Delayed Babcock-Leighton dynamos in the diffusion-dominated regime

Context. Solar dynamo models of Babcock-Leighton type typically assume the rise of magnetic flux tubes to be instantaneous. Solutions with high-magnetic-diffusivity have too short periods and a wrong migration of their active belts. Only the low-diffusivity regime with advective meridional flows is usually considered. Aims. In the present paper we discuss these assumptions and applied a time delay in the source term of the azimuthally averaged induction equation. This delay is set to be the rise time of magnetic flux tubes which supposedly form at the tachocline. We study the effect of the delay, which adds to the spacial non-locality a non-linear temporal one, in the advective but particularly in the diffusive regime. Methods. Fournier et al. (2017) obtained the rise time according to stellar parameters such as rotation, and the magnetic field strength at the bottom of the convection zone. These results allowed us to constrain the delay in the mean-field model used in a parameter study. Results. We identify an unknown family of solutions. These solutions self-quench, and exhibit longer periods than their non-delayed counterparts. Additionally, we demonstrate that the non-linear delay is responsible for the recover of the equatorward migration of the active belts at high turbulent diffusivities. Conclusions. By introducing a non-linear temporal non-locality (the delay) in a Babcock-Leighton dynamo model, we could obtain solutions quantitatively comparable to the solar butterfly diagram in the diffusion-dominated regime.Comment: 11 pages, 10 Figure

Plant bed treatment with 1,3-dichloropropene for Meloidogyne hapla control in carrots grown in organic soil

L'efficacité d'un traitement de la planche de semis avec le fumigant 1,3-dichloropropène (1,3-D) pour la lutte contre le Meloidogyne hapla et l'accroissement des rendements de carotte a été évaluée en sol organique dans des champs commerciaux. Le sol a été traité avec le 1,3-D à la dose de 56 et 112 L ha-1, soit incorporé avec un motoculteur sur une bande de 15 cm sur le rang ou injecté sous la planche de semis à 20 cm de profondeur à la dose de 56 L ha-1 à l'aide d'une jambe derrière le motoculteur. L'injection à 56 L ha-1 a fourni le plus haut niveau de lutte contre le nematode avec le plus faible indice de nodosité et les meilleurs rendements en carottes vendables (66,7 t ha-1 vs. 51 ha-1 pour le témoin non traité). La méthode d'application par incorporation a été moins efficace que la méthode par injection, même avec le double de la dose. Dans un deuxième essai au champ, le fumigant a été injecté à la dose de 40 L ha-1 avec un injecteur simple à 20 cm de profondeur. Le traitement de sol a augmente le nombre de carottes vendables (68,7 t ha-1 vs. 11,8 1: ha-1 pour le témoin non traité) et a réduit la nodulation. Un traitement de la planche de semis avec le 1,3-D est une méthode alternative et efficace au traitement traditionnel à la volée pour la lutte contre le nématode des nodosités en culture de carottes en sol organique.The efficacy of plant bed treatment with the fumigant 1,3-dichloropropene (1,3-D) to control Meloidogyne hapla and improve carrot yields was determined in an organic soil under commercial field conditions. The soil was treated with 1,3-D at 56 and 112 L ha-1 either mixed with a rototiller in a 15-cm width band over the row or injected 20 cm deep with a single shank behind the rototiller at a rate of 56 L ha-1. The single injection treatment at the 56 L ha-1 rate provided the best nematode control with the lowest galling indices and the highest yield of marketable carrot roots (66.7 t ha-1 vs. 5 t ha-1 for untreated control). The mixed application method was less effective than the soil injection method, even at twice the rate. In a second field trial, the fumigant was injected at 40 L ha-1 rate through a single shank at 20 cm deep. Soil treatment suppressed galling and significantly increased the number of marketable carrot roots (68.71 ha-1 vs. 11.81 ha-1 control). Plant bed treatment with 1,3-D is an effective alternative to traditional broadcast treatment for control of root-knot nematodes in carrot production on organic soil

FINANCING LOCAL DEVELOPMENT

Community/Rural/Urban Development,

Public sector and business sector earnings: a comparison

We compare public sector wages with private firm ones in 2000, without taking into account for work intensity, job security, advantages&The comparison is made in controlling for age, sex, qualification and residence. We find evidence that public sector provides higher wages to women, to unskilled or persons with low degrees, and in the provinces. Women get higher wages in public sector, except those with high degrees in Paris. Men with high degrees get higher wages in firms, the difference is larger in Paris in comparison with the provinces. Wages dispersion is larger in private firms. For the last ten years, relative situation of public sector employees has been improved from 7 to 11 points.wages, public sector

Core-flow constraints on extreme archeomagnetic intensity changes

Recent studies (Ben-Yosef et al., 2009; Shaar et al., 2011) propose extreme archeomagnetic intensity changes (termed spikes) in the range ~4-5μT/year c.a. 1000 BC in the Near East, around 40 to 50 times larger than values typical of the present-day. In order to investigate whether such extreme changes are consistent with a model of the source region of the magnetic field, namely the fluid flow at the surface of Earth's core, we construct upper bounds for instantaneous magnetic intensity change at an arbitrary site on the Earth's surface. These bounds are constrained by the amount of kinetic energy available to sustain the change, taken here to be a prescribed value for the root-mean-squared surface velocity of 13 km/yr as inferred from the current state of the core. Further, we focus attention on two end-members of optimised core surface flow structure: unrestricted and purely-toroidal. As the derivation of the bounds demands complete knowledge of the geomagnetic field at the core surface, we model the unknown field by means of a Monte Carlo approach, extending to high degree the CHAOS-4 (epoch 2010 AD) and CALS10k1.b (epoch 1000 BC) geomagnetic field models.Using 2000 realisations for each family of stochastic field models, we find that optimised core flows are always large-scale and that they tend to generate a non-dipole, quadrupole-dominated secular variation at the Earth's surface. The dependence of the upper bounds as a function of site location reflects the large-scale structure of the intensity itself: stronger field permits more rapid change. For the site in the Near East, purely-toroidal flows have upper bounds of approximately 0.62 ± 0.02μT/year, whereas unrestricted flows increase this bound to 1.20 ± 0.02μT/year. We favour the former as more geophysically sound, on the account of a large body of previous results from core surface flow inversions and consistency with the existence of a stratified layer at the top of the core. Even if we allow for a generous threefold increase in the prescribed rms velocity (and a concomitant threefold increase in the bound), we conclude that the reported occurrences of extreme intensity changes as suggested in the Near East are not compatible with the commonly accepted structure of core-surface flow. However, it may be that an explanation for spikes lies beyond our current perception of core-dynamics and future work would be further motivated by seeking corroborative evidence of rapid intensity change from sites elsewhere on Earth's surface; we therefore also discuss the form that the secular variation would take in the case of simultanenous archeomagnetic spikes

Field theoretic calculation of scalar turbulence

The cascade rate of passive scalar and Bachelor's constant in scalar turbulence are calculated using the flux formula. This calculation is done to first order in perturbation series. Batchelor's constant in three dimension is found to be approximately 1.25. In higher dimension, the constant increases as $d^{1/3}$.Comment: RevTex4, publ. in Int. J. Mod. Phy. B, v.15, p.3419, 200

Decreasing participation rates for old and young people in France

Today, working in the industrialized countries is mainly a matter of middle-aged people (25 to 54 year old). This is particularly true in France where the participation rate for the less than 25 year old people is the smallest one in OECD countries and that for men older than 54 one of the smallest. For the last thirty years, the participation rate of the youngest and oldest working people has been significantly decreasing, apart that of old women due to the increasing trending female participation rate. To illustrate the causes of these changes, we model from a descriptive point of view male and female participation rates for the following age classes: 15 to 19, 20 to 24, 55 to 59 and 60 to 64. Modelling old people participation rate allows us to illustrate the importance of political measures used over the last thirty years to deal with unemployment, in particular the development of early retirement programs and the decrease of the retirement age. Modelling young people participation rate does not give a leading part to a particular cause among the various ones we consider (development of apprenticeship, increasing number of students passing the baccalauréat, population structure, unemployment rate&). In both situations, we measure only weak, if any, response of participation rates to short-term unemployment rate changes.participation rate, unemployment, early retirement programs, apprenticeship, logistic trend

Mixing Probabilistic and non-Probabilistic Objectives in Markov Decision Processes

In this paper, we consider algorithms to decide the existence of strategies in MDPs for Boolean combinations of objectives. These objectives are omega-regular properties that need to be enforced either surely, almost surely, existentially, or with non-zero probability. In this setting, relevant strategies are randomized infinite memory strategies: both infinite memory and randomization may be needed to play optimally. We provide algorithms to solve the general case of Boolean combinations and we also investigate relevant subcases. We further report on complexity bounds for these problems.Comment: Paper accepted to LICS 2020 - Full versio

Reproduction of Pratylenchus penetrans on various rotation crops in Quebec

La reproduction du nématode des lésions racinaires Pratylenchus penetrans a été évaluée en serre sur 12 cultures de rotation. La moutarde brune (Brassica juncea) a été la meilleure plante hôte et a augmenté de 17,2 fois la population initiale. Le soja (Glycine max), le millet japonais (Echinochloa frumentacea), le colza (B. napus), le sarrasin (Fagopyrum esculentum), la moutarde blanche (B. hirta), et le raygrass vivace (Lolium perenne) ont été également très efficaces à multiplier le nématode et n'étaient pas significativement différents du seigle (Secale cereale), une plante hôte standard favorable. Le millet d'Italie (Setaria italica), l'avoine (Avena sativa), le maïs (Zea mays), et le brome des prés (Bromus inermis) ont accru respectivement de 5,8, 5,7, 4,5 et 3,2 fois la population initiale mais de façon significativement moindre que le seigle. Le millet perlé fourrager (Pennisetum glaucum) a présenté le plus faible taux de multiplication, soit 0,4. Ces résultats nous indiquent que les cultures de rotation couramment recommandées sont favorables à l'accroissement des populations du P. penetrans dans le sol à l'exception du millet perlé fourrager. Cette culture annuelle a un bon potentiel comme culture de rotation dans la répression des populations du nématode des lésions racinaires au Québec.The reproduction of the root-lesion nematode Pratylenchus penetrans was assessed on 12 rotation crops under greenhouse conditions. Brown mustard (Brassica juncea) was the best host and increased the initial population by 17.2 times. Soybean (Glycine max), Japanese millet (Echinochloa frumentacea), rape (B. napus), buckwheat (Fagopyrum esculentum), white mustard (B. hirta), and perennial ryegrass (Lolium perenne) were also very efficient in multiplying the nematode and were not significantly different from rye (Secale cereale), a standard host crop. Foxtail millet (Setaria italica), oats (Avena sativa), corn (Zea mays), and bromegrass (Bromus inermis) increased the initial population by 5.8, 5.7, 4.5, and 3.2 times respectively, but significantly less than rye. Forage pearl millet (Pennisetum glaucum) was the poorest host with a reproduction rate of 0.4. These results indicate that most commonly recommended rotation crops are suitable for the build up of P. penetrans populations in the soil with the exception of forage pearl millet. This annual crop has a great potential as a rotation crop for controlling the root-lesion nematode in Quebec