Hubble expansion variance and the cosmic rest frame

Average homogeneity is only reached on scales greater than 70{100h1Mpc yet standard peculiar velocity approaches assume an most Euclidean geometry below this scale. Furthermore, the Friedmann equation is applied in the nonlinear regime, although this has no motivation in the fundamental principles of general relativity. We investigate the variance of the Hubble expansion in a manner which makes no prior geometrical assumptions, other than the existence of a suitably averaged linear Hubble law. We use the COMPOSITE data set of 4534 galaxies [Watkins, Feldman and Hudson (2009)]

Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets

The spins of ten stellar black holes have been measured using the continuum-fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another that is transient. Both the persistent and transient black holes remain for long periods in a state where their spectra are dominated by a thermal accretion disk component. The spin of a black hole of known mass and distance can be measured by fitting this thermal continuum spectrum to the thin-disk model of Novikov and Thorne; the key fit parameter is the radius of the inner edge of the black hole's accretion disk. Strong observational and theoretical evidence links the inner-disk radius to the radius of the innermost stable circular orbit, which is trivially related to the dimensionless spin parameter a_* of the black hole (|a_*| < 1). The ten spins that have so far been measured by this continuum-fitting method range widely from a_* \approx 0 to a_* > 0.95. The robustness of the method is demonstrated by the dozens or hundreds of independent and consistent measurements of spin that have been obtained for several black holes, and through careful consideration of many sources of systematic error. Among the results discussed is a dichotomy between the transient and persistent black holes; the latter have higher spins and larger masses. Also discussed is recently discovered evidence in the transient sources for a correlation between the power of ballistic jets and black hole spin.Comment: 30 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher). Changes to Sections 5.2, 6.1 and 7.4. Section 7.4 responds to Russell et al. 2013 (MNRAS, 431, 405) who find no evidence for a correlation between the power of ballistic jets and black hole spi

Apical root resorption six and 12 months after initiation of fixed orthodontic appliance therapy

Contains fulltext : 48027.pdf (publisher's version ) (Open Access

Apical root resorption 6 months after initiation of fixed orthodontic appliance therapy.

Contains fulltext : 48020.pdf (publisher's version ) (Closed access)INTRODUCTION: Individual predisposition might be a major reason for the observed variation in apical orthodontic root resorption. If so, resorption might be expressed during the initial stages of orthodontic therapy in patients at risk. METHODS: To explore this hypothesis, we evaluated standardized, digitized periapical radiographs made before treatment (T1) and at a mean period of 6.4 months (SD 0.9) after placement of maxillary incisor brackets (T2) in 290 patients (age range, 10.1 to 57.1 years at T1). Anamnestic and treatment parameters were recorded according to a protocol, and maxillary incisor irregularity was measured on T1 study models. RESULTS: The mean average root resorption for 4 incisors was 0.53 mm (SD 0.47), whereas the sample mean of the most severely resorbed tooth per patient was 1.18 mm (SD 0.86). A total of 4.1% of the patients had an average resorption of 1.5 mm or more, and 15.5% had at least 1 tooth with 2.0 mm or more resorption. The maximum amount of resorption was 4.4 mm. Multivariate linear regression showed that deviated root form and increased T1-to-T2 time period were risk factors for apical root resorption of the central incisors; normal root form and wide roots were preventive factors, with an explained variance of 14%. Similarly, long roots, narrow roots, and increased T1-to-T2 time period were risk factors for resorption of the lateral incisors, whereas normal root form was a preventive factor, with an explained variance of 24%. Parameters associated with use of rectangular wire, presence of incisor irregularity, and history of trauma were not identified as risk factors. Use of elastics was not included in the regression analyses. CONCLUSIONS: Root resorption can begin in the early leveling stages of orthodontic treatment. About 4.1% of patients studied had an average resorption of 1.5 mm or more of the 4 maxillary incisors, and about 15.5% had 1 or more maxillary incisors with resorption of 2.0 mm or more from 3 to 9 months after initiation of fixed appliance therapy. Although teeth with long, narrow, and deviated roots are at increased risk of resorption during this early stage, the explained variance of these risk factors is less than 25%

Macroalgae and temperate rocky reefs

Thomas Wernberg, Alex Campbell, Melinda A. Coleman, Sean D. Connell, Gary A. Kendrick, Pippa J. Moore, Bayden D. Russell, Daniel A. Smale, Peter D. Steinber

Questionnaire survey on cardiologists' view and management of coronary microvascular disease in clinical practice

Contains fulltext : 203601.pdf (publisher's version ) (Open Access

New identities in the Catalan triangle.

In this paper we prove new identities in the Catalan triangle whose (n, p) entry is defined byB n, p : = frac(p, n) ((2 n; n - p)), n, p N, p n . In fact, we show some new identities involving the well-known Catalan numbers, and specially the identityunderover(, p = 1, i) B n, p B n, n + p - i (n + 2 p - i) = (n + 1) C n ((2 (n - 1); i - 1)), i n, that appears in a problem related with the dynamical behavior of a family of iterative methods applied to quadratic polynomials. © 2007 Elsevier Inc. All rights reserved

Farmers’ Subjective Valuation of Subsistence Crops: The Case of Traditional Maize in Mexico

Shadow prices guide farmers’ resource allocations, but for subsistence farmers who grow traditional crops they may bear little relationship with market prices. We theoretically derive shadow prices for a subsistence crop with nonmarket value, then estimate shadow prices of maize using data from a nationally representative survey of rural households in Mexico. Shadow prices are significantly higher than market prices for traditional but not improved maize varieties. They are particularly high in the indigenous areas of southern and southeastern Mexico, indicating large de facto incentives to maintain traditional varieties there. Copyright 2009, Oxford University Press.