Transformation in orbital reconstruction

The orbits provide support and protection for several soft-tissue structures associated with vision. A fracture of the orbital walls may affect globe position and vision, and surgical intervention may be indicated to restore the bony anatomy and alleviate sequalae. Reconstruction is challenging due to the orbit’s complex shape and limited overview. Computer-assisted surgery (CAS) minimizes surgical risk and optimizes the reconstruction result. An overview of current CAS approaches and the results of validation studies that show its beneficial effect is provided in the Introduction Part. The aim of this thesis is to improve the current CAS workflow. The first innovation is the introduction of the Orbital Implant Positioning Frame (OIPF), which provides three-dimensional (3D) assessment of rotation and translation parameters of implant position for postoperative evaluation. The Navigation Chapters describe the OIPF’s use intraoperatively. Real-time, intuitive implant positioning feedback may be provided through the combination of the OIPF, an insertion instrument (TOP) and surgical navigation. This feedback improves implant positioning and reduces operating time. The use of the instrument without navigation also proves to have a beneficial effect on positioning accuracy. In the Registration Chapters, two novel registration workflows for craniomaxillofacial surgical navigation are introduced: virtual splint registration and registration-free navigation. The accuracy of virtual splint registration proved comparable to bone-anchored fiducial, while invasiveness and radiation exposure were reduced. The results for registration-free navigation are contradictory: it was the most accurate method with electromagnetic tracking, but the least accurate with optical tracking. The Revision Chapters concern secondary posttraumatic reconstruction with patient-specific implants (PSIs). In a cohort study, design options for PSIs are provided and the clinical results evaluated. Globe position significantly improved and double vision significantly reduced after secondary PSI reconstruction. A novel surgical workflow with the use of PSIs, specifically for secondary orbitozygomatic reconstruction, is described in the final Chapter. This ‘Orbit First’ method allows accurate reconstruction of the orbit independent of the obtained zygoma position

Correlation between the reliability of HEMT devices and that of a combined oscillator-amplifier

We evaluate an oscillator-amplifier MMIC submitted to high-temperature operating life time tests. To relate adequately these results with individual components’ results, it is important to realise that failure mechanisms in non-linear MMICs are governed by the maximally instantaneous voltages/currents and hence that comparisons should be conducted at equal instantaneous conditions

Carboplatin binding to a model protein in non-NaCl conditions to eliminate partial conversion to cisplatin, and the use of different criteria to choose the resolution limit

Hen egg white lysozyme (HEWL) co-crystallisation conditions of carboplatin without sodium chloride (NaCl) have been utilised to eliminate partial conversion of carboplatin to cisplatin observed previously. Tetragonal HEWL crystals were successfully obtained in 65% MPD with 0.1M citric acid buffer at pH 4.0 including DMSO. The X-ray diffraction data resolution to be used for the model refinement was reviewed using several topical criteria together. The CC1/2 criterion implemented in XDS led to data being significant to 2.0{\AA}, compared to the data only being able to be processed to 3.0{\AA} using the Bruker software package (SAINT). Then using paired protein model refinements and DPI values based on the FreeR value, the resolution limit was fine tuned to be 2.3{\AA}. Interestingly this was compared with results from the EVAL software package which gave a resolution limit of 2.2{\AA} solely using crossing 2, but 2.8{\AA} based on the Rmerge values (60%). The structural results showed that carboplatin bound to only the N{\delta} binding site of His-15 one week after crystal growth, whereas five weeks after crystal growth, two molecules of carboplatin are bound to the His-15 residue. In summary several new results have emerged: - firstly non-NaCl conditions showed a carboplatin molecule bound to His-15 of HEWL; secondly binding of one molecule of carboplatin was seen after one week of crystal growth and two molecules were bound after five weeks of crystal growth; and thirdly the use of several criteria to determine the diffraction resolution limit led to the successful use of data to higher resolution.Comment: 14 pages; submitted to Acta Cryst D Biological Crystallography reference number tz504

The optimisation of water quality monitoring schemes

The monitoring of water quality is necessary to ensure that the health of catchments is maintained. Water quality monitoring is often undertaken by government agencies to identify trends, assess management strategies and the state of catchments. Many water quality studies attempt to identify the quantity and timing of nutrients exported from a catchment. The accuracy of the monitoring scheme is largely controlled by the sampling scheme. Financial constraints are one of the limiting factors and under this constraint, sampling schemes often combine limited sample sizes with estimation methods. The use of statistical methods allows catchment managers to improve the information on expensive water quality properties based on the relationship with low cost properties. Many water quality monitoring programs have access to limited historical data, therefore there is a requirement for methods which can use this limited data to improve water quality monitoring schemes. This thesis aims at examining the effect of event-based sampling, using historical data to improve sample designs and the use of model-based geostatistical methods to improve the quantification of nutrient exports

Positive Psychological Wellbeing Is Required for Online Self-Help Acceptance and Commitment Therapy for Chronic Pain to be Effective

The web-based delivery of psychosocial interventions is a promising treatment modality for people suffering from chronic pain, and other forms of physical and mental illness. Despite the promising findings of first studies, patients may vary in the benefits they draw from self-managing a full-blown web-based psychosocial treatment. We lack knowledge on moderators and predictors of change during web-based interventions that explain for whom web-based interventions are especially (in)effective. In this study, we primarily explored for which chronic pain patients web-based Acceptance and Commitment Therapy (ACT) was (in)effective during a large three-armed randomized controlled trial. Besides standard demographic, physical and psychosocial factors we focused on positive mental health. Data from 238 heterogeneously diagnosed chronic pain sufferers from the general Dutch population following either web-based ACT (n = 82), or one of two control conditions [web-based Expressive Writing (EW; n = 79) and Waiting List (WL; n = 77)] were analysed. ACT and EW both consisted of nine modules and lasted nine to 12 weeks. Exploratory linear regression analyses were performed using the PROCESS macro in SPSS. Pain interference at 3-month follow-up was predicted from baseline moderator (characteristics that influence the outcome of specific treatments in comparison to other treatments) and predictor (characteristics that influence outcome regardless of treatment) variables. The results showed that none of the demographic or physical characteristics moderated ACT treatment changes compared to both control conditions. The only significant moderator of change compared to both EW and WL was baseline psychological wellbeing, and pain intensity was a moderator of change compared to EW. Furthermore, higher pain interference, depression and anxiety, and also lower levels of emotional well-being predicted higher pain interference in daily life 6 months later. These results suggest that web-based self-help ACT may not be allocated to chronic pain sufferers experiencing low levels of mental resilience resources such as self-acceptance, goals in life, and environmental mastery. Other subgroups are identified that potentially need specific tailoring of (web-based) ACT. Emotional and psychological wellbeing should receive much more attention in subsequent studies on chronic pain and illness

Impregnation of bone chips with antibiotics and storage of antibiotics at different temperatures: an in vitro study

<p>Abstract</p> <p>Background</p> <p>Allograft bone used in joint replacement surgery can additionally serve as a carrier for antibiotics and serve as a prophylaxis against infections. However, <it>in vitro </it>dose-response curves for bone chips impregnated with different kinds of antibiotics are not available. In addition, while it would be desirable to add the antibiotics to allograft bone chips before these are stored in a bone bank, the effects of different storage temperatures on antibiotics are unknown.</p> <p>Methods</p> <p>Five different antibiotics (cefazolin, clindamycin, linezolid, oxacillin, vancomycin) were stored, both as pills and as solutions, at -80°C, -20°C, 4°C, 20°C and 37°C; in addition, bone chips impregnated with cefazolin and vancomycin were stored at -80°C and -20°C. After 1 month, 6 months and 1 year, the activity of the antibiotics against <it>Staphylococcus epidermidis </it>was measured using an inoculated agar. The diameter of the <it>S. epidermidis</it>-free zone was taken as a measure of antibiotic activity.</p> <p>In a separate experiment, <it>in vitro </it>dose-response curves were established for bone chips impregnated with cefazolin and vancomycin solutions at five different concentrations.</p> <p>Finally, the maximum absorbed amounts of cefazolin and vancomycin were established by impregnating 1 g of bone chips with 5 ml of antibiotic solution.</p> <p>Results</p> <p>A decrease of the <it>S. epidermidis</it>-free zone was seen with oxacillin and cefazolin solutions stored at 37°C for 1 month, with vancomycin stored at 37°C for 6 months and with cefazolin and oxacillin solutions stored at 20°C for 6 months. The activity of the other antibiotic solutions, pills and impregnated bone chips was not affected by storage. The <it>in vitro </it>dose-response curves show that the free-zone diameter increases logarithmically with antibiotic concentration. The absorbed antibiotic amount of one gram bone chips was determined.</p> <p>Conclusions</p> <p>Storage of antibiotics in frozen form or storage of antibiotic pills at temperatures up to 37°C for 12 months does not affect their activity. However, storage of antibiotic solutions at temperatures above 20°C does affect the activity of some of the antibiotics investigated. The <it>in vitro </it>dose-response curve can be used to determine the optimal concentration(s) for local application. It provides the opportunity to determine the antibiotic content of bone chips, and thus the amount of antibiotics available locally after application.</p

Histological evaluation of allograft incorporation after cemented and non-cemented hip arthroplasty in the goat

No abstract

Impaction grafting and cemented acetabular revision

No abstract