Erratum: In situ Signature of Cyclotron Resonant Heating in the Solar Wind [Phys. Rev. Lett. 129, 165101 (2022)]

This corrects the article DOI: 10.1103/PhysRevLett.129.165101.

Three-Dimensional Energy Transfer in Space Plasma Turbulence from Multipoint Measurement

A novel multispacecraft technique applied to Magnetospheric Multiscale Mission data in the Earth's magnetosheath enables evaluation of the energy cascade rate from the full Yaglom's equation. The method differs from existing approaches in that it (i) is inherently three-dimensional, (ii) provides a statistically significant number of estimates from a single data stream, and (iii) allows visualization of energy flux in turbulent plasmas. This new "lag polyhedral derivative ensemble" technique exploits ensembles of tetrahedra in lag space and established curlometerlike algorithms.

Research interests, experience, and training of Community Health Workers: a mixed Method Approach

The Affordable Care Act includes a call for community health care workers (CHWs) to be integrated into health care delivery systems to improve health care quality. In recent years, there have been increasing calls for community-based participatory research (CBPR) and patient-centered outcomes research (PCOR), as such types of research hold much potential for identifying interventions to reduce health and health care disparities. Yet, little is known about the research training, knowledge, experience, and even interest of CHWs in these types of research or in health research in general (HR). Thus, the purposes of this study include determining if there are differences between participating CHWs (N = 202) in their levels of training, knowledge, experience, and interest in relation to CBPR, PCOR and HR. Findings suggest that certified CHWs, as compared to non-certified CHWs, have significantly higher knowledge levels across all three types of research (β = 1.3, p = .007). Additionally, participants had significantly higher knowledge of HR compared to CBPR (β = 0.5, p = .015), but not higher than their knowledge of PCOR (p > .5). Qualitative data analyses performed to determine research areas of interest among the participating CHWs resulted in eighteen major research interest themes. Examples of these major themes are chronic illness (n = 95), health promotion (n = 39), healthcare services and administration (n = 30), mental health (n = 29), and research evaluation and methodology (n = 26). Together, the findings suggest that though CHWs have an interest in a wide range of health research areas, they could benefit from research trainings tailored to their responsibilities and interests.

In Situ Signature of Cyclotron Resonant Heating in the Solar Wind

The dissipation of magnetized turbulence is an important paradigm for describing heating and energy transfer in astrophysical environments such as the solar corona and wind; however, the specific collisionless processes behind dissipation and heating remain relatively unconstrained by measurements. Remote sensing observations have suggested the presence of strong temperature anisotropy in the solar corona consistent with cyclotron resonant heating. In the solar wind, in situ magnetic field measurements reveal the presence of cyclotron waves, while measured ion velocity distribution functions have hinted at the active presence of cyclotron resonance. Here, we present Parker Solar Probe observations that connect the presence of ion-cyclotron waves directly to signatures of resonant damping in observed proton-velocity distributions using the framework of quasilinear theory. We show that the quasilinear evolution of the observed distribution functions should absorb the observed cyclotron wave population with a heating rate of 10^{-14}  W/m^{3}, indicating significant heating of the solar wind.

Parker Solar Probe Enters the Magnetically Dominated Solar Corona

The high temperatures and strong magnetic fields of the solar corona form streams of solar wind that expand through the Solar System into interstellar space. At 09:33 UT on 28 April 2021 Parker Solar Probe entered the magnetized atmosphere of the Sun 13 million km above the photosphere, crossing below the Alfvén critical surface for five hours into plasma in casual contact with the Sun with an Alfvén Mach number of 0.79 and magnetic pressure dominating both ion and electron pressure. The spectrum of turbulence below the Alfvén critical surface is reported. Magnetic mapping suggests the region was a steady flow emerging on rapidly expanding coronal magnetic field lines lying above a pseudostreamer. The sub-Alfvénic nature of the flow may be due to suppressed magnetic reconnection at the base of the pseudostreamer, as evidenced by unusually low densities in this region and the magnetic mapping.

A Case for Electron-Astrophysics

The smallest characteristic scales, at which electron dynamics determines the plasma behaviour, are the next frontier in space and astrophysical plasma research. The analysis of astrophysical processes at these scales lies at the heart of the research theme of electron-astrophysics. Electron scales are the ultimate bottleneck for dissipation of plasma turbulence, which is a fundamental process not understood in the electron-kinetic regime. In addition, plasma electrons often play an important role for the spatial transfer of thermal energy due to the high heat flux associated with their velocity distribution. The regulation of this electron heat flux is likewise not understood. By focussing on these and other fundamental electron processes, the research theme of electron-astrophysics links outstanding science questions of great importance to the fields of space physics, astrophysics, and laboratory plasma physics. In this White Paper, submitted to ESA in response to the Voyage 2050 call, we review a selection of these outstanding questions, discuss their importance, and present a roadmap for answering them through novel space-mission concepts.

How Alfvén waves energize the solar wind: heat vs work

A growing body of evidence suggests that the solar wind is powered to a large extent by an Alfvén-wave (AW) energy flux. AWs energize the solar wind via two mechanisms: heating and work. We use high-resolution direct numerical simulations of reflection-driven AW turbulence (RDAWT) in a fast-solar-wind stream emanating from a coronal hole to investigate both mechanisms. In particular, we compute the fraction of the AW power at the coronal base (P _AWb) that is transferred to solar-wind particles via heating between the coronal base and heliocentric distance r, which we denote χ _H(r), and the fraction that is transferred via work, which we denote χ _W(r). We find that χ _W(r _A) ranges from 0.15 to 0.3, where r _A is the Alfvén critical point. This value is small compared to one because the Alfvén speed v _A exceeds the outflow velocity U at r < r _A, so the AWs race through the plasma without doing much work. At r > r _A, where v _A < U, the AWs are in an approximate sense "stuck to the plasma," which helps them do pressure work as the plasma expands. However, much of the AW power has dissipated by the time the AWs reach r = r _A, so the total rate at which AWs do work on the plasma at r > r _A is a modest fraction of P _AWb. We find that heating is more effective than work at r < r _A, with χ _H(r _A) ranging from 0.5 to 0.7. The reason that χ _H ⩾ 0.5 in our simulations is that an appreciable fraction of the local AW power dissipates within each Alfvén-speed scale height in RDAWT, and there are a few Alfvén-speed scale heights between the coronal base and r _A. A given amount of heating produces more magnetic moment in regions of weaker magnetic field. Thus, paradoxically, the average proton magnetic moment increases robustly with increasing r at r > r _A, even though the total rate at which AW energy is transferred to particles at r > r _A is a small fraction of P _AWb.

The multi-scale nature of the solar wind

The solar wind is a magnetized plasma and as such exhibits collective plasma behavior associated with its characteristic spatial and temporal scales. The characteristic length scales include the size of the heliosphere, the collisional mean free paths of all species, their inertial lengths, their gyration radii, and their Debye lengths. The characteristic timescales include the expansion time, the collision times, and the periods associated with gyration, waves, and oscillations. We review the past and present research into the multi-scale nature of the solar wind based on in-situ spacecraft measurements and plasma theory. We emphasize that couplings of processes across scales are important for the global dynamics and thermodynamics of the solar wind. We describe methods to measure in-situ properties of particles and fields. We then discuss the role of expansion effects, non-equilibrium distribution functions, collisions, waves, turbulence, and kinetic microinstabilities for the multi-scale plasma evolution.

Alfvénic velocity spikes and rotational flows in the near-Sun solar wind

The prediction of a supersonic solar wind¹ was first confirmed by spacecraft near Earth^2,3 and later by spacecraft at heliocentric distances as small as 62 solar radii⁴. These missions showed that plasma accelerates as it emerges from the corona, aided by unidentified processes that transport energy outwards from the Sun before depositing it in the wind. Alfvénic fluctuations are a promising candidate for such a process because they are seen in the corona and solar wind and contain considerable energy^5-7. Magnetic tension forces the corona to co-rotate with the Sun, but any residual rotation far from the Sun reported until now has been much smaller than the amplitude of waves and deflections from interacting wind streams⁸. Here we report observations of solar-wind plasma at heliocentric distances of about 35 solar radii^9-11, well within the distance at which stream interactions become important. We find that Alfvén waves organize into structured velocity spikes with duration of up to minutes, which are associated with propagating S-like bends in the magnetic-field lines. We detect an increasing rotational component to the flow velocity of the solar wind around the Sun, peaking at 35 to 50 kilometres per second-considerably above the amplitude of the waves. These flows exceed classical velocity predictions of a few kilometres per second, challenging models of circulation in the corona and calling into question our understanding of how stars lose angular momentum and spin down as they age^12-14.

Evidence for electron Landau damping in space plasma turbulence

How turbulent energy is dissipated in weakly collisional space and astrophysical plasmas is a major open question. Here, we present the application of a field-particle correlation technique to directly measure the transfer of energy between the turbulent electromagnetic field and electrons in the Earth's magnetosheath, the region of solar wind downstream of the Earth's bow shock. The measurement of the secular energy transfer from the parallel electric field as a function of electron velocity shows a signature consistent with Landau damping. This signature is coherent over time, close to the predicted resonant velocity, similar to that seen in kinetic Alfven turbulence simulations, and disappears under phase randomisation. This suggests that electron Landau damping could play a significant role in turbulent plasma heating, and that the technique is a valuable tool for determining the particle energisation processes operating in space and astrophysical plasmas.

Stochastic proton heating by kinetic-Alfvén-wave turbulence in moderately high-β plasmas

Stochastic heating refers to an increase in the average magnetic moment of charged particles interacting with electromagnetic fluctuations whose frequencies are much smaller than the particles' cyclotron frequencies. This type of heating arises when the amplitude of the gyroscale fluctuations exceeds a certain threshold, causing particle orbits in the plane perpendicular to the magnetic field to become stochastic rather than nearly periodic. We consider the stochastic heating of protons by Alfvén-wave (AW) and kinetic-Alfvén-wave (KAW) turbulence, which may make an important contribution to the heating of the solar wind. Using phenomenological arguments, we derive the stochastic-proton-heating rate in plasmas in which β _p ∼ 1 - 30, where β _p is the ratio of the proton pressure to the magnetic pressure. (We do not consider the β _p ≳ 30 regime, in which KAWs at the proton gyroscale become non-propagating.) We test our formula for the stochastic-heating rate by numerically tracking test-particle protons interacting with a spectrum of randomly phased AWs and KAWs. Previous studies have demonstrated that at β _p ≲1, particles are energized primarily by time variations in the electrostatic potential and thermal-proton gyro-orbits are stochasticized primarily by gyroscale fluctuations in the electrostatic potential. In contrast, at β _p ≳ 1, particles are energized primarily by the solenoidal component of the electric field and thermal-proton gyro-orbits are stochasticized primarily by gyroscale fluctuations in the magnetic field.

Majority of Solar Wind Intervals Support Ion-Driven Instabilities

We perform a statistical assessment of solar wind stability at 1 AU against ion sources of free energy using Nyquist's instability criterion. In contrast to typically employed threshold models which consider a single free-energy source, this method includes the effects of proton and He^{2+} temperature anisotropy with respect to the background magnetic field as well as relative drifts between the proton core, proton beam, and He^{2+} components on stability. Of 309 randomly selected spectra from the Wind spacecraft, 53.7% are unstable when the ion components are modeled as drifting bi-Maxwellians; only 4.5% of the spectra are unstable to long-wavelength instabilities. A majority of the instabilities occur for spectra where a proton beam is resolved. Nearly all observed instabilities have growth rates γ slower than instrumental and ion-kinetic-scale timescales. Unstable spectra are associated with relatively large He^{2+} drift speeds and/or a departure of the core proton temperature from isotropy; other parametric dependencies of unstable spectra are also identified.

Growth factors in expressed prostatic fluid from men with prostate cancer, BPH, and clinically normal prostates

BACKGROUND

Although growth factors such as epidermal growth factor (EGF), transforming growth factor (TGF)-alpha, and TGF-beta are important regulators of prostate cell growth in vitro and in animal models, evidence to support their role in human prostate cancer development remains sparse. We previously showed that men without prostate cancer have concentrations of EGF and TGF-alpha in expressed prostatic fluid (EPF) that are individually distinct and stable over time. This study addressed whether growth factor levels in EPF are associated with the presence or progression of prostate cancer.

METHODS

We measured levels of immunoreactive EGF, TGF-alpha, and TGF-beta1 in stored EPF samples from three age-matched groups: 19 men with untreated, histologically diagnosed prostate cancer (CaP), 38 with benign prostate hyperplasia (BPH), and 19 with normal prostate glands (NPD).

RESULTS

Median TGF-alpha was lower in the BPH group (0.45 ng/ml) than in either CaP (0.63 ng/ml) or NPD (0.58 ng/ml) groups (P = 0.03 and 0.12, respectively). For EGF, the median was lowest in the CaP group and highest in the NPD group (92.5 ng/ml vs. 175.5 ng/ml, P = 0.006). For TGF-beta1, the median level in CaP was 2.7 times higher than the median level among all controls (6.65 ng/ml vs. 2.46 ng/ml, P = 0.002). Growth factor levels were not associated with tumor stage or Gleason score. However, the single case with distant metastases had TGF-beta1 levels 23-fold higher than the CaP median.

CONCLUSIONS

The results suggest that at the time of CaP diagnosis, EGF levels in EPF are significantly lower, and TGF-beta1 levels significantly higher, than normal. Marked overexpression of TGF-beta1 in advanced CaP might be reflected in extremely high EPF levels.

Molecular comparison of the mitochondrial and cytoplasmic hsp70 of Trypanosoma cruzi, Trypanosoma brucei and Leishmania major

We compared the expression and localization of the mitochondrial and cytoplasmic hsp70 of the protozoans Trypanosoma cruzi, Trypanosoma brucei and Leishmania major. The mitochondrial protein is encoded by multiple mRNA in all species, while the cytoplasmic protein is encoded by a single mRNA. In all three species, the mitochondrial hsp70 is concentrated in the kinetoplast, a submitochondrial structure that houses the unusual DNA (kDNA) that characterizes this group of organisms, while the cytoplasmic protein is distributed throughout the cell. These results suggest that, in all kinetoplastid species, mt-hsp70 has a specific function in kDNA biology, possibly in the processes of kDNA replication, RNA editing or kinetoplast structure.

The distal region of the long arm of human chromosome 1 carries tumor suppressor activity for a human fibrosarcoma line

Loss or inactivation of tumor suppressor genes has been implicated by indirect methods in the etiology of most human cancers. In the functional studies presented here, tumor suppressors on human chromosome 1 were investigated using microcell-mediated chromosome transfer. Translocated chromosomes from normal human cells representing most of 1q, or all of 1p and a small portion of 1q translocated onto the region of the X chromosome encoding HPRT, were transferred into human fibrosarcoma cell line HT1080. Analysis of HT1080 microcell hybrids showed a tumor suppressor activity associated with 1q. All HT1080 cells carrying transferred 1q in a ratio of 1:1 with the HT1080 genome showed a more flattened morphology and a reduced ability to form tumors in nude mice compared to parental HT1080 cells. Diploid HT1080 cells carrying a single extra 1q also had a longer population doubling time and showed a loss of ability to clone in soft agar. Tumors arose from 1q-containing clones with a longer latency period, and a large majority of the cells comprising these tumors had lost the transferred chromosome. These results indicate the presence on chromosome 1q23-qter of a tumor suppressor gene or genes that can act to suppress transformation of a human fibrosarcoma cell line.

Studies on an acquired inhibition of factor VIII induced by penicillin allergy

An inhibitor of antihaemophilic globulin has been found in association with penicillin allergy. Inhibitor activity was detected after a severe reaction of penicillin. Neutralization studies showed the activity resided in an IgG globulin with kappa light chains. Experiments with insolubilized gammaglobulin demonstrated that the activity of the inhibitor was found in a specific penicillin antibody.