107 research outputs found
Optimal Timing of Simethicone Supplement for Bowel Preparation: A Prospective Randomized Controlled Trial
No full textBackground and Aims. Simethicone (SIM), as an antifoaming agent, has been shown to improve bowel preparation during colonoscopy. However, the optimal timing of SIM addition remained undetermined. We aimed to investigate the optimal timing of SIM addition to polyethylene glycol (PEG) to improve bowel preparation. Methods. Eligible patients were randomly assigned to two groups: the SIM evening group (SIM addition to PEG in the evening of the day prior to colonoscopy) and the SIM morning group (SIM addition to PEG in the morning of colonoscopy). The primary outcome was Bubble Scale (BS). The secondary outcomes were Boston Bowel Preparation Scale (BBPS) and adenoma detection rate (ADR). Results. A total of 419 patients were enrolled in this study. The baseline characteristics of the patients were similar in both groups. No significant differences were observed in terms of BS (8.76 ± 0.90 vs. 8.65 ± 1.16, P = 0.81), ADR (34.1% vs. 30.8%, P = 0.47), Boston Bowel Preparation Scale (BBPS) (8.59 ± 0.94 vs. 8.45 ± 1.00, P = 0.15), and withdrawal time (8.22 ± 2.04 vs. 8.01 ± 2.51, P = 0.094) between the two groups. Moreover, safety and compliance were similar in both groups. However, the SIM evening group was associated with shorter cecal intubation time (3.80 ± 1.81 vs. 4.42 ± 2.03, P < 0.001), higher BS (2.95 ± 0.26 vs. 2.88 ± 0.38, P = 0.04) in the right colon, and diminutive ADR (62.5% vs. 38.6%, P = 0.022) in the right colon, when compared to the SIM evening group. Conclusions. The SIM addition to PEG in the evening of the day prior to colonoscopy can shorten cecal intubation time and improve BS scores and diminutive ADR of the right colon compared with the SIM addition to PEG in the morning of colonoscopy in bowel preparation
Six‐way decomposition of causal effects: Unifying mediation and mechanistic interaction
No full textThe sufficient component cause (SCC) model and counterfactual model are two common methods for causal inference, each with their own advantages: the SCC model allows the mechanistic interaction to be detailed, whereas the counterfactual model features a systemic framework for quantifying causal effects. Hence, integrating the SCC and counterfactual models may facilitate the conceptualization of causation. Based on the marginal SCC (mSCC) model, we propose a novel counterfactual mSCC framework that includes the steps of definition, identification, and estimation. We further propose a six‐way effect decomposition for assessing mediation and the mechanistic interaction. The results demonstrate that when all variables are binary, the six‐way decomposition is an extension of four‐way decomposition and that without agonism, the six‐way decomposition is reduced to four‐way decomposition. To illustrate the utility of the proposed decomposition, we apply it to a Taiwanese cohort to examine the mechanism of hepatitis C virus (HCV)‐induced hepatocellular carcinoma (HCC) with liver inflammation measured by alanine aminotransferase (ALT) as a mediator. Among the HCV‐induced HCC cases, 62.27% are not explained by either mediation or interaction in relation to ALT; 9.32% are purely mediated by ALT; 16.53% are caused by the synergistic effect of HCV and ALT; and 9.31% are due to the mediated synergistic effect of HCV and ALT. In summary, we introduce an SCC model framework based on counterfactual theory and detail the required identification assumptions and estimation procedures; we also propose a six‐way effect decomposition to unify mediation and mechanistic interaction analyses.補正完
Design and optimisation of a coreless superconducting synchronous generator
No full textConstantly increasing demand for electrical power requires more efficient and more powerful machines to be built. The conventional technology cannot provide such machines. It cannot deliver machines that are smaller, lighter and provide larger torques and power ratings. The answer to these problems is believed to be in superconducting machines.After short introduction to the phenomena of superconductivity and superconducting devices, practical superconducting tapes are described. The evolution and problems considered during the design of a coreless superconducting rotor for a synchronous machine are described. A few possible coreless rotor configurations are characterised and a simple formula is used to minimise the harmonic content.Estimation of machine parameters and evaluation of losses is also conducted. The areas to which particular attention has to be paid are pointed out. All these are undertaken for a demonstrator size machine with BSCCO windings. But to achieve real benefits it is important to build a machine that more closely represents real machines. Hence an optimisation method is used to investigate the possibility of increasing the size of the machine
Performance Evaluation of Link Metrics in Vehicle Networks: a Study from the Cologne Case
No full textInternational audienceIn vehicle ad hoc networks, the link duration is an impor-tant concept for clustering and dissemination. Many linkmetrics are proposed to predict it based on the vehicles’ ve-locities and distance between vehicles. However, there is alack of comparison of these metrics under the same frame-work. In this paper, we compare several common adoptedlink metrics, LLT (link life time), SLS (spatial locality sim-ilarity), and SF (similarity function), in the performance oflink duration prediction, according to a real vehicular mo-bility trace of the city of Cologne, Germany. We find thatthere exists a large gap in between the predicted link du-ration order and real link duration order for the real traffictrace, and there is no winning link metric in all scenarios.Furthermore, as an example, we show that, by combiningexisting link metrics intelligently, it is possible to create anew link metric that predicts link duration better.</p
A Hoarse Warning: Ortner Syndrome
No full text10.1016/j.amjmed.2018.07.036AMERICAN JOURNAL OF MEDICINE131121460-146
Magnetic resonance image segmentation for knee osteoarthritis using active shape models
No full textKnee osteoarthritis is a chronic joint inflammation disease that affects the aged population nowadays. The disease leads to gradual degradation of cartilage and thus deteriorates the function of the knee joint. Magnetic Resonance Imaging (MRI) provides promising results for the early detection of knee osteoarthritis. Conventionally, the MR image segmentation for knee osteoarthritis is manually done by clinicians. Limitations of this process include being laborious, time-consuming and prone to subjective diagnosis error. Therefore, the development of an automated cartilage segmentation method is crucial to assist the medical research in knee osteoarthritis. This project applied the Active Shape Models (ASM) approach to create semi-automated cartilage segmentation software. A shape model was constructed from a training set consisting of 10 knee MR images which includes major variations of the knee cartilage shape. Principle component analysis (PCA) was utilized to identify the main axes of variations used to build the shape model. This shape model was finally used to segment the knee articular cartilage. Outcomes of the ASM segmentation were compared with the outcome of manual segmentation. Experimental results showed that the sensitivity of developed ASM approach increased averagely from 73.78% to 80.75%, proportional to the increasing of the number of iteration in the segmentation as well as landmark of the shape model. This technique is reliable to contribute to medical research in knee osteoarthritis by providing an efficient and high accuracy segmentation method for knee articular cartilage, to further assist in the detection of knee osteoarthritis via MRI technique
Insight-HXMT and GECAM-C observations of the brightest-of-all-time GRB 221009A
No full textInternational audienceGRB 221009A is the brightest gamma-ray burst ever detected since the discovery of this kind of energetic explosions. However, an accurate measurement of the prompt emission properties of this burst is very challenging due to its exceptional brightness. With joint observations of \textit{Insight}-HXMT and GECAM-C, we made an unprecedentedly accurate measurement of the emission during the first 1800 s of GRB 221009A, including its precursor, main emission (ME, which dominates the burst in flux), flaring emission and early afterglow, in the hard X-ray to soft gamma-ray band from 10 keV to 6 MeV. Based on the GECAM-C unsaturated data of the ME, we measure a record-breaking isotropic equivalent energy () of erg, which is about eight times the total rest-mass energy of the Sun. The early afterglow data require a significant jet break between 650 s and 1100 s, most likely at s from the afterglow starting time , which corresponds to a jet opening angle of , where is the ambient medium density in units of and is the ratio between -ray energy and afterglow kinetic energy. The beaming-corrected total -ray energy is erg, which is typical for long GRBs. These results suggest that this GRB may have a special central engine, which could launch and collimate a very narrowly beamed jet with an ordinary energy budget, leading to exceptionally luminous gamma-ray radiation per unit solid angle. Alternatively, more GRBs might have such a narrow and bright beam, which are missed by an unfavorable viewing angle or have been detected without distance measurement
Insight-HXMT and GECAM-C observations of the brightest-of-all-time GRB 221009A
No full textInternational audienceGRB 221009A is the brightest gamma-ray burst ever detected since the discovery of this kind of energetic explosions. However, an accurate measurement of the prompt emission properties of this burst is very challenging due to its exceptional brightness. With joint observations of \textit{Insight}-HXMT and GECAM-C, we made an unprecedentedly accurate measurement of the emission during the first 1800 s of GRB 221009A, including its precursor, main emission (ME, which dominates the burst in flux), flaring emission and early afterglow, in the hard X-ray to soft gamma-ray band from 10 keV to 6 MeV. Based on the GECAM-C unsaturated data of the ME, we measure a record-breaking isotropic equivalent energy () of erg, which is about eight times the total rest-mass energy of the Sun. The early afterglow data require a significant jet break between 650 s and 1100 s, most likely at s from the afterglow starting time , which corresponds to a jet opening angle of , where is the ambient medium density in units of and is the ratio between -ray energy and afterglow kinetic energy. The beaming-corrected total -ray energy is erg, which is typical for long GRBs. These results suggest that this GRB may have a special central engine, which could launch and collimate a very narrowly beamed jet with an ordinary energy budget, leading to exceptionally luminous gamma-ray radiation per unit solid angle. Alternatively, more GRBs might have such a narrow and bright beam, which are missed by an unfavorable viewing angle or have been detected without distance measurement
Insight-HXMT and GECAM-C observations of the brightest-of-all-time GRB 221009A
No full textGRB 221009A is the brightest gamma-ray burst ever detected since the discovery of this kind of energetic explosions. However, an accurate measurement of the prompt emission properties of this burst is very challenging due to its exceptional brightness. With joint observations of \textit{Insight}-HXMT and GECAM-C, we made an unprecedentedly accurate measurement of the emission during the first 1800 s of GRB 221009A, including its precursor, main emission (ME, which dominates the burst in flux), flaring emission and early afterglow, in the hard X-ray to soft gamma-ray band from 10 keV to 6 MeV. Based on the GECAM-C unsaturated data of the ME, we measure a record-breaking isotropic equivalent energy () of erg, which is about eight times the total rest-mass energy of the Sun. The early afterglow data require a significant jet break between 650 s and 1100 s, most likely at s from the afterglow starting time , which corresponds to a jet opening angle of , where is the ambient medium density in units of and is the ratio between -ray energy and afterglow kinetic energy. The beaming-corrected total -ray energy is erg, which is typical for long GRBs. These results suggest that this GRB may have a special central engine, which could launch and collimate a very narrowly beamed jet with an ordinary energy budget, leading to exceptionally luminous gamma-ray radiation per unit solid angle. Alternatively, more GRBs might have such a narrow and bright beam, which are missed by an unfavorable viewing angle or have been detected without distance measurement
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