2,374 research outputs found
Higher-order interference and single-system postulates characterizing quantum theory
We present a new characterization of quantum theory in terms of simple
physical principles that is different from previous ones in two important
respects: first, it only refers to properties of single systems without any
assumptions on the composition of many systems; and second, it is closer to
experiment by having absence of higher-order interference as a postulate, which
is currently the subject of experimental investigation. We give three
postulates -- no higher-order interference, classical decomposability of
states, and strong symmetry -- and prove that the only non-classical
operational probabilistic theories satisfying them are real, complex, and
quaternionic quantum theory, together with 3-level octonionic quantum theory
and ball state spaces of arbitrary dimension. Then we show that adding
observability of energy as a fourth postulate yields complex quantum theory as
the unique solution, relating the emergence of the complex numbers to the
possibility of Hamiltonian dynamics. We also show that there may be interesting
non-quantum theories satisfying only the first two of our postulates, which
would allow for higher-order interference in experiments while still respecting
the contextuality analogue of the local orthogonality principle.Comment: 21 + 6 pages, 1 figure. v4: published version (includes several minor
corrections
Entropy, majorization and thermodynamics in general probabilistic theories
In this note we lay some groundwork for the resource theory of thermodynamics
in general probabilistic theories (GPTs). We consider theories satisfying a
purely convex abstraction of the spectral decomposition of density matrices:
that every state has a decomposition, with unique probabilities, into perfectly
distinguishable pure states. The spectral entropy, and analogues using other
Schur-concave functions, can be defined as the entropy of these probabilities.
We describe additional conditions under which the outcome probabilities of a
fine-grained measurement are majorized by those for a spectral measurement, and
therefore the "spectral entropy" is the measurement entropy (and therefore
concave). These conditions are (1) projectivity, which abstracts aspects of the
Lueders-von Neumann projection postulate in quantum theory, in particular that
every face of the state space is the positive part of the image of a certain
kind of projection operator called a filter; and (2) symmetry of transition
probabilities. The conjunction of these, as shown earlier by Araki, is
equivalent to a strong geometric property of the unnormalized state cone known
as perfection: that there is an inner product according to which every face of
the cone, including the cone itself, is self-dual. Using some assumptions about
the thermodynamic cost of certain processes that are partially motivated by our
postulates, especially projectivity, we extend von Neumann's argument that the
thermodynamic entropy of a quantum system is its spectral entropy to
generalized probabilistic systems satisfying spectrality.Comment: In Proceedings QPL 2015, arXiv:1511.0118
Effects of varying concentrations of certain major and minor nutrients on the interaction between a blue-green alga and a diatom
EEG theta and Mu oscillations during perception of human and robot actions.
The perception of others' actions supports important skills such as communication, intention understanding, and empathy. Are mechanisms of action processing in the human brain specifically tuned to process biological agents? Humanoid robots can perform recognizable actions, but can look and move differently from humans, and as such, can be used in experiments to address such questions. Here, we recorded EEG as participants viewed actions performed by three agents. In the Human condition, the agent had biological appearance and motion. The other two conditions featured a state-of-the-art robot in two different appearances: Android, which had biological appearance but mechanical motion, and Robot, which had mechanical appearance and motion. We explored whether sensorimotor mu (8-13 Hz) and frontal theta (4-8 Hz) activity exhibited selectivity for biological entities, in particular for whether the visual appearance and/or the motion of the observed agent was biological. Sensorimotor mu suppression has been linked to the motor simulation aspect of action processing (and the human mirror neuron system, MNS), and frontal theta to semantic and memory-related aspects. For all three agents, action observation induced significant attenuation in the power of mu oscillations, with no difference between agents. Thus, mu suppression, considered an index of MNS activity, does not appear to be selective for biological agents. Observation of the Robot resulted in greater frontal theta activity compared to the Android and the Human, whereas the latter two did not differ from each other. Frontal theta thus appears to be sensitive to visual appearance, suggesting agents that are not sufficiently biological in appearance may result in greater memory processing demands for the observer. Studies combining robotics and neuroscience such as this one can allow us to explore neural basis of action processing on the one hand, and inform the design of social robots on the other
Infrared and Near-Infrared Spectroscopy of Acetylacetone and Hexafluoroacetylacetone
The infrared and near-infrared spectra of acetylacetone, acetylacetone-d8, and hexafluoroacetylacetone are characterized from experiment and computations at different levels. In the fundamental region, the intramolecular hydrogen bonded OH-stretching transition is clearly observed as a very broad band with substantial structure and located at significantly lower frequency compared to common OH-stretching frequencies. There is no clear evidence for OH-stretching overtone transitions in the near-infrared region, which is dominated by the CH-stretching overtones of the methine and methyl CH bonds. From molecular dynamics (MD) simulations, with a potential energy surface previously validated for tunneling splittings, the infrared spectra are determined and used in assigning the experimentally measured ones. It is found that the simulated spectrum in the region associated with the proton transfer mode is exquisitely sensitive to the height of the barrier for proton transfer. Comparison of the experimental and the MD simulated spectra establishes that the barrier height is around 2.5 kcal/mol, which favorably compares with 3.2 kcal/mol obtained from high-level electronic structure calculations
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Assessing rotation-invariant feature classification for automated wildebeest population counts
Accurate and on-demand animal population counts are the holy grail for wildlife conservation organizations throughout the world because they enable fast and responsive adaptive management policies. While the collection of image data from camera traps, satellites, and manned or unmanned aircraft has advanced significantly, the detection and identification of animals within images remains a major bottleneck since counting is primarily conducted by dedicated enumerators or citizen scientists. Recent developments in the field of computer vision suggest a potential resolution to this issue through the use of rotation-invariant object descriptors combined with machine learning algorithms. Here we implement an algorithm to detect and count wildebeest from aerial images collected in the Serengeti National Park in 2009 as part of the biennial wildebeest count. We find that the per image error rates are greater than, but comparable to, two separate human counts. For the total count, the algorithm is more accurate than both manual counts, suggesting that human counters have a tendency to systematically over or under count images. While the accuracy of the algorithm is not yet at an acceptable level for fully automatic counts, our results show this method is a promising avenue for further research and we highlight specific areas where future research should focus in order to develop fast and accurate enumeration of aerial count data. If combined with a bespoke image collection protocol, this approach may yield a fully automated wildebeest count in the near future
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Reparametrization invariance reexamined
Reparameterization invariance, a symmetry of heavy quark effective theory, appears in different forms in the literature. The most commonly cited forms of the reparameterization transformation are shown to induce the same constraints on operators that do not vanish under the equation of motion to order 1/m2 , and to be related by a redefinition of the heavy quark field. We give a new, very straightforward proof that that the reparameterization invariance constraints apply to all orders in αs under matching to full QCD and renormalization-group running, at least up to and including O(1/m2).Physic
Atomic scale engines: Cars and wheels
We introduce a new approach to build microscopic engines on the atomic scale
that move translationally or rotationally and can perform useful functions such
as pulling of a cargo. Characteristic of these engines is the possibility to
determine dynamically the directionality of the motion. The approach is based
on the transformation of the fed energy to directed motion through a dynamical
competition between the intrinsic lengths of the moving object and the
supporting carrier.Comment: 4 pages, 3 figures (2 in color), Phys. Rev. Lett. (in print
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Identification of proteins binding coding and non-coding human RNAs using protein microarrays
Background: The regulation and function of mammalian RNAs has been increasingly appreciated to operate via RNA-protein interactions. With the recent discovery of thousands of novel human RNA molecules by high-throughput RNA sequencing, efficient methods to uncover RNA-protein interactions are urgently required. Existing methods to study proteins associated with a given RNA are laborious and require substantial amounts of cell-derived starting material. To overcome these limitations, we have developed a rapid and large-scale approach to characterize binding of in vitro transcribed labeled RNA to ~9,400 human recombinant proteins spotted on protein microarrays. Results: We have optimized methodology to probe human protein microarrays with full-length RNA molecules and have identified 137 RNA-protein interactions specific for 10 coding and non-coding RNAs. Those proteins showed strong enrichment for common human RNA binding domains such as RRM, RBD, as well as K homology and CCCH type zinc finger motifs. Previously unknown RNA-protein interactions were discovered using this technique, and these interactions were biochemically verified between TP53 mRNA and Staufen1 protein as well as between HRAS mRNA and CNBP protein. Functional characterization of the interaction between Staufen 1 protein and TP53 mRNA revealed a novel role for Staufen 1 in preserving TP53 RNA stability. Conclusions: Our approach demonstrates a scalable methodology, allowing rapid and efficient identification of novel human RNA-protein interactions using RNA hybridization to human protein microarrays. Biochemical validation of newly identified interactions between TP53-Stau1 and HRAS-CNBP using reciprocal pull-down experiments, both in vitro and in vivo, demonstrates the utility of this approach to study uncharacterized RNA-protein interactions.Stem Cell and Regenerative Biolog
Business Process Modeling for Successful Implementation of Interorganizational Systems
Studies show that the physical implementation of an interorganizational business process or system can be a major source of operational problems and reduced business benefits. Better process modeling has been advocated as a solution. Although powerful modeling tools exist, current practice often gives short-shrift to documenting the physical implementation details that can create or exacerbate such problems. In this paper we describe the modeling approach we devised for the interorganizational business processes and systems we observe in our ongoing fieldwork. Our approach involves using allowable extensions to a popular modeling notation (BPMN), although other modeling tools would work equally well. We illustrate the benefit of our approach in the case of the Internet Payment Platform, a pilot project of the United States Department of the Treasury
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