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An accurate implementation of wetting and pressure drop is crucial to correctly reproduce fluid displacement processes in porous media. Although several strategies have been proposed in the literature, a systematic comparison of them is needed to determine the most suitable for practical applications. Here, we carried out numerical simulations to investigate the performance of two widely used wettability schemes in the lattice Boltzmann color gradient model, namely, the geometrical wetting scheme by Leclaire et al. [Phys. Rev. E 95(3), 033306 (2017)](scheme-I) and the modified direction of the color gradient scheme by Akai et al. [Adv. Water Resour. 116, 56–66 (2018)] (scheme-II). We showed that scheme-II was more accurate in simulating static contact angles of a fluid droplet on a solid surface. However, scheme-I was more accurate in simulating a dynamic case of a binary fluid flow in a horizontal capillary tube described by the Washburn equation. Moreover, we investigated the performance of two popular pressure gradient implementation types. Type-I used the so-called Zou–He pressure boundary conditions at the inlet and the outlet of the domain, while type-II used an external body force as a pressure gradient. We showed that the type-I implementation was slightly more accurate in simulating a neutrally wetting fluid in a horizontal capillary tube described by the Washburn equation. We also investigated the differences between the two types of pressure gradient implementation in simulating two fluid displacement processes in a Bentheimer sandstone rock sample: the primary drainage and the imbibition displacement processes. [ABSTRACT FROM AUTHOR]

We study almost complex structures with lower bounds on the rank of the Nijenhuis tensor. Namely, we show that they satisfy an h-principle. As a consequence, all parallelizable manifolds and all manifolds of dimension 2 n ≥ 10 (respectively ≥ 6 ) admit a almost complex structure whose Nijenhuis tensor has maximal rank everywhere (resp. is nowhere trivial). For closed 4-manifolds, the existence of such structures is characterized in terms of topological invariants. Moreover, we show that the Dolbeault cohomology of non-integrable almost complex structures is often infinite dimensional (even on compact manifolds). [ABSTRACT FROM AUTHOR]

We generalize a recently developed improved multicomponent pseudopotential lattice Boltzmann method in three dimensions and analyze its applicability to simulate flows through realistic porous media. The model is validated and characterized via benchmarks, and we investigate its performance by simulating the displacement of immiscible fluids in three-dimensional geometries. Two samples are considered, namely, a pack of spheres obtained numerically and a Bentheimer sandstone rock sample obtained experimentally. We show that with this model, it is possible to simulate realistic viscosity ratios, to tune surface tension independently, and, most importantly, to preserve the volume of trapped fluid. We also evaluate the computational performance of the model on the graphical processing unit and mention the implemented optimizations to increase the computational speed and reduce the memory requirements. [ABSTRACT FROM AUTHOR]

Immiscible fluid displacement in porous media occurs in several natural and industrial processes. For example, during petroleum extraction from porous rock reservoirs, water is used to displace oil. In this paper, we investigate the primary drainage and imbibition in a heterogeneous porous medium using an improved numerical model based on the multicomponent pseudopotential lattice Boltzmann method. We apply recent developments from the literature and develop new pressure boundary conditions. We show that the proposed model is able to simulate realistic viscosity ratios, and it allows independent tuning of surface tension from viscosity. Moreover, the model suppresses a nonphysical behavior of previous schemes, in which trapped fluid volumes significantly change with time. Furthermore, we show that the developed model correctly captures the underlying physical phenomena of fluid displacements. We simulate oil–water flows and verify that the measured values of irreducible water and residual oil saturations are realistic. Finally, we vary the wetting conditions of the porous medium to represent different wettability states. For the different scenarios, we show that the simulations are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The principle of conservation of energy tells us that 'energy can neither be created nor destroyed but only transformed'. The validity of the principle is without question. The problem is the concept. Contemporary physicists have asserted that we do not know what energy is. We find, however, 19th century physicists, contemporary physicists and historians of science who converge on the point: Mayer and Joule discovered energy. Therefore, we do not know what energy is, but we know these authors discovered it. What did they then discover? What can we learn from this with regard to the energy concept problem? To deal with this issue, I will distinguish between what the authors did experimentally and what they said about the phenomena. This method of analysis makes the difference in relation to historical works on the subject. In a second step, I will consider the introduction of the energy concept, which is from 1850s, and the reification of the energy in 1880s. Finally, I will address the energy conservation principle and the concept of energy conveyed by this principle in contemporary textbooks. As we shall see, the conservation of a magnitude that we call energy nowadays was discovered by Mayer and Joule; an indestructible and transformable entity was not. Adopting the original conservation principle would be enough to avoid the energy concept problem. [ABSTRACT FROM AUTHOR]

The present comment on Solari and Natiello's paper (Found. Sci. 2019) values their constructivist approach to Newtonian Mechanics. My critical point concerns only the link between the concept of force and phenomena. It will be shown that the idealised form of the law of inertia created by the authors avoids criticism of the law and that this law (idealised or not) leads to the concept of force as the cause of acceleration. This concept appears in the authors' reconstruction as an assumption. They add that this assumption must be contrasted with experiments. Following this, I address an experiment, in which the force that is taken as the cause of acceleration, is not present in the phenomenon at stake. As it thus does not satisfy the property of locality, which any cause has to, force cannot be a cause. [ABSTRACT FROM AUTHOR]

In this paper we present a detailed analysis of the contribution of the Light-by-Light (LbL), Durham and double diffractive processes for the diphoton production in ultraperipheral PbPb collisions at the Large Hadron Collider (LHC), High-Energy LHC (HE-LHC) and Future Circular Collider (FCC). The acceptance of the central and forward LHC detectors is taken into account and predictions for the invariant mass, rapidity, transverse momentum and acoplanarity distributions are presented. Our results indicate that the contribution of the Durham process is negligible and that the double diffractive process can be strongly suppressed by the exclusivity cuts, which will allow to perform a precise analysis of the LbL scattering, as well the search of beyond Standard Model physics in this final state. [ABSTRACT FROM AUTHOR]

We learned at high school and university that Newton’s second law is F=ma. However, Newton never wrote this equation. Furthermore, there is no agreement among historians of science as to the equation that expresses Newton’s second law. On the other hand, Euler claimed to have discovered a principle of mechanics, which is F=ma. The respective paper of Euler provides us with the means of clarifying the issue. We can compare Newton’s second law and Euler’s principle with each other and verify whether there are significant differences between both laws. This is the task of the present paper. The result is that Newton’s axiomatic system and technique of decomposing force differ from Euler’s. [ABSTRACT FROM AUTHOR]

The occurrence of tiger shark Galeocerdo cuvier in the Atlantic Ocean was assessed using at-sea observer data from multiple pelagic longline fisheries. Geographic positions of 2764 G. cuvier recorded between 1992 and 2013 and covering a wide area of the Atlantic Ocean were compared with the currently accepted distribution ranges of the species. Most records fell outside those ranges in both the Southern and Northern Hemispheres, which strongly suggests that the distribution range of G. cuvier in the open ocean is considerably larger than previously described [ABSTRACT FROM AUTHOR]

In this article, a unified framework is introduced for robust structural topology optimization for 2D and 3D continuum and truss problems. The uncertain material parameters are modelled using a spatially correlated random field which is discretized using the Karhunen–Loève expansion. The spectral stochastic finite element method is used, with a polynomial chaos expansion to propagate uncertainties in the material characteristics to the response quantities. In continuum structures, either 2D or 3D random fields are modelled across the structural domain, while representation of the material uncertainties in linear truss elements is achieved by expanding 1D random fields along the length of the elements. Several examples demonstrate the method on both 2D and 3D continuum and truss structures, showing that this common framework provides an interesting insight into robustness versus optimality for the test problems considered. [ABSTRACT FROM AUTHOR]

In a dynamic and evolving society there is a need for temporary and mobile structures. For this, deployable scissor structures – structural mechanisms that can transform from a compact state to a fully deployed configuration – are suitable. However, this transformational capacity complicates the design process since there is a strong interaction between geometry, kinematic properties and structural response. In the conceptual design phase there is a need for more structural insight related to geometric aspects of deployable scissor structures. Toward this end, this research evaluates the influence of design parameters (height, span, structural thickness, number of units, and scissor type) on the structural behaviour (stress, deflection and mass) of scissor arches. A sensitivity analysis is first performed which determines the relative influence of each of these parameters. Then a comprehensive parametric structural study is performed to determine the best values for efficient (low mass) scissor systems. The result of this research is a set of guidelines to facilitate the design of competitive scissor structures and enhance further analysis and realisation. [ABSTRACT FROM AUTHOR]

Modeling machining operations has been a challenge since the 1900s. It has been by empirical, science-based, and computer-based modeling, which started with FEM by the 1970s. For success material, rupture, friction, and convection have to be correctly modeled. Computation time has always been one of the main limitations for accurately describing heat propagation on machining. The present work proposes and tests a hybrid model using an explicit algorithm for the chip formation and an implicit one for heat propagation. Heat flux on workpiece and tool were obtained by the explicit and used as input to the implicit. Simulated results were in good agreement with experimental end milling for very short periods of computer time. [ABSTRACT FROM AUTHOR]

This study presents experimental evidence for the sequence of activation and the evolution of primary tension (TTW), secondary compression (CTW) and tertiary double twinning (DTW) in an extruded Mg-4wt%Li alloy during uniaxial compression by means of in-situ and ex-situ EBSD and (HR-)TEM. In-situ EBSD analysis reveals that the secondary CTWs propagate very slowly, while the tertiary DTWs propagate faster once nucleated. Thereby, when DTW-ing overtakes the CTW, CTW boundary migration stops, indicating that the thickness of the CTW is limited by the onset of internal DTW-ing. This finding confirms some prior proposals based on post-mortem analyses. High-resolution (HR-)TEM analysis of a -18% compressed sample reveals significant basal slip activity and a high amount of basal stacking faults within the primary TTW as well as within the secondary CTW. Additionally, the HR-TEM analysis showed a large amount of basal dislocations within the area of the CTW-DTW transition. These findings give strong experimental evidence that the observed predominance of type 1 DTW-ing is related to the dissociation of extended basal dislocations. [ABSTRACT FROM AUTHOR]

Objective Childhood maltreatment ( CM) has been associated with several diseases in adult life, including diabetes, obesity and mental disorders. Inflammatory conditions have been postulated as possible mediators of this relationship. The aim was to conduct a systematic review regarding the association between CM and inflammatory markers in adulthood. Method A literature search of the Pub Med, ISI, EMBASE and Psych INFO databases was conducted. The key terms used were as follows: 'Child Maltreatment', 'Childhood Trauma', 'Early Life Stress', 'Psychological Stress', 'Emotional Stress', 'Child Abuse' and 'Child Neglect'. They were cross-referenced separately with the terms: 'C-reactive Protein (CRP)', 'Tumor Necrosis Factor', 'Cytokine', 'Interleukin', 'Inflammatory' and 'Inflammation'. Results Twenty articles remained in the review after exclusion criteria were applied. Studies showed that a history of CM was associated with increased levels of CRP, fibrinogen and proinflammatory cytokines. Increased levels of circulating CRP in individuals with a history of CM were the most robust finding among the studies. Data about anti-inflammatory mediators are still few and inconsistent. Conclusion Childhood maltreatment is associated with a chronic inflammatory state independent of clinical comorbidities. However, studies are heterogeneous regarding CM assessment and definition. Important methodological improvements are needed to better understand the potential impact of CM on inflammatory response. [ABSTRACT FROM AUTHOR]

Magnetohydrodynamic (MHD) activity in magnetically confined fusion experiments is often associated with detrimental effects such as increased radial transport and consequent loss of confinement. In particular, the (2,1) neoclassical tearing mode (NTM), when proceeding to mode-locking, is a potentially disruptive instability hence with the potential to compromise the mechanical integrity of the machine. It is therefore quite significant to be able to characterize in real-time the most virulent and performance limiting instabilities such that adequate mitigation or complete stabilization using feedback control methods are employed during the plasma discharge. This work proposes a Kalman filter (KF) based mechanism for providing, in real-time, the amplitude and phase evolution of instabilities within a predefined set of mode numbers. The method relies on two KF implementations: a non-linear KF isolating the non-stationary dominant signal component of a sensor measurement and subsequently a linear KF which projects the former, for a collection of sensors, onto a predefined set of mode numbers. A basic overview of algorithms commonly used for real-time mode number analysis is also presented along with applications of the proposed algorithm to recently recorded data of the Joint European Torus (JET) tokamak. [ABSTRACT FROM AUTHOR]

The real-time tracking of instantaneous quantities such as frequency, amplitude, and phase of components immerse in noisy signals has been a common problem in many scientific and engineering fields such as power systems and delivery, telecommunications, and acoustics for the past decades. In magnetically confined fusion research, extracting this sort of information from magnetic signals can be of valuable assistance in, for instance, feedback control of detrimental magnetohydrodynamic modes and disruption avoidance mechanisms by monitoring instability growth or anticipating mode-locking events. This work is focused on nonlinear Kalman filter based methods for tackling this problem. Similar methods have already proven their merits and have been successfully employed in this scientific domain in applications such as amplitude demodulation for the motional Stark effect diagnostic. In the course of this work, three approaches are described, compared, and discussed using magnetic signals from the Joint European Torus tokamak plasma discharges for benchmarking purposes. [ABSTRACT FROM AUTHOR]

There has been much research on Schrӧdinger's route to what we now call Schrӧdinger's equation. Various authors disagree as to the exact nature of the influence of each of the physicists he cites--and of some that he does not. This paper, intended for graduate students of and researchers in quantum theory, clarifies Schrӧdinger's original aims in formulating a wave equation for matter, discusses how far he fulfilled his original aspirations and in what respects he fell short of his goal. An analysis of Schrӧdinger's foundational paper enables us to distinguish between a formal and an epistemological part, and consider the input of the physicists cited on the basis of the part in which each reference occurs. It turns out, for instance, that Hamilton's optical-mechanical analogy belongs entirely to the epistemological part. Indeed, no element of this analogy plays any role in the formal part of Schrӧdinger's argument. Instead of basing his theory on this analogy, as is often done nowadays in the physics literature and even in the history of science, we maintain that the aim of Schrӧdinger's project was to represent wave phenomena by a 'wave' in configuration- or q-space, parallelingHertz's treatment in his Mechanics (1894). The influence of this book on Schrӧdinger's foundational paper is demonstrated by an analysis of his unpublished paper: Hertz'sMechanics and Einstein's Theory ofGravitation. This approach enables us to dispense with the optical-mechanical analogy in tracing the route to Schrӧdinger's equation. We also discuss the curious role of the Van Vleck determinant as the 'missing link' in taking the classical limit of Schrӧdinger's wavefunction. A concluding section discusses the relation of some of Schrӧdinger's earlier and later work to the development of quantum field theory. [ABSTRACT FROM AUTHOR]

Real-time harmonic estimation and frequency tracking are well known pivotal problems in many engineering domains. Incidentally, similar challenges arise in tokamak plasma diagnostics' data processing where the spectral complexity of characteristic signals poses additional obstacles. Building up on previous Kalman filter based developments, this paper describes an adaptive real-time algorithm for simultaneous multi-component frequency tracking and harmonic estimation in noisy signals. Furthermore, the proposed gain adaptation method is shown to improve estimation performance in cases where the amplitude ratio of signal components differs by roughly up to three orders of magnitude. A series of selectively devised tests were carried out for challenging the performance and determining the operational limits of the algorithm when aiming to provide accurate estimates, in real-time, of both instantaneous amplitude and phase plus the instantaneous frequency evolution of dominant tones in noisy signals. Finally, results and performance issues are discussed. [ABSTRACT FROM PUBLISHER]

Abstract: This paper deals with the preliminary shape design of three-dimensional bridge structures. For crossing wide spans, lightweight truss structures are well-suited. Due to their complex equilibrium state involving a geometrically nonlinear behaviour, the generation of an equilibrated system requires numerical form finding methods, namely the force density method for truss structures. To enforce geometric restrictions, a constrained force density method is developed. Then, the scope of the form finding method is extended to the search of optimal configurations by combining the force density method with multiobjective genetic algorithms within an integrated design process. Large scale applications illustrate the proposed strategy. [ABSTRACT FROM AUTHOR]

The article investigates the through-thickness variations of the crystallographic texture using the real-space and the Laplace-space methods. In utilizing the real-space method, the depth-resolution was achieved by a decoupled z translation of the sample relative to the gauge volume allowing a direct allocation of the measured diffraction signal. On the other hand, the Laplace-space method was used for the measurement of the texture depth distribution by the comparison of higher-order reflections.

El tiburón de profundidad Etmopterus bigelowi se distribuye globalmente en aguas templadas y tropicales; sin embargo, hay poca información disponible sobre su biología ya que raramente se captura y existe confusión taxonómica con su especie hermana Etmopterus pusillus. Los ejemplares utilizados en este trabajo se obtuvieron de julio a diciembre de 2004 como captura incidental de la pesca comercial de arrastre de aguas profundas dirigida al camarón rojo Aristaeomorpha foliacea en el Atlántico sudoccidental. Se examinaron 55 ejemplares (22 machos y 33 hembras) de 31.5 a 73 cm de longitud total (LT) y de 103 a 1600 g de peso total. Se analizó la relación peso-talla para ambos sexos, observándose diferencias significativas en las pendientes de las regresiones, tanto de hembras como de machos. La talla de madurez para cada sexo se evaluó ajustando una regresión logística. La talla de primera madurez de las hembras (56.0 cm LT) fue mayor que la de los machos (45.1 cm LT). El presente trabajo aporta información preliminar esencial sobre E. bigelowi que puede ser incorporada en modelos de evaluación de riesgo y evaluación de la población, cruciales para prácticas de gestión dirigidas a evitar la sobreexplotación de estos vulnerables tiburones de aguas profundas. [ABSTRACT FROM AUTHOR]

The blurred lantern shark Etmopterus bigelowi, a deep-water squaloid shark, is globally widespread in temperate and tropical waters, but there is little available information about its biology owing to its relative rarity of capture and taxonomic confusion with its sibling species Etmopterus pusillus. Specimens used in this study were collected from July to December 2004 as by-catch in the commercial deepwater trawl fishery targeting red shrimp Aristaeomorpha foliacea in the southwestern Atlantic. We examined 55 specimens (22 males and 33 females) ranging in total length (TL) from 31.5 to 73 cm and in total weight from 103 to 1600 g. Length-weight relationships were explored for each sex and significant differences were found in the slope coefficients of the male and female regressions. The size at maturity for each sex was evaluated fitting a logistic regression. Females matured at larger sizes than males, with estimated sizes at first maturity of 56.0 cm TL for females and 45.1 cm TL for males. The present study provides important preliminary information about E. bigelowi that can be incorporated in risk assessment and stock assessment models, essential for efficient management practices aimed at avoiding overexploitation of these vulnerable deep-sea sharks. [ABSTRACT FROM AUTHOR]

Abstract: The Integrated Tokamak Modelling Task Force (ITM-TF) is developing an infrastructure where the validation needs, as being formulated in terms of multi-device data access and detailed physics comparisons aiming for inclusion of synthetic diagnostics in the simulation chain, are key components. As the activity and the modelling tools are aimed for general use, although focused on ITER plasmas, a device independent approach to data transport and a standardized approach to data management (data structures, naming, and access) is being developed in order to allow cross-validation between different fusion devices using a single toolset. Extensive work has already gone into, and is continuing to go into, the development of standardized descriptions of the data (Consistent Physical Objects). The longer term aim is a complete simulation platform which is expected to last and be extended in different ways for the coming 30 years. The technical underpinning is therefore of vital importance. In particular the platform needs to be extensible and open-ended to be able to take full advantage of not only today''s most advanced technologies but also be able to marshal future developments. As a full level comprehensive prediction of ITER physics rapidly becomes expensive in terms of computing resources, the simulation framework needs to be able to use both grid and HPC computing facilities. Hence data access and code coupling technologies are required to be available for a heterogeneous, possibly distributed, environment. The developments in this area are pursued in a separate project—EUFORIA (EU Fusion for ITER Applications) which is providing about 15 professional person year (ppy) per annum from 14 different institutes. The range and size of the activity is not only technically challenging but is providing some unique management challenges in that a large and geographically distributed team (a truly pan-European set of researchers) need to be coordinated on a fairly detailed project level. The 2009 Work programme of ITM-TF organizes 240 individuals from 24 different associations providing about 60ppy in total. Remote participation and collaborative tools and facilities as the ENEA sponsored Gateway have proven indispensible to meet this challenge.The current status of ITM-TF and EUFORIA is presented and discussed. [Copyright &y& Elsevier]

Routine studies are performed on JET using a new set of antennas to excite Toroidal Alfvén Eigenmodes (TAE). A TAE resonance footprint is observed in the plasma response measurement when there is a noticeable variation in both the amplitude and the phase of the response with respect to the excitation. An algorithm for real-time identification of TAE resonances, based on a hardware lock-in amplifier, is presently used at the Joint European Torus (JET) tokamak for detecting such variations. In this paper, we revisit the problem of estimating the I-Q characteristics from a known non-stationary frequency mode, with a resonant- like phase response, embedded in a digital signal. A non-stationary linear model is used in a recursive filter implementation of a lock-in amplifier. We propose it as a viable alternative to hardware synchronous detectors such as the one in use at the JET and compare its' performance with standard digital lock-in techniques in terms of bandwidth and phase response under high throughput rates requirements. [ABSTRACT FROM AUTHOR]

A novel technique for the real-time measurement of the magnetic field pitch angle in JET discharges using the motional Stark effect diagnostic is presented. Kalman filtering techniques are adopted to estimate the amplitude of the avalanche photodiode signals’ harmonics that are relevant for the pitch angle calculation. The proposed technique {for extended technical details of the generic algorithm see [R. Coelho and D. Alves, IEEE Trans. Plasma Sci. 37, 164 (2009)]} is shown to be much more robust and provides less noisy estimates than an equivalent lock-in amplifier scheme, in particular when dealing with edge localized modes. [ABSTRACT FROM AUTHOR]

The prospects for the real-time amplitude estimation of selected harmonic components of quasi-periodic signals from a motional Stark effect (MSE) tokamak plasma diagnostic is addressed using Kalman filtering techniques. The proposed method is shown to be more competitive than a standard low-pass filter lock-in amplifier scheme. In particular, when block data processing is limited to a small number of samples signal harmonics are narrowly separated in frequency or in the presence of frequency jitter, the superior competencies of the Kalman filtering method are evidenced. [ABSTRACT FROM AUTHOR]

In this paper, the population biology of the velvet belly lanternshark Etmopterus spinax was studied and life-history coefficients determined. Age was estimated from sections of the second dorsal spine and validated by marginal increment analysis. Males attained a maximum age of 8 years while 11 year-old females were found. Several growth models were fitted and compared for both size-at-age and mass-at-age data, showing that even though this is a small-sized species, it has a relatively slow growth rate. This species matures late, specifically at 49·6 and 42·5% of the maximum observed ages for males and females, respectively. It has a low fecundity, with a mean ovarian fecundity of 9·94 oocytes and a mean uterine fecundity of 7·59 embryos per reproductive cycle. This species seems to have a long reproductive cycle, and even though no conclusive data were obtained, a 2–3 year cycle is possible. The estimated coefficients indicate that this species has a vulnerable life cycle, typical of deepwater squalid sharks. Given the high fishing pressures that it is suffering in the north-east Atlantic, this fish may already be facing severe declines or in risk of facing them in the near future. [ABSTRACT FROM AUTHOR]

The successful control of a fusion plasma discharge relies on the continuous improvement of existing diagnostics and on the development of new ones based on innovative concepts. It is equally important to provide efficient numerical tools capable of extracting, in real time, the most important physical quantities emerging from the collected data. This encompasses, for instance, the determination of the wavenumber and amplitude tracking of plasma instabilities, a necessary ingredient for establishing in real time the type of feedback control stabilization scheme to be used. In this paper, the characterization of the wavenumber spectra of unstable modes observed in ISTTOK plasma discharges is addressed using a set of two poloidal arrays of magnetic coils (Mirnov coils). In particular, the prospect for the estimation of the poloidal wavenumber in real time using recursive filtering techniques is investigated. It is shown that, in contrast with typical cross-spectrum analysis, where a large dataset is required to estimate the wavenumbers, with this innovative technique, the wavenumber spectra may be obtained in faster time scales. [ABSTRACT FROM AUTHOR]

In this work, the nonlinear growth of the classical tearing mode is revisited, using reduced magnetohydrodynamic numerical simulations in cylindrical geometry, emphasizing the limiting scenario of a marginally unstable mode, i.e., 0∼Δ′a<4, where a is the minor radius and Δ′ is the stability parameter [H. Furth, J. Killeen, and M. N. Rosenbluth, Phys. Fluids 6, 459 (1963)]. Conventionally, the mode becomes unstable when Δ′>0 and, eventually, a steady state island width (saturated island width) is achieved. It is found that, contrary to theoretical predictions, no steady state solution is obtained for typically low temperature plasmas with perpendicular viscosity and magnetic Reynolds number below a certain threshold. Plasma inertial forces are identified as the physical mechanism behind such nonlinear evolution. [ABSTRACT FROM AUTHOR]

Asphaltenes are components of crude oil, and their average chemical structures are characterized with difficulty. This study shows that simple Fourier transform infrared (FTIR) analysis spectroscopy could be adapted to the determination of aromatic hydrogens in asphaltenes and resins and elucidation of their average molecules. The work demonstrates the existence of a linear correlation in the infrared (IR) intensities of the symmetric and asymmetric aromatic hydrogens in methyl substituted arenes, in the 2,900 to 3,100 cm-1 region and of the out-of-plane deformation in the 700 to 900 cm-1 region. [ABSTRACT FROM AUTHOR]

The effect of sheared equilibrium plasma rotation on the stability of tearing modes in an Ohmic (low plasma β) regime is investigated. It is found, by means of numerical MHD simulations in a cylindrical geometry, that plasma rotation in the equivalent toroidal direction can result either in the increase or in the decrease of the instability growth rate. Perpendicular plasma viscosity and plasma rotation shear at the modes’ rational surface play a key role on assessing the effect of shear flow. While destabilizing for low viscosity plasmas (ratio of the resistive to viscous diffusion time scales τR/τV<1), for viscous plasmas (τR/τV>1) shear flow reduces the growth rate. Above a given threshold in the rotation shear (that depends on the ratio τR/τV) a tearing mode, unstable in the absence of rotation, can be stabilized. The effect of sheared toroidal flow on mode stability, in both viscosity regimes that are considered in the paper, is qualitatively independent of the aspect ratio. [ABSTRACT FROM AUTHOR]

Abstract: Using a portfolio of stocks from the London Stock Exchange FTSE100 index (FTSE), we study both the time dependence of their correlations and the normalized tree length of the associated minimal spanning tree (MST). The first four moments of the distribution of correlations and lengths of the tree are examined in detail and differences in behavior noted. For different economic groups and industries, clustering is evident. However, comparing the classification used prior to 2006 with that introduced in January 2006 it is clear that the new classification, apart from one or two notable exceptions, is much more compatible with the clustering obtained by the MST analysis. We finally compare the MST for real data with that obtained for a synthetic random market. The latter tree would seem more like the structure found by Coronnello et al. for trees based on high-frequency data. [Copyright &y& Elsevier]

The understanding of the nature, driving mechanisms, and dynamics of turbulence activity in tokamak plasmas is a major challenge in fusion research. In the ISTTOK tokamak, edge turbulence activity has been extensively studied using both limiter and electrode biasing to induce local sheared electric fields, thus affecting turbulence and consequently particle confinement. Due to the fast time scales involved plasmas (pulse length of 30 ms and particle confinement of the order of 0.3 ms) and the turbulent nature of ISTTOK plasmas, not only turbulence but also magnetohydrodynamic (MHD) activity occurs at rapid bursts. Therefore, resolving the modes both spatially and during time (in particular, regarding the energy/frequency spectrum) requires advanced time-frequency analysis tools, capable of tracking short lasting (0.1 ms) MHD modes. In this article, we explore the capabilities of the empirical mode decomposition method as a tool for turbulence and MHD instability analysis. The time evolution of the energy content associated with fluctuating potential, edge plasma density (obtained from Langmuir probes), and perturbed magnetic fields (Mirnov coil signals) is obtained, and a comparison is made with other advanced time-frequency signal estimators. [ABSTRACT FROM AUTHOR]

This paper deals with the theoretical-experimental study of heat conduction in hardened materials for the production of molds and dies using high speed cutting. The employed materials were the AISI P20 and AISI D2 steels, being the tests carried out with (TiAl)N coated ball nose in a work piece with the shape of a ¼ tube with 28 mm diameter and 100 mm length. This investigation demonstrates the variation of temperature as a function of different cooling systems, that is, compressed air and compressed cold air. Possible geometric deformation of the machined surfaces due to these variations in temperature for distinct cooling systems was also evaluated. [ABSTRACT FROM AUTHOR]

The quintessential property of neuronal systems is their intensive patterns of selective synaptic connections. The current work describes a physics-based approach to neuronal shape modeling and synthesis and its consideration for the simulation of neuronal development and the formation of neuronal communities. Starting from images of real neurons, geometrical measurements are obtained and used to construct probabilistic models which can be subsequently sampled in order to produce morphologically realistic neuronal cells. Such cells are progressively grown while monitoring their connections along time, which are analysed in terms of percolation concepts. However, unlike traditional percolation, the critical point is verified along the growth stages, not the density of cells, which remains constant throughout the neuronal growth dynamics. It is shown, through simulations, that growing beta cells tend to reach percolation sooner than the alpha counterparts with the same diameter. Also, the percolation becomes more abrupt for higher densities of cells, being markedly sharper for the beta cells. In the addition to the importance of the reported concepts and methods to computational neuroscience, the possibility of reaching percolation through morphological growth of a fixed number of objects represents in itself a novel paradigm of great theoretical and practical interest for the areas of statistical physics and critical phenomena. [ABSTRACT FROM AUTHOR]

The physico-chemical behavior of asphaltene is very useful to assist prediction and control the mechanisms of asphaltene deposition during the production of petroleum fluids. It has been realized that the first step in the formation of precipitated asphaltene particles is the self-aggregation mechanism to form colloidal particles or pseudo-micelles in several solvents. In this work, the critical micelle concentration (CMC) of two asphaltene fractions extracted from vacuum residues (VR) were obtained by surface tension measurements, using aromatic solvents. The molecular weight (1094-565 g/mol), calculated from average radii of the asphaltene molecules adsorbed at the air–solvent interface, are also in agreement with the values for small aggregates reported using small angle X-ray scattering. [ABSTRACT FROM AUTHOR]

The response of generic metastable tearing modes (of which neoclassical tearing modes-NTMs- are a particular example) to resonant external magnetic fields, in rotating tokamak fusion plasmas, is analyzed. In particular, the problem of the bifurcation process that may arise during the driven destabilization of the mode by the external fields is addressed. The results presented provide a clear picture of both the mode amplitude and frequency dynamics in a scenario where there is a differential rotation between the rotating plasma and the external fields. It is shown that the mode frequency exhibits a highly oscillatory behavior during the bifurcation process (owing to the differential rotation) and not a smooth transition between the driving frequency and natural mode rotation. On such grounds, the interpretation of experimental results where magnetic coupling is thought to play a role on the destabilization of some NTMs is revised. [ABSTRACT FROM AUTHOR]

In the design of mechanical structures, the evolutionary algorithms have taken a more and more important place, mostly because of their ability to explore widely the design space. Furthermore, as several objectives are often pursued simultaneously in industrial applications, multiobjective optimization has become a wide area of research in recent years. However, only a few methods integrate a multicriteria decision aid approach to reflect the user’s preferences since the beginning of the search process. In this paper, PROMETHEE II, an outranking method developed in the operational research field, has been implemented in an evolutionary algorithm. Furthermore, as the handling of the constraints is very critical, an original technique called PAMUC (Preferences Applied to MUltiobjectivity and Constraints) is proposed to tackle simultaneously the constrained and multiobjective aspects. It has been validated on standard test cases, and applied to the design optimization of two valves of the Vinci engine (from launcher Ariane 5). Results analyzed thanks to the R1 norm introduced by Hansen and Jaszkiewicz show that PAMUC outperforms the classical weighted-sum method (combined with a dynamic penalty-based technique to handle the constraints), and therefore seem to be more appropriate to reflect the user’s preferences. [Copyright &y& Elsevier]

Purpose: Depressive disorders (DD) in adolescence are often misdiagnosed and under-recognised. A major clinical problem regards the high rate of co-morbidity with other disorders, namely substance abuse. The aim of this study was to assess the discriminative power of the Beck Depression Inventory II (BDI-II) to characterise specific social–demographic variables related to DD in adolescence. Methods: A Portuguese version of the BDI-II and a social–demographic questionnaire were administered to 775 Portuguese adolescents (312 males, 463 females; mean age: 16.9 years); 83 adolescents performed a clinical interview following DSM-IV criteria. Results: Mean BDI-II Portuguese version (BDI-II-P) total score was 10.31 (standard deviation: 8.4), with females reporting more depressive symptoms than males (P < 0.001). Low academic achievement, sleep disturbances, and alcohol consumption were consistently associated with depressive symptoms for both genders. Higher tobacco consumption was significantly associated with depressive symptoms in females. Familial factors did not appear to be associated with depressive symptoms in males. However, a higher frequency of siblings, having separated parents as well as a more extreme perception of the mother’s educational style were consistently associated with depressive symptoms in females. Conclusion: The BDI-II-P showed discriminative power to characterise social–demographic variables related to DD especially in adolescent females. [Copyright &y& Elsevier]

Presents a study which proposed a technique which uses scanning electron microscope to study the electrical properties of insulators. Limitation of the validity of conventional techniques in measuring the electric properties of insulators; Discussion of the standard techniques; Details of the technique using the electrostatic mirror.

The article presents a case study of a 67-year-old man with a 6-month history of a small painless lump on the right side of his abdomen. Histological examination revealed a degenerate worm in the subcutaneous tissue which is surrounded by a foreign-body giant cell reaction with a palisade of epithelioid histiocytes. It notes that the patient was diagnosed with subcutaneous dirofilariasis which is a nodule located on the head or arms.

Presents an analytical derivations of the 1/radius of curvature (R(V)) function for a charged segment perpendicular to the sample surface and for a charged disc parallel to that surface. Curve for particular charge distributions; Application to the charged segment; Analysis of the experimental results; Proper account of the image charge in the substrate.

Describes a case of induced inhomogeneities, which were induced in slightly conductive materials. Information on inhomogeneous under stress; When charge density builds up.

A design for a low-frequency 1/f optical noise generator using fractional statistics is proposed and demonstrated for the first time. The 1/f noise samples were obtained by transformation functions performed on pseudorandom binary sequences that modulate a laser source. The 1/f spectrum representation of the optical noise samples shows that this proposition is very promising for the investigation of this noise effect in optical devices and system reliability. It can also be useful for the spectral distribution measurements of ultra-narrow linewidth lasers. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction: Neurodevelopmental disorders such as Autism Spectrum Disorder (ASD) and Attention Deficit Hyperactivity Disorder (ADHD) are lifelong conditions which have undergone huge diagnostic and therapeutic evolutions in the past decades. Although there seems to be consensus regarding therapeutic interventions in ADHD targeting dopaminergic and noradrenergic deficits in this disorder, the aetiology of the disorder seems far more complex, and in the case of ASD specific therapeutic target are still elusive to date. Concerns about adverse effects and interactions of multiple pharmacotherapy have boosted research on treatment strategies as nutritional supplements, but their advantages remain controversial. Objectives: The present study aimed to investigate nutritional status in Portuguese children diagnosed with ASD and ADHD (n=91). Methods: Clinical evaluation included the Autism Diagnostic Observation Schedule (ADOS-2) and Autism Diagnostic Interview-Revised (ADI-R) and formal cognitive evaluation scales was performed in all the children, and patients on special diets, with metabolic disorders or with known vitamin deficiencies were excluded. Results: An association between subclinical nutritional deficits and both Autism Spectrum Disorders and Attention Deficit Hyperactivity Disorder was detected. Conclusions: With the present work, the authors aim to enlighten the role for PUFA's, iodine, zinc, selenium, iron and magnesium in neurodevelopment as distinct factors in the clinical presentation of both disorders. The relationship between nutritional status and ROS in the pathophysiology of ASD and ADHD is explored. [ABSTRACT FROM AUTHOR]