Line-focus solar concentration 10 times higher than the 2D thermodynamic limit.

Line-focus solar concentrators have traditionally been limited by the 2D concentration limit due to the continuous translational symmetry in these systems. This limit is orders of magnitude lower than the 3D limit, severely limiting the achievable concentration ratio compared to point-focus systems. We propose a design principle for line-focus solar concentrators that bypasses this 2D limit, while maintaining a trough-like configuration and only requiring single-axis external solar tracking. This is achieved by combining the concept of étendue squeezing with the concept of tracking integration. To demonstrate the principle, we present a design example that achieves a simulated average yearly efficiency of 80% at a geometric concentration of 335x under light with a ±9mrad angular distribution and horizontal single-axis external tracking. We also show how the same design principle can achieve a line-focus with 1563x geometric concentration at 90% efficiency if design constraints are relaxed by foregoing tracking-integration and assuming two-axis external solar tracking. This design principle opens up the design space for high-concentration line-focus solar concentrators, and may contribute to a reconsideration of the trade-off between concentration and acceptance angle in such systems.

Beyond the 2D limit: étendue-squeezing line-focus solar concentrators.

Line-focus solar concentrators are commonly designed by extruding a two-dimensional concentrator in the third dimension. For concentration in air, these concentrators are, by the nature of their design, limited by the two-dimensional solar concentration limit of 212×. This limit is orders of magnitude lower than the 45000× concentration limit for three-dimensional solar concentrators. Through the use of étendue squeezing, we conceptually show that it is possible to design line-focus solar concentrators beyond this 2D limit. This allows a concentrator to benefit from a line focus suitable for heat extraction through a tubular receiver, while reaching concentration ratios and acceptance angles previously unseen for line-focus concentrators. We show two design examples, achieving simulated 75× concentration and 218× concentration ratios, with a ±1∘ acceptance angle. For comparison, the 2D concentration limit is 57× at this acceptance angle. Étendue-squeezing line-focus solar concentrators, combined with recent developments in tracking integration, may enable the development of a new class of concentrated solar power systems.

Platelet count and risk of major bleeding in venous thromboembolism.

The relationship between platelet count and risk of major bleeding in patients with venous thromboembolism (VTE) during anticoagulation remains unclear. We therefore investigated the association between platelet count, measured at VTE diagnosis and before the thrombotic event, and risk of major bleeding. Participants comprised 744 patients with incident VTE derived from the Tromsø Study. Major bleedings were recorded during the first year after VTE. Cox-regression was used to calculate hazard ratios (HRs) for major bleeding across platelet count quartiles.There were 55 major bleedings (incidence rate 9.1/100 person-years, 95% confidence interval [CI] 7.0-11.8). The major bleeding risk increased across quartiles of platelet count measured at VTE diagnosis (P for trend<0.02). In the age- and sex-adjusted model, subjects with platelet count in the highest quartile (≥300x109/L) had a 4.3-fold (95% CI 1.7-10.9) higher risk of major bleeding compared to those with platelet count in the lowest quartile (≤192x109/L), and exclusion of patients with cancer yielded similar results. When platelet count was measured on average 7 years before a VTE, the corresponding HR was 2.5 (95% CI 0.9-6.7). Our results suggest that increasing platelet count, assessed several years before and at VTE diagnosis, is associated with a higher risk of major bleeding, and could be a stable individual marker of major bleeding risk in VTE-patients.

High-performance stationary solar tracking through multi-objective optimization of beam-steering lens arrays.

Beam-steering lens arrays enable solar tracking using millimeter-scale relative translation between a set of lens arrays. This may represent a promising alternative to the mechanical bulk of conventional solar trackers, but until now a thorough exploration of possible configurations has not been carried out. We present an approach for designing beam-steering lens arrays based on multi-objective optimization, quantifying the trade-off between beam divergence and optical efficiency. Using this approach, we screen and optimize a large number of beam-steering lens array configurations, and identify new and promising configurations. We present a design capable of redirecting sunlight into a <2° divergence half-angle, with 73.4% average yearly efficiency, as well as a simplified design achieving 75.4% efficiency with a <3.5° divergence half-angle. These designs indicate the potential of beam-steering lens arrays for enabling low-cost solar tracking for stationary solar concentrators.

Emerging Horizons in Heart Failure with Preserved Ejection Fraction: The Role of SGLT2 Inhibitors.

Heart failure with preserved ejection fraction (HFpEF) is a condition with increasing disease burden. Prevalence of HFpEF is increasing, reflecting an increasingly elderly and comorbid population, as well as reinforcing the need for more treatments for this disease. The pathophysiology of HFpEF is complex. Some inflammatory processes seen in HFpEF are shared with diabetes mellitus (DM) and there is an association seen between the two conditions. It is therefore no wonder that treatments for diabetes may have some effect on heart failure outcomes. Current treatment strategies in HFpEF are limited, with treatments focusing on symptom control rather than morbidity or mortality benefit. However, there are now promising results from the EMPEROR-Preserved study that show significantly reduced cardiovascular death or hospitalisation for heart failure (HHF) in patients taking empagliflozin, compared to those taking placebo. These results indicate a promising future for sodium-glucose co-transporter 2 (SGLT2) inhibitors in HFpEF. The ongoing DELIVER trial (investigating the use of dapagliflozin in HFpEF) is awaited but could provide further evidence of support for SGLT2 inhibitors in HFpEF. With hospital admissions for HFpEF increasing in the UK, the economic impact of treatments that reduce HHF is vast. The European Society of Cardiology (ESC) recently added SGLT2 inhibitors to their guidelines for treatment of heart failure with reduced ejection fraction (HFrEF) following DAPA-HF and EMPEROR-Reduced trials and we suggest that similar changes be made to guidelines to support the use of SGLT2 inhibitors in the management of HFpEF in upcoming months.

Prothrombotic genotypes and risk of major bleeding in patients with incident venous thromboembolism.

BACKGROUND: Genotypes associated with venous thromboembolism (VTE) may protect against bleeding due to a hypercoagulable state. Whether the risk of major bleeding is reduced in parallel with an increasing number of prothrombotic genotypes during anticoagulant treatment in VTE remains unknown. OBJECTIVES: To investigate the association between multiple prothrombotic genotypes and risk of major bleeding in patients with VTE. METHODS: Patients with incident VTE (n = 676) derived from the Tromsø Study were genotyped for rs6025 (F5), rs1799963 (F2), rs8176719 (ABO), rs2066865 (FGG) and rs2036914 (F11) single nucleotide polymorphisms (SNPs). Major bleeding events were recorded during the first year after VTE according to the International Society on Thrombosis and Haemostasis criteria. Cox-regression was used to calculate hazard ratios with 95% confidence intervals (CIs) for major bleeding adjusted for age, sex and duration of anticoagulation according to individual prothrombotic SNPs and categories of risk alleles (5-SNP score; 0-1, 2, 3 and ≥4). RESULTS: In total, 50 patients experienced major bleeding (incidence rate: 9.5/100 person-years, 95% CI 7.2-12.5). The individual SNPs and number of risk alleles were not associated with major bleeding risk. The hazard ratios for major bleeding per category increase of genetic risk score were 1.0 (95% CI 0.8-1.3) for the total study population and 1.1 (95% CI 0.8-1.5) when patients with active cancer were excluded. Analyses restricted to the first 3 months after VTE yielded similar results. CONCLUSION: Our findings suggest that an increasing number of prothrombotic risk alleles is not protective against major bleeding in VTE patients during anticoagulation.

Hospitalization as a trigger for venous thromboembolism - Results from a population-based case-crossover study.

BACKGROUND: Previous studies have reported that around 50% of patients with venous thromboembolism (VTE) has undergone recent hospitalization. However, studies on the impact of hospitalization as a trigger factor for VTE are limited. OBJECTIVES: To investigate the impact of hospitalization with and without concurrent immobilization as a trigger factor for VTE. METHODS: We conducted a case-crossover study of 530 cancer-free VTE patients. Hospitalizations were registered during the 90-day period preceding the VTE diagnosis (hazard period), and in four preceding 90-day control periods. A 90-day washout period between the control- and hazard periods was implemented to avoid potential carry-over effects. Conditional logistic regression was used to calculate odds ratios (OR) of VTE according to hospitalization. RESULTS: In total, 159 (30%) of the VTE-patients had been hospitalized in the hazard period, and the OR of hospitalization was 9.4 (95% CI: 6.8-12.8). The risk increased slightly with the total number of days spent in hospital (OR per day: 1.11, 95% CI: 1.04-1.18), and with the number of hospitalizations (OR 8.9, 95% CI: 6.4-12.4 for 1 hospitalization and OR 12.3, 95% CI 6.4-23.6 for ≥2 hospitalizations). Hospitalization without immobilization was 6-times (OR: 6.3, 95% CI: 4.4-9.2) more common, whereas hospitalization with immobilization was near 20-times (OR: 19.8, 95% CI: 11.5-34.0) more common in the 90-days prior to a VTE compared to the control periods. CONCLUSIONS: Hospitalization is a major trigger factor for VTE also in the absence of immobilization. However, immobilization contributes substantially to the risk of VTE among hospitalized patients.

D-Dimer Measured at Diagnosis of Venous Thromboembolism is Associated with Risk of Major Bleeding.

Identification of patients at risk of major bleeding is pivotal for optimal management of anticoagulant therapy in venous thromboembolism (VTE). Studies have suggested that D-dimer may predict major bleeding during anticoagulation; however, this is scarcely investigated in VTE patients. We aimed to investigate the role of D-dimer, measured at VTE diagnosis, as a predictive biomarker of major bleeding. The study population comprised 555 patients with a first community-acquired VTE (1994-2016), who were identified among participants from the Tromsø study. Major bleeding events were recorded during the first year after VTE and defined according to the criteria of the International Society on Thrombosis and Haemostasis. Cox-regression was used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) adjusted for age, sex, and duration of anticoagulant therapy. In total, 29 patients experienced major bleeding (incidence rate: 5.7/100 person-years, 95% CI: 4.0-8.2). The major bleeding risk was highest during the first 3 months, especially in patients with D-dimer ≥8.3 µg/mL (upper 20th percentile), with 28.8 major bleedings/100 person-years (95% CI: 13.7-60.4). Patients with D-dimer ≥8.3 µg/mL had a 2.6-fold (95% CI: 1.1-6.6) higher risk of major bleeding than patients with D-dimer ≤2.3 µg/mL (lower 40th percentile). Major bleeding risk according to D-dimer ≥8.3 versus ≤2.3 µg/mL was particularly pronounced among those with deep vein thrombosis (HR: 4.6, 95% CI: 1.3-16.2) and provoked events (HR: 4.2, 95% CI: 1.0-16.8). In conclusion, our results suggest that D-dimer measured at diagnosis may serve as a predictive biomarker of major bleeding after VTE, especially within the initial 3 months.