194 research outputs found

    A geological survey of Panama (1913)

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    The general plan of the surrey comprises a systematic study of the physiography, stratigraphy and structural geology, geologic history, geologic correlation, mineral resources (including coal, oil, and other fields), petrography and paleontology of the Canal Zone, and of as much of the adjacent areas of the Isthmian region as is feasible

    Biological Survey of the Panama Canal Zone (1911)

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    With the cooperation of several of the executive departments, and of the Field Museum of Natural History, a party of about 10 naturalists was accordingly sent to the zone, and the results so far accomplished have been very satisfactory. Large collections of biological material have been received, including specimens of a considerable number of genera and species new to science. It also seemed important to determine exactly the geographical distribution of the various organisms inhabiting the Isthmus, which is one of the routes by which the animals and plants of South America have entered North America and vice versa. The estimated cost of the survey which would have to be met by the Institution is $11,000..

    Kinematics of the New Zealand plate boundary: Relative motion by GPS across networks of 1000 km and 50 km spacing

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    The NASA/DOSE 'Kinematics of the New Zealand Plate Boundary' experiment is a four-year cooperative Global Positioning System (GPS) experiment involving 6 universities and institutions in New Zealand and the United States. The investigation covers two scales, the first on the scale of plates (approximately 1000 km) and the second is on the scale of the plate boundary zone (approximately 50 km). In the first portion of the experiment, phase A, the objective is to make direct measurements of tectonic plate motion between the Australian and Pacific plates using GPS in order to determine the Euler vector of this plate pair. The phase A portion of this experiment was initiated in December 1992 with the first-epoch baseline measurements on the large scale network. The network will be resurveyed two years later to obtain velocities. The stations which were observed for phase A are shown and listed. Additional regional stations which will be used for this study are listed and are part of either CIGNET or other global tracking networks. The phase A portion of the experiment is primarily the responsibility of the UNAVCO investigators. Therefore, this report concentrates on phase A. The first year of NASA funding for phase A included only support for the field work. Processing and analysis will take place with the second year of funding. The second part of the experiemnt measured relative motion between the Australian and Pacific plates across the pate boundary zone between Hokitika and Christchurch on the South Island of New Zealand. The extent and rate of deformation will be determined by comparisons with historical, conventional surveys and by repeated GPS measurements to be made in two years. This activity was the emphasis of the LDGO portion of the study. An ancillary experiment, phase C, concentrated on plate boundary deformation in the vicinity of Wellington and was done as part of training during the early portion of the field campaign. Details of the objectives of the field investigations are given in the appendix. An overview of the 1992 GPS field program is also given in the appendix

    Radiostereometric Analysis of Femoral Head Penetration in Cross-Linked Polyethylene in THR Patients

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    Background: In the young total hip replacement (THR) population limiting polyethylene liner wear is crucial to preventing premature implant failure. Highly cross-linked ultra-high molecular weight polyethylene (HXLPE) liners were designed to improve wear resistance of polyethylene liners. Radiostereometric analysis (RSA) provides highly precise measurements of liner wear. This study utilized RSA to characterize wear of conventional versus HXLPE liners up to five years following THR. Methods: This IRB-approved, prospective, randomized, blinded study, involved 46 patients with a mean age of 58 and BMI of 30. Each patient was double randomized to receive a conventional or HXLPE liner with an uncemented titanium mesh or tantalum trabecular metal cup. Both liners were prepared from compression-molded GUR 1050 resin without calcium stearate, while HXLPE liners undergo further e-beam irradiation and annealing. At the time of surgery, 1mm tantalum RSA markers were implanted around the liner periphery, femur and periacetabular bone. RSA examinations, Harris Hip, UCLA, WOMAC, SF-36 scores were obtained pre-operatively, post-operatively, at six weeks, six months and annually through five years. Results: All patients had statistically significant improvement in Harris Hip, WOMAC and SF-36 PCS scores following THR with no difference between cohorts. On RSA examination, of titanium shells, HXLPE liners revealed significantly lower femoral head penetration at each follow up except six weeks and six months (p Conclusion: In this young THR population RSA shows significantly less femoral head penetration in the HXLPE liners compared to conventional liners. Novel RSA techniques have been developed to determine polyethylene wear in patients

    Tantalum versus Titanium Acetabular Shells in Young Active THR Patients: A Radiostereometric Analysis (RSA) Study

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    Introduction: In the active THR (total hip replacement) population, acetabular component stability is crucial for preventing implant failure. Titanium fiber metal coating is the most common material used in cementless THR. Trabecular metal, composed of porous tantalum, is designed to improve tissue infiltration and limit migration. It is unknown if tantalum offers an advantage over titanium in the biologic fixation of porous-coated acetabular shells. Radiostereometric analysis (RSA) provides highly precise measurements of micromotion that are otherwise not detectable by routine radiographs. Methods: In this IRB approved, prospective, randomized, blinded study, 46 patients received a primary THR by a single surgeon. Each patient was randomized to receive a titanium (23) or tantalum (23) uncemented cup. Tantalum RSA markers were implanted around the polyethylene liner and into the patient’s femur and periacetabular bone. Also, patients received either a highly cross-linked (n=25) or a conventional liner (n=21). RSA examinations, Harris Hip, UCLA, WOMAC, SF-12 scores were obtained at 10 days, 6 months, and annually through 5 years. Results: The randomized groups had comparable mean age, preoperative activity, and average BMI. The tantalum shells demonstrated less median translation than the titanium shells at each time-point, but there was no statistical difference between the two shells. At 6 months median translation of tantalum and titanium was -0.01mm and 0.04mm and remained stable with median translation of -0.02mm and 0.04mm at four years. Mean UCLA, WOMAC, Harris Hip, and SF-12 PCS and MCS scores improved similarly in both groups. Conclusions: After THR, both patient cohorts had excellent clinical outcomes with statistically significant improvements in function and pain relief. Although tantalum porous-coated acetabular shells demonstrated less y-translation and y-rotation at all time points, there was no statistically significant difference in shell migration and both shells demonstrated excellent stability with minimal micromotion at four years

    Radiostereometric Analysis of Tantalum vs. Titanium Acetabular Shells in Young THR Patients

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    Introduction: In the active total hip replacement (THR) population, maintaining acetabular component stability and limiting polyethylene wear are crucial components to preventing premature implant failure. Titanium with Co/Cr/Mo fiber metal coating is among the most common materials used in cementless THR. Trabecular metal, composed of porous tantalum, has a metallic strut design resembling trabecular bone, designed to improve tissue infiltration and limit migration. This study assesses the stability and clinical outcomes of tantalum versus titanium acetabular shells using radiostereometric analysis (RSA) technology. Methods: In this IRB approved, prospective, randomized, blinded study, 46 patients received a primary THR by a single surgeon (DCA). Each patient was randomized to receive a titanium (23) (Trilogy, Zimmer) or tantalum (23) (Modular tantalum shell, Zimmer) uncemented hemispheric cup and either a highly-crosslinked or conventional polyethylene liner. Tantalum RSA markers were implanted around the liner periphery, femur, and periacetabular bone in each patient. RSA examinations, Harris Hip, UCLA, WOMAC, SF-36 scores were obtained at 10 days, 6 months, and annually with the furthest patients evaluated through 5 years. Results: Median translation was greater at all time points for the tantalum mesh cups except for the 3-year follow-up, however due to large standard errors, there was no significant difference between the two designs (p\u3e0.05). These large standard errors were predominantly caused by two outliers, neither of which had clinical evidence of loosening at 5 years follow-up. Mean UCLA, WOMAC, Harris Hip, and SF-36 PCS and MCS scores improved similarly in both groups. Conclusions: In this young THR population, both titanium and tantalum acetabular shells demonstrated excellent stability at five years follow up. Tantalum shells demonstrated slightly greater micromotion, but there was no statistically significant difference in shell migration. Outstanding clinical outcomes with statistically significant improvements in function and pain relief were observed in both groups

    Baker Center Journal of Applied Public Policy - Vol. IV, No.II

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    This special edition includes articles from speakers at a 2010 conference - Howard H. Baker, Jr: A Life in Public Service and a special addendum including photographs and cartoons from Sen. Baker\u27s career

    "The Book of Negroes’ illustrated edition: circulating African-Canadian history through the Middlebrow"

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    This article examines the 2009 deluxe illustrated edition of Lawrence Hill’s Commonwealth Writers’ Prize– and Canada Reads–winning novel The Book of Negroes, originally published in 2007. It relates the story of Aminata, a West African girl kidnapped and sold into slavery, and her experiences on an indigo plantation in the American south, followed by further displacements to Charleston, Nova Scotia, Sierra Leone, and London. In New York, as the Revolutionary War comes to a close, Aminata becomes the scribe for the Book of Negroes, documenting the Black Loyalists, as well as the slaves and indentured servants of white Loyalists, granted passage by the British to Canada. Hill has commented that the Book of Negroes is an important document about which Canadians are largely ignorant. This desire to circulate knowledge about African-Canadian history through the novel is particularly manifest in the illustrated edition of 2009, where a photograph of the Book of Negroes features prominently, along with countless other images and captions which supplement and interrupt Hill’s narrative. This article considers the significance and implications of this “keepsake” or “souvenir” edition, particularly its circulation of knowledge about African-Canadian history through visual pleasure

    The Influence of Curator Goals on Collections of Lived Experience Narratives: A Qualitative Study

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    Objective: The aim of this study was to investigate how curator goals influence the design of curation processes for collections of mental health lived experience narratives. The objectives were (1) to characterize the goals of a range of curators of existing collections, and (2) to identify specific working practices impacted by these goals.Research Design and Methods: Thirty semi-structured interviews were conducted with a purposive sample of curators of collections of lived experience narratives. Thematic analysis was conducted. Goals and impacts on working practice were tabulated, and narrative summaries were constructed to describe the relation between the two.Results: Curators interviewed were from seven countries (Brazil, Canada, Hong Kong, India, Italy, UK, USA), and 60% had lived experience of mental health service usage. Participants discussed eight goals that inspired their work: fighting stigma, campaigning for change in service provision, educating about mental health and recovery, supporting others in their recovery journey, critiquing psychiatry, influencing policy, marketing health services, and reframing mental illness. These goals influenced how decisions were made about inclusion of narratives, editing of narrative content, withdrawal rights, and anonymization. Conclusions: Our work will support the development of curatorship as a professional practice by shaping training for curators, helping curators reflect on the outcomes they would like to achieve, and helping individuals planning a collection to reflect on their motivations. We argue that transparency is an essential orientation for curators. Transparency allows narrators to make an informed choice about donating a narrative. It allows policy makers to understand the influences on a collection and hence treat it as a source of collective evidence
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