A proof of the Baues-Lemaire conjecture in rational homotopy theory

summary:This paper contains an announcement of a result, which settles the connection between various algebraic models for rational homotopy theory: the models of Quillen, Sullivan and Adams-Hilton-Anick. It is shown how this result, combined with a recent result of Anick, implies a conjecture of {\it H. J. Baues} and {\it J. M. Lemaire} [Math. Ann. 225, 219-245 (1977; Zbl 0322.55019)].\par We describe in some detail the construction of these models (Section 1). We present a variant of the Adams-Hilton model, which is defined in a natural way for simplicial sets. A forthcoming paper will contain a detailed proof of Theorem 1. A generalization to mild homotopy theories is in preparation, where we establish a close connection between extensions of the rational theories due to Dwyer, Cenkl-Porter and Anick

First Chemical Analysis of Stars in The Triangulum-Andromeda Star Cloud

We undertake the first high resolution spectroscopic study of the Triangulum-Andromeda (TriAnd) star cloud --- an extended, mid-latitude Milky Way halo substructure about 20 kpc away in the second Galactic quadrant --- through six M giant star candidates selected to be both spatially and dynamically associated with this system. The abundance patterns of [Ti/Fe], [Y/Fe] and [La/Fe] as a function of [Fe/H] for these stars support TriAnd as having an origin in a dwarf galaxy with a chemical enrichment history somewhat similar to that of the Sagittarius dwarf spheroidal (dSph) galaxy. We also investigate the previously proposed hypothesis that TriAnd is an outlying, dynamically older piece of the Monoceros Stream (also known as the Galactic Anticenter Stellar Structure, "GASS") under the assumption that both features come from the tidal disruption of the same accreted Milky Way satellite and find that net differences in the above abundance patterns between the TriAnd and GASS stars studied suggest that these two systems are independent and unrelated.Comment: Accepted for publication in ApJ Letter

Dark Matter Constraints from the Sagittarius Dwarf and Tail System

2MASS has provided a three-dimensional map of the >360 degree, wrapped tidal tails of the Sagittarius (Sgr) dwarf spheroidal galaxy, as traced by M giant stars. With the inclusion of radial velocity data for stars along these tails, strong constraints exist for dynamical models of the Milky Way-Sgr interaction. N-body simulations of Sgr disruption with model parameters spanning a range of initial conditions (e.g., Sgr mass and orbit, Galactic rotation curve, halo flattening) are used to find parameterizations that match almost every extant observational constraint of the Sgr system. We discuss the implications of the Sgr data and models for the orbit, mass and M/L of the Sgr bound core as well as the strength, flattening, and lumpiness of the Milky Way potential.Comment: 6 pages, 0 figures. Contribution to proceedings of ``IAU Symposium 220: Dark Matter in Galaxies'', eds. S. Ryder, D.J. Pisano, M. Walker, and K. Freema

Group finding in the stellar halo using M-giants in 2MASS: An extended view of the Pisces Overdensity?

A density based hierarchical group-finding algorithm is used to identify stellar halo structures in a catalog of M-giants from the Two Micron All Sky Survey (2MASS). The intrinsic brightness of M-giant stars means that this catalog probes deep into the halo where substructures are expected to be abundant and easy to detect. Our analysis reveals 16 structures at high Galactic latitude (greater than 15 degree), of which 10 have been previously identified. Among the six new structures two could plausibly be due to masks applied to the data, one is associated with a strong extinction region and one is probably a part of the Monoceros ring. Another one originates at low latitudes, suggesting some contamination from disk stars, but also shows protrusions extending to high latitudes, implying that it could be a real feature in the stellar halo. The last remaining structure is free from the defects discussed above and hence is very likely a satellite remnant. Although the extinction in the direction of the structure is very low, the structure does match a low temperature feature in the dust maps. While this casts some doubt on its origin, the low temperature feature could plausibly be due to real dust in the structure itself. The angular position and distance of this structure encompass the Pisces overdensity traced by RR Lyraes in Stripe 82 of the Sloan Digital Sky Survey (SDSS). However, the 2MASS M-giants indicate that the structure is much more extended than what is visible with the SDSS, with the point of peak density lying just outside Stripe 82. The morphology of the structure is more like a cloud than a stream and reminiscent of that seen in simulations of satellites disrupting along highly eccentric orbits.Comment: Accepted for publication in Ap

Sport injuries in adolescents

In spite of the wide range of injuries in adolescents during sports activities, there are only a few studies investigating the type and frequency of sport injuries in puberty. However, this information may help to prevent, diagnose and treat sports injuries among teens. 4468 injuries in adolescent patients were treated over a ten year period of time: 66,97% were boys and 32.88% girls. The most frequent sports injuries were football (31.13%) followed by handball (8.89%) and sports during school (8.77%). The lower extremity was involved in 68.71% of the cases. Knee problems were seen in 29.79% of the patients; 2.57% spine and 1.99% head injuries. Injuries consisted primarily of distortions (35.34%) and ligament tears (18.76%); 9,00% of all injuries were fractures. We found more skin wounds (6:1) and fractures (7:2) in male patients compared to females. The risk of ligament tears was highest during skiing. Three of four ski injuries led to knee problems. Spine injuries were observed most often during horse riding (1:6). Head injuries were seen in bicycle accidents (1:3). Head injuries were seen in male patients much more often then in female patients (21:1). Fractures were noted during football (1:9), skiing (1:9), inline (2:3), and during school sports (1:11). Many adolescents participate in various sports. Notwithstanding the methodological problems with epidemiological data, there is no doubt about the large number of athletes sustain musculoskeletal injuries, sometimes serious. In most instances, the accident does not happened during professional sports and training. Therefore, school teachers and low league trainer play an important role preventing further accidence based on knowledge of individual risk patterns of different sports

Effect of BMP-12, TGF-β1 and autologous conditioned serum on growth factor expression in Achilles tendon healing

Purpose: Achilles tendon ruptures are devastating and recover slowly and incompletely. There is a great demand for biomolecular therapies to improve recovery, yet little is understood about growth factors in a healing tendon. Here, the role of growth factors during tendon healing in a rat model and their reaction to single and multiple growth factor treatment are explored. Methods: Rat tendons were transected surgically and resutured. The expression of bFGF, BMP-12, VEGF and TGF-β1 was assessed by immunohistochemical analysis one to 8weeks after surgery. Paracrine effects of TGF-β1 or BMP-12 added by adenoviral transfer, as well as the effect of autologous conditioned serum (ACS) on growth factor expression, were evaluated. Results: bFGF, BMP-12 and VEGF expression was highest 1week after transection. bFGF and BMP-12 declined during the remaining period whereas VEGF expression persisted. TGF-β1 expression dramatically increased after 8weeks. ACS treatment increased bFGF (P=0.007) and BMP-12 (P=0.004) expression significantly after 8weeks. Also overall expression of bFGF, BMP-12 and TGF-β1 regardless of time point was significantly greater than controls with ACS treatment (P<0.05). Both BMP-12 and TGF-β1 treatments had no significant effect. No effect was observed in VEGF with any treatment. Conclusion: bFGF, BMP-12, VEGF and TGF-β1 are differentially expressed during tendon healing. Additional BMP-12 or TGF-β1 has no significant influence, whereas ACS generally increases expression of all factors except VEGF. Staged application of multiple growth factors may be the most promising biomolecular treatmen

Probing the Halo From the Solar Vicinity to the Outer Galaxy: Connecting Stars in Local Velocity Structures to Large-Scale Clouds

(Abridged) This paper presents the first connections made between two local features in velocity-space found in a survey of M giant stars and stellar spatial inhomogeneities on global scales. Comparison to cosmological, chemodynamical stellar halo models confirm that the M giant population is particularly sensitive to rare, recent and massive accretion events. These events can give rise to local observed velocity sequences - a signature of a small fraction of debris from a common progenitor, passing at high velocity through the survey volume, near the pericenters of their eccentric orbits. The majority of the debris is found in much larger structures, whose morphologies are more cloud-like than stream-like and which lie at the orbital apocenters. Adopting this interpretation, the full-space motions represented by the observed velocity features are derived under the assumption that the members within each sequence share a common velocity. Orbit integrations are then used to trace the past and future trajectories of these stars across the sky revealing plausible associations with large, previously-discovered, cloud-like structures. The connections made between nearby velocity structures and these distant clouds represent preliminary steps towards developing coherent maps of such giant debris systems. These maps promise to provide new insights into the origin of debris clouds, new probes of Galactic history and structure, and new constraints on the high-velocity tails of the local dark matter distribution that are essential for interpreting direct detection experiments.Comment: submitted to the Astrophysical Journal, 40 pages, 13 figure