18,948 research outputs found
Microtremor response of a mass movement in Federal District of Brazil
The present study provides a brief description of the ambient noise recorded at a slow moving mass movement in Ribeirão Contagem Basin. The area is an interesting natural laboratory as river detachment processes in a number of different stages can be identified and are easily accessible. We investigate the site dynamic characteristics of the study area by recording ambient noise time-series at nine points, using portable nine three-component short period seismometers. The time-series are processed to give both horizontal to vertical spectral ratio (HVSR) curves as well as time-frequency plots of noise power spectral density (SPD). The HVSR curves illustrate and quantify aspects of site resonance effects due to underlying geology. Probability density function (PDF) shows that noise level lies well between new high noise model (NHNM) and new lower noise model (NLNM) and their probabilities are higher above 2 Hz. HVSR curves present a uniform lithologically controlled peak at 2 Hz. Directional properties of the wavefield are determined by beamforming method. The f-k analysis results in the E-W component show that at 5 Hz phase velocities are close to 1700 m/s while at 10 Hz dropped to 250 m/s. We observed that between 5 and 16 Hz the incoming wavefield arrive from 260 degrees. Further studies will apply a detailed noise analysis for the understanding of dynamics of the mass movement, which is triggered by the river erosion
Representation of South Asian people in randomised clinical trials: analysis of trials' data
Excluding patients of ethnic minority groups from clinical
trials is unethical, introduces substantial bias, and
means that findings are based on unrepresentative
populations. The National Institutes of Health Revitalization
Act 1993 requires that all minority groups be represented
in the sample in research projects supported
by the National Institutes of Health, unless there is a
clear and compelling justification not to do so. In the
United Kingdom no such legislation exists
Crisis Communication at Higher Education Institutions in South Africa: A Public Relations Perspective
The higher education sector has undergone dramatic restructuring through incorporations and mergers. This restructuring has led to the breakdown of apartheid racial divides and provided a vision of a single coordinated higher education system. In addition to opportunities various challenges have also emerged from these mergers. One such challenge is that higher education institutions may find themselves in tensions with their partners which may result in disagreements that could lead to crisis situations. In crisis situations, the pace of the conflict accelerates dramatically. This means that the affected parties have to react very quickly or risk having their ability to protect their interests substantially reduced. Implicit in this is the importance of communication. Often in a crisis situation, communication gets distorted; as a result rumors often supplant real facts. Thus, clear communication needs to be pre planned and increased during a crisis. The aim of this research is to investigate the role of communication during the planning and management of a crisis at higher education institutions in KwaZulu-Natal. A qualitative methodology was employed in this study. It reports on the preliminary results of in-depth interviews that were conducted at the four public higher education institutions in KwaZulu-Natal. Themes emanating from the literature review were used to develop an interview schedule which comprised of open-ended and closed-ended questions
Optimized identification of fecal pollution sources in a rural tidal watershed in coastal New Hampshire
Escherichia coli ribotyping was used to identify fecal contamination sources in Grommet Creek- a tidal creek that drains into Great Bay and contaminates shellfishing beds. Water samples were collected during late summer through late fall. Fecal samples were collected to establish a local source species database. Fecal indicator bacteria were enumerated from water samples and ribotyping was conducted by using EcoR1 restriction enzyme digestion and an automated RiboPrinter(c). There was consistent relative abundance between source types with wild animals and birds as the primary sources. An optimized approach for maximizing source identification involved using a 90% similarity threshold and prioritizing the first (local) database, then the second (larger area), and the third (regional) database for source identification. Using this approach, 67% of the E. coli water sample isolates were identified to sources, mainly as geese, deer, and fox, suggesting that diminishing of these sources could improve water quality
Acoustics-turbulence interaction
An investigation of the instability frequency was undertaken. Measurements revealed that the hot wire probe induces and sustains stable upstream oscillation of the free shear layer. The characteristics of the free shear layer tone are found to be different from the slit jet wedge edgetone phenomenon. The shear tone induced by a plane wedge in a plane free shear layer was then examined in order to further document the phenomenon. The eigenvalues and eigenfunctions of the tone fundamental show agreement with the spatial stability theory. A comprehensive summary of the results is also included
A new architecture for dynamic e-business database interoperability
There have been many approaches of data sharing in e-businesses, attempting at mapping each field at the source to its corresponding field at the target. These approaches eliminate the need for deriving the global schema and hence eliminate a substantial overhead. But, the approaches work out well only when both the source and the target databases have approximately the same content. Moreover, if some concepts of source do not have the counterpart fields in the target then the mapping will lose the concepts. This problem will be further aggregated by the mapping compositions and the large size of the databases. In this paper, we propose a framework to alleviate the interoperability problem
Maintaining the integrity of XML signatures by using the manifest element
One of the aims of providing 'security of data' in e-commerce transactions is making sure that the receiver receives the same data which the sender sends, that is the data has not been tampered in any way. To achieve this aim digital signatures are used. A digital signature helps in providing integrity, message authentication, and signer authentication for the signed data. An XML signature can contain or point to the data that is being signed. In this paper we discuss a possible solution of avoiding a signature from breaking when there is a change in the location of the document after it has been signed
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