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Ring patterns showing complacent and sensitive ring series. (a) Climate has minimal effect on ring widths when trees have ample moisture every year. (b) Maximum ring-width variations occur on sites where growth is limited by factors that vary from…

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from article Dendrochronology

Core being taken from a tree with an increment borer. (Courtesy of Laboratory of Tree-Ring Research, University of Arizona)

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from article Dendrochronology

Chronology building. Chronologies are extended backward in time by matching patterns of wood samples whose ages overlap.

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from article Dendrochronology

Skeleton plot (top) from an idealized tree-ring sequence in a specimen (bottom). Ring widths are represented by vertical lines in inverse proportion; that is, tall lines represent narrow rings. An exceptionally wide ring is designated by the letter…

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from article Dendrochronology

Bristlecone pines, which attain ages of more than 4000 years, form the basis for the second longest chronology yet developed. (Courtesy of Laboratory of Tree-Ring Research, University of Arizona)

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from article Paleoindian

Location of some important North American Paleoindian sites during the late-Pleistocene Ice Age.

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from article Sleep-dependent memory processing

The sleep cycle, memory systems, and memory stages. (a) The human sleep cycle. Across the night, rapid eye movement (REM) sleep and non-REM (NREM) sleep cycle every 90 minutes in an ultradian manner (that is, occurring in cycles that are repeated…

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from article Sleep-dependent memory processing

Sleep-dependent motor skill learning. (a) Wake first. After morning training (10 a.m., clear bar), subjects showed no significant change in performance when tested after 12 hours of wake time (10 p.m., clear bar). However, when tested again…

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from article Sleep-dependent memory processing

Sleep-dependent integration of human relational memory. (a) Delayed inference (associative) memory performance (% correct) in a relational memory task following different offline delays. Immediate testing after just a 20-min offline delay…

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from article Territoriality