4,114 research outputs found
Following glaziouâs footsteps: rediscovery and updated description of three species of behuria cham. (melastomataceae) from the Atlantic forest (Brazil)
This study was carried out in the state of Rio de Janeiro and led to the rediscovery of three endemic and threatened species of Behuria (Melastomataceae). The type specimens for these species were collected by the French botanist A.F.M. Glaziou. Behuria corymbosa and Behuria glazioviana were collected for the last time 127 years ago by him, in 1889. Behuria mourae was collected twice after the type; the last collection dates from about 72 years ago. In order to find the exact localities where Glaziou collected these three species we studied the labels of the type specimens, Glaziouâs notebooks and letters, looking for tracks that would lead us to places that he visited. We also consulted documents from a local library and gathered information from local people. Here we present updated descriptions, comments, photos and conservation assessments for each species.3023229240CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQCOORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPES306852/2013-6Sem informaçã
Behuria lumiarensis (Melastomataceae), a new species on a mountaintop of the brazilian Atlantic Forest
We describe and illustrate Behuria lumiarensis, a new species from the state of Rio de Janeiro, Brazil. It has been collected only once in montane vegetation in the Municipality of Nova Friburgo. The new species can be recognized by the combination of leaf blades with adaxial surface covered with sessile glands and abaxial surface moderately covered with stalked glands only on the veins, hypanthium sparsely covered with stalked glands, a large calyx tube with narrow sepals that are not apiculate in the apex, small petals, and glabrous ovary apex.3052111117CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQCOORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPES457510/2014-5; 306852/2013-6Sem informaçã
Error Prevention Scheme with Four Particles
It is shown that a simplified version of the error correction code recently
suggested by Shor exhibits manifestation of the quantum Zeno effect. Thus,
under certain conditions, protection of an unknown quantum state is achieved.
Error prevention procedures based on four-particle and two-particle encoding
are proposed and it is argued that they have feasible practical
implementations.Comment: 4 pages, RevTeX, references updated and improved protocol adde
A Comparison of Blocking Methods for Record Linkage
Record linkage seeks to merge databases and to remove duplicates when unique
identifiers are not available. Most approaches use blocking techniques to
reduce the computational complexity associated with record linkage. We review
traditional blocking techniques, which typically partition the records
according to a set of field attributes, and consider two variants of a method
known as locality sensitive hashing, sometimes referred to as "private
blocking." We compare these approaches in terms of their recall, reduction
ratio, and computational complexity. We evaluate these methods using different
synthetic datafiles and conclude with a discussion of privacy-related issues.Comment: 22 pages, 2 tables, 7 figure
Pump It Out! The Effect of Transmitter Activity on Content Propagation in Social Media
People share billions of pieces of content such as news, videos, and photos through social media every day. Marketers are interested in the extent to which such content propagates and, importantly, which factors make widespread propagation more likely. Extant research considers various factors, such as content attributes (e.g., newness), source traits (e.g., expertise), and network structure (e.g., connectivity). This research builds on prior work by introducing a novel behavior-focused transmitter characteristic that is positively associated with content propagation in social media: activity, or how frequently a person transmits content. Evidence for this effect comes from five studies and different paradigms. First, two studies using data from large social media platforms (Twitter and LiveJournal) show that content posted by higher-activity transmittersâwhom we refer to as âsocial pumpsââpropagates more than content posted by lower-activity transmitters. Second, three experiments explore the mechanism driving this effect, showing that social media users receiving content from a social pump are more likely to retransmit it (a necessary behavior for achieving aggregate-level propagation) because they infer that content from a social pump is more likely to be current, and therefore more attractive as something to pass along through retransmission
Leaf segmentation and tracking using probabilistic parametric active contours
Active contours or snakes are widely used for segmentation and tracking. These techniques require the minimization of an energy function, which is generally a linear combination of a data fit term and a regularization term. This energy function can be adjusted to exploit the intrinsic object and image features. This can be done by changing the weighting parameters of the data fit and regularization term. There is, however, no rule to set these parameters optimally for a given application. This results in trial and error parameter estimation. In this paper, we propose a new active contour framework defined using probability theory. With this new technique there is no need for ad hoc parameter setting, since it uses probability distributions, which can be learned from a given training dataset
Modelling diffusion of innovations in a social network
A new simple model of diffusion of innovations in a social network with
upgrading costs is introduced. Agents are characterized by a single real
variable, their technological level. According to local information agents
decide whether to upgrade their level or not balancing their possible benefit
with the upgrading cost. A critical point where technological avalanches
display a power-law behavior is also found. This critical point is
characterized by a macroscopic observable that turns out to optimize
technological growth in the stationary state. Analytical results supporting our
findings are found for the globally coupled case.Comment: 4 pages, 5 figures. Final version accepted in PR
Growth and characterization of nanocrystalline SrTiOx films: Room temperature deposition using RF sputtering system in a pure argon environment
We report a comprehensive description of the structure, optical and electrical properties of asdeposited and annealed SrTiOx (STO) thin films. Nanocrystalline STO films were deposited on p-type Si (1 0 0) and UV-grade fused silica substrates by RF magnetron sputtering at room temperature in a pure argon environment. Well adhered and transparent films with very smooth surfaces were obtained. As-deposited films showed 70% transparency in the visible spectrum, transparency increased to 77% after annealing at 700 °C. The direct and indirect optical band gaps were found to be 2.88 eV and 2.44 eV, for as-deposited films. For annealed films, indirect band gap increased to 2.57 eV while the direct optical band gap value remained constant. Upon annealing, the refractive indices (n) of the films decreased from 2.36 to 2.32. Ag/STO/p-Si device structures were also fabricated and characterized by current-voltage, capacitance-voltage and dielectric measurements. The calculated values are compared with experimental data from the literature and discussed in terms of device performances. A butterfly loop-type hysteresis curve was observed for the voltage-dependent capacitance measurement in annealed thin film devices. Dielectric constants were calculated as 31.7 and 57.4 for as-deposited and annealed films at 100 kHz, respectively. Charge storage capacity was found to be >4.5 ΌC cm-2 for as-deposited and 3.5 ΌC cm-2 for annealed films. © 2017 IOP Publishing Ltd
A novel quantum key distribution scheme with orthogonal product states
The general conditions for the orthogonal product states of the multi-state
systems to be used in quantum key distribution (QKD) are proposed, and a novel
QKD scheme with orthogonal product states in the 3x3 Hilbert space is
presented. We show that this protocol has many distinct features such as great
capacity, high efficiency. The generalization to nxn systems is also discussed
and a fancy limitation for the eavesdropper's success probability is reached.Comment: 4 Pages, 3 Figure
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