Major Outcomes in Atrial Fibrillation Patients with One Risk Factor: Impact of Time in Therapeutic Range

BACKGROUND: The benefits and harms of oral anticoagulation (OAC) therapy in patients with only one stroke risk factor (i.e. CHA2DS2-VASc= 1 in males, or 2 in females) has been subject of debate. METHODS: We analysed all patients with only one stroke risk factor from the merged datasets of SPORTIF III and V trials. Anticoagulation control was defined according to time in therapeutic range (TTR). RESULTS: Of the original trial cohort, 1,097 patients had only one stroke risk factor. Stroke/systemic thromboembolic event had an incidence of 0.9 per 100 patient-years, with an incidence of 1.6 per 100 patient-years for all-cause death and 2.3%/patient-years for the composite outcome of stroke/systemic thromboembolic event/all-cause death. There were no significant differences in the risk for stroke/systemic thromboembolic event between sexes, nor between the different stroke risk factors amongst these atrial fibrillation patients with only one stroke risk factor. Cox regression analysis in patients treated with warfarin only found TTR to be inversely associated with stroke/systemic thromboembolic event (p=0.034) and all-cause death (p=0.015). Chronic heart failure was significantly associated with the outcome of all-cause death (p=0.0019) and the composite outcome of stroke/systemic thromboembolic event/all-cause death (p=0.021). There was a significant inverse linear association between TTR and the cumulative risk for both stroke/systemic thromboembolic event and all-cause death (both p<0.001). CONCLUSIONS: In atrial fibrillation patients with only one additional stroke risk factor (i.e. CHA2DS2-VASc= 1 in males or 2 in females), rates of major adverse events (stroke/systemic thromboembolic event, mortality) were high, despite anticoagulation. TTR in warfarin-treated patients was inversely associated with the occurrence of both stroke/systemic thromboembolic event and all-cause death

Cubic beam elements in practical analysis and design of steel frames

This paper discusses various issues in the use of cubic beam elements for computer structural analysis/design of steel frames. It is pointed out that the concern expressed in recent literature regarding the number of cubic elements required to model a steel member is not justified, and that the inaccuracy of one cubic element in Euler buckling analysis of a simply supported column is largely irrelevant to the second-order elastic analysis/design or advanced analysis of steel frames. The sources of inaccuracy of the cubic element are elucidated. It is also explained that the plastic-zone analysis method is not so inefficient as was previously believed. The spatial cubic element is shown to be capable of accurately accounting for the coupling between axial, flexural and torsional deformation modes. It is concluded that for the purposes of second-order elastic analysis/design and advanced analysis of 2D and 3D steel frames, the well-documented cubic element is a versatile and efficient choice

Limitations of current design procedures for steel members in space frames

The use of more advanced methods of analysis to design steel frames may lead to substantial material savings, in addition to simplicity in the design procedures. However, these benefits do not yet appear to be a powerful incentive for many structural engineers to abandon the familiar linear elastic analysis (LEA) based design procedures, even when dealing with steel structures that are not regular rectangular frames. This paper uses a heuristic example to demonstrate the serious limitations of the LEA based design procedures, whether alignment charts or system buckling analysis is used to determine the effective lengths of the compression members. It is shown that LEA based design procedures may lead to unsafe structures due to their inability to account for bending moment amplification in the rigidly connected tension members of a space frame. Furthermore, there is no allowance for the amplification of axial forces due to changes in the structure geometry, which is significant for the space frame example. Confidence in the system buckling analysis method for determining the effective lengths of compression members, based on linear buckling analysis, is shown to be potentially dangerous for certain types of frames. For the space frame example, the elastic buckling load is overestimated by over 200%. The conservatism inherent in the member capacity check equations specified in steel design standards is also illustrated

Beam element verification for 3D elastic steel frame analysis

The paper describes the attributes that should be possessed by a benchmark example for verifying the beam elements used to carry out 3D linear buckling analysis and 3D second-order elastic analysis of steel frames. Based on the attributes described, the paper proposes a suite of benchmark examples selected from the literature. The necessary features of a beam element required to pass the proposed benchmark problems are given, and beam elements that possess these features are cited. The paper also explains the merits of linear buckling analysis examples, and provides a commentary on two well-known examples

The year in cardiology: arrhythmias and pacing.

During this last year, there has been much progress with regard to anticoagulant and ablation therapy for atrial fibrillation (AF). Apart from recently issued European Society of Cardiology Guidelines for the management of patients with supraventricular arrhythmias, there has been little progress in research in this field. Ventricular arrhythmias and device therapy have seen modest progress

Pembinaan konstruk instrumen penilaian pasca penghunian untuk perumahan bertingkat yang dibina menggunakan kaedah Sistem Binaan Berindustri (IBS)

Post Occupancy Evaluation (POE) is an activity of the building evaluation process with a focus on quality, operational performance and satisfaction of the occupants. The POE is important to evaluate completed and occupied buildings to identify weaknesses and potential for future improvement. To date, there have been various variations of POE instruments and tools to evaluate occupied buildings. However, the POE instrument for assessing high-rise housing constructed using the industrialized building system (IBS) method has not been developed specifically. In this regard, this study aims to discuss the construction of an effective POE instrument to measure the quality and performance of high-rise housing built using the IBS method. For this purpose, the 3 round Delphi method was adapted by involving 15 experts selected based on their background and experience related to IBS. The results of a three-round Delphi study found that 33 out of all sub-constructs were dropped because of low mean scores (<4.2 in two rounds) while 75 sub-constructs were identified as final items. The results of the Delphi study also found that all 10 constructs were 1) Spatial; 2) Design and aesthetics; 3) Physical; 4) Building materials; 5) Quality of work; 6) Comfort and well-being; 7) Environment and health; 8) Maintenance; 9) Value and 10) Cost is the most significant construct for developing PPP instruments. Accordingly, an effective Post-Occupancy Assessment Instrument for measuring the quality, performance and value of a home built using the IBS method should include all of these constructs

Effect of loading direction on the bearing capacity of cold-reduced steel sheets

This study is concerned with double-shear bolted connections in cold-reduced steel sheets that undergo the pure bearing failure mode of the inside sheet. Compared to the published test results of bolted connections failing in the net section fracture, those involving the bearing failure mode had very wide scatter in the ultimate test loads of specimens having seemingly similar configurations. This technical note presents the laboratory test results of 51 specimens composed of G2 and G450 steel sheets, which have very different ductility properties. One new and significant finding is that the absolute bearing capacity can be considerably higher in the rolling direction of the cold-reduced steel sheet than in the perpendicular direction, even though the tensile strength has the opposite trend. Another result is that material ductility has a much greater effect on the bearing capacity than on the net section tension capacity. It was also found that snug tightening had little effect on the bearing capacity of specimens thicker than 1.5 mm. For the inside sheet of a double-shear bolted connection, the current American Iron and Steel Institute provision for bearing capacity is reasonably accurate if the load is applied in the rolling direction of G2 steel sheet, but is overoptimistic in the perpendicular direction

Block shear capacity of bolted connections in hot-rolled steel plates

This paper extends the research previously conducted at the University of Wollongong on block shear failure of bolted connections in cold-reduced steel sheets with low ductility to hot-rolled steel plates. It examines the applicability of the basic approach employed for cold-reduced sheet steel bolted connections, which makes use of the so-called active shear planes, to hot-rolled steel plate connections. The active shear planes lie midway between the gross and the net shear planes defined in the steel structures specifications. The paper shows that shear yielding leading to the block shear failure of a bolted connection in a hot-rolled steel gusset plate is typically accompanied by full strain hardening. The paper proposes a design equation that provides more accurate and consistent results compared to the American, Australian, Canadian and European code equations in determining the block shear capacities of bolted connections in hot-rolled steel gusset plates. A resistance factor of 0.85 is recommended in order to achieve a target reliability index of 4.0 or greater

Bearing Strength of Untightened Double-Shear Bolted Connections in Cold-Formed Steel Construction

This paper presents the experimental investigation of cold-formed steel double-shear bolted connections where both the bolt head and the nut are not in contact with the outer sheets. The inner sheet of each specimen is not constrained from out-of-plane distortion or bulging downstream of the bolt, and fails in bearing. Based on a series of tests involving specimens having bolt diameters ranging from 12 to 16 mm and sheet thicknesses ranging from 1.5 to 3.0 mm, it has been found that the absence of out-of-plane constraint in untightened bolted connections leads to much lower bearing capacities than predicted by the specification’s bearing strength equation. The effect is more pronounced for thinner sheets. An interesting finding is that the threaded bolt specimens had higher bearing capacities than the corresponding ones with shank bolts. It appears that the bolt threads provided some out-of-plane constraint to the connected sheet