Curbing Cream-Skimming: Evidence on Enrolment Incentives

Can enrolment incentives reduce the incidence of cream-skimming in the delivery of public sector services (e.g. education, health, job training)? In the context of a large government job training program, we investigate whether the use of enrolment incentives that set different 'shadow prices' for serving different demographic subgroups of clients, influence case workers' choice of intake population. Exploiting exogenous variation in these shadow prices, we show that training agencies change the composition of their enrollee populations in response to changes in the incentives, increasing the relative fraction of subgroups whose shadow prices increase. We also show that the increase is due to training agencies enrolling at the margin weaker members, in terms of performance, of that subgroup.performance measurement, cream-skimming, enrolment incentives, bureaucrat behavior, public organizations

On D*-extension property of the Hartogs domains

A complex analytic space is said to have the D*-extension property if and only if any holomorphic map from the punctured disk to the given space extends to a holomorphic map from the whole disk to the same space. A Hartogs domain H over the base X (a complex space) is a subset of X × C where all the fibers over X are disks centered at the origin, possibly of infinite radius. Denote by [phi] the function giving the logarithm of the reciprocal of the radius of the fibers, so that, when X is pseudoconvex, H is pseudoconvex if and only if [phi] is plurisubharmonic. We prove that H has the D*-extension property if and only if (i) X itself has the D*-extension property, (ii) [phi] takes only finite values and (iii) [phi] is plurisubharmonic. This implies the existence of domains which have the D*-extension property without being (Kobayashi) hyperbolic, and simplifies and generalizes the authors' previous such example

Curbing cream-skimming: Evidence on enrolment incentives

Using data from a large, U.S. federal job training program, we investigate whether enrolment incentives that exogenously vary the ‘shadow prices’ for serving different demographic subgroups of clients influence case workers’ intake decisions. We show that case workers enroll more clients from subgroups whose shadow prices increase but select at the margin weaker-performing members from those subgroups. We conclude that enrolment incentives curb cream-skimming across subgroups leaving a residual potential for cream-skimming within a subgroup.Performance measurement, cream-skimming, enrolment incentives, bureaucrat behavior, public organizations

The effects of stellar winds on the magnetospheres and potential habitability of exoplanets

Context: The principle definition of habitability for exoplanets is whether they can sustain liquid water on their surfaces, i.e. that they orbit within the habitable zone. However, the planet's magnetosphere should also be considered, since without it, an exoplanet's atmosphere may be eroded away by stellar winds. Aims: The aim of this paper is to investigate magnetospheric protection of a planet from the effects of stellar winds from solar-mass stars. Methods: We study hypothetical Earth-like exoplanets orbiting in the host star's habitable zone for a sample of 124 solar-mass stars. These are targets that have been observed by the Bcool collaboration. Using two wind models, we calculate the magnetospheric extent of each exoplanet. These wind models are computationally inexpensive and allow the community to quickly estimate the magnetospheric size of magnetised Earth-analogues orbiting cool stars. Results: Most of the simulated planets in our sample can maintain a magnetosphere of ~5 Earth radii or larger. This suggests that magnetised Earth analogues in the habitable zones of solar analogues are able to protect their atmospheres and is in contrast to planets around young active M dwarfs. In general, we find that Earth-analogues around solar-type stars, of age 1.5 Gyr or older, can maintain at least a Paleoarchean Earth sized magnetosphere. Our results indicate that planets around 0.6 - 0.8 solar-mass stars on the low activity side of the Vaughan-Preston gap are the optimum observing targets for habitable Earth analogues.Comment: 8 pages, 3 figures, accepted to Astronomy and Astrophysic

RNA interference of the stress related OsMADS26 transcription factor in rice increases resistance to various pathogens and reduces plant development

Several transcription factors have been involved in rice response against biotic and abiotic stresses (Khong et al., 2008). In A. thaliana, the MADS box transcription factor AGL12 control cell division in root meristem and is involved in flowering transition (Tapia-Lopez et al., 2008). When over expressed in Catharanthus roseus cell suspension AGL12 promotes tissue like organization and alkaloid biosynthesis (Montiel et al., 2007). OsMADS26, the rice orthologous of AGL12 in A. thaliana was recently over expressed under the control of a DEX inducible promoter and described as a stress related gene Lee et al., 2008). Nevertheless its precise function remains unknown. QPCR analysis revealed that this gene is expressed both in leaves and roots and is upregulated in response to osmotic stress. In order to precise the function of OsMAD26 in stress response or in development, and in absence of insertion mutant, we had generated rice lines RNA interfered for this gene. Interfered lines were obtained with two GST tagging the 5' or the 3' end of the mRNA. Interfered lines were affected in their development (root, tillering, height, dry weight) and were delayed for their flowering time in comparison to control. Roots of interfered lines present a reduced geotropism. Interfered lines were not affected in comparison to control line in their availability to resist to drought stress. But interestingly, interfered lines present an increased resistance against Magnaeporthae grisea, Xanthomonas oryzae and the Rice Yellow Mottle Virus. This suggests that OsMADS26 is a negative regulator of biotic stress response and acts as a general activator of development. In order to identify the genes and the biological pathways regulated by OsMADS26 we have proceeded to a transcriptome comparative analysis of genes expressed in WT and RNA interfered lines. Data analysis is in progress. (Texte intégral

Godunov type scheme for the linear wave equation with Coriolis source term

International audienceWe propose a method to explain the behavior of the Godunov finite volume scheme applied to the linear wave equation with Coriolis source term at low Froude number. In particular, we use the Hodge decomposition and we study the properties of the modified equation associated to the Godunov scheme. Based on the structure of the discrete kernel of the linear operator discretized by using the Godunov scheme, we clearly explain the inaccuracy of the classical Godunov scheme at low Froude number and we introduce the way to modify it to recover a good accuracy

Semen quality of stress negative Piétrain and Duroc boars in the tropics: the case of Vietnam

This study was carried out in Dong Hiep pig farm, North of Vietnam in order to evaluate the semen quality of stress negative Piétrain and Duroc boars. A total of 722 ejaculates from 13 homozygous (CC), 7 heterozygous (CT) stress negative Piétrain and 10 Duroc CC boars was collected between 2008 and 2012. The sperm quality was assessed on each ejaculate using ejaculate volume (VOL), spermatozoa motility (MO), sperm concentration (CO) and total number of spermatozoids (NT). Genetic type of boars, season, year and (season x year) as well as (genetic type x year) interactions were included in the model as fixed factors. The results show that the semen quality was influenced by all studied effects (p<0.05) except VOL for season (p=0.45) and season x year (p=0.55), and CO for genetic type (p=0.93). VOL and NT (291.74ml and 103.37×109spz) of Piétrain CC were higher than those (241.40ml and 84.58×109spz) of Piétrain CT and (228.05ml and 77.15×109spz) of Duroc (p<0.001) although the values of the 3 genetic groups are in the range of normal semen. MO, CO and NT tend to be higher in cold than in hot season (p<0.001). These results suggest that semen from Piétrain and Duroc boars could be used in tropical climatic conditions (particularly Piétrain CC) and that the semen quality could be improved through reduction of heat stress

Growth performance and sperm quality of stress negative Piétrain boars and their hybrids with Duroc

peer reviewedThis study was conducted to evaluate the effects of genetic background and season on growth performance and semen quality of boars. Five genetic groups were evaluated, including stress-negative Piétrain boars with CC (PiCC) or CT (PiCT) halothane genotypes, and Piétrain x Duroc hybrid boars with various compositions (25% (PiDu25), 50% (PiDu50) or 75% (PiDu75) of Piétrain origin). The results showed that genetic group has a significant effect on growth performance and semen quality. The hybrid boars PiDu25, PiDu50 and PiDu75 had better growth rate, but lower lean meat in comparison with pure stress-negative Piétrain, except PiDu75 boars. PiDu25, PiDu50 and PiCC boars demonstrated high semen quality. A season effect was observed on most of semen quality traits of pure stress-negative Piétrain as well as hybrid boars with different genetic constitution. Sperm concentration was lower in Summer and Autumn, higher in Winter and Spring. The Piétrain x Duroc hybrid boars, especially PiDu75 seem to be promising as terminal boars

Magnetic field and wind of Kappa Ceti: towards the planetary habitability of the young Sun when life arose on Earth

We report magnetic field measurements for Kappa1~Cet, a proxy of the young Sun when life arose on Earth. We carry out an analysis of the magnetic properties determined from spectropolarimetric observations and reconstruct its large-scale surface magnetic field to derive the magnetic environment, stellar winds and particle flux permeating the interplanetary medium around Kappa1~Cet. Our results show a closer magnetosphere and mass-loss rate of Mdot = 9.7 x 10^{-13} Msol/yr, i.e., a factor 50 times larger than the current solar wind mass-loss rate, resulting in a larger interaction via space weather disturbances between the stellar wind and a hypothetical young-Earth analogue, potentially affecting the planet's habitability. Interaction of the wind from the young Sun with the planetary ancient magnetic field may have affected the young Earth and its life conditionsComment: 6 pages, 5 figures, Published at the Astrophysical Journal Letters (ApJL): Manuscript #LET3358