Onset Of Summer Research Articles

Extended ozone depletion and reduced snow and ice cover-Consequences for Antarctic biota.

Stratospheric ozone, which has been depleted in recent decades by the release of anthropogenic gases, is critical for shielding the biosphere against ultraviolet-B (UV-B) radiation. Although the ozone layer is expected to recover before the end of the 21st century, a hole over Antarctica continues to appear each year. Ozone depletion usually peaks between September and October, when fortunately, most Antarctic terrestrial vegetation and soil biota is frozen, dormant and protected under snow cover. Similarly, much marine life is protected by sea ice cover. The ozone hole used to close before the onset of Antarctic summer, meaning that most biota were not exposed to severe springtime UV-B fluxes. However, in recent years, ozone depletion has persisted into December, which marks the beginning of austral summer. Early summertime ozone depletion is concerning: high incident UV-B radiation coincident with snowmelt and emergence of vegetation will mean biota is more exposed. The start of summer is also peak breeding season for many animals, thus extreme UV-B exposure (UV index up to 14) may come at a vulnerable time in their life cycle. Climate change, including changing wind patterns and strength, and particularly declining sea ice, are likely to compound UV-B exposure of Antarctic organisms, through earlier ice and snowmelt, heatwaves and droughts. Antarctic field research conducted decades ago tended to study UV impacts in isolation and more research that considers multiple climate impacts, and the true magnitude and timing of current UV increases is needed.

Incidence and influencing factors of post-stroke cognitive impairment in convalescent young patients with first-ever stroke

ObjectiveTo investigate the occurrence of post-stroke cognitive impairment (PSCI) and its influencing factors in convalescent young patients with first-ever stroke. MethodsA total of 300 first-ever young stroke patients (age ≤45 years) were collected. The Mini-Mental State Examination (MMSE) was used to assess the cognitive status. The sociodemographic data, clinical symptoms, social environment, and behavior-related information were collected and analyzed. ResultsThe incidence of PSCI in young stroke patients was 62.33 %. Through univariate analysis, there were statistical differences in different levels of education, smoking status and hypertension (P < 0.05). With subsequently multivariate logistic regression analysis, it was found that junior high school (OR=8.58,95 %CI:2.25∼32.70) and high school (OR=10.50,95 %CI:2.69∼41.00) education levels, lesion volume >3.00 cm3 (OR=8.03,95 %CI:2.28∼28.36), stroke in the frontal-parietal-temporal region (OR=7.26,95 %CI:1.58∼33.40) and the basal ganglia area (OR=6.13,95 %CI:1.24∼30.43), high NIHSS score (OR=1.17,95 %CI: 1.06∼1.29), and high diastolic blood pressure variability coefficient (OR=1.43,95 %CI: 1.02∼2.01) were risk factors for PSCI. Meanwhile, 24≤BMI<28 (OR=0.06,95 %CI:0.02∼0.23) and BMI<24 (OR=0.18,95 %CI:0.06∼0.53), hospitalization cost >20,000/month (OR=0.22,95 %CI:0.09∼0.56), and stroke onset in spring and summer (OR=0.37,95 %CI:0.14∼0.96) were protective factors. ConclusionThe incidence of PSCI is relatively high in young stroke patients. Junior high and high school education, stroke lesions >3.00cm3, strokes in the frontal-parietal-temporal and basal ganglia regions, high NIHSS scores, and high DBPV are risk factors for PSCI in young stroke patients. Meanwhile, BMI<28, treatment cost >20,000/month, and stroke onset in spring and summer are protective factors for PSCI in young stroke patients.

Neurological syndromes and potential triggers associated with antibodies to neuronal surface antigens

BackgroundAutoantibodies against surface neuronal antigens have been associated with specific neurological presentations including autoimmune encephalitis (AE), with variable association with neoplasia and infections. MethodsWe described the phenotype and environmental associations of patients with neurological syndromes associated with antibodies against neuronal surface antigens who were referred to a tertiary center in the South of Brazil. All patients were tested for neuronal autoantibodies using cell-based assays. Clinical, radiological, and laboratory findings were retrospectively reviewed. ResultsWe identified 16 patients, 15 had subacute, and one had a progressive disease course. Among patients with subacute onset, 11 (73 %) were N-Methyl-d-Aspartate receptor (NMDAr-IgG)+, 3 (20 %) were Leucine-rich Glioma-Inactivated-1 (LGI1-IgG)+, and 1 (6 %) was positive for Glycine receptor-IgG. The patient with a progressive disease course had antibodies against IgLON5. Most patients had disease onset in spring and summer suggesting environmental factors for the development of AE. Also, we observed a different pattern of brain lesions when NMDAr-IgG encephalitis followed herpes encephalitis and a previously unreported association with Rosai-Dorfman-Destombe disease. All patients with encephalopathy met criteria for possible AE and all proven NMDAr-IgG+ met criteria for NMDAr-IgG encephalitis. However, only one LGI1-IgG+ patient fulfilled clinical criteria for limbic encephalitis. All but one received high-dose intravenous methylprednisolone, 11 also had intravenous human immunoglobulin, and 4 plasma exchange. Furthermore, all patients received second-line immunotherapy. Importantly, most patients improved with immunotherapy, even when initiated later in the disease course. ConclusionWe identified seasonal variability associated with neuronal surface antibodies suggesting environmental triggers. Also, we described the coexistence of NMDAr-IgG encephalitis with histiocytosis. In our series, most patients received second-line immunotherapy. We observed neurologic improvement after treatment even in cases of delayed diagnosis. Increasing the recognition and availability of tests and treatments for these conditions is of paramount importance in low- and middle-income countries.

Seasonal Variation in Neurological Severity and Clinical Outcomes in Ischemic Stroke Patients - A 9-Year Study of 5,238 Patients.

Because the effects of extreme weather conditions on stroke severity and outcomes are unclear, we evaluated seasonal variations in stroke severity and clinical outcomes. Between 2012 and 2020 we enrolled 5,238 patients with acute ischemic stroke, who were divided into 4 seasons according to stroke onset: spring, summer, autumn and winter. We analyzed the effect of season on the severity and outcomes of all subjects. Multivariable analysis showed that the winter group had 1.234-fold increased risk of moderate-to-severe neurological deficits than the summer group (95% confidence interval (CI): 1.034-1.472, P=0.020). Compared with the summer group, the winter and the spring groups experienced 1.243- and 1.251-fold the risk of suffering from worse outcomes among all patients at 6-month follow-up (95% CI 1.008-1.534, P=0.042, 95% CI 1.013-1.544, P=0.037). The 1-year follow-up revealed similar results. Further comparison of each season in the 2012-2015 and 2016-2020 periods found that the proportion of poor outcomes in the latter autumn group was lower than that in the former time period, with significant differences in both 6-month and 1-year follow-up. The onset season was related to the severity and clinical outcomes of ischemic stroke. Patients with winter onset had more severe neurological deficits and worse outcomes than those with summer onset.

Summer Onset in Northern East Asia: Feature, Mechanism and Variability

Summer in the East Asian monsoon region is characterized by heavy rainfall and high temperature. Its onset, depicted by monsoon rainfall and/or airflow as well as surface air temperature, has been well documented. However, the onset of summer season is rarely addressed in northern East Asia (NEA) around the northern edge of the East Asian summer monsoon. This study investigates the feature, mechanism, and variability of the summer onset in NEA based on the ERA-5 reanalysis dataset for 1979–2020. Results show that, in climatology, the onset of summer in NEA occurs in pentad 31 when the spring-to-summer warming process is decelerated at the highest rate. The change in the warming rate is mainly attributed to a decrease in the diabatic heat, mostly surface sensible heat, and temperature advection plays a small role. After the onset of summer, regional low-level northwesterly winds are weakened, and a local NEA cyclonic low forms. The latter, coupled with monsoon southerly airflow to the south, advects more moisture into NEA and increases regional rainfall. Furthermore, a temperature threshold of 17 °C, the climatological regional mean surface air temperature in pentad 31, was proposed to depict summer onset in NEA. Based on the temperature threshold, the year-to-year variability of summer onset timing in NEA is revealed, ranging from pentad 29 (late May) to 34 (middle June), with the standard deviation of 1.2 pentads. It advanced by 0.6 pentads, on average, after the late 1990s. This study provides a new method to objectively quantify the timing of summer onset in East Asia, which is thermodynamically explainable and may help us to depict and monitor summer onset in different latitudes and topography.

Inter‐Model Differences in Future Summer Onset Over the Northern High Latitudes

AbstractClimate models consistently project a significant advance of summer onset over the Northern high latitude lands in the late 21st century. However, large inter‐model differences exist, in particular, over Northwest Russia, Bering Sea region and Northeastern Canada. This study quantifies the influences of background global warming rate and regional snow‐albedo feedback on the inter‐model spreads in summer onset projections. Linear regression analysis reveals that models' transient climate response (TCR) values explain around 39%–50% of regional inter‐model variances, indicating the dominant contribution of models' global warming rate. When removing TCR influences, the summer onset and snow cover exhibit significant inter‐model correlations over Bering Sea region and Northeastern Canada, explaining 25%–30% of the inter‐model variances. These results suggest that global climate sensitivity as well as regional snow‐albedo feedback need to be considered for reliable projection of future summer season timing at regional scales.

Species composition of bedbugs (Heteroptera) in the rapeseed fields in the Minsk region of Belarus

The article discusses the species composition of Heteroptera in the fields of winter and spring rapeseed in the Minsk region of Belarus. A comparison of the species composition of Heteroptera in different seasons in the fields of winter rape was carried out, the dominant species and families of Heteroptera in the fields of winter and spring rape were identified.On the fields of winter rapeseed in summer, the number of species and individuals of Heteroptera is greater than in spring. 41 species were found in the fields of winter rapeseed, they belong to 11 families. Representatives of 9 species were noted among carnivore; their abundance is 23.42 %. The number of collected larvae was 20.25 % of the total number of individuals, of which 14.24 % of larvae belong to the family Miridae. The larvae appear in the fields with the onset of summer. The dominant species is Lygus rugulipennis – 30.7 %. Representatives of 16 species from 7 families of Heteroptera were found in the fields, with the dominant family Miridae – 78.23 %. Representatives of 5 species were noted among carnivore; their abundance is 8.84 %. The number of larvae collected during this period exceeded adults by 1.4 times. The Cymidae family was found only in field No. 3 of winter rape, Rhopalidae was found in the field of spring rape in 2016.

Asymmetry variations in Arctic summer onset and ending: Role of sea-ice melting

Previous studies found that in Arctic regions with severe sea ice melting, summer ending (SE) variations are significantly larger than summer onset (SO) variations in the past few decades. Based on short-term observations, researchers preliminarily suggested that radiation variations caused by an earlier melting onset could be the possible reason for asymmetric Arctic SO/ending variations (AASV). Based on observations and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis I dataset, here we quantitatively characterize AASV by calculating the difference between the 11 year sliding trend of Arctic SO and SE. The results show that AASV positively correlates with sea ice melting in summer. The increased summer sea ice melting increases the area to absorb short-wave radiation in summer and then release more long-wave radiation to heat the lower atmosphere and delay the peak time of long-wave radiation releasing. The variations in radiation lead to a significant delay of the Arctic SE, with no significant variations in SO. We introduce CMIP6 historical and future simulations of 15 models to verify further the relationship between AASV and summer sea ice melting. Historical run reproduces the observed asymmetry, and future simulations under various warming levels show that AASV will vanish with disappeared melting variations or be strengthened with increased melting. The latter could delay freeze-up and further exacerbate the following years’ melting, which will enhance AASV. Furthermore, AASV will delay the onset and peak time of Arctic amplification.

OMALIZUMAB FOR SKEETER SYNDROME: THREE SUCCESSFULLY TREATED PATIENTS

<h3>Introduction</h3> Skeeter syndrome is a rare disease associated with an overwhelming immunologic response to proteins in mosquito saliva. Typical symptoms include large local reactions, hives, swelling, blisters, fever, malaise and rarely anaphylaxis. Prevention measures include mosquito avoidance, use of insect repellants and prophylaxis with oral nonsedating H1 antihistamines. Systemic steroids are often required for severe cases. To date there is no FDA-approved treatment for Skeeter syndrome. Thousands of patients in Skeeter syndrome support groups express dissatisfaction with the lack of treatment options. Allergists have similarly been frustrated by the lack of options available for their Skeeter syndrome patients. Case reports have demonstrated the efficacy of omalizumab in treating other blistering disorders such as bullous pemphigoid. I hypothesized that omalizumab would be effective for reducing the severity of these reactions in patients who continue to suffer despite avoidance measures and standard of care. <h3>Case Description</h3> I treated three adult patients with Skeeter syndrome with 300 mg of omalizumab every four weeks initiated one month prior to the onset of summer. Treatment was continued throughout the duration of summer months when mosquito exposure remained highest. Among the three patients treated with omalizumab, over 100 bites were sustained during therapy. All three patients demonstrated a rapid improvement in the size of their local reactions with no further development of bullae after the first dose of omalizumab. <h3>Discussion</h3> This report highlights a potential therapeutic option for a rare disease and calls for further studies to demonstrate the efficacy of omalizumab for Skeeter syndrome.

Early-onset trend in European summer caused by Greenland topographic effect

Global heating, which is considered irreversible at least for the near future, causes various climate crises directly affecting human life. Accordingly, European countries have been afflicted by frequent heatwaves in summer. Convolutional neural network deep learning models have revealed the lengthening of the European summer over the past 42 years. Here we show that the early onset of summer is responsible for this climatic trend. In late May, an anti-cyclonic circulation anomaly strengthens over the United Kingdom, Ireland, and the adjoining Atlantic Ocean, causing significant temperature increases across Western Europe, Iceland, and around the Barents Sea. The intensification of the mid-latitude westerly wind impinging on Greenland seems to be responsible for strengthening the anomalous circulation change via topographically forced stationary Rossby wave responses. As the westerly wind intensification is ensued by further global heating, summer will begin earlier, and thus more frequent European heatwaves are expected to occur.

Adaptive optics in the Arctic? A commentary on Fosbury and Jeffery.

Adaptive optics in the Arctic? A commentary on Fosbury and Jeffery.

Forgotten forbs: Standard vegetation surveys underrepresent ecologically and culturally important forbs in a threatened grassland ecosystem

AbstractForbs are a culturally and ecologically important yet poorly studied component of the Pacific Northwest Bunchgrass (PNB) ecosystem of western North America. Because many PNB forbs emerge early in the spring and senesce at the onset of summer, typical vegetation surveys, which occur mid‐summer, likely underrepresent forbs. We evaluated how the timing of vegetation sampling affected estimates of perennial forb abundance, richness, and floral density, with a focus on species that are culturally significant to Indigenous people of the region. We sampled 29 plots three times: mid‐summer (July), as well as 7 (May) and 12 (April) weeks prior. Timing had large effects on estimates, with significant declines in forb richness (42%), cover (80%), and floral density (95%) between April and July. The density of Camassia quamash and Lomatium cous, two culturally important species, declined 91% and 96%, respectively, from April to July. Nearly 65% of forbs had documented uses by Plateau Tribes. The consequences of biased estimates are significant and (1) limit our understanding of fundamental ecological processes and interactions; (2) hinder effective conservation and management because we lack information on forb abundance, status, and trends, and (3) result in disproportionately negative impacts to Indigenous communities as many forbs are important for subsistence and ceremonial purposes. Vegetation sampling during the spring months coincident with peak forb abundance, in addition to summer sampling would provide more appropriate data with which to evaluate and characterize PNB vegetation dynamics and improve our understanding, management, and conservation of native forbs.

Clinical analysis of 99 children with Henoch-Schönlein purpura complicated with overt gastrointestinal bleeding.

To analyze and summarize the clinical features, diagnosis, and treatment of children with Henoch-Schönlein purpura (HSP) complicated by overt gastrointestinal bleeding (GI bleeding) for achieving early identification, prevention, and treatment in terms of severe GI bleeding. A retrospective analysis was conducted on children with HSP complicated by overt GI bleeding who were admitted to the Department of Traditional Chinese Medicine of Beijing Children's Hospital from January 2017 to December 2019. According to the severity of GI bleeding, the patients were divided into mild bleeding group (61 cases) and moderate and severe bleeding group (38 cases). Inflammatory parameters, coagulation function, GI ultrasound findings, and clinical features were compared. Logistic regression analysis was used to determine the related variables affecting the severity of GI bleeding, and the ROC curve was used to determine the variable test efficacy. Onset in summer, wide distribution of skin rash with facial involvement, the elevation of D-dimer and high neutrophil-to-lymphocyte ratio (NLR) had significant effects on the severity of GI bleeding. ROC curve analysis showed that the optimal cut-off points of NLR and D-dimer for predicting severe GI bleeding in children with HSP were 10.56 and 0.89mg/L, respectively. Facial rash may be a warning sign of GI bleeding. Enhanced monitoring of NLR and D-dimer is helpful for early recognition of GI bleeding as well as assessment of severity.

Parental environment modulates offspring thermal tolerance in a foundational intertidal seaweed

Thermotolerance acquisition is an important ecophysiological trait under global warming scenarios because it can allow organisms and populations to adapt, particularly during the most sensitive early stages of a life cycle. Here we used seasonality as a natural scenario to explore whether parental thermal histories can modulate thermotolerance of recruits of a canopy-forming intertidal seaweed (Fucus guiryi) across an ecologically relevant thermal gradient (15–28°C). For this purpose, we harvested embryos from parents after the periods of maximum and minimum accumulated heat exposure (late summer and late winter), and at the onset of summer. During early ontogeny we followed initial embryo size, internal nutrient content, survival, growth and developmental stages as performance metrics to address whether parental acclimation modulates thermal tolerance via provisioning or parental effects. Late winter recruits of F. guiryi exhibited the greatest thermotolerance, showing a broader range of optimal temperatures and higher upper thermal limits for growth and survival, probably associated with better provisioning from parental thalli. Physiological fitness of recruits decreased above 25°C, showing arrested growth, impaired development and dropping survival rates, but functional loss was more abrupt in early summer. Late summer responses confirmed that heat hardening occurs in natural populations, but at the seasonal scale the adaptive significance of this increased thermotolerance is much lower than that induced by winter parental provisioning. Heat-induced thermotolerance occurred from early to late summer due to parental exposure to warming. However, winter provisioning promoted greater thermotolerance acquisition. Exposure to moderate thermal stress at the onset of summer without prior seasonal acclimation resulted in minimum levels of thermal tolerance and loss of offspring fitness. While warmer winters might be neutral or benefit early development, increasing temperatures and poor nutritional conditions at the onset of the summer season may reduce survival and hamper population recruitment.

Continuing the Role of the Citizen Scientist

New introductions to invasive mosquitoes, Aedes aegypti and Aedes albopictus, increase the risk for vector-borne diseases such as dengue, chikungunya, and Zika in the United States. Tracking these new introductions is more important than ever. This lesson plan focuses on the collection of mosquito larvae and pupae before the onset of summer with a focus on insect development. Students will observe the immature mosquitoes grow and metamorphose into adults. Novel aspects include collecting larvae and pupae around the home/school, observing the mosquito life cycle by safely rearing them from immature stages (larvae and pupae) to adults, and learning important background information on mosquito biology and pathogens that mosquitoes can transmit. The lesson describes new tools to use with the Invasive Mosquito Project, an international citizen science–based mosquito surveillance program exploring mosquitoes and the pathogens they may transmit to interested community members (including students and teachers) and their companion animals. This project is a stand-alone or follow-up lesson plan to the mosquito egg collection lesson used prior to the onset of winter (see Cohnstaedt et al., 2016). Students are able to participate in a hands-on tutorial to build a sealed emergence chamber to safely raise mosquitoes. Long-term data sets can also be used by teachers and students for further classroom discussions on the risks of mosquito-borne illnesses nationwide. This lesson further focuses on how individuals must play an active role in protecting their communities and pets from illness and increasing awareness of the dangerous pathogens mosquitoes can transmit and the importance of mosquito management. Materials from this lesson plan (available at http://www.citizenscience.us) can be adapted for each classroom but are best-suited for middle school to high school classes, as well as Advanced Placement classes.

Weekly and seasonal variation in the circadian melatonin rhythm in humans: Entrained to local clock time, social time, light exposure or sun time?

A recent elegant study published in this journal (Zerbini, Winnebeck & Merrow, J Pineal Res, e12723, 2021) reported data on weekly and seasonal changes in circadian timing, as assessed by the melatonin rhythm in dim light in a population that was exposed to a change from standard time to day light saving time. The authors highlight a one hour earlier timing of melatonin onset in summer compared with winter and a 20minutes delay on work-free days compared with work days. The variations in the timing of the melatonin rhythm are reported in standard time and the authors imply that the data are consistent with synchronization to midday and that "we know that humans entrain to sun time." Here, we show that their extensive data are most parsimoniously explained by entrainment to local clock time and associated light exposure rather than "sun time," indexed by either dawn or midday.

Seventy‐year disruption of seasons characteristics in the Arabian Peninsula

AbstractClimate change has significantly influenced the characteristics of seasons and negatively affected ecosystems and socio‐economic life. This study presents a new, objective definition for seasons in the Arabian Peninsula. Specifically, the study determines disruptions in the onset, cessation, and duration of winter, spring, summer, and autumn based on mean intra‐annual changes of 12 climatological parameters from 1950 to 2019. Data for climatological parameters were obtained from the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis. These data were analysed using two multivariate statistical methods: principal component analysis and cluster analysis. The results show that the characteristics of the four seasons differ from conventionally defined seasons. The differing characteristics of the four seasons are (a) that winter extends for 91 days, between 2 November (the previous year) and 31 January; (b) spring extends for 111 days, until 22 May; (c) summer extends for 106 days, until 5 September and, finally; (d) autumn completes the cycle, extending for 57 days. To investigate the decadal disruption of seasons' characteristics, the analysis was performed on the data collected during five overlapping 30‐year periods: 1950–1979, 1960–1989, 1970–1999, 1980–2009, and 1990–2019. The most remarkable changes were noticed during the last 30 years. Compared to the 70‐year analysis, the 1990–2019 analysis showed extra prolongation in the duration of summer and a shortage in winter, which aligns with the recent warming and drying of the Arabian Peninsula. Summer (winter) lasts for 126 (76) days. All analyses propose that all seasons start earlier, compared with the astronomical definition. The findings of this study are key to understanding the consequences of seasons changes in the Arabian Peninsula. These consequences include impacts on agriculture, water deficits, ecosystems, and land cover.

Age-related variation in reproductive potential and influence on recruitment of western sand lance Ammodytes japonicus in the Seto Inland Sea, western Japan

Assessment of total egg production as a proxy for reproductive potential is critical for understanding the mechanisms of recruitment variability and implementing appropriate stock management. This study determined whether the temporal variation in the estimated egg production index (EPI) of spawning western sand lance (Ammodytes japonicus) collected in the Bisan Strait in the central Seto Inland Sea in Japan explains its recruitment variability from 2009 to 2019. Although the maturation rates of individuals aged 1 year varied among sampling years, they were positively correlated with mean standard length at aestivation onset in summer. The negative relationship between the mean standard length and density of aestivating young-of-the-year fish at aestivation onset suggests that growth was dependent on density during the spring foraging period. All specimens aged 2 and 3 years were mature, and relative fecundity was significantly higher than that in specimens aged 1 year. The EPI of spawning individuals was markedly reduced in recent years and was associated with the decreased density of fish aged 2 and 3 years. In addition, the number of recruit fish was significantly associated with the EPI of spawning fish. However, the density of spawning fish in winter did not adequately explain the variation in recruitment. Thus, our findings suggest that sand lance aged 1 year have reduced reproductive potential, and that the causes of the recent decline in sand lance stocks might be partly attributable to a decline in the abundance of older fish.

A combined structural and seasonal approach to assess wildfire susceptibility and hazard in summertime

Wildfire susceptibility and hazard models based on drivers that change only on a multiyear timescale are considered of a structural nature. They ignore specific short-term conditions in any year and period within the year, especially summer, when most wildfire damage occurs in southern Europe. We investigate whether the predictive capacity of structural wildfire susceptibility and hazard models can be improved by integrating a seasonal dimension, expressed by three variables with yearly to seasonal timescales: (1) a meteorological index rating fuel flammability at the onset of summer; (2) the scarcity of fuel associated with the burned areas of the previous year, and (3) the excessive abundance of fuel in especially fire-prone areas that have not been burned in the previous ten years. We describe a new methodology for combining the structural maps with the seasonal variables, producing year-specific seasonal susceptibility and hazard maps. We then compare the structural and seasonal maps as to their capacity to predict burnt areas during the summer period in a set of eight independent years. The seasonal maps revealed a higher predictive capacity in 75% of the validation period, both for susceptibility and hazard, when only the highest class was considered. This percentage was reduced to 50% when the two highest classes were considered together. In some years, structural factors and other unconsidered variables probably exert a strong influence over the spatial pattern of wildfire incidence. These findings can complement existing structural data and improve the mapping tools used to define wildfire prevention and mitigation actions.

Analysis of the effects of thermal stress on milk production in a humid tropical climate using linear and non-linear models.

The decline of milk production in crossbred cattle during the onset of summer was evaluated using lactation records of the cows (n = 48) maintained at the Livestock Research Station, Thiruvazhamkunnu, for the period between January 2019 and March 2019. Climate data were obtained from an automatic weather station maintained on the campus. The temperature-humidity index (THI) was used to assess the thermal stress on animals. Values varied between 70.78 and 83.93 during the study period, indicating that the cows were exposed to mild and moderate stress. Highly significant negative correlations (p < 0.01) were observed between the average temperature, THI, and milk production. Linear, logarithmic, power, and polynomial models linking milk production and THI were used to fit the data. The coefficient of determination (R2) in general exceeded 0.85 and these equations could be used to model the drop in milk production or predict production loss due to thermal stress. The rate of decline in daily milk production observed in the study was 2.13% per unit increase in THI. A general linear model that included THI, parity, and the stage of lactation as independent variables, and milk production as a response variable, was also tested. Parity and stages of lactation were observed to influence forenoon and afternoon milk production significantly (p < 0.01). The temperature-humidity index also had a significant effect on forenoon milk production (p < 0.05) and afternoon milk production (p < 0.01).