5,010 research outputs found
Superintendent and School Board Relations: Impacting Achievement through Collaborative Understanding of Roles and Responsibilities
One of the most important and influential persons in the governance structure of the local school district is the Superintendent of Schools. Functioning as the CEO of the district, the superintendent is responsible for a myriad of functions. Examples include daily operations inclusive of transportation and finance, curriculum and policy implementation, media relations, and empowering leaders. However, as Meador (2014) contends, a crucial role is that of board liaison. The Superintendent is responsible for keeping the board informed, making recommendations regarding district operations, and setting the board agenda. It is interesting to note that the superintendent does participate in board meetings, but in an advisory capacity. Finally, the superintendent is responsible for enacting all mandates approved by the school board
High-resolution Spectroscopy of Extremely Metal-poor Stars in the Least Evolved Galaxies: Leo IV
We present high-resolution Magellan/MIKE spectroscopy of the brightest star in the ultra-faint dwarf galaxy Leo IV. We measure an iron abundance of [Fe/H] = –3.2, adding to the rapidly growing sample of extremely metal-poor (EMP) stars being identified in Milky Way satellite galaxies. The star is enhanced in the α elements Mg, Ca, and Ti by ~0.3 dex, very similar to the typical Milky Way halo abundance pattern. All of the light and iron-peak elements follow the trends established by EMP halo stars, but the neutron-capture elements Ba and Sr are significantly underabundant. These results are quite similar to those found for stars in the ultra-faint dwarfs Ursa Major II, Coma Berenices, Boötes I, and Hercules, suggesting that the chemical evolution of the lowest-luminosity galaxies may be universal. The abundance pattern we observe is consistent with predictions for nucleosynthesis from a Population III supernova explosion. The extremely low metallicity of this star also supports the idea that a significant fraction (≳10%) of the stars in the faintest dwarfs have metallicities below [Fe/H] = –3.0
Cavity-aided non-demolition measurements for atom counting and spin squeezing
Probing the collective spin state of an ensemble of atoms may provide a means
to reduce heating via the photon recoil associated with the measurement and
provide a robust, scalable route for preparing highly entangled states with
spectroscopic sensitivity below the standard quantum limit for coherent spin
states. The collective probing relies on obtaining a very large optical depth
that can be effectively increased by placing the ensemble within an optical
cavity such that the probe light passes many times through the ensemble. Here
we provide expressions for measurement resolution and spectroscopic enhancement
in such cavity-aided non-demolition measurements as a function of cavity
detuning. In particular, fundamental limits on spectroscopic enhancements in
Rb are considered.Comment: Substantially shortened. 19 pages, 16 figure
Relaxation oscillations, stability, and cavity feedback in a superradiant Raman laser
We experimentally study the relaxation oscillations and amplitude stability
properties of an optical laser operating deep into the bad-cavity regime using
a laser-cooled Rb Raman laser. By combining measurements of the laser
light field with nondemolition measurements of the atomic populations, we infer
the response of the gain medium represented by a collective atomic Bloch
vector. The results are qualitatively explained with a simple model.
Measurements and theory are extended to include the effect of intermediate
repumping states on the closed-loop stability of the oscillator and the role of
cavity feedback on stabilizing or enhancing relaxation oscillations. This
experimental study of the stability of an optical laser operating deep into the
bad-cavity regime will guide future development of superradiant lasers with
ultranarrow linewidths.Comment: 9 pages, 6 figure
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