4,424 research outputs found
Leibniz algebroid associated with a Nambu-Poisson structure
The notion of Leibniz algebroid is introduced, and it is shown that each
Nambu-Poisson manifold has associated a canonical Leibniz algebroid. This fact
permits to define the modular class of a Nambu-Poisson manifold as an
appropiate cohomology class, extending the well-known modular class of Poisson
manifolds
What are the prospects for privatizing infrastructure? Lessons from U. S. roads and solid waste
Infrastructure (Economics) ; Roads
Opioids: The Silent Painkillers of the 21st Century
This research paper is not solely meant for college academics to add to the tedious job of reading and grading another senior symposium. Instead, I hope this reading finds numerous individuals inside and outside the college institution. It’s important to spread awareness to the general public about opioid addiction, pharmaceutical corruption, and the overall health (well-being) of individuals who live in present day American society.
This paper is organized into numerous sections detailing the history and mass production of pharmaceutical opioids within the United States. The author then focuses on the drug OxyContin for its role within the opioid epidemic and gives the reader a close description of its manufacturer\u27s corrupted tactics. Some sections are broken down into more subdivision portions to help the reader understand the information in further depth. The full contents can be seen on page four. The content page also acts as a mini summary of the entire paper
Cosmological Properties of a Gauged Axion
We analyze the most salient cosmological features of axions in extensions of
the Standard Model with a gauged anomalous extra U(1) symmetry. The model is
built by imposing the constraint of gauge invariance in the anomalous effective
action, which is extended with Wess-Zumino counterterms. These generate
axion-like interactions of the axions to the gauge fields and a gauged shift
symmetry. The scalar sector is assumed to acquire a non-perturbative potential
after inflation, at the electroweak phase transition, which induces a mixing of
the Stuckelberg field of the model with the scalars of the electroweak sector,
and at the QCD phase transition. We discuss the possible mechanisms of
sequential misalignments which could affect the axions of these models, and
generated, in this case, at both transitions. We compute the contribution of
these particles to dark matter, quantifying their relic densities as a function
of the Stuckelberg mass. We also show that models with a single anomalous U(1)
in general do not account for the dark energy, due to the presence of mixed
U(1)-SU(3) anomalies.Comment: 29 pages, 5 figures. Revised version, accepted by Phys. Rev.
Magneto-Acoustic Waves of Small Amplitude in Optically Thin Quasi-Isentropic Plasmas
The evolution of quasi-isentropic magnetohydrodynamic waves of small but
finite amplitude in an optically thin plasma is analyzed. The plasma is assumed
to be initially homogeneous, in thermal equilibrium and with a straight and
homogeneous magnetic field frozen in. Depending on the particular form of the
heating/cooling function, the plasma may act as a dissipative or active medium
for magnetoacoustic waves, while Alfven waves are not directly affected. An
evolutionary equation for fast and slow magnetoacoustic waves in the single
wave limit, has been derived and solved, allowing us to analyse the wave
modification by competition of weakly nonlinear and quasi-isentropic effects.
It was shown that the sign of the quasi-isentropic term determines the scenario
of the evolution, either dissipative or active. In the dissipative case, when
the plasma is first order isentropically stable the magnetoacoustic waves are
damped and the time for shock wave formation is delayed. However, in the active
case when the plasma is isentropically overstable, the wave amplitude grows,
the strength of the shock increases and the breaking time decreases. The
magnitude of the above effects depends upon the angle between the wave vector
and the magnetic field. For hot (T > 10^4 K) atomic plasmas with solar
abundances either in the interstellar medium or in the solar atmosphere, as
well as for the cold (T < 10^3 K) ISM molecular gas, the range of temperature
where the plasma is isentropically unstable and the corresponding time and
length-scale for wave breaking have been found.Comment: 14 pages, 10 figures. To appear in ApJ January 200
Commercial Property Rent Dynamics in U.S. Metropolitan Areas: An Examination of Office, Industrial, Flex and Retail Space
This paper is concerned with the market rental rate for space offered by commercial property and how that rental rate evolves over time. Rental rates reflect the value of the services provided by the property and can have a significant impact on the ability of its owners to make monthly debt obligations. We investigate commercial property rent dynamics for 34 large metropolitan areas in the U.S. The dynamics are studied from the second quarter of 1990 through the second quarter of 2009 and the results are compared across four property types or uses (office, industrial, flex, and retail). There is substantial heterogeneity in both the long and short run responses to changing demand and supply conditions. In general, the office market is the slowest to adjust back towards equilibrium while industrial and flex markets adjust back to the long run equilibrium very quickly. For industrial and office types, the speed of adjustment is substantially faster within quality segments and is strongest for grade A properties
Some Phenomenology of Intersecting D-Brane Models
We present some phenomenology of a new class of intersecting D-brane models.
Soft SUSY breaking terms for these models are calculated in the u - moduli
dominant SUSY breaking approach (in type IIA). In this case, the dependence of
the soft terms on the Yukawas and Wilson lines drops out. These soft terms have
a different pattern compared to the usual heterotic string models.
Phenomenological implications for dark matter are discussed.Comment: 29 pages, 1 figure, References adde
Cell-autonomous inhibition of alpha 7-containing nicotinic acetylcholine receptors prevents death of parasympathetic neurons during development
Neurotrophic molecules are key retrograde influences of cell survival in the developing nervous system, but other influences such as activity are also emerging as important factors. In the avian ciliary ganglion, half the neurons are eliminated between embryonic day 8 (E8) and E14, but it is not known how cell death is initiated. Because systemic application of alpha7-nicotinic acetylcholine receptor (nAChR) antagonists prevents this cell loss, we examined differences in receptor densities and responses of intracellular calcium to nicotine using the calcium-sensitive dye fura-2. In addition, we determined whether cell-autonomous inhibition of alpha7 activation in neurons prevented cell death. E8 neurons are heterogeneous with respect to alpha7-nAChR density, which leads to large increases in [Ca2+]i in some neurons; E8 neurons also exhibit a slower rate of Ca2+ decay after nicotinic stimulation than E13 neurons. Expressing alpha-bungarotoxin that is tethered to the membrane by a glycosylphosphatidylinositol linkage (GPIalpha btx) in ciliary ganglion neurons with the retroviral vector RCASBP(A) blocks increases in intracellular calcium induced by nicotine through alpha7-nAChRs and prevents neurons from dying. Expression of GPIalpha btx in surrounding non-neural tissues, but not in neurons, does not prevent cell loss. Furthermore, the GPIalpha btx is not efficiently expressed in the accessory oculomotor neurons, eliminating preganglionic inputs as another site for action of the antagonist. These results support the hypothesis that cholinergic inputs facilitate cell death in the developing autonomic nervous system by activating alpha7-nAChRs, possibly by leading to increases in intracellular calcium that exceed the threshold for cell survival
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