168 research outputs found
Nível de dano do percevejo Barriga-Verde Dichelops melacanthus na cultura do trigo Triticum aestivum L.
bitstream/CPAO-2010/32713/1/COT2010159.pd
Entomofauna associada à cultura da mandioca na região sul de Mato Grosso do Sul.
bitstream/item/38729/1/BP200637.pd
Competitive percolation strategies for network recovery
Restoring operation of critical infrastructure systems after catastrophic
events is an important issue, inspiring work in multiple fields, including
network science, civil engineering, and operations research. We consider the
problem of finding the optimal order of repairing elements in power grids and
similar infrastructure. Most existing methods either only consider system
network structure, potentially ignoring important features, or incorporate
component level details leading to complex optimization problems with limited
scalability. We aim to narrow the gap between the two approaches. Analyzing
realistic recovery strategies, we identify over- and undersupply penalties of
commodities as primary contributions to reconstruction cost, and we demonstrate
traditional network science methods, which maximize the largest connected
component, are cost inefficient. We propose a novel competitive percolation
recovery model accounting for node demand and supply, and network structure.
Our model well approximates realistic recovery strategies, suppressing growth
of the largest connected component through a process analogous to explosive
percolation. Using synthetic power grids, we investigate the effect of network
characteristics on recovery process efficiency. We learn that high structural
redundancy enables reduced total cost and faster recovery, however, requires
more information at each recovery step. We also confirm that decentralized
supply in networks generally benefits recovery efforts.Comment: 14 pages, 6 figure
Dynamics of fully coupled rotators with unimodal and bimodal frequency distribution
We analyze the synchronization transition of a globally coupled network of N
phase oscillators with inertia (rotators) whose natural frequencies are
unimodally or bimodally distributed. In the unimodal case, the system exhibits
a discontinuous hysteretic transition from an incoherent to a partially
synchronized (PS) state. For sufficiently large inertia, the system reveals the
coexistence of a PS state and of a standing wave (SW) solution. In the bimodal
case, the hysteretic synchronization transition involves several states.
Namely, the system becomes coherent passing through traveling waves (TWs), SWs
and finally arriving to a PS regime. The transition to the PS state from the SW
occurs always at the same coupling, independently of the system size, while its
value increases linearly with the inertia. On the other hand the critical
coupling required to observe TWs and SWs increases with N suggesting that in
the thermodynamic limit the transition from incoherence to PS will occur
without any intermediate states. Finally a linear stability analysis reveals
that the system is hysteretic not only at the level of macroscopic indicators,
but also microscopically as verified by measuring the maximal Lyapunov
exponent.Comment: 22 pages, 11 figures, contribution for the book: Control of
Self-Organizing Nonlinear Systems, Springer Series in Energetics, eds E.
Schoell, S.H.L. Klapp, P. Hoeve
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Exotic states in a simple network of nanoelectromechanical oscillators.
Synchronization of oscillators, a phenomenon found in a wide variety of natural and engineered systems, is typically understood through a reduction to a first-order phase model with simplified dynamics. Here, by exploiting the precision and flexibility of nanoelectromechanical systems, we examined the dynamics of a ring of quasi-sinusoidal oscillators at and beyond first order. Beyond first order, we found exotic states of synchronization with highly complex dynamics, including weak chimeras, decoupled states, traveling waves, and inhomogeneous synchronized states. Through theory and experiment, we show that these exotic states rely on complex interactions emerging out of networks with simple linear nearest-neighbor coupling. This work provides insight into the dynamical richness of complex systems with weak nonlinearities and local interactions
Further investigation of confirmed urinary tract infection (UTI) in children under five years: a systematic review.
Background: Further investigation of confirmed UTI in children aims to prevent renal scarring and future complications. Methods: We conducted a systematic review to determine the most effective approach to the further investigation of confirmed urinary tract infection (UTI) in children under five years of age. Results: 73 studies were included. Many studies had methodological limitations or were poorly reported. Effectiveness of further investigations: One study found that routine imaging did not lead to a reduction in recurrent UTIs or renal scarring. Diagnostic accuracy: The studies do not support the use of less invasive tests such as ultrasound as an alternative to renal scintigraphy, either to rule out infection of the upper urinary tract (LR- = 0.57, 95%CI: 0.47, 0.68) and thus to exclude patients from further investigation or to detect renal scarring (LR+ = 3.5, 95% CI: 2.5, 4.8). None of the tests investigated can accurately predict the development of renal scarring. The available evidence supports the consideration of contrast-enhanced ultrasound techniques for detecting vesico-ureteric reflux (VUR), as an alternative to micturating cystourethrography (MCUG) (LR+ = 14.1, 95% CI: 9.5, 20.8; LR- = 0.20, 95%CI: 0.13, 0.29); these techniques have the advantage of not requiring exposure to ionising radiation. Conclusion: There is no evidence to support the clinical effectiveness of routine investigation of children with confirmed UTI. Primary research on the effectiveness, in terms of improved patient outcome, of testing at all stages in the investigation of confirmed urinary tract infection is urgently required
Meningeal dissemination in primary CNS lymphoma: prospective evaluation of 282 patients
BACKGROUND: The impact of meningeal dissemination in primary CNS lymphoma (PCNSL) is debated, and the reported frequency varies. We prospectively evaluated the diagnostic value of PCR in comparison with CSF cytomorphology and MRI for diagnosing meningeal dissemination in PCNSL. METHODS: We evaluated 282 patients from a multicenter therapy study for PCNSL for the presence of meningeal dissemination: 205 with CSF cytomorphology, 171 with PCR of the rearranged immunoglobulin heavy-chain genes in CSF, and 217 with cranial MRI. RESULTS: Meningeal dissemination was found in 33 of 205 patients (16%) by cytomorphology, in 19 of 171 (11%) patients evaluated by PCR, and in 8 of 217 patients (4%) by MRI. Considering either of these methods, the relative frequency of meningeal dissemination was 17.4% (49 of 282 patients). PCR was monoclonal in 6 of 19 (32%) samples with positive cytomorphology, 1 of 13 samples (8%) with suspicious cytology, and in 10 of 105 (10%) cytologically negative samples. In 11 samples with positive and 12 with suspicious cytology, PCR showed only a polyclonal pattern. The probability of meningeal dissemination detection was higher in cases with CSF pleocytosis (>5/microL) with an OR of 2.48 (95% CI 1.15-5.34, p = 0.018). CSF protein had no predictive value for meningeal dissemination detection. CONCLUSIONS: We found a low rate of meningeal dissemination in primary CNS lymphoma in this large prospective study. The rate of discordant PCR and cytomorphologic results was high. Thus, the methods should be regarded as complementary. CSF pleocytosis had predictive value for meningeal dissemination detection
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