7,143 research outputs found
Stable gauged maps
We give an introduction to moduli stacks of gauged maps satisfying a
stability conditition introduced by Mundet and Schmitt, and the associated
integrals giving rise to gauged Gromov-Witten invariants. We survey various
applications to cohomological and K-theoretic Gromov-Witten invariants.Comment: Survey for the 2015 AMS Summer Institute on Algebraic Geometry. Split
off from the more technical paper "Properness for scaled gauged maps"
[arXiv:1606.01383]. There is still substantial overlap between the two
papers. This version has minor correction
Experiment K-6-06. Morphometric and EM analyses of tibial epiphyseal plates from Cosmos 1887 rats
Light and electron microscopy studies were carried out on decalcified tibial epiphyseal plates of rats flown aboard Cosmos 1887 (12.5d flight plus 53.5h recovery). Analysis of variance showed that the proliferative zone of flight animals was significantly higher than that of synchronous controls, while the hypertrophic/calcification zone was significantly reduced. Flight animals had more cells than synchronous controls in the proliferative zone, and less in the hypertrophic/calcification region. The total number of cells, however, was significantly higher in flight animals. No differences were found for perimeter or shape factor of growth plates, but area was significantly lower in flight animals in comparison to synchronous controls. Collagen fibrils in flight animals were shorter and wider than in synchronous controls. The time required for a cell to cycle through the growth plate is 2 to 3 days, so most of the cells and matrix present were formed after the animals had returned to 1 g, and probably represent stages of recovery from microgravity exposure, which in itself is an interesting question
TECTONIC CONTROLS ON LOWER DEVONIAN SANDSTONE DISTRIBUTION, ALABAMA
The Devonian Frog Mountain Formation thickens abruptly eastward across the Eastern Coosa thrust fault from \u3c12 m on the west to\u3e70 m on the east. The thin Frog Mountain on the west unconformably overlies the Cambrian-Ordovician Knox Group. The thin Frog Mountain (mostly shale) is overlain by the Mississippian Maury Shale (~1 m thick) and Fort Payne Chert (~50 m thick). The thick Frog Mountain on the east rests on the Middle Ordovician Athens Shale, a black shale \u3e150 m thick. The Athens overlies the Knox Group. The thick Frog Mountain is nearly all sandstone and is overlain by Fort Payne Chert which is only ~1 m thick
In the Eastern Coosa hanging wall, an upper-level out-of-the-syncline thrust fault with thick Frog Mountain in the hanging wall cuts more than 290 m stratigraphically down section from Athens to lower Knox in the footwall. The upper-level Frog Mountain thrust sheet crosses over the Eastern Coosa fault, and truncates folds in the Eastern Coosa footwall, moving ~2 km.
The thick Frog Mountain Formation associated with the Eastern Coosa thrust sheet has been transported ~100 km cratonward. The Frog Mountain Formation was deposited over a low topographic high, which was in the location of the Blountian peripheral foreland bulge
Tunable entanglement distillation of spatially correlated down-converted photons
We report on a new technique for entanglement distillation of the bipartite
continuous variable state of spatially correlated photons generated in the
spontaneous parametric down-conversion process (SPDC), where tunable
non-Gaussian operations are implemented and the post-processed entanglement is
certified in real-time using a single-photon sensitive electron multiplying CCD
(EMCCD) camera. The local operations are performed using non-Gaussian filters
modulated into a programmable spatial light modulator and, by using the EMCCD
camera for actively recording the probability distributions of the
twin-photons, one has fine control of the Schmidt number of the distilled
state. We show that even simple non-Gaussian filters can be finely tuned to a
~67% net gain of the initial entanglement generated in the SPDC process.Comment: 12 pages, 6 figure
Integrating Multiple Professional Learning Frameworks to Assist Teachers’ Reflective Inquiry
This study sought to determine how three teachers experienced learning when engaged in ongoing reflective inquiry regarding their teaching beliefs, teaching behaviors, and the comparison of those beliefs and behaviors. Three case studies describe teachers writing educational platforms, comparing their platforms to their classroom behaviors, and engaging in efforts to align their teaching with their beliefs. Five professional learning frameworks supported the teachers in their reflective inquiry: action research, a critical friend, reflective writing, a collegial support group and clinical supervision. The critical friend met teachers in individual meetings to discuss the inquiry process, facilitated their collegial support group meetings and conducted non-evaluative clinical supervision cycles for each teacher. Data collected for the study included transcribed audio recordings of the critical friend’s individual meetings with teachers, post-observation conferences, and collegial support group meetings. Additional data included the teachers’ educational platforms, action research game plans, classroom observation data, and reflective journals. Data for each teacher were analyzed and triangulated to develop individual cases, and a cross-case comparison identified group themes. Although they progressed through the inquiry process in different ways and at different tempos, all three teachers experienced cognitive dissonance that led to a commitment to align their beliefs and behaviors
Ion condensation on charged patterned surfaces
We study ion condensation onto a patterned surface of alternating charges.
The competition between self-energy and ion-surface interactions leads to the
formation of ionic crystalline structures at low temperatures. We consider
different arrangements of underlying ionic crystals, including single ion
adsorption, as well as the formation of dipoles at the interface between
charged domains. Molecular dynamic simulation illustrates existence of single
and mixed phases. Our results contribute to understanding pattern recognition,
and molecular separation and synthesis near patterned surfaces.Comment: 3 figure
Teacher Leaders of Collaborative Action Research: Challenges and Rewards
This study describes four successful collaborative action research (CAR) projects through the lens of teacher leaders who facilitated the CAR. For each CAR project described, the study reports on the relationship of the teacher leader with team members, various phases of CAR, the challenges of implementation and how those challenges were addressed, and results of the action research. Additionally, the study identifies several common characteristics of the widely varied CAR projects. All of the teacher leaders relied on positive relationships with teachers to enlist them into the CAR and keep it going. The CAR teams gathered a variety of data throughout their action research, to assess needs, monitor progress, and determine outcomes. The four CAR projects all included embedded professional development and opportunities for teacher reflection. The teacher leaders gathered feedback from the participating teachers throughout the implementation of the CAR. All of the CAR projects encountered barriers that caused the teachers stress and threatened to curtail the projects; however the teacher leaders were able to navigate those barriers by displaying flexibility and modifying the CAR. All of the CAR projects yielded positive outcomes, and in each case the participants agreed to continue the CAR the following school year
Dual regimes of ion migration in high repetition rate femtosecond laser inscribed waveguides
Ion migration in high repetition rate femtosecond laser inscribed waveguides
is currently being reported in different optical glasses. For the first time we
discuss and experimentally demonstrate the presence of two regimes of ion
migration found in laser written waveguides. Regime-I, corresponds to the
initial waveguide formation mainly via light element migration (in our case
atomic weight < 31u), whereas regime-II majorly corresponds to the movement of
heavy elements. This behavior brings attention to a problem which has never
been analyzed before and that affects laser written active waveguides in which
active ions migrate changing their local spectroscopic properties. The
migration of active ions may in fact detune the pre-designed optimal values of
active photonic devices. This paper experimentally evidences this problem and
provides solutions to avert it.Comment: 4 pages, 5 figure
Design and implementation of a compliant robot with force feedback and strategy planning software
Force-feedback robotics techniques are being developed for automated precision assembly and servicing of NASA space flight equipment. Design and implementation of a prototype robot which provides compliance and monitors forces is in progress. Computer software to specify assembly steps and makes force feedback adjustments during assembly are coded and tested for three generically different precision mating problems. A model program demonstrates that a suitably autonomous robot can plan its own strategy
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