958 research outputs found
Land Use Land Cover Change within Kakum Conservation Area in the Assin South District of Ghana, 1991-2015
Kakum Conservation Area is roughly 1187km2, extending over large portions of forest reserves in the Assin South District of Ghana. The district hosts the remaining biodiversity hotspots within highly fragmented rainforest of West Africa. Although the conservation has been gazetted as protected area, it has since been impacted by illegal chainsaw logging, expanding agricultural land use and built construction to meet the housing needs of the rapidly growing population of the district. However, there is paucity of data on the magnitude, rate and types of land cover change occurring in the district. This study seeks to address these by examining the magnitude, the rate and direction of change in land cover between 1991 and 2015. The study objective was achieved using supervised classification and post classification change detection of remotely sensed Landsat satellite imagery of the district taken in 1991, 2001 and 2015. The results show that, within the study period, the population of the area increased by 2.9%, thick forest decreased by 8.2km2, light forest increased by 5.3km2 and built environment increased by 2.9km2 per annum. These results are considered potential hindrance to sustainable development, including biodiversity conservation in the forest reserves and climate change mitigation in general. There is therefore need for measures to end deforestation and stimulate reforestation of the lost forest cover. The district needs to initiate an enquiry into the effectiveness of the current forest reserve management practices and sustainability of land use systems in the district
Electronic inhomogeneity and Ag:Sb imbalance of Ag1−yPb18Sb1+zTe20 high-performance thermoelectrics elucidated by 125Te and 207Pb NMR
Using magic-angle spinning 125Te and 207Pb NMR, we have discovered the presence of two phases of approximately tenfold different free-electron concentration, n, in high-performance thermoelectrics Ag1−yPb18Sb1+zTe20 (“LAST-18”), proven by pairs of Knight-shifted NMR peaks and biexponential spin-lattice relaxation. The ratio of the phases is typically 2:1 with n ≈ 2 × 1019 cm−3 and 0.2 × 1019 cm−3, respectively, determined from the spin-lattice relaxation times. 125Te NMR spectra show that both phases contain similar concentrations of Sb. The low-n component is assigned to Ag-rich regions with Ag-Sb pairing (but not AgSbTe2), the dominant high-n component to PbTe:Sb resulting from the excess of Sb relative to Ag. The electronic inhomogeneity observed here must be considered in the search for a better understanding of high performance thermoelectric materials
Project 8 Phase III Design Concept
We present a working concept for Phase III of the Project 8 experiment,
aiming to achieve a neutrino mass sensitivity of ( C.L.)
using a large volume of molecular tritium and a phased antenna array. The
detection system is discussed in detail.Comment: 3 pages, 3 figures, Proceedings of Neutrino 2016, XXVII International
Conference on Neutrino Physics and Astrophysics, 4-9 July 2016, London, U
Results from the Project 8 phase-1 cyclotron radiation emission spectroscopy detector
The Project 8 collaboration seeks to measure the absolute neutrino mass scale
by means of precision spectroscopy of the beta decay of tritium. Our technique,
cyclotron radiation emission spectroscopy, measures the frequency of the
radiation emitted by electrons produced by decays in an ambient magnetic field.
Because the cyclotron frequency is inversely proportional to the electron's
Lorentz factor, this is also a measurement of the electron's energy. In order
to demonstrate the viability of this technique, we have assembled and
successfully operated a prototype system, which uses a rectangular waveguide to
collect the cyclotron radiation from internal conversion electrons emitted from
a gaseous Kr source. Here we present the main design aspects of the
first phase prototype, which was operated during parts of 2014 and 2015. We
will also discuss the procedures used to analyze these data, along with the
features which have been observed and the performance achieved to date.Comment: 3 pages; 2 figures; Proceedings of Neutrino 2016, XXVII International
Conference on Neutrino Physics and Astrophysics, 4-9 July 2016, London, U
Comment on "Evidence for Neutrinoless Double Beta Decay"
We comment on the recent claim for the experimental observation of
neutrinoless double-beta decay. We discuss several limitations in the analysis
provided in that paper and conclude that there is no basis for the presented
claim.Comment: A comment written to Modern Physics Letters A. 4 pages, no figures.
Updated version, accepted for publicatio
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