737 research outputs found
An Examination of how participation in a cohort-based leadership development program for high-potential employees contributes to the development of leaders at a Major Professional services firm in the United States
University of Minnesota Ph.D. dissertation. December 2014. Major: Organizational Leadership, Policy, and Development. Advisor: David A. Christesen, Shari L. Peterson. 1 computer file (PDF); ix, 170 pages, appendices A-E.This case study examined the leadership development experience of employees who participated in a high-potential leadership development program within a major professional services firm in the Midwest United States. Leadership development is a top priority for many organizations and a critical driver of success. Effective leadership is also recognized as a source of sustainable competitive advantage and greater market value. Despite these compelling factors, the need for developing leaders has been listed among organizations' top concerns for more than a decade. These factors create challenges in developing the talent needed for organizations to remain competitive. As these challenges converge they intensify the need for well-planned, consistent, and rigorous development of high-potential talent. These needs support the call for a greater understanding of how participation in a cohort-based leadership development program contributes to high-potentials' development as leaders
Thermodynamics of natural images
The scale invariance of natural images suggests an analogy to the statistical
mechanics of physical systems at a critical point. Here we examine the
distribution of pixels in small image patches and show how to construct the
corresponding thermodynamics. We find evidence for criticality in a diverging
specific heat, which corresponds to large fluctuations in how "surprising" we
find individual images, and in the quantitative form of the entropy vs. energy.
The energy landscape derived from our thermodynamic framework identifies
special image configurations that have intrinsic error correcting properties,
and neurons which could detect these features have a strong resemblance to the
cells found in primary visual cortex
Measuring Physical and visual material properties to determine their perceives degree of naturalness
Crystal structure of CyanoQ from the thermophilic cyanobacterium Thermosynechococcus elongatus and detection in isolated photosystem II complexes.
The PsbQ-like protein, termed CyanoQ, found in the cyanobacterium Synechocystis sp. PCC 6803 is thought to bind to the lumenal surface of photosystem II (PSII), helping to shield the Mn(4)CaO(5) oxygen-evolving cluster. CyanoQ is, however, absent from the crystal structures of PSII isolated from thermophilic cyanobacteria raising the possibility that the association of CyanoQ with PSII might not be a conserved feature. Here, we show that CyanoQ (encoded by tll2057) is indeed expressed in the thermophilic cyanobacterium Thermosynechococcus elongatus and provide evidence in support of its assignment as a lipoprotein. Using an immunochemical approach, we show that CyanoQ co-purifies with PSII and is actually present in highly pure PSII samples used to generate PSII crystals. The absence of CyanoQ in the final crystal structure is possibly due to detachment of CyanoQ during crystallisation or its presence in sub-stoichiometric amounts. In contrast, the PsbP homologue, CyanoP, is severely depleted in isolated PSII complexes. We have also determined the crystal structure of CyanoQ from T. elongatus to a resolution of 1.6 Å. It lacks bound metal ions and contains a four-helix up-down bundle similar to the ones found in Synechocystis CyanoQ and spinach PsbQ. However, the N-terminal region and extensive lysine patch that are thought to be important for binding of PsbQ to PSII are not conserved in T. elongatus CyanoQ. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11120-014-0010-z) contains supplementary material, which is available to authorized users
The Effect of Nonstationarity on Models Inferred from Neural Data
Neurons subject to a common non-stationary input may exhibit a correlated
firing behavior. Correlations in the statistics of neural spike trains also
arise as the effect of interaction between neurons. Here we show that these two
situations can be distinguished, with machine learning techniques, provided the
data are rich enough. In order to do this, we study the problem of inferring a
kinetic Ising model, stationary or nonstationary, from the available data. We
apply the inference procedure to two data sets: one from salamander retinal
ganglion cells and the other from a realistic computational cortical network
model. We show that many aspects of the concerted activity of the salamander
retinal neurons can be traced simply to the external input. A model of
non-interacting neurons subject to a non-stationary external field outperforms
a model with stationary input with couplings between neurons, even accounting
for the differences in the number of model parameters. When couplings are added
to the non-stationary model, for the retinal data, little is gained: the
inferred couplings are generally not significant. Likewise, the distribution of
the sizes of sets of neurons that spike simultaneously and the frequency of
spike patterns as function of their rank (Zipf plots) are well-explained by an
independent-neuron model with time-dependent external input, and adding
connections to such a model does not offer significant improvement. For the
cortical model data, robust couplings, well correlated with the real
connections, can be inferred using the non-stationary model. Adding connections
to this model slightly improves the agreement with the data for the probability
of synchronous spikes but hardly affects the Zipf plot.Comment: version in press in J Stat Mec
The cytoplasm of living cells: A functional mixture of thousands of components
Inside every living cell is the cytoplasm: a fluid mixture of thousands of
different macromolecules, predominantly proteins. This mixture is where most of
the biochemistry occurs that enables living cells to function, and it is
perhaps the most complex liquid on earth. Here we take an inventory of what is
actually in this mixture. Recent genome-sequencing work has given us for the
first time at least some information on all of these thousands of components.
Having done so we consider two physical phenomena in the cytoplasm: diffusion
and possible phase separation. Diffusion is slower in the highly crowded
cytoplasm than in dilute solution. Reasonable estimates of this slowdown can be
obtained and their consequences explored, for example, monomer-dimer equilibria
are established approximately twenty times slower than in a dilute solution.
Phase separation in all except exceptional cells appears not to be a problem,
despite the high density and so strong protein-protein interactions present. We
suggest that this may be partially a byproduct of the evolution of other
properties, and partially a result of the huge number of components present.Comment: 11 pages, 1 figure, 1 tabl
Building Success in Online Educational Programs for Adult Learners
The purpose of this symposium is to explore multiple perspectives on building and maintaining high quality online educational programs in university settings for adult learners
Toward a statistical mechanics of four letter words
We consider words as a network of interacting letters, and approximate the
probability distribution of states taken on by this network. Despite the
intuition that the rules of English spelling are highly combinatorial (and
arbitrary), we find that maximum entropy models consistent with pairwise
correlations among letters provide a surprisingly good approximation to the
full statistics of four letter words, capturing ~92% of the multi-information
among letters and even "discovering" real words that were not represented in
the data from which the pairwise correlations were estimated. The maximum
entropy model defines an energy landscape on the space of possible words, and
local minima in this landscape account for nearly two-thirds of words used in
written English
Fiducial Reference Measurements for Satellite Ocean Colour (FRM4SOC)
Earth observation data can help us understand and address some of the grand challenges and threats facing us today as a species and as a planet, for example climate change and its impacts and sustainable use of the Earth’s resources. However, in order to have confidence in earth observation data, measurements made at the surface of the Earth, with the intention of providing verification or validation of satellite-mounted sensor measurements, should be trustworthy and at least of the same high quality as those taken with the satellite sensors themselves. Metrology tells us that in order to be trustworthy, measurements should include an unbroken chain of SI-traceable calibrations and comparisons and full uncertainty budgets for each of the in situ sensors. Until now, this has not been the case for most satellite validation measurements. Therefore, within this context, the European Space Agency (ESA) funded a series of Fiducial Reference Measurements (FRM) projects targeting the validation of satellite data products of the atmosphere, land, and ocean, and setting the framework, standards, and protocols for future satellite validation efforts. The FRM4SOC project was structured to provide this support for evaluating and improving the state of the art in ocean colour radiometry (OCR) and satellite ocean colour validation through a series of comparisons under the auspices of the Committee on Earth Observation Satellites (CEOS). This followed the recommendations from the International Ocean Colour Coordinating Group’s white paper and supports the CEOS ocean colour virtual constellation. The main objective was to establish and maintain SI traceable ground-based FRM for satellite ocean colour and thus make a fundamental contribution to the European system for monitoring the Earth (Copernicus). This paper outlines the FRM4SOC project structure, objectives and methodology and highlights the main results and achievements of the project: (1) An international SI-traceable comparison of irradiance and radiance sources used for OCR calibration that set measurement, calibration and uncertainty estimation protocols and indicated good agreement between the participating calibration laboratories from around the world; (2) An international SI-traceable laboratory and outdoor comparison of radiometers used for satellite ocean colour validation that set OCR calibration and comparison protocols; (3) A major review and update to the protocols for taking irradiance and radiance field measurements for satellite ocean colour validation, with particular focus on aspects of data acquisition and processing that must be considered in the estimation of measurement uncertainty and guidelines for good practice; (4) A technical comparison of the main radiometers used globally for satellite ocean colour validation bringing radiometer manufacturers together around the same table for the first time to discuss instrument characterisation and its documentation, as needed for measurement uncertainty estimation; (5) Two major international side-by-side field intercomparisons of multiple ocean colour radiometers, one on the Atlantic Meridional Transect (AMT) oceanographic cruise, and the other on the Acqua Alta oceanographic tower in the Gulf of Venice; (6) Impact and promotion of FRM within the ocean colour community, including a scientific road map for the FRM-based future of satellite ocean colour validation and vicarious calibration (based on the findings of the FRM4SOC project, the consensus from two major international FRM4SOC workshops and previous literature, including the IOCCG white paper on in situ ocean colour radiometry)
Universal Statistical Behavior of Neural Spike Trains
We construct a model that predicts the statistical properties of spike trains
generated by a sensory neuron. The model describes the combined effects of the
neuron's intrinsic properties, the noise in the surrounding, and the external
driving stimulus. We show that the spike trains exhibit universal statistical
behavior over short times, modulated by a strongly stimulus-dependent behavior
over long times. These predictions are confirmed in experiments on H1, a
motion-sensitive neuron in the fly visual system.Comment: 7 pages, 4 figure
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