79 research outputs found
Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures
Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo
Natural Resources Research Institute Technical Report
The originally uploaded version of this report was missing content from page 38 of the document (page 47 of the file). The page simply said "Insert photos" and the page number. The current version has had that page 38 replaced with a scanned version from the physical copy of the report. Page 38 now contains Figures 13a and 13b. The physical copy of the report had a plastic sheet in front of page 38 with words (e.g., "graphite") and lines and arrows on it; it was intended to line up on top of the images on page 38 below. These have been scanned together as one page.A geological model explaining the formation of mineralization at the Serpentine Cu-Ni
deposit, located at the western edge of the Keweenawan (1.1 Ga) Duluth Complex near Babbitt,
Minnesota, has been developed following detailed re-logging of drill core and compilation of
geochemical (Cu-Ni-S) data. The model suggests that sulfide mineralization was influenced by a
combination of factors, the most important being localized structural preparation of the Lower
Proterozoic (1.8 Ga) Virginia Formation footwall. The drill core provides evidence that faulting and
the emplacement of sills (both pre-and/or early-Duluth Complex) were responsible for this structural
preparation. Both processes led to weakening and/or fracturing of the footwall, thereby allowing
greater magma/footwall interaction to take place in a relatively confined area. This intimate
interaction enhanced the genesis and distribution of Cu-Ni sulfide mineralization at the Serpentine
deposit. A laterally extensive bedded pyrrhotite unit of the Virginia Formation is believed to have
further contributed to the formation of semi-massive to massive sulfides present within the deposit
by acting as a local source of additional sulfur (and minor additional Cu and Ni). Additional sulfur
isotope work is necessary before an in situ sulfur source can be ruled out, however.
A very general igneous stratigraphy has been determined for the Serpentine deposit, based
on the idea that at least three distinct magmatic events and/or intrusive styles were responsible. The
first (and earliest) contributed to the deposit's sulfide mineralization, due to its extensive interaction
with the footwall; its rocks are a heterogeneous, gradational mixture of fine- to medium-grained
troctolite, augite troctolite, and norite, loosely confined to the lowest one-half to two-thirds of the
deposit. The second event produced rocks of greater homogeneity that are more plagioclase-rich,
coarser grained, and relatively sulfide-poor; spatially, they tend to overlie those of the first. A third,
but much less volumetrically significant, magmatic event and/or intrusive style probably occurred
shortly after the second and was likely related to a faulting episode; it formed rocks that are
predominantly ultramafic. Spatially, these ultramafic rocks are largely associated with the more
homogeneous plagioclase-rich rocks, frequently occurring as linear sub-vertical bodies.
Analytical work shows the platinum group element (PGE) potential of the Serpentine deposit
is somewhat limited. The highest value (274 ppb rhenium) occurred in a massive sulfide sample.
Only three samples contained more than 100 ppb palladium. Based on these results, the mechanisms
and/or conditions for PGE enrichment that were present at the Local Boy deposit were lacking at
the Serpentine deposit. A possible explanation is that the Serpentine deposit received additional
sulfur from a local source, while the Local Boy deposit formed from a sulfide melt that: 1) formed
elsewhere; 2) scavenged more PGEs from a more primitive(?) magma; and 3) moved an
undetermined distance before being injected into structure zones, without the addition of local
sulfur. Future investigations may shed more light on the apparent differences between these two
deposits.Natural Resources Research Institute, University of Minnesota Duluth, 5013 Miller Trunk Highway, Duluth, MN 55811-1442; Indiana University, Department of Geological Sciences, Bloomington, IN 47405; Funded by the Minnesota Mining and Minerals Resources Research Institut
RI-20 Geology of the Deer Lake Complex, Itasca County, Minnesota
Contains two articles:Cumulus Mineralogy and Petrology of the
Deer Lake Complex, Itasca County, Minnesota ; Sulfide Minerals in the Layered Sills of the
Deer Lake Complex, Itasca County, Minnesota
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