Ammonia production by human faecal bacteria, and the enumeration, isolation and characterization of bacteria capable of growth on peptides and amino acids

DA - 20130125 IS - 1471-2180 (Electronic) IS - 1471-2180 (Linking) LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't SB - IMPeer reviewedPublisher PD

Fotografía de Anthony Wallace

  I have been a photojournalist with Agence France-Presse (AFP) in Hong Kong for three years.Desde hace tres años soy fotoperiodista de la Agencia France-Presse (AFP) en Hong Kong. 

Deuteron Photodisintegration at Intermediate Energies

This thesis describes an experiment whose aim was to measure the angular differential cross-section d2s/dpdEt for the two-body photodisintegration of the deuteron D(t,p)n at photon energies in the region of 140 MeV. The experiment was performed using the Glasgow tagged photon spectrometer which was installed at the Mainz Institut fur Kernphysik to take advantage of the high quality d. c. electron beam provided by the racetrack microtron MAMI-A. The experimental work and subsequent data analysis took place in the period from March 1986 to December 1988. The motivation for the project was provided by the recent renewal of theoretical interest in the deuteron photodisintegration reaction which has lead to a call for new and more reliable data on the process. The significance of the reaction lies in its use as a test case for the application of modern models of the N --- N interaction. Such models seek to describe the nuclear force in terms of the underlying hadronic dynamics of the nucleon-meson system as opposed to the essentially phenomenological parameterisations which have been used previously. Photons, both real and virtual, provide the ideal tool for such studies since the electromagnetic interaction is the best understood of all the elementary processes. The experiment was performed with a 0.45 g cm-2 liquid deuterium target cell placed in a tagged photon beam with a total intensity of 10e7 s-1 in the range Et=133 --- 158MeV. Protons were detected in a large solid angle (0. 9 steradian) position sensitive plastic scintillator telescope which had an energy resolution of 5% and an angular resolution of 3. Measurement of the proton energy and angle together with knowledge of photon energy overdefined the reaction kinematics thus facilitating a very clean rejection of background events. Reliable normalisation was assisted by the tagging technique which determined the photon flux to +/-1%. A complete Monte Carlo simulation of the experiment was developed in order to evaluate the systematic corrections to the data. Included in the simulation are effects due to the beam-target geometry, energy losses of the protons in the target, energy deposition in the detector, light production non-linearities and nuclear interactions of the protons in the CH scintillator medium, and also variations in the light collection efficiency throughout the scintillator blocks. The monte carlo simulation produces an efficiency correction factor specific to each data point, as well as providing global normalisation factors to account for the tagging efficiency and the combination of beam and target geometries. The data is presented in the form of two angular distributions corresponding to mean photon energies of 140 and 150 MeV. The total systematic error is estimated to be not greater than 6 %. The results are found to be in good general agreement with other recent experiments but it is observed that none of the available theoretical calculations can give a fully satisfactory account of the data

An experimental investigation of laminar free convection heat transfer form the surface of a vertical circular cylinder

M.S.Charles W. Gorto

Optimizing multi-dimensional terahertz imaging analysis for colon cancer diagnosis

Peer reviewedPublisher PD

Educator’s Perceptions of the Impacts of School Violence on Caribbean Societies

Globally, school violence plays an ominous role in the education process as it has been widely recognized as having negative impacts. In this context, education in a violence-free environment is a challenge facing some schools, students and teachers in the Caribbean. Internationally, school violence is a relatively well researched area, however, both internationally and in the Caribbean, educator’s perceptions of the impacts of school violence is relatively understudied. This study explores educator’s perceptions of the impacts of school violence on Caribbean societies and offers an interpretive exploration of these perceptions. Self-administered questionnaires were randomly distributed to educators in Antigua and Barbuda, Barbados, Jamaica, St. Lucia, St. Vincent and the Grenadines and Trinidad and Tobago. To analyze the data, frequency distribution was used and the data converted into percentages. The results gleaned from one hundred and twenty respondents indicate that school violence has impacts at the individual, institutional and community levels

How to Buy a Continent: The Protocols of Indian Treaties as Developed by Benjamin Franklin and Other Members of the American Philosophical Society

In 1743, when Benjamin Franklin announced the formation of an American Philosophical Society for the Promotion of Useful Knowledge, it was important for the citizens of Pennsylvania to know more about their American Indian neighbors. Beyond a slice of land around Philadelphia, three quarters of the province were still occupied by the Delaware and several other Indian tribes, loosely gathered under the wing of an Indian confederacy known as the Six Nations. Relations with the Six Nations and their allies were being peacefully conducted in a series of so-called “Indian Treaties” that dealt with the fur trade, threats of war with France, settlement of grievances, and the purchase of land

VUV Optical Properties of Rare Earth Doped YPO4 Prepared by Different Routes

The optical properties of nanocrystalline YPO4:Ln3+ (Ln = Eu, Sm, Tb) prepared via co-precipitation are compared to larger crystallites of YPO4:Ln3+ prepared via traditional solid state reaction. In larger crystals (~330 nm) a distinct peak is observed at 150 nm in the excitation spectra, the intensity of which decreases markedly in smaller crystals (~20 nm). Using excitation and reflectance spectroscopy, host–to–activator energy transfer efficiencies were calculated for Y1-xPO4:Lnx3+ (0.01 ≤ x ≤ 0.10). From the transfer efficiency data, we estimate that trapping by Eu3+ and Sm3+ is at least five times more efficient than trapping by Tb3+ for excitation at the band edge. The fraction of energy lost to the surface or grain boundaries for excitation at 150 nm and 138 nm is also estimated. We propose that in the samples prepared via co-precipitation, an amorphous phase forms at grain boundaries that is responsible for the loss of efficiency under 150 nm excitation