272 research outputs found

    A step towards a reinforcement learning de novo genome assembler

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    The use of reinforcement learning has proven to be very promising for solving complex activities without human supervision during their learning process. However, their successful applications are predominantly focused on fictional and entertainment problems - such as games. Based on the above, this work aims to shed light on the application of reinforcement learning to solve this relevant real-world problem, the genome assembly. By expanding the only approach found in the literature that addresses this problem, we carefully explored the aspects of intelligent agent learning, performed by the Q-learning algorithm, to understand its suitability to be applied in scenarios whose characteristics are more similar to those faced by real genome projects. The improvements proposed here include changing the previously proposed reward system and including state space exploration optimization strategies based on dynamic pruning and mutual collaboration with evolutionary computing. These investigations were tried on 23 new environments with larger inputs than those used previously. All these environments are freely available on the internet for the evolution of this research by the scientific community. The results suggest consistent performance progress using the proposed improvements, however, they also demonstrate the limitations of them, especially related to the high dimensionality of state and action spaces. We also present, later, the paths that can be traced to tackle genome assembly efficiently in real scenarios considering recent, successfully reinforcement learning applications - including deep reinforcement learning - from other domains dealing with high-dimensional inputs

    BeppoSAX Observations of 1 Jy BL Lacertae Objects. I

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    We present new BeppoSAX observations of seven BL Lacertae objects selected from the 1 Jy sample plus one additional source. The collected data cover the energy range 0.1 - 10 keV (observer's frame), reaching ~ 50 keV for one source (BL Lac). All sources characterized by a peak in their multifrequency spectra at infrared/optical energies (i.e., of the LBL type) display a relatively flat (alpha_x ~ 0.9) X-ray spectrum, which we interpret as inverse Compton emission. Four objects (2/3 of the LBL) show some evidence for a low-energy steepening which is likely due to the synchrotron tail merging into the inverse Compton component around ~ 1 - 3 keV. If this were generally the case with LBL, it would explain why the 0.1 - 2.4 keV ROSAT spectra of our sources are systematically steeper than the BeppoSAX ones (by ~ 0.5 in alpha_x). The broad-band spectral energy distributions fully confirm this picture and a synchrotron inverse Compton model allows us to derive the physical parameters (intrinsic power, magnetic field, etc.) of our sources. Combining our results with those obtained by BeppoSAX on BL Lacs covering a wide range of synchrotron peak frequencies, we confirm and clarify the dependence of the X-ray spectral index on synchrotron peak frequency originally found in ROSAT data.Comment: 14 pages, 7 figures. Accepted for publication in MNRAS. Postscript file also available at http://icarus.stsci.edu/~padovani/xrayspectra_papers.htm

    Benefits of fasting abbreviation and early refeeding of multimodal perioperative care protocols: Benefícios da abreviação de jejum e realimentação precoce dos protocolos de cuidados perioperatórios multimodais

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    The multimodal protocols of perioperative care, as a European project of ERAS-Enhanced Recovery After Surgery and, in Brazil, the project ACERTO (Acceleration of Total Post-Operative Recovery), emerged as relevant alternatives to reduce preoperative discomforts, including anxiety, thirst, hunger, and enhance the recovery of surgical patients. These initiatives, supported by scientific evidence, advocate the fasting abbreviation with the ingestion of clear liquids up to 2 hours before elective surgery, as a strategy to reduce insulin resistance, immunomodulation and for the purpose of anesthetic induction, without causing risks of aspiration of gastric contents, as well as early refeeding with a small volume of diet, capable of stimulating the gastrointestinal tract and reducing the period of postoperative ileus. In this way, the literature shows that such measures are safe and bring several benefits, such as reducing hospitalization time and reducing the number of complications

    Headache: Prevalence and relationship with office or ambulatory blood pressure in a general population sample (the Vobarno Study).

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    The association of headache and arterial hypertension is still controversial, although headache is usually considered a symptom of hypertension. The aim of this study is to evaluate the prevalence of headache in a general population sample and the relationship with arterial hypertension, as diagnosed by office measurements and ambulatory monitoring of blood pressure (BP).In the randomized sample of the Vobarno population, 301 subjects (126 males, 175 females, age range 35-50 years) underwent a structured standardized headache questionnaire, office and 24-h ambulatory BP monitoring.Prevalence of lifetime headache and of migraine was greater in females than in males. Office and 24-h BP values did not differ between subjects without headache and subjects with headache. No differences in headache prevalence (58% vs 55%), migraine prevalence (32% vs 28%) and use of analgesic drugs in the presence of headache (82% vs 78%) were observed between hypertensive patients (93.5% newly diagnosed, 6.5% treated) and normotensive subjects.In a general population sample, hypertension (diagnosed by office and/or 24-h BP) is not associated with headache

    Advances in Quantitative Imaging of Genetic and Acquired Myopathies: Clinical Applications and Perspectives

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    In the last years, magnetic resonance imaging (MRI) has become fundamental for the diagnosis and monitoring of myopathies given its ability to show the severity and distribution of pathology, to identify specific patterns of damage distribution and to properly interpret a number of genetic variants. The advances in MR techniques and post-processing software solutions have greatly expanded the potential to assess pathological changes in muscle diseases, and more specifically of myopathies; a number of features can be studied and quantified, ranging from composition, architecture, mechanical properties, perfusion, and function, leading to what is known as quantitative MRI (qMRI). Such techniques can effectively provide a variety of information beyond what can be seen and assessed by conventional MR imaging; their development and application in clinical practice can play an important role in the diagnostic process and in assessing disease course and treatment response. In this review, we briefly discuss the current role of muscle MRI in diagnosing muscle diseases and describe in detail the potential and perspectives of the application of advanced qMRI techniques in this field

    Late and Severe Myopathy in a Patient With Glycogenosis VII Worsened by Cyclosporine and Amiodarone

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    Glycogenosis VII (GSD VII) is a rare autosomal recessive glycogen storage disorder caused by mutations in the PFKM gene encoding the phosphofructokinase (PFK) enzyme. A classical form with exercise intolerance, contractures, and myoglobinuria, a severe multisystem infantile form, an hemolytic variant and a late-onset form usually presenting with muscle pain and mild fixed proximal weakness have been reported. We describe a 65-year-old man affected by muscle PFK deficiency who, since the age of 33, presented with exercise intolerance and myoglobinuria. Muscle biopsy showed a vacuolar myopathy with glycogen storage. The biochemical assay of PFK-M showed very low residual activity (6%). Genetic analysis of PFKM gene evidenced the presence of the heterozygote c.1817A>C (p.Asp543Ala) and c.488 G>A (p.Arg100Gln) pathogenic mutations. In his fifth decade, he started cyclosporine after liver transplantation for hepatocellular carcinoma and, then, amiodarone because of atrial fibrillation. In the following years, he developed a progressive and severe muscle weakness, mainly involving lower limbs, up to a loss of independent walking. Muscle MRI showed adipose substitution of both anterior and posterior thigh muscles with selective sparing of the medial compartment. Marked signs of adipose substitution were also documented in the legs with a selective replacement of gemelli and peroneus muscles. The temporal relationship between the patient's clinical worsening and chronic treatment with cyclosporine and amiodarone suggests an additive toxic damage by these two potentially myotoxic drugs determining such an unusually severe phenotype, also confirmed by muscle MRI findings

    A model for the cosmological evolution of low frequency radio sources

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    We present a new evolutionary model that describes the population properties of radio sources at frequencies <5 GHz, thus complementing the De Zotti et al. (2005) model, holding at higher frequencies. We find that simple analytic luminosity evolution is still sufficient to fit the wealth of available data on local luminosity functions, multi-frequency source counts, and redshift distributions. However, the fit requires a luminosity-dependent decline of source luminosities at high redshifts, at least for steep-spectrum sources, thus confirming earlier indications of a "downsizing" also for radio sources. The upturn of source counts at sub-mJy levels is accounted for by a straightforward extrapolation, using the empirical far-IR/radio correlation, of evolutionary models matching the far-IR counts and redshift distributions of star-forming galaxies. We also discuss the implications of the new model for the interpretation of data on large-scale clustering of radio sources and on the Integrated Sachs-Wolfe (ISW) effect, and for the investigation of the contribution of discrete sources to the extragalactic background. As for the ISW effect, a new analysis exploiting a very clean CMB map, yields at a substantially higher significance than reported before.Comment: 14 pages, 11 figures, accepted for publication on MNRA

    Radical radiotherapy for paediatric solid tumour metastases:An overview of current European protocols and outcomes of a SIOPE multicenter survey

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    Purpose/objective: About 20% of children with solid tumours (ST) present with distant metastases (DM). Evidence regarding the use of radical radiotherapy of these DM is sparse and open for personal interpretation. The aim of this survey was to review European protocols and to map current practice regarding the irradiation of DM across SIOPE-affiliated countries. Materials/methods: Radiotherapy guidelines for metastatic sites (bone, brain, distant lymph nodes, lung and liver) in eight European protocols for rhabdomyosarcoma, non-rhabdomyosarcoma soft-tissue sarcoma, Ewing sarcoma, neuroblastoma and renal tumours were reviewed. SIOPE centres irradiating >= 50 children annually were invited to participate in an online survey. Results: Radiotherapy to at least one metastatic site was recommended in all protocols, except for high-risk neuroblastoma. Per protocol, dose prescription varied per site, and information on delineation and treatment planning/delivery was generally missing. Between July and September 2019, 20/27 centres completed the survey. Around 14% of patients were deemed to have DM from ST at diagnosis, of which half were treated with curative intent. A clear cut-off for a maximum number of DM was not used in half of the centres. Regardless of the tumour type and site, conventional radiotherapy regimens were most commonly used to treat DM. When stereotactic radiotherapy was used, a wide range of fractionation regimens were applied. Conclusion: Current radiotherapy guidelines for DM do not allow a consistent approach in a multicentre setting. Prospective (randomised) trials are needed to define the role of radical irradiation of DM from paediatric ST. (C) 2020 The Author(s). Published by Elsevier Ltd
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