The origin of remanent magnetism in sedimentary rocks

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Geology and Geophysics, 1960.Includes bibliographical references (leaves 132-133).by David Greenewalt.Ph.D

Kinematics of swimming of penguins at the Detroit Zoo

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73876/1/j.1469-7998.1979.tb03424.x.pd

The Early Byzantine Domed Basilicas of West Asia Minor, An essay in Graphic Reconstruction

This paper investigates the methodology employed in the recent survey and reconstruction of the major Early Byzantine domed churches of west Asia Minor. This involved both the documentation of construction details as well as their interpretation by reference to coeval monuments elsewhere. Focusing on this methodology, the author explores techniques of graphic recording and the theoretical framework within which parallels with other buildings can inform the work of reconstruction. The detailed examination of two case studies illustrates the way in which seemingly random scraps of testimony were interpreted to provide evidence for the missing superstructure of the churches. These case studies also serve to explore the adaptation of the methodology to sites with different characteristics and help to assess the credibility of the resulting graphic reconstructions

Measurement artefacts lead to false positives in the study of birdsong in noise

Numerous studies over the past decade have reported correlations between elevated levels of anthropogenic noise and a rise in the minimum frequency of acoustic signals of animals living in noisy habitats. This pattern appears to be occurring globally, and higher pitched signals have been hypothesized to be adaptive changes that reduce masking by low‐frequency traffic noise. However, the sound analysis methods most often used in these studies are prone to measurement errors that can result in false positives. In addition, the commonly used method of measuring frequencies visually from spectrograms might also lead to observer‐expectancy biases that could exacerbate measurement errors. We conducted an experiment to (i) quantify the size and type of errors that result from ‘eye‐balling’ frequency measurements with cursors placed manually on spectrograms of signals recorded in noise and no‐noise conditions, and (ii) to test whether observer expectations lead to significant errors in frequency measurements. We asked 54 volunteers, blind to the true intention of our study, to visually measure the minimum frequency of a variety of natural and synthesized bird sounds, recorded either in noise, or no‐noise conditions. Test subjects were either informed or uninformed about the hypothesized results of the measurements. Our results demonstrate that inappropriate methodology in acoustic analysis can yield false positives with effect sizes as large, or even larger, than those reported in published studies. In addition to these measurement artefacts, psychological observer biases also led to false positives – when observers expected signals to have higher minimum frequencies in noise, they measured significantly higher minimum frequencies than uninformed observers, who had not been primed with any expectation. The use of improper analysis methods in bioacoustics can lead to the publication of spurious results. We discuss alternative methods that yield unbiased frequency measures and we caution that it is imperative for researchers to familiarize themselves both with the functions and limitations of their sound analysis programmes. In addition, observer‐expectancy biases are a potential source of error not only in the field of bioacoustics, but in any situation where measurements can be influenced by human subjectivity

Maintenance of the pectoralis muscle during hibernation in the big brown bat, Eptesicus fuscus

The relationship between pectoralis muscle mass and body mass is examined throughout the annual body mass cycle in Eptesicus fuscus in order to evaluate muscle maintenance during hibernation. E. fuscus undergoes large fluctuations in body mass during the year due to pregnancy, parturition, prehibernation fattening, and hibernation (Table 1). Parallel changes occur in pectoralis muscle mass and total pectoralis protein mass (Table 2). The strong correlation between log pectoralis mass and log body mass (Fig. 3) and the lack of correlation between pectoralis mass and forearm length (Fig. 1, 2) suggest that the seasonal variation in pectoralis muscle mass represents a compensatory response to changing body mass. In active bats this relationship closely resembles the compensatory response predicted by flight theory.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47128/1/360_2004_Article_BF00689733.pd

Homing pigeons (Columba livia) modulate wingbeat characteristics as a function of route familiarity

Mechanisms of avian navigation have received considerable attention, but whether different navigational strategies are accompanied by different flight characteristics is unknown. Managing energy expenditure is critical for survival, therefore understanding how flight characteristics, and hence energy allocation, potentially change with birds’ familiarity with a navigational task could provide key insights into the costs of orientation. We addressed this question by examining changes in wingbeat characteristics and airspeed of homing pigeons (Columba livia) as they learned a homing task. Twenty-one pigeons were released 20 times individually from either 3.85 km or 7.06 km from home. Birds were equipped with 5 Hz GPS trackers and 200 Hz tri-axial accelerometers. We found that, as the birds’ route efficiency increased during the first six releases, their median peak-to-peak dorsal body (DB) acceleration and median DB amplitude also increased. This, in turn, led to higher airspeeds, suggesting that birds fly slower when traversing unfamiliar terrain. By contrast, after route efficiency stabilised, birds exhibited increasing wingbeat frequencies, which did not result in further increases in speed. Overall, higher wind support was also associated with lower wingbeat frequencies and with increased DB amplitude. Our study suggests that the cost of early flights from an unfamiliar location may be higher than subsequent flights both due to inefficient routes (increased distance) and lower airspeeds (increased time). Furthermore, the results indicate, for the first time, that birds modulate their wingbeat characteristics as a function of navigational knowledge, and suggest that flight characteristics may be used as "signatures" of birds' route familiarity

Allometry of the Duration of Flight Feather Molt in Birds

Replacement of flight feathers takes disproportionately more time for large birds than it does for small birds, because feather length increases with body size almost twice as fast as feather growth rate increases