687 research outputs found
The finitary coding of two Bernoulli schemes with unequal entropies has finite expectation
AbstractIt is well known that for any two Bernoulli schemes with a finite number of states and unequal entropies, there exists a finitary homomorphism from the scheme with the larger entropy to the one with smaller entropy. We prove that the average number of coordinates in the larger entropy scheme needed to determine one coordinate in the image point is finite
Applications of airborne remote sensing in atmospheric sciences research
This paper explores the potential for airborne remote sensing for atmospheric sciences research. Passive and active techniques from the microwave to visible bands are discussed. It is concluded that technology has progressed sufficiently in several areas that the time is right to develop and operate new remote sensing instruments for use by the community of atmospheric scientists as general purpose tools. Promising candidates include Doppler radar and lidar, infrared short range radiometry, and microwave radiometry
Shapes and singularities in triatic liquid crystal vesicles
Determining the equilibrium configuration and shape of curved two-dimensional
films with (generalized) liquid crystalline (LC) order is a difficult infinite
dimensional problem of direct relevance to the study of generalized
polymersomes, soft matter and the fascinating problem of understanding the
origin and formation of shape (morphogenesis). The symmetry of the free energy
of the LC film being considered and the topology of the surface to be
determined often requires that the equilibrium configuration possesses singular
structures in the form of topological defects such as disclinations for nematic
films. The precise number and type of defect plays a fundamental role in
restricting the space of possible equilibrium shapes. Flexible closed vesicles
with spherical topology and nematic or smectic order, for example, inevitably
possess four elementary strength disclination defects positioned at the
four vertices of a tetrahedral shell. Here we address the problem of
determining the equilibrium shape of flexible vesicles with generalized LC
order. The order parameter in these cases is an element of , for any
positive integer . We will focus on the case , known as triatic LCs.
We construct the appropriate order parameter for triatics and find the
associated free energy. We then describe the structure of the elementary
defects of strength in flat space. Finally, we prove that sufficiently
floppy triatic vesicles with the topology of the 2-sphere equilibrate to
octahedral shells with strength defects at each of the six vertices,
independently of scale.Comment: New results and new sections added, 4 new figures and updated
abstrac
Stalling the State: How Digital Platforms Contribute to and Profit From Delays in the Enforcement and Adoption of Regulations
While it is often claimed that the pace of digital transformation is such that its own, often glacial changes do not allow the state to catch up, we argue that technological companies, with the help of some state actors, have been slowing the state down. To capture this phenomenon, we introduce the notion of stalling strategies. We argue that stalling strategies have allowed digital platforms to create time that they have spent generating revenue and accumulating platform power, which later protected them from state actions. Drawing on a case study of Uber in Poland and a number of shadow cases, we distinguish five stalling strategies: reinventing classifications, dragging out court proceedings, stealing the time of street-level bureaucrats, delaying new regulations, and taking time to (not) comply. By analyzing stalling strategies, this article contributes to discussions about the politics of platform capitalism, the temporality of digitalization, and institutional drift.Introduction Theory: Primitive Accumulation of Platform Power and Stalling Strategies Case Selection and Data Stalling Strategies Beyond the Particular Case: Stalling to Accumulate Platform Power, Stalling to Protect It Conclusion: Platform Power as a Fait Accompli Acknowledgements Notes Reference
Destruction of chain-superconductivity in YBa_2Cu_4O_8 in a weak magnetic field
We report measurements of the temperature dependent components of the
magnetic penetration depth {\lambda}(T) in single crystal samples of
YBa_2Cu_4O_8 using a radio frequency tunnel diode oscillator technique. We
observe a downturn in {\lambda}(T) at low temperatures for currents flowing
along the b and c axes but not along the a axis. The downturn in {\lambda}_b is
suppressed by a small dc field of ~0.25 T. This and the zero field anisotropy
of {\lambda}(T) likely result from proximity induced superconducting on the CuO
chains, however we also discuss the possibility that a significant part of the
anisotropy might originate from the CuO2 planes.Comment: 5 page
A Proposal for Semantic Map Representation and Evaluation
Semantic mapping is the incremental process of “mapping” relevant information of the world (i.e., spatial information, temporal events, agents and actions) to a formal description supported by a reasoning engine. Current research focuses on learning the semantic of environments based on their spatial location, geometry and appearance. Many methods to tackle this problem have been proposed, but the lack of a uniform representation, as well as standard benchmarking suites, prevents their direct comparison. In this paper, we propose a standardization in the representation of semantic maps, by defining an easily extensible formalism to be used on top of metric maps of the environments. Based on this, we describe the procedure to build a dataset (based on real sensor data) for benchmarking semantic mapping techniques, also hypothesizing some possible evaluation metrics. Nevertheless, by providing a tool for the construction of a semantic map ground truth, we aim at the contribution of the scientific community in acquiring data for populating the dataset
Meteoroid sensor material development Final report, 20 Sep. 1968 - 20 Sep. 1969
Dielectrics evaluated for use in micrometeoroid sensor capacitor
A bound on the free energy of tensionless membranes
Using the proof of Willmore's conjecure by Marques and Neves, we conjecture
that the free energy of tensionless fluid membranes of arbitrary genus has an
upper bound. This implies that the average genus of such a membrane, in
equilibrium, is finite, regardless of external constraints.Comment: 4 pages, 1 figur
Electrical characteristics of Pyrrone polymers
Electrical properties and high energy radiation effect on Pyrrone polymer
Evidence for nodal superconductivity in LaFePO
In several iron-arsenide superconductors there is strong evidence for a fully
gapped superconducting state consistent with either a conventional s-wave
symmetry or an unusual state where there the gap changes sign between
the electron and hole Fermi surface sheets. Here we report measurements of the
penetration depth in very clean samples of the related
iron-phosphide superconductor, LaFePO, at temperatures down to 100 mK.
We find that varies almost perfectly linearly with strongly
suggesting the presence of gap nodes in this compound. Taken together with
other data, this suggests the gap function may not be generic to all pnictide
superconductors
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