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Search Results: 1 - 10 of 6296 matches for " Nicolas Massager "
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Clinical Impact of Targeting Inaccuracy Due to Distortion of the Leksell Stereotactic Frame  [PDF]
Cécile Renier, Nicolas Massager
Open Journal of Modern Neurosurgery (OJMN) , 2018, DOI: 10.4236/ojmn.2018.83026
Abstract: Background: Distortion of the Leksell stereotactic frame can occur during surgical and radiosurgical frame-based procedures. The targeting accuracies of surgical procedures such as DBS surgery or frame-based biopsy, or Gamma Knife radiosurgical procedures, are related to the stereotactic frame that is commonly referred to a non-deformable referential system. Objective: To evaluate the clinical impact of frame distortion on accuracy of targeting in various stereotactic procedures. Methods: We studied the influence of increasing levels of distortion of the Leksell frame both on surgical procedures using the stereotactic arch, and on radiosurgical procedures with the Gamma Knife. For surgical procedures we applied the Target Simulator of Elekta to a frame submitted to different levels of frame distortion, and we measured the modifications of accuracy of targeting. For radiosurgical procedures the Leksell frame was applied on an anthropomorphic phantom and modifications of target coordinates were measured by an imaging method using the stereotactic CBCT of the Gamma Knife ICON. Results: For surgical procedures, we found a linear relation between the amount of the frame distortion and the extent of the deviation from the stereotactic target using the stereotactic arch (R2 = 0.99709). The level of bending of the frame is also linearly related to the level of inaccuracy of stereotactic targeting based on acquisition of MRI and CTscan with the Elekta imaging boxes (R2 = 0.96825). The inaccuracy of targeting related to frame bending can be avoided by a systematic control at the end of frame placement and by the use of the CBCT of the Gamma Knife Icon. Conclusion: Distortion of the frame is a significant source of clinical inaccuracy of targeting for stereotactic procedures. Frame bending must be checked after each frame placement and corrected if needed to avoid targeting inaccuracy during stereotactic surgery and radio-surgery procedures.
The Future of Benthic Indicators: Moving up to the Intertidal  [PDF]
Nicolas Spilmont
Open Journal of Marine Science (OJMS) , 2013, DOI: 10.4236/ojms.2013.32A008
Abstract:

The use of benthic indicators has increased dramatically during the last decades. The number of articles published on the subject, as well as the number of citations, has been particularly increasing since the early 90’s, notably in relation with the implementation of directives for the management of aquatic/marine ecosystems such as the Water Framework Directive and the Marine Strategy Framework Directive. Current benthic indicators suffer from severe drawbacks and their practical use is still discussed and might have reached a dead end. Indicators based on species composition are not totally satisfactory, mainly because they exhibit a high spatio-temporal variability (e.g. variable at both seasonal and pluri-annual scales) and are user-dependent (e.g. divergent results from US orEuropeexperts.) In turn, modifications of behaviour, metabolism, phenotype or stable isotopes composition in invertebrates usually occur at short time scales, compared to detectable changes in community composition, and makes their use particularly relevant as indicators of perturbation. It is argued in this paper that these functional indicators might be relatively quickly implemented in the intertidal, and represent an effective alternative to current benthic indicators.

Cerebral Networks of Interfacial Water: Analogues of the Neural Correlates of Consciousness in a Synthetic Three-Shell Realistic Head Model  [PDF]
Nicolas Rouleau, Michael Persinger
Journal of Signal and Information Processing (JSIP) , 2014, DOI: 10.4236/jsip.2014.54017
Abstract: The physical properties of water, particularly the nature of interfacial water and pH shifts associated with dynamics of the hydronium ion near any surface, may be a primary source of the complex electromagnetic patterns frequently correlated with consciousness. Effectively all of the major correlates of consciousness, including the 40 Hz and 8 Hz coupling between the cerebral cortices and hippocampal formation, can be accommodated by the properties of water within a specific-shaped volume exposed to a magnetic field. In the present study, quantitative electroencephalographic activity was measured from an experimental simulation of the human head constructed using conductive dough whose pH could be changed systematically. Spectral analyses of electrical potentials generated over the regions equivalent to the left and right temporal lobes in humans exhibited patterns characteristic of Schumann Resonance. This fundamental and its harmonics are generated within the earth-ionospheric cavity with intensities similar to the volumetric intracerebral magnetic (~2 pT) and electric field (~6 × 10-1 V·m-1) strengths. The power densities for specific pH values were moderately correlated with those obtained from normal human brains for the fundamental (first) and second harmonic for the level simulating the cerebral cortices. Calculations indicated that the effective pH would be similar to that encountered within a single layer of protons near the plasma membrane surface. These results reiterate recent measurements in a large population of human brains showing the superimposition of Schumann power densities in QEEG data and indicate that intrinsic features of proton densities within cerebral water may be a fundamental basis to consciousness that can be simulated experimentally.
Local Electromagnetic Fields Exhibit Temporally Non-Linear, East-West Oriented 1 - 5 nT Diminishments within a Toroid: Empirical Measurement and Quantitative Solutions Indicating a Potential Mechanism for Excess Correlation  [PDF]
Nicolas Rouleau, Michael Persinger
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2015, DOI: 10.4236/jemaa.2015.72003
Abstract: States of excess correlation have previously been achieved at macroscopic levels by simultaneously exposing two non-local spaces to weak electromagnetic field patterns, generated by toroids, presented in a sequence such that the angular velocity of the field is modulated by changes in frequency over time. Here we systematically investigated effects upon the local space at the center of a single toroid generating the excess correlation sequence. The results indicated that a 1 - 5 nT diminishment in field intensity on the Y- or east-west axis was characteristic of the excess correlation sequence which was not indicated for control conditions. Statistically significant shifts in field intensity approximately 40 to 60 s before the onset of the first field associated with the excess correlation sequence indicated a temporally non-linear effect which converged upon the ratio of g and the rotational velocity of the Earth for the local space where Coriolis-like forces were inferred. Intensity shifts associated with the excess correlation sequence but not controls were quantitatively convergent upon parameters of the hydrogen line (1.42 GHz). Implications for these findings were discussed in relation to Mach’s principle and, in particular, to the electron as a physical unit which was found to relate classical and quantum systems.
Recent Trends in Occupational Injuries and Diseases in Argentina: A Panel Data Approach  [PDF]
Valentina Viego, Nicolas Sagui
Occupational Diseases and Environmental Medicine (ODEM) , 2015, DOI: 10.4236/odem.2015.34007
Abstract: Occupational injuries pose major public health and development related problems. However, efforts towards identification of determinants of labor incidents among salaried workers are still scarce in developing countries. This study aimed to identify sector and time effects on occupational accidents and diseases among Argentinean workers during 2004-2013. A negative binomial panel data model is estimated based on official data on injuries and fatalities in workplaces collected by the Board of Occupational Risks. Business cycle and profitability indicators are used as explanatory variables. Estimations also are adjusted by sector and time effects. Argentina business cycle tends to be negatively related with occupational injuries rates. In contrast, accidents at work reported tend to exhibit longer losses in working days. We also find a positive relationship between profitability and fatal injuries. These results may suggest incentives for under reporting and lower investments in safety by more profitable activities, which can imply some level of endogeneity between profit rate and occupational injuries.
Two-dimensional graphic representation and analysis of learners’ traces
Nicolas Delestre,Nicolas Malandain
STICEF , 2007,
Abstract: The learner follow-up in problem solving is a hard issue. It is more difficult when there are a lot of learners or when those learners use distance learning. We propose in this paper a two-dimensional graphic representation of student's traces. To achieve this goal, we use and modify numerical analysis algorithms (automatic dimensionality reduction algorithms like Self Organizing Map and Stochastic Neighbour Embedding). We also propose a new distance between sets whose elements have semantic similarity. Finally, we validate and improve our algorithm with simulated data and experimental data
Experimental neck muscle pain impairs standing balance in humans
Nicolas Vuillerme,Nicolas Pinsault
Physics , 2009, DOI: 10.1007/s00221-008-1639-7
Abstract: Impaired postural control has been reported in patients with chronic neck pain of both traumatic and non-traumatic etiologies, but whether painful stimulation of neck muscle per se can affect balance control during quiet standing in humans remains unclear. The purpose of the present experiment was thus to investigate the effect of experimental neck muscle pain on standing balance in young healthy adults. To achieve this goal, 16 male university students were asked to stand upright as still as possible on a force platform with their eyes closed in two conditions of No pain and Pain of the neck muscles elicited by experimental painful electrical stimulation. Postural control and postural performance were assessed by the displacements of the center of foot pressure (CoP) and of the center of mass (CoM), respectively. The results showed increased CoP and CoM displacements variance, range, mean velocity, and mean and median frequencies in the Pain relative to the No pain condition. The present findings emphasize the destabilizing effect of experimental neck muscle pain per se, and more largely stress the importance of intact neck neuromuscular function on standing balance.
Partial list of bipartite Bell inequalities with four binary settings
Nicolas Brunner,Nicolas Gisin
Physics , 2007, DOI: 10.1016/j.physleta.2008.01.052
Abstract: We give a partial list of 26 tight Bell inequalities for the case where Alice and Bob choose among four two-outcome measurements. All tight Bell inequalities with less settings are reviewed as well. For each inequality we compute numerically the maximal quantum violation, the resistance to noise and the minimal detection efficiency required for closing the detection loophole. Surprisingly, most of these inequalities are outperformed by the CHSH inequality.
Anderson localization of elementary excitations in a one dimensional Bose-Einstein condensate
Nicolas Bilas,Nicolas Pavloff
Physics , 2006, DOI: 10.1140/epjd/e2006-00166-3
Abstract: We study the elementary excitations of a transversely confined Bose-Einstein condensate in presence of a weak axial random potential. We determine the localization length (i) in the hydrodynamical low energy regime, for a domain of linear densities ranging from the Tonks-Girardeau to the transverse Thomas-Fermi regime, in the case of a white noise potential and (ii) for all the range of energies, in the ``one-dimensional mean field regime'', in the case where the randomness is induced by a series of randomly placed point-like impurities. We discuss our results in view of recent experiments in elongated BEC systems.
Quantum cryptography with and without entanglement
Nicolas Gisin,Nicolas Brunner
Physics , 2003,
Abstract: Quantum cryptography is reviewed, first using entanglement both for the intuition and for the experimental realizations. Next, the implementation is simplified in several steps until it becomes practical. At this point entanglement has disappeared. This method can be seen as a lesson of Applied Physics. Finally, security issues, e.g. photon number splitting attacks, and counter-measures are discussed.
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