Correlation regimes in fluctuations of fatigue crack growth

This paper investigates correlation properties of fluctuations in fatigue crack growth of polycrystalline materials, such as ductile alloys, that are commonly encountered in structures and machinery components of complex electromechanical systems. The model of crack damage measure indicates that the fluctuations of fatigue crack growth are characterized by strong correlation patterns within short time scales and are uncorrelated for larger time scales. The two correlation regimes suggest that the 7075-T6 aluminum alloy, analyzed in this paper, is characterized by a micro-structure which is responsible for an intermittent correlated dynamics of fatigue crack growth within a certain scale. The constitutive equations of the damage measure are built upon the physics of fracture mechanics and are substantiated by Karhunen-Lo\`{e}ve decomposition of fatigue test data. Statistical orthogonality of the estimated damage measure and the resulting estimation error is demonstrated in a Hilbert space setting.Comment: 30 pages, 8 figures, to appear in Physica

Factors influencing fatigue in UK nurses working in respiratory clinical areas during the second wave of the Covid‐19 pandemic: An online survey

AIMS AND OBJECTIVES: This study explores UK nurses' experiences of working in a respiratory clinical area during the COVID‐19 pandemic over winter 2020. BACKGROUND: During the first wave of the pandemic, nurses working in respiratory clinical areas experienced significant levels of anxiety and depression. As the pandemic has progressed, levels of fatigue in nurses have not been assessed. METHODS: A cross‐sectional e‐survey was distributed via professional respiratory societies and social media. The survey included Generalised Anxiety Disorder Assessment (GAD7), Patient Health Questionnaire (PHQ9, depression), a resilience scale (RS‐14) and Chalder mental and physical fatigue tools. The STROBE checklist was followed as guidance to write the manuscript. RESULTS: Despite reporting anxiety and depression, few nurses reported having time off work with stress, most were maintaining training and felt prepared for COVID challenges in their current role. Nurses reported concerns over safety and patient feedback was both positive and negative. A quarter of respondents reported wanting to leave nursing. Nurses experiencing greater physical fatigue reported higher levels of anxiety and depression. CONCLUSIONS: Nurses working in respiratory clinical areas were closely involved in caring for COVID‐19 patients. Nurses continued to experience similar levels of anxiety and depression to those found in the first wave and reported symptoms of fatigue (physical and mental). A significant proportion of respondents reported considering leaving nursing. Retention of nurses is vital to ensure the safe functioning of already overstretched health services. Nurses would benefit from regular mental health check‐ups to ensure they are fit to practice and receive the support they need to work effectively. RELEVANCE TO CLINICAL PRACTICE: A high proportion of nurses working in respiratory clinical areas have been identified as experiencing fatigue in addition to continued levels of anxiety, depression over winter 2020. Interventions need to be implemented to help provide mental health support and improve workplace conditions to minimise PTSD and burnout

The complete plasmid sequences of Salmonella enterica serovar Typhimurium U288.

Salmonella enterica Serovar Typhimurium U288 is an emerging pathogen of pigs. The strain contains three plasmids of diverse origin that encode traits that are of concern for food security and safety, these include antibiotic resistant determinants, an array of functions that can modify cell physiology and permit genetic mobility. At 148,711 bp, pSTU288-1 appears to be a hybrid plasmid containing a conglomerate of genes found in pSLT of S. Typhimurium LT2, coupled with a mosaic of horizontally-acquired elements. Class I integron containing gene cassettes conferring resistance against clinically important antibiotics and compounds are present in pSTU288-1. A curious feature of the plasmid involves the deletion of two genes encoded in the Salmonella plasmid virulence operon (spvR and spvA) following the insertion of a tnpA IS26-like element coupled to a blaTEM gene. The spv operon is considered to be a major plasmid-encoded Salmonella virulence factor that is essential for the intracellular lifecycle. The loss of the positive regulator SpvR may impact on the pathogenesis of S. Typhimurium U288. A second 11,067 bp plasmid designated pSTU288-2 contains further antibiotic resistance determinants, as well as replication and mobilization genes. Finally, a small 4675 bp plasmid pSTU288-3 was identified containing mobilization genes and a pleD-like G-G-D/E-E-F conserved domain protein that modulate intracellular levels of cyclic di-GMP, and are associated with motile to sessile transitions in growth

Atrophy of the cholinergic basal forebrain can detect presynaptic cholinergic loss in Parkinson's Disease

Objectives: Structural imaging of the cholinergic basal forebrain may provide a biomarker for cholinergic system integrity that can be used in motor and non-motor outcome studies in Parkinson's disease. However, no prior studies have validated these structural metrics with cholinergic nerve terminal in vivo imaging in Parkinson's disease. Here, we correlate cholinergic basal forebrain morphometry with the topography of vesicular acetylcholine transporter in a large Parkinson's sample. Methods: [18F]-Fluoroethoxybenzovesamicol vesicular acetylcholine transporter positron emission tomography was carried out in 101 non-demented people with Parkinson's (76.24% male, mean age 67.6 ± 7.72 years, disease duration 5.7 ± 4.4 years). Subregional cholinergic basal forebrain volumes were measured using magnetic resonance imaging morphometry. Relationships were assessed via volume-of-interest based correlation analysis. Results: Subregional volumes of the cholinergic basal forebrain predicted cholinergic nerve terminal loss, with most robust correlations occurring between the posterior cholinergic basal forebrain and temporofrontal, insula, cingulum, and hippocampal regions, and with modest correlations in parieto-occipital regions. Hippocampal correlations were not limited to the cholinergic basal forebrain subregion Ch1-2. Correlations were also observed in the striatum, thalamus, and brainstem. Interpretation: Cholinergic basal forebrain morphometry is a robust predictor of regional cerebral vesicular acetylcholine transporter bindings, especially in the anterior brain. The relative lack of correlation between parieto-occipital binding and basal forebrain volumes may reflect the presence of more diffuse synaptopathy in the posterior cortex due to etiologies that extend well beyond the cholinergic system. ANN NEUROL 2023;93:991–998

Using coloured filters to reduce the symptoms of visual stress in children with reading delay

Background: Meares Irlen Syndrome (MIS), otherwise known as “visual stress”, is one condition that can cause difficulties with reading. Aim: This study aimed to compare the effect of two coloured-filter systems on the symptoms of visual stress in children with reading delay. Methods: The study design was a pre-test, post-test, randomized head-to-head comparison of two filter systems on the symptoms of visual stress in school children. A total of 68 UK mainstream schoolchildren with significant impairment in reading ability completed the study. Results: The filter systems appeared to have a large effect on the reported symptoms between pre and post three-month time points (d = 2.5, r = 0.78). Both filter types appeared to have large effects (Harris d = 1.79, r = 0.69 and DRT d = 3.22, r = 0.85). Importantly, 35% of participants’ reported that their symptoms had resolved completely; 72% of the 68 children appeared to gain improvements in three or more visual stress symptoms. Conclusion and significance: The reduction in symptoms, which appeared to be brought about by the use of coloured filters, eased the visual discomfort experienced by these children when reading. This type of intervention therefore has the potential to facilitate occupational engagement

A comparison of two-coloured filter systems for treating visual reading difficulties

Copyright @ 2013 Informa UK Ltd.Purpose: Visual disturbances that make it difficult to read text are often termed “visual stress”. Coloured filters in spectacles may help some children overcome reading problems that are often caused by visual stress. It has been suggested that for optimal effect each child requires an individually prescribed colour for each eye, as determined in systems such as the “Harris Foundation” coloured filters. Alternatively, it has been argued that only blue or yellow filters, as used in the “Dyslexia Research Trust” (DRT) filter system, are necessary to affect the underlying physiology. Method: A randomised, double blind trial with 73 delayed readers, was undertaken to compare changes in reading and spelling as well as irregular and non-word reading skills after 3 months of wearing either the Harris or the DRT filters. Results: Reading improved significantly after wearing either type of filter (t = −8.4, p < 0.01), with 40% of the children improving their reading age by 6 months or more during the 3 month trial. However, spelling ability (t = 2.1, p = 0.05) and non-word reading (f = 4.7, p < 0.05) improved significantly more with the DRT than with the Harris filters. Conclusion: Education and rehabilitation professionals should therefore, consider coloured filters as an effective intervention for delayed readers experiencing visual stress

Cholinergic basal forebrain structure influences the reconfiguration of white matter connections to support residual memory in mild cognitive impairment

The fornix and hippocampus are critical to recollection in the healthy human brain. Fornix degeneration is a feature of aging and Alzheimer's disease. In the presence of fornix damage in mild cognitive impairment ( MCI ), a recognized prodrome of Alzheimer's disease, recall shows greater dependence on other tracts, notably the parahippocampal cingulum ( PHC ). The current aims were to determine whether this shift is adaptive and to probe its relationship to cholinergic signaling, which is also compromised in Alzheimer's disease. Twenty-five human participants with MCI and 20 matched healthy volunteers underwent diffusion MRI, behavioral assessment, and volumetric measurement of the basal forebrain. In a regression model for recall, there was a significant group × fornix interaction, indicating that the association between recall and fornix structure was weaker in patients. The opposite trend was present for the left PHC. To further investigate this pattern, two regression models were generated to account for recall performance: one based on fornix microstructure and the other on both fornix and left PHC. The realignment to PHC was positively correlated with free recall but not non-memory measures, implying a reconfiguration that is beneficial to residual memory. There was a positive relationship between realignment to PHC and basal forebrain gray matter volume despite this region demonstrating atrophy at a group level, i.e., the cognitive realignment to left PHC was most apparent when cholinergic areas were relatively spared. Therefore, cholinergic systems appear to enable adaptation to injury even as they degenerate, which has implications for functional restoration

Experiences of nurses caring for respiratory patients during the first wave of the COVID-19 pandemic: an online survey study

Background: Nurses have been at the forefront of the pandemic response, involved in extensive coordination of services, screening, vaccination and front-line work in respiratory, emergency and intensive care environments. The nature of this work is often intense and stress-provoking with an inevitable psychological impact on nurses and all healthcare workers. This study focused on nurses working in respiratory areas with the aim of identifying and characterising the self-reported issues that exacerbated or alleviated their concerns during the first wave of the COVID-19 pandemic.Methods: An online survey was developed consisting of 90 questions using a mixture of open-ended and closed questions. Participant demographic data were also collected (age, gender, ethnicity, number of years qualified, details of long-term health conditions, geographical location, nursing background/role and home life). The online survey was disseminated via social media and professional respiratory societies (British Thoracic Society, Primary Care Respiratory Society, Association of Respiratory Nurse Specialists) over a 3-week period in May 2020 and the survey closed on 1 June 2020.Results: The study highlights the experiences of nurses caring for respiratory patients during the first wave of the pandemic in early 2020. Concerns were expressed over the working environment, the supply and availability of adequate protective personal equipment, the quality of care individuals were able to deliver, and the impact on mental health to nurses and their families. A high number provided free-text comments around their worries and concerns about the impact on their household; these included bringing the virus home, the effect on family members worrying about them, mental health and the impact of changing working patterns, and managing with children. Although both formal and informal support were available, there were inconsistencies in provision, highlighting the importance of nursing leadership and management in ensuring equity of access to services.Conclusions: Support for staff is essential both throughout the pandemic and afterwards, and it is important that preparation of individuals regarding building resilience is recognised. It is also clear that psychological support and services for nurses and the wider healthcare team need to be available and quickly convened in the event of similar major incidents, either global or local

Structural connectivity and brain network analyses in Parkinson's disease: A cross-sectional and longitudinal study.

IntroductionParkinson's disease (PD) is an idiopathic disease of the central nervous system characterized by both motor and non-motor symptoms. It is the second most common neurodegenerative disease. Magnetic resonance imaging (MRI) can reveal underlying brain changes associated with PD.ObjectiveIn this study, structural connectivity and white matter networks were analyzed by diffusion MRI and graph theory in a cohort of patients with PD and a cohort of healthy controls (HC) obtained from the Parkinson's Progression Markers Initiative (PPMI) database in a cross-sectional analysis. Furthermore, we investigated longitudinal changes in the PD cohort over 36 months.ResultCompared with the control group, participants with PD showed lower structural connectivity in several brain areas, including the corpus callosum, fornix, and uncinate fasciculus, which were also confirmed by a large effect-size. Additionally, altered connectivity between baseline and after 36 months was found in different network paths inside the white matter with a medium effect-size. Network analysis showed trends toward lower network density in PD compared with HC at baseline and after 36 months, though not significant after correction. Significant differences were observed in nodal degree and strength in several nodes.ConclusionIn conclusion, altered structural and network metrics in several brain regions, such as corpus callosum, fornix, and cingulum were found in PD, compared to HC. We also report altered connectivity in the PD group after 36 months, reflecting the impact of both PD pathology and aging processes. These results indicate that structural and network metrics might yield insight into network reorganization that occurs in PD

Factors influencing fatigue in nurses working in respiratory clinical areas during the second wave of the Covid?19 pandemic: An online survey

Aims and objectivesThis study explores UK nurses' experiences of working in a respiratory clinical area during the COVID-19 pandemic over winter 2020.BackgroundDuring the first wave of the pandemic, nurses working in respiratory clinical areas experienced significant levels of anxiety and depression. As the pandemic has progressed, levels of fatigue in nurses have not been assessed.MethodsA cross-sectional e-survey was distributed via professional respiratory societies and social media. The survey included Generalised Anxiety Disorder Assessment (GAD7), Patient Health Questionnaire (PHQ9, depression), a resilience scale (RS-14) and Chalder mental and physical fatigue tools. The STROBE checklist was followed as guidance to write the manuscript.ResultsDespite reporting anxiety and depression, few nurses reported having time off work with stress, most were maintaining training and felt prepared for COVID challenges in their current role. Nurses reported concerns over safety and patient feedback was both positive and negative. A quarter of respondents reported wanting to leave nursing. Nurses experiencing greater physical fatigue reported higher levels of anxiety and depression.ConclusionsNurses working in respiratory clinical areas were closely involved in caring for COVID-19 patients. Nurses continued to experience similar levels of anxiety and depression to those found in the first wave and reported symptoms of fatigue (physical and mental). A significant proportion of respondents reported considering leaving nursing. Retention of nurses is vital to ensure the safe functioning of already overstretched health services. Nurses would benefit from regular mental health check-ups to ensure they are fit to practice and receive the support they need to work effectively.Relevance to clinical practiceA high proportion of nurses working in respiratory clinical areas have been identified as experiencing fatigue in addition to continued levels of anxiety, depression over winter 2020. Interventions need to be implemented to help provide mental health support and improve workplace conditions to minimise PTSD and burnout