Effect Of Ambient Temperature Research Articles

Thermal protection of a vertical plate using ethylene glycol film cooling flowing down on a vertical plate

This paper concerns a numerical investigation of the evaporative cooling of liquid film falling along a vertical channel. The first plate is insulated and wetted by an ethylene glycol liquid film while the second one (y = d) is dry and isothermal. A marching procedure is employed for solution of the equation of mass momentum, energy and concentration in the flow. Numerical results for air-ethylene glycol system are presented. The effects of ambient gas temperature and inlet vapor mass fraction of ethylene glycol on the heat and mass transfer and on the ethylene glycol liquid film evaporation are investigated.

Investigating the effects of ambient temperature on photoelectric unit operation

In this paper, effects of low and high ambient temperatures on the operation of a photoelectric unit are investigated. The research methodology consisted in determination of the energy efficiency of a photoelectric unit across a wide range of ambient temperatures, providing graphical interpretations and describing the procedure of field observations. Regularities in determining the average statistical indicators of energy efficiency rise and drop in a photoelectric unit were applied for a particular range of ambient temperatures. These studies were undertaken during the winter of 2021 in the Materials Science Laboratory of V.P. Larionov Institute of Physical-Technical Problems of the North, Siberian Branch of the Russian Academy of Sciences, using a fixed climate chamber. Reference parameters were obtained for changes in the photoelectric unit generating capacity (within -60ºC to +60ºC), which can be applied in modeling operational processes and engineering calculations of operating conditions of solar power plants. It was found that, at the same illumination and ambient temperature values, a photoelectric panel generates the maximum energy at -60ºC and minimal energy at +60 ºC, with the specific power drop for this temperature range being 19%. A significant drop in the specific power of the photoelectric unit was achieved at +30 ºC and higher due to the increased internal resistance of the unit. For temperatures below -40ºC, the specific power of the analyzed unit increased insignificantly due to the decreased internal resistance of the unit. The obtained values of the generating capacity of a photoelectric unit within a wide range of ambient temperatures can be used in developing a procedure for evaluating the effects of ambient temperature and its various ranges on the operation of photoelectric units, as well as for a more accurate determination of the solar generation energy potential under certain climate conditions. In future studies, field observations are planned to identify the nature of the effect of two and more climatic factors on the operation of a photoelectric unit.

Thermal analysis of phase change material encapsulated li-ion battery pack using multi-scale multi-dimensional framework

Li-ion batteries are employed to propel Electric vehicles (EVs) and Hybrid Electric Vehicles (HEVs) into a clean and sustainable future. A battery pack experiences high heat generation under extreme and abusive conditions, which may lead to catastrophic thermal runaway. The present study proposes an efficient and economical Phase Change Material (PCM) based Battery Thermal Management System (BTMS) to avoid thermal runaway. A 3D simulation is performed on a single battery (1P1S) and a battery pack consisting of six batteries stacked in series (1P6S), with and without PCM, using the multi-scale multi-dimensional Newman, Tiedemann, Gu, and Kim (NTGK) model in ANSYS. The NTGK model analyzes the battery pack's discharge behavior and thermal performance. For PCM-based BTMS, the NTGK is coupled with the solidification and melting model. The effect of ambient temperature, discharge rate, and convective heat transfer coefficient on 1P1S and 1P6S battery packs with and without PCM is investigated under extreme and abusive conditions. The ambient temperature (Tamb) significantly impacts PCM selection and battery performance. The effective T­amb – PCM combinations are proposed for the optimal working of the battery pack. Under the extreme conditions of the fast-discharging rate, the PCM-based BTMS reduces the maximum battery temperature by 25.3 K and 19.5 K and improves the temperature uniformity by 5.3 K and 3.6 K at 5C and 4C discharge rates, respectively. Also, at Tamb of 300 K, the proposed PCM-based BTMS significantly reduces the maximum temperature by 60.4 K, 46 K, and 29.3 K when the external shorting resistance is 0.10, 0.15, and 0.25 Ω, respectively. The proposed cooling system averts the thermal runaway when external shorting is 0.10 Ω, and internal shorting is >0.1 μΩ. This research will be helpful in the further development of PCM-based thermal management systems for large-scale and commercial applications.

Finding the Goldilocks zone: Effects of ambient temperature on mortality of hospitalized older adults.

None of the authors reported potential, real, or perceived conflicts of interest or additional financial disclosures. Table S1. Summary statistics for admissions of acutely ill older adults, according to in-hospital death, 2009–2019. Table S2. Summary statistics for ambient temperature, relative humidity, and air pollutants in Sao Paulo, Brazil, 2009–2019 (n = 105,192 hourly measures).1 1CETESB. Qualidade do Ar. CETESB. https://cetesb.sp.gov.br/ar/qualar. Table S3. Association between mean daily ambient temperature and hospital mortality in acutely ill older adults, 2009–2019 (n = 2164 admissions). Figure S1. Study flowchart. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Influence of hydrogen fuel cell temperature safety on bus driving characteristics and stack heating mode

Hydrogen fuel cells have developed rapidly in bus because of their cleanliness. The driving parameters of hydrogen fuel cell bus and the internal temperature distribution of hydrogen fuel stack are investigated in this study. The 1-D model of hydrogen fuel cell bus and the 2-D model of hydrogen fuel cell stack are established based on AMESim. In the cooling process, for the existing typical thermal management system, the influence of ambient temperature on the fuel cell bus driving parameters is analyzed by the 1-D model. In the heating process, the internal temperature distribution of the stack is analyzed under three heating modes by the 2-D model. As the ambient temperature increases, to ensure the safe operating temperature of the fuel cells, the bus top speed should be reduced, and the acceleration time should be extended. When the stack needs to be heated, the gas-liquid heating mode can supply a more uniform temperature distribution inside the stack. • The 1-D vehicle model and 2-D stack model of hydrogen fuel cell are established. • The effect of ambient temperature on driving parameters is analyzed. • The internal temperature distribution of the stack is analyzed under three heating modes. • Gas-liquid heating mode can give a more uniform stack temperature distribution.

Experimental investigation of a post-combustion pool fire phenomenon due to the spray-wall interaction under DI engine-like cold-start conditions

Spray-wall interactions (SWI) have remained nowadays as an active area of research and the complex multi-physical field processes between the spray and the wall are still not well understood. In this study, a post-combustion pool fire phenomenon due to the SWI was found by optical diagnostic techniques: pool fire appeared near the stagnation point after spray combustion. The spray combustion and pool fire are not continuous. This abnormal combustion characteristic under low ambient temperature conditions (680–720 K) was investigated and the effect of ambient temperature on the macroscopic characteristics of pool fires was quantified and analyzed. The results show that the wall-attached fuel film will be re-ignited and continue to combust for a longer period after the impingement spray combustion. The appearance moment, dwell time, fire duration, and macroscopic characteristics of this post-combustion pool fire are non-monotonic as a function of the ambient temperature. When the ambient temperature is 700 K, the post-combustion pool fire appears earliest, the dwell time is the smallest, and the pool fire duration, flame length, and flame height of the pool fire are the largest. This is mainly dominated by the gas temperature around the wall-attached fuel film and fuel film mass.

An Improved Noise Modeling Method Using a Quasi-Physical Zone Division Model for AlGaN/GaN HEMTs

Accurate characterization of transistor noise performance is significant for low-noise amplifier (LNA) design. The conventional empirical noise model contains too many fitting parameters and thus relies on a large number of on-wafer noise measurements, especially the ambient temperature effects modeling. In this article, an improved noise modeling method using the quasi-physical zone division (QPZD) theory is proposed. The boundary potential calculation in the traditional modeling method is improved by considering the effects of the charge depletion region when the transistor is in the ON-state, which can result in at least two orders of magnitude improvement in the accuracy of the noise power spectral density (PSD). With this improvement, the noise performance can be accurately predicted without adding any fitting parameters in the noise PSD models. Furthermore, ambient temperature modeling of the noise performance is realized by considering the ambient temperature effects of drain–source current <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {ds}}$ </tex-math></inline-formula> with a modified <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {off}}$ </tex-math></inline-formula> model and some other significant intrinsic parameters. Verification shows that the proposed QPZD noise model with the improved boundary potential calculation method can well predict the noise performance and scattering parameters at different ambient temperatures. The method of this study can be applied to physical-based noise modeling of GaN high-electron-mobility transistors (HEMTs) and LNA design.

An Experimental Study on Novel Gas Discharge Tubes With Graphene as Electron Emission Material

Electrical equipment is subjected to gas discharge tube (GDT) direct current (dc) breakdown voltage dispersion and breakdown voltage drop after a surge. It is noteworthy that GDT damage may even cause the failure of electrical equipment. Accordingly, the chemical vapor deposition (CVD) of graphene was proposed in this study as an electron emission material of the GDT based on the existing electron powder GDT. The GDT exhibiting a voltage class of 470 V was prepared, and its structure and surge characteristics were analyzed. The effects of gas pressure, aging time, and ambient temperature on the breakdown voltage of the graphene GDT were studied. The surge process of the graphene GDT was simulated using the 8/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20~\mu \text{s}$ </tex-math></inline-formula> impulse current generator, and the resistance ability of the graphene GDT against the surge was examined. Moreover, it was compared with the same type of commercial electron powder GDT. As indicated by the experimental results, a positive correlation was identified between the gas pressure and the dc breakdown voltage of the graphene GDT under a certain pressure. The effect of aging time and ambient temperature on dc breakdown voltage was limited. The breakdown voltage of the graphene GDT was first increased and then decreased with the increase in the number of surges. After 100 surges, the breakdown voltage of the graphene GDT stabilized at 350 V, whose stability was better than that of the electron powder GDT. The above-described analysis confirmed that graphene GDT exhibits better surge resistance ability.

NMC811-Li6PS5Cl-Li/In All-Solid-State Battery Capacity Attenuation Based on Temperature-Pressure-Electrochemical Coupling Model

Solid-state batteries have been widely studied due to their unique advantages such as high mechanical strength, good temperature adaptability, and long cycle life. However, the coupling effect of external pressures and ambient temperatures on the cycle performance of solid-state batteries has not been systematically elucidated. Based on the finite element simulation, this work establishes a temperature-pressure-electrochemical coupling model to assess the coupling effect of temperature and pressure on the cycle capacity decay of solid-state batteries. Taking an NMC811-Li6PS5Cl-Li/In solid-state battery as an example, the results show that the optimal pressure range of the battery is 127.38 MPa-254.76 MPa. Applying external stress to a solid-state battery can significantly reduce its capacity decay rate, 191.07 MPa was selected in the optimal stress interval, ten cycles of charge-discharge cycle experiment were carried out on NMC811-Li6PS5Cl-Li/In battery at an ambient temperature of 60 °C, the tenth turn capacity of this battery only decays to 97.78% of the initial capacity, while the tenth turn capacity of the non-pressure battery decays to 96.57%. The model established in this study provides an effective approach for finding the optimal external pressure range for solid state batteries, which will contribute to the development of batteries with longer cycle life.

Evaluating the short-term effect of ambient temperature on non-fatal outdoor falls and road traffic injuries among children and adolescents in China: a time-stratified case-crossover study.

Supplementary material is available in the online version of this article at 10.1007/s11783-023-1705-1 and is accessible for authorized users.

Biomass combustion behaviors based on online monitoring system: Morphological, thermodynamic and kinetic analysis

Identifying the matching law between the morphology, thermodynamic and kinetic characteristics of single biomass can significantly achieve high-efficiency combustion. A visual combustion furnace with online monitoring system was designed and built to record in real-time the apparent volume shrinkage, particle heating process and gas releasing behaviors of single biomass briquette during the combustion process. Furthermore, this work aimed to present a new method to infer the effect of ambient temperature on the pore structure of volatile precipitation and char combustion, mainly through a comparative analysis of the changes in shrinkage ratio and activation energy with carbon conversion efficiency (CCE). The higher the ambient temperature, the faster the biomass heating rate, and the earlier it reached the peak heating rate and the ambient temperature, but the heating process of biomass in the water evaporation stage was almost the same at different ambient temperatures. Oxygen concentration had a significant effect on the volume shrinkage and gas product releasing characteristics, but less on the particle heat transfer. After deducting the experimental system errors, the biomass reaction mode, activation energy and pore structure changed significantly around 40–45% CCE. When the CCE was less than 40%, the biomass mainly underwent volatile precipitation and combustion, with smaller apparent volume shrinkage but larger pore volume at 700 °C compared to 900°C ambient temperature. With the CCE greater than 45% and less than 70%, the char combustion dominated the reaction process, the apparent volume shrinkage was smaller, but the pore structure was more developed at higher ambient temperatures compared to lower temperatures. When the CCE exceeded 70%, the apparent volume and carbon conversion remained almost constant at 700°C, but the volume shrinkage ratio continued to decrease at 900°C ambient temperature. This research and proposed method provide more accurate fundamental support for modeling particle combustion at the reactor scale and designing biomass combustion systems.

Experimental Investigation of the Effects of Insulation Materials and Concrete Strength on Temperature Transitions in FRP Reinforced Structural Elements Under High Temperature

There are serious concerns about the preference of Fiber Reinforced Polymer (FRP) bars, which are widely used in buildings, in reinforced concrete structures due to their sensitivity to high temperatures. Especially in cases where the glass transition temperature of FRPs exceeds, losses occur in the mechanical and physical properties of FRP bars. Fire insulation materials used in reinforced concrete structures are of great importance in protecting the building elements against high temperatures. Insulation materials protect concrete and rebars against high temperatures and prevent strength reductions. In this study, the effects of different fire insulation materials and concrete strength on temperature transitions in FRP reinforced concrete structural elements were determined by experimental studies. The protection performances of the concrete and the rebars in the concrete against the effects of temperature were investigated. The study was carried out in 500 oC environments that can reach the glass transition temperature (80-110 oC) of FRP bars. Ambient temperatures, concrete surface temperatures and reinforcement surface temperatures in the concrete were measured depending on time with the experimental setup created. As a result of the study, it was determined that fire insulation materials are more effective than concrete strengths. In the effect of ambient temperature on the concrete surface, while the rock wool allowed a temperature transition of 13%, this value was 22% in glass wool and 26% in red drywall.

Human body heat-driven thermoelectric generators as a sustainable power supply for wearable electronic devices: Recent advances, challenges, and future perspectives

Thermoelectric generators are devices that directly convert heat flux or the temperature difference between two hot and cold surfaces into electricity. With the advancement of the Internet of Things (IoT) technology and the development of wearable and portable devices, the issue of providing a sustainable power source is one of the main challenges in the development path of these tools. Creating electric power by harvesting the waste heat from the human body is one of the effective solutions in this way. For this reason, the development and improvement of the technology of wearable thermoelectric generators have received much attention recently. Due to the low-temperature difference between the two sides of wearable thermoelectric generators and the high thermal resistance between the skin and the heated surface of these modules, the performance of these systems is highly dependent on their structural parameters and environmental factors. In this paper, it has tried to review all the previous studies regarding the impact of structural factors (such as the matching of internal and external thermal resistances, geometrical parameters of the module, design of heat source and sink, and flexibility of thermoelectric module) and environmental parameters (including the effect of ambient air temperature and humidity, skin temperature, and the interaction of power consumers with thermoelectric modules). Based on the studies, it seems that in optimizing the performance of wearable thermoelectric generators (WTEGs), it is necessary to consider the effect of the human body's thermoregulatory responses, such as skin temperature and sweating rate. The change in skin temperature directly affects the performance of WTEGs, and the change in sweating rate can also affect the thermal resistance between the skin and the hot plate and overshadow the matching of thermal resistances during operation.

Association between ambient temperature and chronic rhinosinusitis.

Chronic exposure to particulate matter air pollution (PM2.5 ) is associated with chronic rhinosinusitis (CRS). Elevated ambient temperature may increase PM2.5 levels and thereby exacerbate sinonasal symptoms. This study investigates the association between high ambient temperature and the risk of CRS diagnosis. Patients with CRS were diagnosed at Johns Hopkins hospitals from May to October 2013-2022, and controls were matched patients without CRS meanwhile. A total of 4752 patients (2376 cases and 2376 controls) were identified with a mean (SD) age of 51.8 (16.8) years. The effect of maximum ambient temperature on symptoms was estimated with a distributed lag nonlinear model (DLNM). Extreme heat was defined as 35.0°C (95th percentile of the maximum temperature distribution). Conditional logistic regression models estimated the association between extreme heat and the risk of CRS diagnosis. Exposure to extreme heat was associated with increased odds of exacerbation of CRS symptoms (odds ratio [OR] 1.11, 95% confidence interval [CI] 1.03-1.19). The cumulative effect of extreme heat during 0-21 lag days was significant (OR 2.37, 95% CI 1.60-3.50) compared with the minimum morbidity temperature (MMT) at 25.3°C. Associations were more pronounced among young and middle-aged patients and patients with abnormal weight. We found that short-term exposure to high ambient temperature is associated with increased CRS diagnosis, suggesting a cascading effect of meteorological phenomena. These results highlight climate change's potentially deleterious health effects on upper airway diseases, which could have a significant public health impact.

An Experimental Study on Ice Accretion under Bridge Cable in Different Conditions

The ice accumulation on the surface of the stay cable of the bridge is a frequently identified problem that threatens the safety of bridge traffic. Therefore, it is important to investigate the ice accumulation on the stay cable under different conditions. To understand the distribution characteristics and variation rules of ice, this study analyzed the effects of ambient temperature, cable inclination angle, and diameter on the ice accumulation of the high-density polyethylene (HDPE) stay cable. The results show that the ambient temperature significantly affects ice formation in the lower part of the stay cable. Low temperature facilitates the formation and growth of icicles, while larger size and inclination angle of the stay cable inhibit the icicle growth. When the inclination angle of the cable is less than 60°, icicles easily form at the bottom of the cable. Smaller-diameter cables are more likely to accumulate icicles at the bottom.

Effect of Ambient Temperature on the Mechanical Properties of High Ductility Concrete

This study analyzes the mechanical properties of high ductility concrete (HDC) under different ambient temperatures to provide a parameter basis for the design of HDC bridge deck link slabs. Five temperatures (-30, 0, 20, 40, and 60 °C) were designed to investigate the compressive, tensile, and flexural properties of HDC after temperature treatment and analyze the pore structure. The results show that, compared with the HDC performance at room temperature (20 °C), the compressive strength, ultimate tensile strength, and flexural strength decreased after treatment at low temperatures (-30 and 0 °C), while the strength increased after treatment at high temperatures (40 and 60 °C). After experiencing low- and high-temperature treatments, the ultimate tensile strain and ultimate deflection of the HDC increased. The tensile and flexural failures of the HDC exhibited multiple cracking, and the stress-strain/deflection curve showed a strain/deflection hardening stage. The tensile constitutive relationship can be simplified as a bilinear two-stage relationship. As the temperature increased, the porosity of harmless and less harmful pores in HDC gradually increased, while the porosity of harmful and more harmful pores gradually decreased, resulting in an increase in HDC strength. Based on the influence of temperature on HDC properties, design parameters for the HDC bridge deck link slab structure are proposed.

Thermal management of photovoltaic-thermoelectric generator hybrid system using radiative cooling and heat pipe

Temperature regulation of photovoltaic modules is crucial for improving their efficiency. Nowadays, radiative cooling is a widely adopted passive thermal management technique for photovoltaic systems. Heat pipe and radiative cooling are two primary passive photovoltaic cooling methods employed in photovoltaic-thermoelectric generator hybrid systems. Therefore, this study proposes a novel photovoltaic-heat pipe-thermoelectric generator-radiative cooling hybrid system by applying heat pipe and radiative cooling simultaneously to control the temperature of the photovoltaic-thermoelectric generator hybrid system. A detailed computational model of the proposed system is developed and analyzed in the COMSOL Multiphysics. A comparative analysis of the photovoltaic module temperature drop and its efficiency enhancement between the proposed and the reference system consisting of only a photovoltaic module is performed. The effects of solar radiation, ambient temperature, and wind speed on both systems are studied under the Atacama Desert and Las Vegas climatic conditions. This proposed configuration reduced the photovoltaic temperature by efficiently evacuating its residual heat using a heat pipe and then rejecting it to the atmosphere using a radiative cooler. Results show that in contrast to the reference system, the proposed system reduced the average photovoltaic operating temperature by 2 °C for both the summer and winter seasons of the Atacama Desert and by 13 °C for Les Vegas. The maximum and minimum reductions of the photovoltaic temperature in the proposed system, as compared to the reference system, are 4 °C and 1.5 °C respectively, in June and 9 °C and 1 °C respectively, in January for the Atacama Desert. The maximum PV conversion efficiency and energy production improvements as compared to the reference system are 0.8% & 1.03% respectively, (for summer), and 0.3% & 0.94% respectively, (for winter) for the Atacama Desert, and 1.8% & 7.2% respectively, for the Las Vegas environment. The expected range of LCOE for a hybrid PV-HP-TEG-RC system is found to be between 0.065-0.089 USD/kWh. This study can help in improving the energy conversion efficiency by controlling the photovoltaic temperature using passive cooling methods in harsh environmental conditions such as the desert locations.

Effect of high ambient temperature on physiological responses during incremental exercise in Thoroughbred horses

Several reports have suggested that the risk of exertional heat illness (EHI) in Thoroughbred racehorses increases in high ambient temperatures. Heat dissipation in horses during exercise becomes less efficient when the body temperature and ambient temperature are close. Therefore, we hypothesised that exercise at 40 °C may increase body temperature, oxygen consumption, and cardiac output during incremental exercise tests compared to 20 and 30 °C. Six trained Thoroughbred horses were studied in a randomised, crossover design at three ambient temperatures with a 6-day washout period. Using a 3% inclined treadmill, horses performed incremental exercise tests at 1.7, 3.5, 6, 8, and 10 m/s for 90 s at ambient temperatures of 20, 30, and 40 °C. The effects of ambient temperature at 10 m/s on physiological variables were analysed using mixed models (P&lt;0.05). Pulmonary arterial temperature and rectal temperature at 40 °C were higher than those at 20 °C (P&lt;0.001) and 30 °C (P&lt;0.001). Similarly, oxygen consumption (vs 20 °C, P=0.009; vs 30 °C, P=0.006) and cardiac output (vs 20 °C, P=0.001; vs 30 °C, P=0.001) at 40 °C were higher than those at 20 and 30 °C. Arterial O2 partial pressure, O2 saturation, and pH at 40 °C were lower than those at 20 and 30 °C. Arterial CO2 partial pressure at 40 °C was higher than that at 20 and 30 °C. No differences were observed in arterial-mixed venous O2 concentration difference (P=0.391) and plasma lactate concentration (P=0.134) at different ambient temperatures. These results indicate that exercise at 40 °C causes excessive high body temperature, decreased running economy, and increased cardiac output compared to exercise at 20 and 30 °C. We strongly suggest that trainers and veterinarians should anticipate the occurrence of increased thermal stresses when ambient temperature is extremely high even in dry conditions and prepare to mitigate the risk of EHI from the perspective of equine welfare.

Nationwide assessment of atmospheric organochlorine pesticides over a decade during 2008–2017 in South Korea

Long-term nationwide atmospheric monitoring of organochlorine pesticides (OCPs) was performed in South Korea during 2008–2017. Their occurrences, seasonal and temporal variability, sources, and effect of ambient temperature were investigated. The OCPs are pronounced with a mean concentration of total OCPs ranging from 5.2 to 256 pg/Sm3. However, a decrease of 54 % was observed in the mean concentration of total OCPs from 2008 to 2017 associated with regulatory actions. OCP concentrations did not show any variations between the different site types, and OCPs were ubiquitously present at all site types. The mean concentration of total OCPs in summer was two-fold higher than in winter. The concentrations of DRINs, DDTs, ENDOs, and HCHs were significantly higher in summer, but the concentrations of chlordane and heptachlor were higher in winter. The diagnostic ratios identified major sources as ongoing sources, past use, and atmospheric transport. Clausius Clapeyron plots strongly suggested the re-emission of α-endosulfan, β-endosulfan, α-HCH, and β-HCH, and ΔHsa (enthalpy of surface air exchange) values suggested the influence of the transport and/or new sources on aldrin, dieldrin, and chlordane. The occurrence of OCPs due to re-emissions, ongoing sources, and long-range atmospheric transport could be a challenge towards the complete phase-out of OCPs in South Korea.

A sudden and widespread change in symptoms and incidence of vascular streak dieback of cocoa (Theobroma cacao) linked to environmental change in Sulawesi, Indonesia

Unstable new-encounter relationships between plants and pathogens form when organisms are transported between once-isolated biogeographic regions. Ceratobasidium theobromae is a new-encounter pathogen that has plagued the cocoa industry causing vascular streak dieback in Southeast Asia and western Melanesia. The disease underwent a sudden change in symptoms associated with an increase in disease incidence in Indonesia and Malaysia from about 2004. These changes have not been linked to changes in the pathogen or host and this shift could signal an effect of region-wide environmental changes in the responses of cocoa trees to infection. To study the effect of ambient temperature on symptom expression, this study assessed disease symptoms in cocoa trees along altitudinal gradients in Sulawesi, Indonesia. It recorded types of VSD symptoms (necrotic or chlorotic) in clones and local hybrids on managed farms, and in a reciprocal transplant experiment. The results found that consistently across landscapes, in trees of varying inherent susceptibilities to VSD, the incidence of new, necrotic symptoms decreased with altitude and was restricted to lowlands, while the chlorotic symptoms that originally characterised the disease were found throughout the altitudinal range. The new symptom pattern in cocoa appears to be an environmentally driven change in tree responses to the pathogen, possibly related to recent climate warming or elevated atmospheric concentration of CO2 due to widespread burning of forest and peat beds in Indonesia. The increased occurrence of a necrotic response of leaves to invasion by C. theobromae is typical of a hypersensitive response often associated with resistance to invasion by pathogens and could indicate enhanced resistance, although prolonged attachment of diseased leaves allows increased sporulation of the fungus and increased disease incidence.These are the first results to show an altered plant host–fungus pathogen response likely due to climate change, indicating that global warming may cause subtle but ecologically important changes in plant-parasite interactions. New-encounter relationships that are less stable than long-term co-evolved relationships might provide early-warning of ecological changes due to climate change. Determining whether the changed symptoms are a new threat is vital knowledge for farmers' livelihoods in this region.