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1.	Montoya, Oscar Danilo, et al. (författare) Optimal Demand Reconfiguration in Three-Phase Distribution Grids Using an MI-Convex Model 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:7 Tidskriftsartikel (refereegranskat)abstract The problem of the optimal load redistribution in electrical three-phase medium-voltage grids is addressed in this research from the point of view of mixed-integer convex optimization. The mathematical formulation of the load redistribution problem is developed in terminals of the distribution node by accumulating all active and reactive power loads per phase. These loads are used to propose an objective function in terms of minimization of the average unbalanced (asymmetry) grade of the network with respect to the ideal mean consumption per-phase. The objective function is defined as the l1-norm which is a convex function. As the constraints consider the binary nature of the decision variable, each node is conformed by a 3Ã—3 matrix where each row and column have to sum 1, and two equations associated with the load redistribution at each phase for each of the network nodes. Numerical results demonstrate the efficiency of the proposed mixed-integer convex model to equilibrate the power consumption per phase in regards with the ideal value in three different test feeders, which are composed of 4, 15, and 37 buses, respectively.
2.	Abu-Youssef, Morsy A. M., et al. (författare) Molecular, supramolecular structures combined with hirshfeld and dft studies of centrosymmetric m(Ii)-azido {m=ni(ii), fe(ii) or zn(ii)} complexes of 4-benzoylpyridine 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:11 Tidskriftsartikel (refereegranskat)abstract The supramolecular structures of the three metal (II) azido complexes [Fe(4bzpy)4 (N3 )2 ]; 1, [Ni(4bzpy)4 (N3 )2 ]; 2 and [Zn(4bzpy)2 (N3 )2 ]n; 3 with 4-benzoylpyridine (4bzpy) were presented. All complexes contain hexa-coordinated divalent metal ions with a slightly distorted octahedral MN6 coordination sphere. Complexes 1 and 2 are monomeric with terminal azido groups while 3 is one-dimensional coordination polymer containing azido groups with µ(1,1) and µ(1,3) bridging modes of bonding. Hirshfeld analysis was used to quantitatively determine the different contacts affecting the molecular packing in the studied complexes. The most common interactions are the polar O … H and N … H interactions and the hydrophobic C … H contacts. The charges at the M(II) sites are calculated to be 1.004, 0.847, and 1.147 e for complexes 1–3, respectively. The degree of asymmetry is the highest in the case of the terminal azide in complexes 1 and 2 while was found the lowest in the µ(1,1) and µ(1,3) azide bonding modes in the Zn(II) complex 3. These facts were further explained in terms of atoms in molecules (AIM) topological parameters.
3.	Ardonne, Eddy, et al. (författare) Classification of Metaplectic Fusion Categories 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:11 Tidskriftsartikel (refereegranskat)abstract In this paper, we study a family of fusion and modular systems realizing fusion categories Grothendieck equivalent to the representation category for so(2p+1)2. These categories describe non-abelian anyons dubbed ‘metaplectic anyons’. We obtain explicit expressions for all the F- and R-symbols. Based on these, we conjecture a classification for their monoidal equivalence classes from an analysis of their gauge invariants and define a function which gives us the number of classes.
4.	Bashitialshaer, Raed, et al. (författare) Obstacle Comparisons to Achieving Distance Learning and Applying Electronic Exams during COVID-19 Pandemic 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:1 Tidskriftsartikel (refereegranskat)abstract This study aims to identify obstacles and barriers to achieving quality distance learning and the use of electronic exams, comparing them to pursue success in the distance education system during the coronavirus pandemic (COVID-19). It also aimed to determine the similarity and differences between the two main components of distance education. This is based on a sample of evaluations from professors and students at universities in the Arab world, i.e., Algerian, Egyptian, Iraqi, and Palestinian universities. We used a descriptive approach using questionnaires (open question) with conveniently selected samples from two different groups: (1) 400 professors and student’s feedback from 600 distributed (i.e., Algerian, Egyptian, Palestinian, and Iraqi) and (2) 152 professors and student’s feedback from 300 distributed (i.e., Palestinian universities in the governorates of Gaza). The results indicated that professors and students faced 27 barriers in both distance learning and electronic exams, which are divided into four groups (categories) according to the sample. Recommendations to understand and overcome these obstacles will also be presented to improve distance learning and e-exams in the future. It is important to coordinate efforts in the development of distance education, especially concerning universities using distance learning and e-exams.
5.	Berggren, Åsa, et al. (författare) The Relationship Between Morphological Symmetry and Immune Response in Wild-Caught Adult Bush-Crickets 2009 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 1, s. 106-114 Tidskriftsartikel (refereegranskat)abstract Despite interest in the relationship between fluctuating asymmetry (FA), immune response and ecological factors in insects, little data are available from wild populations. In this study we measured FA and immune response in 370 wild-caught male bush-crickets, Metrioptera roeseli, from 20 experimentally introduced populations in southern-central Sweden. Individuals with more-symmetric wings had a higher immune response as measured by the cellular encapsulation of a surgically-implanted nylon monofilament. However, we found no relationship between measures of FA in other organs (i.e. tibia and maxillary palp) and immune response, suggesting that this pattern may reflect differing selection pressures
6.	Dahlberg, Oskar, et al. (författare) Fully Metallic Flat Lens Based on Locally Twist-Symmetric Array of Complementary Split-Ring Resonators 2019 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 11:4 Tidskriftsartikel (refereegranskat)abstract In this article, we demonstrate how twist symmetries can be employed in the design of flat lenses. A lens design is proposed, consisting of 13 perforated metallic sheets separated by an air gap. The perforation in the metal is a two-dimensional array of complementary split-ring resonators. In this specific design, the twist symmetry is local, as it is only applied to the unit cell of the array. Moreover, the twist symmetry is an approximation, as it is only applied to part of the unit cell. First, we demonstrate that, by varying the order of twist symmetry, the phase delay experienced by a wave propagating through the array can be accurately controlled. Secondly, a lens is designed by tailoring the unit cells throughout the aperture of the lens in order to obtain the desired phase delay. Simulation and measurement results demonstrate that the lens successfully transforms a spherical wave emanating from the focal point into a plane wave at the opposite side of the lens. The demonstrated concepts find application in future wireless communication networks where fully-metallic directive antennas are desired.
7.	Farooq, Muhammad, et al. (författare) Computing Expectiles Using k-Nearest Neighbours Approach 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:4 Tidskriftsartikel (refereegranskat)abstract Expectiles have gained considerable attention in recent years due to wide applications in many areas. In this study, the k-nearest neighbours approach, together with the asymmetric least squares loss function, called ex-kNN, is proposed for computing expectiles. Firstly, the effect of various distance measures on ex-kNN in terms of test error and computational time is evaluated. It is found that Canberra, Lorentzian, and Soergel distance measures lead to minimum test error, whereas Euclidean, Canberra, and Average of (L1,L∞) lead to a low computational cost. Secondly, the performance of ex-kNN is compared with existing packages er-boost and ex-svm for computing expectiles that are based on nine real life examples. Depending on the nature of data, the ex-kNN showed two to 10 times better performance than er-boost and comparable performance with ex-svm regarding test error. Computationally, the ex-kNN is found two to five times faster than ex-svm and much faster than er-boost, particularly, in the case of high dimensional data.
8.	Ferrari, Arnaud, 1973-, et al. (författare) Exploration of Extended Higgs Sectors with Run-2 Proton-Proton Collision Data at the LHC 2021 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 13:11 Tidskriftsartikel (refereegranskat)abstract One doublet of complex scalar fields is the minimal content of the Higgs sector in order to achieve spontaneous electroweak symmetry breaking and, in turn, to generate the masses of fundamental particles in the Standard Model. However, several theories beyond the Standard Model predict a nonminimal Higgs sector and introduce additional singlets, doublets or even higher-order weak isospin representations, thereby yielding additional Higgs bosons. With its high proton-proton collision energy (13 TeV during Run-2), the Large Hadron Collider opens a new window towards the exploration of extended Higgs sectors. This review article summarises the current state-of-the-art experimental results recently obtained in searches for new neutral and charged Higgs bosons with a partial or full Run-2 dataset.
9.	Fisher, W.P., Jr. (författare) Bateson and wright on number and quantity : How to not separate thinking from its relational context 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:8 Tidskriftsartikel (refereegranskat)abstract As part of his explication of the epistemological error made in separating thinking from its ecological context, Bateson distinguished counts from measurements. With no reference to Bateson, the measurement theory and practice of Benjamin Wright also recognizes that number and quantity are different logical types. Describing the confusion of counts and measures as schizophrenic, like Bateson, Wright, a physicist and certified psychoanalyst, showed mathematically that convergent stochastic processes informing counts are predictable in ways that facilitate methodical measurements. Wright’s methods experimentally evaluate the complex symmetries of nonlinear and stochastic numeric patterns as a basis for estimating interval quantities. These methods also retain connections with locally situated concrete expressions, mediating the data display by contextualizing it in relation to the abstractly communicable and navigable quantitative unit and its uncertainty. Decades of successful use of Wright’s methods in research and practice are augmented in recent collaborations of metrology engineers and psychometricians who are systematically distinguishing numeric counts from measured quantities in new classes of knowledge infrastructure. Situating Wright’s work in the context of Bateson’s ideas may be useful for infrastructuring new political, economic, and scientific outcomes. © 2021 by the author.
10.	Gudkov, Vladimir, et al. (författare) A Possible Neutron-Antineutron Oscillation Experiment at PF1B at the Institut Laue Langevin 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:12 Tidskriftsartikel (refereegranskat)abstract We consider a possible neutron–antineutron (n−n¯) oscillation experiment at the PF1B instrument at Institut Laue Langevin. It can improve the best existing constraint on the transition rate and also allow the testing of the methods and instrumentation which would be needed for a later larger-scale experiment at ESS. The main gain factors over the most competitive experiment, performed earlier at PF1 instrument at ILL, are: a more intense neutron beam and a new operating mode based on coherent n and n¯ mirror reflections. The installation of such an experiment would need a temporary replacement of the existing ballistic neutron guide by a specially designed n/n¯ guide with a gradually increasing cross section and a specially selected coating as well as the development and construction of an advanced n¯ annihilation detector with a high efficiency and low background. The overall gain factor could reach up to an order of magnitude and depends on the chosen experiment configuration.
11.	Göteman, Malin (författare) N=(4,4) supersymmetry and T-duality 2012 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 4:4, s. 603-625 Tidskriftsartikel (refereegranskat)
12.	Heissenberg, Carlo, et al. (författare) Corrections to Wigner-Eckart Relations by Spontaneous Symmetry Breaking 2020 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 12:7 Tidskriftsartikel (refereegranskat)abstract The matrix elements of operators transforming as irreducible representations of an unbroken symmetry groupGare governed by the well-known Wigner-Eckart relations. In the case of infinite-dimensional systems, withGspontaneously broken, we prove that the corrections to such relations are provided by symmetry breaking Ward identities, and simply reduce to a tadpole term involving Goldstone bosons. The analysis extends to the case in which an explicit symmetry breaking term is present in the Hamiltonian, with the tadpole term now involving pseudo Goldstone bosons. An explicit example is discussed, illustrating the two cases.
13.	Jain, Sheenam, et al. (författare) Garment Categorization Using Data Mining Techniques 2020 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; :6 Tidskriftsartikel (refereegranskat)abstract The apparel industry houses a huge amount and variety of data. At every step of the supply chain, data is collected and stored by each supply chain actor. This data, when used intelligently, can help with solving a good deal of problems for the industry. In this regard, this article is devoted to the application of data mining on the industry’s product data, i.e., data related to a garment, such as fabric, trim, print, shape, and form. The purpose of this article is to use data mining and symmetry-based learning techniques on product data to create a classification model that consists of two subsystems: (1) for predicting the garment category and (2) for predicting the garment sub-category. Classification techniques, such as Decision Trees, Naïve Bayes, Random Forest, and Bayesian Forest were applied to the ‘Deep Fashion’ open-source database. The data contain three garment categories, 50 garment sub-categories, and 1000 garment attributes. The two subsystems were first trained individually and then integrated using soft classification. It was observed that the performance of the random forest classifier was comparatively better, with an accuracy of 86%, 73%, 82%, and 90%, respectively, for the garment category, and sub-categories of upper body garment, lower body garment, and whole-body garment.
14.	Jing, Wang, et al. (författare) System Dynamics Modeling Strategy for Civil Construction Projects : The Concept of Successive Legislation Periods 2019 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 11:5, s. 1-18 Tidskriftsartikel (refereegranskat)abstract Cost and time performance are considered to be the most important aspects in the construction industry. The exceptional conditions that took place in Iraq since the beginning of the third millennia had a huge vicious impact on the cost and time performance of local constructionprojects. This may represent the principal motivation for the local authorities to enact some four successive legislations in order to control the performance of the construction industry. In this research, an evaluation is made to the cost and time performance of local construction projects and their variation due to the multiple changes in the internal factors that affect project performance,and changes in the surrounding events include legislative, economic, and security environment during the period that lasted from 2003 to 2014. Data is collected from 30 governmental projects to conduct the evaluation. A comprehensive questionnaire is performed to estimate a quantitative value for the impact of several factors that concern both the owner and the contractor, with special consideration to their variation through the successive legislation periods. These estimates are, in turn, utilized in a system dynamics model, in which the project development process is simulated.The final cost and duration changes in the project are accumulated in the form of stocks to give an indication of the cost and time performance of the project. The developed model returned a progressive reduction of 10.9% for the change in project cost and 135.37% for the change in project schedule throughout the eleven years period.
15.	Lan, Kun, et al. (författare) Self-Adaptive Pre-Processing Methodology for Big Data Stream Mining in Internet of Things Environmental Sensor Monitoring 2017 Ingår i: Symmetry. - Basel : MDPI. - 2073-8994. ; 9:10 Tidskriftsartikel (refereegranskat)abstract Over the years, advanced IT technologies have facilitated the emergence of new ways of generating and gathering data rapidly, continuously, and largely and are associated with a new research and application branch, namely, data stream mining (DSM). Among those multiple scenarios of DSM, the Internet of Things (IoT) plays a significant role, with a typical meaning of a tough and challenging computational case of big data. In this paper, we describe a self-adaptive approach to the pre-processing step of data stream classification. The proposed algorithm allows different divisions with both variable numbers and lengths of sub-windows under a whole sliding window on an input stream, and clustering-based particle swarm optimization (CPSO) is adopted as the main metaheuristic search method to guarantee that its stream segmentations are effective and adaptive to itself. In order to create a more abundant search space, statistical feature extraction (SFX) is applied after variable partitions of the entire sliding window. We validate and test the effort of our algorithm with other temporal methods according to several IoT environmental sensor monitoring datasets. The experiments yield encouraging outcomes, supporting the reality that picking significant appropriate variant sub-window segmentations heuristically with an incorporated clustering technique merit would allow these to perform better than others
16.	Lidin, Sven, et al. (författare) A higher dimensional description of the structure of β-Mn 2012 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 4:3, s. 537-544 Tidskriftsartikel (refereegranskat)abstract The structure of β-Mn crystallizes in space group P4 132. The pseudo 8-fold nature of the 4 1 axes makes it constitute an approximant to the octagonal quasicrystals. In this paper we analyze why a five-dimensional super space group containing mutually perpendicular 8-fold axes cannot generate P4 132 on projection to 3-d space and how this may instead be accomplished from a six-dimensional model. A procedure for generating the actual structure of β-Mn lifted to six-dimensional space is given.
17.	Lindström, Ulf (författare) Supersymmetric Sigma Model Geometry 2012 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 4:3, s. 474-506 Tidskriftsartikel (refereegranskat)abstract This is a review of how sigma models formulated in Superspace have become important tools for understanding geometry. Topics included are: The (hyper)kahler reduction; projective superspace; the generalized Legendre construction; generalized Kahler geometry and constructions of hyperkahler metrics on Hermitian symmetric spaces.
18.	Low-Rank Multi-Channel Features for Robust Visual Object Tracking 2019 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 11:9 Tidskriftsartikel (refereegranskat)abstract Kernel correlation filters (KCF) demonstrate significant potential in visual object tracking by employing robust descriptors. Proper selection of color and texture features can provide robustness against appearance variations. However, the use of multiple descriptors would lead to a considerable feature dimension. In this paper, we propose a novel low-rank descriptor, that provides better precision and success rate in comparison to state-of-the-art trackers. We accomplished this by concatenating the magnitude component of the Overlapped Multi-oriented Tri-scale Local Binary Pattern (OMTLBP), Robustness-Driven Hybrid Descriptor (RDHD), Histogram of Oriented Gradients (HoG), and Color Naming (CN) features. We reduced the rank of our proposed multi-channel feature to diminish the computational complexity. We formulated the Support Vector Machine (SVM) model by utilizing the circulant matrix of our proposed feature vector in the kernel correlation filter. The use of discrete Fourier transform in the iterative learning of SVM reduced the computational complexity of our proposed visual tracking algorithm. Extensive experimental results on Visual Tracker Benchmark dataset show better accuracy in comparison to other state-of-the-art trackers.
19.	Palomares-Caballero, Angel, et al. (författare) Twist and Glide Symmetries for Helix Antenna Design and Miniaturization 2019 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 11:3 Tidskriftsartikel (refereegranskat)abstract Here we propose the use of twist and glide symmetries to increase the equivalent refractive index in a helical guiding structure. Twist- and glide-symmetrical distributions are created with corrugations placed at both sides of a helical strip. Combined twist-and glide-symmetrical helical unit cells are studied in terms of their constituent parameters. The increase of the propagation constant is mainly controlled by the length of the corrugations. In our proposed helix antenna, twist and glide symmetry cells are used to reduce significantly the operational frequency compared with conventional helix antenna. Equivalently, for a given frequency of operation, the dimensions of helix are reduced with the use of higher symmetries. The theoretical results obtained for our proposed helical structure based on higher symmetries show a reduction of 42.2% in the antenna size maintaining a similar antenna performance when compared to conventional helix antennas.
20.	Pan, Feng, et al. (författare) np-Pair Correlations in the Isovector Pairing Model 2021 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 13:8 Tidskriftsartikel (refereegranskat)abstract A diagonalization scheme for the shell model mean-field plus isovector pairing Hamiltonian in the O(5) tensor product basis of the quasi-spin SU Lambda(2) circle times SUI(2) chain is proposed. The advantage of the diagonalization scheme lies in the fact that not only can the isospin-conserved, charge-independent isovector pairing interaction be analyzed, but also the isospin symmetry breaking cases. More importantly, the number operator of the np-pairs can be realized in this neutron and proton quasi-spin basis, with which the np-pair occupation number and its fluctuation at the J = 0(+) ground state of the model can be evaluated. As examples of the application, binding energies and low-lying J = 0(+) excited states of the even-even and odd-odd N similar to Z ds-shell nuclei are fit in the model with the charge-independent approximation, from which the neutron-proton pairing contribution to the binding energy in the ds-shell nuclei is estimated. It is observed that the decrease in the double binding-energy difference for the odd-odd nuclei is mainly due to the symmetry energy and Wigner energy contribution to the binding energy that alter the pairing staggering patten. The np-pair amplitudes in the np-pair stripping or picking-up process of these N = Z nuclei are also calculated.
21.	Pérez de los Heros, Carlos (författare) Status, Challenges and Directions in Indirect Dark Matter Searches 2020 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 12:10 Forskningsöversikt (refereegranskat)abstract Indirect searches for dark matter are based on detecting an anomalous flux of photons, neutrinos or cosmic-rays produced in annihilations or decays of dark matter candidates gravitationally accumulated in heavy cosmological objects, like galaxies, the Sun or the Earth. Additionally, evidence for dark matter that can also be understood as indirect can be obtained from early universe probes, like fluctuations of the cosmic microwave background temperature, the primordial abundance of light elements or the Hydrogen 21-cm line. The techniques needed to detect these different signatures require very different types of detectors: Air shower arrays, gamma- and X-ray telescopes, neutrino telescopes, radio telescopes or particle detectors in balloons or satellites. While many of these detectors were not originally intended to search for dark matter, they have proven to be unique complementary tools for direct search efforts. In this review we summarize the current status of indirect searches for dark matter, mentioning also the challenges and limitations that these techniques encounter.
22.	Pertoldi, Cino, et al. (författare) The Novel Concept of "Behavioural Instability" and Its Potential Applications 2016 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 8:11 Tidskriftsartikel (refereegranskat)abstract The concept of developmental instability (DI) is a well-known indicator of environmental and genetic stress and is often investigated using various indices such as fluctuating asymmetry, directional asymmetry, antisymmetry and phenotypic variance. Investigations dealing with DI are using morphometric traits. The aim of this investigation is to present the novel concept of behavioural instability in which the trait measured is a behavioural trait. We apply the conventional indices used for the estimation of developmental instability on directional movement-clockwise (CW) and counter-clockwise (CCW) movement of 19 highly inbred lines of Drosophila melanogaster tested in a circular arena. We show that it is possible to quantify behavioural instability using the indices traditionally used to investigate DI. Results revealed several significant differences among lines, depending on the index utilized. The perspectives of utilizing the concept in biological research such as toxicology, evolutionary and stress biology are discussed.
23.	Pham, Binh Thai, et al. (författare) Performance Evaluation of Machine Learning Methods for Forest Fire Modeling and Prediction 2020 Ingår i: Symmetry. - Switzerland : MDPI. - 2073-8994. ; 12:6 Tidskriftsartikel (refereegranskat)abstract Predicting and mapping fire susceptibility is a top research priority in fire-prone forests worldwide. This study evaluates the abilities of the Bayes Network (BN), Naïve Bayes (NB), Decision Tree (DT), and Multivariate Logistic Regression (MLP) machine learning methods for the prediction and mapping fire susceptibility across the Pu Mat National Park, Nghe An Province, Vietnam. The modeling methodology was formulated based on processing the information from the 57 historical fires and a set of nine spatially explicit explanatory variables, namely elevation, slope degree, aspect, average annual temperate, drought index, river density, land cover, and distance from roads and residential areas. Using the area under the receiver operating characteristic curve (AUC) and seven other performance metrics, the models were validated in terms of their abilities to elucidate the general fire behaviors in the Pu Mat National Park and to predict future fires. Despite a few differences between the AUC values, the BN model with an AUC value of 0.96 was dominant over the other models in predicting future fires. The second best was the DT model (AUC = 0.94), followed by the NB (AUC = 0.939), and MLR (AUC = 0.937) models. Our robust analysis demonstrated that these models are sufficiently robust in response to the training and validation datasets change. Further, the results revealed that moderate to high levels of fire susceptibilities are associated with ~19% of the Pu Mat National Park where human activities are numerous. This study and the resultant susceptibility maps provide a basis for developing more efficient fire-fighting strategies and reorganizing policies in favor of sustainable management of forest resources.
24.	Shestopalov, Yury, 1953-, et al. (författare) Qualitative theory of two-dimensional polynomial dynamical systems 2021 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 13:10 Tidskriftsartikel (refereegranskat)abstract A qualitative theory of two-dimensional quadratic-polynomial integrable dynamical systems (DSs) is constructed on the basis of a discriminant criterion elaborated in the paper. This criterion enables one to pick up a single parameter that makes it possible to identify all feasible solution classes as well as the DS critical and singular points and solutions. The integrability of the considered DS family is established. Nine specific solution classes are identified. In each class, clear types of symmetry are determined and visualized and it is discussed how transformations between the solution classes create new types of symmetries. Visualization is performed as series of phase portraits revealing all possible catastrophic scenarios that result from the transition between the solution classes.
25.	Stefanov, Bozhidar I., et al. (författare) Effects of Anodic Aluminum Oxide Substrate Pore Geometry on the Gas-Phase Photocatalytic Activity of ZnO/Al2O3 Composites Prepared by Atomic Layer Deposition 2021 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 13:8 Tidskriftsartikel (refereegranskat)abstract We report on the photocatalytic activity of ZnO layers deposited by atomic layer deposition on a porous anodic aluminum oxide substrate with hexagonal pore symmetry and varied pore dimensions. ZnO/Al2O3 composites were prepared with pore diameters in the range 93–134 nm and interpore distance in the range 185–286 nm, and their photocatalytic activity was measured for gas-phase photocatalytic oxidation of acetaldehyde at varying UV illumination intensities (0.08–3.94 mW cm−2). The results show that substrates with narrower pore diameters (<115 nm, in the case of this study) have a detrimental effect on the photocatalyst performance, despite their higher effective surface. The results are explained on the basis of limited mass transfer inside the porous structure and can be used as a guideline in the purposeful design of photocatalysts with a nanoporous or nanotubular structure.
26.	Sun, Y., et al. (författare) A fuzzy programming method for modeling demand uncertainty in the capacitated road-rail multimodal routing problem with time windows 2019 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 11:1 Tidskriftsartikel (refereegranskat)abstract Demand uncertainty is an important issue that influences the strategic, tactical, and operational-level decision making in the transportation/logistics/supply chain planning. In this study, we explore the effect of demand uncertainty on the operational-level freight routing problem in the capacitated multimodal transportation network that consists of schedule-based rail transportation and time-flexible road transportation. Considering the imprecise characteristic of the demand, we adopt fuzzy set theory to model its uncertainty and use trapezoidal fuzzy numbers to represent the fuzzy demands. We set multiple transportation orders as the optimization object and employ soft time windows to reflect the customer requirement on on-time transportation. Under the above situation, we establish a fuzzy mixed integer nonlinear programming (FMINLP) model to formulate the capacitated road-rail multimodal routing problem with demand uncertainty and time windows. We first use the fuzzy expected value model and credibility measure based fuzzy chance-constrained programming to realize the defuzziness of the model and then adopt linearization technique to reformulate the crisp model to finally generate an equivalent mixed integer linear programming (MILP) model that can be solved by standard mathematical programming software. Finally, a numerical case is presented to demonstrate the feasibility of the proposed method. Sensitivity analysis and fuzzy simulation are combined to quantify the effect of demand uncertainty on the routing problem and also reveal some helpful insights and managerial implications.
27.	Tamayo-Dominguez, Adrian, et al. (författare) One-Plane Glide-Symmetric Holey Structures for Stop-Band and Refraction Index Reconfiguration 2019 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 11:4 Tidskriftsartikel (refereegranskat)abstract This work presents a new configuration to create glide-symmetric structures in a single plane, which facilitates fabrication and avoids alignment problems in the assembly process compared to traditional glide-symmetric structures based on several planes. The proposed structures can be printed on the metal face of a dielectric substrate, which acts as a support. The article includes a parametric study based on dispersion diagrams on the appearance of stop-bands and phase-shifting by breaking the symmetry. In addition, a procedure to regenerate symmetry is proposed that may be useful for reconfigurable devices. Finally, the measured and simulated S parameters of 10 x 10 unit-cell structures are presented to illustrate the attenuation in these stop-bands and the refractive index of the propagation modes. The attenuation obtained is greater than 30 dB in the stop-band for the symmetry-broken prototype.
28.	Tamm, Martin (författare) A Combinatorial Approach to Time Asymmetry 2016 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 8:3 Tidskriftsartikel (refereegranskat)abstract In this paper, simple models for the multiverse are analyzed. Each universe is viewed as a path in a graph, and by considering very general statistical assumptions, essentially originating from Boltzmann, we can make the set of all such paths into a finite probability space. We can then also attempt to compute the probabilities for different kinds of behavior and in particular under certain conditions argue that an asymmetric behavior of the entropy should be much more probable than a symmetric one. This offers an explanation for the asymmetry of time as a broken symmetry in the multiverse. The focus here is on simple models which can be analyzed using methods from combinatorics. Although the computational difficulties rapidly become enormous when the size of the model grows, this still gives hints about how a full-scale model should behave.
29.	Tamm, Martin (författare) Minimizing Curvature in Euclidean and Lorentz Geometry 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:8 Tidskriftsartikel (refereegranskat)abstract In this paper, an interesting symmetry in Euclidean geometry, which is broken in Lorentz geometry, is studied. As it turns out, attempting to minimize the integral of the square of the scalar curvature leads to completely different results in these two cases. The main concern in this paper is about metrics in R-3, which are close to being invariant under rotation. If we add a time-axis and let the metric start to rotate with time, it turns out that, in the case of (locally) Euclidean geometry, the (four-dimensional) scalar curvature will increase with the speed of rotation as expected. However, in the case of Lorentz geometry, the curvature will instead initially decrease. In other words, rotating metrics can, in this case, be said to be less curved than non-rotating ones. This phenomenon seems to be very general, but because of the enormous amount of computations required, it will only be proved for a class of metrics which are close to the flat one, and the main (symbolic) computations have been carried out on a computer. Although the results here are purely mathematical, there is also a connection to physics. In general, a deeper understanding of Lorentz geometry is of fundamental importance for many applied problems.
30.	Vigren, Erik, et al. (författare) Simple Solutions of Lattice Sums for Electric Fields Due to Infinitely Many Parallel Line Charges 2020 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 12:6 Tidskriftsartikel (refereegranskat)abstract We present surprisingly simple closed-form solutions for electric fields and electric potentials at arbitrary position(x, y)within a plane crossed by infinitely long line charges at regularly repeating positions using angular or elliptic functions with complex arguments. The lattice sums for the electric-field components and the electric potentials could be exactly solved, and the duality symmetry of trigonometric and lemniscate functions occurred in some solutions. The results may have relevance in calculating field configurations with rectangular boundary conditions. Several series related to Gauss's constant are presented, established either as corollary results or via parallel investigations conducted in the spirit of experimental mathematics.
31.	Visinelli, Luca (författare) (Non-)Thermal Production of WIMPs during Kination 2018 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 10:11 Tidskriftsartikel (refereegranskat)abstract Understanding the nature of the Dark Matter (DM) is one of the current challenges in modern astrophysics and cosmology. Knowing the properties of the DM particle would shed light on physics beyond the Standard Model and even provide us with details of the early Universe. In fact, the detection of such a relic would bring us information from the pre-Big Bang Nucleosynthesis (BBN) period, an epoch from which we have no direct data, and could even hint at inflation physics. In this work, we assume that the expansion rate of the Universe after inflation is governed by the kinetic energy of a scalar field phi, in the so-called "kination" model. Adding to previous work on the subject, we assume that the phi field decays into both radiation and DM particles, which we take to be Weakly Interacting Massive Particles (WIMPs). The present abundance of WIMPs is then fixed during the kination period through either a thermal "freeze-out" or "freeze-in" mechanism, or through a non-thermal process governed by the decay of phi. We explore the parameter space of this theory with the requirement that the present WIMP abundance provides the correct relic budget. Requiring that BBN occurs during the standard cosmological scenario sets a limit on the temperature at which the kination period ends. Using this limit and assuming the WIMP has a mass m(chi) = 100 GeV, we obtain that the thermally averaged WIMP annihilation cross section has to satisfy the constraints 4 x 10(-16) GeV-2 less than or similar to less than or similar to 2 x 10(-5) GeV-2 in order for having at least one of the production mechanism to yield the observed amount of DM. This result shows how the properties of the WIMP particle, if ever measured, can yield information on the pre-BBN content of the Universe.
32.	Visinelli, Luca, et al. (författare) Revisiting a Negative Cosmological Constant from Low-Redshift Data 2019 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 11:8 Tidskriftsartikel (refereegranskat)abstract Persisting tensions between high-redshift and low-redshift cosmological observations suggest the dark energy sector of the Universe might be more complex than the positive cosmological constant of the ?CDM model. Motivated by string theory, wherein symmetry considerations make consistent AdS backgrounds (i.e., maximally-symmetric spacetimes with a negative cosmological constant) ubiquitous, we explore a scenario where the dark energy sector consists of two components: a negative cosmological constant, with a dark energy component with equation of state w phi on top. We test the consistency of the model against low-redshift baryon acoustic oscillation and Type Ia supernovae distance measurements, assessing two alternative choices of distance anchors: the sound horizon at baryon drag determined by the Planck collaboration and the Hubble constant determined by the SH0ES program. We find no evidence for a negative cosmological constant and mild indications for an effective phantom dark energy component on top. A model comparison analysis reveals that the ?CDM model is favoured over our negative cosmological constant model. While our results are inconclusive, should low-redshift tensions persist with future data, it would be worth reconsidering and further refining our toy negative cosmological constant model by considering realistic string constructions.
33.	Vissani, Francesco, et al. (författare) On the Time Distribution of Supernova Antineutrino Flux 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:10 Tidskriftsartikel (refereegranskat)abstract Neutrino leptonic flavor symmetry violation is the only evidence for physics beyond the standard model. Much of what we have learned on these particles is derived from the study of their natural sources, such as the Sun or core-collapse supernovae. Neutrino emission from supernovae is particularly interesting and leptonic flavor transformations in supernova neutrinos have attracted a lot of theoretical attention. Unfortunately, the emission of core-collapse supernovae is not fully understood: thus, an inescapable preliminary step to progress is to improve on that, and future neutrino observations can help. One pressing and answerable question concerns the time distribution of the supernova anti-neutrino events. We propose a class of models of the time distribution that describe emission curves similar to those theoretically expected and consistent with available observations from the data of supernova SN1987A. They have the advantages of being motivated on physical bases and easy to interpret; they are flexible and adaptable to the results of the observations from a future galactic supernova. Important general characteristics of these models are the presence of an initial ramp and that a significant portion of the signal is in the first second of the emission.
34.	Yang, Taimin, et al. (författare) A Comparison of Structure Determination of Small Organic Molecules by 3D Electron Diffraction at Cryogenic and Room Temperature 2021 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 13:11 Tidskriftsartikel (refereegranskat)abstract 3D electron diffraction (3D ED), also known as micro-crystal electron diffraction (MicroED), is a rapid, accurate, and robust method for structure determination of submicron-sized crystals. 3D ED has mainly been applied in material science until 2013, when MicroED was developed for studying macromolecular crystals. MicroED was considered as a cryo-electron microscopy method, as MicroED data collection is usually carried out in cryogenic conditions. As a result, some researchers may consider that 3D ED/MicroED data collection on crystals of small organic molecules can only be performed in cryogenic conditions. In this work, we determined the structure for sucrose and azobenzene tetracarboxylic acid (H4ABTC). The structure of H4ABTC is the first crystal structure ever reported for this molecule. We compared data quality and structure accuracy among datasets collected under cryogenic conditions and room temperature. With the improvement in data quality by data merging, it is possible to reveal hydrogen atom positions in small organic molecule structures under both temperature conditions. The experimental results showed that, if the sample is stable in the vacuum environment of a transmission electron microscope (TEM), the data quality of datasets collected under room temperature is at least as good as data collected under cryogenic conditions according to various indicators (resolution, I/σ(I), CC1/2 (%), R1, Rint, ADRA).
35.	Yiu, Sze-Chun, et al. (författare) Status of the Design of an Annihilation Detector to Observe Neutron-Antineutron Conversions at the European Spallation Source 2022 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 14:1 Tidskriftsartikel (refereegranskat)abstract The goal of the HIBEAM/NNBAR program is to search for baryon number violation via the conversion or oscillation of neutrons into sterile neutrons and/or antineutrons at the European Spallation Source. A key experimental component of the program is the construction of an annihilation detector to directly observe the production of an antineutron following the oscillation. Design studies for the annihilation detector are presented. The predicted response of the detector models are studied using GEANT4 simulations made with Monte Carlo simulations of the annihilation signal topology and cosmic ray backgrounds. Particle identification and sensitive discriminating observables, such as invariant mass and sphericity, are shown.
36.	Zhu, Jun, et al. (författare) On the Importance of Clar Structures of Polybenzenoid Hydrocarbons as Revealed by the n-Contribution to the Electron Localization Function 2010 Ingår i: Symmetry. - Basel : MDPI. - 2073-8994. ; 2:3, s. 1653-1682 Tidskriftsartikel (refereegranskat)abstract The degree of p-electron (de)localization and aromaticity of a series of polybenzenoid hydrocarbons (PBHs) has been analyzed through the π-contribution to the electron localization function (ELFπ), calculated at the B3LYP/6-311G(d,p) hybrid density functional theory level. The extent of p-electron delocalization in the various hexagons of a PBH was determined through analysis of the bifurcation values of the ELFp basins (BV(ELFp)), the spans in the bifurcation values in each hexagon (ΔBV(ELFπ)), and the ring-closure bifurcation values of the ELFπ (RCBV(ELFπ)). These computed results were compared to the qualitative description of local aromaticities of the different hexagons in terms of Clar structures with p-sextets. Benzene, [18]annulene, and thirty two PBHs were analyzed at their equilibrium geometries, and benzene and triphenylene were also analyzed at bond length distorted structures. In general, the description of PBHs in terms of Clar valence structures is supported by the ELFp properties, although there are exceptions. For PBHs at their equilibrium geometries there is a clear sigmoidal relationship between the CC bond lengths and the amount of p-electron (de)localization at these bonds, however, this relationship is lost for bond distorted geometries. In the latter cases, we specifically examined benzene in D3h symmetric “1,3,5-cyclohexatriene” structures and triphenylene in eight different structures. From the distorted benzenes and triphenylenes it becomes clear that there is a distinct tendency for the p-electron network to retain delocalization (aromaticity). The ELFp analysis thus reveals an antidistortive rather than a distortive behavior of the p-electrons in these investigated compounds.
37.	Bock, Wolfgang, et al. (författare) On Solvable Lie Algebras of White Noise Operators 2022 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 14:11 Tidskriftsartikel (refereegranskat)abstract We characterize the dimension of Lie algebras of white noise operators containing the quantum white noise derivatives of the conservation operator. We establish isomorphisms to filiform Lie algebras, Engel-type algebras, and solvable Lie algebras with Heisenberg nilradical and Abelian nilradical. A new class of solvable Lie algebras is proposed, those having an Engel-type algebra as nilradical. This arises in white noise analysis as a (Formula presented.) -dimensional Lie algebra containing the identity operator, annihilation operators, creation operators (Heisenberg algebra), number operator, and Gross Laplacian.
38.	Conte, F, et al. (författare) A Transcriptome- and Interactome-Based Analysis Identifies Repurposable Drugs for Human Breast Cancer Subtypes 2022 Ingår i: SYMMETRY-BASEL. - : MDPI AG. ; 14:11 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Breast cancer (BC) is a heterogeneous and complex disease characterized by different subtypes with distinct morphologies and clinical implications and for which new and effective treatment options are urgently demanded. The computational approaches recently developed for drug repurposing provide a very promising opportunity to offer tools that efficiently screen potential novel medical indications for various drugs that are already approved and used in clinical practice. Here, we started with disease-associated genes that were identified through a transcriptome-based analysis, which we used to predict potential repurposable drugs for various breast cancer subtypes by using an algorithm that we developed for drug repurposing called SAveRUNNER. Our findings were also in silico validated by performing a gene set enrichment analysis, which confirmed that most of the predicted repurposable drugs may have a potential treatment effect against breast cancer pathophenotypes.
39.	Gschwendtner, Dda, et al. (författare) The AWAKE Run 2 Programme and Beyond 2022 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 14:8 Tidskriftsartikel (refereegranskat)abstract Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. The use of high energy protons to drive wakefields in plasma has been demonstrated during Run 1 of the AWAKE programme at CERN. Protons of energy 400 GeV drove wakefields that accelerated electrons to 2 GeV in under 10 m of plasma. The AWAKE collaboration is now embarking on Run 2 with the main aims to demonstrate stable accelerating gradients of 0.5-1 GV/m, preserve emittance of the electron bunches during acceleration and develop plasma sources scalable to 100s of metres and beyond. By the end of Run 2, the AWAKE scheme should be able to provide electron beams for particle physics experiments and several possible experiments have already been evaluated. This article summarises the programme of AWAKE Run 2 and how it will be achieved as well as the possible application of the AWAKE scheme to novel particle physics experiments.
40.	Kabir, Md Alamgir, et al. (författare) CODE : A Moving-Window-Based Framework for Detecting Concept Drift in Software Defect Prediction 2022 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 14:12 Tidskriftsartikel (refereegranskat)abstract Concept drift (CD) refers to data distributions that may vary after a minimum stable period. CD negatively influences models’ performance of software defect prediction (SDP) trained on past datasets when applied to the new datasets. Based on previous studies of SDP, it is confirmed that the accuracy of prediction models is negatively affected due to changes in data distributions. Moreover, cross-version (CV) defect data are naturally asymmetric due to the nature of their class imbalance. In this paper, a moving window-based concept-drift detection (CODE) framework is proposed to detect CD in chronologically asymmetric defective datasets and to investigate the feasibility of alleviating CD from the data. The proposed CODE framework consists of four steps, in which the first pre-processes the defect datasets and forms CV chronological data, the second constructs the CV defect models, the third calculates the test statistics, and the fourth provides a hypothesis-test-based CD detection method. In prior studies of SDP, it is observed that in an effort to make the data more symmetric, class-rebalancing techniques are utilized, and this improves the prediction performance of the models. The ability of the CODE framework is demonstrated by conducting experiments on 36 versions of 10 software projects. Some of the key findings are: (1) Up to 50% of the chronological-defect datasets are drift-prone while applying the most popular classifiers used from the SDP literature. (2) The class-rebalancing techniques had a positive impact on the prediction performance for CVDP by correctly classifying the CV defective modules and detected CD by up to 31% on the resampled datasets.
41.	Kabir, Md Alamgir, et al. (författare) Cross-Version Software Defect Prediction Considering Concept Drift and Chronological Splitting 2023 Ingår i: Symmetry. - : Multidisciplinary Digital Publishing Institute (MDPI). - 2073-8994. ; 15:10 Tidskriftsartikel (refereegranskat)abstract Concept drift (CD) refers to a phenomenon where the data distribution within datasets changes over time, and this can have adverse effects on the performance of prediction models in software engineering (SE), including those used for tasks like cost estimation and defect prediction. Detecting CD in SE datasets is difficult, but important, because it identifies the need for retraining prediction models and in turn improves their performance. If the concept drift is caused by symmetric changes in the data distribution, the model adaptation process might need to account for this symmetry to maintain accurate predictions. This paper explores the impact of CD within the context of cross-version defect prediction (CVDP), aiming to enhance the reliability of prediction performance and to make the data more symmetric. A concept drift detection (CDD) approach is further proposed to identify data distributions that change over software versions. The proposed CDD framework consists of three stages: (i) data pre-processing for CD detection; (ii) notification of CD by triggering one of the three flags (i.e., CD, warning, and control); and (iii) providing guidance on when to update an existing model. Several experiments on 30 versions of seven software projects reveal the value of the proposed CDD. Some of the key findings of the proposed work include: (i) An exponential increase in the error-rate across different software versions is associated with CD. (ii) A moving-window approach to train defect prediction models on chronologically ordered defect data results in better CD detection than using all historical data with a large effect size (Formula presented.).
42.	Larsson, Matz, 1955-, et al. (författare) Why Are Most Humans Right-Handed? The Modified Fighting Hypothesis 2023 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 15:4 Forskningsöversikt (refereegranskat)abstract Humans show a population-level preference for using the right hand. The fighting hypothesis is an influential theory that suggests that left-handedness persists because its rarity provides a surprise advantage in fighting interactions, and that left-handedness is less frequent because it has a health cost. However, evidence for the health cost of left-handedness is unsubstantiated, leaving the greater frequency of right-handers unexplained. Research indicates that homicide may have been common in early hominins. We propose that the hand used to hold a weapon by early hominins could have influenced the outcome of a fight, due to the location of the heart and aorta. A left-handed unilateral grip exposes the more vulnerable left hemithorax towards an opponent, whereas a right-hand unilateral grip exposes the less vulnerable right hemithorax. Consequently, right-handed early ancestors, with a preference for using the right forelimb in combat, may have had a lower risk of a mortal wound, and a fighting advantage. This would explain their greater frequency. In accordance with the original fighting hypothesis, we also suggest that left-handed fighters have a surprise advantage when they are rare, explaining their persistence. We discuss evidence for the modified fighting hypothesis, its predictions, and ways to test the theory.
43.	Laxdal, Aron, et al. (författare) Born to Score? The Relationship between Left-Handedness and Success from the 7-Meter Line 2022 Ingår i: Symmetry. - Basel : MDPI. - 2073-8994. ; 14:10 Tidskriftsartikel (refereegranskat)abstract An asymmetry in the prevalence of left-handedness vs. right-handedness in society has supposedly resulted in negative frequency-dependent advantages for left-handers in interactive sports. The aim of this study was to test whether these advantages apply to handball by examining whether being left-handed is beneficial when executing 7 m shots, a highly unimanual movement. All 1,625 7 m shots at the men’s 2016–2022 European championships were analyzed using a Bayesian two-level analysis. While the results did not indicate that left-handers were more likely to score from any single 7 m shot, left-handers were overrepresented among the designated shooters compared to both the population as a whole (38% vs. 11.6%) and left-handers on any given handball team (38% vs. 25%). The implication here was that handedness plays no role in the outcome of 7 m shots at the world-class level, but handedness does appear to play a role in who becomes a world-class 7 m shooter. © 2022 by the authors.
44.	Lou, Xiaolong, et al. (författare) Asymmetric Free-Hand Interaction on a Large Display and Inspirations for Designing Natural User Interfaces 2022 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 14:5 Tidskriftsartikel (refereegranskat)abstract Hand motion sensing-based interaction, abbreviated as ‘free-hand interaction’, provides a natural and intuitive method for touch-less interaction on a large display. But due to inherent usability deficiencies of the unconventional size of the large display and the kinematic limitations of the user’s arm joint movement, a large display-based free-hand interaction is suspected to have different performance across the whole areas of the large display. To verify this, a multi-directional target pointing and selection experiment was designed and conducted based on the ISO 9241-9 evaluation criteria. Results show that (1) free-hand interaction in display areas close to the center of the body had a higher accuracy than that in peripheral-body areas; (2) free-hand interaction was asymmetric at the left side and the right side of the body. More specifically, left-hand interaction in the left-sided display area was more efficient and accurate than in the right-sided display area. For the right-hand interaction, the result was converse; moreover, (3) the dominant hand generated a higher interaction accuracy than the non-dominant hand. Lessons and strategies are discussed for designing user-friendly natural user interfaces in large displays-based interactive applications.
45.	Pazsit, Imre, 1948 (författare) Symmetries and Asymmetries in Branching Processes 2023 Ingår i: Symmetry. - 2073-8994. ; 15:6 Forskningsöversikt (refereegranskat)abstract As is known in stochastic particle theory, the same random process can be described by two different master equations for the evolution of the probability density, namely, by a forward or a backward master equation. These are the generalised analogues of the direct and adjoint equations of traditional transport theory. At the level of the first moment, these two equations show considerable resemblance to each other, but they become increasingly different with increasing moment order. The purpose of this paper is to demonstrate this increasing asymmetry and to discuss the underlying reasons. It is argued that since the reason of the different forms of the forward and the backward equations lies in the lack of invariance of the process to time reversal, the reason for the increasing asymmetry between the two forms for higher-order moments or processes with several variables (particle types) can be related to the increasing level of the violation of the invariance to time reversal, as is illustrated with some examples.
46.	Rodríguez, José Víctor, et al. (författare) Frequency-selective wallpaper for indoor interference reduction and MIMO capacity improvement 2020 Ingår i: Symmetry. - 2073-8994. ; 12:5 Tidskriftsartikel (refereegranskat)abstract This paper presents the design and features of frequency-selective wallpaper-based on periodic and symmetric metallic hexagons-intended to be attached to standard walls for filtering out 5GHz signals (e.g., IEEE 802.11a systems)without blocking other selected radio communication services (e.g., cellular mobile communication signals). It analyzes the characteristics of the radio channel-as found within standard indoor environments-with both regular walls and walls with the proposed frequency-selective wallpaper, examined using a ray-launching programfor single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems. This allows the harvesting of parameters, including channel capacity, power delay profile, and signal-to-interference ratio, for proper comparison between the two environments under study: with and without the presented wallpaper. The achieved results clearly show that the use of the proposed frequency-selective wallpaper in an indoor scenario reduces interference levels by an additional attenuation of up to 20 dB in comparison to an unpapered wall. Additionally, with MIMO systems, radio channel characteristics, such as capacity, are improved due to the increase in the magnitude of all singular values of the channel transfer matrix compared to the unpapered wall case, thereby leading to the existence of more relevant subchannels.
47.	Rosswog, Stephan, et al. (författare) Thinking Outside the Box : Numerical Relativity with Particles 2022 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 14:6 Tidskriftsartikel (refereegranskat)abstract The observation of gravitational waves from compact objects has now become an active part of observational astronomy. For a sound interpretation, one needs to compare such observations against detailed Numerical Relativity simulations, which are essential tools to explore the dynamics and physics of compact binary mergers. To date, essentially all simulation codes that solve the full set of Einstein’s equations are performed in the framework of Eulerian hydrodynamics. The exception is our recently developed Numerical Relativity code SPHINCS_BSSN which solves the commonly used BSSN formulation of the Einstein equations on a structured mesh and the matter equations via Lagrangian particles. We show here, for the first time, SPHINCS_BSSN neutron star merger simulations with piecewise polytropic approximations to four nuclear matter equations of state. In this set of neutron star merger simulations, we focus on perfectly symmetric binary systems that are irrotational and have 1.3 M⊙ masses. We introduce some further methodological refinements (a new way of steering dissipation, an improved particle–mesh mapping), and we explore the impact of the exponent that enters in the calculation of the thermal pressure contribution. We find that it leaves a noticeable imprint on the gravitational wave amplitude (calculated via both quadrupole approximation and the Ψ4 formalism) and has a noticeable impact on the amount of dynamic ejecta. Consistent with earlier findings, we only find a few times 10−3M⊙ as dynamic ejecta in the studied equal mass binary systems, with softer equations of state (which are more prone to shock formation) ejecting larger amounts of matter. In all of the cases, we see a credible high-velocity (∼0.5…0.7c) ejecta component of ∼10−4M⊙ that is launched at contact from the interface between the two neutron stars. Such a high-velocity component has been suggested to produce an early, blue precursor to the main kilonova emission, and it could also potentially cause a kilonova afterglow.
48.	Salaeh, Nureehan, et al. (författare) Long-Short Term Memory Technique for Monthly Rainfall Prediction in Thale Sap Songkhla River Basin, Thailand 2022 Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 14:8 Tidskriftsartikel (refereegranskat)abstract Rainfall is a primary factor for agricultural production, especially in a rainfed agricultural region. Its accurate prediction is therefore vital for planning and managing farmers’ plantations. Rainfall plays an important role in the symmetry of the water cycle, and many hydrological models use rainfall as one of their components. This paper aimed to investigate the applicability of six machine learning (ML) techniques (i.e., M5 model tree: (M5), random forest: (RF), support vector regression with polynomial (SVR-poly) and RBF kernels (SVR- RBF), multilayer perceptron (MLP), and long-short-term memory (LSTM) in predicting for multiple-month ahead of monthly rainfall. The experiment was set up for two weather gauged stations located in the Thale Sap Songkhla basin. The model development was carried out by (1) selecting input variables, (2) tuning hyperparameters, (3) investigating the influence of climate variables on monthly rainfall prediction, and (4) predicting monthly rainfall with multi-step-ahead prediction. Four statistical indicators including correlation coefficient (r), mean absolute error (MAE), root mean square error (RMSE), and overall index (OI) were used to assess the model’s effectiveness. The results revealed that large-scale climate variables, particularly sea surface temperature, were significant influence variables for rainfall prediction in the tropical climate region. For projections of the Thale Sap Songkhla basin as a whole, the LSTM model provided the highest performance for both gauged stations. The developed predictive rainfall model for two rain gauged stations provided an acceptable performance: r (0.74), MAE (86.31 mm), RMSE (129.11 mm), and OI (0.70) for 1 month ahead, r (0.72), MAE (91.39 mm), RMSE (133.66 mm), and OI (0.68) for 2 months ahead, and r (0.70), MAE (94.17 mm), RMSE (137.22 mm), and OI (0.66) for 3 months ahead.
49.	Shor, Oded, et al. (författare) Dendrographic Hologram Theory : Predictability of Relational Dynamics of the Event Universe and the Emergence of Time Arrow 2022 Ingår i: Symmetry. - : MDPI. - 2073-8994. ; 14:6 Tidskriftsartikel (refereegranskat)abstract Recently we started the development of Dendrographic Hologram Theory (DH-theory). It is based on the novel mathematical representation of the relational event universe (in the spirit of Smolin et al.). Elementary events are represented by branches of dendrograms, finite trees that are generated from data with clustering algorithms. In this context, we studied the dynamics of the event universe generated by the appearance of a new event. Generally, each new event can generate the complete reconstruction of the whole dendrogramic universe. However, we found (via numerical simulation) unexpected stability in this universe. Its events are coupled via the hierarchic relational structure, which is relatively stable even with respect to the random generation of new events. We also observed the regularity patterns in the location of new events on dendrograms. In the course of evolution, the dendrogram's complexity increases and determines the arrow of time in the event universe. We used the complexity measure from particle shape dynamics, which was shown to increase in both directions away from a Janus point and thus determine the arrow of time in symmetrical manner away from a Janus point. The particle shape dynamics theory is a relational theory with close ideological resemblance to DH-theory, as both rely on Mach's principle and Leibniz's relationalism and principles. By using the complexity measure on dendrograms and its p-adic string representation, we demonstrate the emergence of a time arrow from the p-adic zero-dimensional field, where space and time are absent.
50.	Spassky, Dmitry, et al. (författare) Enhancement of light output in ScxY1-xPO4:Eu3+ solid solutions 2020 Ingår i: Symmetry. - 2073-8994. ; 12:6 Tidskriftsartikel (refereegranskat)abstract The luminescence properties of ScxY1-xPO4:Eu3+ solid solutions have been studied under excitation by synchrotron radiation in the energy range of 4.5-50 eV. The luminescence originating from three different types of emission centers was observed, and the origin of the emission centers was determined. The light output of ScxY1-xPO4:Eu3+ was shown to depend non-linearly on the ratio of Sc and Y cations, whereas it is maximal in compounds with their equal content. The branching of the energy relaxation process between different emission centers is analyzed for the brightest Sc0.5Y0.5PO4:Eu3+ solid solution.

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