A study of canine and equine skeletal muscle

(1) This study compares Greyhounds and Thoroughbreds - breeds selected for high speed running - with other breeds of their species by gross dissection, histometric and histochemical and biochemical methods, to Identify adaptations which would favour their superior athletic capacity. Skeletal muscle has been the primary tissue of interest because of its power-generating nature.(2) Carcass dissection was carried out on 44 Greyhounds from blrthweight to 37 kg, 31 other dogs from blrthweight to 47 kg, 30 Thoroughbreds from 0*69 kg to 509 kg and 33 other horses from 2*2 to 547 kg liveweight.(2a) Measurements on the humerus, radius and ulna, femur and tibia and fibula Indicated that their combined lengths were not different in Greyhounds and other dogs, but tended to be longer in adult Thoroughbreds than in adult other horses.(2b) Within limb variations in bone lengths were not apparent between breeds. However the eplpodial segment in dogs and the propodial segment in horses grows faster.(2c) There is no difference in fresh bone density between the itypes of dog and horse, but dog bones tend to be more dense than horse bones.(2d) The proportions of muscle, bone and fat relative to liveweight were compared between athletes and others in adults and during growth. In adults the most functionally significant difference is that muscle occupies a greater proportion of liveweight in athletes. Adult Greyhounds have less fat than other dogs while bone weight forms a remarkably similar proportion of liveweight in all adult dogs and horses. In athletes there is a greater growth rate of muscle which explains the difference in adult proportions. Growth changes in muscle distribution explain the greater propulsive capacity of the Greyhound spinal column and femoral region and of the Thoroughbred hindlimb. It is also compatible with the potentially higher stride frequency of the Greyhound hindlimb.(2e) Athletes tend to have heavier hearts than non-athletes at adult llveweights, despite the lower growth rate of the heart in athletes.(3) In all 33 Greyhounds from birth to 37 kg, 26 other dogs from birth to 47 kg, 34 Thoroughbreds from 11 kg to 598 kg and 34 other horses from 2*3 to 560 kg liveweight were used for histometric and biochemical assay, of samples of their m. semitendinosus, m. diaphragms and m. pectoralis transversus. Mean fibre areas were established in samples of all three muscles, and in m. semitendinosus only the transverse sectional area and total number of fibres in it were also estimated. Histochemical profiles of Individual fibres were estimated using myosin adenosine triphosphate (myosin ATPase), succinate dehydrogenase (SDHase), and glycogen phosphorylase (GPase) reactions; capillaries were also demonstrated using a modification of the myosin ATPase reaction.(3a) Athletes have more larger fibres in m. semitendinosus than non-athletes. The mean fibre area of m. dlaphragma is also larger in Greyhounds and Thoroughbreds than in their fellows but the mean fibre area of m. pectoralis transversus is similar in the two types of animal within each species. Although the mean fibre area of corresponding muscles is significantly larger in horses than in dogs the difference is not related to their liveweight difference.(3b) The major histochemical difference between fibres is their myosin ATPase activity, which differentiates them according to whether they have a high or low activity. In adult dog muscle, all fibres have a high SDHase activity and myosin ATPase low-reacting fibres have a low activity of GPase. In adult horse muscle all fibres have a high activity of GPase. In m. dlaphragma and m. pectoralis transversus all fibres also have a high SDHase activity so that only the myosin ATPase reaction differentiates fibres in these muscles, however fibres with a low activity of SDHase are present in samples of m. semitendinosus.(3c) The myosin ATPase reaction differentiates fibres at the earliest stage of growth observed. The GPase and SDHase activities gradually develop from an amorphous staining pattern in the young to the appropriate adult type. The proportional area of myosin ATPase low-reacting fibres in the three muscles studied is related to liveweight from birth to near adulthood. Thereafter the relationship is less obvious in "athletes" than "non-athletes.(3d) There is a greater proportional area of myosin ATPase high-reacting fibres in the limb muscles of both Greyhounds and Thoroughbreds and in m. diaphragma of Greyhounds. In adults this feature does not appear to be due to training as are alterations in aerobic and anaerobic capacity. This dissimilarity (in the proportions of muscles occupied by myosin ATPase high-reacting fibres) suggests that there may be differences in the nervous systems of athletes and non-athletes.(3e) It is concluded that the proportions of fibre types in muscles are related to the function of muscles and its parts. Although the proportions of fibre types in different muscles and parts of muscles and in different types of animals resemble those of adults at the earliest stages investigated, histochemical evidence has been obtained which suggests transformation of the physiological properties of fibres as a normal occurrence but to differing extents during growth of normal athletes and non-athletes.(3f) Capillary density is remarkably similar between muscles of all groups of animals at all except very early stages of growth.(4) The biochemical estimation of SDHase activity does not show a within species difference is the adult but indicates an increase in activity in both species during growth. It has also been found that there is a greater aerobic activity in m. diaphragma than in the other two muscles and a greater activity in the deep medial than in the superficial lateral region of m. semitendinosus.(5) M. longissimus is proportionally lighter in Greyhounds taken out of training than in others. Such specimens have a greater myosin ATPase high-reacting fibre area in their m. diaphragma and lesser capillary density in their m. pectoralis transversus than trained Greyhounds.(6) The crosses of Thoroughbreds with other horses, show anatomical properties more like Thoroughbreds than non-athletic horses.(7) The results are discussed in relation to stride length and frequency. It is suggested that in adult athletes enhanced stride length is favoured by longer limbs in horses, and a greater acceleration capacity in both species. A higher natural frequency of the Greyhound hindlimb, and a greater intrinsic speed of sarcomere contraction in the athletes of both species favour enhanced stride frequency. The combination of these endowments aids a greater maximum speed of running in both Greyhounds and Thoroughbreds when compared with their fellows

Efficient Photometric Selection of Quasars from the Sloan Digital Sky Survey: 100,000 z<3 Quasars from Data Release One

We present a catalog of 100,563 unresolved, UV-excess (UVX) quasar candidates to g=21 from 2099 deg^2 of the Sloan Digital Sky Survey (SDSS) Data Release One (DR1) imaging data. Existing spectra of 22,737 sources reveals that 22,191 (97.6%) are quasars; accounting for the magnitude dependence of this efficiency, we estimate that 95,502 (95.0%) of the objects in the catalog are quasars. Such a high efficiency is unprecedented in broad-band surveys of quasars. This ``proof-of-concept'' sample is designed to be maximally efficient, but still has 94.7% completeness to unresolved, g<~19.5, UVX quasars from the DR1 quasar catalog. This efficient and complete selection is the result of our application of a probability density type analysis to training sets that describe the 4-D color distribution of stars and spectroscopically confirmed quasars in the SDSS. Specifically, we use a non-parametric Bayesian classification, based on kernel density estimation, to parameterize the color distribution of astronomical sources -- allowing for fast and robust classification. We further supplement the catalog by providing photometric redshifts and matches to FIRST/VLA, ROSAT, and USNO-B sources. Future work needed to extend the this selection algorithm to larger redshifts, fainter magnitudes, and resolved sources is discussed. Finally, we examine some science applications of the catalog, particularly a tentative quasar number counts distribution covering the largest range in magnitude (14.2<g<21.0) ever made within the framework of a single quasar survey.Comment: 35 pages, 11 figures (3 color), 2 tables, accepted by ApJS; higher resolution paper and ASCII version of catalog available at http://sdss.ncsa.uiuc.edu/qso/nbckde

SDSS Standard Star Catalog for Stripe 82: the Dawn of Industrial 1% Optical Photometry

We describe a standard star catalog constructed using multiple SDSS photometric observations (at least four per band, with a median of ten) in the $ugriz$ system. The catalog includes 1.01 million non-variable unresolved objects from the equatorial stripe 82 ($|\delta_{J2000}|<$ 1.266$^\circ$) in the RA range 20h 34m to 4h 00m, and with the corresponding $r$ band (approximately Johnson V band) magnitudes in the range 14--22. The distributions of measurements for individual sources demonstrate that the photometric pipeline correctly estimates random photometric errors, which are below 0.01 mag for stars brighter than (19.5, 20.5, 20.5, 20, 18.5) in $ugriz$, respectively (about twice as good as for individual SDSS runs). Several independent tests of the internal consistency suggest that the spatial variation of photometric zeropoints is not larger than $\sim$0.01 mag (rms). In addition to being the largest available dataset with optical photometry internally consistent at the $\sim$1% level, this catalog provides practical definition of the SDSS photometric system. Using this catalog, we show that photometric zeropoints for SDSS observing runs can be calibrated within nominal uncertainty of 2% even for data obtained through 1 mag thick clouds, and demonstrate the existence of He and H white dwarf sequences using photometric data alone. Based on the properties of this catalog, we conclude that upcoming large-scale optical surveys such as the Large Synoptic Survey Telescope will be capable of delivering robust 1% photometry for billions of sources.Comment: 63 pages, 24 figures, submitted to AJ, version with correct figures and catalog available from http://www.astro.washington.edu/ivezic/sdss/catalogs/stripe82.htm

The Milky Way Tomography with SDSS: III. Stellar Kinematics

We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r<20 and proper-motion measurements derived from SDSS and POSS astrometry, including ~170,000 stars with radial-velocity measurements from the SDSS spectroscopic survey. Distances to stars are determined using a photometric parallax relation, covering a distance range from ~100 pc to 10 kpc over a quarter of the sky at high Galactic latitudes (|b|>20 degrees). We find that in the region defined by 1 kpc <Z< 5 kpc and 3 kpc <R< 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby ($Z<1$ kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (<100 pc), we detect a multimodal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and LSST.Comment: 90 pages, 26 figures, submitted to Ap

The Milky Way Tomography With SDSS. III. Stellar Kinematics

We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r 20 degrees). We find that in the region defined by 1 kpc < Z < 5 kpc and 3 kpc < R < 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby (Z < 1 kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (< 100 pc), we detect a multi-modal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity-ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and the Large Synoptic Survey Telescope.NSF AST-615991, AST-0707901, AST-0551161, AST-02-38683, AST-06-07634, AST-0807444, PHY05-51164NASA NAG5-13057, NAG5-13147, NNXO-8AH83GPhysics Frontier Center/Joint Institute for Nuclear Astrophysics (JINA) PHY 08-22648U.S. National Science FoundationMarie Curie Research Training Network ELSA (European Leadership in Space Astrometry) MRTN-CT-2006-033481Fermi Research Alliance, LLC, United States Department of Energy DE-AC02-07CH11359Alfred P. Sloan FoundationParticipating InstitutionsJapanese MonbukagakushoMax Planck SocietyHigher Education Funding Council for EnglandMcDonald Observator

Characterization of M,L and T dwarfs in the Sloan Digital Sky Survey

An extensive sample of M, L and T dwarfs identified in the Sloan Digital Sky Survey (SDSS) has been compiled. The sample of 718 dwarfs includes 677 new objects (629 M dwarfs, 48 L dwarfs) together with 41 that have been previously published. All new objects and some of the previously published ones have new optical spectra obtained either with the SDSS spectrographs or with the Apache Point Observatory 3.5m ARC telescope. Spectral types and SDSS colors are available for all objects; approximately 35% also have near-infrared magnitudes measured by 2MASS or on the Mauna Kea system. We use this sample to characterize the color--spectral type and color--color relations of late type dwarfs in the SDSS filters, and to derive spectroscopic and photometric parallax relations for use in future studies of the luminosity and mass functions based on SDSS data. We find that the (i*-z*) and (i*-J) colors provide good spectral type and absolute magnitude (M_i*) estimates for M and L dwarfs. Our distance estimates for the current sample indicate that SDSS is finding early M dwarfs out to about 1.5 kpc, L dwarfs to approximately 100 pc and T dwarfs to near 20 pc. The T dwarf photometric data show large scatter and are therefore less reliable for spectral type and distance estimation.Comment: 46 pages, 14 figures (24 pages of figures), Accepted for publication in the Astronomical Journa

A New Very Cool White Dwarf Discovered by the Sloan Digital Sky Survey

Early data taken during commissioning of the SDSS have resulted in the discovery of a very cool white dwarf. It appears to have stronger collision induced absorption from molecular hydrogen than any other known white dwarf, suggesting it has a cooler temperature than any other. While its distance is presently unknown, it has a surprisingly small proper motion, making it unlikely to be a halo star. An analysis of white dwarf cooling times suggests that this object may be a low-mass star with a helium core. The SDSS imaging and spectroscopy also recovered LHS 3250, the coolest previously known white dwarf, indicating that the SDSS will be an effective tool for identifying these extreme objects.Comment: 15 pages, including 5 figures. Accepted for Astrophysical Journal Letter

The Milky Way Tomography with SDSS: II. Stellar Metallicity

Using effective temperature and metallicity derived from SDSS spectra for ~60,000 F and G type main sequence stars (0.2<g-r<0.6), we develop polynomial models for estimating these parameters from the SDSS u-g and g-r colors. We apply this method to SDSS photometric data for about 2 million F/G stars and measure the unbiased metallicity distribution for a complete volume-limited sample of stars at distances between 500 pc and 8 kpc. The metallicity distribution can be exquisitely modeled using two components with a spatially varying number ratio, that correspond to disk and halo. The two components also possess the kinematics expected for disk and halo stars. The metallicity of the halo component is spatially invariant, while the median disk metallicity smoothly decreases with distance from the Galactic plane from -0.6 at 500 pc to -0.8 beyond several kpc. The absence of a correlation between metallicity and kinematics for disk stars is in a conflict with the traditional decomposition in terms of thin and thick disks. We detect coherent substructures in the kinematics--metallicity space, such as the Monoceros stream, which rotates faster than the LSR, and has a median metallicity of [Fe/H]=-0.96, with an rms scatter of only ~0.15 dex. We extrapolate our results to the performance expected from the Large Synoptic Survey Telescope (LSST) and estimate that the LSST will obtain metallicity measurements accurate to 0.2 dex or better, with proper motion measurements accurate to ~0.2 mas/yr, for about 200 million F/G dwarf stars within a distance limit of ~100 kpc (g<23.5). [abridged]Comment: 40 pages, 21 figures, emulateApJ style, accepted to ApJ, high resolution figures are available from http://www.astro.washington.edu/ivezic/sdss/mw/astroph0804.385