The standard model of particle physics describes matter and antimatter as coming from the same fields and this fact has been confirmed experimentally. It is then curious that the observable universe is made of matter and not antimatter. We will first discuss the evidence that we live in a matter-dominated (or matter-antimatter asymmetric) Universe and then proceed to discuss if this can be explained according to our current understanding of the cosmology and particle physics. We will argue that an important process known as baryogenesis to generate a cosmic matter-antimatter asymmetry had to occur before the Universe was a few second old. Then, we will discuss the necessary ingredients for a successful baryogenesis and point out that the current model contains all the ingredients but not in a sufficient amount. Finally, we will discuss possible extensions to the current model which allow successful baryogenesis and how they can be tested experimentally. Interestingly, they might also be connected to other open puzzles in the fundamental physics, like the tiny neutrino mass.
Se presenta una introducción a los fundamentos de la Relatividad General y la noción de Agujeros Negros de una manera elemental, asumiendo conocimientos básicos de Física, y relegando a notas al pie de página aquellas acotaciones técnicas que requieran mayores conocimientos. Se da además una breve introdución histórica del concepto de agujero negro, y se mencionan los notables avances recientes en el campo experimental: la detección en 2015 de ondas gravitacionales en LIGO y las imágenes obtenidas por el Event Horizon Telescope.
Com observações cuidadosas e sistemáticas do céu, há muito tempo o ser humano vem construindo e refinando o seu conhecimento a respeito do Universo e de si mesmo. As grandezas observacionais sobre as quais repousa a astronomia estão sendo, finalmente, abundantemente medidas e com precisões inimagináveis graças à Missão Espacial Gaia da Agência Espacial Europeia. Com seus três data releases (2016, 2018 e 2020/22), temos, hoje, em nossas mãos, dados observacionais em quantidade e com qualidade com as quais até bem pouco tempo nem sonhávamos. Entre eles, a grandeza mais importante de toda a astronomia: a distância de mais de um 1,5 bilhão de estrelas que nos permite dizer onde se encontram, como são e como ''dançam'', iniciando assim, uma nova era no estudo da Galáxia e do Universo. Esses dados, disponibilizados para o mundo todo ao mesmo tempo, representam uma alteração radical na base do conhecimento astronômico e impactam tremendamente a astronomia no sentido mais amplo do termo, por muitos e muitos anos. Colegas de todas as partes do mundo estão mergulhados nesse oceano de posições, movimentos, brilhos, cores, etc, confirmando, revendo e refinando o que sabemos e prestes a enfrentarem, uma vez mais na história, o novo.
Aim/Objectives/Background: The goal of therapy with unsealed radiopharmaceutical sources is to provide either cure or significant prolongation of disease-specific survival, and effective reduction and/or prevention of adverse disease-related symptoms or untoward events while minimizing treatment-associated side effects and complications. Radium-223 dichloride (radium-223) is an alpha particle–emitting isotope used for targeted bone therapy. This practice parameter is intended to guide appropriately trained and licensed physicians performing therapy with radium-223. Such therapy requires close cooperation and communication between the physicians who are responsible for the clinical management of the patient and those who administer radiopharmaceutical therapy and manage the attendant side effects. Adherence to this parameter should help to maximize the efficacious use of radium-223, maintain safe conditions, and ensure compliance with applicable regulations. Methods: This practice parameter was developed according to the process described on the American College of Radiology (ACR) website (“The Process for Developing ACR Practice Parameters and Technical Standards,” www.acr.org/ClinicalResources/Practice-Parameters-and-Technical-Standards) by the Committee on Practice Parameters of the ACR Commission on Radiation Oncology in collaboration with the American College of Nuclear Medicine (ACNM), the American Society for Radiation Oncology (ASTRO), and the Society of Nuclear Medicine and Molecular Imaging (SNMMI). All these societies contributed to the development of the practice parameter and approved the final document. Results: This practice parameter addresses the many factors which contribute to appropriate, safe, and effective clinical use of radium-223. Topics addressed include qualifications and responsibilities of personnel, specifications of patient examination and treatment; documentation, radiation safety, quality control/improvement, infection control, and patient education. Conclusions: This practice parameter is intended as a tool to guide clinical use of radium-223 with the goal of facilitating safe and effective medical care based on current knowledge, available resources and patient needs. The sole purpose of this document is to assist practitioners in achieving this objective.
Observations from the Juno and Cassini missions provide essential constraints on the internal structures and compositions of Jupiter and Saturn, resulting in profound revisions of our understanding of the interior and atmospheres of Gas Giant planets. The next step to understand planetary origins in our Solar System requires a mission to their Ice Giant siblings, Uranus and Neptune.
Li is the very element that presents deep insights yet many problems to astrophysics. In this proceeding manuscript I first introduce a stellar solution to the cosmological Li problem, which reveals that Li was first destroyed and re-accumulated by these stars shortly after they were born, then discuss Li in the interstellar medium in the form of the molecule LiH, and the different Li enrichment histories seen in the Galactic thick and thin discs with data from the Gaia-ESO survey.
Polycyclic aromatic hydrocarbons (PAHs) are key species in astrophysical environments in which vacuum ultraviolet (VUV) photons are present, such as star-forming regions. The interaction with these VUV photons governs the physical and chemical evolution of PAHs. Models show that only large species can survive. However, the actual molecular properties of large PAHs are poorly characterized and the ones included in models are only an extrapolation of the properties of small and medium-sized species. We discuss here experiments performed on trapped ions including some at the SOLEIL VUV beam line DESIRS. We focus on the case of the large dicoronylene cation, C48H20+ , and compare its behavior under VUV processing with that of smaller species. We suggest that C2 H2 is not a relevant channel in the fragmentation of large PAHs. Ionization is found to largely dominate fragmentation. In addition, we report evidence for a hydrogen dissociation channel through excited electronic states. Although this channel is minor, it is already effective below 13.6 eV and can significantly influence the stability of astro-PAHs. We emphasize that the competition between ionization and dissociation in large PAHs should be further evaluated for their use in astrophysical models.
Adaptive Sampling Trust-Region Optimization (ASTRO) is a class of derivative-based stochastic trust-region algorithms developed to solve stochastic unconstrained optimization problems where the objective function and its gradient are observable only through a noisy oracle or using a large dataset. ASTRO incorporates adaptively sampled function and gradient estimates within a trust-region framework to generate iterates that are guaranteed to converge almost surely to a first-order or a second-order critical point of the objective function. Efficiency in ASTRO stems from two key aspects: (i) adaptive sampling to ensure that the objective function and its gradient are sampled only to the extent needed, so that small sample sizes result when iterates are far from a critical point and large sample sizes result when iterates are near a critical point; and (ii) quasi-Newton Hessian updates using BFGS. We describe ASTRO in detail, give a sense of its theoretical guarantees, and report extensive numerical results.
A review of some of the papers that discuss the relevance of the temperature structure present in H II regions and planetary nebulae is presented. Particular attention is given to the determination of the chemical abundances of these objects.
Abstract. The Soft X-ray Imager (SXI) is an imaging spectrometer using charge-coupled devices (CCDs) aboard the Hitomi x-ray observatory. The SXI sensor has four CCDs with an imaging area size of 31 mm×31 mm arranged in a 2×2 array. Combined with the x-ray mirror, the Soft X-ray Telescope, the SXI detects x-rays between 0.4 and 12 keV and covers a 38′×38′ field of view. The CCDs are P-channel fully depleted, back-illumination type with a depletion layer thickness of 200 μm. Low operation temperature down to −120°C as well as charge injection is employed to reduce the charge transfer inefficiency (CTI) of the CCDs. The functionality and performance of the SXI are verified in on-ground tests. The energy resolution measured is 161 to 170 eV in full width at half maximum for 5.9-keV x-rays. In the tests, we found that the CTI of some regions is significantly higher. A method is developed to properly treat the position-dependent CTI. Another problem we found is pinholes in the Al coating on the incident surface of the CCDs for optical light blocking. The Al thickness of the contamination blocking filter is increased to sufficiently block optical light.
In June 2017, the board of directors of the American Society of Radiation Oncology (ASTRO) revised and updated the organization’s strategic plan. The directors reiterated that the core purpose of the organization is to advance the field of radiation oncology, and the overarching vision is that the field should be a recognized leader in quality, innovation, and value in multidisciplinary cancer care. The strategic plan would be operationalized through 4 major areas of focus, the first of which was to “elevate the profile of the field” for the purpose of establishing radiation oncology as an equal partner in the field of cancer. One barometer of public exposure of the field of radiation oncology is the depth of penetration into social media, defined as tools for electronic communication. The aspirational goals of a national medical conference are to provide education, networking opportunities, and access to the latest technology for improving patient care. Professional medical societies have begun to explore how best to incorporate social media to augment these missions, and metrics of social media activity related to a society’s meetings might provide insights into the quantity of communications connecting attendees and other interested stakeholders in the general public. In the present report, we offer preliminary subjective and objective observations about the extent of the social media activity generated in association with the 2017 Annual Meeting of ASTRO and compare findings with prior ASTRO Annual Meetings and with the activity generated by selected other annual medical conferences.
The rise of the Internet of Things (IoT) and the recent focus on a gamut of 'Smart City' initiatives world-wide have pushed for new advances in data stream systems to (1) support complex analytics and evolving graph applications as continuous queries, and (2) deliver fast and scalable processing on large data streams. Unfortunately current continuous query languages (CQL) lack the features and constructs needed to support the more advanced applications. For example recursive queries are now part of SQL, Datalog, and other query languages, but they are not supported by most CQLs, a fact that caused a significant loss of expressive power, which is further aggravated by the limitation that only non-blocking queries can be supported. To overcome these limitations we have developed an a dvanced st ream r easo ning system ASTRO that builds on recent advances in supporting aggregates in recursive queries. In this demo, we will briefly elucidate the formal Streamlog semantics, which combined with the Pre-Mappability (PreM) concept, allows the declarative specification of many complex continuous queries, which are then efficiently executed in real-time by the portable ASTRO architecture. Using different case studies, we demonstrate (i) the ease-of-use, (ii) the expressive power and (iii) the robustness of our system, as compared to other state-of-the-art declarative CQL systems.
Nishant K. Singh, Harsha Raichur, Maarit J. Käpylä
et al.
Recent numerical work in helioseismology has shown that a periodically varying subsurface magnetic field leads to a fanning of the $f$-mode, which emerges from the density jump at the surface. In an attempt to model a more realistic situation, we now modulate this periodic variation with an envelope, giving thus more emphasis on localized bipolar magnetic structures in the middle of the domain. Some notable findings are: (i) compared to the purely hydrodynamic case, the strength of the $f$-mode is significantly larger at high horizontal wavenumbers $k$, but the fanning is weaker for the localized subsurface magnetic field concentrations investigated here than the periodic ones studied earlier; (ii) when the strength of the magnetic field is enhanced at a fixed depth below the surface, the fanning of the $f$-mode in the $kω$ diagram increases proportionally in such a way that the normalized $f$-mode strengths remain nearly the same in different such cases; (iii) the unstable Bloch modes reported previously in case of harmonically varying magnetic fields are now completely absent when more realistic localized magnetic field concentrations are imposed beneath the surface, thus suggesting that the Bloch modes are unlikely to be supported during most phases of the solar cycle; (iv) the $f$-mode strength appears to depend also on the depth of magnetic field concentrations such that it shows a relative decrement when the maximum of the magnetic field is moved to a deeper layer. We argue that detections of $f$-mode perturbations such as those being explored here could be effective tracers of solar magnetic fields below the photosphere before these are directly detectable as visible manifestations in terms of active regions or sunspots.
The raw BRITE photometry is affected by the presence of many outliers and instrumental effects. We present and discuss possible ways to correct the photometry for instrumental effects. Special attention is paid to the procedure of decorrelation which enables removal of most of the instrumental effects and considerably improves the quality of the final photometry.
The BDB, Binary star DataBase http://bdb.inasan.ru combines data of the catalogues of binary and multiple stars of all observational types. There is a number of ways for variable stars to form or to be a part of binary or multiple systems. We describe how such stars are represented in the database.