Extending the Service-Life of Bridges using Sustainable and Resilient Abutment Systems: An Experimental Approach to Electrochemical Characterization of Lightweight Mechanically Stabilized Earth

Bridges are critical components of transportation infrastructure. This research addresses the need to extend the service life of bridges by improving the safety and reliability of bridge abutments and reducing their life-cycle cost and footprints. Mechanically stabilized earth (MSE) is a known strategy to enhance the economy and performance of bridge abutments. In addition, the application of rotary-kiln-manufactured lightweight aggregate backfills improves the performance of MSE bridge abutments with a leaner structural system. Such improvements include a reduction of structural demands due to a lower density, free drainage of granular materials, a high internal friction angle, less settlement with no consolidation, and accelerated construction requiring less compaction effort. This project aims to assess the electrochemical properties of expanded shale, clay, and slate (ESCS) aggregates and their influence on the corrosion of embedded steel strips. The experimental methodology involves evaluating current testing methods to measure electrical resistivity, pH, sulfate, chloride, and corrosion considering various gradation, moisture, dilution, and curing conditions. Samples represent available sources of ESCS with one source of normal weight aggregates for comparison. Results indicate the appropriateness of ESCS for addressing corrosion in MSE backfills. Further, outcomes provide guidelines to categorically predict the corrosivity of steel reinforcement when ESCS is employed as fill within MSE systems. These guidelines can help optimize the design and reduce the need to maintain and rehabilitate bridges, abutments, and approach and departure slabs on roadways to keep transportation systems safe and cost-efficient for sustainable infrastructure

Extending the Service-Life of Bridges Using Sustainable and Resilient Abutment Systems: An Experimental Approach to the Electrochemical Characterization of Lightweight Mechanically Stabilized Earth [Research Brief]

This research addresses the need to extend the service life, reduce the life cycle cost, and improve the safety and reliability of bridge abutments, part of the nation\u2019s critical transportation infrastructure. Mechanically stabilized earth (MSE) abutments contribute to the constructability and economy of bridge infrastructure. The electrochemical properties of backfill materials influence the corrosion of embedded steel strips in MSE systems. The application of rotary kiln manufactured lightweight aggregates contributes to the sustainability of bridge abutments by addressing corrosion concerns, reducing structural loads and settlements, providing free drainage, and accelerating construction. This project investigates the properties and characteristics of expanded shale, clay, and slate aggregates compared with normal-weight aggregates concerning the corrosivity of steel reinforcement

Extending the Service-Life of Bridges Using Sustainable and Resilient Abutment Systems: An Experimental Approach to the Electrochemical Characterization of Lightweight Mechanically Stabilized Earth

ZSB12017-SJAUXBridges are critical components of transportation infrastructure. This research addresses the need to extend the service life of bridges by improving the safety and reliability of bridge abutments and reducing their life-cycle cost and footprints. Mechanically stabilized earth (MSE) is a known strategy to enhance the economy and performance of bridge abutments. In addition, the application of rotary-kiln-manufactured lightweight aggregate backfills improves the performance of MSE bridge abutments with a leaner structural system. Such improvements include a reduction of structural demands due to a lower density, free drainage of granular materials, a high internal friction angle, less settlement with no consolidation, and accelerated construction requiring less compaction effort. This project aims to assess the electrochemical properties of expanded shale, clay, and slate (ESCS) aggregates and their influence on the corrosion of embedded steel strips. The experimental methodology involves evaluating current testing methods to measure electrical resistivity, pH, sulfate, chloride, and corrosion considering various gradation, moisture, dilution, and curing conditions. Samples represent available sources of ESCS with one source of normal weight aggregates for comparison. Results indicate the appropriateness of ESCS for addressing corrosion in MSE backfills. Further, outcomes provide guidelines to categorically predict the corrosivity of steel reinforcement when ESCS is employed as fill within MSE systems. These guidelines can help optimize the design and reduce the need to maintain and rehabilitate bridges, abutments, and approach and departure slabs on roadways to keep transportation systems safe and costefficient for sustainable infrastructure

Anarchy's anatomy : two-tiered security systems and Libya’s civil wars

No issue deserves more scrutiny than the mechanisms whereby popular unrest unleashes civil wars. We argue that one institution — two-tiered security systems — is particularly pernicious in terms of the accompanying civil war risk. These systems’ defining characteristic is the juxtaposition of small communally stacked units that protect regimes from internal adversaries with larger regular armed forces that deter external opponents. These systems aggravate civil war risks because stacked security units lack the size to repress widespread dissent, but inhibit rapid regime change through coup d’état. Regular militaries, meanwhile, fracture when ordered to employ force against populations from which they were recruited.PostprintPeer reviewe

Clinical Utilities of Peripheral Blood Gene Expression Profiling in the Management of Cardiac Transplant Patients

Cardiac allografts induce host immune responses that lead to endomyocardial tissue injury and progressive graft dysfunction. Inflammatory cell infiltration and myocyte damage characterize acute cellular rejection (ACR) that presents episodically in either a subclinical or symptom-associated manner. Sampling of the endomyocardium by transvenous biopsy enables pathologic grading using light microscopic criteria to distinguish severity based on the focality or diffuseness of inflammation and associated myocyte injury. Monitoring for ACR utilizes endomyocardial biopsy in conjunction with history and physical examination and assessment of allograft function by echocardiography. However, procedural and interpretive issues limit the diagnostic certainty provided by endomyocardial biopsy. The dynamic profiling of genes expressed by peripheral blood mononuclear cells (PBMCs) enables quantitative assessments of intracellular mRNA whose levels fluctuate during systemic alloimmune responses. Gene expression profiling of PBMCs using a multi-gene ACR classifier enables the AlloMap® molecular expression test to distinguish moderate to severe ACR (p = 0.0018) in heart transplant patients. The AlloMap test provides molecular insights into a patient's risk for ACR by distilling the aggregate expression levels of its informative genes into a single score on a scale of 0 to 40. The selection of a score as a threshold value for clinical decision-making is based on its associated negative predictive value (NPV), which ranges from 98 to 99% for values in three post-transplant periods: >2 to ≤6 months, > 6to ≤ 12 months, and >12 months. Scores below the threshold value rule out ACR, while those above suggest increased ACR risk. Incorporating the AlloMap test into immunomonitoring protocols provides an opportunity for clinicians to enhance patient care and to define its role in immunodiagnostic strategies to optimize the clinical outcomes of heart transplant recipients. This summary highlights the concepts presented in an invited presentation at a conference focused on Immunodiagnostics and Immunomonitoring: From Research to Clinic, in San Diego, CA on November 7, 2006

Usual Primary Care Provider Characteristics of a Patient-Centered Medical Home and Mental Health Service Use

BACKGROUND: The benefits of the patient-centered medical home (PCMH) over and above that of a usual source of medical care have yet to be determined, particularly for adults with mental health disorders. OBJECTIVE: To examine qualities of a usual provider that align with PCMH goals of access, comprehensiveness, and patient-centered care, and to determine whether PCMH qualities in a usual provider are associated with the use of mental health services (MHS). DESIGN: Using national data from the Medical Expenditure Panel Survey, we conducted a lagged cross-sectional study of MHS use subsequent to participant reports of psychological distress and usual provider and practice characteristics. PARTICIPANTS: A total of 2,358 adults, aged 18–64 years, met the criteria for serious psychological distress and reported on their usual provider and practice characteristics. MAIN MEASURES: We defined “usual provider” as a primary care provider/practice, and “PCMH provider” as a usual provider that delivered accessible, comprehensive, patient-centered care as determined by patient self-reporting. The dependent variable, MHS, included self-reported mental health visits to a primary care provider or mental health specialist, counseling, and psychiatric medication treatment over a period of 1 year. RESULTS: Participants with a usual provider were significantly more likely than those with no usual provider to have experienced a primary care mental health visit (marginal effect [ME] = 8.5, 95 % CI = 3.2–13.8) and to have received psychiatric medication (ME = 15.5, 95 % CI = 9.4–21.5). Participants with a PCMH were additionally more likely than those with no usual provider to visit a mental health specialist (ME = 7.6, 95 % CI = 0.7–14.4) and receive mental health counseling (ME = 8.5, 95 % CI = 1.5–15.6). Among those who reported having had any type of mental health visit, participants with a PCMH were more likely to have received mental health counseling than those with only a usual provider (ME = 10.0, 95 % CI = 1.0–19.0). CONCLUSIONS: Access to a usual provider is associated with increased receipt of needed MHS. Patients who have a usual provider with PCMH qualities are more likely to receive mental health counseling

Language of Lullabies: The Russification and De-Russification of the Baltic States

This article argues that the laws for promotion of the national languages are a legitimate means for the Baltic states to establish their cultural independence from Russia and the former Soviet Union