3,736 research outputs found
The Perils of Positivity
The passion and productivity that characterizes research on positive organizational behavior (POB) is impressive. Yet POB research is accumulating so rapidly that it may exceed what the field's conceptual, methodological, and ideological foundation can bear. I discuss here six concerns prompted by the articles in this special issue. These concerns are (1) the emphasis of positive organizational scholarship on individual-level phenomena, (12) the ahistorical character of POB research and writing, (3) the construct validity of key concepts, (4) over-reliance on a particular research strategy, (5) implicit acceptance of fundamental flaws in how work and organizations are designed, and (6) the seductiveness of new research paradigms.Psycholog
Magnetic field topology of the RS CVn star II Pegasi
The dynamo processes in cool active stars generate complex magnetic fields
responsible for prominent surface stellar activity and variability at different
time scales. For a small number of cool stars magnetic field topologies were
reconstructed from the time series of spectropolarimetric observations using
the Zeeman Doppler imaging (ZDI) method. In this study we follow a long-term
evolution of the magnetic field topology of the RS CVn binary star II Peg. We
collected high-resolution circular polarisation observations of II Peg using
the SOFIN spectropolarimeter at the Nordic Optical Telescope. These data cover
12 epochs spread over 7 years. A multi-line diagnostic technique in combination
with a new ZDI code is applied to interpret these observations. Magnetic
inversions using these data reveals evolving magnetic fields with typical local
strengths of 0.5-1.0 kG and complex topologies. Despite using a self-consistent
magnetic and temperature mapping technique, we do not find a clear correlation
between magnetic and temperature features in the ZDI maps. Neither do we
confirm the presence of persistent azimuthal field rings found in other RS CVn
stars. Reconstruction of the magnetic field topology of II Peg reveals
significant evolution of both the surface magnetic field structure and the
extended magnetospheric field geometry. From 2004 to 2010 the total field
energy drastically declined and the field became less axisymmetric. This also
coincided with the transition from predominantly poloidal to mainly toroidal
field topology. A qualitative comparison of the ZDI maps of II Peg with the
prediction of dynamo theory suggests that the magnetic field in this star is
produced mainly by the turbulent alpha^2 dynamo rather than the solar
alphaOmega dynamo. Our results do not show a clear active longitude system, nor
is there an evidence of the presence of an azimuthal dynamo wave.Comment: 20 pages, 10 figures; accepted for publication in Astronomy &
Astrophysic
Recommended from our members
Joseph E. McGrath (1927-2007)
Presents an obituary for Joseph E. McGrath (1927â2007). Joseph E. McGrath, who died on April 1, 2007, often described himself as a âconceptual carpenter.â It was an apt description: Joe conceived and built the frameworks within which a remarkable number of students and colleagues designed their studies, chose their methods, and developed their theories. He was not one to promote the flashy new concept, to generate the gasp-provoking empirical demonstration, or to concoct the unheard of new measure or manipulation. Instead, Joe created elegant conceptual and methodological platforms on which he, along with his many students and colleagues around the world, productively explored an extraordinarily diverse set of scientific and social problems.Psycholog
Rethinking Leadership, or Team LEaders Are Not Music Directors
Let us begin with a thought experiment. Think for a moment about one of the finest groups you have every seenâone that accomplished its work superbly, that got better and better as a performing unit over time, and whose members came away from the group experience wiser and more skilled than they were before. Next, think about a different group, one that failed to achieve its purposes, that deteriorated in performance
capability over time, and whose members found the group experience far more frustrating than fulfilling
Spot activity of the RS CVn star {\sigma} Geminorum
We model the photometry of RS CVn star Geminorum to obtain new
information on the changes of the surface starspot distribution, i.e., activity
cycles, differential rotation and active longitudes. We use the previously
published Continuous Periods Search-method (CPS) to analyse V-band differential
photometry obtained between the years 1987 and 2010 with the T3 0.4 m Automated
Telescope at the Fairborn Observatory. The CPS-method divides data into short
subsets and then models the light curves with Fourier-models of variable orders
and provides estimates of the mean magnitude, amplitude, period and light curve
minima. These light curve parameters are then analysed for signs of activity
cycles, differential rotation and active longitudes. We confirm the presence of
two previously found stable active longitudes, synchronised with the orbital
period d and find eight events where the active longitudes
are disrupted. The epochs of the primary light curve minima rotate with a
shorter period d than the orbital motion. If the
variations in the photometric rotation period were to be caused by differential
rotation, this would give a differential rotation coefficient of . The presence of two slightly different periods of active regions may
indicate a superposition of two dynamo modes, one stationary in the orbital
frame and the other one propagating in the azimuthal direction. Our estimate of
the differential rotation is much higher than previous results. However,
simulations show that this can be caused by insufficient sampling in our data.Comment: 10 pages, 6 figures. Submitted to A&
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