H2S paper strip method - A bacteriological test for faecal coliforms in drinking water at various temperatures

Epidemics arising from waterborne diseases are a global health problem. Faecal contamination of drinking water is the main cause of these outbreaks. According to WHO (1996) for drinking water to be safe, a 100 ml sample should not contain any coliform bacteria. The standard methods currently used for routine testing have many limitations especially when applied in remote areas. The H2S method has been developed as an on-site, inexpensive and easy to use method to test drinking water for remote and rural areas. The present work analyses the reliability of the H2S method for detecting faecal contamination in drinking water. The minimum level of faecal coliforms that could be detected and the incubation period required at various levels of contamination were studied. The range of temperatures at which the method was effective and the incubation period required at various temperatures were also determined. The H2S method was found to be able to detect contamination down to a level of 1 CFU/100 ml of coliform bacteria. Although the H2S method could be used at a temperature range of 20 to 44oC, temperatures between 28 to 37oC gave faster results. An incubation period of only 24 hours was required at 37oC, which was found to be the most suitable incubation temperature. The incubation period increased with a decrease or increase in temperature

Elastic Scattering of Pions From the Three-nucleon System

We examine the scattering of charged pions from the trinucleon system at a pion energy of 180 MeV. The motivation for this study is the structure seen in the experimental angular distribution of back-angle scattering for pi+ 3He and pi- 3H but for neither pi- 3He nor pi+ 3H. We consider the addition of a double spin flip term to an optical model treatment and find that, though the contribution of this term is non-negligible at large angles for pi+ 3He and pi- 3H, it does not reproduce the structure seen in the experiment.Comment: 15 pages + 5 figure

An intermediate state between the kagome-ice and the fully polarized state in Dy2_2Ti2_2O7_7

Dy$_2$Ti$_2$O$_7$ is at present the cleanest example of a spin-ice material. Previous theoretical and experimental work on the first-order transition between the kagome-ice and the fully polarized state has been taken as a validation for the dipolar spin-ice model. Here we investigate in further depth this phase transition using ac-susceptibility and dc-magnetization, and compare this results with Monte-Carlo simulations and previous magnetization and specific heat measurements. We find signatures of an intermediate state between the kagome-ice and full polarization. This signatures are absent in current theoretical models used to describe spin-ice materials.Comment: 7 pages, 4 figure

Monte Carlo Eikonal Scattering

Monte Carlo evaluation is used to calculate heavy-ion elastic scattering including the center-of-mass correction and the Coulomb interaction.Angular distributions are presented for a number of nuclear pairs over a wide energy range using nucleon-nucleon scattering parameters taken from phase-shift analyses and densities from independent sources. A technique for the efficient expansion of the Glauber amplitude in partial waves is developed

Convex Functions and Spacetime Geometry

Convexity and convex functions play an important role in theoretical physics. To initiate a study of the possible uses of convex functions in General Relativity, we discuss the consequences of a spacetime $(M,g_{\mu \nu})$ or an initial data set $(\Sigma, h_{ij}, K_{ij})$ admitting a suitably defined convex function. We show how the existence of a convex function on a spacetime places restrictions on the properties of the spacetime geometry.Comment: 26 pages, latex, 7 figures, improved version. some claims removed, references adde

Finite Density QCD in the Chiral Limit

We present the first results of an exact simulation of full QCD at finite density in the chiral limit. We have used a MFA (Microcanonical Fermionic Average) inspired approach for the reconstruction of the Grand Canonical Partition Function of the theory; using the fugacity expansion of the fermionic determinant we are able to move continuously in the ($\beta -\mu$) plane with $m=0$.Comment: 3 pages, LaTeX, 3 figures, uses espcrc2.sty, psfig. Talk presented by A. Galante at Lattice 97. Correction of some reference

Frustration in Finite Density QCD

We present a detailed analysis of the QCD partition function in the Grand Canonical formalism. Using the fugacity expansion we find evidence for numerical instabilities in the standard evaluation of its coefficients. We discuss the origin of this problem and propose an issue to it. The correct analysis shows no evidence for a discontinuity in the baryonic density in the strong coupling limit. The moderate optimism that was inspired by the Grand Canonical Partition Function calculations in the last years has to be considered ill-founded.Comment: 9 pages, 6 Postscript figures; some comments adde

Discipline-Specific Compared to Generic Training of Teachers in Higher Education

A recurrent theme arising in the higher education sector is the suitability and effectiveness of generic versus discipline-specific training of university teachers, who are often recruited based on their disciplinary specialties to become teachers in higher education. We compared two groups of participants who had undergone training using a generic post-graduate certificate in higher education (PGCertGeneric) versus a discipline-specific course in veterinary education (PGCertVetEd). The study was conducted using a survey that allowed comparison of participants who completed PGCertGeneric (n=21) with PGCertVetEd (n=22). Results indicated that participants from both PGCertGeneric and PGCertVetEd considered teaching to be satisfying and important to their careers, valued the teaching observation component of the course, and identified similar training needs. However, the participants of the PGCertVetEd felt that the course made them better teachers, valued the relevance of the components taught, understood course design better, were encouraged to do further courses/reading in teaching and learning, changed their teaching as a result of the course, and were less stressed about teaching as compared to the PGCertGeneric participants (p<.05). It is likely that the PGCertVetEd, which was designed and developed by veterinarians with a wider understanding of the veterinary sector, helped the participants perceive the training course as suited to their needs

Charge Symmetry Violation Effects in Pion Scattering off the Deuteron

We discuss the theoretical and experimental situations for charge symmetry violation (CSV) effects in the elastic scattering of pi+ and pi- on deuterium (D) and 3He/3H. Accurate comparison of data for both types of targets provides evidence for the presence of CSV effects. While there are indications of a CSV effect in deuterium, it is much more pronounced in the case of 3He/3H. We provide a description of the CSV effect on the deuteron in terms of single- and double- scattering amplitudes. The Delta-mass splitting is taken into account. Theoretical predictions are compared with existing experimental data for pi-d scattering; a future article will speak to the pi-three nucleon case.Comment: 16 pages of RevTeX, 7 postscript figure

On a conjecture about Dirac's delta representation using q-exponentials

A new representation of Dirac's delta-distribution, based on the so-called q-exponentials, has been recently conjectured. We prove here that this conjecture is indeed valid