7,007 research outputs found
Conductance fingerprint of Majorana fermions in the topological Kondo effect
We consider an interacting nanowire/superconductor heterostructure attached
to metallic leads. The device is described by an unusual low-energy model
involving spin-1 conduction electrons coupled to a nonlocal spin-1/2 Kondo
impurity built from Majorana fermions. The topological origin of the resulting
Kondo effect is manifest in distinctive non-Fermi-liquid (NFL) behavior, and
the existence of Majorana fermions in the device is demonstrated unambiguously
by distinctive conductance lineshapes. We study the physics of the model in
detail, using the numerical renormalization group, perturbative scaling and
abelian bosonization. In particular, we calculate the full scaling curves for
the differential conductance in AC and DC fields, onto which experimental data
should collapse. Scattering t-matrices and thermodynamic quantities are also
calculated, recovering asymptotes from conformal field theory. We show that the
NFL physics is robust to asymmetric Majorana-lead couplings, and here we
uncover a duality between strong and weak coupling. The NFL behavior is
understood physically in terms of competing Kondo effects. The resulting
frustration is relieved by inter-Majorana coupling which generates a second
crossover to a regular Fermi liquid.Comment: 17 pages, 8 figure
Relationship Between the Foveal Avascular Zone and Foveal Pit Morphology
Purpose.To assess the relationship between foveal pit morphology and size of the foveal avascular zone (FAZ).
Methods. Forty-two subjects were recruited. Volumetric images of the macula were obtained using spectral domain optical coherence tomography. Images of the FAZ were obtained using either a modified fundus camera or an adaptive optics scanning light ophthalmoscope. Foveal pit metrics (depth, diameter, slope, volume, and area) were automatically extracted from retinal thickness data, whereas the FAZ was manually segmented by two observers to extract estimates of FAZ diameter and area.
Results. Consistent with previous reports, the authors observed significant variation in foveal pit morphology. The average foveal pit volume was 0.081 mm3 (range, 0.022 to 0.190 mm3). The size of the FAZ was also highly variable between persons, with FAZ area ranging from 0.05 to 1.05 mm2 and FAZ diameter ranging from 0.20 to 1.08 mm. FAZ area was significantly correlated with foveal pit area, depth, and volume; deeper and broader foveal pits were associated with larger FAZs.
Conclusions. Although these results are consistent with predictions from existing models of foveal development, more work is needed to confirm the developmental link between the size of the FAZ and the degree of foveal pit excavation. In addition, more work is needed to understand the relationship between these and other anatomic features of the human foveal region, including peak cone density, rod-free zone diameter, and Henle fiber layer
CFD Simulation of Low Reynolds-number Turbulence Models in Coral Thermal Microenvironment
The increasing frequency and severity of mass bleaching events in the past few decades has raised considerable concerns. Here we report on the numerical simulations of Low Reynolds turbulence models coral microenvironments to determine surface temperature rise in reef corals and test whether our model is capable to estimate of the extent of warming likely to be en-countered in the nature during calm conditions. The Computational Fluid Dynamics (CFD) simulation uses the OpenFOAM CFD libraries to implement a steady-state turbulent flow porous medium model, with heat transfer accounted for using a transport equation for temperature. We validated the model using controlled laboratory experiment observations
Kiloparsec-scale Spatial Offsets in Double-peaked Narrow-line Active Galactic Nuclei. I. Markers for Selection of Compelling Dual Active Galactic Nucleus Candidates
Merger-remnant galaxies with kpc-scale separation dual active galactic nuclei
(AGNs) should be widespread as a consequence of galaxy mergers and triggered
gas accretion onto supermassive black holes, yet very few dual AGNs have been
observed. Galaxies with double-peaked narrow AGN emission lines in the Sloan
Digital Sky Survey are plausible dual AGN candidates, but their double-peaked
profiles could also be the result of gas kinematics or AGN-driven outflows and
jets on small or large scales. To help distinguish between these scenarios, we
have obtained spatial profiles of the AGN emission via follow-up long-slit
spectroscopy of 81 double-peaked narrow-line AGNs in SDSS at 0.03 < z < 0.36
using Lick, Palomar, and MMT Observatories. We find that all 81 systems exhibit
double AGN emission components with ~kpc projected spatial separations on the
sky, which suggests that they are produced by kpc-scale dual AGNs or kpc-scale
outflows, jets, or rotating gaseous disks. In addition, we find that the
subsample (58%) of the objects with spatially compact emission components may
be preferentially produced by dual AGNs, while the subsample (42%) with
spatially extended emission components may be preferentially produced by AGN
outflows. We also find that for 32% of the sample the two AGN emission
components are preferentially aligned with the host galaxy major axis, as
expected for dual AGNs orbiting in the host galaxy potential. Our results both
narrow the list of possible physical mechanisms producing the double AGN
components, and suggest several observational criteria for selecting the most
promising dual AGN candidates from the full sample of double-peaked narrow-line
AGNs. Using these criteria, we determine the 17 most compelling dual AGN
candidates in our sample.Comment: 12 pages, 8 figures, published in ApJ. Modified from original version
to reflect referee's comment
Vaccine Cooler for the Global Poor
Cal Poly physics professors Peter Schwartz and Nathan Heston approached the Solar Freeze team with the problem that remote communities in Africa have limited access to modern-day medicine or vaccines. They suggested that we try and design a cooling device that can keep vaccines cold for multiple days at a time while the medicine is transported to remote villages. Currently, there are vaccine cooler products on the market, but most of them are very expensive or lack portability. Peter and Nate have tasked the Solar Freeze team to come up with a less expensive solution that is also portable and can handle the harsh environments of Africa. Due to the fact that Peter and Nate have done extensive research and laboratory experiments with using a solar panel to power thermo-electric coolers, they suggested that a thermo-electric cooler should be used to keep the cooler cold. The Solar Freeze team’s goal is to design a solar-powered vaccine cooler that utilizes thermo-electric coolers to freeze a phase change material and keep vaccines at optimal temperature
A Novel Massage Therapy Technique for Management of Chronic Cervical Pain: A Case Series
Background: Neck pain is a generalized condition resulting from a complex etiology with presentation of a wide variety of symptoms. Neck pain is most often accompanied by decreased range of motion (ROM), muscle and joint stiffness, and limitations in functional capabilities. This condition may result in significant personal and societal burden.
Purpose: We evaluated the effectiveness of a novel massage therapy intervention by following the treatment regimen and outcomes of two patients experiencing chronic neck pain.
Participants: Two patients (46 and 53 years old) experienced chronic (>5 years) neck pain. Both patients reported pain, limited ROM, and muscle and joint stiffness. Additionally, the first patient reported a lack of sleep, and both patients stated their pain interfered with their quality of life and activities of daily living.
Intervention: Patients received the Integrative Muscular Movement Technique (IMMT) intervention approximately twice a week for a total of eight treatments, each approximately 20 minutes in duration.
Results: Both patients experienced a reduction in pain and an increase in cervical ROM in flexion, extension, rotation, and sidebending. The first patient also reported an increased ability to sleep. Both patients reported an increased ability to perform activities of daily living, including work-related responsibilities.
Conclusions: For the two patients included in this report, therapist observations and patient reports indicate that inclusion of the IMMT treatment in a treatment regimen for chronic neck pain may lead to decreased pain and increased cervical ROM. These positive effects of the IMMT intervention may have a role in enhancing functional outcomes of these patients
AEGIS: Extinction and Star Formation Tracers from Line Emission
Strong nebular emission lines are a sensitive probe of star formation and
extinction in galaxies, and the [O II] line detects star forming populations
out to z>1. However, star formation rates from emission lines depend on
calibration of extinction and the [O II]/H-alpha line ratio, and separating
star formation from AGN emission. We use calibrated line luminosities from the
DEEP2 survey and Palomar K magnitudes to show that the behavior of emission
line ratios depends on galaxy magnitude and color. For galaxies on the blue
side of the color bimodality, the vast majority show emission signatures of
star formation, and there are strong correlations of extinction and [O
II]/H-alpha with restframe H magnitude. The conversion of [O II] to
extinction-corrected H-alpha and thus to star formation rate has a significant
slope with M_H, 0.23 dex/mag. Red galaxies with emission lines have a much
higher scatter in their line ratios, and more than half show AGN signatures. We
use 24 micron fluxes from Spitzer/MIPS to demonstrate the differing populations
probed by nebular emission and by mid-IR luminosity. Although extinction is
correlated with luminosity, 98% of IR-luminous galaxies at z~1 are still
detected in the [O II] line. Mid-IR detected galaxies are mostly bright and
intermediate color, while fainter, bluer galaxies with high [O II] luminosity
are rarely detected at 24 microns.Comment: 4 pages, 3 figures. Accepted for publication in ApJ Letters AEGIS
special editio
Oxidation of tertiary amine-derivatized surfaces to control protein adhesion
Selective oxidation of omega-tertiary amine self-assembled thiol monolayers to tertiary amine N-oxides is shown to transform the adhesion of model proteins lysozyme and fibrinogen upon them. Efficient preparation of both secondary and tertiary linker amides as judged by X-ray photoelectron spectroscopy (XPS) and water droplet contact angle was achieved with an improved amide bond formation on gold quartz crystal microbalance (QCM) sensors using 2-(1H-7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyl hexafluorophosphate methanaminium uronium (HATU). Oxidation with hydrogen peroxide was similarly assessed, and adhesion of lysozyme and fibrinogen from phosphate buffered saline was then assayed by QCM and imaged by AFM. Tertiary amine-functionalized sensors adsorbed multilayers of aggregated lysozyme, whereas tertiary amine N-oxides and triethylene glycol-terminated monolayers are consistent with small protein aggregates. The surface containing a dimethylamine N-oxide headgroup and ethyl secondary amide linker showed the largest difference in adsorption of both proteins. Oxidation of tertiary amine decorated surfaces therefore holds the potential for selective deposition of proteins and cells through masking and other patterning techniques
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