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The paper describes a method for calculating margins to voltage instability. The method is based on sensitivity techniques. The measure to voltage instability can be given in terms of MW, MVAr or MVA depending on the components in the increase in load. The extensions to earlier publications of the method are the ability to increase the load and generation simultaneously on several buses without increasing the computation time. A single forward and backward substitution is sufficient to find the required sensitivities when the load is increased. The productions of the plant can be increased either by a specified profile or by using the turbine droop characteristics. A method for identification of contingencies needing an explicit reserve evaluation is briefly described.

Optical-equivalent snow grain size (R_opt) and snow BRDF (bidirectional reflectance distribution function) were measured in Antarctica during austral summer 2013/14. We combined longterm observations at Kohnen station (75° 0' S, 0° 4' E) at the outer part of the East Antarctic Plateau with airborne measurements (60 flight hours) over Dronning Maud Land covering different surface roughness and areas with higher (coastal areas) and lower (inner Antarctica) precipitation frequencies. The optical grain sizes were retrieved from ground-based surface albedo measurements collected by the COmpact RAdiation measurement System (CORAS) and airborne observations with the Spectral Modular Airborne Radiation measurement sysTem (SMART). They were validated against in-situ observations (IceCube device) and spaceborn reflectance measurements by the MODerate Resolution Imaging Spectroradiometer (MODIS). The data shows that snow metamorphism and wind-induced transport of freshly fallen ice crystals lead to a cascading increase, whereas precipitation induced an abrupt decrease of R_opt. Retrieved R_opt were in accordance with in-situ observations within the ranges given by the measurement uncertainties. However, SMART data slightly overestimated the ground-based results. A 180° digital camera provides airborne radiance measurements with high angular resolution utilizing detailed radiometric and geometric calibrations. In combination with spectral downward irradiance measured by SMART, the snow BRDF was calculated. The snow BRDF was obtained for a variety of conditions with different surface roughness, snow grain size and solar zenith angle and will be a valuable data set for numerous remote sensing techniques and radiative transfer studies above snow surfaces. The comparison between smooth and rough surfaces (sastrugi) showed significant differences in the BRDF of snow, which is additionally influenced by the diurnal cycle and snow grain size. [ABSTRACT FROM AUTHOR]

The reflection of solar radiation at snow surfaces is particularly anisotropic in polar regions due to low sun elevations and the anisotropic phase function of ice crystals. The bidirectional reflectance distribution function (BRDF) of snow was derived from airborne measurements of a digital 180° fish-eye camera in Antarctica during austral summer 2013/14. The snow BRDF was obtained for a variety of conditions with different surface roughness, snow grain size, and solar zenith angle. The airborne measurements covered an area of around 1000 x 1500 km2 in the vicinity of Kohnen station (75° 0' S, 0° 4' E) at the outer part of the East Antarctic Plateau. The observations (60 flight hours) over Dronning Maud Land include regions with higher (coastal areas) and lower (inner Antarctica) precipitation frequencies. The calibrated 180° digital camera provides radiance measurements of almost the entire lower hemisphere with an angular resolution of 0.1° per camera pixel. In combination with spectral downward irradiance measured by the Spectral Modular Airborne Radiation measurement sysTem (SMART), BRDF was calculated using an atmospheric correction. The BRDF was analyzed with respect to snow grain size retrieved from spectral surface albedo measurements and surface roughness determined by means of a laser scanner. The comparison between smooth and rough surfaces (sastrugi) showed significant differences in the BRDF of snow, which are superimposed on the diurnal cycle and the dependence on snow grain size. By inverting a semi-empirical kernel-driven BRDF model, we parameterized the snow BRDF with respect to surface roughness, snow grain size, and solar zenith angle. This allows a direct comparison of the BRDF measurements with BRDF products from satellite remote sensing. [ABSTRACT FROM AUTHOR]

Mixed-phase clouds (MPCs), which consist of both supercooled cloud droplets and ice crystals, play an important role in the Earth's radiative energy budget and hydrological cycle. In particular, the fraction of ice crystals in MPCs determines their radiative effects, precipitation formation and lifetime. In order for ice crystals to form in MPCs, ice-nucleating particles (INPs) are required. However, a large-scale relationship between INPs and ice initiation in clouds has yet to be observed. By analyzing satellite observations of the typical transition temperature (T*) where MPCs become more frequent than liquid clouds, we constrain the importance of INPs in MPC formation. We find that over the Arctic and Southern Ocean, snow and sea ice cover significantly reduces T*. This indicates that the availability of INPs is essential in controlling cloud phase evolution and that local sources of INPs in the high-latitudes play a key role in the formation of MPCs., (© 2022 The Authors.)

Background: The use of psychotropics is high among the older population and may have detrimental effects on their physical and mental health. Cardiorespiratory fitness (CRF) is a strong and modifiable measure of health and declines with age. We aimed to study the association of change in CRF with use of psychotropics in community-dwelling older adults., Methods: We analyzed longitudinal data from 1531 older adults from the Generation 100 study, aged 70-77 years at inclusion, and with a permanent address in Trondheim, Norway. Data on objectively measured peak oxygen uptake (VO 2peak ) were linked with register data from the Norwegian Prescription Database on prescribed psychotropics. The included psychotropics were antidepressants (N06A), antipsychotics (N05A), anxiolytics (N05B), hypnotics and sedatives (N05C), and N03AE (benzodiazepine derivatives). Analyses were done on any psychotropics as one group, and on the following separate groups: antidepressants (N06A), benzodiazepines (N05BA, N05CD, and N03AE), and z-hypnotics (N05CF). Peak oxygen uptake was measured four times over a five-year period and corresponding medication use was measured as defined daily doses (DDD). A random effects estimator was applied to investigate the association of change in VO 2peak with the use of psychotropics., Results: We found a statistically significant curvilinear association of change in VO 2peak with use of any psychotropics and antidepressants. For VO 2peak up to ~ 40 ml/kg/min, each 1 ml/kg/min increase was associated by a 3.3 DDD and 2.5 DDD decrease in use of any psychotropics and antidepressants, respectively. A bottoming-out effect was found and increases in VO 2peak above ~ 40 ml/kg/min showed increased use of any psychotropics and antidepressants. However, the association of change in VO 2peak with use was stronger for changes in the lower continuum of VO 2peak levels and decreased with increasing VO 2peak . No statistically significant association of change in VO 2peak with use of benzodiazepines and z-hypnotics were found. However, because of a non-randomized design, we cannot rule out the possibility of confounding by indication., Conclusions: The results of this study show a curvilinear association of change in VO 2peak with use of any psychotropics and antidepressants in older adults. This relationship adds a new viewpoint on the adverse effects of psychotropic use and should be considered in interventions and policies aimed at reducing psychotropic medication use among the older population., (© 2022. The Author(s).)

Aims: The aim of this study was to compare the effects of 5 years of supervised exercise training (ExComb), and the differential effects of subgroups of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT), with control on the cardiovascular risk profile in older adults., Methods and Results: Older adults aged 70-77 years from Trondheim, Norway (n = 1567, 50% women), able to safely perform exercise training were randomized to 5 years of two weekly sessions of HIIT [∼90% of peak heart rate (HR), n = 400] or MICT (∼70% of peak HR, n = 387), together forming ExComb (n = 787), or control (instructed to follow physical activity recommendations, n = 780). The main outcome was a continuous cardiovascular risk score (CCR), individual cardiovascular risk factors, and peak oxygen uptake (VO2peak). CCR was not significantly lower [-0.19, 99% confidence interval (CI) -0.46 to 0.07] and VO2peak was not significantly higher (0.39 mL/kg/min, 99% CI -0.22 to 1.00) for ExComb vs. control. HIIT showed higher VO2peak (0.76 mL/kg/min, 99% CI 0.02-1.51), but not lower CCR (-0.32, 99% CI -0.64 to 0.01) vs. control. MICT did not show significant differences compared to control or HIIT. Individual risk factors mostly did not show significant between-group differences, with some exceptions for HIIT being better than control. There was no significant effect modification by sex. The number of cardiovascular events was similar across groups. The healthy and fit study sample, and contamination and cross-over between intervention groups, challenged the possibility of detecting between-group differences., Conclusions: Five years of supervised exercise training in older adults had little effect on cardiovascular risk profile and did not reduce cardiovascular events., Registration: ClinicalTrials.gov: NCT01666340., (© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.)