845 research outputs found

    Rice bundle sheath cell shape is regulated by the timing of light exposure during leaf development

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    Plant leaves contain multiple cell types which achieve distinct characteristics whilst still coordinating development within the leaf. The bundle sheath possesses larger individual cells and lower chloroplast content than the adjacent mesophyll, but how this morphology is achieved remains unknown. To identify regulatory mechanisms determining bundle sheath cell morphology we tested the effects of perturbing environmental (light) and endogenous signals (hormones) during leaf development of Oryza sativa (rice). Total chloroplast area in bundle sheath cells was found to increase with cell size as in the mesophyll but did not maintain a ‘set‐point’ relationship, with the longest bundle sheath cells demonstrating the lowest chloroplast content. Application of exogenous cytokinin and gibberellin significantly altered the relationship between cell size and chloroplast biosynthesis in the bundle sheath, increasing chloroplast content of the longest cells. Delayed exposure to light reduced the mean length of bundle sheath cells but increased corresponding leaf length, whereas premature light reduced final leaf length but did not affect bundle sheath cells. This suggests that the plant hormones cytokinin and gibberellin are regulators of the bundle sheath cell‐chloroplast relationship and that final bundle sheath length may potentially be affected by light‐mediated control of exit from the cell cycle

    Measurement of Radiation Damage to 130nm Hybrid Pixel Detector Readout Chips

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    We present the first measurements of the performance of the Medipix3 hybrid pixel readout chip after exposure to significant x-ray flux. Specifically the changes in performance of the mixed mode pixel architecture, the digital periphery, digital to analogue converters and the e-fuse technology were characterised. A high intensity, calibrated x- ray source was used to incrementally irradiate the separate regions of the detector whilst it was powered. This is the first total ionizing dose study of a large area pixel detector fabricated using the 130nm CMOS technology

    Effect of Crystallinity on Water Vapor Sorption, Diffusion, and Permeation of PLA-Based Nanocomposites

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    The effects of crystalline morphology and presence of nanoparticles such as cellulose nanofibers (CNFs), organically modified nanoclay (C30B), or a combination of both on water vapor sorption and diffusion in polylactide (PLA) were evaluated by a quartz spring microbalance (QSM). It was found that the large spherulite size induced by high-temperature processing leads to an increase in water sorption and a substantial reduction of diffusion with increasing crystallinity. Contrarily, small-sized spherulites, arising after low-temperature processing during solvent-casting, showed a different behavior with a slight decrease in both water vapor sorption and diffusion with increasing crystallinity. These observations suggest that solvent-casting at low temperatures should not be used to predict the properties a material will show after industrial-scale processing. From the analysis of the nanocomposite materials, it was concluded that nanoparticles affected the materialâ€Čs properties not only by themselves but also by modifying the crystalline morphology. Interestingly, this led to CNF showing similar performance to C30B, decreasing water diffusivity (21 vs 27%) on isothermally crystallized materials despite its less favorable geometry. Additionally, the incorporation of 1 wt % CNF and C30B decreased water vapor transmission rate (WVTR) by 24% under an amorphous state but by 44% in a crystallized state, which makes hybrid CNF/C30B composites a promising food packaging material

    The Gender Shift: Disassociating Gendered Behavior from a Predicted Model of Career Disadvantage Among Female Veterinarians

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    In 2000, Akerlof & Kranton published a social identity theory that aimed to link gender identity with the economic outcome of individuals working in gendered organizations. Their theory predicts that females working in a gender labelled ‘male’ occupation should incur economic penalties for exhibiting behaviors that are typically gender stereotyped as ‘female’, and should therefore feel ambiguity towards work in a ‘male’ occupation if they follow traditional gender stereotypes. Although they acknowledge that movement of women into a previously male-dominated workforce will have an influence on their predictions, Akerlof & Kranton (2000) do not discuss in any detail how they expect their predicted outcomes to change. The United Kingdom veterinary industry is currently experiencing an unprecedented gender shift towards a female-dominated workforce, with women outnumbering their male counterparts since 2011 (RCVS, 2014). Historically a gender labelled ‘male’ occupation, veterinary medicine is now an example of a profession that has an occupational gender label that does not match the dominant gender of the workforce. This study uses Akerlof & Kranton’s (2000) social identity theory as a framework of analysis for understanding how female veterinarians are experiencing and understanding gender as a potential barrier to their career progression, and the impact that the gender shift towards a female-dominated workforce is having on those working within it. The findings of the study suggest that the dominance of females in the veterinary profession has a larger influence on predicted economic outcomes for female veterinarians than the Akerlof & Kranton (2000) theory predicts. The respondents of this study expressed feeling no disadvantage as a result of gendered behaviors, and instead perceived that career disadvantage for female veterinarians stemmed from the gendered features of the organizations in which they worked

    Acetyl Distribution in Acetylated Whole Wood and Reactivity of Isolated Wood Cell-Wall Components to Acetic Anhydride

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    Lignin, holocellulose, cellulose, and hemicelluloses were isolated from pine wood and reacted with acetic anhydride. The order of reactivity was found to be lignin < hemicellulose

    Professionals’ views on the use of smartphone technology to support children and adolescents with memory impairment due to acquired brain injury

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    Purpose: To identify from a health-care professionals’ perspective whether smartphones are used by children and adolescents with acquired brain injury as memory aids; what factors predict smartphone use and what barriers prevent the use of smartphones as memory aids by children and adolescents. Method: A cross-sectional online survey was undertaken with 88 health-care professionals working with children and adolescents with brain injury. Results: Children and adolescents with brain injury were reported to use smartphones as memory aids by 75% of professionals. However, only 42% of professionals helped their clients to use smartphones. The only factor that significantly predicted reported smartphone use was the professionals’ positive attitudes toward assistive technology. Several barriers to using smartphones as memory aids were identified, including the poor accessibility of devices and cost of devices. Conclusion: Many children and adolescents with brain injury are already using smartphones as memory aids but this is often not facilitated by professionals. Improving the attitudes of professionals toward using smartphones as assistive technology could help to increase smartphone use in rehabilitation

    Characterisation of Medipix3 Silicon Detectors in a Charged-Particle Beam

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    While designed primarily for X-ray imaging applications, the Medipix3 ASIC can also be used for charged-particle tracking. In this work, results from a beam test at the CERN SPS with irradiated and non-irradiated sensors are presented and shown to be in agreement with simulation, demonstrating the suitability of the Medipix3 ASIC as a tool for characterising pixel sensors.Comment: 16 pages, 13 figure

    Adolescent Experiences of the COVID-19 Pandemic and School Closures and Implications for Mental Health, Peer Relationships and Learning: A Qualitative Study in South-West England

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    The COVID-19 ‘lockdown’ and multiple school closures disrupted the daily lives and routines of the entire UK population. However, adolescents were likely particularly impacted by such measures due to this time being key for social and educational development. This qualitative study explored young people’s experiences of lockdowns and school closures. Fifteen secondary schools within south-west England were initially contacted and three schools participated in recruitment efforts. From December 2020 to March 2021, 25 students aged 14–15 participated in a combination of individual interviews (n = 5) and focus groups (n = 3). Findings revealed diverse experiences of the pandemic and highlighted the complexity of experiences according to individual student contexts. Three main themes were identified: (1) Learning environments; (2) Connection to peers; (3) Transition, adaptation and coping. These findings highlight the value young people place on face-to-face social contact with close friends, and the sense of structure provided by school, with implications for future home-based learning. Further in-depth qualitative research is needed to continue to understand the varied experiences during the course of the pandemic, particularly longer-term impacts on mental health and learning

    Impact of School and Peer Connectedness on Adolescent Mental Health and Well-Being Outcomes during the COVID-19 Pandemic:A Longitudinal Panel Survey

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    School closures and social distancing measures during the pandemic have disrupted young people’s daily routines and social relationships. We explored patterns of change in adolescent mental health and tested the relationship between pre-pandemic levels of school and peer connectedness and changes in mental health and well-being between the first lockdown and the return to school. This is a secondary analysis of a longitudinal 3-wave panel survey. The study sample included 603 students (aged 13–14) in 17 secondary schools across south-west England. Students completed a survey pre-pandemic (October 2019), during lockdown (May 2020) and shortly after returning to school (October 2020). Multilevel models, with random effects, were conducted for anxiety, depression and well-being outcomes with school and peer connectedness as predictor variables. Symptoms of anxiety decreased from pre-pandemic to during the first UK lockdown and increased on the return to school; anxious symptoms decreased the most for students reporting feeling least connected to school pre-pandemic. Students reporting low levels of school and peer connectedness pre-pandemic experienced poorer mental health and well-being at all time points. Low school connectedness pre-pandemic was associated with a greater increase in anxious and depressive symptoms between lockdown and the return to school when compared to students with medium levels of school connectedness. No associations were found with high school connectedness or with low/high peer connectedness. For adolescents with poor school connectedness, the enforced time away from school that the pandemic caused led to reduced anxiety. Going forwards, we need to consider ways in which to promote connection with school as a way of supporting mental health and well-being
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