4,761 research outputs found
Late Light Curves of Normal Type Ia Supernovae
We present late-epoch optical photometry (BVRI) of seven
normal/super-luminous Type Ia supernovae: SN 2000E, SN 2000ce, SN 2000cx, SN
2001C, SN 2001V, SN 2001bg, SN 2001dp. The photometry of these objects was
obtained using a template subtraction method to eliminate galaxy light
contamination during aperture photometry. We show the optical light curves of
these supernovae out to epochs of up to ~640 days after the explosion of the
supernova. We show a linear decline in these data during the epoch of 200-500
days after explosion with the decline rate in the B,V,& R bands equal to about
1.4 mag/100 days, but the decline rate of the I-band is much shallower at 0.94
mag/100 days.Comment: 33 pages, 11 figures, Accepted for publication in The Astronomical
Journa
Efficient multiple time scale molecular dynamics: using colored noise thermostats to stabilize resonances
Multiple time scale molecular dynamics enhances computational efficiency by
updating slow motions less frequently than fast motions. However, in practice
the largest outer time step possible is limited not by the physical forces but
by resonances between the fast and slow modes. In this paper we show that this
problem can be alleviated by using a simple colored noise thermostatting scheme
which selectively targets the high frequency modes in the system. For two
sample problems, flexible water and solvated alanine dipeptide, we demonstrate
that this allows the use of large outer time steps while still obtaining
accurate sampling and minimizing the perturbation of the dynamics. Furthermore,
this approach is shown to be comparable to constraining fast motions, thus
providing an alternative to molecular dynamics with constraints.Comment: accepted for publication by the Journal of Chemical Physic
Near Infrared Spectra of Type Ia Supernovae
We report near infrared (NIR) spectroscopic observations of twelve
``Branch-normal'' Type Ia supernovae (SNe Ia) which cover the wavelength region
from 0.8-2.5 microns. Our sample more than doubles the number of SNe Ia with
published NIR spectra within three weeks of maximum light. The epochs of
observation range from thirteen days before maximum light to eighteen days
after maximum light. A detailed model for a Type Ia supernovae is used to
identify spectral features. The Doppler shifts of lines are measured to obtain
the velocity and, thus, the radial distribution of elements.
The NIR is an extremely useful tool to probe the chemical structure in the
layers of SNe Ia ejecta. This wavelength region is optimal for examining
certain products of the SNe Ia explosion that may be blended or obscured in
other spectral regions. We identify spectral features from MgII, CaII, SiII,
FeII, CoII, NiII and possibly MnII. We find no indications for hydrogen, helium
or carbon in the spectra. The spectral features reveal important clues about
the physical characteristics of SNe Ia. We use the features to derive upper
limits for the amount of unburned matter, to identify the transition regions
from explosive carbon to oxygen burning and from partial to complete silicon
burning, and to estimate the level of mixing during and after the explosion.Comment: 44 pages, 7 figures, 3 tables, accepted by Ap
Uniformity of V minus Near Infrared Color Evolution of Type Ia Supernovae, and Implications for Host Galaxy Extinction Determination
From an analysis of SNe 1972E, 1980N, 1981B, 1981D, 1983R, 1998bu, 1999cl,
and 1999cp we find that the intrinsic V-K colors of Type Ia SNe with
multi-color light curve shape (MLCS) parameter -0.4 < Delta < +0.2 suggest a
uniform color curve. V-K colors become bluer linearly with time from roughly
one week before B-band maximum until one week after maximum, after which they
redden linearly until four weeks after maximum. V-H colors exhibit very similar
color evolution. V-J colors exhibit slightly more complex evolution, with
greater scatter. The existence of V minus near infrared color relations allows
the construction of near infrared light curve templates that are an improvement
on those of Elias et al. (1985).
We provide optical BVRI and infrared JHK photometry of the Type Ia supernovae
1999aa, 1999cl, and 1999cp. SN 1999aa is an overluminous "slow decliner" (with
Delta = -0.47 mag). SN 1999cp is a moderately bright SN unreddened in its host.
SN 1999cl is extremely reddened in its host. The V minus near infrared colors
of SN 1999cl yield A_V = 2.01 +/- 0.11 mag. This leads to a distance for its
host galaxy (M 88) in agreement with other distance measurements for members of
the Virgo cluster.Comment: 57 pages, 13 postscript figures, to appear in the August 20, 2000,
issue of the Astrophysical Journal. Contains updated references and a number
of minor corrections dealt with when page proofs were correcte
A Mi\u27kmaq First Nation cosmology: investigating the practice of contemporary Aboriginal Traditional Medicine in dialogue with counselling – toward an Indigenous therapeutics
This paper explores from a Mi’kmaq and Aboriginal standpoint foundational knowledge in Indigenous therapeutics. Based on an eco-social-psycho-spiritual way of working, the article proposes Indigenous cultural models that open a window to a rich cultural repository of meanings associated with Indigenous cosmology, ontology and epistemology. The three layers of meaning, theory and practice within the symbolic ‘Medicine Lodge’ or ‘Place of The Dreaming’ give rise to ways of working that are deeply integrative and wholistic. These forms of Indigenous theory and practice have much to offer the counselling and complimentary health professions
Extended polarized semiclassical model for quantum-dot cavity QED and its application to single-photon sources
We present a simple extension of the semi-classical model for a two-level
system in a cavity, in order to incorporate multiple polarized transitions,
such as those appearing in neutral and charged quantum dots (QDs), and two
nondegenerate linearly polarized cavity modes. We verify the model by exact
quantum master equation calculations, and experimentally using a neutral QD in
a polarization non-degenerate micro-cavity, in both cases we observe excellent
agreement. Finally, the usefulness of this approach is demonstrated by
optimizing a single-photon source based on polarization postselection, where we
find an increase in the brightness for optimal polarization conditions as
predicted by the model.Comment: 8 pages, for simple code see https://doi.org/10.5281/zenodo.347666
Electro-optic polarization tuning of microcavities with a single quantum dot
We present an oxide aperture microcavity with embedded quantum dots that
utilizes a three contact design to independently tune the quantum dot
wavelength and birefringence of the cavity modes. A polarization splitting
tuning of 5 GHz is observed. For typical microcavity polarization
splittings, the method can be used to achieve perfect polarization degeneracy
that is required for many polarization-based implementations of photonic
quantum gates. The embedded quantum dot wavelength can be tuned into resonance
with the cavity, independent of the polarization tuning
Increasing Campus Sense of Belonging through LLC Participation: To Gems Camp We Go
Gemstone seeks to develop students’ research and collaboration skills, foster leadership opportunities, and provide a sense of belonging on a large campus utilizing the Best Practices Model (BPM) and a variety of high impact practices (HIPs), like a Gemstone-specific orientation program called Gems Camp. While studies have demonstrated that LLCs increase students’ sense of belonging, the goal of this study is to explicitly test via propensity score matching if (a) enrollment in the Gemstone Honors Program increases sense of belonging compared to university students not in Gemstone and (b) attendance at Gems Camp increases sense of belonging in Gemstone students. Gemstone students (N=221) had an increased sense of belonging compared to matched university students (N=221). Moreover, Gemstone students who attended Gems Camp (N=92) had an increased sense of belonging compared to matched Gemstone students who did not attend Gems Camp (N=92). In conclusion, the Gemstone Honors Program is an example of an LLC with scaffolded high impact practices, such as intentional first year programming, undergraduate research, and collaborative projects, that promotes an increase in students’ sense of belonging, providing a model for other LLCs to consider in their programming efforts
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