Size Effect of Hydrated Lime on the Mechanical Performance of Asphalt Concrete.

Despite widespread agreement on the beneficial nature of hydrated lime (HL) addition to asphalt concrete mixes, understanding of the effect of HL particle size is still limited. Previous investigations have focused mainly on two different size comparisons, and so certain guidance for a practical application cannot yet be produced. This study investigates three distinct sizes of HL, in the range of regular, nano, and sub-nano scales, for their effects on the properties of modified asphalt concretes. Five different percentages of HL as a partial replacement of ordinary limestone filler in asphalt concrete mixes were studied for wearing course application purposes. Experimental tests were conducted to evaluate the mechanical properties, including resistance to plastic flow, volumetric properties, moisture susceptibility, resilient modulus, and permanent deformation. The results revealed that a positive correlation exists between the mechanical properties and the fineness of HL particle sizes.

Using Age Tracers and Decadal Sampling to Discern Trends in Nitrate, Arsenic, and Uranium in Groundwater Beneath Irrigated Cropland.

Repeat sampling and age tracers were used to examine trends in nitrate, arsenic, and uranium concentrations in groundwater beneath irrigated cropland. Much higher nitrate concentrations in shallow modern groundwater were observed at both the Columbia Plateau and High Plains sites (median values of 10.2 and 15.4 mg/L as N, respectively) than in groundwater that recharged prior to the onset of intensive irrigation (median values of <1 and <4 mg/L as N, respectively). Repeat sampling of these well networks indicates that high nitrate concentrations in modern, shallow groundwater have been sustained for decades, posing a future risk to older, deeper groundwater used for drinking water. In fact, nitrate concentrations in older modern water (30-60 years since recharge) at the High Plains site have increased in the past decade. Groundwater irrigated areas in the Columbia Plateau tend to have higher nitrate concentrations in groundwater than surface water irrigated areas, suggesting repeated dissolution of land applied fertilizer during recirculation may be an important factor causing high nitrate concentrations in groundwater. Mobilization of uranium and arsenic by land surface activities is suggested by the higher concentrations of these constituents in modern, shallow groundwater than in older, deeper groundwater at the Columbia Plateau site. Bicarbonate concentrations in modern groundwater are positively correlated with uranium (r = 0.72, p < 0.01), suggesting bicarbonate may mobilize uranium in this system. A positive correlation between arsenic and phosphorus concentrations in modern groundwater (r = 0.55, p < 0.01) suggests that phosphate from fertilizer outcompetes arsenate for sorption sites, mobilizing sorbed arsenic derived from past pesticide use or other sources.

Socio-economic status in childhood and later alcohol use: a systematic review.

AIM: To conduct a systematic review of longitudinal studies that examined the association between childhood socio-economic status (SES) and alcohol use in later life. METHODS: A systematic search to identify all longitudinal population-based studies that examined the association between childhood SES and later alcohol use. RESULTS: Nineteen relevant articles were identified (eight birth cohorts and 11 papers on school-aged cohorts). There was little consistent evidence to support an association between lower childhood SES and later (mis)use of alcohol. Only a minority of studies included assessment of problem alcohol use, and in only one study was the relationship between SES and alcohol use the main research question. CONCLUSION: We found little robust evidence to support the assumption that childhood disadvantage is associated with later alcohol use/abuse. Given the importance of this issue in terms of policy, the lack of evidence is surprising and emphasizes the need for further research in order to inform future policies and public health messages.

Alcohol consumption as a risk factor for anxiety and depression: results from the longitudinal follow-up of the National Psychiatric Morbidity Survey.

BACKGROUND: Longitudinal studies have been in conclusive in identifying alcohol as a risk factor for anxiety and depression. AIMS: To examine whether excessive alcohol consumption is a risk factor for anxiety and depression in the general population, and whether anxiety and depression are risk factors for excessive alcohol consumption. METHOD: Data were analysed from the 18-month follow-up of the Psychiatric Morbidity Among Adults Living in Private Households, 2000 survey. RESULTS: Hazardous and dependent drinking were not associated with onset of anxiety and depression at follow-up. Binge-drinking was non-significantly associated with incident anxiety and depression (adjusted OR=1.36, 95% CI 0.74-2.50). Abstainers were less likely to have new-onset anxiety and depression at follow-up. Anxiety and depression or sub-threshold symptoms at baseline were not associated with incident hazardous or binge-drinking at follow-up, but there was weak evidence linking sub-threshold symptoms with onset of alcohol dependence (adjusted OR=2.04, 95% CI 0.84-4.97). CONCLUSIONS: Excessive alcohol consumption was not associated with the onset of anxiety and depression but abstinence was associated with a lower risk. Sub-threshold symptoms were weakly associated with new-onset alcohol dependence.