91 research outputs found
Radiation Induced by Charged Particles in Optical Fibers
International audienceThe field of a charged particle passing through or near an optical fiber polarizes the fiber atoms transiently. This produces a particle-induced guided light (PIGL). PIGL can also be assisted by a metallic object stuck to the fiber, via plasmon excitation. Type-I PIGL is produced in a translation-invariant part of the fiber, type-II PIGL is produced at a fiber end, an indentation or a metallic object. Properties of type-I PIGL in a single-mode fiber (spectrum, polarization) are reviewed. Order of magnitudes are given for type-II PIGL from a fiber end or a metallic ball. Interference effects are outlined, in particular the guided Smith-Purcell radiation. Applications of PIGL to beam diagnostics are discussed
On the distribution of Iwasawa invariants associated to multigraphs
Let be a prime number. The Iwasawa theory of multigraphs is the
systematic study of growth patterns in the number of spanning trees in abelian
-towers of multigraphs. In this context, growth patterns are realized by
certain analogues of Iwasawa invariants, which depend on the prime and
the abelian -tower of multigraphs. We formulate and study statistical
questions about the behaviour of the Iwasawa and invariants
Sequencing the genome of the Burmese python (Python molurus bivittatus) as a model for studying extreme adaptations in snakes
The Consortium for Snake Genomics is in the process of sequencing the genome and creating transcriptomic resources for the Burmese python. Here, we describe how this will be done, what analyses this work will include, and provide a timeline
Semi-Public Competitions *
Abstract The process of innovation is driven by two main factors: new inventions and institutions supporting the transformation of inventions into marketable innovations. This paper proposes a new institution, called a semi-public competition, that has been neglected by the economic literature but exists frequently in practice. I show how semi-public competitions can mitigate a dilemma that arises at an early stage of innovative activity and specify the conditions under which a semi-public competition can increase welfare. The results suggest that governments promote knowledge about the semi-public competition mechanism but refrain from direct public funding of competitions
Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences
The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & NemĂ©sio 2007; Donegan 2008, 2009; NemĂ©sio 2009aâb; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported
by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on
18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based
researchers who signed it in the short time span from 20 September to 6 October 2016
The IDENTIFY study: the investigation and detection of urological neoplasia in patients referred with suspected urinary tract cancer - a multicentre observational study
Objective
To evaluate the contemporary prevalence of urinary tract cancer (bladder cancer, upper tract urothelial cancer [UTUC] and renal cancer) in patients referred to secondary care with haematuria, adjusted for established patient risk markers and geographical variation.
Patients and Methods
This was an international multicentre prospective observational study. We included patients aged â„16 years, referred to secondary care with suspected urinary tract cancer. Patients with a known or previous urological malignancy were excluded. We estimated the prevalence of bladder cancer, UTUC, renal cancer and prostate cancer; stratified by age, type of haematuria, sex, and smoking. We used a multivariable mixed-effects logistic regression to adjust cancer prevalence for age, type of haematuria, sex, smoking, hospitals, and countries.
Results
Of the 11 059 patients assessed for eligibility, 10 896 were included from 110 hospitals across 26 countries. The overall adjusted cancer prevalence (n = 2257) was 28.2% (95% confidence interval [CI] 22.3â34.1), bladder cancer (n = 1951) 24.7% (95% CI 19.1â30.2), UTUC (n = 128) 1.14% (95% CI 0.77â1.52), renal cancer (n = 107) 1.05% (95% CI 0.80â1.29), and prostate cancer (n = 124) 1.75% (95% CI 1.32â2.18). The odds ratios for patient risk markers in the model for all cancers were: age 1.04 (95% CI 1.03â1.05; P < 0.001), visible haematuria 3.47 (95% CI 2.90â4.15; P < 0.001), male sex 1.30 (95% CI 1.14â1.50; P < 0.001), and smoking 2.70 (95% CI 2.30â3.18; P < 0.001).
Conclusions
A better understanding of cancer prevalence across an international population is required to inform clinical guidelines. We are the first to report urinary tract cancer prevalence across an international population in patients referred to secondary care, adjusted for patient risk markers and geographical variation. Bladder cancer was the most prevalent disease. Visible haematuria was the strongest predictor for urinary tract cancer
La radioactivitĂ©, câest naturel !
Notre monde est nĂ© de la fusion nuclĂ©aire. Lâhomme et les ĂȘtres vivants sont donc exposĂ©s Ă la radioactivitĂ© qui en rĂ©sulte. Retour sur un phĂ©nomĂšne de la physique qui nâa rien de mystĂ©rieux
Amélioration du comportement cinématique des machines par l'optimisation des trajets d'usinage 5 axes
Le couplage précision-vitesse est une problématique importante de l'usinage à 5 axes. Le respect de la précision impose à la machine de ralentir. De plus, le calcul du trajet ne prend pas en compte le comportement de la machine et induit aussi des ralentissements. Ces travaux de thÚse visent deux objectifs : Optimiser le comportement de la machine outil en modifiant l'orientation de l'axe outil dans le repÚre machine ; Garantir le respect des contraintes géométriques fonctionnelles sur l'orientation de l'axe outil. Une méthode d'optimisation sous contrainte est proposée. La fonction objectif utilise un modÚle simplifié du comportement de la machine. Le concept du Domaine d'Orientation Admissible est alors défini pour contraindre l'orientation de l'outil dans le repÚre piÚce puis dans le repÚre machine afin d'y réaliser l'optimisation. La méthode d'optimisation est comparée à des méthodes alternatives selon des critÚres de rapidité de calcul et de performanceCLERMONT FD-BCIU Sci.et Tech. (630142101) / SudocSudocFranceF
INTERFERENCE AND SHADOW EFFECTS IN THE PRODUCTION OF LIGHT BY CHARGED PARTICLES IN OPTICAL FIBERS 1
A charged particle passing through or near a narrow optical fiber induces, by polarisation, coherent light guided by the fiber. In the limit of zero crossing angle, the radiation tends towards a Cherenkov radiation with a discrete spectrum, studied by different authors. If the particle crosses a bent fiber at regularly spaced points, interference gives quasi-monochromatic lines. If the particle passes near an end of the fiber, light is produced by the capture of virtual photons through the end face. An alternative way consists in sticking a metallic ball to the fiber: the passing particle induces plasmons which are then evacuated as light in the fiber. Interferences can occur between lights from several ends or balls. Applications of these various light signals to beam diagnostics are discussed. The shadow effect, which reduces the photon yield when the particle runs parallel to a row of balls, is pointed out and an upper bound âdE/dz †C(Ze/b) 2 for the particle energy loss is conjectured (Ze is the particle charge, b the impact parameter and C a numerical constant). This bound should also apply to other kinds of light sources, in particular to Smith-Purcell radiation
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