2,379 research outputs found
The Structure of Temperament and Personality Traits: A Developmental Perspective
In this chapter, we articulate a developmental perspective on personality traits from early childhood through adulthood. In the first section, we address two topics that are fundamental in defining the most important traits at each point in the life span: the relationship between temperament and personality and the methods used to ascertain the structure of traits in the temperament and personality research traditions. We argue in this section that temperament and personality are different ways of describing the same basic traits, with temperament research primarily focused on early-emerging individual differences and personality research focused on individual differences that appear later in childhood and continue into adulthood. In the second section, we describe the current status of the most prominent models of temperament, as well as the most widely-accepted personality trait model, the Big Five. In the third section, we articulate a structural model that integrates contemporary findings on temperament and personality traits from early childhood through adulthood. We use the Big Five trait structure, along with the trait of activity level, to organize this taxonomy. In the fourth section, we discuss the current research on the psychological and biological processes that underlie individual differences in the Big Five traits in childhood and adulthood. In the final sections, we offer concluding thoughts on the nature of personality trait development and suggestions for future research. This is an exciting time in the study of personality in part because of the marked progress in uncovering the basic structure of traits across the lifespan.
A model for the kinetics of a solar-pumped long path laser experiment
A kinetic model for a solar-simulator pumped iodine laser system is developed and compared to an experiment in which the solar simulator output is dispersed over a large active volume (150 cu cm) with low simulator light intensity (approx. 200 solar constants). A trace foreign gas which quenches the upper level is introduced into the model. Furthermore, a constant representing optical absorption of the stimulated emission is introduced, in addition to a constant representing the scattering at each of the mirrors, via the optical cavity time constant. The non-uniform heating of the gas is treated as well as the pressure change as a function of time within the cavity. With these new phenomena introduced into the kinetic model, a best reasonable fit to the experimental data is found by adjusting the reaction rate coefficients within the range of known uncertainty by numerical methods giving a new bound within this range of uncertainty. The experimental parameters modeled are the lasing time, laser pulse energy, and time to laser threshold
A NASA high-power space-based laser research and applications program
Applications of high power lasers are discussed which might fulfill the needs of NASA missions, and the technology characteristics of laser research programs are outlined. The status of the NASA programs or lasers, laser receivers, and laser propulsion is discussed, and recommendations are presented for a proposed expanded NASA program in these areas. Program elements that are critical are discussed in detail
Hyperinfestation of Smallmouth Bass (Micropterus dolomieui) by the Trematode Clinostomum marginatum
Preliminary design and cost of a 1-megawatt solar-pumped iodide laser space-to-space transmission station
A preliminary conceptual design of a space-based solar pumped iodide laser emitting 1 megawatt of laser power for space-to-space power transmission is described. A near parabolic solar collector focuses sunlight onto the t-C4F9I (perfluoro-t butyl iodide) lasant within a transverse flow optical cavity. Using waste heat, a thermal system was designed to supply compressor and auxiliary power. System components were designed with weight and cost estimates assigned. Although cost is very approximate, the cost comparison of individual system components leads to valuable insights for future research. In particular, it was found that laser efficiency was not a dominant cost or weight factor, the dominant factor being the laser cavity and laser transmission optics. The manufacturing cost was approx. two thirds of the total cost with transportation to orbit the remainder. The flowing nonrenewable lasant comprised 20% of the total life cycle cost of the system and thus was not a major cost factor. The station mass was 92,000 kg without lasant, requiring approx. four shuttle flights to low Earth orbit where an orbital transfer vehicle will transport it to the final altitude of 6378 km
Distribution of Clinostomum marginatum (Yellow Grub) Metacercaria in Smallmouth Bass Populations from Crooked Creek in North Central Arkansas
Four hundred thirty-three smallmouth bass (Micropterus dolomieui) were collected from ten sites on Crooked Creek in North Central Arkansas from just below the city of Harrison to the White River in the summers of 1988-90. Necropsy of these hosts for yellow grub (Clinostomum marginatum) metacercariae showed a range of mean abundance (average/fish) from 1.4 ±1.9 (SD) at a far up stream site to 105 ± 368 at the White River juncture. An increasing mean abundance of C. marginatum was seen from the uppermost sites of the creek downstream to the White River. Relating stream mileage with mean abundance gave a correlation coefficient (r) of 0.78, with P= \u3c0.01. Maximum abundance (maximum number of parasites in a single host from a site) ranged from 7 to 2500 and also showed a positive correlation with stream mileage (r=0.77,P=\u3c0.01). Prevalence (% fish infected) at the different sites ranged from 61 to 91% but showed no significant correlation with stream distance. The increasingly heavier infections seen in the downstream sites are not due to poor water quality but probably to the combination of the greater presence of the definitive host, the great blue heron, and large intermediate host (smallmouth) populations
Phylogeography of Scaled Quail
Scaled quail (Callipepla squamata) are distributed over much of the Chihuahuan Desert in the United States and south into central Mexico. Four subspecies have been described based on slight variations in coloration and body size, but the distinctiveness of the subspecies is unknown. We conducted a range-wide phylogeographic analysis of scaled quail based on the mitochondrial control region (D-loop). Our objectives were to: (1) ascertain the overall genetic diversity, (2) examine the phylogeographic structure of the scaled quail, and (3) examine the genetic distinctiveness of its 4 subspecies. We obtained D-loop sequences from 190 hunter-harvested wings and 38 museum specimens. Haplotype diversity (Hd 1⁄4 0.386) and nucleotide diversity (p 1⁄4 0.002) were relatively low. We found 16 D- loop haplotypes, 5 of which were shared by 2 or more subspecies. Haplotype A (carried by 178 individuals) was most widespread and occurred in nearly every population. Analysis of molecular variance revealed that most of the genetic variation in scaled quail occurred within populations rather than among subspecies. The low levels of genetic diversity probably reflect a historically restricted distribution within the Chihuahuan Desert, and wide geographic distribution of some haplotypes implies expansion from a single refugium. Our data indicate the scaled quail subspecies probably do not represent historically independent units. Phenotypic-based subspecies should not be used as proxies for management units if preserving genetic diversity and evolutionary potential is a goal of management, unless molecular data demonstrate the subspecies represent genetically distinct entities. Our data support viewing the entire species as a single management unit
Phylogeography of Bobwhites
Bobwhites (Colinus spp.) are a widely distributed genus of New World quails. Four species are recognized with a geographic range spanning the eastern United States to northern South America. The northern bobwhite (C. virginianus) historically occurred throughout much of the eastern United States and eastern Mexico with disjunct populations in Sonora and Cuba. The Yucata ́n bobwhite (C. nigrogularis) occurs in allopatric populations in Nicaragua and Honduras, and on the Yucata ́n Peninsula. The spot-bellied and crested bobwhites (C. leucopogon and C. cristatus) constitute a species complex with the spot-bellied bobwhite distributed from Guatemala to Costa Rica, and the crested bobwhite from Panama to northern Brazil. The 4 species exhibit substantial intraspecific variation, and up to 56 subspecies are recognized among Colinus largely on the basis of geographic distribution and male plumage coloration. However, relationships within and among species have not been studied in detail. We sampled museum study skins and obtained DNA sequences from mitochondrial control region and ND2 genes. We used concatenated sequences of control region and ND2 to investigate relationships among the bobwhite species, and the control region to assess the geographic distribution of genetic variation within each species. Maximum likelihood analysis of bobwhite phylogeny revealed Colinus is composed of two deeply divergent lineages, one clade of northern and Yucata ́n bobwhites and another of spot-bellied and crested bobwhites. The Yucata ́n bobwhite was genetically distinct from the northern bobwhite. The Yucata ́n bobwhite was composed of 2 distinct subclades, one confined to the Yucata ́n Peninsula and another occurring in Nicaragua. The genetic data showed the spot-bellied bobwhite is closely related to the crested bobwhite, but did not reveal clear support for 2 distinct species. The crested bobwhite was composed of 3 distinct lineages: a western clade that occurs in Panama and west of the northern Andes in Venezuela and Colombia, an eastern clade concentrated in Venezuela (east of the Andes), and a clade restricted to northern Brazil. We found 58 control region haplotypes, of which 29 were shared among 2 northern bobwhite subspecies and 5 haplotypes were especially geographically widespread. We found 16 haplotypes in the Yucata ́n bobwhite with 4 restricted to the Yucata ́n Peninsula and shared among the 3 subspecies found there, and 3 other haplotypes restricted to the Nicaraguan subspecies. The spot-bellied bobwhite did not share haplotypes with any of the 3 crested bobwhite subclades. We found little phylogeographic structure within the spot-bellied bobwhite, and 2 of the 5 haplotypes occurred across much of the species’ range and were shared among the 6 subspecies. The crested bobwhite exhibited strong phylogeographic structure and a lack of shared haplotypes among subspecies. The 20 haplotypes of the crested bobwhite were distributed unevenly among its 3 clades: 2 haplotypes in the Brazilian clade, 6 in the eastern clade, and 12 in the western clade. The weak phylogeographic structure and geographically widespread haplotypes of the northern bobwhite suggests large effective population size and gene flow among subspecies. The deep phylogeographic breaks within the Yucata ́n bobwhite and the spot-bellied bobwhite-crested bobwhite complex may be due to changes in the availability of suitable habitat and geological events during the Pleistocene. The lack of geographically distinct groups within the northern bobwhite implies that many subspecies may not provide good management units. Our data support the continued recognition of the Yucata ́n bobwhite as a distinct species. The 2 intraspecific groups identified in the Yucata ́n and the 4 groups within the spot- bellied/crested bobwhite complex may each represent discrete management units. Further assessment of the phylogenetic relationships and the phylogeography of the bobwhite species is warranted to clarify the phylogeny of Colinus
Development of a new laser Doppler velocimeter for the Ames High Reynolds Channel No. 2
A new two-channel laser Doppler velocimeter developed for the Ames High Reynolds Channel No. 2 is described. Design features required for the satisfactory operation of the optical system in the channel environment are discussed. Fiber optics are used to transmit the megahertz Doppler signal to the photodetectors located outside the channel pressure vessel, and provision is made to isolate the optical system from pressure and thermal strain effects. Computer-controlled scanning mirrors are used to position the laser beams in the channel flow. Techniques used to seed the flow with 0.5-micron-diam polystyrene spheres avoiding deposition on the test-section windows and porous boundary-layer removal panels are described. Preliminary results are presented with a discussion of several of the factors affecting accuracy
Grand Unification of AGN and the Accretion and Spin Paradigms
While attempts to unify certain classes of AGN using orientation and
environmental effects have been successful, it is widely recognized that
intrinsic properties of the accreting black hole system also must play a role
in determining the appearance of such an object. In addition to mass and
accretion rate, the angular momentum (or spin) of the black hole can play a
crucial role in determining the power of a relativistic jet that is generated
by magnetohydrodynamic acceleration near the hole. In this paper a scenario is
presented, based on accretion theory and recent models of MHD jet production,
in which the primary (although not only) parameter differentiating between
radio loud and quiet objects is the black hole spin, and that determining
quasar vs. radio galaxy is the accretion rate. A surprising number of desirable
features result from these simple concepts and the accompanying equations. In
addition, there are several testable predictions that can determine whether
this grand unification scheme has further merit.Comment: 13 pages, 3 figures; to appear in Life Cycles of Radio Galaxies, ed.
J. Biretta et al., New Astronomy Review
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