Miracle-dz/UniFAR-FTUs huggingface dataset:
An Excursion From Enumerative Geometry to Solving Systems of Polynomial Equations with Macaulay 2

Solving a system of polynomial equations is a ubiquitous problem in the applications of mathematics. Until recently, it has been hopeless to find explicit solutions to such systems, and mathematics has instead developed deep and powerful theories about the solutions to polynomial equations. Enumerative Geometry is concerned with counting the number of solutions when the polynomials come from a geometric situation and Intersection Theory gives methods to accomplish the enumeration. We use Macaulay 2 to investigate some problems from enumerative geometry, illustrating some applications of symbolic computation to this important problem of solving systems of polynomial equations. Besides enumerating solutions to the resulting polynomial systems, which include overdetermined, deficient, and improper systems, we address the important question of real solutions to these geometric problems. The text contains evaluated Macaulay 2 code to illuminate the discussion. This is intended as a chapter in a book on applications of Macaulay 2 to problems in mathematics. While this chapter is largely expository, the results in the last section concerning lines tangent to quadrics are new.
Ages for Globular Clusters in the Outer Galactic Halo: The Second-Parameter Clusters Palomar 3, Palomar 4, and Eridanus

We have used the Wide Field Planetary Camera 2 on the Hubble Space Telescope to obtain photometry of the outer halo globular clusters Palomar 3, Palomar 4, and Eridanus. These three are classic examples of the "second-parameter" anomaly because of their red horizontal-branch morphologies in combination with their low-to-intermediate metallicities. Our color-magnitude diagrams (CMDs) inV,V - I reach Vlim ≃ 27.0, clearly delineating the subgiant and turnoff regions and about 3 mag of the unevolved main sequences. The slopes and dereddened colors of the giant branches are consistent with published [Fe/H] estimates that rank the clusters (Pal 3, Eridanus, Pal 4) in order of increasing metallicity, with all three falling near or between the abundance values of the classic nearby halo clusters M3 and M5. Differential fits of their CMDs are made to each other and to M3 and M5 for relative age determinations. We find that the three outer halo cluster CMDs differ from the nearby clusters in a way that is consistent with their being younger by ∼1.5–2 Gyr, if we have correctly estimated the clusters' chemical abundance ratios. Conversely, the inferred age difference could be smaller (≲1 Gyr) if either [Fe/H] or [α/Fe] for the outer halo clusters is significantly lower than we have assumed. Possible age spreads of order 1 Gyr among both the nearby and outer halo clusters may also be present.
Unquenched large orbital magnetic moment in NiO

Magnetic properties of NiO are investigated by incorporating the spin-orbit interaction in the LSDA+U scheme. It is found that the large part of orbital moment remains unquenched in NiO. The orbital moment contributes about mu_L = 0.29 mu_B to the total magnetic moment of M = 1.93 mu_B, as leads to the orbital-to-spin angular momentum ratio of L/S = 0.36. The theoretical values are in good agreement with recent magnetic X-ray scattering measurements.
Fireballs in dense stellar regions as an explanation of gamma-ray bursts

We study a cosmological scenario for gamma ray bursts (GRBs) where relativistic flows interact with dense radiation fields. It is shown that this scenario is plausible in very dense stellar regions which are known to exist in collapsed cores of globular clusters or dense nuclei of galaxies. It yields a correct quantitative description of the temporal behavior of GRBs. Several other properties of GRBs are easily explained.
A 33 GHz Survey of Local Major Mergers: Estimating the Sizes of the Energetically Dominant Regions from High-resolution Measurements of the Radio Continuum

We present Very Large Array observations of the 33 GHz radio continuum emission from 22 local ultraluminous and luminous infrared (IR) galaxies (U/LIRGs). These observations have spatial (angular) resolutions of 30–720 pc (0.″07–0.″67) in a part of the spectrum that is likely to be optically thin. This allows us to estimate the size of the energetically dominant regions. We find half-light radii from 30 pc to 1.7 kpc. The 33 GHz flux density correlates well with the IR emission, and we take these sizes as indicative of the size of the region that produces most of the energy. Combining our 33 GHz sizes with unresolved measurements, we estimate the IR luminosity and star formation rate per area and the molecular gas surface and volume densities. These quantities span a wide range (4 dex) and include some of the highest values measured for any galaxy (e.g., ). At least 13 sources appear Compton thick ( ). Consistent with previous work, contrasting these data with observations of normal disk galaxies suggests a nonlinear and likely multivalued relation between star formation rate and molecular gas surface density, though this result depends on the adopted CO-to-H2 conversion factor and the assumption that our 33 GHz sizes apply to the gas. Eleven sources appear to exceed the luminosity surface density predicted for starbursts supported by radiation pressure and supernova feedback; however, we note the need for more detailed observations of the inner disk structure. U/LIRGs with higher surface brightness exhibit stronger [C ii] 158 μm deficits, consistent with the suggestion that high energy densities drive this phenomenon.
BER Performance for Downlink NOMA

Non-Orthogonal Multiple Access (NOMA) is a possible multiple access option for the coming generation of wireless communications that has a higher SE and takes advantage of network resource reuse. As a result, academic and industry researchers have recently looked into the error performance and capacity of NOMA schemes. Because of the non-orthogonal nature of NOMA technique, the main disadvantage is users’ interference, which is normally mitigated using interference cancellation techniques such as Successive Interference Cancellation (SIC) at the receivers. In this paper, we investigate the performance of NOMA and the power allocation strategy utilized on BER. We used BASK modulation with Rayleigh fading channel and AWGN channel. The numerical results show that NOMA works well in equal and different distances between users.
Modeling and Analysis in Peer-To-Peer Botnet with Virtual Patching and Quarantine Strategy

Botnets, especially peer-to-peer (P2P) botnets have become the root because of many Internet attacks recently. To effectively suppress P2P botnets, quarantine and virtual patching strategy are proposed and two dynamical models (SIIQR model and SIIQPR model) are given based on the SIIR model. The two models can examine the impact of different containment strategies on the growth of the P2P botnets. In addition, the stability of equilibrium is investigated and the basic reproduction number is obtained, which governs whether or not P2P botnets are extinct. The virtual patching strategy and quarantine strategy can effectively contain the propagation of the P2P botnets. Numerical and simulation results show the effectiveness of our models, larger infected rate, and larger deploying rate of virtual patching can control the number of infected hosts more effectively.
Inner Structure of CME Shock Fronts Revealed by the Electromotive Force and Turbulent Transport Coefficients in Helios-2 Observations

Electromotive force is an essential quantity in dynamo theory. During a coronal mass ejection (CME), magnetic helicity gets decoupled from the Sun and advected into the heliosphere with the solar wind. Eventually, a heliospheric magnetic transient event might pass by a spacecraft, such as the Helios space observatories. Our aim is to investigate the electromotive force, the kinetic helicity effect (α term), the turbulent diffusion (β term), and the cross-helicity effect (γ term) in the inner heliosphere below 1 au. We set up a one-dimensional model of the solar wind velocity and magnetic field for a hypothetic interplanetary CME. Because turbulent structures within the solar wind evolve much slower than this structure needs to pass by the spacecraft, we use a reduced curl operator to compute the current density and vorticity. We test our CME shock-front model against an observed magnetic transient that passes by the Helios-2 spacecraft. At the peak of the fluctuations in this event we find strongly enhanced α, β, and γ terms, as well as a strong peak in the total electromotive force. Our method allows us to automatically identify magnetic transient events from any in situ spacecraft observations that contain magnetic field and plasma velocity data of the solar wind.
Planar Hall effect in the type-II Dirac semimetal 
VAl3

The study of electronic properties in topological systems is one of the most fascinating topics in condensed matter physics, which has generated enormous interests in recent times. New materials are frequently being proposed and investigated to identify their non-trivial band structure. While sophisticated techniques such as angle-resolved photoemission spectroscopy have become popular to map the energy-momentum relation, the transport experiments lack any direct confirmation of Dirac and Weyl fermions in a system. From band structure calculations, VAl$_{3}$ has been proposed to be a type II topological Dirac semimetal. This material represents a large family of isostructural compounds, all having similar electronic band structure and is an ideal system to explore the rich physics of Lorentz symmetry violating Dirac fermions. In this work, we present a detailed analysis on the magnetotransport properties of VAl$_{3}$. A large, non-saturating magnetoresistance has been observed. Hall resistivity reveals the presence of two types of charge carriers with high mobility. Our measurements show a large planar Hall effect in this material, which is robust and can be easily detectable up to high temperature. This phenomenon originates from the relativistic chiral anomaly and non-trivial Berry curvature, which validates the theoretical prediction of the Dirac semimetal phase in VAl$_{3}$.
Impact of simulated 1/f noise for HI intensity mapping experiments

Cosmology has entered an era where the experimental limitations are not due to instrumental sensitivity but instead due to inherent systematic uncertainties in the instrumentation and data analysis methods. The field of neutral hydrogen (HI) intensity mapping (IM) is still maturing, however early attempts are already systematics limited. One such systematic limitation is 1/f noise, which largely originates within the instrumentation and manifests as multiplicative gain fluctuations. To date, there has been little discussion about the possible impact of 1/f noise on upcoming single-dish HI IM experiments such as BINGO (Baryonic Acoustic Oscillations from Integrated Neutral Gas Observations), FAST (Five hundred metre Aperture Spherical Telescope), or SKA (Square Kilometre Array). Presented in this work are Monte Carlo end-to-end simulations of a 30 d HI IM survey using the SKA–MID array covering a bandwidth of 950 and 1410 MHz. These simulations extend 1/f noise models to include not just temporal fluctuations, but also correlated gain fluctuations across the receiver bandpass. The power spectral density of the spectral gain fluctuations are modelled as a power law, and characterized by a parameter β. It is found that the degree of 1/f noise frequency correlation will be critical to the success of HI IM experiments. Small values of β (β < 0.25) or high correlation is preferred as this is more easily removed using current component separation techniques. Spectral index of temporal fluctuations (α) is also found to have a large impact on signal-to-noise ratio. Telescope slew speed has a smaller impact, and a scan speed of 1 deg s^−1 should be sufficient for an HI IM survey with the SKA.
Unifying linear dimensionality reduction

Linear dimensionality reduction methods are a cornerstone of analyzing high dimensional data, due to their simple geometric interpretations and typically attractive computational properties. These methods capture many data features of interest, such as covariance, dynamical structure, correlation between data sets, input-output relationships, and margin between data classes. Methods have been developed with a variety of names and motivations in many fields, and perhaps as a result the deeper connections between all these methods have not been understood. Here we unify methods from this disparate literature as optimization programs over matrix manifolds. We discuss principal component analysis, factor analysis, linear multidimensional scaling, Fisher's linear discriminant analysis, canonical correlations analysis, maximum autocorrelation factors, slow feature analysis, undercomplete independent component analysis, linear regression, and more. This optimization framework helps elucidate some rarely discussed shortcomings of well-known methods, such as the suboptimality of certain eigenvector solutions. Modern techniques for optimization over matrix manifolds enable a generic linear dimensionality reduction solver, which accepts as input data and an objective to be optimized, and returns, as output, an optimal low-dimensional projection of the data. This optimization framework further allows rapid development of novel variants of classical methods, which we demonstrate here by creating an orthogonal-projection canonical correlations analysis. More broadly, we suggest that our generic linear dimensionality reduction solver can move linear dimensionality reduction toward becoming a blackbox, objective-agnostic numerical technology.
UvA-DARE (Digital Academic Repository) Struggling and Success in Web Search

Web searchers sometimes struggle to ﬁnd relevant information. Struggling leads to frustrating and dissatisfying search experiences, even if searchers ultimately meet their search objectives. Better understanding of search tasks where people struggle is important in improving search systems. We address this important issue using a mixed methods study using large-scale logs, crowd-sourced labeling, and predictive modeling. We analyze anonymized search logs from the Microsoft Bing Web search engine to characterize aspects of struggling searches and better explain the relationship between struggling and search success. To broaden our understanding of the struggling process beyond the behavioral signals in log data, we develop and utilize a crowd-sourced labeling methodology. We collect third-party judgments about why searchers appear to struggle and, if appropriate, where in the search task it became clear to the judges that searches would succeed (i.e., the pivotal query). We use our ﬁndings to propose ways in which systems can help searchers reduce struggling. Key components of such support are algorithms that accurately predict the nature of future actions and their anticipated impact on search outcomes. Our ﬁndings have implications for the design of search systems that help searchers struggle less and succeed more.
Power control and resource allocation for return on investment maximization in cross‐modal communications

Multi‐modal services will become the mainstream in future applications, including video, audio, and haptic flows. In multi‐modal services, video and audio primarily require high‐rate transmission, while haptic flow requires ultra‐high reliability and ultra‐low latency transmission, which imposes unprecedented challenges on the network. To improve the transmission efficiency of multi‐modal services, this article proposes a cross‐modal communication architecture in the cloud radio access network based on network slicing technology. First, we take the data rate and transmission latency of video, audio, and haptic flows contents as the quality of service (QoS) parameters, and send different modes of flows into varying slices for transmission. Second, to transmit the cross‐modal services efficiently while saving communication resources as many as possible, we define our optimization goal as the form of return on investment (ROI), that is, we aim to maximize the return of QoS parameters under the limited investment in communication resources. Third, we propose a two‐stage framework to solve this ROI maximization problem. In the first stage, we propose the power control gradient assisted binary search algorithm to solve the power control problem, which can achieve the optimization of data rate and transmission latency and obtain the suitable QoS. Then, in the second stage, we introduce the network slicing ant colony optimization algorithm to solve the slice resource allocation problem, and get the largest possible ROI. The simulation results verify the effectiveness of the proposed cross‐modal communication architecture, and prove the optimum of the proposed algorithm in terms of ROI compared to some existing algorithms, such as the reverse labeling Dijkstra algorithm, the delay acceptance algorithm, and the random searching algorithm.
A New Cytotoxic Ceramide from Dalbergia boehmii Taub. Stem Bark

Background: Dalbergia boehmii (Leguminosae) , is a medicinal plant used in the Northen part of Cameroon, against digestive tract diseases and fever. Objectives: This work which is part of the search for bioactive molecules through natural products, aimed to isolate, characterize and evaluate the cytotoxicity of compounds from D. boehmii . Materials and Methods: Chemical investigations were carrying out on stem barks of Dalbergia boehmii using chromatographic techniques. Structures elucidation of isolated compounds were done using 1D and 2D NMR as well as EI-MS and literature data. Some isolated compounds were evaluated in vitro against MCF-7 cell lines for their cytotoxicity activity, using the MTT colorimetric method. Results: The chemical investigation leaded to the isolation of a new ceramide derivative named Dalbergiamide (1), a triterpene identified as olean-12-ene-3,11-dione (2) isolated here for the first time from Dalbergia genus, along with two known compounds, glucoside 3-O - β - D-sitosterol (3) and glucoside 3-O - β -D-stigmasterol (4). Compounds 1 and 2 were found to be cytotoxic at 50 μM with IC 50 value of 17.13 μM and 35.52 ± 2.95 μM respectively. Conclusion: These promising results suggested more in-depth studies should be carried out on this plant in order to assess its potential in the fight against cancer.
Feeling exhausted and isolated? The connections between university students’ remote teaching and learning experiences, motivation, and psychological well-being during the COVID-19 pandemic

Abstract We examined university students’ experiences of remote teaching and learning, how the experiences are associated with well-being, and whether those associations differ according to motivation. Using latent variable modelling, we classified Finnish university students (N = 2686) based on their expectancy-value-cost profiles, compared latent means, and tested whether the predictions varied across profiles. Six expectancy-value-cost profiles were identified: moderately motivated, utility-oriented, disengaged, indifferent, positively ambitious, and struggling ambitious. Overall, positively ambitious students seemed most adaptive in terms of their study experiences and well-being. Similarly across the profiles, engagement was predicted positively by the evaluation of remote teaching and negatively by experienced strain, exhaustion positively by the evaluation of teaching and strain, and depressive symptoms positively by strain and sense of alienation. Findings suggest that subjective experiences of remote teaching and learning during the pandemic contribute to students’ well-being in unique ways and that distinct motivational mindsets may buffer against the negative outcomes.
Evaluation of Cytochrome P4502E1 mRNA Expression and Its Effects in Antioxidant Defenses, and Cell Toxicity in Printing Workers

Background: Cytochrome P4502E1 (CYP2E1) metabolizes environmental toxins, however, compound metabolism can produce oxidative stress, causing in-cell toxicity and sometimes transformation. Aim: To evaluate CYP2E1 gene expression and its effects in antioxidant defenses, and cell toxicity in printing workers. Methods: The hierarchical method of health and chemical risk was used to evaluate chemical exposure in workplace. Blood samples and buccal epithelial cells were obtained from printing workers, and workers without any history of occupational exposure to chemicals (control group). Gene expression of CYP2E1, and antioxidant enzymes Superoxide dismutase (SOD) and Catalase (CAT) from leukocytes were evaluated. Hematic analysis and cell-free DNA from plasma were analyzed. Frequencies of cells with micronuclei (MN) and nuclear abnormalities from buccal epithelial cells were explored. Results: Evaluation of chemical exposure in working place demonstrated that ethyl alcohol, isopropyl alcohol, and isophorone represent 91% of the accumulated potential risk. CYP2E1 expression showed a 2.5-fold overexpression in the printing workers compared to the control group. SOD expression showed a 0.5-fold lower level in the printing workers than the control group, and CAT expression showed no differences between groups. Lower red blood cell and platelet values were detected in the printing workers than in the control group, and cell-free DNA plasma concentration was 3-fold higher in the printing workers than in the control group. The printing workers showed a higher frequency of cells with MN and nuclear anomalies than the control group. Conclusion: CYP2E1 overexpression triggers antioxidant defenses and toxic cell effects in printing workers.
Effect of S-PRG particles on demineralization and remineralization of dentin: a clinical case report

It is known that the production of acid by oral bacteria dissolves mineral phases on the enamel surface, facilitating the formation of dental caries, with lactic acid being the main cause of caries, followed by acetic and propionic acids. Fluoride-containing materials play an important role in preventing demineralization and remineralization and these are widely used in dentistry. Although the benefits of fluoride in terms of reducing the incidence of dental caries are well established, fluoride cannot prevent caries in all patients; thus, the development of new anti-caries agents with remineralization properties is necessary. Thus, new products are emerging with this purpose and in this article, a material with Surface Pre Reacted Glass ionomer (S-PRG) particles will be addressed, these are produced by the acid-base reaction of fluoroboroaluminosilicate glass and polyacrylic acid and are known to have a potential to release 06 ions, such as Al, B, Na, Si, Sr and F, where these released ions played an important role in pH neutralization, leading to inhibition of enamel demineralization early point, where strontium (Sr) is becoming as a strong inducer of dentin matrix remineralization. Thus, this work aimed to demonstrate with a clinical case using S-PRG materials that can become an ally in the remineralization of the dental element. In conclusion, among the innovations that promote the concept of preventive and minimally invasive management, the bioactivity containing S-PRG can avoid invasive and definitive procedures such as tooth extraction.