University of Maine

About: University of Maine is a education organization based out in Orono, Maine, United States. It is known for research contribution in the topics: Population & Ice sheet. The organization has 8637 authors who have published 16932 publications receiving 590124 citations. The organization is also known as: University of Maine at Orono.

Effects of Ultraviolet Radiation on Amphibians: Field Experiments

Abstract: SYNOPSIS. Numerous reports suggest that populations of amphibians from a wide variety of locations are experiencing population declines and/or range reductions. In some cases, unusually high egg mortality has been reported. Field experiments have been used with increasing frequency to investigate ultraviolet radiation as one of the potential factors contributing to these declines. Results from field experiments illustrate that hatching success of eggs is hampered by ultraviolet radiation in a number of species, while other species appear to be unaffected. Continued mortality in early life-history stages may ultimately contribute to a population decline. Although UV-B radiation may not contribute to the population declines of all species, it may play a role in the population decline of some species, especially those that lay eggs in open shallow water subjected to solar radiation and in those that have a poor ability to repair UV-induced DNA damage.

A Conceptual Model of Wayfinding Using Multiple Levels of Abstraction

Abstract: Wayfinding is part of everyday life. This study concentrates on the development of a conceptual model of human navigation in the U.S. Interstate Highway Network. It proposes three different levels of conceptual understanding that constitute the cognitive map: the Planning Level, the Instructional Level, and the Driver Level. This paper formally defines these three levels and examines the conceptual objects that comprise them. The problem treated here is a simpler version of the open problem of planning and navigating a multi-mode trip. We expect the methods and preliminary results found here for the Interstate system to apply to other systems such as river transportation networks and railroad networks.

Imaging biological structures with fluorescence photoactivation localization microscopy

Abstract: Fluorescence photoactivation localization microscopy (FPALM) images biological structures with subdiffraction-limited resolution. With repeated cycles of activation, readout and bleaching, large numbers of photoactivatable probes can be precisely localized to obtain a map (image) of labeled molecules with an effective resolution of tens of nanometers. FPALM has been applied to a variety of biological imaging applications, including membrane, cytoskeletal and cytosolic proteins in fixed and living cells. Molecular motions can be quantified. FPALM can also be applied to nonbiological samples, which can be labeled with photoactivatable probes. With emphasis on cellular imaging, we describe here the adaptation of a conventional widefield fluorescence microscope for FPALM and present step-by-step procedures to successfully obtain and analyze FPALM images. The fundamentals of this protocol may also be applicable to users of similar imaging techniques that apply localization of photoactivatable probes to achieve super-resolution. Once alignment of the setup has been completed, data acquisitions can be obtained in approximately 1–30 min and analyzed in approximately 0.5–4 h.

Influence of Electric Fields on the Molecular Alignment in the Liquid Crystal p-(Anisalamino)-phenyl Acetate

Abstract: The effects of electric fields on the molecular alignment in the liquid crystal p-(anisalamino)-phenyl acetate are discussed The behavior of this material is similar to that of p-azoxyanisole in that the ordering which is normally observed shows an alignment with the molecular axis preferring a direction parallel to the field at low audio frequencies, and perpendicular to the field for frequencies of a few hundred kHz Results comparing the effectiveness of electric and magnetic fields for producing molecular alignment are presented which support a theory presented earlier to explain the ordering in p-azoxyanisole at audio frequencies This theory involves the anisotropy associated with the electrical conductivity Results are also presented which show that the effectiveness of dc electric fields is comparable to that for low audio frequencies A few comments are made concerning recent work employing electric fields to produce ordering in liquid crystals for NMR studies