Natural Ambient Conditions Research Articles

Physiological and behavioral responses of an arboreal mammal to smoke and charcoal-ash substrate

The recent observation that torpor plays a key role in post-fire survival has been mainly attributed to the reduced food resources after fires. However, some of these adjustments can be facilitated or amplified by environmental changes associated with fires, such as the presence of a charcoal-ash substrate. In a previous experiment on a small terrestrial mammal the presence of charcoal and ash linked to food restriction intensified torpor use. However, whether fire cues also act as a trigger of torpor use when food is available and whether they affect other species including arboreal mammals remains elusive. To evaluate whether smoke, charcoal and ash can act as proximate triggers for an impending period of food shortage requiring torpor for mammals, we conducted an experiment on captive sugar gliders (Petaurus breviceps), a small, arboreal marsupial, housed in outside aviaries under different food regimes and natural ambient conditions. When food was available, fire simulation via exposure to smoke and charcoal-ash substrate caused a significant earlier start of activity and a significant decrease in resting body temperature. In contrast, only when food was withheld, did smoke and charcoal-ash exposure significantly enhance torpor depth and duration. Thus, our study not only provides evidence that fire simulation does affect arboreal and terrestrial species similarly, but also suggests that smoke and ash were presumably selected as cues for torpor induction because they indicate an impending lack of food.

Thermal physiology of a reproductive female marsupial, Antechinus flavipes

Reproduction is an energetically costly, but necessary, process for animals. Small mammals in particular are at a disadvantage as they experience high heat losses to their environment, substantially increasing their energetic costs. However, many small mammals save energy by using torpor, a reduction in metabolic rate and body temperature (Tb). Antechinus flavipes is a small dasyurid marsupial endemic to Australia that uses torpor during adverse conditions. Females usually produce only one litter in their life. In our study, we aimed to quantify the thermal physiology of reproductive female A. flavipes held under natural ambient conditions in an outdoor aviary, and also under stable conditions indoors, during gestation, parturition and lactation. Throughout gestation, A. flavipes displayed similar variations in torpor use and Tb to reproductively unsuccessful females (did not produce young). Torpor use increased with decreasing ambient temperature in the outdoor aviary and ceased when held under stable ambient conditions indoors. Interestingly, during parturition/early lactation, Tb was tightly controlled and daily Tb variation decreased by ≥2.3 °C in comparison to all other reproductive states. Additionally, daily Tb variations during lactation were slightly smaller than those of gestating and reproductively unsuccessful females; however, this conclusion is only preliminary. Our results reveal that the flexibility of the thermal physiology of female A. flavipes is important throughout the reproductive period, except during parturition/early lactation when a stable Tb is likely beneficial to the early stages of development.

Stomatal patchiness of field-grown sultana leaves: Diurnal changes and light effects

Unirrigated, field-grown Sultana vines were used to study diurnal changes of stomatal patchiness under the natural ambient conditions of South Australia. Non-homogenous aperture of stomata (patchiness) was determined by an infiltration technique and by counting infiltrated patches. Stomatal conductance was linearly related to the number of patches with open stomata (r 2 = 0.622). Both parameters increased in the early morning (maxima at 8 a.m.) and decreased thereafter. In the afternoon stomatal conductance and the number of patches with open stomata remained at a low level. When dark adapted leaves were exposed to sun light (900 -1000 mu mol quanta . m -2 . s -1 ) the number of patches with open stomata increased from 23 to 143 cm -2 within 15 min, indicating that besides several stress factors light induces non-homogenous stomatal opening. It is assumed that stomatal action of single patches is autonomous, i.e. stomata of single patches will regulate water loss and CO 2 uptake according to local changes of ambient and endogenous conditions.

The impact of solution chemistry of electrolyte on the sorption of pentachlorophenol and phenanthrene by natural hematite nanoparticles

Hematite nanoparticles (NPs) were studied as a sorbent for hydrophobic organic contaminants (OCs) under natural ambient conditions through specially designed contrasting solution chemistry of electrolyte. Ionizable pentachlorophenol (PCP) and non-ionizable phenanthrene (PHE) were selected as representative OCs. The sorption capacities of PCP and PHE were pH-dependent, and a larger amount of PCP was sorbed at pH values below its pKa (4.75). However, the PHE sorption capacity was higher at relatively high or low pHs (e.g. below 4.0 and above 10.0), possibly due to the larger available surface area of the hematite NPs, caused by the higher values of net charges and charge density. Changes in pH might thus affect the sorption of OCs by hematite NPs, through modification of the surface characteristics of the sorbent and the electronic properties of the sorbate molecules. The influence of different ionic strengths indicated that the amounts of PCP and PHE sorbed by hematite NPs decreased as a concentration function of different types of ions (e.g. Na+, K+, Mg2+ and Ca2+), with the underlying mechanism possibly being due to four interactions i.e. hydrogen-bonding, competitive sorption by ions in the ambient solution, screening effects and aggregation effects. The results confirmed that the surface chemistry of hematite NPs, the chemical properties of PCP and PHE, and solution chemistry (e.g. pH and ionic strength) of the electrolyte all played an important role in PCP and PHE sorption by hematite NPs. By comparison of both sorption capacity and ecologic advantages, our results suggested that natural hematite NPs would be more competitive and efficient for PCP and PHE sorption than engineered NPs. This finding increases our knowledge regarding the environmental function of natural NPs (such as hematite NPs) for OC remediation through manipulating their interfacial behavior.

Thermal tolerance, net CO2 exchange and growth of a tropical tree species, Ficus insipida, cultivated at elevated daytime and nighttime temperatures

Global warming and associated increases in the frequency and amplitude of extreme weather events, such as heat waves, may adversely affect tropical rainforest plants via significantly increased tissue temperatures. In this study, the response to two temperature regimes was assessed in seedlings of the neotropical pioneer tree species, Ficus insipida. Plants were cultivated in growth chambers at strongly elevated daytime temperature (39°C), combined with either close to natural (22°C) or elevated (32°C) nighttime temperatures. Under both growth regimes, the critical temperature for irreversible leaf damage, determined by changes in chlorophyll a fluorescence, was approximately 51°C. This is comparable to values found in F. insipida growing under natural ambient conditions and indicates a limited potential for heat tolerance acclimation of this tropical forest tree species. Yet, under high nighttime temperature, growth was strongly enhanced, accompanied by increased rates of net photosynthetic CO2 uptake and diminished temperature dependence of leaf-level dark respiration, consistent with thermal acclimation of these key physiological parameters.

The American National Standards Institute/Acoustical Society of America new (draft as 5 May 2012) standard method to define and measure the background sound in quiet areas

This draft standard is a joint work effort of S3/SC1, the animal bioacoustics committee, and S12, the noise committee. The draft standard includes 3 major, distinct components: (1) a method to measure the background using unattended instruments, and based on L-levels with L-90 as the default; (2) a definition for ANS-weighted sound pressure level, which is simply the A-weighted sound level after deleting all of the sound energy in the 2-kHz octave band or above; and (3), requirements for monitoring the sound in parks and wilderness area. The background measurement procedure is mainly for low-noise residential areas and relevant to the siting of such installations as wind farms and power plants. The ANS-weighting is applicable to both measurement of background and monitoring in parks. The requirements for monitoring in parks and wilderness areas ensure that measurements adequately capture the range of natural ambient conditions. The draft standard provides for two grades of measurement/monitoring: engineering or survey. In addition, this is the first standard to clearly and unambiguously define and establish the requirements for the measurement of percentile levels (exceedance values).

Morphology and Developmental Rate of the Blow Fly,Hemipyrellia ligurriens(Diptera: Calliphoridae): Forensic Entomology Applications

Hemipyrellia ligurriens (Diptera: Calliphoridae) is a forensically important blow fly species presented in many countries. In this study, we determined the morphology of all stages and the developmental rate of H. ligurriens reared under natural ambient conditions in Phitsanulok province, northern Thailand. Morphological features of all stages based on observing under a light microscope were described and demonstrated in order to use for identification purpose. Moreover, development time in each stage was given. The developmental time of H. ligurriens to complete metamorphosis; from egg, larva, pupa to adult, took 270.71 h for 1 cycle of development. The results from this study may be useful not only for application in forensic investigation, but also for study in its biology in the future.

Contribution of the horizontal transmission of the entomopathogenic fungus Beauveria bassiana to the overall performance of a fungal powder formulation against Triatoma infestans.

Control of domiciliated Triatoma infestans, the major Chagas disease vector in southern South America, is currently achieved by indoor residual spraying of infested houses with chemical insecticides. However, in recent years this strategy has been threatened by the emergence of pyrethroid-resistant bug populations. As an alternative approach, we have previously demonstrated the efficacy of the entomopathogenic fungus Beauveria bassiana to control T. infestans bugs regardless of their pyrethroid susceptibility. In this work, we tested the virulence and residual activity of a powdered fungal formulation, and studied the significance of the horizontal transmission process (autodissemination) to fungal infection of bugs. The B. bassiana-based formulation was highly virulent against all T. infestans stages, and maintained its insecticidal capability for at least 5 months under natural ambient conditions. We showed that horizontal transmission of conidia is associated to bug density, and contributes significantly to the overall population infection event.

The effects of handling time, ambient light, and anaesthetic method, on the standardized measurement of fish colouration

The effects of handling time, ambient light intensity, and anaesthetic method, on the collection of spectral reflectance data were assessed in two species of Malawi cichlids ( Melanochromis auratus and Metriaclima zebra ). Using spectrometry, colour patches were measured over 10 min, under increasing ambient light levels, and using three anaesthetic methods. As time elapsed, maximum percent reflectance (Rmax) decreased across all anaesthetic methods and species, suggesting that measurements should be taken immediately after capture and anaesthetization. With increasing light intensity, Rmaxincreased significantly, suggesting that measurements should be taken under natural ambient conditions when possible. Finally, we found that anaesthetizing fish using an ice bath produced significantly higher Rmaxthan using either MS-222 (tricaine methanesulphonate) or clove oil (eugenol). However, the highest proportion of ultraviolet (UV) colouration was recorded while fish were anaesthetized with clove oil. Our results highlight the variation involved in measuring fish colour patterns using two related species, and thus indicate the need for a standardized approach to collecting spectral reflectance data in fish.

Effect of betaine and air ammonia concentration on broiler performance, plasma corticosterone level, lymphoid organ weights and some haematological indices

This study was initiated to examine the effect of betaine supplementation (1g/kg) on hematocrit level, erythrocyte and leukocyte number, heterophil/lymphocyte ratio, plasma corticosterone, rectal temperature, relative lymphoid organ weights and average daily gain in broiler chickens reared in a poultry house under natural ambient conditions and high air ammonia level. A total of 100 broiler chickens at the age of 45 d were allocated into 2 groups: control and betaine supplemented. The broilers were kept on deep litter in windowless poultry house. The results of this study indicated no significant changes in terms of hematocrit, erythrocyte number, leukocyte number, lymphoid organ weights and average daily gain.Betaine supplemented broilers had lower heterophil/lymphocytes ratio at d8 (P<0.05) relative to control broilers inspite of the similar values of plasma corticosterone between the groups. Plasma corticosterone concentration in betaine supplemented broilers increased (P<0.05) at d 15, relative to d8. The observed increase in plasma corticosterone was not accompanied by increase in heterophil to lymphocyte ratio. These results are interpreted to suggest that the decreased heterophil/lymphocyte ratio in experimental broilers was due to the modulatory effects of ammonia on NO synthesis rather than to the modulatory effect of corticosterone.

Sobrevivência de fungos associados ao potencial fisiológico de sementes de triticale (X. triticosecale Wittmack) durante o armazenamento

Sementes de triticale de um lote do cultivar IAC-2, com 85% de germinação e incidência natural de Pyricularia grisae (34.5%), Bipolaris sorokiniana (12%), Fusarium graminearum (15%) e Alternaria alternata (35%), foram armazenadas em câmara fria, a 10 ºC, e em local sem controle das condições do ambiente, por doze meses. O potencial fisiológico foi avaliado em intervalos bimestrais, utilizando-se os testes de germinação, de envelhecimento acelerado, de tetrazólio e de emergência de plântulas no campo; a sobrevivência dos fungos foi avaliada por meio do teste de papel de filtro. As sementes mantiveram o nível de viabilidade e de vigor e a incidência de fungos patogênicos foi pouco alterada no armazenamento a 10 ºC. Em condições de ambiente não controlado, a germinação e a viabilidade das sementes armazenadas decresceram, aumentando a quantidade de sementes mortas devido à maior velocidade de deterioração e a um nível crescente de fungos de armazenamento, principalmente de Penicillium spp. Nestas condições, a incidência dos fungos patogênicos decresceu continuamente até o final do período de armazenamento, atingindo valores muito baixos; porém na época recomendada para a semeadura da cultura no Estado de São Paulo (mês de abril), a sobrevivência destes patógenos ainda comprometia a qualidade sanitária das sementes.

Características físico-químicas e nutricionais de pimentão produzido em campo e hidroponia

The objective of this work was to evaluate the physicochemical characteristics and proximate composition of bell pepper cultivars stored in natural ambient conditions (temperature of 21 ± 2 °C and relative humidity of 70 ± 5%). The experiment was carried out using a completely randomized design, with four types of bell peppers (Paloma and Impacto produced through a hydroponic production system; Paloma and Magali produced in the field) and six analysis periods, with three repetitions. The cultivars Paloma produced in the field and hydroponic Impacto presented the greatest mass. The highest moisture and lowest crude fiber contents were obtained for Paloma cultivar, and the highest protein and carbohydrate contents, for Magali cultivar. Soluble solids were higher in Magali produced in the field. Moisture was not influenced by the treatments (field or hydroponic) and storage. During the 12 days of storage, all treatments presented high values of vitamin C, being higher in hydroponic Impacto and lower in Magali from the field. Mass loss reached 14.11% at 12 days of storage, which was considered the limiting period for bell pepper storage. Paloma and Impacto cultivars can be recommended for cultivation.

Persistence of Dengue Virus RNA in Dried <I>Aedes aegypti</I> (Diptera: Culicidae) Exposed to Natural Tropical Conditions

Aedes aegypti (L.) is the primary vector of dengue viruses, a group of four serotypic single-stranded RNA viruses. Dengue virus RNA can be readily detected in fresh or dried infected mosquitoes by using reverse transcriptase-polymerase chain reaction (RT-PCR). The current study examined the persistence and limit of dengue virus RNA detection in infected Ae. aegypti killed and exposed to natural ambient tropical conditions of temperature and humidity. Under relatively harsh conditions, dengue RNA retained sufficient integrity to be detected in dried mosquitoes up to 13 wk after exposure to relatively high ambient temperatures (26.3-31.7 degrees C) and relative humidity (49.4-69.9%). These findings confirm that the necessity for testing either fresh or frozen mosquitoes is not a prerequisite when using RT-PCR as the viral detection method, and under particular epidemiological circumstances it allows for a more convenient means of conducting vector-virus surveillance activities where collection methods and logistics may preclude immediate testing or access to a cold chain.

Response of naked neck (Nana) and normal (nana) broiler chickens to dietary energy levels in a subtropical climate

1. The comparative response of naked neck (Nana) broiler chickens and their normally feathered (nana) full sibs to varied dietary energy levels was assessed under natural ambient conditions in a subtropical climate in two separate trials, one in winter (19·0 to 26·0°C) and the other in summer (28·1 to 37·4°C). 2. The chickens were fed on diets with 10·9, 11·5 or 12·1 MJ ME/kg and with a constant protein content of 200 g/kg from 1 to 42 d of age. 3. Both genotypes showed similar body weight, food intake and food conversion efficiency at 42 d of age. Body weight and food conversion efficiency improved on the diet with the highest energy content. 4. Apparent retention (AR) of crude protein (CP) was higher in nana chickens than in their Nana sibs in the winter trial, while no differences were observed for AR of dry matter (DM), crude fibre (CF), ether extract (EE) or calcium. In the summer trial, no difference in nutrient retention was seen between the genotypes. Increasing dietary energy had a positive influence on AR of DM, CP and EE. 5. The relative weights of feathers and skin were lower in Nana chickens than in their normal counterparts. Ready-to-cook yields were greater at the high dietary energy content, while abdominal fat increased with increasing energy content. Nana chickens had more skin protein and less fat in breast muscle and skin than their normal sibs in the summer trial. 6. It was concluded that the Nana broiler chickens showed similar performance and did not differ in dietary energy requirements in comparison to their nana sibs under natural ambient conditions in a subtropical climate.

Exchange of carbonyl sulfide (COS) between wheat soil and atmosphere

The exchange of COS between wheat soil and atmosphere was investigated by using a dynamic enclosure. The investigated soil type acted as a significant sink for the trace gas COS. Atmospheric COS mixing ratios and temperature were found to be the physicochemical parameters controlling the uptake. The uptake reached maximum about 0.6×10−12 mol · g−1 · h−1 at 15–20°C under natural ambient atmospheric conditions. The measured uptake values agree well with that calculated by Guenther algorithm.

Exchange of carbonyl sulfide (COS) between wheat soil and atmosphere

The exchange of COS between wheat soil and atmosphere was investigated by using a dynamic enclosure. The investigated soil type acted as a significant sink for the trace gas COS. Atmospheric COS mixing ratios and temperature were found to be the physicochemical parameters controlling the uptake. The uptake reached maximum about 0.6×10 -12 mol·g -1 ·h -1 at 15—20℃ under natural ambient atmospheric conditions. The measured uptake values agree well with that calculated by Guenther algorithm.

Modeling Concrete Shrinkage under Variable Ambient Conditions

Drying shrinkage in concrete structures is an important part of the delayed strains. In this paper, drying shrinkage is analyzed and modeled under natural ambient conditions. An experiment on a 30-cm-thick concrete beam, monitored over a period of several years, shows that fluctuations in shrinkage correspond to the average relative humidity of the previous 90 days. Since this property depends on the type of concrete used and the geometry of the beam, we modeled drying and shrinkage of the beam to obtain a model that could be adapted to all types of concrete and geometry. Drying is modeled using a nonlinear diffusion equation, and the shrinkage is simply assumed to be proportional to the weight loss. An initial approach based on these hypotheses, however, does not correspond to the experimental results obtained when there is an increase in the average humidity. If it is assumed, on the other hand, that the diffusivity is lower in the wetting phase, a good approximation to the experimental results can be assumed.

Modélisation du retrait du béton en ambiance variable

Drying shrinkage in concrete structures is an important part of the delayed strains. In this paper, this shrinkage is analyzed and modeled under natural ambient conditions. An experiment on a 30 cm...

Brain cooling and respiratory heat exchange in camels during rest and exercise

Respiration in relation to brain temperature (T b) and body temperature (T c) were investigated in two camels at rest and one during exercise (running at 10 km/h). The animals were subjected to natural ambient conditions (day: 25–30 °C, relative humidity (RH) about 65%; night: 15–20 °C, RH approx. 90%). They were studied when fully hydrated and during progressive dehydration by up to 15% of initial weight. At low T c (< 38 °C)T b > T c by approximately 0.2 °C, at higher T c significant brain cooling was observed by as much as 1.5 °C during exercise. Minute ventilation (V̇ e) and respiratory rate (f) increased with T c such that tidal volume was constant and similar at rest and during exercise (T c−T b) increased linearly with f and hence V̇ e. The cooling, dependent on turbinate heat exchange was related to certain features of the air flow pattern and f which have also been described in other large mammals.

Sleep changes in emperor penguins during fasting.

The proportion and the distribution over 24 h of the different arousal stages characterized in emperor penguins [wakefulness (W), drowsiness (D), slow-wave sleep (SWS), and paradoxical sleep (PS)] were studied under natural ambient conditions in four subjects that were first fed and then deprived of food for 7-18 days. In both fed and fasting states, each arousal stage was distributed through numerous episodes of short duration. The fasting state provoked only a slight increase in D. There was, however, a large increase in SWS, which increased from 37.5 to 55.4%/day, mainly at the expense of W, which fell from 42.7 to 21.9%/day, in close relation to the first two fasting phases when proteins were saved and when most of the energy was derived from lipids. PS proportions were lower during fasting (from 5.7 to 2.4%/day). These changes in the arousal stages in emperor penguins are examined for their implications in sleep mechanisms and energy saving. Their possible consequences, due to the reduced alertness, are also discussed.