2,326 research outputs found
X-ray diffraction from bone employing annular and semi-annular beams
This is the final version of the article. Available from the publisher via the DOI in this record.There is a compelling need for accurate, low cost diagnostics to identify osteo-tissues that are associated with a high risk of fracture within an individual. To satisfy this requirement the quantification of bone characteristics such as 'bone quality' need to exceed that provided currently by densitometry. Bone mineral chemistry and microstructure can be determined from coherent x-ray scatter signatures of bone specimens. Therefore, if these signatures can be measured, in vivo, to an appropriate accuracy it should be possible by extending terms within a fracture risk model to improve fracture risk prediction.In this preliminary study we present an examination of a new x-ray diffraction technique that employs hollow annular and semi-annular beams to measure aspects of 'bone quality'. We present diffractograms obtained with our approach from ex vivo bone specimens at Mo Kα and W Kα energies. Primary data is parameterized to provide estimates of bone characteristics and to indicate the precision with which these can be determined.We acknowledge gratefully the funding provided by the UK Engineering and Physical
Sciences Research Council (EPSRC) grant number EP/K020196/
Energy-dispersive X-ray diffraction using an annular beam
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.We demonstrate material phase identification by measuring polychromatic diffraction spots from samples at least 20 mm in diameter and up to 10 mm thick with an energy resolving point detector. Within our method an annular X-ray beam in the form of a conical shell is incident with its symmetry axis normal to an extended polycrystalline sample. The detector is configured to receive diffracted flux transmitted through the sample and is positioned on the symmetry axis of the annular beam. We present the experiment data from a range of different materials and demonstrate the acquisition of useful data with sub-second collection times of 0.5 s; equating to 0.15 mAs. Our technique should be highly relevant in fields that demand rapid analytical methods such as medicine, security screening and non-destructive testing.We acknowledge gratefully the funding provided by the UK Engineering and Physical
Sciences Research Council (EPSRC) grant number EP/K020196/1
AdS Black Hole Solutions in the Extended New Massive Gravity
We have obtained (warped) AdS black hole solutions in the three dimensional
extended new massive gravity. We investigate some properties of black holes and
obtain central charges of the two dimensional dual CFT. To obtain the central
charges, we use the relation between entropy and temperature according to the
AdS/CFT dictionary. For AdS black holes, one can also use the central charge
function formalism which leads to the same results.Comment: 24pages, some organization corrected, minor corrections, references
added, final published versio
Thermodynamics of a class of non-asymptotically flat black holes in Einstein-Maxwell-Dilaton theory
We analyse in detail the thermodynamics in the canonical and grand canonical
ensembles of a class of non-asymptotically flat black holes of the
Einstein-(anti) Maxwell-(anti) Dilaton theory in 4D with spherical symmetry. We
present the first law of thermodynamics, the thermodynamic analysis of the
system through the geometrothermodynamics methods, Weinhold, Ruppeiner,
Liu-Lu-Luo-Shao and the most common, that made by the specific heat. The
geometric methods show a curvature scalar identically zero, which is
incompatible with the results of the analysis made by the non null specific
heat, which shows that the system is thermodynamically interacting, does not
possess extreme case nor phase transition. We also analyse the local and global
stability of the thermodynamic system, and obtain a local and global stability
for the normal case for 0<\gamma<1 and for other values of \gamma, an unstable
system. The solution where \gamma=0 separates the class of locally and globally
stable solutions from the unstable ones.Comment: 18 pages, version accepted for publication in General Relativity and
Gravitatio
Continuous Hawking-Page transitions in Einstein-scalar gravity
We investigate continuous Hawking-Page transitions in Einstein's gravity
coupled to a scalar field with an arbitrary potential in the weak gravity
limit. We show that this is only possible in a singular limit where the
black-hole horizon marginally traps a curvature singularity. Depending on the
subleading terms in the potential, a rich variety of continuous phase
transitions arise. Our examples include second and higher order, including the
Berezinskii-Kosterlitz-Thouless type. In the case when the scalar is dilaton,
the condition for a continuous phase transition lead to (asymptotically)
linear-dilaton background. We obtain the scaling laws of thermodynamic
functions, as well as the viscosity coefficients near the transition. In the
limit of weak gravitational interactions, the bulk viscosity asymptotes to a
universal constant, independent of the details of the scalar potential. As a
byproduct of our analysis we obtain a one-parameter family of kink solutions in
arbitrary dimension d that interpolate between AdS near the boundary and
linear-dilaton background in the deep interior. The continuous Hawking-Page
transitions found here serve as holographic models for normal-to superfluid
transitions.Comment: 35 pages + appendice
Warped black holes in 3D general massive gravity
We study regular spacelike warped black holes in the three dimensional
general massive gravity model, which contains both the gravitational
Chern-Simons term and the linear combination of curvature squared terms
characterizing the new massive gravity besides the Einstein-Hilbert term. The
parameters of the metric are found by solving a quartic equation constrained by
an inequality that imposes the absence of closed timelike curves. Explicit
expressions for the central charges are suggested by exploiting the fact that
these black holes are discrete quotients of spacelike warped AdS(3) and a known
formula for the entropy. Previous results obtained separately in topological
massive gravity and in new massive gravity are recovered as special cases.Comment: 38 pages, 7 figures. v2: minor changes, added refs and an appendix on
self-dual and null z-warped black hole
Conservation implications of the mating system of the Pampa Hermosa landrace of peach palm analyzed with microsatellite markers
Peach palm (Bactris gasipaes) is cultivated by many indigenous and traditional communities from Amazonia to Central America for its edible fruits, and is currently important for its heart-of-palm. The objective of this study was to investigate the mating system of peach palm, as this is important for conservation and breeding. Eight microsatellite loci were used to genotype 24 open-pollinated progenies from three populations of the Pampa Hermosa landrace maintained in a progeny trial for genetic improvement. Both the multi-locus outcrossing rates (0.95 to 0.99) and the progeny level multi-locus outcrossing rates (0.9 to 1.0) were high, indicating that peach palm is predominantly allogamous. The outcrossing rates among relatives were significantly different from zero (0.101 to 0.202), providing evidence for considerable biparental inbreeding within populations, probably due to farmers planting seeds of a small number of open-pollinated progenies in the same plot. The correlations of paternity estimates were low (0.051 to 0.112), suggesting a large number of pollen sources (9 to 20) participating in pollination of individual fruit bunches. Effective population size estimates suggest that current germplasm collections are insufficient for long-term ex situ conservation. As with most underutilized crops, on farm conservation is the most important component of an integrated conservation strategy
Rural waste generation: a geographical survey at local scale
"The paper examines the per capita waste generation rates from from rural areas of NeamÈ› County (Romania) using thematic cartography. Geographical approach of this issue is difficult because the lack of a geostatistic database at commune scale. Spatial analysis of waste indicators reveals several disparities between localities. Comparability of data between communes located in various geographical conditions must be carrefully made according to local waste management systems. Several dysfunctionalities are outlined in order to compare these results, on the one hand, between localities and on the one hand, between recent years. Geographical analysis of waste generation rates is imperative for a proper monitoring of this sector. Data from 2009, 2010 and 2012 shows that rural waste management is in a full process of change towards a more organized, stable and efficient system." (author's abstract
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