8,730 research outputs found
Transform-Limited-Pulse Representation of Excitation with Natural Incoherent Light
We study the natural excitation of molecular systems, applicable to, for
example, photosynthetic light-harvesting complexes, by natural incoherent
light. In contrast with the conventional classical models, we show that the
light need not have random character to properly represent the resultant linear
excitation. Rather, thermal excitation can be interpreted as a collection of
individual events resulting from the system's interaction with individual,
deterministic pulsed realizations that constitute the field. The derived
expressions for the individual field realizations and excitation events allow
for a wave function formalism, and therefore constitute a useful calculational
tool to study dynamics following thermal-light excitation. Further, they
provide a route to the experimental determination of natural incoherent
excitation using pulsed laser techniques.Comment: 5 pages, 3 figures, 1 page supplementary information. Comments
welcom
Keeping California cool: Recent cool community developments
In 2006, California introduced the Global Warming Solutions Act (Assembly Bill 32), which requires the state to reduce greenhouse gas emissions to 1990 levels by 2020. "Cool community" strategies, including cool roofs, cool pavements, cool walls and urban vegetation, have been identified as voluntary measures with potential to reduce statewide emissions. In addition, cool community strategies provide co-benefits for residents of California, such as reduced utility bills, improved air quality and enhanced urban livability. To achieve these savings, Lawrence Berkeley National Laboratory (LBNL) has worked with state and local officials, non-profit organizations, school districts, utilities, and manufacturers for 4 years to advance the science and implementation of cool community strategies. This paper summarizes the accomplishments of this program, as well as recent developments in cool community policy in California and other national and international efforts. We also outline lessons learned from these efforts to characterize successful programs and policies to be replicated in the future
Studies of waveform requirements for intermediate mass-ratio coalescence searches with advanced detectors
The coalescence of a stellar-mass compact object into an intermediate-mass
black hole (intermediate mass-ratio coalescence; IMRAC) is an important
astrophysical source for ground-based gravitational-wave interferometers in the
so-called advanced configuration. However, the ability to carry out effective
matched-filter based searches for these systems is limited by the lack of
reliable waveforms. Here we consider binaries in which the intermediate-mass
black hole has mass in the range 24 - 200 solar masses with a stellar-mass
companion having masses in the range 1.4 - 18.5 solar masses. In addition, we
constrain the mass ratios, q, of the binaries to be in the range 1/140 < q <
1/10 and we restrict our study to the case of circular binaries with
non-spinning components. We investigate the relative contribution to the
signal-to-noise ratio (SNR) of the three different phases of the coalescence:
inspiral, merger and ringdown. We show that merger and ringdown contribute to a
substantial fraction of the total SNR over a large portion of the mass
parameter space, although in a limited portion the SNR is dominated by the
inspiral phase. We further identify three regions in the IMRAC mass-space in
which: (i) inspiral-only searches could be performed with losses in detection
rates L in the range 10% < L < 27%, (ii) searches based on inspiral-only
templates lead to a loss in detection rates in the range 27% < L < 50%$, and
(iii) templates that include merger and ringdown are essential to prevent
losses in detection rates greater than 50%. We investigate the effectiveness
with which the inspiral-only portion of the IMRAC waveform space is covered by
comparing several existing waveform families in this regime. Our results
reinforce the importance of extensive numerical relativity simulations of
IMRACs and the need for further studies of suitable approximation schemes in
this mass range.Comment: 10 pages, 3 figure
Verifying the no-hair property of massive compact objects with intermediate-mass-ratio inspirals in advanced gravitational-wave detectors
The detection of gravitational waves from the inspiral of a neutron star or
stellar-mass black hole into an intermediate-mass black hole (IMBH) promises an
entirely new look at strong-field gravitational physics. Gravitational waves
from these intermediate-mass-ratio inspirals (IMRIs), systems with mass ratios
from ~10:1 to ~100:1, may be detectable at rates of up to a few tens per year
by Advanced LIGO/Virgo and will encode a signature of the central body's
spacetime. Direct observation of the spacetime will allow us to use the
"no-hair" theorem of general relativity to determine if the IMBH is a Kerr
black hole (or some more exotic object, e.g. a boson star). Using modified
post-Newtonian (pN) waveforms, we explore the prospects for constraining the
central body's mass-quadrupole moment in the advanced-detector era. We use the
Fisher information matrix to estimate the accuracy with which the parameters of
the central body can be measured. We find that for favorable mass and spin
combinations, the quadrupole moment of a non-Kerr central body can be measured
to within a ~15% fractional error or better using 3.5 pN order waveforms; on
the other hand, we find the accuracy decreases to ~100% fractional error using
2 pN waveforms, except for a narrow band of values of the best-fit non-Kerr
quadrupole moment.Comment: Second version, 12 pages, 5 figures, accepted by PR
Multispace and Multilevel BDDC
BDDC method is the most advanced method from the Balancing family of
iterative substructuring methods for the solution of large systems of linear
algebraic equations arising from discretization of elliptic boundary value
problems. In the case of many substructures, solving the coarse problem exactly
becomes a bottleneck. Since the coarse problem in BDDC has the same structure
as the original problem, it is straightforward to apply the BDDC method
recursively to solve the coarse problem only approximately. In this paper, we
formulate a new family of abstract Multispace BDDC methods and give condition
number bounds from the abstract additive Schwarz preconditioning theory. The
Multilevel BDDC is then treated as a special case of the Multispace BDDC and
abstract multilevel condition number bounds are given. The abstract bounds
yield polylogarithmic condition number bounds for an arbitrary fixed number of
levels and scalar elliptic problems discretized by finite elements in two and
three spatial dimensions. Numerical experiments confirm the theory.Comment: 26 pages, 3 figures, 2 tables, 20 references. Formal changes onl
Characteristics and processing of fps-16/ jimsphere raw radar data
Error analysis of fps-16/jimsphere raw radar dat
Selecting digital filters for application to detailed wind profiles
Selecting digital filters for application to detailed wind profiles - table
Capability of the FPS-16 radar/jimsphere system for direct measurement of vertical air motions
Capability and procedure for direct measurement of vertical air currents using FPS-16 radar/ jimsphere syste
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