Use of the IGBT Module in the Active Region to Design a High Current Active Filter

Particle accelerators require high-precision magnetic fields on the order or 100ppm or less. This implies that the precision of the associated electrical current in the electromagnet that generates these fields should be smaller than 100ppm. However, conventional switching power supplies cannot offer this precision due to the frequency limitation of the switches. This research considers the use of power electronics devices operating in a linear as an alternative solution to meet the requirements of particle accelerator electromagnets. This thesis presents the study of an insulated-gate bipolar transistor (IGBT) driver using a new control method that linearizes the IGBT’s collector-emitter voltage (???) gain. This allows the use of the IGBT in its linear region. This enables the implementation of an active filter as part of the superconducting magnet test facilities within the Superconducting Magnet Division (SMD) at Brookhaven National Laboratory (BNL). The IGBT driver and active filter incorporate a dual feedback loop topology to control IGBT modules and achieves improved capability in achieving precise control of electromagnet currents. This approach allows the use of commercially available IGBT devices that are normally optimized to work as switches. The design, simulation, prototyping, and test results of an IGBT driver using the proposed dual-loop feedback approach is performed using MITSUBISHI CM1000-24H IGBTs, LabVIEW software and National Instruments Compact RIO hardware. Experimental results are presented that confirm the effectiveness of the proposed method

Tracing the Evolution of Agglomeration Economies: Spain, 1860-1991

This article attempts to quantify how the effect of agglomeration economies on population growth has evolved over time. Using district population in Spain between 1860 and 1991, recorded approximately every decade, this article examines whether initial population affects subsequent population growth. Our results show that, while the relationship between these two variables hardly existed during the second half of the 19th century, this link increased significantly between 1910 and 1970, although this trend was abruptly interrupted by the Civil War and the autarkic period that followed. The intensity of this relationship debilitated in the 1970s, a process that continued during the 1980s as rural out-migration diminished and de-industrialisation hit traditional manufacturing sectors. Our findings also stress that agglomeration economies were stronger in medium-size districts, especially from 1960 onwards, thus suggesting that congestion costs began to mitigate the benefits arising from agglomeration economies in the largest locations

The Shadow of Cities: Size, Location and the Spatial Distribution of Population in Spain

Using a large data set on the population of Spanish municipalities between 1877 and 2001, this paper analyses how their initial size and the presence of neighbouring urban locations influence subsequent population growth and how these links have evolved over time. Our results show that initial size is negatively related to population growth, except in the 1960s and 1970s when this relationship becomes positive. Likewise, the presence of neighbouring urban locations limited local population growth in the late 19th century, a negative effect that persisted, but at a diminishing rate, until the second half of the 20th century. The influence of nearby cities became increasingly positive from then onwards, and especially so during the 1970s

Correction to: Dimensions of leisure-time physical activity and risk of depression in the “Seguimiento Universidad de Navarra” (SUN) prospective cohort

After publication of our article [1] we have been notified that Table 2 was incorrectly formatte

NEW EVIDENCE ON REGIONAL INEQUALITY IN IBERIA (1900-2000): A GEOGRAPHICAL APPROACH

Abstract This paper presents new evidence on the evolution of regional inequality in Iberia from 1900 to 2000 from a geographical perspective. To do so we introduce a new historical dataset of regional GDPs for Spanish NUTS III and Portuguese Historical Districts (HD), synthetic indices of regional inequality and different measures of spatial correlation across regional pc GDPs. The results show that the Portuguese and Spanish national economic integration processes initially led to the economic specialization across Iberian regions promoting the divergence in terms of their regional pc GDPs. Notwithstanding, ulterior advances in the integration of national markets and the subsequent first stages in the process of adhesion of these two national economies into the UE coexisted with a progressive reduction in Iberian regional inequality

Improving Antiretroviral Therapy Adherence in Resource-Limited Settings at Scale: a Discussion of Interventions and Recommendations

INTRODUCTION: Successful population-level antiretroviral therapy (ART) adherence will be necessary to realize both the clinical and prevention benefits of antiretroviral scale-up and, ultimately, the end of AIDS. Although many people living with HIV are adhering well, others struggle and most are likely to experience challenges in adherence that may threaten virologic suppression at some point during lifelong therapy. Despite the importance of ART adherence, supportive interventions have generally not been implemented at scale. The objective of this review is to summarize the recommendations of clinical, research, and public health experts for scalable ART adherence interventions in resource-limited settings. METHODS: In July 2015, the Bill and Melinda Gates Foundation convened a meeting to discuss the most promising ART adherence interventions for use at scale in resource-limited settings. This article summarizes that discussion with recent updates. It is not a systematic review, but rather provides practical considerations for programme implementation based on evidence from individual studies, systematic reviews, meta-analyses, and the World Health Organization Consolidated Guidelines for HIV, which include evidence from randomized controlled trials in low- and middle-income countries. Interventions are categorized broadly as education and counselling; information and communication technology-enhanced solutions; healthcare delivery restructuring; and economic incentives and social protection interventions. Each category is discussed, including descriptions of interventions, current evidence for effectiveness, and what appears promising for the near future. Approaches to intervention implementation and impact assessment are then described. RESULTS AND DISCUSSION: The evidence base is promising for currently available, effective, and scalable ART adherence interventions for resource-limited settings. Numerous interventions build on existing health care infrastructure and leverage available resources. Those most widely studied and implemented to date involve peer counselling, adherence clubs, and short message service (SMS). Many additional interventions could have an important impact on ART adherence with further development, including standardized counselling through multi-media technology, electronic dose monitoring, decentralized and differentiated models of care, and livelihood interventions. Optimal targeting and tailoring of interventions will require improved adherence measurement. CONCLUSION: The opportunity exists today to address and resolve many of the challenges to effective ART adherence, so that they do not limit the potential of ART to help bring about the end of AIDS

Can modeling of HIV treatment processes improve outcomes? Capitalizing on an operations research approach to the global pandemic

<p>Abstract</p> <p>Background</p> <p>Mathematical modeling has been applied to a range of policy-level decisions on resource allocation for HIV care and treatment. We describe the application of classic operations research (OR) techniques to address logistical and resource management challenges in HIV treatment scale-up activities in resource-limited countries.</p> <p>Methods</p> <p>We review and categorize several of the major logistical and operational problems encountered over the last decade in the global scale-up of HIV care and antiretroviral treatment for people with AIDS. While there are unique features of HIV care and treatment that pose significant challenges to effective modeling and service improvement, we identify several analogous OR-based solutions that have been developed in the service, industrial, and health sectors.</p> <p>Results</p> <p>HIV treatment scale-up includes many processes that are amenable to mathematical and simulation modeling, including forecasting future demand for services; locating and sizing facilities for maximal efficiency; and determining optimal staffing levels at clinical centers. Optimization of clinical and logistical processes through modeling may improve outcomes, but successful OR-based interventions will require contextualization of response strategies, including appreciation of both existing health care systems and limitations in local health workforces.</p> <p>Conclusion</p> <p>The modeling techniques developed in the engineering field of operations research have wide potential application to the variety of logistical problems encountered in HIV treatment scale-up in resource-limited settings. Increasing the number of cross-disciplinary collaborations between engineering and public health will help speed the appropriate development and application of these tools.</p

Expanding ART for Treatment and Prevention of HIV in South Africa: Estimated Cost and Cost-Effectiveness 2011-2050

Background: Antiretroviral Treatment (ART) significantly reduces HIV transmission. We conducted a cost-effectiveness analysis of the impact of expanded ART in South Africa. Methods: We model a best case scenario of 90% annual HIV testing coverage in adults 15-49 years old and four ART eligibility scenarios: CD4 count <200 cells/mm3(current practice), CD4 count <350, CD4 count <500, all CD4 levels. 2011-2050 outcomes include deaths, disability adjusted life years (DALYs), HIV infections, cost, and cost per DALY averted. Service and ART costs reflect South African data and international generic prices. ART reduces transmission by 92%. We conducted sensitivity analyses. Results: Expanding ART to CD4 count <350 cells/mm3prevents an estimated 265,000 (17%) and 1.3 million (15%) new HIV infections over 5 and 40 years, respectively. Cumulative deaths decline 15%, from 12.5 to 10.6 million; DALYs by 14% from 109 to 93 million over 40 years. Costs drop $504 million over 5 years and$3.9 billion over 40 years with breakeven by 2013. Compared with the current scenario, expanding to <500 prevents an additional 585,000 and 3 million new HIV infections over 5 and 40 years, respectively. Expanding to all CD4 levels decreases HIV infections by 3.3 million (45%) and costs by $10 billion over 40 years, with breakeven by 2023. By 2050, using higher ART and monitoring costs, all CD4 levels saves$0.6 billion versus current; other ART scenarios cost $9-194 per DALY averted. If ART reduces transmission by 99$17.5 billion. Sensitivity analyses suggest that poor retention and predominant acute phase transmission reduce DALYs averted by 26% and savings by 7%. Conclusion: Increasing the provision of ART to <350 cells/mm3 may significantly reduce costs while reducing the HIV burden. Feasibility including HIV testing and ART uptake, retention, and adherence should be evaluated

Why Pleiotropic Interventions are Needed for Alzheimer's Disease

Alzheimer's disease (AD) involves a complex pathological cascade thought to be initially triggered by the accumulation of β-amyloid (Aβ) peptide aggregates or aberrant amyloid precursor protein (APP) processing. Much is known of the factors initiating the disease process decades prior to the onset of cognitive deficits, but an unclear understanding of events immediately preceding and precipitating cognitive decline is a major factor limiting the rapid development of adequate prevention and treatment strategies. Multiple pathways are known to contribute to cognitive deficits by disruption of neuronal signal transduction pathways involved in memory. These pathways are altered by aberrant signaling, inflammation, oxidative damage, tau pathology, neuron loss, and synapse loss. We need to develop stage-specific interventions that not only block causal events in pathogenesis (aberrant tau phosphorylation, Aβ production and accumulation, and oxidative damage), but also address damage from these pathways that will not be reversed by targeting prodromal pathways. This approach would not only focus on blocking early events in pathogenesis, but also adequately correct for loss of synapses, substrates for neuroprotective pathways (e.g., docosahexaenoic acid), defects in energy metabolism, and adverse consequences of inappropriate compensatory responses (aberrant sprouting). Monotherapy targeting early single steps in this complicated cascade may explain disappointments in trials with agents inhibiting production, clearance, or aggregation of the initiating Aβ peptide or its aggregates. Both plaque and tangle pathogenesis have already reached AD levels in the more vulnerable brain regions during the “prodromal” period prior to conversion to “mild cognitive impairment (MCI).” Furthermore, many of the pathological events are no longer proceeding in series, but are going on in parallel. By the MCI stage, we stand a greater chance of success by considering pleiotropic drugs or cocktails that can independently limit the parallel steps of the AD cascade at all stages, but that do not completely inhibit the constitutive normal functions of these pathways. Based on this hypothesis, efforts in our laboratories have focused on the pleiotropic activities of omega-3 fatty acids and the anti-inflammatory, antioxidant, and anti-amyloid activity of curcumin in multiple models that cover many steps of the AD pathogenic cascade (Cole and Frautschy, Alzheimers Dement 2:284–286, 2006)