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Search Results: 1 - 10 of 401475 matches for " M Wallis "
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Digital mammography in the United Kingdom: the reality
M Wallis
Breast Cancer Research , 2006, DOI: 10.1186/bcr1418
Abstract: To date, all the equipment has been technically satisfactory and produces good image quality at an acceptable dose. Several units have been shown to work on mobile vans. Translating this into safe and affordable screening has been less successful.No full-field digital mammography machine will work at its best without patient archiving and communications systems and a radiology information system. Integration into the current Information Technology structures has been hampered by parallel development and implementation work on the national Information Technology programme and a national reluctance to spend local money on short-term fixes.The current differences in cost will not be offset by savings in film and film-handling processes, so improvements in throughput (i.e. shorter appointments and/or longer days) are required, and this has not been fully addressed.
Production, purification and characterization of two recombinant DNA-derived N-terminal ovine growth hormone variants: oGH3 and oGH5
AJ Sami, OC Wallis, M Wallis
African Journal of Biotechnology , 2008,
Abstract: Two recombinant DNA-derived variants of ovine growth hormone were produced, purified, characterized and compared with the authentic pituitary derived GH. The variants oGH3 and oGH5 were isolated by differential centrifugation method and were purified after refolding by ion-exchange chromatography and gel filtration. Both the proteins showed single band on SDS-PAGE and had molecular weight and iso-electric point closer to authentic pituitary GH. The variants oGH3 and oGH5 were compared with the authentic pituitary derived GH in radio immuno assays, radio receptor assays and binding with the monoclonal antibodies OA 11 and OA12.
Workload and casemix in Cape Town emergency departments
L A Wallis, M Twomey
South African Medical Journal , 2007,
Abstract: Introduction. Little is known about the nature of patients presenting to emergency departments (EDs) in South Africa. This study aimed to provide evidence on ED usage in Cape Town by studying patients at four community health centre (CHC) EDs, with details of the severity of their presentation and their disposal. Methods. A total of 16 392 patients presented in this 8-week prospective observational study, and 15 681 were included in the descriptive data analysis. One-quarter were children. Results. There were clear and predictable peaks in attendance after 16h00 and at weekends, with a steady stream of patients presenting overnight. Case severity was evenly distributed between emergency, urgent and routine care. Nearly 10% of patients were referred on to a higher level of care. Conclusion. The data from this study present a model for staffing and resource allocation. It has implications for the provision of emergency care in CHC EDs. South African Medical Journal Vol. 97 (12) 2007: pp.1276-1280.
Using Host-Specificity of Cryptosporidium to Understand Contaminant Sources, Seasonality, and Human Health Risk in Three Watersheds of Differing Land-Use  [PDF]
Janis L. Thomas, Katarina D. M. Pintar, Peter M. Wallis, Norman F. Neumann
Journal of Environmental Protection (JEP) , 2016, DOI: 10.4236/jep.2016.73033

Three tributaries of the Grand River watershed (Ontario, Canada), each representing different watershed types (urban, agricultural/rural, and mixed land-use) were examined to understand the spatial, temporal, and host-source distribution of the waterborne pathogen, Cryptosporidium. Cryptosporidium was frequently found throughout the study (73%, 65/89) with occurrence and concentrations observed to be similar among the varying watershed types. However, applying advanced genotyping techniques, marked differences in dominant host sources could be observed in each watershed. The agricultural/rural and mixed land-use watersheds were dominated by genotypes typically associated with cattle (i.e., C. andersoni), while the urban watershed had the highest diversity of Cryptosporidium genotypes with a variety of wildlife as the common source of contamination (e.g., muskrat and cervine genotypes). A similar seasonal trend observed in the urban, agricultural, and mixed land-use watershed suggests that factors beyond specific land use activities (e.g. autumn manure spreading) may influence the timing and concentration of Cryptosporidium in these streams. Corresponding genotyping results provided additional insight into source inputs during these seasonal peaks, indicating that wildlife may be important seasonal contributors to Cryptosporidium contamination in these streams. Despite the abundance of Cryptosporidium in these watersheds, most of the genotypes observed were of limited human health importance. This study provides evidence regarding the significance of including genotyping results into studies examining waterborne Cryptosporidium. Using this technique can provide a greater understanding of the risk to the population using water sources, as well as provide insight into the probable sources and timing of contamination. This ancillary information can contribute to implementation of targeted management strategies to further protect sources of drinking water and recreation areas.

Relating Kenyan manufacturing SMEs' finance needs to information on alternative sources of finance
S.O. Migiro,M. Wallis
South African Journal of Information Management , 2009, DOI: 10.4102/sajim.v8i1.218
Interventional Radiology Procedures after Pediatric Pyeloplasty and Ureteral Reimplantation in Patients with Postoperative Obstruction  [PDF]
Brent W. Snow, M. Chad Wallis, G. Peter Feola, John W. Rampton, Teisha Shiozaki
Open Journal of Urology (OJU) , 2014, DOI: 10.4236/oju.2014.46015

Introduction: Obstructive complication after pyeloplasty or ureteral reimplant surgery is a rare though worrisome problem in pediatric urology. These are often complex patients with complicated post-operative courses that at times require interventional radiology procedures. The current literature is lacking in guiding principles to manage these complications. In this study we have reviewed these difficult to manage patients at our children’s hospital over the past 15 years. Methods: A list of patients who underwent interventional radiology procedures to place nephrostomy tubes or internal double-J ureteral stents was compared a list of patients undergoing pyeloplasty or reimplant procedures. These lists were cross-referenced to a list of patients undergoing cystoscopic removal of double-J stents. This small patient group does not represent all complications but those with radiology intervention. Results: At our institution, during the years 1998-2011 we performed 458 pyeloplasties and 3003 open ureteral reimplant procedures. 14 (0.4%) met all of the inclusion criteria. The long term outcome of these problems showed 11 of these patients went on to stability or improvement with either percutaneous drainage or JJ stent placement alone, and three of the reimplant patients ultimately required redo surgery. Of our pyeloplasty patients only three required percutaneous nephrostomy tube, and one went on to JJ stent placement (0.66% of pyeloplasties). No patients in the pyeloplasty group needed surgical revision. Of patients how had undergone ureteral reimplantation, with or without tapering, seven of them underwent interventional radiology procedures (0.23% of reimplant patients). Conclusion: Pediatric urology patients with persistent obstruction after pyeloplasties and ureteral reimplantation surgery with or without tapering who needed interventional radiology rescue procedure resolved or stabilized in 11 of 14 patients. Surgical revision was performed in only 3 of our 14 patients after months of conservative trial after interventional radiologic procedures.

Production of ultracold NH molecules by sympathetic cooling with Mg
Alisdair O. G. Wallis,Jeremy M. Hutson
Physics , 2009, DOI: 10.1103/PhysRevLett.103.183201
Abstract: We carry out calculations on $M$-changing collisions of NH ($^3\Sigma^-$) molecules in magnetically trappable states using a recently calculated potential energy surface. We show that elastic collision rates are much faster than inelastic rates for a wide range of fields at temperatures up to 10 mK and that the ratio increases for lower temperatures and magnetic fields. If NH molecules can be cooled to temperatures approaching 10 mK and brought into contact with laser-cooled Mg then there is a good prospect that sympathetic cooling can be achieved.
Optically induced conical intersections in traps for ultracold atoms and molecules
Alisdair O. G. Wallis,Jeremy M. Hutson
Physics , 2011, DOI: 10.1103/PhysRevA.84.051402
Abstract: We show that conical intersections can be created in laboratory coordinates by dressing a parabolic trap for ultracold atoms or molecules with a combination of optical and static magnetic fields. The resulting ring trap can support single-particle states with half-integer rotational quantization and many-particle states with persistent flow. Two well-separated atomic or molecular states are brought into near-resonance by an optical field and tuned across each other with an inhomogeneous magnetic field. Conical intersections occur at the nodes in the optical field.
Output of a pulsed atom laser
H. Steck,M. Naraschewski,H. Wallis
Physics , 1997, DOI: 10.1103/PhysRevLett.80.1
Abstract: We study the output properties of a pulsed atom laser consisting of an interacting Bose-Einstein condensate (BEC) in a magnetic trap and an additional rf field transferring atoms to an untrapped Zeeman sublevel. For weak output coupling we calculate the dynamics of the decaying condensate population, of its chemical potential and the velocity of the output atoms analytically.
A categorical description of Bass-Serre theory
M. V. Lawson,A. R. Wallis
Mathematics , 2013,
Abstract: Self-similar group actions may be encoded by a class of left cancellative monoids called left Rees monoids, a result obtained by combining pioneering work by Perrot with later work by the first author. Left Rees monoids that are also right cancellative are called Rees monoids. Irreducible Rees monoids have the striking property that they are embedded in their universal groups and these universal groups are HNN extensions by a single stable letter. In this paper, we generalize the above theory from monoids to categories. We study the structure of left Rees categories and prove that Rees categories embed into their universal groups. Furthermore, we show that from each graph of groups, we may construct a Rees category and prove that the fundamental group of the former is the universal group of the latter. In this way, Bass-Serre theory may be viewed as a special case of the general problem of embedding categories into groupoids.
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