Increase In Apparent Temperature Research Articles

Impact of apparent temperatures on park visitation behavior: A comprehensive analysis using large-scale mobility data

As many regions continue to show record temperatures and high frequencies of extreme climate events, climate change is disrupting human health and prosperity. This study focuses on how temperature changes and extreme heat as key climate components can impact park visitations (key physical activities indicator). Using the large mobility dataset SafeGraph, this study introduced a causal machine learning approach to estimate marginal heterogenous treatment effects (HTE) of daily apparent temperatures for different park properties and activity types. Our results revealed the declining effects of park visitations as apparent temperature increases and the significant disturbances under extreme heat. Different temperature thresholds that may harm park visitations were identified. Nearby green and public spaces (e.g. neighborhood parks) are the most susceptible category to summer heat. Dog parks, Playgrounds and Ball Field/Sports were well used during the heat. Pool/Splash pad and Community center have shown capabilities of mitigating heat stress. Effectiveness of other park facilities, including Restroom/Drinking Fountain, Water Body, Shade Area Facility were also presented. This study estimates climate impact on park behaviors for multiple usage and environmental situations. Our findings may help future planners, policymakers, landscape architects and park managers better understand climate-related risks when making investment and development decisions.

A precursor plateau and pre-maximum [O ii] emission in the superluminous SN2019szu: a pulsational pair-instability candidate

ABSTRACT We present a detailed study on SN2019szu, a Type I superluminous supernova at z = 0.213 that displayed unique photometric and spectroscopic properties. Pan-STARRS and ZTF forced photometry show a pre-explosion plateau lasting ∼40 d. Unlike other SLSNe that show decreasing photospheric temperatures with time, the optical colours show an apparent temperature increase from ∼15 000 to ∼20 000 K over the first 70 d, likely caused by an additional pseudo-continuum in the spectrum. Remarkably, the spectrum displays a forbidden emission line (likely attributed to λλ7320,7330) visible 16 d before maximum light, inconsistent with an apparently compact photosphere. This identification is further strengthened by the appearances of [O iii] λλ4959, 5007, and [O iii] λ4363 seen in the spectrum. Comparing with nebular spectral models, we find that the oxygen line fluxes and ratios can be reproduced with ∼0.25 M⊙ of oxygen-rich material with a density of $\sim 10^{-15}\, \rm {g\, cm}^{-3}$. The low density suggests a circumstellar origin, but the early onset of the emission lines requires that this material was ejected within the final months before the terminal explosion, consistent with the timing of the precursor plateau. Interaction with denser material closer to the explosion likely produced the pseudo-continuum bluewards of ∼5500 Å. We suggest that this event is one of the best candidates to date for a pulsational pair-instability ejection, with early pulses providing the low density material needed for the formation of the forbidden emission line, and collisions between the final shells of ejected material producing the pre-explosion plateau.

Numerically Detection Fluid Characteristic Effects in Porous Media for Plastic Manufacturing Process Reconstruction

Research work aimed to prove the cooling effectiveness and efficiency of heating numerically. It was carried out by reconstructing the mold to reduce condensation while keeping the production cycle time. The simulation was done using CFD Fluent, Finite Volume Method (FVM) with a solution method of pressure-velocity, SIMPLE coupling, and second-order upwind discretization scheme. The model's boundary condition represents plastic packaging's production process. The simulation was done to optimize performance during production. Reconstruction and simulation were undertaken. The initial investigation was to produce data for cooling time versus the whole production time. The research result indicated that the average cooling time was 3/5 of the total production time. There were 15.5706 of 26.4206 sec and 15.641 of 26.491 sec, respectively. Further investigation was focused on investigating heat absorption and transfer through cells in the matrix. The porous effect showed temperature gradient reduction between cooled and cooler temperatures by simulation in color. The phenomenon predicted that the Ra contributed to the rate of temperature decrease revealed. There is also an apparent increase in temperature interfaces is evidence. The porous media application with The Rayleigh Number ≥ 105 retained the potential cooling effectivity and heating efficiency. By simulation, a series of discussions of the result of research, the potential may apply in the plastic mold to reconstruct the space and its methods using filling-porous. It is relevant because the heating ability in the phase change of fluid that creates particular characteristics has the potential to make effective cooling.

The association of maternal exposure to ambient temperature with low birth weight in term pregnancies varies by location: In Brazil, positive associations may occur only in the Amazon region

Exposure to ambient temperature has been linked to adverse birth outcomes in several regions, including the USA, Australia, China, countries in the Middle East, and European countries. To date, no studies were performed in South America, a region with serious challenges related to climate change. Our investigation addresses this literature lack by examining the association between Low Birth Weight (LBW) and ambient temperature exposure in the largest county in South America, Brazil. We applied a nationwide case-control study design using a logistic regression model to estimate the odds ratio (OR) for LBW associated with ambient temperature during a specific trimester of pregnancy (1–3 trimester). Our sample size includes 5,790,713 birth records nationwide over 18 years (2001–2018), of which 264,967 infants were included in the model as cases of LBW, representing 4.6% of our total sample. We adjusted our model for several confounding variables, including weather factors, air pollution, seasonality, and SES variables at the individual level. Our findings indicate that North was the only region with positive and statistically significant associations in the primary analysis and most of the sensitivity analysis, which is the region where the Amazon is located. In this region, we estimated an increase of 5.16% (95%CI: 3.60; 6.74) in the odds of LBW per 1 °C increase in apparent temperature when the exposure occurred in the second trimester. Our results may be explained by the climate conditions in the Amazon region in the past years. A large body of literature indicates that the Amazon region has been facing serious climate challenges including issues related to policy, governance, and deforestation. Specifically, regarding deforestation, it is suggested that land use change and deforestation is projected to increase heat stress in the Amazon region, because of Amazon savannization, increasing the risk of heat stress exposure in Northern Brazil. Our study can assist public sectors and clinicians in mitigating the risk and vulnerability of the Amazonian population.

The Ellerman bomb and ultraviolet burst triggered successively by an emerging magnetic flux rope

Ellerman bombs (EBs) and ultraviolet (UV) bursts are common brightening phenomena, which are usually generated in the low solar atmosphere of emerging flux regions. In this paper, we have investigated the emergence of an initial un-twisted magnetic flux rope based on three-dimensional (3D) magneto-hydrodynamic (MHD) simulations. The EB-like and UV burst-like activities successively appear in the U-shaped part of the undulating magnetic fields triggered by the Parker instability. The EB-like activity starts to appear earlier and lasts for about 80 seconds. Six minutes later, a much hotter UV burst-like event starts to appear and lasts for about 60 seconds. Along the direction vertical to the solar surface, both the EB and UV burst start in the low chromosphere, but the UV burst extends to a higher altitude in the up chromosphere. The regions with apparent temperature increase in the EB and UV burst are both located inside the small twisted flux ropes generated in magnetic reconnection processes, which are consistent with the previous 2D simulations that most hot regions are usually located inside the magnetic islands. However, the twisted flux rope corresponding to the EB is only strongly heated after it floats up to an altitude much higher than the reconnection site during that period. Our analyses show that the EB is heated by the shocks driven by the strong horizontal flows at two sides of the U-shaped magnetic fields. The twisted flux rope corresponding to the UV burst is heated by the driven magnetic reconnection process.

Emission of volatile organic compounds during aerobic decomposition of banana peel.

Emissions of volatile organic compounds (VOCs) were continuously measured during the aerobic decomposition of banana peel in a laboratory-scale landfill simulator over 25 d. Using direct membrane inlet single-photon ionisation time-of-flight mass spectrometry (MI-SPI-ToF-MS), 18 VOCs belonging to 10 functional groups were detected in the air samples, and their VOC emission profiles were established using cluster analysis on time-resolved data. Three emission stages were clearly identified, with the major release for most VOC compounds occurring during the first 14 d. The emission patterns of the individual compounds were quite similar despite the different release mechanisms. In addition, no apparent increase in temperature was observed inside the simulator during the entire experimental period. We suggest that the volatilisation of the constituents in the waste pile contributed equally to VOC emissions as did the degradation of banana peel via microbial activity. The average emission rate of total VOCs reached 44.3 × 10-3 mg VOC kg-1 of dry banana peel, with more than half belonging to malodourous substances. The malodourous emissions of the decaying banana peel in an aerobic environment mainly originated from styrene, dimethyl sulphide, and diethyl sulphide, the most common contributors to offensive odourants during food waste biodegradation.

Projection of apparent temperature using statistical downscaling approach in the Pearl River Delta

In this study, a stepwise-clustered statistical downscaling model is established to simulate future apparent temperatures based on NCEP reanalysis data and four global climate models (GCMs). AP is a metric used to quantify thermal comfort or discomfort. The model can express nonlinear relationships between variables at large scale and local scale. The model is employed for projecting future apparent temperature changes over the Pearl River Delta (PRD), on the south coast of China, under three representative concentration pathways (RCP) scenarios. The cluster tree generated for the daily apparent temperature is calibrated for the period 1971–1990 and validated for the period 1991–2000. The R2 values obtained for the validation period at eight selected cities for four GCMs (i.e., CanESM2, CNRM-CM5, CSIRO-Mk3-6-0, and IPSL-CM5A-LR) are 0.88, 0.87, 0.86, and 0.87, respectively. The results reflected that apparent temperature is projected to have a constant increment over the PRD in the future period (2035–2095). Moreover, the monthly apparent temperature in April has the largest expected increment in the future period, while the smallest increment is found in January. The results also indicated that the apparent temperature increases faster than the air temperature under the RCP4.5 and the RCP8.5 scenarios in the PRD. The findings illuminate that the expected increase in apparent temperature over the PRD can be mainly explained by increasing air temperatures and decreasing wind speeds. The results can provide decision makers with useful information for urban health risk assessments.

Highly efficient H-bonding charge-transfer complex for microsupercapacitors under extreme conditions of low temperatures

Owing to sluggish ionic mobility at low temperatures, supercapacitors, as well as other energy-storage devices, always suffer from severe capacity decay and even failure under extreme low-temperature circumstances. Solar-thermal-enabled self-heating promises an attractive approach to overcome this issue. Here, we report a unique H-bonding charge-transfer complex with a high photothermal conversion efficiency of 79.5% at 405 nm based on chloranilic acid and albendazole. Integrated with a microsupercapacitor, the chloranilic acid-albendazole complex (CAC) film prompts an apparent temperature increase of 22.7 °C under 1 sun illumination at −32.6 °C, effectively elevating the working temperature of devices. As a result, the rate capability of the microsupercapacitor has been significantly improved with a 17-fold increase in capacitance at a current density of 60 μA cm −2 , leading to outstanding low-temperature performances. Importantly, the integrated device is capable of working at a low temperature of −30 °C in the open air, which demonstrates the potential of CAC in practical applications for low-temperature ultracapacitive energy-storage devices. An unusual H-bonding charge-transfer complex based on chloranilic acid and albendazole with a high photothermal conversion efficiency of 79.5% is developed. Driven by the efficient solar-thermal effect, planar microsupercapacitors exhibit outstanding electrochemical performances under extreme conditions of low temperature.

Cultural heritage microclimate change: Human-centric approach to experimentally investigate intra-urban overheating and numerically assess foreseen future scenarios impact

Microclimate change related events affect cities total environment and therefore citizens’ wellbeing. In a framework of urban resilience challenge, it is important to guarantee thermally comfortable conditions to dwellers in outdoors but also to preserve cultural heritage masterpieces for tourism and local socio-cultural identity. This work couples an innovative field monitoring at multiple scales and a validated numerical modelling effort to identify indoor and outdoor critical conditions at the present time and in the future, according to IPCC climate change forecast scenarios. The authors focused the attention on the overheating risk of Gubbio historical city center, in central Italy. Experimental data analysis highlights the microclimate granularity of the case study with detected temperature discrepancies up to 2.5 °C observed at pedestrian height during the hottest hour, i.e. 2p.m. Collected data are then used to validate the numerical models of (i) the most significant building of the city and (ii) its surroundings to investigate indoor/outdoor thermal comfort stress due to climate change and local overheating. The combined analysis shows that indoor operative temperature reaches 32 °C on average in 80 years, compared to the current 29 °C value. In the outdoors, apparent temperature increases by about 10 °C on 2100, being responsible for a serious threat compromising socio-cultural life, human health and outdoor and recreational activities.

Temperature, placental abruption and stillbirth

BackgroundPregnant women may be vulnerable to changes in ambient temperature and warming climates. Recent evidence suggests that temperature increases are associated with placental abruption, a risk factor for stillbirth. ObjectivesWe investigated the effect of acute exposures to apparent temperature on stillbirths in Harris County, Texas, 2008–2013. MethodsWe conducted a case-crossover study to investigate the association between temperature and stillbirth among 708 women. We used data from the National Climatic Data Center to estimate maternal exposure to daily average apparent temperature over the days (lag days 1 through 6) preceding the stillbirth event. We employed symmetric bidirectional sampling to select six control periods one to three weeks before and after each event and applied conditional logistic regression to examine associations between increases of apparent temperature and stillbirths during the warm season (May–September). We adjusted for fine particulate matter (PM2.5), nitrogen dioxide (NO2) and ozone (O3) and used stratified analysis to examine differences in risk by maternal race/ethnicity. We also examined the association among stillbirths with and without placental abruptions. ResultsIndependent of air pollutant exposures, a 10 °F increase in apparent temperature in the week preceding delivery (lag days 1 to 6) was positively associated with a 45% (adjusted OR = 1.45, 95% confidence interval (CI): 1.18, 1.77) increase in risk for stillbirth. Risks were elevated for stillbirths occurring in June through August, for Hispanic and non-Hispanic Black women, but not for non-Hispanic Whites. We also observed elevated risks associated with temperature increases in the few days preceding delivery among stillbirths caused by placental abruption, with the risk being highest on lag day 1 (OR = 1.93, 95% CI: 1.15, 3.23). ConclusionsIndependent of maternal ambient air pollutant exposure, we found evidence of an association between apparent temperature increases in the week preceding an event and risk of stillbirth. Risks for stillbirth varied by race/ethnicity. Further, in the first study to evaluate the impact of temperature on a specific complication during pregnancy, the risks were higher among mothers with placental abruption.

The temperature increase at one position in the colony can predict honey bee swarming (Apis cerana)

Although swarming is a natural biological behavior of the honey bee, it significantly influences the production of honey bee products. In this short note, we measured temperature changes of entire Eastern honey bee (Apis cerana) nests during six swarming events. We found that there was a linear heating process before swarming initiated, furthermore, a specific location with the most apparent temperature increase was identified. It lies at the bottom part of the bee space between the wall of the hive and the first frame, which was towards the nest entrance. The mean heating rates before swarming was initiated at 0.0690 ± 0.0314 °C/min until a faster speed of 0.3139 ± 0.1343 °C/min followed. A method for predicting swarming of Apis cerana was proposed.

Magnetically triggered transgene expression in mammalian cells by localized cellular heating of magnetic nanoparticles

To develop a remote control system of transgene expression through localized cellular heating of magnetic nanoparticles, a heat-inducible transgene expression system was introduced into mammalian cells. Cells were labeled with magnetic nanoparticles and exposed to an alternating magnetic field. The magnetically labeled cells expressed the transgene in a monolayer and multilayered cell sheets in which cells were heated around the magnetic nanoparticles without an apparent temperature increase in the culture medium. Magnetic cells were also generated by genetically engineering with a ferritin gene, and transgene expression could be induced by exposure to an alternating magnetic field. This approach may be applicable to the development of novel gene therapies in cell-based medicine.

Temperature and Term Low Birth Weight in California.

Few investigations have explored temperature and birth outcomes. In a retrospective cohort study, we examined apparent temperature, a combination of temperature and relative humidity, and term low birth weight (LBW) among 43,629 full-term LBW infants and 2,032,601 normal-weight infants in California (1999-2013). The California Department of Public Health provided birth certificate data, while meteorological data came from the California Irrigation Management Information System, US Environmental Protection Agency, and National Centers for Environmental Information. After considering several temperature metrics, we observed the best model fit for term LBW over the full gestation (per 10-degrees-Fahrenheit (°F) increase in apparent temperature, 13.0% change, 95% confidence interval: 4.1, 22.7) above 55°F, and the greatest association was for third-trimester exposure above 60°F (15.8%, 95% confidence interval: 5.0, 27.6). Apparent temperature during the first month of pregnancy exhibited no significant risk, while the first trimester had a significantly negative association, and second trimester, last month, and last 2 weeks had slightly increased risks. Mothers who were black or older, delivered male infants, or gave birth during the warm season had infants at the highest risks. This study provides further evidence for adverse birth outcomes from heat exposure for vulnerable subgroups of pregnant women.

Spatial and Temporal Modulation of Thermal Emission.

Precise control of a material's emissivity is critical for thermal-engineering applications. Metamaterials, which derive their optical properties from sub-wavelength structures, have emerged as a promising way to tune emissivity over a wide parameter space. However, metamaterial designs have not yet achieved simultaneous spatial and temporal control of emissivity, which is important for advanced engineering applications such as adaptive thermal management and reconfigurable infrared camouflage. Here, spatiotemporal emissivity control is demonstrated by designing and fabricating a large-area, infrared metamaterial that is modulated with ultraviolet (UV) light. The UV light generates free carriers in a photosensitive ZnO spacer layer, which changes the metamaterial optical properties and causes a localized increase in emissivity. Thermal imaging of the metamaterial during UV illumination reveals an apparent temperature increase as a result of the emissivity change. The imaged temperature fluctuation is recorded under exposure from a temporally modulated and spatially patterned UV illumination source to characterize both the temporal response and spatial resolution of the emissivity change. The results of this work demonstrate new capabilities for thermal metamaterials that could bring about the next generation of thermal-engineering devices.

Three-dimensional hydrodynamic simulations of OMEGA implosions

The effects of large-scale (with Legendre modes ≲10) asymmetries in OMEGA direct-drive implosions caused by laser illumination nonuniformities (beam-power imbalance and beam mispointing and mistiming), target offset, and variation in target-layer thickness were investigated using the low-noise, three-dimensional Eulerian hydrodynamic code ASTER. Simulations indicate that these asymmetries can significantly degrade the implosion performance. The most important sources of the asymmetries are the target offsets (∼10 to 20 μm), beam-power imbalance (σrms∼10%), and variations (∼5%) in target-layer thickness. Large-scale asymmetries distort implosion cores, resulting in a reduced hot-spot confinement and an increased residual kinetic energy of implosion targets. The ion temperature inferred from the width of simulated neutron spectra is influenced by bulk fuel motion in the distorted hot spot and can result in up to an ∼1-keV increase in apparent temperature. Similar temperature variations along different lines of sight are observed. Demonstrating hydrodynamic equivalence to ignition designs on OMEGA requires a reduction in large-scale target and laser-imposed nonuniformities, minimizing target offset, and employing highly efficient mid-adiabat (α = 4) implosion designs, which mitigate cross-beam energy transfer and suppress short-wavelength Rayleigh–Taylor growth.

The impact of high apparent temperature on spontaneous preterm delivery: a case-crossover study

BackgroundDespite the prediction that temperatures are expected to increase in the future, little is known about the health effects of increasing temperatures on pregnant women. The objective of this study was to investigate the impact of apparent temperature on spontaneous preterm delivery (PTD).MethodsA case-crossover study of 14,466 singleton spontaneous preterm deliveries occurring between January 1, 1995 and December 31, 2009 among Kaiser Permanente Northern California (KPNC) members was conducted. Preterm deliveries were identified through KPNC's Electronic Health Records (EHR) data. Data on gestational age at delivery, infant sex, and maternal address were also extracted from KPNC's EHR and linked to meteorologic and air pollution monitoring data based on residential zip code.ResultsAn 11.6% (95% CI: 4.1, 19.7) increase in spontaneous PTD was associated with a 10 °F (5.6 °C) increase in weekly average (lag06) apparent temperature, during the warm season. During the cold season, increases in apparent temperature did not significantly impact the overall effect of spontaneous PTD (6.2%, (95% CI: -3.0, 16.2) per 10 °F (5.6 °C) increase in weekly average (lag06) apparent temperature). Significant differences in the relationship between apparent temperature and spontaneous PTD emerged for region, gestational age and infant sex, during the cold season. No significant differences emerged for air pollutants.ConclusionsOur findings provide evidence for an increase in the odds of spontaneous PTD associated with increases in apparent temperature, especially during the warm season.

Graphene as a photothermal actuator for control of lipid mesophase structure.

The optical density of pristine graphene is high and broad in the near infrared region of the electromagnetic spectrum positioning this material as a highly efficient photothermal agent for in vivo applications. In this study, surfactant assisted exfoliated graphene was incorporated within bulk lipid samples of varying lipid types: glyceryl monoether, glyceryl monooleate and phytantriol. The pristine graphene sheets did not disrupt the packing of the liquid crystals while being in sufficiently intimate contact to provide localized heating and induce phase transitions. The phase progressions induced through heating using NIR irradiation of the entrained graphene particles within the bulk liquid crystal were studied using SAXS and confirmed using polarized optical microscopy. Increases in apparent temperature experienced by the matrix of up to 50 °C were observed by establishing a SAXS versus bulk temperature calibration curve allowing in situ measurements. The studies demonstrate the potential for use of graphene as a photothermal actuator across a range of lipid based systems of interest in controlled drug delivery.

The importance of heating duration for Raman CM thermometry: evidence from contact metamorphism around the Great Whin Sill intrusion, UK

AbstractThe degree of crystallinity of amorphous carbonaceous material (CM) increases with heating. Previous studies have shown good correlations between maximum temperature and the structural state of CM as measured by Raman spectroscopy. Changes in CM are also expected to depend on the time‐scale of heating, but there are very few data that can be used to define this relationship. Thermal modelling of contact metamorphism developed around the 66 m thick Great Whin Sill in County Durham, England, shows that the time‐scale of heating was on the order of ~40–270 years with a temperature range of ~300–680 °C within ~110 m from the sill contact. Raman spectroscopy reveals a significant increase in the crystallinity of the CM (from a less crystallized D1‐band width of ~110 cm−1 up to a well crystallized R2 peak area ratio of ~0.43) within ~50 m from the sill contact—corresponding to an apparent increase in temperature of up to ~200 °C when estimated using conventional Raman CM geothermometry. Over this distance, the temperatures derived from thermal modelling exceed ~400 °C and heating occurred over a time‐scale of c. 100 years. Combining the results of this study with the results of previous work shows both the maximum attained temperature and the duration of heating have a significant effect on the resulting Raman spectra and demonstrates the utility of this method to derive quantitative descriptions of the kinetics of CM crystallization in rocks.

Association Between High Ambient Temperature and Risk of Stillbirth in California.

Recent studies have linked elevated apparent temperatures with adverse birth outcomes, such as preterm delivery, but other birth outcomes have not been well studied. We examined 8,510 fetal deaths (≥20 weeks' gestation) to estimate their association with mean apparent temperature, a combination of temperature and humidity, during the warm season in California (May-October) from 1999 to 2009. Mothers whose residential zip codes were within 10 km of a meteorological monitor were included. Meteorological data were provided by the California Irrigation Management Information System, the US Environmental Protection Agency, and the National Climatic Data Center, while the California Department of Public Health provided stillbirth data. Using a time-stratified case-crossover study design, we found a 10.4% change (95% confidence interval: 4.4, 16.8) in risk of stillbirth for every 10°F (5.6°C) increase in apparent temperature (cumulative average of lags 2-6 days). Risk varied by maternal race/ethnicity and was greater for younger mothers, less educated mothers, and male fetuses. The highest risks were observed during gestational weeks 20-25 and 31-33. No associations were found during the cold season (November-April), and the observed associations were independent of air pollutants. This study adds to the growing body of literature identifying pregnant women and their fetuses as subgroups vulnerable to heat exposure.

Infrared Visualization of the Cavity Effect Using Origami-Inspired Surfaces

Surface temperature and apparent radiative surface properties (emissivity, absorptivity) may be controlled by varying surface topology through a phenomenon known as the cavity effect. Cavities created by origami folds offer the potential to achieve dynamic control of apparent radiative surface properties through actuation. To illustrate this phenomenon, a thin (0.0254 mm) stainless-steel, specularly reflecting surface (emissivity, ε = 0.117) was resistively heated (6.74 W). Accordion-shaped folds (1.27 cm panels) were used to create V-shaped grooves that transition from 29° at the center to 180° near the edges. Thermocouples were attached to the center of each cavity panel (Figure (a)). An IR image of the surface (Figure (b)) reveals that the apparent temperature increases as the cavity angle decreases and is not necessarily indicative of the actual surface temperature. This increase is due to an increase in the number of specular reflections associated with the cavity effect. A similar folded surface was placed 7 cm from a blackbody radiator at 1000° C, to illustrate the change in apparent absorptivity with cavity angle. The cavity angle was held constant across the surface and varied between tests from 180° to 37° (Figure (c), top to bottom). The increase in apparent temperature is a direct result of the increase in apparent absorptivity for decreasing cavity angle, despite constant heating conditions.