A part of the survey programme on the evaluation of environmental radioactivity in Cameroon has just been initiated. The radioactivity level of soils in a volcanic area in Cameroon was determined and discussed. 30 soils samples were collected from Buea and Limbé cities located in the south-western Cameroon. These two regions are known for theirs volcanic grounds due to the presence of Mount Cam...

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We review the search for the top quark conducted by the DØ collaboration using data from the Fermilab pp collider. Based upon a preliminary analysis of an integrated luminosity of about 13.5 pb −1 , we have searched for tt production and decay in the experimental channels involving a pair of dileptons (e or µ) plus jets, or single leptons plus jets. Summed over all channels, we observe 7 events...

The ionizing spectral energy distribution of quasars exhibits a steepening of the distribution short-ward of 1200 Å. The change of the power-law index from approximately −1 to −2 so far has been interpreted as being intrinsic to quasars. We study an alternative interpretation, in which a tenuous absorption screen is responsible for the change of index. We find that the most successful function ...

This paper proposes a feature-based multi-sensor fire detector operating on ordinary video and long wave infrared (LWIR) thermal images. The detector automatically extracts hot objects from the thermal images by dynamic background subtraction and histogram-based segmentation. Analogously, moving objects are extracted from the ordinary video by intensity-based dynamic background subtraction. The...

We propose a variant of hybrid inflation which is applicable in a wide class of supersymmetric grand unified models. The observed temperature perturbations of cosmic background radiation can be reproduced with natural values of the parameters of the theory and a grand unification scale which is consistent with the unification of the minimal supersymmetric standard model gauge couplings as measu...

In order to draw out the essential behavior of the universe, investigations of early universe cosmology often reduce the complex system to a simple integrable system. Inflationary models are of this kind as they focus on simple scalar field scenarios with correspondingly simple dynamics. However, we can be assured that the universe is crowded with many interacting fields of which the inflaton i...