37 research outputs found
Robust Gamma regression models for the analysis of health care cost data
No full textAbstract: The population-mean cost of patients with certain pathologies is the parameter of interest for allocating health resources. It generally depends upon a number of covariates and the presence of outliers yields difficulties in the estimation procedure. Recent research in parametric robust techniques proposed the use of robust estimating equations via M-estimation for the Gamma model [2] and a class of high efficiency and high breakdown point estimators [14] extended to the case of generalized log-gamma regression [12]. In the present work, we compared results obtained by the two parametric robust procedures with the standard GLM (Generalized Linear Model) Gamma with log link, both in a simulation study and in a cardiovascular trial. The robust procedures outperformed the GLM Gamma in the contaminated simulation scenario and in the real dataset the significance of some covariates changed between the three estimators, with a better ability of the Log Gamma Robust in isolating the outliers driving these changes
Bairdemys GAFFNEY & TONG & MEYLAN 2002, new genus
No full text<i>BAIRDEMYS</i>, new genus <p> TYPE SPECIES: <i>Bairdemys hartsteini</i>, new species.</p> <p>DISTRIBUTION: Miocene of Puerto Rico and Venezuela.</p> <p> DIAGNOSIS: A <i>Shweboemys</i> Group Pelomedusoides (sensu Meylan, 1996) known from skull and shell; secondary palate shorter than in all <i>Shweboemys</i> Group except <i>‘‘Shweboemys’’ gaffneyi</i>; medial edges of palatal cleft curved as in <i>‘‘Shweboemys’’ gaffneyi</i>; ventral convexity on triturating surface larger than in all other <i>Shweboemys</i> Group; eustachian tube separated by bone from rest of fenestra postotica in contrast to all known Podocnemididae; antrum postoticum extremely small and slitlike in contrast to all other <i>Shweboemys</i> Group; frontal and prefrontal strongly convex on dorsal surface in contrast to all other <i>Shweboemys</i> Group; basisphenoid separated from palatines by medially meeting pterygoids as in <i>‘‘Shweboemys’’ antiqua</i>; basioccipital longer than in <i>Shweboemys pilgrimi</i>; jugal­pterygoid contact prevents palatine­parietal contact.</p> <p> INCLUDED SPECIES: <i>Bairdemys venezuelensis</i> (Wood and Díaz de Gamero, 1971), <i>Bairdemys hartsteini</i>, new species (see table 1 for comparisons).</p> <p>ETYMOLOGY: The genus name is in honor of Dr. Donald Baird, a student of fossil turtles and other reptiles, who spent most of his career at Princeton University, and was an</p> <p> TABLE 1 <b> Comparison of <i>Bairdemys</i> species</b> </p> <p>inspiring mentor of both authors. Don is active in many areas of vertebrate paleontology and fossil reptile research and has influenced many young people in paleontology. In 1964, when one of the authors, Gene Gaffney, was a senior at Rutgers University, Don was directly responsible for introducing Gene to fossil turtles. Roger Wood, the other author, as a Princeton undergraduate was also influenced by Don in entering paleontology.</p>Published as part of <i>GAFFNEY, EUGENE S., TONG, HAIYAN & MEYLAN, PETER A., 2002, Bairdemys, a New Side-Necked Turtle (Pelomedusoides: Podocnemididae) from the Miocene of the Caribbean, pp. 1-28 in American Museum Novitates 3359</i> on pages 2-4, DOI: 10.1206/0003-0082(2002)379<0001:GANSNT>2.0.CO;2, <a href="http://zenodo.org/record/4712203">http://zenodo.org/record/4712203</a>
Participer à la vie locale : le cas de Meylan
No full textMeylan est une petite commune de l’agglomération de Grenoble qui a attiré l’attention de nombreux observateurs en raison du développement extraordinaire de la vie associative. Meylan est gérée depuis 1971 par une équipe d’orientation socialiste dont l’élection est le signe de l’émergence sur le plan communal de nouvelles couches sociales moyennes et supérieures.La vie sociale à Meylan est pensée en termes de vie associative, dans une perspective de gestion communautaire de la cité. Mais ce projet participatif n’est pas sans ambiguïté. Il met en évidence la contradiction dans laquelle se trouve toute association prise entre les nécessités de la gestion d’un espace urbain et la spécificité des pratiques qui s’y inscrivent. Quelles sont dès lors les conditions d’une réelle démocratisation de la vie locale ?Meylan is a little municipality located within the metropolitan area of Grenoble that has attracted considerable attention due to intense activity of community groups. The election of a Socialist slate to City Hall in 1971 was largely due to the presence of new middle and upper-middle classes on the local scene.Community groups play an important role in the daily life of Meylan as they seek to develop new methods of neighbourhood management but their policy of citizen participation is ambiguous. These groups are caught in the bind between the necessity to establish effective management procedures and the necessity to respect the particular characteristics of each neighbourhood. The author seeks to elucidate the conditions that are necessary for a real democratization of community life.Meylan es una pequeña comuna en la aglomeración de Grenoble que ha llamado la atención de muchos observadores por el desarrollo extraordinario de su vida asociativa. Meylan está dirigida desde 1971 por un equipo de orientación socialista del cual la elección es el signo de la emergencia en el plano comunal de nuevas capas sociales medias y superiores.La vida social en Meylan es concebida en términos de vida asociativa, en una perspectiva de gestión comunitaria de la ciudad; pero este proyecto participativo no está libre de ambiguëdades. El muestra la contradicción que vive toda asociación tironeada entre las necesidades de la gestión de un espacio urbano y la especificidad de las prácticas que se realizan. ?Cuáles son, por lo tanto, las condiciones de una democratización real de la vida local
Higher order symmetries of real hypersurfaces in ℂ³
No full textWe study nonlinear automorphisms of Levi degenerate hypersurfaces of finite multitype. By results of Kolar, Meylan, and Zaitsev in 2014, the Lie algebra of infinitesimal CR automorphisms may contain a graded component consisting of nonlinear vector fields of arbitrarily high degree, which has no analog in the classical Levi nondegenerate case, or in the case of finite type hypersurfaces in . We analyze this phenomenon for hypersurfaces of finite Catlin multitype with holomorphically nondegenerate models in complex dimension three. The results provide a complete classification of such manifolds. As a consequence, we show on which hypersurfaces 2-jets are not sufficient to determine an automorphism. The results also confirm a conjecture about the origin of nonlinear automorphisms of Levi degenerate hypersurfaces, formulated by the first author for an AIM workshop in 2010
Notes on Myxomycetes V. On the identity of the genera Cribraria and Dictydium
No full textThe genus Dictydium was created by SCHRADER (1797) for Cribrarialike forms lacking a cup. ROSTAFINSKI (1875) gave it its modern definition: i.e. having meridional costae which are joined at frequent intervals by fine, more or less parallel threads. He further created a genus Heterodictyon for a species (H. mirabile) which has ribs in the lower part and a Cribraria-like net in the upper. Massee in his monograph (1892) transferred Heterodictyon to Cribraria (C. mirabilis Mass.), pointing out that there is “every shade of transition between the two extremes,” and that Heterodictyon bienaszii Racib. i.e. ( Cribraria macrocarpa of the later monographs) “closely connects the genus Cribraria in the wider sense with Dictydium.” Jahn in 1901 described a variety “anomalum” of Dictydium umbilicatum (i.e. D. cancellatum Batsch), with a rigid stem “ohne die hakenformige Aufhangung in das Sporenkörbchen”, with a rather long sporangium, always without a cup, with the ribs merging into a Cribraria-like net in the upper part, and with a more persistent silvery peridium than is found in the typical form. He studied this taxon for some years, and came to the conclusion that it was not more than a variety of Dictydium umbilicatum. Later MEYLAN (Bull. Soc. Vaud. 44: 295. 1908) raised it to specific rank ( Dictydium anomalum), mentioning a similar variation in presence or absence of the cup as occurs in D. cancellatum, and never finding any “formes transitoires vers D. umbilicatum”. He further was of opinion that D. anomalum would probably be identical with Rostafinski’s Heterodictyon mirabile. In 1911 Lister reduced D. anomalum Meylan to his var. alpinum of D. cancellatum. In Bull. Soc. Vaud. 57: 305. 1932 Meylan went a step further, and sank Dictydium cancellatum (Batsch) var. alpinum Lister into Dictydium mirabile (Rost.) Meylan. In a later paper wherein G. LISTER describes D. rutilum (Journ. of Bot 71: 222, 1933), this author states that D. cancellatum var. alpinum is clearly the same as Rostafinski’s species, adding that Meylan considered this variety worthy of specific rank. Dr G. W. Martin (private communication, shortly to be published), agrees with Meylan that this taxon merits specific rank
Surgical Safety and Hospital Volume Across a Wide Range of Interventions
No full textOBJECTIVES:: For certain major operations, inpatient mortality risk is lower in high-volume hospitals than those in low-volume hospitals. Extending the analysis to a broader range of interventions and outcomes is necessary before adopting policies based on minimum volume thresholds. METHODS:: Using the United States 2004 Nationwide Inpatient Sample, we assessed the effect of intervention-specific and overall hospital volume on surgical complications, potentially avoidable reoperations, and deaths across 1.4 million interventions in 353 hospitals. Outcome variations across hospitals were analyzed through a 3-level hierarchical logistic regression model (patients, surgical interventions, and hospitals), which took into account interventions on multiple organs, 144 intervention categories, and structural hospital characteristics. Discriminative performance and calibration were good. RESULTS:: Hospitals with more experience in a given intervention had similar reoperation rates but lower mortality and complication rates: odds ratio per volume deciles 0.93 and 0.97. However, the benefit was limited to heart surgery and a small number of other operations. Risks were higher for hospitals that performed more interventions overall: odds ratio per 1000 for each event was approximately 1.02. Even after adjustment for specific volume, mortality varied substantially across both high- and low-volume hospitals. CONCLUSION:: Although the link between specific volume and certain inpatient outcomes suggests that specialization might help improve surgical safety, the variable magnitude of this link and the heterogeneity of hospital effect do not support the systematic use of volume-based referrals. It may be more efficient to monitor risk-adjusted postoperative outcomes and to investigate facilities with worse than expected outcomes
Hubble, Chandra and Keck Constraints on Massive Galaxy Clusters at z=0.2 and z=0.5
No full textI present recent observations from two Hubble Space Telescope(HST)/ACS programs that target the most X–ray luminous and thus (presumably) most massive galaxy clusters at – the highest redshift at which complete, well–defined samples of such rare systems are available. The first program (GO:9836, PI: R.S. Ellis) exploits a huge mosaic of 41 ACS pointings spanning a 10 Mpc region centered on MS0451-03. This is the largest contiguous space–based image of a cluster to date. I describe a preliminary weak–lensing analysis and a new Keck/DEIMOS redshift catalog of 1000 galaxies in this field. The second program (GO:9722, PI: H. Ebeling) studies the core regions of the twelve most luminous clusters at from the MAssive Cluster Survey (MACS; Ebeling et al. 2001). Multi–color ACS observations in combination with recent Keck/LRIS spectroscopy of gravitational arcs constrain the distribution of mass in the cluster cores, thus laying the foundation for detailed multi–diagnostic (lensing, X–ray, near–infrared, SZE) investigation of this sample. For example, it is of particular interest to explore how the structure and state of relaxation of massive clusters evolved between this sample at that measured by Smith et al. (2004, astro–ph/0403588) at .To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.htm
Precise measurements of time delays in gravitationally lensed quasars for competitive and independent determination of the Hubble constant
No full textDuring these last decades, by virtue of observations, the Standard Cosmological Model has emerged, providing a description of the Universe's evolution using a minimal set of independent constraints - the cosmological parameters. Among them is the expansion rate of the Universe, the so-called Hubble constant or H0, first measured by Lemaître in 1927. The century that followed this cornerstone measurement saw numerous attempts to refine the initial value, and for good reason: a precise and independent measurement of H0 will bring strong constraints on the cosmological models. It could notably help the astronomers to better understand the nature of dark energy, thus making it one of the most sought-after prizes in modern cosmology. My work at the Laboratory of Astrophysics of EPFL is embedded in this context. I am part of the COSMOGRAIL and H0LiCOW collaborations, aiming to measure the Hubble constant with the highest level of precision using time-delay cosmography, a method based on the theory of strong gravitational lensing. This effect occurs when an observer looks at a light source located behind a massive foreground galaxy. The mass of the galaxy acts similarly to an optical lens and focuses the light rays emitted by the source. As a consequence, multiple lensed images of the source appear around the lens galaxy. If the luminosity of the source changes over time, the variations will be seen in all the lensed images but with a temporal delay due to the different travel paths of the light rays. By carefully monitoring the luminosity variations of each lensed image, one can precisely measure the temporal delays between them. Combined to high-resolution observations of the foreground galaxy and its surroundings, it is possible to directly measure the Hubble constant upon the sole assumption that the General Relativity is correct. Since more than 13 years, COSMOGRAIL monitors dozens of lensed quasars to produce high-quality light curves and time-delay measurements. During these last four years, I took care of the monitoring schedule, continuous data reduction and time-delay measurements through the development of curve-shifting techniques. I produced light curves and measured time delays on a variety of lenses. After more than a decade of endeavours, COSMOGRAIL and H0LiCOW finally revealed their measurement of the expansion rate of the Universe from a blind analysis of three lensed sources. I had the privilege to be the lead author of the publication presenting our measurement of the Hubble constant, H0=71.9 -3.0+2.4 km/s/Mpc 3.8% precision in the Standard Cosmological Model. Such a precision allows a direct comparison with the results of the distance ladder technique in the local Universe and the Planck satellite Cosmic Microwave Background observations in the distant Universe, both of which being currently in a significant tension of unknown source.LASTR
