512 research outputs found
Flow graphs: interweaving dynamics and structure
The behavior of complex systems is determined not only by the topological
organization of their interconnections but also by the dynamical processes
taking place among their constituents. A faithful modeling of the dynamics is
essential because different dynamical processes may be affected very
differently by network topology. A full characterization of such systems thus
requires a formalization that encompasses both aspects simultaneously, rather
than relying only on the topological adjacency matrix. To achieve this, we
introduce the concept of flow graphs, namely weighted networks where dynamical
flows are embedded into the link weights. Flow graphs provide an integrated
representation of the structure and dynamics of the system, which can then be
analyzed with standard tools from network theory. Conversely, a structural
network feature of our choice can also be used as the basis for the
construction of a flow graph that will then encompass a dynamics biased by such
a feature. We illustrate the ideas by focusing on the mathematical properties
of generic linear processes on complex networks that can be represented as
biased random walks and also explore their dual consensus dynamics.Comment: 4 pages, 1 figur
Using citizen science to identify Australia’s least known birds and inform conservation action
Citizen science is a popular approach to biodiversity surveying, whereby data that are collected by volunteer naturalists may help analysts to understand the distribution and abundance of wild organisms. In Australia, birdwatchers have contributed to two major citizen science programs, eBird (run by the Cornell Lab of Ornithology) and Birdata (run by Birdlife Australia), which collectively hold more than 42 million records of wild birds from across the country. However, these records are not evenly distributed across space, time, or taxonomy, with particularly significant variation in the number of records of each species in these datasets. In this paper, we explore this variation and seek to determine which Australian bird species are least known as determined by rates of citizen science survey detections. We achieve this by comparing the rates of survey effort and species detection across each Australian bird species? range, assigning all 581 species to one of the four groups depending on their rates of survey effort and species observation. We classify 56 species into a group considered the most poorly recorded despite extensive survey effort, with Coxen?s Fig Parrot Cyclopsitta coxeni, Letter-winged Kite Elanus scriptus, Night Parrot Pezoporus occidentalis, Buff-breasted Buttonquail Turnix olivii and Red-chested Buttonquail Turnix pyrrhothorax having the very lowest numbers of records. Our analyses provide a framework to identify species that are poorly represented in citizen science datasets. We explore the reasons behind why they may be poorly represented and suggest ways in which targeted approaches may be able to help fill in the gaps.Publisher PDFPeer reviewe
An efficient and principled method for detecting communities in networks
A fundamental problem in the analysis of network data is the detection of
network communities, groups of densely interconnected nodes, which may be
overlapping or disjoint. Here we describe a method for finding overlapping
communities based on a principled statistical approach using generative network
models. We show how the method can be implemented using a fast, closed-form
expectation-maximization algorithm that allows us to analyze networks of
millions of nodes in reasonable running times. We test the method both on
real-world networks and on synthetic benchmarks and find that it gives results
competitive with previous methods. We also show that the same approach can be
used to extract nonoverlapping community divisions via a relaxation method, and
demonstrate that the algorithm is competitively fast and accurate for the
nonoverlapping problem.Comment: 14 pages, 5 figures, 1 tabl
GEMSEC: Graph Embedding with Self Clustering
Modern graph embedding procedures can efficiently process graphs with
millions of nodes. In this paper, we propose GEMSEC -- a graph embedding
algorithm which learns a clustering of the nodes simultaneously with computing
their embedding. GEMSEC is a general extension of earlier work in the domain of
sequence-based graph embedding. GEMSEC places nodes in an abstract feature
space where the vertex features minimize the negative log-likelihood of
preserving sampled vertex neighborhoods, and it incorporates known social
network properties through a machine learning regularization. We present two
new social network datasets and show that by simultaneously considering the
embedding and clustering problems with respect to social properties, GEMSEC
extracts high-quality clusters competitive with or superior to other community
detection algorithms. In experiments, the method is found to be computationally
efficient and robust to the choice of hyperparameters
Luspatercept for myelodysplastic syndromes/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis
Health-related quality of life in patients with β-thalassemia: Data from the phase 3 BELIEVE trial of luspatercept
BACKGROUND: Patients with transfusion-dependent (TD) β-thalassemia require long-term red blood cell transfusions (RBCTs) that lead to iron overload, impacting health-related quality of life (HRQoL). METHODS: The impact of luspatercept, a first-in-class erythroid maturation agent, versus placebo on HRQoL of patients with TD β-thalassemia was evaluated in the phase 3 BELIEVE trial. HRQoL was assessed at baseline and every 12 weeks using the 36-item Short Form Health Survey (SF-36) and Transfusion-dependent Quality of Life questionnaire (TranQol). Mean change in HRQoL was evaluated from baseline to week 48 for patients receiving luspatercept + best supportive care (BSC) and placebo + BSC and between luspatercept responders and non-responders. RESULTS: Through week 48, for both groups, mean scores on SF-36 and TranQol domains were stable over time and did not have a clinically meaningful change. At week 48, more patients who achieved clinical response (≥50% reduction in RBCT burden over 24 weeks) in the luspatercept + BSC group had improvement in SF-36 Physical Function compared with placebo + BSC (27.1% vs. 11.5%; p = .019). CONCLUSIONS: Luspatercept + BSC reduced transfusion burden while maintaining patients' HRQoL. HRQoL domain improvements from baseline through 48 weeks were also enhanced for luspatercept responders
Circadian hormone secretory profiles in women with severe premenstrual tension syndrome.
The circadian secretory profiles of serum prolactin, growth hormone and cortisol were measured in two women suffering from severe premenstrual tension syndrome and in two asymptomatic control subjects. Subjects and controls were screened and included after a rigorous selection process. Blood samples were obtained every 30 min over a period of 24 h in each woman both on day 9 (follicular phase) and day 26 (luteal phase) of the menstrual cycle. There was no relationship between the hormonal secretory profiles and the premenstrual tension syndrome.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75119/1/j.1471-0528.1984.tb04785.x.pd
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Multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories
This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element, finite element, finite difference, particle mechanics, and elastoplastic cellular automata methods. The simulation results indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure and permeability changes during the first 100 years (i.e., after emplacement and drift closure). Moreover, the results indicate that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and thermal stress, whereas such time-dependency is insignificant after peak temperature, because decreasing thermal stress
Universal Properties of Mythological Networks
As in statistical physics, the concept of universality plays an important,
albeit qualitative, role in the field of comparative mythology. Here we apply
statistical mechanical tools to analyse the networks underlying three iconic
mythological narratives with a view to identifying common and distinguishing
quantitative features. Of the three narratives, an Anglo-Saxon and a Greek text
are mostly believed by antiquarians to be partly historically based while the
third, an Irish epic, is often considered to be fictional. Here we show that
network analysis is able to discriminate real from imaginary social networks
and place mythological narratives on the spectrum between them. Moreover, the
perceived artificiality of the Irish narrative can be traced back to anomalous
features associated with six characters. Considering these as amalgams of
several entities or proxies, renders the plausibility of the Irish text
comparable to the others from a network-theoretic point of view.Comment: 6 pages, 3 figures, 2 tables. Updated to incorporate corrections from
EPL acceptance proces
Activation of the G-protein-coupled receptor GPR30 induces anxiogenic effects in mice, similar to oestradiol
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