5,882 research outputs found
Bioreceptive interfaces for biophilic urban resilience
The emerging field of Biodesign sees living organisms as embedded
in the design process to create bio-generated materials
and artefacts. To support the growth and maintenance of
these organisms, designers can adopt a Bioreceptive Design
(BD) approach, recently defined as a design approach occurring
every time materials or artefacts are intentionally designed
to be colonized by life forms. Through this approach,
the inert counterpart undergoes specific studies to reach
the best bioreceptive potential for the designated life form,
also considering the environment in which the artifact will be
placed. In urban environments, BD examples tackle vegetation
to create greener spaces and provide phytoremediation
for better air quality and biodiversity in the built environment,
in the wider view of nature-based solutions and climatic transitions
of cities.
This study addresses the possibility of developing bioreceptive
interfaces for mosses and lichens to respond to biophilic
and regenerative sustainability needs in urban contexts.
These organisms have contributed as pioneers, during the
evolution of life on our Planet, in the formation and regulation
of soil and atmosphere; moreover, they are currently used in
biomonitoring actions, also contributing to the environmental
awareness of the built environment. The paper proposes BD as
a design approach of mutual interest, aiming at responding to
the host needs and preferable environmental conditions, serving
multiple species that act as co-authors of an open-ended
design, increasing urban biodiversity, and providing resilient, restorative,
and regenerative environments.
In particular, we present some of the results of an interdisciplinary
research through design, born from the collaboration
between design and biology, aiming both to bring sustainable
and innovative solutions for the Biodesign and architecture
sectors, but also to positively affect biological activities of biomonitoring
and citizen awareness. From the design perspective,
BD is applied for the selection of those material features
that match the needs of the selected organism (e.g., porosity,
color). Moreover, the use of Computational Design has played
a crucial role in designing and prototyping bioinspired, organic
shapes and textures. From a biological perspective, the research
compares different methodologies for the bio-colonization
of artefacts to obtain the best results for the timing and
survival of the organisms. The prototypes were therefore exposed
open-air with no protection or superficial treatments in
a highly colonized area (from mosses and lichens), favoring the
attachment of spores and propagules on the surfaces. On the
other hand, some prototypes were used to test the transplant
of the organisms as an alternative and faster possibility, also
suitable for interior design.
This study points out how BD can be applicable when designing
for the living, making clear the designer’s possibilities
for adopting this approach: ranging from material design to biomimicry,
designing for not-only-human users, considering the
host’s needs and preferable growth conditions, adopting a multispecies
design approach while suggesting new relationships
among biotic and abiotic agents. The paper highlights how BD
can provide sustainable, low-maintenance, and regenerative
nature-based solutions to foster resilient urban environments
Medium Modification of The Pion-Pion Interaction at Finite Density
We discuss medium modifications of the unitarized pion-pion interaction in
the nuclear medium. We incorporate both the effects of chiral symmetry
restoration and the influence of collective nuclear pionic modes originating
from the p-wave coupling of the pion to delta-hole configurations. We show in
particular that the dropping of the sigma meson mass significantly enhances the
low energy structure created by the in-medium collective pionic modes.Comment: 26 pages, 7 figures included, Latex fil
Optical and Infrared Photometry of the Unusual Type Ia Supernova 2000cx
We present optical and infrared photometry of the unusual Type Ia supernova
2000cx. With the data of Li et al. (2001) and Jha (2002), this comprises the
largest dataset ever assembled for a Type Ia SN, more than 600 points in
UBVRIJHK. We confirm the finding of Li et al. regarding the unusually blue B-V
colors as SN 2000cx entered the nebular phase. Its I-band secondary hump was
extremely weak given its B-band decline rate. The V minus near infrared colors
likewise do not match loci based on other slowly declining Type Ia SNe, though
V-K is the least ``abnormal''. In several ways SN 2000cx resembles other slow
decliners, given its B-band decline rate (Delta m_15(B) = 0.93), the appearance
of Fe III lines and weakness of Si II in its pre-maximum spectrum, the V-K
colors and post-maximum V-H colors. If the distance modulus derived from
Surface Brightness Fluctuations of the host galaxy is correct, we find that the
rate of light increase prior to maximum, the characteristics of the bolometric
light curve, and the implied absolute magnitude at maximum are all consistent
with a sub-luminous object with Delta m_15(B) ~ 1.6-1.7 having a higher than
normal kinetic energy.Comment: 46 pages, 17 figures, to be published in Publications of the
Astronomical Society of the Pacifi
Ultraviolet Light Curves of Supernovae with Swift Uvot
We present ultravioliet (UV) observations of supernovae (SNe) obtained with
the UltraViolet/Optical Telescope (UVOT) on board the Swift spacecraft. This is
the largest sample of UV light curves from any single instrument and covers all
major SN types and most subtypes. The UV light curves of SNe Ia are fairly
homogenous while SNe Ib/c and IIP show more variety in their light curve
shapes. The UV-optical colors clearly differentiate SNe Ia and IIP,
particularly at early times. The color evolution of SNe IIP, however, makes
their colors similar to SNe Ia at about 20 days after explosion. SNe Ib/c are
shown to have varied UV-optical colors. The use of UV colors to help type SNe
will be important for high redshift SNe discovered in optical observations.
These data can be added to ground based optical and near infrared data to
create bolometric light curves of individual objects and as checks on generic
bolometric corrections used in the absence of UV data. This sample can also be
compared with rest-frame UV observations of high redshift SNe observed at
optical wavelengths.Comment: 11 pages, including 8 figures. Submitted to A
The ESSENCE Supernova Survey: Survey Optimization, Observations, and Supernova Photometry
We describe the implementation and optimization of the ESSENCE supernova
survey, which we have undertaken to measure the equation of state parameter of
the dark energy. We present a method for optimizing the survey exposure times
and cadence to maximize our sensitivity to the dark energy equation of state
parameter w=P/rho c^2 for a given fixed amount of telescope time. For our
survey on the CTIO 4m telescope, measuring the luminosity distances and
redshifts for supernovae at modest redshifts (z~0.5 +- 0.2) is optimal for
determining w. We describe the data analysis pipeline based on using reliable
and robust image subtraction to find supernovae automatically and in near
real-time. Since making cosmological inferences with supernovae relies
crucially on accurate measurement of their brightnesses, we describe our
efforts to establish a thorough calibration of the CTIO 4m natural photometric
system. In its first four years, ESSENCE has discovered and spectroscopically
confirmed 102 type Ia SNe, at redshifts from 0.10 to 0.78, identified through
an impartial, effective methodology for spectroscopic classification and
redshift determination. We present the resulting light curves for the all type
Ia supernovae found by ESSENCE and used in our measurement of w, presented in
Wood-Vasey et al, 2007.Comment: Submitted to ApJ. Companion paper to Wood-Vasey et al (2007).
Electronic tables available at http://www.ctio.noao.edu/essence/wresult
Quasi-Elastic Scattering in the Inclusive (He, t) Reaction
The triton energy spectra of the charge-exchange C(He,t) reaction
at 2 GeV beam energy are analyzed in the quasi-elastic nucleon knock-out
region. Considering that this region is mainly populated by the charge-exchange
of a proton in He with a neutron in the target nucleus and the final proton
going in the continuum, the cross-sections are written in the distorted-wave
impulse approximation. The t-matrix for the elementary exchange process is
constructed in the DWBA, using one pion- plus rho-exchange potential for the
spin-isospin nucleon- nucleon potential. This t-matrix reproduces the
experimental data on the elementary pn np process. The calculated
cross-sections for the C(He,t) reaction at to triton
emission angle are compared with the corresponding experimental data, and are
found in reasonable overall accord.Comment: 19 pages, latex, 11 postscript figures available at
[email protected], submitted to Phy.Rev.
Near-Ultraviolet Properties of a Large Sample of Type Ia Supernovae as Observed with the Swift UVOT
We present ultraviolet (UV) and optical photometry of 26 Type Ia supernovae
(SNe~Ia) observed from March 2005 to March 2008 with the NASA {\it Swift}
Ultraviolet and Optical Telescope (UVOT). The dataset consists of 2133
individual observations, making it by far the most complete study of the UV
emission from SNe~Ia to date. Grouping the SNe into three subclasses as derived
from optical observations, we investigate the evolution of the colors of these
SNe, finding a high degree of homogeneity within the normal subclass, but
dramatic differences between that group and the subluminous and SN 2002cx-like
groups. For the normal events, the redder UV filters on UVOT (, ) show
more homogeneity than do the bluer UV filters (, ). Searching for
purely UV characteristics to determine existing optically based groupings, we
find the peak width to be a poor discriminant, but we do see a variation in the
time delay between peak emission and the late, flat phase of the light curves.
The UV light curves peak a few days before the band for most subclasses (as
was previously reported by Jha et al. 2006a), although the SN 2002cx-like
objects peak at a very early epoch in the UV. That group also features the
bluest emission observed among SNe~Ia. As the observational campaign is
ongoing, we discuss the critical times to observe, as determined by this study,
in order to maximize the scientific output of future observations.Comment: Accepted to Astrophysical Journa
Faint Thermonuclear Supernovae from AM Canum Venaticorum Binaries
Helium that accretes onto a Carbon/Oxygen white dwarf in the double white
dwarf AM Canum Venaticorum (AM CVn) binaries undergoes unstable thermonuclear
flashes when the orbital period is in the 3.5-25 minute range. At the shortest
orbital periods (and highest accretion rates, Mdot > 10^-7 Msol/yr), the
flashes are weak and likely lead to the Helium equivalent of classical nova
outbursts. However, as the orbit widens and Mdot drops, the mass required for
the unstable ignition increases, leading to progressively more violent flashes
up to a final flash with Helium shell mass ~ 0.02-0.1 Msol. The high pressures
of these last flashes allow the burning to produce the radioactive elements
48Cr, 52Fe, and 56Ni that power a faint (M_V in the range of -15 to -18) and
rapidly rising (few days) thermonuclear supernova. Current galactic AM CVn
space densities imply one such explosion every 5,000-15,000 years in 10^11 Msol
of old stars (~ 2-6% of the Type Ia rate in E/SO galaxies). These ".Ia"
supernovae (one-tenth as bright for one-tenth the time as a Type Ia supernovae)
are excellent targets for deep (e.g. V=24) searches with nightly cadences,
potentially yielding an all-sky rate of 1,000 per year.Comment: To appear in The Astrophysical Journal Letters; 4 pages, 3 figures.
Expected rates somewhat reduced due to lowered galactic density of AM CVn
binarie
Search for anomalous t t-bar production in the highly-boosted all-hadronic final state
A search is presented for a massive particle, generically referred to as a
Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are
sufficiently massive to produce highly Lorentz-boosted top quarks, which yield
collimated decay products that are partially or fully merged into single jets.
The analysis uses new methods to analyze jet substructure, providing
suppression of the non-top multijet backgrounds. The analysis is based on a
data sample of proton-proton collisions at a center-of-mass energy of 7 TeV,
corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits
in the range of 1 pb are set on the product of the production cross section and
branching fraction for a topcolor Z' modeled for several widths, as well as for
a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any
enhancement in t t-bar production beyond expectations of the standard model for
t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version
includes a minor typo correction that will be submitted as an erratu
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