Mass Release Research Articles

A Conservative Approach for the Fast Deflagration Analysis in the Containment With GASFLOW-MPI

The nuclear regulation authorities of many countries require that the containment remains its integrity for a local hydrogen risk during any possible accident conditions. Therefore, the combustion consequence should be analyzed to demonstrate that the containment integrity is not being challenged for the hydrogen risk when the flame acceleration risk cannot be safely ruled out. Considering the uncertainties of both the combustion model and severe accident analysis, the criteria and experimentally based combustion (CREBCOM) model is adopted to provide a conservative result for pressure and the thermal load for combustion analyses in this study. Firstly, the CREBCOM is developed in the GASFLOW-MPI code and validated with the RUT experiment. The result shows that the CREBCOM model can provide a reliable overpressure for the choking regime combustion. Then, this model is adopted for the hydrogen safety analysis for the Advanced Pressurized Water Reactor (PWR) 1000. The hydrogen distribution is calculated with the mass and energy release obtained from severe accident analysis, from which, the most unfavorable ignition time and location is selected. The result of the CREBCOM model is compared with that of the turbulent flame closure model, which is a commonly used model for combustion analysis in containment safety. The results show that the CREBCOM model can provide a conservative prediction for the pressure and thermal load of combustion. Therefore, the CREBCOM model with the sonic flame assumption is applicable for the FA risk analysis in a local compartment for nuclear containments where a sonic deflagration cannot be safely excluded and manages to obtain a conservative pressure and thermal load for further evaluation on the containment integrity.

A male-specific sex marker for the endangered western sawshelled turtle (Myuchelys bellii) using in silico whole-genome subtraction

Artificial incubation of eggs for the mass release of hatchlings is a common conservation intervention for imperilled turtle species. Programs designed to reinforce wild populations need to ensure that they are releasing appropriate male to female ratios into the wild. In many turtle species, the sex of juveniles cannot be identified using external morphology until they approach sexual maturity. For the endangered western sawshelled turtle, Myuchelys bellii, sexual dimorphism does not occur until at least 6 years of age. We aimed to develop a molecular test to identify the sex of M. bellii during the life stages where they cannot be sexed morphologically—embryos, hatchlings and small juveniles. We used in silico whole-genome subtraction of a female M. bellii (XX) from a male (XY) to identify a Y chromosome-specific sequence which we characterized and developed into a PCR sex test. Our research is the first to use a whole-genome subtraction method in-silico to successfully establish sex chromosome markers in a freshwater turtle species. Developing this technology provides an opportunity for conservation programs to ensure that populations are supplemented with a proportionate number of male and female hatchlings. Further, it allows large scale measurement of naturally occurring sex ratios in hatchlings and small juveniles, which in turn enables estimates of sex ratios within wild populations free from age-at-maturity bias. The application of sex-specific marker technology also provides an opportunity to quantify the influence of sex on behaviour, movement and survival in the segment of populations that cannot be morphologically sexed.

Analysis on containment thermal hydraulic behaviour under passive containment heat removal system operation condition for HPR1000

HPR1000 NPP is designed with Passive Containment Heat Removal System (PCS) following the technical route called active and passive combined concept. The installed PCS system will have effect on the thermal hydraulic (T-H) behavior in the containment, and the complex T-H environment will influence the heat removal and operating character of PCS system backwards. The main goal of this work is to evaluate the effectiveness of the PCS system of HPR1000 and analyse the complex T-H environment of HPR1000 when the PCS system is operating. The HPR1000 containment is modelled by the containment T-H code and the PCS system is modelled based on experiment results. Then, the severe accident sequence initiated by large break LOCA is calculated by an integrated computer code, which outputs mass and energy release sources from reactor coolant primary system as boundaries for the containment T-H code. The results show that HPR1000 PCS system has enough heat removal capability under selected severe accident, which could ensure the containment meet the design requirement. Also, the nonuniformity of temperature and gases in the containment will disappear when the mass and energy releases turn stable, and the operating of PCS system does not cause a huge effect on containment inhomogeneity.

Predicting first-order evaporation rate constant alpha (α) from small spills of organic solvents in a controlled environment

Exposures to vapors generated by small spills of organic solvents are common in the occupational hygiene practice. In these scenarios, contaminant mass release is exponentially decreasing, driven by an evaporation rate constant alpha (α). Knowing α is fundamental for adequately modeling peak concentrations and/or short-term exposures that occur and for achieving efficient occupational risk analysis and management. The purpose of this study was to measure alpha experimentally using a gravimetric approach in a controlled environment during solvent evaporation tests designed to simulate small spills of solvents. The effects of several factors on α were evaluated. Equations based on regression models derived from the experimental data were proposed for predicting α. Predictions were externally validated against experimental data. A total of 183 tests was performed. Data analyses found that alpha (α) values increased with vapor pressure, spill surface area-to-spill volume ratio, and air speed across the spill. Larger α were associated with petri dish containers compared to watch glasses. Three regression models were created for predicting α. They had four variables in common, namely vapor pressure, molecular weight, air speed above the liquid, and surface tension of the liquid. The fifth variable was either spill volume, spill surface area, or spill surface area-to-spill volume ratio. The R2 of the regression models were equal to 0.98. External validation showed mean relative errors of −32.9, −32.0, and −25.5%, respectively, with associated standard deviations of the relative errors of 17.7, 33.3, and 26.0%, respectively, and associated R2 of 0.92, 0.65, and 0.87, respectively. The proposed equations can be used for estimating α in exposure scenarios similar to those evaluated in this study. Moreover, these models constitute a step further in the improvement of knowledge on estimating evaporation rates for small spills of organic solvents.

Proximal Ulna Osteotomy for Complex Fractures of the Distal Humerus: A 3-Dimensional Laser Analysis and Comparison With Olecranon Osteotomy

The current methods of distal humerus (DH) articular surface visualization only allow a limited view of the joint. This study describes an osteotomy procedure that increases the visualization of and access to the DH articular surface for fixation without compromising ligaments. Eighteen fresh-frozen human elbows (9 matched pairs) underwent proximal ulna osteotomy (PUO) or transverse olecranon osteotomy (OO) contralaterally. The visualized articular surface of the DH was demarcated, and the surface areas of the DH, capitellum, and trochlea were measured using 3-dimensional scanning. The angular arc of the articular surface of the capitellum and trochlea was measured using a goniometer. The 3-dimensional scans showed that 87.6% of the total DH surface area was visualized using PUO versus 65.6% using OO. When the trochlea and capitellum surface areas were separated, 94.0% versus 75.9% of the trochlea and 74.8% versus 44.7% of the capitellum were visualized using PUO and OO, respectively. The goniometric angles demonstrated that 98.2% versus 70.9% of the trochlea and 75.1% versus 43.5% of the capitellum articular surface arc angles were visualized using PUO and OO, respectively. After PUO with further release of the flexor-pronator mass was performed, 100% of the DH articular surface was visualized. Proximal ulnar osteotomy improves the visualization of the DH articular surface. Proximal ulna osteotomy spares ligaments, avoids osteotomizing the greater sigmoid notch, involves more robust metaphyseal bone for potentially better fixation, and may permit DH arthroplasty without compromising primary ligamentous elbow stabilizers. Further clinical studies are needed to assess the utility of this type of osteotomy.

Geochemical conditions influence vanadium, nickel, and molybdenum release from oil sands fluid petroleum coke

Petroleum coke is a potential source of vanadium (V), nickel (Ni), and molybdenum (Mo) to water resources in Athabasca Oil Sands Region (AOSR) of northern Alberta, Canada. Large stockpiles of this bitumen upgrading byproduct will be incorporated into mine closure landscapes and understanding the processes and conditions controlling the release and transport of these transition metals is critical for effective reclamation. We performed a series of laboratory column experiments to quantify V, Ni, and Mo release from fluid petroleum coke receiving meteoric water (MW), oil sands process-affected water (OSPW), and acid rock drainage (ARD) influents. We found that influent water chemistry strongly influences metal release, with variations among metals largely attributed to pH-dependent aqueous speciation and surface reactions. Cumulative V, Ni, and Mo mass release was greatest for columns receiving the low-pH ARD influent. Additionally, cumulative V and Mo mass release were greater in columns receiving OSPW compared to MW influent, whereas cumulative Ni mass release was greater in columns receiving MW compared to OSPW influent. Nevertheless, only a small proportion of total V, Ni, and Mo was released during the experiments, with the majority occurring during the first 10 pore volumes (PVs). This study offers insight into geochemical controls on V, Ni, and Mo release from fluid petroleum coke that supports ongoing development of oil sands mine reclamation strategies for landscapes that contain petroleum coke.

The LISA DFACS: Model Predictive Control design for the test mass release phase

This paper presents a Model Predictive Control (MPC) design for the test mass release phase of the LISA space mission. LISA is a gravitational wave observatory consisting of a triangular constellation of three spacecraft. The gravitational waves are detected by measuring the relative distance between free falling test masses by means of a laser interferometer. Each test mass is a cubic body located inside an electrostatic suspension that is initially locked by a clamp mechanism. Once the plungers are retracted, the test masses are released with high initial offsets and velocities. To detect the gravitational waves, each test mass must be accurately positioned at the cage centre and its attitude must be aligned with the local cage frame. However, the low actuation authority of the electrostatic suspension along with the critical initial conditions, make the attitude and translation control a difficult task. MPC is a suitable technique for this application because it can systematically account for command saturations, state constraints and can provide optimal (or sub-optimal) control inputs by solving an optimization problem online. In this paper, an MPC controller is designed and validated by means of Monte Carlo simulations, achieving satisfactory results.

Integrated control of Aedes albopictus in Southwest Germany supported by the Sterile Insect Technique

BackgroundThe invasive species Aedes albopictus, commonly known as the Asian tiger mosquito, has undergone extreme range expansion by means of steady introductions as blind passengers in vehicles traveling from the Mediterranean to south-west Germany. The more than 25 established populations in the State of Baden-Württemberg, Palatine and Hesse (south-west Germany) have become a major nuisance and public health threat. Aedes albopictus deserves special attention as a vector of arboviruses, including dengue, chikungunya and Zika viruses. In Germany, Ae. albopictus control programs are implemented by local communities under the auspices of health departments and regulatory offices.MethodsThe control strategy comprised three pillars: (i) community participation (CP) based on the elimination of breeding sites or improved environmental sanitation, using fizzy tablets based on Bacillus thuringiensis israelensis (fizzy Bti tablets; Culinex® Tab plus); (ii) door-to-door (DtD) control by trained staff through the application of high doses of a water-dispersible Bti granular formulation (Vectobac® WG) aimed at achieving a long-lasting killing effect; and (iii) implementation of the sterile insect technique (SIT) to eliminate remaining Ae. albopictus populations. Prior to initiating large-scale city-wide treatments on a routine basis, the efficacy of the three elements was evaluated in laboratory and semi-field trials. Special emphasis was given to the mass release of sterile Ae. albopictus males.ResultsMore than 60% of the local residents actively participated in the first pillar (CP) of the large-scale control program. The most effective element of the program was found to be the DtD intervention, including the application of Vectobac® WG (3000 ITU/mg) to potential breeding sites (10 g per rainwater container, maximum of 200 l = maximum of approx. 150,000 ITU/l, and 2.5 g per container < 50 l) with a persistence of at least 3 weeks. In Ludwigshafen, larval source management resulted in a Container Index for Ae. albopictus of < 1% in 2020 compared to 10.9% in 2019. The mean number of Aedes eggs per ovitrap per 2 weeks was 4.4 in Ludwigshafen, 18.2 in Metzgergrün (Freiburg) (SIT area) and 22.4 in the control area in Gartenstadt (Freiburg). The strong reduction of the Ae. albopictus population by Bti application was followed by weekly releases of 1013 (Ludwigshafen) and 2320 (Freiburg) sterile Ae. albopictus males per hectare from May until October, resulting in a high percentage of sterile eggs. In the trial areas of Ludwigshafen and Frieburg, egg sterility reached 84.7 ± 12.5% and 62.7 ± 25.8%, respectively; in comparison, the natural sterility in the control area was 14.6 ± 7.3%. The field results were in line with data obtained in cage tests under laboratory conditions where sterility rates were 87.5 ± 9.2% after wild females mated with sterile males; in comparison, the sterility of eggs laid by females mated with unirradiated males was only 3.3 ± 2.8%. The overall egg sterility of about 84% in Ludwigshafen indicates that our goal to almost eradicate the Ae. albopictus population could be achieved. The time for inspection and treatment of a single property ranged from 19 to 26 min depending on the experience of the team and costs 6–8 euros per property.ConclusionsIt is shown that an integrated control program based on a strict monitoring scheme can be most effective when it comprises three components, namely CP, DtD intervention that includes long-lasting Bti-larviciding to strongly reduce Ae. albopictus populations and SIT to reduce the remaining Ae. albopictus population to a minimum or even to eradicate it. The combined use of Bti and SIT is the most effective and selective tool against Ae. albopictus, one of the most dangerous mosquito vector species.Graphical

Antegrade dissection of external iliac artery after failed attempt of common femoral artery chronic total occlusion angioplasty

Introduction. Endovascular treatment of chronic total occlusion (CTO) represents a true challenge even for experienced interventional radiologists. We are presenting a case of hidden antegrade dissection of the external iliac artery (EIA) after a failed attempt to recanalize CTO of the common femoral artery (CFA). Case outline. A 52-year-old male patient was admitted for multidetector computed tomography (CT) angiography. Left common iliac artery (CIA) stenting was performed, followed by ?crossover? attempt of recanalization of right CFA CTO that failed. The next day, left femoral superficial artery angioplasty was performed and after one month, angioplasty of the left popliteal and the bellow-knee arteries. A month later, the patient was readmitted for surgical reconstruction of the CFA. After desobstruction, excellent inflow was obtained and a Dacron graft was inserted. A few hours postoperatively, Fogarty catheter thrombectomy was performed. The next morning, pulsations were weakened again and CT angiography showed antegrade dissection of the EIA. Stenting of the EIA was performed with two stents and a favorable outcome was achieved. After a detailed analysis of the CT, hidden thrombosed antegrade dissection of the EIA was noted in the lateral view, which was not seen in the posterior/anterior view and was presented as fibrous plaque with mural thrombosis. Dissection occurred after failed attempt of CFA recanalization and was clinically silent until flow was established triggering opening of the false lumen and the release of thrombotic masses. Conclusion. In patients with failed angioplasty of CTO of the CFA and CT characteristics of fibrous plaque proximal to the site of attempted angioplasty, thrombosed antegrade dissection should be considered.

Test mass capture for drag-free satellite based on RBF neural network adaptive sliding mode control

For drag-free satellites, one core technology required to achieve the mission requirements is the capture control of the test mass after release. The purpose of capture control is to avoid collisions between test mass and satellite cavity. Currently, there are few studies concerning the capture control of test mass after release. This paper presented a high-precision capture control method for the test mass release, which covers attitude-orbit modeling with 12 degrees of freedom, RBF neural network adaptive sliding mode controller design, actuation waveforms selection, actuation strategy selection, performance results, and contrast analysis.

Integrated surface-subsurface water and solute modeling of a reclaimed in-pit oil sands mine: Effects of ground freezing and thawing

Study regionAthabasca Oil Sands, Alberta, Canada. Study focusThe upland and wetlands substrate in reclaimed oil sands landforms will be constructed of post-mining materials with an objective of replicating the landscape and hydrology of the surrounding boreal systems. Porewater in these materials contain elevated levels of salts and other solutes. Water quality will govern the success and sustainability of the reclaimed landscape. Tightly coupled water and heat dynamics control water and solute movement in boreal systems. We used three-dimensional integrated surface-subsurface flow and chloride transport models with and without ground freezing-thawing to compare performance of an in-pit oil sands mine currently being reclaimed. New hydrological insights for the regionTransient simulations under wet/dry climate cycles suggest that the reclaimed landform will shed water only during wet years. Annual water balance with and without coupled heat dynamics is identical. However, the three-dimensional representation of ground freeze-thaw results in reduced snowmelt infiltration, summer groundwater table, and solute release during winter. The outcome is increased spring runoff, 20% decrease in chloride mass release over simulated eight-year wet climate cycle and relatively reduced summer runoff. The model results suggest that (1) coupled heat dynamics should be considered for detailed evaluation of reclaimed in-pit landforms at finer time scales, and (2) modeling reclaimed landforms without freeze-thaw provides conservative annual solute release estimates, which is appropriate for coarse site-wide models.

The mass release of migrants from UK immigration detention during the COVID-19 pandemic: what can be learned?

Convincing international evidence demonstrates that immigration detention adversely affects mental health. During the COVID-19 outbreak, additional concerns were raised about the safety and appropriateness of immigration detention. Consequently, several hundred migrants were released en masse from UK immigration detention centres, and few new detentions took place. Over 70% fewer migrants were held in detention centres in June 2020 compared with December 2019. This large 'natural experiment' has demonstrated that detaining fewer migrants is possible and it provides an opportunity to review the necessity for large-scale detention for the purpose of immigration control, as well as its impact on health inequalities. Additionally, given that detainee release arrangements had already been considered unsafe prior to the pandemic, clinicians and service providers should take into consideration that many of those released may not be receiving adequate post-release continuity of care.

Simulating the effect of check dam collapse in a debris-flow channel

Sequences of erosion control/consolidation check dams are the most widespread channel countermeasure in the European Alps. Some of them were built in the past based on ancient technologies. Nowadays they may not be fully adequate to mitigate the debris-flow/flood events that are becoming more frequent and intense. Consequently, there is the remote possibility that they could fail with disastrous consequences as observed in some cases. A reliable methodology to reproduce the effect of check dam collapse has not yet proposed. Therefore the aim of this study is to define a procedure to simulate the effect of check dam collapse in a debris-flow event.In this study we analysed the catastrophic debris flow occurred in the Rotian channel (Italian Alps) during which a series of check dams collapsed magnifying the event and causing severe damages.With the aid of field data we reconstructed the event and used the simulation tool r.avaflow to reproduce the debris flow. We then defined three scenarios to simulate the event: (A) debris-flow propagation over an erodible channel; (B) propagation on a rigid channel bed combined with the release of impulsive masses to isolate the analysis of the effect of check dam collapse; (C) a combination of the previous scenarios. The simulation performance was assessed analysing the pre- and post-event LiDAR surveys.Results showed that the C scenario accurately reproduced the observed debris-flow erosion pattern. In particular, we found out that most of the entrained debris volume derived from bed erosion rather than the sediment retained by check dams. The adopted method, which composes the contribution of bed erosion and check dam collapse, could be of particular relevance for residual risk estimation when mitigation structures are old and may fail with potential disastrous consequences.

CaV1.3 L-type Ca2+ channel modulates pancreatic β-cell electrical activity and survival

Pancreatic β cells express several high voltage-gated Ca2+ channel (HVCC) isoforms critical for insulin release, cell differentiation, and survival. RNaseq and qPCR analyses demonstrated that CACNA1D gene encoding for CaV1.3-α1D isoform is highly expressed in pancreatic islets of both mice and men. Additionally, CACNA1D genetic polymorphisms were associated with increased susceptibility for diabetes while CaV1.3 gain-of-function mutations cause hyperinsulinemia in humans. Nevertheless, functional evidence for the role of CaV1.3 on β-cell electrical activity, insulin release, and β-cell mass is contradictory and largely unknown. Here, we show that CaV1.3 deletion led to a sixfold increase in DNA damage and a threefold decrease in proliferation markers in pancreatic β cells of 14-d-old mice, while adult mice were largely unaffected. However, β-cell mass was reduced by ∼20% in both young and old mice, resulting in a diminished sustained insulin release. Voltage-clamp recordings in β-cells of 14-d-old mice showed an ∼20% reduction in total Ca2+ influx (WT Ipeak = -19.76 ± 1.04 pA/pF; CaV1.3-/- Ipeak = -14.84 ± 0.61 pA/pF, P = 0.001) accompanied by slower inactivation and an ∼5 mV rightwards shift in the voltage dependence of activation (WT V1/2 = -7.71 ± 0.82 mV; CaV1.3-/- V1/2 = -2.32 ± 1.09 mV, P = 0.0003). Although to a lower extent, Ca2+ influx in adult CaV1.3-/- β cells was similarly affected. Moreover, current-clamp recordings showed that CaV1.3 deletion delayed the glucose-induced action potential (AP) onset, reduced AP firing frequency (e.g., at 7.5 mM glucose, WT = 4.3 Hz; CaV1.3-/- = 2.1 Hz, P = 0.001) and AP-train frequency (e.g., at 7.5 mM glucose intertrain interval, WT = 49.3 ± 9.6 s; CaV1.3-/- = 120.3 ± 25.5 s, P = 0.04) in both young and adult β cells. Therefore, our data demonstrate that the CaV1.3 channel is required for the initiation of glucose-induced β-cell electrical activity and modulates β-cell mass and insulin release in both young and old mice.

Risk assessment of lead and cadmium leaching from solidified/stabilized MSWI fly ash under long-term landfill simulation test

The long-term effectiveness concern of municipal solid waste incineration (MSWI) fly ash (FA) disposal has been placed more emphatic recently, however, few studies worked on the control of leaching risk of heavy metals under the long-term stability. In this study, the leaching properties and risk assessment of two representative solidified/stabilized (S/S) FA wastes, i.e., sodium dithiocarbamate (DTC) chelator treated and Portland cement + chelator combining treated, were evaluated by a long-term cycles assessment method which coupled multifaceted environmental stresses (e.g., freezing-thawing, drying-wetting, accelerated carbonation). The results showed that the cement/chelator had a better long-term stability and exhibited ~55% lower cumulative overall pollution toxicity index (OPTI) than chelator treatment after the test, which was always rated as “low risk” during the cycles. In addition, the cement/chelator exhibited ~23.3% smaller cumulative mass release rate than the chelator treatment after 6 cycles and restrained the transformation of Pb and Cd from stable states to removable fractions, which attributes to its great erosion resistance and compact pore structure. Under the cumulative external factors and carbon dioxide attacks, the decalcification of hydrate products (e.g., C-S-H, hydrocalumite), as well as deterioration of pore structure are the critical factors increasing the local erosion, cracking and heavy metals release. Thus, the optimization of S/S waste microstructure (e.g., enhancing binder system) and landfill site conditions (e.g., reducing rainfall impact) could be propitious to the S/S waste risk control and management.

Temperature-Inducible Precision-Guided Sterile Insect Technique.

Releases of sterile males are the gold standard for many insect population control programs, and precise sex sorting to remove females prior to male releases is essential to the success of these operations. To advance traditional methods for scaling the generation of sterile males, we previously described a CRISPR-mediated precision-guided sterile insect technique (pgSIT), in which Cas9 and gRNA strains are genetically crossed to generate sterile males for mass release. While effective at generating F1 sterile males, pgSIT requires a genetic cross between the two parental strains, which requires maintenance and sexing of two strains in a factory. Therefore, to advance pgSIT further by removing this crossing step, here we describe a next-generation temperature-inducible pgSIT (TI-pgSIT) technology and demonstrate its proof-of-concept in Drosophila melanogaster. Importantly, we were able to develop a true breeding strain for TI-pgSIT that eliminates the requirement for sex sorting-a feature that may help further automate production at scale.

Modelling the effects of water chemistry and flowrate on clay erosion

Clay buffer is a key component of the engineered barrier system (EBS) for geological disposal of higher activity radioactive waste. Experimental observations indicate the possibility of buffer erosion at the interface with host rock due to interactions with groundwater. Existing models for clay erosion are very limited in terms of addressing the hydro-chemical effects, while the assessment of the long-term performance of clay buffer requires robust predictive models covering expected environment conditions and multiphysics phenomena involved in the erosion process. The work presented here is a step towards such a predictive capability, which considers clay expansion, detachment of clay particles and transport of detached particles by groundwater within a single modelling framework. The effects of solution chemistry and flowrate on the penetration, extruded mass and particle release rate of clay buffer are investigated in this paper. A series of experimental data are used to validate the swelling and erosion model developed in this study. The results show that the extrusion distance, which is controlled by both clay swelling and detachment processes, is nearly linearly dependent on the water flowrate irrespective of the water chemistry. Similar linear dependence of the erosion rate on water flowrate is observed for flowrates less than 10−5 m/s. Higher water flowrates are shown to induce nonlinearly increasing erosion rates in accordance with experiments. A flowrate threshold is found above which the erosion behaviour of compacted bentonite can be significantly affected. A concept of tolerance time for clay buffer is introduced as a failure criterion. The results indicate that the coupled effect of water chemistry and velocity requires further investigation for ionic concentrations below 1 mM.

Exploring the nature of ambiguous merging systems: GW190425 in low latency

GW190425 is a recently discovered gravitational wave (GW) source whose individual binary components are consistent with being neutron stars (NSs). However, the source-frame chirp mass 1.44 ± 0.02 M⊙ is larger than that of any double NS system known as yet, and it falls in the ‘ambiguous’ interval for which the presence of a black hole (BH) cannot be ruled out from the GW signal analysis alone. GW190425 might host an NS and a light BH, with a mass in the so-called lower mass gap. No electromagnetic (EM) counterpart has been associated with this event, due to the poorly informative sky localisation and larger distance compared to GW170817. We construct kilonova (KN) light curve models for GW190425, in both the double NS and BH-NS scenarios, considering two equations of state (EoSs) consistent with current constraints from GW170817 and the NICER results, including BH spin effects, and testing different fitting formulae for the ejecta mass. According to our models, the putative presence of a light BH in GW190425 would have produced a brighter KN emission compared to the double NS case, ideally leading to the possibility of distinguishing the nature of the binary. However, depending on the adopted fitting formula for the ejecta, the feasibility of this distinction might depend on the EoS and on the BH spin. Concerning candidate counterparts of GW190425, classified later on as supernovae, our models could have been used to discard two transients detected in their early r-band evolution, as these fall outside the phase space encompassed by our models. We conclude that combining the chirp mass and distance information from the GW signal with a library of KN light curves can help in identifying the EM counterpart early on, and we stress that the low-latency release of the chirp mass in this interval of ambiguous values can be vital for successful EM follow-ups.

Effects of Constant versus Fluctuating Temperatures on Fitness Indicators of the Aphid Dysaphis plantaginea and the Parasitoid Aphidius matricariae.

Simple SummaryLike all organisms, insects encounter temperatures that fluctuate on different time scales: within a day, between days, or throughout the seasons. However, most studies on the impact of temperature on insect physiology, behavior, morphology, or ecology have focused on constant temperatures tested in the laboratory. In our study, we wanted to know if fluctuating temperatures during the day (7–17 °C, average 12 °C) can affect insects differently compared to a constant temperature of 12 °C. We used, as a model, the apple aphid Dysaphis plantaginea, a major threat to apple orchards worldwide, and its parasitoid Aphidius matricariae, which is used in biological control. We found that many traits—but not all—were affected. In particular, the fluctuating thermal regime reduced the development time of aphids and parasitoids, improved the rate of parasitism, and tended (albeit slightly) to increase the longevity of both species. In contrast, we did not find strong effects on morphological traits. Our results can be used to better predict how these agronomically important insects behave in orchards, how ecologically-relevant fluctuating temperatures affect host–parasitoid relationships, and ultimately what the implications are in the context of climate change and biological control.Testing fluctuating rather than constant temperatures is likely to produce more realistic datasets, as they are ecologically more similar to what arthropods experience in nature. In this study, we evaluated the impact of three constant thermal regimes (7, 12, and 17 °C) and one fluctuating thermal regime (7–17 °C with a mean of 12 °C) on fitness indicators in the rosy apple aphid Dysaphis plantaginea, a major pest of apple orchards, and the parasitoid Aphidius matricariae, one of its natural enemies used in mass release biological control strategies. For some—but not all—traits, the fluctuating 7–17 °C regime was beneficial to insects compared to the constant 12 °C regime. Both aphid and parasitoid development times were shortened under the fluctuating regime, and there was a clear trend towards an increased longevity under the fluctuating regime. The fecundity, mass, and size were affected by the mean temperature, but only the mass of aphids was higher at 7–17 °C than at a constant 12 °C. Parasitism rates, but not emergence rates, were higher under the fluctuating regime than under the constant 12 °C regime. Results are discussed within the framework of insect thermal ecology and Jensen’s inequality. We conclude that incorporating thermal fluctuations in ecological studies could allow for the more accurate consideration of how temperature affects host–parasitoid interactions and insect responses to temperature change over time.

Developmental Temperature Affects Life-History Traits and Heat Tolerance in the Aphid Parasitoid Aphidius colemani.

Simple SummaryIndividual insects can experience different temperatures across their lives. In consequence, development of immature stages can take place at temperatures contrasting with those that the adult will encounter. In order to study the adaptation of organisms to warm environments, it is interesting to establish the links between developmental temperature and responses of the adult generation, in terms of physiology, morphology, and behavior. We exposed the parasitoid Aphidius colemani to three temperatures during larval development (10, 20, or 28 °C). We then measured the responses of adult parasitoids regarding their traits (physiology, morphology) and their tolerance to high temperatures. Mass, lipid reserves, survival, and heat tolerance of adults were affected by the rearing temperature regime. This means that, overall, developmental temperatures may affect how insects respond to a given temperature once they are adults, which may consequently influence the ability of parasitoids to control their aphid hosts. These results are important in the context of biological control in hot environments, such as the Maghreb, where this species of parasitoid is used in mass release techniques to control aphids in various crops.Developmental temperature plays important roles in the expression of insect traits through thermal developmental plasticity. We exposed the aphid parasitoid Aphidius colemani to different temperature regimes (10, 20, or 28 °C) throughout larval development and studied the expression of morphological and physiological traits indicator of fitness and heat tolerance in the adult. We showed that the mass decreased and the surface to volume ratio of parasitoids increased with the development temperature. Water content was not affected by rearing temperature, but parasitoids accumulated more lipids when reared at 20 °C. Egg content was not affected by developmental temperature, but adult survival was better for parasitoids reared at 20 °C. Finally, parasitoids developed at 20 °C showed the highest heat stupor threshold, whereas parasitoids developed at 28 °C showed the highest heat coma threshold (better heat tolerance CTmax1 and CTmax2, respectively), therefore only partly supporting the beneficial acclimation hypothesis. From a fundamental point of view, our study highlights the role of thermal plasticity (adaptive or not) on the expression of different life history traits in insects and the possible correlations that exist between these traits. From an applied perspective, these results are important in the context of biological control through mass release techniques of parasitoids in hot environments.