3,216 research outputs found
Supervised learning for suicidal ideation detection in online user content
Copyright Š 2018 Shaoxiong Ji et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Early detection and treatment are regarded as the most effective ways to prevent suicidal ideation and potential suicide attempts-two critical risk factors resulting in successful suicides. Online communication channels are becoming a new way for people to express their suicidal tendencies. This paper presents an approach to understand suicidal ideation through online user-generated content with the goal of early detection via supervised learning. Analysing users' language preferences and topic descriptions reveals rich knowledge that can be used as an early warning system for detecting suicidal tendencies. Suicidal individuals express strong negative feelings, anxiety, and hopelessness. Suicidal thoughts may involve family and friends. And topics they discuss cover both personal and social issues. To detect suicidal ideation, we extract several informative sets of features, including statistical, syntactic, linguistic, word embedding, and topic features, and we compare six classifiers, including four traditional supervised classifiers and two neural network models. An experimental study demonstrates the feasibility and practicability of the approach and provides benchmarks for the suicidal ideation detection on the active online platforms: Reddit SuicideWatch and Twitter
Testing for Network and Spatial Autocorrelation
Testing for dependence has been a well-established component of spatial
statistical analyses for decades. In particular, several popular test
statistics have desirable properties for testing for the presence of spatial
autocorrelation in continuous variables. In this paper we propose two
contributions to the literature on tests for autocorrelation. First, we propose
a new test for autocorrelation in categorical variables. While some methods
currently exist for assessing spatial autocorrelation in categorical variables,
the most popular method is unwieldy, somewhat ad hoc, and fails to provide
grounds for a single omnibus test. Second, we discuss the importance of testing
for autocorrelation in data sampled from the nodes of a network, motivated by
social network applications. We demonstrate that our proposed statistic for
categorical variables can both be used in the spatial and network setting
Building block libraries and structural considerations in the self-assembly of polyoxometalate and polyoxothiometalate systems
Inorganic metal-oxide clusters form a class of compounds that are unique in their topological and electronic versatility and are becoming increasingly more important in a variety of applications. Namely, Polyoxometalates (POMs) have shown an unmatched range of physical properties and the ability to form structures that can bridge several length scales. The formation of these molecular clusters is often ambiguous and is governed by self-assembly processes that limit our ability to rationally design such molecules. However, recent years have shown that by considering new building block principles the design and discovery of novel complex clusters is aiding our understanding of this process. Now with current progress in thiometalate chemistry, specifically polyoxothiometalates (POTM), the field of inorganic molecular clusters has further diversified allowing for the targeted development of molecules with specific functionality. This chapter discusses the main differences between POM and POTM systems and how this affects synthetic methodologies and reactivities. We will illustrate how careful structural considerations can lead to the generation of novel building blocks and further deepen our understanding of complex systems
Different reactions to adverse neighborhoods in games of cooperation
In social dilemmas, cooperation among randomly interacting individuals is
often difficult to achieve. The situation changes if interactions take place in
a network where the network structure jointly evolves with the behavioral
strategies of the interacting individuals. In particular, cooperation can be
stabilized if individuals tend to cut interaction links when facing adverse
neighborhoods. Here we consider two different types of reaction to adverse
neighborhoods, and all possible mixtures between these reactions. When faced
with a gloomy outlook, players can either choose to cut and rewire some of
their links to other individuals, or they can migrate to another location and
establish new links in the new local neighborhood. We find that in general
local rewiring is more favorable for the evolution of cooperation than
emigration from adverse neighborhoods. Rewiring helps to maintain the diversity
in the degree distribution of players and favors the spontaneous emergence of
cooperative clusters. Both properties are known to favor the evolution of
cooperation on networks. Interestingly, a mixture of migration and rewiring is
even more favorable for the evolution of cooperation than rewiring on its own.
While most models only consider a single type of reaction to adverse
neighborhoods, the coexistence of several such reactions may actually be an
optimal setting for the evolution of cooperation.Comment: 12 pages, 5 figures; accepted for publication in PLoS ON
Holographic Entanglement Entropy in P-wave Superconductor Phase Transition
We investigate the behavior of entanglement entropy across the holographic
p-wave superconductor phase transition in an Einstein-Yang-Mills theory with a
negative cosmological constant. The holographic entanglement entropy is
calculated for a strip geometry at AdS boundary. It is found that the
entanglement entropy undergoes a dramatic change as we tune the ratio of the
gravitational constant to the Yang-Mills coupling, and that the entanglement
entropy does behave as the thermal entropy of the background black holes. That
is, the entanglement entropy will show the feature of the second order or first
order phase transition when the ratio is changed. It indicates that the
entanglement entropy is a good probe to investigate the properties of the
holographic phase transition.Comment: 19 pages,15 figures, extended discussion in Sec.5, references adde
Holographic Charged Fluid with Anomalous Current at Finite Cutoff Surface in Einstein-Maxwell Gravity
The holographic charged fluid with anomalous current in Einstein-Maxwell
gravity has been generalized from the infinite boundary to the finite cutoff
surface by using the gravity/fluid correspondence. After perturbing the boosted
Reissner-Nordstrom (RN)-AdS black brane solution of the Einstein-Maxwell
gravity with the Chern-Simons term, we obtain the first order perturbative
gravitational and Maxwell solutions, and calculate the stress tensor and
charged current of the dual fluid at finite cutoff surfaces which contains
undetermined parameters after demanding regularity condition at the future
horizon. We adopt the Dirichlet boundary condition and impose the Landau frame
to fix these parameters, finally obtain the dependence of transport
coefficients in the dual stress tensor and charged current on the arbitrary
radical cutoff . We find that the dual fluid is not conformal, but it has
vanishing bulk viscosity, and the shear viscosity to entropy density ratio is
universally . Other transport coefficients of the dual current turns
out to be cutoff-dependent. In particular, the chiral vortical conductivity
expressed in terms of thermodynamic quantities takes the same form as that of
the dual fluid at the asymptotic AdS boundary, and the chiral magnetic
conductivity receives a cutoff-dependent correction which vanishes at the
infinite boundary.Comment: 19 pages, v2: references added, v3: typos corrected, v5: typos
corrected, version accepted for publication in JHE
Feeding spectra and activity of the freshwater crab Trichodactylus kensleyi (Decapoda: Brachyura: Trichodactylidae) at La Plata basin
Background: In inland water systems, it is important to characterize the trophic links in order to identify the âtrophic speciesâ and, from the studies of functional diversity, understand the dynamics of matter and energy in these environments. The aim of this study is to analyze the natural diet of Trichodactylus kensleyi of subtropical rainforest streams and corroborate the temporal variation in the trophic activity during day hours.
Results: A total of 15 major taxonomic groups were recognized in gut contents. The index of relative importance identified the following main prey items in decreasing order of importance: vegetal remains, oligochaetes, chironomid larvae, and algae. A significant difference was found in the amount of full stomachs during day hours showing a less trophic activity at midday and afternoon. The index of relative importance values evidenced the consumption of different prey according to day moments. Results of the gut content indicate that T. kensleyi is an omnivorous crab like other trichodactylid species. Opportunistic behavior is revealed by the ingestion of organisms abundant in streams such as oligochaetes and chironomid larvae. The consumption of allochthonous plant debris shows the importance of this crab as shredder in subtropical streams. However, the effective assimilation of plant matter is yet unknown in trichodactylid crabs.
Conclusions: This research provides knowledge that complements previous studies about trophic relationships of trichodactylid crabs and supported the importance of T. kensleyi in the transference of energy and matter from benthic community and riparian sources to superior trophic levels using both macro- and microfauna.Fil: Williner, VerĂłnica. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto Nacional de LimnologĂa. Universidad Nacional del Litoral. Instituto Nacional de LimnologĂa; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: de Azevedo Carvalho, Debora. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto Nacional de LimnologĂa. Universidad Nacional del Litoral. Instituto Nacional de LimnologĂa; ArgentinaFil: Collins, Pablo Agustin. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto Nacional de LimnologĂa. Universidad Nacional del Litoral. Instituto Nacional de LimnologĂa; Argentina. Universidad Nacional del Litoral. Facultad de BioquĂmica y Ciencias BiolĂłgicas; Argentin
Treatment Outcomes and Cost-Effectiveness of Shifting Management of Stable ART Patients to Nurses in South Africa: An Observational Cohort
Lawrence Long and colleagues report that âdown-referringâ stable HIV patients from a doctor-managed, hospital-based ART clinic to a nurse-managed primary health facility provides good health outcomes and cost-effective treatment for patients
Brane-World Gravity
The observable universe could be a 1+3-surface (the "brane") embedded in a
1+3+\textit{d}-dimensional spacetime (the "bulk"), with Standard Model
particles and fields trapped on the brane while gravity is free to access the
bulk. At least one of the \textit{d} extra spatial dimensions could be very
large relative to the Planck scale, which lowers the fundamental gravity scale,
possibly even down to the electroweak ( TeV) level. This revolutionary
picture arises in the framework of recent developments in M theory. The
1+10-dimensional M theory encompasses the known 1+9-dimensional superstring
theories, and is widely considered to be a promising potential route to quantum
gravity. At low energies, gravity is localized at the brane and general
relativity is recovered, but at high energies gravity "leaks" into the bulk,
behaving in a truly higher-dimensional way. This introduces significant changes
to gravitational dynamics and perturbations, with interesting and potentially
testable implications for high-energy astrophysics, black holes, and cosmology.
Brane-world models offer a phenomenological way to test some of the novel
predictions and corrections to general relativity that are implied by M theory.
This review analyzes the geometry, dynamics and perturbations of simple
brane-world models for cosmology and astrophysics, mainly focusing on warped
5-dimensional brane-worlds based on the Randall--Sundrum models. We also cover
the simplest brane-world models in which 4-dimensional gravity on the brane is
modified at \emph{low} energies -- the 5-dimensional Dvali--Gabadadze--Porrati
models. Then we discuss co-dimension two branes in 6-dimensional models.Comment: A major update of Living Reviews in Relativity 7:7 (2004)
"Brane-World Gravity", 119 pages, 28 figures, the update contains new
material on RS perturbations, including full numerical solutions of
gravitational waves and scalar perturbations, on DGP models, and also on 6D
models. A published version in Living Reviews in Relativit
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