12,431 research outputs found
Long-term polarimetric observations of OH127.8+0.0
OH 1612 and 1667 MHz masers from the well known object OH127.8+0.0 were mon-
itored in full-polarization mode over a period of 6.5 years and mapped with
MERLIN at one epoch. The OH variability pattern of the star is typical of
extremely long- period AGB stars. The distance determined from the 1612 MHz
light curve and a new measurement of the angular radius is 3.87 (0.28) kpc. At
both frequencies, the flux of polarized emission tightly follows the total flux
variations while, the degrees of circu- lar and linear polarization are
constant within measurement accuracy.. There is net polarization at both lines.
The magnetic field strength estimated from a likely Zeeman pair is -0.6 mG at
the distance of 5400 au from the star.At the near and far sides of the
envelope, the polarization vectors are well aligned implying a regular
structure of the magnetic field. The polarization characteristics of the OH
maser emission suggest a radial magnetic field which is frozen in the stellar
wind.Comment: 12 pages, 9 figure
What is Strategic Competence and Does it Matter? Exposition of the Concept and a Research Agenda
Drawing on a range of theoretical and empirical insights from strategic management and the cognitive and organizational sciences, we argue that strategic competence constitutes the ability of organizations and the individuals who operate within them to work within their cognitive limitations in such a way that they are able to maintain an appropriate level of responsiveness to the contingencies confronting them. Using the language of the resource based view of the firm, we argue that this meta-level competence represents a confluence of individual and organizational characteristics, suitably configured to enable the detection of those weak signals indicative of the need for change and to act accordingly, thereby minimising the dangers of cognitive bias and cognitive inertia. In an era of unprecedented informational burdens and instability, we argue that this competence is central to the longer-term survival and well being of the organization. We conclude with a consideration of the major scientific challenges that lie ahead, if the ideas contained within this paper are to be validated
Multilinear Eigenfunction Estimates And Global Existence For The Three Dimensional Nonlinear Schr\"Odinger Equations
We study nonlinear Schr\"odinger equations, posed on a three dimensional
Riemannian manifold . We prove global existence of strong solutions on
and as far as the nonlinearity is defocusing and
sub-quintic and thus we extend the results of Ginibre-Velo and Bourgain who
treated the cases of the Euclidean space and the flat torus \T^3
respectively. The main ingredient in our argument is a new set of multilinear
estimates for spherical harmonics.Comment: Lemma 4.6 in the previous version was false, we made slight
modifications to use only a weaker version of this lemm
Assessing schematic knowledge of introductory probability theory
[Abstract]: The ability to identify schematic knowledge is an important goal for both assessment
and instruction. In the current paper, schematic knowledge of statistical probability theory is
explored from the declarative-procedural framework using multiple methods of assessment.
A sample of 90 undergraduate introductory statistics students was required to classify 10
pairs of probability problems as similar or different; to identify whether 15 problems
contained sufficient, irrelevant, or missing information (text-edit); and to solve 10 additional
problems. The complexity of the schema on which the problems were based was also
manipulated. Detailed analyses compared text-editing and solution accuracy as a function of
text-editing category and schema complexity. Results showed that text-editing tends to be
easier than solution and differentially sensitive to schema complexity. While text-editing and
classification were correlated with solution, only text-editing problems with missing
information uniquely predicted success. In light of previous research these results suggest
that text-editing is suitable for supplementing the assessment of schematic knowledge in
development
How to automate a kinematic mount using a 3D printed Arduino-based system
We demonstrate a simple, flexible and cost-effective system to automatize
most of the kinematic mounts available nowadays on the market. It combines 3D
printed components, an Arduino board, stepper motors, and simple electronics.
The system developed can control independently and simultaneously up to ten
stepper motors using commands sent through the serial port, and it is suitable
for applications where optical realignment using flat mirrors is required on a
periodic basis.Comment: 9 pages, 8 figure
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