1,550 research outputs found
Unsupervised clustering of Type II supernova light curves
As new facilities come online, the astronomical community will be provided
with extremely large datasets of well-sampled light curves (LCs) of transient
objects. This motivates systematic studies of the light curves of supernovae
(SNe) of all types, including the early rising phase. We performed unsupervised
k-means clustering on a sample of 59 R-band Type II SN light curves and find
that our sample can be divided into three classes: slowly-rising (II-S),
fast-rise/slow-decline (II-FS), and fast-rise/fast-decline (II-FF). We also
identify three outliers based on the algorithm. We find that performing
clustering on the first two components of a principal component analysis gives
equivalent results to the analysis using the full LC morphologies. This may
indicate that Type II LCs could possibly be reduced to two parameters. We
present several important caveats to the technique, and find that the division
into these classes is not fully robust and is sensitive to the uncertainty on
the time of first light. Moreover these classes have some overlap, and are
defined in the R-band only. It is currently unclear if they represent distinct
physical classes, and more data is needed to study these issues. However, our
analysis shows that the outliers are actually composed of slowly-evolving SN
IIb, demonstrating the potential use of such methods. The slowly-evolving SNe
IIb may arise from single massive progenitors.Comment: Comments welcome. Fixed small typo
Arithmetic of the Asai L-function for Hilbert Modular Forms.
Arithmetic of the Asai L-function for Hilbert modular forms
Adam Kaye
Chair: Kartik Prassanna
We prove two results on rationality of
special values of the Asai L-function
attached to Hilbert modular forms at
critical points. Such L-functions only
admit critical values when the Hilbert modular form has
non-parallel weight.
Our rationality results generalize
previous work of Shimura on algebraicity.
The first result uses a period defined by
transferring the Hilbert modular form
to a Shimura curve.
The second result uses a period defined
using rational structures on
the coherent cohomology of Hilbert modular
surfaces.
We also give some partial results
towards integrality of such L-values.
Our results are motivated by the study of a
p-adic analog of the Beilinson conjecture,
which is a deep conjecture relating
algebraic cycles (and motivic cohomology) to values
of L-functions.PhDMathematicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/120693/1/adamkaye_1.pd
Dissecting the Gaseous Halos of z~2 Damped Ly Systems with Close Quasar Pairs
We use spectroscopy of close pairs of quasars to study diffuse gas in the
circumgalactic medium (CGM) surrounding a sample of 40 Damped Lya systems
(DLAs). The primary sightline in each quasar pair probes an intervening DLA in
the redshift range 1.6 < z_DLA < 3.6, such that the second quasar sightline
then probes Lya, CII, SiII, and CIV absorption in the CGM transverse to the DLA
to projected distances kpc. Analysis of the Lya profiles in
these CGM sightlines constrains the covering fraction (f_C) of optically thick
HI (having column density N_HI > 10^17.2 cm^-2) to be greater than ~30% within
kpc of DLAs. Strong SiII 1526 absorption with equivalent
width W_1526 > 0.2 Ang occurs with an incidence f_C (W_1526 > 0.2 Ang) =
20(+12/-8)% within kpc, indicating that low-ionization metal
absorption associated with DLAs probes material at a physical distance R_3D <
30 kpc. However, we find that strong CIV 1548 absorption is ubiquitous in these
environments (f_C (W_1548 > 0.2 Ang) = 57(+12/-13)% within
kpc), and in addition exhibits a high degree of kinematic coherence on scales
up to ~175 kpc. We infer that this high-ionization material arises
predominantly in large, quiescent structures extending beyond the scale of the
DLA host dark matter halos rather than in ongoing galactic winds. The Lya
equivalent width in the DLA-CGM is anticorrelated with at >98%
confidence, suggesting that DLAs arise close to the centers of their host halos
rather than on their outskirts. Finally, the average Lya, CII and CIV
equivalent widths are consistent with those measured around z~2 Lyman Break
Galaxies. Assuming that DLAs trace a galaxy population with lower masses and
luminosities, this finding implies that the absorption strength of cool
circumgalactic material has a weak dependence on dark matter halo mass for M_h
< 10^12 M_sun.Comment: Submitted to ApJ. 30 pages, 13 figures, 3 tables, 1 appendix. Uses
emulateapj forma
Jet substructure as a new Higgs search channel at the LHC
It is widely considered that, for Higgs boson searches at the Large Hadron
Collider, WH and ZH production where the Higgs boson decays to b anti-b are
poor search channels due to large backgrounds. We show that at high transverse
momenta, employing state-of-the-art jet reconstruction and decomposition
techniques, these processes can be recovered as promising search channels for
the standard model Higgs boson around 120 GeV in mass.Comment: 4 pages, 3 figure
CLEO Spectroscopy Results
Recent contributions of the CLEO experiment to hadron spectroscopy are
presented.Comment: 6 pages, 4 figures, presented at Beauty 2005, Assisi, Italy, 20--24
June 2005 References further update
Homophobia and heterosexism
âHomophobiaâ is a widely understood term referring to antihomosexual attitudes and practices, but terms such as âhomophobia,â âheterosexism,â and âheteronormativityâ point to different ideas of what âhomosexualâ means, and where opposition to same-sex relations originates. Gayle Rubin, relying on structural anthropology, proposes that it arises as a disciplinary mechanism used by men to exercise control over womenâs reproductive power in families. Gender panic theory focuses particularly on how defensiveness against losing male status and privilege generates homophobia. Sociohistorical theories examine how homophobia increases or decreases according to the symbolic placement of lesbian, gay, bisexual, and transgender people in the social status system. In the early twenty-first century, contradictory trends have led to improved citizenship rights for LGBT people in some countries, while others have reinforced or increased state and social violence against their LGBT populations
Edward Albee: 02-04-1981
Edward Albee was an American playwright, best known for plays such as Whoâs Afraid of Virginia Woolf?, A Delicate Balance, and Seascape. The interview begins with a discussion about creative art and its usefulness in sending messages to an audience. Albee then discusses the different types of theater and how they appeal to different audiences. He continues by talking about the plays he has adapted from books, the criticism heâs received for those adaptions, and a general discussion of why his critics critique him so harshly. The interview concludes with a discourse on film as a medium, the future of playwriting, and a discussion about Albeeâs own plays and his writing process.https://digitalcommons.brockport.edu/writers_videos/1014/thumbnail.jp
Potential for promoting recurrent laryngeal nerve regeneration by remote delivery of viral gene therapy
Objectives/Hypothesis: The aims of this study were to demonstrate the ability to enhance nerve regeneration by remote delivery of a viral vector to the crushed recurrent laryngeal nerve (RLN), to demonstrate the usefulness of a crushed RLN model to test the efficacy of viral gene therapy, and to discuss future potential applications of this approach. Study Design: Animal study. Methods: Adult SpragueâDawley rats were assigned to two groups. In the experimental group, an adenoâassociated viral (AAV) vector carrying a zincâfinger transcription factor, which stimulates endogenous insulinlike growth factor I production (AAV2âTOâ6876vp16), was injected into the crushed RLN. In the control group, an AAV vector carrying the gene for green fluorescent protein was injected into the crushed RLN. Unilateral RLN paralysis was confirmed endoscopically. At 1 week, laryngeal endoscopies were repeated and recorded. Larynges were cryosectioned in 15âÎŒm sections and processed for acetylcholine histochemistry (motor endplates) followed by neurofilament immunoperoxidase (nerve fibers). Percentage nerveâendplate contact (PEC) was determined and compared. Vocal fold motion was evaluated by blinded reviewers using a visual analogue scale (VAS). Results: The difference between PEC on the crushed and uncrushed sides was statistically less in the experimental group (0.54 ± 0.18 vs. 0.30 ± 0.26, P = .0006). The VAS score at 1 week was significantly better in the experimental group ( P = .002). Conclusions: AAV2âTOâ6876vp16 demonstrated a neurotrophic effect when injected into the crushed RLN. The RLN offers a conduit for viral gene therapy to the brainstem that could be useful for the treatment of RLN injury or bulbar motor neuron disease.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90195/1/22436_ftp.pd
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