1,723 research outputs found
Identification of Nonlinear Normal Modes of Engineering Structures under Broadband Forcing
The objective of the present paper is to develop a two-step methodology
integrating system identification and numerical continuation for the
experimental extraction of nonlinear normal modes (NNMs) under broadband
forcing. The first step processes acquired input and output data to derive an
experimental state-space model of the structure. The second step converts this
state-space model into a model in modal space from which NNMs are computed
using shooting and pseudo-arclength continuation. The method is demonstrated
using noisy synthetic data simulated on a cantilever beam with a
hardening-softening nonlinearity at its free end.Comment: Journal pape
High Efficacy of Two Artemisinin-Based Combinations (Artesunate + Amodiaquine and Artemether + Lumefantrine) in Caala, Central Angola.
In April 2004, 137 children 6-59 months of age with uncomplicated Plasmodium falciparum (Pf) malaria (Caala, Central Angola) were randomized to receive either artemether-lumefantrine (Coartem) or artesunate + amodiaquine (ASAQ). After 28 days of follow-up, there were 2/61 (3.2%) recurrent parasitemias in the Coartem group and 4/64 (6.2%) in the ASAQ group (P = 0.72), all classified as re-infections after PCR genotyping (cure rate = 100% [95%CI: 94-100] in both groups). Only one patient (ASAQ group) had gametocytes on day 28 versus five (Coartem) and three (ASAQ) at baseline. Compared with baseline, anemia was significantly improved after 28 days of follow-up in both groups (Coartem: from 54.1% to 13.4%; ASAQ: from 53.1% to 15.9%). Our findings are in favor of a high efficacy of both combinations in Caala. Now that Coartem has been chosen as the new first-line anti-malarial, the challenge is to insure that this drug is available and adequately used
How Multivalency controls Ionic Criticality
To understand how multivalency influences the reduced critical temperatures,
Tce (z), and densities, roce (z), of z : 1 ionic fluids, we study equisized
hard-sphere models with z = 1-3. Following Debye, Hueckel and Bjerrum,
association into ion clusters is treated with, also, ionic solvation and
excluded volume. In good accord with simulations but contradicting
integral-equation and field theories, Tce falls when z increases while roce
rises steeply: that 80-90% of the ions are bound in clusters near T_c serves to
explain these trends. For z \neq 1 interphase Galvani potentials arise and are
evaluated.Comment: 4 pages, 4 figure
Propagation on networks: an exact alternative perspective
By generating the specifics of a network structure only when needed
(on-the-fly), we derive a simple stochastic process that exactly models the
time evolution of susceptible-infectious dynamics on finite-size networks. The
small number of dynamical variables of this birth-death Markov process greatly
simplifies analytical calculations. We show how a dual analytical description,
treating large scale epidemics with a Gaussian approximations and small
outbreaks with a branching process, provides an accurate approximation of the
distribution even for rather small networks. The approach also offers important
computational advantages and generalizes to a vast class of systems.Comment: 8 pages, 4 figure
Experience with the LEP vacuum system at energies above 90 GeV and future expectations
The LEP storage ring has been operated at energies above 90 GeV for more than 1000 hours during 1997. Because of the rapid increase with the beam energy of the power radiated as synchrotron light, the vacuum system has been submitted to very stringent conditions as far as power evacuation and photon stimulated gas desorption are concerned. The operational experience acquired under these, up to now unexplored, conditions will be reviewed together with an outline of the limitations which were experienced at these high levels of radiation in the use of the available vacuum instrumentation. Based o n the available data detailed predictions concerning the beam lifetime, gas desorption and beam cleaning of the vacuum system under the impact of photons with a critical energy approaching 1 MeV will be formulated
Cadmium accumulation and interactions with zinc, copper, and manganese, analysed by ICP-MS in a long-term Caco-2 TC7 cell model
The influence of long-term exposure to cadmium (Cd) on essential minerals was investigated using a Caco-2
TC7 cells and a multi-analytical tool: microwave digestion and inductively coupled plasma mass spectrometry.
Intracellular levels, effects on cadmium accumulation, distribution, and reference concentration
ranges of the following elements were determined: Na, Mg, Ca, Cr, Fe, Mn, Co, Ni, Cu, Zn, Mo, and Cd.
Results showed that Caco-2 TC7 cells incubated long-term with cadmium concentrations ranging from 0 to
10 lmol Cd/l for 5 weeks exhibited a significant increase in cadmium accumulation. Furthermore, this
accumulation was more marked in cells exposed long-term to cadmium compared with controls, and that
this exposure resulted in a significant accumulation of copper and zinc but not of the other elements
measured. Interactions of Cd with three elements: zinc, copper, and manganese were particularly studied.
Exposed to 30 lmol/l of the element, manganese showed the highest inhibition and copper the lowest on
cadmium intracellular accumulation but Zn, Cu, and Mn behave differently in terms of their mutual
competition with Cd. Indeed, increasing cadmium in the culture medium resulted in a gradual and significant
increase in the accumulation of zinc. There was a significant decrease in manganese from 5 lmol
Cd/l exposure, and no variation was observed with copper.
Abbreviation: AAS – Atomic absorption spectrometry; CRM– Certified reference material; PBS – Phosphate
buffered saline without calcium and magnesium; DMEM – Dubelcco’s modified Eagle’s medium
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