Use of Dredged Material for Oyster Habitat Creation in Coastal Virginia

Dredging can have a beneficial effect on oyster habitat when the placement of the dredged material is effectively managed to help provide the bottom structure necessary to develop an oyster reef. Construction and maintenance of the Waterway on the Coast of Virginia (WCV) by the U. S. Army Corps of Engineers (Corps) has provided a number of examples of this process, both serendipitous and deliberate. The historical development of reefs that evolved from the random overboard placement of dredged material and the subsequent leasing of these areas for oyster cultivation is reviewed. A monitoring plan for the development of a reef in Swash Bay using maintenance dredging material is also described including pre- and post-dredging hydrographic surveys, surface sediment distributions, and shellfish surveys. After one year, the benthic communities at the recently used placement site, the historical placement site and an unimpacted area in Swash Bay were compared using the Benthic Assessment Method (BAM) to determine short-term impacts. The historical and unimpacted sites had very similar values while the recently used site was somewhat lower. Consequences of continued success in developing oyster reefs in close proximity to a dredged channel are addressed with a suggested management plan that involves rotating the placement among a number of sites. This would allow for the continued maintenance of both the channel and the adjacent oyster reefs.https://scholarworks.wm.edu/vimsbooks/1090/thumbnail.jp

Assessing Cross anisotropy of Small-Strain Stiffness Using the Resonant Column apparatus

Almost all soils exhibit cross-anisotropic stiffness to some extent. However, measuring the cross anisotropic properties of soils is difficult because of the need to determine the 3 independent stiffness parameters Eν, Eh, Gνh, and the associated Poisson’s ratios, nνh and nhh. Current techniques that are employed, for example using bender elements or field geophysics, are not always reliable, whilst preparing specimens in different orientations and subsequent testing using standard laboratory techniques has practical constraints. The resonant column is a laboratory apparatus that has been extensively used to measure the torsional stiffness (Gνh). Relatively recent development has also allowed the Stokoe resonant column to measure Young’s modulus from flexural excitation of the specimen. The apparatus has also been used to determine Eν through axial oscillation. Thus a modified resonant column apparatus can apply four different excitations (flexure in two directions, torsion and longitudinal excitation) to a soil. This paper reports a series of dynamic finite element numerical simulations of physical tests in the resonant column apparatus, carried out to model both the apparatus and a cross-anisotropic soil specimen. Forward modelling has been carried out to determine the impact of different degrees of anisotropy on the resonant frequencies of ‘specimens’ with their axes of anisotropy aligned in different directions relative to the vertical axis of the apparatus. Methods of determining the elastic parameters from these data are assessed

Inequalities in the distribution of COVID-19-related financial difficulties for Australian families with young children

BACKGROUND: We examine (1) the frequency of financial difficulties in Australian families with young children (0-8 years) in the early and later phases of the pandemic; (2) the extent to which parents' pre-pandemic socio-economic disadvantage (SED) predicted financial difficulties; and (3) whether grandparent intergenerational SED further amplified this risk. METHOD: Data: Australian Temperament Project (ATP; established 1983, N = 2443) and ATP Generation 3 study (ATPG3; established 2012; N = 702), of which 74% (N = 553) completed a COVID-specific module in the early (May-September 2020) and/or later (October-December 2021) phases of the pandemic. OUTCOMES: Parent-reported loss of employment/reduced income, difficulty paying for essentials, and financial strain. EXPOSURES: Pre-pandemic parent and grandparent education and occupation. ANALYSIS: Logistic regressions, estimated via generalized estimating equations, were used to examine associations between the pre-pandemic SED of parents and grandparents and their interaction with financial difficulties, adjusting for potential confounders. RESULTS: At both pandemic time points, a third of parents reported adverse financial impacts (early: 34%, 95% confidence interval [CI] = 30-38; later: 32%, 95% CI = 28-36). Each standard deviation increase in the parents' pre-pandemic SED was associated with a 36% increase in the odds of reporting multiple financial difficulties (odds ratio [OR] = 1.36, 95% CI = 1.04-1.78). There was little evidence of an interaction between the SED of parents and grandparents. CONCLUSIONS: Financial impacts related to the COVID-19 pandemic were common and, irrespective of grandparent SED, disproportionately borne by parents with higher pre-pandemic SED. Given the well-established relationship between disadvantage and child health and development, sustained and well-targeted government supports will be critical to minimizing adverse impacts in years to come

The stiffess of unsaturated railway formations

The rational design of a substructure to support a rail track requires an estimation of the stiffness value of the formation on which it is to be built. Stiffness values derived from back-analyses of deformations of the ground beneath the track have been found by the authors to be much higher than those predicted from laboratory element testing on saturated specimens. This may be because of differences in compaction between field and laboratory, or because suctions created by lack of saturation play a key role in controlling stiffness, and therefore the performance of the track when in use. To test the latter hypothesis a laboratory study has been carried out on material representative of that found in South African railway formations. This was tested at constant dry density and various water contents, with matric suctions determined using different established techniques, and very-small-strain stiffness levels obtained from resonant column testing. A suction stress characteristic curve was developed to identify the contribution of suction to the overall effective stress for this material. The results show that suction can indeed be an important contributing factor to the magnitude of stiffness. For material tested at constant dry density, the stiffness initially increases with reducing compaction water content, and therefore with increasing suction. It subsequently reduces back towards the saturated value as the compaction water content approaches zero, even though the matric suction continues to increase. The relative increase in very-small-strain stiffness due to suction depends, to a large extent, on the net normal stress during the stiffness measurement. The effect of matric suction is proportionately greatest at the low net normal stress levels that apply for shallow infrastructures such as rail formations. Also, the operational stiffness depends not only on the current water content (and therefore suction), but also on the water content at which the material has been compacted.The Engineering and Physical Sciences Research Council’s ‘Rail Research UK’ programmehttp://pif.sagepub.comhb2016Civil Engineerin

The Tribological Behaviour of Carbon Fibre Reinforced Polyaryletherketones (PAEKs) through their Glass Transitions.

yesAdvanced engineering polymers of the Polyaryletherketone (PAEK) family with carbon fibre reinforcement are finding application in engineering systems as tribological bearing surfaces under severe operating conditions that cyclically move the polymer into and beyond the glass transition temperature region. To support such an application, the friction in high speed and low load PAEK-steel sliding contacts was investigated both unlubricated and lubricated with a trinonyl trimellitate ester, a base fluid for high temperature industrial lubricants. Four polymers in the PAEK family, PEEK, PEK, PEKEKK and PEKK, with 30%wt of carbon fibre whiskers were tested against an AISI 4140 steel disc. When unlubricated, low friction depended upon the formation of a PAEK transfer film on the steel disc and when this became unstable in the glass transition region the friction increased to much higher levels with associated polymer surface damage. Frictional heating due to the high sliding speed dominated the differences in glass transition behaviour between the four PAEKs. When lubricated, the lubricant film controlled friction and there was no significant effect of the glass transition of any of the PAEKs. The irreversible nature of the glass transition in PAEKs in such tribological applications, due to high surface damage at high temperature, means that it is essential to ensure effective lubrication in both fluid film and boundary lubrication.Innovate UK, Knowledge Transfer Partnershi

Finding the Patient’s Voice Using Big Data: Analysis of Users’ Health-Related Concerns in the ChaCha Question-and-Answer Service (2009–2012)

Background: The development of effective health care and public health interventions requires a comprehensive understanding of the perceptions, concerns, and stated needs of health care consumers and the public at large. Big datasets from social media and question-and-answer services provide insight into the public’s health concerns and priorities without the financial, temporal, and spatial encumbrances of more traditional community-engagement methods and may prove a useful starting point for public-engagement health research (infodemiology). Objective: The objective of our study was to describe user characteristics and health-related queries of the ChaCha question-and-answer platform, and discuss how these data may be used to better understand the perceptions, concerns, and stated needs of health care consumers and the public at large. Methods: We conducted a retrospective automated textual analysis of anonymous user-generated queries submitted to ChaCha between January 2009 and November 2012. A total of 2.004 billion queries were read, of which 3.50% (70,083,796/2,004,243,249) were missing 1 or more data fields, leaving 1.934 billion complete lines of data for these analyses. Results: Males and females submitted roughly equal numbers of health queries, but content differed by sex. Questions from females predominantly focused on pregnancy, menstruation, and vaginal health. Questions from males predominantly focused on body image, drug use, and sexuality. Adolescents aged 12–19 years submitted more queries than any other age group. Their queries were largely centered on sexual and reproductive health, and pregnancy in particular. Conclusions: The private nature of the ChaCha service provided a perfect environment for maximum frankness among users, especially among adolescents posing sensitive health questions. Adolescents’ sexual health queries reveal knowledge gaps with serious, lifelong consequences. The nature of questions to the service provides opportunities for rapid understanding of health concerns and may lead to development of more effective tailored interventions. [J Med Internet Res 2016;18(3):e44

Effect of monthly vitamin D3 supplementation in healthy adults on adverse effects of earthquakes: randomised controlled trial

Objective: To determine whether supplementation with vitamin D improves resilience to the adverse effects of earthquakes. Design: Opportunistic addition to an established randomised double blind placebo controlled trial. Setting: Christchurch, New Zealand, where a prolonged series of catastrophic earthquakes beginning on 4 September 2010 occurred, which caused widespread destruction, fatalities, and extensive psychological damage. Participants: 322 healthy adults (241 women; 81 men) aged 18-67 who were already participating in the vitamin D and acute respiratory infections study (VIDARIS) between February 2010 and November 2011. Intervention Participants were randomised to receive an oral dose of either 200 000 IU vitamin D3 monthly for two months then 100 000 IU monthly (n=161) or placebo (n=161) for a total of 18 months. Main outcome measure This is a post hoc analysis from the previously published VIDARIS trial. The primary endpoint in the current analysis was the self reported effects and overall adverse impact of the Christchurch earthquakes as assessed by questionnaire four months after the most destructive earthquake on 22 February 2011, which was used as the index event. The secondary end point was the number of “psychological” adverse events that participants reported at their usual monthly appointments as part of the original VIDARIS trial. Results: 308 participants completed the earthquake impact questionnaire (n=152 in the vitamin D group and 156 in the placebo group). There was no significant difference in the number of self reported adverse effects between those receiving vitamin D supplementation and those receiving placebo. There was also no difference in the overall adverse impact score between treatment groups (χ2 P=0.44). The exception was that those in the vitamin D group experienced more adverse effects on family relationships (22% v 13%; χ2 P=0.03). The number of psychological adverse events—such as fatigue, stress, anxiety, and insomnia—that participants reported at their usual monthly appointments was significantly higher after the earthquake (χ2 P=0.007) but did not differ between treatment groups. Conclusion: In this trial, vitamin D supplementation did not reduce the adverse impact of earthquakes in healthy adults. Trial registration Australian New Zealand Clinical Trials Registry (anzctr.org.au) ACTRN1260900048622