10,476 research outputs found
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Technological innovation in community housing development: Barriers to energy efficiency
Community housing developers produce affordable housing and jobs for many residents of low-income neighborhoods through the rehabilitation of existing single and multi-family buildings. Typically operating as small, not-for-profits or community-based organizations, the vast numbers of community housing developers creates high coordinating costs of operating jointly to acquire the shared learning needed to implement new techniques, such as those involving energy efficiency. This paper presents a model of technology adoption that suggests that new profitable technologies will be adopted only with low probability and that strategic interaction between potential adopters further reduces the likelihood of adoption. These features result from the ability of potential adopters to postpone the bearing the costs of adoption of new technologies and their ability to share the knowledge of others who have adopted new technologies. These features are particularly characteristic of community housing developers
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National labs working with local communities
In mid September Argonne National Laboratory celebrated its fiftieth anniversary with an open house in which more than 20,000 people toured the site and viewed some 100 demonstrations, exhibits and presentations of the scientific and engineering programs currently being pursued at Argonne. During the course of the open house it became obvious that to even long time residents of the Chicago area the activities of ANL were unknown or unclear. Part of this lack of knowledge about the scientific and engineering research occurring at DOE national laboratories is the remoteness of most research programs from the everyday lives of citizens. It is both the discussions that are remote as well as a remoteness of impacts on ordinary lives that often leads people to miss the exciting research activity occurring nearby. However, at least one research program at Argonne is structured to be purposefully different. The Existing Buildings Efficiency Research (EBER) program pursues its scientific work in concert with architects, engineers, and community developers as they attempt to provide high quality energy efficient, high performance buildings at reasonable cost. Instead of conducting experiments inside the barbed wire fences of secure facilities, technical assistance for the inclusion of DOE tools, techniques, and technologies is offered at the construction site within the community and research results are drawn back as projects are monitored for the performance of the energy conservation measures. In this report several projects at ANL are briefly discussed to give a sense of the possibilities for the laboratory and broader scientific community to work one-on-one with community-based organizations and the agencies that directly serve the needs of low-income neighborhoods
Fireballs Loading and the Blast Wave Model of Gamma Ray Bursts
A simple function for the spectral power
is proposed to model, with 9 parameters, the spectral and temporal evolution of
the observed nonthermal synchrotron power flux from GRBs in the blast wave
model. Here mc is the observed dimensionless photon
energy and is the observing time. Assumptions and an issue of lack of
self-consistency are spelled out. The spectra are found to be most sensitive to
the baryon loading, expressed in terms of the initial bulk Lorentz factor
, and an equipartition term which is assumed to be constant in
time and independent of . Expressions are given for the peak spectral
power at the photon energy of the spectral power peak. A general rule is that the total
fireball particle kinetic energy , where is the deceleration time scale and is the maximum measured bolometric
power output in radiation, during which it is carried primarily by photons with
energy .Comment: 26 pages, including 4 figures, uses epsf.sty, rotate.sty; submitted
to ApJ; revised version with extended introduction, redrawn figures, and
correction
Intense Electromagnetic Outbursts from Collapsing Hypermassive Neutron Stars
We study the gravitational collapse of a magnetized neutron star using a
novel numerical approach able to capture both the dynamics of the star and the
behavior of the surrounding plasma. In this approach, a fully general
relativistic magnetohydrodynamics implementation models the collapse of the
star and provides appropriate boundary conditions to a force-free model which
describes the stellar exterior. We validate this strategy by comparing with
known results for the rotating monopole and aligned rotator solutions and then
apply it to study both rotating and non-rotating stellar collapse scenarios,
and contrast the behavior with what is obtained when employing the
electrovacuum approximation outside the star. The non-rotating electrovacuum
collapse is shown to agree qualitatively with a Newtonian model of the
electromagnetic field outside a collapsing star. We illustrate and discuss a
fundamental difference between the force-free and electrovacuum solutions,
involving the appearance of large zones of electric-dominated field in the
vacuum case. This provides a clear demonstration of how dissipative
singularities appear generically in the non-linear time-evolution of force-free
fluids. In both the rotating and non-rotating cases, our simulations indicate
that the collapse induces a strong electromagnetic transient. In the case of
sub-millisecond rotation, the magnetic field experiences strong winding and the
transient carries much more energy. This result has important implications for
models of gamma-ray bursts.Comment: 28 pages, 20 figures (quality lowered to reduce sizes). Improved
initial data and matching condition results in a lower, but still important,
energy emission. Added appendix with a discussion on effects of transition
laye
Renewable and Tough Poly(l -lactic acid)/Polyurethane Blends Prepared by Dynamic Vulcanization
Melt blending of homopolymers is an effective way to achieve an attractive combination of polymer properties. Dynamic vulcanization of fatty-acid-based polyester polyol with glycerol and poly(l-lactic acid) (PLLA) in the presence of hexamethylene diisocyanate (HDI) was performed with the aim of toughening PLLA. The dynamic vulcanization in an internal mixer led to the formation of a PLLA/PU biobased blend. Melt torque, Fourier transform infrared (FTIR), and gel fraction analysis demonstrated the successful formation of cross-linked polyurethane (PU) inside the PLLA matrix. Scanning electron microscopy (SEM) analysis showed that the PLLA/PU blends exhibit a sea-island morphology. Gel fraction analysis revealed that a rubbery phase was formed inside the PLLA matrix, which was insoluble in chloroform. FTIR analysis of the insoluble part shows the appearance of an absorption band centered at 1758 cm-1, related to the crystalline carbonyl vibration of the PLLA component, thus suggesting the partial involvement of PLLA chains in the cross-linking reaction. The overall content of the PU phase in the blends significantly affected the mechanical properties, thermal stability, and crystallization behavior of the materials. The overall crystallization rate of PLLA was noticeably decreased by the incorporation of PU. At the same time, polarized light optical microscopy (PLOM) analysis revealed that the presence of the PU rubbery phase inside the PLLA matrix promoted PLLA nucleation. With the formation of the PU network, the impact strength showed a remarkable increase while Young's modulus correspondingly decreased. The blends showed slightly reduced thermal stability compared to the neat PLLA
Yet Another Model of Gamma-Ray Bursts
Sari and Piran have demonstrated that the time structure of gamma-ray bursts
must reflect the time structure of their energy release. A model which
satisfies this condition uses the electrodynamic emission of energy by the
magnetized rotating ring of dense matter left by neutron star coalescence; GRB
are essentially fast, high field, differentially rotating pulsars. The energy
densities are large enough that the power appears as an outflowing equilibrium
pair plasma, which produces the burst by baryon entrainment and subsequent
internal shocks. I estimate the magnetic field and characteristic time scale
for its rearrangement, which determines the observed time structure of the
burst. There may be quasi-periodic oscillations at the rotational frequencies,
which are predicted to range up to 5770 Hz (in a local frame). This model is
one of a general class of electrodynamic accretion models which includes the
Blandford and Lovelace model of AGN, and which can also be applied to black
hole X-ray sources of stellar mass. The apparent efficiency of nonthermal
particle acceleration is predicted to be 10--50%, but higher values are
possible if the underlying accretion flow is super-Eddington. Applications to
high energy gamma-ray observations of AGN are briefly discussed.Comment: 21pp, latex, uses aaspp4.st
BATSE Observations of Gamma-Ray Burst Spectra. IV. Time-Resolved High-Energy Spectroscopy
We report on the temporal behavior of the high-energy power law continuum
component of gamma-ray burst spectra with data obtained by the Burst and
Transient Source Experiment. We have selected 126 high fluence and high flux
bursts from the beginning of the mission up until the present. Much of the data
were obtained with the Large Area Detectors, which have nearly all-sky
coverage, excellent sensitivity over two decades of energy and moderate energy
resolution, ideal for continuum spectra studies of a large sample of bursts at
high time resolution. At least 8 spectra from each burst were fitted with a
spectral form that consisted of a low-energy power law, a spectral break at
middle energies and a high-energy continuum. In most bursts (122), the
high-energy continuum was consistent with a power law. The evolution of the
fitted high-energy power-law index over the selected spectra for each burst is
inconsistent with a constant for 34% of the total sample. The sample
distribution of the average value for the index from each burst is fairly
narrow, centered on -2.12. A linear trend in time is ruled out for only 20% of
the bursts, with hard-to-soft evolution dominating the sample (100 events). The
distribution for the total change in the power-law index over the duration of a
burst peaks at the value -0.37, and is characterized by a median absolute
deviation of 0.39, arguing that a single physical process is involved. We
present analyses of the correlation of the power-law index with time, burst
intensity and low-energy time evolution. In general, we confirm the general
hard-to-soft spectral evolution observed in the low-energy component of the
continuum, while presenting evidence that this evolution is different in nature
from that of the rest of the continuum.Comment: 30 pages, with 2 tables and 9 figures To appear in The Astrophysical
Journal, April 1, 199
Neuroprotective effects of mGluR5 activation through the PI3K/Akt pathway and the molecular switch of AMPA receptors
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