High Efficiency Detection of Argon Scintillation Light of 128nm Using LAAPDs

The possibility of efficient collection and detection of vacuum ultraviolet light as emitted by argon, krypton, and xenon gas is studied. Absolute quantum efficiencies of large area avalanche photodiodes (LAAPDs) are derived at these wavelengths. VUV light of wavelengths down to the 128nm of Ar emission is shown to be detectable with silicon avalanche photodiodes at quantum efficiencies above 42%. Flexible Mylar foil overcoated with Al+MgF$_2$ is measured to have a specular reflectivity of $\sim$91% at argon emission wavelength. Low-pressure argon gas is shown to emit significant amounts of non-UV radiation. The average energy expenditure for the creation of non-UV photons in argon gas at this pressure is measured to be below 378 eV.Comment: 5 pages, 4 figures, Talk given at IEEE 2005 Nuclear Science Symposium and Medical Imaging Conference, Puerto Ric

Schooling for and with Democracy

Given the current challenges facing our democracy in the United States, the role of public schools in forming habits of democratic practice in our citizenry is as important today as ever. To explore this urgent topic, the author interviewed 13 leaders of 10 New York City public schools committed to educating for and with democracy. Six patterns of beliefs and practices emerged from the conversations, including commitments to intentionally developing informed, empathic, inclusive, inquiry-minded, confident, vocal, and involved citizens through parallel democratic structures for both adults and students. A seventh pattern was also identified; however, it took the shape of the absence of an intentional naming of democracy as it is being practiced. This raised a question for further discussion: To what degree is making this connection explicit in school communities important? Implications of these patterns are briefly discussed, and a few recommended next steps are offered for the consideration of educational leaders and policy makers. It is the hope and plan of the author to bring the group of interviewed school leaders together to discuss these patterns and dig more deeply into the work of schooling for and with democratic participation.https://educate.bankstreet.edu/faculty-staff/1043/thumbnail.jp

Coherent Schools, Powerful Learning: When Shared Beliefs Fuse School Culture, Structures, and Instruction

Describes the evolution of a theoretical model of school quality drawn from my experiences teaching at different schools, pursuing graduate studies, leading district policy and support networks, and partnering with school systems, as I presently do at Bank Street College of Education. The model positions schools as the key lever for improvement and equity in our public system and focuses on the coherence of school culture, structures, and instructional approach grounded in beliefs of human development and learning. Using two contrasting schools as cases to explore and develop this model, I offer one as an example of incoherence and the other, Humanities Preparatory Academy in New York City, as an exemplar of how culture, structures, and instruction are fused by shared beliefs and made manifest by leveraging a set of core values. I then turn to the role of districts and state agencies, which cannot directly generate coherence in schools from the outside in. Recent research underscores the importance of school-level coherence and also indicates that the ecosystem of schools must change to foster such coherence. I end with a brief discussion of our need to shift our systemic policies and approaches away from the reductive forces of high-stakes testing and instead embrace this holistic vision of schooling to shape future school improvement and reform efforts.https://educate.bankstreet.edu/faculty-staff/1061/thumbnail.jp

A Tablet-Computer App Displaying Runway Winds

We tested variants of a mobile meteorological tablet-computer application designed to help general aviation (GA) pilots land aircraft more safely under windy conditions. This “app” compared METAR runway wind information in several graphical and textual formats. Study 1 tested 25 GA pilots on 18 runway wind scenarios. Graphical METARs depicted the runway with a large arrow at 90°, representing the crosswind speed component, and a second arrow parallel to the runway, representing the headwind/tailwind component. We hypothesized that eliminating the need for complex mental calculation of wind components would increase speed and/or accuracy of information processing. Study 2 tested 17 pilots on 24 scenarios, employing the same basic method, but enhanced by color-coding the wind-component arrows according to each pilot’s previously stated maximums for landing wind risk-tolerance. Both studies showed that runwayrelative, two-arrow wind component depictions were significantly fastest and most efficient. Pilots unanimously preferred graphical displays over textual

Contributions of order O(mquark2){\cal O}(m_{\rm quark}^2) to Kℓ3K_{\ell 3} form factors and unitarity of the CKM matrix

The form factors for the $K_{\ell 3}$ semileptonic decay are computed to order $O(p^4)$ in generalized chiral perturbation theory. The main difference with the standard $O(p^4)$ expressions consists in contributions quadratic in quark masses, which are described by a single divergence-free low-energy constant, $A_3$. A new simultaneous analysis is presented for the CKM matrix element $V_{us}$, the ratio $F_K/F_{\pi}$, $K_{\ell 3}$ decay rates and the scalar form factor slope $\lambda_0$. This framework easily accommodates the precise value for $V_{ud}$ deduced from superallowed nuclear $\beta$-decays

Chiral two-loop pion-pion scattering parameters from crossing-symmetric constraints

Constraints on the parameters in the one- and two-loop pion-pion scattering amplitudes of standard chiral perturbation theory are obtained from explicitly crossing-symmetric sum rules. These constraints are based on a matching of the chiral amplitudes and the physical amplitudes at the symmetry point of the Mandelstam plane. The integrals over absorptive parts appearing in the sum rules are decomposed into crossing-symmetric low- and high-energy components and the chiral parameters are finally related to high-energy absorptive parts. A first application uses a simple model of these absorptive parts. The sensitivity of the results to the choice of the energy separating high and low energies is examined with care. Weak dependence on this energy is obtained as long as it stays below ~560 MeV. Reliable predictions are obtained for three two-loop parameters.Comment: 23 pages, 4 figures in .eps files, Latex (RevTex), our version of RevTex runs under Latex2.09, submitted to Phys. Rev. D,minor typographical corrections including the number at the end of the abstract, two sentences added at the end of Section 5 in answer to a referee's remar

Citizen Engagement through Design Space Exploration Integrating citizen knowledge and expert design in computational urban planning

A common understanding exists that citizens should become more involved in thedesign, planning, and governance of the city. Due to a lack of common platformsand difficulties in the meaningful integration of the participatory input, however,the tools and methods currently employed in citizen engagement are often illconnected to the design and governance tools and processes used by experts. Inthis paper we describe a Grasshopper and Rhino based approach, which allowsdesigners to share a subset of the design space formed by parametric designvariants with citizens via the online interface Beta.Speckle. In a user study weevaluated the usability of the tool as well as studied the design choices ofparticipants, which were found to be influenced by preferences for visual orderand underlying economic, social, and environmental values. For the futuredesign of participatory exercises, it was concluded that indicators relating tocitizens' values and preferences will allow for a more effective exploration of thedesign space and increase the meaningfulness of results

ArDM: a ton-scale liquid Argon experiment for direct detection of Dark Matter in the Universe

The ArDM project aims at developing and operating large noble liquid detectors to search for direct evidence of Weakly Interacting Massive Particle (WIMP) as Dark Matter in the Universe. The initial goal is to design, assemble and operate a $\approx$1 ton liquid Argon prototype to demonstrate the feasibility of a ton-scale experiment with the required performance to efficiently detect and sufficiently discriminate backgrounds for a successful WIMP detection. Our design addresses the possibility to detect independently ionization and scintillation signals. In this paper, we describe this goal and the conceptual design of the detector.Comment: 5 pages, 3 figures, Talk given at IXth international conference on Topics in Astroparticle and Underground Physics (TAUP05), Zaragoza, (Spain

B\"acklund transformation for non-relativistic Chern-Simons vortices

A B\"acklund transformation yielding the static non-relativistic Chern-Simons vortices of Jackiw and Pi is presented.Comment: 7 pages plain Te