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- 2019
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Alexander, John H., et al.
(författare)
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Apixaban with Antiplatelet Therapy after Acute Coronary Syndrome
- 2011
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 365:8, s. 699-708
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Tidskriftsartikel (refereegranskat)abstract
- Background: Apixaban, an oral, direct factor Xa inhibitor, may reduce the risk of recurrent ischemic events when added to antiplatelet therapy after an acute coronary syndrome.Methods: We conducted a randomized, double-blind, placebo-controlled clinical trial comparing apixaban, at a dose of 5 mg twice daily, with placebo, in addition to standard antiplatelet therapy, in patients with a recent acute coronary syndrome and at least two additional risk factors for recurrent ischemic events.Results: The trial was terminated prematurely after recruitment of 7392 patients because of an increase in major bleeding events with apixaban in the absence of a counterbalancing reduction in recurrent ischemic events. With a median follow-up of 241 days, the primary outcome of cardiovascular death, myocardial infarction, or ischemic stroke occurred in 279 of the 3705 patients (7.5%) assigned to apixaban (13.2 events per 100 patient-years) and in 293 of the 3687 patients (7.9%) assigned to placebo (14.0 events per 100 patient-years) (hazard ratio with apixaban, 0.95; 95% confidence interval [CI], 0.80 to 1.11; P = 0.51). The primary safety outcome of major bleeding according to the Thrombolysis in Myocardial Infarction (TIMI) definition occurred in 46 of the 3673 patients (1.3%) who received at least one dose of apixaban (2.4 events per 100 patient-years) and in 18 of the 3642 patients (0.5%) who received at least one dose of placebo (0.9 events per 100 patient-years) (hazard ratio with apixaban, 2.59; 95% CI, 1.50 to 4.46; P = 0.001). A greater number of intracranial and fatal bleeding events occurred with apixaban than with placebo.Conclusions: The addition of apixaban, at a dose of 5 mg twice daily, to antiplatelet therapy in high-risk patients after an acute coronary syndrome increased the number of major bleeding events without a significant reduction in recurrent ischemic events.
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- Kroepelin, S, et al.
(författare)
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Climate-driven ecosystem succession in the Sahara: The past 6000 years
- 2008
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 320:5877, s. 765-768
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Tidskriftsartikel (refereegranskat)abstract
- Desiccation of the Sahara since the middle Holocene has eradicated all but a few natural archives recording its transition from a "green Sahara" to the present hyperarid desert. Our continuous 6000- year paleoenvironmental reconstruction from northern Chad shows progressive drying of the regional terrestrial ecosystem in response to weakening insolation forcing of the African monsoon and abrupt hydrological change in the local aquatic ecosystem controlled by site- specific thresholds. Strong reductions in tropical trees and then Sahelian grassland cover allowed large- scale dust mobilization from 4300 calendar years before the present ( cal yr B. P.). Today's desert ecosystem and regional wind regime were established around 2700 cal yr B. P. This gradual rather than abrupt termination of the African Humid Period in the eastern Sahara suggests a relatively weak biogeophysical feedback on climate.
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- Bhatt, Deepak L., et al.
(författare)
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Rationale, design and baseline characteristics of the effect of ticagrelor on health outcomes in diabetes mellitus patients Intervention study
- 2019
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Ingår i: Clinical Cardiology. - : Wiley. - 0160-9289 .- 1932-8737. ; 42:5, s. 498-505
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Tidskriftsartikel (refereegranskat)abstract
- In the setting of prior myocardial infarction, the oral antiplatelet ticagrelor added to aspirin reduced the risk of recurrent ischemic events, especially, in those with diabetes mellitus. Patients with stable coronary disease and diabetes are also at elevated risk and might benefit from dual antiplatelet therapy. The Effect of Ticagrelor on Health Outcomes in diabEtes Mellitus patients Intervention Study (THEMIS, NCT01991795) is a Phase 3b randomized, double-blinded, placebo-controlled trial of ticagrelor vs placebo, on top of low dose aspirin. Patients >= 50 years with type 2 diabetes receiving anti-diabetic medications for at least 6 months with stable coronary artery disease as determined by a history of previous percutaneous coronary intervention, bypass grafting, or angiographic stenosis of >= 50% of at least one coronary artery were enrolled. Patients with known prior myocardial infarction (MI) or stroke were excluded. The primary efficacy endpoint is a composite of cardiovascular death, myocardial infarction, or stroke. The primary safety endpoint is Thrombolysis in Myocardial Infarction major bleeding. A total of 19 220 patients worldwide have been randomized and at least 1385 adjudicated primary efficacy endpoint events are expected to be available for analysis, with an expected average follow-up of 40 months (maximum 58 months). Most of the exposure is on a 60 mg twice daily dose, as the dose was lowered from 90 mg twice daily partway into the study. The results may revise the boundaries of efficacy for dual antiplatelet therapy and whether it has a role outside acute coronary syndromes, prior myocardial infarction, or percutaneous coronary intervention.
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| 9. |
- Brambatti, Michela, et al.
(författare)
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Comparison of dabigatran versus warfarin in diabetic patients with atrial fibrillation : Results from the RE-LY trial
- 2015
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 196, s. 127-131
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Diabetes mellitus (DM) is frequent among patients with atrial fibrillation (AF). The RE-LY trial permits evaluation of patient characteristics, outcomes and the effectiveness of dabigatran etexilate among diabetic individuals. Methods: Patient characteristics and outcomes were compared between diabetic and non-diabetic patients and the relative efficacy of each dose of dabigatran (150 mg bid and 110 mg bid) versus warfarin was evaluated. Results: Of 18,113 patients in RE-LY, 4221 patients (23.3%) had DM. Patients with DM were younger (70.9 vs. 71.7 years), more likely to have hypertension (86.6% vs. 76.5%), coronary artery disease (37.4% vs. 24.9%) and peripheral vascular disease (5.6% vs. 3.2%); (all p < 0.01). Time in therapeutic range for warfarin-treated patients was 65% for diabetic versus 68% for non-diabetic patients (p < 0.001). Regardless of assigned treatment, stroke or systemic embolism was more common among patients with DM (1.9% per year vs. 1.3% per year, p < 0.001). DM was also associated with an increased risk of death (5.1% per year vs. 3.5% per year, p < 0.001) and major bleeding (4.2% per year vs. 3.0% per year, p < 0.001). The absolute reduction in stroke or systemic embolism with dabigatran compared to warfarin was greater among patients with DM than those without DM (dabigatran 110 mg: 0.59% per year vs. 0.05% per year; dabigatran 150 mg: 0.89% per year vs. 0.51% per year). Conclusions: Compared to non-DM patients, AF patients with DM derive a greater absolute risk reduction in embolic events when treated with dabigatran. ClinicalTrials.gov Identifier: NCT00262600.
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- Connolly, Stuart J., et al.
(författare)
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The Long-Term Multicenter Observational Study of Dabigatran Treatment in Patients With Atrial Fibrillation (RELY-ABLE) Study
- 2013
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Ingår i: Circulation. - 0009-7322 .- 1524-4539. ; 128:3, s. 237-243
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Tidskriftsartikel (refereegranskat)abstract
- Background During follow-up of between 1 and 3 years in the Randomized Evaluation of Long-term Anticoagulation Therapy (RE-LY) trial, 2 doses of dabigatran etexilate were shown to be effective and safe for the prevention of stroke or systemic embolism in patients with atrial fibrillation. There is a need for longer-term follow-up of patients on dabigatran and for further data comparing the 2 dabigatran doses. Methods and Results Patients randomly assigned to dabigatran in RE-LY were eligible for the Long-term Multicenter Extension of Dabigatran Treatment in Patients with Atrial Fibrillation (RELY-ABLE) trial if they had not permanently discontinued study medication at the time of their final RE-LY study visit. Enrolled patients continued to receive the double-blind dabigatran dose received in RE-LY, for up to 28 months of follow up after RE-LY (median follow-up, 2.3 years). There were 5851 patients enrolled, representing 48% of patients originally randomly assigned to receive dabigatran in RE-LY and 86% of RELY-ABLE-eligible patients. Rates of stroke or systemic embolism were 1.46% and 1.60%/y on dabigatran 150 and 110 mg twice daily, respectively (hazard ratio, 0.91; 95% confidence interval, 0.69-1.20). Rates of major hemorrhage were 3.74% and 2.99%/y on dabigatran 150 and 110 mg (hazard ratio, 1.26; 95% confidence interval, 1.04-1.53). Rates of death were 3.02% and 3.10%/y (hazard ratio, 0.97; 95% confidence interval, 0.80-1.19). Rates of hemorrhagic stroke were 0.13% and 0.14%/y. Conclusions During 2.3 years of continued treatment with dabigatran after RE-LY, there was a higher rate of major bleeding with dabigatran 150 mg twice daily in comparison with 110 mg, and similar rates of stroke and death.
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- Ebrahimi-Fakhari, Darius, et al.
(författare)
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Defining the clinical, molecular and imaging spectrum of adaptor protein complex 4-associated hereditary spastic paraplegia
- 2020
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Ingår i: Brain. - OXFORD ENGLAND : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 143:10, s. 2929-2944
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Tidskriftsartikel (refereegranskat)abstract
- Bi-allelic loss-of-function variants in genes that encode subunits of the adaptor protein complex 4 (AP-4) lead to prototypical yet poorly understood forms of childhood-onset and complex hereditary spastic paraplegia: SPG47 (AP4B1), SPG50 (AP4M1), SPG51 (AP4E1) and SPG52 (AP4S1). Here, we report a detailed cross-sectional analysis of clinical, imaging and molecular data of 156 patients from 101 families. Enrolled patients were of diverse ethnic backgrounds and covered a wide age range (1.0-49.3 years). While the mean age at symptom onset was 0.8 +/- 0.6 years [standard deviation (SD), range 0.2-5.0], the mean age at diagnosis was 10.2 +/- 8.5 years (SD, range 0.1-46.3). We define a set of core features: early-onset developmental delay with delayed motor milestones and significant speech delay (50% non-verbal); intellectual disability in the moderate to severe range; mild hypotonia in infancy followed by spastic diplegia (mean age: 8.4 +/- 5.1 years, SD) and later tetraplegia (mean age: 16.1 +/- 9.8 years, SD); postnatal microcephaly (83%); foot deformities (69%); and epilepsy (66%) that is intractable in a subset. At last follow-up, 36% ambulated with assistance (mean age: 8.9 +/- 6.4 years, SD) and 54% were wheelchair-dependent (mean age: 13.4 +/- 9.8 years, SD). Episodes of stereotypic laughing, possibly consistent with a pseudobulbar affect, were found in 56% of patients. Key features on neuroimaging include a thin corpus callosum (90%), ventriculomegaly (65%) often with colpocephaly, and periventricular white-matter signal abnormalities (68%). Iron deposition and polymicrogyria were found in a subset of patients. AP4B1-associated SPG47 and AP4M1-associated SPG50 accounted for the majority of cases. About two-thirds of patients were born to consanguineous parents, and 82% carried homozygous variants. Over 70 unique variants were present, the majority of which are frameshift or nonsense mutations. To track disease progression across the age spectrum, we defined the relationship between disease severity as measured by several rating scales and disease duration. We found that the presence of epilepsy, which manifested before the age of 3 years in the majority of patients, was associated with worse motor outcomes. Exploring genotype-phenotype correlations, we found that disease severity and major phenotypes were equally distributed among the four subtypes, establishing that SPG47, SPG50, SPG51 and SPG52 share a common phenotype, an 'AP-4 deficiency syndrome'. By delineating the core clinical, imaging, and molecular features of AP-4-associated hereditary spastic paraplegia across the age spectrum our results will facilitate early diagnosis, enable counselling and anticipatory guidance of affected families and help define endpoints for future interventional trials.
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| 15. |
- Herrmann, Jochen, et al.
(författare)
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European Society of Pediatric Radiology survey of perioperative imaging in pediatric liver transplantation: (1) pre-transplant evaluation.
- 2024
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Ingår i: Pediatric radiology. - 1432-1998. ; 54:2, s. 260-268
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Tidskriftsartikel (refereegranskat)abstract
- Liver transplantation is the state-of-the-art curative treatment in end-stage liver disease. Imaging is a key element for successful organ-transplantation to assist surgical planning. So far, only limited data regarding the best radiological approach to prepare children for liver transplantation is available.In an attempt to harmonize imaging surrounding pediatric liver transplantation, the European Society of Pediatric Radiology (ESPR) Abdominal Taskforce initiated a survey addressing the current status of imaging including the pre-, intra-, and postoperative phase. This paper reports the responses on preoperative imaging.An online survey, initiated in 2021, asked European centers performing pediatric liver transplantation 44 questions about their imaging approach. In total, 26 centers were contacted and 22 institutions from 11 countries returned the survey. From 2018 to 2020, the participating centers collectively conducted 1,524 transplantations, with a median of 20 transplantations per center per annum (range, 8-60).Most sites (64%) consider ultrasound their preferred modality to define anatomy and to plan surgery in children before liver transplantation, and additional cross-sectional imaging is only used to answer specific questions (computed tomography [CT], 90.9%; magnetic resonance imaging [MRI], 54.5%). One-third of centers (31.8%) rely primarily on CT for pre-transplant evaluation. Imaging protocols differed substantially regarding applied CT scan ranges, number of contrast phases (range 1-4 phases), and applied MRI techniques.Diagnostic imaging is generally used in the work-up of children before liver transplantation. Substantial differences were noted regarding choice of modalities and protocols. We have identified starting points for future optimization and harmonization of the imaging approach to multicenter studies.
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- Hijazi, Ziad, et al.
(författare)
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Apixaban or Vitamin K Antagonists and Aspirin or Placebo According to Kidney Function in Patients With Atrial Fibrillation After Acute Coronary Syndrome or Percutaneous Coronary Intervention : Insights From the AUGUSTUS Trial
- 2021
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Ingår i: Circulation. - : Lippincott Williams & Wilkins. - 0009-7322 .- 1524-4539. ; 143:12, s. 1215-1223
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Tidskriftsartikel (refereegranskat)abstract
- Background: In the AUGUSTUS trial (An Open-Label, 2x2 Factorial, Randomized Controlled, Clinical Trial to Evaluate the Safety of Apixaban Versus Vitamin K Antagonist and Aspirin Versus Aspirin Placebo in Patients With Atrial Fibrillation and Acute Coronary Syndrome or Percutaneous Coronary Intervention), apixaban resulted in less bleeding and fewer hospitalizations than vitamin K antagonists, and aspirin caused more bleeding than placebo in patients with atrial fibrillation and acute coronary syndrome or percutaneous coronary intervention treated with a P2Y(12) inhibitor. We evaluated the risk-benefit balance of antithrombotic therapy according to kidney function.Methods: In 4456 patients, the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) formula was used to calculate baseline estimated glomerular filtration rate (eGFR). The effect of apixaban versus vitamin K antagonists and aspirin versus placebo was assessed across kidney function categories by using Cox models. The primary outcome was International Society on Thrombosis and Haemostasis major or clinically relevant nonmajor bleeding. Secondary outcomes included death or hospitalization and ischemic events (death, stroke, myocardial infarction, stent thrombosis [definite or probable], or urgent revascularization). Creatinine clearanceResults: Overall, 30%, 52%, and 19% had an eGFR of >80, >50 to 80, and 30 to 50 mL.min(-1).1.73 m(-2), respectively. At the 6-month follow-up, a total of 543 primary outcomes of bleeding, 1125 death or hospitalizations, and 282 ischemic events occurred. Compared with vitamin K antagonists, patients assigned apixaban had lower rates for all 3 outcomes across most eGFR categories without significant interaction. The absolute risk reduction with apixaban was most pronounced in those with an eGFR of 30 to 50 mL.min(-1).1.73 m(-2) for bleeding events with rates of 13.1% versus 21.3% (hazard ratio, 0.59; 95% CI, 0.41-0.84). Patients assigned aspirin had a higher risk of bleeding in all eGFR categories with an even greater increase among those with eGFR >80 mL.min(-1).1.73 m(-2): 16.6% versus 5.6% (hazard ratio, 3.22; 95% CI, 2.19-4.74; P for interaction=0.007). The risk of death or hospitalization and ischemic events were comparable to aspirin and placebo across eGFR categories with hazard ratios ranging from 0.97 (95% CI, 0.76-1.23) to 1.28 (95% CI, 1.02-1.59) and from 0.75 (95% CI, 0.48-1.17) to 1.34 (95% CI, 0.81-2.22), respectively.Conclusions: The safety and efficacy of apixaban was consistent irrespective of kidney function, compared with warfarin, and in accordance with the overall trial results. The risk of bleeding with aspirin was consistently higher across all kidney function categories.
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- Levis, Brooke, et al.
(författare)
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Comparison of major depression diagnostic classification probability using the SCID, CIDI, and MINI diagnostic interviews among women in pregnancy or postpartum : An individual participant data meta-analysis
- 2019
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Ingår i: International Journal of Methods in Psychiatric Research. - : WILEY. - 1049-8931 .- 1557-0657. ; 28:4
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: A previous individual participant data meta-analysis (IPDMA) identified differences in major depression classification rates between different diagnostic interviews, controlling for depressive symptoms on the basis of the Patient Health Questionnaire-9. We aimed to determine whether similar results would be seen in a different population, using studies that administered the Edinburgh Postnatal Depression Scale (EPDS) in pregnancy or postpartum.Methods: Data accrued for an EPDS diagnostic accuracy IPDMA were analysed. Binomial generalised linear mixed models were fit to compare depression classification odds for the Mini International Neuropsychiatric Interview (MINI), Composite International Diagnostic Interview (CIDI), and Structured Clinical Interview for DSM (SCID), controlling for EPDS scores and participant characteristics.Results Among fully structured interviews, the MINI (15 studies, 2,532 participants, 342 major depression cases) classified depression more often than the CIDI (3 studies, 2,948 participants, 194 major depression cases; adjusted odds ratio [aOR] = 3.72, 95% confidence interval [CI] [1.21, 11.43]). Compared with the semistructured SCID (28 studies, 7,403 participants, 1,027 major depression cases), odds with the CIDI (interaction aOR = 0.88, 95% CI [0.85, 0.92]) and MINI (interaction aOR = 0.95, 95% CI [0.92, 0.99]) increased less as EPDS scores increased.Conclusion Different interviews may not classify major depression equivalently.
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| 19. |
- Lopes, Renato D., et al.
(författare)
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Antithrombotic Therapy after Acute Coronary Syndrome or PCI in Atrial Fibrillation
- 2019
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Ingår i: New England Journal of Medicine. - : MASSACHUSETTS MEDICAL SOC. - 0028-4793 .- 1533-4406. ; 380:16, s. 1509-1524
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Tidskriftsartikel (refereegranskat)abstract
- Background Appropriate antithrombotic regimens for patients with atrial fibrillation who have an acute coronary syndrome or have undergone percutaneous coronary intervention (PCI) are unclear. Methods In an international trial with a two-by-two factorial design, we randomly assigned patients with atrial fibrillation who had an acute coronary syndrome or had undergone PCI and were planning to take a P2Y(12) inhibitor to receive apixaban or a vitamin K antagonist and to receive aspirin or matching placebo for 6 months. The primary outcome was major or clinically relevant nonmajor bleeding. Secondary outcomes included death or hospitalization and a composite of ischemic events. Results Enrollment included 4614 patients from 33 countries. There were no significant interactions between the two randomization factors on the primary or secondary outcomes. Major or clinically relevant nonmajor bleeding was noted in 10.5% of the patients receiving apixaban, as compared with 14.7% of those receiving a vitamin K antagonist (hazard ratio, 0.69; 95% confidence interval [CI], 0.58 to 0.81; P<0.001 for both noninferiority and superiority), and in 16.1% of the patients receiving aspirin, as compared with 9.0% of those receiving placebo (hazard ratio, 1.89; 95% CI, 1.59 to 2.24; P<0.001). Patients in the apixaban group had a lower incidence of death or hospitalization than those in the vitamin K antagonist group (23.5% vs. 27.4%; hazard ratio, 0.83; 95% CI, 0.74 to 0.93; P=0.002) and a similar incidence of ischemic events. Patients in the aspirin group had an incidence of death or hospitalization and of ischemic events that was similar to that in the placebo group. Conclusions In patients with atrial fibrillation and a recent acute coronary syndrome or PCI treated with a P2Y(12) inhibitor, an antithrombotic regimen that included apixaban, without aspirin, resulted in less bleeding and fewer hospitalizations without significant differences in the incidence of ischemic events than regimens that included a vitamin K antagonist, aspirin, or both.
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- Quintana, C., et al.
(författare)
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High Speed Electro-Absorption Modulator for Long Range Retroreflective Free Space Optics
- 2017
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 29:9, s. 707-710
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we present the design and implementation of a pixelated electro-absorption modulator-based modulating retroreflector (MRR) for high-speed optical wireless communications. The modulator is based on a multiple quantum well structure embedded in an asymmetric Fabry-Perot cavity. This MRR was used in an outdoor link, operating at 150 Mb/s with a bit error rate (BER) of 1.22 × 10-6 at a range of 200 m. The system was also tested in laboratory-controlled conditions achieving a data rate of 200 Mb/s with a BER of 2 × 10-4. To the best of our knowledge, this is the fastest retroreflective free-space optics demonstration in both the indoor and outdoor environments.
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- Sherwood, Matthew W, et al.
(författare)
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Apixaban following acute coronary syndromes in patients with prior stroke : Insights from the APPRAISE-2 trial
- 2018
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Ingår i: American Heart Journal. - : Elsevier BV. - 0002-8703 .- 1097-6744. ; 197, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Patients with prior stroke are at greater risk for recurrent cardiovascular events post-acute coronary syndromes (ACS) and may have a different risk/benefit profile with antithrombotic therapy than patients without prior stroke.METHODS: We studied 7391 patients with ACS from APPRAISE-2, stratified by the presence or absence of prior stroke. Baseline characteristics and outcomes of cardiovascular death, myocardial infarction (MI), or stroke were compared between groups. Interactions between prior stroke, treatment assignment (apixaban vs placebo), and outcomes were tested before and after multivariable adjustment with Cox proportional hazards models.RESULTS: A total of 902 patients (12%) had prior stroke. Those with prior stroke were older (69 vs 67 years), had more hypertension (91% vs 77%), peripheral vascular disease (22% vs18%), and impaired renal function (38% vs 30%) but less diabetes (44% vs 48%) than those without prior stroke. Patients with prior stroke vs no prior stroke had higher unadjusted rates of cardiovascular death (4.8% vs 4.0%), MI (11.2% vs 7.1%), and ischemic stroke (3.2% vs 0.9%). Patients with prior stroke assigned to apixaban had similar rates of the composite of cardiovascular death, MI, or stroke compared with those assigned to placebo (HR 1.39; 95% CI 0.92-2.08). Patients without prior stroke assigned to apixaban had similar rates of cardiovascular death, MI, or ischemic stroke compared with those assigned to placebo (HR 0.87; 95% CI 0.73-1.04; P-interaction=.041). Median follow-up was 240 days.CONCLUSIONS: Patients with prior stroke are at higher risk for recurrent cardiovascular events post-ACS and had a differential risk/benefit profile with oral anticoagulation.
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| 28. |
- Ta, Huy Q., et al.
(författare)
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Single Cr atom catalytic growth of graphene
- 2018
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Ingår i: Nano Reseach. - : TSINGHUA UNIV PRESS. - 1998-0124 .- 1998-0000. ; 11:5, s. 2405-2411
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Tidskriftsartikel (refereegranskat)abstract
- Single atoms are the ultimate minimum size limit for catalysts. Graphene, as an exciting, ultimately thin (one atom thick) material can be imaged in a transmission electron microscope with relatively few imaging artefacts. Here, we directly observe the behavior of single Cr atoms in graphene mono- and di-vacancies and, more importantly, at graphene edges. Similar studies at graphene edges with other elemental atoms, with the exception of Fe, show catalytic etching of graphene. Fe atoms have been shown to both etch and grow graphene. In contrast, Cr atoms are only observed to induce graphene growth. Complementary theoretical calculations illuminate the differences between Fe and Cr, and confirm single Cr atoms as superior catalysts for sp(2) carbon growth.
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