23,260 research outputs found
Improving Photometry and Astrophotography by Eliminating Dark Frames and Flat Fields
I report on the efforts to improve the dark frames and flat fielding procedure for the charged-coupled device (CCD) camera for the Celestron C14 telescope at the UNH observatory. Dark frames are images taken while the shutter of the camera is closed so that only electronic and dark noise and other internal inconsistencies are recorded. These are important because they allow astronomers to subtract out interference from dark current. Additionally, flat fields are images of the entire field of the telescope so that the brightness in the pixels of the telescope’s field of view is uniform. Flat fields are vital since they provide a consistent illumination for all photos taken from the camera. With the combination of these two features, I was able to optimize the clarity of the telescope’s pictures and show through photometry how the new calibrated images appear in comparison to images prior to the calibration. Overall, these enhanced photographs will assist in achieving better results for future astronomy labs at UNH
Parameterized Complexity of Graph Constraint Logic
Graph constraint logic is a framework introduced by Hearn and Demaine, which
provides several problems that are often a convenient starting point for
reductions. We study the parameterized complexity of Constraint Graph
Satisfiability and both bounded and unbounded versions of Nondeterministic
Constraint Logic (NCL) with respect to solution length, treewidth and maximum
degree of the underlying constraint graph as parameters. As a main result we
show that restricted NCL remains PSPACE-complete on graphs of bounded
bandwidth, strengthening Hearn and Demaine's framework. This allows us to
improve upon existing results obtained by reduction from NCL. We show that
reconfiguration versions of several classical graph problems (including
independent set, feedback vertex set and dominating set) are PSPACE-complete on
planar graphs of bounded bandwidth and that Rush Hour, generalized to boards, is PSPACE-complete even when is at most a constant
Open subgroups of the automorphism group of a right-angled building
We study the group of type-preserving automorphisms of a right-angled
building, in particular when the building is locally finite. Our aim is to
characterize the proper open subgroups as the finite index closed subgroups of
the stabilizers of proper residues.
One of the main tools is the new notion of firm elements in a right-angled
Coxeter group, which are those elements for which the final letter in each
reduced representation is the same. We also introduce the related notions of
firmness for arbitrary elements of such a Coxeter group and -flexibility of
chambers in a right-angled building. These notions and their properties are
used to determine the set of chambers fixed by the fixator of a ball. Our main
result is obtained by combining these facts with ideas by Pierre-Emmanuel
Caprace and Timoth\'ee Marquis in the context of Kac-Moody groups over finite
fields, where we had to replace the notion of root groups by a new notion of
root wing groups.Comment: 29 page
The Senior Communicator of the Future – Competencies and Training Needs
Sanchez (2005) proposed the future leading communicator as: “the true professional [who] will be an adroit strategist, a creative technician and a skilled facilitator – a friend of technology and an exponent of life-long learning. The future is a global voyage into the art and science of communication, where the successful communicator will be like the men and women of the Renaissance, pulling it all together, but in the high tech environment of the 21st century.” (pp.10-11)
Since the 1980s, starting from Broom and Dozier’s seminal studies on the nature of public relations employment and professionalism, there has been discussion of the career paths, competencies and training needs of public relations and corporate communication professionals. More recently, the Arthur W. Page Society (2007) has scoped the role of the Chief Communication Officer’s role in the Authentic Enterprise which placed the communicator at C-Level (Executive Board) or close to it (the marzipan layer) of the corporation.
The research to be reported in this paper analyses the responses of leading European and international senior-level communicators as to the knowledge, skills, relationships, 360-degree vision, and managerial abilities that senior communications professionals will need in five years’ time, and what it takes to prepare the next generation of leaders in globally integrated organizations.
The paper will also reflect on recent academic and practice literature about the nature of these competencies and discusses the potential methods and routes of their delivery. It will also consider the current operating situation, the challenges facing senior corporate communicators and their future needs.
The outcomes will include recommendations for consideration by educators and employers, especially those operating in cross-cultural environments
On the "initial" Angular Momentum of Galaxies
Spherical density profiles and specific angular momentum profiles of Dark
Matter halos found in cosmological N-body simulations have been measured
extensively. The distribution of the total angular momentum of dark matter
halos is also used routinely in semi-analytic modeling of the formation of disk
galaxies. However, it is unclear whether the initial (i.e. at the time the halo
is assembled) angular momentum distributions of baryons is related to the dark
matter at all. Theoretical models for ellipticities in weak lensing studies
often rely on an assumed correlation of the angular momentum vectors of dark
matter and gas in galaxies. Both of these assumptions are shown to be in
reasonable agreement with high resolution cosmological smoothed particle
hydrodynamical simulations that follow the dark matter as long as only
adiabatic gas physics are included. However, we argue that in more realistic
models of galaxy formation one expects pressure forces to play a significant
role at turn--around. Consequently the torquing force on DM and baryons will be
uncorrelated and their respective angular momenta are not expected to align. An
SPH simulation with ad-hoc feedback is presented that illustrates these
effects. Massive low redshift elliptical galaxies may be a notable exception
where "light may trace mass".Comment: 4 latex pages (uses sprocl.sty), 1 eps figure. To appear in the
proceedings of "The Shapes of Galaxies and Their Halos", Yale, May 200
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