11,510 research outputs found
Epigenetic aberrations and cancer
The correlation between epigenetic aberrations and disease underscores the importance of epigenetic mechanisms. Here, we review recent findings regarding chromatin modifications and their relevance to cancer
THE IMPACT OF ELIMINATION OF THE U.S. ORANGE JUICE TARIFF ON THE MARKET FOR PROCESSED ORANGE PRODUCTS
International Relations/Trade,
Market Forces and Price Ceilings: A Classroom Experiment
The effect of price controls on competitive equilibrium is a standard topic in many undergraduate economics courses. This classroom experiment demonstrates the effect of rent control (price ceilings) on the market for apartments. As participants in the experiment, students experience the effect of a price ceiling as buyers (renters) and sellers (landlords). The classroom-posted offer market exhibits a shortage under a binding price ceiling. Further, we explore a secondary response to rent control. When given the opportunity, landlords lower the quality of the apartments by reducing maintenance expenditures under the price ceiling, thus moving the market back to equilibrium. Since many students are themselves renters, they should relate to changes in quality due to lower maintenance by landlords. This experiment will stimulate discussion on market forces and on public policy aimed at restricting prices.
Doppelganger defects
We study k-defects - topological defects in theories with more than two
derivatives and second-order equations of motion - and describe some striking
ways in which these defects both resemble and differ from their analogues in
canonical scalar field theories. We show that, for some models, the homotopy
structure of the vacuum manifold is insufficient to establish the existence of
k-defects, in contrast to the canonical case. These results also constrain
certain families of DBI instanton solutions in the 4-dimensional effective
theory. We then describe a class of k-defect solutions, which we dub
doppelgangers, that precisely match the field profile and energy density of
their canonical scalar field theory counterparts. We give a complete
characterization of Lagrangians which admit doppelganger domain walls. By
numerically computing the fluctuation eigenmodes about domain wall solutions,
we find different spectra for doppelgangers and canonical walls, allowing us to
distinguish between k-defects and the canonical walls they mimic. We search for
doppelgangers for cosmic strings by numerically constructing solutions of DBI
and canonical scalar field theories. Despite investigating several examples, we
are unable to find doppelganger cosmic strings, hence the existence of
doppelgangers for defects with codimension >1 remains an open question.Comment: 27 pages, 4 figure
The Effect Demographics Have On The Demand For Orange Juice
This paper investigates how the demand for orange juice is affected by the demographics of consumers. There are many variables in the orange juice demand equation and demographics are only one. Demographic variables are important in determining the tastes and preferences of different regions. The data that has been collected is weekly data over a two year period of time. The seemingly unrelated regression method will be used to examine the data. This project will be beneficial to orange juice advertising firms and companies that sell orange juice.Food Consumption/Nutrition/Food Safety, Marketing,
When can gravitational-wave observations distinguish between black holes and neutron stars?
Gravitational-wave observations of compact binaries have the potential to
uncover the distribution of masses and angular momenta of black holes and
neutron stars in the universe. The binary components' physical parameters can
be inferred from their effect on the phasing of the gravitational-wave signal,
but a partial degeneracy between the components' mass ratio and their angular
momenta limits our ability to measure the individual component masses. At the
typical signal amplitudes expected by the Advanced Laser Interferometer
Gravitational-wave Observatory (signal-to-noise ratios between 10 and 20), we
show that it will in many cases be difficult to distinguish whether the
components are neutron stars or black holes. We identify when the masses of the
binary components could be unambiguously measured outside the range of current
observations: a system with a chirp mass M
would unambiguously contain the smallest-mass neutron star observed, and a
system with \mathcal{M} \ge 2.786 \Msun must contain a black hole. However,
additional information would be needed to distinguish between a binary
containing two 1.35 M neutron stars and an exotic
neutron-star--black-hole binary. We also identify those configurations that
could be unambiguously identified as black-hole binaries, and show how the
observation of an electromagnetic counterpart to a neutron-star--black-hole
binary could be used to constrain the black-hole spin.Comment: 5 pages, 4 figures. Final version to be published in Ap.J.Let
Long Term Adr Performance: How Do Regional Issues Listed on the NYSE Compare to Us and Regional Index Returns?
This study examines the long-term performance of Asia Pacific, European, and Latin American ADRs versus the S&P500 and their respective regional indexes from 1990-2010. The sample was dividend by stable markets (1990s) and volatile markets (2000s). We find that, when analyzed in total, regional indexes perform similarly to the S&P500. However, the Asia Pacific and Latin America regions do offer diversification benefits individually. Furthermore, the ADRs from each region underperform in stable markets (1990s) and outperform in volatile markets (2000s) leading to great diversification benefits
Magnetic Wreaths and Cycles in Convective Dynamos
Solar-type stars exhibit a rich variety of magnetic activity. Seeking to
explore the convective origins of this activity, we have carried out a series
of global 3D magnetohydrodynamic (MHD) simulations with the anelastic spherical
harmonic (ASH) code. Here we report on the dynamo mechanisms achieved as the
effects of artificial diffusion are systematically decreased. The simulations
are carried out at a nominal rotation rate of three times the solar value
(3), but similar dynamics may also apply to the Sun. Our previous
simulations demonstrated that convective dynamos can build persistent toroidal
flux structures (magnetic wreaths) in the midst of a turbulent convection zone
and that high rotation rates promote the cyclic reversal of these wreaths. Here
we demonstrate that magnetic cycles can also be achieved by reducing the
diffusion, thus increasing the Reynolds and magnetic Reynolds numbers. In these
more turbulent models, diffusive processes no longer play a significant role in
the key dynamical balances that establish and maintain the differential
rotation and magnetic wreaths. Magnetic reversals are attributed to an
imbalance in the poloidal magnetic induction by convective motions that is
stabilized at higher diffusion levels. Additionally, the enhanced levels of
turbulence lead to greater intermittency in the toroidal magnetic wreaths,
promoting the generation of buoyant magnetic loops that rise from the deep
interior to the upper regions of our simulated domain. The implications of such
turbulence-induced magnetic buoyancy for solar and stellar flux emergence are
also discussed.Comment: 21 pages, 16 figures, accepted for publication in Ap
On choosing the start time of binary black hole ringdown
The final stage of a binary black hole merger is ringdown, in which the
system is described by a Kerr black hole with quasinormal mode perturbations.
It is far from straightforward to identify the time at which the ringdown
begins. Yet determining this time is important for precision tests of the
general theory of relativity that compare an observed signal with quasinormal
mode descriptions of the ringdown, such as tests of the no-hair theorem. We
present an algorithmic method to analyze the choice of ringdown start time in
the observed waveform. This method is based on determining how close the strong
field is to a Kerr black hole (Kerrness). Using numerical relativity
simulations, we characterize the Kerrness of the strong-field region close to
the black hole using a set of local, gauge-invariant geometric and algebraic
conditions that measure local isometry to Kerr. We produce a map that
associates each time in the gravitational waveform with a value of each of
these Kerrness measures; this map is produced by following outgoing null
characteristics from the strong and near-field regions to the wave zone. We
perform this analysis on a numerical relativity simulation with parameters
consistent with GW150914- the first gravitational wave detection. We find that
the choice of ringdown start time of after merger used in the
GW150914 study to test general relativity corresponds to a high dimensionless
perturbation amplitude of in the strong-field
region. This suggests that in higher signal-to-noise detections, one would need
to start analyzing the signal at a later time for studies that depend on the
validity of black hole perturbation theory.Comment: 23+4 pages, 22 figure
Whole body active warm up and inspiratory muscle warm up do not improve running performance when carrying thoracic loads
Whole body active warm ups (AWU) and inspiratory muscle warm up (IMW) prior to exercise improves performance on some endurance exercise tasks. This study investigated the effects of AWU with and without IMW upon 2.4 km running time-trial performance while carrying a 25 kg backpack, a common task and backpack load in physically demanding occupations. Participants (n = 9) performed five 2.4 km running time-trials with a 25 kg thoracic load preceded in random order by 1) IMW comprising 2 x 30 inspiratory efforts against a pressure-threshold load of 40 % maximal inspiratory pressure (PImax), 2) 10 min unloaded running (AWU) at lactate turnpoint (10.33 ± 1.58 km·h-1), 3) placebo IMW (PLA) comprising five min breathing using a sham device, 4) AWU+IMW and 5) AWU+PLA. Pooled baseline PImax was similar between trials and increased by 7% and 6% following IMW and AWU+IMW (P0.05). Time-trial performance was not different between any trials. Whole body AWU and IMW performed alone or combination have no ergogenic effect upon high intensity, short duration performance when carrying a 25 kg load in a backpack.N/
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