1,622 research outputs found
The Strange Tale of Wesley and Florence Garrison: Racial Crosscurrents of the Postwar Florida Republican Party
For the first two thirds of the 20th Century, the Republican Party of Florida had a well-deserved reputation for being quiet, weak, and ineffectual. The Democratic Party dominated electoral politics so completely that some counties in the panhandle and north central Florida prided themselves on having no registered Republicans. Yet at the 1952 state Republican convention, held in the sleepy college town of Gainesville, the participants acted as if their meeting mattered. A group of upstarts led by Miami real estate developers Wesley and Florence Garrison, a couple some regarded as reformers and some regarded as rabblerousers, commandeered the front row of seating and refused to allow the state executive committee to take their positions on stage. After the Alachua County sheriff restored order, the Garrisons and their supporters made their presence known by repeatedly interrupting the opening roll call with chants of contest and communist, and slamming their chair legs loudly against the tile floor. At issue was the party\u27s decision to abandon the primary election and select its delegates to the Republican national convention without participation from rank and file party members, a choice the Garrisons vehemently opposed. Despite the repeated distractions, however, the state party went on with its agenda and appointed a delegate slate that excluded the Gamsons and their allies
Magellan LDSS3 emission confirmation of galaxies hosting metal-rich Lyman-alpha absorption systems
Using the Low Dispersion Survey Spectrograph 3 at the Magellan II Clay
Telescope, we target {candidate absorption host galaxies} detected in deep
optical imaging {(reaching limiting apparent magnitudes of 23.0-26.5 in and filters) in the fields of three QSOs, each of which shows the
presence of high metallicity, high absorption systems in their
spectra (Q0826-2230: =0.9110, Q1323-0021: ,
Q1436-0051: ). We confirm three host galaxies {at
redshifts 0.7387, 0.7401, and 0.9286} for two of the Lyman- absorption
systems (one with two galaxies interacting). For these systems, we are able to
determine the star formation rates (SFRs); impact parameters (from previous
imaging detections); the velocity shift between the absorption and emission
redshifts; and, for one system, also the emission metallicity.} Based on
previous photometry, we find these galaxies have LL. The [O II]
SFRs for these galaxies are in the range M yr
{(uncorrected for dust)}, while the impact parameters lie in the range
kpc. {Despite the fact that we have confirmed galaxies at 50 kpc from the QSO,
no gradient in metallicity is indicated between the absorption metallicity
along the QSO line of sight and the emission line metallicity in the galaxies.}
We confirm the anti-correlation between impact parameter and from
the literature. We also report the emission redshift of five other galaxies:
three at , and two (LL) at not
corresponding to any known absorption systems.Comment: 14 pages, 7 figures, 4 tables, accepted to MNRA
Oliveros Virus: A Novel Arenavirus from Argentina
AbstractDuring the past few decades several newly recognized rodent-borne arenaviruses have been shown to be associated with severe hemorrhagic fever cases in South America. Changes in ecology and farming practices throughout the region have increased the concern over the potential public health threat posed by such emerging virus diseases. Oliveros (OLV) virus is a recently discovered arenavirus of the rodentBolomys obscurusin Argentina. Genetic analysis of the small genomic RNA segment, which encodes the nucleocapsid protein and the envelope glycoproteins, shows that Oliveros is a novel, phylogenetically distinct member of theArenaviridaefamily which differs in nucleotide sequence from the previously characterized members by approximately 35% or more. Despite this level of diversity, OLV virus possesses the same ambisense genome structure and many overall RNA and protein features in common with other arenaviruses. These data represent an important first step in the development of specific immunological and PCR diagnostic reagents to allow assessment of the prevalence and disease potential of this virus
Fundamental constraints on particle tracking with optical tweezers
A general quantum limit to the sensitivity of particle position measurements
is derived following the simple principle of the Heisenberg microscope. The
value of this limit is calculated for particles in the Rayleigh and Mie
scattering regimes, and with parameters which are relevant to optical tweezers
experiments. The minimum power required to observe the zero-point motion of a
levitating bead is also calculated, with the optimal particle diameter always
smaller than the wavelength. We show that recent optical tweezers experiments
are within two orders of magnitude of quantum limited sensitivity, suggesting
that quantum optical resources may soon play an important role in high
sensitivity tracking applications
OVI Absorption in the Milky Way Disk, and Future Prospects for Studying Absorption at the Galaxy-IGM Interface
We present a brief summary of results from our FUSE program designed to study
OVI absorption in the disk of the Milky Way. As a full analysis of our data has
now been published, we focus on the improvements that FUSE afforded us compared
to Copernicus data published thirty years ago. We discuss FUSE's limitations in
studying OVI absorption from nearby galaxies using background QSOs, but present
FUSE spectra of two probes which indicate the absence of OVI (but the presence
of Lyman-beta) absorption 8 and 63 kpc from a foreground galaxy. Finally, we
discuss the need for a more sensitive UV spectrograph to map out the physical
conditions of baryons around galaxies.Comment: Invited review to appear in the proceedings of "Future Directions in
Ultraviolet Spectroscopy" meeting, held Oct 20-22, 2008, Annapolis, MD. To
appear as an AIP Conference Proceedin
Bioinspired materials for underwater adhesion with pathways to switchability
Strong adherence to underwater or wet surfaces for applications like tissue adhesion and underwater robotics is a significant challenge. This is especially apparent when switchable adhesion is required that demands rapid attachment, high adhesive capacity, and easy release. Nature displays a spectrum of permanent to reversible attachment from organisms ranging from the mussel to the octopus, providing inspiration for underwater adhesion design that has yet to be fully leveraged in synthetic systems. Here, we review the challenges and opportunities for creating underwater adhesives with a pathway to switchability. We discuss key material, geometric, modeling, and design tools necessary to achieve underwater adhesion similar to the adhesion control demonstrated in nature. Through these interdisciplinary efforts, we envision that bioinspired adhesives can rise to or even surpass the extraordinary capabilities found in biological systems
Proton and Alpha Driven Instabilities in an Ion Cyclotron Wave Event
Ion scale wave events or "wave storms" in the solar wind are characterised by
enhancements in magnetic field fluctuations as well as coherent magnetic field
polarisation signatures at or around the local ion cyclotron frequencies. In
this paper we study in detail one such wave event from Parker Solar Probe's
(PSP) fourth encounter, consisting of an initial period of left-handed (LH)
polarisation abruptly transitioning to a strong period of right-handed (RH)
polarisation, accompanied by clear core-beam structure in both the alpha and
proton velocity distribution functions. A linear stability analysis shows that
the LH polarised waves are anti-Sunward propagating Alfv\'en/ion cyclotron
(A/IC) waves primarily driven by a proton cyclotron instability in the proton
core population, and the RH polarised waves are anti-Sunward propagating fast
magnetosonic/whistler (FM/W) waves driven by a firehose-like instability in the
secondary alpha beam population. The abrupt transition from LH to RH is caused
by a drop in the proton core temperature anisotropy. We find very good
agreement between the frequencies and polarisations of the unstable wave modes
as predicted by linear theory and those observed in the magnetic field spectra.
Given the ubiquity of ion scale wave signatures observed by PSP, this work
gives insight into which exact instabilities may be active and mediating energy
transfer in wave-particle interactions in the inner heliosphere, as well as
highlighting the role a secondary alpha population may play as a rarely
considered source of free energy available for producing wave activity
Synchrotron radiation x-ray topography and defect selective etching analysis of threading dislocations in GaN
The crystal quality of bulk GaN crystals is continuously improving due to advances in GaN growth techniques. Defect characterization of the GaN substrates by conventional methods is impeded by the very low dislocation density and a large scale defect analysis method is needed. White beam synchrotron radiation x-ray topography (SR-XRT) is a rapid and non-destructive technique for dislocation analysis on a large scale. In this study, the defect structure of an ammonothermal c-plane GaN substrate was recorded using SR-XRT and the image contrast caused by the dislocation induced microstrain was simulated. The simulations and experimental observations agree excellently and the SR-XRT image contrasts of mixed and screw dislocations were determined. Apart from a few exceptions, defect selective etching measurements were shown to correspond one to one with the SR-XRT results.Peer reviewe
The In Situ Signature of Cyclotron Resonant Heating
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. We
show that the observed cyclotron wave population coincides with both flattening
in the phase space distribution predicted by resonant quasilinear diffusion and
steepening in the turbulent spectra at the ion-cyclotron resonant scale. In
measured velocity distribution functions where cyclotron resonant flattening is
weaker, the distributions are nearly uniformly subject to ion-cyclotron wave
damping rather than emission, indicating that the distributions can damp the
observed wave population. These results are consistent with active cyclotron
heating in the solar wind
Scientific challenges and present capabilities in underwater robotic vehicle design and navigation for oceanographic exploration under-ice.
This paper reviews the scientific motivation and challenges, development, and use of underwater robotic vehicles designed for use in ice-covered waters, with special attention paid to the navigation systems employed for under-ice deployments. Scientific needs for routine access under fixed and moving ice by underwater robotic vehicles are reviewed in the contexts of geology and geophysics, biology, sea ice and climate, ice shelves, and seafloor mapping. The challenges of under-ice vehicle design and navigation are summarized. The paper reviews all known under-ice robotic vehicles and their associated navigation systems, categorizing them by vehicle type (tethered, untethered, hybrid, and glider) and by the type of ice they were designed for (fixed glacial or sea ice and moving sea ice). © 2020 by the authors
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