Influence of Replicated Subsamples and Subsample Heterogeneity on the Linear Index of Food Selection

In descriptive studies of prey preference, relative abundances of prey often are calculated from a series of replicated subsamples and total sample sizes are estimated rather than counted. When this is done, the apparent statistical power of the linear index of food selection (Li = ri ‐ pi, where ri and piare proportions of prey taxon i in the gut and habitat, respectively) is artificially inflated. Additional biological variability, due either to environmental heterogeneity or to differences in feeding behavior among individual predators, will inflate further the apparent power of the index and also will produce underestimates of the degree of feeding selectivity. To correct for these problems, expressions that allow for subsampling designs and biological heterogeneity are provided for the standard error of the linear index and the associated degrees of freedom. The ratio of observed sampling variance in relative abundance to that expected for random sampling allows measurement of heterogeneity and statistical testing of the null hypothesis of homogeneity.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142170/1/tafs0517.pd

Hubble Advanced Camera for Surveys Observations of the z=6.42 Quasar SDSS 1148+5251: A Leak in the Gunn-Peterson Trough

The Hubble Advanced Camera for Surveys has been used to obtain a narrow-band image of the weak emission peak seen at lambda=7205 A in the Gunn-Peterson Ly beta absorption trough of the highest redshift quasar, SDSS J1148+5251. The emission looks perfectly point-like; there is no evidence for the intervening galaxy that we previously suggested might be contaminating the quasar spectrum. We derive a more accurate astrometric position for the quasar in the two filters and see no indication of gravitational lensing. We conclude that the light in the Ly beta trough is leaking through two unusually transparent, overlapping windows in the IGM absorption, one in the Ly beta forest at z ~ 6 and one in the Ly alpha forest at z ~ 5. If there are significant optical depth variations on velocity scales small compared with our spectral resolution (~150 km/s), the Ly alpha trough becomes more transparent for a given Ly beta optical depth. Such variations can only strengthen our conclusion that the fraction of neutral hydrogen in the IGM increases dramatically at z>6. We argue that the transmission in the Ly beta trough is not only a more sensitive measure of the neutral fraction than is Ly alpha, it also provides a less biased estimator of the neutral hydrogen fraction than does the Ly alpha transmission.Comment: Submitted to the Astronomical Journa

Probing the Ionization State of the Universe at z>6

We present high signal-to-noise ratio Keck ESI spectra of the two quasars known to have Gunn-Peterson absorption troughs, SDSS J1030+0524 (z=6.28) and SDSS J1148+5251 (z=6.37). The Ly alpha and Ly beta troughs for SDSS J1030+0524 are very black and show no evidence for any emission over a redshift interval of ~0.2 starting at z=6. On the other hand, SDSS J1148+5251 shows a number of emission peaks in the Ly beta Gunn-Peterson trough along with a single weak peak in the Ly alpha trough. The Ly alpha emission has corresponding Ly beta emission, suggesting that it is indeed a region of lower optical depth in the intergalactic medium at z=6.08. The stronger Ly beta peaks in the spectrum of SDSS J1148+5251 could conceivably also be the result of "leaks" in the IGM, but we suggest that they are instead Ly alpha emission from an intervening galaxy at z=4.9. This hypothesis gains credence from a strong complex of C IV absorption at the same redshift and from the detection of continuum emission in the Ly alpha trough at the expected brightness. If this proposal is correct, the quasar light has probably been magnified through gravitational lensing by the intervening galaxy. The Stromgren sphere observed in the absorption spectrum of SDSS J1148+5251 is significantly smaller than expected based on its brightness, which is consistent with the hypothesis that the quasar is lensed. If our argument for lensing is correct, the optical depths derived from the troughs of SDSS J1148+5251 are only lower limits (albeit still quite strong, with tau(LyA)>16 inferred from the Ly beta trough.) The Ly beta absorption trough of SDSS J1030+0524 gives the single best measurement of the IGM transmission at z>6, with an inferred optical depth tau(LyA)>22.Comment: To appear in July 2003 AJ, 34 pages, 11 figures; minor changes/typos fixe

The Deeper Challenges of Global Terrorism: A Democratizing Response

The audacious and gruesome terrorist attacks on the World Trade Center and the Pentagon, along with the military response, have been the defining political events of this new millennium. The most profound challenge directed at the international community, and to all of us, is to choose between two alternative visions. What we call the traditional statist response emphasizes \u27national security\u27 as the cornerstone of human security. Centralization of domestic authority, secrecy, militarism, nationalism, and an emphasis on unconditional citizen loyalty, to her or his state as the primary organizing feature of international politics are all attributes of this approach. We recommend an alternative vision, one that we call democratic transnationalism. Democratic transnationalism attempts to draw on the successes of democratic, particularly multinational democratic, domestic orders as a model for achieving human security in the international sphere. This approach calls for the resolution of political conflict through an open transnational citizen/societal (rather than state or market) centered political process legitimized by fairness, adherence to human rights, the rule of law, and representative community participation. The promotion of security for individuals and groups through international human rights law in general, as reinforced by the incipient international criminal court with its stress on an ethos of individual legal responsibility, assessed within a reliable constitutional setting, is a crucial element of this democratic transnationalist vision, which aspires to achieve a cosmopolitan reach

A Global Parliament: Essays and Articles

Democracy is the guiding principle for fairly and peacefully making community decision at the local, provincial, and national levels of human society. In this compilation of works, Falk and Strauss argue for a practical approach to now finally extending democratic decision-making to the global system

Comparative Patterns Of Growth And Development In Cricetine Rodents And The Evolution Of Ontogeny

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137498/1/evo05721.pd