13 research outputs found
Metal-on-metal hip arthroplasty:physical activity monitoring, outcomes and systemic toxicity
Get PDFThe relationship between objectively measured physical activity and blood metal concentrations in patients with MoM hip replacements was investigated in two different cohort studies. The average number of steps per day of the patients in these studies was comparable to healthy subjects of the same age. This indicates a normal activity level of the patient population in this study. There was a wide variation in the cobalt concentrations of the patients. A significant correlation was found between cobalt concentrations and various parameters of daily physical activity (number of sit-to-stand transfers and high-intensity peaks). No statistically significant relationships were found between cobalt concentrations and daily time spent walking, total number of steps and total percentage of time physically active. It seems that quantitative general daily activities, such as normal walking, do not influence cobalt concentrations, or do so only slightly. Especially qualitative aspects of the activities (high intensity, fast walking, many sit-to-stand transfers) seem to influence cobalt concentrations. It also compared the activity found in patients with MoM prostheses with patients with conventional prostheses. The groups were similar in terms of gender, age at surgery, follow-up since surgery and BMI. Contrary to expectations, patients with an HRA were not found to be more physically active. Patients show similar physical activities independent of the type of implant. These patients were also asked to complete questionnaires (PROMs), asking about their physical activity. It turned out that these questionnaires hardly correspond to the objectively measured physical activity.Using the Dutch National Register of Orthopaedic Implants (LROI), there was an investigation as to whether the replacement (revision) of a MoM prosthesis was comparable to the revision of a non-MoM prosthesis in terms of outcomes. Revision surgery for failed MoM hip replacements has a high risk of revisions, but this is comparable to the outcome of revisions for non-MoM hip replacements. Partial revision of the stem and MoM arthrodesis after the first revision show poor results in the surgical treatment of a failed MoM hip prosthesis.After the implantation of a MoM hip prosthesis, patients have seen an increase in metal concentrations in the blood. Cobalt intoxication is an increasingly described complication with potentially severe symptoms; this is called 'Prosthetic Hip-Associated Cobalt Toxicity (PHACT)'. A literature review was carried out on the subject. The origin of most symptoms was in the sensory system (senses), followed by the cardiovascular (heart-vessel) and neurological (brain/nerves) systems. The threshold value of cobalt, at which symptoms start to appear, could not be determined due to the wide distribution of the concentrations described. In addition to this literature review, we asked patients whether they experienced any complaints. The results showed that oculo-vestibular (eye, hearing, balance organ) symptoms were more frequent in the groups with high cobalt concentration and with increasing prevalence for higher thresholds. This is an indication of the correlation between cobalt concentration and symptom prevalence.<br/
Monthly swelling of the knee - Case report and review of the literature
No full textIntroduction: We report a 17-year old with monthly swelling of her knee. The complaints are associated with the menstrual cycle. After physical examination, radiographs, MRI and an arthroscopy with biopsies, a diagnosis of intra-articular endometriosis and menstrual arthritis was made.Discussion: Both an intra-articular manifestation of endometriosis and menstrual arthritis are very rare diagnoses. Extraperitoneal lesions of endometriosis are rare and the mechanism for spreading outside the retroperitoneal space is unknown. A similar situation exists for menstrual arthritis, it is thought that cytokines, which are produced as a reaction to retrograde menstruation, are the trigger for menstrual arthritis. A review of literature is given.Conclusion: A monthly recurrent, painful swelling of a joint, can and should give rise to thorough investigation. Differential diagnostic one should think of intra-articular manifestation of endometriosis and menstrual arthritis. We give a proposal for treatment.</p
Consensus-less Security: A truly scalable distributed ledger
No full textDistributed ledger technology was expected to spark a technical revolution similar to the internet revolution. After the release of Bitcoin in 2008, many developments have significantly increased the performance of distributed ledger technology. Nevertheless, the first truly scalable ledger has yet to be deployed. All of them have issues with scaling in either the throughput, the number of nodes which can validate transaction or both. The concept behind a distributed ledger is that the integrity of the ledger is a shared responsibility. However, as soon as new technology emerges, also misuse surfaces, especially if there are financial gains involved. The general solution, to prevent such abuse, in distributed ledger technology is through the use of global consensus. If the majority of a network is honest, and we require a majority vote on the validity of a transaction, no malicious transactions will succeed. A downside of requiring a majority vote is that every node eligible to vote must contain full knowledge on all previous transactions. This work argues that the requirement of global consensus is a major limiting factor when it comes to the scalability of current ledgers. The goal of this work is to design a scalable distributed ledger whose security does not rely on global consensus. It proposes a novel algorithm that guarantees security, even under adversarial attack, by up to a third of the network exhibiting byzantine behavior. It does so using Trustchain, a pair-wise ledger designed by the Delft University of Technology, and `Fair Witness Selection Protocol', a newly designed publicly verifiable witness selection algorithm with an indicated message and communication complexity of . A mathematical lower-bound is given on the security level of the algorithm, and the security is reduced to the security of the underlying hash function. Several experiments were executed on the DAS-5 supercomputer to confirm the scalability of this work. These experiments show that the throughput of the network scales linearly, and has been tested up to 2500 nodes (simultaneously acting as validators and clients). To the best of the author's knowledge, it is the only ledger that has no theoretical limits on the number of clients, number of validators, or throughput. A peak-throughput of 7025 tx/s has been observed at a network size of 280 nodes. Furthermore, the total transaction time remained roughly constant at about 15 milliseconds regardless of the network size
A method for predicting spatial distribution of evaporation using simple meteorological data
No full textA methodology for predicting the spatial distribution of evaporation rate in a catchment based on the Penman-Monteith (P-M) equation is suggested. The prediction is resolved into the four basic controlling components: net radiation, aerodynamic resistance, saturation state of the atmosphere and canopy resistance. Computer models of each component were then devised based on digital terrain analysis and tested for validity against observed data for clear sky conditions. Predicted values of potential evaporation compared favourably with those calculated from the observed data with a model efficiency of 0.80 and actual evaporation values were calculated based on this success. The digital terrain analysis enabled interpolation of the P-M calculations throughout the catchment allowing prediction of the spatial distribution of evaporation. -from Author
Neurology in Metal-on-Metal Hip Arthroplasty - a Case of Suspected Prosthetic Hip-Associated Cobalt Toxicity
No full textMetal-on-Metal hip arthroplasty was a frequently performed procedure, until concerns raised. Metal ion concentrations raise after the placement of a MoM prosthesis. This might lead to toxic concentrations of cobalt ions which might result in cardiotoxicity, thyroid toxicity and/or neuro-ocular toxicity. It is possible that raised cobalt and chromium concentrations have a role in the development of neurodegenerative diseases like Creutzfeldt-Jakob. We describe a patient with a MoM prosthesis who developed neurological symptoms were we thought of cobalt intoxication but turned out to be Creutzfeldt-Jakob disease
Neurology in metal-on-metal hip arthroplasty a case of suspected prosthetic hip-associated cobalt toxicity
No full textMetal-on-Metal hip arthroplasty was a frequently performed procedure, until concerns raised. Metal ion concentrations raise after the placement of a MoM prosthesis. This might lead to toxic concentrations of cobalt ions which might result in cardiotoxicity, thyroid toxicity and/or neuro-ocular toxicity. It is possible that raised cobalt and chromium concentrations have a role in the development of neurodegenerative diseases like Creutzfeldt-Jakob. We describe a patient with a MoM prosthesis who developed neurological symptoms were we thought of cobalt intoxication but turned out to be Creutzfeldt-Jakob disease
Solar Powered Drones: PV Generator
No full textDrones are unmanned flying vehicles, which can be used for a broad spectrum of different applications. One of these applications is the generation of albedo maps. However, it could take some time to map an area. Therefore problems can occur the with respect to its flight range, which typically lies between 20 to 45 km for mini UAVs. The goal of this project is to design a PV powered drone that can create an albedo map of an area that is equal or bigger than the area of the Technical University of Delft. This is done by choosing and modelling an UAV system, where after choosing and modelling a PV generator system. Based on these models, power dynamics and flight ranges are calculated. The usability is tested for different weather conditions of Delft. The UAV system with PV generator without protection layers has a flying range between 129 and 250 km, depending in the irradiance. For the same system with protective layers, the flight range varies from 117 to 208 km. the total flight range that is needed to map the area of the TU Delft is 48.75 km. Therefore, there can be concluded that in both cases our goal has been achieved. When these results are compared to the weather conditions of the TU Delft, it can be concluded that on average a UAV system with PV generator will increase the flight range. However, when comparing this system to a system with additional batteries, the latter will achieve better results. In order to make sure that the PV generator system will guarantee a longer flight range, limitations regarding times, periods and places are made. Keep in mind that since these results are solely based on models of systems, it's best to create and test the physical system to validate the found results. This thesis is written in context of the Bachelor Graduation Project. We would like to express our gratitude to our daily supervisor Patrizio Manganiello and our supervisors Andres Calcabrini and Mirco Muttillo for their guidance during the project. Finally we would like to thank our colleagues: Laura Muntenaar and Sjoerd de Groot of the control algorithm project and Jetse Spijkstra and Martin Geertjes of the power electronics project for an enjoyable and productive collaboration. J. Koning & R. van der Hoorn Delft, June 2020</p
Spinal Surgeons’ Opinions on Pre- and Postoperative Rehabilitation in Patients Undergoing Lumbar Spinal Fusion Surgery: A Survey-Based Study in the Netherlands and Sweden
Get PDFStudy Design. A cross-sectional survey in the Netherlands and Sweden. Objective. To investigate Dutch and Swedish spinal surgeons' opinions on spinal fusion pre- and postoperative rehabilitation. Summary of Background Data. Lumbar spinal fusion surgery is increasingly provided in patients with chronic low back pain. No guidelines however exist for pre-and postoperative rehabilitation and it is unknown what opinions spinal surgeons currently have about pre-and postoperative rehabilitation. Methods. A survey was circulated to Dutch and Swedish spinal surgeons. Reminders were sent after 4 and 8/9 weeks. Data of completed questionnaires of orthopedic-and neurosurgeons currently performing lumbar spinal fusion were included for analysis. Analysis comprised a range of descriptive summaries (numerical, graphical, and tabular). Results. Surveys of 34 Dutch and 48 Swedish surgeons were analyzed. Surgeons provided preoperative information on postoperative mobilization. Spinal fusion techniques varied, but technique did not influence postoperative treatment. Swedish surgeons recommended slightly faster mobilization than Dutch (direct vs. 1-day postoperative), and more activities the first day (sitting, standing, walking). Stair climbing was the most reported discharge criterion; however, time point to start varied. More Swedish surgeons referred to postoperative physiotherapy than Dutch (88% vs. 44%). Time-point to start home activities varied from 1 week to more than 6 months. Pain increase was allowed for less than 24 hours (The Netherlands 81%, Sweden 92%). Conclusion. Findings reflect variability in lumbar spinal fusion rehabilitation in two European countries, especially in postoperative phase. The study proposes many new research topics and acts as starting point for future research valuable for the spinal community
Developing a critical theory of child abuse : a discussion of the nature of child abuse as a manifestation of the social order
Get PDFThis thesis is an exploration into the nature and the prevalence of
child abuse. It incorporates in this investigation how children
understand abuse, and how the child may reject or oppose it. Its
origins lie in the experiences and observations I made as a local
authority social worker where children were silent, where child
abuse was seen as an event, a distinct moment within family life,
and with apparently little recognition of its relationship with the
social order. Arising from this observation, I consider how the
care of children may be a manifestation of the social order. This
thesis is therefore also a critique of the present theory and
practice of working within the field of childcare.
The premise taken here is that in order to understand abuse, there
must be an account of the individual's sense of being, as this
relates to wider issues of the political economy. Thus this
investigation uses the perspective of critical theory, since
critical theory can incorporate an analysis of both structure and
the experiential. It enables the researcher to shift perspective
and to focus on different levels and aspects of being.
Therefore, since child abuse is situated within the family, an
analysis based on the perspectives of critical theory is used to
examine family relationships. This includes an examination of the
relationships between parents, as well as of those between them and
the child. Three different facets of family life are explored:
that of gender construction from the viewpoint of feminist
psychoanalysis; the relationship between the social order and
interpersonal behaviour from the perspective of Marx and radical
feminism; and parental authority, drawing on the work of Laing.
Derived from this exploration, the key concepts of patriarchy,
alienation and mystification inform the direction of the empirical
investigation.
The empirical investigation, using firstly autobiographies of
childhood and then direct interviews with children, explores
further these concepts'. The autobiographies are used as a way of
sensitising oneself to the issues for the child, and as a means of
categorising experiences for the subsequent interviews with
children. From this reading, an alternative understanding of child
abuse is developed, one which differs from the narrow definition
used by organisations. Hence abuse can be seen as the experience
of hurt and pain, either emotional or physical, and which takes
place in a relationship based on the parental domination, control
and exploitation of the child. This understanding of abuse
situates the subjective experience within an interpersonal dynamic
of power and subordination.
Using this definition in analysing the interviews with children, it
was apparent that all children expedrience a form of abuse to some
degree. Abuse is not, therefore, the property of a small number of deviant families. Additionally it is argued that children are
silenced and rendered powerless within the family by three
mechanisms: firstly by the 'privacy control mechanism', secondly by
the 'ideology of paternalism', and thirdly by mystification. These
can be interpreted as also reinforcing the social order, since this
also depends for its maintenance on domination, powerlessness, and
mystification of the mechanisms of control.
The thesis concludes with a number of proposals for further
exploring these concepts in terms of developing sociological theory
and social work practice. The report on the death of Jasmine
Beckford is subjected to an alternative analysis, and derived from
this critique, ways of confronting violence, mystification and
privacy are discussed. Finally the thesis stresses the importance
of understanding child abuse as a personal as well as a social
phenomenon, and that it has ultimately, a political significance
Socioeconomic status affects patient-reported outcome measures in total hip and knee arthroplasty:A retrospective Dutch registry study
No full textBackground: To determine the association between socioeconomic status (SES) and patient-reported outcome measures in a Dutch cohort who have undergone total hip arthroplasty (THA) or total knee arthroplasty (TKA). Methods: A retrospective national registry study of all patients who underwent primary THA or TKA between 2014 and 2020 in the Netherlands was performed. Linear mixed effects regression models were used to assess the association between SES and patient-reported outcome measures for THA and TKA patients separately. The following measures were collected: numeric rating scale for pain, Oxford Hip/Knee Score, Hip/Knee disability and Osteoarthritis Outcome Score, and the EuroQol 5-Dimensions questionnaire. Sex, age, body mass index, American Society of Anesthesiologists classification, Charnley classification, and smoking status were considered as covariates in the models. Results: THA patients (n = 97,443) were on average 70 years old with a body mass index of 27.4 kg/m 2, and TKA patients (n = 78,811) were on average 69 years old with a body mass index of 29.7 kg/m 2. Preoperatively, patients with a lower SES undergoing THA or TKA reported more severe symptoms and lower health-related quality of life. At 1-year follow-up, they also reported lower scores and less improvement over time compared to patients with a higher SES. Conclusions: Patients with lower SES report worse symptoms when admitted for surgery and less improvement after surgery. Future research must address potentially mediating factors of the association between SES and symptom reporting such as access to surgery and rehabilitation, subjectivity in reporting, and patient expectation for THA and TKA outcomes.</p
