University of Tennessee at Martin

The origin and acceleration of high-energy particles, constituting cosmic rays, is likely to remain an important topic in modern astrophysics. Among the two categories galactic and solar cosmic rays, the latter are much less investigated. The primary source of solar cosmic ray particles are impulsive explosions of the magnetized plasma, known as solar flares and coronal mass ejections. These particles, however, are characterized by relatively low energies compared to their galactic counterparts. In this work, we explore the resonance wave–wave (RWW) interaction between the polarized electromagnetic radiation emitted by the solar active regions and the quantum waves associated with high-energy, relativistic electrons generated during solar flares. Mathematically, the RWW interaction problem boils down to analyzing a Klein–Gordon Equation (spinless electrons) embedded in the electromagnetic field. We find that RWW could accelerate the relativistic electrons to enormous energies even comparable to energies in the galactic cosmic rays.

Abstract This paper examines the propagation of time-harmonic waves in a two-dimensional triangular lattice with a lattice constant a = 1 {a=1} . The sources are positioned along line segments within the lattice. Specifically, we investigate the discrete Helmholtz equation with a wavenumber k ∈ ( 0 , 2 ⁢ 2 ) {k\in(0,2\sqrt{2})} , where input data is prescribed on finite rows or columns of lattice sites. We focus on two main questions: the efficacy of the numerical methods employed in evaluating the Green’s function, and the necessity of the cone condition. Consistent with a continuum theory, we employ the notion of radiating solution and establish a unique solvability result and Green’s representation formula using difference potentials. Finally, we propose a numerical computation method and demonstrate its efficiency through examples related to the propagation problems in the left-handed two-dimensional inductor-capacitor metamaterial.

We introduce new machine learning techniques for analyzing chaotic dynamical systems. The main goal of this study is to develop a simple method for calculating the Lyapunov exponent using only two trajectory data points, in contrast to traditional methods that require averaging procedures. Additionally, we explore phase transition graphs to analyze the shift from regular periodic to chaotic dynamics, focusing on identifying “almost integrable” trajectories where conserved quantities deviate from whole numbers. Furthermore, we identify “integrable regions” within chaotic trajectories. These methods are tested on two dynamical systems: “two objects moving on a rod” and the “Henon–Heiles” system.

Abstract Background and Hypothesis Individuals with schizophrenia have less priors than controls, meaning they rely less upon their prior experiences to interpret the current stimuli. These differences in priors are expected to show as higher alternation rates in bistable perception tasks like the Structure-from-Motion (SfM) paradigm. In this paradigm, continuously moving dots in two dimensions are perceived subjectively as traveling along a three-dimensional sphere, which results in a direction of motion (left or right) that shifts approximately every few seconds. Study Design Here, we tested healthy controls, patients with schizophrenia, siblings of patients with schizophrenia, and patients with depression with both the intermittent and continuous variants of the SfM paradigm. Study Results In the intermittent variant of the SfM paradigm, depressive patients exhibited the lowest alternation rate, followed by unaffected controls. In contrast, patients with schizophrenia and their unaffected siblings displayed significantly higher alternation rates. In the continuous variant of the SfM paradigm, patients with schizophrenia showed the lowest mean percept durations, while there were no differences between the other three groups. Conclusions The intermittent SfM paradigm is a candidate endophenotype for schizophrenia. The aberrant processing in the patients may stem from alterations in adaptation and/or cross-inhibition mechanisms leading to changes in priors, as suggested by current models in the field. The intermittent SfM paradigm is, hence, a trait marker that offers the great opportunity to investigate perceptual abnormalities across the psychiatry spectrum, ranging from depression to psychosis.

Abstract The history of medieval Georgian poetry is long and complicated. Placed between Persian and Byzantine commonwealths, the unification of the Georgian kingdom under the Bagratids in the eleventh century brought about a dramatic cultural revival. The formation and development of what is known as secular poetry was a reaction to the simultaneous adoption and adaptation of Persian and Byzantine elements by Georgian culture. As a result, over time, a distinct literary genre was shaped, with its own linguistic, graphic, and poetic registers – emerged, which was often contrasted with ecclesiastic writing alongside a a rigid differentiation between secular and religious writing generally and poetry specifically. The present paper identifies the origins and reasons for such a differentiation in early modern and modern political and literary discourses. While it mentions many poems from the twelfth to the seventeenth century, two relatively early theories of poetry are discussed in detail: Ephrem Mc‘ire’s (twelfth-century) reference to the “form and substance” dichotomy in poetry and Shota Rust‘aveli’s (twelfth- or thirteenth-century) vision of what does and what does not constitute proper poetry. In subsequent centuries, these discussion about the limits of poetry were integrated into identity discourses, as illustrated by the numerous sequels to and emulations of Rust‘aveli, and fed into a certain anxiety over Georgian culture within the context of total Persian dominance

A closed set of fluid equations with radiation reaction force (RRF) are constructed from the moments of the appropriate single particle kinetic equation describing a relativistic degenerate (high density) electron plasma. The closure, in analogy with the Maxwellian closure for non-degenerate plasmas, is affected via a parametrized Fermi-Dirac distribution. It is shown that the degeneracy increases RRF just as will be predicted from the so-called “Compton Rocket” effect.

Abstract Background and Hypothesis For a long time, it was proposed that schizophrenia (SCZ) patients rely more on sensory input and less on prior information, potentially leading to reduced serial dependence—ie, a reduced influence of prior stimuli in perceptual tasks. However, existing evidence is constrained to a few paradigms, and whether reduced serial dependence reflects a general characteristic of the disease remains unclear. Study Design We investigated serial dependence in 26 SCZ patients and 27 healthy controls (CNT) to evaluate the influence of prior stimuli in a classic visual orientation adjustment task, a paradigm not previously tested in this context. Study Results As expected, the CNT group exhibited clear serial dependence, with systematic biases toward the orientation of stimuli shown in the preceding trials. Serial dependence in SCZ patients was largely comparable to that in the CNT group. Conclusions These findings challenge the prevailing notion of reduced serial dependence in SCZ, suggesting that observed differences between healthy CNT and patients may depend on aspects of perceptual or cognitive processing that are currently not understood.

Abstract We consider propagation of two-dimensional waves on the infinite hexagonal (honeycomb) lattice. Namely, we study the discrete Helmholtz equation in hexagonal lattices without and with a boundary. It is shown that for some configurations these problems can be equivalently reduced to similar problems for the triangular lattice. Based on this fact, new results are obtained for the existence and uniqueness of the solution in the case of the real wave number k ∈ ( 0 , 6 ) ∖ { 2 , 3 , 2 } {k\in(0,\sqrt{6})\setminus\{\sqrt{2},\sqrt{3},2\}} for the non-homogeneous Helmholtz equation in hexagonal lattices with no boundaries and the real wave number k ∈ ( 0 , 2 ) ∪ ( 2 , 6 ) {k\in(0,\sqrt{2})\cup(2,\sqrt{6})} for the exterior Dirichlet problem.

Abstract This paper presents a general review of the Oxford Handbook of the Languages of the Caucasus. It summarizes over four dozen different typological rarities found in Caucasian languages, and examines what explanations have been given for their presence, and what roles phylogeny, contact and human geography play in their appearance in these languages.

Previous studies have found a negative relationship between creativity and conservatism. However, as these studies were mostly conducted on samples of homogeneous nationality, the generalizability of the effect across different cultures is unknown. We addressed this gap by conducting a study in 28 countries. Based on the notion that attitudes can be shaped by both environmental and ecological factors, we hypothesized that parasite stress can also affect creativity and thus, its potential effects should be controlled for. The results of multilevel analyses showed that, as expected, conservatism was a significant predictor of lower creativity, adjusting for economic status, age, sex, education level, subjective susceptibility to disease, and country-level parasite stress. In addition, most of the variability in creativity was due to individual rather than country-level variance. Our study provides evidence for a weak but significant negative link between conservatism and creativity at the individual level (β = −0.08, p < .001) and no such effect when country-level conservatism was considered. We present our hypotheses considering previous findings on the behavioral immune system in humans.

We considered the question of how our artificial constructions are visible to advanced extraterrestrial civilizations. Taking the universality of the laws of physics, we found that the maximum distance where the detection is possible is of the order of 3000 ly and under certain conditions Type-II advanced alien societies might be able to resolve this problem.

Menétrey M.Q., Roinishvili M., Chkonia E., Herzog M.H., Pascucci D.

Abstract Recent work suggests that the individual alpha peak frequency (IAPF) reflects the temporal resolution of visual processing: individuals with higher IAPF can segregate stimuli at shorter intervals compared to those with lower IAPF. However, this evidence mainly comes from studies focusing on short intervals, with stimulus onset asynchronies (SOA) rarely extending beyond a single alpha cycle (e.g., ~100 ms). Here, we investigated the relationship between IAPF and performance in visual backward masking (VBM), which allowed us to test the effects of IAPF for longer SOAs than an alpha cycle. A group of healthy controls (N = 79) and schizophrenia patients (N = 121), who generally exhibit lower IAPF, were tested in conditions with a Vernier shown alone, a Vernier followed by a mask at two SOAs (30 and 150 ms), or only a mask. Our results show that IAPF can predict VBM performance in all conditions with a Vernier. Furthermore, in both the control and schizophrenia groups, individuals with higher IAPF showed reduced masking effects, even when the SOA of 150 ms exceeded the alpha cycle. These findings challenge the notion that IAPF is exclusively related to temporal resolution and visual processing within a single alpha cycle. We discuss alternative mechanisms by which IAPF determines visual performance.

Using batteries of visual tests, most studies have found that there are only weak correlations between the performance levels of the tests. Factor analysis has confirmed these results. This means that a participant excelling in one test may rank low in another test. Hence, there is very little evidence for a common factor in vision. In visual aging research, cross-sectional studies have repeatedly found that healthy older adults’ performance is strongly deteriorated in most visual tests compared to young adults. However, also within the healthy older population, there is no evidence for a visual common factor. To investigate whether the weak between-tests correlations are due to fluctuations in individual performance throughout time, we conducted a longitudinal study. Healthy older adults performed a battery of eight visual tests, with two re-tests after approximately four and seven years. Pearson’s, Spearman’s and intraclass correlations of most visual tests were significant across the three testing, indicating that the tests are reliable and individual differences are stable across years. Yet, we found low between-tests correlations at each visit, which is consistent with previous studies finding no evidence for a visual common factor. Our results exclude the possibility that the weak correlations between tests are due to high within-individual variance across time.

In this study, we examine the efficiency of pair creation by means of the centrifugal mechanism. The strong magnetic field and the effects of rotation, which always take place in Kerr-type black holes, guarantee the frozen-in condition, leading to the generation of an exponentially amplifying electrostatic field. This field, upon reaching the Schwinger threshold, leads to efficient pair production. Researchers have studied this process across a wide range of AGN luminosities and black hole masses, and found that the mechanism is highly efficient, indicating that for AGNs where centrifugal effects are significant, the annihilation lines in the MeV range will be very strong.

Background: Sexual violence is a complex and pressing social issue that needs urgent solutions. Republic of Georgia is one of those countries where despite some advancements in law and practice, patriarchal beliefs and behaviour patterns still prevail in a daily life. So far, there has not been undertaken an in-depth study on how Georgians and particularly youth, define sexual violence and what are the justifications behind these views. The aim of the research is to understand how Georgian students understand sexual violence, who they think are responsible for sexual violence and what are the underlying reasons behind those views. Method: In total, 37 in-depth interviews have been conducted with Georgian students, from September of 2019 to March of 2021. The study participants were recruited from different universities, including the two biggest cities of Georgia - Tbilisi and Batumi.   Results: The research revealed that understanding of sexual violence is far more complex than it was expected. Georgian students define sexual violence as a broad category where sexual harassment and sexual coercion have overlapping and at the same time independent meaning. Interpretation and attribution of responsibility in all three categories are dependent on situations and context that contain not only physical violence but also inappropriate touch, insistent gaze, comments about body parts, sexist insults and discrimination, messages of sexual content, psychological pressure and blackmailing. Attribution of responsibility was equally dependent on personal judgements as well as culturally determined stereotypes. Conclusion: Sexual violence is not a new phenomenon in Georgia, but its consideration as a social problem is. The research demonstrated that understanding and judgment on sexual violence, sexual harassment and sexual coercion is nuanced issue and still needs clear categories of definitions.