Papers by Camila da Silva
AIP Conference Proceedings, 2008
AIP Conference Proceedings, 2006
ISTTOK has performed one of the earliest experiments of AC tokamak operation showing that long di... more ISTTOK has performed one of the earliest experiments of AC tokamak operation showing that long discharges could be produced merely with inductive current drive. However, due to the design of the machine, the data acquisition system and the power supplies, a limit of 250 ms (six times the nominal forward shot duration) is currently imposed. In this paper the relevant
This contribution summarizes the current implementation of the time-of-flight (TOF) energy analys... more This contribution summarizes the current implementation of the time-of-flight (TOF) energy analysis for plasma potential measurements by the heavy ion beam diagnostic (HIBD) on the tokamak ISTTOK. The technique is described in detail. The results of the measurements of the ISTTOK plasma potential radial profile are presented. It is proved that the TOF energy analysis is suitable for simultaneous multichannel detection using a multiple cell array detector. With the aim of improving the signal-to-noise ratio of the diagnostic, the channeltrons have recently been installed on the "start" and "stop" detectors and preliminary results are discussed.
Review of Scientific Instruments, 2008
The heavy ion beam probe (HIBP) diagnostic permits the measurements of electron density and plasm... more The heavy ion beam probe (HIBP) diagnostic permits the measurements of electron density and plasma potential as well as their fluctuations. The use of a multiple cell array detector (MCAD) spreads the HIBP capabilities to make simultaneous measurements across the plasma column. Two sets of current-to-voltage converters with respective bandwidths of 400 kHz and 4 MHz have been tested. This upgrade of the MCAD electronics has allowed the observation of quasicoherent fluctuations in bulk plasma at frequencies between 100 and 200 kHz. The localization and frequency of bulk plasma fluctuations correlate with the magnetohydranamic activity of the plasma.
Lecture Notes in Computer Science, 2006
The first task in that proposal was to develop an external module for implementing tabling primit... more The first task in that proposal was to develop an external module for implementing tabling primitives that provide direct control over the search strategy. ® The external module will serve as the basis to study how tabling interacts with the EAM and to detect in advance the potential integration problems before incorporating tabling within the EAM environment.
Synthetic Metals, 2003
We have investigated the dynamics of photoexcitations in chiral assemblies of p-phenylenevinylene... more We have investigated the dynamics of photoexcitations in chiral assemblies of p-phenylenevinylene oligomers functionalized with hydrogen-bonding motifs. In the regime of low excitation densities, the luminescence transients are influenced by the migration of excitons to defect sites, indicative of fast diffusivity of excitons along the molecular assemblies. In addition, at high excitation densities, bimolecular exciton annihilation is shown to result in the fast depopulation of the stacks' excitonic energy levels.
Review of Scientific Instruments, 2012
A pinhole probe (PHP) for the simultaneous measurement of the parallel, T∥, and perpendicular, T⊥... more A pinhole probe (PHP) for the simultaneous measurement of the parallel, T∥, and perpendicular, T⊥, ion temperature has been designed and tested in the scrape-off-layer (SOL) plasma of the tokamak ISTTOK. The PHP consists of a tunnel immersed into the plasma parallel to magnetic field and an ion collector. One end of the tunnel is covered with a thin foil that has a pinhole sampling ions from the plasma. The other end of the tunnel (close to the negatively biased collector) is covered with a fine-mesh screen. The possibility of performing an analytical description of the PHP current-to-voltage characteristics obtained on the collector when biasing the tunnel simplifies the interpretation of the results. The PHP operation has been previously tested in T∥, T⊥ measurements in low temperature weekly magnetized plasma [H. Mase, T. Honzava, and G. Miyamoto, J. Appl. Phys. 49(10), 5171 (1978)]10.1063/1.324412. In this paper, the PHP operation in the SOL of the tokamak ISTTOK is described, a...
Plasma Physics and Controlled Fusion, 2007
In the present paper we report on a novel mechanical probe, which is able to measure the plasma p... more In the present paper we report on a novel mechanical probe, which is able to measure the plasma pressure directly. The probe consists of two pendulums whose heads are exposed to the tokamak edge plasma, while the deflection is measured very sensitively outside the plasma by means of semi-conductor strain gauges. The plasma pressure was successfully measured in the ISTTOK
Plasma Physics and Controlled Fusion, 2009
Journal of Nuclear Materials, 2011
The ISTTOK edge plasma parameters show significant poloidal asymmetries in both equilibrium and f... more The ISTTOK edge plasma parameters show significant poloidal asymmetries in both equilibrium and fluctuating parameters. Asymmetries favoring the outboard side are observed in density, turbulent particle flux and diffusion coefficient independently of the toroidal magnetic field direction, suggesting a ballooning-like transport. This interpretation is supported by the characteristics of the fluctuations as they are found to be more intermittent on
International Journal of Clinical Practice, 2006
Refractory neurogenic detrusor overactivity refers to the clinical condition that is no longer ma... more Refractory neurogenic detrusor overactivity refers to the clinical condition that is no longer manageable by anticholinergic therapy. This condition represents a formidable task to caregivers because the treatment of urinary incontinence and adequate protection of the upper urinary tract become extremely difficult. Treatment options for refractory neurogenic detrusor overactivity include detrusor injections of botulinum toxin and intravesical instillation of vanilloid compounds, mainly resiniferatoxin, or anticholinergic drugs. If these options fail, bladder augmentation or sacral anterior root stimulation offers excellent outcomes, although at much higher costs and risks to the patients.
Insect Biochemistry and Molecular Biology, 1999
Determinations of carbohydrases, aminopeptidases and acid phosphatase in the larval midgut cells ... more Determinations of carbohydrases, aminopeptidases and acid phosphatase in the larval midgut cells and in the luminal contents of Callosobruchus maculatus and Zabrotes subfasciatus have been carried out. The results showed that larvae of both species displayed similar distribution of digestive enzymes in the intestinal compartments. Most larval digestive enzyme activities were found in the luminal contents. Of the activities found in the midgut tissue, only aminopeptidase is predominant in the membrane fraction. Comparisons of activities recovered from a seed flour mass equivalent to the midgut mass showed that a high percentage of the luminal aminopeptidase activity and, to a lesser extent, α-galactosidase activity, can be derived from the seeds, whereas the other enzymes are produced by the insects. Activities against starch, maltose and maltodextrins were found to show the highest levels of activity, followed by enzymes active against galactosyl oligosaccharides. Based on differences in elution profiles on hydrophobic chromatography and banding patterns in mildly denaturing electrophoresis, both species showed a multiplicity of glycosidases. The data suggest that the majority of carbohydrate digestion occurs in the midgut lumen, whereas protein digestion should take place partly in the lumen and partly at the cell surface. Larvae of Z. subfasciatus can modulate the levels of α-amylases and α-glucosidase in response to different diets. The complex of carbohydrases found is qualitatively appropriate to digest the free oligosaccharides and oligomaltodextrins produced by α-amylases from the starch granules of host seeds.
IEEE Transactions on Nuclear Science, 2011
A real-time plasma position control system is manda- tory to achieve long duration (up to 250 ms)... more A real-time plasma position control system is manda- tory to achieve long duration (up to 250 ms), Alternating Cur- rent (AC) discharges on the ISTTOK tokamak. Such a system has been used for some time supported only on magnetic field diag- nostic data. However, this system is clearly challenged when the plasma current is low, rendering it inoperative during the
Fusion Engineering and Design, 2004
We have developed a digital signal processor-based system for real-time control of the ISTTOK pla... more We have developed a digital signal processor-based system for real-time control of the ISTTOK plasma position based on a low-cost digital signal processor (DSP) board. A novel plasma shape reproduction method was developed using a Cauchy-condition expansion applied to the vacuum region around the plasma. This method showed to be best suited than classic methods such as Legendre-Fourier expansion (LFE) or current filaments (CF), particularly in small tokamaks with passive stabilizer conductors where the presence of strong eddy currents can cause significant errors in magnetic field sensors. We compare the results of the boundary reconstruction method with the measurements from a microwave interferometer diagnostic. We present an implementation in the DSP system that allows the real time control of the plasma position with a required 1 ms period.
Fisheries Research, 2007
In this study the performance of computational neural networks (CNNs) models to forecast 1-month ... more In this study the performance of computational neural networks (CNNs) models to forecast 1-month ahead monthly anchovy catches in the north area of Chile considering only anchovy catches in previous months as inputs to the models was analysed. For that purpose several CNN approaches were implemented and compared: (a) typical autoregressive univariate CNN models; (b) a convolution process of the input variables to the CNN model; (c) recurrent neural networks (Elman model); (d) a hybrid methodology combining CNN and ARIMA models. The results obtained in two different external validation phases showed that CNN having inputs of anchovy catches of the 6 previous months hybridised with ARIMA(2,0,0) provided very accurate estimates of the monthly anchovy catches. For this model, the explained variance in the external validation fluctuated between 84% and 87%, the standard error of prediction (SEP, %) was lower than 31% and mean absolute error (MAE) was around 18,000 tonnes. Also, significant results were obtained with recurrent neural networks and seasonal hybrid CNN + ARIMA models. The strong correlation among estimated and observed anchovy catches in the external validation phases suggests that calibrated models captured the general trend of the historical data and therefore these models can be used to carry out an accuracy forecast in the context of a short-medium term time period.
European Urology, 2000
< bold> Obj... more < bold> Objectives:</bold> To assess the pungency and the desensitizing effects of intravesical resiniferatoxin, an ultrapotent capsaicin analog, in patients with detrusor hyperreflexia.< p>< bold> Methods:</bold> Fourteen patients with detrusor hyperreflexia ...
Critical Care, 2008
Introduction In order to find out the frequency rates of domestic and wild animal bites as well a... more Introduction In order to find out the frequency rates of domestic and wild animal bites as well as the evaluation of the prevalence rates of rabies disease in the human population in the Province of Kerman, a retrospective study was designed to analyze statistically the collected recorded data related to this project. Methods This study was conducted within the framework of MPVM student research projects by means of collaboration between
Actividad Pesquera y de …, 2003
... Claudio Silva G.1, Eleuterio Yáñez R.1, María Angela Barbieri B.1,2 y Karen Nieto S ... Barbi... more ... Claudio Silva G.1, Eleuterio Yáñez R.1, María Angela Barbieri B.1,2 y Karen Nieto S ... Barbieri, MA, M. Bravo, M. Farías, A. González, O. Pizarro & E. Yáñez. ... Fenómenos aso-ciados a la estructura térmica superficial del mar observados a través de imágenes satelitales en la zona ...
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Papers by Camila da Silva