2,927 research outputs found
Perspectives about living on the horns of dilemmas: An analysis of gender factors related to superintendent decision-making and problem-solving
The major focus of this paper is a gender-based analysis of school superintendent decision-making and problem-solving as well as an investigation of contemporary leadership dilemmas. The findings are based on responses from 258 superintendents of K-12 school districts in Delaware, Maryland, New Jersey, New York, and Pennsylvania collected over a period of three years (2009-2011). The researchers also conducted 18 comprehensive qualitative “face-to-face” interviews with self-selected superintendents who responded to the quantitative survey. The intended outcome of this article is for education policy makers, professors, and practitioners to comprehensively examine the extent and degree of various dilemmas confronting the Mid-Atlantic Region school superintendent sample and to evaluate the decision-making and problem-solving approaches used by them. The study results that are presented will serve as valuable references to not only individual superintendents but also to university administrator preparation professors and to state administrator licensure agencies because it is important for all aspiring superintendents to know the various issues associated with education leadership and the personal and professional dilemmas that they need to be prepared to face as they embark on a career to improve schooling in the United States
Search for the Hypothetical pi -> mu x Decay
The KARMEN collaboration has reported the possible observation of a hitherto
unknown neutral and weakly interacting particle x, which is produced in the
decay pi -> mu + x with a mass m(x) = 33.9 MeV. We have searched for this
hypothetical decay branch by studying muons from pion decay in flight with the
LEPS spectrometer at the piE3 channel at PSI and find branching ratios BR(pi-
to mu- anti-x) < 4e-7 and BR(pi+ to mu+ x) < 7e-8 (95\% C.L.). Together with
the limit BR > 2e-8 derived in a recent theoretical paper our result would
leave only a narrow region for the existence of x if it is a heavy neutrino.Comment: 10 pages, TeX (uses epsf), 3 Postscript figures uu-encode
Search for Light Gauge Bosons of the Dark Sector at the Mainz Microtron
A new exclusion limit for the electromagnetic production of a light U(1)
gauge boson {\gamma}' decaying to e^+e^- was determined by the A1 Collaboration
at the Mainz Microtron. Such light gauge bosons appear in several extensions of
the standard model and are also discussed as candidates for the interaction of
dark matter with standard model matter. In electron scattering from a heavy
nucleus, the existing limits for a narrow state coupling to e^+e^- were reduced
by nearly an order of magnitude in the range of the lepton pair mass of 210
MeV/c^2 < m_e^+e^- < 300 MeV/c^2. This experiment demonstrates the potential of
high current and high resolution fixed target experiments for the search for
physics beyond the standard model.Comment: 4 pages, 7 figure
Constraining the Hadronic Contributions to the Muon Anomalous Magnetic Moment
The mini-proceedings of the Workshop on "Constraining the hadronic
contributions to the muon anomalous magnetic moment" which included the "13th
meeting of the Radio MonteCarLow WG" and the "Satellite meeting R-Measurements
at BES-III" held in Trento from April 10th to 12th, 2013, are presented. This
collaboration meeting aims to bring together the experimental e+e- collider
communities from BaBar, Belle, BESIII, CMD2, KLOE, and SND, with theorists
working in the fields of meson transitions form factors, hadronic contributions
to (g-2)_\mu and effective fine structure constant, and development of Monte
Carlo generator and Radiative Corrections for precision e+e- and tau physics.Comment: 45 pages, 17 contributions. Editors: P. Masjuan and G. Venanzon
Evidence for the tongue of ionization under northward interplanetary magnetic field conditions
[1] The activities of the International Ionospheric Tomography Community open up new possibilities of simultaneously imaging the large-scale spatial structure of the ionosphere in different longitude sectors. In the study, tomography receiver chains in Scandinavia and Greenland were used to provide a wide view of the plasma density structure in the winter, magnetic postnoon sector under conditions of stable, positive interplanetary magnetic field B z component. The spatial distributions of the plasma are discussed in light of a high-latitude plasma convection pattern pertinent to the conditions, which is supported by DMSP flow measurements. The observations are consistent with a tongue of dayside photoionization being drawn antisunward by the convection pattern to form an arc of enhanced plasma density around the periphery of the polar cap
Calculation of the Two-Loop Heavy-Flavor Contribution to Bhabha Scattering
We describe in detail the calculation of the two-loop corrections to the QED
Bhabha scattering cross section due to the vacuum polarization by heavy
fermions. Our approach eliminates one mass scale from the most challenging part
of the calculation and allows us to obtain the corrections in a closed
analytical form. The result is valid for arbitrary values of the heavy fermion
mass and the Mandelstam invariants, as long as s,t,u >> m_e^2.Comment: 43 pages, 8 figures; added reference
Study of the decay phi--> f0(980)g --> pi+pi-g with the KLOE detector
We measured, with the KLOE detector, the spectrum of pi+pi- invariant mass in
a sample of 6.7 x 10^5 e+e- --> pi+pi-g events with the photon at large polar
angle (theta_g>45^o) at a centre of mass energy sqrt(s) around the phi mass. We
observe a clear contribution from the intermediate process phi --> f0(980)g. A
sizeable effect is also observed in the distribution of the forward-backeard
asymmetry. We use different theoretical models to fit the spectrum and we
determine the f_0 mass and coupling constants to the phi, to pi+pi- and to KK.Comment: 15 pages, 6 figures, submitted to Phys.Lett.
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