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.

Thermogeography over time creates biogeographic regions: a temperature/space/time‐integrated model and an abundance‐weighted test for benthic marine algae

Abstract: We developed a time-integrated thermogeographic model to demonstrate conditions under which benthic marine algal assemblages evolve biogeographic patterns in their distribution and abundance. The graphical model applies to rocky marine sublittoral zones in which seasonal temperatures, coastline area, isolation, and evolutionary time are primary factors. Time is treated by using the temperature/area/distributions for the present (interglacial period) integrated with that of 18,000 years before present (glacial period). These two alternate states characterize the global marine realm since the late Pliocene to Pleistocene time during which many extant species have evolved. The resulting abiotic “thermogeographic” model defines 20 regions that correspond with the cores of 24 recognized biogeographic regions and/or provinces determined by published distributions of organisms. Modern biogeographic regions conform closely with thermogeographic regions where temperature, area, and time are integrated. We also propose that biogeographic patterns should be determined by the abundance of species assemblages rather than presence and absence or percent endemism as is commonly done. We test the efficacy of thermogeographic regions with abundance-weighted patterns in the biogeography of crustose coralline red algae (Rhodophyta/Corallinales) in the colder part of the northern hemisphere. Based on abundance, rather than presence/absence, coralline red algal biogeographic regions correspond closely with the model's thermogeographic regions.

Otolith δ18O record of mid-holocene sea surface temperatures in peru

Abstract: Peruvian sea catfish (Galeichthys peruvianus) sagittal otoliths preserve a record of modern and mid-Holocene sea surface temperatures (SSTs). Oxygen isotope profiles in otoliths excavated from Ostra [6010 +/- 90 years before the present (yr B.P.); 8 degrees 55'S] indicate that summer SSTs were approximately 3 degrees C warmer than those of the present. Siches otoliths (6450 +/- 110 yr B.P.; 4 degrees 40'S) recorded mean annual temperatures approximately 3 degrees to 4 degrees C warmer than were measured under modern conditions. Trophic level and population diversity and equitability data from these faunal assemblages and other Peruvian archaeological sites support the isotope interpretations and suggest that upwelling of the Peru-Chile current intensified after approximately 5000 yr B.P.

Recent climate and ice-sheet changes in West Antarctica compared with the past 2,000 years

Abstract: West Antarctic temperature and pressure observations begin onlyin 1957, and reliable satellite observations of Antarctic sea icedate to 1979. Comprehensive observations of glacier dynamicsin the most rapidly changing areas were initiated in the 1990s.Borehole temperature data from the WAIS, although confirmingthe recent rapid rise in temperature, do not resolve decadal-scalevariability in the past

Experiments to relate acoustic emission energy to fracture energy of concrete

Abstract: Acoustic emission (AE) was used to measure energy associated with fracture of standard concrete test specimens. The goal of the work was to identify ways in which AE could be used to quantify damage in generic laboratory structures for the purpose of tuning damage models. A series of mortar and concrete specimens of different compositions were tested for fracture energy G-sub-f, while simultaneously being monitored for acoustic emission energy release. Reasonable correlation between the 2 quantities was observed for fine-grained specimens; however, the relationship was not as good for coarse-grained specimens. Toughening mechanisms such as friction are suggested as being responsible for the poor relationship observed in the course-grained materials. It is further suggested that AE energy release can be related to actual crack formation energy but not to friction and other internal energy dissipation or toughening mechanisms.

De Novo Synthesis of 4,5-Dimethoxycatechol and 2,5-Dimethoxyhydroquinone by the Brown Rot Fungus Gloeophyllum trabeum†

Abstract: The new dimethoxycatechol 4,5-dimethoxy-1,2-benzenediol (DMC) and the new dimethoxyhydroquinone 2,5-dimethoxy-1,4-benzenediol (DMH) were isolated from stationary cultures of the brown rot fungus Gloeophyllum trabeum growing on a glucose mineral medium protected from light. The structure was elucidated by gas chromatography-mass spectrometry through comparison to a synthetic standard. Further confirmation was obtained by forming a dimethoxyoxazole derivative by condensation of DMC with methylene chloride and through examination of methylated derivatives. DMC and DMH may serve as ferric chelators, oxygen-reducing agents, and redox-cycling molecules, which would include functioning as electron transport carriers to Fenton’s reactions. Thus, they appear to be important components of the brown rot decay system of the fungus.