56,962 research outputs found
Uniqueness and Logical Disagreement
This paper discusses the uniqueness thesis, a core thesis in the epistemology of disagreement. After presenting uniqueness and clarifying relevant terms, a novel counterexample to the thesis will be introduced. This counterexample involves logical disagreement. Several objections to the counterexample are then considered, and it is argued that the best responses to the counterexample all undermine the initial motivation for uniqueness
An informal analysis of flight control tasks
Issues important in rotorcraft flight control are discussed. A perceptual description is suggested of what is believed to be the major issues in flight control. When the task is considered of a pilot controlling a helicopter in flight, the task is decomposed in several subtasks. These subtasks include: (1) the control of altitude, (2) the control of speed, (3) the control of heading, (4) the control of orientation, (5) the control of flight over obstacles, and (6) the control of flight to specified positions in the world. The first four subtasks can be considered to be primary control tasks as they are not dependent on any other subtasks. However, the latter two subtasks can be considered hierarchical tasks as they are dependent on other subtasks. For example, the task of flight control over obstacles can be decomposed as a task requiring the control of speed, altitude, and heading. Thus, incorrect control of altitude should result in poor control of flight over an obstacle
Experimentally feasible quantum erasure-correcting code for continuous variables
We devise a scheme that protects quantum coherent states of light from
probabilistic losses, thus achieving the first continuous-variable quantum
erasure-correcting code. If the occurrence of erasures can be probed, then the
decoder enables, in principle, a perfect recovery of the original light states.
Otherwise, if supplemented with postselection based on homodyne detection, this
code can be turned into an efficient erasure-filtration scheme. The
experimental feasibility of the proposed protocol is carefully addressed
Extinction of quasiparticle interference in underdoped cuprates with coexisting order
Recent scanning tunnelling spectroscopy measurements [Y. Koksaka et al.,
Nature 454, 1072 (2008)] have shown that dispersing quasiparticle interference
peaks in Fourier transformed conductance maps disappear as the bias voltage
exceeds a certain threshold corresponding to the coincidence of the contour of
constant quasiparticle energy with the antiferromagnetic zone boundary. Here we
argue that this is caused by quasistatic short-range coexisting order present
in the d-wave superconducting phase, and that the most likely origin of this
order is disorder-induced incommensurate antiferromagnetism. We show explicitly
how the peaks are extinguished in the related situation with coexisting
long-range antiferromagnetic order, and discuss the connection with the
realistic disordered case. Since it is the localized quasiparticle interference
peaks rather than the underlying antinodal states themselves which are
destroyed at a critical bias, our proposal resolves a conflict between scanning
tunneling spectroscopy and photoemission regarding the nature of these states.Comment: 10 pages, 9 figure
Increments of Uncorrelated Time Series Can Be Predicted With a Universal 75% Probability of Success
We present a simple and general result that the sign of the variations or
increments of uncorrelated times series are predictable with a remarkably high
success probability of 75% for symmetric sign distributions. The origin of this
paradoxical result is explained in details. We also present some tests on
synthetic, financial and global temperature time series.Comment: 8 pages, 3 figure
DNA extraction from museum specimens of parasitic Hymenoptera.
At the same time that molecular researchers are improving techniques to extract DNA from museum specimens, this increased demand for access to museum specimens has created tension between the need to preserve specimens for maintaining collections and morphological research and the desire to conduct molecular analyses. To address these concerns, we examined the suitability of non-invasive DNA extraction techniques on three species of parasitic Hymenoptera (Braconidae), and test the effects of body size (parasitoid species), age (time since collection), and DNA concentration from each extract on the probability of amplifying meaningful fragments of two commonly used genetic loci. We found that age was a significant factor for determining the probability of success for sequencing both 28S and COI fragments. While the size of the braconid parasitoids significantly affected the total amount of extracted DNA, neither size nor DNA concentration were significant factors for the amplification of either gene region. We also tested several primer combinations of various lengths, but were unable to amplify fragments longer than ~150 base pairs. These short fragments of 28S and COI were however sufficient for species identification, and for the discovery of within species genetic variation
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