458 research outputs found

    Missing Transverse-Doppler Effect in Time-Dilation Experiments with High-Speed Ions

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    Recent experiments with high-speed ions have investigated potential deviations from the time-dilation predicted by special relativity (SR). The main contribution of this article is to show that the SR predictions are matched by the experimental results only when the transverse Doppler effect in the observed emissions from the ions are neglected in the analysis. However, the Doppler effect in the emission cannot be neglected because it is similar to the time dilation effect. Thus, the article highlights the need to consider Doppler emission effects when validating SR time dilation using high-speed ion experiments.Comment: 3 pages, 3 figure

    How and Why is An Answer (Still) Correct? Maintaining Provenance in Dynamic Knowledge Graphs

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    Knowledge graphs (KGs) have increasingly become the backbone of many critical knowledge-centric applications. Most large-scale KGs used in practice are automatically constructed based on an ensemble of extraction techniques applied over diverse data sources. Therefore, it is important to establish the provenance of results for a query to determine how these were computed. Provenance is shown to be useful for assigning confidence scores to the results, for debugging the KG generation itself, and for providing answer explanations. In many such applications, certain queries are registered as standing queries since their answers are needed often. However, KGs keep continuously changing due to reasons such as changes in the source data, improvements to the extraction techniques, refinement/enrichment of information, and so on. This brings us to the issue of efficiently maintaining the provenance polynomials of complex graph pattern queries for dynamic and large KGs instead of having to recompute them from scratch each time the KG is updated. Addressing these issues, we present HUKA which uses provenance polynomials for tracking the derivation of query results over knowledge graphs by encoding the edges involved in generating the answer. More importantly, HUKA also maintains these provenance polynomials in the face of updates---insertions as well as deletions of facts---to the underlying KG. Experimental results over large real-world KGs such as YAGO and DBpedia with various benchmark SPARQL query workloads reveals that HUKA can be almost 50 times faster than existing systems for provenance computation on dynamic KGs

    Insights into surface chemistry down to nanoscale: an accessible colour hyperspectral imaging approach for scanning electron microscopy

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    Chemical imaging (CI) is the spatial identification of molecular chemical composition and is critical to characterising the (in-) homogeneity of functional material surfaces. Nanoscale CI on bulk functional material surfaces is a longstanding challenge in materials science and is addressed here. We demonstrate the feasibility of surface sensitive CI in the scanning electron microscope (SEM) using colour enriched secondary electron hyperspectral imaging (CSEHI). CSEHI is a new concept in the SEM, where secondary electron emissions in up to three energy ranges are assigned to RGB (red, green, blue) image colour channels. The energy ranges are applied to a hyperspectral image volume which is collected in as little as 50 s. The energy ranges can be defined manually or automatically. Manual application requires additional information from the user as first explained and demonstrated for a lithium metal anode (LMA) material, followed by manual CSEHI for a range of materials from art history to zoology. We introduce automated CSEHI, eliminating the need for additional user information, by finding energy ranges using a non-negative matrix factorization (NNMF) based method. Automated CSEHI is evaluated threefold: (1) benchmarking to manual CSEHI on LMA; (2) tracking controlled changes to LMA surfaces; (3) comparing automated CSEHI and manual CI results published in the past to reveal nanostructures in peacock feather and spider silk. Based on the evaluation, CSEHI is well placed to differentiate/track several lithium compounds formed through a solution reaction mechanism on a LMA surface (eg. lithium carbonate, lithium hydroxide and lithium nitride). CSEHI was used to provide insights into the surface chemical distribution on the surface of samples from art history (mineral phases) to zoology (di-sulphide bridge localisation) that are hidden from existing surface analysis techniques. Hence, the CSEHI approach has the potential to impact the way materials are analysed for scientific and industrial purposes

    The effect of two speech and language approaches on speech problems in people with Parkinson’s disease: the PD COMM RCT

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    Background Speech impairments are common with Parkinson’s disease (reported prevalence 68%), increasing conversational demands, reliance on family and social withdrawal. Objective(s) The PD COMM trial compared the clinical and cost-effectiveness of two speech and language therapy approaches: Lee Silverman Voice Treatment LOUD and National Health Service speech and language therapy for the treatment of speech or voice problems in people with Parkinson’s disease to no speech and language therapy (control) and against each other. Design PD COMM is a phase III, multicentre, three-arm, unblinded, randomised controlled trial. Participants were randomised in a 1 : 1 : 1 ratio to control, National Health Service speech and language therapy or Lee Silverman Voice Treatment LOUD via a central computer-generated programme, using a minimisation procedure with a random element, to ensure allocation concealment. Mixed-methods process and health economic evaluations were conducted. Setting United Kingdom outpatient and home settings. Participants People with idiopathic Parkinson’s disease, with self-reported or carer-reported speech or voice problems. We excluded people with dementia, laryngeal pathology and those within 24 months of previous speech and language therapy. Interventions The Lee Silverman Voice Treatment LOUD intervention included maximum effort drills and high-effort speech production tasks delivered over four 50-minute therapist-led personalised sessions per week, for 4 weeks with prescribed daily home practice. National Health Service speech and language therapy content and dosage reflected local non-Lee Silverman Voice Treatment speech and language therapy practices, usually 1 hour, once weekly, for 6 weeks. Trained, experienced speech and language therapists or assistants provided interventions. The control was no speech and language therapy until the trial was completed. Main outcome measures Primary outcome: Voice Handicap Index total score at 3 months. Secondary outcomes: Voice Handicap Index subscales, Parkinson’s Disease Questionnaire-39; Questionnaire on Acquired Speech Disorders; EuroQol-5D-5L; ICEpop Capabilities Measure for Older Adults; Parkinson’s Disease Questionnaire – Carers; resource utilisation; and adverse events. Assessments were completed pre-randomisation and at 3, 6 and 12 months post randomisation. Results Three hundred and eighty-eight participants were randomised to Lee Silverman Voice Treatment LOUD (n = 130), National Health Service speech and language therapy (n = 129) and control (n = 129). The impact of voice problems at 3 months after randomisation was lower for Lee Silverman Voice Treatment LOUD participants than control [−8.0 (99% confidence interval: −13.3, −2.6); p = 0.001]. There was no evidence of improvement for those with access to National Health Service speech and language therapy when compared to control [1.7 (99% confidence interval: −3.8, 7.1); p = 0.4]. Participants randomised to Lee Silverman Voice Treatment LOUD reported a lower impact of their voice problems than participants randomised to National Health Service speech and language therapy [99% confidence interval: −9.6 (−14.9, −4.4); p < 0.0001]. There were no reports of serious adverse events. Staff were confident with the trial interventions; a range of patient and therapist enablers of implementing Lee Silverman Voice Treatment LOUD were identified. The economic evaluation results suggested Lee Silverman Voice Treatment LOUD was more expensive and more effective than control or National Health Service speech and language therapy but was not cost-effective with incremental cost-effectiveness ratios of £197,772 per quality-adjusted life-year gained and £77,017 per quality-adjusted life-year gained, respectively. Limitations The number of participants recruited to the trial did not meet the pre-specified power. Conclusions People that had access to Lee Silverman Voice Treatment LOUD described a significantly greater reduction in the impact of their Parkinson’s disease-related speech problems 3 months after randomisation compared to people that had no speech and language therapy. There was no evidence of a difference between National Health Service speech and language therapy and those that received no speech and language therapy. Lee Silverman Voice Treatment LOUD resulted in a significantly lower impact of voice problems compared to National Health Service speech and language therapy 3 months after randomisation which was still present after 12 months; however, Lee Silverman Voice Treatment LOUD was not found to be cost-effective. Future work Implementing Lee Silverman Voice Treatment LOUD in the National Health Service and identifying alternatives to Lee Silverman Voice Treatment LOUD for those who cannot tolerate it. Investigation of less costly alternative options for Lee Silverman Voice Treatment delivery require investigation, with economic evaluation using a preference-based outcome measure that captures improvement in communication

    Vamsa: Automated Provenance Tracking in Data Science Scripts

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    There has recently been a lot of ongoing research in the areas of fairness, bias and explainability of machine learning (ML) models due to the self-evident or regulatory requirements of various ML applications. We make the following observation: All of these approaches require a robust understanding of the relationship between ML models and the data used to train them. In this work, we introduce the ML provenance tracking problem: the fundamental idea is to automatically track which columns in a dataset have been used to derive the features/labels of an ML model. We discuss the challenges in capturing such information in the context of Python, the most common language used by data scientists. We then present Vamsa, a modular system that extracts provenance from Python scripts without requiring any changes to the users' code. Using 26K real data science scripts, we verify the effectiveness of Vamsa in terms of coverage, and performance. We also evaluate Vamsa's accuracy on a smaller subset of manually labeled data. Our analysis shows that Vamsa's precision and recall range from 90.4% to 99.1% and its latency is in the order of milliseconds for average size scripts. Drawing from our experience in deploying ML models in production, we also present an example in which Vamsa helps automatically identify models that are affected by data corruption issues

    Oscillatory biquadratic coupling in Fe/Cr/Fe(001)

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    Copyright © 1997 The American Physical SocietyPolar Kerr measurements have been used to measure the dependence of the biquadratic coupling strength B12 on Cr thickness in an Fe/Cr/Fe trilayer. The overall behavior, which consists of a maximum coupling strength at dCr=5 Å (3.5 ML) with a falloff at greater Cr thicknesses, is found to be consistent with in-plane Kerr and Brillouin light-scattering measurements performed on the same sample. The polar Kerr measurements suggest additionally that B12 increases from zero near zero Cr thickness, and that it oscillates in magnitude after the first peak, with a second peak in B12 occurring at about dCr=12 Å (8.3 ML). The positions and heights of the first and second biquadratic coupling maxima, in relation to the first bilinear coupling maximum, show excellent agreement with previous measurements by Köbler et al. of the biquadratic coupling behavior in Fe/Cr/Fe, and also show good agreement with the predictions of an intrinsic biquadratic coupling mechanism due to Edwards et al

    Evaluating the GeoSnap 13-μ\mum Cut-Off HgCdTe Detector for mid-IR ground-based astronomy

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    New mid-infrared HgCdTe (MCT) detector arrays developed in collaboration with Teledyne Imaging Sensors (TIS) have paved the way for improved 10-μ\mum sensors for space- and ground-based observatories. Building on the successful development of longwave HAWAII-2RGs for space missions such as NEO Surveyor, we characterize the first 13-μ\mum GeoSnap detector manufactured to overcome the challenges of high background rates inherent in ground-based mid-IR astronomy. This test device merges the longwave HgCdTe photosensitive material with Teledyne's 2048x2048 GeoSnap-18 (18-μ\mum pixel) focal plane module, which is equipped with a capacitive transimpedance amplifier (CTIA) readout circuit paired with an onboard 14-bit analog-to-digital converter (ADC). The final assembly yields a mid-IR detector with high QE, fast readout (>85 Hz), large well depth (>1.2 million electrons), and linear readout. Longwave GeoSnap arrays would ideally be deployed on existing ground-based telescopes as well as the next generation of extremely large telescopes. While employing advanced adaptive optics (AO) along with state-of-the-art diffraction suppression techniques, instruments utilizing these detectors could attain background- and diffraction-limited imaging at inner working angles <10 λ/D\lambda/D, providing improved contrast-limited performance compared to JWST MIRI while operating at comparable wavelengths. We describe the performance characteristics of the 13-μ\mum GeoSnap array operating between 38-45K, including quantum efficiency, well depth, linearity, gain, dark current, and frequency-dependent (1/f) noise profile.Comment: 17 pages, 17 figures. Accepted for publication in special addition of Astronomische Nachrichten / Astronomical Notes as a contribution to SDW202

    Isotopic evidence for long-distance connections of the AD thirteenth century Promontory caves occupants

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    Las cuevas Promontory (Utah) y la Cueva Franktown (Colorado) contienen registros de alta fidelidad en cuanto a las ocupaciones de corto término de grupos humanos con cultura material conectada al Subártico/Planicies del Norte. Esta investigación utiliza excremento, pelo, piel de cuero y colágeno del hueso de bisonte provenientes de los sitios Promontory y Franktown para establecer una base de datos isotópicos locales y variabilidad isotópica de carbono e identifica la piel de cuero de procedencia lejana. La envoltura de tobillo de un mocasín recuperado de la Cueva 1 de Promontory tuvo un valor δ13C que indica un componente C4 considerable en la dieta del animal, lo que es un resultado distinto a las dietas C3 que se identificaron a partir del análisis de 171 muestras de bisonte provenientes de Promontory y el norte de Utah. Aplicamos una combinación única de análisis isotópico de tejidos múltiples, mapas isotópicos (“isoscapes”) de carbono, ADN antiguo (identificación de sexo y especie), tasa de remodelación de tejidos, contextos arqueológicos y la ecología del bisonte para demonstrar que el valor alto δ13C probablemente no es un resultado debido al consumo de plantas locales, movilidad del bisonte o comercio. En cambio, la piel de cuero del bisonte fue probablemente adquirida a través de viajes de larga distancia hacia zonas con pastos C4 abundantes muy al sur o al este. El conocimiento extenso sobre el paisaje obtenido a través de asociaciones de larga distancia debió permitir a los habitantes de las cuevas Promontory tomar decisiones bien informadas sobre las direcciones y rutas de movimiento para realizar un cambio territorial, el cual parece haber ocurrido a finales del sigo XIII.The Promontory caves (Utah) and Franktown Cave (Colorado) contain high-fidelity records of short-term occupations by groups with material culture connections to the Subarctic/Northern Plains. This research uses Promontory and Franktown bison dung, hair, hide, and bone collagen to establish local baseline carbon isotopic variability and identify leather from a distant source. The ankle wrap of one Promontory Cave 1 moccasin had a δ13C value that indicates a substantial C4 component to the animal's diet, unlike the C3 diets inferred from 171 other Promontory and northern Utah bison samples. We draw on a unique combination of multitissue isotopic analysis, carbon isoscapes, ancient DNA (species and sex identification), tissue turnover rates, archaeological contexts, and bison ecology to show that the high δ13C value was not likely a result of local plant consumption, bison mobility, or trade. Instead, the bison hide was likely acquired via long-distance travel to/from an area of abundant C4 grasses far to the south or east. Expansive landscape knowledge gained through long-distance associations would have allowed Promontory caves inhabitants to make well-informed decisions about directions and routes of movement for a territorial shift, which seems to have occurred in the late thirteenth century

    Mediterranean spotted fever: clinical and laboratory characteristics of 415 Sicilian children

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    BACKGROUND: Mediterranean spotted fever (MSF) is an acute febrile, zoonotic disease caused by Rickettsia conorii and transmitted to humans by the brown dogtick Rhipicephalus sanguineus. Nearly four hundred cases are reported every year (mainly from June to September) on the Italian island of Sicily. The aim of the study was to analyze the clinical and laboratory characteristics of patients with MSF and the efficacy of the drugs administered. METHODS: Our study was carried out on 415 children with MSF, during the period January 1997 – December 2004, at the "G. Di Cristina" Children's hospital in Palermo, Sicily, Italy. On admission patients' clinical history, physical and laboratory examination and indirect immunofluorescence antibody test (IFAT) for Rickettsia conorii were performed. Diagnosis was considered confirmed if the patients had an MSF diagnostic score greater than or equal to 25 according to the Raoult's scoring system. All patients were treated with chloramphenicol or with macrolides (clarithromycin or azithromycin). RESULTS: Fever, rash and tache noire were present in 386 (93%), 392 (94.5%) and 263 (63.4%) cases respectively. Eighteen (4.6%) children showed atypical exanthema. Chloramphenicol and newer macrolides all appeared to be effective and safe therapies. CONCLUSION: Clinical features of 415 children with MSF were similar to those reported by other authors except for a lower incidence of headache, arthralgia and myalgia and a higher frequency of epato-splenomegaly. Concerning therapy, clarithromycin can be considered a valid alternative therapy to tetracyclines or chloramphenicol especially for children aged < eight years

    11β-Hydroxysteroid dehydrogenase type 1 inhibition in idiopathic intracranial hypertension: a double-blind randomized controlled trial

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    Treatment options for idiopathic intracranial hypertension are limited. The enzyme 11β-hydroxysteroid dehydrogenase type 1 has been implicated in regulating cerebrospinal fluid secretion, and its activity is associated with alterations in intracranial pressure in idiopathic intracranial hypertension. We assessed therapeutic efficacy, safety and tolerability and investigated indicators of in vivo efficacy of the 11β-hydroxysteroid dehydrogenase type 1 inhibitor AZD4017 compared with placebo in idiopathic intracranial hypertension. A multicenter, UK, 16-week phase II randomized, double-blind, placebo-controlled trial of 12-week treatment with AZD4017 or placebo was conducted. Women aged 18–55 years with active idiopathic intracranial hypertension (>25 cmH2O lumbar puncture opening pressure and active papilledema) were included. Participants received 400 mg of oral AZD4017 twice daily compared with matching placebo over 12 weeks. The outcome measures were initial efficacy, safety and tolerability. The primary clinical outcome was lumbar puncture opening pressure at 12 weeks analysed by intention-to-treat. Secondary clinical outcomes were symptoms, visual function, papilledema, headache and anthropometric measures. In vivo efficacy was evaluated in the central nervous system and systemically. A total of 31 subjects [mean age 31.2 (SD = 6.9) years and body mass index 39.2 (SD = 12.6) kg/m2] were randomized to AZD4017 (n = 17) or placebo (n = 14). At 12 weeks, lumbar puncture pressure was lower in the AZD4017 group (29.7 cmH2O) compared with placebo (31.3 cmH2O), but the difference between groups was not statistically significant (mean difference: −2.8, 95% confidence interval: −7.1 to 1.5; P = 0.2). An exploratory analysis assessing mean change in lumbar puncture pressure within each group found a significant decrease in the AZD4017 group [mean change: −4.3 cmH2O (SD = 5.7); P = 0.009] but not in the placebo group [mean change: −0.3 cmH2O (SD = 5.9); P = 0.8]. AZD4017 was safe, with no withdrawals related to adverse effects. Nine transient drug-related adverse events were reported. One serious adverse event occurred in the placebo group (deterioration requiring shunt surgery). In vivo biomarkers of 11β-hydroxysteroid dehydrogenase type 1 activity (urinary glucocorticoid metabolites, hepatic prednisolone generation, serum and cerebrospinal fluid cortisol:cortisone ratios) demonstrated significant enzyme inhibition with the reduction in serum cortisol:cortisone ratio correlating significantly with reduction in lumbar puncture pressure (P = 0.005, R = 0.70). This is the first phase II randomized controlled trial in idiopathic intracranial hypertension evaluating a novel therapeutic target. AZD4017 was safe and well tolerated and inhibited 11β-hydroxysteroid dehydrogenase type 1 activity in vivo. Reduction in serum cortisol:cortisone correlated with decreased intracranial pressure. Possible clinical benefits were noted in this small cohort. A longer, larger study would now be of interest
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