EFFICIENCY OF NATURAL LIGHTING IN OFFICE BUILDINGS ON THE EXAMPLE OF A BUILDING LOCATED IN POLAND

It is important for sustainability to reduce the energy demand of both existing and planned buildings. The requirements for workspace lighting clearly define the minimum light intensity that must be provided. The aim of the study was to verify if the selected office layouts independently fulfill the requirements of the Polish Norm for lighting of workplaces without the use of artificial light sources. The analysis took into consideration standard working hours of office buildings, that is from January to December, from 8 a.m. to 4 p.m. Interpretation of the obtained data allowed to select the layouts that maintain the most stable efficiency of natural daylight.

Analysis of High-precision TESS Photometry of the Black Hole X-Ray Binary Cygnus X-1: Evidence of Intrinsic Variability of the Luminous Blue Supergiant Component

We report on Transiting Exoplanet Survey Satellite (TESS) high-precision photometry of the iconic non-eclipsing 5.60 days (O9.7Iab+black hole) binary Cygnus X-1. Previous ground-based photometry reveals low-amplitude (∼0.04 mag) ellipsoidal light-variations that arise from the tidal (and rotational) distortion of the O9.7Iab companion. Additional small light-variations have also been reported by many observers. Short-cadence TESS photometry was conducted over ∼27 days during 2019 July–August. The photometry shows the expected ∼5.60 days binary ellipsoidal variations, but in addition ∼0.01–0.03 mag complex quasi-periodic brightness variations. The observations were analyzed to investigate the underlying extra-binary variability. We also determined a new time of minimum light and calculated an updated period and light elements. The quasi-periodic, (non-binary) light-variations likely arise from the complex pulsations of the blue supergiant.

Light intensity regulates flower visitation in Neotropical nocturnal bees

The foraging activity of diurnal bees often relies on flower availability, light intensity and temperature. We do not know how nocturnal bees, which fly at night and twilight, cope with these factors, especially as light levels vary considerably from night to day and from night to night due to moon phase and cloud cover. Given that bee apposition compound eyes function at their limits in dim light, we expect a strong dependence of foraging activity on light intensity in nocturnal bees. Besides being limited by minimum light levels to forage, nocturnal bees should also avoid foraging at brighter intensities, which bring increased competition with other bees. We investigated how five factors (light intensity, flower availability, temperature, humidity, and wind) affect flower visitation by Neotropical nocturnal bees in cambuci (Campomanesia phaea, Myrtaceae). We counted visits per minute over 30 nights in 33 cambuci trees. Light intensity was the main variable explaining flower visitation of nocturnal bees, which peaked at intermediate light levels occurring 25 min before sunrise. The minimum light intensity threshold to visit flowers was 0.00024 cd/m2. Our results highlight the dependence of these nocturnal insects on adequate light levels to explore resources.

Comparison of microscopic illumination between a three-dimensional heads-up system and eyepiece in cataract surgery

Introduction The ability to reduce illumination levels is generally accepted as one of the main benefits of a three-dimensional heads-up system (3D system: Ngenuity®; Alcon, CA, USA). Some studies have focused on illumination reduction in vitreoretinal procedures; however, information regarding illumination reduction in cataract surgery has not been published. Purpose This study aimed to compare the illumination of the operational field with a 3D system and a standard microscope eyepiece during cataract surgery. Subject and methods We retrospectively evaluated 91 eyes of 84 consecutive patients who were undergoing cataract surgery at our hospital. We used the 3D system and the eyepiece on alternative days. We determined the minimum light intensity required for safe surgery using the foot switch of the microscope (OMS800; Topcon, Tokyo, Japan). Illuminance on the ocular surface and the minimum illuminance required for the operation were calculated from the minimum light intensity. Results The 3D system was used in 45 eyes (3D group), and the eyepiece was used in 46 eyes (eyepiece group). The values of minimum illuminance in the 3D group were significantly lower than those in the eyepiece group (3D: 5500 ± 2000 lux, eyepiece: 11,900 ± 1800 lux; p < 0.001*). In addition, the illuminance of the operational field was reduced by 60.4% on average using the 3D system. Conclusion With real-time digital processing and automated brightness control, the 3D system reduced ocular surface illumination by 50% or more. Hence, the 3D system may contribute to reducing the risk of retinal phototoxicity and patient photophobia.

The stellar photosphere–hydrogen ionization front interaction in classical pulsators: a theoretical explanation for observed period–colour relations

ABSTRACT Period–colour and amplitude–colour (PCAC) relations can be used to probe both the hydrodynamics of outer envelope structure and evolutionary status of Cepheids and RR Lyraes. In this work, we incorporate the PCAC relations for RR Lyraes, BL Her, W Vir, and classical Cepheids in a single unifying theory that involves the interaction of the hydrogen ionization front (HIF) and stellar photosphere and the theory of stellar evolution. PC relations for RR Lyraes and classical Cepheids using the Optical Gravitational Lensing Experiment (OGLE-IV) data are found to be consistent with this theory: RR Lyraes have shallow/sloped relations at minimum/maximum light, whilst long-period (P &gt; 10 d) Cepheids exhibit sloped/flat PC relations at minimum/maximum light. The differences in the PC relations for Cepheids and RR Lyraes can be explained based on the relative location of the HIF and stellar photosphere which changes depending on their position on the Hertzsprung–Russell diagram. We also extend our analysis of PCAC relations for type II Cepheids in the Galactic bulge, Large and Small Magellanic Clouds using OGLE-IV data. We find that BL Her stars have sloped PC relations at maximum and minimum light similar to short-period (P &lt; 10 d) classical Cepheids. W Vir stars exhibit sloped/flat PC relation at minimum/maximum light similar to long-period classical Cepheids. We also compute state-of-the-art 1D radiation hydrodynamic models of RR Lyraes, BL Her and classical Cepheids using the radial stellar pulsation code in mesa to further test these ideas theoretically and find that the models are generally consistent with this picture. We are thus able to explain PC relations at maximum and minimum light across a broad spectrum of variable star types.

Quantitative evaluation of digital-image enhancement during heads-up surgery

Image-processing is an advantage of heads-up surgery and expected to facilitate ophthalmic surgeries. To evaluate image-processing quantitatively, we analyzed the surgical images of twenty eyes that underwent vitrectomy with internal limiting membrane (ILM) peeling assisted by Brilliant Blue G (BBG). Still images of the peeling procedure were obtained from the surgical video, and the color difference was calculated between two adjacent spots inside and outside the ILM-peeling contour, i.e., without and with BBG staining, respectively. The color differences were compared between the two settings with and without image-processing, delivered by an algorithm to enhance the color and contrast. Color differences were calculated using two methods: the Euclidean distance based on RGB values (RGB distance) and the Delta-E00 formula provided by the International Commission on Illumination. In five cases, minimum light intensities required to recognize the contour of ILM-peeling were compared during surgeries between the two settings with and without enhancement. Image-processing increased the mean color difference significantly (P < 0.001) from 15.47 and 4.49 to 34.03 and 8.00, respectively, for the RGB distance and Delta-E00. The minimum light intensity was reduced from 15 to 5 on average by image-enhancement. These results showed image-processing enhances color differences and reduces light intensities during vitrectomy.

Leaf and Crown Optical Properties of Five Early-, Mid- and Late-Successional Temperate Tree Species and Their Relation to Sapling Light Demand

The optical properties of leaves and canopies determine the availability of radiation for photosynthesis and the penetration of light through tree canopies. How leaf absorptance, reflectance and transmittance and radiation transmission through tree canopies change with forest succession is not well understood. We measured the leaf optical properties in the photosynthetically active radiation (PAR) range of five Central European early-, mid- and late-successional temperate broadleaf tree species and studied the minimum light demand of the lowermost shade leaves and of the species’ offspring. Leaf absorptance in the 350–720 nm range varied between c. 70% and 77% in the crown of all five species with only a minor variation from the sun to the shade crown and between species. However, specific absorptance (absorptance normalized by mass per leaf area) increased about threefold from sun to shade leaves with decreasing leaf mass area (LMA) in the late-successional species (Carpinus betulus L., Tilia cordata Mill., Fagus sylvatica L.), while it was generally lower in the early- to mid-successional species (Betula pendula Roth, Quercus petraea (Matt.)Liebl.), where it changed only a little from sun to shade crown. Due to a significant increase in leaf area index, canopy PAR transmittance to the forest floor decreased from early- to late-successional species from ~15% to 1%–3% of incident PAR, linked to a decrease in the minimum light demand of the lowermost shade leaves (from ~20 to 1%–2%) and of the species’ saplings (from ~20 to 3%–4%). The median light intensity on the forest floor under a closed canopy was in all species lower than the saplings’ minimum light demand. We conclude that the optical properties of the sun leaves are very similar among early-, mid- and late-successional tree species, while the shade leaves of these groups differ not only morphologically, but also in terms of the resource investment needed to achieve high PAR absorptance.

ROAD† and K2 photometry of V348 Sgr: probing the pulsation dust connection

ABSTRACT V348 Sgr is simultaneously an active hot R Coronae Borealis (RCB) variable, a peculiar extreme helium star, and the hydrogen-deficient central star of a planetary nebula. Explaining the RCB-type variability has been difficult since the star spends much of its time at minimum light. We present new ground-based multicolour photometry covering five observing seasons and 80 d of continuous photometry from space. The latter demonstrate small-amplitude (&lt;0.01 mag) variability at maximum light on time-scales typical for strange-mode pulsation in hot helium supergiants. These could provide a trigger for frequent dust-production episodes; other mechanisms must also be considered. Multicolour photometry probes the reddening properties of extinction events from minimum to maximum light. The latter are comparable with extinction events due to carbonaceous grains seen in cooler RCB stars. Minimal reddening at minimum light is indicative that starlight scattered from circumstellar dust into the line of sight dominates transmitted light.

High vowel distribution and trochaic markedness in Québécois

This paper argues for quantity-sensitive, trochaic foot structure in Québécois French, which allows for a unified prosodic account of the variable distribution of tenseness of high vowels in non-final syllables. Following Montreuil (Montreuil, Jean-Pierre. 2004a. Fragmenting weight in Scottish English. In Monica Pulki (ed.), La tribune internationale des langues vivantes, 36, 114–22. Paris. Montreuil, Jean-Pierre. 2004b. The Computation of weight in English and in Québec French. First PAC Workshop 23–24 April 2004, Université de Toulouse le Mirail.) a grammatical, sonority-based surface weight distinction is assumed for Québécois French vowels, with tense high vowels associated to a full mora µ, while lax high vowels are associated to a hypomora λ, a weight value less than µ. The weight is shown to be regulated at the level of the minimally monomoraic foot, which can be expanded to include an adjacent syllable in words consisting of more than two syllables, following the proposed Trochaic Markedness Hierarchy, based on the following three ranked principles: 1) quantitative minimum: light and heavy rimes are preferred to superlight (λ) rimes, 2) quantitative evenness: even trochees are preferred to uneven trochees, and 3) quantitative dominance: the left branch that is heavier than the right branch is preferred to the left branch that is lighter. Possible shapes of the trochee are shown to be aligned with alternating surface realizations of high vowels.