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In the forefront of quantitative solar physics research using large-aperture ground-based solar optical telescopes, high-contrast observation along with high-accuracy polarimetric measurement in the solar active region are required. In this paper, we propose a novel high-contrast imaging telescope construction with a 60 cm medium aperture, namely, the PAthfinder in Solar Adaptive Telescope (PASAT), in which a deformable secondary mirror is used as the adaptive optical correction device and a symmetrical optical path design is employed, leading to the least Muller matrix polarization instruments. The telescope can provide a high-resolution magnetic field with high accuracy for the solar active regions, as well as high-contrast images with a superior signal-to-noise ratio and photometric accuracy of the solar photosphere and chromosphere. These data will be directly used for a better understanding of the evolution and release of magnetic energy, which will help in improving space weather forecasting. Meanwhile, PASAT will accumulate the relevant techniques for constructing similar, larger solar telescopes in the future. [ABSTRACT FROM AUTHOR]

The aim of this article is to study the minimum variance analysis (MVA) degeneration problem based on the variance space geometry. We propose a mathematical metric to evaluate the separation of the eigenvalues. In the MVA method, a variance space is obtained geometrically using an ellipsoid where the axes are equal to the square root of the eigenvalues of the covariance matrix. The metric is defined as the product between the geometric flattening of the ellipsoid with respect to the three axes. In this article, we present a statistical analysis applied to the distribution of the eigenvalue ratios and the mathematical metric focussed on the study of several interplanetary coronal mass ejections with and without magnetic clouds (MCs). The results show the non-applicability of the ratio between the intermediate and minimum eigenvalues, as well as that around 90 % of MC events have values in the [ 4.5 , 19.5 ] range for the defined metric. Our metric is compared with others and we show its robustness in indicating the usefulness of the MVA method to identify the axes of MCs. [ABSTRACT FROM AUTHOR]

The Mexican Space Weather Service (SCiESMEX in Spanish) and National Space Weather Laboratory (LANCE in Spanish) were organized in 2014 and in 2016, respectively, to provide space weather monitoring and alerts, as well as scientific research in Mexico. In this work, we present the results of the first joint observations of two events (22 June and 29 September 2015) with our local network of instruments and their related products. This network includes the MEXART radio telescope (solar flare and radio burst), the Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories (CALLISTO) at the MEXART station (solar radio burst), the Mexico City Cosmic Ray Observatory (cosmic ray fluxes), GPS receiver networks (ionospheric disturbances), and the Teoloyucan Geomagnetic Observatory (geomagnetic field). The observations show that we detected significant space weather effects over the Mexican territory: geomagnetic and ionospheric disturbances (22 June 2015), variations in cosmic ray fluxes, and also radio communications' interferences (29 September 2015). The effects of these perturbations were registered, for the first time, using space weather products by SCiESMEX: total electron content (TEC) maps, regional geomagnetic index Kmex, radio spectrographs of low frequency, and cosmic ray fluxes. These results prove the importance of monitoring space weather phenomena in the region and the need to strengthening the instrumentation network. [ABSTRACT FROM AUTHOR]

An understanding of the mass build-up in galaxies over time necessitates tracing the evolution of cold gas (molecular and atomic) in galaxies. To that end, we have conducted a pilot study called CO Observations with the LMT of the Blind Ultra-Deep H I Environment Survey (COOL BUDHIES).We have observed 23 galaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z = 0.206), where 12 are cluster members and 11 are slightly in the foreground or background, using about 28 total hours on the Redshift Search Receiver on the Large Millimeter Telescope (LMT) to measure the 12CO J= 1→0 emission line and obtain molecular gas masses. These new observations provide a unique opportunity to probe both the molecular and atomic components of galaxies as a function of environment beyond the local Universe. For our sample of 23 galaxies, nine have reliable detections (S/N ≥ 3.6) of the 12COline, and another six have marginal detections (2.0 < S/N < 3.6). For the remaining eight targets we can place upper limits on molecular gas masses roughly between 109 and 1010M☉. Comparing our results to other studies of molecular gas, we find that our sample is significantly more abundant in molecular gas overall, when compared to the stellar and the atomic gas component, and our median molecular gas fraction lies about 1σ above the upper limits of proposed redshift evolution in earlier studies. We discuss possible reasons for this discrepancy, with the most likely conclusion being target selection and Eddington bias. [ABSTRACT FROM AUTHOR]

We use a numerical code called PAKALMPI to compute synthetic spectra of the solar emission in quiet conditions at millimeter, sub-millimeter, and infrared wavelengths. PAKALMPI solves the radiative transfer equation, with non- local thermodynamic equilibrium (NLTE), in a three- dimensional geometry using a multiprocessor environment. The code is able to use three opacity functions: classical bremsstrahlung, H-, and inverse bremsstrahlung. In this work, we have computed and compared two synthetic spectra, one in the common way: using bremsstrahlung opacity function and considering a fully ionized atmosphere; and a new one considering bremsstrahlung, inverse bremsstrahlung, and H- opacity functions in NLTE. We analyzed in detail the local behavior of the low atmospheric emission at 17,212, and 405 GHz (frequencies used by the Nobeyama Radio Heliograph and the Solar Submillimeter Telescope). We found that the H~ is the major emission mechanism at low altitudes (below 500 km) and that at higher altitudes the classical bremsstrahlung becomes the major mechanism of emission. However, the brightness temperature remains unalterable. Finally, we found that the inverse bremsstrahlung process is not important for radio emission at these heights. [ABSTRACT FROM AUTHOR]

One of the key challenges facing computer architects and compiler writers is the increasing discrepancy between processor cycle times and main memory access times. To alleviate this problem in array-intensive embedded signal and video processing applications, compilers may employ either control-centric transformations that change data access patterns of nested loops or data-centric transformations that modify memory layouts of multidimensional arrays. Most of the memory layout optimizations proposed so far either modify the layout of each array independently or are based on explicit data reorganizations at runtime. This paper focuses on a compiler technique, called array regrouping, that automatically maps multiple arrays into a single data (array) space to improve data access pattern. We present a mathematical framework that enables us to systematically derive suitable mappings for a given array-intensive embedded application. The framework divides the arrays accessed in a given program into several groups and each group is independently layout-transformed to improve spatial locality and reduce the number of conflict misses. As compared to the previous approaches, the proposed technique makes two new contributions: 1) It presents a graph based formulation of the array regrouping problem and 2) it demonstrates potential benefits of this aggressive array-regrouping strategy in optimizing behavior of embedded systems. Extensive experimental results demonstrate significant improvements in cache miss rates and execution times. An important advantage of this approach over the previous techniques that target conflict misses is that it reduces conflict misses without increasing the data space requirements of the application being optimized. This is a very desirable property in many embedded/portable environments where data space requirements determine the minimum physical memory capacity. [ABSTRACT FROM AUTHOR]

Key Points: The editors thank the 2022 peer reviewers [ABSTRACT FROM AUTHOR]

Key Point: The editors thank the 2021 peer reviewers [ABSTRACT FROM AUTHOR]

Natural disasters represent a major problem for many big cities. The biggest part of the population is in cities, which makes the concept of urban planning be a significant problem for the decision makers. In this paper, there are presented the results of a comparative analysis of the disaster risk management practices between Bucharest and Ciudad de Mexico in South America; and Istanbul in the euro-Mediterranean region. The analysis shows that all three cities have made considerable efforts regarding the risk analysis, especially in earthquakes. The elements they took into consideration are: the political engagement, identifying risks, the institutions and managing knowledge. Finally, the papers concludes by reasoning that the local authorities must focus more on reducing risks in order to reduce the physical vulnerability and to reach urban durabilit [ABSTRACT FROM AUTHOR]