Miracle-dz/UniFAR-FTUs huggingface dataset:
A Multi-Rate Approach for Nonlinear Pre-Distortion Using End-to-End Deep Learning in IM-DD Systems

Modern intra-data center (IDC) interconnects leverage robust and low-cost intensity modulation (IM) and direct detection (DD) optical links, based on multimode fibers (MMFs) and vertical-cavity surface-emitting lasers (VCSELs). Current solutions, based on on-off keying (OOK) modulations, reach up to 25-50 Gbps per lane over nearly 100 meters. The actual target for IDCs is to increase VCSEL-MMF links capacity up to 100 Gbps, using PAM-4 on the same devices. To counteract the consequent linear and nonlinear distortions affecting the transmitted signals, an effective solution is to exploit digital signal processing (DSP). In this manuscript, we propose a novel method to optimize a nonlinear artificial neural network (ANN) digital pre-distorter (DPD), based on End-to-end (E2E) learning, that, trained jointly with a Feed-Forward Equalizer (FFE), fulfills physical amplitude constraints and handles different ratio between the sampling rates incurring along with an optical IM-DD system. We indeed propose an E2E ANN system operating simultaneously at different sampling frequencies. We moreover propose in our training method a substitution to the time-domain injection of the receiver noise in the system with an additive regularization term in the FFE gradient loss. We experimentally show the advantages of our proposed DPD comparing the bit error rate (BER) performance against the same scenario without DPD. We assess the gain in terms of Gross Bit Rate and Optical Path Loss (OPL), at given BER targets, for different fiber lengths.
Experiences of family members caring for a sibling with mental illness in Giyani, Limpopo

Background Mental illness is a serious condition affecting the diagnosed individual and all family members. Family members caring for a sibling with mental illness encounter severe challenges, which, if unresolved, becomes a burden they carry for the rest of their lives. Objectives The purpose of the study was to describe family members’ experiences caring for a sibling with mental illness in Giyani. Method A qualitative, exploratory, descriptive and contextual research design was used. Eight family members caring for a sibling with mental illness were purposively sampled. Data were collected through in-depth phenomenological interviews, and data were analysed using thematic coding, and an external coder was consulted. Results The study’s findings revealed that family members caring for a sibling with mental illness experienced significant challenges. The three themes that emerged after data analysis were the following: caring for a sibling with mental illness was an overwhelming experience; family members experience emotional instability as a result of caring for their sibling with mental illness and family members need support in caring for their sibling with mental illness. Conclusion The findings indicated that family members need support in caring for a sibling with mental illness. Family members would cope better with support from extended family, healthcare professionals in mental health and the community; this will reduce the burden of caring for a sibling with mental for family members. Furthermore, the availability of resources can assist in facilitating family members’ mental health. Contribution This study could make an impact in psychiatric nursing practice, nursing education in promotion of support for family members for a sibling with mental illness.
Internet usage behavior among agricultural students in Haryana

Internet is a versatile tool used by the students for multiple purposes. A study was carried out to find the internet usage behavior among the students of CCS Haryana Agricultural University, Hisar during 2018-2019. The data were collected from 200 respondents using structured interview schedule, as personal interview schedule reduces the bias of respondents and help in collection of credible data. Findings revealed that majority of the students (71.00%) used the internet daily for more than 2 h at their hostel. Most of the students (82.50%) used internet for entertainment purpose compared to academic and professional purpose. Hence, concerted efforts like; formal education of ICT tools, easy access and usage, cost effectiveness measures, etc. have to be made by the policy makers, administrators and academicians concerned to make necessary improvements in planning and implementing ICTs strategies, so that students must be made aware of use of internet and promote interest among them for its optimum academic and professional use. Study also revealed that age, education, medium of schooling, schooling, parental income, family education, scientism, job preference, annual expenditure, mass media exposure, information seeking behavior and risk orientation with their usage behavior of internet had positive and significant correlation at 0.05 level of probability.
What is geometry in quantum theory

In this scientiﬁc preface to the ﬁrst issue of International Journal of Geometric Methods in Modern Physics 1 , we brieﬂy survey some peculiarities of geometric techniques in quantum models. Contemporary quantum theory meets an explosion of diﬀerent types of quantization. Some of them (geometric quantization, deformation quantization, noncommutative geometry, topological ﬁeld theory etc.)
Mass- and Energy-Conserved Numerical Schemes for Nonlinear Schr ¨odinger Equations

In this paper, we propose a family of time-stepping schemes for approximating general nonlinear Schrodinger equations. The proposed schemes all satisfy both mass conservation and energy conservation. Truncation and dispersion error analyses are provided for each proposed scheme. Efficient fixed-point iterative solvers are also constructed to solve the resulting nonlinear discrete problems. As a byproduct, an efficient one-step implementation of the BDF schemes is obtained as well. Extensive numerical experiments are presented to demonstrate the convergence and the capability of capturing the blow-up phenomenon of the proposed schemes.
Symplectic involutions of K3[n]$K3^{[n]}$ type and Kummer n$n$ type manifolds

In this paper, we describe the fixed locus of a symplectic involution on a hyper‐Kähler manifold of type K3[n]$K3^{[n]}$ or of Kummer n$n$ type. We prove that the fixed locus consists of finitely many copies of deformations of Hilbert schemes of K3$K3$ surfaces of lower dimensions and isolated fixed points.
Variability-Controlled HfZrO2 Ferroelectric Tunnel Junctions for Reservoir Computing

We propose reservoir computing (RC), a framework for constructing recurrent neural networks (RNNs) with simple training rule, using ferroelectric tunnel junction (FTJ) crossbar array. Not only the weights of connection between reservoir layer and output layer need to be trained, but also random fixed weights within reservoir layer can be realized by the conductance of FTJs. Random weights within reservoir layers have optimal variability, which is dependent not on the type of the distribution but on the reservoir size. Optimal variability can be attained by device-to-device variability in FTJs together with analog converters on the wordlines and the bitlines. Analog resistive switching characteristics in FTJs can also realize the weights connected to output layer, which need to be trained. Furthermore, device-to-device variability in Hf $_{{1}- {x}}$ ZrxO2 (HZO) FTJ is extensively investigated. Taking into account the low current operation in FTJs, RC with FTJ crossbar array is a potential candidate for neuromorphic computing system with low power consumption.
Conformal symmetry classes for pp-wave spacetimes

We determine conformal symmetry classes for the pp-wave spacetimes. This refines the isometry classification scheme given by Sippel and Goenner (1986 Gen. Rel. Grav. 18 1229). It is shown that every conformal Killing vector for the null fluid type N pp-wave spacetimes is a conformal Ricci collineation. The maximum number of proper non-special conformal Killing vectors in a type N pp-wave spacetime is shown to be three, and we determine the form of a particular set of type N pp-wave spacetimes admitting such conformal Killing vectors. We determine the conformal symmetries of each type N isometry class of Sippel and Goenner and present new isometry classes.
A Fitting Recognition Approach Combining Depth-Attention YOLOv5 and Prior Synthetic Dataset

To address power transmission lines (PTLs) traveling through complex environments leading to misdetections and omissions in fitting recognition using cameras, we propose a fitting recognition approach combining depth-attention YOLOv5 and prior synthetic dataset to improve the validity of fitting recognition. First, datasets with inspection features are automatically synthesized based on prior series data, achieving better results with a smaller data volume for the deep learning model and reducing the cost of obtaining fitting datasets. Next, a unique data collection mode is proposed using a developed flying-walking power transmission line inspection robot (FPTLIR) as the acquisition platform. The obtained image data in this collection mode has obvious time-space, stability, and depth difference, fusing the two data types in the deep learning model to improve the accuracy. Finally, a depth-attention mechanism is proposed to change the attention on the images with depth information, reducing the probability of model misdetection and omission. Test field experiments results show that compared with YOLOv5, the mAP5095 (mean average precision on step size 0.05 for thresholds from 0.5 to 0.95) of our depth-attention YOLOv5 model for fitting is 68.1%, the recall is 98.3%, and the precision is 98.3%. Among them, AP, recall, and precision increased by 5.2%, 4.8%, and 4.1%, respectively. Test field experiments verify the feasibility of the depth-attention YOLOv5. Line field experiments results show that the mAP5095 of our depth-attention YOLOv5 model for fittings is 64.6%, and the mAPs of each class are improved compared with other attention mechanisms. The inference speed of depth-attention YOLOv5 is 3ms slower than the standard YOLOv5 model and 10ms to 15ms faster than other attention mechanisms, verifying the validity of the depth-attention YOLOv5. The proposed approach improves the accuracy of the fitting recognition on PTLs, providing a recognition and localization basis for the automation and intelligence of inspection robots.
Random constraint sampling and duality for convex optimization

We are interested in solving convex optimization problems with large numbers of constraints. Randomized algorithms, such as random constraint sampling, have been very successful in giving nearly optimal solutions to such problems. In this paper, we combine random constraint sampling with the classical primal-dual algorithm for convex optimization problems with large numbers of constraints, and we give a convergence rate analysis. We then report numerical experiments that verify the effectiveness of this algorithm.
On The Link Between Emotion, Attention And Content In Virtual Immersive Environments

While immersive media have been shown to generate more intense emotions, saliency information has been shown to be a key component for the assessment of their quality, owing to the various portions of the sphere (viewports) a user can attend. In this article, we investigate the tri-partite connection between user attention, user emotion and visual content in immersive environments. To do so, we present a new dataset enabling the analysis of different types of saliency, both low-level and high-level, in connection with the user’s state in 360◦ videos. Head and gaze movements are recorded along with self-reports and continuous physiological measurements of emotions. We then study how the accuracy of saliency estimators in predicting user attention depends on user-reported and physiologically-sensed emotional perceptions. Our results show that high-level saliency better predicts user attention for higher levels of arousal. We discuss how this work serves as a first step to understand and predict user attention and intents in immersive interactive environments.
Can we ever distinguish between quintessence and a cosmological constant

Many ambitious experiments have been proposed to constrain dark energy and detect its evolution. At the present, observational constraints are consistent with a cosmological constant and there is no firm evidence for any evolution in the dark energy equation of state w. In this paper, we pose the following question: suppose that future dark energy surveys constrain w at low redshift to be consistent with -1 to a percent level accuracy, what are the implications for models of dynamical dark energy? We investigate this problem in a model-independent way by following quintessence field trajectories in 'energy' phase-space. Attractor dynamics in this phase-space leads to two classes of acceptable models: (1) models with flat potentials, i.e. an effective cosmological constant, and (2) models with potentials that suddenly flatten with a characteristic kink. The prospect of further constraining the second class of models from distance measurements and fluctuation growth rates at low redshift (z < or approx. 3) seems poor. However, in some models of this second class, the dark energy makes a significant contribution to the total energy density at high redshift. Such models can be further constrained from observation of the cosmic microwave background anisotropies and from primordial nucleosynthesis. Itmore » is possible, therefore, to construct models in which the dark energy at high redshift causes observable effects, even if future dark energy surveys constrain w at low redshift to be consistent with -1 to high precision. « less
On Oscillations of Solutions of the Fourth-Order Thin Film Equation Near Heteroclinic Bifurcation Point

It is shown that solutions of the Cauchy for the fourth-order thin film equation becomes non-oscillatory and non-sign-changing precisely at and above the heteroclinic bifurcation point n=1.75987. , so that, possibly, these solutions begin to coincide with nonnegative solutions of a standard and well-known free-boundary problem.
Realizable Classes and Embedding Problems

Let $K$ be a number field with ring of integers $\mathcal{O}_K$ and let $G$ be a finite group. Given a $G$-Galois $K$-algebra $K_h$, let $\mathcal{O}_h$ denote its ring of integers. If $K_h/K$ is tame, then a classical theorem of E. Noether implies that $\mathcal{O}_h$ is locally free over $\mathcal{O}_KG$ and hence defines a class in the locally free class group of $\mathcal{O}_KG$. For $G$ abelian, by combining the work of J. Brinkhuis and L. McCulloh, we prove that the structure of the collection of all such classes is related to the study of embedding problems.
TWISTED TOPOLOGICAL GRAPH ALGEBRAS

We define the notion of a twisted topological graph algebra associated to a topological graph and a $1$-cocycle on its edge set. We prove a stronger version of a Vasselli's result. We expand Katsura's results to study twisted topological graph algebras. We prove a version of the Cuntz-Krieger uniqueness theorem, describe the gauge-invariant ideal structure. We find that a twisted topological graph algebra is simple if and only if the corresponding untwisted one is simple.
A Pilot Study on the Prediction of Non-Contact Muscle Injuries Based on ACTN3 R577X and ACE I/D Polymorphisms in Professional Soccer Athletes

Muscle injuries are among the main reasons for medical leavings of soccer athletes, being a major concern within professional teams and their prevention associated with sport success. Several factors are associated with a greater predisposition to injury, and genetic background is increasingly being investigated. The aim of this study was to analyze whether ACTN3 R577X and ACE I/D polymorphisms are predictors of the incidence and severity of muscle injury in professional soccer athletes from Brazil, individually and in association. Eighty-three professional athletes from the first and second divisions of the Brazilian Championship were evaluated regarding the polymorphisms through blood samples. Nighty-nine muscle injuries were identified during the seasons of 2018, 2019 and 2020 and categorized according to severity. ACTN3 XX individuals had a higher frequency of severe injuries compared to the RX and RR genotypes (p = 0.001), and in the dominant model (compared to RX+RR), with p < 0.001. The trend p-value test showed an increased number of injuries/season following the order XX > RX > RR (p = 0.045). Those with the ACE II genotype had almost 2 fold the number of injuries per season compared to those with the ID+DD genotypes (p = 0.03). Logistic regression showed that the polymorphisms are predictors of the development of severe injury (ACTN3 R577X model with p = 0.004, R2: 0.259; ACE I/D model with p = 0.045, R2: 0.163), where ACTN3 XX individuals were more likely to suffer from severe injury (OR: 5.141, 95% CI: 1.472–17.961, p = 0.010). The combination of the ACTN3 577X allele and the ACE II genotype showed an increased number of injuries per season, enhanced by 100% (1.682 injuries/season versus 0.868 injuries/season, p = 0.016). Our findings suggest that both polymorphisms ACTN3 R577X and ACE I/D (and their interaction) are associated with the susceptibility and severity of non-contact muscle injury in soccer players.
Bubble dynamics in N dimensions

Cavitation and bubble dynamics are central concepts in engineering, the natural sciences, and the mathematics of fluid mechanics. Due to the nonlinear nature of their dynamics, the governing equations are not fully solvable. Here, the dynamics of a spherical bubble in an N-dimensional fluid are discussed in the hope that examining bubble behavior in N dimensions will add insight to their behavior in three dimensions. Several canonical results in bubble dynamics are re-derived, including the Rayleigh collapse time, the Rayleigh-Plesset equation, and the Minnaert frequency. Recent analytical approximations to the Rayleigh collapse are discussed, and the N-dimensional generalization is used to resolve a known discrepancy. Numerical simulations are used to examine the onset of nonlinear behavior. Overall, the dynamics of bubbles are faster at higher dimensions, with nonlinear behavior occurring at lower strain. Several features are found to be unique to three dimensions, including the trend of nonlinear behav.
Degrees of self-maps of products

Every closed oriented manifold $M$ is associated with a set of integers $D(M)$, the set of self-mapping degrees of $M$. In this paper we investigate whether a product $M\times N$ admits a self-map of degree $d$, when neither $D(M)$ nor $D(N)$ contains $d$. We find sufficient conditions so that $D(M\times N)$ contains exactly the products of the elements of $D(M)$ with the elements of $D(N)$. As a consequence, we obtain manifolds $M\times N$ that do not admit self-maps of degree $-1$ (strongly chiral), that have finite sets of self-mapping degrees (inflexible) and that do not admit any self-map of degree $dp$ for a prime number $p$. Furthermore we obtain a characterization of odd-dimensional strongly chiral hyperbolic manifolds in terms of self-mapping degrees of their products.
FEM and CIP-FEM for Helmholtz Equation with High Wave Number and PML truncation

The Helmholtz scattering problem with high wave number is truncated by the perfectly matched layer (PML) technique and then discretized by the linear continuous interior penalty finite element method (CIP-FEM). It is proved that the truncated PML problem satisfies the inf--sup condition with inf--sup constant of order $O(k^{-1})$. Stability and convergence of the truncated PML problem are discussed. In particular, the convergence rate is twice of the previous result. The preasymptotic error estimates in the energy norm of the linear CIP-FEM as well as FEM are proved to be $C_1kh+C_2k^3h^2$ under the mesh condition that $k^3h^2$ is sufficiently small. Numerical tests are provided to illustrate the preasymptotic error estimates and show that the penalty parameter in the CIP-FEM may be tuned to reduce greatly the pollution error.
Vanishing Abelian integrals on zero‐dimensional cycles

In this paper, we study conditions for the vanishing of Abelian integrals on families of zero‐dimensional cycles. That is, for any rational function f(z), characterize all rational functions g(z) and zero‐sum integers {ni} such that the function t↦∑ nig(zi(t)) vanishes identically. Here zi(t) are continuously depending roots of f(z)−t. We introduce a notion of (un)balanced cycles. Our main result is an inductive solution of the problem of vanishing of Abelian integrals when f, g are polynomials on a family of zero‐dimensional cycles under the assumption that the family of cycles we consider as well as all the cycles encountered in the inductive process is unbalanced. We also solve the problem on some balanced cycles.
Energy-preserving methods on Riemannian manifolds

The energy preserving discrete gradient methods are generalized to finite-dimensional Riemannian manifolds by definition of a discrete approximation to the Riemannian gradient, a retraction, and a coordinate center function. The resulting schemes are intrinsic and do not depend on a particular choice of coordinates, nor on embedding of the manifold in a Euclidean space. Generalizations of well-known discrete gradient methods, such as the average vector field method and the Itoh--Abe method are obtained. It is shown how methods of higher order can be constructed via a collocation-like approach. Local and global error bounds are derived in terms of the Riemannian distance function and the Levi-Civita connection. Some numerical results on spin system problems are presented.
Tautological relations for stable maps to a target variety

We define tautological relations for the moduli space of stable maps to a target variety. Using the double ramification cycle formula for target varieties of Janda-Pandharipande-Pixton-Zvonkine, we construct nontrivial tautological relations parallel to Pixton's double ramification cycle relations for the moduli of curves. Examples and applications are discussed.
Further improvements to incidence and Beck-type bounds over prime finite fields

We establish improved finite field Szemeredi-Trotter and Beck type theorems. First we show that if P and L are a set of points and lines respectively in the plane F_p^2, with |P|,|L| \leq N and N<p, then there are at most C_1 N^{3/2-1/662+o(1)} incidences between points in P and lines in L. Here C_1 is some absolute constant greater than 1. This improves on the previously best-known bound of C_1 N^{3/2-1/806+o(1)}. Second we show that if P is a set of points in \mathbb{F}_p^2 with |P|<p then either at least C_2|P|^{1-o(1)} points in P are contained in a single line, or P determines least C_2 |P|^{1+1/109-o(1)} distinct lines. Here C_2 is an absolute constant less than 1. This improves on previous results in two ways. Quantitatively, the exponent of 1+1/109-o(1) is stronger than the previously best-known exponent of 1+1/267. And qualitatively, the result applies to all subsets of F_p^2 satisfying the cardinality condition; the previously best-known result applies only when P is of the form P=A*A for A \subseteq F_p.