Introduction/purpose
In adult scoliosis surgery (AS) delineation of risk factors contributing to failure is important to improve patient care. Treatment goals include deformity correction resulting ...in a balanced spine and horizontal lowest instrumented vertebra (LIV) in fusions not ending at S1. Therefore, the study objectives were to determine predictors for deformity correction, complications, revision surgery, and outcomes as well as to determine predictors of postoperative evolution of the LIV-take-off angle (LIV-TO) and symptomatic adjacent segment disease (ASD).
Methods
The authors performed a retrospective analysis of 448 patients who had AS surgery. Patients’ age averaged 51 years, BMI 26, and follow-up of 40 months. According to the SRS adult scoliosis classification, 51 % of patients had major lumbar curves, 24 % each with single thoracic or double major curves. 54 % of patients had stable vertebra at L5 and 34 % of patients had fusion to S1. The mean number of posterior fusion levels was eight and implant density 73 %. Among standard radiographic measures of deformity the LIV-TO was assessed on neutral and bending/traction-films (bLIV-TO). Clinical outcomes were assessed in 145 patients with degenerative-type AS using validated measures (ODI, COMI and SF-36). Prediction analysis was conducted with stepwise multiple regression analyses.
Results
Preoperative thoracic curve (TC) was 53° and 33° at follow-up. Preoperative lumbar curve (LC) was 43° and 24° at follow-up. Curve flexibility was low (TC 34 %/LC 38 %). TC-correction (38 %) was predicted by preoperative TC (
r
= 0.9) and TC-flexibility (
r
= 0.8). LC-correction (50 %) was predicted by preoperative LC (
r
= 0.8), LC-flexibility (
r
= 0.8) and screw density (
r
= 0.7). Preoperative LIV-TO was 18.2° and at follow-up 9.4° (
p
< 0.01). 20 % of patients had a non-union (18 % at L5-S1). The risk for non-union at L5-S1 increased with age (
p
= 0.04), low screw density (
p
= 0.03), and postoperative sagittal imbalance (T9-tilt (
p
= 0.01), C7-SVA (
p
= 0.01), LL (
p
= 0.01) and PI-LL mismatch (
p
= 0.01). 32 % of patients had revision surgery. Risk for revision was increased in fusions to S1 (
p
< 0.01), increased BMI (
p
< 0.01), sagittal imbalance (C7-SVA,
p
< 0.01), age (
p
= 0.02), and disc wedging distal to the LIV (
p
< 0.01). To a varying extent, clinical outcomes negatively correlated (
p
< 0.05) with revision, ASD, perioperative complications, age, low postoperative TC- and LC-correction, and sagittal and coronal imbalance at follow-up (C7-SVA, PT, and C7-CSVL). 59 patients had ASD, which correlated with preoperative and postoperative sagittal and coronal parameters of deformity. In a multivariate model, preoperative bLIV-TO (
p
< 0.01) and preoperative LIV-TO (
p
< 0.01) demonstrated the highest predictive strength for follow-up LIV-TO.
Conclusion
In the current study, the magnitude of deformity correction in the sagittal and coronal planes was shown to have significant impact on radiographic and clinical outcomes as well as revision rates. Findings indicate that risks for complications might be reduced by restoration of sagittal balance, appropriate deformity correction and advanced lumbosacral fixation. The use of preoperative LIV-TO and LIV-TO on bending/traction-films were shown to be useful for surgical planning, selection of the LIV and prediction of follow-up-TO, respectively. Parameters of sagittal balance rather than coronal deformity predicted ASD.
Previous experimental studies have shown that some halogenated fire suppressant agents added to hydrocarbon–air systems can enhance the combustion. For example, their addition to the air stream can ...widen the flammability limits of lean mixtures, and increase the maximum explosion pressure for constant volume combustion. To explore the experimentally observed combustion enhancement, the combustion properties of pure mixtures of fire suppressants and air/oxygen were studied. Adiabatic combustion temperatures, ignition delays and burning velocities were calculated for several typical fluorinated fire suppressant agents (CF3H, C2F5H, C3F7H and C3F7COC2F5) in mixtures with air, and CF3Br and CF3I in air and oxygen. Calculated burning velocities are in the range 0.37–2.5cm/s at initial temperature 400K (stoichiometric air mixtures of CF3H, C2F5H, C3F7H, C3F7COC2F5, 1bar). The results show that the fluorinated agents possess sufficient energy to participate in combustion processes, and can support combustion with burning velocities which should be measurable (for some of the systems) at slightly elevated initial temperatures. Simulated ignition delays for C3F7H and C3F7COC2F5 are shorter than for propane for the analyzed range of temperature (1000–1500K), and those for C2F5H/air mixtures are comparable with propane in a lower temperature range (1000–1250K).
Introduction
Cervical laminectomy is a reliable tool for posterior decompression in various cervical spine pathologies. Although there is increasing evidence of superior clinical, neurological and ...radiological outcomes when using anterior cervical decompression, laminectomy can be a valuable tool when combined with instrumented lateral mass fusion for carefully selected indications.
Methods
Literature review.
Results
This review article will provide decision-making guidance, technical advices and pitfalls. The technical advice for laminectomy and instrumented lateral mass fusion is illustrated. The authors review the literature on outcomes and complications and suggest indications for the safe and successful application of cervical laminectomy and lateral mass fusion.
Constrained by the experimental conditions, field fire tests at high-altitude areas can only examine a limited number of low pressure environments. To explore more low pressure environments, an ...altitude chamber of size 3×2×2m has been built to simulate static low pressure environments in the range from 101kPa to 30kPa, as well as dynamic pressure environments depressurized from 101kPa to 30kPa at different descent rates. Then by aid of the altitude chamber, low-pressure fires under both static and dynamic pressures were tested. In the static fire tests, four static pressures, i.e. 101kPa, 75kPa, 64kPa and 40kPa were examined through automatically adjusting the pumping speed to maintain a fixed static pressure in the altitude chamber. In the dynamic fire tests, depressurization processes with three descent rates from 101kPa to 30kPa were examined in the altitude chamber through pumping gas and simultaneously replenishing air at the rates of 0, 15 and 20Nm3/h. The tested pool fire sizes were 6-cm-diameter and 10-cm-diameter round pans filled with a 2-cm-height layer of 99% pure liquid n-Heptane, and in the static tests cold water were laid beneath the fuel layer in order to cool the fuel. Multi-point axial flame temperature, radiative heat flux, mass burning rate, chamber pressure and hi-speed flame videos etc. were measured for each test. Some special phenomena were observed from the hi-speed flame videos for the liquid pool fires during the depressurization, e.g. the flame shifted from turbulent to laminar and its base turned blue as pressure drops, then at low enough pressure a polyhedral flame appeared and swirled in the pan. The flame temperature and radiative heat flux were analyzed in correlation with mass burning rate and pressure to reveal the pressure effect on fire behavior.
Several agents are under consideration to replace CF
3Br for use in suppressing fires in aircraft cargo bays. In a Federal Aviation Administration performance test simulating the explosion of an ...aerosol can, however, the replacements, when added at sub-inerting concentrations, have all been found to create higher pressure rise than with no agent, hence failing the test. Thermodynamic equilibrium calculations as well as perfectly-stirred reactor simulations with detailed reaction kinetics, are performed to understand the reasons for the unexpected enhanced combustion rather than suppression. The high pressure rise with added C
2HF
5 or C
3H
2F
3Br is shown to be dependent upon the amount of added agent, and can only occur if a large fraction of the available oxidizer in the chamber is consumed, corresponding to stoichiometric proportions of fuel, oxygen, and agent. Conversely, due to the unique stoichiometry of CF
3Br, this agent is predicted to cause no increase in pressure, even in the absence of chemical inhibition. The stirred-reactor simulations predict that the inhibition effectiveness of CF
3Br is highly dependent upon the mixing conditions of the reactants (which affects the local stoichiometry and hence the overall reaction rate). For C
2HF
5, however, the overall reaction rate was only weakly dependent upon stoichiometry, so the fuel–oxidizer mixing state has less effect on the suppression effectiveness.
Introduction
The decision of when to use selective thoracic fusion (STF) and the prediction of spontaneous lumbar curve correction (SLCC) remain difficult. Using a novel methodological approach, the ...authors yielded for a better prediction of SLCC and analyzed the efficacy of anterior scoliosis correction and fusion (ASF).
Methods
A retrospective analysis of 273 patients treated with ASF for STF was performed. In total, 87 % of the patients showed a Lenke 1 curve pattern. The lumbar curve modifier was classified as A in 66 % of the patients, B in 21 % of the patients and C in 13 % of the patients. The fusion length averaged 6.7 levels. The analysis included an assessment of radiographic deformity and correction, surgery characteristics, complications and revisions and clinical outcomes to improve the prediction of SLCC. Patients with a Type A-L, Type B or Type C modifier were stratified into a target follow-up lumbar curve (LC) category of ≤20° or >20°. Linear regression analyses were performed to assess the accuracy of predicting LC magnitude, and a multivariate logistic regression model was built using the following preoperative (preop) predictors: main thoracic curve (MTC), LC, MTC-bending and LC-bending. The output variable indicated whether a patient had an LC >20° at follow-up. A variable selection algorithm was applied to identify significant predictors. Two thresholds (cut-offs) were applied to the test sample to create high positive and negative prediction values. The data from 33 additional patients were gathered prospectively to create an independent test sample to learn how the model performed with independent data as a test of the generalizability of the model.
Results
The average patient age was 17 years, and the average follow-up period was 33 months. The MTC was 53.1° ± 10.2° preoperatively, 29.8° ± 10.5° with bending and was 25.4° ± 9.7° at follow-up (
p
< 0.01). The LC was 35.7° ± 7.5° preoperatively, 8.9° ± 5.8° with bending, and 21.8° ± 7.0° at follow-up (
p
< 0.01). After applying a variable selection algorithm, the preop LC
p
< 0.02, odds ratio (OR) = 1.09 and preop LC-bending (
p
< 0.009, OR = 1.14) remained in the model as significant predictors. The performance of the linear regression model was tested in an independent test sample, and the difference between the observed and predicted values was only 1° ± 4.5°. Based on the test sample, the lower threshold was set to 25 %, and the upper threshold was set to 75 %. Patients with prediction values of 25–75 % were identified by the model, but by definition of the model, no prediction was made. In the test sample, 87 % of the patients were correctly classified as having an LC ≤20° at follow-up, and 84 % of the patients were correctly classified as having an LC >20°. The model test in the independent test sample revealed that 100 % of the patients were correctly classified as having an LC ≤20°, and 86 % of the patients were correctly classified as having an LC >20°.
Conclusion
After analyzing a sufficiently large sample of 273 patients who underwent ASF for STF, significant predictors for SLCC were established and reported according to the surgical outcomes. Application of the prediction models can aid surgeons in the decision-making process regarding when to perform STF. Our results indicate that with stratification of outcomes into target curves (e.g., an LC <20°), future benchmarks for STF might be more conclusive.
•We examine how BCT can help implement circular supply chain management (CSCM).•Dynamic capabilities are deduced for successful CSCM implementations with BCT.•Case studies are presented illustrating ...practical examples.•Supply chain traceability and related sensing capabilities are major benefits of BCT-driven CSCM.
Achieving a circular economy (CE) is considered one of the most significant challenges of our time, as environmental challenges and social discrepancies keep increasing. While companies need to transform their supply chains towards sustainability and circularity, implementing CE concepts into practice is not straightforward and requires technical and non-technical capabilities, referring to dynamic capabilities. One of the most promising digital technologies for improving sustainability and circularity is blockchain. However, the literature on relationships between blockchain technology (BCT), sustainability, and the CE is still in its infancy. This study illustrates how BCT can help implement circular supply chain management (CSCM) from a dynamic capabilities perspective. A multiple case study approach examines how BCT’s potential impacts CSCM. Building on the case evidence, necessary dynamic capabilities are deduced for successful CE implementations with BCT. The analysis demonstrates that supply chain traceability and related sensing capabilities are major benefits of BCT-driven CSCM. Thus, we contribute to theory by examining which dynamic capabilities need to be developed when realizing CSCM through BCT. The results indicate that the BCT potentials depend on the business model pointing to certain contingencies.
Aggressive Russian policies and the Trump administration's transactional approach to alliances have put nuclear issues back on the agenda for European governments. Arguments for German acquisition of ...nuclear weapons have gained no traction among German decision makers, as this would require multiple costly and radical shifts of Berlin's foreign and security policies. German-French convergence on the role of nuclear weapons in European security is a necessary - though not necessarily sufficient - precondition for a strengthened nuclear dimension to the EU's security and defense policies. However, the different nuclear cultures in France and Germany, French aversion to nuclear consultations, and inter-European divisions on the role of nuclear weapons make it unlikely that Germany will support a Eurodeterrent anytime soon. In the short term, the German debate on NATO's response to the end of the INF treaty and Berlin's decision on new dual-capable aircraft to support NATO's nuclear sharing arrangements will be indicators of changing nuclear attitudes and policies.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
9.
Adenovirus endocytosis Meier, Oliver; Greber, Urs F.
The journal of gene medicine,
June 2003, Letnik:
5, Številka:
6
Journal Article
This volume evaluates the impact of coercive arms control efforts to curb the spread of weapons of mass destruction in the twenty-first century.
A new paradigm in arms control is gradually replacing ...the idea that mutually agreed restrictions on armaments can improve international security. Thus, Hedley Bull's classic definition of arms control as the "cooperation between antagonistic pairs of states in military affairs" needs to be amended by a new notion of coercive arms control as the set of non-cooperative and non-reciprocal measures to restrict the weapons or military capabilities of certain states.
This volume addresses the topic of how this ongoing paradigmatic shift will affect the effectiveness of arms control as a conflict management instrument.While some argue that new instruments can complement and strengthen traditional, multilateral and inclusive arms control regimes, others maintain that conflicts and contradictions between coercive and cooperative arms control regimes will severely limit their effectiveness. This volume provides a forum for academics and practitioners from around the globe to discuss these developments in depth and to assess the specific strengths and weaknesses of these new instruments of arms control.
This book will be of much interest to students of arms control, global governance, foreign policy and IR/Security Studies in general.
