Interpretation of the Dynamic Response of a Masonry Arch Rail Viaduct Using Finite-Element Modeling

Linear-elastic finite-element analysis is sometimes used to assess masonry arch bridges under service loads, despite the limitations of this method. Specifically, linear-elastic analysis can be sensitive to material properties, geometry, and support settlements, while also allowing the development of tensile stresses that may be unrealistic for masonry structures. However, even though linear-elastic methods remain appealing for their simplicity, it is rare to evaluate their output against experimental data. In this paper, detailed strain and displacement monitoring data for a masonry arch viaduct are used to evaluate a series of independently developed linear-elastic simulations of this structure. Although uncertainties in input parameters mean the magnitude of modeling results cannot be presumed accurate, the simulated response pattern was found to agree reasonably well with monitoring data in regions of low damage. However, more damaged regions produced a markedly different local response. Comparisons between the simulations revealed useful conclusions regarding common modeling assumptions, namely the importance of modeling backing material, spandrels, and foundation stiffness, to capture their influence on the arch response.This work forms part of a PhD, which is funded through an EPSRC Doctoral Training Partnership (grant reference number EP/M506485/1). Data collection was made possible by the Cambridge Centre for Smart Infrastructure and Construction, through additional EPSRC funding (grant reference number EP/L010917/1)

The effects of native conifer encroachment and importance of high-severity wildfire in fire-excluded California black oak ecosystems of northern California

The absence of fire in many oak woodlands that historically experienced frequent fire has resulted in invasion and subsequent overtopping of oaks by fast-growing conifers. Little is known about the effects of these structural and compositional changes occurring in California black oak (Quercus kelloggii) woodlands. This study addresses two broad questions: 1) How will conifer-encroached California black oaks respond to re-introduced fire in areas that have gone unburned for many decades? And 2) what actions can forest managers take toward California black oak woodland restoration and maintenance over time? Tree competition around individual California black oaks, tree age, and California black oak post-fire responses were investigated in Klamath and Lassen National Forests in northern California. Plots were established around focal oaks where attributes of neighboring encroaching trees, tree regeneration, and fire effects were measured. At both sites woodland overstory was heavily dominated by relatively fire-intolerant conifers, particularly Douglas-fir (Pseudotsuga menziesii) and white fir (Abies concolor). At the Klamath site, trees that pierced California black oak crowns were younger than paired oaks. The probability of California black oak mortality from fire was correlated with neighboring Douglas-fir height, indicating a compromising effect of encroachment on oak survival. At the Lassen site 90% of killed California black oak stems sprouted following fire. Oak recovery was strongest in severely burned areas; linear modeling revealed significant negative relationships between overstory tree survival and both California black oak sprout height and basal area. A conceptual model for the formation and persistence of these specific stand structures is proposed in which fire severity and encroachment pressure affect compositional change over time. Unless specific management actions are taken to protect California black oak woodlands, many encroached stands may be converted to conifer forest.Thesis (M.S.)--Humboldt State University, Natural Resources: Forestry, 201

The three-dimensional flow of force in a damaged, skewed masonry arch railway bridge – Insights from fibre Bragg rosettes, videogrammetry, and modelling

Masonry arch bridges are common, especially in the UK and Europe, but interpretation of their structural behaviour can be challenging and is often complicated by histories of damage over their long working lives. Assessing the performance of repair works at these bridges is vital, to provide confidence in their continued use. This paper presents novel applications of fibre-optic sensing and videogrammetry to measure and visualise the three-dimensional, dynamic structural response of a skewed masonry arch railway bridge in unprecedented detail. In particular, fibre-optic strain rosettes are used to map the distributions of principal strains, and hence force flow, throughout the arch, while videogrammetry reveals a secondary load path in the form of transverse arch bending. Monitoring results are then combined with simplified analytical models of this transverse bending, to study the effectiveness of intervention works aimed at restoring structural connectivity between the arch and its spandrel walls

Deuterium brain imaging at 7T during D 2 O dosing

PurposeTo characterize the (2H) deuterium MR signal measured from human brain at 7T in participants loading with D2O to ˜1.5% enrichment over a six-week period.Methods2H spectroscopy and imaging measurements were used to track the time-course of 2H enrichment within the brain during the initial eight-hour loading period in two participants. Multi-echo gradient echo (MEGE) images were acquired at a range of TR values from four participants during the steady-state loading period and used for mapping 2H T1 and T2* relaxation times. Co-registration to higher resolution 1H images allowed T1 and T2* relaxation times of deuterium in HDO in cerebrospinal fluid (CSF), gray matter (GM), and white matter (WM) to be estimated.Results2H concentrations measured during the eight-hour loading were consistent with values estimated from cumulative D2O dose and body mass. Signal changes measured from three different regions of the brain during loading showed similar time-courses. After summing over echoes, gradient echo brain images acquired in 7.5 minutes with a voxel volume of 0.36 ml showed an SNR of ˜16 in subjects loaded to 1.5%. T1-values for deuterium in HDO were significantly shorter than corresponding values for 1H in H2O, while T2* values were similar. 2H relaxation times in CSF were significantly longer than in GM or WM.ConclusionDeuterium MR Measurements at 7T were used to track the increase in concentration of 2H in brain during heavy water loading. 2H T1 and T2* relaxation times from water in GM, WM, and CSF are reported

Gluconacetobacter diazotrophicus AZ0019 requires functional nifD gene for optimal plant growth promotion in tomato plants

Gluconacetobacter diazotrophicus is a nitrogen fixing bacterium able to colonise a wide range of host plants and is marketed as a biofertiliser due to its ability to promote plant growth. This study aims to investigate how biological nitrogen fixation (BNF) competency affects the growth promotion of inoculated tomato plants and to describe the colonisation mechanism of this bacterium in dicot systems. A nitrogen fixation impaired mutant (Gd nifD-) was produced by disrupting the nifD gene, which encodes the nitrogenase Mo-Fe subunit, in order to assess its plant growth promotion (PGP) capability in comparison to G. diazotrophicus wild type strain (Gd WT). Furthermore, tagged strains were employed to monitor the colonisation process through qPCR analyses and fluorescence microscopy. Following a preliminary glass house trial, Gd WT or Gd nifD- were applied to hydroponically grown tomato plants under nitrogen-replete and nitrogen-limiting conditions. Bacteria reisolation data and plant growth parameters including height, fresh weight, and chlorophyll content were assessed 15 days post inoculation (dpi). Gd WT significantly enhanced plant height, fresh weight, and chlorophyll content in both nitrogen conditions, while Gd nifD- showed a reduced PGP effect, particularly in terms of chlorophyll content. Both strains colonised plants at similar levels, suggesting that the growth advantages were linked to BNF capacity rather than colonisation differences. These findings indicate that a functional nifD gene is a fundamental requirement for optimal plant growth promotion by G. diazotrophicu

Mental Imagery to Reduce Alcohol-related harm in patients with alcohol use disorder and alcohol-related liver damaGE

OBJECTIVE: The healthcare burden of alcohol-related liver disease (ARLD) is increasing. ARLD and alcohol use disorder (AUD) is best managed by reduction or cessation of alcohol use, but effective treatments are lacking. We tested whether people with ARLD and AUD admitted to hospital could be recruited to and retained in a trial of Functional Imagery Training (FIT), a psychological therapy that uses mental imagery to reduce alcohol craving. We conducted a multicentre randomised pilot trial of treatment as usual (TAU) versus FIT+TAU in people admitted to hospital with ARLD and AUD. DESIGN: Participants were randomised to TAU (a single session of brief intervention) or FIT+TAU (TAU with one hospital-based FIT session then eight telephone sessions over 6 months). Pilot outcomes included recruitment rate and retention at day 180. Secondary outcomes included fidelity of FIT delivery, alcohol use, and severity of alcohol dependence. RESULTS: Fifty-four participants (mean age 49; 63% male) were recruited and randomised, 28 to TAU and 26 to FIT+TAU. The retention rate at day 180 was 43%. FIT was delivered adequately by most alcohol nurses. 50% of intervention participants completed FIT sessions 1 and 2. There were no differences in alcohol use or severity of alcohol dependence between treatment groups at day 180. CONCLUSION: Participants with ARLD and AUD could be recruited to a trial of FIT versus FIT+TAU. However, retention at day 180 was suboptimal. Before conducting a definitive trial of FIT in this patient group, modifications in the intervention and recruitment/retention strategy must be tested. TRIAL REGISTRATION NUMBER: ISRCTN41353774

Omega-3 polyunsaturated fatty acid supplementation versus placebo on vascular health, glycaemic control, and metabolic parameters in people with type 1 diabetes: a randomised controlled preliminary trial

Background: The role of omega-3 polyunsaturated fatty acids (n-3PUFA), and the potential impact of n-3PUFA supplementation, in the treatment and management of type 1 diabetes (T1D) remains unclear and controversial. Therefore, this study aimed to examine the efficacy of daily high-dose-bolus n-3PUFA supplementation on vascular health, glycaemic control, and metabolic parameters in subjects with T1D. Methods: Twenty-seven adults with T1D were recruited to a 6-month randomised, double-blind, placebo-controlled trial. Subjects received either 3.3 g/day of encapsulated n-3PUFA or encapsulated 3.0 g/day corn oil placebo (PLA) for 6-months, with follow-up at 9-months after 3-month washout. Erythrocyte fatty acid composition was determined via gas chromatography. Endpoints included inflammation-associated endothelial biomarkers (vascular cell adhesion molecule-1 [VCAM-1], intercellular adhesion molecule-1 [ICAM-1], E-selectin, P-selectin, pentraxin-3, vascular endothelial growth factor [VEGF]), and their mediator tumor necrosis factor alpha [TNFα] analysed via immunoassay, vascular structure (carotid intima-media thickness [CIMT]) and function (brachial artery flow mediated dilation [FMD]) determined via ultrasound technique, blood pressure, glycosylated haemoglobin (HbA1c), fasting plasma glucose (FPG), and postprandial metabolism. Results: Twenty subjects completed the trial in full. In the n-3PUFA group, the mean ± SD baseline n-3PUFA index of 4.93 ± 0.94% increased to 7.67 ± 1.86% (P  0.05). Conclusions: This study indicates that daily high-dose-bolus of n-3PUFA supplementation for 6-months does not improve vascular health, glucose homeostasis, or metabolic parameters in subjects with T1D. The findings from this preliminary RCT do not support the use of therapeutic n-3PUFA supplementation in the treatment and management of T1D and its associated complications. Trial Registration ISRCTN, ISRCTN40811115. Registered 27 June 2017, http://www.isrctn.com/ISRCTN40811115

The effects of native conifer encroachment and importance of high-severity wildfire in fire-excluded California black oak ecosystems of northern California

The absence of fire in many oak woodlands that historically experienced frequent fire has resulted in invasion and subsequent overtopping of oaks by fast-growing conifers. Little is known about the effects of these structural and compositional changes occurring in California black oak (Quercus kelloggii) woodlands. This study addresses two broad questions: 1) How will conifer-encroached California black oaks respond to re-introduced fire in areas that have gone unburned for many decades? And 2) what actions can forest managers take toward California black oak woodland restoration and maintenance over time? Tree competition around individual California black oaks, tree age, and California black oak post-fire responses were investigated in Klamath and Lassen National Forests in northern California. Plots were established around focal oaks where attributes of neighboring encroaching trees, tree regeneration, and fire effects were measured. At both sites woodland overstory was heavily dominated by relatively fire-intolerant conifers, particularly Douglas-fir (Pseudotsuga menziesii) and white fir (Abies concolor). At the Klamath site, trees that pierced California black oak crowns were younger than paired oaks. The probability of California black oak mortality from fire was correlated with neighboring Douglas-fir height, indicating a compromising effect of encroachment on oak survival. At the Lassen site 90% of killed California black oak stems sprouted following fire. Oak recovery was strongest in severely burned areas; linear modeling revealed significant negative relationships between overstory tree survival and both California black oak sprout height and basal area. A conceptual model for the formation and persistence of these specific stand structures is proposed in which fire severity and encroachment pressure affect compositional change over time. Unless specific management actions are taken to protect California black oak woodlands, many encroached stands may be converted to conifer forest

The effects of native conifer encroachment and importance of high-severity wildfire in fire-excluded California black oak ecosystems of northern California

Thesis (M.S.)--Humboldt State University, Natural Resources: Forestry, 2011The absence of fire in many oak woodlands that historically experienced frequent fire has resulted in invasion and subsequent overtopping of oaks by fast-growing conifers. Little is known about the effects of these structural and compositional changes occurring in California black oak (Quercus kelloggii) woodlands. This study addresses two broad questions: 1) How will conifer-encroached California black oaks respond to re-introduced fire in areas that have gone unburned for many decades? And 2) what actions can forest managers take toward California black oak woodland restoration and maintenance over time? Tree competition around individual California black oaks, tree age, and California black oak post-fire responses were investigated in Klamath and Lassen National Forests in northern California. Plots were established around focal oaks where attributes of neighboring encroaching trees, tree regeneration, and fire effects were measured. At both sites woodland overstory was heavily dominated by relatively fire-intolerant conifers, particularly Douglas-fir (Pseudotsuga menziesii) and white fir (Abies concolor). At the Klamath site, trees that pierced California black oak crowns were younger than paired oaks. The probability of California black oak mortality from fire was correlated with neighboring Douglas-fir height, indicating a compromising effect of encroachment on oak survival. At the Lassen site 90% of killed California black oak stems sprouted following fire. Oak recovery was strongest in severely burned areas; linear modeling revealed significant negative relationships between overstory tree survival and both California black oak sprout height and basal area. A conceptual model for the formation and persistence of these specific stand structures is proposed in which fire severity and encroachment pressure affect compositional change over time. Unless specific management actions are taken to protect California black oak woodlands, many encroached stands may be converted to conifer forest.United States Department of Agriculture - Forest Service, Pacific Southwest Research Statio