3,962 research outputs found
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Sporormiella as a tool for detecting the presence of large herbivores in the Neotropics
The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in temperate regions, we find that Sporormiella spores are a useful proxy to study the extinction of Pleistocene megafauna or the arrival of European livestock in Neotropical landscapes
Persistent currents in a circular array of Bose-Einstein condensates
A ring-shaped array of Bose-Einstein condensed atomic gases can display
circular currents if the relative phase of neighboring condensates becomes
locked to certain values. It is shown that, irrespective of the mechanism
responsible for generating these states, only a restricted set of currents are
stable, depending on the number of condensates, on the interaction and
tunneling energies, and on the total number of particles. Different
instabilities due to quasiparticle excitations are characterized and possible
experimental setups for testing the stability prediction are also discussed.Comment: 7 pages, REVTex
Probabilistic Guarded P Systems, A New Formal Modelling Framework
Multienvironment P systems constitute a general, formal
framework for modelling the dynamics of population biology, which consists
of two main approaches: stochastic and probabilistic. The framework
has been successfully used to model biologic systems at both micro (e.g.
bacteria colony) and macro (e.g. real ecosystems) levels, respectively.
In this paper, we extend the general framework in order to include
a new case study related to P. Oleracea species. The extension is made
by a new variant within the probabilistic approach, called Probabilistic
Guarded P systems (in short, PGP systems). We provide a formal definition,
a simulation algorithm to capture the dynamics, and a survey of
the associated software.Ministerio de Economía y Competitividad TIN2012- 37434Junta de Andalucía P08-TIC-0420
The normalization of online campaigning in the web.2.0 era
This article is based on a comparative study of online campaigning and its effects by country and over time, using four of the largest European Union member states (France, Germany, Poland and the United Kingdom) as a case study. Our research explores the extent of embeddedness of online campaigning, the strategic uses of the whole online environment and in particular the use of the interactive features associated with web.2.0 era. However, our research goes beyond studies of online campaigning as we also determine whether online campaigning across platforms matters in electoral terms. Our data support the normalization hypothesis which shows overall low levels of innovation but that the parties with the highest resources tend to develop online campaigns with the highest functionality. We find that there is a vote dividend for those parties which utilized web.2.0 features the most and so offered visitors to their web presence a more interactive experience
Evaluation of the health-related quality of life of children in Schistosoma haematobium-endemic communities in Kenya: a cross-sectional study.
BACKGROUND: Schistosomiasis remains a global public health challenge, with 93% of the ~237 million infections occurring in sub-Saharan Africa. Though rarely fatal, its recurring nature makes it a lifetime disorder with significant chronic health burdens. Much of its negative health impact is due to non-specific conditions such as anemia, undernutrition, pain, exercise intolerance, poor school performance, and decreased work capacity. This makes it difficult to estimate the disease burden specific to schistosomiasis using the standard DALY metric.
METHODOLOGY/PRINCIPAL FINDINGS: In our study, we used Pediatric Quality of Life Inventory (PedsQL), a modular instrument available for ages 2-18 years, to assess health-related quality of life (HrQoL) among children living in a Schistosoma haematobium-endemic area in coastal Kenya. The PedsQL questionnaires were administered by interview to children aged 5-18 years (and their parents) in five villages spread across three districts. HrQoL (total score) was significantly lower in villages with high prevalence of S. haematobium (-4.0%, p<0.001) and among the lower socioeconomic quartiles (-2.0%, p<0.05). A greater effect was seen in the psychosocial scales as compared to the physical function scale. In moderate prevalence villages, detection of any parasite eggs in the urine was associated with a significant 2.1% (p<0.05) reduction in total score. The PedsQL reliabilities were generally high (Cronbach alphas ≥0.70), floor effects were acceptable, and identification of children from low socioeconomic standing was valid.
CONCLUSIONS/SIGNIFICANCE: We conclude that exposure to urogenital schistosomiasis is associated with a 2-4% reduction in HrQoL. Further research is warranted to determine the reproducibility and responsiveness properties of QoL testing in relation to schistosomiasis. We anticipate that a case definition based on more sensitive parasitological diagnosis among younger children will better define the immediate and long-term HrQoL impact of Schistosoma infection
P-splines with derivative based penalties and tensor product smoothing of unevenly distributed data
The P-splines of Eilers and Marx (1996) combine a B-spline basis with a
discrete quadratic penalty on the basis coefficients, to produce a reduced rank
spline like smoother. P-splines have three properties that make them very
popular as reduced rank smoothers: i) the basis and the penalty are sparse,
enabling efficient computation, especially for Bayesian stochastic simulation;
ii) it is possible to flexibly `mix-and-match' the order of B-spline basis and
penalty, rather than the order of penalty controlling the order of the basis as
in spline smoothing; iii) it is very easy to set up the B-spline basis
functions and penalties. The discrete penalties are somewhat less interpretable
in terms of function shape than the traditional derivative based spline
penalties, but tend towards penalties proportional to traditional spline
penalties in the limit of large basis size. However part of the point of
P-splines is not to use a large basis size. In addition the spline basis
functions arise from solving functional optimization problems involving
derivative based penalties, so moving to discrete penalties for smoothing may
not always be desirable. The purpose of this note is to point out that the
three properties of basis-penalty sparsity, mix-and-match penalization and ease
of setup are readily obtainable with B-splines subject to derivative based
penalization. The penalty setup typically requires a few lines of code, rather
than the two lines typically required for P-splines, but this one off
disadvantage seems to be the only one associated with using derivative based
penalties. As an example application, it is shown how basis-penalty sparsity
enables efficient computation with tensor product smoothers of scattered data
Lattice Boltzmann simulations in microfluidics: probing the no-slip boundary condition in hydrophobic, rough, and surface nanobubble laden microchannels
In this contribution we review recent efforts on investigations of the effect
of (apparent) boundary slip by utilizing lattice Boltzmann simulations. We
demonstrate the applicability of the method to treat fundamental questions in
microfluidics by investigating fluid flow in hydrophobic and rough
microchannels as well as over surfaces covered by nano- or microscale gas
bubbles.Comment: 11 pages, 6 figure
Estimating the robustness and uncertainty of animal social networks using different observational methods
Social network analysis is quickly becoming an established framework to study the structure of animal social systems. To explore the social network of a population, observers must capture data on the interactions or associations between individuals. Sampling decisions significantly impact the outcome of data collection, notably the amount of data available from which to construct social networks. However, little is known about how different sampling methods, and more generally the extent of sampling effort, impact the robustness of social network analyses. Here, we generate proximity networks from data obtained via nearly continuous GPS tracking of members of a wild baboon troop (Papio anubis). These data allow us to produce networks based on complete observations of inter-individual distances between group members. We then mimic several widely used focal animal sampling and group scanning methods by subsampling the complete dataset to simulate observational data comparable to that produced by human observers. We explore how sampling effort, sampling methods, network definitions, and levels and types of sampling error affect the correlation between the estimated and complete networks. Our results suggest that for some scenarios, even low levels of sampling effort (5-10 samples/individual) can provide the same information as high sampling effort (>64 samples/individual). However, we find that insufficient data collected across all potentially interacting individuals, certain network definitions (how edge weights and distance thresholds are calculated) and misidentifications of individuals in the network can generate spurious network structure with little or no correlation to the underlying or “real” social structure. Our results suggest that data collection methods should be designed to maximize the number of potential interactions (edges) recorded each observation. We discuss the relative trade-offs between maximizing the amount of data collected across as many individuals as possible and the potential for erroneous observations
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Leaving the Past (Self) Behind: Non-Reporting Rape Survivors' Narratives of Self and Action
Using a symbolic interactionist framework, this study considers the narratives of non-reporting rape survivors. We use interviews to examine the complex processes that inform a survivor’s decision not to report. Rape is not interpreted as an isolated event; it is something that is seen as caused by, connected to, and affecting the survivor’s sense of self and agency. Rape forces the survivor to reconstruct a sense of agency in the aftermath of the traumatic attack. Rather than report the rape, the survivors constructed narratives that direct blame and accountability toward the “old self”. This less visible, yet still agentic strategy, allows the survivors to regain a sense of agency and control. As a result, a more positive, optimistic self can be constructed, while pursuing legal justice would force them to reenact an “old” self that cannot be disentangled from the rape
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