2,248 research outputs found
Dropouts of Fully Stripped Ions in the Solar Wind: A Diagnostic for Wave Heating versus Reconnection
The SWICS instrument aboard the ACE satellite has detected frequent intervals
in the slow solar wind and interplanetary coronal mass ejections (ICMEs) in
which C6+ and other fully stripped ions are strongly depleted, though the
ionization states of elements such as Si and Fe indicate that those ions should
be present. It has been suggested that these outlier or dropout events can be
explained by the resonant cyclotron heating process, because these ions all
have the same cyclotron frequency as He2+. We investigate the region in the
corona where these outlier events form. It must be above the ionization
freeze-in height and the transition to collisionless plasma conditions, but low
enough that the wind still feels the effects of solar gravity. We suggest that
the dropout events correspond to relatively dense blobs of gas in which the
heating is reduced because local variations in the Alfven speed change the
reflection of Alfven waves and the turbulent cascade. As a result, the wave
power at the cyclotron frequency of the fully stripped ions is absorbed by He2+
and may not be able to heat the other fully-stripped ions enough to overcome
solar gravity. If this picture is borne out, it may help to discriminate
between resonant cyclotron heating and stochastic heating models of the solar
wind
Tawney and the third way
From the 1920s to the 1950s R. H. Tawney was the most influential socialist thinker in Britain. He articulated an ethical socialism at odds with powerful statist and mechanistic traditions in British socialist thinking. Tawney's work is thus an important antecedent to third way thinking. Tawney's religiously-based critique of the morality of capitalism was combined with a concern for detailed institutional reform, challenging simple dichotomies between public and private ownership. He began a debate about democratizing the enterprise and corporate governance though his efforts fell on stony ground. Conversely, Tawney's moralism informed a whole-hearted condemnation of market forces in tension with both his concern with institutional reform and modern third way thought. Unfortunately, he refused to engage seriously with emergent welfare economics which for many social democrats promised a more nuanced understanding of the limits of market forces. Tawney's legacy is a complex one, whose various elements form a vital part of the intellectual background to current third way thinking
On the possibility of magneto-structural correlations: detailed studies of di-nickel carboxylate complexes
A series of water-bridged dinickel complexes of the general formula [Ni<sub>2</sub>(μ<sub>2</sub>-OH<sub>2</sub>)(μ2-
O<sub>2</sub>C<sup>t</sup>Bu)<sub>2</sub>(O<sub>2</sub>C<sup>t</sup>Bu)2(L)(L0)] (L = HO<sub>2</sub>C<sup>t</sup>Bu, L0 = HO<sub>2</sub>C<sup>t</sup>Bu (1), pyridine (2),
3-methylpyridine (4); L = L0 = pyridine (3), 3-methylpyridine (5)) has been synthesized
and structurally characterized by X-ray crystallography. The magnetic properties
have been probed by magnetometry and EPR spectroscopy, and detailed measurements
show that the axial zero-field splitting, D, of the nickel(ii) ions is on the same order as
the isotropic exchange interaction, J, between the nickel sites. The isotropic exchange
interaction can be related to the angle between the nickel centers and the bridging
water molecule, while the magnitude of D can be related to the coordination sphere at
the nickel sites
Purcell-Enhanced Single Photons at Telecom Wavelengths from a Quantum Dot in a Photonic Crystal Cavity
Quantum dots are promising candidates for telecom single photon sources due
to their tunable emission across the different low-loss telecommunications
bands, making them compatible with existing fiber networks. Their suitability
for integration into photonic structures allows for enhanced brightness through
the Purcell effect, supporting efficient quantum communication technologies.
Our work focuses on InAs/InP QDs created via droplet epitaxy MOVPE to operate
within the telecoms C-band. We observe a short radiative lifetime of 340 ps,
arising from a Purcell factor of 5, owing to interaction of the QD within a
low-mode-volume photonic crystal cavity. Through in-situ control of the sample
temperature, we show both temperature tuning of the QD's emission wavelength
and a preserved single photon emission purity at temperatures up to 25K. These
findings suggest the viability of QD-based, cryogen-free, C-band single photon
sources, supporting applicability in quantum communication technologies
Activating Fc γ receptors contribute to the antitumor activities of immunoregulatory receptor-targeting antibodies
Fc γ receptor (FcγR) coengagement can facilitate antibody-mediated receptor activation in target cells. In particular, agonistic antibodies that target tumor necrosis factor receptor (TNFR) family members have shown dependence on expression of the inhibitory FcγR, FcγRIIB. It remains unclear if engagement of FcγRIIB also extends to the activities of antibodies targeting immunoregulatory TNFRs expressed by T cells. We have explored the requirement for activating and inhibitory FcγRs for the antitumor effects of antibodies targeting the TNFR glucocorticoid-induced TNFR-related protein (GITR; TNFRSF18; CD357) expressed on activated and regulatory T cells (T reg cells). We found that although FcγRIIB was dispensable for the in vivo efficacy of anti-GITR antibodies, in contrast, activating FcγRs were essential. Surprisingly, the dependence on activating FcγRs extended to an antibody targeting the non-TNFR receptor CTLA-4 (CD152) that acts as a negative regulator of T cell immunity. We define a common mechanism that correlated with tumor efficacy, whereby antibodies that coengaged activating FcγRs expressed by tumor-associated leukocytes facilitated the selective elimination of intratumoral T cell populations, particularly T reg cells. These findings may have broad implications for antibody engineering efforts aimed at enhancing the therapeutic activity of immunomodulatory antibodies
The Public Health Exposome: A Population-Based, Exposure Science Approach to Health Disparities Research
The lack of progress in reducing health disparities suggests that new approaches are needed if we are to achieve meaningful, equitable, and lasting reductions. Current scientific paradigms do not adequately capture the complexity of the relationships between environment, personal health and population level disparities. The public health exposome is presented as a universal exposure tracking framework for integrating complex relationships between exogenous and endogenous exposures across the lifespan from conception to death. It uses a social-ecological framework that builds on the exposome paradigm for conceptualizing how exogenous exposures “get under the skin”. The public health exposome approach has led our team to develop a taxonomy and bioinformatics infrastructure to integrate health outcomes data with thousands of sources of exogenous exposure, organized in four broad domains: natural, built, social, and policy environments. With the input of a transdisciplinary team, we have borrowed and applied the methods, tools and terms from various disciplines to measure the effects of environmental exposures on personal and population health outcomes and disparities, many of which may not manifest until many years later. As is customary with a paradigm shift, this approach has far reaching implications for research methods and design, analytics, community engagement strategies, and research training
First radial velocity results from the MINiature Exoplanet Radial Velocity Array (MINERVA)
The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated
observatory of four 0.7m robotic telescopes fiber-fed to a KiwiSpec
spectrograph. The MINERVA mission is to discover super-Earths in the habitable
zones of nearby stars. This can be accomplished with MINERVA's unique
combination of high precision and high cadence over long time periods. In this
work, we detail changes to the MINERVA facility that have occurred since our
previous paper. We then describe MINERVA's robotic control software, the
process by which we perform 1D spectral extraction, and our forward modeling
Doppler pipeline. In the process of improving our forward modeling procedure,
we found that our spectrograph's intrinsic instrumental profile is stable for
at least nine months. Because of that, we characterized our instrumental
profile with a time-independent, cubic spline function based on the profile in
the cross dispersion direction, with which we achieved a radial velocity
precision similar to using a conventional "sum-of-Gaussians" instrumental
profile: 1.8 m s over 1.5 months on the RV standard star HD 122064.
Therefore, we conclude that the instrumental profile need not be perfectly
accurate as long as it is stable. In addition, we observed 51 Peg and our
results are consistent with the literature, confirming our spectrograph and
Doppler pipeline are producing accurate and precise radial velocities.Comment: 22 pages, 9 figures, submitted to PASP, Peer-Reviewed and Accepte
Synchronization modulation increases transepithelial potentials in MDCK monolayers through Na/K pumps
Peer reviewedPublisher PD
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