| 1. |
- Clemmensen, Tor Skibsted, et al.
(författare)
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Left Ventricular Pressure-Strain-Derived Myocardial Work at Rest and during Exercise in Patients with Cardiac Amyloidosis
- 2020
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Ingår i: Journal of the American Society of Echocardiography. - : MOSBY-ELSEVIER. - 0894-7317 .- 1097-6795. ; 33:5, s. 573-582
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Tidskriftsartikel (refereegranskat)abstract
- Background: Left ventricular pressure-strain-derived myocardial work index (LVMWI) is a novel, noninvasive method for left ventricular (LV) function evaluation in relation to LV pressure dynamics. LV global longitudinal strain (LVGLS) has proven benefit for diagnosis and risk stratification in patients with cardiac amyloidosis (CA), but LVGLS does not adjust for loading conditions. The aim of the present study was to characterize LVMWI at rest and during exercise in patients with CA. Methods: A total of 155 subjects were retrospectively included. These subjects comprised 100 patients with CA and 55 healthy control subjects. All patients had previously undergone comprehensive two-dimensional echocardiographic examinations at rest. Furthermore, a subgroup 27 patients with CA and 41 control subjects was examined using sennisu pine exercise stress echocardiography. Results: Patients with CA had significantly lower LVGLS, LVMWI, and LV myocardial work efficiency (LVMWE) than control subjects (P < .0001 for all). The reduction in LV myocardial performance was more pronounced in the basal segments, which led to significant alterations in the average apical-to-basal segmental ratios between patients with CA and control subjects (LVGLS, 2.6 [1.9 to 4.1] vs 1.3 [1.2 to 1.5]; LVMWI, 2.6 [1.7 to 3.8] vs 1.3 [1.1 to 1.5]; LVMWE, 1.1 [1.0 to 1.3] vs 1.0 [1.0 to 1.1]; P < .0001 for all). The average increase in LVMWI from rest to peak exercise was 1,974 mm Hg% (95% CI, 1,699 to 2,250 mm Hg%; P < .0001) in control subjects and 496 mm Hg% (95% CI, 156 to 835 mm Hg%; P < .01) in patients with CA. The absolute numeric LVGLS increase was 5.6% (95% CI, 3.9% to 7.3%; P < .0001) in control subjects and only 1.2% (95% CI, -0.9% to 3.3%; P = .26) in patients with CA (between groups, P < .0001) from rest to peak exercise. The LVMWI increase in patients with CA was mediated by improvement in the apical segments (P < .0001), whereas there was no significant LVMWI alterations in the midventricular or basal segments. LVMWE remained stable during exercise in control subjects (Delta -0.6%; 95% CI, -2.5% to 1.2%; P = .50) but decreased significantly in patients with CA (Delta -2.5%; 95% CI, -4.8% to -0.2%; P < .05). Conclusions: Patients with CA have significantly reduced magnitude of LVMWI compared with healthy control subjects. With exercise, the differences are even more pronounced. Even though LVMWI increased with exercise, LVMWE decreased, suggesting inefficient myocardial energy exploitation in patients with CA.
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| 2. |
- Langer, Fabian, et al.
(författare)
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Few-cycle lightwave-driven currents in a semiconductor at high repetition rate
- 2020
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Ingår i: Optica. - 2334-2536. ; 7:4, s. 276-279
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Tidskriftsartikel (refereegranskat)abstract
- When an intense, few-cycle light pulse impinges on a dielectric or semiconductor material, the electric field will interact nonlinearly with the solid, driving a coherent current. An asymmetry of the ultrashort, carrier-envelope-phase-stable waveform results in a net transfer of charge, which can be measured by macroscopic electric contact leads. This effect has been pioneered with extremely short, single-cycle laser pulses at low repetition rate, thus limiting the applicability of its potential for ultrafast electronics. We investigate lightwave-driven currents in gallium nitride using few-cycle laser pulses of nearly twice the duration and at a repetition rate 2 orders of magnitude higher than in previous work. We successfully simulate our experimental data with a theoretical model based on interfering multiphoton transitions, using the exact laser pulse shape retrieved from dispersion-scan measurements. Substantially increasing the repetition rate and relaxing the constraint on the pulse duration marks an important step forward toward applications of controlling currents with light.
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| 3. |
- Rosengren, Sara, et al.
(författare)
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Diagnostic Accuracy of [11C]PIB Positron Emission Tomography for Detection of Cardiac Amyloidosis
- 2020
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Ingår i: JACC Cardiovascular Imaging. - : Elsevier BV. - 1936-878X .- 1876-7591. ; 13:6, s. 1337-1347
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: This dual-site study evaluated the diagnostic accuracy of the method.BACKGROUND: Pittsburgh compound ([11C]PIB) positron emission tomography (PIB-PET) has shown promise as a specific and noninvasive method for the diagnosis of cardiac amyloidosis (CA).METHODS: The study had 2 parts. In the initial study, 51 subjects were included, 36 patients with known CA and increased wall thickness (15 immunoglobulin light chain [AL] and 21 transthyretin [ATTR] amyloidosis) and 15 control patients (7 were nonamyloid hypertrophic and 8 healthy volunteers). Subjects underwent PIB-PET and echocardiography. Sensitivity and specificity of PIB-PET were established for 2 simple semiquantitative approaches, standardized uptake value ratio (SUVR) and retention index (RI). The second part of the study included 11 amyloidosis patients (5 AL and 6 hereditary ATTR) without increased wall thickness to which the optimal cutoff values of SUVR (>1.09) and RI (>0.037 min-1) were applied prospectively.RESULTS: The diagnostic accuracy of visual inspection of [11C]PIB uptake was 100% in discriminating CA patients with increased wall thickness from controls. Semiquantitative [11C]PIB uptake discriminated CA from controls with a 94% (95% confidence interval [CI]: 80% to 99%) sensitivity for both SUVR and RI and specificity of 93% (95% CI: 66% to 100%) for SUVR and 100% (95% CI: 75% to 100%) for RI. [11C]PIB uptake was significantly higher in AL-CA than in ATTR-CA patients (p < 0.001) and discriminated AL-CA from controls with 100% (95% CI: 88% to 100%) accuracy for both the semiquantitative measures. In the prospective group without increased wall thickness, RI was elevated compared to controls (p = 0.001) and 5 of 11 subjects were evaluated as [11C]PIB PET positive.CONCLUSIONS: In a dual-center setting, [11C]PIB PET was highly accurate in detecting cardiac involvement in the main amyloid subtypes, with 100% accuracy in AL amyloidosis. A proportion of amyloidosis patients without known cardiac involvement were [11C]PIB PET positive, indicating that the method may detect early stages of CA.
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| 4. |
- Skibsted Clemmensen, Tor, et al.
(författare)
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Prognostic implications of left ventricular myocardial work indices in cardiac amyloidosis
- 2021
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Ingår i: European Heart Journal Cardiovascular Imaging. - : Oxford University Press. - 2047-2404 .- 2047-2412. ; 22:6, s. 695-704
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Left ventricular (LV) myocardial work index (LVMWI) derived from pressure-strain analysis resembles a novel non-invasive method for LV function evaluation. LV global longitudinal strain (LVGLS) has proven beneficial for risk stratification in cardiac amyloidosis (CA) patients. This study aimed to evaluate the potential additive value of LVMWI for outcome prediction in CA patients.METHODS AND RESULTS: We enrolled 100 CA patients in the period 2014-19 from Aarhus University Hospital, Denmark and Uppsala University Hospital, Sweden. All patients underwent comprehensive echocardiographic evaluation and were prospectively followed until censuring date on 31 March 2019 or death. During follow-up, we registered major adverse cardiac events (MACE) comprising heart failure requiring hospitalization and all-cause mortality. The median follow-up was 490 (228-895) days. During follow-up, a total of 42% of patients experienced MACE and 29% died. Patients with LVMWI <1043 mmHg% had higher MACE risk than patients with LVMWI >1043 mmHg% [hazard ratio (HR) 2.3, 95% confidence interval (CI) 1.2-4.3; P = 0.01]. Furthermore, patients with LVMWI <1039 mmHg% also had higher all-cause mortality risk than patients with LVMWI >1039 mmHg% (HR 2.6, 95% CI 1.2-5.5; P < 0.05). Moreover, the apical-to-basal segmental work ratio was a significant MACE and all-cause mortality predictor. By combining LVMWI and apical-to-basal segmental work ratio, we obtained an independent model for all-cause mortality prediction (high vs. low risk: HR 6.4, 95% CI 2.4-17.1; P < 0.0001). In contrast, LVGLS did not predict all-cause mortality.CONCLUSION: LV myocardial work may be of prognostic value in CA patients by predicting both MACE and all-cause mortality.
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| 5. |
- Ståhl, Jan Eric, et al.
(författare)
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A Concept from Sensor to Sustainability in Machining - An Interdisciplinary Approach over a Wide TRL Range
- 2024
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Ingår i: Proceedings of the 11th Swedish Production Symposium (SPS2024) : Sustainable Production through Advanced Manufacturing, Intelligent Automation and Work Integrated Learning - Sustainable Production through Advanced Manufacturing, Intelligent Automation and Work Integrated Learning. - 2352-751X .- 2352-7528. - 9781643685106 - 9781643685113 ; 52, s. 148-170
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Konferensbidrag (refereegranskat)abstract
- This publication describes a concept that intends to enable an optimization of machining with regard to the balance between criteria related to technology, economy and sustainability. The work is of a discussion nature and intends to provide a framework for further research and development in the area. Previous research and development during the 80's and 90's is presented in general terms and in particular the reasons for its limited success in providing real-time feedback on machining operations are highlighted, despite very large financial investments even by today's standards. Ongoing research worldwide in current process optimization and its associated building blocks will be highlighted, and identified important work is referenced. Below are new conditions that can be linked to both process knowledge and its modeling, as well as new conditions for developing integrated sensors that can handle the extreme environment in and around a processing operation. A previous limiting factor has been signal processing and signal transmission, which with new knowledge and developed technology in the last 10 years provides new conditions for process optimization in real time.The need for new and up-to-date principles for process optimization, which also integrate sustainability issues and environmental impact, has increased in importance in several respects. Important issues such as tool utilization, efficient use of materials and high time utilization have become relevant as these process results control both energy consumption and environmental impact. The geopolitical development linked to the availability of critical tool materials such as cobalt and tungsten also drives research issues that can generally optimize and streamline production processes.Finally, the publication describes the possibility of realizing a real-time feedback and optimized machining that takes into account technology, economy and sustainability, through interdisciplinary research across several levels of technology readiness (TRL). The results are expected to have positive effects on several production factors before, during and after machining. Developed technologies in machining can also make valuable contributions to the development of other products and production processes.
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