23,262 research outputs found
Does p40-targeted therapy represent a significant evolution in the management of plaque psoriasis?
No full textL'articolo è un articolo di revisione che discute le differenze di efficacia e di sicurazza dei farmaci anti-TNF e anti p40 nella terapia della psoriasi grav
Risk Analysis for Autonomous Underwater Vehicle Operations in Extreme Environments
No full textAutonomous underwater vehicles (AUVs) are used increasingly to explore hazardous marine environments. Risk assessment for such complex systems is based on subjective judgment and expert knowledge as much as on hard statistics. Here, we describe the use of a risk management process tailored to AUV operations, the implementation of which requires the elicitation of expert judgment. We conducted a formal judgment elicitation process where eight world experts in AUV design and operation were asked to assign a probability of AUV loss given the emergence of each fault or incident from the vehicle's life history of 63 faults and incidents. After discussing methods of aggregation and analysis, we show how the aggregated risk estimates obtained from the expert judgments were used to create a risk model. To estimate AUV survival with mission distance, we adopted a statistical survival function based on the nonparametric Kaplan-Meier estimator. We present theoretical formulations for the estimator, its variance, and confidence limits. We also present a numerical example where the approach is applied to estimate the probability that the Autosub3 AUV would survive a set of missions under Pine Island Glacier, Antarctica in January–March 2009
CE Challenges: Work to Do
No full textCE has been used for more than two decades now. Despite many successes and advantages, there are still many challenges to be addressed. These challenges are both technical and organisational. In the paper we will address the current challenges of CE. Many challenges are related to the exchange of data and knowledge and to the systems that make data and knowledge exchange possible. Although much progress has been made in enabling extensive data and knowledge exchange and use, much remains to be wished. For example, there are still barriers to data exchange. Technically, these barriers may consist of different formats, differences in infrastructures and systems, and different semantics. There are also organisational and political barriers. For example, investment in information system may heavily impact upstream suppliers, while revenues of better information exchange may predominantly be gained by downstream actors. Without sharing costs and revenues, chain-wide information exchange will not be easily realised. Another barrier is the possible lack of willingness to share information, because of potential misuse of knowledge and loss of power. The paper is organised as follows. First we will describe the current manifestation of CE as described in a recent book. Second, we will list current trends in CE. Third, we will present some Critical Success Factors (CSFs) that are considered relevant for implementing and adapting CE practices. Last, we indicate some research and practical questions to be addressed, especially for areas that have a high potential and actual impact. </p
Synthesis optimization and charge carrier transfer mechanism in LiLuSiO<sub>4</sub>:Ce, Tm storage phosphor
No full textLiLuSiO4:Ce and LiLuSiO4:Ce, Tm show very efficient charge carrier storage properties upon beta irradiation after samples have received treatment in vacuum. They outperform the commercial storage phosphor BaFBr(I):Eu2+ in many aspects. The influence of the synthesis conditions, Ce and Tm concentration, nonstoichiometry and codoping with Ca, Hf, Al and Ge are reported. Based on the results of the synthesis optimization, thermoluminescence (TL) emission and TL excitation spectra a mechanism of charge carrier transfer, storage, and recombination during irradiation and thermal or optical readout is proposed.Accepted Author ManuscriptRST/Fundamental Aspects of Materials and EnergyRST/Luminescence Material
Hauteurs de Griffiths-Kato des pinceaux de variétés projectives
No full textThe Griffiths height of a variation of Hodge structures over a projective curve is defined as the degree of its canonical line bundle, as defined by Griffiths and generalized by Peters to allow bad reduction points. It may be seen as a geometric analog of the Kato height attached to pure motives over number fields. In this paper, we establish various formulas expressing the Griffiths height of the middle-dimensional cohomology of a pencil of projective complex hypersurfaces in terms of characteristic classes. Firstly, using Steenbrink's theory and the Grothendieck-Riemann-Roch theorem, we give an expression in terms of characteristic classes of the alternating sum of the Griffiths heights of the cohomology groups of the fibers of a pencil of projective varieties with non-singular total space, whose singular fibers are divisors with normal crossings. Using this expression, we may compute the same alternating sum of Griffiths heights associated to a pencil of projective varieties with non-singular total space and only ordinary double points as singularities of its fibers. By using the weak Lefschetz theorem and the above formulas, we may express the Griffiths height of the middle-dimensional cohomology of an ample pencil of hypersurfaces in a smooth pencil in terms of characteristic classes and of the Griffiths heights associated to the ambient smooth pencil. This leads to closed formulas for the Griffiths height of the middle-dimensional cohomology of pencils of projective varieties in the following special cases: for pencils of hypersurfaces in a projective bundle, and for linear pencils of hypersurfaces in a smooth projective variety, of which Lefschetz pencils are a special instance. Finally, as an appendix, we establish transversality results which show that the hypotheses on the pencils of hypersurfaces under which some of our formulas for Griffiths heights hold (namely, that the pencils admit smooth total spaces and singular fibers with only ordinary double points), are generically satisfied.On définit la hauteur de Griffiths d'une variation de structures de Hodge sur une courbe projective comme le degré de son fibré en droites canonique, tel qu'il est défini par Griffiths et généralisé par Peters afin de permettre des points de mauvaise réduction. On peut voir cette hauteur comme un analogue géométrique de la hauteur de Kato attachée aux motifs purs sur des corps de nombres. Dans ce mémoire, nous établissons diverses formules exprimant la hauteur de Griffiths de la cohomologie en dimension moitié d'un pinceau d'hypersurfaces projectives complexes en termes de classes caractéristiques. En premier lieu, à l'aide de la théorie de Steenbrink et du théorème de Grothendieck-Riemann-Roch, nous exprimons en termes de classes caractéristiques la somme alternée des hauteurs de Griffiths des groupes de cohomologie des fibres d'un pinceau de variétés projectives, avec un espace total non singulier, et dont les fibres singulières sont des diviseurs à croisements normaux. Cette expression nous permet de calculer la même somme alternée des hauteurs de Griffiths associées à un pinceau de variétés projectives, avec un espace total non singulier, et dont les seules singularités des fibres sont des points doubles ordinaires. À l'aide du théorème de Lefschetz faible et des formules ainsi établies, nous exprimons ensuite la hauteur de Griffiths de la cohomologie en dimension moitié d'un pinceau ample d'hypersurfaces dans un pinceau lisse en termes de classes caractéristiques et des hauteurs de Griffiths associées au pinceau lisse ambiant. Cela mène à des formules explicites pour la hauteur de Griffiths de la cohomologie en dimension moitié de pinceaux de variétés projectives dans les cas particuliers suivants : celui des pinceaux d'hypersurfaces dans un fibré en projectifs, et celui des pinceaux linéaires d'hypersurfaces dans une variété projective lisse — dont les pinceaux de Lefschetz sont un exemple. Enfin, en annexe, nous établissons des résultats de transversalité qui montrent que les hypothèses sur les pinceaux d'hypersurfaces pour lesquelles sont établies plusieurs de nos formules pour les hauteurs de Griffiths — admettre un espace total lisse et des fibres singulières à points doubles ordinaires — sont satisfaites de manière générique
Hauteurs de Griffiths-Kato des pinceaux de variétés projectives
No full textOn définit la hauteur de Griffiths d'une variation de structures de Hodge sur une courbe projective comme le degré de son fibré en droites canonique, tel qu'il est défini par Griffiths et généralisé par Peters afin de permettre des points de mauvaise réduction. On peut voir cette hauteur comme un analogue géométrique de la hauteur de Kato attachée aux motifs purs sur des corps de nombres. Dans ce mémoire, nous établissons diverses formules exprimant la hauteur de Griffiths de la cohomologie en dimension moitié d'un pinceau d'hypersurfaces projectives complexes en termes de classes caractéristiques. En premier lieu, à l'aide de la théorie de Steenbrink et du théorème de Grothendieck-Riemann-Roch, nous exprimons en termes de classes caractéristiques la somme alternée des hauteurs de Griffiths des groupes de cohomologie des fibres d'un pinceau de variétés projectives, avec un espace total non singulier, et dont les fibres singulières sont des diviseurs à croisements normaux. Cette expression nous permet de calculer la même somme alternée des hauteurs de Griffiths associées à un pinceau de variétés projectives, avec un espace total non singulier, et dont les seules singularités des fibres sont des points doubles ordinaires. À l'aide du théorème de Lefschetz faible et des formules ainsi établies, nous exprimons ensuite la hauteur de Griffiths de la cohomologie en dimension moitié d'un pinceau ample d'hypersurfaces dans un pinceau lisse en termes de classes caractéristiques et des hauteurs de Griffiths associées au pinceau lisse ambiant. Cela mène à des formules explicites pour la hauteur de Griffiths de la cohomologie en dimension moitié de pinceaux de variétés projectives dans les cas particuliers suivants : celui des pinceaux d'hypersurfaces dans un fibré en projectifs, et celui des pinceaux linéaires d'hypersurfaces dans une variété projective lisse — dont les pinceaux de Lefschetz sont un exemple. Enfin, en annexe, nous établissons des résultats de transversalité qui montrent que les hypothèses sur les pinceaux d'hypersurfaces pour lesquelles sont établies plusieurs de nos formules pour les hauteurs de Griffiths — admettre un espace total lisse et des fibres singulières à points doubles ordinaires — sont satisfaites de manière générique.The Griffiths height of a variation of Hodge structures over a projective curve is defined as the degree of its canonical line bundle, as defined by Griffiths and generalized by Peters to allow bad reduction points. It may be seen as a geometric analog of the Kato height attached to pure motives over number fields. In this paper, we establish various formulas expressing the Griffiths height of the middle-dimensional cohomology of a pencil of projective complex hypersurfaces in terms of characteristic classes. Firstly, using Steenbrink's theory and the Grothendieck-Riemann-Roch theorem, we give an expression in terms of characteristic classes of the alternating sum of the Griffiths heights of the cohomology groups of the fibers of a pencil of projective varieties with non-singular total space, whose singular fibers are divisors with normal crossings. Using this expression, we may compute the same alternating sum of Griffiths heights associated to a pencil of projective varieties with non-singular total space and only ordinary double points as singularities of its fibers. By using the weak Lefschetz theorem and the above formulas, we may express the Griffiths height of the middle-dimensional cohomology of an ample pencil of hypersurfaces in a smooth pencil in terms of characteristic classes and of the Griffiths heights associated to the ambient smooth pencil. This leads to closed formulas for the Griffiths height of the middle-dimensional cohomology of pencils of projective varieties in the following special cases: for pencils of hypersurfaces in a projective bundle, and for linear pencils of hypersurfaces in a smooth projective variety, of which Lefschetz pencils are a special instance. Finally, as an appendix, we establish transversality results which show that the hypotheses on the pencils of hypersurfaces under which some of our formulas for Griffiths heights hold (namely, that the pencils admit smooth total spaces and singular fibers with only ordinary double points), are generically satisfied
Design of indicators for measuring product performance in the circular economy
No full textThis paper explores measurement of product performance with respect to circular economy (CE) principles.
Potential indicators are assessed with special attention given to questions such as: the variables that should
be measured; how these variables should be assessed; and in which format they should be presented.
The resulting considerations are used to develop a prototype whose design is informed through feedback
from CE experts. The prototype uses a points-based questionnaire which converges into a simple final
result with minimum and maximum limits. The selected approach is critically appraised, and its utility
for decision-making discussed. The prototype is tested against a product in the chemical processing
industry. The strengths include: ease of use; simplicity; speed; and an effective metaphor for the diffusion
of CE principles. The limitations include: the opaque and potentially misleading nature of a single metric;
superficial engagement with decision-making; and the reliance on context-specific assumptions. Future
developments could include refining the approach to encourage deeper reflection, and generalisation of
the approach to different industry sectors or sustainability frameworks
Towards the Green-Griffiths-Lang conjecture
No full textversion 2 has been expanded and improved (15 pages)International audienceThe Green-Griffiths-Lang conjecture stipulates that for every projective variety X of general type over C, there exists a proper algebraic subvariety of X containing all non constant entire curves f : C → X. Using the formalism of directed varieties, we prove here that this assertion holds true in case X satisfies a strong general type condition that is related to a certain jet-semistability property of the tangent bundle TX . We then give a sufficient criterion for the Kobayashi hyperbolicity of an arbitrary directed variety (X,V). This work is dedicated to the memory of Professor Salah Baouendi.La conjecture de Green-Griffiths-Lang stipule que pour toute variété projective X de type général sur C, il existe une sous-variété algébrique propre de X contenant toutes les courbes entières non constantes f: C → X. En utilisant le formalisme des variétés dirigées, nous prouvons ici que cette affirmation est vraie dans le cas où X est de type général et satisfait une condition additionnelle liée à une certaine propriété de semi-stabilité au sens des jets du fibré tangent TX. Nous donnons ensuite un critère suffisant garantissant l'hyperbolicité au sens de Kobayashi d'une variété dirigée arbitraire (X,V). Ce travail est dédié à la mémoire du professeur Salah Baouendi
Signature of quantum Griffiths singularity state in a layered quasi-one-dimensional superconductor
No full textQuantum Griffiths singularity was theoretically proposed to interpret the phenomenon of divergent dynamical exponent in quantum phase transitions. It has been discovered experimentally in three-dimensional (3D) magnetic metal systems and two-dimensional (2D) superconductors. But, whether this state exists in lower dimensional systems remains elusive. Here, we report the signature of quantum Griffiths singularity state in quasi-one-dimensional (1D) TaPdS nanowires. The superconducting critical field shows a strong anisotropic behavior and a violation of the Pauli limit in a parallel magnetic field configuration. Current-voltage measurements exhibit hysteresis loops and a series of multiple voltage steps in transition to the normal state, indicating a quasi-1D nature of the superconductivity. Surprisingly, the nanowire undergoes a superconductor-metal transition when the magnetic field increases. Upon approaching the zero-temperature quantum critical point, the system uncovers the signature of the quantum Griffiths singularity state arising from enhanced quenched disorders, where the dynamical critical exponent becomes diverging rather than being constant
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