9,285 research outputs found
Renormalization and blow up for charge one equivariant critical wave maps
We prove the existence of equivariant finite time blow up solutions for the
wave map problem from 2+1 dimensions into the 2-sphere. These solutions are the
sum of a dynamically rescaled ground-state harmonic map plus a radiation term.
The local energy of the latter tends to zero as time approaches blow up time.
This is accomplished by first "renormalizing" the rescaled ground state
harmonic map profile by solving an elliptic equation, followed by a
perturbative analysis
The Critical Exponent is Computable for Automatic Sequences
The critical exponent of an infinite word is defined to be the supremum of
the exponent of each of its factors. For k-automatic sequences, we show that
this critical exponent is always either a rational number or infinite, and its
value is computable. Our results also apply to variants of the critical
exponent, such as the initial critical exponent of Berthe, Holton, and Zamboni
and the Diophantine exponent of Adamczewski and Bugeaud. Our work generalizes
or recovers previous results of Krieger and others, and is applicable to other
situations; e.g., the computation of the optimal recurrence constant for a
linearly recurrent k-automatic sequence.Comment: In Proceedings WORDS 2011, arXiv:1108.341
Threonine dehydratase deficiency: A probable cause of non‐ketotic hyperglycinaemia
A patient with classical symptoms of non‐ketotic hyperglycinaemia (NKH) is presented. Threonine dehydratase was undetectable in a liver autopsy specimen, which was obtained within 1 h of death and immediately frozen at −70 °C. Activities of four marker enzymes were normal. This represents the first documentation of an inborn error of threonine metabolism and a new explanation of NKH.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147124/1/jimd0053.pd
Using the art practice of play to communicate legged robotics research concepts
The art practice of play uses spontaneity and surprise to communicate meaningful content and inspire critical thinking (1-3). We describe three engineering education outreach efforts that use play to communicate legged robotics research concepts. In the first workshop, Penn engineering students were motivated to learn how to program a legged robot using the narrative of a “dance competition,” with the winning dances to be showcased at the Philadelphia Science Festival. In the second workshop, Philadelphia School District high school students used a poseably programmable legged robot to tell a story by performing a series of behaviors in a set of their own design and documenting the story as a video artwork. Here, there were two narratives: One created by the workshop directors, communicating concepts about complex multi-legged behaviors and gaits, and the other created by the students using the robots to express their ideas. In the final workshop, middle school students created locomoting robots using motors, post-consumer materials, and basic art supplies. The concepts of energy and physical programming were demonstrated using working Trashbots and practiced during an introductory exercise making a vibrating motor from a spinning one. Participants then created a robot of their own design using iterative experimentation. We conclude from these three workshops that play can be used as a vehicle for scientific communication. (1) David Getsy, ed. From diversion to subversion: Games, play, and twentieth-century art, Vol. 16 (Penn State Press, 2011). (2) Nato Thompson and Gregory Scholette, eds. The interventionists: Users\u27 manual for the creative disruption of everyday life (MIT Press, 2004). (3) Diedra Krieger, ‘Plastic Fantastic,’ Gyre Exhibition, Anchorage Museum, Alaska, 2014.
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Nondispersive solutions to the L2-critical half-wave equation
We consider the focusing -critical half-wave equation in one space
dimension where denotes the
first-order fractional derivative. Standard arguments show that there is a
critical threshold such that all solutions with extend globally in time, while solutions with may develop singularities in finite time.
In this paper, we first prove the existence of a family of traveling waves
with subcritical arbitrarily small mass. We then give a second example of
nondispersive dynamics and show the existence of finite-time blowup solutions
with minimal mass . More precisely, we construct a
family of minimal mass blowup solutions that are parametrized by the energy
and the linear momentum . In particular, our main result
(and its proof) can be seen as a model scenario of minimal mass blowup for
-critical nonlinear PDE with nonlocal dispersion.Comment: 51 page
1,8‐Bis(diphenylamino)‐ and 1,8‐Bis(methylphenylamino)naphthalene: Molecular Structure and Dynamic Behavior
The title compounds 2 and 3 have been synthesized from 1,8‐diaminonaphthalene. The molecular structure of 2 has been determined by X‐ray structure analysis and is discussed with regard to the arrangement of the peri‐diphenylamino substituents in the crystalline state and the steric strain in the molecule. NMR studies of 3 reveal two conformational processes. Their nature is discussed and barriers are reported
Accessing Law: An Empirical Study Exploring the Influence of Legal Research Medium
The legal profession is presently engaged in an uncontrolled experiment. Attorneys now locate and access legal authorities primarily through electronic means. Although this shift to an electronic research medium radically changes how attorneys discover and encounter law, little empirical work investigates impacts from the shift to an electronic medium.
This Article presents the results of one of the most robust empirical studies conducted to date comparing research processes using print and electronic sources. While the study presented in this Article was modest in scope, the extent and type of the differences that it reveals are notable. Some of the observed differences between print and electronic research processes confirm predictions offered, but never before confirmed, about how the research medium changes the research process. This Article strongly supports calls for the legal profession and legal academy to be more attentive to the implications of the shift to electronic research
Highly conductive molecular junctions based on direct binding of benzene to platinum electrodes
Highly conductive molecular junctions were formed by direct binding of
benzene molecules between two Pt electrodes. Measurements of conductance,
isotopic shift in inelastic spectroscopy and shot noise compared with
calculations provide indications for a stable molecular junction where the
benzene molecule is preserved intact and bonded to the Pt leads via carbon
atoms. The junction has a conductance comparable to that for metallic atomic
junctions (around 0.1-1 Go), where the conductance and the number of
transmission channels are controlled by the molecule's orientation at different
inter-electrode distances.Comment: 4 pages, 4 figure
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