926 research outputs found

    On totally geodesic submanifolds in the Jacobian locus

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    We study submanifolds of A_g that are totally geodesic for the locally symmetric metric and which are contained in the closure of the Jacobian locus but not in its boundary. In the first section we recall a formula for the second fundamental form of the period map due to Pirola, Tortora and the first author. We show that this result can be stated quite neatly using a line bundle over the product of the curve with itself. We give an upper bound for the dimension of a germ of a totally geodesic submanifold passing through [C] in M_g in terms of the gonality of C. This yields an upper bound for the dimension of a germ of a totally geodesic submanifold contained in the Jacobian locus, which only depends on the genus. We also study the submanifolds of A_g obtained from cyclic covers of the projective line. These have been studied by various authors. Moonen determined which of them are Shimura varieties using deep results in positive characteristic. Using our methods we show that many of the submanifolds which are not Shimura varieties are not even totally geodesic.Comment: To appear on International Journal of Mathematic

    On some differential-geometric aspects of the Torelli map

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    In this note we survey recent results on the extrinsic geometry of the Jacobian locus inside Ag\mathsf{A}_g. We describe the second fundamental form of the Torelli map as a multiplication map, recall the relation between totally geodesic subvarieties and Hodge loci and survey various results related to totally geodesic subvarieties and the Jacobian locus.Comment: To appear on Boll. UMI, special volume in memory of Paolo de Bartolomei

    Bone Absorptiometry in Metabolic Bone Disease: Baseline Values and Long-Term Treatment with Calcitriol (Post-Menopausal Osteoporosis Versus Osteomalacia)

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    Total body bone absorptiometry reveals low mineral density in both postmenopausal osteoporosis and osteomalacia patients. The method was used to investigate the effect of calcitriol administration on patients suffering from one of these conditions. In osteomalacia, the administration of calcitriol resulted in a dramatic improvement in bone mineral density (sometimes up to 50% in 12 months), indicating the rapid mineralization of previously uncalcified bone tissue as a result of the normalization of the Ca x P product. In osteoporosis a similar treatment was seen to halt the progressive decrease in bone mineral levels and sometimes resulted in minor increases in density (up to 5%). This is likely to be due to a normalization of intestinal calcium malabsorption which halts secondary homeostatic bone resorption

    Clinical Examination, Ultrasound and MRI Imaging of The Painful Elbow in Psoriatic Arthritis and Rheumatoid Arthritis: Which is Better, Ultrasound or MR, for Imaging Enthesitis?

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    Introduction: The purpose of the current study was to examine the painful elbow, and in particular enthesitis, in psoriatic arthritis (PsA) and rheumatoid arthritis (RA) using clinical examination, ultrasonography (US) and magnetic resonance imaging (MRI). Methods: Patients with elbow pain (11 with PsA and 9 with RA) were recruited. Clinical examination, US and MRI studies were performed on the same day. For enthesitis, the common extensor and flexor insertions and the triceps insertion were imaged (20 patients, giving a total of 60 sites with comparative data). Imaging was performed with the radiologists blinded to the diagnosis and clinical findings. US was used to assess ‘inflammatory activity’ (Power Doppler signal, oedema, tendon thickening and bursal swelling) and ‘damage’ (erosions, cortical roughening and enthesophytes). MRI was used to assess ‘inflammation’ (fluid in paratenon, peri-entheseal soft-tissue oedema, entheseal enhancement with gadolinium, entheseal oedema and bone oedema) and ‘damage’ (erosion, cortical roughening and enthesophyte). Results: Complete scan data were not available for all patients as one patient could not tolerate the MRI examination. No significant differences in imaging scores were found between PsA and RA. Analysis of damage scores revealed complete agreement between US and MRI data in 43/55 (78%) comparisons; in 10/55 (18%) cases the US data were abnormal but the MRI data normal; in 2/55 (4%) cases, the MRI data were abnormal and the US data normal. Analysis of the inflammation scores revealed complete agreement between US and MRI data in 33/55 (60%) comparisons; in 3/55 (5%) cases US data were abnormal but MRI data normal; in 19/55 (35%) cases the MRI data were abnormal and the US data normal. There was a poor relationship between assessments based on clinical examination and imaging studies. Readers could not accurately identify the disease from imaging findings. Conclusion: Based on our results, at the elbow, US and MR have different roles in assessing enthesitis, with US apparently the better diagnostic tool for assessing damage and MR the better tool for assessing inflammation. In this study enthesitis and synovitis in the painful elbow were found equally in cases of established RA and PsA

    The politics of urban management and planning in African cities

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    Half of Africa’s population is expected to live in a city by 2035, up from 40 per cent today. This is a testament to the fact that a quarter of the world’s fastest-growing cities are in Africa and 52 African cities already have more than 1 million inhabitants each. But these cities are only projected to absorb a quarter of the growth in urban populations, meaning that small and medium cities will host the majority of new urban dwellers (UN-Habitat, 2014: 23–25). African cities are the most unequal in the world, posing a major challenge to their future (UN-Habitat, 2010: 2)

    Partnering with higher education institutions for social and environmental justice in the global South: lessons from the Sierra Leone Urban Research Centre

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    In the context of the £1.5 billion aid money that the UK government is now channelling through UK research institutions, this article explores the importance of building local institutions and capacity in order to establish equitable research partnerships that respond to local concerns. It will also explore the role of these institutions in brokering local partnerships for urban justice

    A Fixed Combination of Palmitoylethanolamide and Melatonin (PEATONIDE) for the Management of Pain, Sleep, and Disability in Patients with Fibromyalgia: a Pilot Study

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    Fibromyalgia is characterized by chronic widespread pain, fatigue, and sleep disturbances. Recent theories attribute fibromyalgia to central sensitization syndromes, suggesting altered nociceptive processing leads to hyperalgesia and allodynia. Standardized effective treatments are currently lacking. Palmitoylethanolamide and melatonin have shown pain-relieving effects in chronic pain conditions, including fibromyalgia, with excellent safety. Our open-label study assessed the impact of a daily combination of 1200 mg of palmitoylethanolamide and 0.2 mg of melatonin on pain, sleep, and quality of life in fibromyalgia patients. Between June 2023 and March 2024, 50 patients (2016 ACR criteria) were treated and evaluated at baseline, 1 month, 3 months, and 4 months (1 month discontinuation). The assessments included VAS for pain, ISI for insomnia, HAQ for health assessments, and a tender points evaluation. The patients, averaging 54.12 years old with a 3:1 female-to-male ratio, showed significant improvements in VAS, ISI, and HAQ scores relative to their own baselines and a reduction in tender points at 1 and 3 months, which was maintained at 4 months. No adverse events were reported. This study is the first to demonstrate the efficacy of a palmitoylethanolamide and melatonin combination as an adjunct therapy in fibromyalgia, highlighting its potential to reduce pain and improve sleep and quality of life
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