3,585 research outputs found
A direct image of the obscuring disk surrounding an active galactic nucleus
Active galactic nuclei (AGN) are generally accepted to be powered by the
release of gravitational energy in a compact accretion disk surrounding a
massive black hole. Such disks are also necessary to collimate powerful radio
jets seen in some AGN. The unifying classification schemes for AGN further
propose that differences in their appearance can be attributed to the opacity
of the accreting material, which may obstruct our view of the central region of
some systems. The popular model for the obscuring medium is a parsec-scale disk
of dense molecular gas, although evidence for such disks has been mostly
indirect, as their angular size is much smaller than the resolution of
conventional telescopes. Here we report the first direct images of a pc-scale
disk of ionised gas within the nucleus of NGC 1068, the archetype of obscured
AGN. The disk is viewed nearly edge-on, and individual clouds within the
ionised disk are opaque to high-energy radiation, consistent with the unifying
classification scheme. In projection, the disk and AGN axes align, from which
we infer that the ionised gas disk traces the outer regions of the long-sought
inner accretion disk.Comment: 14 pages, LaTeX, PSfig, to appear in Nature. also available at
http://hethp.mpe-garching.mpg.de/Preprint
Parallel processing area extraction and data transfer number reduction for automatic GPU offloading of IoT applications
For Open IoT, we have proposed Tacit Computing technology to discover the
devices that have data users need on demand and use them dynamically and an
automatic GPU offloading technology as an elementary technology of Tacit
Computing. However, it can improve limited applications because it only
optimizes parallelizable loop statements extraction. Thus, in this paper, to
improve performances of more applications automatically, we propose an improved
method with reduction of data transfer between CPU and GPU. We evaluate our
proposed offloading method by applying it to Darknet and find that it can
process it 3 times as quickly as only using CPU.Comment: 6 pages, 4 figures, in Japanese, IEICE Technical Report, SC2018-3
Resonant Coupling Parameter Estimation with Superconducting Qubits
Today’s quantum computers are composed of tens of qubits interacting with each other and the environment in increasingly complex networks. To achieve the best possible performance when operating such systems, it is necessary to have accurate knowledge of all parameters in the quantum computer Hamiltonian. In this paper, we demonstrate theoretically and experimentally a method to efficiently learn the parameters of resonant interactions for quantum computers consisting of frequency-tunable superconducting qubits. Such interactions include, for example, those with other qubits, resonators, two-level systems, or other wanted or unwanted modes. Our method is based on a significantly improved swap spectroscopy calibration and consists of an offline data collection algorithm, followed by an online Bayesian learning algorithm. The purpose of the offline algorithm is to detect and coarsely estimate resonant interactions from a state of zero knowledge. It produces a quadratic speedup in the scaling of the number of measurements. The online algorithm subsequently refines the estimate of the parameters to accuracy comparable with that of traditional swap spectroscopy calibration but in constant time. We perform an experiment implementing our technique with a superconducting qubit. By combining both algorithms, we observe a reduction of the calibration time by 1 order of magnitude. Our method will improve present medium-scale superconducting quantum computers and will also scale up to larger systems. Finally, the two algorithms presented here can be readily adopted by communities working on different physical implementations of quantum computing architectures
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Generation of Enterococci Bacteria in a Coastal Saltwater Marsh and Its Impact on Surf Zone Water Quality
Elevated levels of enterococci bacteria, an indicator of fecal pollution, are routinely detected in the surf zone at Huntington State and City Beaches in southern California. A multidisciplinary study was carried out to identify sources of enterococci bacteria landward of the coastline. We find that enterococci bacteria are present at high concentrations in urban runoff, bird feces, marsh sediments, and on marine vegetation. Surprisingly, urban runoff appears to have relatively little impact on surf zone water quality because of the long time required for this water to travel from its source to the ocean. On the other hand, enterococci bacteria generated in a tidal saltwater marsh located near the beach significantly impact surf zone water quality. This study identifies a potential tradeoff between restoring coastal wetlands and protecting beach water quality and calls into question the use of ocean bathing water standards based on enterococci at locations near coastal wetlands
Rubinstein-Taybi syndrome with scoliosis
<p>Abstract</p> <p>Study Design</p> <p>Case report.</p> <p>Objective</p> <p>The authors present the case of a 14-year-old boy with Rubinstein-Taybi syndrome (RSTS) presenting scoliosis.</p> <p>Summary of Background Data</p> <p>There have been no reports on surgery for RSTS presenting scoliosis.</p> <p>Methods</p> <p>The patient was referred to our hospital for evaluation of a progressive spinal curvature. A standing anteroposterior spine radiograph at presentation to our hospital revealed an 84-degree right thoracic curve from T6 to T12, along with a 63-degree left lumbar compensatory curve from T12 to L4. We planned a two-staged surgery and decided to fuse from T4 to L4. The first operation was front-back surgery because of the rigidity of the right thoracic curve. The second operation of lumbar anterior discectomy and fusion was arranged 9 months after the first surgery to prevent the crankshaft phenomenon due to his natural course of adolescent growth. To avoid respiratory complications, the patient was put on a respirator in the ICU for several days after both surgeries.</p> <p>Results</p> <p>Full-length spine radiographs after the first surgery revealed no instrumentation failure and showed that the right thoracic curve was corrected to 31 degrees and the left lumbar curve was corrected to 34 degrees. No postoperative complications occurred after both surgeries.</p> <p>Conclusions</p> <p>We succeeded in treating the patient without complications. Full-length spine standing radiographs at one year after the second operation demonstrated a stable bony arthrodesis with no loss of initial correction.</p
Lymphocyte subsets and the role of Th1/Th2 balance in stressed chronic pain patients
Background: The complex regional pain syndrome (CRPS) and fibromyalgia (FM) are chronic pain syndromes occurring in highly stressed individuals. Despite the known connection between the nervous system and immune cells, information on distribution of lymphocyte subsets under stress and pain conditions is limited. Methods: We performed a comparative study in 15 patients with CRPS type I, 22 patients with FM and 37 age- and sex-matched healthy controls and investigated the influence of pain and stress on lymphocyte number, subpopulations and the Th1/Th2 cytokine ratio in T lymphocytes. Results: Lymphocyte numbers did not differ between groups. Quantitative analyses of lymphocyte subpopulations showed a significant reduction of cytotoxic CD8+ lymphocytes in both CRPS (p < 0.01) and FM (p < 0.05) patients as compared with healthy controls. Additionally, CRPS patients were characterized by a lower percentage of IL-2-producing T cell subpopulations reflecting a diminished Th1 response in contrast to no changes in the Th2 cytokine profile. Conclusions: Future studies are warranted to answer whether such immunological changes play a pathogenetic role in CRPS and FM or merely reflect the consequences of a pain-induced neurohumoral stress response, and whether they contribute to immunosuppression in stressed chronic pain patients. Copyright (c) 2008 S. Karger AG, Basel
Proactive and politically skilled professionals: What is the relationship with affective occupational commitment?
The aim of this study is to extend research on employee affective commitment in three ways: (1) instead of organizational commitment the focus is on occupational commitment; (2) the role of proactive personality on affective occupational commitment is examined; and (3) occupational satisfaction is examined as a mediator and political skills as moderator in the relationship between proactive personality and affective occupational commitment. Two connected studies, one in a hospital located in the private sector and one in a university located in the public sector, are carried out in Pakistan, drawing on a total sample of over 400 employees. The results show that proactive personality is positively related to affective occupational commitment, and that occupational satisfaction partly mediates the relationship between proactive personality and affective occupational commitment. No effect is found for a moderator effect of political skills in the relationship between proactive personality and affective occupational commitment. Political skills however moderate the relationship between proactive personality and affective organizational commitment
Subtidal macrozoobenthos communities from northern Chile during and post El Niño 1997–1998
Despite a large amount of climatic and oceanographic information dealing with the recurring climate phenomenon El Niño (EN) and its well known impact on diversity of marine benthic communities, most published data are rather descriptive and consequently our understanding of the underlying mechanisms and processes that drive community structure during EN are still very scarce. In this study, we address two questions on the effects of EN on macrozoobenthic communities: (1) how does EN affect species diversity of the communities in northern Chile? and (2) is EN a phenomenon that restarts community assembling processes by affecting species interactions in northern Chile? To answer these questions, we compared species diversity and co-occurrence patterns of soft-bottoms macrozoobenthos communities from the continental shelf off northern Chile during (March 1998) and after (September 1998) the strong EN event 1997–1998. The methods used varied from species diversity and species co-occurrence analyses to multivariate ordination methods.
Our results indicate that EN positively affects diversity of macrozoobenthos communities in the study area, increasing the species richness and diversity and decreasing the species dominance. EN represents a strong disturbance that affects species interactions that rule the species assembling processes in shallow-water, sea-bottom environments
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