Sweat evaporation is the body’s primary cooling mechanism, yet the physical factors governing it are not fully understood. We identify a “dueling buoyancy” effect in the context of the human body, in which perspiration vapor reduces the near-skin air density, counteracting the downward flow driven by cooling of warm air upon contact with the skin. In hot, arid, stagnant environments, this opposing buoyancy suppresses free convection and can reduce sweat evaporation by more than half. As a result, commonly used thermoregulation models can substantially underpredict body temperature (e.g., by 1°C after 2 hours of exposure to typical Arizona summer conditions). We develop compact, physics-informed models for free-convective heat transfer coefficients across wide temperature and humidity ranges, enabling improved thermoregulation modeling and thermal audits. These results enhance understanding of human heat balance and support more accurate heat-stress assessment to inform behavioral, infrastructural, and policy decisions for extreme-heat adaptations.

Clothing properties, including color, fit, style, and textile composition, strongly influence human radiative heat gain, the dominant heat transfer pathway in hot, dry climates. Although textiles are increasingly engineered to reduce the heat load across the visible and near-infrared, and far-infrared regions, comparing realistic performance of such apparel is difficult because spectral measurements alone cannot capture interactions among the environment, clothing, and the geometry of the human body. Here, we evaluated apparel using an outdoor and internally cooled thermal manikin, “ANDI”, exposed to direct sunlight under hot, low-wind conditions. By dynamically matching the manikin surface and ambient air temperatures, convective heat transfer is minimized, enabling direct measurement of net radiative heat flux. We validated the approach by comparing the outdoor performance of white and black cotton and polyester shirts under natural or controlled airflow conditions, demonstrating high repeatability at air speeds near 1 m/s. Next, we evaluated how color, fit, style, and textile composition of upper-body garments, as well as headgear, influence radiative performance. Clothing color was the dominant factor controlling radiative heat gain, with white and light-colored garments substantially outperforming dark alternatives, whereas textile composition, garment fit, and style generally had smaller effects. Similarly, light-colored hats with thicker, opaque crowns provided the greatest reduction in head heat gain, whereas black hats consisting of thin fabrics offered considerably less protection despite similar coverage. These findings reinforce long-standing recommendations to wear light-colored clothing in the sun while also demonstrating the value of objective, whole-garment testing for comparing apparel designs and validating future radiative cooling technologies intended to improve outdoor thermal comfort and safety.

Abstract Maternal thermal strain is associated with adverse pregnancy outcomes, yet fetal temperatures cannot currently be directly measured, limiting quantification of fetal thermal strain. Here, we develop two steady-state models for estimating internal temperatures in a near-term fetus. First, we improve the only previously published human fetal thermoregulation model, deriving a closed-form solution within its simplified uniform-cylinder representation. Second, we introduce a multilayer, anatomically segmented model that resolves tissue-specific temperatures. Both couple the fetal body to central blood pool and amniotic fluid compartments and incorporate a new placenta–umbilical cord heat-exchanger representation. Predictions agree with available intrauterine scalp measurements, with fetal core and head-center temperatures approximately 0.5°C and 0.8°C above maternal core, respectively. Physiologically plausible changes in umbilical cord heat-exchanger effectiveness or blood flow increased fetal temperatures by approximately 0.3°C. These models enable estimation of otherwise inaccessible temperatures, while the multilayer formulation lays a foundation for transient, coupled maternal-fetal thermoregulation modeling.

As global temperatures rise due to climate change, the frequency and intensity of heatwaves are increasing, posing significant threats to human health, productivity, and well-being. Thermoregulation models are important tools for quantifying the risk of extreme heat, providing insights into physiological strain indicators such as core and skin temperatures, sweat rates, and thermal comfort levels. This study evaluated four thermoregulation models of varying complexity, differentiated by the geometry and underlying thermoregulatory mechanisms. The models assessed include the Gagge two-node model, the Stolwijk-1971 model, the JOS3 model, and the UTCI-Fiala model. Additionally, we introduce the Stolwijk-2024 model, a modified version of the original Stolwijk model, which incorporates updated empirical coefficients derived from recent studies while retaining the original framework. The models were tested against human trial data across a wide range of extreme heat exposures, including transient extreme heat, humid heat, various physical activity levels, and clothing insulation scenarios. Our findings demonstrate that multi-node and multi-segment models, such as JOS3, UTCI-Fiala, and Stolwijk-2024, reliably predict core (average RMSD: <0.3°C) and skin (average root-mean-square deviation, RMSD: <0.6°C) temperatures, making them suitable for assessing heat strain and thermal comfort in moderate to extreme environmental conditions. In contrast, simpler models like the single-segment, two-node Gagge’s model performed poorly in predicting core temperature under conditions involving high metabolic rates (>3.75 met) in moderate to hot environments (>35°C), with an average RMSD of 1.2°C. Similarly, the Stolwijk-1971 model showed a systematic bias (∼0.45°C), underpredicting core temperatures during high metabolic rates. This study underscores the robustness and applicability of open-source models like JOS3 and Stolwijk-2024 in public health, urban design, and climate impact research, highlighting their potential to improve our understanding of heat strain and thermal comfort in the context of a warming climate.

Outdoor built environments can be designed to enhance thermal comfort, yet the relationship between the two is often assessed in whole-body terms, overlooking the asymmetric nature of thermal interactions between the human body and its surroundings. Moreover, the radiative component of heat exchange-dominant in hot and dry climates-is typically lumped into a single artificial metric, the mean radiant temperature, rather than being resolved into its shortwave and longwave spectral components. The shortwave irradiation distribution on the human body is often highly anisotropic, causing localized thermal discomfort in outdoor environments. However, no existing methods effectively quantify shortwave and longwave irradiation distributions on the human body. To address this gap, we developed two methods to quantify these processes. The first approach uses an outdoor thermal manikin with a white-coated side, enabling the separation of spectral components by subtracting measurements from symmetrically corresponding surface zones of tan color. The second hybrid approach converts radiometer measurements in six directions into boundary conditions for computational thermal manikin simulations. We evaluated irradiation distributions for various body parts using both methods during outdoor measurements across sunny, partially shaded, and fully shaded sites under warm to extremely hot conditions. In most cases, the two methods produced closely aligned results, with divergences highlighting their respective strengths and limitations. Additionally, we used the manikin to quantify irradiation attenuation provided by five long-sleeve shirts with colors ranging from white to black. These advanced methods can be integrated with airflow and thermoregulatory modeling to optimize outdoor built environments for enhanced human thermal comfort.

A segmented-scintillator-based implantation detector was developed to study the energy distribution of /1- delayed neutrons emitted from exotic isotopes. The detector comprises a 34 x 34 YSO scintillator coupled to an 8 x 8 anode Position-Sensitive Photo-Multiplier Tube (PSPMT) via a tapered light guide. The detector was used at RIBF, RIKEN for time-of-flight-based neutron spectroscopy measurement in the 78Ni region. The detector provides the position and timing resolution necessary for ion-beta correlations and time of flight measurements. The detector provides a high similar to 80% beta-detection efficiency and a sub-nanosecond timing resolution. This contribution discusses the details of the design, operation, implementation, and analysis developed to obtain neutron time-of-flight spectrum and the analysis methods in the context of neutron-rich nuclei in the 78Ni region.

Sweat secretion and evaporation from the skin dictate the human ability to thermoregulate and thermal comfort in hot environments and impact skin interactions with cosmetics, textiles and wearable electronics/sensors. However, sweating has mostly been investigated using macroscopic physiological methods, leaving micro-to-macroscale sweating dynamics unexplored. We explore these processes by using a coupled micro-imaging and transport measurement approach used in engineering studies of phase change processes. Specifically, we used a comprehensive set of ‘macroscale’ physiological measurements (ventilated capsule sweat rate (SR), galvanic skin conductance and dielectric epidermis hydration) complemented by three microscale imaging techniques (visible light, midwave infrared and optical coherence tomography imaging). Inspired by industrial jet cooling devices, we also explore an ‘air jet’ (versus cylindrical) capsule for measuring SR. To enable near-simultaneous application of these methods, we studied forehead sweating dynamics of six supine subjects undergoing passive heating, cooling and secondary heating. The relative dynamics of the physiological measurements agree with prior observations and can be explained using imaged microscale sweating dynamics. This comprehensive study provides new insights into the biophysical dynamics of sweating onset and following cyclic porewise, transition and filmwise sweating modes and highlights the roles of stratum corneum hydration, salt deposits and microscale hair.

Understanding the thermal comfort and safety of diverse populations within indoor settings requires a quantitative understanding of the primary heat exchange pathways between occupants and their surroundings: radiation and free convection. Thus far, however, free convective heat transfer coefficients have only been determined for the average Western adult. To this end, we investigated how variation in body shape impacts free convection heat transfer using an experimentally validated numerical model. The multiphysics model was compared against experiments conducted using the thermal manikin ANDI ("Advanced Newton Dynamic Instrument") in a climate-controlled enclosure across five air-to-skin temperature differences ranging from 4.9 to 13.9°C. The difference between measured and simulated heat fluxes for the whole body, and per anatomical region, was typically <5%, occasionally reaching 15-20%, for some body regions due to physical features not modeled in the virtual ANDI model. Using the validated model, we simulated free convection around a family, or diverse group, of virtual manikins representing the 1st to 99th percentile body mass index (BMI) and height variation in the United States adult population. Our results show that the free convection heat transfer coefficient is independent of human sex and height but decreases slightly with increased BMI. However, the variation from the average manikin in the whole body and regional free convection coefficients with BMI was small, not exceeding 8% and 16%, respectively. Furthermore, our regression coefficients and exponents can be derived from the theorical correlation for free turbulent convection from a vertical plate, which also explains the observed independence of the heat transfer coefficient from the manikins' height. Overall, these findings demonstrate the general applicability of using an average body shape in indoor thermal audits and/or overheating risk assessments to understand thermal comfort and heat stress. The results and valid application of the model support critical insights for human health, productivity, and well-being connected to heat and cooling in buildings.

The negative health impacts of extreme heat exposure can be mitigated by incorporating hyperlocal biometeorological observations into heat action planning, emergency responses, and heat-reducing urban design. A significant portion of outdoor human heat exposure is radiative, but it is often overlooked due to the absence of affordable, accurate, and user-friendly sensors. We developed a two cylinder anemometer and radiometer (CARla) consisting of unheated and heated gray components, which quantifies wind speed and the total radiation absorbed by the human body. The spectral properties of the gray coating match the standard short- and longwave absorptivity used in mean radiant temperature (MRT) calculations. We optimized the geometrical parameters of the cylinders, including height, wall thickness, and side-mounting, to minimize errors in MRT and wind speed measurements. Experiments were conducted across 15 outdoor sites in Tempe, Arizona, during the record-setting heat wave from August to October 2024. Results demonstrated that the MRT measured using CARla closely matched those measured using 3-way net radiometers. The average error in MRT using the new compact system was 1.3 ± 2.2 °C across a wide MRT range (20 to 75 °C). CARLa represents a significant improvement compared to other low-cost radiometers. The average difference between the CARla and ultrasonic anemometers for wind speed was − 0.05 ± 0.36 m·s−1 in the 0.25 to 3 m·s−1 range, comparable to standard low-cost anemometers. We integrated the CARla sensor with an Arduino-based logger, creating a cost-effective and accurate tool for broadly characterizing human exposure to extreme heat.

This presentation reports on the thermal conductivity of heterogeneous liquid metal-silver-polymer composites for thermal interface materials. More specifically, we report on how the polymer viscosity during composite formation impacts the ability to form thermally conductive percolation pathways of the liquid metal and silver fillers. We achieve a thermal conductivity of ~15 W M−1 K−1 for samples made with a 100 cSt viscosity polymer in a volumetric ratio of 37:13:50 (liquid metal:silver:polymer) and an applied curing pressure of 2 MPa.

Sweat secretion and evaporation from the skin dictate the human ability to thermoregulate and thermal comfort in hot environments and impact skin interactions with cosmetics, textiles and wearable electronics/sensors. However, sweating has mostly been investigated using macroscopic physiological methods, leaving micro-to-macroscale sweating dynamics unexplored. We explore these processes by using a coupled micro-imaging and transport measurement approach used in engineering studies of phase change processes. Specifically, we used a comprehensive set of ‘macroscale’ physiological measurements (ventilated capsule sweat rate (SR), galvanic skin conductance and dielectric epidermis hydration) complemented by three microscale imaging techniques (visible light, midwave infrared and optical coherence tomography imaging). Inspired by industrial jet cooling devices, we also explore an ‘air jet’ (versus cylindrical) capsule for measuring SR. To enable near-simultaneous application of these methods, we studied forehead sweating dynamics of six supine subjects undergoing passive heating, cooling and secondary heating. The relative dynamics of the physiological measurements agree with prior observations and can be explained using imaged microscale sweating dynamics. This comprehensive study provides new insights into the biophysical dynamics of sweating onset and following cyclic porewise, transition and filmwise sweating modes and highlights the roles of stratum corneum hydration, salt deposits and microscale hair.

Gallium-based liquid metals (LMs) have surface tension an order of magnitude higher than water and break up into micro-droplets when mixed with other liquids. In contrast, silicone oil readily mixes into LM foams to create oil-in-LM emulsions with oil inclusions. Previously, the LM was foamed through rapid mixing in air for an extended duration (over 2 h). This process first results in the internalization of oxide flakes that form at the air-liquid interface. Once a critical fraction of these randomly shaped solid flakes is reached, air bubbles internalize into the LM to create foams that can internalize secondary liquids. Here, we introduce an alternative oil-in-LM emulsion fabrication method that relies on the prior addition of SiO2 micro-particles into the LM before mixing it with the silicone oil. This particle-assisted emulsion formation process provides a higher control over the composition of the LM-particle mixture before oil addition, which we employ to systematically study the impact of particle characteristics and content on the emulsions' composition and properties. We demonstrate that the solid particle size (0.8 mu m to 5 mu m) and volume fraction (1%-10%) have a negligible impact on the internalization of the oil inclusions. The inclusions are mostly spherical with diameters of 20-100 mu m diameter and are internalized by forming new, rather than filling old, geometrical features. We also study the impact of the particle characteristics on the two key properties related to the functional application of the LM emulsions in the thermal management of microelectronics. In particular, we measure the impact of particles and silicone oil on the emulsion's thermal conductivity and its ability to prevent deleterious gallium-induced corrosion and embrittlement of contacting metal substrates.

To quantify how the viscosities of silicone oil (SO) and liquid metal (LM) relate to emulsion-formation (LM-in-SO versus SO-in-LM), a process was developed to produce LM pastes with adjustable viscosity and minimal oxide and bubbles. Increased LM viscosity allows greater silicone oil intake and/or intake of higher-viscosity silicone oils.

Sweat evaporation is critical to human thermoregulation, but current understanding of the process on 20 μm to 2 cm scale is limited. To this end, we introduce a wind-tunnel-shaped ventilated capsule with an infrared window for simultaneous infrared sweat imaging and evaporation rate measurement. Implementing the capsule in pilot human subject tests suggests that the common assumption of sweat being an isothermal film is only valid when the evaporation rate is low and sweat forms puddles on the skin. Before transitioning to this filmwise mode, sweating occurs in cyclic dropwise mode, displaying a 3x higher mass transfer coefficient in the same conditions. Imaging highlighted distinct phenomena occurring during and between these modes including out-of-duct evaporation, pulsating droplets, temporary and eventually lasting crevice filling, and individual drop-to-film spreading. In all, sweat evaporation is an impactful area that our results show is ripe for exploration, which can be achieved quantitatively using the introduced platform.

The ^{244}Pu(^{50}Ti,xn)^{294-x}Lv reaction was investigated at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. The experiment was aimed at the production of a superheavy element with Z≥114 by irradiating an actinide target with a beam heavier than ^{48}Ca. Produced Lv ions were separated from the unwanted beam and nuclear reaction products using the Berkeley Gas-filled Separator and implanted into a newly commissioned focal-plane detector system. Two decay chains were observed and assigned to the decay of ^{290}Lv. The production cross section was measured to be σ_{prod}=0.44(_{-0.28}^{+0.58})  pb at a center-of-target center-of-mass energy of 220(3) MeV. This represents the first published measurement of the production of a superheavy element near the "island of stability," with a beam of ^{50}Ti and is an essential precursor in the pursuit of searching for new elements beyond Z=118.

The 9 decays of 87 Br, 88 Br, and 87 Kr were measured with the Modular Total Absorption Spectrometer (MTAS) at Oak Ridge National Laboratory's Holifield Radioactive Ion Beam Facility (HRIBF). Both bromine isotopes are 9-delayed neutron emitters that have large cumulative fission yields and were identified as top-priority cases for total absorption study by the Nuclear Energy Agency in 2007. Our investigations corroborate that the decay schemes of 87 Br and 88 Br suffer from the so-called pandemonium effect. Unique MTAS properties enable direct neutron measurements. We present MTAS-derived 9-delayed neutron spectra, 9-delayed neutron emission probabilities of P n ( 87 Br) = 2.36(24)%, and P n ( 88 Br) = 6.4(6)%, and the 9-delayed neutron transitions intensity of 4(2)% to the first excited 87 Kr state, populated in the 9-neutron decay of 88 Br. Incorporating new data into calculations of the electromagnetic decay heat component emitted during thermal neutron fission of 235U and 239 Pu improves agreement with experimental data up to approximately 80 s after fission. The estimation of the nuclear reactor nu e flux results in changes of up to 1% in the expected nu e interactions with the detector material for 235 U, 238 U, 239 Pu, and 241 Pu.

The first complete measurement of the β-decay strength distribution of _{17}^{45}Cl_{28} was performed at the Facility for Rare Isotope Beams (FRIB) with the FRIB Decay Station Initiator during the second FRIB experiment. The measurement involved the detection of neutrons and γ rays in two focal planes of the FRIB Decay Station Initiator in a single experiment for the first time. This enabled an analytical consistency in extracting the β-decay strength distribution over the large range of excitation energies, including neutron unbound states. We observe a rapid increase in the β-decay strength distribution above the neutron separation energy in _{18}^{45}Ar_{27}. This was interpreted to be caused by the transitioning of neutrons into protons excited across the Z=20 shell gap. The SDPF-MU interaction with reduced shell gap best reproduced the data. The measurement demonstrates a new approach that is sensitive to the proton shell gap in neutron rich nuclei according to SDPF-MU calculations.

Concurrent increases in homelessness and heat intensity, duration, and frequency translate to an urban heat risk trap for the unsheltered population. Homelessness is both a driver and consequence of poor health, co-creating distinct geographies with various risk factors that exacerbate heat vulnerability. We tested the efficacy of different tent shadings over identical tents often observed in the Phoenix area (white bedsheet, mylar, tarp, and aluminum foil) and compared them to a control tent (uncovered) and ambient conditions. We monitored all meteorological variables at all six locations, notably Mean Radiant Temperature (MRT). The in-tent microclimate variability was applied to complete statistical and physiological modeling including the use of behavioral or recreational drugs on heat strain. Findings indicate that tent shadings resulted in significantly lower in-tent MRT during the day (p < 0.05), but exacerbated in-tent thermal risk during the night compared to the control tent and ambient conditions. Furthermore, we found evidence that the temperature metric matters, and using only either MRT or air temperature (Tair) to assess “heat” could lead to inconsistent conclusions about in-tent microclimate. Interactions between shade types and time significantly amplified in-tent thermal risk. Physiological modeling indicates a higher risk of heat strain (core temperature beyond 40˚C) for those taking certain drugs. Decision makers should promote testing different heat intervening strategies toward realizing effective means of protecting human life and preventing heat illnesses. This study illuminates the need for an interdisciplinary approach to studying tents as shelters that considers the total heat load with heat strain modeling.

Extreme heat is a current and growing global health concern. Current heat exposure models include meteorological and human factors that dictate heat stress, comfort, and risk of illness. However, radiation models simplify the human body to a cylinder, while convection ones provide conflicting predictions. To address these issues, we introduce a new method to characterize human exposure to extreme heat with unprecedented detail. We measure heat loads on 35 body surface zones using an outdoor thermal manikin (“ANDI”) alongside an ultrasonic anemometer array and integral radiation measurements (IRM). We show that regardless of body orientation, IRM and ANDI agree even under high solar conditions. Further, body parts can be treated as cylinders, even in highly turbulent flow. This geometry-rooted insight yields a whole-body convection correlation that resolves prior conflicts and is valid for diverse indoor and outdoor wind flows. Results will inform decision-making around heat protection, adaptation, and mitigation.

Isomer spectroscopy of heavy neutron-rich nuclei beyond the N=126 closed shell has been performed for the first time at the Radioactive Isotope Beam Factory of the RIKEN Nishina Center. New millisecond isomers have been identified at low excitation energies, 985.3(19) keV in 213Tl and 874(5) keV in 215Tl. The measured half-lives of 1.34(5) ms in 213Tl and 3.0(3) ms in 215Tl suggest spins and parities 11/2- with the single proton-hole configuration h11/2 as leading component. They are populated via E1 transitions by the decay of higher-lying isomeric states with proposed spin and parity 17/2+, interpreted as arising from a single s1/2 proton hole coupled to the 8+ seniority isomer in the (A+1)Pb cores. The lowering of the 11/2- states is ascribed to an increase of the h11/2 proton effective single-particle energy as the second g9/2 orbital is filled by neutrons, owing to a significant reduction of the proton-neutron monopole interaction between the h11/2 and g9/2 orbitals. The new ms-isomers provide the first experimental observation of shell evolution in the almost unexplored N>126 nuclear region below doubly-magic 208Pb.