5,638 research outputs found
Medical Marijuana Laws, Traffic Fatalities, and Alcohol Consumption
To date, 16 states have passed medical marijuana laws, yet very little is known about their effects. Using state-level data, we examine the relationship between medical marijuana laws and a variety of outcomes. Legalization of medical marijuana is associated with increased use of marijuana among adults, but not among minors. In addition, legalization is associated with a nearly 9 percent decrease in traffic fatalities, most likely to due to its impact on alcohol consumption. Our estimates provide strong evidence that marijuana and alcohol are substitutes.medical marijuana, traffic fatalities, alcohol consumption
High on Life? Medical Marijuana Laws and Suicide
Using state-level data for the period 1990 through 2007, we estimate the effect of legalizing medical marijuana on suicide rates. Our results suggest that the passage of a medical marijuana law is associated with an almost 5 percent reduction in the total suicide rate, an 11 percent reduction in the suicide rate of 20- through 29-year-old males, and a 9 percent reduction in the suicide rate of 30- through 39-year-old males. Estimates of the relationship between legalization and female suicides are less precise and are sensitive to functional form.medical marijuana laws, marijuana, alcohol, suicide
Observation of O+ 4P-4D0 lines in proton aurora over Svalbard
Spectra of a proton aurora event show lines of O+ 4P-4D0 multiplet (4639–4696 Å) enhanced relative to the N2 +1N(0,2) compared to normal electron aurora. Conjugate satellite particle measurements are used as input to electron and proton transport models, to show that p/H precipitation is the dominant source of both the O+ and N2 +1N emissions. The emission cross-section of the multiplet in p collisions with O and O2 estimated from published work does not explain the observed O+ brightness, suggesting a higher emission cross-section for low energy p impact on O
Cosmological quintessence accretion onto primordial black holes : conditions for their growth to the supermassive scale
In this work we revisit the growth of small primordial black holes (PBHs)
immersed in a quintessential field and/or radiation to the supermassive black
hole (SMBHs) scale. We show the difficulties of scenarios in which such huge
growth is possible. For that purpose we evaluated analytical solutions of the
differential equations (describing mass evolution) and point out the strong
fine tuning for that conclusions. The timescale for growth in a model with a
constant quintessence flux is calculated and we show that it is much bigger
than the Hubble time.The fractional gain of the mass is further evaluated in
other forms, including quintessence and/or radiation. We calculate the
cosmological density due to quintessence necessary to grow BHs to the
supermassive range and show it to be much bigger than one. We also describe the
set of complete equations analyzing the evolution of the BH+quintessence
universe, showing some interesting effects such the quenching of the BH mass
growth due to the evolution of the background energy. Additional constraints
obtained by using the Holographic Bound are also described. The general
equilibrium conditions for evaporating/accreting black holes evolving in a
quintessence/radiation universe are discussed in the Appendix.Comment: 21 pp., 2 Figures, To appear in IJMP
The ducky^{2J} Mutation in Cacna2d2 Results in Reduced Spontaneous Purkinje Cell Activity and Altered Gene Expression
The mouse mutant ducky and its allele ducky^{2J} represent a model for absence epilepsy characterized by spike-wave seizures and cerebellar ataxia. These mice have mutations in Cacna2d2, which encodes the α₂δ-2 calcium channel subunit. Of relevance to the ataxic phenotype, α₂δ-2 mRNA is strongly expressed in cerebellar Purkinje cells (PCs). The Cacna2d2du2J mutation results in a 2 bp deletion in the coding region and a complete loss of α₂δ-2 protein. Here we show that du^{2J}/du^{2J} mice have a 30% reduction in somatic calcium current and a marked fall in the spontaneous PC firing rate at 22°C, accompanied by a decrease in firing regularity, which is not affected by blocking synaptic input to PCs. At 34°C, du^{2J}/du^{2J} PCs show no spontaneous intrinsic activity. DU^{2J}/du^{2J} mice also have alterations in the cerebellar expression of several genes related to PC function. At postnatal day 21, there is an elevation of tyrosine hydroxylase mRNA and a reduction in tenascin-C gene expression. Although du^{2J}/+ mice have a marked reduction in α₂δ-2 protein, they show no fall in PC somatic calcium currents or increase in cerebellar tryrosine hydroxylase gene expression. However, du^{2J}/+ PCs do exhibit a significant reduction in firing rate, correlating with the reduction in α₂δ-2. A hypothesis for future study is that effects on gene expression occur as a result of a reduction in somatic calcium currents, whereas effects on PC firing occur as a long-term result of loss of α₂δ-2 and/or a reduction in calcium currents and calcium-dependent processes in regions other than the soma
Temporal Variability of the X-ray Emission of the Crab Nebula Torus
We have analyzed five ROSAT HRI images of the Crab Nebula spanning the years
1991 to 1997 and have found significant changes in the emission structure of
the X-ray torus surrounding the pulsar. Certain regions increase in brightness
by about 20% over the six years, while others show decreases in surface
brightness. The origin of these changes is unclear, but a possible explanation
is that the bulk velocity of the synchrotron radiating electrons has decreased
on the order of 20% as well.Comment: 15 pages plus 6 figures, figure 1 and figure 6 are in color, to
appear in The Astrophysical Journal, Jan 1, 1999, Vol. 510, #
Forming Galaxies with MOND
Beginning with a simple model for the growth of structure, I consider the
dissipationless evolution of a MOND-dominated region in an expanding Universe
by means of a spherically symmetric N-body code. I demonstrate that the final
virialized objects resemble elliptical galaxies with well-defined relationships
between the mass, radius, and velocity dispersion. These calculations suggest
that, in the context of MOND, massive elliptical galaxies may be formed early
(z > 10) as a result of monolithic dissipationless collapse. Then I reconsider
the classic argument that a galaxy of stars results from cooling and
fragmentation of a gas cloud on a time scale shorter than that of dynamical
collapse. Qualitatively, the results are similar to that of the traditional
picture; moreover, the existence, in MOND, of a density-temperature relation
for virialized, near isothermal objects as well as a mass-temperature relation
implies that there is a definite limit to the mass of a gas cloud where this
condition can be met-- an upper limit corresponding to that of presently
observed massive galaxies.Comment: 9 pages, 9 figures, revised in response to comments of referee. Table
added, extended discussion, accepted MNRA
Wind Climatology at 87 km above the Rocky Mountains at Bear Lake Observatory--Fabry-Perot Observations of OH
This paper presents the neutral -wind climatology at approximately 87-km 53 altitude from Utah State University\u27s Bear Lake Observatory (BLO). a mid-latitude site 54 situated in the middle of the Rocky Mountains. The winds were determined using a very 55 sensitive Fabry-Perot interferometer (FPI) observing the OH Me inel (6-2) PI (3) line al 56 843 nm. The climatology. determined from monthly averages of the nightly evolution of 57 the geographic meridional and zonal wind components over forty· five months, has three 58 distinct seasonal patterns: winter (November- February), summer (May-Jul y), and late 59 Slimmer (August and September). The background zonal wind is eastward the whole year 60 except March and April. The background meridional wind is northward in winter and 61 southward during the rest of the year. In late summer. the winds exhibit a very strong 62 semidiurnal tidal variation almost every night. In summer, they exhibit a similar tidal 63 variation on enough nights that a semi diurnal pattern appears in the climatology. In 64 winter. the nighHo·night variability is so great that little structure is evident in the 65 climatology . These winds are compared to those from other techniques or sites: ~l 66 observations from UARS. FPI observations from Michigan, and MF radar observations. 67 While generally agreeing in relative amplitudes and i.n phase. differences do exist. 68 especially the weak semidiurnal tide at BLO in winter and a greatly reduced {tide at spring 69 equinox compared to late summer. It is likely that these differences arise from the 2 70 topographical generation of gravity waves by winds flowing over the Rocky Mountains. 71 The tidal variations are also compared to results from the global-scale wave model 72 (GSWM): our semidiurnal amplitudes arc considerably bigger except in winter, and our 73 phases vary from showing very good agreement in July, fair agreement in April and 74 January, and disagreement in October. These large differences may be evidence that 11011 - 75 linear effects are more important than realized. The behavior of the background winds is 76 consistent with different populations of gravity waves reaching 87 km in summer and 77 winter. The behavior of the semidiurnal tidal variation is consistent\u27 with a strong 78 interaction between the tidal and gravity·wave wind fields, and is consistent with the 79 different summer and Winter gravity wave population s, and with a fall· spring asymmetry 80 characterized by much weaker gravity wave sources in late summer than near spring 81 equinox
Spectra and Light Curves of GRB Afterglows
We performed accurate numerical calculations of angle-, time-, and
frequency-dependent radiative transfer for the relativistic motion of matter in
gamma-ray burst (GRB) models. Our technique for solving the transfer equation,
which is based on the method of characteristics, can be applied to the motion
of matter with a Lorentz factor up to 1000. The effect of synchrotron
self-absorption is taken into account. We computed the spectra and light curves
from electrons with a power-law energy distribution in an expanding
relativistic shock and compare them with available analytic estimates. The
behavior of the optical afterglows from GRB 990510 and GRB 000301c is discussed
qualitatively.Comment: 8 pages, 7 figure
Scalar radiation emitted from a source rotating around a black hole
We analyze the scalar radiation emitted from a source rotating around a
Schwarzschild black hole using the framework of quantum field theory at the
tree level. We show that for relativistic circular orbits the emitted power is
about 20% to 30% smaller than what would be obtained in Minkowski spacetime. We
also show that most of the emitted energy escapes to infinity. Our formalism
can readily be adapted to investigate similar processes.Comment: 19 pages (REVTEX), 5 figures, title slightly changed, extra
demonstration and minor improvements included. To appear in Class. Quant.
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