Vertebral compression fractures (VCFs) are the most common type of fracture secondary to osteoporosis. These fractures are associated with significant rates of morbidity and mortality and annual direct medical expenditures of more than $1 billion in the United States. Although many patients will respond favorably to nonsurgical care of their VCF, contemporary natural history data suggest that more than 40% of patients may fail to achieve significant pain relief within 12 months of symptom onset. As a result, percutaneous vertebral augmentation is often used to hasten symptom resolution and return of function. However, controversy regarding the role of kyphoplasty and vertebroplasty in the treatment of symptomatic VCFs exists. The purposes of this review are (1) to outline the epidemiology of VCFs as well as the physical morbidity and economic impact of these injuries, (2) to familiarize the reader with the best available evidence surrounding the operative and nonoperative treatment of VCFs, and (3) to examine the literature pertaining to the cost-effectiveness of surgical management of VCFs with the overarching goal of helping physicians make informed decisions regarding symptomatic VCF treatment.

Executive SummaryThis report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.15 and 4.19. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in February 2002.The Tank Farm Vadose Zone Project is led by CH2M HILL Hanford Group, Inc. Their goals include defining risks from past and future single-shell tank farm activities, identifying and evaluating the efficacy of interim measures, and collecting geotechnical information and data. The purpose of these activities is to support future decisions made by the U.S. Department of Energy (DOE) regarding near-term operations, future waste retrieval, and final closure activities for the single-shell tank Waste Management Areas. To help in this effort, CH2M HILL Hanford Group, Inc. contracted with scientists at Pacific Northwest National Laboratory to analyze sediment samples collected from borehole 299-W23-19.Borehole 299-W23-19 was drilled at the southwestern edge of tank SX-115 as a characterization borehole to evaluate the depth distribution of contamination leaked from tank SX-115. The borehole was cored throughout the vadose zone during drilling. The geology, stratigraphy, and lithology of the drill core were described in the field and in the laboratory. The drill cores were sampled for analyses of physical, chemical, and hydraulic properties in order to better understand the distribution of contaminants and the mechanisms of contaminant movement beneath the SX tank farm.Electrical conductivity and chromium, nitrate, sodium, and technetium concentrations were found to be good indicators of the plume distribution. Data for the other measured contaminants indicate that leaked tank fluids have impacted the vadose zone beneath tank SX-115 from about 22.2 meters (73 feet) depth to the base of the upper Plio-Pleistocene unit at about a 47.5 meters (156 feet) depth. The technetium-99 plume, however, appears to occur as deep as 62.5 meters (205 feet), which is the depth of the deepest sample.The bulk of the leaked fluid beneath tank SX-115 resides in the upper Plio-Pleistocene unit between a 38.1 meters (125-feet) and 47.5 meters (156-foot) depth. This is slightly deeper than the contamination investigated at tank SX-108 and tank SX-109, both of which have the bulk of contamination in the shallower Hanford formation.Results of chemical analyses point to three potential mechanisms influencing the distribution of contaminants in the vadose zone. Common ion exchange reactions appear to have influenced the distribution of most mobile contaminants whereas oxidation-reduction reactions seem to have influenced chromium distribution. Observations from this study suggest that nitrate, technetium-99, and perhaps molybdenum migrate with no measurable retardation in the vadose zone whereas sodium, chromium, and selenium migrate with a small amount of retardation. These conclusions are similar to the conclusions found during the S...

137Cesium and other contaminants have leaked from single-shell storage tanks (SSTs) into coarse-textured, relatively unweathered unconsolidated sediments. Contaminated sediments were retrieved from beneath a leaky SST to investigate the distribution of adsorbed 137Cs+ across different sediment size fractions. All fractions contained mica (biotite, muscovite, vermiculatized biotite), quartz, and plagioclase along with smectite and kaolinite in the clay-size fraction. A phosphor-plate autoradiograph method was used to identify particular sediment particles responsible for retaining 137Cs+. The Cs-bearing particles were found to be individual mica flakes or agglomerated smectite, mica, quartz, and plagioclase. Of these, only the micaceous component was capable of sorbing Cs+ strongly. Sorbed 137Cs+ could not be significantly removed from sediments by leaching with dithionite citrate buffer or KOH, but a fraction of the sorbed 137Cs+ (5-22%) was desorbable with solutions containing an excess of Rb+. The small amount of 137Cs+ that might be mobilized by migrating fluids in the future would likely sorb to nearby micaceous clasts in downgradient sediments.

A new class of circularly polarized (CP) Fabry-Perot cavity antennas is introduced that maintain the simplicity of a linearly polarized primary feed and a single cavity structure. The proposed antennas employ a double-sided partially reflective surface (PRS), which allows independent control of the magnitude and phase responses for the reflection and transmission coefficients. In conjunction with an anisotropic high impedance surface (HIS) ground plane, this arrangement allows for the first time a single cavity antenna to produce a specified gain in CP from a linearly polarized primary source. A design procedure for this class of antennas is introduced. The method exploits a simple ray optics model to calculate the magnitude and phase of the electric field in the cavity upon plane wave excitation. Based on this model, analytical expressions are derived, which enforce the resonance condition for both polarizations at a predetermined PRS reflectivity (and hence predetermined antenna gain) together with a 90 o differential phase between them. The validity of the concept is confirmed by means of an example entailing an antenna with gain of approximately 21 dB at 15 GHz. Full-wave simulation results and experimental testing on a fabricated prototype are presented and agree well with the theoretical predictions.