4,015 research outputs found

    Energy Dependent Tunneling in a Quantum Dot

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    We present measurements of the rates for an electron to tunnel on and off a quantum dot, obtained using a quantum point contact charge sensor. The tunnel rates show exponential dependence on drain-source bias and plunger gate voltages. The tunneling process is shown to be elastic, and a model describing tunneling in terms of the dot energy relative to the height of the tunnel barrier quantitatively describes the measurements.Comment: 4 pages, 4 figure

    Angiogenesis in Paget's Disease of the Vulva and the Breast: Correlation with Microvessel Density

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    Our understanding of the pathogenesis of Paget's disease of the vulva and the breast remains limited. Current evidence supports the fact that angiogenesis plays an important role in the pathogenesis of several diseases. Therefore, we sought to define its role, as correlated with microvessel density, in Paget's disease of the vulva and the breast. Microvessels were analysed using anti-von Willebrand factor antibody in 105 cases of Paget's disease of the vulva and the breast comprising 71 cases of Paget's disease of the vulva, including 8 cases with invasive disease, and 34 cases of Paget's disease of the breast. The latter included 12 cases with DCIS, 5 cases with both DCIS and invasive carcinoma, and 6 with carcinoma alone. Eleven cases had no underlying tumour identified. Increased microvessel density was demonstrated in Paget's disease of the breast with DCIS and with carcinoma alone compared to Paget's disease of the breast alone, P < 0.08 and P < 0.013, respectively. There were no significant differences in microvessel density in the vulval cases. Neovascularisation is an important process in the development of Paget's disease of the breast. Other biological and molecular processes are more involved in the pathogenesis of Paget's disease of the vulva

    Population genetics of trypanosoma brucei rhodesiense: clonality and diversity within and between foci

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    African trypanosomes are unusual among pathogenic protozoa in that they can undergo their complete morphological life cycle in the tsetse fly vector with mating as a non-obligatory part of this development. Trypanosoma brucei rhodesiense, which infects humans and livestock in East and Southern Africa, has classically been described as a host-range variant of the non-human infective Trypanosoma brucei that occurs as stable clonal lineages. We have examined T. b. rhodesiense populations from East (Uganda) and Southern (Malawi) Africa using a panel of microsatellite markers, incorporating both spatial and temporal analyses. Our data demonstrate that Ugandan T. b. rhodesiense existed as clonal populations, with a small number of highly related genotypes and substantial linkage disequilibrium between pairs of loci. However, these populations were not stable as the dominant genotypes changed and the genetic diversity also reduced over time. Thus these populations do not conform to one of the criteria for strict clonality, namely stability of predominant genotypes over time, and our results show that, in a period in the mid 1990s, the previously predominant genotypes were not detected but were replaced by a novel clonal population with limited genetic relationship to the original population present between 1970 and 1990. In contrast, the Malawi T. b. rhodesiense population demonstrated significantly greater diversity and evidence for frequent genetic exchange. Therefore, the population genetics of T. b. rhodesiense is more complex than previously described. This has important implications for the spread of the single copy T. b. rhodesiense gene that allows human infectivity, and therefore the epidemiology of the human disease, as well as suggesting that these parasites represent an important organism to study the influence of optional recombination upon population genetic dynamics

    Nunalleq, Stories from the Village of Our Ancestors:Co-designing a multivocal educational resource based on an archaeological excavation

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    This work was funded by the UK-based Arts and Humanities Research Council through grants (AH/K006029/1) and (AH/R014523/1), a University of Aberdeen IKEC Award with additional support for travel and subsistence from the University of Dundee, DJCAD Research Committee RS2 project funding. Thank you to the many people who contributed their support, knowledge, feedback, voices and faces throughout the project, this list includes members of the local community, colleagues, specialists, students, and volunteers. If we have missed out any names we apologize but know that your help was appreciated. Jimmy Anaver, John Anderson, Alice Bailey, Kieran Baxter, Pauline Beebe, Ellinor Berggren, Dawn Biddison, Joshua Branstetter, Brendan Body, Lise Bos, Michael Broderick, Sarah Brown, Crystal Carter, Joseph Carter, Lucy Carter, Sally Carter, Ben Charles, Mary Church, Willard Church, Daniele Clementi, Annie Cleveland, Emily Cleveland, Joshua Cleveland, Aron Crowell, Neil Curtis, Angie Demma, Annie Don, Julia Farley, Veronique Forbes, Patti Fredericks, Tricia Gillam, Sean Gleason, Sven Haakanson, Cheryl Heitman, Grace Hill, Diana Hunter, Joel Isaak, Warren Jones, Stephan Jones, Ana Jorge, Solveig Junglas, Melia Knecht, Rick Knecht, Erika Larsen, Paul Ledger, Jonathan Lim Soon, Amber Lincoln, Steve Luke, Francis Lukezic, Eva Malvich, Pauline Matthews, Roy Mark, Edouard Masson-MacLean, Julie Masson-MacLean, Mhairi Maxwell, Chuna Mcintyre, Drew Michael, Amanda Mina, Anna Mossolova, Carl Nicolai Jr, Chris Niskanen, Molly Odell, Tom Paxton, Lauren Phillips, Lucy Qin, Charlie Roberts, Chris Rowe, Rufus Rowe,Chris Rowland, John Rundall, Melissa Shaginoff, Monica Shah, Anna Sloan, Darryl Small Jr, John Smith, Mike Smith, Joey Sparaga, Hannah Strehlau, Dora Strunk, Larissa Strunk, Lonny Strunk, Larry Strunk, Robbie Strunk, Sandra Toloczko, Richard Vanderhoek, the Qanirtuuq Incorporated Board, the Quinhagak Dance Group and the staff at Kuinerrarmiut Elitnaurviat. We also extend our thanks to three anonymous reviewers for their valuable comments on our paper.Peer reviewedPublisher PD

    Patient ratings in exercise therapy for the management of tendinopathy: a systematic review with meta-analysis.

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    The objective of this study was to synthesise exercise therapy intervention data investigating patient rating outcomes for the management of tendinopathy. A systematic review and meta-analysis of randomised controlled trials investigating exercise therapy interventions and reporting patient rating outcomes were undertaken. Eligible settings were considered to be any setting in any country listed as very high on the human development index. Eligible participants were considered to be people with a diagnosis of any tendinopathy of any severity or duration. Exercise therapy for the management of tendinopathy was considered for inclusion based on alignment with five different therapy classes: 1) resistance; 2) plyometric; 3) vibration; 4) flexibility; and 5) movement pattern retraining modalities. The main outcomes sought were those that measured patient rating of condition, including patient satisfaction and Global Rating of Change (GROC). From a total of 124 exercise therapy studies, 34 (Achilles: 41%; rotator cuff: 32%; patellar: 15%; elbow: 9%; and gluteal: 3%) provided sufficient information to be meta-analysed. The data were obtained across 48 treatment arms and 1246 participants. The pooled estimate for proportion of satisfaction was 0.63 [95% CrI: 0.53 to 0.73], and the pooled estimate for percentage of maximum GROC was 53 [95% CrI: 38 to 69%]. The proportion of patients reporting positive satisfaction and perception of change increased with longer follow-up periods from treatment onset. Patient satisfaction and GROC appear similar and are ranked moderately high demonstrating that patients generally perceive exercise therapies positively. Further research including greater consistency in measurement tools is required to explore and where possible, identify patient- and exercise-related moderating factors that can be used to improve person-centred care

    Sequential addition of neuronal stem cell temporal cohorts generates a feed-forward circuit in the Drosophila larval nerve cord

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    How circuits self-assemble starting from neuronal stem cells is a fundamental question in developmental neurobiology. Here, we addressed how neurons from different stem cell lineages wire with each other to form a specific circuit motif. In Drosophila larvae, we combined developmental genetics (Twin spot MARCM, Multi-color Flip Out, permanent labeling) with circuit analysis (calcium imaging, connectomics, network science). For many lineages, neuronal progeny are organized into subunits called temporal cohorts. Temporal cohorts are subsets of neurons born within a tight time window that have shared circuit level function. We find sharp transitions in patterns of input connectivity at temporal cohort boundaries. In addition, we identify a feed-forward circuit that encodes the onset of vibration stimuli. This feed-forward circuit is assembled by preferential connectivity between temporal cohorts from different lineages. Connectivity does not follow the often-cited early-to-early, late-to-late model. Instead, the circuit is formed by sequential addition of temporal cohorts from different lineages, with circuit output neurons born before circuit input neurons. Further, we generate new tools for the fly community. Our data raise the possibility that sequential addition of neurons (with outputs oldest and inputs youngest) could be one fundamental strategy for assembling feed-forward circuits
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