1,907 research outputs found
Successfully Executing Ambitious Strategies in Government: An Empirical Analysis
How are senior government executives who attempt to execute an ambitious vision requiring significant strategic change in their organizations able to succeed? How do they go about formulating a strategy in the first place? What managerial and leadership techniques do they use to execute their strategy? In this paper, these questions are examined by comparing (so as to avoid the pitfalls of "best practices" research) management and leadership behaviors of a group of agency leaders from the Clinton and Bush administrations identified by independent experts as having been successful at executing an ambitious strategy with a control group consisting of those the experts identified as having tried but failed at significant strategic change, along with counterparts to the successes, who had the same position as they in a different administration. We find a number of differentiators (such as using strategic planning, monitoring performance metrics, reorganizing, and having a smaller number of goals), while other techniques either were not commonly used or failed to differentiate (such as establishing accountability systems or appeals to public service motivation). We find that agencies that the successes led had significantly lower percentages of political appointees than the average agency in the government. One important finding is that failures seem to have used techniques recommended specifically for managing transformation or change as frequently as successes did, so use of such techniques does not differentiate successes from failures. However, failures (and counterparts) used techniques associated with improving general organizational performance less than successes.
Noise Correlation in Cosmic Microwave Background Experiments
Many analyses of microwave background experiments neglect the correlation of
noise in different frequency or polarization channels. We show that these
correlations, should they be present, can lead to severe misinterpretation of
an experiment. In particular, correlated noise arising from either electronics
or atmosphere may mimic a cosmic signal. We quantify how the likelihood
function for a given experiment varies with noise correlation, using both
simple analytic models and actual data. For a typical microwave background
anisotropy experiment, noise correlations at the level of 1\% of the overall
noise can seriously {\it reduce} the significance of a given detection.Comment: Analysis generalized; conclusions unaltere
Cluster evolution as a probe of primordial density fluctuations
Although COBE's detection of large angle microwave background anisotropies fixes the amplitude of density fluctuations on length scales k exp -1 approximately = (300-6000) h(exp -1)Mpc, what is crucial for the level of large scale clustering is the amplitude of density fluctuations on scales (5-50) h(exp -1)Mpc. The level of dynamical clustering is usually parameterized by the size of the mass fluctuations in 8 h exp -1 Mpc spheres, sigma sub 8. For the cold dark matter model, COBE gives sigma sub 8 approximately = 1, while models with extra large scale power give sigma sub 8 approximately = 1/2. The most massive clusters of galaxies (greater than or approximately = 10 exp 15 solar mass) form from rare 'peak patches' found in the initial mass density distribution. Their abundance as a function of redshift is a sensitive probe of the wave number band k(exp -1) approx. (3-8) h(exp -1)Mpc, hence of sigma sub 8, and so cluster evolution can discriminate among models allowed by the COBE results. We use our Hierarchical Peaks Method, which accurately reproduces the results of P3M N-body simulations, to calculate the evolution of cluster x-ray flux counts, luminosity, and temperature functions as a function of sigma sub 8 for CDM models and those with more large scale power. We find that the EMSS and Edge et al. cluster samples support sigma sub 8 in the range from approx. 0.6-0.9, and that models with more large scale power (and hence flatter fluctuation spectra in the cluster regime) fit the x-ray bright end better
Primeval galaxies in the sub-mm and mm
Although the results of COBE's FIRAS experiment 1 constrain the deviation in energy from the CMB blackbody in the 500-5000 micron range to be delta E/E, sub cmb less than 0.005, primeval galaxies can still lead to a brilliant sub-mm sky of non-Gaussian sources that are detectable at 10 inch resolution from planned arrays such as SCUBA on the James Clerk Maxwell Telescope and, quite plausibly, at sub-arcsecond resolution in planned mm and sub-mm interferometers. Here, we apply our hierarchical peaks method to a CDM model to construct sub-mm and mm maps of bursting PG's appropriate for these instruments with minimum contours chosen to correspond to realistic observational parameters for them and which pass the FIRAS limits
Cutworm damage to the Missouri corn crop, 1977-1980
Cover title.Includes bibliographical references
An investigation of liquid crystalline and semiconducting blends for applications in photovoltaics
We investigated a number of novel liquid crystalline semiconductors which have been synthesised in house at the University of Hull. The electrochemical and optical properties of these materials were studied, in order to assess their suitability as donor or acceptor materials for photovoltaic (PV) devices. We investigated the HOMO and LUMO energies of materials with similar chemical structures and hence identified the effect of adding or removing certain molecular groups. Compounds with a benzothiadiazole-thiophene structure were found to be potentially low band gap electron donor materials with perylene based compounds as electron acceptors. Fluorene-thiophene based compounds were also identified as potential electron donors. Charge mobility was studied for several electron donor compounds with similar chemical structures. Donor and acceptor (D/A) blends were investigated and compared to the pure compounds. The Time of Flight (TOF) technique was used to measure mobility. For the pure donor a reduction in mobility is seen when the molecule chain is extended with two additional thiophene groups. The electron mobility of the blends was higher by 2 orders of magnitude than that of the pure acceptor. This provides the blends with balanced charge transport for PV devices.We fabricated and characterised bulk heterojunction PV devices mixing various donor materials with the same perylene acceptor. The highest device efficiency was produced by a fluorene-thiophene structured donor compound. The fill factor (FF) for all devices was poor and this may be attributed to the acceptor material. We investigated the phase transitions of several D/A blends. An improved device efficiency was produced when we annealed within the liquid crystal phase. We investigated the thin film morphology using an atomic force microscope (AFM) and correlated domain size to PV device performance
An Improved Measurement of the Hubble Constant from the Sunyaev-Zeldovich Effect
We present a determination of the Hubble constant from measurements of the
Sunyaev-Zeldovich Effect (SZE) in an orientation-unbiased sample of 7 z < 0.1
galaxy clusters. With improved X-ray models and a more accurate 32-GHz
calibration, we obtain H_O = 64+14-11 +/- 14_sys km/s/Mpc. for a standard CDM
cosmology, or 66+14-11 +/- 15_sys km/s/Mpc for a flat LambdaCDM cosmology. In
combination with X-ray cluster measurements and the BBN value for Omega_B, we
find Omega_M = 0.32 +/- 0.05.Comment: 5 pp., Accepted for publication in ApJ
Assessing An Economics Programme: Hansen Proficiencies, ePortfolio, and Undergraduate Research
Numerous sources calling for more accountability in higher education are putting increased pressure on many economics departments to develop assessment plans. This paper discusses a set of principles for programmatic assessment gleaned from the assessment literature, while highlighting one US economic department's journey to develop an assessment of student learning outcomes based on Hansen's proficiencies. We explain the curriculum reforms that culminate with independent undergraduate research as suggested by the highest level of Hansen's proficiencies. We describe ePortfolios which showcase student abilities and integrate evidence of student learning across the curriculum. For departments without direct guidance from accreditation boards or other agencies, we put forth a process of forming programmatic assessment in economics.
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