31,229 research outputs found
Water quality map of Saginaw Bay from computer processing of LANDSAT-2 data
There are no author-identified significant results in this report
Numerical Algorithm for Detecting Ion Diffusion Regions in the Geomagnetic Tail with Applications to MMS Tail Season May 1 -- September 30, 2017
We present a numerical algorithm aimed at identifying ion diffusion regions
(IDRs) in the geomagnetic tail, and test its applicability. We use 5 criteria
applied in three stages. (i) Correlated reversals (within 90 s) of Vx and Bz
(at least 2 nT about zero; GSM coordinates); (ii) Detection of Hall electric
and magnetic field signatures; and (iii) strong (>10 mV/m) electric fields.
While no criterion alone is necessary and sufficient, the approach does provide
a robust, if conservative, list of IDRs. We use data from the Magnetospheric
Multiscale Mission (MMS) spacecraft during a 5-month period (May 1 to September
30, 2017) of near-tail orbits during the declining phase of the solar cycle. We
find 148 events satisfying step 1, 37 satisfying steps 1 and 2, and 17
satisfying all three, of which 12 are confirmed as IDRs. All IDRs were within
the X-range [-24, -15] RE mainly on the dusk sector and the majority occurred
during traversals of a tailward-moving X-line. 11 of 12 IDRs were on the
dusk-side despite approximately equal residence time in both the pre- and
post-midnight sectors (56.5% dusk vs 43.5% dawn). MMS could identify signatures
of 4 quadrants of the Hall B-structure in 3 events and 3 quadrants in 7 of the
remaining 12 confirmed IDRs identified. The events we report commonly display
Vx reversals greater than 400 km/s in magnitude, normal magnetic field
reversals often >10 nT in magnitude, maximum DC |E| which are often well in
excess of the threshold for stage 3. Our results are then compared with the set
of IDRs identified by visual examination from Cluster in the years 2000-2005.Comment: In Submission at JGR:Space Physic
Radiation environment for rendezvous and docking with nuclear rockets
Radiation environment data for the NERVA engine are provided which may be utilized in estimating radiation exposures associated with various space maneuvers. Spatial distributions of neutron and gamma tissue kerma rates produced during full thrust operation of the engine are presented. Final rendezvous with an orbiting space station would be achieved subsequent to full thrust operation during a period of 10 or more hours duration in which impulse is delivered by the propellant used for removal of decay heat. Consequently, post operation radiation levels are of prime importance in estimating space station exposures. Maps of gamma kerma rates around the engine are provided for decay times of 4 and 24 hours after a representative firing. Typical decay curves illustrating the dependence of post operation kerma rates on decay time and operating history are included. Examples of the kerma distributions around the engine which result from integration over specific exposure periods are shown
Bounding the norm of a log-concave vector via thin-shell estimates
Chaining techniques show that if X is an isotropic log-concave random vector
in R^n and Gamma is a standard Gaussian vector then E |X| < C n^{1/4} E |Gamma|
for any norm |*|, where C is a universal constant. Using a completely different
argument we establish a similar inequality relying on the thin-shell constant
sigma_n = sup ((var|X|^){1/2} ; X isotropic and log-concave on R^n).
In particular, we show that if the thin-shell conjecture sigma_n = O(1)
holds, then n^{1/4} can be replaced by log (n) in the inequality.
As a consequence, we obtain certain bounds for the mean-width, the dual
mean-width and the isotropic constant of an isotropic convex body.
In particular, we give an alternative proof of the fact that a positive
answer to the thin-shell conjecture implies a positive answer to the slicing
problem, up to a logarithmic factor.Comment: preliminary version, 13 page
Production of a water quality map of Saginaw Bay by computer processing of LANDSAT-2 data
Surface truth and LANDSAT measurements collected July 31, 1975, for Saginaw Bay were used to demonstrate a technique for producing a color coded water quality map. On this map, color was used as a code to quantify five discrete ranges in the following water quality parameters: (1) temperature, (2) Secchi depth, (3) chloride, (4) conductivity, (5) total Kjeldahl nitrogen, (6) total phosphorous, (7)chlorophyll a, (8) total solids and (9) suspended solids. The LANDSAT and water quality relationship was established through the use of a set of linear regression equations where the water quality parameters are the dependent variables and LANDSAT measurements are the independent variables. Although the procedure is scene and surface truth dependent, it provides both a basis for extrapolating water quality parameters from point samples to unsampled areas and a synoptic view of water mass boundaries over the 3000 sq. km bay area made from one day's ship data that is superior, in many ways, to the traditional machine contoured maps made from three day's ship data
The Effect of Dyad Interaction and Marital Adjustment on Cognitive Performance in Everyday Logical Problem Solving
The theory of formal operations as a final stage of adult development has come under criticism for various reasons, primarily the overemphasis on logical thought processes which are based on invariant and absolute rules within a closed system. Everyday problems, in contrast, are typically open-ended and are defined by the context in which they are embedded.
The purpose of this study was to investigate cognitive behaviors that occurred between two individuals as they cooperatively worked together to solve logical problems. Of interest were the effects of marital adjustment on cognitive performance, the relation between social behaviors, marital adjustment, and cognition, and the influence of familiar versus a stranger dyadic problem-solving setting on cognitive behaviors. It was hypothesized that well adjusted married and stranger dyads would not only demonstrate mastery of problem-solving tasks at the formal operational level, but would also demonstrate more relativistic and/or dialectical problem solving, and more facilitative social behaviors, than poorly adjusted married and stranger dyads.
Forty couples between the ages of 35 and 50, who had been married between five and thirty years, were prescreened for verbal intelligence and marital adjustment. They were then randomly assigned to participate in one of four dyadic settings, that is, maritally well versus poorly adjusted couples solving problems in either married or unmarried/stranger dyads. Dyads were administered five formal operational problems. Two of the five were formal logical, or mathematical in nature, while three problems contained both mathematical and interpersonal, or social elements. Each dyad was videotaped during the problem-solving process, beginning with the instructions. Participant averaged about 1 hour and 15 minutes to complete five problems.
Analyses of variance were performed on marital adjustment and dyadic setting as related to formal and relativistic cognitions. There were no marital adjustment or dyadic setting differences in overall ability to use formal operations. However, maritally well adjusted stranger and married dyads evidenced significantly more relativistic cognitions, particularly on problems involving a social/everyday element, than poorly adjusted married and stranger dyads. These differences also held constant across each of three increasingly complex levels of relativistic behaviors. Multivariate analyses were performed on four separate social behavior scales as related to formal and relativistic cognitions, as well as marital adjustment and dyadic setting groups. Again, formal operations did not distinguish between the differing social behaviors; however, the social behavior scales, particularly avoidant versus cooperative behaviors, were strongly related to marital adjustment and relativistic thinking
A Feynman-Kac Formula for Anticommuting Brownian Motion
Motivated by application to quantum physics, anticommuting analogues of
Wiener measure and Brownian motion are constructed. The corresponding Ito
integrals are defined and the existence and uniqueness of solutions to a class
of stochastic differential equations is established. This machinery is used to
provide a Feynman-Kac formula for a class of Hamiltonians. Several specific
examples are considered.Comment: 21 page
An implementation of the programming structural synthesis system (PROSSS)
A particular implementation of the programming structural synthesis system (PROSSS) is described. This software system combines a state of the art optimization program, a production level structural analysis program, and user supplied, problem dependent interface programs. These programs are combined using standard command language features existing in modern computer operating systems. PROSSS is explained in general with respect to this implementation along with the steps for the preparation of the programs and input data. Each component of the system is described in detail with annotated listings for clarification. The components include options, procedures, programs and subroutines, and data files as they pertain to this implementation. An example exercising each option in this implementation to allow the user to anticipate the type of results that might be expected is presented
Targeted expression of SV40 T antigen in the hair follicle of transgenic mice produces an aberrant hair phenotype
Directed expression of SV40 large T antigen (TAg) in transgenic mice can induce tissue-specific tumorigenesis and useful cell lines exhibiting differentiated characteristics can be established from resultant tumor cells. In an attempt to produce an immortalised mouse hair follicle cortical cell line for the study of hair keratin gene control, SV40 TAg expression was targeted to the hair follicles of transgenic mice using a sheep hair gene promoter. Expression of SV40 TAg in the follicle cortex disrupted normal fiber ultrastructure, producing a marked phenotypic effect. Affected hairs were wavy or severely kinked (depending on the severity of the phenotype) producing an appearance ranging from a ruffled coat to a stubble covering the back of the mouse. The transgenic hairs appeared to be weakened at the base of the fibers, leading to premature hair-loss and a thinner pelage, or regions of temporary nudity. No follicle tumors or neoplasia were apparent and immortalisation of cortical cells could not be established in culture. In situ hybridisation studies in the hair follicle using histone H3 as a cell proliferation marker suggested that cell proliferation had ceased prior to commencement of K2.10-TAg expression and was not re-established in the differentiating cortical cells. Hence, TAg was unable to induce cell immortalisation at that stage of cortical cell differentiation. However, transgenic mice developed various other abnormalities including vertebral abnormalities and bladder, liver and intestinal tumors, which resulted in reduced life expectancy.R. Keough, B. Powell and G. Roger
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