Array programming provides a powerful, compact and expressive syntax for accessing, manipulating and operating on data in vectors, matrices and higher-dimensional arrays. NumPy is the primary array programming library for the Python language. It has an essential role in research analysis pipelines in fields as diverse as physics, chemistry, astronomy, geoscience, biology, psychology, materials science, engineering, finance and economics. For example, in astronomy, NumPy was an important part of the software stack used in the discovery of gravitational waves1 and in the first imaging of a black hole2. Here we review how a few fundamental array concepts lead to a simple and powerful programming paradigm for organizing, exploring and analysing scientific data. NumPy is the foundation upon which the scientific Python ecosystem is constructed. It is so pervasive that several projects, targeting audiences with specialized needs, have developed their own NumPy-like interfaces and array objects. Owing to its central position in the ecosystem, NumPy increasingly acts as an interoperability layer between such array computation libraries and, together with its application programming interface (API), provides a flexible framework to support the next decade of scientific and industrial analysis. NumPy is the primary array programming library for Python; here its fundamental concepts are reviewed and its evolution into a flexible interoperability layer between increasingly specialized computational libraries is discussed.
The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra.
Context. Quasi-periodic density structures (PDSs) are quasiperiodic variations in the solar wind density that range from a few minutes to a few hours. They are trains of advected density structures with radial length scales LR ≈ 100 − 10 000 Mm, and they thus belong to the class of so-called mesoscale structures in the solar wind. Although the precise mechanisms that form PDSs are still debated, cumulative evidence from multiple studies using in situ and remote data supports the view that most PDSs have a solar origin and do not form through dynamics during their propagation in interplanetary space. Low-frequency (< 1 mHz) PDSs have been associated with small-scale flux ropes, which further indicates a solar origin.
Aims. We further investigated the origin and properties of PDSs by searching for coherent small-scale helical structures and flux ropes within PDS intervals.
Methods. We used an extensive list of PDSs, compiled from Solar Orbiter measurements, and we applied a wavelet analysis technique to obtain the reduced magnetic helicity, cross helicity, and residual energy.
Results. Our results indicate that small flux ropes are a constituent of PDS events, while the occurrence probability of helical Alfvénic structures is similar within and outside the PDSs.
Conclusions. These results are consistent with the scenario in which PDSs are formed by processes involving magnetic reconnection.
The core component to ensure the refined and safe operation of distribution network scheduling is 10 kV bus load probabilistic prediction. However, existing probabilistic prediction methods suffer from insufficient dynamic feature extraction and compromised prediction reliability caused by quantile crossing. To address these issues, this paper proposes a 10 kV bus load probabilistic prediction method integrating multi-value quantile regression (MQR) and a temporal fusion ensemble learning model (ELM). Firstly, a temporal fusion ensemble learning model is constructed, which integrates multiple temporal fusion network (TFN) sub-models through a stacking framework to parallel extract multi-dimensional temporal features of loads, effectively enhancing its feature capture capability for complex load data. Secondly, MQR is introduced as the core objective function to synchronously generate multi-quantile load forecasting results, comprehensively depicting the load probability distribution. Finally, a Listwise Maximum Likelihood Estimation (ListMLE) ranking constraint mechanism is embedded, which optimizes quantile ordering through monotonicity constraints, significantly reducing the degree of quantile crossing and improving the interpretability of forecasting results. The results show that the MQR-ELM algorithm achieves a Prediction Interval Coverage Probability of 94.624% (close to the nominal coverage rate of 95%), a Prediction Interval Averaged Width of 588.526, a Crossing Degree Index of only 0.0476, and a Continuous Ranked Probability Score as low as 84.931. All core indicators are significantly superior to those of the comparative algorithms.
We present JWST NIRCam observations of the emerging young star clusters (eYSCs) detected in the nearby spiral galaxy M83. The NIRcam mosaic encompasses the nuclear starburst, the bar, and the inner spiral arms. The eYSCs, detected in Pa α and Br α maps, have been largely missed in previous optical campaigns of young star clusters (YSCs). We distinguish between eYSCI, if they also have compact 3.3 μ m polycyclic aromatic hydrocarbon (PAH) emission associated with them, and eYSCII, if they only appear as compact Pa α emitters. We find that the variations in the 3.3 μ m PAH feature are consistent with an evolutionary sequence where eYSCI evolve into eYSCII and then optical YSCs. This sequence is clear in the F300M−F335M (tracing the excess in the 3.3 μ m PAH feature) and the F115W−F187N (tracing the excess in Pa α ) colors, which become increasingly bluer as clusters emerge. The central starburst stands out as the region where the most massive eYSCs are currently forming in the galaxy. We estimate that only about 20% of eYSCs will remain detectable as compact YSCs. Combining eYSCs and YSCs (≤10 Myr), we recover an average clearing timescale of 6 Myr in which clusters transition from embedded to fully exposed. We see evidence of shorter emergence timescales (∼5 Myr) for more massive (>5 × 10 ^3 M _⊙ ) clusters, while star clusters of ∼10 ^3 M _⊙ about 7 Myr. We estimate that eYSCs remain associated with the 3.3 μ m PAH emission for 3–4 Myr. Larger samples of eYSC and YSC populations will provide stronger statistics to further test environmental and cluster mass dependencies on the emergence timescale.
The evolution of the velocity distribution of pickup ions is crucial for understanding the energetic neutral atom (ENA) fluxes observed by Interstellar Boundary Explorer. Pickup ions in the heliosheath contain two main components: those transmitted across the heliospheric termination shock and those locally created within the heliosheath. In this work, we discuss the velocity distribution of the latter locally created component. We find that pickup ions created by the charge exchange of neutral solar wind (NSW) may be a significant source of the observed ENA fluxes between about 100 eV and 1 keV. Moreover, newborn pickup ions can maintain highly anisotropic velocity distribution in the heliosheath. This is because the kinetic instabilities are weak after the solar wind flow decelerates at the termination shock. Hybrid kinetic simulations show the mirror instability to be the dominant mode for conditions in the heliosheath close to the termination shock. We estimate that effects of NSW and anisotropy may enhance the expected phase space density of newborn pickup ions by more than a factor of 100.
Abstract Sabkha environments are a prevalent topographic feature in arid coastal areas. Along the Arabian Gulf, sabkhas overlie substantial hydrocarbon reservoirs and exhibit intricate lithological characteristics and an extremely shallow water table. These factors contribute to elevated seismic velocities and signal distortion. Static correction, a crucial initial step in seismic reflection processing, is employed to mitigate the impact of shallow surface layers. In this study, we investigate the variations in seismic properties along the uppermost part of mature and developing sabkhas. We employed high‐resolution seismic experiments with geophone spacing of 10 cm to explore the upper tens of centimeters. Conventional surveys with a 2 m spacing complement this approach to investigate deeper layers. Both sabkhas exhibit a unique characteristic of a partially saturated zone, which affects the seismic velocity, leading to lower velocities and consequently influencing the accuracy of the static correction. The high‐resolution surveys demonstrated superior accuracy to conventional approaches in determining the top of the partial saturation zone and hardground layer, hence resulting in a more reliable velocity delineation. Moreover, velocities derived from conventional, replacement, and tomogram approaches resulted in unreliable static corrections in mature coastal sabkha compared with developing inland sabkha, attributed to the considerable geological complexity that is characteristic of mature coastal sabkha environments. Carrying out a high‐resolution seismic survey in sabkha environments is therefore necessary to mitigate near‐surface velocity effects.
The propagation of interplanetary shocks, particularly those driven by coronal mass ejections (CMEs), is still an outstanding question in heliophysics and space weather forecasting. Here, we address the effects of the ambient solar wind on the propagation of two similar CME-driven shocks from the Sun to Earth. The two shock events (CME03, 2010 April 3; CME12, 2012 July 12) have the following properties. Both events (1) were driven by a halo CME (i.e., the source location is near the Sun–Earth line); (2) had a CME source in the southern hemisphere; (3) had a similar transit time (∼2 days) to Earth; (4) occurred in a nonquiet solar period; and (5) led to a severe geomagnetic storm. The initial (near the Sun) propagation speed, as measured by coronagraph images, was slower (by ∼300 km s ^−1 ) for CME03 than CME12, but it took about the same amount of traveling time for both events to reach Earth. According to the in situ solar wind observations from the Wind spacecraft, the CME03-driven shock was associated with a faster solar wind upstream of the shock than the CME12-driven shock. This is also demonstrated in our global MHD simulations. Analysis of our simulation result indicates that the drag force indirectly plays an important role in the shock propagation. The present study suggests that in addition to the initial CME propagation speed near the Sun, the shock speed (in the inertial frame) and the ambient solar wind conditions—in particular, the solar wind speed—are key to timing the arrival of CME-driven shock events.
Karol Horodecki, Jingfang Zhou, Maciej Stankiewicz
et al.
Quantum contextuality is one of the most recognized resources in quantum communication and computing scenarios. We provide a new quantifier of this resource, the rank of contextuality (RC). We define RC as the minimum number of non-contextual behaviors that are needed to simulate a contextual behavior. We show that the logarithm of RC is a natural contextuality measure satisfying several properties considered in the spirit of the resource-theoretic approach. The properties include faithfulness, monotonicity, and additivity under tensor product. We also give examples of how to construct contextual behaviors with an arbitrary value of RC exhibiting a natural connection between this quantifier and the arboricity of an underlying hypergraph. We also discuss exemplary areas of research in which the new measure appears as a natural quantifier.
It is well known that deep learning (DNN) has strong limitations due to a lack of explainability and weak defense against possible adversarial attacks. These attacks would be a concern for autonomous teams producing a state of high entropy for the team’s structure. In our first article for this Special Issue, we propose a <i>meta-learning/DNN</i> → <i>kNN</i> architecture that overcomes these limitations by integrating deep learning with explainable nearest neighbor learning (kNN). This architecture is named “shaped charge”. The focus of the current article is the empirical validation of “shaped charge”. We evaluate the proposed architecture for summarization, question answering, and content creation tasks and observe a significant improvement in performance along with enhanced usability by team members. We observe a substantial improvement in question answering accuracy and also the truthfulness of the generated content due to the application of the shaped-charge learning approach.
Isabella L. Trierweiler, Alexandra E. Doyle, Edward D. Young
A persistent question in exoplanet demographics is whether exoplanetary systems form from similar compositional building blocks to our own. Polluted white dwarf stars offer a unique way to address this question, as they provide measurements of the bulk compositions of exoplanetary material. We present a statistical analysis of the rocks polluting oxygen-bearing white dwarfs and compare their compositions to rocks in the solar system. We find that the majority of the extrasolar rocks are consistent with the composition of typical chondrites. Measurement uncertainties prevent distinguishing between chondrites and bulk Earth but do permit detecting the differences between chondritic compositions and basaltic or continental crust. We find no evidence of crust among the polluted white dwarfs. We show that the chondritic nature of extrasolar rocks is also supported by the compositions of local stars. While galactic chemical evolution results in variations in the relative abundances of rock-forming elements spatially and temporally on galaxy-wide scales, the current sample of polluted white dwarfs are sufficiently young and close to Earth that they are not affected by this process. We conclude that exotic compositions are not required to explain the majority of observed rock types around polluted white dwarfs and that variations between exoplanetary compositions in the stellar neighborhood are generally not due to significant differences in the initial composition of protoplanetary disks. Nonetheless, there is evidence from stellar observations that planets formed in the first several billion years in the Galaxy have lower metal core fractions compared with Earth on average.
Abstract In this paper, we formulate two new classes of black hole solutions in higher curvature quartic quasitopological gravity with nonabelian Yang–Mills theory. At first step, we consider the SO(n) and $$SO(n-1,1)$$ S O ( n - 1 , 1 ) semisimple gauge groups. We obtain the analytic quartic quasitopological Yang–Mills black hole solutions. Real solutions are only accessible for the positive value of the redefined quartic quasitopological gravity coefficient, $$\mu _{4}$$ μ 4 . These solutions have a finite value and an essential singularity at the origin, $$r=0$$ r = 0 for space dimension higher than 8. We also probe the thermodynamic and critical behavior of the quasitopological Yang–Mills black hole. The obtained solutions may be thermally stable only in the canonical ensemble. They may also show a first order phase transition from a small to a large black hole. In the second step, we obtain the pure quasitopological Yang–Mills black hole solutions. For the positive cosmological constant and the space dimensions greater than eight, the pure quasitopological Yang–Mills solutions have the ability to produce both the asymptotically AdS and dS black holes for respectively the negative and positive constant curvatures, $$k=-1$$ k = - 1 and $$k=+1$$ k = + 1 . This is unlike the quasitopological Yang–Mills theory which can lead to just the asymptotically dS solutions for $$\Lambda >0$$ Λ > 0 . The pure quasitopological Yang–Mills black hole is not thermally stable.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity