Equivalent Distances Research Articles

Comparative analysis of the prediction accuracy of hydrogen cloud explosion overpressure peak based on three kinds of theoretical models

Abstract Hydrogen energy is pivotal in the energy transition due to its high efficiency and zero-emission characteristics. However, the potential for explosions constrains its broader application. Gaining insights into the dynamics of overpressure in hydrogen explosions is vital for the safe design of explosion-proof facilities and the determination of equipment spacing. This study investigates hydrogen explosions in open spaces of 1 m³ and 27 m³ volumes, analyzing flame propagation and overpressure distribution. It also evaluates the accuracy of three theoretical models in predicting peak overpressure. The results reveal that the spherical flame from a hydrogen cloud explosion transforms into an ellipsoidal shape upon contact with the ground. The average flame propagation velocity across different equivalent ratio is ordered as follows: Va (φ = 1.0) > Va (φ = 1.5) > Va (φ = 2.5) > Va (φ = 0.5). At equivalent distances, the peak overpressure of hydrogen cloud explosions is comparable across both scales. The traditional trinitrotoluene model overestimates the peak overpressure of hydrogen cloud explosions at both scales. The optimized trinitrotoluene model achieves over 90% accuracy in predicting hydrogen cloud explosions in 1m³ volumes but shows decreased accuracy in 27 m³ explosions. At source intensity level 3, the Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek multi-energy model exhibits a prediction accuracy of over 70% for peak overpressure in hydrogen cloud explosions, with consistent performance across different scales, rendering it a more reliable model for such predictions. This research enhances hydrogen safety assessment technologies by providing a more precise method for evaluating large-scale hydrogen cloud explosion risks.

Velocity as an overlooked driver in the echolocation behavior of aerial hawking vespertilionid bats.

Moving animals must gather information at sufficient rates, detail, and range relative to their velocity while filtering this information to that essential for a given task.1,2 Echolocators, because of their active sensory system, are exceptional models for investigating how animals filter and adjust information flow to motor patterns.3,4 During airborne prey capture, bats adjust echolocation and, by extension, how they probe for information in distance- and context-dependent ways.5,6,7 We investigated how sensory probing guides movement and how niche specializations shape strategies to integrate information acquisition and motion velocity. Specifically, we recorded three sympatric bats of the same foraging guild (edge-space hawkers), but different niches, as they intercepted airborne prey under identical conditions. When hawking, we find that the trawler, Myotis daubentonii, and the hawker, Pipistrellus pygmaeus, exhibit similar flight and echolocation behavior, whereas the gleaner, M. nattereri, flies slower and produces calls of lower duration and intensity, greater bandwidth and call interval, but similar beam breadth. Strikingly, these differences in echolocation behavior converge when accounting for flight speed. We show that these species move equivalent distances between call emissions and that all bats travel through their respective sonar ranges in the same time interval. Further, each echolocation call's duration is related to the two-way travel time of its sonar range, and thus velocity, the same way across species. The similarity in how these bats sample their environment relative to velocity suggests general mechanisms of information processing and conserved traits underlying auditory attention in vespertilionid bats and, perhaps, other echolocators.

Limitations and rotation of the two-armed phase spiral in the Milky Way stellar disc

Context. The Milky Way’s history of recent disturbances is vividly demonstrated by a structure in the vertical phase-space distribution known as the Gaia phase spiral. A one-armed phase spiral has been seen widely across the Milky Way disc, while a two-armed one has only been observed in the solar neighbourhood. Aims. This study aims to determine the properties of the two-armed phase spiral and to put it in a Galactic context, with the ultimate goal of understanding the structure and history of the Milky Way disc. Methods. The Gaia DR3 data were used to trace and characterise the two-armed phase spiral. Special focus was put on the phase spiral’s spatial distribution, rotational behaviour, and chemical characteristics. To quantify the properties of the phase spiral, we used a model that fits a spiral pattern to the phase space distribution of the stars. Results. We found that the two-armed phase spiral is detectable only within a narrow range of galactocentric distances and angular momenta in the solar neighbourhood, R = 8 ± 0.5 kpc, LZ = 1450 ± 50 kpc km s−1. Outside this region, the phase spiral is one-armed. The two-armed phase spiral rotates with the phase angle, in a similar way to the one-armed phase spiral, and changes axis ratio with phase angle. Additionally, stars within the phase-space overdensity caused by the two-armed phase spiral pattern have slightly higher mean metallicity than stars in the underdense regions of the pattern at equivalent galactocentric distances, angular momenta, and vertical orbit extents. Conclusions. The two-armed phase spiral rotates with phase angle and its effect can be seen in metallicity, in a similar way to the one-armed phase spiral. However, the limited range over which it can be found, and its variation in shape are quite different from the one-armed version, suggesting it is a much more localised phenomenon in the Galactic disc.

Bayesian peak identification method for low count rate gamma spectrum under short-time measurement based on physical priors

A Bayesian peak identification method based on physical model had been proposed in this study to perform qualitative analysis for the low count rate gamma spectrum under short-time measurement. Based on the prior knowledge about gamma detection, the distribution of energy deposited in the detector near the region of interest of a target peak through photoelectric effect, Compton scattering and multiple scattering had been analyzed and approximated using three elementary components, then, the distribution of each component after convolution had been studied, and at last, a probabilistic mixture model had been proposed to directly describe the distribution of measured energy within region of interest. When the data measurement has been completed, a Gibbs sampler was used to estimate the posterior distribution of model parameters to discriminate the existence of target peaks. The numerical and physical experiments were performed to verify the effectiveness of the parameter estimation algorithm and the performance of the proposed identification method. The numerical experiments showed the identification precision is proportional to counts and peak-to-total ratio, when the peak-to-total ratio is greater than 0.5, the proposed method could identify the peak with a probability greater than 50% given 50 observations. The physical experiment used a NaI(Tl) detector to measure 137Cs, 60Co and 152Eu sources in a laboratory environment at different equivalent distances, the peak identification precision had been tested for the proposed method, and the experiments proved that the probabilistic model is a good approximation to the physical process, and the proposed identification method outperformed the conventional method under short-time measurement conditions.

Nutrient transport by overland sheet flow on sites containing swine slurry

Nutrients in agricultural runoff may cause offsite environmental impacts. The objective of this investigation was to examine nutrient transport by overland sheet flow on sites containing swine slurry. Data examined in this study was collected during field rainfall simulation tests conducted on cropland sites in southeast Nebraska, USA. Inflow was added to the top of experimental plots in four successive increments to simulate runoff rates occurring at greater downslope distances. Runoff rates on the experimental sites ranged from 2.3 to 21.2 L min−1 and maximum equivalent downslope distances varied from 5 to 108 m. Phosphorus (P) and nitrogen (N) transport rates were found to increase in a linear fashion with runoff rate. Hypothesis testing using the student’s t-test affirmed the prediction that a linear equation, calibrated for site specific conditions, can be used to relate nutrient transport rates to runoff rates. P and N transport rates were thought to be influenced by (a) the quantity of nutrients released by swine slurry at a particular runoff rate and (b) the amount of overland sheet flow available to transport the released nutrients. If nutrient transport rates can be linked to runoff rates, it may be possible to extrapolate experimental results obtained from small plots to greater downslope distances. Existing process-based models used to route overland sheet flow along hillslopes on upland areas could also be modified to include nutrient constituents.

Equivalent Modeling and Analysis of Handover Process in K-Tier UAV Networks

Featured by flexible deployment, unmanned aerial vehicles (UAVs) can form multi-tier networks in 3D space, enhancing the capacity, but this heterogeneity causes more unnecessary handovers (HOs), i.e., ping-pongs (PPs) and handover failures (HOFs). However, existing studies have not modeled the HO process in multi-tier UAV networks. This paper proposes an equivalent model for the HO process in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> -tier UAV networks, where nonlinear mapping rules are established from the altitude and transmit power to equivalent horizontal distances specific to HO events, then HO status during time-to-trigger (TTT) is analyzed via the mapping rules. Specifically, each trigger condition of the HO events is transformed into a circular boundary centered on the projection of the target UAV with the corresponding trigger radii. Considering the practical HO process, the HO trigger location is tractably modeled as a random variable of the path length from the start, and the signal-to-interference ratio during TTT and the residence time are analyzed through equivalent geometric relations. The results show that there exists an altitude ratio that causes the most frequent HO, which increases by 25% to 150% under different configurations. Trade-offs between HOF and PP exist in the altitude ratio and transmit power ratio, besides the HO parameters.

Bubble nucleation and jetting inside a millimetric droplet

In this work we present experiments and simulations on the nucleation and successive dynamics of laser-induced bubbles inside liquid droplets in free-fall motion, i.e. a case where the bubbles are subjected to the influence of a free boundary in all directions. Within this spherical millimetric droplet, we have investigated the nucleation of secondary bubbles induced by the rarefaction wave that is produced when the shock wave emitted by the laser-induced plasma reflects at the drop surface. Interestingly, three-dimensional clusters of cavitation bubbles are observed. Their shape is compared with the negative pressure distribution computed with a computational fluid dynamics model and allows us to estimate a cavitation threshold value. In particular, we observed that the focusing of the waves in the vicinity of the free surface can give rise to explosive cavitation events that end up in fast liquid ejections. High-speed recordings of the drop/bubble dynamics are complemented by the velocity and pressure fields simulated for the same initial conditions. The effect of the proximity of a curved free surface on the jetting dynamics of the bubbles was qualitatively assessed by classifying the cavitation events using a non-dimensional stand-off parameter ${\Upsilon\hskip -1,05em -\,}$ that depends on the drop size, the bubble maximum radius and the relative position of the bubble inside the drop. Additionally, we studied the role of the drop's curvature by implementing a structural similarity algorithm to compare cases with bubbles produced near a flat surface to the bubbles inside the drop. Interestingly, this quantitative comparison method indicated the existence of equivalent stand-off distances at which bubbles influenced by different boundaries behave in a very similar way. The oscillation of the laser-induced bubbles promotes the onset of Rayleigh–Taylor and Rayleigh–Plateau instabilities, observed on the drop's surface. This phenomenon was studied by varying the ratio of the maximum radii of the bubble and the drop. The specific mechanisms leading to the destabilisation of the droplet surface were identified.

Anisotropy safety potential field model under intelligent and connected vehicle environment and its application in car-following modeling

Potential field theory, as a theory that can also be applied to vehicle control, is an emerging risk quantification approach to accommodate the connected and self-driving vehicle environment. Vehicles have different risk impact effects on other road participants in each direction under the influence of road rules. This variability exhibited by vehicles in each direction is not considered in the previous potential field model. Therefore, this paper proposed a potential field model that takes the anisotropy of vehicle impact into account: (1) introducing equivalent distances to separate the potential field area in the different directions before and after the vehicle; (2) introducing co-virtual forces to characterize the effect of the side-by-side travel phenomenon on vehicle car-following travel; (3) introducing target forces and lane resistance, which regress the control of desired speed to control the acceptable risk of drivers. The Next Generation Simulation (NGSIM) dataset is used in this study to create the model's initial parameter values based on the artificial swarm algorithm. The simulation findings indicate that when the vehicle is given the capacity to perceive the surrounding traffic environment, the suggested the anisotropic safety potential field model (ASPFM) performs better in terms of driving safety.

A Deadlock-Free Hybrid Estimation of Distribution Algorithm for Cooperative Multi-UAV Task Assignment With Temporally Coupled Constraints

This study addresses the cooperative multi unmanned aerial vehicles task assignment problem (CMTAP) with temporally coupled constraints and aims to find a feasible assignment to minimize the equivalent distances of all tasks. We first present a mixed-integer linear programming model of CMTAP. To solve the undesirable deadlocks of CMTAP, a Petri net amender is constructed based on a candidate solution, and a deadlock-free solution is equivalent to a feasible transition sequence that can be fired sequentially in the corresponding amender. With this amender, we present a Petri net-based deadlock amending method (PDAM) with polynomial time complexity to convert a deadlocked solution into a deadlock-free solution. Also, a deadlock-free hybrid estimation of distribution algorithm (DHEDA) is developed for CMTAP by embedding PDAM into the original EDA. To further improve the solution quality, we establish a local exploitation method, and an adaptive operational probability is used to balance the computational burden and local exploitation ability. Then a match-up based reassignment method is proposed to cope with time-sensitive targets. Finally, extensive computational experiments demonstrate that PDAM is more effective at solving deadlocks than graph-based methods, particularly for large-scale CMTAP, and DHEDA outperforms existing algorithms when solving CMTAP.

Defining Phylogenetic Network Distances Using Cherry Operations.

In phylogenetic networks, picking a cherry consists of removing a leaf that shares a parent with another leaf, or removing a reticulate edge whose endpoints are parents of leaves. Cherry-picking operations were recently shown to have several structural and algorithmic applications in the study of networks, for instance in determining their reconstructibility or in solving the network hybridization and network containment problems. In particular, some networks within certain classes are isomorphic if they can be reduced to a single node by the same sequence of cherry-picking operations. Therefore, cherry-picking sequences contain information on the level of similarity between two networks. In this paper, we expand on this idea by devising four novel distances on networks based on cherry picking and their reverse operation. We provide bounds between these distances and show that three of them are equal despite their different formulations. We also show that computing these three equivalent distances is NP-hard, even when restricted to comparing a tree and a network. On the positive side, we show that they can be computed in quadratic time on two trees, providing a new comparative measure for phylogenetic trees that can be computed efficiently.

V10-07 AUTOLOGOUS FAT TRANSFER AS A PROSTATE-RECTAL SPACER FOR PROSTATE BRACHYTHERAPY

You have accessJournal of UrologyCME1 Apr 2023V10-07 AUTOLOGOUS FAT TRANSFER AS A PROSTATE-RECTAL SPACER FOR PROSTATE BRACHYTHERAPY Ezequiel Becher, Juan Fernandez Long, Marcelo Bou, Edgardo F Becher, Luis Montes de Oca, and Marcelo Borghi Ezequiel BecherEzequiel Becher More articles by this author , Juan Fernandez LongJuan Fernandez Long More articles by this author , Marcelo BouMarcelo Bou More articles by this author , Edgardo F BecherEdgardo F Becher More articles by this author , Luis Montes de OcaLuis Montes de Oca More articles by this author , and Marcelo BorghiMarcelo Borghi More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003328.07AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Implanted rectal spacers (IRS) have been developed to increase the distance between the prostate and the rectum, thus optimizing dose escalation in prostate brachytherapy (BT). Cost is a disadvantage and there is a lack of availability worldwide. We have developed an autologous fat transfer (AFT) technique to use as an IRS immediately after the implant of the seeds in low-dose-rate BT. We aim to present the feasibility and durability this technique. METHODS: A total of 120 patients underwent AFT (21 were treated with primary BT, 79 with a combined primary treatment of external beam radiotherapy and BT, 20 with salvage BT). The isodose used for primary BT was 14400 cGy, 11,000 cGy after 4600 cGy of external beam radiotherapy in the combined group, and 14400 cGy for the salvage group. Patients underwent a CT scan at 3, 6 and 12 months to measure the distance between the rectum and the prostate. RESULTS: An average of 18 cc (10-40) of fat was transferred successfully in 100% of cases.The mean distance to the rectum at the level of the base, middle, and apex at 1 and 6 months were 11.2, 9.7, and 7.6 mm; 8.3, 8.1, and 5.9 mm, respectively. No rectal toxicity or major complications were reported. CONCLUSIONS: The use of fat as an IRS seems to be a valid alternative to reduce rectal toxicity after BT, achieving equivalent distances to synthetic IRS. It is feasible, safe, and the loss of distance at 6 months is small. Cost is lower than other alternatives. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e928 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ezequiel Becher More articles by this author Juan Fernandez Long More articles by this author Marcelo Bou More articles by this author Edgardo F Becher More articles by this author Luis Montes de Oca More articles by this author Marcelo Borghi More articles by this author Expand All Advertisement PDF downloadLoading ...

Assessment of the universality of duplex stainless steel powder in laser additive repair based on Schaeffler diagram

The type and quantity of repair materials used in ocean or field environment is unclear. This study investigated the effective methods for evaluating the universality of a specific powder for multiple materials using a self-made universal duplex stainless steel powder (UDSS) as the object and tensile strength (σ) of the additive repair part in the normal direction of the interface as the index. Based on the Schaeffler diagram, the equivalent distances of Cr and Ni were used to characterize the chemical composition difference between the material to be repaired and the UDSS powder, and the angle θ was used to characterize the difference in microstructures. Three models, σ-(Cr eq , Ni eq ) , σ-ρ equivalent distance linear, and σ -( ρ,θ ) polar coordinate models, were proposed for predicting the strength of the additive repaired part. These models were verified using the results of repair tests on five substrates. The mean prediction error, pf, of the σ -( ρ, θ ) polar coordinate model was minimum, that is, approximately 9.68%. Under the conditions of this study, the maximum normal strengths of the repaired specimen interface in the normal direction were 689, 704, and 957 MPa in the austenite, ferritic, and ferrite + austenite regions, respectively, thus proving the universality of the UDSS powder used. This study provides a novel and a reliable method for evaluating the universality of UDSS powder for laser-additive repair. The relationship between the tensile strength and evolution of the microstructure, chemical composition, and microhardness near the interface is discussed.

Mitogenome Analyses Reveal Limited Introduction of Anopheles coluzzii Into the Central African Islands of São Tomé and Príncipe

Islands possess physical characteristics that make them uniquely well-suited for initial field trials of new genetic-based technologies applied to African malaria vectors. This has led to efforts to characterize the degree of isolation of island mosquito populations. São Tomé and Príncipe (STP) is a country composed of two small islands in the Gulf of Guinea (Central Africa) where Anopheles coluzzii is the primary malaria vector. Several studies have shown a relatively high degree of genetic isolation between A. coluzzii populations in STP and the mainland compared with pairs of mainland populations separated by equivalent distances. Here, we analyzed complete mitochondrial genomes of individual A. coluzzii specimens from STP and neighboring mainland countries. The objectives are to describe the history of A. coluzzii establishment in STP, specifically to address several questions germane to their suitability as sites for a field trial release of genetically engineered mosquitoes (GEMs). These questions include: (i) What are the origins of A. coluzzii populations in STP?; (ii) How many introductions occurred?; (iii) When was A. coluzzii introduced into STP? and (iv) Is there ongoing, contemporary gene flow into STP from mainland populations? Phylogenetic analysis and haplotype networks were constructed from sequences of 345 A. coluzzii from STP, and 107 individuals from 10 countries on or near the west coast of Africa. Analysis of these data suggest that there have been two introductions of A. coluzzii onto the island of São Tomé that occurred roughly 500 years ago and that these originated from mainland West Africa. It appears that A. coluzzii has never been introduced into Príncipe Island directly from mainland Africa, but there have been at least four introductions originating from São Tomé. Our findings provide further support for the notion that contemporary populations of A. coluzzii on São Tomé and Príncipe are genetically isolated from mainland populations of this mosquito species.

Different planning policies for the initial movement velocity depending on whether the known uncertainty is in the cursor or in the target: Motor planning in situations where two potential movement distances exist.

During goal-directed behaviors, individuals can be required to start a movement before deciding on the final goal. Previous studies have focused on the initial movement direction in situations involving multiple targets in different directions from the starting position and have shown that the movement is initiated in the average direction among the target directions. However, the previous studies only included situations with targets at equivalent distances, and the characteristics of motor planning in situations with multiple movement possibilities over different potential distances are unclear. In such situations, movement velocity is another important control variable. Furthermore, while previous studies examined situations with an uncertain motor target position, uncertainty can also exist in the effector position (e.g., body or tool locations). Therefore, we examined (1) whether the average output is confirmed in the initial movement velocity during execution in situations involving two potential movements with different distances. In addition, we examined (2) whether planning of the movement velocity can differ depending on the presence of uncertainty in the cursor or the target. In the main conditions, the participants were required to start a reaching movement with two potential movement distances; in the two-cursor condition, two cursors were presented before the start of the trial, and in the two-target condition, two targets were presented. As a control condition, a distance condition corresponding to each main condition was also performed. In the control condition, the initial movement velocity varied linearly with distance. Then, we tested whether the initial movement velocity in situations with two potential movement distances would follow the averaging output of the corresponding control condition. The results revealed that while the initial movement velocity in the two-target condition was slower than the averaging output, that in the two-cursor condition approached the averaging output. These results suggest that the velocity profile of the goal-directed movement is not simply averaged in a situation where two potential targets exist, and that there is a difference in the planning policy of the initial movement depending on whether the known uncertainty is for the movement goal or the effector.

Phylogenetic inference of where species spread or split across barriers

SignificanceGeography molds how species evolve in space. Strong geographical barriers to movement, for instance, both inhibit dispersal between regions and allow isolated populations to diverge as new species. Weak barriers, by contrast, permit species range expansion and persistence. These factors present a conundrum: How strong must a barrier be before between-region speciation outpaces dispersal? We designed a phylogenetic model of dispersal, extinction, and speciation that allows regional features to influence rates of biogeographic change and applied it to the neotropical radiation of Anolis lizards. Separation by water induces a threefold steeper barrier to movement than equivalent distances over land. Our model will help biologists detect relationships between evolutionary processes and the spatial contexts in which they operate.

Sex- and Age-related Differences in Spinal Degeneration: An Anatomical and Magnetic Resonance Imaging Study of the Human Spine.

ABSTRACTObjectives:A precise anatomical understanding of the morphology of the spine is indispensable for neck and low back pain therapy including rehabilitation. However, few studies have directly addressed spinal morphology with a focus on the height of the vertebral body and discs. The aim of the current study was to analyze sex- and age-related changes in the spine by measuring the distance between adjacent centers of the intervertebral disc spaces from the posterior aspect in cadavers and by using magnetic resonance imaging (MRI) measurements at the cervical and lumbar vertebral levels.Methods:In the cadaveric study, the posterior distance between the adjacent centers of the disc spaces was measured for 58 spinal canals. The equivalent distances were examined using MRI in 370 and 660 subjects who presented with neck pain and back pain, respectively.Results:The distance between the adjacent centers of the intervertebral disc spaces in male cadavers was larger than that in female cadavers from C3 to L5/S1. The MRI results showed that the distance between the adjacent centers of the intervertebral disc spaces decreased with age in all spinal areas in men and women. Cadaveric values were significantly lower than the MRI values in men, whereas in women, no significant differences were observed.Conclusions:These results suggest that age-related changes in the cervical and lumbar spine are associated with differences between men and women in the degrees of progressive vertebral body and disc degeneration.

Virtual Reality Application on Road Markings’ Visibility Analysis

The most important function of road markings is to guide road users; therefore, their visibility, in relation to retroreflectivity (RL), plays an essential role in the markings’ performance at nighttime. Researchers have applied field experiments to determine the minimum acceptable levels of markings’ RL. However, field studies usually involve a large investment of time, personnel, space, and budget. This paper presents a preliminary study that adopted virtual reality (VR) techniques to establish an immersive driving environment for the RL analysis of yellow markings. The objective is to evaluate the minimum required marking visibility for road users, especially senior drivers, while driving at nighttime. The brightness feature created in the VR model does not simulate the optical behavior of markings’ glass beads, but it simulates the marking’s visibility in relation to detection distance at each test drive. This is an alternative method to correlate the field RL and the VR simulation model through the equivalent detection distances that were recorded by the observers who participated in both field and VR driving tests. The relationship between the field markings’ RL, 80 to 130 mcd/m2/lx, and simulated markings’ brightness was successfully established with its limitations of RL between 80 and 130 mcd/m2/lx. Three age clusters are involved in this study, namely 20–30, 40–50, and 60+ years old, with 30 people in each cluster. The simulation study found that the driver’s behavior in relation to reaction time is highly related to age cluster but not driving speed or RL. The average reaction times for the three age clusters are 0.438 s, 0.499 s, and 0.522 s, respectively. However, the perception reaction time 2.5 s was considered while calculating the required RL for markings. Results found that the minimum required yellow markings’ RL increases with driving speed, and it requires 80 mcd/m2/lx for 50 km/h and 130 mcd/m2/lx for 65 km/h to satisfy the 85 percentiles of the driving population in Taiwan.

Multi-temperature X-ray diffraction study of a reversible structural phase transition in the high-temperature polymorph of Ce2Rh2Ga compound

A recently investigated HT-Ce2Rh2Ga was found to exhibit a magnetic phase transition at 128.5 K. A comprehensive multi-temperature investigation in the 85–400 K temperature range showed that the compound undergoes a structural phase transition as well. Upon cooling below 123.2 K its crystal symmetry changes from Cmce to C2/m being accompanied by non-merohedral twinning. Both structural transformations are reversible with a small hysteresis furthermore. The temperature of the structural phase transition was detected by anomalies in temperature dependences of unit cell dimensions, interatomic distances, and atomic displacement parameters. Negative thermal expansion along the c-axis was revealed in the range 92.7–170 K. When cooled to 200 K, Ce and Rh atoms converge to a distance sufficient for structural changes to become qualitative. Upon further cooling to 145 K, this interaction affects positions of all the atoms in the structure, leading to anisotropy of earlier equivalent interatomic distances and a sharp anomalous increase in atomic displacement parameters, the dynamics of which deviates more and more from the theoretical dependences in the Einstein and Debye approximations.

Transneuronal delivery of designer cytokines: perspectives for spinal cord injury.

Transneuronal delivery of designer cytokines: perspectives for spinal cord injury.

Mosquito sound communication: are male swarms loud enough to attract females?

Given the unsurpassed sound sensitivity of mosquitoes among arthropods and the sound source power required for long-range hearing, we investigated the distance over which female mosquitoes detect species-specific cues in the sound of station-keeping mating swarms. A common misunderstanding, that mosquitoes cannot hear at long range because their hearing organs are ‘particle-velocity’ receptors, has clouded the fact that particle velocity is an intrinsic component of sound whatever the distance to the sound source. We exposed free-flying Anopheles coluzzii females to pre-recorded sounds of male An. coluzzii and An. gambiae s.s. swarms over a range of natural sound levels. Sound levels tested were related to equivalent distances between the female and the swarm for a given number of males, enabling us to infer distances over which females might hear large male swarms. We show that females do not respond to swarm sound up to 48 dB sound pressure level (SPL) and that louder SPLs are not ecologically relevant for a swarm. Considering that swarms are the only mosquito sound source that would be loud enough to be heard at long range, we conclude that inter-mosquito acoustic communication is restricted to close-range pair interactions. We also showed that the sensitivity to sound in free-flying males is much enhanced compared to that of tethered ones.