412 research outputs found

    Non-degenerate normal-mode doublets in vibrating flat circular plates

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    The vibrations of flat circular plates have been studied for hundreds of years, and they are well understood by the scientific community. Unfortunately, when vibrating circular plates are discussed in textbooks, the relationship between pairs of spatially orthogonal vibrational patterns that occur at each of the normal-mode frequencies is often ignored. Usually these orthogonal solutions are presented to the student as being degenerate in frequency; however, in practice the degeneracy of the doublet is often broken and the two spatially orthogonal solutions are separated in frequency. We show theoretically and experimentally that the degeneracy can be broken by a small asymmetry in the plate, and we derive a formula for predicting the magnitude of the frequency-splitting. We have used electronic speckle pattern interferometry to investigate the phenomena of doublet splitting and have confirmed the validity of the theory

    Carbon Stock Assessment in Silvopastoral Systems along an Elevational Gradient: A Study from Cattle Producers in the Sumaco Biosphere Reserve, Ecuadorian Amazon

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    Silvopastoral system (SPS) has been considered as a sustainable management system contribute to greenhouse gas (GHG) reduction, among other benefits compared with open pasture. However, little research has been conducted on the soil and tree biomass carbon stored in traditional pasture with dispersed trees (PWT) compared with pasture in monoculture (PM). The present study was conducted in the Ecuadorian Amazon Region (EAR), along an elevational gradient from 400 to 2000 masl., within the buffer and transition zone of the Sumaco Biosphere Reserve (SBR), using 71 temporary circular plots of 2826 m2, where 26 plots were stablished in PWT and 45 plots in PM. The main results in PWT show significant differences (p ≤ 0.01) between aboveground carbon biomass (AGCtrees) from 41.1 (lowlands), 26.5 (Middle hills) and 16.7 (high mountains) Mg ha−1 respectively, with an average of 31.0 Mg ha−1 in the whole study area. The total carbon pool along the altitudinal gradient in five components: (AGCtrees), belowground carbon (BGCtrees), pasture carbon (AGClitter+pasture) and carbon in soil components (0–10 and 10–30 cm) for PWT ranged from 112.80 (lowlands) to 91.34 (high mountains) Mg ha−1; while for the PM systems assessing three components (AGClitter+pasture) and carbon in soil components (0–10 and 10–30 cm) ranged from 52.5 (lowlands) to 77.8 (middle zone) Mg ha−1. Finally, the paper shows the main dominant tree species in pasture systems that contribute to carbon storage along elevational gradient and concludes with recommendations for decision-making aimed at improving cattle ranching systems through a silvopastoral approach to mitigate the effects of climate change

    AP-4 vesicles contribute to spatial control of autophagy via RUSC-dependent peripheral delivery of ATG9A.

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    Adaptor protein 4 (AP-4) is an ancient membrane trafficking complex, whose function has largely remained elusive. In humans, AP-4 deficiency causes a severe neurological disorder of unknown aetiology. We apply unbiased proteomic methods, including 'Dynamic Organellar Maps', to find proteins whose subcellular localisation depends on AP-4. We identify three transmembrane cargo proteins, ATG9A, SERINC1 and SERINC3, and two AP-4 accessory proteins, RUSC1 and RUSC2. We demonstrate that AP-4 deficiency causes missorting of ATG9A in diverse cell types, including patient-derived cells, as well as dysregulation of autophagy. RUSC2 facilitates the transport of AP-4-derived, ATG9A-positive vesicles from the trans-Golgi network to the cell periphery. These vesicles cluster in close association with autophagosomes, suggesting they are the "ATG9A reservoir" required for autophagosome biogenesis. Our study uncovers ATG9A trafficking as a ubiquitous function of the AP-4 pathway. Furthermore, it provides a potential molecular pathomechanism of AP-4 deficiency, through dysregulated spatial control of autophagy

    Femtosecond x-ray diffraction from an aerosolized beam of protein nanocrystals

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    We demonstrate near-atomic-resolution Bragg diffraction from aerosolized single granulovirus crystals using an x-ray free-electron laser. The form of the aerosol injector is nearly identical to conventional liquid-microjet nozzles, but the x-ray-scattering background is reduced by several orders of magnitude by the use of helium carrier gas rather than liquid. This approach provides a route to study the weak diffuse or lattice-transform signal arising from small crystals. The high speed of the particles is particularly well suited to upcoming MHz-repetition-rate x-ray free-electron lasers

    Mechanisms of micro-terror? Early career CMS academics’ experiences of ‘targets and terror’ in contemporary business schools

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    In this article, we apply the concept of ‘targets and terror’, previously used in the healthcare sector, to the audit culture within business schools. We explore to what extent terror, or the inculcation of fear through processes of domination, is identifiable in the micro-level experiences of early career academics. Drawing on an international study of 38 Critical Management Studies early career academics from 15 countries, we develop a theoretical framework combining Bourdieu’s modes of domination and Meyerson and Scully’s Tempered Radicalism, which helps us identify top-down and horizontal processes of micro-terror and bottom-up processes of micro-terrorism, specifically self-terrorisation and counter-terrorisation. In extending the study of ‘targets and terror’ cultures to contemporary business schools, we develop a clearer understanding of how domination plays out in the everyday processes of management and self-management. From Bourdieu’s modes of domination, we discern a dark picture of institutional and interpersonal overt and symbolic violence in the name of target achievement. The Tempered Radicalism lens helps us to understand early career academic challenges that can lead to self-terrorisation but also brings possible ways forward, showing early career academics how to resist mechanisms of micro-terror through their own small acts of counter-terrorisation, providing some hope specifically as the basis for collective resistance

    "Surviving discrimination by pulling together" : LGBTQI cancer patient and carer experiences of minority stress and social support

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    Background: Lesbian, gay, bisexual, transgender, queer and/or intersex (LGBTQI) people with cancer and their carers report poorer psychological outcomes than the general non-LGBTQI cancer population. There is growing acknowledgement that these health inequities can be explained by minority stress, which can be buffered by social support. Study Aim: To examine subjective experiences of minority stress and social support for LGBTQI people with cancer and their carers, drawing on qualitative findings from the Out with Cancer study. Method: An online survey including open ended items was completed by 430 LGBTQI cancer patients and 132 partners and other carers, representing a range of tumor types, sexual and gender identities, age and intersex status. A sub-sample of 104 patients and 31 carers completed an interview, with a follow-up photovoice activity and second interview completed by 45 patients and 10 carers. Data was thematically analysed using an intersectional theoretical framework. Results: Historical and present-day experiences of discrimination, violence, family rejection and exclusion created a legacy of distress and fear. This impacted on trust of healthcare professionals and contributed to distress and unmet needs in cancer survivorship and care. Social support, often provided by partners and other chosen family, including intimate partners and other LGBTQI people, buffered the negative impacts of minority stress, helping LGBTQI patients deal with cancer. However, some participants lacked support due to not having a partner, rejection from family of origin and lack of support within LGBTQI communities, increasing vulnerability to poor psychological wellbeing. Despite the chronic, cumulative impacts of minority stress, LGBTQI patients and carers were not passive recipients of discriminatory and exclusion in cancer care, demonstrating agency and resistance through collective action and advocacy. Conclusion: LGBTQI people have unique socio-political histories and present-day psycho-social experiences that contribute to distress during cancer. Social support serves to buffer and ameliorate this distress. There is a need for cancer healthcare professionals and support services to be aware of and responsive to these potential vulnerabilities, including the intersectional differences in experiences of minority stress and social support. There is also a need for recognition and facilitation of social support among LGBTQI people with cancer and their carers
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