828 research outputs found
Mars Thermospheric Variability Revealed by MAVEN EUVM Solar Occultations: Structure at Aphelion and Perihelion, and Response to EUV Forcing
The Mars thermosphere holds clues to the evolution of the Martian climate,
and has practical implications for spacecraft visiting Mars, which often use it
for aerobraking upon arrival, or for landers, which must pass through it.
Nevertheless, it has been sparsely characterized, even when past accelerometer
measurements and remote observations are taken into account. The Mars
Atmosphere and Volatile EvolutioN (MAVEN) orbiter, which includes a number of
instruments designed to characterize the thermosphere, has greatly expanded the
available thermospheric observations. This paper presents new and unanticipated
measurements of density and temperature profiles (120-200 km) derived from
solar occultations using the MAVEN Extreme Ultraviolet (EUV) Monitor. These new
measurements complement and expand MAVEN's intended thermospheric measurement
capacity. In particular, because the local-time is inherently fixed to the
terminator, solar occultations are ideally suited for characterizing long-term
and latitudinal variability. Occultation measurements are made during
approximately half of all orbits, resulting in thousands of new thermospheric
profiles. The density retrieval method is presented in detail, including an
uncertainty analysis. Altitude-latitude maps of thermospheric density and
temperature at perihelion and aphelion are presented, revealing structures that
have not been previously observed. Tracers of atmospheric dynamics are also
observed, including a high altitude polar warming feature at intermediate
latitudes, and an apparent thermostatic response to solar EUV heating during a
solar rotation, which shows heating at high altitudes that is accompanied by
cooling at lower altitudes.Comment: Submitted to JGR: Planet
MGS Radio Science electron density profiles: Interannual variability and implications for the Martian neutral atmosphere
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94869/1/jgre1778.pd
A Phytosociological Study of a Relict Hardwood Forest in Barren County, Kentucky
Although general information is readily available concerning the structure and composition of deciduous forests, especially in the eastern part of the United States, there seems to be little specific information concerning forest composition in the Commonwealth of Kentucky. The lack of phytosociological studies prior to the development of the land, and the extent of land development in Kentucky, has led to a paucity of information regarding the natural forest vegetation of the Commonwealth. To the author\u27s knowledge, there are few publications dealing with the vegetational composition of relict or virgin forests in Kentucky. It is apparent that there is a special need for studies of natural areas that have been relatively undisturbed by man. A small wooded area in Barren County, Kentucky, referred to as Bonayer Forest, was chosen for a detailed phytosociological analysis in 1971 after a preliminary investigation indicated that the forest might be representative of the natural vegetation of southcentral Kentucky.
This study was undertaken to describe the vegetational composition of the forest, to gain some insight into the successful development of the stand, to compare the tree composition of the forest with that of representative woodlots in the surrounding area, and to establish a record of Bonayer Forest as a basis for possible future studies of a structural or functional nature. An underlying aim of this investigation was to determine whether or not this small forest is indicative of the vegetational composition that would be present in the region if it were undisturbed by man
Through the Bottom of a Drinking Glass: How Beer and Brewing Changed Human HIstory
Abstract Every corner of the earth is either currently influenced by or has been influenced by the beer and brewing industry. The significance of this product throughout human history is extensive and one would think the study of it would reflect this. However, until recently the study of beer and brewing was mostly historical and archeological in nature. The social, personal lives and economic impact of those who either consume or produce beer were largely overlooked. This look into how beer and brewing changed cultures and the life of everyone from the king to the peasant is of great importance in understanding the evolution of its role as a driver in the growth of human society. It is the primary contention of this paper that the relegation of beer to a common man’s drink has been purposely exaggerated by certain groups and the impact of the social bias of some on this industry can be seen best through the resulting temperance and prohibition movements in America. This was the result of the clear misunderstanding of how essential beer and brewing are to the human populace if not to its current survival as a clear marker of how human societies came to be what they are today. However, to understand this one would need to both possess a time machine and travel to each period. Since this is clearly not a viable option currently this paper will attempt through the collaboration of historical evidence combined with first person experience to paint a picture of the role that brewing and consuming beer played in the life of these people
Emotion Socialization and Autism Spectrum Disorder: The Role of Disability Severity and Parental Attributions in Predicting Parents\u27 Emotional Responses
The importance of parents in emotion socialization is highly established among children who are typically developing (Sheffield Morris, Silk, Steinberg, Myers, & Robinson, 2007). Child characteristics, such as child temperament and emotional reactivity, have been found to influence parenting (Bell & Chapman, 1986; Belsky, 1984). However, little is known about the emotion socialization practices of parents of children with special needs and how disability severity may influence these practices. Participants included 68 parents of children with autism spectrum disorder (ASD) (ages 3-11). Parents reported on three dimensions, using three questionnaires: disability severity via the Vineland Adaptive Behavior Scales, 2nd edition (Sparrow, Cicchetti, & Balla, 2005); emotion socialization practices via the Coping with Children\u27s Negative Emotions Scale (Fabes, Eisenberg, & Bernzweig, 1990); parents\u27 attributions for children\u27s emotional expressions using the Parents\u27 Attributions for Children\u27s Behavior Questionnaire. Using regression, the relationship between autism severity, parents\u27 attributions for children\u27s emotional expressions, and parents\u27 emotion socialization practices was examined. Findings suggest that severity of ASD does not appear to influence parents\u27 use of supportive emotion socialization practices. However, autism severity does influence parents\u27 attributions for children\u27s emotional expressions, with lower autism severity increasing parents\u27 views of their children\u27s negative emotionality as unstable and modifiable. The results of this study have implications for parenting children with ASD, early intervention, and future research in this area
Dayside thermal structure of Venus' upper atmosphere characterized by a global model
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94843/1/jgre3057.pd
Constituting We the People
We study roles of the thermosphere and exosphere on the Martian ionospheric
structure and ion escape rates in the process of the solar wind-Mars
interaction. We employ a four-species multifluid MHD (MF-MHD) model to simulate
the Martian ionosphere and magnetosphere. The thermosphere background is
taken from the Mars Global Ionosphere Thermosphere Model (M-GITM) and the
oxygen exosphere is adopted from the Mars exosphere Monte Carlo model -
Adaptive Mesh Particle Simulator (AMPS). A total of four cases with the
combination of 1D (globally averaged) and 3D thermospheres and exospheres are
studied.
The ion escape rates calculated by adopting 1D and 3D atmospheres are
similar; however, the latter are required to adequately reproduce MAVEN
ionospheric observations. In addition, our simulations show that the 3D hot
oxygen corona plays an important role in preventing planetary molecular ions
(O and CO) escaping from Mars, mainly resulting from the mass
loading of the high-altitude exospheric O ions. The thermospheric
oxygen atom, however, is demonstrated to be the primary neutral source for
O ion escape during the relatively weak solar cycle 24.Comment: 21 pages, 10 figures, 4 tables, accepted for publication in Journal
of Geophysical Research-Space Physic
Solar cycle variability of Mars dayside exospheric temperatures: Model evaluation of underlying thermal balances
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95086/1/grl25450.pd
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