Discontinuous Research Articles

Improving the efficiency of evidence-based interventions: The strengths and limitations of randomised controlled trials

Globally, randomised controlled trials (RCTs) are increasingly seen as the gold standard of programme evaluation, representing the best way to determine whether new interventions are effective – but they are not without limitations. In this article, we discuss the phases of scientific discovery and the research standards that are necessary before scaling up interventions. We also outline the core characteristics of RCTs, such as randomisation, efficacy and effectiveness, and discuss the benefits of using the RCT as the standard of intervention evaluation. We discuss how ‘realist’ evaluation contributes to what policymakers need to know in order to make a decision about an evaluation and alternatives to the RCT, such as stepped wedge, regression discontinuity, non-randomised cohort, and time series designs.

Skeletal Approach to Mandible Reconstruction Represented as an Image

ABSTRACTMandible or facial bone reconstruction is a serious challenge in craniomaxillofacial surgery. Considering the complex shape and structure of the mandible, careful presurgical planning or availability of objective methods to analyse the patient mandible is necessary to achieve predictable outcomes. It has become evident that methods that can retrieve back the exact shape and structure of the mandibular defect across any anatomical location of the mandible are required. Skeletons, a dimensionally reduced version of the shape, are an important descriptor capable of capturing the most relevant features. In this paper, a technique to retrieve the shape of the mandible from its skeleton properties, by comparing it to the skeleton of a mandible with no defects, also called template mandible has been addressed. It is also employed to correct the mandibular structure for the type of discontinuity in it, to obtain a reconstructed mandible. This will enable to look at how the defect or the discontinuity in t...

A cryptic genetic boundary in remnant populations of a long-lived, bird-pollinated shrubBanksia sphaerocarpavar.caesia(Proteaceae)

Plant species often exhibit genetic structure at multiple spatial scales. Detection of this structure may depend on the sampling strategy used. We intensively sampled a common, naturally patchy Banksia species within a 200 km2 region, in order to assess patterns of genetic diversity and structure at multiple spatial scales. In total, 1321 adult shrubs from 37 geographical populations were genotyped using eight highly polymorphic microsatellite markers developed for the species. Genetic structure was detected at three spatial scales. First, we identified a stark and unexpected division of the landscape into two genetic subregions, one to the north-east and one to the south-west of the sampling grid. This differentiation was based on sudden, highly structured differences in common allele frequencies, the cause of which is unknown but that may relate to physical and reproductive barriers to gene flow, localised selection, and/or historical processes. Second, we observed genetic differentiation of populations within these subregions, reflecting previously described patterns of restricted pollen flow in this species. Finally, fine-scale genetic structure, although weak, was observed within some of the populations (mean SP = 0.01837). When feasible, intensive sampling may uncover cryptic patterns of genetic structure that would otherwise be overlooked when sampling at broader spatial scales. Further studies using a similar sampling strategy may reveal this type of discontinuity to be a feature of other south-western Australian taxa and has implications for our understanding of evolution in this landscape as well as conservation into the future. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115, 241–255.

Improving the efficiency of evidence-based interventions: The strengths and limitations of randomised controlled trials

Globally, randomised controlled trials (RCTs) are increasingly seen as the gold standard of programme evaluation, representing the best way to determine whether new interventions are effective – but they are not without limitations. In this article, we discuss the phases of scientific discovery and the research standards that are necessary before scaling up interventions. We also outline the core characteristics of RCTs, such as randomisation, efficacy and effectiveness, and discuss the benefits of using the RCT as the standard of intervention evaluation. We discuss how ‘realist’ evaluation contributes to what policymakers need to know in order to make a decision about an evaluation and alternatives to the RCT, such as stepped wedge, regression discontinuity, non-randomised cohort, and time series designs.

Experimental study on heat transfer performance improvement of wavy finned flat tube

Three types of enhanced fin structures, including that of discontinuous fin, staggered fin and fin with vortex-generator, are proposed to enhance air side heat transfer of air-cooled condenser of power generating unit. Wind tunnel experiments with a visualized window for temperature distribution measurement of fin surface are taken to investigate heat transfer characteristics of the enhanced wavy fins, and compare with that of the original continuous wavy fin. Infrared thermography technique is employed to obtain the temperature distributions of fin surfaces, based on which, accurate fin efficiency can be acquired. While the air flow Reynolds number ranges from 1340 to 13,476, the experimental correlations of flow and heat transfer for all four types of wavy fins are obtained. The Nusselt numbers of discontinuous type, staggered type and vortex-generator type are increased by 11.29%, 28.61% and 56.46% on average, and the friction factors are increased by 3.23%, 66.26% and 48.58% on average, respectively. The PECs of three enhance wavy fin structures are higher than 1.0 in most operating conditions, implying their positive effect on heat exchange process. However, fin efficiencies obtained of all types of wavy fin are quite low, indicating that the present fin types should be shorter for higher heat transfer effectiveness.

Biodegradable covered magnesium alloys stent for a lateral aneurysm model in common carotid artery in rabbits

Objective To discuss the feasibility of biodegradable covered magnesium alloys stent for a rabbit model of lateral aneurysm in the common carotid artery (CCA). Methods The left CCA was ligated in 20 conventional New Zealand rabbits. MRA of the neck was performed 1 month after ligation. The rabbits with thickening of the right CCA and non- or slight thickening of the bilateral vertebral arteries were selected for lateral aneurysm model making. The venous pouch and the right CCA wall by discontinuous extroversion sutures, to form a lateral aneurysm model. The biodegradable covered magnesium alloys stents or Willis covered stents were inserted two weeks after model making. Angiography was performed prior to the procedure, 3, 6 and 12 months after stent implantation to evaluate the disappearance of the aneurysms and patency of the right CCA. The degradation behaviour is invastagated with molybdenum target 2 weeks, 1, 2, 4, 6, 9 and 12 months after stent placement. Results The left CCAs were successful ligated in all rabbits. MRA 1 month after ligation showed thickening of the right CCA and non-thickening of the bilateral vertebral arteries in 17 of 20 rabbits. In these animals, the CCA lateral aneurysm model was deemed successful, and biodegradable covered magnesium alloys stents and Willis covered stents were implanted in 9 and 8 aneurysms, respectively. DSA after biodegradable covered magnesium alloys stent placement displayed disappearance of the aneurysms and patency of the CCA in all 9 rabbits during follow-ups. DSA 3 months after Willis stent placement displayed patency of the CCA in 7 rabbits and occlusion of the artery in one. No occlusion of the right CCA was observed on angiography at 6 and 12 months. The degradation of the biodegradable covered magnesium alloys stent was investigated with molybdenum target during follow-ups, and no changes was observed in Willis covered stent. Conclusion Biodegradable covered magnesium alloys stent is a feasible approach for the treatment of a lateral aneurysm in the right CCA. Key words: Cerebral aneurysm; Common carotid artery; Model, rabbit; Stents

A general holographic metal/superconductor phase transition model

We study the scalar condensation of a general holographic superconductor model in AdS black hole background away from the probe limit. We find the model parameters together with the scalar mass and backreaction can determine the order of phase transitions completely. In addition, we observe two types of discontinuities of the scalar operator in the case of first order phase transitions. We analyze in detail the effects of the scalar mass and backreaction on the formation of discontinuities and arrive at an approximate relation between the threshold model parameters. Furthermore, we obtain superconductor solutions corresponding to higher energy states and examine the stability of these superconductor solutions.

Barrier Reflected Backward Doubly Stochastic Differential Equations WithDiscontinuous Generators

In this paper, we study one-dimensional reflected backward doubly stochastic differential equations(RBDSDEs) with one continuous barrier and discontinuous generator(left or right continuous). By establishing a new comparison theorem for RBDSDEs, we provide a minimal or a maximal solution to RBDSDEs under weaker hypotheses. Furthermore, we obtain a generalized comparison theorem. Some known results axe improved and extended.

On discontinuous groups acting on (ℍ2n+1r × ℍ2n+1r)/Δ

AbstractLet ℍ

Effect of early mechanical ventilation with continuous vacuum suction in treatment of serious pulmonary contusion

Objective To summarize the value of early mechanical ventilation plus continuous vacuum suction in treatment of serious pulmonary contusion. Methods Forty-eight cases of severe pulmonary contusion were assigned to mechanical ventilation plus continuous vacuum suction (observation group, n=20) and mechanical ventilation plus discontinuous vacuum suction (control group, n=28) according to the random number table. Modes of mechanical ventilation were synchronized intermittent mandatory ventilation (SIMV), pressure support ventilation (PSV), and positive and expiratory pressure (PEEP). Changes in blood gas analysis, mechanical ventilation time, and associated complications were compared between groups. Results At ventilation time of 6 and 24 hours, PaO2 in observation group was (100.36±5.90)mmHg and (105.34±7.40)mmHg respectively, with significant differences from (75.36±8.95)mmHg and (76.36±8.35)mmHg in control group (P 0.05). Conclusion Early mechanical ventilation with sustained vacuum suction is effective to keep airway clear, improve oxygenation index, decrease PEEP level, and control the duration of mechanical ventilation, but may not lower the risks of ventilator-associated pneumonia and pulmonary atelectasis. Key words: Lung injury; Ventilators, negative-pressure; Treatment outcome

Application value of optical coherence tomography in predicting visual outcome after vitrectomy for idiopathic macular epiretinal membrane

Background Idiopathic macular epiretinal membrane (IMEM) shows a high incidence and affects visual function of patients.The primary management of IMEM is vitrectomy, but the study on prediction of visual acuity after operation by optical coherence tomography (OCT) is seldom. Objective This study was to evaluate the predicting ability of OCT for preoperative visual outcome for IMEM patients who received vitrectomy. Methods The clinical data of IMEM patients with vitrectomy from March 2009 to May 2013 were retrospectively analyzed in People's Hospital Peking University.Forty-nine eyes of 48 cases were divided into continuous group (19 eyes of 18 cases) and discontinuous group (31 eyes of 31 cases) based on whether the extraretinal layers were intact on OCT, including retinal pigment epithelium (RPE), inner and outer segment of photoreceptors (IS/OS) and external limiting membrane (ELM).Central foveal thickness (CFT) by high-resolution spectral-domain OCT and best corrected visual acuity (BCVA) (LogMAR) before surgery and 12 weeks after surgery were recorded and compared between the two groups, and the correlations of shift of CFT with the shift of LogMAR vision was analyzed by unitary linear regression to evaluate the value of OCT in predicting postoperative vision.Writen informed consent was obtained from each patient prior to any medical operation.Written informed consent was obtained from each patient before surgery. Results In 12 weeks after operation, reflective strips of RPE layer, IS/OS and ELM layer were intact in 18 eyes of the continuous group after vitrectomy.The number of eyes with discontinuous strip in RPE layer decreased to 1 eye after operation from 6 eyes before operation, and the number of eyes with IS/OS reflective strip discontinue decreased to 19 eyes after operation from 29 eyes before operation, and that with ELM layer discontinue decreased to 15 eyes after operation from before operation in the discontinuous group.The improvement of LogMAR BCVA was increased with the decline of CFT values with a negative correlation between them (R2=0.298, B=0.001, P=0.000), and postoperative LogMAR visual acuity improved 1 line whenever CFT reduced by 100 μm.LogMAR BCVA was 0.4±0.19 before surgery and 0.36±0.21after surgery in the continuous group, showing a insignificant difference between them (t=0.876, P=0.393).In the discontinuous group, the postoperative logMAR BCVA was significantly higher after operation (0.46±0.26) than 0.82±0.41 after operation (t=6.206, P=0.000).The increase value of LogMAR after vitrectomy was 0.3 in the discontinuous group, which was superior to 0.0 of the continuous group. Conclusions The continuity of extraretinal layers and CFT by OCT are closely associated with the improvement of vision after vitrectomy in the eyes with IMEM. Postoperative vision is better in IMEM eye with continuous retinal reflective strips before operation, and majority of IMEM eyes can improve vision after operation. Preoperative OCT seems to be an important diagnostic tool for the selection of patients who benefit or not from surgery to certain extent. Key words: Computerized tomography; Optical coherence tomography; Visual outcome; Prognosis; Idiopathic macular epiretinal membranes; Vitrectomy

Comparative Study between PID-controller and Fuzzy Logic Controller of a Novel Flyback Converter

In this paper, proportional–integral–derivative (PID)-based Fly-back converter and fuzzy-type controllers are compared for 220V A.C input and 440 D.C output flyback converter operating in discontinuous conduction mode (DCM).Design of fuzzy controllers is based on heuristic knowledge of converter behavior, and tuning requires some expertise to minimize unproductive trial and error. The design of PID control is based on the frequency response of the converter. For the flyback converter, the performance of the fuzzy controller was superior in some respects to that of the PID controllers. The fuzzy controller was able to achieve faster transient response in most tests, had a more stable steady-state response, and was more robust under some operating conditions. MATLAB/Simulink software is used for implementation and simulation results show the performance variations.

Analysis of Five Level Diode Clamped Multilevel Inverter Using Discontinuous TPWM Technique

This paper presents a five level diode clamped multilevel inverter topology which can be used for lowmedium power industrial applications. The topology of five levels diode clamp multilevel inverter is tested using MATLAB. Circuit operation is presented, simulated & Total Harmonic Distortion is analysed. A pulse to the inverter is provided using discontinuous PWM technique.

Occurrence state of SiO2 in hercynite synthesized by reaction sintering

Sample was prepared using Fe2O3, Al2O3 and Si O2 powders as raw materials according to mass ratio Fe O:Al2O3 of 40.8:59.2 and adding a percent of Si O2 in the synthetic system, and being sintered under high purity nitrogen atmosphere at 1 600 ℃for 4 h. The sample was analyzed and characterized by X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy and transmission electron microscope. Based on Fe O-Al2O3-Si O2 ternary phase diagram, the existence of silicon dioxide was investigated. The results indicate that silicon dioxide didn't enter into hercynite crystals, but existed among hercynite crystals as amorphous phase. When a percent of Si O2 was added into the synthetic system, amorphous phase containing Si O2 was discontinuously distributed and the direct contact among hercynite crystals wasn't changed.

Analysis of Bifurcation in Quadratic BuckConverter

This paper presents the analysis of a bifurcation in quadratic buck converter. This class of converter offers very wide range of DC voltage conversion ratio enabling higher switching frequencies. In this paper, analysis of the quadratic buck converter in discontinuous conduction mode (DCM) is presented and corresponding simulation results obtained using MATLAB software. Pulse train control quadratic buck converter operated in DCM is analysed for bifurcation. Non linear dynamics of DCM quadratic buck converter under different input voltage and load conditions are examined and the simulation results are given.

ICONE23-1559 CREEP-FATIGUE TESTS OF DOUBLE-END NOTCHED BAR MADE OF MOD.9CR-1MO STEEL

This paper describes experimental and analytical works to confirm that the design standard for Sodium cooled Fast Reactor (SFR) components sufficiently covers possible failure mechanisms. Present design standards for SFR components have been proposed by Japan Society of Mechanical Engineers (JSME). For economical reasons, Mod.9Cr-1Mo ferritic steel, equivalent to ASME Gr.91, will be widely adopted to coolant systems in future SFRs. Creep-fatigue damage evaluation method in JSME design standard for SFR components has been constructed based on experiments and/or numerical analyses of conventional austenitic stainless steels, such as 304SS. Since the material characteristics of Mod.9Cr-1Mo steel are substantially different from those of austenitic stainless steels, it is required to verify the applicability of the design standards to the SFR components made of Mod.9Cr-1Mo steel. However, few structural test data exist to verify the applicability of the conventional design standards. Therefore, to investigate creep-fatigue failure aspect of the several types of structural discontinuities, a series of uni-axial creep-fatigue tests were conducted using double-ended notch bar specimens made of Mod.9Cr-1Mo steel under displacement controlled condition with 30 minute holding. In these tests, imposed axial displacement was controlled to result in 0.7% axial strain range at the minimum section area. The curvature radii of the specimens were 1.6 mm, 11.2 mm and 40.0 mm. The specimen having 1.6 mm notch and 11.2 mm notch failed from outer surface but the specimen having 40.0 mm notch showed obvious internal crack nucleation. In addition, though total duration time of the creep-fatigue test was only 2,000 hours, a lot of creep voids and inter granular crack growth were observed. To clarify the cause of such peculiar failure, some additional experiments were performed, as well as some numerical analyses. We could point out that such a peculiar failure aspect might result from corresponding stress distribution in the cross section. Since radial temperature distribution resulted from high-frequency induction heating and local multiaxiality also might produce such peculiar failure, analytical investigations were carried out. As a result of a series of investigations, possible causes of such peculiar failure could be narrowed down. A future investigation plan was proposed to clarify the most significant cause.

Difficulties and Errors of 1st Grade Computer Teaching and Technology Department Students on Discontinuity Types of Partial Functions and Some Certain Functions

The aim of this study is to investigate difficulties and errors of 1st grade Computer Teaching and Technology Department students on discontinuity kinds of partial functions and some certain functions. The data is gathered by the questionnaire containing 10 open ended questions. The answers of students are categorized according to 0-3 points’ schema. Based on the results and detailed analysis of students’ responses it is observed that students have many difficulties on finding the right and left hand side limit of partial functions on specific points. So it leads errors on determining the discontinuity types of these functions. Moreover, the results of analysis show that students have some difficulties on determining the discontinuity of some specific functions.

Gas-dynamic Discontinuity Conception

The aim of the study-to demonstrate the properties of the gas-dynamic discontinuity as a singularity the geometry of the Euler equations give on this basis, the definition of the intensity discontinuity. We have considered the gas-dynamic discontinuity conception. We demonstrated geometrical content of gas dynamics equation. The shock-wave process concept (as a transfer function of gas-dynamic variables space reorganization) was introduced. The basic types of gas-dynamic discontinuities: shock waves, compression shocks, centered depression and compression waves, contact discontinuities were considered. The discontinuity intensity concept was introduced. The basic formulae and discontinuity intensity calculation results were given.

Nested dyadic grids associated with Legendre–Gauss–Lobatto grids

Legendre---Gauss---Lobatto (LGL) grids play a pivotal role in nodal spectral methods for the numerical solution of partial differential equations. They not only provide efficient high-order quadrature rules, but give also rise to norm equivalences that could eventually lead to efficient preconditioning techniques in high-order methods. Unfortunately, a serious obstruction to fully exploiting the potential of such concepts is the fact that LGL grids of different degree are not nested. This affects, on the one hand, the choice and analysis of suitable auxiliary spaces, when applying the auxiliary space method as a principal preconditioning paradigm, and, on the other hand, the efficient solution of the auxiliary problems. As a central remedy, we consider certain nested hierarchies of dyadic grids of locally comparable mesh size, that are in a certain sense properly associated with the LGL grids. Their actual suitability requires a subtle analysis of such grids which, in turn, relies on a number of refined properties of LGL grids. The central objective of this paper is to derive the main properties of the associated dyadic grids needed for preconditioning the systems arising from $$hp$$hp- or even spectral (conforming or Discontinuous Galerkin type) discretizations for second order elliptic problems in a way that is fully robust with respect to varying polynomial degrees. To establish these properties requires revisiting some refined properties of LGL grids and their relatives.

Detection and Estimation of Jump Points in Non parametric Regression Function with AR(1) Noise

In this paper, we propose a method based on wavelet analysis to detect and estimate jump points in non parametric regression function. This method is applied to AR(1) noise process under random design. First, the test statistics are constructed on the empirical wavelet coefficients. Then, under the null hypothesis, the critical values of test statistics are obtained. Under the alternative, the consistency of the test is proved. Afterward, the rate of convergence, the estimators of the number, and locations of change points are given theoretically. Finally, the excellent performance of our method is demonstrated through simulations using artificial and real datasets.