From MFN to SFN: Performance Prediction Through Machine Learning

In the last decade, the transition of digital terrestrial television (DTT) systems from multi-frequency networks (MFNs) to single-frequency networks (SFNs) has become a reality. SFN offers multiple advantages concerning MFN, such as more efficient management of the radioelectric spectrum, homogenizing the network parameters, and a potential SFN gain. However, the transition process can be cumbersome for operators due to the multiple measurement campaigns and required finetuning of the final SFN system to ensure the desired quality of service. To avoid time-consuming field measurements and reduce the costs associated with the SFN implementation, this paper aims to predict the performance of an SFN system from the legacy MFN and position data through machine learning (ML) algorithms. It is proposed a ML concatenated structure based on classification and regression to predict SFN electric-field strength, modulation error ratio, and gain. The model's training and test process are performed with a dataset from an SFN/MFN trial in Ghent, Belgium. Multiple algorithms have been tuned and compared to extract the data patterns and select the most accurate algorithms. The best performance to predict the SFN electric-field strength is obtained with a coefficient of determination (R2) of 0.93, modulation error ratio of 0.98, and SFN gain of 0.89 starting from MFN parameters and position data. The proposed method allows classifying the data points according to positive or negative SFN gain with an accuracy of 0.97

Debris Disks in NGC 2547

We have surveyed the 30 Myr-old cluster NGC 2547 for planetary debris disks using Spitzer. At 4.5-8 um we are sensitive to the photospheric level down to mid-M stars (0.2 Msol) and at 24 um to early-G stars (1.2 Msol). We find only two to four stars with excesses at 8 um out of ~400-500 cluster members, resulting in an excess fraction <~1 percent at this wavelength. By contrast, the excess fraction at 24 um is ~40 percent (for B-F types). Out of four late-type stars with excesses at 8 um two marginal ones are consistent with asteroid-like debris disks. Among stars with strong 8 um excesses one is possibly from a transitional disk, while another one can be a result of a catastrophic collision. Our survey demonstrates that the inner 0.1-1 AU parts of disks around solar-type stars clear out very thoroughly by 30 Myrs of age. Comparing with the much slower decay of excesses at 24 and 70 um, disks clear from the inside out, of order 10 Myr for the inner zones probed at 8 um compared with a hundred or more Myr for those probed with the two longer wavelengths.Comment: Accepted to ApJ, 29 pages, 13 figs. A Note in Proof concerning cluster's age was added in the original submission of 2007 July 19. Full Tables 1 and 2 in the electronic form together with the article with full resolution figures are available at http://www.astro.ufl.edu/~ngorlova/disksNGC2547

A Line Through the Sacred Lands of the Altai Mountains: Perspectives on the Altai Pipeline Project

In 2006 preliminary plans were made public showing that Gazprom intended to construct a pipeline through the Altai republic (Russia, south-west Siberia). Unfortunately, there was almost no attention to integrating the conservation of cultural heritage (both archaeological and landscape) into the planning of the pipeline, though the Altai is well-known for its rich cultural heritage. Hitherto, no assessment has been made of the potential impact of the project, nor did Gazprom release detailed information about the exact course of the route. The present article aims to illustrate the potential impact of the pipeline based on a detailed study of a small segment of the route, using remote sensing images and data gathered during fieldwork. This assessment underlines the need for a well-thought-out strategy, which is required if sustainable integration of heritage conservation into the construction plan is to be realized. If such a balance is not found, thousands of archaeological monuments could disappear, which would result in a huge cultural and scientific loss. As a possible solution, an integrative strategy founded on a desk-based study of remote sensing images and a well-directed field survey is suggested

Vista D2.1 Supporting Data for Business and Regulatory Scenarios Report

Vista examines the effects of conflicting market forces on European performance in ATM, through the evaluation of impact metrics on four key stakeholders, and the environment. The review of regulatory and business factors is presented. Vista will model the current and future (2035, 2050) framework based on the impact of regulatory and business factors. These factors are obtained from a literature review of regulations, projects and technological and operational changes. The current value of those factors and their possible evolution are captured in this deliverable

Spitzer 24 micron Survey of Debris Disks in the Pleiades

We performed a 24 micron 2 Deg X 1 Deg survey of the Pleiades cluster, using the MIPS instrument on Spitzer. Fifty four members ranging in spectral type from B8 to K6 show 24 micron fluxes consistent with bare photospheres. All Be stars show excesses attributed to free-free emission in their gaseous envelopes. Five early-type stars and four solar-type stars show excesses indicative of debris disks. We find a debris disk fraction of 25 % for B-A members and 10 % for F-K3 ones. These fractions appear intermediate between those for younger clusters and for the older field stars. They indicate a decay with age of the frequency of the dust-production events inside the planetary zone, with similar time scales for solar-mass stars as have been found previously for A-stars.Comment: accepted to Ap

Discovery of Reflection Nebulosity Around Five Vega-like Stars

Coronagraphic optical observations of six Vega-like stars reveal reflection nebulosities, five of which were previously unknown. The nebulosities illuminated by HD 4881, HD 23362, HD 23680, HD 26676, and HD 49662 resemble that of the Pleiades, indicating an interstellar origin for dust grains. The reflection nebulosity around HD 123160 has a double-arm morphology, but no disk-like feature is seen as close as 2.5 arcsec from the star in K-band adaptive optics data. We demonstrate that uniform density dust clouds surrounding HD 23362, HD 23680 and HD 123160 can account for the observed 12-100 micron spectral energy distributions. For HD 4881, HD 26676, and HD 49662 an additional emission source, such as from a circumstellar disk or non-equilibrium grain heating, is required to fit the 12-25 micron data. These results indicate that in some cases, particularly for Vega-like stars located beyond the Local Bubble (>100 pc), the dust responsible for excess thermal emission may originate from the interstellar medium rather than from a planetary debris system.Comment: The Astrophysical Journal, in press for March, 2002 (32 pages, 13 figures

Tycho 2 stars with infrared excess in the MSX Point Source Catalogue

Stars of all evolutionary phases have been found to have excess infrared emission due to the presence of circumstellar material. To identify such stars, we have positionally correlated the infrared MSX point source catalogue and the Tycho 2 optical catalogue. A near/mid infrared colour criteria has been developed to select infrared excess stars. The search yielded 1938 excess stars, over half (979) have never previously been detected by IRAS. The excess stars were found to be young objects such as Herbig Ae/Be and Be stars, and evolved objects such as OH/IR and carbon stars. A number of B type excess stars were also discovered whose infrared colours could not be readily explained by known catalogued objects.Comment: Added Comment: 16 pages, 9 figures, accepted for publication in MNRA

Efficient 3D trilateration algorithm for visible light positioning

© 2019 IOP Publishing Ltd. This letter presents an efficient algorithm for estimating the three-dimensional (3D) location of a photodiode (PD) receiver via visible light positioning. It solely works on measured powers from different light-emitting diode (LED) sources and does not require any prior knowledge of the PD receiver height. It is found that four LEDs are required that are not on the same circle, in order to unambiguously determine the 3D location. The algorithm is optimized towards a minimized calculation time in view of real-time operation on energy-constrained lightweight and mobile devices such as drones

A Phase II Basket Trial of Dual Anti-CTLA-4 and Anti-PD-1 Blockade in Rare Tumors (DART SWOG 1609) in Patients with Nonpancreatic Neuroendocrine Tumors.

PurposeImmune checkpoint blockade has improved outcomes across tumor types; little is known about the efficacy of these agents in rare tumors. We report the results of the (nonpancreatic) neuroendocrine neoplasm cohort of SWOG S1609 dual anti-CTLA-4 and anti-PD-1 blockade in rare tumors (DART).Patients and methodsWe performed a prospective, open-label, multicenter phase II clinical trial of ipilimumab plus nivolumab across multiple rare tumor cohorts, with the (nonpancreatic) neuroendocrine cohort reported here. Response assessment by grade was not prespecified. The primary endpoint was overall response rate [ORR; RECIST v1.1; complete response (CR) and partial response (PR)]; secondary endpoints included progression-free survival (PFS), overall survival (OS), stable disease &gt;6 months, and toxicity.ResultsThirty-two eligible patients received therapy; 18 (56%) had high-grade disease. Most common primary sites were gastrointestinal (47%; N = 15) and lung (19%; N = 6). The overall ORR was 25% [95% confidence interval (CI) 13-64%; CR, 3%, N = 1; PR, 22%, N = 7]. Patients with high-grade neuroendocrine carcinoma had an ORR of 44% (8/18 patients) versus 0% in low/intermediate grade tumors (0/14 patients; P = 0.004). The 6-month PFS was 31% (95% CI, 19%-52%); median OS was 11 months (95% CI, 6-∞). The most common toxicities were hypothyroidism (31%), fatigue (28%), and nausea (28%), with alanine aminotransferase elevation (9%) as the most common grade 3/4 immune-related adverse event, and no grade 5 events.ConclusionsIpilimumab plus nivolumab demonstrated a 44% ORR in patients with nonpancreatic high-grade neuroendocrine carcinoma, with 0% ORR in low/intermediate grade disease