440 research outputs found
Minimum Participation Rules with Heterogeneous Countries
Almost all international environmental agreements include a minimum participation rule. Under such a rule an agreement becomes legally binding if and only if a certain threshold in terms of membership or contribution is reached. We analyze a cartel game with open membership and heterogeneous countries to study the endogenous choice of a minimum participation rule and its role for the success of international environmental agreement
Intensity limits of the PSI Injector II cyclotron
We investigate limits on the current of the PSI Injector II high intensity
separate-sector isochronous cyclotron, in its present configuration and after a
proposed upgrade. Accelerator Driven Subcritical Reactors, neutron and neutrino
experiments, and medical isotope production all benefit from increases in
current, even at the ~ 10% level: the PSI cyclotrons provide relevant
experience. As space charge dominates at low beam energy, the injector is
critical. Understanding space charge effects and halo formation through
detailed numerical modelling gives clues on how to maximise the extracted
current. Simulation of a space-charge dominated low energy high intensity (9.5
mA DC) machine, with a complex collimator set up in the central region shaping
the bunch, is not trivial. We use the OPAL code, a tool for charged-particle
optics calculations in large accelerator structures and beam lines, including
3D space charge. We have a precise model of the present production) Injector
II, operating at 2.2 mA current. A simple model of the proposed future
(upgraded) configuration of the cyclotron is also investigated.
We estimate intensity limits based on the developed models, supported by
fitted scaling laws and measurements. We have been able to perform more
detailed analysis of the bunch parameters and halo development than any
previous study. Optimisation techniques enable better matching of the
simulation set-up with Injector II parameters and measurements. We show that in
the production configuration the beam current scales to the power of three with
the beam size. However, at higher intensities, 4th power scaling is a better
fit, setting the limit of approximately 3 mA. Currents of over 5 mA, higher
than have been achieved to date, can be produced if the collimation scheme is
adjusted
Temporal Model of an Optically Pumped Co-Doped Solid State Laser
Currently, research is being conducted on the optical properties of materials associated with the development of solid-state lasers in the 2 micron region. In support of this effort, a mathematical model describing the energy transfer in a holmium laser sensitized with thulium is developed. In this paper, we establish some qualitative properties of the solution of the model, such as non-negativity, boundedness, and integrability. A local stability analysis is then performed from which conditions for asymptotic stability are obtained. Finally, we report on our numerical analysis of the system and how it compares with experimental results
Temporal model of an optically pumped co-doped solid state laser
Currently, research is being conducted on the optical properties of materials associated with the development of solid state lasers in the two micron region. In support of this effort, a mathematical model describing the energy transfer in a holmium laser sensitized with thulium is developed. In this paper, we establish some qualitative properties of the solution of the model, such as non-negativity, boundedness, and integrability. A local stability analysis is then performed from which conditions for asymptotic stability are attained. Finally, we report on our numerical analysis of the system and how it compares with experimental results
Survival, functional outcome and satisfaction of first revision total knee arthroplasty at a mean eleven-year follow-up.
PURPOSE
Providing long-term outcome data after rTKA and compare one- versus two-stage and septic versus aseptic revisions.
METHODS
This study represents a single-center retrospective study of first rTKAs performed for any reason with a final follow-up of a minimum of five years. Outcome parameters included stability assessment ROM, radiologic assessment, HSS score, KSS score, OKS score, EQ-5D-3L and VAS. 44 patients were included in the study. Subgroups analysis of one- versus two-stage revision and septic versus aseptic revision was performed.
RESULTS
The leading causes of rTKA in this mean 11 year follow-up study were aseptic loosening (36%) and periprosthetic joint infection (27%). At the final follow-up, there was a 89% survivorship of the implants. Patients showed a ROM of 114 ± 13°, HSS score of 78 ± 12, KKS objective score of 77 ± 16, KSS expectation and satisfaction score of 32 ± 11, KSS functional activity score of 50 ± 20, OKS of 30 ± 9, VAS of 53 ± 25 and EQ-5D index of 0.649. Functional outcome scores were not significantly altered in the analyzed subgroups.
CONCLUSIONS
In our 11Â years follow-up, we obtained 89% implant survivorship. Measurements regarding functional outcome and pain showed results in the medium range of the respective scores, while patient satisfaction lay in the upper third. No significant differences in outcome scores between one- and two-stage revisions and septic versus aseptic revisions were observed. Level of Evidence Level III, retrospective cohort study
Indications, clinical outcome and survival of rotating hinge total knee arthroplasty in a retrospective study of 63 primary and revision cases.
PURPOSE
The purpose of this study is to report and compare outcome data of both primary and revision cases using a rotating hinge knee (RHK) implant.
METHODS
This study retrospectively analyzed 63 cases (19 primary, 44 revisions) at a mean follow-up of 34 ± 8 months after RHK implantation. Outcome parameters were stability, range of motion (ROM), loosening, Hospital of Special Surgery Score (HSS), Knee Society Score (KSS), Oxford Knee Score (OKS), EQ-5D-3L, and Visual Analog Scale (VAS) for overall function. Revision rates and implant survival are reported.
RESULTS
Eleven percent showed medio-lateral instability < 5 mm, a mean ROM of 115° ± 17° and radiologic loosening occurred in 8% (2% symptomatic). PROMS showed the following results: HSS 79 ± 18, KSS 78 ± 27, OKS 26 ± 10, EQ-5D index 0.741 ± 0.233 and VAS 70 ± 20. Primary cases revealed better outcomes in HHS (p = .035) and OKS (p = 0.047). KSS, EQ-5D index and VAS did not differ between primary and revision cases (p = 0.070; p = 0.377; p = 0.117). Revision rate was 6.3% with an implant survival of 96.8%.
CONCLUSIONS
RHK arthroplasty can be performed with good clinical outcome and low revision rate in revision and complex primary cases. RHK is an option in cases where standard arthroplasty and even implants with a higher degree of constraint have reached their limits.
LEVEL OF EVIDENCE
Level III, retrospective cohort study
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