Advancement of direct drive generator systems for offshore renewable energy production

As machine topologies and technologies mature, the fundamental function of the device is honed. Direct drive machines have the potential to launch the renewable energy sector into a new era of large scale, reliable, offshore power generation. With advancements in new technologies, such as superconductivity, the reduction of generator mass due to incorporation of machine and device structures, the continued advancements in component and system reliability; direct drive generators have the ability to outsize geared wind systems and simplify submerged linear and rotary power generation. The research held within this thesis will focus on improving direct drive power take off systems for offshore renewable energy power generation by splitting the area into four parts. The first part will discuss the various methods of energy extraction within the offshore and marine environment. The future of the sector will be discussed, and a forecast of technological advancement and existing reliability issues will be provided based on current data. The second part will focus on drive trains and direct drive generators, assessing the current topologies and suggesting alternatives that may thrive in a variety of large and small offshore renewable machines. The third part investigates the application of novel linear bearings in direct drive systems for offshore and submerged operation. A brief study of the loads found in wave applications will be presented and the testing of several polymer bearing materials will be outlined. The final part will discuss the potential benefits of flooding the airgap of a direct drive generator with sea water for marine applications. Results will be presented from two linear test rigs and the marinisation of devices will conclude the report

Development of a Superconducting Claw-Pole Linear Test-Rig

Superconducting generators can help to reduce the cost of energy for large offshore wind turbines, where the size and mass of the generator have a direct effect on the installation cost. However, existing superconducting generators are not as reliable as the alternative technologies. In this paper, a linear test prototype for a novel superconducting claw-pole topology, which has a stationary superconducting coil that eliminates the cryocooler coupler will be presented. The issues related to mechanical, electromagnetic and thermal aspects of the prototype will be presented

Radar Observations and the Shape of Near-Earth Asteroid 2008 EV5

We observed the near-Earth asteroid 2008 EV5 with the Arecibo and Goldstone planetary radars and the Very Long Baseline Array during December 2008. EV5 rotates retrograde and its overall shape is a 400 /pm 50 m oblate spheroid. The most prominent surface feature is a ridge parallel to the asteroid's equator that is broken by a concavity 150 m in diameter. Otherwise the asteroid's surface is notably smooth on decameter scales. EV5's radar and optical albedos are consistent with either rocky or stony-iron composition. The equatorial ridge is similar to structure seen on the rubble-pile near-Earth asteroid (66391) 1999 KW4 and is consistent with YORP spin-up reconfiguring the asteroid in the past. We interpret the concavity as an impact crater. Shaking during the impact and later regolith redistribution may have erased smaller features, explaining the general lack of decameter-scale surface structure.Comment: This paper has been accepted for publication in Icarus: http://www.sciencedirect.com/science/article/B6WGF-5207B2F-4/2/d87cd2ae4da00c2b277e2dc79a532c4

Comparative genomic analyses identify common molecular pathways modulated upon exposure to low doses of arsenic and cadmium

<p>Abstract</p> <p>Background</p> <p>Exposure to the toxic metals arsenic and cadmium is associated with detrimental health effects including cancers of various organs. While arsenic and cadmium are well known to cause adverse health effects at high doses, the molecular impact resulting from exposure to environmentally relevant doses of these metals remains largely unexplored.</p> <p>Results</p> <p>In this study, we examined the effects of <it>in vitro </it>exposure to either arsenic or cadmium in human TK6 lymphoblastoid cells using genomics and systems level pathway mapping approaches. A total of 167 genes with differential expression were identified following exposure to either metal with surprisingly no overlap between the two. Real-time PCR was used to confirm target gene expression changes. The gene sets were overlaid onto protein-protein interaction maps to identify metal-induced transcriptional networks. Interestingly, both metal-induced networks were significantly enriched for proteins involved in common biological processes such as tumorigenesis, inflammation, and cell signaling. These findings were further supported by gene set enrichment analysis.</p> <p>Conclusions</p> <p>This study is the first to compare the transcriptional responses induced by low dose exposure to cadmium and arsenic in human lymphoblastoid cells. These results highlight that even at low levels of exposure both metals can dramatically influence the expression of important cellular pathways.</p

Incidence of AIDS-Defining Opportunistic Infections in a Multicohort Analysis of HIV-infected Persons in the United States and Canada, 2000–2010

Background. There are few recent data on the rates of AIDS-defining opportunistic infections (OIs) among human immunodeficiency virus (HIV)–infected patients in care in the United States and Canada

Hospital Readmissions Among Persons With Human Immunodeficiency Virus in the United States and Canada, 2005–2018: A Collaboration of Cohort Studies

BackgroundHospital readmission trends for persons with human immunodeficiency virus (PWH) in North America in the context of policy changes, improved antiretroviral therapy (ART), and aging are not well-known. We examined readmissions during 2005-2018 among adult PWH in NA-ACCORD.MethodsLinear risk regression estimated calendar trends in 30-day readmissions, adjusted for demographics, CD4 count, AIDS history, virologic suppression (&lt;400 copies/mL), and cohort.ResultsWe examined 20 189 hospitalizations among 8823 PWH (73% cisgender men, 38% White, 38% Black). PWH hospitalized in 2018 versus 2005 had higher median age (54 vs 44 years), CD4 count (469 vs 274 cells/μL), and virologic suppression (83% vs 49%). Unadjusted 30-day readmissions decreased from 20.1% (95% confidence interval [CI], 17.9%-22.3%) in 2005 to 16.3% (95% CI, 14.1%-18.5%) in 2018. Absolute annual trends were -0.34% (95% CI, -.48% to -.19%) in unadjusted and -0.19% (95% CI, -.35% to -.02%) in adjusted analyses. By index hospitalization reason, there were significant adjusted decreases only for cardiovascular and psychiatric hospitalizations. Readmission reason was most frequently in the same diagnostic category as the index hospitalization.ConclusionsReadmissions decreased over 2005-2018 but remained higher than the general population's. Significant decreases after adjusting for CD4 count and virologic suppression suggest that factors alongside improved ART contributed to lower readmissions. Efforts are needed to further prevent readmissions in PWH

Large genome-wide association study identifies three novel risk variants for restless legs syndrome

Funder: Scottish Government; doi: https://doi.org/10.13039/100012095Funder: Cancer Research UK (CRUK); doi: https://doi.org/10.13039/501100000289Abstract: Restless legs syndrome (RLS) is a common neurological sensorimotor disorder often described as an unpleasant sensation associated with an urge to move the legs. Here we report findings from a meta-analysis of genome-wide association studies of RLS including 480,982 Caucasians (cases = 10,257) and a follow up sample of 24,977 (cases = 6,651). We confirm 19 of the 20 previously reported RLS sequence variants at 19 loci and report three novel RLS associations; rs112716420-G (OR = 1.25, P = 1.5 × 10−18), rs10068599-T (OR = 1.09, P = 6.9 × 10−10) and rs10769894-A (OR = 0.90, P = 9.4 × 10−14). At four of the 22 RLS loci, cis-eQTL analysis indicates a causal impact on gene expression. Through polygenic risk score for RLS we extended prior epidemiological findings implicating obesity, smoking and high alcohol intake as risk factors for RLS. To improve our understanding, with the purpose of seeking better treatments, more genetics studies yielding deeper insights into the disease biology are needed

End-Stage Renal Disease Among HIV-Infected Adults in North America

Background. Human immunodeficiency virus (HIV)-infected adults, particularly those of black race, are at high-risk for end-stage renal disease (ESRD), but contributing factors are evolving. We hypothesized that improvements in HIV treatment have led to declines in risk of ESRD, particularly among HIV-infected blacks

On the Determinants of Social Capital in Greece Compared to Countries of the European Union

Social capital refers to the stock of social relations, based on norms and networks of cooperation and trust that spill over to the market and state to enhance collective action between actors and achieve improved social efficiency and economic growth. The aim of the present paper is to discuss the implications of contemporary literature and empirical findings on social capital for the growth prospects of Greece, compared to the member-states of the European Union. In order to examine the potential of social capital to enhance growth, we must look into the factors that determine the nature and context of trust, norms and networks that have emerged in our multinational, multiethnic and multicultural Europe.The contribution of this paper is to offer insight on the determinants of social capital in Greece, compared to the European Union (EU - former 15 member-states). For this purpose, we regress an index of individual group membership, derived from the European Community Household Panel (ECHP), on a set of individual as well as aggregate factors of social capital. Regression results provide evidence of the impact of both individual and institutional characteristics on group membership. Differences on the extent of group membership between countries might be indicative of the historical and cultural differences that have affected the evolution of social capital across Europe. Particularly in Greece, the relatively low level of group membership compared to the other EU countries might provide further evidence of its low levels of civicness. Historically, its weak civil society has been a result of a prior civic tradition of clientelism under arbitrary rule, the interference of special-interest groups and the lack of credibility and impartiality from the part of the state. And these factors might be responsible for the slow pace in reform and growth observed compared to the rest of the EU. Nevertheless, the findings on the determinants of social capital may direct us to possible means of rebuilding patterns of participatory and cooperative behavior, especially in countries with low levels of trust and civicness, such as Greece