1,806 research outputs found

    Double radiative decay Z→ffˉγγZ \rightarrow f\bar{f}\gamma\gamma in the Standard Model

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    Z-boson decay Z→ff~γγZ \rightarrow f\tilde{f}\gamma\gamma in the Standard Model is analysed. The distribution function on the invariant masses of the photon and fermion pairs is calculated in the leading logarithmic approximation. It is shown that this distribution function has a specific shape of a ``crest''. (To be published in Mod.Phys.Lett.A)Comment: 6 pages, LaTeX, (the figures are not included), Yaroslavl, Yaroslavl State University preprint YARU-HE-94/0

    Infrared-ultraviolet spectra of active galactic nuclei

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    Data from IRAS and IUE were combined with ground based optical and infrared spectrophotometry to derive emission line free spectral energy distributions (SEDs) for 29 active galactic nuclei (AGNs) between 0.1 and 100 microns. The IRAS data were scaled down to account for extended emission. These correction factors, determined by comparing small aperture ground based 10.6 micron data with large aperture IRAS 12 micron fluxes, were usually less than 25%. These corrected SEDs are shown

    Secure Satellite Communication Systems Design with Individual Secrecy Rate Constraints

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    In this paper, we study multibeam satellite secure communication through physical (PHY) layer security techniques, i.e., joint power control and beamforming. By first assuming that the Channel State Information (CSI) is available and the beamforming weights are fixed, a novel secure satellite system design is investigated to minimize the transmit power with individual secrecy rate constraints. An iterative algorithm is proposed to obtain an optimized power allocation strategy. Moreover, sub-optimal beamforming weights are obtained by completely eliminating the co-channel interference and nulling the eavesdroppers' signal simultaneously. In order to obtain jointly optimized power allocation and beamforming strategy in some practical cases, e.g., with certain estimation errors of the CSI, we further evaluate the impact of the eavesdropper's CSI on the secure multibeam satellite system design. The convergence of the iterative algorithm is proven under justifiable assumptions. The performance is evaluated by taking into account the impact of the number of antenna elements, number of beams, individual secrecy rate requirement, and CSI. The proposed novel secure multibeam satellite system design can achieve optimized power allocation to ensure the minimum individual secrecy rate requirement. The results show that the joint beamforming scheme is more favorable than fixed beamforming scheme, especially in the cases of a larger number of satellite antenna elements and higher secrecy rate requirement. Finally, we compare the results under the current satellite air-interface in DVB-S2 and the results under Gaussian inputs.Comment: 34 pages, 10 figures, 1 table, submitted to "Transactions on Information Forensics and Security

    Neurolytic Celiac Plexus Blockade in Patients with Upper Intraabdominal Malignancies: An Evidence-Based Narrative Review

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    Background: Cancer-related abdominal pain is a common symptom associated with upper intra-abdominal carcinoma, especially in patients with advanced disease and it has posed a significant therapeutic challenge to medical practitioners. Typically, cancer pain can be managed by following the World Health Organization 3-step analgesic ladder. However, analgesic use of opioids, the mainstay treatment for moderate-to-severe cancer-related pain, may be ineffective in a subset of cancer patients. Escalation of dosage may be limited by opioid-induced side effects. The aim of this study was to review the literature addressing the effect of neurolytic celiac plexus block (NCPB) on the palliation of pain emanating from advanced upper intra-abdominal malignancies. Methods: Electronic databases including Medline/PubMed, EMBASE, and Cochrane Library were searched. Only studies with a high level of evidence were reviewed. These included prospective randomized control studies, systematic reviews and meta-analyses. Further, references from included articles were carefully reviewed for additional relevant trials. Results: A total of 13 prospective randomized trials, 5 systematic reviews and meta-analyses, and one Cochrane review article were found to meet eligibility criteria. Conclusion: Neurolysis of the celiac/splanchnic plexus is an effective and safe therapeutic modality that should be considered early for palliation of cancer-related pain in advanced upper intra-abdominal malignancies. This is especially true for patients with intolerable opioid-induced adverse events and painful symptoms resistant to oral analgesics

    Neurolytic Celiac Plexus Blockade in Patients with Upper Intraabdominal Malignancies: An Evidence-Based Narrative Review

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    Background: Cancer-related abdominal pain is a common symptom associated with upper intra-abdominal carcinoma, especially in patients with advanced disease and it has posed a significant therapeutic challenge to medical practitioners. Typically, cancer pain can be managed by following the World Health Organization 3-step analgesic ladder. However, analgesic use of opioids, the mainstay treatment for moderate-to-severe cancer-related pain, may be ineffective in a subset of cancer patients. Escalation of dosage may be limited by opioid-induced side effects. The aim of this study was to review the literature addressing the effect of neurolytic celiac plexus block (NCPB) on the palliation of pain emanating from advanced upper intra-abdominal malignancies. Methods: Electronic databases including Medline/PubMed, EMBASE, and Cochrane Library were searched. Only studies with a high level of evidence were reviewed. These included prospective randomized control studies, systematic reviews and meta-analyses. Further, references from included articles were carefully reviewed for additional relevant trials. Results: A total of 13 prospective randomized trials, 5 systematic reviews and meta-analyses, and one Cochrane review article were found to meet eligibility criteria. Conclusion: Neurolysis of the celiac/splanchnic plexus is an effective and safe therapeutic modality that should be considered early for palliation of cancer-related pain in advanced upper intra-abdominal malignancies. This is especially true for patients with intolerable opioid-induced adverse events and painful symptoms resistant to oral analgesics

    The Global Ocean Data Analysis Project version 2 (GLODAPv2) – an internally consistent data product for the world ocean

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    27 páginas, 11 tablas, 9 figuras.-- Are Olsen ... et al.-- This work is distributed under the Creative Commons Attribution 3.0 License.-- Proyecto CarbochangeVersion 2 of the Global Ocean Data Analysis Project (GLODAPv2) data product is composed of data from 724 scientific cruises covering the global ocean. It includes data assembled during the previous efforts GLODAPv1.1 (Global Ocean Data Analysis Project version 1.1) in 2004, CARINA (CARbon IN the Atlantic) in 2009/2010, and PACIFICA (PACIFic ocean Interior CArbon) in 2013, as well as data from an additional 168 cruises. Data for 12 core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have been subjected to extensive quality control, including systematic evaluation of bias. The data are available in two formats: (i) as submitted but updated to WOCE exchange format and (ii) as a merged and internally consistent data product. In the latter, adjustments have been applied to remove significant biases, respecting occurrences of any known or likely time trends or variations. Adjustments applied by previous efforts were re-evaluated. Hence, GLODAPv2 is not a simple merging of previous products with some new data added but a unique, internally consistent data product. This compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg−1 in dissolved inorganic carbon, 6 µmol kg−1 in total alkalinity, 0.005 in pH, and 5 % for the halogenated transient tracersThe GLODAPv2 project itself received support from a number of agencies and projects. Importantly, the EU-IP CARBOCHANGE (FP7 264878) provided funding for A. Olsen, M. Hoppema, S. van Heuven, and T. Tanhua as well as travel support for R. Key and the project framework that instigated GLODAPv2. A. Olsen further acknowledges generous support from the FRAM – High North Research Centre for Climate and the Environment, the Centre for Climate Dynamics at the Bjerknes Centre for Climate Research, the EU AtlantOS (grant agreement no. 633211) project, and the Norwegian Research Council project SNACS (229752). R. Key was supported by KeyCrafts grant 2012-001, CICS grants NA08OAR4320752 and NA14OAR4320106, NASA grant NNX12AQ22G, NSF grants OCE-0825163 (with a supplement via WHOI P.O. C119245) and PLR-1425989, and Battelle contract #4000133565 to CDIAC. A. Kozyr was supported by DOE contract DE-AC05-00OR2272 to UT-Battelle, operators of CDIAC under ORNL. S. K. Lauvset and E. Jeansson appreciate support from the Norwegian Research Council (projects DECApH, 214513 and VENTILATE, 229791). The International Ocean Carbon Coordination Project (IOCCP) also supported this activity through the U.S. National Science Foundation grant (OCE- 1243377) to the Scientific Committee on Oceanic Research. A. Velo and F. F. Pérez acknowledge the support provided by BOCATS project (CTM2013-41048-P) co-funded by the Spanish Government and the Fondo Europeo de Desarrollo Regional (FEDER), and the AtlantOS project (grant agreement no. 633211) funded by EU H2020 research and innovation programme.Peer reviewe

    Relaying energy allocation in training-based amplify and forward relay communications

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    We consider relay-assisted communication in a training-based transmission scheme. Each transmission block consists of a training phase and a data transmission phase. The relay node employs the amplify-and-forward protocol during all transmissions. We focus on the relay signaling design and investigate the benefit of allowing for different relaying power during the training phase and the data transmission phase. Specifically, the relaying energy allocation between the two phases is optimized for maximizing the average received signal-to-noise ratio at the destination node. We study this optimization problem for both single-antenna relay and multi-antenna relay and derive a simple closed-form relaying energy allocation strategy that achieves near-optimal performance. This closed-form strategy depends only on the length of the data transmission phase but not on other system parameters such as the relaying energy budget, the number of antennas at the relay, and the distances between the source, relay and destination nodes.This work was supported by the Australian Research Council's Discovery Projects funding scheme (project no. DP0984950, DP110102548) and the Research Council of Norway through the project 197565/V30. The work has been carried out while T. Lamahewa was at the Australian National University

    Calculations of the shore retreat rate using thermoterrace dimensions

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    Thirty-Day Unplanned Readmission and Its Effect on 90-Day Mortality in Hepatocellular Carcinoma Patients Undergoing Partial Hepatectomy

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    Background: Despite advances of surgical techniques, hepatectomy continues to be potentially dangerous and is associated with postoperative mortality, morbidity and readmission. The objective of this study was to determine the effect of 30-day unplanned readmission on ‘conditional’ 90-day mortality among hepatocellular carcinoma (HCC) patients who underwent partial hepatectomy. Methods: National Cancer Database (NCDB) was queried from 2004 to 2012 for patients with hepatocellular carcinoma (HCC) who underwent partial hepatectomy. Thirty-day unplanned readmission rate, and associated risk factors, was determined for 7,696 patients. The association between 30-day unplanned readmission and conditional 90-day mortality was further addressed. Results: The 30-day unplanned readmission rate for patients with HCC who underwent partial hepatectomy was 5.2%. Risk factors associated with 30-day unplanned readmission were sex, race/ethnicity, Charlson-Deyo score, and annual hospital hepatectomy volume. An overall adjusted odds of having conditional 90-day mortality was 2.325 times higher (95% CI 1.643 - 3.219) among patients with a history of 30-day unplanned readmission than those without. This association was dependent on age, sex, race/ethnicity, insurance status, alpha-fetoprotein (AFP), liver fibrosis, Charlson-Deyo comorbidity score and annual hospital hepatectomy volume. Conclusion: Efforts in patient care should be taken to reduce 30-day unplanned readmission after partial hepatectomy for patients with HCC to reduce conditional 90-day mortality
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