Design of cylindrical plastic pipe linings to resist buckling due to collapse pressures

Flexible (non-bonded) polymeric sewer linings are used extensively to renovate both gravity and pressure pipes. Linings for both types of pipe are subject to collapse pressures, and in the case of gravity pipes this is the dominant source of loading; the efficient design of linings to sustain collapse pressures is therefore an important problem. In this paper, the buckling of an ideal thinwalled elastic lining in a rigid cylindrical cavity is first presented as a simple closed form solution, and The effect of a representative small imperfection shown to be significant. The different types of imperfection that can be encountered in practical lined pipe systems are identified, and the situations in which each can arise are discussed. A generalised procedure for obtaining the structural imperfections in, and hence buckling capacities of, practical systems is then presented and two example applications are used to illustrate its application in specific situations

Effect of compaction pressure on consolidation behaviour of unsaturated silty soil

The effect of compaction pressure on subsequent soil behaviour during isotropic consolidation has been investigated by conducting controlled-suction triaxial tests on samples of an unsaturated compacted silty soil. A comprehensive set of laboratory experiments was carried out in a double-walled triaxial apparatus on samples of unsaturated soil that were prepared using two different compaction pressures. The axis translation technique was used for creating the desired suctions in the samples. In the experiments, the soil samples were subjected to isotropic consolidation under constant suctions. The results show that different compaction pressures produce different fabrics in a soil and therefore affect the behaviour of the soil. The results also show that the value of yield stress and the location of the loading¿collapse (LC) yield curve are functions of soil fabric. Furthermore, it is shown that the slopes of normal consolidation lines for densely and loosely compacted samples differ in unsaturated conditions but are the same in saturated soils. A comparison is made between the behaviour of the dense and loose samples, and the difference in the behaviour is explained

A comparison of substance use behaviours and normative beliefs in North West European university and college students.

The social norms approach is an increasingly popular intervention for substance use that has been used extensively in the American college system. It operates by correcting normative misperceptions individuals hold about their peers. However, there have been few direct comparisons of substance use misperceptions between student populations in different European countries. The current study sought to address this through use of a survey of substance use and normative beliefs at universities in five European countries. Students at each site were invited to take part in an online survey that included items on personal substance use and the perceived use of peers. A total sample of 6404 students was obtained. Mann-Whitney and χ2 analysis were used to demonstrate an apparent misperception effect, with the majority of students at each site significantly (p<0.05) overestimating the substance use of their peers. This study suggests that students in Europe are prone to misperceiving the substance use of their peers in a manner similar to their American college counterparts, despite the cultural and legislative differences between these settings. This provides support for the potential in using social norms approaches to reduce rates of harmful substance use in European student populations

Promise and pitfalls in the application of big data to occupational and environmental health

EditorialIs “big data” merely a catchphrase, or does the approach hold real promise in informing occupational and environmental health? Can challenges related to messy and unrepresentative data and spurious findings be overcome

The adrenocortical response to synthetic ACTH following a trek to high altitude

Background: Gradual ascent to high altitude is typically associated with reduced resting aldosterone and unchanged cortisol, features that may facilitate acclimatization but are poorly understood. Aims: To investigate the cortisol and aldosterone response to adrenocorticotrophic hormone at altitude. Methods: Eleven subjects underwent a 250 µg short synacthen test at sea-level and again after trekking to 3600 m in Nepal. Cortisol and aldosterone were measured by conventional assay from blood samples taken immediately prior to the administration of synacthen (T0) and then 30 (T30) and 60 (T60) minutes later. Results: At 3600 m resting basal cortisol and aldosterone levels were both significantly lower than they were at sea-level (p=0.004, p=0.003 respectively). Cortisol values at T30 and T60 were no different between sea-level and 3600 m but the increment after synacthen was significantly (p=0.041) greater at 3600 m due to a lower basal value. Aldosterone at T30 and T60 was significantly lower (p=0.003 for both) at 3600 m than at sea-level and the increment following synacthen was also significantly (p=0.003) less at 3600 m. Conclusions: At 3600 m there appears to be a divergent adrenal response to synthetic adrenocorticotrophic hormone with an intact cortisol response but a reduced aldosterone response, relative to sea-level. This may reflect a specific effect of hypoxia on aldosterone synthesis and may be beneficial to acclimatization

Implementation of the participatory approach for supervisors to prevent sick leave: a process evaluation

To perform a process evaluation of a multifaceted strategy to implement the participatory approach for supervisors to prevent sick leave in three organisations. The implementation strategy incorporated a working group meeting with stakeholder representatives, supervisor training, and optional supervisor coaching. Context, recruitment, reach, dose delivered, dose received, fidelity, and satisfaction with the strategy were assessed at organisational and supervisor level using questionnaires and registration forms. At least 4 out of 6 stakeholders were represented in the working group meetings, and 11 % (n = 116) of supervisors could be reached. The working group meetings and supervisor training were delivered and received as planned and were well appreciated within all three organisations. Three supervisors made use of coaching. At 6-month follow-up, 11 out of 41 supervisors (27 %) indicated that they had applied the participatory approach at least one time. The implementation strategy was largely carried out as intended. However, reach of both supervisors and department managers should be improved. Future studies should consider targeting employees with the strategy

Major changes in glacial and Holocene terrestrial temperatures and sources of organic carbon recorded in the Amazon fan by tetraether lipids

The Amazon basin is a major component of the global carbon and hydrological cycles, a significant natural source of methane, and home to remarkable biodiversity and endemism. Reconstructing past climate changes in the Amazon basin is important for a better understanding of the effect of such changes on these critical functions of the basin. Using a novel biomarker proxy, based on the membrane lipids of soil bacteria with a new regional calibration, we present a reconstruction of changes in mean annual air temperatures for the Amazon catchment during the last 37 kyr B. P. Biomarkers were extracted from Ocean Drilling Program sediment core ODP942 recovered from the Amazon fan. The Amazon fan is a major depository for terrestrial sediments, with the advantage that the terrestrial material captured reflects a regional integration of the whole river catchment. The reconstructed tropical Amazonian temperatures were similar to 5 degrees C cooler at the Last Glacial Maximum (similar to 21 degrees C) compared to modern values (similar to 26 degrees C). This is in agreement with previous estimates of tropical continental temperatures in the tropical Amazon basin and tropical Africa during the Last Glacial Maximum. Moreover, we also illustrate how the soil bacterial membrane lipid record reveals major changes in basin dynamics and sediment provenance during the glacial-Holocene transition, impacting the biomarker reconstructions from similar to 11 kyr onward

Phenoconversion from probable rapid eye movement sleep behavior disorder to mild cognitive impairment to dementia in a population-based sample

© 2017 The Authors Introduction Rapid eye movement sleep behavior disorder (RBD) is strongly associated with synucleinopathies. In 2012, we reported an increased risk of mild cognitive impairment (MCI) and Parkinson disease (PD) in cognitively normal Olmsted County, Minnesota, residents, aged 70 to 89 years with probable RBD. Here, we examine their progression to dementia and other neurodegenerative phenotypes. Methods Fifteen participants with RBD who were diagnosed with either MCI or PD were longitudinally followed, and their subsequent clinical courses were reviewed. Results Over 6.4 ± 2.9 years, six of the 14 participants with MCI developed additional neurodegenerative signs, five of whom had Lewy body disease features. Four of them progressed to dementia at a mean age 84.8 ± 4.9 years, three of whom met the criteria for probable dementia with Lewy bodies. One subject with PD developed MCI, but not dementia. Discussion Our findings from the population-based sample of Olmsted County, Minnesota, residents suggest that a substantial number of RBD patients tend to develop overt synucleinopathy features over time, and RBD patients who develop MCI and subsequent dementia have clinical features most consistent with dementia with Lewy bodies

Collateral and Debt Maturity Choice. A Signaling Model

This paper derives optimal loan policies under asymmetric information where banks offer loan contracts of long and short duration, backed or unbacked with collateral. The main novelty of the paper is that it analyzes a setting in which high quality firms use collateral as a complementary device along with debt maturity to signal their superiority. The least-cost signaling equilibrium depends on the relative costs of the signaling devices, the difference in firm quality and the proportion of good firms in the market. Model simulations suggest a non-monotonic relationship between firm quality and debt maturity, in which high quality firms have both long-term secured debt and short-term secured or non-secured debt.

Adrenal suppression in patients taking inhaled glucocorticoids is highly prevalent and management can be guided by morning cortisol

Context Up to 3% of US and UK populations are prescribed glucocorticoids (GC). Suppression of the hypothalamo–pituitary–adrenal axis with the potential risk of adrenal crisis is a recognized complication of therapy. The 250 μg short Synacthen stimulation test (SST) is the most commonly used dynamic assessment to diagnose adrenal insufficiency. There are challenges to the use of the SST in routine clinical practice, including both the staff and time constraints and a significant recent increase in Synacthen cost. Methods We performed a retrospective analysis to determine the prevalence of adrenal suppression due to prescribed GCs and the utility of a morning serum cortisol for rapid assessment of adrenal reserve in the routine clinical setting. Results In total, 2773 patients underwent 3603 SSTs in a large secondary/tertiary centre between 2008 and 2013 and 17.9% (n=496) failed the SST. Of 404 patients taking oral, topical, intranasal or inhaled GC therapy for non-endocrine conditions, 33.2% (n=134) had a subnormal SST response. In patients taking inhaled GCs without additional GC therapy, 20.5% (34/166) failed an SST and suppression of adrenal function increased in a dose-dependent fashion. Using receiver operating characteristic curve analysis in patients currently taking inhaled GCs, a basal cortisol ≥348 nmol/l provided 100% specificity for passing the SST; a cortisol value <34 nmol/l had 100% sensitivity for SST failure. Using these cut-offs, 50% (n=83) of SSTs performed on patients prescribed inhaled GCs were unnecessary. Conclusion Adrenal suppression due to GC treatment, particularly inhaled GCs, is common. A basal serum cortisol concentration has utility in helping determine which patients should undergo dynamic assessment of adrenal function