20,200 research outputs found
The status of music education in the public junior high schools of Massachusetts as of the year 1945-1955
Thesis (Ed.M.)--Boston Universit
High Voltage CMOS Control Interface for Astronomy - Grade Charged Coupled Devices
The Pan-STARRS telescope consists of an array of smaller mirrors viewed by a
Gigapixel arrays of CCDs. These focal planes employ Orthogonal Transfer CCDs
(OTCCDs) to allow on-chip image stabilization. Each OTCCD has advanced logic
features that are controlled externally. A CMOS Interface Device for High
Voltage has been developed to provide the appropiate voltage signal levels from
a readout and control system designated STARGRASP. OTCCD chip output levels
range from -3.3V to 16.7V, with two different output drive strenghts required
depending on load capacitance (50pF and 1000pF), with 24mA of drive and a rise
time on the order of 100ns. Additional testing ADC structures have been
included in this chip to evaluate future functional additions for a next
version of the chip.Comment: 13 pages, 17 gigure
Comparison of numerical methods for the calculation of cold atom collisions
Three different numerical techniques for solving a coupled channel
Schroedinger equation are compared. This benchmark equation, which describes
the collision between two ultracold atoms, consists of two channels, each
containing the same diagonal Lennard-Jones potential, one of positive and the
other of negative energy. The coupling potential is of an exponential form. The
methods are i) a recently developed spectral type integral equation method
based on Chebyshev expansions, ii) a finite element expansion, and iii) a
combination of an improved Numerov finite difference method and a Gordon
method. The computing time and the accuracy of the resulting phase shift is
found to be comparable for methods i) and ii), achieving an accuracy of ten
significant figures with a double precision calculation. Method iii) achieves
seven significant figures. The scattering length and effective range are also
obtained.Comment: 22 pages, 3 figures, submitted to J. Comput. Phys. documentstyle
[thmsa,sw20aip]{article} in .te
Nonlinear Dynamics in the Resonance Lineshape of NbN Superconducting Resonators
In this work we report on unusual nonlinear dynamics measured in the
resonance response of NbN superconducting microwave resonators. The nonlinear
dynamics, occurring at relatively low input powers (2-4 orders of magnitude
lower than Nb), and which include among others, jumps in the resonance
lineshape, hysteresis loops changing direction and resonance frequency shift,
are measured herein using varying input power, applied magnetic field, white
noise and rapid frequency sweeps. Based on these measurement results, we
consider a hypothesis according to which local heating of weak links forming at
the boundaries of the NbN grains are responsible for the observed behavior, and
we show that most of the experimental results are qualitatively consistent with
such hypothesis.Comment: Updated version (of cond-mat/0504582), 16 figure
Geological and site specific factors influencing earthquake hazard assessment for New Brunswick, Canada
Seismic hazard studies by Earthquakes Canada place most of New Brunswick in the moderate part of the hazard range. Limitations are identified with the documented earthquake database suggesting that revisions are necessary for location and magnitude of some of the known historical earthquakes. In addition, the disturbance from a given event magnitude can be modified by local geological conditions and site specific factors. This is particularly true for New Brunswick, where many of the communities were settled along river valleys and coastal areas, which are under-lain by thick deposits of glacial and alluvial sediments that can amplify ground motion. The historical documentation and paleoseismic studies that identify seismic-generated disturbances are reviewed in this paper. Ground motion from both moderate (4 MN) local and large (> 5 MN) regional earthquakes represents a hazard at some locations and particularly those sites adjacent to steep slopes or sites underlain by thick surficial deposits. Amplification of ground motion would be expected at sites overlying low shear wave velocity zones typical of alluvial sediments. This may explain the larger shaking effects experienced in the downtown area of Fredericton from distant earthquakes. Alteration of springs, rivers and groundwater supplies has happened as a result of earthquakes, although few effects remain permanent. Reports of earthquake-generated tsunamis and lake seiches are rare for New Brunswick. Earthquake-induced rock falls occurred along some rock slopes during moderate earthquakes in 1855 and 1937, and a landslide occurred in marine sediments possibly triggered by a minor unrecorded local tremor in 1977. This study identifies the need for future paleoseismic research and microzonation studies for the major communities within the province.
RÉSUMÉ
Des études de l’aléa sismique réalisées par Séismes Canada situent la majeure partie du Nouveau‑Brunswick au niveau moyen de l’échelle de l’aléa. La base de données sismologiques documentées fait part de restrictions laissant supposer la nécessité de révisions de l’emplacement et de la magnitude de certains des tremblements de terre passés connus. De plus, les secousses dues à la magnitude d’un séisme donné peuvent être modifiées par les conditions géologiques locales et par des facteurs propres à l’emplacement. C’est particulièrement le cas au Nouveau‑Brunswick où de nombreuses localités se sont implantées le long de vallées fluviales et de secteurs côtiers qui reposent sur des dépôts épais de sédiments glaciaires et alluvionnaires pouvant amplifier les mouvements du sol. Cet article passe en revue la documentation historique et les études paléosismiques qui définissent les secousses sismiques. Les mouvements du sol que produisent les tremblements de terre régionaux importants (> 5 MN) et locaux moyens (4 MN) représentent un aléa en certains endroits, particulièrement à proximité des pentes abruptes ou des secteurs reposant sur des dépôts superficiels épais. Une amplification des mouvements du sol peut être anticipée dans les secteurs recouvrant des zones de faible vitesse d’ondes transversales typiques des sédiments alluvionnaires. Une telle situation pourrait expliquer les secousses plus marquées vécues dans le centre‑ville de Fredericton par suite de tremblements de terre éloignés. Certains séismes ont modifié des ruisseaux, des rivières et des réserves d’eaux souterraines, mais de tels effets sont rarement permanents. Il est rare qu’on signale des tsunamis et des seiches sur des lacs dus à des tremblements de terre au Nouveau‑Brunswick. Des éboulements provoqués par des séismes sont survenus le long de certaines pentes rocheuses au cours de tremblements de terre moyens en 1855 et en 1937, et un glissement de terrain possiblement déclenché par une faible secousse sismique locale non enregistrée en 1977 s’est produit dans des sédiments marins. L’étude démontre la nécessité d’études de microzonation et de recherches paléosismiques futures visant les principales localités de la province.
[Traduit par la redaction
Ionization potentials in the limit of large atomic number
By extrapolating the energies of non-relativistic atoms and their ions with
up to 3000 electrons within Kohn-Sham density functional theory, we find that
the ionization potential remains finite and increases across a row, even as
. The local density approximation becomes chemically
accurate (and possibly exact) in some cases. Extended Thomas-Fermi theory
matches the shell-average of both the ionization potential and density change.
Exact results are given in the limit of weak electron-electron repulsion.Comment: 4 pages, 5 figure
R-matrix Floquet theory for laser-assisted electron-atom scattering
A new version of the R-matrix Floquet theory for laser-assisted electron-atom
scattering is presented. The theory is non-perturbative and applicable to a
non-relativistic many-electron atom or ion in a homogeneous linearly polarized
field. It is based on the use of channel functions built from field-dressed
target states, which greatly simplifies the general formalism.Comment: 18 pages, LaTeX2e, submitted to J.Phys.
Energy-momentum conservation in pre-metric electrodynamics with magnetic charges
A necessary and sufficient condition for energy-momentum conservation is
proved within a topological, pre-metric approach to classical electrodynamics
including magnetic as well as electric charges. The extended Lorentz force,
consisting of mutual actions by F=(E, B) on the electric current and G=(H, D)
on the magnetic current, can be derived from an energy-momentum "potential" if
and only if the constitutive relation G=G(F) satisfies a certain vanishing
condition. The electric-magnetic reciprocity introduced by Hehl and Obukhov is
seen to define a complex structure on the tensor product of 2-form pairs (F,G)
which is independent of but consistent with the Hodge star operator defined by
any Lorentzian metric. Contrary to a recent claim in the literature, it does
not define a complex structure on the space of 2-forms itself.Comment: 8 pages, 1 fugur
Nutrition Strategies for Triathlon
Contemporary sports nutrition guidelines recommend that each athlete develop a personalised, periodised and practical approach to eating that allows him or her to train hard, recover and adapt optimally, stay free of illness and injury and compete at their best at peak races. Competitive triathletes undertake a heavy training programme to prepare for three different sports while undertaking races varying in duration from 20 min to 10 h. The everyday diet should be adequate in energy availability, provide CHO in varying amounts and timing around workouts according to the benefits of training with low or high CHO availability and spread high-quality protein over the day to maximise the adaptive response to each session. Race nutrition requires a targeted and well-practised plan that maintains fuel and hydration goals over the duration of the specific event, according to the opportunities provided by the race and other challenges, such as a hot environment. Supplements and sports foods can make a small contribution to a sports nutrition plan, when medical supplements are used under supervision to prevent/treat nutrient deficiencies (e.g. iron or vitamin D) or when sports foods provide a convenient source of nutrients when it is impractical to eat whole foods. Finally, a few evidence-based performance supplements may contribute to optimal race performance when used according to best practice protocols to suit the triathlete’s goals and individual responsiveness
- …