Intense Bursts Research Articles

A high redshift population of galaxies at the North Ecliptic Pole

Context. Dusty high-z galaxies are extreme objects with high star formation rates (SFRs) and luminosities. Characterising the properties of this population and analysing their evolution over cosmic time is key to understanding galaxy evolution in the early Universe. Aims. We select a sample of high-z dusty star-forming galaxies (DSFGs) and evaluate their position on the main sequence (MS) of star-forming galaxies, the well-known correlation between stellar mass and SFR. We aim to understand the causes of their high star formation and quantify the percentage of DSFGs that lie above the MS. Methods. We adopted a multi-wavelength approach with data from optical to submillimetre wavelengths from surveys at the North Ecliptic Pole to study a submillimetre sample of high-redshift galaxies. Two submillimetre selection methods were used, including: sources selected at 850 μm with the Sub-millimetre Common-User Bolometer Array 2) SCUBA-2 instrument and Herschel-Spectral and Photometric Imaging Receiver (SPIRE) selected sources (colour-colour diagrams and 500 μm risers), finding that 185 have good multi-wavelength coverage. The resulting sample of 185 high-z candidates was further studied by spectral energy distribution fitting with the CIGALE fitting code. We derived photometric redshifts, stellar masses, SFRs, and additional physical parameters, such as the infrared luminosity and active galactic nuclei (AGN) contribution. Results. We find that the Herschel-SPIRE selected DSFGs generally have higher redshifts (z = 2.57−0.09+0.08) than sources that are selected solely by the SCUBA-2 method (z = 1.45−0.06+0.21). We find moderate SFRs (797−50+108 M⊙ yr−1), which are typically lower than those found in other studies. We find that the different results in the literature are, only in part, due to selection effects, as even in the most extreme cases, SFRs are still lower than a few thousand solar masses per year. The difference in measured SFRs affects the position of DSFGs on the MS of galaxies; most of the DSFGs lie on the MS (60%). Finally, we find that the star formation efficiency (SFE) depends on the epoch and intensity of the star formation burst in the galaxy; the later the burst, the more intense the star formation. We discuss whether the higher SFEs in DSFGs could be due to mergers.

Event-related potentials following gaps in noise: The effects of the intensity of preceding noise

Auditory temporal resolution is critical for the perception of speech. It is often studied using gap detection methods in which a silent period (or “gap”) is inserted in a long duration auditory stimulus. When the gap is inserted in a frequently occurring standard stimulus, it elicits a negative-going event-related potential, called the deviant-related negativity (DRN). A time-efficient multi-deviant paradigm was employed in which a standard 200 ms noise burst was presented on 50% of trials and a deviant stimulus, containing a gap, on the remaining 50% of trials. Seven different deviants were constructed by inserting a gap in the centre of the standard. The duration of the seven gaps ranged from 2 to 40 ms. In different conditions, the intensity of the noise burst was either 60 or 80 dB SPL. Ten adults watched a silent video while ignoring the auditory sequence. As expected, the amplitude of the DRN increased as gap duration became longer, regardless of the intensity of the noise in which the gap occurred. The intensity of the noise burst also affected the DRN measured peak-to-peak (DRN-to-following positivity). This was reduced when the gap occurred in the lower intensity noise burst. The time efficient multi-deviant paradigm can thus be employed to determine the effects of factors known to affect gap detection: the duration of the gap, and the intensity of the sound in which the gap is inserted.

Stimulation and inhibition of respiratory burst in neutrophils as a result of action of weak combined magnetic fields adjusted to ICR of protonated water forms

ABSTRACT Weak combined collinear magnetic fields (CMFs) composed of constant component, 60 μT and low-frequency alternating field, 100 nT, used in 40 min pretreatment, were shown to have diverse effects (alleviation/stimulation) depending on the frequency of the alternating component on respiratory burst intensity in neutrophil suspension after activation by N-formyl-Met-Leu-Phe recorded by luminol-dependent chemiluminescence. About 12.6 Hz frequency formally corresponding to ion cyclotron resonance (ICR) frequency of hydrated hydronium ion (Н9О4 +) had notable stimulating effect. On the contrary, treatment with 48.5 Hz frequency corresponding to hydronium ion (Н3О+) was accompanied by significant alleviation of respiratory burst intensity. CMFs-pretreated water conducted only stimulating effect of CMFs when the field was adjusted to ICR of hydrated hydronium ion form, which is direct proof of participation of water in the mechanism of this effect of CMFs.

Supervised Convolutional Neural Networks for Classification of Flaring and Nonflaring Active Regions Using Line-of-sight Magnetograms

Abstract Solar flares are explosions in the solar atmosphere that release intense bursts of short-wavelength radiation and are capable of producing severe space-weather. Flares release free energy built up in coronal fields, which are rooted in active regions (ARs) on the photosphere, via magnetic reconnection. The exact processes that lead to reconnection are not fully known and therefore reliable forecasting of flares is challenging. Recently, photospheric magnetic-field data has been extensively analyzed using machine learning (ML) and these studies suggest that flare-forecasting accuracy does not strongly depend on how long in advance flares are predicted. Here, we use ML to understand the evolution of AR magnetic fields before and after flares. We explicitly train convolutional neural networks (CNNs) to classify Solar Dynamics Observatory/Helioseismic and Magnetic Imager line-of-sight magnetograms into ARs producing at least one M- or X-class flare or as nonflaring. We find that flaring ARs remain in flare-productive states—marked by recall > 60% with a peak of ∼80%—days before and after flares. We use occlusion maps and statistical analysis to show that the CNN pays attention to regions between the opposite polarities from ARs and the CNN output is dominantly decided by the total unsigned line-of-sight flux of ARs. Using synthetic bipole magnetograms, we find spurious dependencies of the CNN output on magnetogram dimensions for a given bipole size. Our results suggest that it is important to use CNN designs that eliminate such artifacts in CNN applications for processing magnetograms and, in general, solar image data.

Source region identification and geophysical effects of stealth coronal mass ejections

We use the example of two Stealth-type coronal mass ejections (stealth CMEs) registered by LASCO C2 on the quiescent Sun on 16 June 2010 and in the active region NOAA 11520 7 July 2012 to demonstrate that these mass ejections emerged in a lower-coronal area where an intense short-term radiation burst was registered in several extreme ultraviolet channels. It is established for the first time that the stealth CME emergence is accompanied by an eruption of small-scale loop-like structures, and the frontal structure (FS) formation is detected. The time dependences of the velocity of these FSs are discussed. The conclusion is made that having reached Earth orbit and impacting on the Earth magnetosphere, the stealth CMEs can lead to magnetic substorm generation.

Application of Solar Radio Bursts Observation in Detecting Magnetic Reconnection Phenomenon

This study highlights the importance of solar activity observation in radio region which covers 45-870 MHz, which also provides clues on the appearance of magnetic reconnection. It was carried out by utilizing e-CALLISTO data from Glasgow station. On 9th March 2019, intense solar radio bursts type III sparked off and were detected by Glasgow station in the UK at 12.29 UT, that lasted for 15 minutes. There were two bursts that were observed to appear separately by 1-minute interval. Accompanying the bursts formation was a B6.5 flare, the highest flare throughout the day and it was recorded by NOAA at 12.26 UT which was in the time frame of the bursts event. It is believed that the type III bursts were associated to the flare formation as radio emissions were emitted at the beginning of the flare during reconnection. From the analysis, results have shown that multiple magnetic reconnection process took place during the solar activity as indicated by a large group of bursts. However, no extended bursts formed for the rest of the day as well as lack of activity produced by the same region for the following days and that could be a hint of the decay phase of AR 2734. Detailed discussions on the bursts corresponding to the flare activity are discussed in this paper.

Multiresponsive Hybrid Microparticles for Stimuli-Responsive Delivery of Bioactive Compounds

Hybrid microparticles based on an iron core and an amphiphilic polymeric shell have been prepared to respond simultaneously to magnetic and ultrasonic fields and variation in the surrounding pH to trigger and modulate the delivery of doxorubicin. The microparticles have been developed in four steps: (i) synthesis of the iron core; (ii) surface modification of the core; (iii) conjugation with the amphiphilic poly(lactic acid)-grafted chitosan; and (iv) doxorubicin loading. The particles demonstrate spherical shape, a size in the range of 1–3 µm and surface charge that is tuneable by changing the pH of the environment. The microparticles demonstrate good stability in simulated physiological solutions and are able to hold up to 400 µg of doxorubicin per mg of dried particles. The response to ultrasound and the changes in the shell structure during exposure to different pH levels allows the control of the burst intensity and release rate of the payload. Additionally, the magnetic response of the iron core is preserved despite the polymer coat. In vitro cytotoxicity tests performed on fibroblast NIH/3T3 demonstrate a reduction in the cell viability after administration of doxorubicin-loaded microparticles compared to the administration of free doxorubicin. The application of ultrasound causes a burst in the release of the doxorubicin from the carrier, causing a decrease in cell viability. The microparticles demonstrate in vitro cytocompatibility and hemocompatibility at concentrations of up to 50 and 60 µg/mL, respectively.

Phagocytic activity of blood monocytes in response to methicillin-resistant strains of Staphylococcus aureus

Current study performed to estimate the phagocytic activity of blood monocytes of varying phenotypes exposed to MRSA and MSSA strains. Objects: Blood monocytes were collected from 25 healthy adults (age: 25–45 years). Live suspensions of MRSA/MSSA strains were used at concentration of 106 colony-forming units (CFU)/mL. Metods. Phagocytic functions were estimated by using fluorescein isothiocyanate (FITC)-labelled MRSA and MSSA strains followed by running flow cytometry on FC 500 series flow cytometer (Beckman Coulter, USA). Whole peripheral blood cells were directly labelled with immunofluorescently tagged monoclonal CD14-PE/CD45-ECD/HLA-DR-PC5/CD16-PC7 antibodies (Beckman Coulter, USA). Respiratory burst intensity was evaluated in monocytes by measuring activity of lucigeninand luminol-dependent spontaneous and induced chemiluminescence. Monocytes were induced by using live suspension of MRSA/MSSA strains at a concentration of 106 CFU/mL. Results and discussion. While studying luminol-dependent monocyte activities after exposure to MRSA vs. MSSA, it was observed a 3.5-fold decreased curve square, whereas lucigenin-dependent chemiluminescence was increased by 6-fold. Compared to MSSA exposure, index of activation (IA) was decreased by 1.1-fold in response to MRSA exposure that was confirmed by lowered release of reactive oxygen species (ROS) from monocytes in response to MRSA exposure. Moreover, IRSS increased by 1.3-fold upon MRSA exposure. Examining monocyte oxygen-independent phagocytosis against MRSA vs. MSSA revealed significantly increased phagocytic number and concomitantly decreased phagocytic index. An evaluation of the activities of various monocyte subsets in response to MRSA vs. MSSA revealed increased phagocytic index by 1.5-fold for CD14lowCD16+ and CD14+CD16+ monocyte subsets as well as 3-fold for CD14+CD16– monocytes. Counts for all phagocytic subsets were decreased (1.4-, 1.5- and 4-fold for CD14lowCD16+, CD14+CD16+ and CD14+CD16– monocytes, respectively). To summarize, intensity of the respiratory burst was lowered upon MRSA exposure and percentage of monocyte subsets. Overall deficiency of superoxide anion production was observed in response to MRSA. In contrast, oxygen-independent event revealed phenotypic changes in frequency of peripheral blood monocytes upon MRSA exposure. We observed that CD14+CD16– classical monocytes were more rapidly activated. Conclusion. Thus, we concluded that CD14+CD16– monocytes became more rapidly activated but exhibited less effective phagocytosis, whereas CD14+CD16+ and CD14lowCD16+ monocytes were more slowly activated and demonstrated stronger phagocytic activity.

Nature of star formation in first galaxies

AbstractOne of the primary foci of research in astrophysics is on developing a rigorous understanding of the first galaxies. This entails studying the physical processes such as accretion, cooling and star formation in first galaxies, and also investigating the consequences of these processes in the present day Universe. We investigate the star formation in the early galaxies and its subsequent evolution using the eagle simulation and find that the star formation has a smooth evolutionary behaviour at low redshifts leading to a main sequence of star formation that can be explained by deterministic models using accretion history as an input. In contrast, at high redshift (>6), most of the galaxies are bursty. At high redshift, instead of exhibiting a main sequence in SFR – Mh plane, they bunch-up around a halo mass of ≈ 109 Mȯ and SFR ≈0.1 Mȯ yr−1. As a consequence, the reionization of the Universe is led by low mass haloes hosting brighter galaxies that are undergoing intense bursts. Furthermore, the bursts in the infant galaxies lead to a poorly mixed interstellar medium in which the stars can form from gas enriched predominantly by a single nucleosynthetic channel. The lower mass subset of the stars formed in first galaxies resemble the carbon enhanced metal poor stars in our Galaxy while the higher mass ones reionized the Universe.

Kink-antikink scattering in the ϕ4 model without static intersoliton forces

Kink-antikink scattering in the $\phi^4$ model is investigated in the limit when the static inter-soliton force vanishes. We observe the formation of spectral walls and, further, identify a new phenomenon, the vacuum wall, whose existence gives rise to a bouncing structure for the annihilating solitons. Furthermore, we discover higher order spectral walls, i.e., spectral walls which form when higher harmonics enter the continuous spectrum. These higher order spectral walls not only deform the soliton trajectories, they also can be observed easily as very intense radiation bursts.

The effects of 17 Beta-Estradiol primed mesenchymal stem cells on the biology of co-cultured neutrophil

ObjectivesMesenchymal stem cells (MSCs) can influence immune effector cells. It is proved that MSCs respond to various Toll-like receptor (TLR) ligands, which could ultimately result in changes in their immunomodulatory effects. Neutrophils play an essential role in the first line defense system and their function can be regulated by MSCs. Estrogen is a female hormone that contributes to sex differences in several immune-related diseases. With regard to the stated facts, this research aims to elucidate the effects of estrogen treatment on the ability of TLR4-primed MSCs to regulate neutrophil functions. MethodsFollowing isolation and characterization, MSCs were stimulated with LPS as a TLR4 ligand and subsequently incubated with different concentrations (0, 10, 20 and 40 nM) of estrogen for 48 hrs. Then, MSCs were co-cultured with neutrophils to investigate the vitality and function of the co-cultured neutrophils. ResultsOur results indicated that TLR4-primed MSCs could decrease the viability and neutral red uptake potential of co-cultured neutrophils. Furthermore, neutrophils co-cultured with TLR4-primed MSCs exhibited a decrease in the respiratory burst intensity after being challenged with opsonized yeast. Interestingly, treating TLR4-primed MSCs with estrogen reversed the observed alterations in neutrophil functions. ConclusionIt appears that estrogen can alter the interaction between MSCs and neutrophils.

Effect of shear wave propagation on estimation of heating distribution by high-intensity focused ultrasound using acoustic radiation force imaging

In a high-intensity focused ultrasound (HIFU) treatment, to predict a HIFU heat source is important for the safety and efficiency. Acoustic radiation force impulse imaging using a HIFU burst is known as a method for the prediction from the distribution of the tissue displacement in a homogeneous tissue. However, the distribution induced by HIFU radiation force expands as the shear wave propagates. In this study, the effect of the shear wave propagation on the estimation of the heat source distribution was investigated by changing the burst duration and intensity of HIFU. The results showed that a shorter HIFU burst provided the higher accuracy of the prediction, improving the spatial resolution. It is concluded that the estimation method has the potential to estimate in a wide range of HIFU energy and requires one to obtain the distribution of displacements immediately after the start of HIFU burst exposure.

Endomorphin-1 affecting innate immune cells in vitro

Opioid peptides belong to one of most studied groups of regulatory peptides due to exerting extremely wide range of biological activities and play an important role in regulating homeostasis. The endogenous opioid system is involved in the functioning of diverse organs and systems, including the immune system. Currently, an immunomodulatory effect of the three major families of opioid peptides such as endorphins, enkephalins, dinorphins has been thoroughly described. Much less data are available about the endomorphin-related immunomodulatory effects. The aim of this work was to assess effects of endomorphin-1 on phagocytosis, production of reactive oxygen species and IL-1β by various subsets of peripheral blood innate immune cells in vitro. The leukocytes of obtained from peripheral venous blood of healthy volunteer donors aged 22 to 40 years were used in the study. Endomorphin-1 was used at concentrations of 10-6, 10-8, 10-10, 10-12 М. Blood leukocyte fraction was isolated from heparinized venous blood settled for 2 hours in a thermostat at 37 °С. The neutrophil fraction was isolated by centrifuging in of Ficoll-Urographin (ρ = 1.077) density gradient placing the upper layer of blood plasma with leukocytes. Assessment of leukocyte oxygen-dependent microbicidal activity was carried out by using the reaction of luminol-dependent chemiluminescence (LZHL) by using opsonized zymosan at concentration of 150 μg/ml; 10-5 M luminol was used to probe reaction magnitude. The separation of the mononuclear cell fraction was carried out by centrifuging in of Ficoll-Urographin (ρ = 1.077) density gradient. The monocyte fraction was isolated mechanically. To assess IL-1β production, mononuclear cells and monocytes were cultured for 24 hours followed by measuring its level with enzyme-linked immunosorbent assay. To evaluate monocytes and neutrophil phagocyte activity, FITC-labeled St.aureus uptake method was used. Statistical processing was performed with one-way ANOVA test and paired LSD criterion for post-hoc comparison, with significance set at p 0.05. It was found that endomorphin-1 reduced leukocyte spontaneous, but not induced production of reactive oxygen species. In the neutrophil fraction, endomorphin-1 did not affect spontaneous oxygen dependent microbicidity and reduced intensity of the respiratory burst in stimulated neutrophils. In addition, it increased the percentage of monocyte phagocytosis and enhanced spontaneous IL-1β production by mononuclear cells. Thus, endomorphin-1 exhibited multidirectional effects on various parameters of innate immunity. Being typical to other groups of regulatory peptides, modality of endomorphin-1 related effects depended on cell fraction and presence of a stimulating cues.

Nucleation mechanisms of iodic acid in clean and polluted coastal regions

In coastal regions, intense bursts of particles are frequently observed with high concentrations of iodine species, especially iodic acid (IA). However, the nucleation mechanisms of IA, especially in polluted environments with high concentrations of sulfuric acid (SA) and ammonia (A), remain to be fully established. By quantum chemical calculations and atmospheric cluster dynamics code (ACDC) simulations, the self-nucleation of IA in clean coastal regions and that influenced by SA and A in polluted coastal regions are investigated. The results indicate that IA can form stable clusters stabilized by halogen bonds and hydrogen bonds through sequential addition of IA, and the self-nucleation of IA can instantly produce large amounts of stable clusters when the concentration of IA is high during low tide, which is consistent with the observation that intense particle bursts were linked to high concentrations of IA in clean coastal regions. Besides, SA and A can stabilize IA clusters by the formation of more halogen bonds and hydrogen bonds as well as proton transfers, and the binary nucleation of IA-SA/A rather than the self-nucleation of IA appears to be the dominant pathways in polluted coastal regions, especially in winter. These new insights are helpful to understand the mechanisms of new particle formation induced by IA in clean and polluted coastal regions.

Change in the Mindset of a Paediatric Exercise Physiologist: A Review of Fifty Years Research.

In this review, the career of a pediatric exercise physiologist (HCGK) is given over a period of almost 50 years. His research was concentrated on the relationship of physical activity (physical education, sport, and daily physical activity) with health and fitness in teenagers in secondary schools. (1) His first experiment was an exercise test on a bicycle ergometer to measure aerobic fitness by estimating physical work capacity at a heart rate of 170 beats/minute (PWC170). (2) Secondly, a randomized control trial (RCT) was performed with an intervention of more intensive physical education (PE) with circuit interval training during three lessons per week over a period of six weeks. (3) Thereafter, a second RCT was performed with an intervention of two extra PE lessons per week over a whole school year. The results of these two RCTs appeared to be small or nonsignificant, probably because the effects were confounded by differences in maturation and the habitual physical activity of these teenagers. (4) Therefore, the scope of the research was changed into the direction of a long-term longitudinal study (the Amsterdam Growth And Health Longitudinal Study). This study included male and female teenagers that were followed over many years to get insight into the individual changes in biological factors (growth, fitness, obesity, hypercholesterolemia, and hypertension) and lifestyle parameters such as nutrition, smoking, alcohol usage, and daily physical activity. With the help of new advanced statistical methods (generalized estimating equations, random coefficient analysis, and autoregression analysis) suitable for longitudinal data, research questions regarding repeated measurements, tracking, or stability were answered. New measurement techniques such as mineral bone density by means of dual-energy X-ray absorptiometry (DEXA) showed that bone can also be influenced by short bursts of mechanical load. This changed his mind: In children and adolescents, not only can daily aerobic exercise of at least 30 to 60 min duration increase the aerobic power of muscles, but very short highly intensive bursts of less than one minute per day can also increase the strength of their bones.

The origin and influence of multi-[formula omitted] signals in positron burst measurement

When an intense positron burst impinges upon a target within nano or picoseconds, a pulse of gamma-rays is created. The gamma-ray pulse contains many annihilation events about the positron burst. A spatial detecting method with a detector array is able to exploit the timing information in such gamma-ray pulses by mounting many independent detector cells of the array spherically around the target. It is possible that multiple annihilated photons in the pulse will fall into the same solid angle of one detector unit, and when one more gamma-ray is detected, a multi-γ signal is generated. In this paper, the principle, the influence factors of the multi-γ signals generation and the effect of multi-γ signals on the time detection of the positron burst are studied by experiment and simulation. Furthermore, a method of eliminating multi-γ signals is also proposed and evaluated. The results can provide support for the design of the detector array applied to measure the positron lifetimes in the burst, such as the detector distance to the source and the method dealing with the multi-γ signals.

Spectropolarimetric Imaging of Metric Type III Solar Radio Bursts

We present low-frequency (80 – 240 MHz) radio observations of circular polarization in 16 isolated type III solar radio bursts using the Murchison Widefield Array (MWA) between August 2014 and November 2015. For most of the bursts, near burst onset, we find on average $9\%$ circular polarization at 80 MHz and $22\%$ at 240 MHz whereas these percentages are $5\%$ and $20\%$ near burst maximum. The polarization fractions are neither constant in time nor uniform over the spatial extents of the bursts. We measure polarization fractions as a function of burst source’s position. On average, near both burst onset and maximum, we find higher polarization near the disk center and lower polarization when the burst source is near the limb. We study total intensity (Stokes $I$), circularly polarized intensity (Stokes $V$), and polarization fraction ($| V| /I$) profiles for type III bursts with and without source motion as a function of position at times when the intensity of bursts is maximum. For the burst event with no source motion, we find symmetric profiles for Stokes $I$, $V$, and $| V| /I$. We find symmetric $I$ and $V$ but asymmetric $| V| /I$ profiles for burst events which have source motion. We argue that this is due to the fundamental emission at the front of a type III electron beam and motion of the burst source. We then perform spectropolarimetric imaging studies of moving burst sources and analyze their motion. At burst onset, we obtain relatively higher polarization fractions, which is considered to be due to a large contribution from fundamental plasma emission at the front of the beam. At burst maximum, the polarization fraction is lower due to the combination of fundamental and harmonic components. After peak intensity, the emission is dominated again by the fundamental component that decays until the end of a burst with lesser polarization fraction than earlier. We argue that the fundamental radiation that decays over time after peak burst intensity is strongly scattered. This pattern of fundamental, fundamental and harmonic, and then fundamental emission with time at each frequency is consistent with the interpretations of Dulk, Suzuki, and Sheridan (Astron. Astrophys.130, 39, 1984), Robinson, Cairns, and Willes (Astrophys. J.422, 870, 1994), and Robinson and Cairns (Solar Phys.181, 363, 1998). We propose that scattering effects can be a viable reason for low polarization fractions in type III events. Finally, we investigate the variations of the decay time ($t_{d}$) for three events with frequency ($f$), finding that $t_{d} \propto f^{-2.0\pm 0.1}$ and decreases more rapidly with increasing $f$ compared with previous lower-frequency observations ($t_{d} \propto f^{-1.1\pm 0.1}$). This is interpreted in terms of radial variations of the turbulence properties.

The FIREBIRD-II CubeSat mission: Focused investigations of relativistic electron burst intensity, range, and dynamics.

FIREBIRD-II is a National Science Foundation funded CubeSat mission designed to study the scale size and energy spectrum of relativistic electron microbursts. The mission consists of two identical 1.5 U CubeSats in a low earth polar orbit, each with two solid state detectors that differ only in the size of their geometric factors and fields of view. Having two spacecraft in close orbit allows the scale size of microbursts to be investigated through the intra-spacecraft separation when microbursts are observed simultaneously on each unit. Each detector returns high cadence (10 s of ms) measurements of the electron population from 200 keV to >1 MeV across six energy channels. The energy channels were selected to fill a gap in the observations of the Heavy Ion Large Telescope instrument on the Solar, Anomalous, and Magnetospheric Particle Explorer. FIREBIRD-II has been in orbit for 5 years and continues to return high quality data. After the first month in orbit, the spacecraft had separated beyond the expected scale size of microbursts, so the focus has shifted toward conjunctions with other magnetospheric missions. FIREBIRD-II has addressed all of its primary science objectives, and its long lifetime and focus on conjunctions has enabled additional science beyond the scope of the original mission. This paper presents a brief history of the FIREBIRD mission's science goals, followed by a description of the instrument and spacecraft. The data products are then discussed along with some caveats necessary for proper use of the data.

Associations between circulating levels of natural antibodies, total serum immunoglobulins, and polymorphonuclear leukocyte function in early postpartum dairy cows

The objective of this study was to investigate the associations between natural antibodies (NAbs) and total serum immunoglobulins (Igs) concentrations (both from IgG and IgM isotypes), with variables of polymorphonuclear leukocytes (PMN) function of dairy cows in the early postpartum period. Seventy-five healthy postpartum dairy cows at 2 ± 1 days in milk were enrolled in a cross-sectional study. Natural and total antibodies in serum samples were measured by ELISA. Flow cytometry was used to determine the phagocytosis and oxidative burst capacities of PMN and the quantification of the adhesion molecule l-selectin. Leukocyte count and differentials, and serum haptoglobin were also measured. A positive correlation between NAbsIgM and total serum IgM and between NAbsIgM and NAbsIgG were found. Before performing the associations between circulating Igs concentrations and PMN function variables, cows were categorized into having low, medium or high circulating antibodies based on their NAbs and total Igs serum concentrations. None of the PMN variables assessed differed between low, medium, and high cows for both NAbsIgM and NAbsIgG. While associations between PMNs function and total IgG were not observed, some associations between total IgM concentrations and PMN activity were found. Cows with high serum IgM had greater phagocytic activity compared to cows in the low IgM group. Finally, the proportion of PMN that performed oxidative burst and PMN surface expression of l-selectin intensity was greater in high total IgM group when compared to medium and low groups. In conclusion, association between NAbs, and PMN activity variables were not observed, but total serum IgM was associated to some PMN function variables in early post-partum dairy cows.

The Discharge Preceding the Intense Reillumination in Positive Leader Steps Under the Slow Varying Ambient Electric Field

AbstractUnder the slow varying ambient electric field, positive leader propagation exhibits steps characterized by intense reilluminations and abrupt elongations. These steps are currently not well understood. In this work, we investigate these steps in laboratory atmospheric discharges, using a high‐speed video camera and a synchronized electrical parameter measurement system. The discharge, emitting weak light and preceding the intense reillumination, is discovered. This finding suggests that the leader channel actually restarts and extends forward before the intense reillumination, which deepens our understanding of the dynamic process of the positive leader step. The discharge before the intense reillumination contributes to the corona inception from the electrode, leading to the intense reillumination of the leader channel and the emergence of an intense corona streamer burst from the leader tip.