Abrupt Temperature Changes Research Articles

Effects of climate change on different geographical populations of the cotton bollworm Helicoverpa armigera (Lepidoptera, Noctuidae).

The effects of climate change on pest phenology and population size are highly variable. Understanding the impacts of localized climate change on pest distribution and phenology is helpful for improving integrated pest management strategies. Here, the population dynamics of cotton bollworms (Helicoverpa armigera) from Maigaiti County, south Xinjiang, and Shawan County, north Xinjiang, China, were analyzed using a 29‐year dataset at lower latitudes and a 23‐year dataset at higher latitudes to determine the effects of climate change on the population dynamics of H. armigera. The results showed that all generations of H. armigera at both sites showed increasing trends in population size with climate warming. Abrupt changes in phenology and population number occurred after abrupt temperature changes. Climate change had a greater effect on the phenology of H. armigera at higher latitudes than at lower latitudes and led to a greater increase in population size at lower latitudes than at higher latitudes; the temperature increase at higher latitudes will cause a greater increase in the adult moth population size in the future compared to that at lower latitudes; and abrupt changes in the phenology, temperature increase, and population size at lower latitudes occurred earlier than those at higher latitudes. Thus, it is necessary to develop sustainable management strategies for Helicoverpa armigera at an early stage.

The Evolution of a Northward‐Propagating Buoyant Coastal Plume After a Wind Relaxation Event

AbstractAfter a relaxation of the regional southward, upwelling‐favorable winds along the central California coast, warm water from the Santa Barbara Channel propagates northward as a buoyant plume. As the plume transits up the coast, it causes abrupt temperature changes and modifies shelf stratification. We use temperature and velocity data from 35 moorings north of Pt. Arguello to track the evolution of a buoyant plume after a wind relaxation event in October 2017. The moorings were deployed September–October 2017 and span a ∼30 km stretch of coastline, including nine cross‐shelf transects that range from 17 to 100 m water depth. The high spatial resolution of the data set enables us to track the spatiotemporal evolution of the plume, including across‐front temperature difference, cross‐shore structure, and propagation velocity. We observe an alongshore current velocity signal that takes ∼10 hr to propagate ∼25 km alongshore (∼0.7 m/s) and a temperature signal that takes ∼34 hr to propagate the same distance (∼0.2 m/s). The plume cools as it transits northward, leading to a decrease in the cross‐front temperature difference and the reduced gravity (g’). The plume’s propagation velocity is nonuniform in space and time, with accelerations and decelerations unexplained by the alongshore reduction in g’ or advection by tidal currents. As the plume reaches the northernmost part of the mooring array, its temperature variability is obscured by internal waves, a prominent feature in the region. We focus on one relaxation event but observe five other similar events over the 2 months record.

The Hydrological Urban Heat Island: Determinants of Acute and Chronic Heat Stress in Urban Streams

AbstractDuring and after rainfall events, the interaction of precipitation with hot urban pavements leads to hot runoff, and its merger with urban streams can result in an abrupt change in water temperature that can harm aquatic ecosystems. To understand this phenomenon and its relation to land cover and hydrometeorological parameters, we analyzed data spanning two years from 100 sites in the eastern United States. To identify surges, we first isolated temperature jumps of at least 0.5°C over 15 min occurring simultaneously with water flow increase. Surge magnitude was defined as the difference between peak stream temperature and baseflow temperature right before the jump. At least 10 surges were observed in 53 of the studied streams, with some surges exceeding 10°C. Our results demonstrate that the watershed developed area and vegetation fraction are the best descriptors of surge frequency (Spearman correlation of 0.76 and 0.77, respectively). On the other hand, for surge magnitude and peak temperature, the primary drivers are stream discharge and stream temperature immediately before the surge. In general, the more urbanized streams were found to be already warmer than their more “vegetated” counterparts during baseflow conditions, and were also the most affected by temperature surges. Together, these findings suggest the existence of a hydrological urban heat island, here defined as the increase in stream temperature (chronic and/or acute), caused by increased urbanization.

Targeted Temperature Management Protocol in a Pediatric Intensive Care Unit: A Quality Improvement Project.

In patients with acute neurological injury, abrupt temperature change exacerbates increased intracranial pressures and negatively affects perfusion pressure and cerebral blood flow. Critical care nurses must provide coordinated and effective interventions to maintain normothermia without precipitating shivering immediately after acute neurological injury in pediatric patients. To improve hyperthermia management in a 40-bed pediatric intensive care unit, an interdisciplinary pediatric critical care team developed, implemented, and evaluated a targeted temperature management protocol. The project was guided by the organization's plan-do-study-act quality improvement process. Quality improvement was assessed retrospectively using electronic medical records of patients meeting eligibility criteria. Samples of pediatric patients who received temperature interventions were compared before and after protocol implementation. The protocol included environmental, pharmacological, and body surface cooling device interventions, as well as use of a bedside shivering assessment scale and stepwise interventions to prevent and control shivering. Before implementation of the targeted temperature management protocol, 64% of patients had documented temperatures higher than 37.5 °C, and body surface cooling devices were used in 10% of patients. After protocol implementation, more than 80% of patients had documented temperatures higher than 37.5 °C, and body surface cooling devices were used in 62% of patients. Four patients (6%) before and 5 patients (31%) after protocol implementation were treated with body surface cooling without requiring use of neuromuscular blockade. Creation and implementation of a targeted temperature management protocol increased nurses' documented use of body surface cooling to manage hyperthermia in pediatric intensive care unit patients with acute neurological injury.

Kovacs effect in glass with material memory revealed in non-equilibrium particle interactions

The Kovacs effect is a remarkable feature of the ageing dynamics of glass forming liquids near the glass transition temperature. It consists in a non-monotonous evolution of the volume/enthalpy after a succession of two abrupt temperature changes: first from a high initial temperature T i to a much lower annealing temperature T a followed by a smaller second jump back to a slightly higher final temperature T f. The second change is performed when the instantaneous value of the volume/enthalpy coincides with the equilibrium one at the final temperature. While this protocol might be expected to yield equilibrium dynamics right after the second temperature change, one observes the so-called Kovacs hump in glassy systems. In this paper we apply such thermal protocol to the distinguishable particles lattice model for a wide range of fragility of the system. We study the Kovacs hump based on energy relaxation and all main experimental features are captured. Results are compared to general predictions based on a master equation approach in the linear response limit. We trace the origin of the Kovacs hump to the non-equilibrium nature of the probability distribution of particle interaction energies after the annealing and find that its difference with respect to the final equilibrium distribution is non-vanishing with two isolated zeros. This allows Kovacs’ condition of equilibrium total energy to be met out-of-equilibrium, thus representing the memory content of the system. Furthermore, the hump is taller and occurs at a larger overlap with the system initial configuration for more fragile systems. The dynamics of a structural temperature for the mobile regions strongly depends on the glass fragility while for the immobile ones only a weak dependence is found.

일방향 주기적 진동상태인 원통 내부 유체의 유동 및 열전달에 대한 점근해석

A study is made of time-dependent flow and heat transfer of an incompressible Boussinesq fluid in an oscillating infinite cylinder along the horizontal axis under micro-gravity environment. The flow and heat transfer are initiated by forcing a periodic oscillation on the cylinder containing an incompressible fluid and, simultaneously, imposing an abrupt change of wall temperature. For the asymptotic analysis, Boussinesq approximation is adopted. Assuming the approximation of high Reynolds number (R<SUB>e</SUB> ≫ 1), small magnitude of thermal expansion of the fluid (ϵ ≪ 1) and moderate amplitude of the oscillation (δ), a theoretical asymptotic analysis has been performed on flow and temperature field. The results clarify the reason why heat transfer could be agumented along the axis of oscillation. The predictions are consistent with the previous numerical results.

Unusual magnetization process and magnetocaloric effect in α-CoV2O6 driven by pulsed magnetic fields

In low-dimensional Ising spin systems, an interesting observation is the presence of step magnetization at low temperatures. Here we combine both DC and pulsed magnetic fields to study the 1/3 magnetization plateau and multiple steps in the Ising spin-chain material α-CoV2O6. Magnetization in pulsed fields is quite different from that in DC fields, showing multiple steps in an intermediate range of 4.2–6 K, inverted hysteresis below 4.2 K and asymmetric magnetization in negative fields below 11 K. We demonstrate that these unusual behaviors in magnetization are caused by the spin dynamics and the anomalous magnetocaloric effect (MCE) in α-CoV2O6, i.e., abrupt changes of sample temperature in adiabatic conditions. We successfully separate the influence between the intrinsic slow spin dynamics and the quasi-extrinsic temperature change. From the MCE, we find that some irreversible behavior is originated from the slow spin dynamics. Two different slow dynamics associated with the metastable steps are observed: one is sensitive to the slow field sweep rate at the order of ∼mT s−1 and weakly depends on temperature, while the other responds to the rapid field sweep rate of ∼kT s−1 and dominates at lowest temperature. We also distinguish that the metastable transition at H 4 is the first order and crucial for the ferrimagnetic to ferromagnetic transition. This study is useful to the understanding of multistep magnetization in α-CoV2O6 and sheds light on recent experimental findings of related compounds.

Teratological changes in postembryos of Eratigena atrica obtained by the application of alternating temperatures on spider embryos.

Spider embryonic development depends on several factors, including temperature. Under optimum thermal conditions embryogenesis proceeds undisturbed and embryo mortality is low. On the other hand, dramatic shifts in incubation temperature may cause a range of developmental defects in embryos. It has been confirmed in numerous laboratory experiments that abrupt temperature changes can be a powerful teratogenic factor. Changes in the external structure are frequently reflected in the internal anatomy, and above all, in the central nervous system. In the present teratological study, by exposing spider embryos to the temperatures of 14 °C and 32 °C, changed every 12 hours for the first 10 days of their development, we obtained 74 postembryos of Eratigena atrica with body deformities such as oligomely, heterosymely, schistomely, bicephaly, complex anomalies and others. We selected six spiders to describe and analyze their morphological changes. In one case, that of a spider affected by polymely (the presence of a supernumerary appendage) combined with heterosymely (the fusion of walking legs), we also focused on the structure of the central nervous system. The analysis indicated that this complex anomaly was accompanied by only one change in the central nervous system: the presence of a supernumerary neuropil. Since no fusion of walking leg neuropils was observed, it was concluded that, in this instance, there was no relationship between the fusion of legs and the structure of the central nervous system.

Response relationships between abrupt seasonal temperature changes/warming (cooling) hiatuses in China and their influencing factors.

The mechanisms of abrupt seasonal temperature changes and warming (cooling) hiatuses remain unclear. Clarifying how they respond to various influencing factors is critically important to understanding their mechanisms. In this study, the influencing factors to which the abrupt changes in Tav, Tnav, and Txav were most sensitive followed the order of (AGG and CO2) > SR > WS > AMO > PDO > MEI > AO > AP > RH. Seasonal Tav had the greatest sensitivity to all influencing factors, followed by seasonal Tav and lastly by seasonal Txav. An abrupt temperature change occurred when AGG, AMO, or SR increased continuously to a certain value, when PDO was in a positive phase (warm phase) and increased continuously to a certain value, when MEI changed abruptly, when WS and RH continued to decline for a certain time and reached a certain tendency rate, or when AP continued to decline for a certain time and reached a certain value. During the period before and after the warming (cooling) hiatuses, the temperature at most of the stations only had a significant relationship with a few influencing factors, and the hiatuses in seasonal Tav, Tnav, and Txav were overall most sensitive to changes in WS, followed by changes in RH and lastly by changes in AP. The occurrence of warming (cooling) hiatuses was highly consistent with the variation trend of some influencing factors, which to some extent affected the warming (cooling) hiatuses. Abrupt seasonal temperature changes/warming (cooling) hiatuses are the combined effects of multiple influencing factors.

Thermal Performance of a Convective Functionally Graded Fin Using Fractional Non-Fourier Heat Conduction

To analyze the thermal performance of longitudinal fins made of functionally graded materials, this article studies the transient heat transfer in a longitudinally graded fin with power-law thermal conductivity in a convective ambiance using a fractional heat conduction model. This model has an advantage over the Fourier heat conduction in describing the anomalous heat diffusion and non-Fourier effect, and in avoiding the infinite velocity of heat waves and abrupt change of temperature. For heat shock at the base, instantaneous temperature response in an axially graded fin surrounded by convective fluid is obtained through numerical inversion of the Laplace transform. The effects of non-Fourier parameters such as the fractional order and phase lag of heat flux (relaxation time), and the gradient index of the thermal conductivity on the temperature distribution and fin efficiencies are analyzed and shown graphically. Two definitions of instantaneous fin efficiency are discussed for homogeneous and longitudinally graded fins. The occurrence of heat convection leads to a subdiffusion term, and the temperature change exhibits a significant difference when adopting the fractional-order model and the integer-order model. The obtained results are of great benefit to the design of enhancing the thermal performance of extended surfaces.

Predicting catastrophic temperature changes based on past events via a CNN-LSTM regression mechanism

The modelling and prediction of extreme temperature changes in enclosed compartments is a domain with applications ranging from residential fire alarms, industrial temperature sensors to search and rescue personnel safety systems. The spread of fire in enclosed compartments is a highly uncertain and nonlinear process. Hence, in safety-critical cases, any false negatives pose a serious threat to the safety of individuals such as firefighters that are engaged in rescue activities. This work aims to model the nonlinear fire spread behaviour as a temporal, deep learning-based regressive methodology. The objective is to efficiently identify abrupt and extreme temperature changes that often result in increases of 300+ °C. A major challenge in such time-series models is that of learning from historic time-series samples which are known to suffer from high noise levels, outliers and data imbalance. This work contributes on the development of a convolutional neural network (CNN)-long short-term memory (LSTM) methodology to handle temperature data originating from body-mounted and fixed sensors and develop a temperature increase warning mechanism. The main contribution exploits the contextualisation ability of CNN-LSTM to predict temperature changes in windows of 5–120 s. The model identifies the spatial temperature change patterns via a CNN encoder, which are then fed into an LSTM network. This regression mechanism is trained and validated against a set of unique fire spread conditions and involved live tests ranging from containers to residential and industrial units. The model’s performance was evaluated with MAPE sensitivity analysis against data originating from body-mounted sensors and third-party NIST datasets. The outcome showed an error ranging from 0.89 to 2.05% to 5.46% and 6.23%, respectively. The model efficacy was also evaluated against a range of input–output temperature ranges from 5, 30 to 120-s windows and showed a FN rate of 2.15% for pre-alarm-to-normal and 3.11% for alarm-to-pre-alarm cases in body-mounted sensors and a higher FN rate of 5.14% reported for pre-alarm-to-normal case for the raised platfor sensor tests.

Response relationship between the abrupt temperature change‐climate warming hiatus and changes in influencing factors in China

AbstractThe mechanism of the abrupt temperature change‐climate warming hiatus is not clear, and understanding the response relationships between it and the influencing factors is significant to the study the mechanism. Based on the annual average temperature (Tave), annual average minimum temperature (Tmin), and annual average maximum temperature (Tmax) of 622 meteorological stations in China from 1951 to 2018, the response relationships between the three temperatures and the influencing factors were analyzed. The results showed that In the periods before, during, and after an abrupt temperature change, For the abrupt changes in the three temperatures, the regions significantly influenced by the solar radiation (SR), AMO, multivariate El Niño southern oscillation (ENSO) index (MEI), and Pacific Decadal Oscillation (PDO) accounted for more than 80% of China, and for the abrupt changes in Tmin, the regions with significant influences covered the whole of China. The regions significantly influenced by the AO accounted for more than 60% of China, and the regions significantly influenced by the remaining factors accounted for more than 30% of China. The AO mainly influenced the abrupt temperature change in the northern regions, the AGG and CO2 mainly influenced all the regions except for Northeast China, and the influencing scopes of the atmospheric pressure (AP) were relatively small and not concentrated. In summary, when some conditions continued for a period and a tendency rate or value was reached, abrupt temperature change occurred, and the conditions were as follows: the AGG continued to increase, the PDO was in a positive phase, the AMO and SR continued to rise, the MEI changed abruptly, and the AP in each zone continued to decline/increase and experienced the subsequent trend change. In the periods before, during, and after the climate warming hiatus, few influencing factors had a significant correlation with the temperatures. The MEI and PDO influenced more than 80% of the regions that experienced the climate warming hiatus, and other factors influenced less than 60% of these regions. In the 1990s, especially after 1998, the increase in the AGG slowed, the PDO declined or was in a negative phase, the MEI and SR decreased, and the AP in each zone continued to decline/increase and experienced the subsequent trend change; when those conditions continued for a period and a tendency rate or value was reached, the climate warming hiatus occurred. The abrupt temperature change‐climate warming hiatus was the result of the joint action of multiple influencing factors.

Highly reliable THz hermetic detector based on InGaAs/InP Schottky barrier diode

We demonstrate on n-InGaAs/n+-InP hetero-epitaxial structure based low-barrier Schottky barrier diode with integrated antenna for broadband THz detection. These devices showed refined and uniform nonlinear rectifying characteristics. Based on this device, a compact and robust hermetic packaged module was fabricated. The developed module showed stable and consistent electrical characteristics even in mechanical/vibration shock and abrupt change of temperature. The detection performance of module was characterized by frequency domain spectroscopy system, and as a result, it had a detectable bandwidth of 0.1–0.8 THz, a voltage responsivity of 320 V/W, and noise equivalent power of 3.1∙10−9 W/Hz0.5 at 300 GHz.

Origin of andradite in the Quaternary volcanic Andahua Group, Central Volcanic Zone, Peruvian Andes

Euhedral andradite crystals were found in trachyandesitic (latitic) lavas of the volcanic Andahua Group (AG) in the Central Andes. The AG comprises around 150 volcanic centers, most of wich are monogenetic. The studied andradite is complexly zoned (enriched in Ca and Al in its core and mantle, and in Fe in this compositionally homogenous rim). The core-mantle regions contain inclusions of anhydrite, halite, S- and Cl-bearing silicate glass, quartz, anorthite, wollastonite magnetite and clinopyroxene. The chemical compositions of the garnet and its inclusions suggest their contact metamorphic to pyrometamorphic origin. The observed zoning pattern and changes in the type and abundance of inclusions are indicative of an abrupt change in temperature and subsequent devolatilization of sulfates and halides during the garnet growth. This process is interpreted to have taken place entirely within a captured xenolith of evaporite-bearing wall rock in the host trachyandesitic magma. The devolitilization of sediments, especially sulfur-bearing phases, may have resulted in occasional but voluminous emissions of gases and may be regarded as a potential hazard associated with the AG volcanism.

Temperature Stress Induces Shift From Co-Existence to Competition for Organic Carbon in Microalgae-Bacterial Photobioreactor Community - Enabling Continuous Production of Microalgal Biomass.

To better predict the consequences of environmental change on aquatic microbial ecosystems it is important to understand what enables community resilience. The mechanisms by which a microbial community maintain its overall function, for example, the cycling of carbon, when exposed to a stressor, can be explored by considering three concepts: biotic interactions, functional adaptations, and community structure. Interactions between species are traditionally considered as, e.g., mutualistic, parasitic, or neutral but are here broadly defined as either coexistence or competition, while functions relate to their metabolism (e.g., autotrophy or heterotrophy) and roles in ecosystem functioning (e.g., oxygen production, organic matter degradation). The term structure here align with species richness and diversity, where a more diverse community is though to exhibit a broader functional capacity than a less diverse community. These concepts have here been combined with ecological theories commonly used in resilience studies, i.e., adaptive cycles, panarchy, and cross-scale resilience, that describe how the status and behavior at one trophic level impact that of surrounding levels. This allows us to explore the resilience of a marine microbial community, cultivated in an outdoor photobioreactor, when exposed to a naturally occurring seasonal stress. The culture was monitored for 6weeks during which it was exposed to two different temperature regimes (21 ± 2 and 11 ± 1°C). Samples were taken for metatranscriptomic analysis, in order to assess the regulation of carbon uptake and utilization, and for amplicon (18S and 16S rRNA gene) sequencing, to characterize the community structure of both autotrophs (dominated by the green microalgae Mychonastes) and heterotrophs (associated bacterioplankton). Differential gene expression analyses suggested that community function at warm temperatures was based on concomitant utilization of inorganic and organic carbon assigned to autotrophs and heterotrophs, while at colder temperatures, the uptake of organic carbon was performed primarily by autotrophs. Upon the shift from high to low temperature, community interactions shifted from coexistence to competition for organic carbon. Network analysis indicated that the community structure showed opposite trends for autotrophs and heterotrophs in having either high or low diversity. Despite an abrupt change of temperature, the microbial community as a whole responded in a way that maintained the overall level of diversity and function within and across autotrophic and heterotrophic levels. This is in line with cross-scale resilience theory describing how ecosystems may balance functional overlaps within and functional redundancy between levels in order to be resilient to environmental change (such as temperature).

Responses of periphyton communities to abrupt changes in water temperature and velocity, and the relevance of morphology: A mesocosm approach

Sudden instream releases of water from hydropower plants (hydropeaking [HP]) can cause abrupt temperature variations (thermopeaking [TP]), typically on a daily/sub-daily basis. In alpine rivers, hydropeaking and thermopeaking waves usually overlap, which leads to a multiple stressor of flow velocity pulses and temperature alteration. Periphytic communities could give important insights into the effects of combined thermo- and hydropeaking (THP) in stream ecosystems. Thus, the study's first aim was to assess the combined effects of thermo-hydropeaking on structural (composition, biomass) and functional (photosynthesis, enzyme activity) properties of periphyton. The second aim was to assess the interaction between periphytic algae and the heterotrophic communities (bacteria) and determine how biotic and abiotic factors explain the variability of bacterial enzymatic activities in the periphyton. We assessed the effects of repeated cold and warm thermo-hydropeaking for 24 days on periphyton, by manipulating discharge and temperature in six experimental flumes directly fed by an Alpine stream. Our study revealed that THP had structural and functional effects on periphyton in oligotrophic streams, where the effects depending on the direction of the temperature change (cold/warm) and on the morphological setting (pool/riffle). The results showed that even a short-term increase in flow velocity and temperature decrease could induce better growth conditions for diatoms. Additionally, an increase in the interaction between periphytic algae and bacteria during thermo-hydropeaking was also shown, this coupling being more pronounced in pool than in riffle sections. Our results clearly showed that riffle sections develop less periphytic algal biomass and activity and therefore, THP can reduce biomass availability for primary consumers in large areas of impacted streams. These findings highlight the importance of mitigation measures, focusing on establishing heterogeneous stream bed areas, with frequent pool and riffle sequences.

Comportamento de sistemas de vedação vertical externa frente ao ensaio de ação de calor e choque térmico

Um dos requisitos abordados pela NBR 15575:2013, mais conhecida por Norma de Desempenho (ND), está relacionado com a durabilidade das edificações e estabelece como método de avaliação o ensaio de Ação de Calor e Choque Térmico (ACCT), que verifica o comportamento de Sistemas de Vedação Vertical Externa (SVVE) frente a mudanças bruscas de temperatura. O objetivo do trabalho foi verificar o item durabilidade proposto na norma brasileira e contrastar os resultados de diferentes sistemas construtivos frente ao ensaio de ACCT, bem como comparar as prescrições de ensaio de ACCT em diferentes Normas internacionais. O método envolveu a coleta de dados de ensaios já realizados de acordo com a ABNT (2013b). Assim, constatou-se a existência de diversos métodos sendo empregadas para realização do mesmo ensaio, inclusive com variação da dimensão das amostras. Em relação a outras normativas, verifica-se que a norma brasileira é mais branda, devido ao ensaio ter o menor número de ciclos e com menor duração. Constatou-se, também, a facilidade na aprovação ao requisito de desempenho previsto na norma e, que há lacunas de especificação que dificultam a padronização dos procedimentos de ensaio, tais como: tempo de aspersão e temperatura da água.

Meteorological influences on solar energy production in a coastal Amazon region

A study was conducted with a photovoltaic distributed generation system in São Luís, Brazil, to determine the influence of meteorological variables on the generation of energy. The methodology is composed of three stages: the first corresponds to the obtaining, organization, and treatment of the data; the second involves the application of mathematical models to determine the yield, operating temperature, nominal power, and estimated power; and the third is to generate the correlations obtained between the monitored climatic variables, whether on an hourly, daily, monthly, or annual scale. For an average temperature of 27.50ºC in March, it was verified that the ultraviolet radiation was 5.06, while the average of the total radiation was 481.01 W.m-2. The maximum peak temperature was 27.88°C at noon, while the ultraviolet radiation was 8.55 and total radiation was 794.97 W.m-2. At this average temperature variation of 0.38°C, there is a variation of 313.96 W.m-2. It is concluded that, because São Luís is very close to the equator, the conditions to produce the system are favorable, mainly because, on average, there were no abrupt changes in temperature and radiation for the period studied. Even in the wintry period, the production behaved within the parameters designed.

The Summer Is Coming: nocte and timeless Genes Are Influenced by Temperature Cycles and May Affect Aedes aegypti Locomotor Activity.

Mosquitoes exhibit activity rhythms, crucial for the transmission of pathogens, under the control of a circadian clock. Aedes aegypti is one of the world’s leading vectors. For decades, several studies have linked the rise in ambient temperature with the increase in their activity. Here, we identify candidate genes whose expression is influenced by temperature cycles and may affect Aedes locomotor activity. We observed that timeless completely lost its rhythmic expression in light/dark, with out-of-phase temperature cycles, and by RNAi mediated knockdown of nocte, an important gene for Drosophila circadian synchronization by temperature cycles. Thus, timeless and nocte are important genes for synchronization by temperature cycles in Aedes aegypti. To reinforce our findings, we simulated in the laboratory the gradual temperature fluctuations that were as close as possible to daily temperature variations in Brazil. We observed that the activity and the expression of the molecular circadian clock of Ae. aegypti differs significantly from that of mosquitoes subjected to constant or rectangular abrupt changes in temperature. We suggest that for understanding the circadian behavior of Aedes with possible implications for intervention strategies, the seminatural paradigm needs to replace the traditional laboratory study.

Seasonal Dynamics of Catalase Activity in Cystoseira crinita (Black Sea) and Fucus vesiculosus (Barents Sea)

Abstract The seasonal dynamics of catalase activity of two related species of brown macroalgae, Cystoseira crinita (Desf.) Bory (1832) and Fucus vesiculosus L. (1753) was studied. In general, catalase activity (CA) in C. crinita was several times higher than in F. vesiculosus. The maximum values of CA in C. crinita were observed in November and the minimum ones in September. For F. vesiculosus, the maximum CA was found in January and the minimum in April. Abrupt changes in water temperature significantly affected the catalase activity in C. crinita and F. vesiculosus. In both species of algae, a similar seasonal trend in the change of CA was noted: two periods of adaptation adjustment associated with sharp changes in the temperature regime (spring and autumn) were distinguished. In spring, with a rapid increase in the temperature of the water masses, catalase inactivation occurred, whereas during summer to winter transition, accompanied by a sharp water cooling, catalase activity increases. Stabilization of the CA values of the studied macroalgae in the absence of sharp temperature variability was observed. However, this period of “stationary state” varies in time: in Cystoseira crinita it lasts from May to August, and in Fucus vesiculosus it lasts from May to December.