Do the Health Benefits of Cycling Outweigh the Risks?

BACKGROUND: Although from a societal point of view a modal shift from car to bicycle may have beneficial health effects due to decreased air pollution emissions, decreased greenhouse gas emissions, and increased levels of physical activity, shifts in individual adverse health effects such as higher exposure to air pollution and risk of a traffic accident may prevail.Objective: We describe whether the health benefits from the increased physical activity of a modal shift for urban commutes outweigh the health risks. DATA SOURCES AND EXTRACTION: We have summarized the literature for air pollution, traffic accidents, and physical activity using systematic reviews supplemented with recent key studies. DATA SYNTHESIS: We quantified the impact on all-cause mortality when 500,000 people would make a transition from car to bicycle for short trips on a daily basis in the Netherlands. We have expressed mortality impacts in life-years gained or lost, using life table calculations. For individuals who shift from car to bicycle, we estimated that beneficial effects of increased physical activity are substantially larger (3-14 months gained) than the potential mortality effect of increased inhaled air pollution doses (0.8-40 days lost) and the increase in traffic accidents (5-9 days lost). Societal benefits are even larger because of a modest reduction in air pollution and greenhouse gas emissions and traffic accidents. CONCLUSIONS: On average, the estimated health benefits of cycling were substantially larger than the risks relative to car driving for individuals shifting their mode of transport

Single crystalline InxGa1−xN layers on germanium by molecular beam epitaxy

InxGa1−xN (InGaN) alloys are predominantly grown by heteroepitaxy on foreign substrates. Most often Al2O3, SiC and Si are used as substrates, however this complicates vertical conduction from the InGaN surface to the substrate backside. Therefore we investigate the heteroepitaxial growth of InGaN layers on Ge substrates. Single crystalline InGaN was obtained and domain formation was suppressed by using a thin GaN buffer layer. The InGaN shows compressive strain, which follows from the lattice mismatch with the GaN buffer layer. The In distribution is uniform throughout the InGaN layer, with no significant In segregation within the layer. Only at the surface, in a very thin layer of 20 nm, strong In segregation is observed with about 50% In. InGaN/GaN/Ge diodes show vertical current conduction of 1 A cm−2 at −2 V. InGaN grown on Ge is therefore promising for device applications with preferred vertical conduction.status: publishe

Radiosafe micro-computed tomography for longitudinal evaluation of murine disease models

Implementation of in vivo high-resolution micro-computed tomography (µCT), a powerful tool for longitudinal analysis of murine lung disease models, is hampered by the lack of data on cumulative low-dose radiation effects on the investigated disease models. We aimed to measure radiation doses and effects of repeated µCT scans, to establish cumulative radiation levels and scan protocols without relevant toxicity. Lung metastasis, inflammation and fibrosis models and healthy mice were weekly scanned over one-month with µCT using high-resolution respiratory-gated 4D and expiration-weighted 3D protocols, comparing 5-times weekly scanned animals with controls. Radiation dose was measured by ionization chamber, optical fiberradioluminescence probe and thermoluminescent detectors in a mouse phantom. Dose effects were evaluated by in vivo µCT and bioluminescence imaging read-outs, gold standard endpoint evaluation and blood cell counts. Weekly exposure to 4D µCT, dose of 540-699 mGy/scan, did not alter lung metastatic load nor affected healthy mice. We found a disease-independent decrease in circulating blood platelets and lymphocytes after repeated 4D µCT. This effect was eliminated by optimizing a 3D protocol, reducing dose to 180-233 mGy/scan while maintaining equally high-quality images. We established µCT safety limits and protocols for weekly repeated whole-body acquisitions with proven safety for the overall health status, lung, disease process and host responses under investigation, including the radiosensitive blood cell compartment.status: accepte