115 research outputs found

    Dementia and Stroke Risk Associated with Brain Artery Luminal Diameters

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    Background: It is unclear whether brain artery diameters measured on conventional T2-weighted brain MRI images relate to dementia and stroke outcomes across distinct populations. We aimed this study to evaluate the association of T2-weighted brain artery luminal diameters with dementia and stroke in three distinct population‑based studies. Methods: Three longitudinal population-based studies with 8420 adults \u3e40 years old (Northern Manhattan Study [NOMAS] from the United States, and the Rotterdam Study [RS], from the Netherlands, and Three-City, from France) with brain MRI scans obtained between 1999 and 2015. The median follow-up time for clinical events ranged between 7 and 12.5 years. We tested our hypothesis in each cohort separately due to local data‑sharing regulations. The exposure variable was brain carotid and basilar artery luminal diameters measured on MRI axial T2‑weighted scans. Multivariable hazard ratios (HRs) and their 95% confidence intervals (CI) expressed the risk of dementia and stroke (primary outcomes) associated with the lowest (\u3c5th) and highest (\u3e95th) percentiles of the rank‑normalized brain artery diameters compared to a reference group defined as the diameters distributed between the 5th and 95th percentiles. Secondary outcomes included total and vascular mortality, and fatal and nonfatal cardiovascular and coronary end points. Results: Among the three cohorts (mean age ranged from 65 to 73 y, ≥57% women), 335 participants developed dementia and 331 strokes. Compared with the reference group, participants with arterial diameters \u3e95th percentile had a higher risk of dementia (HR range 1.15-4.50) and any stroke (HR range 1.29-2.03). For secondary outcomes, participants with arterial diameters \u3e95th percentile had a consistent higher risk of coronary outcomes, vascular mortality and a composite of any vascular events. The results were less supportive of a higher risk of events among participants with arterial diameters \u3c5th percentile except for vascular mortality. Conclusions: Individuals with dilated brain arteries are at higher risk of dementia and vascular events. Our findings were consistency across distinct populations in spite of using a non-enhanced, conventional T2-weighted MRI sequence. Understanding the underlying physiopathology of the reported associations, particularly with dementia and stroke, might reveal novel vascular contributions to dementi

    Brain artery diameters and risk of dementia and stroke

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    INTRODUCTION: We tested the association of brain artery diameters with dementia and stroke risk in three distinct population-based studies using conventional T2-weighted brain magnetic resonance imaging (MRI) images.METHODS: We included 8420 adults &gt; 40 years old from three longitudinal population-based studies with brain MRI scans. We estimated and meta-analyzed the hazard ratios (HRs) of the brain and carotids and basilar diameters associated with dementia and stroke. RESULT: Overall and carotid artery diameters &gt; 95th percentile increased the risk for dementia by 1.74 (95% confidence interval [CI], 1.13–2.68) and 1.48 (95% CI, 1.12–1.96) fold, respectively. For stroke, meta-analyses yielded HRs of 1.59 (95% CI, 1.04–2.42) for overall arteries and 2.11 (95% CI, 1.45–3.08) for basilar artery diameters &gt; 95th percentile. DISCUSSION: Individuals with dilated brain arteries are at higher risk for dementia and stroke, across distinct populations. Our findings underline the potential value of T2-weighted brain MRI-based brain diameter assessment in estimating the risk of dementia and stroke.</p

    Brain artery diameters and risk of dementia and stroke

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    INTRODUCTION: We tested the association of brain artery diameters with dementia and stroke risk in three distinct population-based studies using conventional T2-weighted brain magnetic resonance imaging (MRI) images.METHODS: We included 8420 adults &gt; 40 years old from three longitudinal population-based studies with brain MRI scans. We estimated and meta-analyzed the hazard ratios (HRs) of the brain and carotids and basilar diameters associated with dementia and stroke. RESULT: Overall and carotid artery diameters &gt; 95th percentile increased the risk for dementia by 1.74 (95% confidence interval [CI], 1.13–2.68) and 1.48 (95% CI, 1.12–1.96) fold, respectively. For stroke, meta-analyses yielded HRs of 1.59 (95% CI, 1.04–2.42) for overall arteries and 2.11 (95% CI, 1.45–3.08) for basilar artery diameters &gt; 95th percentile. DISCUSSION: Individuals with dilated brain arteries are at higher risk for dementia and stroke, across distinct populations. Our findings underline the potential value of T2-weighted brain MRI-based brain diameter assessment in estimating the risk of dementia and stroke.</p

    Rapid evaluation of particle properties using inverse SEM simulations

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    The characteristic X-rays produced by the interactions of the electron beam with the sample in a scanning electron microscope (SEM) are usually captured with a variable-energy detector, a process termed energy dispersive spectrometry (EDS). The purpose of this work is to exploit inverse simulations of SEM-EDS spectra to enable rapid determination of sample properties, particularly elemental composition. This is accomplished using penORNL, a modified version of PENELOPE, and a modified version of the traditional Levenberg–Marquardt nonlinear optimization algorithm, which together is referred to as MOZAIK-SEM. The overall conclusion of this work is that MOZAIK-SEM is a promising method for performing inverse analysis of X-ray spectra generated within a SEM. As this methodology exists now, MOZAIK-SEM has been shown to calculate the elemental composition of an unknown sample within a few percent of the actual composition

    Determination of the Failure Susceptibility of a Flat Die used in Biomass Pelletizing Machines by means of FEA based Design Exploration

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    This paper focuses on a design analysis of a flat die used in an agricultural biomass pelletizing machine by considering its high pressure loading failure susceptibility. The pellet die is one of the key elements in a pelletizing machine, and the strength of the die plate has an important role on the pellet’s quality and producibility. In fact, higher compression ratio (CR - the ratio of effective length and the internal (press channel) diameter of a die orifice/hole) will provide denser pellets which is a desired phenomenon, however, if the compression pressure is too high or CR is not determined to compensate high pressures, the raw material may block the die and the die may experience deformation failure due to overloading. If the desire is to make high quality pellets with no die failure, optimum flat die hole/orifice design parameters should be used which can provide the best CR for a specific compression pressure. This is the core motivation of this research. In this study, Finite Element Analysis (FEA) based design exploration has been utilised for a sample single hole flat die with various die geometry parameters against various compression pressure values. Following the FEA design exploration undertaken, a response surface analysis (RSA) was carried out and then estimation models (empirical equations), which could be used to calculate parameters of the die hole/orifice against applied compression pressure and failure susceptibility based on structural stress and deformation, was described. The results gained from the RSA has indicated that the estimation models have high R2 values (higher than 98 %) which could be used for adequately predicting failure susceptibility indicators. In addition to this, FEM-based simulation print-outs have provided useful stress distribution visuals on the die against different compression pressure values. Most especially, the study has highlighted that a detailed structural optimisation study may be scheduled in order to obtain die geometry design parameters with a focus on the failure susceptibility

    Outcomes of elective liver surgery worldwide: a global, prospective, multicenter, cross-sectional study

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    Background: The outcomes of liver surgery worldwide remain unknown. The true population-based outcomes are likely different to those vastly reported that reflect the activity of highly specialized academic centers. The aim of this study was to measure the true worldwide practice of liver surgery and associated outcomes by recruiting from centers across the globe. The geographic distribution of liver surgery activity and complexity was also evaluated to further understand variations in outcomes. Methods: LiverGroup.org was an international, prospective, multicenter, cross-sectional study following the Global Surgery Collaborative Snapshot Research approach with a 3-month prospective, consecutive patient enrollment within January–December 2019. Each patient was followed up for 90 days postoperatively. All patients undergoing liver surgery at their respective centers were eligible for study inclusion. Basic demographics, patient and operation characteristics were collected. Morbidity was recorded according to the Clavien–Dindo Classification of Surgical Complications. Country-based and hospital-based data were collected, including the Human Development Index (HDI). (NCT03768141). Results: A total of 2159 patients were included from six continents. Surgery was performed for cancer in 1785 (83%) patients. Of all patients, 912 (42%) experienced a postoperative complication of any severity, while the major complication rate was 16% (341/2159). The overall 90-day mortality rate after liver surgery was 3.8% (82/2,159). The overall failure to rescue rate was 11% (82/ 722) ranging from 5 to 35% among the higher and lower HDI groups, respectively. Conclusions: This is the first to our knowledge global surgery study specifically designed and conducted for specialized liver surgery. The authors identified failure to rescue as a significant potentially modifiable factor for mortality after liver surgery, mostly related to lower Human Development Index countries. Members of the LiverGroup.org network could now work together to develop quality improvement collaboratives
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