Matching CIE illuminants to measured spectral power distributions: A method to evaluate non-visual potential of daylight in two European cities

The evaluation of non-visual effects of light is a crucial topic in lighting design research and practice. Performing such analysis requires precise information about the spectral distribution of the tested light source. Assessing non-visual effects of daylight is complicated due to its spectral composition continuously changing, depending on many factors. Currently there are no available databases with spectral and spatial radiation patterns of the sky vault for locations spread all over the world, and an easy and common method to evaluate non-visual effects of daylight is lacking. The goal of the paper is to provide a simple method to evaluate the non-visual potential of daylight, accounting for its variability. In order to present it, spectral measurements were conducted in two European cities in spring and summer. Horizontal and vertical illuminance toward the four cardinal directions was measured. Daylight variability was analysed in terms of illuminance, Correlated Colour Temperature (CCT) and Melanopic to Photopic (M/P) ratio. A comparison between the measured spectra and the CIE standard illuminants was performed and it was found that the usefulness of this method to evaluate non-visual effects of light in terms of M/P is adequate and provides reliable results. Therefore, a simple method to estimate the non-visual potential of daylight based on the use of D series of illuminants was presented and validated by comparing the results with the measured data. Using this method to calculate M/P always achieves RMSPEs below 6%

DnaK Chaperone-Mediated Control of Activity of a ς(32) Homolog (RpoH) Plays a Major Role in the Heat Shock Response of Agrobacterium tumefaciens

RpoH (Escherichia coli ς(32) and its homologs) is the central regulator of the heat shock response in gram-negative proteobacteria. Here we studied salient regulatory features of RpoH in Agrobacterium tumefaciens by examining its synthesis, stability, and activity while increasing the temperature from 25 to 37°C. Heat induction of RpoH synthesis occurred at the level of transcription from an RpoH-dependent promoter, coordinately with that of DnaK, and followed by an increase in the RpoH level. Essentially normal induction of heat shock proteins was observed even with a strain that was unable to increase the RpoH level upon heat shock. Moreover, heat-induced accumulation of dnaK mRNA occurred without protein synthesis, showing that preexisting RpoH was sufficient for induction of the heat shock response. These results suggested that controlling the activity, rather than the amount, of RpoH plays a major role in regulation of the heat shock response. In addition, increasing or decreasing the DnaK-DnaJ chaperones specifically reduced or enhanced the RpoH activity, respectively. On the other hand, the RpoH protein was normally stable and remained stable during the induction phase but was destabilized transiently during the adaptation phase. We propose that the DnaK-mediated control of RpoH activity plays a primary role in the induction of heat shock response in A. tumefaciens, in contrast to what has been found in E. coli

The molecular architecture of the metalloprotease FtsH

The ATP-dependent integral membrane protease FtsH is universally conserved in bacteria. Orthologs exist in chloroplasts and mitochondria, where in humans the loss of a close FtsH-homolog causes a form of spastic paraplegia. FtsH plays a crucial role in quality control by degrading unneeded or damaged membrane proteins, but it also targets soluble signaling factors like σ(32) and λ-CII. We report here the crystal structure of a soluble FtsH construct that is functional in caseinolytic and ATPase assays. The molecular architecture of this hexameric molecule consists of two rings where the protease domains possess an all-helical fold and form a flat hexagon that is covered by a toroid built by the AAA domains. The active site of the protease classifies FtsH as an Asp-zincin, contrary to a previous report. The different symmetries of protease and AAA rings suggest a possible translocation mechanism of the target polypeptide chain into the interior of the molecule where the proteolytic sites are located

Sources and chemistry of polar tropospheric halogens (Cl, Br, I) using the CAM-Chem Global Chemistry-Climate Model, links to netCDF files

Here, we present the first implementation of an interactive polar module into the halogen version of the CAM-Chem model with the intention of expanding the model applicability to the polar regions, besides its widely usage for atmospheric studies throughout the tropics and mid-latitudes. The state-of-the-art polar module considers full gas-phase and heterogeneous inorganic chlorine, bromine and iodine chemistry and sources, which adds up to the organic halogen emissions from the ocean surface (the so-called very short-lived (VSL) substances). The online sea-ice halogen sources depend on the seasonal variation of different types of icy surfaces and the intensity of radiation reaching the polar surface. Our results indicate that the contribution of polar halogen sources represents between 45 and 80% of the global biogenic VSL bromine and chlorine emissions, respectively; and that the Antarctic iodine sea-ice annual flux is ~10 times larger than the total iodine source arising from the Southern Ocean. This work provides, for the first time, quantitative estimates of the annual and seasonal flux strength of each halogen family from the Arctic and Antarctic, as well as their contribution to the global tropospheric halogen budget, highlighting the importance of including the contribution of polar tropospheric halogens in global chemistry-climate models