Corrosion and biofouling of offshore wind monopile foundations

The impact of corrosion and biofouling on offshore wind turbines is considered to be a key issue in terms of operation and maintenance (O&M) which must be better addressed. Early design assumptions for monopile foundations anticipated low, uniform corrosion rates in a sealed compartment that would be completely air- and water-tight. However, operational experience has shown that in practice it is very difficult to maintain a fully sealed compartment, with seawater and oxygen ingress frequently observed within many monopiles across the industry. A key concern is that this situation may accelerate corrosion of the internal surfaces. On the external surfaces, the accumulation of biofouling is known to impede the safe transfer of technicians from vessel to transition piece (TP) and requires frequent cleaning. It is also likely to influence the dynamic behaviour of the foundation due to the added weight and the hydrodynamic loading due to thickness and surface roughness changes. There is sufficient evidence to suggest that the current offshore wind guidelines on biofouling could be improved to optimise the design margins. This thesis investigated the influence of internal monopile corrosion and external biofouling growth on the turbines at Teesside Offshore Wind Farm (owned and operated by EDF Energy). At Teesside, the primary drivers of internal monopile corrosion are identified as temperature, oxygen, pH and tidal variation. The influence of each of these parameters on the corrosion rate of monopile steel were investigated in a series of laboratory experiments and in-situ monopile trials. The experimental study was conducted at EDF laboratories in France using 186 corrosion coupons that were exposed to various treatments simulating internal monopile conditions. At Teesside, 49 coupons were suspended at various internal monopile locations across 5 foundations. In both cases, the weight loss measurement of coupons over time was used to determine the corrosion rates. Results suggest that tidal (wet/dry cycles) low pH and oxygen ingress have the greatest influence on the corrosion degradation of unprotected monopile steel. Internal tidal variations create a particularly aggressive corrosion environment. A decision tree matrix has been developed to predict corrosion rate classification (high/medium/low) under a range of environmental conditions. In parallel, a biofouling assessment was conducted at Teesside Offshore Wind Farm to determine the type and extent of marine growth on the intertidal and submerged zones of turbines. This has enabled a better understanding of the species diversity and community morphology but has also facilitated the development and testing of two sampling methodologies for the intertidal and subsea regions of offshore wind turbines; scrape sampling and remotely operated vehicle (ROV) surveying, respectively. The results of the assessment suggest a zonation pattern of marine growth with depth that is consistent with findings from other offshore wind farms and platforms. A super abundance of the non-native midge species T. japonicas at the intertidal zone has also been observed at other offshore wind farms in Belgium and Denmark, however, this is first evidence of its existence at a UK offshore wind farm. Removal of biofouling from the intertidal zones and jet-washing has now been optimised to coincide with peak settlement periods of mussels and barnacles. Image analysis and 3D mapping was conducted on the subsea ROV video footage to estimate thickness, roughness and added weight of biofouling. This research provides an initial investigation into the effects of internal corrosion and external biofouling on monopile foundations at Teesside Offshore Wind Farm. The methodologies developed for this investigation and the results are critically discussed in the context of asset life assessment and improvements are suggested in further work

Neural tube derived Wnt signals cooperate with FGF signaling in the formation and differentiation of the trigeminal placodes

BACKGROUND: Neurogenic placodes are focal thickenings of the embryonic ectoderm that form in the vertebrate head. It is within these structures that the precursors of the majority of the sensory neurons of the cranial ganglia are specified. The trigeminal placodes, the ophthalmic and maxillomandibular, form close to the midbrain-hindbrain boundary and many lines of evidence have shown that signals emanating from this level of the neuraxis are important for the development of the ophthalmic placode. RESULTS: Here, we provide the first evidence that both the ophthalmic and maxillomandibular placodes form under the influence of isthmic Wnt and FGF signals. Activated Wnt signals direct development of the Pax3 expressing ophthalmic placodal field and induce premature differentiation of both the ophthalmic and the maxillomandibular placodes. Similarly, overexpression of Fgf8 directs premature differentiation of the trigeminal placodes. Wnt signals require FGF receptor activity to initiate Pax3 expression and, subsequently, the expression of neural markers, such as Brn3a, within the cranial ectoderm. Furthermore, fibroblast growth factor signaling via the mitogen activated protein kinase pathway is required to maintain early neuronal differentiation within the trigeminal placodes. CONCLUSION: We demonstrate the identity of inductive signals that are necessary for trigeminal ganglion formation. This is the first report that describes how isthmic derived Wnt signals act in concert with fibroblast growth factor signaling. Together, both are necessary and sufficient for the establishment and differentiation of the ophthalmic and maxillomandibular placodes and, consequently, the trigeminal ganglion

Neural tube derived Wnt signals cooperate with FGF signaling in the formation and differentiation of the trigeminal placodes

<p>Abstract</p> <p>Background</p> <p>Neurogenic placodes are focal thickenings of the embryonic ectoderm that form in the vertebrate head. It is within these structures that the precursors of the majority of the sensory neurons of the cranial ganglia are specified. The trigeminal placodes, the ophthalmic and maxillomandibular, form close to the midbrain-hindbrain boundary and many lines of evidence have shown that signals emanating from this level of the neuraxis are important for the development of the ophthalmic placode.</p> <p>Results</p> <p>Here, we provide the first evidence that both the ophthalmic and maxillomandibular placodes form under the influence of isthmic Wnt and FGF signals. Activated Wnt signals direct development of the <it>Pax3 </it>expressing ophthalmic placodal field and induce premature differentiation of both the ophthalmic and the maxillomandibular placodes. Similarly, overexpression of <it>Fgf8 </it>directs premature differentiation of the trigeminal placodes. Wnt signals require FGF receptor activity to initiate <it>Pax3 </it>expression and, subsequently, the expression of neural markers, such as <it>Brn3a</it>, within the cranial ectoderm. Furthermore, fibroblast growth factor signaling via the mitogen activated protein kinase pathway is required to maintain early neuronal differentiation within the trigeminal placodes.</p> <p>Conclusion</p> <p>We demonstrate the identity of inductive signals that are necessary for trigeminal ganglion formation. This is the first report that describes how isthmic derived Wnt signals act in concert with fibroblast growth factor signaling. Together, both are necessary and sufficient for the establishment and differentiation of the ophthalmic and maxillomandibular placodes and, consequently, the trigeminal ganglion.</p

WLS Retrograde Transport to the Endoplasmic Reticulum during Wnt Secretion

SummaryWnts are transported to the cell surface by the integral membrane protein WLS (also known as Wntless, Evi, and GPR177). Previous studies of WLS trafficking have emphasized WLS movement from the Golgi to the plasma membrane (PM) and then back to the Golgi via retromer-mediated endocytic recycling. We find that endogenous WLS binds Wnts in the endoplasmic reticulum (ER), cycles to the PM, and then returns to the ER through the Golgi. We identify an ER-targeting sequence at the carboxyl terminus of native WLS that is critical for ER retrograde recycling and contributes to Wnt secretory function. Golgi-to-ER recycling of WLS requires the COPI regulator ARF as well as ERGIC2, an ER-Golgi intermediate compartment protein that is also required for the retrograde trafficking of the KDEL receptor and certain toxins. ERGIC2 is required for efficient Wnt secretion. ER retrieval is an integral part of the WLS transport cycle

Impact of Emerging Health Insurance Arrangements on Diabetes Outcomes and Disparities: Rationale and Study Design

Consumer-directed health plans combine lower premiums with high annual deductibles, Internet-based quality-of-care information, and health savings mechanisms. These plans may encourage members to seek better value for health expenditures but may also decrease essential care. The expansion of high-deductible health plans (HDHPs) represents a natural experiment of tremendous proportion. We designed a pre–post, longitudinal, quasi-experimental study to determine the effect of HDHPs on diabetes quality of care, outcomes, and disparities. We will use a 13-year rolling sample (2001–2013) of members of an HDHP and members of a control group. To reduce selection bias, we will limit participants to those whose employers mandate a single health insurance type. The study will measure rates of monthly hemoglobin A1c, lipid, and albuminuria testing; availability of blood glucose test strips; and rates of retinal examinations, high-severity emergency department visits, and preventable hospitalizations. Results could be used to design health plan features that promote high-quality care and better outcomes among people who have diabetes

A Cohort Study of Thiazolidinediones and Fractures in Older Adults with Diabetes

Context: Thiazolidenediones (TZDs) are selective ligands of peroxisome-proliferator-activated receptor-␥ and have been shown to reduce bone mineral density. Recent results from several randomized controlled trials find an increased risk of fracture with TZDs compared with other oral antidiabetic agents. Objective: The aim of the study was to determine the association between TZD use and fracture risk among older adults with diabetes. Design: We conducted a cohort study. Participants: Medicare beneficiaries with at least one diagnosis of diabetes initiating monotherapy for an oral hypoglycemic agent participated in the study. Main Outcome: We measured the incidence of fracture within the cohort. Results: Among the 20,964 patients with diabetes eligible for this study, 686 (3.3%) experienced a fracture during the median follow-up of approximately 10 months. Although not statistically significant, patients using only a TZD were more likely to experience a fracture than those using metformin (adjusted relative risk, 1.31; 95% confidence interval, 0.98 -1.77; P ϭ 0.071) or a sulfonylurea (adjusted relative risk, 1.21; 95% confidence interval, 0.94 -1.55; P ϭ 0.12). Each individual TZD was associated with an increased risk, with confidence intervals overlapping unity, compared with both metformin and sulfonylureas. The adjusted risk of any fracture associated with TZD use compared with metformin was elevated for non-insulin-using patients, women and men. If TZD use is associated with fractures, the number needed for one excess fracture when comparing TZD users to sulfonylurea users was 200, and the number was 111 when comparing TZDs with metformin. Conclusions: As has been found with other analyses, our data suggest that TZDs may be associated with an increased risk of fractures compared with oral sulfonylureas and metformin

Changing-look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. I. Sample from the Early Data

Changing-look active galactic nuclei (CL AGNs) can be generally confirmed by the emergence (turn-on) or disappearance (turn-off) of broad emission lines (BELs), associated with a transient timescale (about 100 ∼ 5000 days) that is much shorter than predicted by traditional accretion disk models. We carry out a systematic CL AGN search by crossmatching the spectra coming from the Dark Energy Spectroscopic Instrument and the Sloan Digital Sky Survey. Following previous studies, we identify CL AGNs based on Hα, Hβ, and Mg ii at z ≤ 0.75 and Mg ii, C iii], and C iv at z > 0.75. We present 56 CL AGNs based on visual inspection and three selection criteria, including 2 Hα, 34 Hβ, 9 Mg ii, 18 C iii], and 1 C iv CL AGN. Eight cases show simultaneous appearances/disappearances of two BELs. We also present 44 CL AGN candidates with significant flux variation of BELs, but remaining strong broad components. In the confirmed CL AGNs, 10 cases show additional CL candidate features for different lines. In this paper, we find: (1) a 24:32 ratio of turn-on to turn-off CL AGNs; (2) an upper-limit transition timescale ranging from 330 to 5762 days in the rest frame; and (3) the majority of CL AGNs follow the bluer-when-brighter trend. Our results greatly increase the current CL census (∼30%) and would be conducive to exploring the underlying physical mechanism

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

SRY and DAXI in mammalian sex determination

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