1,895 research outputs found
Anyone Can Become a Troll: Causes of Trolling Behavior in Online Discussions
In online communities, antisocial behavior such as trolling disrupts
constructive discussion. While prior work suggests that trolling behavior is
confined to a vocal and antisocial minority, we demonstrate that ordinary
people can engage in such behavior as well. We propose two primary trigger
mechanisms: the individual's mood, and the surrounding context of a discussion
(e.g., exposure to prior trolling behavior). Through an experiment simulating
an online discussion, we find that both negative mood and seeing troll posts by
others significantly increases the probability of a user trolling, and together
double this probability. To support and extend these results, we study how
these same mechanisms play out in the wild via a data-driven, longitudinal
analysis of a large online news discussion community. This analysis reveals
temporal mood effects, and explores long range patterns of repeated exposure to
trolling. A predictive model of trolling behavior shows that mood and
discussion context together can explain trolling behavior better than an
individual's history of trolling. These results combine to suggest that
ordinary people can, under the right circumstances, behave like trolls.Comment: Best Paper Award at CSCW 201
A Summary of Archaeological Excavations from 1983-1986 at the Green Family Print Shop, 18AP29, Annapolis, Maryland
18AP29, the Green Family Printshop, also known as the Jonas Green site, was excavated from 1983 to 1986 by Archaeology in Annapolis and Historic Annapolis Foundation. The site is not only the home of a significant figure in colonial Maryland but is also the location of one of the first colonial printing operations in Maryland. This site represents an important pre-industrial business in Annapolis. While this domestic site is complicated and rich, one of the most fascinating aspect of 18AP29 is the discovery of a large quantity of printers' type. Extensive analysis of the printers' type and documentary research on one of the print shop's products, the colonial newspaper, the Maryland Gazette, provides insights into the print culture which was developing during the 18th and 19th centuries. This report summarizes the stratigraphic analysis, minimum vessel counts, and faunal
analysis. It provides some description of the printers' type
Energy representation for out-of-equilibrium Brownian-like systems: steady states and fluctuation relations
Stochastic dynamics in the energy representation is employed as a method to
study non-equilibrium Brownian-like systems. It is shown that the equation of
motion for the energy of such systems can be taken in the form of the Langevin
equation with multiplicative noise. Properties of the steady states are
examined by solving the Fokker-Planck equation for the energy distribution
functions. The generalized integral fluctuation theorem is deduced for the
systems characterized by the shifted probability flux operator. There are a
number of entropy and fluctuation relations such as the Hatano-Sasa identity
and the Jarzynski's equality that follow from this theorem.Comment: revtex4-1, 18 pages, extended discussion, references adde
Singlet-triplet energy gaps modulation of Diindeno [1,2-b: 1’2’-g] anthracene molecular family
Nowadays there is a large interest in organic materials based on diradical polycyclic aromatic hydrocarbons (PAHs) due to their unique properties, such as narrow frontier-orbital energy gaps, strong absorption in the visible spectrum, etc. However, the inherent diradical nature make these compounds with limited chemical stability giving rise to rapid decomposition under ambient conditions thus reducing their practical use. In recent years PAH diradicals that exhibit remarkable stability have been prepared thanks to the description of efficient synthetic routes to access them. One of these remarkable cases is the diindeno [1,2-b: 1’2’-g] anthracene, named as DIAn. DIAn is constituted by antiaromatic segments together with a central pro-aromatic structure.
One of the important observable properties of diradicals is the singlet-triplet energy gap, ∆EST, which is intimately connected with the diradical character. The possibility of access to the molecular structure of diradicals is very valuable since properties such as the bond-order or the bond-length alternation of the mentioned moieties reveal the diradical content. Electronic and vibrational spectroscopies are alternative sources of structural information that often compensate the absence of solid-state structures.
In this communication, we expand the studies of DIAn by introducing another aspect of the modulation of the ∆EST which concerns with: i) the extension of the terminal benzenes with another fused benzene (i.e., forming terminal napthalenes) and ii) with the isomerization resulting from the fusion topology of these terminal benzenes. We will present a UV-Vis-NIR and Raman spectroscopic study of the new compounds. The variation of the spectra within molecular family will be discussed in connection with the variation of ∆EST and with the diradical character of the new molecules.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Identification of Rhoptry Trafficking Determinants and Evidence for a Novel Sorting Mechanism in the Malaria Parasite Plasmodium falciparum
The rhoptry of the malaria parasite Plasmodium falciparum is an unusual secretory organelle that is thought to be related to secretory lysosomes in higher eukaryotes. Rhoptries contain an extensive collection of proteins that participate in host cell invasion and in the formation of the parasitophorous vacuole, but little is known about sorting signals required for rhoptry protein targeting. Using green fluorescent protein chimeras and in vitro pull-down assays, we performed an analysis of the signals required for trafficking of the rhoptry protein RAP1. We provide evidence that RAP1 is escorted to the rhoptry via an interaction with the glycosylphosphatidyl inositol-anchored rhoptry protein RAMA. Once within the rhoptry, RAP1 contains distinct signals for localisation within a sub-compartment of the organelle and subsequent transfer to the parasitophorous vacuole after invasion. This is the first detailed description of rhoptry trafficking signals in Plasmodium
No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations
The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere, which-given methane's lifetime of several centuries-predicts an even, well mixed distribution of methane. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally
Martian dust storm impact on atmospheric H<sub>2</sub>O and D/H observed by ExoMars Trace Gas Orbiter
Global dust storms on Mars are rare but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere, primarily owing to solar heating of the dust. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes, as well as a decrease in the water column at low latitudes. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere
Suppressing quantum errors by scaling a surface code logical qubit
Practical quantum computing will require error rates that are well below what
is achievable with physical qubits. Quantum error correction offers a path to
algorithmically-relevant error rates by encoding logical qubits within many
physical qubits, where increasing the number of physical qubits enhances
protection against physical errors. However, introducing more qubits also
increases the number of error sources, so the density of errors must be
sufficiently low in order for logical performance to improve with increasing
code size. Here, we report the measurement of logical qubit performance scaling
across multiple code sizes, and demonstrate that our system of superconducting
qubits has sufficient performance to overcome the additional errors from
increasing qubit number. We find our distance-5 surface code logical qubit
modestly outperforms an ensemble of distance-3 logical qubits on average, both
in terms of logical error probability over 25 cycles and logical error per
cycle ( compared to ). To investigate
damaging, low-probability error sources, we run a distance-25 repetition code
and observe a logical error per round floor set by a single
high-energy event ( when excluding this event). We are able
to accurately model our experiment, and from this model we can extract error
budgets that highlight the biggest challenges for future systems. These results
mark the first experimental demonstration where quantum error correction begins
to improve performance with increasing qubit number, illuminating the path to
reaching the logical error rates required for computation.Comment: Main text: 6 pages, 4 figures. v2: Update author list, references,
Fig. S12, Table I
Non-Abelian braiding of graph vertices in a superconducting processor
Indistinguishability of particles is a fundamental principle of quantum
mechanics. For all elementary and quasiparticles observed to date - including
fermions, bosons, and Abelian anyons - this principle guarantees that the
braiding of identical particles leaves the system unchanged. However, in two
spatial dimensions, an intriguing possibility exists: braiding of non-Abelian
anyons causes rotations in a space of topologically degenerate wavefunctions.
Hence, it can change the observables of the system without violating the
principle of indistinguishability. Despite the well developed mathematical
description of non-Abelian anyons and numerous theoretical proposals, the
experimental observation of their exchange statistics has remained elusive for
decades. Controllable many-body quantum states generated on quantum processors
offer another path for exploring these fundamental phenomena. While efforts on
conventional solid-state platforms typically involve Hamiltonian dynamics of
quasi-particles, superconducting quantum processors allow for directly
manipulating the many-body wavefunction via unitary gates. Building on
predictions that stabilizer codes can host projective non-Abelian Ising anyons,
we implement a generalized stabilizer code and unitary protocol to create and
braid them. This allows us to experimentally verify the fusion rules of the
anyons and braid them to realize their statistics. We then study the prospect
of employing the anyons for quantum computation and utilize braiding to create
an entangled state of anyons encoding three logical qubits. Our work provides
new insights about non-Abelian braiding and - through the future inclusion of
error correction to achieve topological protection - could open a path toward
fault-tolerant quantum computing
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