541 research outputs found
Stanford University’s John Otterbein Snyder: Student, Collaborator, and Colleague of David Starr Jordan and Charles Henry Gilbert
John Otterbein Snyder (1867–1943) was an early student of David Starr Jordan at Stanford University and subsequently rose to become an assistant professor there. During his 34 years with the university he taught a wide variety of
courses in various branches of zoology and advised numerous students. He eventually mentored 8 M.A. and 4 Ph.D. students to completion at Stanford. He also assisted in
the collection of tens of thousands of fish specimens from the western Pacific, central Pacific, and the West Coast of North America, part of the time while stationed as “Naturalist” aboard the U.S. Fish Commission’s Steamer Albatross (1902–06). Although his early publications dealt
mainly with fish groups and descriptions (often as a junior author with Jordan), after 1910 he became more autonomous and eventually rose to become one of the Pacific salmon, Oncorhynchus spp., experts on the West Coast. Throughout his career, he was especially esteemed by colleagues as “a
stimulating teacher,” “an excellent biologist,” and “a fine man
Spacecraft Glow and the Eisg/skirt Experiment
The objective of this experiment is to develop an understanding of the physical processes leading to spacecraft glow phenomena. The emphasis is to be on surface temperature and altitude effects. A complete understanding of the phenomena could be used to accomplish the following: (1) characterize optical instrument backgrounds; (2) provide guidelines for thermal insulations; (3) characterize material selection for flight optics and associated spacecraft; and (4) affect flight-operation altitude selection for relevant missions
Time-Resolved AU-Scale Jets Traced by Masers in the IRAS 4A/B Regions of NGC1333
We present results of VLBI observations of the water masers associated with
IRAS 4A and IRAS 4B in the NGC 1333 star-forming region taken in four epochs
over a two month period. Both objects have been classified as extremely young
sources and each source is known to be a multiple system. Using the Very Long
Baseline Array, we detected 35 masers in Epoch I, 40 masers in Epoch II, 35 in
Epoch III, and 24 in Epoch IV. Only one identified source in each system
associates with these masers. These data are used to calculate proper motions
for the masers and trace the jet outflows within 100 AU of IRAS 4A2 and IRAS
4BW. In IRAS 4A2 there are two groups of masers, one near the systemic cloud
velocity and one red-shifted. They expand linearly away from each other at
velocities of 53 km/s. In IRAS 4BW, masers are observed in two groups that are
blue-shifted and red-shifted relative to the cloud velocity. They form complex
linear structures with a thickness of 3 mas (1 AU at a distance of 320 pc) that
expand linearly away from each other at velocities of 78 km/s. Neither of the
jet outflows traced by the maser groups align with the larger scale outflows.
We suggest the presence of unresolved companions to both IRAS 4A2 and 4BW.Comment: Accepted by Ap
Change in Blood Pressure Variability Among Treated Elderly Hypertensive Patients and Its Association With Mortality
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Metallothionein-I/II expression associates with the astrocyte DNA damage response and not Alzheimer-type pathology in the ageing brain
Oxidative stress and oxidative DNA damage are early features of mild cognitive impairment and Alzheimer’s disease (AD), occurring before the formation of classical AD neuropathology, and resulting from an imbalance between pro- and anti-oxidants. Astrocytes play a major neuroprotective role, producing high levels of anti-oxidants including metallothionein-I and –II (MT-I/II). In the present study we characterized the immunoreactive profile of MT-I/II in the temporal cortex of the Cognitive Function and Ageing Study (CFAS)
aging population-representative neuropathology cohort, and examined H2O2-modulation of MT transcription by human astrocytes. MT-I/II is primarily expressed by astrocytes in the aging brain, but is also associated with pyramidal neurons in a small proportion of cases. Astrocyte expression of MT-I/II does not correlate with Alzheimer-type pathology (Aβ plaques and neurofibrillary tangles) but does relate to astrocyte oxidative DNA damage (rs= 0.312, p= 0.006) and the astrocyte response to oxidative DNA damage in vivo (rs= 0.238, p= 0.04), and MT gene expression is significantly induced in human astrocytes response to oxidative stress in vitro (p=0.01). In contrast, neuronal MT-I/II does not relate to oxidative DNA damage or the neuronal DNA damage response, but is significantly higher in cases with high levels of local tangle pathology (p=0.007). As MT-I/II is neuroprotective against
oxidative stress, modulation of MT-I/II expression is a potential therapeutic target to treat the onset and progression of cognitive impairment
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