1,170 research outputs found
Exposure to substance use prevention messages among adolescents. Short report.
This issue of The CBHSQ Report examines adolescents' exposure to substance use prevention messages using US data from the 2002 to 2015 National Survey on Drug Use and Health (NSDUH). It also uses 2015 NSDUH data to examine exposure to prevention messages by key demographic characteristics. The 2015 estimates are based on a total sample size of 17,000 adolescents aged 12 to 17
Manifestations of Extra Dimensions in a Neutrino Telescope
Theories with large extra dimensions provide the possibility that a flavor
neutrino, localized in a 3+1 brane, can mix with a singlet neutrino living in
the bulk. This mixing leads to unconventional patterns of neutrino matter
oscillations and we examine in details how these oscillations depend upon two
parameters: the brane-bulk coupling and the effective mass of the
flavor neutrino inside matter. We find that high energy GeV)
neutrinos, to be detected by neutrino telescopes, can give signals of
extra dimensions. With a 1 k neutrino telescope extra dimensions with
radius down to can be tested directly, while for smaller radius an
indirect evidence can be established.Comment: 14 pages, 5 figures, added conclusion
Suppressed star formation in circumnuclear regions in Seyfert galaxies
Feedback from black hole activity is widely believed to play a key role in
regulating star formation and black hole growth. A long-standing issue is the
relation between the star formation and fueling the supermassive black holes in
active galactic nuclei (AGNs). We compile a sample of 57 Seyfert galaxies to
tackle this issue. We estimate the surface densities of gas and star formation
rates in circumnuclear regions (CNRs). Comparing with the well-known
Kennicutt-Schmidt (K-S) law, we find that the star formation rates in CNRs of
most Seyfert galaxies are suppressed in this sample. Feedback is suggested to
explain the suppressed star formation rates.Comment: 1 color figure and 1 table. ApJ Letters in pres
Neutrino suppression and extra dimensions: a minimal model
We study flavour neutrinos confined to our 4-dimensional world coupled to one
"bulk" state, i.e. a Kaluza-Klein tower. We discuss the spatial development of
the neutrino disappearance, the possibility of resurgence and the effective
flavour transitions induced in this mechanism. We show that even a simple model
can produce an energy-independent suppression at large distances, and relate
this to experimental data.Comment: 14 pages, 8 figures; the exclusion of sterile neutrinos by
SuperKamiokande is discussed; references adde
The influence of the geomagnetic field and of the uncertainties in the primary spectrum on the development of the muon flux in the atmosphere
In this paper we study the sensitivity of the flux of atmospheric muons to
uncertainties in the primary cosmic ray spectrum and to the treatment of the
geomagnetic field in a calculation. We use the air shower simulation program
AIRES to make the calculation for two different primary spectra and under
several approximations to the propagation of charged particles in the
geomagnetic field. The results illustrate the importance of accurate modelling
of the geomagnetic field effects. We propose a high and a low fit of the proton
and helium fluxes, and calculate the muon fluxes with these different inputs.
Comparison with measurements of the muon flux by the CAPRICE experiment shows a
slight preference for the higher primary cosmic ray flux parametrization.Comment: 24 pages, 13 figures, submitted to Phys.Rev.
Atmospheric neutrino flux from 3-dimensional simulation
The atmospheric muon and neutrino flux have been simulated using the same
approach which successfully accounted for the recent secondary proton, electron
and positron flux measurements in orbit by the AMS experiment. For the muon
flux, a good agreement is obtained with the CAPRICE and HEAT data for altitudes
ranging from sea level up to about 38 km. The general features of the
calculated atmospheric neutrino flux are reported and discussed. The flux
obtained at the Super-Kamiokande experiment location are reported and compared
with other calculations. For low neutrino energies the flux obtained is
significantly smaller than that used in the data analysis of underground
experiment. The simulation results for the SOUDAN experiment site are also
reported.Comment: 33 pages, 27 figures, 12 tables, final version for Phys. Rev.
Matter effects in long baseline experiments, the flavor content of the heaviest (or lightest) neutrino and the sign of Delta m^2
The neutrinos of long baseline beams travel inside the Earth's crust where
the density is approximately rho = 2.8 g cm^-3. If electron neutrinos
participate in the oscillations, matter effects will modify the oscillation
probabilities with respect to the vacuum case. Depending on the sign of Delta
m^2 an MSW resonance will exist for neutrinos or anti-neutrinos with energy
approximately E_nu(res) = 4.7 |\Delta m^2|/(10^-3 eV^2) GeV. For Delta m^2 in
the interval indicated by the Super-Kamiokande experiment this energy range is
important for the proposed long baseline experiments.
For positive Delta m^2 the most important effects of matter are a 9% (25%)
enhancement of the transition probability P(nu_mu -> nu_e) for the KEK to
Kamioka (Fermilab to Minos and CERN to Gran Sasso) beam(s) in the energy region
where the probability has its first maximum, and an approximately equal
suppression of P(antinu_mu -> antinu_e). For negative Delta m^2 the effects for
neutrinos and anti-neutrinos are interchanged. Producing beams of neutrinos and
antineutrinos and measuring the oscillation probabilities for both (nu_mu ->
nu_e) and (antinu_mu -> antinu_e) transitions can solve the sign ambiguity in
the determination of Delta m^2.Comment: Latex, 28 pages, 12 postscript figure
Nuclear Physics with Electroweak Probes
In recent years, the italian theoretical Nuclear Physics community has played
a leading role in the development of a unified approach, allowing for a
consistent and fully quantitative description of the nuclear response to
electromagnetic and weak probes. In this paper I review the main achievements
in both fields, point out some of the open problems, and outline the most
promising prospects.Comment: Invited Talk at the XII Workshop on Theoretical Nuclear Physics in
Italy, Cortona, October 8-10, 200
- …