The Mass-Richness Relation of MaxBCG Clusters from Quasar Lensing Magnification using Variability

Accurate measurement of galaxy cluster masses is an essential component not only in studies of cluster physics, but also for probes of cosmology. However, different mass measurement techniques frequently yield discrepant results. The SDSS MaxBCG catalog's mass-richness relation has previously been constrained using weak lensing shear, Sunyaev-Zeldovich (SZ), and X-ray measurements. The mass normalization of the clusters as measured by weak lensing shear is >~25% higher than that measured using SZ and X-ray methods, a difference much larger than the stated measurement errors in the analyses. We constrain the mass-richness relation of the MaxBCG galaxy cluster catalog by measuring the gravitational lensing magnification of type I quasars in the background of the clusters. The magnification is determined using the quasars' variability and the correlation between quasars' variability amplitude and intrinsic luminosity. The mass-richness relation determined through magnification is in agreement with that measured using shear, confirming that the lensing strength of the clusters implies a high mass normalization, and that the discrepancy with other methods is not due to a shear-related systematic measurement error. We study the dependence of the measured mass normalization on the cluster halo orientation. As expected, line-of-sight clusters yield a higher normalization; however, this minority of haloes does not significantly bias the average mass-richness relation of the catalog.Comment: 9 pages. Accepted for publication in Ap

The Pitfalls of Empirical Research: Studying Faculty Publication Studies

This article critiques empirical studies by attorneys in the hopes that they will be held to the minimal standards of research competence that are to be found in other academic fields which rely on empirical studies. Because law-trained scholars are notoriously weak at empirical research, this article identifies some of the methodological considerations that should inform empirical research. These fall into four broad categories: (1) problems of conceptualization, (2) problems of measurement, (3) problems of data presentation and analysis, and (4) problems of inference. This article examines all of these considerations in the context of an empirical survey done by Professors Swygert and Gozansky investigating the relationship between law faculty research and tenure

The Pitfalls of Empirical Research: Studying Faculty Publication Studies

This article critiques empirical studies by attorneys in the hopes that they will be held to the minimal standards of research competence that are to be found in other academic fields which rely on empirical studies. Because law-trained scholars are notoriously weak at empirical research, this article identifies some of the methodological considerations that should inform empirical research. These fall into four broad categories: (1) problems of conceptualization, (2) problems of measurement, (3) problems of data presentation and analysis, and (4) problems of inference. This article examines all of these considerations in the context of an empirical survey done by Professors Swygert and Gozansky investigating the relationship between law faculty research and tenure

Probabilities and Proof: Can HLA and Blood Group Testing Prove Paternity?

Advancing medical technology has produced tests which offer the opportunity to resolve paternity disputes with more accuracy than unaided traditional evidentiary techniques are likely to obtain. Because the biology underlying the statistical evidence in paternity cases offers a wealth of previously unavailable information which is certain to revolutionize the adjudication of paternity suits, but it is important that the courts not become so mesmerized by these new sources of evidence that they neglect to subject them to traditional principles of evidence applicable to all testimony. Additionally, for some time scholars have disagreed on the proper application of a probability formula called Bayes\u27 Theorem to questions of proof. Because the evidence yielded by modern serologic tests is inherently quantitative and probabilistic, questions concerning the use of Bayesian calculations in the trial setting will thus have to be decided in these paternity disputes. This article undertakes a critical analysis of the use of probability calculations in paternity cases and of the broader issues implicit in this growing practice. Although the statistical information derived from Human Leucocyte Antigen (HLA) testing should be admissible in paternity cases, the article concludes that no expert, no matter what skill level, can correctly testify to any quantified probability that the defendant in a given case is in fact the father. It reviews the difficulties associated with traditional evidentiary techniques in paternity cases, the nature and appeal of HLA and other modern serologic techniques, and the statistical reasoning which necessarily underlies expert testimony. After reviewing the problems associated with statistical identification evidence, the article concludes by endorsing more suitable alternatives to the methodology currently used in paternity litigation

The QUEST Data Processing Software Pipeline

A program that we call the QUEST Data Processing Software Pipeline has been written to process the large volumes of data produced by the QUEST camera on the Samuel Oschin Schmidt Telescope at the Palomar Observatory. The program carries out both aperture and PSF photometry, combines data from different repeated observations of the same portion of sky, and produces a Master Object Catalog. A rough calibration of the data is carried out. This program, as well as the calibration procedures and quality checks on the output are described.Comment: 17 pages, 1 table, 8 figure

From classical to quantum glass

We study the effects of a transverse magnetic field on the dynamics of the randomly diluted, dipolar coupled, Ising magnet LiHo_(0.167)Y_(0.833)F_4. The transverse field mixes the eigenfunctions of the ground-state Ising doublet with the otherwise inaccessible excited-state levels. We observe a rapid decrease in the characteristic relaxation times, large changes in the spectral form of the relaxation, and a depression of the spin-glass transition temperature with the introduction of quantum fluctuations

Second harmonic light scattering induced by defects in the twist-bend nematic phase of liquid crystal dimers

The nematic twist-bend (NTB) phase, exhibited by certain thermotropic liquid crystalline (LC) dimers, represents a new orientationally ordered mesophase -- the first distinct nematic variant discovered in many years. The NTB phase is distinguished by a heliconical winding of the average molecular long axis (director) with a remarkably short (nanoscale) pitch and, in systems of achiral dimers, with an equal probability to form right- and left-handed domains. The NTB structure thus provides another fascinating example of spontaneous chiral symmetry breaking in nature. The order parameter driving the formation of the heliconical state has been theoretically conjectured to be a polarization field, deriving from the bent conformation of the dimers, that rotates helically with the same nanoscale pitch as the director field. It therefore presents a significant challenge for experimental detection. Here we report a second harmonic light scattering (SHLS) study on two achiral, NTB-forming LCs, which is sensitive to the polarization field due to micron-scale distortion of the helical structure associated with naturally-occurring textural defects. These defects are parabolic focal conics of smectic-like ``pseudo-layers", defined by planes of equivalent phase in a coarse-grained description of the NTB state. Our SHLS data are explained by a coarse-grained free energy density that combines a Landau-deGennes expansion of the polarization field, the elastic energy of a nematic, and a linear coupling between the two

Identification of Non-unitary triplet pairing in a heavy Fermion superconductor UPt_3

A NMR experiment recently done by Tou et al. on a heavy Fermion superconductor UPt$_3$ is interpreted in terms of a non-unitary spin-triplet pairing state which we have been advocating. The proposed state successfully explains various aspects of the seemingly complicated Knight shift behaviors probed for major orientations, including a remarkable d-vector rotation under weak fields. This entitles UPt$_3$ as the first example that a charged many body system forms a spin-triplet odd-par ity pairing at low temperatures and demonstrates unambiguously that the putative spin-orbit coupling in UPt$_3$ is weak.Comment: 4 pages, 2 eps figures, to be published in J. Phys. Soc. Jpn. 67 (1998) No.