698 research outputs found
Landslide Mitigation on the Sonoma Coast in Northern California
Heavy rains in late December 2001 and January 2002 caused approximately 100 meters of roadway to settle approximately 0.5 meters within a week along Highway 1 on the Sonoma County Coast (Post Mile 30.3). This area has a complex landslide history involving two active landslides. These landslides coalesce on a narrow section of Highway 1 approximately 130 meters above the Pacific Ocean. A tieback wall, sheet piles and a lightweight fill embankment had previously been constructed at this location to try to stabilize and maintain the roadway. The subsurface material at the site is composed of a matrix of very weak and extremely fractured shale and mudstone with the inclusion of sandstone blocks and fragments. The landslides are mainly driven by erosion at their base caused by storm related flows in Timber Gulch Creek and wave action undermining the slopes below the roadway. The Office of Geotechnical Design West was requested to provide Geotechnical expertise for mitigating the landslide in an expeditious manner. Several mitigation measures were considered to stabilize the landslide. The selected repair strategy was to move the roadway approximately 30 meters inland behind the failure plane of the landslide. This required the construction of a 21-meter high soil nail wall and the excavation of approximately 100,000 cubic meters of rock material. In addition, a new tieback wall needed to be constructed on the outside shoulder of the new realigned highway to prevent the current landslide scarp from encroaching into the new roadway. Design of the mitigation system was completed by March 2002 and construction started early April 2002 and completed by June 2003. This paper describes the geology and landslide history of the site and the observations, design details, soil nail pull out testing data, and wallmonitoring data obtained during the construction of the soil nail and the soldier beam tieback walls. This project demonstrated the efficiency and flexibility of soil nail and post tensioned tieback anchors for mitigating large landslides in extremely unfavorable geologic and topographic conditions. California Department of Transportation sponsored the project
Automated Spore Analysis using Bright-Field Imaging and Raman Microscopy
After the discovery of inadvertent shipments of viable B. anthracis spores by the United States Department of Defense in 2015, alternative and orthogonal methods were investigated to analyze spores to determine their viability. In this thesis we demonstrate a novel analysis technique that combines bright-field microscopy imaging with Raman chemical microscopy.
We first developed an image segmentation routine based on the watershed method to locate individual spores within bright-field images. This routine was able to effectively demarcate 97.4% of the Bacillus spores within the bright-field images with minimal over-segmentation. Size and shape measurements, to include major and minor axis and area, were then extracted for 4048 viable spores which showed very good agreement with previously published values. When similar measurements were taken on 3627 gamma-irradiated spores, a statistically significant difference was noted for the minor axis length, ratio of major to minor axis, and total area when compared to the non-irradiated spores. Classification results show the ability to correctly classify 67% of viable spores with an 18% misclassification rate using the bright-field image by thresholding the minimum classification length.
Raman chemical imaging microscopy (RCIM) was then used to measure populations of viable, gamma irradiated, and autoclaved spores of B. anthracis Sterne, B. atrophaeus. B. megaterium, and B. thuringiensis kurstaki. Significant spectral differences were observed between viable and inactivated spores due to the disappearance of features associated with calcium dipicolinate after irradiation. Principal component analysis was used which showed the ability to distinguish viable spores of B. anthracis Sterne and B. atrophaeus from each other and the other two Bacillus species.
Finally, Raman microscopy was used to classify mixtures of viable and gamma inactivated spores. A technique was developed that fuses the size and shape characteristics obtained from the bright-field image to preferentially target viable spores. Simulating a scenario of a
A practical demonstration of the technique was performed on a field of view containing approximately 7,000 total spores of which are only 12 were viable to simulate a sample that was not fully irradiated. Ten of these spores are properly classified while interrogating just 25% of the total spores
The Lino Site: A Stratified Late Archaic Campsite in a Terrace of the San Idelfonzo Creek, Webb County, Southern Texas
Archeologists from TRC Mariah Associates Inc. of Austin conducted mitigation excavations at the Lino site (41WB437) during a six-week period in April and May 1998 under contract with the Texas Department of Transportation, Environmental Affairs Division. The prehistoric archeological site was within the right-of-way of the planned expansion of Highway 83, south of Laredo. A single 196 m2 block measuring 7m north-south by 28 m east-west was investigated following requirements of a contract that stipulated a three-pronged approach to data recovery. First, a Gradall™ was employed to carefully strip 2 to 4 cm thick layers in eight 3m wide areas within the block. Balks measuring 80 cm wide by 120 cm tall were left standing between each 3 m wide Gradall™ -stripped area. The material discovered in situ during the Gradall™ stripping was plotted using a total data station. When clusters of cultural materials were encountered during the Gradall™ stripping, these were designated as features, and a series of manual excavations in 1 by 1 m units were dug around each feature. The matrix surrounding these features was screened and in situ data recorded with the total data station. Feature matrix was collected and floated in the laboratory. A total of 124 m2 were hand excavated around 24 recognized features discovered during Gradall™ stripping. Upon reaching the target depth of 120 cm below the surface, the Gradall™ stripping ceased, having mechanically removed 187 m3 of deposits
Observation of the Non-linear Meissner Effect
A long-standing theoretical prediction is that in clean, nodal unconventional
superconductors the magnetic penetration depth , at zero temperature,
varies linearly with magnetic field. This non-linear Meissner effect is an
equally important manifestation of the nodal state as the well studied
linear-in- dependence of , but has never been convincingly
experimentally observed. Here we present measurements of the nodal
superconductors CeCoIn and LaFePO which clearly show this non-linear
Meissner effect. We further show how the effect of a small dc magnetic field on
can be used to distinguish gap nodes from non-nodal deep gap
minima. Our measurements of KFeAs suggest that this material has such a
non-nodal state
Observation of the non-linear Meissner effect
A long-standing theoretical prediction is that in clean, nodal unconventional superconductors the magnetic penetration depth λ, at zero temperature, varies linearly with magnetic field. This non-linear Meissner effect is an equally important manifestation of the nodal state as the well studied linear-in-T dependence of λ, but has never been convincingly experimentally observed. Here we present measurements of the nodal superconductors CeCoIn5 and LaFePO which clearly show this non-linear Meissner effect. We further show how the effect of a small dc magnetic field on λ(T) can be used to distinguish gap nodes from non-nodal deep gap minima. Our measurements of KFe2As2 suggest that this material has such a non-nodal state
Drug-associated adverse events and their relationship with outcomes in patients receiving treatment for extensively drug-resistant tuberculosis in South Africa
BACKGROUND: Treatment-related outcomes in patients with extensively drug-resistant tuberculosis (XDR-TB) are poor. However, data about the type, frequency and severity of presumed drug-associated adverse events (AEs) and their association with treatment-related outcomes in patients with XDR-TB are scarce. METHODS: Case records of 115 South-African XDR-TB patients were retrospectively reviewed by a trained researcher. AEs were estimated and graded according to severity [grade 0 = none; grade 1-2 = mild to moderate; and grade 3-5 = severe (drug stopped, life-threatening or death)]. FINDINGS: 161 AEs were experienced by 67/115(58%) patients: 23/67(34%) required modification of treatment, the offending drug was discontinued in 19/67(28%), reactions were life-threatening in 2/67(3.0%), and 6/67(9.0%) died. ∼50% of the patients were still on treatment at the time of data capture. Sputum culture-conversion was less likely in those with severe (grade 3-5) vs. grade 0-2 AEs [2/27(7%) vs. 24/88(27%); p = 0.02]. The type, frequency and severity of AEs was similar in HIV-infected and uninfected patients. Capreomycin, which was empirically administered in most cases, was withdrawn in 14/104(14%) patients, implicated in (14/34) 41% of the total drug withdrawals, and was associated with all 6 deaths in the severe AE group (renal failure in five patients and hypokalemia in one patient). CONCLUSION: Drug-associated AEs occur commonly with XDR-TB treatment, are often severe, frequently interrupt therapy, and negatively impact on culture conversion outcomes. These preliminary data inform on the need for standardised strategies (including pre-treatment counselling, early detection, monitoring, and follow-up) and less toxic drugs to optimally manage patients with XDR-TB
Unhealthy Drinking Patterns in Older Adults: Prevalence and Associated Characteristics
To examine the prevalence of unhealthy drinking patterns in community-dwelling older adults and its association with sociodemographic and health characteristics. DESIGN : Cross-sectional analysis of nationally representative survey data. SETTING : The data source was the 2003 Access to Care file of the Medicare Current Beneficiary Survey, which represents the continuously enrolled Medicare population. PARTICIPANTS : Community-dwelling Medicare beneficiaries aged 65 and older (N=12,413). MEASUREMENTS : The prevalence of unhealthy alcohol use by older adults defined in relation to two parameters of recommended limits: monthly use exceeding 30 drinks per typical month and “heavy episodic” drinking of four or more drinks in any single day during a typical month in the previous year. Sociodemographic and health status variables were also included. RESULTS : Nine percent of elderly Medicare beneficiaries reported unhealthy drinking, with higher prevalence in men (16%) than women (4%). In logistic regression analyses with the full sample, higher education and income; better health status; male sex; younger age; smoking; being white; and being divorced, separated, or single were associated with higher likelihood of unhealthy drinking. Among drinkers, in addition to sociodemographic variables, self-reported depressive symptoms were positively associated with unhealthy drinking. Among unhealthy drinkers, race and ethnicity variables were associated with likelihood of heavy episodic drinking. CONCLUSION : Almost one in 10 elderly Medicare beneficiaries report exceeding recommended drinking limits. Several distinct unhealthy drinking patterns were identified and associated with sociodemographic and health characteristics, suggesting the value of additional targeted approaches within the context of universal screening to reduce alcohol misuse by older adults.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65179/1/j.1532-5415.2007.01539.x.pd
Assessment of the frequency-domain multi-distance method to evaluate the brain optical properties: Monte Carlo simulations from neonate to adult
The near infrared spectroscopy (NIRS) frequency-domain multi-distance (FD-MD) method allows for the estimation of optical properties in biological tissue using the phase and intensity of radiofrequency modulated light at different source-detector separations. In this study, we evaluated the accuracy of this method to retrieve the absorption coefficient of the brain at different ages. Synthetic measurements were generated with Monte Carlo simulations in magnetic resonance imaging (MRI)-based heterogeneous head models for four ages: newborn, 6 and 12 month old infants, and adult. For each age, we determined the optimal set of source-detector separations and estimated the corresponding errors. Errors arise from different origins: methodological (FD-MD) and anatomical (curvature, head size and contamination by extra-cerebral tissues). We found that the brain optical absorption could be retrieved with an error between 8–24% in neonates and infants, while the error increased to 19–44% in adults over all source-detector distances. The dominant contribution to the error was found to be the head curvature in neonates and infants, and the extra-cerebral tissues in adults
- …