Foot, IA was 2.68 ± 1.09 and −2.97 ± 2.37 for the same amputees fitted with their usual feet. Conclusions Indexes of anthropomorphicity, while of different magnitude, were positive in control able-bodied group and in the amputee group wearing Free-Flow Foot, which was qualitatively associated with concave shape of their moment–angle curves. The 3 usual feet worn by the participants were classified as nonanthropomorphic as their individual moment–angle curves were convex and the corresponding IAs were negative. Furthermore, this study showed that a foot with anthropomorphic characteristics tends to decrease maximal loads at the bone–implant interface as compared to the nonanthropomorphic feet and possibly may minimize the risks to compromise the integrity of this interface.

Transmission Error in Synchronous Belt With Resonance Under Installation Tension

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Masanori Kagotani ◽  
Hiroyuki Ueda
Keyword(s):  
Transmission Error ◽  
Speed Ratio ◽  
Experimental Transmission ◽  
Transmission Errors ◽  
Belt Drives ◽  
Concave Shape ◽  
Mode Vibration ◽  
The Difference ◽  
The Moment ◽  
Good Agreement

Synchronous belt drives generate resonance on the belt spans between the driving and driven pulleys when the transverse natural frequency of the belt, matches the meshing frequency of the belt tooth and the pulley tooth. The resonance of the belt spans affects the accuracy of rotation transmission. In the present study, the mechanisms generating the transmission error in synchronous belt drives under installation tension and a pulley speed ratio of 1:1 are investigated theoretically and experimentally for the case in which the belt spans generate first mode vibration due to resonance. In addition, the change in the shaft load caused by resonance is examined. The calculated and experimental transmission errors show good agreement, and so the validity of our analysis is confirmed. Transmission error is generated by the difference in displacement between the upper and lower belt spans due to the convex or concave shape, the difference in the amount of belt climbing at the beginning and end of meshing, and the generation of torque due to the moment of inertia on the driven side. The transmission error has a period of 1/2 of one pitch of the pulley, and the generated change in the shaft load, which is the sum of the displacement due to the convex or concave shape of the upper and lower spans and the sum of the belt climbing at the beginning and end of meshing, has a period of one pitch of the pulley.

scholarly journals Elastic Simulation of Joints with Particle-Based Fluid

2021 ◽  
Vol 11 (15) ◽  
pp. 6900
Author(s):  
Su-Kyung Sung ◽  
Sang-Won Han ◽  
Byeong-Seok Shin
Keyword(s):  
Principal Stress ◽  
Human Body ◽  
Yield Condition ◽  
Maximum Principal Stress ◽  
Human Motion ◽  
The Difference ◽  
The Moment ◽  
External Forces ◽  
Physical Changes ◽  
Elastic Simulation

Skinning, which is used in skeletal simulations to express the human body, has been weighted between bones to enable muscle-like motions. Weighting is not a form of calculating the pressure and density of muscle fibers in the human body. Therefore, it is not possible to express physical changes when external forces are applied. To express a similar behavior, an animator arbitrarily customizes the weight values. In this study, we apply the kernel and pressure-dependent density variations used in particle-based fluid simulations to skinning simulations. As a result, surface tension and elasticity between particles are applied to muscles, indicating realistic human motion. We also propose a tension yield condition that reflects Tresca’s yield condition, which can be easily approximated using the difference between the maximum and minimum values of the principal stress to simulate the tension limit of the muscle fiber. The density received by particles in the kernel is assumed to be the principal stress. The difference is calculated by approximating the moment of greatest force to the maximum principal stress and the moment of least force to the minimum principal stress. When the density of a particle increases beyond the yield condition, the object is no longer subjected to force. As a result, one can express realistic muscles.

Section plane selection influences the results of histomorphometric studies: the example of dental implants

2012 ◽  
Vol 57 (5) ◽  
Author(s):  
Sigmar Kopp ◽  
Mareike Warkentin ◽  
Ferenc Öri ◽  
Peter Ottl ◽  
Günther Kundt ◽  
...  
Keyword(s):  
Section Plane ◽  
Section Thickness ◽  
Implant Surface ◽  
Bone Implant ◽  
Osseointegrated Implants ◽  
Section Technique ◽  
Significant Difference ◽  
Bone To Implant Contact ◽  
The Mean ◽  
Dependent Samples

AbstractThis study was designed to determine and statistically analyze bone-to-implant contact (BIC) values for human specimens segmented in at least two different locations.Samples of human bone with fractured osseointegrated implants were obtained from six patients. Sections were prepared, dehydrated, and resin infiltrated. Undecalcified bone sections were produced using the thin-section technique according to Donath, ultimately obtaining a section thickness of approximately 20 μm. Fifteen specimens were available for histomorphometry. The bone sections were digitized and analyzed. The bone-to-metal contact (BMC) parameter was determined histomorphometrically. The BMC was returned in terms of the visibly bone-covered implant surfaces as a percentage of the total implant surface shown.The values obtained for the six implants were arranged as six maximum-distance pairs and tested for significance using the t-test for dependent samples. The mean difference in BIC was 11.69±9.79%. The two-sided test showed a significant difference (p=0.033).The accidental or deliberate choice of section plane for a bone-implant block has an influence on the BIC value. To make BIC values more comparable, a standardization of section planes is desirable.

Open access to scientific information: comparative study in DOAJ

2014 ◽  
Vol 35 (4/5) ◽  
pp. 364-374 ◽  
Author(s):  
Tereza Stoyanova Trencheva ◽  
Tania Yordanova Todorova
Keyword(s):  
Open Access ◽  
Comparative Study ◽  
Scientific Information ◽  
Comparative Approach ◽  
Content Type ◽  
Open Access Journals ◽  
Global Movement ◽  
The Difference ◽  
Important Position ◽  
The Moment

Purpose – The purpose of the paper is to provide a comparative retrospective analysis of Bulgarian, Turkish and Croatian Open Access (OA) journals added in Directory of Open Access journals (DOAJ) in the period 2002-2013. Design/methodology/approach – First of all, the study is focussed on brief review of definitions and descriptions of the OA as a global movement. In the study were analyzed the three main OA initiatives and was shown the difference between Golden Road and Green Road. Second of all, the authors used the comparative approach and made a comparative study of the OA journals in Bulgaria, Turkey and Croatia and present the evaluation results and findings. Findings – Qualitative and quantitative data for the study are collected by the DOAJ. The data are analyzed in terms of quantity and period, and the results are presented graphically and tabular and finally there are made major specific conclusions and recommendations. Originality/value – The paper shows that OA in the digital space has an important position in scientific research. There are many discussion issues related to the problems of OA, but overall study of OA to scientific information, and in particular comparative study of Bulgarian, Turkish and Croatian journals in the DOAJ does not exist at the moment.

Alkali-Modified Titanium Surface Stimulating Formation of Bone-Implant Interface

2007 ◽  
Vol 361-363 ◽  
pp. 749-752
Author(s):  
J. Strnad ◽  
Jan Macháček ◽  
Z. Strnad ◽  
C. Povýšil ◽  
Marie Strnadová
Keyword(s):  
Titanium Implant ◽  
Surface Characteristics ◽  
Healing Time ◽  
Machined Surface ◽  
Implant Surface ◽  
Bone Implant ◽  
Bone Response ◽  
Modified Surface ◽  
The Difference ◽  
Titanium Implant Surface

This study was carried out to assess the bone response to alkali-modified titanium implant surface (Bio surface), using histomorphometric investigation on an animal model. The mean net contribution of the Bio surface to the increase in bone implant contact (BIC) with reference to the turned, machined surface was evaluated at 7.94 % (BIC/week), within the first five weeks of healing. The contribution was expressed as the difference in the osseointegration rates ( BIC/'healing time) between the implants with alkali modified surface (Bio surface) and those with turned, machined surface. The surface characteristics that differed between the implant surfaces, i.e. surface morphology, specific surface area, contact angle, hydroxylation/hydration, may represent factors that influence the rate of osseointegration.

scholarly journals Against Declarativity

2020 ◽  
pp. 103-117
Author(s):  
Hans Kellner
Keyword(s):  
Literary Form ◽  
Literary Realism ◽  
Declarative Sentence ◽  
Romantic Literature ◽  
Realist Novel ◽  
Historical Discourse ◽  
The World ◽  
The Difference ◽  
The Moment ◽  
Declarative Statement

Historical discourse is a period phenomenon shaped by the rhetorical and genre understanding of the moment in which it became formalized and professionalized - that is, the second half of the nineteenth century. In the figurative arts, realist painting and its rival, photography, was dominant, and the literary form this notion of consciousness took was the realist novel. Literary realism devices replaced romantic literature devices, just as those latter devices had succeeded, but never replaced the eighteenth-century devices. Historical discourse and the very notion of proper history followed realism devices, mostly the single-lens photographic perspective, one viewer’s viewpoint. From a discourse perspective, this approach took the form of declarative, statement-making. Also, it is not to say that the declarative sentence which gives this term its name was rejected as the preferred way of making assertions about the world - far from it. Although a few self-conscious stylists (Derrida, for instance) work hard to avoid it, the declarative sentence is almost inevitable. Their readers work even harder. But just as narrativity encompasses a realm that extends far beyond narratives, so that narratives can proliferate in an environment that has, in a crucial sense, rejected grand narratives, so declarative statements will exist without entailing statement-making. The declarative act became the defining mark of professional history and remained its principal mode, just as it remains the predominant mode of literature and any number of other discourses. Indeed, this essay is written in the declarative rhetorical mode. However, literary modernism, philosophy, and a host of scientific developments have left this way of representing the world behind. Moreover, the same technological and intellectual changes that caused the modernist vision have, at the same time, created a different world to be depicted, a different sort of event to be represented historically. Not only the form but also the content have changed. The ethical and practical frustrations of representing such events have led to a theoretical challenge to the declarative form of knowing and to a challenge for the genre distinctions that constitute guild history: the idea of the past produced by academically professionalized individuals. For example, the difference between history and fiction - or rather, their respective relationship to truth and reality - has blurred. In contrast, history has adopted some of the modernist literature devices and the present’s practical demands.

scholarly journals Replacement depreciation and price regulation

2006 ◽  
Vol 17 (3) ◽  
pp. 10-20
Author(s):  
IJ Lambrechts
Keyword(s):  
The United States ◽  
Natural Monopoly ◽  
Price Regulation ◽  
Liquid Fuels ◽  
Economic Regulation ◽  
Tax Rates ◽  
Historical Cost ◽  
Investment Rates ◽  
The Difference ◽  
The Moment

Price regulation occurs quite commonly amongst natural monopolies which frequently include public utilities. In South Africa and in certain countries in Africa, there has recently been a revival of price regulation in certain industries and enterprises, where competition is limited or non-existent. Price regulation can be applied in a multitude of ways. Because of the importance of the price levels (historical and replacement) in the price setting exercise, the focus in this paper will be on the issue of depreciation to arrive at the final prices. The electricity utility industry was historically viewed as a highly mature and heavily regulated natural monopoly. In many parts of the world, electricity utilities have already been deregulated to a large extent and in the United States the process was preceded by a process of unbundling or ringfencing of the main divisions, i.e. generation and distribution. Even the network component of transmission, traditionally seen as natural monopolies, was deregulated to a large extent. The deregulation process, whether fully or partially, emphasised the requirement for a detailed explanation for a specific price level. The need for acceptable and transparent selling prices has, therefore, not disappeared. Regulatory pricing is consequently a vital component of pricing at this stage and in the restructured industry it will continue to play an important role because of a limited number of participants. In other sectors of the South African energy industry too, the deregulation process has either not started or has not been completed. Price regulation is presently and will in future be applicable to the liquid fuels industry, which includes the pipeline of Petronet as well as gas pipelines. Other industries which are being price regulated at the moment include water, medicine, telecommunication (fixed lines) and postal rates. Although the economic regulation for these industries may differ substantially, the principles applying to depreciation calculations would be similar. Replacement depreciation produces lower profit figures during periods of inflation. Quoted companies often oppose this system because of a lack of taxation recognition on income and the adverse effect on earnings per share. This paper covers the calculation of depreciation by price regulators where assets are not diversified (single assets). Shorter depreciation lifetimes based on historical cost result in an automatic provision for replacement depreciation. The extent of the provision would be a function of the difference between the actual and selected lifetimes, income tax rates, re-investment rates and the extent of the financial gearing ratio. Provision for replacement depreciation may be reduced significantly, if not reduced completely, by reducing depreciation lifetimes.

scholarly journals Russia – China: A Difficult Way to Strategic Partnership (To the 70th Anniversary of the Establishment of Diplomatic Relations)

2021 ◽  
pp. 231-245
Author(s):  
Sergey Biryukov ◽  
Keyword(s):  
Political Development ◽  
Complex Dynamics ◽  
World Order ◽  
Strategic Partnership ◽  
General Situation ◽  
Republic Of China ◽  
Bilateral Relations ◽  
Political Analysis ◽  
The Difference ◽  
The Moment

Introduction. The article is devoted to the features and historical evolution of the SovietChinese (later Russian-Chinese) relations from the moment of the proclamation of the People’s Republic of China in 1949 to the present. The analysis of the complex of factors that determined the complex dynamics of the relations between the two countries was carried out by the author of the article. It is shown that the SovietChinese (later – Russian-Chinese) relations developed from close alliance to alienation and confrontation – with reaching a level of strategic partnership in the second decade of the 21st century. Methods and materials. The authors seek a combination of general theoretical and special methods, focusing on the historical, sociocultural and political analysis. They are based on the analysis of periodicals, as well as using books, articles and materials of researchers on the problems of the political development of China and the USSR (Russia) and on the transformation of the nature of their bilateral relations. The author analyzes the current situation in the relations between the two countries, according to which the nature of the development of the general situation in international relations and the objective foreign policy interests of China and Russia encourage them to build and deepen bilateral partnership. Results. According to the author, many of the reasons that gave rise to a conflict of interests and confrontation between the two countries in previous years are exhausted today. At the same time, the joint participation of China and Russia in the formation and adoption of a new, more equitable and sustainable world order, in the settlement of conflicts and crises, in the arrangement of the Greater Eurasia space seems to the author justified and promising. Among the factors defining the nature of the Sino-Soviet relations the author identifies the relationship between the leaders of the two countries, the difference of geopolitical concepts and approaches, ideological disputes and differences in the views on strategy and prospects of the communist movement, the logic of the socio-political and socio-economic development in the context of modernization. The changing and contradictory correlation of these factors determined the development of the Soviet-Chinese (later Russian-Chinese) relations from a close alliance to mutual distancing and confrontation – with the subsequent entry into strategic partnership.

scholarly journals Sin, hendes og KorpusDK

2017 ◽  
Vol 25 (24) ◽  
Author(s):  
Sten Vikner ◽  
Katrine Rosendal Ehlers
Keyword(s):  
Language Change ◽  
The Difference ◽  
The Moment ◽  
New Situation ◽  
National Corpus

We will briefly present our analysis of the four reflexive/non-reflexive types of pronouns in Danish (jf. Vikner 1985 and Ehlers & Vikner 2017), which each have to comply with two conditions: One type of condition on elements with/without selv (i.e. sig/hende vs. sig selv/ hende selv), and another type of condition on elements with/without sig (i.e. sig/sig selv vs. hende/hende selv). We will then show how the difference between the reflexive possessive and the non-reflexive possessives (sin vs. hendes) fits into this system, and we will examine how compatible our predictions are with data from the Danish national corpus, KorpusDK. We assume that sin corresponds to both sig and sig selv, and we argue against the view that there is a difference between sin and sin egen which corresponds to the difference between sig and sig selv. Finally we will discuss the language change that seems to be taking place at the moment, from a situation where sin may only have a singular antecedent to the new situation where sin may also have a plural antecedent.

scholarly journals The bases of coordination development as the emergent quality of investment goods supply chain

2021 ◽  
Vol 69 (2) ◽  
pp. 146-152
Author(s):  
V. Falovych ◽  
N. Falovych ◽  
S. Semeniuk
Keyword(s):  
Supply Chain ◽  
Supply Chains ◽  
Production System ◽  
Current Time ◽  
Common Information ◽  
Working Together ◽  
The Difference ◽  
Reducing Costs ◽  
The Moment ◽  
Internal Stakeholders

In this paper article the authors point out the importance of actions aimed at reducing waste, increasing productivity and reducing costs in the supply chain, which will ensure the development of coordination as an emergent function of the supply chain and contribute to the formation of responsibility to internal stakeholders; they also note the difference between logistics and supply chain management (SCM), which, primarily, is that logistics usually refers to the activities taking place within one organization, and supply chains belong to the network of companies working together and coordinate their actions to product supply to the market. The authors point out that the development of partnership in supply chains makes it possible to perform collaborative planning on a common information base, collective management of stocks, risks and all this provides reasons to coordinate activities in the supply chain, i.e. the dependence of «exit» on «entry» becomes homogeneous. Particular attention is paid to the ways of improvement the supply chain functioning, which is proposed to carry out at three levels. The highest level includes the processes taking place throughout the supply chain, and concerns the relationship between all participants [10]. At the operational level (the second level), the constraint theory recommends to use the LPS (Logical Product Structure) method. At the current actions level (the third level) TOC proposes to use the concept of management of the production system DBR (English: Drum – Buffer – Rope), the application of which enables to increase the capacity of the production system. In order to identify the area of necessary changes, the authors propose to build a detailed flowchart of processes, actions and functions from receiving the order from the customer (either external or internal) up to the moment of order fulfilment and delivery to the customer, which makes it possible to analyze sequentially the system operation in the current time and identify the areas of necessary changes, as well as to increase the level of meeting the customer needs, ensuring the efficiency of material and information flows, strengthening the manufacturer status in the market.

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