93 research outputs found
Critical phenomena in complex networks
The combination of the compactness of networks, featuring small diameters,
and their complex architectures results in a variety of critical effects
dramatically different from those in cooperative systems on lattices. In the
last few years, researchers have made important steps toward understanding the
qualitatively new critical phenomena in complex networks. We review the
results, concepts, and methods of this rapidly developing field. Here we mostly
consider two closely related classes of these critical phenomena, namely
structural phase transitions in the network architectures and transitions in
cooperative models on networks as substrates. We also discuss systems where a
network and interacting agents on it influence each other. We overview a wide
range of critical phenomena in equilibrium and growing networks including the
birth of the giant connected component, percolation, k-core percolation,
phenomena near epidemic thresholds, condensation transitions, critical
phenomena in spin models placed on networks, synchronization, and
self-organized criticality effects in interacting systems on networks. We also
discuss strong finite size effects in these systems and highlight open problems
and perspectives.Comment: Review article, 79 pages, 43 figures, 1 table, 508 references,
extende
Knowledge and perceptions of the risks of non-steroidal anti-inflammatory drugs among orthopaedic patients in Thailand
Background There is a high incidence of adverse effects from non-steroidal antiinflammatory drugs (NSAIDs) in Thailand, but patients’ perceptions and knowledge of NSAID risks is unknown. Objective This study aims to assess patients’ perceptions and knowledge of NSAID risks and factors affecting them. Setting University hospital in North-East of Thailand. Method A Cross-sectional study conducted over 4 months, using a self-administered questionnaire. Patients prescribed NSAIDs for at least one month duration from orthopaedic clinic were recruited using systematic random sampling. Main outcome measure Patients’ perceptions on NSAID risks, knowledge on risk factors, and their associated factors. Results A total of 474 questionnaires were assessed. Overall perceptions of risks was low (scoring below five on a 0–10 visual analogue scale), with risks associated with the renal system scoring highest. Perceived risk of gastrointestinal problems differed between patients using non-selective and selective NSAIDs (3.47 ± 2.75 vs 2.06 ± 2.98; P < 0.001). Receiving side effect information from a health professional was associated with higher risk perception. Most patients (80 %) identified high doses, renal disease and gastrointestinal ulcer increased risks of NSAIDs, but fewer than half recognized that use in the elderly, multiple NSAID use, drinking, hypertension and cardiovascular disease also increased risk of adverse events. Having underlying diseases and receiving side effect information were associated with 1.6–2.0 fold increased knowledge of NSAID risks. Conclusion Perceptions and knowledge concerning NSAID risks was generally low in Thai patients, but higher in those who had received side effect information. Risk-related information should be widely provided, especially in high-risk patients
Challenges of beta-deformation
A brief review of problems, arising in the study of the beta-deformation,
also known as "refinement", which appears as a central difficult element in a
number of related modern subjects: beta \neq 1 is responsible for deviation
from free fermions in 2d conformal theories, from symmetric omega-backgrounds
with epsilon_2 = - epsilon_1 in instanton sums in 4d SYM theories, from
eigenvalue matrix models to beta-ensembles, from HOMFLY to super-polynomials in
Chern-Simons theory, from quantum groups to elliptic and hyperbolic algebras
etc. The main attention is paid to the context of AGT relation and its possible
generalizations.Comment: 20 page
Changes in seasonal streamflow extremes experienced in rivers of Northwestern South America (Colombia)
A measure of the variability in seasonal extreme streamflow was estimated for the Colombian Caribbean coast, using monthly time series of freshwater discharge from ten watersheds. The aim was to detect modifications in the streamflow monthly distribution, seasonal trends, variance and extreme monthly values. A 20-year length time moving window, with 1-year successive shiftments, was applied to the monthly series to analyze the seasonal variability of streamflow. The seasonal-windowed data were statistically fitted through the Gamma distribution function. Scale and shape parameters were computed using the Maximum Likelihood Estimation (MLE) and the bootstrap method for 1000 resample. A trend analysis was performed for each windowed-serie, allowing to detect the window of maximum absolute values for trends. Significant temporal shifts in seasonal streamflow distribution and quantiles (QT), were obtained for different frequencies.
Wet and dry extremes periods increased significantly in the last decades. Such increase did not occur simultaneously through the region. Some locations exhibited continuous increases only at minimum QT
- …