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.

A mechanism of abiotic immobilization of nitrate in forest ecosystems: the ferrous wheel hypothesis

Abstract: Forest soils, rather than woody biomass, are the dominant long-term sink for N in forest fertilization studies and, by inference, for N from atmospheric deposition. Recent evidence of significant abiotic immobilization of inorganic-N in forest humus layers challenges a previously widely held view that microbial processes are the dominant pathways for N immobilization in soil. Understanding the plant, microbial, and abiotic mechanisms of N immobilization in forest soils has important implications for understanding current and future carbon budgets. Abiotic immobilization of nitrate is particularly perplexing because the thermodynamics of nitrate reduction in soils are not generally favorable under oxic conditions. Here we present preliminary evidence for a testable hypothesis that explains abiotic immobilization of nitrate in forest soils. Because iron (and perhaps manganese) plays a key role as a catalyst, with Fe(II) reducing nitrate and reduced forms of carbon then regenerating Fe(II), we call this ‘the ferrous wheel hypothesis’. After nitrate is reduced to nitrite, we hypothesize that nitrite reacts with dissolved organic matter through nitration and nitrosation of aromatic ring structures, thus producing dissolved organic nitrogen (DON). In addition to ignorance about mechanisms of DON production, little is known about DON dynamics in soil and its fate within ecosystems. Evidence from leaching and watershed studies suggests that DON production and consumption may be largely uncoupled from seasonal biological processes, although biological processes ultimately produce the DOC and reducing power that affect DON formation and the entire N cycle. The ferrous wheel hypothesis includes both biological and abiological processes, but the reducing power of plant-derived organic matter may build up over seasons and years while the abiotic reduction of nitrate and reaction of organic matter with nitrite may occur in a matter of seconds after nitrate enters the soil solution.

Triclosan exposure, transformation, and human health effects.

Abstract: Triclosan (TCS) is an antimicrobial used so ubiquitously that 75% of the US population is likely exposed to this compound via consumer goods and personal care products. In September 2016, TCS was banned from soap products following the risk assessment by the US Food and Drug Administration (FDA). However, TCS still remains, at high concentrations, in other personal care products such as toothpaste, mouthwash, hand sanitizer, and surgical soaps. TCS is readily absorbed into human skin and oral mucosa and found in various human tissues and fluids. The aim of this review was to describe TCS exposure routes and levels as well as metabolism and transformation processes. The burgeoning literature on human health effects associated with TCS exposure, such as reproductive problems, was also summarized.

Foundations of Geographic Information Science

Abstract: Geographic Information Science. The Nature and Value of Geographic Information. Communicating Geographic Information in Context. Pragmatic Information Content. Representational Commitment in Maps. Granularity in Change over Time. A Theory of Granular Partitions. On the Ontological Status of Geographical Boundaries. Regions in Geography. Neighborhoods and Landmarks. Geographical Terminology Servers. Placing Cultural Events and Documents. Geographic Activity Models.

Sexual Harassment, Workplace Authority, and the Paradox of Power

Abstract: Power is at the core of feminist theories of sexual harassment, although it has rarely been measured directly in terms of workplace authority. Popular characterizations portray male supervisors harassing female subordinates, but power-threat theories suggest that women in authority may be more frequent targets. This article analyzes longitudinal survey data and qualitative interviews from the Youth Development Study to test this idea and to delineate why and how supervisory authority, gender nonconformity, and workplace sex ratios affect harassment. Relative to nonsupervisors, female supervisors are more likely to report harassing behaviors and to define their experiences as sexual harassment. Sexual harassment can serve as an equalizer against women in power, motivated more by control and domination than by sexual desire. Interviews point to social isolation as a mechanism linking harassment to gender nonconformity and women's authority, particularly in male-dominated work settings.

Development and initial validation of the children's sadness management scale

Abstract: Although sadness in children is a normal and transient experience, research has not investigated how children manage sadness. Understanding normative sadness management has important implications for helping children who exhibit maladaptive forms of emotional expression. The Children's Sadness Management Scale (CSMS) was developed to assess children's inhibition, dysregulated-expression, and coping with sadness experience and expression. Using multiple informants, reliability and validity were established based on a community sample of 227 fourth- and fifth-grade children's self-report, maternal report (N = 171), and peer ratings of behavior (N = 227). A three-factor solution was supported with strong internal consistency for the Inhibition scale and moderately strong internal consistency for the Emotion Regulation Coping and Dysregulated-Expression scales. Findings indicate that the CSMS provides a reliable and valid measure of normative sadness management.