213 research outputs found
A hybrid version of swan for fast and efficient practical wave modelling
In the Netherlands, for coastal and inland water applications, wave modelling with
SWAN has become a main ingredient. However, computational times are relatively high. Therefore
we investigated the parallel efficiency of the current MPI and OpenMP versions of SWAN. The MPI
version is not that efficient as the OpenMP version within a single node. Therefore, in this paper
we propose a hybrid version of SWAN. It combines the efficiency of the current OpenMP version on
shared memory with the capability of the current MPI version to distribute memory over nodes. We
describe the numerical algorithm. With numerical experiments for important applications we show
the potential of this hybrid version, We further optimize the approach and illustrate the behavior
for larger number of nodes. Parallel I/O will be subject of future research
A hybrid SWAN version for fast and efficient practical wave modelling
In the Netherlands, for coastal and inland water applications, wave modelling with SWAN has
become a main ingredient. However, computational times are relatively high. Therefore we
investigated the parallel efficiency of the current MPI and OpenMP versions of SWAN. The
MPI version is not that efficient as the OpenMP version within a single node. Therefore, in this
paper we propose a hybrid version of SWAN. It combines the efficiency of the current OpenMP
version on shared memory with the capability of the current MPI version to distribute memory
over nodes. We describe the numerical algorithm. With initial numerical experiments we show
the potential of this hybrid version. Parallel I/O, further optimization, and behavior for larger
number of nodes will be subject of future research
Patch angioplasty during carotid endarterectomy using different materials has similar clinical outcomes
OBJECTIVE: Patch angioplasty during carotid endarterectomy is commonly used to treat carotid artery stenosis. However, the choice of which patch to use is still a matter of debate. Autologous venous material has disadvantages such as wound-related problems at the harvest site and a prolonged intervention time. These limitations can be bypassed when synthetic or biological patches are used. Both materials have been associated with divergent advantages and disadvantages. Therefore, the aim of our study was to compare the long-term follow-up outcomes in patients who received carotid endarterectomy and closure with either bovine pericardial patch or polyester patch. METHODS: A retrospective cohort study was conducted, including all patients who underwent primary carotid endarterectomy and closure with bovine pericardial patch or polyester patch between January 2010 and December 2020 at our tertiary referral center. In 2015, bovine pericardial patch was introduced as an alternative for polyester. The primary outcome was the occurrence of transient ischemic attack or cerebrovascular accident during follow-up and secondary outcomes included restenosis, reintervention, all-cause mortality, and patch infection. Cox proportional hazard models were utilized and hazard ratios with 95%-confidence interval were used to predict the above-mentioned outcomes. RESULTS: 417 carotid endarterectomy patients were included. 254 (61%) patients received bovine pericardial patch and 163 received (39%) polyester. The mean age was 70.2 ± 8.7 and 67% were male. The median follow-up time was 15 (12-27) months for bovine pericardial patch and 42 (16-60) months for polyester (p<0.001). Postoperative hematoma (≤30 days) was significantly lower in the bovine pericardial patch cohort (2% bovine pericardial patch vs 6% polyester; p=0.047). No other significant differences on short-term outcomes were found. Univariable cox regression analyses showed no significant differences between the effect estimates of polyester and bovine pericardial patch on transient ischemic attack or cerebrovascular accident (p=0.106), restenosis (p=0.211), reintervention (p=0.549), and all-cause mortality (p=0.158). No significant differences were found after adjusting for confounders in the multivariable analyses: transient ischemic attack or cerebrovascular accident, (p=0.939), restenosis (p=0.057), reintervention (p=0.193) and all-cause mortality (p=0.742). Three patients with a polyester patch had patch infection compared to none of the patients in the group who received a bovine pericardial patch. CONCLUSION: This large retrospective study showed comparable safety and durability of both bovine pericardial patch and polyester suggesting that both patch types can be safely applied for carotid endarterectomy with patch angioplasty. Patch infection was rare while absent in the bovine pericardial patch group
Long-Term Stroke Risk in Patients With New Ischemic Brain Lesions on MRI After Carotid Revascularization
BACKGROUND: Carotid artery revascularization can result in new ischemic brain lesions on diffusion-weighted magnetic resonance imaging. This study aimed to investigate the relationship between periprocedural ischemic diffusion-weighted imaging (DWI) lesions after carotid artery revascularization and recurrent long-term cerebrovascular events. METHODS: A secondary observational prospective cohort analysis of existing clinical trial data was performed on 162 patients with symptomatic carotid stenosis that were previously randomized to carotid artery stenting or carotid endarterectomy in the ICSS (International Carotid Stenting Study) and included in the magnetic resonance imaging substudy. Magnetic resonance imagings were performed 1 to 7 days before and 1 to 3 days after treatment. The primary composite clinical outcome was the time to any stroke or transient ischemic attack during follow-up. Patients with new diffusion-weighted imaging (DWI) lesions on posttreatment magnetic resonance imaging scan (DWI+) were compared with patients without new lesions (DWI-). RESULTS: The median time of follow-up was 8.6 years (interquartile range, 5.0-12.5). Kaplan-Meier cumulative incidence for the primary outcome after 12.5-year follow-up was 35.3% (SE, 8.9%) in DWI+ patients and 31.1% (SE, 5.6%) in DWI- patients. Uni- and multivariable regression analyses did not show significant differences (hazard ratio, 1.50 [95% CI, 0.76-2.94] and hazard ratio, 1.30 [95% CI, 0.10-1.02], respectively). Higher event rate of the primary outcome in DWI+ patients in the overall cohort was mainly caused by events in the carotid artery stenting group. CONCLUSIONS: Based on our outcome analysis within the ICSS magnetic resonance imaging substudy, DWI lesions following carotid revascularization did not seem to have a relationship with long-term stroke risk. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: ISRCTN 25337470.</p
Long Range Hydration Effects in Electrolytic Free Suspended Black Films
The force law within free suspended black films made of negatively charged
Aerosol-OT (AOT) with added LiCl or CsCl is studied accurately using X-ray
reflectivity (ca. 1{\AA}). We find an electrolyte concentration threshold above
which a substantial additional repulsion is detected in the LiCl films, up to
distances of 100 {\AA}. We interpret this phenomenon as an augmentation of the
Debye screening length, due to the local screening of the condensed hydrophilic
counterions by the primary hydration shell.Comment: 4 pages, 4 figures, to be published Phys. Rev. Let
A narrative review of plaque and brain imaging biomarkers for stroke risk stratification in patients with atherosclerotic carotid artery disease
Objective: In this narrative review, we aim to review imaging biomarkers that carry the potential to non-invasively guide stroke risk stratification for treatment optimization. Background: Carotid atherosclerosis plays a fundamental part in the occurrence of ischemic stroke. International guidelines select the optimal treatment strategy still mainly based on the presence of clinical symptoms and the degree of stenosis for stroke prevention in patients with atherosclerotic carotid plaques. These guidelines, based on randomized controlled trials that were conducted three decades ago, recommend carotid revascularization in symptomatic patients with high degree of stenosis versus a conservative approach for most asymptomatic patients. Due to optimization of best medical therapy and risk factor control, it is suggested that a subgroup of symptomatic patients is at lower risk of stroke and may not benefit from revascularization, whereas a selective subgroup of high-risk asymptomatic patients would benefit from this procedure. Methods: A literature search was performed for articles published up to December 2020 using PubMed, EMBASE and Scopus. Based on the literature found, change in stenosis degree and volume, plaque echolucency, plaque surface, intraplaque haemorrhage, lipid-rich necrotic core, thin fibrous cap, inflammation, neovascularization, microembolic signals, cerebrovascular reserve, intracranial collaterals, silent brain infarcts, diffusion weighted imaging lesions and white matters lesions have the potential to predict stroke risk. Conclusions: The applicability of imaging biomarkers needs to be further improved before the potential synergistic prognostic ability of imaging biomarkers can be verified on top of the clinical biomarkers. In the future, the routine and combined assessment of both plaque and brain imaging biomarkers might help to improve optimization of treatment strategies in individual patients with atherosclerotic carotid artery disease
Similar long-term outcomes for venous, bovine pericardial, and polyester patches for primary carotid endarterectomy
Background: Currently, the type of patch used for carotid endarterectomy closure depends on the preference of the operating surgeon. Various materials are available, including autologous venous patches, bovine pericardial patches (BPP), and synthetic patches. The purpose of this study was to compare the long-term outcomes. Methods: All patients who underwent primary carotid endarterectomy with patch angioplasty using a venous, bovine, or polyester patch between 2010 and 2020 at two high-volume medical centers were included in this retrospective analysis on largely prospectively collected data. Study endpoints included long-term ipsilateral transient ischemic attack or cerebrovascular accident, restenosis, reintervention, and all-cause mortality. Cox proportional hazard models were fitted to assess the effect of patch type to each outcome. Results: In total, 1481 CEAs were performed with a follow-up of 32 (13–65) months. Venous patch was used in 309 patients (20.9%), BPP in 1000 patients (67.5%), and polyester patch in 172 patients (11.6%). A preoperative symptomatic carotid artery stenosis of >50% was observed in 91.9% (n = 284) of the patients who received a venous patch, 92.1% (n = 921) of the patients who received BPP, and 90.7% (n = 156) of the patients who received a polyester patch (p = 0.799). Only in selected patients with an asymptomatic stenosis of >70% surgery was considered. Multivariable analyses showed no significant differences between the three patch types regarding long-term outcomes after adjusting for confounders. Conclusions: In patients undergoing primary carotid endarterectomy, the use of venous, bovine pericardial, or polyester patches seems equally safe and durable in terms of comparability in long-term outcomes
MiR-155 has a protective role in the development of non-alcoholic hepatosteatosis in mice
Hepatic steatosis is a global epidemic that is thought to contribute to the pathogenesis of type 2 diabetes. MicroRNAs (miRs) are regulators that can functionally integrate a range of metabolic and inflammatory pathways in liver. We aimed to investigate the functional role of miR-155 in hepatic steatosis. Male C57BL/6 wild-type (WT) and miR-155−/− mice were fed either normal chow or high fat diet (HFD) for 6 months then lipid levels, metabolic and inflammatory parameters were assessed in livers and serum of the mice. Mice lacking endogenous miR-155 that were fed HFD for 6 months developed increased hepatic steatosis compared to WT controls. This was associated with increased liver weight and serum VLDL/LDL cholesterol and alanine transaminase (ALT) levels, as well as increased hepatic expression of genes involved in glucose regulation (Pck1, Cebpa), fatty acid uptake (Cd36) and lipid metabolism (Fasn, Fabp4, Lpl, Abcd2, Pla2g7). Using miRNA target prediction algorithms and the microarray transcriptomic profile of miR-155−/− livers, we identified and validated that Nr1h3 (LXRα) as a direct miR-155 target gene that is potentially responsible for the liver phenotype of miR-155−/− mice. Together these data indicate that miR-155 plays a pivotal role regulating lipid metabolism in liver and that its deregulation may lead to hepatic steatosis in patients with diabetes
Structure-Specific Fermentation of Galacto-Oligosaccharides, Isomalto-Oligosaccharides and Isomalto/Malto-Polysaccharides by Infant Fecal Microbiota and Impact on Dendritic Cell Cytokine Responses
SCOPE: Next to galacto-oligosaccharides (GOS), starch-derived isomalto-oligosaccharide preparation (IMO) and isomalto/malto-polysaccharides (IMMP) could potentially be used as prebiotics in infant formulas. However, it remains largely unknown how the specific molecular structures of these non-digestible carbohydrates (NDCs) impact fermentability and immune responses in infants. METHODS AND RESULTS: In vitro fermentation of GOS, IMO and IMMP using infant fecal inoculum of 2- and 8-week-old infants showed that only GOS and IMO were fermented by infant fecal microbiota. The degradation of GOS and IMO coincided with an increase in Bifidobacterium and production of acetate and lactate, which was more pronounced with GOS. Individual isomers with an (1↔1)-linkage or di-substituted reducing terminal glucose residue were more resistant to fermentation. GOS, IMO and IMMP fermentation digesta attenuated cytokine profiles in immature dendritic cells (DCs), but the extent was dependent on the infants age and NDC structure. CONCLUSION: The IMO preparation, containing reducing and non-reducing isomers, showed similar fermentation patterns as GOS in fecal microbiota of 2-week-old infants. Knowledge obtained on the substrate specificities of infant fecal microbiota and the subsequent regulatory effects of GOS, IMO and IMMP on DC responses might contribute to the design of tailored NDC mixtures for infants of different age groups. This article is protected by copyright. All rights reserved
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