Collisionless astrophysical plasmas are correlated systems in which particles are often not in thermal equilibrium and can be characterized by power‐law distributions. The kappa distribution ...function, which is a more generalized form of the power‐law function, is often used to describe acceleration and production of high‐energy particles in different space plasma environments. The spectra of particles in the Earth's plasma sheet constructed using Time History of Events and Mesoscale Interactions during Substorms data show that the kappa index exhibits a strong dawn‐dusk asymmetry and a clear dependence on both geocentric distance and magnetic local time. Furthermore, statistics indicate that spectrum hardening, or softening is expected during geomagnetically disturbed periods. To understand how the shape of the particle distribution function evolves and what factors affect the kappa index, we simulate earthward plasma transport using a kinetic drift model. In the simulations, the plasma distribution is initially considered to be a kappa function with κ=6 $\kappa =6$. However, with time, both protons and electrons' distribution functions evolve and deviate from their initial shapes. We demonstrate that by implementing transient low‐entropy plasma injections, the Rice Convection Model average distribution functions can reasonably agree with observations. We also discuss the relative impact of gradient/curvature drift, particle loss, and bubble injections, based on controlled numerical experiments.
Plain Language Summary
In the magnetosphere of the Earth, Coulomb collisions are rare, so particle populations are believed to be far from thermal equilibrium and cannot be characterized by a Maxwellian distribution function. During quiet and disturbed geomagnetic conditions, the so‐called kappa distribution can be used to describe the emergence of high‐energy plasma components. The study of plausible relaxation or acceleration mechanisms in which particle distribution approaches or deviates from the Maxwellian distribution is therefore an important subject that is not yet well understood. Using a many‐fluid numerical model, this study analyzes the development, evolution, and dependence of the thermodynamics of plasma in the inner and middle magnetospheres. Using this model, we examine the average thermodynamic properties of plasma populations in the Earth's plasma sheet under the influence of low‐density plasma flow injections (i.e., plasma bubbles), during which the geomagnetic conditions are expected to be perturbed. By comparing satellite data to our simulation results, we confirm that plasma bubbles (a) allow the plasma sheet's thermodynamics to be modeled more realistically, and (b) explain the tendency of spectra to relax or accelerate as a result of the mixing of different groups of particles associated with energy‐dependent magnetic drifts.
Key Points
Multiple random bubble injections affect the spectral shape of plasma sheet particles
Radial‐ and magnetic local time‐dependent spectral hardening and softening occur, implying a variation of the κ indices
The κ indices obtained in the Rice Convection Model simulation are in reasonable agreement with analyses using Time History of Events and Mesoscale Interactions during Substorms data
Providing a link between magnetars and radio pulsars, high-magnetic-field neutron stars are ideal targets to investigate how bursting/magnetospheric activity and braking torque variations are ...connected to rotational glitches. The last spin-up glitch of the highly magnetized pulsar J1119-6127 back in 2007 was the first glitch in a rotationally powered radio pulsar to be accompanied by radiative changes. Moreover, it was followed by an uncommon glitch relaxation that resulted in a smaller spin-down rate relative to the prediction of the pre-glitch timing model. Here, we present four years of new radio timing observations and analyse the total of 16 years of timing data for this source. The new data uncover an ongoing evolution of the spin-down rate, thereby allowing us to exclude permanent changes in the external or internal torque as a standalone cause of the peculiar features of the glitch recovery. Furthermore, no additional variations of the radio pulse profile are detected, strengthening the association of the previously observed transient emission features with the glitching activity. A self-consistent measurement of the braking index yields a value n ... 2.7, indicating a trajectory in the ... plane inclined towards the magnetars. Such a potential evolutionary link might be strengthened by a, possibly permanent, reduction of ~15 per cent in n at the epoch of the 2007 glitch. (ProQuest: ... denotes formulae/symbols omitted.)
Abstract
The long-period, highly eccentric Wolf-Rayet star binary system WR 140 has exceptionally well-determined orbital and stellar parameters. Bright, variable X-ray emission is generated in ...shocks produced by the collision of the winds of the WC7pd+O5.5fc component stars. We discuss the variations in the context of the colliding-wind model using broadband spectrometry from the RXTE, Swift, and NICER observatories obtained over 20 yr and nearly 1000 observations through three consecutive 7.94 yr orbits, including three periastron passages. The X-ray luminosity varies as expected with the inverse of the stellar separation over most of the orbit; departures near periastron are produced when cooling shifts to excess optical emission in C
iii
λ
5696 in particular. We use X-ray absorption to estimate mass-loss rates for both stars and to constrain the system morphology. The absorption maximum coincides closely with the inferior conjunction of the WC star and provides evidence of the ion-reflection mechanism that underlies the formation of collisionless shocks governed by magnetic fields probably generated by the Weibel instability. Comparisons with
K
-band emission and He
i
λ
10830 absorption show that both are correlated after periastron with the asymmetric X-ray absorption. Dust appears within a few days of periastron, suggesting formation within shocked gas near the stagnation point. The X-ray flares seen in
η
Car have not occurred in WR 140, suggesting the absence of large-scale wind inhomogeneities. Relatively constant soft emission revealed during the X-ray minimum is probably not from recombining plasma entrained in outflowing shocked gas.
In porcine placenta, abnormal development of the placental vasculature leads to placental insufficiency. The aim of this study was to determine the mRNA expression of angiogenic growth factors and to ...determine the vascular characteristics in placenta at day 40 of pig gestation. Samples were collected from maternal‐chorioallantoic interface (n = 21) for the measurement of mRNA expression of VEGFA, ANGPT1, ANGPT2, FGF2 and its receptors KDR, TEK, FGFR1IIIc, FGFR2IIIb respectively, and for immunohistochemistry analysis of CD31 and VEGFA. Immunohistochemical analysis of CD31 and VEGFA, morphometric measurement of blood vessels, high‐resolution light microscopy and transmission electron microscopy were performed. Capillary area density, number of blood vessels and capillary area were significantly higher on the maternal side than on the fetal side (p < .05). The ultrastructural finding of blood vessels demonstrates close contact with the trophoblastic epithelium. The relative mRNA expression of VEGFA and its receptor KDR was higher compared with the other angiogenic genes. In conclusion, a high mRNA expression of VEGFA and its receptor KDR added to the immunohistochemical results suggest a potential role of these genes in this pathway associated with an increase in the density of the capillary area on the maternal side and a reduction in the hemotrophic diffusion distance at the interface for nutrient exchange.
Cocoa bean shells (CBS) are a by-product of the cocoa bean processing industry. They represent 12-20 wt% of dry cocoa beans, after having been separated from these by a roasting process. CBS often ...end up as a waste product which contains around 34 wt% of cellulose. The transformation of this waste into valuable and marketable products would help to improve waste disposal. Indeed, the large annual production of this waste makes it a sustainable and renewable bio-source for the production of chemicals and fibers for advanced applications. In this work, new cellulose microfibrils (CMFs) with a tendril helical morphology and highly hydrated gel-like behavior were successfully extracted from CBS waste using a controlled chemical extraction process. During this study, several physico-chemical characterizations were carried out in order to identify the properties of each of the products at different stages of treatment. Microscopic observations show that the extracted CMFs have a tendril helical shape like climbing plant tendrils. Due to this special morphology, the extracted CMFs show a highly hydrated state forming a gel network without additional modifications. The as-extracted CMFs were used as adsorbent material for the removal of methylene blue from concentrated aqueous solution, as an application to wastewater treatment for the removal of basic dyes. Swelling properties, adsorption kinetics and isotherms were carried out in batch experiments. The results indicated that the CMFs have a high swelling capacity (190%). The pseudo second order model can be effectively used to evaluate the adsorption kinetics and the adsorption isotherms can also be described well by the Langmuir isotherm model with a maximum adsorption capacity of 381.68 mg g
−1
. Thus, the as-extracted CMFs with unique characteristics have the potential to be used as efficient adsorbent material for the removal of different cationic dyes from industrial wastewater.
Cocoa bean shells are a by-product of the cocoa bean processing industry. Highly hydrated cellulose microfibrils with special morphology were obtained from this by-product and used as adsorbent material for waste water treatment.
Context.
Glitches are sudden increases in the rotation rate
ν
of neutron stars, which are thought to be driven by the neutron superfluid inside the star. The Vela pulsar presents a comparatively high ...rate of glitches, with 21 events reported since observations began in 1968. These are amongst the largest known glitches (17 of them have sizes Δ
ν
/
ν
≥ 10
−6
) and exhibit very similar characteristics. This similarity, combined with the regularity with which large glitches occur, has turned Vela into an archetype of this type of glitching behaviour. The properties of its smallest glitches, on the other hand, are not clearly established.
Aims.
We explore the population of small-amplitude, rapid rotational changes in the Vela pulsar and determine the rate of occurrence and sizes of its smallest glitches. This will help advance our understanding of the actual distribution of glitch sizes and inter-glitch waiting times in this pulsar, which has implications for theoretical models of the glitch mechanism.
Methods.
High-cadence observations of the Vela pulsar were taken between 1981 and 2005 at the Mount Pleasant Radio Observatory. An automated systematic search was carried out that investigated whether a significant change of spin frequency
ν
and/or the spin-down rate
ν
̇ takes place at any given time.
Results.
We find two glitches that have not been reported before, with respective sizes Δ
ν
/
ν
of (5.55 ± 0.03) × 10
−9
and (38 ± 4) × 10
−9
. The latter is followed by an exponential-like recovery with a characteristic timescale of 31 d. In addition to these two glitch events, our study reveals numerous events of all possible signatures (i.e. combinations of Δ
ν
and Δ
ν
̇ signs), all of them small with |Δ
ν
|/
ν
< 10
−9
, which contribute to the Vela timing noise.
Conclusions.
The Vela pulsar presents an under-abundance of small glitches compared to many other glitching pulsars, which appears genuine and not a result of observational biases. In addition to typical glitches, the smooth spin-down of the pulsar is also affected by an almost continuous activity that can be partially characterised by small step-like changes in
ν
,
ν
̇ or both. Simulations indicate that a continuous wandering of the rotational phase, following a red spectrum, could mimic such step-like changes in the timing residuals.
Breast cancer ranks first in incidence and mortality in working age women. Cancer initiation and progression relies on accumulation of genetic and epigenetic aberrations that alter cellular ...processes, among them, epithelial to mesenchymal transition (EMT) denotes particularly aggressive neoplasias given its capacity to invade and metastasize. Several microRNAs (miRNA) have been found able to regulate gene expression at the core of EMT. In this study, the Affymetrix CytoScan HD array was used to analyze three different primary tumor cell isolates from Mexican breast cancer patients. We found an amplification in band 22q11.2 shared by the three samples, in the region that encodes miRNA-650. Overexpression of this miRNA has been associated with downregulation of tumor suppressors ING4 and NDRG2, which have been implicated in cancer progression. Using the Pathway Linker platform the ING4 and NDRG2 interaction networks showed a significant association with signaling pathways commonly deregulated in cancer. Also, several studies support their participation in the EMT. Supporting the latter, we found that the three primary isolates were E-cadherin negative, vimentin positive, presented a cancer stem cell-like phenotype CD44+CD24-/low and were invasive in Transwell invasion assays. This evidence suggests that the gain of region 22q11.2 contributes to trigger EMT. This is the first evidence linking miR-650 and breast cancer.
Background and Purpose
Olcegepant (BIBN4096BS) is a selective non‐peptide CGRP receptor antagonist with acute antimigraine properties. Since systemic vascular tone is modulated by perivascular ...(primary sensory CGRPergic and sympathetic) nerves, this randomized study investigated in pithed rats the effect of acute i.v. treatment with olcegepant on the neurogenic and non‐neurogenic: (i) CGRPergic vasodepressor responses; and (ii) noradrenergic vasopressor responses. The pithed rat is an experimental model predictive of systemic (cardio) vascular side effects.
Experimental Approach
Seventy‐five male Wistar rats (divided into 15 groups, n = 5 each) were pithed, artificially ventilated and prepared for: (i) spinal stimulation (T9–T12; 0.56–5.6 Hz) of the sensory CGRPergic vasodepressor outflow or i.v. bolus injections (0.1–1 μg·kg−1) of α‐CGRP, substance P or acetylcholine, which induced frequency‐dependent or dose‐dependent vasodepressor responses; or (ii) spinal stimulation (T7–T9; 0.03–3 Hz) of the sympathetic vasopressor outflow or i.v. bolus injections (0.03–3 μg·kg−1) of noradrenaline, which produced frequency‐dependent or dose‐dependent vasopressor responses.
Key Results
Olcegepant (1000 and 3000 μg·kg−1, i.v.) dose‐dependently blocked the vasodepressor responses to sensory nerve stimulation or i.v. α‐CGRP, without affecting those to substance P or acetylcholine. Whereas it potentiated the vasopressor responses to sympathetic nerve stimulation or i.v. noradrenaline.
Conclusions and Implications
Olcegepant (i.v.) selectively blocked the neurogenic and non‐neurogenic CGRPergic vasodepressor responses. This blockade by olcegepant potentiated the neurogenic and non‐neurogenic noradrenergic vasopressor responses in pithed rats, an effect that might result in an increased vascular resistance and, consequently, in a prohypertensive action.
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