612 research outputs found
Medical Marijuana Policy Reform Reaches Florida: A Scoping Review
Background: Florida became the first state in the U.S. South to legalize the use of medical marijuana to treat a variety of health conditions including chronic pain, epilepsy, and spasticity symptoms from multiple sclerosis. While there are over 200,000 medical marijuana patients in Florida, there remain financial, psychological, and insurance coverage barriers which reduce access for many patients. Purpose: This scoping review, with a focus on state health policy, first describes some clinical studies examining the therapeutic benefits of medical marijuana. Next, there is a discussion of the Florida regulatory environment and major legislation. Also, the review describes how the current Florida policy landscape presents challenges for physicians and patients. Methods: A scoping review of the literature was conducted in PubMed and Google Scholar using the search terms, “medical marijuana” and “medical cannabis” to identify research articles, newspaper reports, and government documents. The purpose of the review was to identify research investigating the therapeutic efficacy of medical marijuana and state policies affecting physician practice. Results: The review concluded there was general scientific consensus of therapeutic benefits for patients, especially for chronic pain, from the use of medical marijuana. The review also identified several barriers for physicians and patients around cost, stigma, and lack of insurance coverage which constrains use and access. Discussion: The review discusses several directions for future medical marijuana policy and research with the aim to improve therapeutic benefits for Florida patients
Caustics and Rogue Waves in an Optical Sea
There are many examples in physics of systems showing rogue wave behaviour,
the generation of high amplitude events at low probability. Although initially
studied in oceanography, rogue waves have now been seen in many other domains,
with particular recent interest in optics. Although most studies in optics have
focussed on how nonlinearity can drive rogue wave emergence, purely linear
effects have also been shown to induce extreme wave amplitudes. In this paper,
we report a detailed experimental study of linear rogue waves in an optical
system, using a spatial light modulator to impose random phase structure on a
coherent optical field. After free space propagation, different random
intensity patterns are generated, including partially-developed speckle, a
broadband caustic network, and an intermediate pattern with characteristics of
both speckle and caustic structures. Intensity peaks satisfying statistical
criteria for rogue waves are seen especially in the case of the caustic
network, and are associated with broader spatial spectra. In addition, the
electric field statistics of the intermediate pattern shows properties of an
optical sea with near-Gaussian statistics in elevation amplitude, and
trough-to-crest statistics that are near-Rayleigh distributed but with an
extended tail where a number of rogue wave events are observed.Comment: 10 pages, 5 figures, to be published in Scientific Report
Pine sawdust biochar as a potential amendment for establishing trees in Appalachian mine spoils
Early growth and survival of tree seedlings is often poor on reclaimed coal surface mines in Appalachia. Biochar produced in bioenergy generation has potential for use as an amendment to improve seedling performance. Mine soil was collected from a recently reclaimed coal surface mine in Wise County, Virginia and mixed with loblolly pine (Pinus taeda L.) sawdust biochar, simulating application rates of 2.3, 11.2 and 22.5 Mg ha-1. Unplanted leaching columns and 4 L tree planting pots were filled with these biochar-soil mixtures, plus controls of pure mine soil and pure biochar. For the tree planting pots, additional pots were created where the biochar was applied as a topdressing at the same application rates as in the mixtures. One-year-old seedlings of both American sycamore (Platanus occidentalis L.) and black locust (Robinia pseudoacacia L.) were planted. Unplanted leaching columns were leached with collected rainwater for six months to simulate weathering. Trees were grown for one growing season. Black locust had higher average above-ground dry woody biomass (24.4 g) than American sycamore (17.0 g), and also higher below-ground biomass (61.0 g compared to 30.2 g). The pure biochar produced greater average below-ground biomass (99.9 g) than the pure mine soil (46.9 g). All of the biochar treatments produced greater average above-ground woody biomass (19.1 g – 33.4 g) than the pure mine soil (10.9 g). After weathering, biochar provided less available soil phosphorus, calcium and iron than the mine soil itself while increasing soil carbon and organic matter. High (22.5 Mg ha-1) biochar applications increased soil volumetric water holding capacity to 18.6% compared to 13.4% for pure mine soil. Naturally-occurring herbaceous biomass in the pots was negatively correlated with above-ground woody biomass at r = -0.483. Topdressing and full incorporation of biochar were not significantly different in their effects on biomass. Results suggest that pine biochar either broadcast at 2.3 - 22.5 Mg ha‑1, or mixed in planting holes with backfill soil, will promote faster above-ground growth and larger root systems in seedlings in mine soils. Further studies should test these methods in the field over multiple years and further refine recommendations of the rate of biochar to use and how best to apply it. New systems are being developed in Appalachia to produce biofuels and biochar from local biomass and to recycle biochar into the land base to enhance future biomass productivity. Applying 4 L of biochar mixed with the backfill of newly-planted trees is the top recommended practice for tree performance
Can Reflection from Grains Diagnose the Albedo?
By radiation transfer models with a realistic power spectra of the projected
density distributions, we show that the optical properties of grains are poorly
constrained by observations of reflection nebulae. The ISM is known to be
hierarchically clumped from a variety of observations (molecules, H I,
far-infrared). Our models assume the albedo and phase parameter of the dust,
the radial optical depth of the sphere averaged over all directions, and random
distributions of the dust within the sphere. The outputs are the stellar
extinction, optical depth, and flux of scattered light as seen from various
viewing angles. Observations provide the extinction and scattered flux from a
particular direction.
Hierarchical geometry has a large effect on the flux of scattered light
emerging from a nebula for a particular extinction of the exciting star. There
is a very large spread in both scattered fluxes and extinctions for any
distribution of dust. Consequently, an observed stellar extinction and
scattered flux can be fitted by a wide range of albedos. With hierarchical
geometry it is not completely safe to determine even relative optical constants
from multiwavelength observations of the same reflection nebula. The geometry
effectively changes with wavelength as the opacity of the clumps varies. Limits
on the implications of observing the same object in various wavelengths are
discussed briefly.
Henry (2002) uses a recipe to determine the scattered flux from a star with a
given extinction. It is claimed to be independent of the geometry. It provides
considerably more scattering than our models, probably leading to an
underestimate of the grain albedos from the UV Diffuse Galactic Light.Comment: 27 pages, including 7 figures. Accepted by Ap
GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire), a SIRTF
Legacy Science Program, will be a fully sampled, confusion-limited infrared
survey of the inner two-thirds of the Galactic disk with a pixel resolution of
\~1.2" using the Infrared Array Camera (IRAC) at 3.6, 4.5, 5.8, and 8.0
microns. The survey will cover Galactic latitudes |b| <1 degree and longitudes
|l|=10 to 65 degrees (both sides of the Galactic center). The survey area
contains the outer ends of the Galactic bar, the Galactic molecular ring, and
the inner spiral arms. The GLIMPSE team will process these data to produce a
point source catalog, a point source data archive, and a set of mosaicked
images. We summarize our observing strategy, give details of our data products,
and summarize some of the principal science questions that will be addressed
using GLIMPSE data. Up-to-date documentation, survey progress, and information
on complementary datasets are available on the GLIMPSE web site:
www.astro.wisc.edu/glimpse.Comment: Description of GLIMPSE, a SIRTF Legacy project (Aug 2003 PASP, in
press). Paper with full res.color figures at
http://www.astro.wisc.edu/glimpse/glimpsepubs.htm
Estimating the Porosity of the Interstellar Medium from Three-Dimensional Photoionization Modeling of H II Regions
We apply our three dimensional photoionization code to model Wisconsin
H-alpha Mapper observations of the H II region surrounding the O9.5V star Zeta
Oph. Our models investigate the porosity of the interstellar medium around zeta
Oph and the effects of 3D densities on the H-alpha surface brightness and
variation in the [N II]/H-alpha line ratio. The Zeta Oph H II region has a well
characterized ionizing source, so it is an excellent starting point for 3D
models of diffuse ionized gas. We investigate various hierarchically clumped
density structures, varying the overall smoothness within the clumping
algorithm. By simulating the observations, we can estimate the porosity of the
medium in the vicinity of Zeta Oph and find that within the context of our
hierarchically clumped models, around 50% to 80% of the volume is occupied by
clumps surrounded by a low density smooth medium. We also conclude that in
order for O stars to ionize the diffuse Warm Ionized Medium, the O star
environment must be more porous than that surrounding Zeta Oph, with clumps
occupying less than one half of the interstellar volume. Our clumpy models have
irregular boundaries, similar to observed H II regions. However, in observed H
II regions it is difficult to identify the precise location of the boundary
because of the foreground and/or background emission from the widespread Warm
Ionized Medium. This complicates the interpretation of the predicted rapid rise
of some emission line ratios near the edge of uniform density H II regions and
combined with the three dimensional clumpy nature of the interstellar medium
may explain the apparent lack of distinctive emission line ratios near H I -- H
II interfaces.Comment: Accepted for publication in Ap
How chemistry controls electron localization in 3d1 perovskites: A Wannier-function study
In the series of 3d1 t2g perovskites, SrVO3--CaVO3--LaTiO3--YTiO3 the
transition-metal d electron becomes increasingly localized and undergoes a Mott
transition between CaVO3 and LaTiO3. By defining a low-energy Hubbard
Hamiltonian in the basis of Wannier functions for the t2g LDA band and solving
it in the single-site DMFT approximation, it was recently shown[1] that
simultaneously with the Mott transition there occurs a strong suppression of
orbital fluctuations due to splitting of the t2g levels. The present paper
reviews and expands this work, in particular in the direction of exposing the
underlying chemical mechanisms by means of ab initio LDA Wannier functions
generated with the NMTO method. The Wannier functions for the t2g band exhibit
covalency between the transition-metal t2g, the large cation-d, and the
oxygen-p states; this covalency, which increases along the series, turns out to
be responsible not only for the splittings of the t2g levels, but also for
non-cubic perturbations of the hopping integrals, both of which are decisive
for the Mott transition. We find good agreement with the optical and
photoemission spectra, with the crystal-field splittings and orbital
polarizations recently measured for the titanates, and with the metallization
volume for LaTiO3. The metallization volume for YTiO3 is predicted. Using
super-exchange theory, we reproduce the observed magnetic orders in LaTiO3 and
YTiO3, but the results are sensitive to detail, in particular for YTiO3 which,
without the Jahn-Teller distortion, would be AFM C- or A-type, rather than FM.
Finally, we show that it possible to unfold the orthorhombic t2g LDA
bandstructure to a pseudocubic zone. In this zone, the lowest band is separated
from the two others by a direct gap and has a width, W_I, which is
significantly smaller than that, W, of the entire t2g band. The progressive
GdFeO3-type distortion favours electron localization by decreasing W, by
increasing the splitting of the t2g levels and by decreasing W_I. Our
conclusions concerning the roles of GdFeO3-type and JT distortions agree with
those of Mochizuki and Imada [2].Comment: Published version, final. For high resolution figures see
http://www.fkf.mpg.de/andersen/docs/pub/abstract2004+/pavarini_02.pd
Near-Infrared Synchrotron Emission from Cas A
High energy observations of Cas A suggested the presence of synchrotron
radiation, implying acceleration of cosmic rays by young supernova remnants. We
detect synchrotron emission from Cas A in the near-infrared using Two Micron
All Sky Survey (2MASS) and Palomar 200 inch PFIRCAM observations. The remnant
is detected in J, H, and Ks bands, with Ks band brightest and J faint. In the J
and H bands, bright [Fe II] lines (1.24um and 1.64um) are detected
spectroscopically. The Palomar observations include Ks continuum, narrow-band
1.64um (centered on [Fe II]) and 2.12um (centered on H2(1-0)) images. While the
narrow-band 1.64um image shows filamentary and knotty structures, similar to
the optical image, the Ks image shows a relatively smooth, diffuse shell,
remarkably similar to the radio image. The broad-band near-infrared fluxes of
Cas A are generally consistent with, but a few tens of percent higher than, an
extrapolation of the radio fluxes. The hardening to higher frequencies is
possibly due to nonlinear shock acceleration and/or spectral index variation
across the remnant. We show evidence of spectral index variation. The presence
of near-infrared synchrotron radiation requires the roll-off frequency to be
higher than 1.5e14 Hz, implying that electrons are accelerated to energies of
at least 0.2 TeV. The morphological similarity in diffuse emission between the
radio and Ks band images implies that synchrotron losses are not dominant. Our
observations show unambiguous evidence that the near-infrared Ks band emission
of Cas A is from synchrotron emission by accelerated cosmic-ray electrons.Comment: accepted by Ap
Photoionization Models of NGC 346
We present spherically symmetric and plane parallel photoionization models of
NGC 346, an HII region in the Small Magellanic Cloud. The models are based on
CLOUDY and on the observations of Peimbert, Peimbert, & Ruiz (2000). We find
that approximately 45% of the H ionization photons escape from the HII region
providing an important ionizing source for the low density interstellar medium
of the SMC. The predicted I(4363)/I(5007) value is smaller than that observed,
probably implying that there is an additional source of energy not taken into
account by the models. From the ionization structure of the best model and the
observed line intensities we determine the abundances of N, Ne, S, Ar, and Fe
relative to O.Comment: 23 pages, 2 figures, Accepted for publication in Ap
FUSE Measurements of Far Ultraviolet Extinction. I. Galactic Sight Lines
We present extinction curves that include data down to far ultraviolet
wavelengths (FUV; 1050 - 1200 A) for nine Galactic sight lines. The FUV
extinction was measured using data from the Far Ultraviolet Spectroscopic
Explorer. The sight lines were chosen for their unusual extinction properties
in the infrared through the ultraviolet; that they probe a wide range of dust
environments is evidenced by the large spread in their measured ratios of
total-to-selective extinction, R_V = 2.43 - 3.81. We find that extrapolation of
the Fitzpatrick & Massa relationship from the ultraviolet appears to be a good
predictor of the FUV extinction behavior. We find that predictions of the FUV
extinction based upon the Cardelli, Clayton & Mathis (CCM) dependence on R_V
give mixed results. For the seven extinction curves well represented by CCM in
the infrared through ultraviolet, the FUV extinction is well predicted in three
sight lines, over-predicted in two sight lines, and under-predicted in 2 sight
lines. A Maximum Entropy Method analysis using a simple three component grain
model shows that seven of the nine sight lines in the study require a larger
fraction of grain materials to be in dust when FUV extinction is included in
the models. Most of the added grain material is in the form of small (radii <
200 A) grains.Comment: Accepted for publication in the Astrophysical Journal. 31 pages with
7 figure
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