Abstract Based on the two postulates of the invariance of both the laws of physics and light speed in inertial frames, Einstein revolutionised the prevalent conceptions of space and time in the Special Theory of Relativity, which is not however without difficulties, due to gaping holes in its philosophical foundations. The first postulate is an unjustified and clumsily drafted extension of Galilean Relativity, while the second postulate, if interpreted as meaning that the speed of light will not be altered by a moving frame, does not lead to Lorentz transformations, but just reveals that a light ray is not transported by a moving frame. Reference frames involving light propagation do not exhibit the equivalence inherent in inertial frames, and hence could be classified as seemingly-inertial, being some category of non-inertial frames. Either equivalence, including simultaneity in both moving and stationary frames, is a defining characteristic of inertial frames, or else if inertial frames allow inequivalence, then they are not indistinguishable, which is a contradiction. All along, the definitions of “frames of reference,” “inertial frames,” and “simultaneity” and the “legal” drafting of the two postulates play a crucial role in the development and consistency of the Theory, almost as much as the thought experiments and the mathematics.
J. T. A. Jong, G. V. Verdoes Kleijn, K. Kuijken
et al.
The Kilo Degree Survey (KiDS) is a 1500 square degree optical imaging survey with the recently commissioned OmegaCAM wide-field imager on the VLT Survey Telescope (VST). A suite of data products will be delivered to the European Southern Observatory (ESO) and the community by the KiDS survey team. Spread over Europe, the KiDS team uses Astro-WISE as its main tool to collaborate efficiently and pool hardware resources. In Astro-WISE the team shares, calibrates and archives all survey data. The data-centric architectural design realizes a dynamic ‘live archive’ in which new KiDS survey products of improved quality can be shared with the team and eventually the full astronomical community in a flexible and controllable manner.
Historicamente, as primeiras soluções da relatividade geral não foram reconhecidas como soluções de buracos negros. Elas foram, a princípio, idealizadas para descrever o campo gravitacional de objetos massivos esfericamente simétricos, como o Sol ou o elétron. Neste artigo, vamos apresentar as soluções de buracos negros em seu contexto histórico e mostrar como a nossa compreensão sobre o universo mudou à medida que desvendamos propriedades fundamentais sobre estes campos gravitacionais. O objetivo é apresentar uma introdução histórica sobre a relatividade geral e buracos negros, focada na teoria de gravitação e suas interpretações, como apoio didático para aqueles que pretendem iniciar os estudos sobre o tema.
BACKGROUND AND PURPOSE The Global Quality Assurance of Radiation Therapy Clinical Trials Harmonization Group (GHG) is a collaborative group of Radiation Therapy Quality Assurance (RTQA) Groups harmonizing and improving RTQA for multi-institutional clinical trials. The objective of the GHG OAR Working Group was to unify OAR contouring guidance across RTQA groups by compiling a single reference list of OARs in line with AAPM TG 263 and ASTRO, together with peer-reviewed, anatomically defined contouring guidance for integration into clinical trial protocols independent of the radiation therapy delivery technique. MATERIALS AND METHODS The GHG OAR multi-professional Working Group comprised of 22 members from 6 international RTQA Groups and affiliated organizations conducted the work in 3 stages: 1) Clinical trial documentation review and identification of structures of interest 2) Review of existing contouring guidance and survey of proposed OAR contouring guidance 3) Review of survey feedback with recommendations for contouring guidance with standardized OAR nomenclature. RESULTS 157 clinical trials were examined; 222 OAR structures were identified. Duplicates, non-anatomical, non-specific, structures with more specific alternative nomenclature, and structures identified by one RTQA group were excluded leaving 58 structures of interest. 6 OAR descriptions were accepted with no amendments, 41 required minor amendments, 6 major amendments, 20 developed as a result of feedback, and 5 structures excluded in response to feedback. The final GHG consensus guidance includes 73 OARs with peer-reviewed descriptions (appendix A). CONCLUSION We provide OAR descriptions with nomenclature for use in clinical trials. A more uniform dataset supports the delivery of clinically relevant and valid conclusions from clinical trials.
Uma das equações mais populares da física é a famosa fórmula da energia de repouso, E = mc2, deduzida por Albert Einstein no desenvolvimento da teoria da relatividade restrita. O artigo onde as ideias que dão origem a essa equação são discutidas por Einstein é apresentado aqui em uma tradução direta do alemão para o português.
We describe the method used by the multi-band template analysis (MBTA) pipeline to compute the probability of astrophysical origin, p astro, of compact binary coalescence candidates in LIGO–Virgo data from the third observing run (O3). The calculation is performed as part of the offline analysis and is used to characterize candidate events, along with their source classification. The technical details and the implementation are described, as well as the results from the first half of the third observing run (O3a) published in GWTC-2.1. The performance of the method is assessed on injections of simulated gravitational-wave signals in O3a data using a parameterization of p astro as a function of the MBTA combined ranking statistic. Possible sources of statistical and systematic uncertainties are discussed, and their effect on p astro quantified.
Social companion robots are getting more attention to assist elderly people to stay independent at home and to decrease their social isolation. When developing solutions, one remaining challenge is to design the right applications that are usable by elderly people. For this purpose, co-creation methodologies involving multiple stakeholders and a multidisciplinary researcher team (e.g., elderly people, medical professionals, and computer scientists such as roboticists or IoT engineers) are designed within the ACCRA (Agile Co-Creation of Robots for Ageing) project. This paper will address this research question: How can Internet of Robotic Things (IoRT) technology and co-creation methodologies help to design emotional-based robotic applications? This is supported by the ACCRA project that develops advanced social robots to support active and healthy ageing, co-created by various stakeholders such as ageing people and physicians. We demonstra this with three robots, Buddy, ASTRO, and RoboHon, used for daily life, mobility, and conversation. The three robots understand and convey emotions in real-time using the Internet of Things and Artificial Intelligence technologies (e.g., knowledge-based reasoning).
Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s-1 (ref. 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of ∼5 cm s-1 is necessary. The combination of a laser frequency comb with a Fabry–Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (∼1-Å) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or ‘astro-comb’, is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s-1 in astronomical radial velocity measurements.
Astronomical images are essential for exploring and understanding the universe. Optical telescopes capable of deep observations, such as the Hubble Space Telescope, are heavily oversubscribed in the Astronomical Community. Images also often contain additive noise, which makes de-noising a mandatory step in post-processing the data before further data analysis. In order to maximise the efficiency and information gain in the post-processing of astronomical imaging, we turn to machine learning. We propose Astro U-net, a convolutional neural network for image de-noising and enhancement. For a proof-of-concept, we use Hubble space telescope images from WFC3 instrument UVIS with F555W and F606W filters. Our network is able to produce images with noise characteristics as if they are obtained with twice the exposure time, and with minimum bias or information loss. From these images, we are able to recover 95.9% of stars with an average flux error of 2.26%. Furthermore the images have, on average, 1.63 times higher signal-to-noise ratio than the input noisy images, equivalent to the stacking of at least 3 input images, which means a significant reduction in the telescope time needed for future astronomical imaging campaigns.
Elwira Sienkiewicz, Michał Gąsiorowski, Ladislav Hamerlík
et al.
AbstractLakes located in the Polish and Slovak parts of the Tatra Mountains were included in the Tatra diatom database (POL_SLOV training set). The relationship between the diatoms and the water chemistry in the surface sediments of 33 lakes was the basis for the statistical and numerical techniques for quantitative pH reconstruction. The reconstruction of the past water pH was performed using the alpine (AL:PE) and POL_SLOV training sets to compare the reliability of the databases for the Tatra lakes. The results showed that the POL_SLOV training set had better statistical parameters (R2 higher by 0.16, RMSE and max. bias lower by 0.2 and 0.36, respectively) compared to the AL:PE training set. The better performance of the POL_SLOV training set is particularly visible in the case of Przedni Staw Polski where the curve of the inferred water pH shows an opposite trend for the period from the 1960s to 1990 compared to that based on the AL:PE dataset. The reliability of the inferred pH was confirmed by the comparison with current instrumental measurements.
Importance The 2014 publication of the Society of Surgical Oncology-American Society for Radiation Oncology (SSO-ASTRO) Consensus Guideline on Margins for Breast-Conserving Surgery recommended a negative margin definition of no ink on tumor. Adoption of this guideline would represent a major change in surgical practice that could lower the rates of reoperation. Objective To assess changes in reoperation rates after publication of the SSO-ASTRO guideline. Data Sources A systematic search of Embase, PREMEDLINE, Evidence-Based Medicine Reviews, Scopus, and Web of Science for biomedical literature published from January 2014 to July 2019 was performed. This search was supplemented by web searches and manual searching of conference abstracts. Study Selection Included studies compared the reoperation rates in preguideline vs postguideline cohorts (actual change), retrospectively applied the SSO-ASTRO guideline to a preguideline cohort (projected change), or described the economic outcomes of the guideline. Data Extraction and Synthesis Study characteristics and reoperation rates were extracted independently by 2 reviewers. Odds ratios (ORs) were pooled by random effects meta-analysis. Analyses were stratified by study setting (institutional or population) and preguideline accepted margins. The economic outcomes of the guideline were summarized narratively. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Main Outcomes and Measures Odds ratios for postguideline vs preguideline reoperation rates. Results From 1114 citations, 30 studies (with 599 016 participants) reported changes in reoperation rates. Studies included a median (range) of 487 (100-521 578) participants, and 20 studies were undertaken in the US, 6 in the UK, 3 in Canada, and 1 in Australia. Among 21 studies of actual changes, pooled ORs showed a statistically significant reduction in reoperation, with an OR lower in institution-based studies than in population-based studies (OR, 0.62 [95% CI, 0.52-0.74] vs 0.76 [95% CI, 0.72-0.80]; P = .04 for subgroup differences). Among 9 studies of projected changes, the pooled OR was lower for preguideline margin thresholds of 2 mm or more compared with 1 mm (OR, 0.47 [95% CI, 0.40-0.56] vs 0.85 [95% CI, 0.79-0.91; P < .001 for subgroup differences). Projected changes were likely to overestimate actual changes. Six studies that estimated the postguideline economic outcome found the guideline to be potentially cost saving, with a median (range) saving of US $3540 ($1800-$25 650) per woman avoiding reoperation. Conclusions and Relevance This study found a decrease in reoperation rates after the publication of the SSO-ASTRO guideline; this reduction was greater at an institutional level than a population level, the latter reflecting the differences in guideline adoption between centers. These early outcomes may be conservative estimates of longer-term implications.
Abstract The X-ray Imaging and Spectroscopy Mission (XRISM) is a recovery mission of ASTRO-H (Hitomi) launched in 2016. The Resolve instrument on the XRISM is an 6 × 6 array of silicon-thermistor microcalorimeters cooled down to 50 mK combined with a 5.6 m focal length X-ray telescope. Its design inherits that of the Soft X-ray Spectrometer (SXS) onboard ASTRO-H that demonstrated high resolution spectroscopy of the X-ray microcalorimeters by observing astronomical objects and providing superb resolution spectra. The cooling chain of the Resolve consists of a 3-stage adiabatic demagnetization refrigerator (ADR), a Joule-Thomson cooler, ~ 30 L superfluid helium, four Stirling coolers and a vacuum vessel or a dewar. Design of the Resolve cooling system is basically the same as that in the SXS but several changes are adopted based on lessons learned. This paper describes mainly the cooling system from room temperature to about 1 K providing the ADR heat sink. Major changes include an aperture baffle for micrometeoroid and orbital debris protection and optical light reduction, an eddy current damper to slow a gate valve opening, a new vibration isolation system with launch-locks.
Document clustering is generally the first step for topic identification. Since many clustering methods operate on the similarities between documents, it is important to build representations of these documents which keep their semantics as much as possible and are also suitable for efficient similarity calculation. As we describe in Koopman et al. (Proceedings of ISSI 2015 Istanbul: 15th International Society of Scientometrics and Informetrics Conference, Istanbul, Turkey, 29 June to 3 July, 2015. Bogaziçi University Printhouse. http://www.issi2015.org/files/downloads/all-papers/1042.pdf, 2015), the metadata of articles in the Astro dataset contribute to a semantic matrix, which uses a vector space to capture the semantics of entities derived from these articles and consequently supports the contextual exploration of these entities in LittleAriadne. However, this semantic matrix does not allow to calculate similarities between articles directly. In this paper, we will describe in detail how we build a semantic representation for an article from the entities that are associated with it. Base on such semantic representations of articles, we apply two standard clustering methods, K-Means and the Louvain community detection algorithm, which leads to our two clustering solutions labelled as OCLC-31 (standing for K-Means) and OCLC-Louvain (standing for Louvain). In this paper, we will give the implementation details and a basic comparison with other clustering solutions that are reported in this special issue.
Abstract We repeat our previous calculation of the spectrum distortion of massless neutrinos in the early universe with a considerably better accuracy and corrected for a missing numerical factor in one of the two ways of calculations presented in our paper [Nucl. Phys. B 503 (1997) 426]. Now both ways of calculations are in perfect agreement and we essentially reproduce our old results presented in the abstract of the paper and used in the calculations of light element abundances. We disagree with the criticism of our calculations presented in astro-ph/9712199 by N.Y. Gnedin and O.Y. Gnedin.