2,790 research outputs found

    Conjugate Hard X-ray Footpoints in the 2003 October 29 X10 Flare: Unshearing Motions, Correlations, and Asymmetries

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    We present a detailed imaging and spectroscopic study of the conjugate hard X-ray (HXR) footpoints (FPs) observed with RHESSI in the 2003 October 29 X10 flare. The double FPs first move toward and then away from each other, mainly parallel and perpendicular to the magnetic neutral line, respectively. The transition of these two phases of FP unshearing motions coincides with the direction reversal of the motion of the loop-top (LT) source, and with the minima of the estimated loop length and LT height. The FPs show temporal correlations between HXR flux, spectral index, and magnetic field strength. The HXR flux exponentially correlates with the magnetic field strength, which also anti-correlates with the spectral index before the second HXR peak's maximum, suggesting that particle acceleration sensitively depends on the magnetic field strength and/or reconnection rate. Asymmetries are observed between the FPs: on average, the eastern FP is 2.2 times brighter in HXR flux and 1.8 times weaker in magnetic field strength, and moves 2.8 times faster away from the neutral line than the western FP; the estimated coronal column density to the eastern FP from the LT source is 1.7 times smaller. The two FPs have marginally different spectral indexes. The eastern-to-western FP HXR flux ratio and magnetic field strength ratio are anti-correlated only before the second HXR peak's maximum. Neither magnetic mirroring nor column density alone can explain the totality of these observations, but their combination, together with other transport effects, might provide a full explanation. We have also developed novel techniques to remove particle contamination from HXR counts and to estimate effects of pulse pileup in imaging spectroscopy, which can be applied to other RHESSI flares in similar circumstances.Comment: 22 pages, 14 figures, 4 tables; ApJ 2009, in pres

    Predicting individual-level income from Facebook profiles

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    Information about a person's income can be useful in several business-related contexts, such as personalized advertising or salary negotiations. However, many people consider this information private and are reluctant to share it. In this paper, we show that income is predictable from the digital footprints people leave on Facebook. Applying an established machine learning method to an income-representative sample of 2,623 U.S. Americans, we found that (i) Facebook Likes and Status Updates alone predicted a person's income with an accuracy of up to r = 0.43, and (ii) Facebook Likes and Status Updates added incremental predictive power above and beyond a range of socio-demographic variables (ΔR2 = 6-16%, with a correlation of up to r = 0.49). Our findings highlight both opportunities for businesses and legitimate privacy concerns that such prediction models pose to individuals and society when applied without individual consent

    Efficient and Compact Representations of Some Non-canonical Prefix-Free Codes

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    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-46049-9_5[Abstract] For many kinds of prefix-free codes there are efficient and compact alternatives to the traditional tree-based representation. Since these put the codes into canonical form, however, they can only be used when we can choose the order in which codewords are assigned to characters. In this paper we first show how, given a probability distribution over an alphabet of σσ characters, we can store a nearly optimal alphabetic prefix-free code in o(σ)o(σ) bits such that we can encode and decode any character in constant time. We then consider a kind of code introduced recently to reduce the space usage of wavelet matrices (Claude, Navarro, and Ordóñez, Information Systems, 2015). They showed how to build an optimal prefix-free code such that the codewords’ lengths are non-decreasing when they are arranged such that their reverses are in lexicographic order. We show how to store such a code in O(σlogL+2ϵL)O(σlog⁡L+2ϵL) bits, where L is the maximum codeword length and ϵϵ is any positive constant, such that we can encode and decode any character in constant time under reasonable assumptions. Otherwise, we can always encode and decode a codeword of ℓℓ bits in time O(ℓ)O(ℓ) using O(σlogL)O(σlog⁡L) bits of space.Ministerio de Economía, Industria y Competitividad; TIN2013-47090-C3-3-PMinisterio de Economía, Industria y Competitividad; TIN2015-69951-RMinisterio de Economía, Industria y Competitividad; ITC-20151305Ministerio de Economía, Industria y Competitividad; ITC-20151247Xunta de Galicia; GRC2013/053Chile. Núcleo Milenio Información y Coordinación en Redes; ICM/FIC.P10-024FCOST. IC1302Academy of Finland; 268324Academy of Finland; 25034

    Acral-type Malignant Acanthosis Nigricans Associated with Gastric Adenocarcinoma

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    Acanthosis nigricans is a symmetric eruption characterized by the presence of a hyperpigmented, velvety cutaneous thickening, that can develop on any part of the body, but characteristically affects the flexural areas of the body. The velvety hyperkeratotic lesions can be located on the dorsum of the hands and feet in dark-skinned people in the form of a variant of acanthosis nigricans called as acral acanthotic anomaly or acral type acanthosis nigricans. Although acanthosis nigricans is associated with malignant tumors, particularly gastric carcinoma, acral type acanthosis nigricans has never been reported to be associated with gastric adenocarcinoma. In our present study, we describe a case of 58-year-old man with acral type acanthosis nigricans and its association with carcinoma of the stomach; a marked improvement was seen in the skin condition of the patient with chemotherapy

    Thermographic imaging in sports and exercise medicine: A Delphi study and consensus statement on the measurement of human skin temperature

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    This is an accepted manuscript of an article published by Elsevier in Journal of Thermal Biology on 18/07/2017, available online: https://doi.org/10.1016/j.jtherbio.2017.07.006 The accepted version of the publication may differ from the final published version.© 2017 Elsevier Ltd The importance of using infrared thermography (IRT) to assess skin temperature (tsk) is increasing in clinical settings. Recently, its use has been increasing in sports and exercise medicine; however, no consensus guideline exists to address the methods for collecting data in such situations. The aim of this study was to develop a checklist for the collection of tsk using IRT in sports and exercise medicine. We carried out a Delphi study to set a checklist based on consensus agreement from leading experts in the field. Panelists (n  =  24) representing the areas of sport science (n = 8; 33%), physiology (n = 7; 29%), physiotherapy (n = 3; 13%) and medicine (n = 6; 25%), from 13 different countries completed the Delphi process. An initial list of 16 points was proposed which was rated and commented on by panelists in three rounds of anonymous surveys following a standard Delphi procedure. The panel reached consensus on 15 items which encompassed the participants’ demographic information, camera/room or environment setup and recording/analysis of tsk using IRT. The results of the Delphi produced the checklist entitled “Thermographic Imaging in Sports and Exercise Medicine (TISEM)” which is a proposal to standardize the collection and analysis of tsk data using IRT. It is intended that the TISEM can also be applied to evaluate bias in thermographic studies and to guide practitioners in the use of this technique.Published versio

    Two Cases of Hypertensive Encephalopathy Involving the Brainstem

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    Hypertensive encephalopathy is a medical emergency whose clinical manifestations are usually associated with bilateral parieto-occipital lesions. Predominant brainstem edema without accompanying occipital lesions is rare in hypertensive encephalopathy and usually occurs in patients with secondary hypertension. We describe the clinical and radiological features of two patients with reversible hypertensive brainstem encephalopathy. Both patients had chronic renal failure, but the extensive neuroimaging abnormalities revealed few clinical features of brainstem involvement. The clinical findings and neuroimaging abnormalities resolved once the hypertension was treated

    Surveying (Dis)Parities and Concerns of Compute Hungry NLP Research

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    Many recent improvements in NLP stem from the development and use of large pre-trained language models (PLMs) with billions of parameters. Large model sizes makes computational cost one of the main limiting factors for training and evaluating such models; and has raised severe concerns about the sustainability, reproducibility, and inclusiveness for researching PLMs. These concerns are often based on personal experiences and observations. However, there had not been any large-scale surveys that investigate them. In this work, we provide a first attempt to quantify these concerns regarding three topics, namely, environmental impact, equity, and impact on peer reviewing. By conducting a survey with 312 participants from the NLP community, we capture existing (dis)parities between different and within groups with respect to seniority, academia, and industry; and their impact on the peer reviewing process. For each topic, we provide an analysis and devise recommendations to mitigate found disparities, some of which already successfully implemented. Finally, we discuss additional concerns raised by many participants in free-text responses

    Posterior reversible encephalopathy syndrome in an untreated hypertensive patient after spinal surgery under general anesthesia -A case report-

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    Posterior reversible encephalopathy syndrome (PRES) is an unfamiliar term to anesthesiologists, and this is characterized by neurologic symptoms that include mental change, headache, seizure and visual disturbance and also abnormal neuroimaging finding. A 71-year-old female patient was operated on for posterior decompression and total laminectomy under general anesthesia for the spinal stenosis. After the operation, she developed generalized tonic-clonic seizure and a stuporous mentality in the recovery room. The magnetic resonance imaging (MRI) revealed swelling and increased signal intensity at the deep gray nuclei, cerebral cortex and cerebellum. After one week, she returned to an alert mentality and then she was diagnosed with PRES. She was discharged without any neurologic deficit on postoperative day 20. This report describes our experience with PRES after spinal surgery was performed under general anesthesia on a suspected untreated hypertensive patient

    Whole-genome analysis of histone H3 lysine 27 trimethylation in Arabidopsis

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    Trimethylation of histone H3 lysine 27 (H3K27me3) plays critical roles in regulating animal development, and in several cases, H3K27me3 is also required for the proper expression of developmentally important genes in plants. However, the extent to which H3K27me3 regulates plant genes on a genome-wide scale remains unknown. In addition, it is not clear whether the establishment and spreading of H3K27me3 occur through the same mechanisms in plants and animals. We identified regions containing H3K27me3 in the genome of the flowering plant Arabidopsis thaliana using a high-density whole-genome tiling microarray. The results suggest that H3K27me3 is a major silencing mechanism in plants that regulates an unexpectedly large number of genes in Arabidopsis (~4,400), and that the maintenance of H3K27me3 is largely independent of other epigenetic pathways, such as DNA methylation or RNA interference. Unlike in animals, where H3K27m3 occupies large genomic regions, in Arabidopsis, we found that H3K27m3 domains were largely restricted to the transcribed regions of single genes. Furthermore, unlike in animals systems, H3K27m3 domains were not preferentially associated with low-nucleosome density regions. The results suggest that different mechanisms may underlie the establishment and spreading of H3K27me3 in plants and animals

    Vulvar Skin Metastasis of Lung Squamous Cell Carcinoma

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    In this study, we examined a case where lung cancer metastasized to the vulvar area. A 79-year-old woman that was a heavy smoker was referred to our department with a short (two-week) history of dyspnea, and with a painful nodule on her right labium majora, which she had noticed almost three years earlier. Histopathologically, the specimen appeared as a poorly differentiated squamous cell carcinoma. The chest X-ray, chest computerized tomography scan, and percutaneous transthoracic needle biopsy via bronchoscopy revealed squamous cell carcinoma in the right upper lobe of the lung. Based on these clinical and histopathological findings, we concluded that her condition was skin metastasis at the right labium majora from the lung cancer, which occurs very rarely
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