188 research outputs found
Relativistic BB84, relativistic errors, and how to correct them
The Bennett-Brassard cryptographic scheme (BB84) needs two bases, at least
one of them linearly polarized. The problem is that linear polarization
formulated in terms of helicities is not a relativistically covariant notion:
State which is linearly polarized in one reference frame becomes depolarized in
another one. We show that a relativistically moving receiver of information
should define linear polarization with respect to projection of
Pauli-Lubanski's vector in a principal null direction of the Lorentz
transformation which defines the motion, and not with respect to the helicity
basis. Such qubits do not depolarize.Comment: revtex
The staggered domain wall fermion method
A different lattice fermion method is introduced. Staggered domain wall
fermions are defined in 2n+1 dimensions and describe 2^n flavors of light
lattice fermions with exact U(1) x U(1) chiral symmetry in 2n dimensions. As
the size of the extra dimension becomes large, 2^n chiral flavors with the same
chiral charge are expected to be localized on each boundary and the full
SU(2^n) x SU(2^n) flavor chiral symmetry is expected to be recovered. SDWF give
a different perspective into the inherent flavor mixing of lattice fermions and
by design present an advantage for numerical simulations of lattice QCD
thermodynamics. The chiral and topological index properties of the SDWF Dirac
operator are investigated. And, there is a surprise ending...Comment: revtex4, 7 figures, minor revisions, 2 references adde
Homotopy on spatial graphs and generalized Sato-Levine invariants
Edge-homotopy and vertex-homotopy are equivalence relations on spatial graphs
which are generalizations of Milnor's link-homotopy. Fleming and the author
introduced some edge (resp. vertex)-homotopy invariants of spatial graphs by
applying the Sato-Levine invariant for the constituent 2-component
algebraically split links. In this paper, we construct some new edge (resp.
vertex)-homotopy invariants of spatial graphs without any restriction of
linking numbers of the constituent 2-component links by applying the
generalized Sato-Levine invariant.Comment: 16 pages, 13 figure
Diffraction Symmetry in Crystalline, Close-Packed C60
We have grown crystals of the carbon structure C60 by sublimation. In contrast to solution-grown crystals, the sublimed crystals have long range order with no evidence of solvent inclusions. Sublimed C60 forms three dimensional, faceted crystals with a close-packed, face-centered cubic unit cell. We have refined a crystal structure using the "soccer ball" model of the C60 molecule. The results indicate that the C60 molecule has the expected spherical shape, however the data are not sufficiently accurate to unambiguously determine atomic positions
Exploring the Post-translational Enzymology of PaaA by mRNA Display
PaaA is a RiPP enzyme that catalyzes the transformation of two glutamic acid residues within a substrate peptide into the bicyclic core of Pantocin A. Here, for the first time, we use mRNA display techniques to understand RiPP enzyme-substrate interactions to illuminate PaaA substrate recognition. Additionally, our data revealed insights into the enzymatic timing of glutamic acid modification. The technique developed is quite sensitive and a significant advancement over current RiPP studies and opens the door to enzyme modified mRNA display libraries for natural product-like inhibitor pans
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Growth and properties of W-B-N diffusion barriers deposited by chemical vapor deposition
The authors have used chemical vapor deposition to grow ternary tungsten-based diffusion barriers to determine if they exhibit properties similar to those of sputter-deposited ternaries. A range of different W-B-N compositions in a band of compositions roughly between 20 and 40% W were produced. The deposition temperature was low, 350 C, and the precursors used are well accepted by the industry. Deposition rates are high for a diffusion barrier application. Resistivities range from 200 to 20,000 {micro}{Omega}-cm, the films with the best barrier properties having {approximately}1,000 {micro}{Omega}-cm resistivities. Adhesion to oxides is sufficient to allow these films to be used as the adhesion layer in a tungsten chemical mechanical polishing plug application. The films are x-ray amorphous as-deposited and have crystallization temperatures of up to 900 C. Barrier performance against Cu has been tested using diode test structures. A composition of W{sub .23}B{sub .49}N{sub .28} was able to prevent diode failure up to a 700 C, 30 minute anneal. These materials, deposited by CVD, display properties similar to those deposited by physical deposition techniques
Propaganda in an Age of Algorithmic Personalization: Expanding Literacy Research and Practice
In this commentary, the author considers the rise of algorithmic personalization and the power of propaganda as they shift the dynamic landscape of 21st‐century literacy research and practice. Algorithmic personalization uses data from the behaviors, beliefs, interests, and emotions of the target audience to provide filtered digital content, targeted advertising, and differential product pricing to online users. As persuasive genres, advertising and propaganda may demand different types of reading practices than texts whose purpose is primarily informational or argumentative. Understanding the propaganda function of algorithmic personalization may lead to a deeper consideration of texts that activate emotion and tap into audience values for aesthetic, commercial, and political purposes. Increased attention to algorithmic personalization, propaganda, and persuasion in the context of K–12 literacy education may also help people cope with sponsored content, bots, and other forms of propaganda and persuasion that now circulate online
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