In September 2016, Stanford's"One Hundred Year Study on Artificial Intelligence"project (AI100) issued the first report of its planned long-term periodic assessment of artificial intelligence (AI) and its impact on society. It was written by a panel of 17 study authors, each of whom is deeply rooted in AI research, chaired by Peter Stone of the University of Texas at Austin. The report, entitled"Artificial Intelligence and Life in 2030,"examines eight domains of typical urban settings on which AI is likely to have impact over the coming years: transportation, home and service robots, healthcare, education, public safety and security, low-resource communities, employment and workplace, and entertainment. It aims to provide the general public with a scientifically and technologically accurate portrayal of the current state of AI and its potential and to help guide decisions in industry and governments, as well as to inform research and development in the field. The charge for this report was given to the panel by the AI100 Standing Committee, chaired by Barbara Grosz of Harvard University.
We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010 -- 2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated ($\sim 90 \%$) by electron and tau flavors. The flux, observed in the energy range from $16\,\mathrm{TeV} $ to $2.6\,\mathrm{PeV}$, is consistent with a single power-law as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be $\gamma=2.53\pm0.07$ and a flux normalization for each neutrino flavor of $\phi_{astro} = 1.66^{+0.25}_{-0.27}$ at $E_{0} = 100\, \mathrm{TeV}$. This flux of electron and tau neutrinos is in agreement with IceCube muon neutrino results and with all-neutrino flavor results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p-value $\ge 0.06$).
Galáxias são estruturas fundamentais no Universo. A descoberta da natureza extragaláctica das nebulosas espirais só ocorreu em meados dos anos 1920. Durante o século que se passou desde então, aprendemos muito sobre as galáxias. Este texto descreve como chegamos à conclusão de que o Universo é povoado de galáxias, muitas semelhantes à nossa própria, a Via Láctea. Veremos como classificamos as galáxias, quais são suas principais propriedades, como elas se formam e evoluem, e como estão distribuídas pelo Universo.
A experiência de dar aula em São Paulo no ano anterior à mudança para Nova York em 1998 foi fundamental para instigar a necessidade de trabalhar com um pseudônimo. Percebemos nas aulas na FAAP (1997-1998) que não só nós estávamos influenciando os alunos como eles também nos influenciavam. Começou a surgir ali, embrionária ainda, a ideia de “contaminação” que permeia nossa prática até hoje: contaminar e ser contaminado. Percebemos então que nunca estamos sozinhos e que a melhor forma de abraçar igualmente todas as pessoas envolvidas num projeto é usar um pseudônimo. Em 1997 criamos então nosso primeiro codinome – feito para um projeto específico de cartões-postais “falsos” da cidade de São Paulo (que eram inseridos clandestinamente em bancas de jornal da cidade e vendidos como cartões turísticos comuns): Diamantino. A ideia principal para a utilização do pseudônimo nesse projeto era que esses cartões-postais não fossem percebidos como “arte”.
We present the third open gravitational-wave catalog (3-OGC) of compact-binary coalescences, based on the analysis of the public LIGO and Virgo data from 2015 through 2019 (O1, O2, O3a). Our updated catalog includes a population of 57 observations, including 4 binary black hole mergers that had not been previously reported. This consists of 55 binary black hole mergers and the 2 binary neutron star mergers, GW170817 and GW190425. We find no additional significant binary neutron star or neutron star–black hole merger events. The most confident new detection is the binary black hole merger GW190925_232845, which was observed by the LIGO–Hanford and Virgo observatories with astro>0.99; its primary and secondary component masses are 20.2−2.5+3.9M⊙ and 15.6−2.6+2.1M⊙ , respectively. We estimate the parameters of all binary black hole events using an up-to-date waveform model that includes both subdominant harmonics and precession effects. To enable deep follow up as our understanding of the underlying populations evolves, we make available our comprehensive catalog of events, including the subthreshold population of candidates, and the posterior samples of our source parameter estimates.
The aim of this review is to provide a comprehensive overview of the role of intraoperative radiation therapy with electrons (IOERT) in breast conserving therapy (BCT), both as partial breast irradiation (PBI) as well as anticipated boost ("IOERT-Boost"). For both applications, the criteria for patient selection, technical details/requirements, physical aspects and outcome data are presented. IOERT as PBI The largest evidence comes from Italian studies, especially the ELIOT randomized trial. Investigators showed that the rate of in-breast relapses (IBR) in the IOERT group was significantly greater than with whole breast irradiation (WBI), even when within the pre-specified equivalence margin. Tumour sizes > 2 cm, involved axillary nodes, Grade 3 and triple negative molecular subtypes emerged as statistically significant predictors of IBR. For patients at low risk for in-breast recurrence (ASTRO/ESTRO recommendations), full dose IOERT was isoeffective with standard WBI. Hence, several national guidelines now include this treatment strategy as one of the standard techniques for PBI in carefully selected patients. IOERT Boost The largest evidence for boost IOERT preceding WBI comes from pooled analyses performed by the European Group of the International Society of Intraoperative Radiation Therapy (ISIORT Europe), where single boost doses (mostly around 10 Gy) preceded whole-breast irradiation (WBI) with 50 Gy (conventional fractionation). At median follow-up periods up to ten years, local recurrence rates around 1% were observed for low risk tumours. Higher local relapse rates were described for grade 3 tumours, triple negative breast cancer as well as for patients treated after primary systemic therapy for locally advanced tumours. Even in this settings, long-term (> 5y) local tumour control rates beyond 95% were achieved. These encouraging results are interpreted as being attributable to utmost precision in dose delivery (by avoiding a "geographic and/or temporal miss"), and the possible radiobiological superiority of a single high dose fraction, compared to the conventionally fractionated boost. IOERT also showed favourable results in terms of cosmetic outcome, assumedly thanks to the small treated volumes combined with complete skin sparing.
Increasing antibiotic resistance in bacteria that cause zoonotic infections is a major problem for farmers rearing animals for food as well as for consumers who eat the contaminated meat resulting in food-borne infections. Bacteriophages incorporated in animal feed may help reduce carriage and infections in animals including chickens and pigs. There are, however, unmet challenges in protecting phages from processing stresses e.g., during animal feed pelleting operations and during transit of phages through the acidic gastric environment. Core-shell capsules were produced using a concentric nozzle and commercially available encapsulation equipment to fabricate capsules with phages formulated in an oil-in-water microemulsion in the core. pH-responsive capsules released the encapsulated phage cargo within 10–30 min triggered by changes in local environmental pH typically found in the lower gastrointestinal (GI) tract of animals. Acid stability of phages exposed to pH values as low as pH 1 was demonstrated. Encapsulated phages were able to withstand exposure to 95 °C wet heat thermal stress for up to 120 s, conditions typically encountered during feed pellet extrusion processing. Free phages were inactivated within 15 s under these conditions. The present study demonstrates that encapsulation of bacteriophages in core-shell pH-responsive capsules with water-in-oil emulsified phages in the core significantly improves phage viability upon exposure to processing and environmental stresses that require consideration during production of animal feed and application in animals for biocontrol. The results from this study should help guide future development of phage formulations suitable for use in animal feed for animal biocontrol applications.
Interstellar signals might be intermittent for many reasons, such as targeted sequential transmissions, or isotropic broadcasts that are not on continuously, or many other reasons. The time interval between such signals would be important, because searchers would need to observe for long enough to achieve an initial detection and possibly determine a period. This article suggests that: (1) the power requirements of interstellar transmissions could be reduced by orders of magnitude by strategies that would result in intermittent signals, and (2) planetary rotation might constrain some transmissions to be intermittent and in some cases to have the period of the source planet, and (3) signals constrained by planetary rotation might often have a cadence in the range of 10-25 hours, if the majority of planets in our solar system are taken as a guide. Extended observations might be needed to detect intermittent signals and are rarely used in SETI but are feasible, and seem appropriate when observing large concentrations of stars or following up on good candidate signals.
In this work we derive the minimum allowed orbital periods of H-rich bodies ranging in mass from Saturn's mass to 1 $M_{\odot}$, emphasizing gas giants and brown dwarfs over the range $0.0003 - 0.074 \, M_\odot$. Analytic fitting formulae for $P_{\rm min}$ as a function of the mass of the body and as a function of the mean density are presented. We assume that the density of the host star is sufficiently high so as not to limit the minimum period. In many instances this implies that the host star is a white dwarf. This work is aimed, in part, toward distinguishing brown dwarfs from planets that are found transiting the host white dwarf without recourse to near infrared or radial velocity measurements. In particular, orbital periods of $\lesssim 100$ minutes are very likely to be brown dwarfs. The overall minimum period over this entire mass range is $\simeq 37$ minutes.
Brett M. Morris, H. Jens Hoeijmakers, Daniel Kitzmann
et al.
We present a method for detecting starspots on cool stars using the cross-correlation function (CCF) of high resolution molecular spectral templates applied to archival high-resolution spectra of G and K stars observed with HARPS/HARPS-N. We report non-detections of starspots on the Sun even when the Sun was spotted, the solar twin 18 Scorpii, and the very spotted Sun-like star HAT-P-11, suggesting that Sun-like starspot distributions will be invisible to the CCF technique, and should not produce molecular absorption signals which might be confused for signatures of exoplanet atmospheres. We detect strong TiO absorption in the T Tauri K-dwarfs LkCa 4 and AA Tau, consistent with significant coverage by cool regions. We show that despite the non-detections, the technique is sensitive to relatively small spot coverages on M dwarfs and large starspot areas on Sun-like stars.
Clemence Fontanive, Luigi R. Bedin, Daniella C. Bardalez Gagliuffi
In this paper we present our project that aims at determining accurate distances and proper motions for the Y brown dwarf population using the Hubble Space Telescope. We validate the program with our first results, using a single new epoch of observations of the Y0pec dwarf WISE J163940.83$-$684738.6. These new data allowed us to refine its proper motion and improve the accuracy of its parallax by a factor of three compared to previous determinations, now constrained to $\varpi = 211.11 \pm 0.56$ mas. This newly derived absolute parallax corresponds to a distance of $4.737 \pm 0.013$ pc, an exquisite and unprecedented precision for faint ultracool Y dwarfs.
A method for the rapid estimation of transfer costs for the removal of debris in low Earth orbit is proposed. Debris objects among a population with similar inclination values are considered. The proposed approximate analysis can provide estimations of actual Deltav between any debris object pair as a function of time; these estimations allow for the rapid evaluation of the costs of large sequences of targets to be removed. The effect of Earth's oblateness perturbation (J2) is exploited to reduce transfer costs. The debris removal problem of the 9th edition of the Global Trajectory Optimization Competition is used to evaluate the estimation accuracy; Deltav estimations of the transfers between objects pairs are verified by comparing them with the GTOC9 solution proposed by the winning team from JPL. The comparison of the results demonstrates the very good accuracy of the simple approximation. Key words: Space debris; approximation; trajectory optimization; J2 perturbation
AU Mic is a young, very active M dwarf star with a debris disk and at least one transiting Neptune-size planet. Here we present detailed analysis of the magnetic field of AU Mic based on previously unpublished high-resolution optical and near-infrared spectropolarimetric observations. We report a systematic detection of circular and linear polarization signatures in the stellar photospheric lines. Tentative Zeeman Doppler imaging modeling of the former data suggests a non-axisymmetric global field with a surface-averaged strength of about 90 G. At the same time, linear polarization observations indicate the presence of a much stronger $\approx$2 kG axisymmetric dipolar field, which contributes no circular polarization signal due to the equator-on orientation of AU Mic. A separate Zeeman broadening and intensification analysis allowed us to determine a mean field modulus of 2.3 and 2.1 kG from the Y- and K-band atomic lines respectively. These magnetic field measurements are essential for understanding environmental conditions within the AU Mic planetary system.
Phillip A. Coles, Sergei N. Yurchenko, Jonathan Tennyson
A new hot line list for $^{14}$NH$_3$ is presented. The line list CoYuTe was constructed using an accurate, empirically refined potential energy surface and a CCSD(T)/aug-cc-pVQZ ab initio dipole moment surface of ammonia, previously reported. The line list is an improvement of the ammonia line list BYTe [Yurchenko et al., Mon. Not. R. Astron. Soc., 413, 1828 (2011)]. The CoYuTe line list covers wavenumbers up to 20000 cm$^{-1}$, i.e. wavelengths beyond 0.5 $μ$m for temperatures up to 1500 K. Comparisons with the high temperature experimental data from the literature show excellent agrement for wavenumbers below 6000 cm$^{-1}$. The CoYuTe line list contains 16.9 billion transitions and is available from the ExoMol website (www.exomol.com) and the CDS database.
Discs of gas and dust surrounding young stars are the birthplace of planets. However, direct detection of protoplanets forming within discs has proved elusive to date. We present the detection of a large, localized deviation from Keplerian velocity in the protoplanetary disc surrounding the young star HD163296. The observed velocity pattern is consistent with the dynamical effect of a two Jupiter-mass planet orbiting at a radius $\approx$ 260au from the star.
The possibility that the chemical composition of the solar atmosphere has been affected by radiative dust cleansing of late and weak accretion flows by the proto-sun itself, is explored. Estimates, using semi-analytical methods and numerical simulations of the motion of dust grains in a collapsing non-magnetic and non-rotating gas sphere with a central light source are made, to model possible dust-cleansing effects. Our calculations indicate that the amounts of cleansed material may well be consistent with the abundance differences observed for the Sun when compared with solar-like stars and with the relations found between these differences and condensation temperature of the element. It seems quite possible that the proposed mechanism might have produced the significant abundance effects observed for the Sun, provided that late and relatively weak accretion did occur. The effects of cleansing may, however, be affected by outflows from the Sun, the existence and dynamics of magnetic fields and of the accretion disk, and the possible presence and location of the Early Sun in a rich stellar cluster.
We study the hydrodynamical stability of the laminar flows associated with warped astrophysical discs using numerical simulations of warped shearing boxes. We recover linear growth rates reported previously due to a parametric resonance of inertial waves, and show that the nonlinear saturated state can significantly reduce the laminar flows, meaning that the warp would evolve on much longer time scales than would be concluded from the internal torques due to these laminar flows. Towards larger warp amplitudes, we find first of all a reversal of angular momentum flux, indicating that the mass distribution would evolve in an anti-diffusive manner, and second that the linear growth rates disappear, possibly because of the very strong shear in the laminar flows in this regime. For discs with small enough viscosity, a nonlinear state can still be found when linear growth rates are absent by introducing a large enough perturbation, either by starting from a nonlinear state obtained at smaller warp amplitude, or by starting from a state with no laminar flows.