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Search Results: 1 - 10 of 1664 matches for " Juliano Zimmer "
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Um novo método para sele o de variáveis preditivas com base em índices de importancia A new framework for predictive variable selection based on variable importance indices
Juliano Zimmer,Michel José Anzanello
Produ??o , 2013,
Abstract: O grande volume de variáveis coletadas em processos industriais imp e dificuldades ao controle e monitoramento de tais processos. A regress o PLS (partial least squares) vem sendo amplamente utilizada em procedimentos de sele o de variáveis por sua capacidade de operar com grande número de variáveis correlacionadas e afetadas por ruído. Este artigo prop e um método para identificar o melhor subconjunto de variáveis de processo para a predi o das variáveis de resposta. Indicadores de importancia das variáveis s o desenvolvidos a partir de parametros da regress o PLS e guiam a elimina o das variáveis irrelevantes. Tais índices s o ent o testados em termos de seu desempenho. Ao ser aplicado em cinco bancos de dados industriais, o método utilizando o índice recomendado reteve apenas 31% das variáveis originais e aumentou a acurácia de predi o do conjunto de teste em 6%. O método proposto também superou a acurácia do método Stepwise, tradicionalmente utilizado em procedimentos de sele o com propósitos de predi o. The large volume of process variables collected from manufacturing applications has jeopardized process control activities. The Partial Least Squares (PLS) regression has been widely used for variable selection due to its ability to handle a large number of correlated and noisy variables. This paper presents a method for selecting the most relevant variables aimed at predicting product variables. For that matter, variable importance indices are developed based on PLS parameters and used to guide the elimination of noisy and irrelevant variables. Variables are then systematically removed from the dataset and the performance of the predictive model evaluated. When applied to five manufacturing datasets, the proposed method retained 31% of the original variables and yielded 6% more accurate predictions than using all original variables. Further, the proposed method outperformed the traditional Stepwise method regarding prediction accuracy.
Wind-Driven Dynamics of Beach-Cast Wrack in a Tide-Free System  [PDF]
Sven Hammann, Martin Zimmer
Open Journal of Marine Science (OJMS) , 2014, DOI: 10.4236/ojms.2014.42009

Whereas wrack dynamics on tidally influenced beaches have been studied to some detail, essentially nothing is known about how drift lines in tide-free coastal systems vary in space and time. We provide evidence for high spatial and temporal dynamics of beach-cast wrack on a sand beach in the Western Baltic Sea. Over the course of one year, the amount of weekly deposited macrophyte wrack fluctuated from zero to 3000 g·m-1 shoreline. Wrack mostly accumulated just above the waterline. Part of the beach-cast wrack is frequently re-suspended into coastal water upon extreme high water level events, or wrack patches are translocated landwards by wind-driven changes in water level or along the shoreline by winds. Consequently, the deposited wrack does accumulate, but a steady-state of ca 400 g·m-1 builds up within 2 - 3 weeks. Eelgrass wrack buried in sand decomposed almost twice as fast as on top of the sand or re-suspended in water. Fragmentation of leaves promoted decomposition only when wrack remained on the sand surface. The spatial and temporal distribution of this valuable source of organic matter is unpredictable and depends on wind and wind-driven waves.

Correction: The Genome: An Outsider's View
Carl Zimmer
PLOS Computational Biology , 2007, DOI: 10.1371/journal.pcbi.0030047
The Genome: An Outsider's View
Carl Zimmer
PLOS Computational Biology , 2006, DOI: 10.1371/journal.pcbi.0020156
Effects of Tetrodotoxin on the Mammalian Cardiovascular System
Thomas Zimmer
Marine Drugs , 2010, DOI: 10.3390/md8030741
Abstract: The human genome encodes nine functional voltage-gated Na + channels. Three of them, namely Na v1.5, Na v1.8, and Na v1.9, are resistant to nanomolar concentrations of tetrodotoxin (TTX; IC 50 ≥ 1 μM). The other isoforms, which are predominantly expressed in the skeletal muscle and nervous system, are highly sensitive to TTX (IC 50 ~ 10 nM). During the last two decades, it has become evident that in addition to the major cardiac isoform Na v1.5, several of those TTX sensitive isoforms are expressed in the mammalian heart. Whereas immunohistochemical and electrophysiological methods demonstrated functional expression in various heart regions, the physiological importance of those isoforms for cardiac excitation in higher mammals is still debated. This review summarizes our knowledge on the systemic cardiovascular effects of TTX in animals and humans, with a special focus on cardiac excitation and performance at lower concentrations of this marine drug. Altogether, these data strongly suggest that TTX sensitive Na + channels, detected more recently in various heart tissues, are not involved in excitation phenomena in the healthy adult heart of higher mammals.
RNA Replicons - A New Approach for Influenza Virus Immunoprophylaxis
Gert Zimmer
Viruses , 2010, DOI: 10.3390/v2020413
Abstract: RNA replicons are derived from either positive- or negative-strand RNA viruses. They represent disabled virus vectors that are not only avirulent, but also unable to revert to virulence. Due to autonomous RNA replication, RNA replicons are able to drive high level, cytosolic expression of recombinant antigens stimulating both the humoral and the cellular branch of the immune system. This review provides an update on the available literature covering influenza virus vaccines based on RNA replicons. The pros and cons of these vaccine strategies will be discussed and future perspectives disclosed.
V_{ud} from neutron beta decay
Zimmer, Oliver
High Energy Physics - Phenomenology , 2013,
Abstract: The experimental determination of V_{ud} from neutron beta decay requires accurate values of the neutron lifetime and the ratio of the weak axial-vector to vector coupling constants of the nucleon. The latter is derived from measurements of angular correlation coefficients in the differential decay probability, such as the beta asymmetry parameter A, the neutrino-electron angular correlation coefficient a, or the parameter C of the proton asymmetry. As a probe free from nuclear structure corrections the decay of the free neutron has the potential to provide the most accurate value of V_{ud}. Towards that end however, the experimental sensitivity still needs to be further improved to become competitive with superallowed nuclear beta decays. This contribution briefly reviews the current status of those neutron decay studies relevant for the determination of V_{ud}.
Versatile Packaging Concept Using Thick Film Hybrids for Analog and Digital Circuits
Ch. Zimmer
Active and Passive Electronic Components , 1983, DOI: 10.1155/apec.10.209
Characterization of N-terminally mutated cardiac Na+ channels associated with long QT syndrome 3 and Brugada syndrome
Thomas Zimmer
Frontiers in Physiology , 2013, DOI: 10.3389/fphys.2013.00153
Abstract: Mutations in SCN5A, the gene encoding the cardiac voltage-gated Na+ channel hNav1.5, can result in life-threatening arrhythmias including long QT syndrome 3 (LQT3) and Brugada syndrome (BrS). Numerous mutant hNav1.5 channels have been characterized upon heterologous expression and patch-clamp recordings during the last decade. These studies revealed functionally important regions in hNav1.5 and provided insight into gain-of-function or loss-of-function channel defects underlying LQT3 or BrS, respectively. The N-terminal region of hNav1.5, however, has not yet been investigated in detail, although several mutations were reported in the literature. In the present study we investigated three mutant channels, previously associated with LQT3 (G9V, R18W, V125L), and six mutant channels, associated with BrS (R18Q, R27H, G35S, V95I, R104Q, K126E). We applied both the two-microelectrode voltage clamp technique, using cRNA-injected Xenopus oocytes, and the whole-cell patch clamp technique using transfected HEK293 cells. Surprisingly, four out of the nine mutations did not affect channel properties. Gain-of-function, as typically observed in LQT3 mutant channels, was observed only in R18W and V125L, whereas loss-of-function, frequently found in BrS mutants, was found only in R27H, R104Q, and K126E. Our results indicate that the hNav1.5 N-terminus plays an important role for channel kinetics and stability. At the same time, we suggest that additional mechanisms, as e.g., disturbed interactions of the Na+ channel N-terminus with other proteins, contribute to severe clinical phenotypes.
Constraining spin-dependent short range interactions using neutron spin precession close to a mirror
O. Zimmer
Physics , 2008, DOI: 10.1016/j.physletb.2010.01.046
Abstract: Spin-dependent short range interactions of free neutrons with matter may be searched for in various ways. This short note discusses pseudomagnetic precession of trapped ultracold neutrons in vicinity to bulk matter, which should be several orders of magnitude more sensitive than any other method proposed so far.
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