621 research outputs found

    Limit linear series in positive characteristic and Frobenius-unstable vector bundles on curves

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2004.Includes bibliographical references (p. 243-248).(cont.) yield a new proof of a result of Mochizuki yield a new proof of a result of Mochizuki Frobenius-unstable bundles for C general, and hence obtaining a self-contained proof of the resulting formula for the degree of V₂.Using limit linear series and a result controlling degeneration from separable maps to inseparable maps, we give a formula for the number of self-maps of P¹ with ramification to order e[sub]i at general points P[sub]i the case that all e[sub]i are less than the characteristic. We also develop a new, more functorial construction for the basic theory of limit linear series, which works transparently in positive and mixed characteristics, yielding a result on lifting linear series from characteristic p to characteristic 0, and even showing promise for generalization to higher-dimensional varieties. Now, let C be a curve of genus 2 over a field k of positive characteristic, and V₂ the Verschiebung rational map induced by pullback under Frobenius on moduli spaces of semistable vector bundles of rank two and trivial determinant. We show that if the Frobenius-unstable vector bundles are deformation-free in a suitable sense, then they are precisely the undefined points of V₂, and may each be resolved by a single blow-up; in this setting, we are able to calculate the degree of V₂ in terms of the number of Frobenius-unstable bundles, and describe the image of the exceptional divisors. We finally examine the Frobenius-unstable bundles on C by studying connections with vanishing p-curvature on certain unstable bundles on C. Using explicit formulas for p-curvature, we completely describe the Frobenius-unstable bundles in characteristics 3, 5, 7. We classify logarithmic connections with vanishing p-curvature on vector bundles of rank 2 on P¹ in terms of self-maps of P¹ with prescribed ramification. Using our knowledge of such maps, we then glue the connections to a nodal curve and deform to a smooth curve toby Brian Osserman.Ph.D

    Living with multimorbidity? The lived experience of multiple chronic conditions in later life

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    Multimorbidity is defined biomedically as the co-existence of two or more long-term conditions in an individual. Globally, the number of people living with multiple conditions is increasing, posing stark challenges both to the clinical management of patients and the organisation of health systems. Qualitative literature has begun to address how concurrency affects the self-management of chronic conditions, and the concept of illness prioritisation predominates. In this article, we adopt a phenomenological lens to show how older people with multiple conditions experience illness. This UK study was qualitative and longitudinal in design. Sampling was purposive and drew upon an existing cohort study. In total, 15 older people living with multiple conditions took part in 27 in-depth interviews. The practical stages of analysis were guided by Constructivist Grounded Theory. We argue that the concept of multimorbidity as biomedically imagined has limited relevance to lived experience, while concurrency may also be erroneous. In response, we outline a lived experience of multiple chronic conditions in later life, which highlights differences between clinical and lay assumptions and makes the latter visible

    Synergies for Improving Oil Palm Production and Forest Conservation in Floodplain Landscapes

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    Lowland tropical forests are increasingly threatened with conversion to oil palm as global demand and high profit drives crop expansion throughout the world’s tropical regions. Yet, landscapes are not homogeneous and regional constraints dictate land suitability for this crop. We conducted a regional study to investigate spatial and economic components of forest conversion to oil palm within a tropical floodplain in the Lower Kinabatangan, Sabah, Malaysian Borneo. The Kinabatangan ecosystem harbours significant biodiversity with globally threatened species but has suffered forest loss and fragmentation. We mapped the oil palm and forested landscapes (using object-based-image analysis, classification and regression tree analysis and on-screen digitising of high-resolution imagery) and undertook economic modelling. Within the study region (520,269 ha), 250,617 ha is cultivated with oil palm with 77% having high Net-Present-Value (NPV) estimates (413/ha?yr413/ha?yr–637/ha?yr); but 20.5% is under-producing. In fact 6.3% (15,810 ha) of oil palm is commercially redundant (with negative NPV of 299/ha?yr-299/ha?yr--65/ha?yr) due to palm mortality from flood inundation. These areas would have been important riparian or flooded forest types. Moreover, 30,173 ha of unprotected forest remain and despite its value for connectivity and biodiversity 64% is allocated for future oil palm. However, we estimate that at minimum 54% of these forests are unsuitable for this crop due to inundation events. If conversion to oil palm occurs, we predict a further 16,207 ha will become commercially redundant. This means that over 32,000 ha of forest within the floodplain would have been converted for little or no financial gain yet with significant cost to the ecosystem. Our findings have globally relevant implications for similar floodplain landscapes undergoing forest transformation to agriculture such as oil palm. Understanding landscape level constraints to this crop, and transferring these into policy and practice, may provide conservation and economic opportunities within these seemingly high opportunity cost landscapes

    The Keele community knee pain forum: action research to engage with stakeholders about the prevention of knee pain and disability

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    <p>Abstract</p> <p>Background</p> <p>Involvement of users in health care research is central to UK health care policy, and guidelines for involvement exist. However, there are limited examples in rheumatology research. The aim of this study was to establish a community knee pain forum aimed at engaging stakeholders in design, dissemination and prioritisation of knee pain research.</p> <p>Methods</p> <p>Ten people were recruited to the forum representing a wide range of agencies. These included Weight Watchers, the leisure industry, Beth Johnson Foundation, health and social care professionals and the public. Three two-hour meetings over a two-year period were held. Experienced qualitative researchers facilitated each meeting. Written feedback after each meeting was elicited, and a short evaluation form was mailed to all members after the final meeting.</p> <p>Results</p> <p>Establishing and maintaining a forum of mixed members required careful preparation and ongoing support. Meetings had to be well-structured in order to allow for balanced participation of lay and professional users. Users contributed to the design of methods, provided ideas for dissemination and set priorities for further research. Clear documentation of meetings ensured that users' contributions to the research cycle were transparent.</p> <p>Conclusion</p> <p>Our knee pain forum illustrates that community engagement can have a positive impact on the development, dissemination and implementation of health research. Engaging with non-academic partners enables mutual learning and this enhances the quality of NHS research.</p

    Introducing a new breed of wine yeast: interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast and Saccharomyces mikatae

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    Interspecific hybrids are commonplace in agriculture and horticulture; bread wheat and grapefruit are but two examples. The benefits derived from interspecific hybridisation include the potential of generating advantageous transgressive phenotypes. This paper describes the generation of a new breed of wine yeast by interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast strain and Saccharomyces mikatae, a species hitherto not associated with industrial fermentation environs. While commercially available wine yeast strains provide consistent and reliable fermentations, wines produced using single inocula are thought to lack the sensory complexity and rounded palate structure obtained from spontaneous fermentations. In contrast, interspecific yeast hybrids have the potential to deliver increased complexity to wine sensory properties and alternative wine styles through the formation of novel, and wider ranging, yeast volatile fermentation metabolite profiles, whilst maintaining the robustness of the wine yeast parent. Screening of newly generated hybrids from a cross between a S. cerevisiae wine yeast and S. mikatae (closely-related but ecologically distant members of the Saccharomyces sensu stricto clade), has identified progeny with robust fermentation properties and winemaking potential. Chemical analysis showed that, relative to the S. cerevisiae wine yeast parent, hybrids produced wines with different concentrations of volatile metabolites that are known to contribute to wine flavour and aroma, including flavour compounds associated with non-Saccharomyces species. The new S. cerevisiae x S. mikatae hybrids have the potential to produce complex wines akin to products of spontaneous fermentation while giving winemakers the safeguard of an inoculated ferment.Jennifer R. Bellon, Frank Schmid, Dimitra L. Capone, Barbara L. Dunn, Paul J. Chamber

    Enrichment analysis of Alu elements with different spatial chromatin proximity in the human genome

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    Transposable elements (TEs) have no longer been totally considered as “junk DNA” for quite a time since the continual discoveries of their multifunctional roles in eukaryote genomes. As one of the most important and abundant TEs that still active in human genome, Alu, a SINE family, has demonstrated its indispensable regulatory functions at sequence level, but its spatial roles are still unclear. Technologies based on 3C(chromosomeconformation capture) have revealed the mysterious three-dimensional structure of chromatin, and make it possible to study the distal chromatin interaction in the genome. To find the role TE playing in distal regulation in human genome, we compiled the new released Hi-C data, TE annotation, histone marker annotations, and the genome-wide methylation data to operate correlation analysis, and found that the density of Alu elements showed a strong positive correlation with the level of chromatin interactions (hESC: r=0.9, P<2.2×1016; IMR90 fibroblasts: r = 0.94, P < 2.2 × 1016) and also have a significant positive correlation withsomeremote functional DNA elements like enhancers and promoters (Enhancer: hESC: r=0.997, P=2.3×10−4; IMR90: r=0.934, P=2×10−2; Promoter: hESC: r = 0.995, P = 3.8 × 10−4; IMR90: r = 0.996, P = 3.2 × 10−4). Further investigation involving GC content and methylation status showed the GC content of Alu covered sequences shared a similar pattern with that of the overall sequence, suggesting that Alu elements also function as the GC nucleotide and CpG site provider. In all, our results suggest that the Alu elements may act as an alternative parameter to evaluate the Hi-C data, which is confirmed by the correlation analysis of Alu elements and histone markers. Moreover, the GC-rich Alu sequence can bring high GC content and methylation flexibility to the regions with more distal chromatin contact, regulating the transcription of tissue-specific genes

    Watch and Learn: Seeing Is Better than Doing when Acquiring Consecutive Motor Tasks

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    During motor adaptation learning, consecutive physical practice of two different tasks compromises the retention of the first. However, there is evidence that observational practice, while still effectively aiding acquisition, will not lead to interference and hence prove to be a better practice method. Observers and Actors practised in a clockwise (Task A) followed by a counterclockwise (Task B) visually rotated environment, and retention was immediately assessed. An Observe-all and Act-all group were compared to two groups who both physically practised Task A, but then only observed (ObsB) or did not see or practice Task B (NoB). The two observer groups and the NoB control group better retained Task A than Actors, although importantly only the observer groups learnt Task B. RT data and explicit awareness of the rotation suggested that the observers had acquired their respective tasks in a more strategic manner than Actor and Control groups. We conclude that observational practice benefits learning of multiple tasks more than physical practice due to the lack of updating of implicit, internal models for aiming in the former

    Therapeutic issues in HIV/HCV-coinfected patients

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    The importance of treating hepatitis C virus (HCV)-associated morbidities in a growing population of patients coinfected with human immunodeficiency virus (HIV) has increased since the introduction of highly active antiretroviral therapy. As a result, investigative attention is turning to HCV-related liver disease and treatment-associated issues in coinfection. HIV/HCV-coinfected patients have higher HCV RNA loads and show more rapid progression of fibrosis than do monoinfected patients. Combination therapy with pegylated interferon plus ribavirin (RBV) is the standard of care for HCV in coinfected patients. Therapy slows fibrosis progression, but toxicity prevents identification of the most effective RBV dose. Coinfected patients have about a threefold greater risk of antiretroviral therapy-associated hepatotoxicity than patients with HIV only. Other challenges include anaemia, mitochondrial toxicity, drug–drug interactions and leucopenia. Thus, chronic hepatitis C should be treated in HIV/HCV-coinfected patients, but steps must be taken to prevent and treat potential toxicities. The first European Consensus Conference on the Treatment of Chronic Hepatitis B and C in HIV Co-infected Patients was held March 2005 in Paris to address these issues. This article reviews the peer-reviewed literature and expert opinion published from 1990 to 2005, and compares results with presentations and recommendations from the Consensus Conference to best present current issues in coinfection

    Mental turmoil, suicide risk, illness perception, and temperament, and their impact on quality of life in chronic daily headache

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    To evaluate the relationship among quality of life, temperament, illness perception, and mental turmoil in patients affected by chronic daily headache with concomitant medication overuse headache. Participants were 116 consecutive adult outpatients admitted to the Department of General Medicine of the Sant’Andrea Hospital in Rome, between January 2007 and December 2007 with a diagnosis of chronic daily headache (illness duration >5 years). Patients were administered the Temperament Evaluation of Memphis, Pisa, Paris and San Diego-autoquestionnaire version (TEMPS-A), the Beck Hopelessness Scale (BHS), the Hamilton Rating Scale for Depression (HAM-D), the Mini-International Neuropsychiatric Interview (MINI), the Revised Illness Perception Questionnaire (IPQ), the Suicide Score Scale (SSS), and the Quality of Life Index (QL-Index). Twenty-eight percent of the patients evidenced moderate to severe depression, and 35% evidenced severe hopelessness. Analyses also indicated that quality of life, temperament, illness perception, and psychological turmoil are associated. However, a hierarchical multivariate regression analysis with quality of life as dependent variable indicated that only a model with mental turmoil variables may fit data; further, only the MINI suicidal intent resulted associated with quality of life (standardized regression coefficient = −0.55; t = −3.06; P < 0.01). Suicide risk may play a central role in affecting the quality of life of patients with chronic headache. The investigation of the interplay of factors that precipitate suicide risk should include assessment of chronic headache and its effects on wellbeing
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