Active Learning and Best-Response Dynamics

We examine an important setting for engineered systems in which low-power distributed sensors are each making highly noisy measurements of some unknown target function. A center wants to accurately learn this function by querying a small number of sensors, which ordinarily would be impossible due to the high noise rate. The question we address is whether local communication among sensors, together with natural best-response dynamics in an appropriately-defined game, can denoise the system without destroying the true signal and allow the center to succeed from only a small number of active queries. By using techniques from game theory and empirical processes, we prove positive (and negative) results on the denoising power of several natural dynamics. We then show experimentally that when combined with recent agnostic active learning algorithms, this process can achieve low error from very few queries, performing substantially better than active or passive learning without these denoising dynamics as well as passive learning with denoising

A reduced-order strategy for 4D-Var data assimilation

This paper presents a reduced-order approach for four-dimensional variational data assimilation, based on a prior EO F analysis of a model trajectory. This method implies two main advantages: a natural model-based definition of a mul tivariate background error covariance matrix $\textbf{B}_r$, and an important decrease of the computational burden o f the method, due to the drastic reduction of the dimension of the control space. % An illustration of the feasibility and the effectiveness of this method is given in the academic framework of twin experiments for a model of the equatorial Pacific ocean. It is shown that the multivariate aspect of $\textbf{B}_r$ brings additional information which substantially improves the identification procedure. Moreover the computational cost can be decreased by one order of magnitude with regard to the full-space 4D-Var method

Scaling Analysis of Chiral Phase Transition for Two Flavors of Kogut-Susskind Quarks

Report is made of a systematic scaling study of the finite-temperature chiral phase transition of two-flavor QCD with the Kogut-Susskind quark action based on simulations on $L^3\times4$ ($L$=8, 12 and 16) lattices at the quark mass of $m_q=0.075, 0.0375, 0.02$ and 0.01. Our finite-size data show that a phase transition is absent for $m_q\geq 0.02$, and quite likely also at $m_q=0.01$. The scaling behavior of susceptibilities as a function of $m_q$ is consistent with a second-order transition at $m_q=0$. However, the exponents deviate from the O(2) or O(4) values theoretically expected.Comment: Talk presented by M. Okawa at the International Workshop on `` LATTICE QCD ON PARALLEL COMPUTERS", 10-15 March 1997, Center for Computational Physics, University of Tsukuba. 7 LaTeX pages plus 5 postscript figures, uses espcrc2.st

Des catégories politiques utilisées dans la Russie contemporaine lors du dernier recensement

Les nouvelles divisions territoriales ont été mises à l’épreuve récemment par le dernier recensement qui montre que nombre de catégories ethniques supprimées lors du recensement de 1939 pour simplifier la carte ethnique, ont tendance à réapparaître à la faveur de la loi pour les petits peuples. On y lit toute la complexité d’une structure que le centre veut figer une fois pour toutes dans des catégories stables pour les consolider, mais dans lesquelles certaines populations ne se reconnaissent absolument pas et revendiquent un autre statut, car à tout statut correspond des droits afférents. La bataille pour la nationalité et le code des Cosaques met ainsi en relief les enjeux autour de ces appellations et identifications depuis les récentes constitutions.Alain Blum, Catherine Goussef, Xavier Letorivellec. Polical categories used in the last census in Russia The new territorial divisions have recently been put to the test by the last census which showed that a number of ethnic groups suppressed during the 1939 census in order to simplify the map, tend to reappear following the law benefiting small ethnic groups. One can read in this all the complexity of a structure which the centre wants to freeze once and for all into stable categories aiming to consolidate these groups but in which some populations do not recognise themselves at all, preferring to claim another status, since there is a corresponding right for each status. Thus the battle for nationality and the Cossacks’ Code bring to the fore the stakes which are associated with these labels and identifications since the recent constitutions were written

La difficile reconnaissance du caractère professionnel des atteintes à la santé mentale

Des évolutions récentes dans la prise en compte des risques psychosociaux ainsi que dans la réglementation, la jurisprudence et les pratiques administratives, ont permis une amélioration de la reconnaissance en accidents du travail ou en maladies professionnelles des atteintes à la santé mentale. Cependant, les démarches pour obtenir cette reconnaissance demeurent difficiles pour les salariés concernés, du fait de la complexité des procédures, mais aussi de l’écart entre le rôle prescrit des acteurs (employeur, médecin du travail, etc.) et leur conduite réelle, et enfin à cause du retentissement possible de la démarche sur la situation de la personne. L’accompagnement par des acteurs aux compétences complémentaires (médecin, psychologue, juriste) apparaît pertinent pour éviter les impasses.Recent developments in the consideration of psychosocial risks, as well as in regulations, jurisprudence and administrative practices have given rise to an improvement in the recognition of mental health damages as occupational accidents or occupational diseases. The formalities to gain this recognition, however, remain complicated for the employees involved because of the procedure complexities, the gap existing between the actors’ (employers, company doctors…) assigned role and actual behavior, last but not least the possible impact of the formalities on the person’s situation. The support offered by people with complementary expertise (doctors, psychologists, jurists…) seems appropriate to avoid reaching deadlock.La reciente evolución en la consideración de los riesgos psicosociales así como en la reglamentación, la jurisprudencia y las prácticas administrativas han permitido una mejora del reconocimiento de los daños a la salud mental como accidentes de trabajo o enfermedades profesionales. Sin embargo, el proceso para obtener este reconocimiento sigue siendo difícil para los trabajadores afectados, debido a la complejidad de los procedimientos, pero también debido a la diferencia entre el rol prescrito de los actores (empleador, médico de la empresa, etc.) y su comportamiento real, y, por último, por el posible impacto de este proceso sobre la situación de la persona. El acompañamiento por parte de los actores con habilidades complementarias (médico, psicólogo, abogado) parece relevante para evitar un impasse

Galactic bulge giants: probing stellar and galactic evolution I. Catalogue of Spitzer IRAC and MIPS sources

Aims: We aim at measuring mass-loss rates and the luminosities of a statistically large sample of Galactic bulge stars at several galactocentric radii. The sensitivity of previous infrared surveys of the bulge has been rather limited, thus fundamental questions for late stellar evolution, such as the stage at which substantial mass-loss begins on the red giant branch and its dependence on fundamental stellar properties, remain unanswered. We aim at providing evidence and answers to these questions. Methods: To this end, we observed seven 15 times 15 arcmin^2 fields in the nuclear bulge and its vicinity with unprecedented sensitivity using the IRAC and MIPS imaging instruments on-board the Spitzer Space Telescope. In each of the fields, tens of thousands of point sources were detected. Results: In the first paper based on this data set, we present the observations, data reduction, the final catalogue of sources, and a detailed comparison to previous mid-IR surveys of the Galactic bulge, as well as to theoretical isochrones. We find in general good agreement with other surveys and the isochrones, supporting the high quality of our catalogue.Comment: 21 pages, accepted for publication in A&A. A version with high-resolution figures, as well as the data catalogues (including cross-id with GLIMPSE and GALCEN) and image mosaics are available at the anonymous ftp://ftp.ster.kuleuven.be/dist/stefan/Spitzer

Markers of low level arsenic exposure for evaluating human cancer risks in a US population

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155831/1/Karagas_et_al_2001_Markers_of_low_level.pd

Interstellar Extinction and Long-Period Variables in the Galactic Center

We use the Spitzer IRAC catalogue of the Galactic Center (GC) point sources (Ramirez et al. 2008) and combine it with new isochrones (Marigo et al. 2008) to derive extinctions based on photometry of red giants and asymptotic giant branch (AGB) stars. This new extinction map extends to much higher values of Av than previoulsy available. Our new extinction map of the GC region covers 2.0 x 1.4 degree (280 x 200 pc at a distance of 8 kpc). We apply it to deredden the LPVs found by Glass et al. (2001) near the GC. We make period-magnitude diagrams and compare them to those from other regions of different metallicity. The Glass-LPVs follow well-defined period-luminosity relations (PL) in the IRAC filter bands at 3.6, 4.5, 5.8, and 8.0 micron. The period-luminosity relations are similar to those in the Large Magellanic Cloud, suggesting that the PL relation in the IRAC bands is universal. We use ISOGAL data to derive mass-loss rates and find for the Glass-LPV sample some correlation between mass-loss and pulsation period, as expected theoretically.The GC has an excess of high luminosity and long period LPVs compared to the Bulge, which supports previous suggestions that it contains a younger stellar population.Comment: 12 pages, 11 figures accepted for publication in Astronomy & Astrophysic

Haptoglobin Phenotype, Preeclampsia Risk and the Efficacy of Vitamin C and E Supplementation to Prevent Preeclampsia in a Racially Diverse Population

Haptoglobin's (Hp) antioxidant and pro-angiogenic properties differ between the 1-1, 2-1, and 2-2 phenotypes. Hp phenotype affects cardiovascular disease risk and treatment response to antioxidant vitamins in some non-pregnant populations. We previously demonstrated that preeclampsia risk was doubled in white Hp 2-1 women, compared to Hp 1-1 women. Our objectives were to determine whether we could reproduce this finding in a larger cohort, and to determine whether Hp phenotype influences lack of efficacy of antioxidant vitamins in preventing preeclampsia and serious complications of pregnancy-associated hypertension (PAH). This is a secondary analysis of a randomized controlled trial in which 10,154 low-risk women received daily vitamin C and E, or placebo, from 9-16 weeks gestation until delivery. Hp phenotype was determined in the study prediction cohort (n = 2,393) and a case-control cohort (703 cases, 1,406 controls). The primary outcome was severe PAH, or mild or severe PAH with elevated liver enzymes, elevated serum creatinine, thrombocytopenia, eclampsia, fetal growth restriction, medically indicated preterm birth or perinatal death. Preeclampsia was a secondary outcome. Odds ratios were estimated by logistic regression. Sampling weights were used to reduce bias from an overrepresentation of women with preeclampsia or the primary outcome. There was no relationship between Hp phenotype and the primary outcome or preeclampsia in Hispanic, white/other or black women. Vitamin supplementation did not reduce the risk of the primary outcome or preeclampsia in women of any phenotype. Supplementation increased preeclampsia risk (odds ratio 3.30; 95% confidence interval 1.61-6.82, p<0.01) in Hispanic Hp 2-2 women. Hp phenotype does not influence preeclampsia risk, or identify a subset of women who may benefit from vitamin C and E supplementation to prevent preeclampsia

Randomized trial assessing home use of two pregnancy tests for determining early medical abortion outcomes at 3, 7 and 14days after mifepristone

AbstractObjectiveTo evaluate the accuracy, feasibility and acceptability of two urine pregnancy tests in assessing abortion outcomes at three time points after mifepristone administration.Study designThis randomized trial enrolled women seeking early medical abortion at two hospitals in Vietnam. Investigators randomly allocated participants to at-home administration of a multilevel urine pregnancy test (MLPT) or a high sensitivity urine pregnancy test (HSPT) to assess their abortion outcomes. A baseline test was administered on the same day as mifepristone. Participants performed and interpreted results of pregnancy tests taken 3, 7 and 14days after mifepristone. Ultrasound exam determined continuing pregnancy.ResultsSix hundred women enrolled, and 300 received each test. A percentage of 97.4 (584) had follow-up, of whom 13 women had continuing pregnancies. The specificity of MLPT at detecting absence of continuing pregnancy was 63.9%, 90.4% and 97.1% at study day 3, 7 and 14. The specificity of HSPT was 6.0%, 19.8% and 62.2%, respectively. The positive predictive value (PPV) of MLPT at detecting continuing pregnancy was 6.4% at day 3 and rose to 46.7% at day 14. In contrast, the PPV for HSPT was 2.2% at day 3 and rose to 6.5% at day 14. At all three time points, the sensitivity and negative predictive values for both tests were 100.0%. Most women found their assigned tests easy to use and would prefer future home follow-up with a pregnancy test.ConclusionsThe MLPT enables women to assess their abortion outcomes more reliably than with HSPT. With MLPT, women can know their outcomes as early as 3 days after mifepristone.ImplicationsMedical abortion service delivery with an MLPT to obtain a baseline (preabortion) human chorionic gonadotropin (hCG) estimate and a second follow-up MLPT 1 to 2 weeks later can establish whether there has been a drop in hCG, signifying absence of a continuing pregnancy. Used this way, MLPTs can enable women to assess their abortion status outside of a clinic setting and without serum hCG testing and/or ultrasound