108 research outputs found
Twenty Years of Disturbance and Change in Fagatele Bay National Marine Sanctuary, American Samoa
Fagatele Bay National Marine Sanctuary contains a moderately
diverse coral reef community (150 coral species, 259 fish species) that is protected
from most human activities. The coral community was devastated by a
crown-of-thorns starfish invasion in 1979 and has recently been affected by two
major hurricanes (1990 and 1991) and a period of unusually high water temperature
(1994). Long-term monitoring of the sanctuary allows for description of
the effects of these disturbances in the absence of anthropogenic processes. The
crown-of-thorns damaged deeper portions of the coral communities most severely,
whereas the hurricanes and warm water affected shallower portions to
a greater degree. Soon after these disturbances, corals started recruiting abundantly
and the reefs began to recover. This is in contrast to some other areas in
American Samoa, where chronic anthropogenic effects seem to have inhibited
coral recruitment and reef recovery. Fish communities were affected by the habitat
degradation associated with the crown-of-thorns outbreak, but have remained
relatively unchanged ever since
Majorana Neutrino, the Size of Extra Dimensions, and Neutrinoless Double Beta Decay
The problem of Majorana neutrino mass generated in
Arkani-Hamed--Dimopoulos-Dvali model with n extra spatial dimensions is
discussed. Taking into account constraints on neutrino masses coming from
cosmological observations, it is possible to obtain lower limits on the size of
extra dimensions as large as 10^{-6} mm. In the case of n=4 it is easy to lower
the fundamental scale of gravity from the Planck energy to electroweak scale
\~TeV without imposing any additional constraints. A link between the half-life
of neutrinoless double beta decay and the size of extra dimensions is
discussed.Comment: 5 pages, 1 figure, using RevTEX. Units conversion correcte
Holographic dual of the Standard Model on the throat
We apply recent techniques to construct geometries, based on local Calabi-Yau
manifolds, leading to warped throats with 3-form fluxes in string theory, with
interesting structure at their bottom. We provide their holographic dual
description in terms of RG flows for gauge theories with almost conformal
duality cascades and infrared confinement. We describe a model of a throat with
D-branes at its bottom, realizing a 3-family Standard Model like chiral sector.
We provide the explicit holographic dual gauge theory RG flow, and describe the
appearance of the SM degrees of freedom after confinement. As a second
application, we describe throats within throats, namely warped throats with
discontinuous warp factor in different regions of the radial coordinate, and
discuss possible model building applications.Comment: 46 pages, 21 figures, reference adde
Primordial black holes in braneworld cosmologies: astrophysical constraints
In two recent papers we explored the modifications to primordial black hole
physics when one moves to the simplest braneworld model, Randall--Sundrum type
II. Both the evaporation law and the cosmological evolution of the population
can be modified, and additionally accretion of energy from the background can
be dominant over evaporation at high energies. In this paper we present a
detailed study of how this impacts upon various astrophysical constraints,
analyzing constraints from the present density, from the present high-energy
photon background radiation, from distortion of the microwave background
spectrum, and from processes affecting light element abundances both during and
after nucleosynthesis. Typically, the constraints on the formation rate of
primordial black holes weaken as compared to the standard cosmology if black
hole accretion is unimportant at high energies, but can be strengthened in the
case of efficient accretion.Comment: 17 pages RevTeX4 file with three figures incorporated; final paper in
series astro-ph/0205149 and astro-ph/0208299. Minor changes to match version
accepted by Physical Review
Changes on physiological parameters of tambaqui (Colossoma macropomum) fed with diets supplemented with Amazonian fruit Camu camu (Myrciaria dubia)
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Energetic particle influence on the Earth's atmosphere
This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally
galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere
are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere
Dissolved oxygen and ammonia levels in water that affect plasma ionic content and gallbladder bile in silver catfish
Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV
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