Natural Explanation Research Articles

Large-scale Evolution of Seconds-long Relativistic Jets from Black Hole–Neutron Star Mergers

We present the first numerical simulations that track the evolution of a black hole–neutron star (BH–NS) merger from premerger to r ≳ 1011 cm. The disk that forms after a merger of mass ratio q = 2 ejects massive disk winds (3–5 × 10−2 M ⊙). We introduce various postmerger magnetic configurations and find that initial poloidal fields lead to jet launching shortly after the merger. The jet maintains a constant power due to the constancy of the large-scale BH magnetic flux until the disk becomes magnetically arrested (MAD), where the jet power falls off as L j ∼ t −2. All jets inevitably exhibit either excessive luminosity due to rapid MAD activation when the accretion rate is high or excessive duration due to delayed MAD activation compared to typical short gamma-ray bursts (sGRBs). This provides a natural explanation for long sGRBs such as GRB 211211A but also raises a fundamental challenge to our understanding of jet formation in binary mergers. One possible implication is the necessity of higher binary mass ratios or moderate BH spins to launch typical sGRB jets. For postmerger disks with a toroidal magnetic field, dynamo processes delay jet launching such that the jets break out of the disk winds after several seconds. We show for the first time that sGRB jets with initial magnetization σ 0 > 100 retain significant magnetization (σ ≫ 1) at r > 1010 cm, emphasizing the importance of magnetic processes in the prompt emission. The jet–wind interaction leads to a power-law angular energy distribution by inflating an energetic cocoon whose emission is studied in a companion paper.

Comprehending the Gossips: Meme Explanation in Time-Sync Video Comment via Multimodal Cues

Recent years have witnessed the booming of online social media platforms with embracing the popular service called “Time-Sync Comment”, which supports the viewers to share their time-sync opinions along with video content. In this way, we observe that numerous semantically-altered terms, or “Memes”, were created by niche users to express their unique ideas and emotions, and further attracted a large group of viewers with better activity and enthusiasm. Unfortunately, since the memes were created based on domain-specific knowledge and semantically varied depending on the multimodal context in videos, newcomers may fail to comprehend the semantic connotation of memes, which may severely impair their user-experiences. To deal with this issue, in this article, we propose a novel meme explanation framework, called ProMDE, to automatically capture and comprehend the memes in time-sync comments, which could further benefit the viewers with meme explanation service. Specifically, we first iteratively reconstruct the original time-sync comments compared with visual embedding to detect the semantically-altered terms as meme candidates. Afterward, based on the guides from the domain-specific corpus, visual and textual features will be fused to represent the context-aware multimodal cues. Moreover, to accurately describe the commonly-seen homophones in memes, i.e., they have the same pronunciation but different word-spelling expressions, we integrate the phonetic symbols as an additional modality to enhance the framework. Finally, we utilize a Transformer-based decoder to generate the natural language explanation for captured memes. Extensive experiments on a large real-world dataset prove that our framework could significantly outperform several state-of-the-art baseline methods, demonstrating the efficacy of modeling multimodal context and pronunciation for meme detection and explanation.

Observation of long-radial-range-correlation in turbulence in high-collisionality high-confinement plasmas on DIII-D

We report on the observation of spatially asymmetric turbulent structures with a long radial correlation length in the core of high-collisionality H-mode plasmas on DIII-D tokamak. These turbulent structures develop from shorter wavelength turbulence and have a radially elongated structure. The envelope of turbulence spans a broad radial range in the mid-radius region, leading to streamer-like transport events. The underlying turbulence is featured by intermittency, long-term memory effect, and the characteristic spectrum of self-organized criticality. The amplitude and the radial scale increase substantially when the shearing rate of the mean flow is reduced below the turbulent scattering rate. The enhanced long-radial-range-correlated (LRRC) transport events are accompanied by apparent degradation of normalized energy confinement time. The emergence of such LRRC transport events may serve as a candidate explanation for the degrading nature of H-mode core plasma confinement at high collisionality on DIII-D tokamak.

Critical Realist Foundations for Berlin Comparative Musicology(vergleichende Musikswissenschaft)

Summary Is it possible to discover the critical realist foundations of Gestalt theory in Berlin comparative musicology (vergleichende Kunstwissenschaft) associated above all with Erich M. von Hornbostel? The balance of natural science explanation and phenomenal experience is a useful model for overcoming Eurocentrism in comparative ethnomusicology, relying both on third-person tools and indigenous music systems. This paper uses Gestalt critical realist epistemology and methodology and a portrayal of the strata making up the understanding of a musical act with chemico-physical, phenomenal and cultural components to create an “amphibian” ethnomusicology. Using this framework it is possible to understand Hornbostel and Sachs’ musical instrument classification system and Hornbostel’s account of “primitive” music as strata in a Gestalt explanatory system. The potential binding agent through the strata is isomorphism.

RadioAstron discovery of a mini-cocoon around the restarted parsec-scale jet in 3C 84

We present RadioAstron space-based very long baseline interferometry (VLBI) observations of the nearby radio galaxy 3C 84 (NGC 1275) at the centre of the Perseus cluster. The observations were carried out during a perigee passage of the Spektr-R spacecraft on September 21–22, 2013 and involved a global array of 24 ground radio telescopes observing at 5 GHz and 22 GHz, together with the Space Radio Telescope (SRT). Furthermore, the Very Long Baseline Array (VLBA) and the phased Very Large Array (VLA) observed the source quasi-simultaneously at 15 GHz and 43 GHz. Fringes between the ground array and the SRT were detected on baseline lengths up to 8.1 times the Earth’s diameter, providing unprecedented resolution for 3C 84 at these wavelengths. We note that the corresponding fringe spacing is 125 μas at 5 GHz and 27 μas at 22 GHz. Our space-VLBI images reveal a previously unseen sub-structure inside the compact ∼1 pc long jet that was ejected about ten years earlier. In the 5 GHz image, we detected, for the first time, low-intensity emission from a cocoon-like structure around the restarted jet. Our results suggest that the increased power of the young jet is inflating a bubble of hot plasma as it carves its way through the ambient medium of the central region of the galaxy. Here, we estimate the minimum energy stored in the mini-cocoon, along with its pressure, volume, expansion speed, and the ratio of heavy particles to relativistic electrons, as well as the density of the ambient medium. About half of the energy delivered by the jet is dumped into the mini-cocoon and the quasi-spherical shape of the bubble suggests that this energy may be transferred to a significantly larger volume of the interstellar medium than what would be accomplished by the well-collimated jet on its own. The pressure of the hot mini-cocoon also provides a natural explanation for the almost cylindrical jet profile seen in the 22 GHz RadioAstron image.

Systematic Multiepoch Monitoring of LkCa 15: Dynamic Dust Structures on Solar System Scales

We present the highest-angular-resolution infrared monitoring of LkCa 15, a young solar analog hosting a transition disk. This system has been the subject of a number of direct-imaging studies from the millimeter through the optical, which have revealed multiple protoplanetary disk rings as well as three orbiting protoplanet candidates detected in infrared continuum emission (one of which was simultaneously seen at Hα). We use high-angular-resolution infrared imaging from 2014 to 2020 to systematically monitor these infrared signals and determine their physical origin. We find that three self-luminous protoplanets cannot explain the positional evolution of the infrared sources since the longer time baseline images lack the coherent orbital motion that would be expected for companions. However, the data still strongly prefer a time-variable morphology that cannot be reproduced by static scattered-light disk models. The multiepoch observations suggest the presence of complex and dynamic substructures moving through the forward-scattering side of the disk at ∼20 au or quickly varying shadowing by closer-in material. We explore whether the previous Hα detection of one candidate would be inconsistent with this scenario and in the process develop an analytical signal-to-noise penalty for Hα excesses detected near forward-scattered light. Under these new noise considerations, the Hα detection is not strongly inconsistent with forward scattering, making the dynamic LkCa 15 disk a natural explanation for both the infrared and Hα data.

Failed supernovae as a natural explanation for the binary black hole mass distribution

Context. As the number of detected gravitational wave sources increases, the better we can understand the mass distribution of binary black holes (BBHs). This “stellar graveyard” shows several features, including an apparent mass gap that makes the distribution bimodal. In turn, the observed chirp mass distribution appears to be trimodal. Aims. We aim to investigate the extent to which we can explain the observed mass distribution based on stellar evolution, specifically with the hypothesis that the mass gap is caused by the difference between successful and failed supernovae (SNe). Methods. We posed a hypothetical remnant function, based on the literature of stellar evolution simulations, which relates initial mass to remnant mass, while including a “black hole island” and producing a bimodal remnant distribution. Moreover, we looked at observed type II SN rates in an attempt to detect the effect of failed SNe. Finally, using a simplified estimation of binary evolution, we determined the remnant distribution resulting from our remnant function and compared it with observations. Results. We find that failed SNe lower type II SN rates by approximately 25%, but the inferred rate from SN surveys is not accurate enough to confirm this. Furthermore, our estimation based on the remnant function produces a mass distribution that matches the general shape of the observed distributions of individual as well as chirp masses. Conclusions. Based on our research, we conclude that the failed SN mechanism and the presence of the black hole island are a natural hypothesis for explaining the individual BBH mass distribution and chirp mass distribution. However, to obtain a firmer conclusion, more detailed simulations are needed.

Causal Semantics for Implicative Verbs

Abstract Implicative verbs (e.g., manage, dare) are characterized by complement inferences (Karttunen, 1971). English manage entails its complement; the entailment reverses polarity with matrix negation, and is accompanied by a projective inference to the complement’s non-triviality (Coleman, 1975; Karttunen & Peters, 1979). I use data from Finnish and English to argue that the implicative inferential profile is derived from backgrounded relations of causal necessity and causal sufficiency (defined over the structure of a formal causal model; Pearl 2000; Schulz 2011) which link the lexical content of an implicative verb to the realization of its complement. The proposal builds on Baglini & Francez’s (2016) causal analysis of manage, but significantly revises the earlier proposal to offer a treatment which accounts not only for English manage, but extends to the lexical semantics of the full implicative class, including ‘polarity-reversing’ verbs like fail, lexically specific verbs like dare, and their Finnish counterparts. Unlike earlier analyses, the proposed causal semantics also provides a natural explanation of the commonalities between two-way entailing verbs like manage and a related class of weaker ‘one-way’ implicatives such as Finnish jaksaa (‘have the strength’), which entail complement truth values under only one matrix polarity, but generate strong pragmatic implicatures in the two-way implicative pattern under the non-entailing polarity.

Adult-born neurons maintain hippocampal cholinergic inputs and support working memory during aging.

Adult neurogenesis is reduced during aging and impaired in disorders of stress, memory, and cognition though its normal function remains unclear. Moreover, a systems level understanding of how a small number of young hippocampal neurons could dramatically influence brain function is lacking. We examined whether adult neurogenesis sustains hippocampal connections cumulatively across the life span. Long-term suppression of neurogenesis as occurs during stress and aging resulted in an accelerated decline in hippocampal acetylcholine signaling and a slow and progressing emergence of profound working memory deficits. These deficits were accompanied by compensatory reorganization of cholinergic dentate gyrus inputs with increased cholinergic innervation to the ventral hippocampus and recruitment of ventrally projecting neurons by the dorsal projection. While increased cholinergic innervation was dysfunctional and corresponded to overall decreases in cholinergic levels and signaling, it could be recruited to correct the resulting memory dysfunction even in old animals. Our study demonstrates that hippocampal neurogenesis supports memory by maintaining the septohippocampal cholinergic circuit across the lifespan. It also provides a systems level explanation for the progressive nature of memory deterioration during normal and pathological aging and indicatesthat the brain connectome is malleable by experience.

Detached and continuous circumstellar matter in Type Ibc supernovae from mass eruption

Abstract Some hydrogen-poor supernovae (SNe) are found to undergo interaction with dense circumstellar matter (CSM) that may originate from mass eruption(s) just prior to core-collapse. We model the interaction between the remaining star and the bound part of the erupted CSM that eventually falls back to the star. We find that while fallback initially results in a continuous CSM down to the star, feedback processes from the star can push the CSM to large radii of ≳1015 cm for several years after the eruption. In the latter case, a tenuous bubble surrounded by a dense and detached CSM extending to ≳1016 cm is expected. Our model offers a natural unifying explanation for the diverse CSM structures seen in hydrogen-poor SNe, such as Type Ibn/Icn SNe that show CSM signatures soon after explosion, and the recently discovered Type Ic SNe 2021ocs and 2022xxf (the “Bactrian”) with CSM signatures seen only at late times.

The Precursors of Scientific Models in Ancient Egypt, Mesopotamia, and Ancient Greek World: A Comparative Study

This research traces and examines specific examples of the precursors of scientific models that were applied in ancient Egypt, Mesopotamia, and the ancient Greek world. The main purpose of the study is to compare the way that these different civilizations used models but also the purposes of their utilization in pre-Hellenic and ancient Greek science. A core question that arose is: Can we trace the roots of the utilization of what we nowadays call ‘‘scientific models’’ in ancient Egyptian, Mesopotamian, and Greek scientific activity? Another important question is how the application of models differs in the scientific activity of these civilizations. Based on an extensive review of historical books, papers, and web sources I inferred that ancient Egyptians and Babylonians utilized tools that nowadays we call mathematical and analogue or material models and the ancient Greeks utilized theoretical, fiction, and analogue models. Moreover, while the basic function of these tools seems to remain stable throughout the centuries, the core difference is detected in the purpose of their utilization in these civilizations and is related to the orientation of their scientific activity. Specifically, the scientific activity of Egyptians and Babylonians mainly aimed at solving practical problems related to spatial planning, architecture, and agriculture as well as issues related to religion while ancient Greek ‘‘episteme,’’ according to Plato, or ‘‘natural philosophy,’’ according to Aristotle, sought the acquisition of knowledge about the natural world, the understanding, description, and explanation of natural phenomena.

Characterization of mesoscopic turbulent transport events with long-radial-range correlation in DIII-D H-mode plasmas

A dimensionless collisionality scan has been performed in H-mode plasmas on DIII-D tokamak, with detailed measurements of intermediate-to-high wavenumber turbulence using Doppler backscattering systems. It is found that the shorter wavelength turbulence develops into spatially asymmetric turbulent structures with a long-radial-range correlation (LRRC) in the mid-radius region of high collisionality discharges. Linear cgyro simulations indicate that the underlying turbulence is likely driven by the electron-temperature-gradient mode. The LRRC transport events are highly intermittent and show a power spectrum of Sñ(k⊥)∝k⊥−1 for density fluctuations, which is often associated with self-organized criticality. The magnitude and the radial scale of those turbulent structures increase significantly when the Er×B mean flow shearing rate decreases at higher collisionality. The enhanced LRRC transport events appear to be correlated with the degraded energy confinement time. The emergence of such LRRC transport events may serve as a candidate explanation for the degrading nature of H-mode core plasma confinement at high collisionality.

What Do You MEME? Generating Explanations for Visual Semantic Role Labelling in Memes

Memes are powerful means for effective communication on social media. Their effortless amalgamation of viral visuals and compelling messages can have far-reaching implications with proper marketing. Previous research on memes has primarily focused on characterizing their affective spectrum and detecting whether the meme's message insinuates any intended harm, such as hate, offense, racism, etc. However, memes often use abstraction, which can be elusive. Here, we introduce a novel task - EXCLAIM, generating explanations for visual semantic role labeling in memes. To this end, we curate ExHVV, a novel dataset that offers natural language explanations of connotative roles for three types of entities - heroes, villains, and victims, encompassing 4,680 entities present in 3K memes. We also benchmark ExHVV with several strong unimodal and multimodal baselines. Moreover, we posit LUMEN, a novel multimodal, multi-task learning framework that endeavors to address EXCLAIM optimally by jointly learning to predict the correct semantic roles and correspondingly to generate suitable natural language explanations. LUMEN distinctly outperforms the best baseline across 18 standard natural language generation evaluation metrics. Our systematic evaluation and analyses demonstrate that characteristic multimodal cues required for adjudicating semantic roles are also helpful for generating suitable explanations.

Is Faith Supernatural?

The Cognitive Science of Religion represents a contemporary attempt at a naturalistic explanation of religion. There is debate as to whether its account of how religious beliefs arise is reconcilable with the religious account, which holds that religious beliefs are caused by God. In my paper, I argue that these two accounts cannot be reconciled when it comes to the specific question of how Christian religious beliefs arise if one accepts an important theological doctrine of the supernaturality of Christian belief. This doctrine implies that there can be no natural explanation for how Christian beliefs arise because they are a gift of divine grace. This leads to a conundrum for Christian theists: they can either reject the CSR account of how their religious beliefs arise, or they can reject the supernaturality of Christian belief. I argue that the latter is preferable. I then draw on the work of the theologian Denis Edwards to illustrate how one can drop this doctrine without abandoning some other fundamental tenets of Christian theology.

Information Ratio = Selection × Breadth + Sizing

Factor-based performance attribution is an established practice among quantitative and fundamental strategies alike. Although popular, this attribution technique is not of great help to investors interested in understanding the source of their idiosyncratic performance. Of special interest is the ability to separate stock selection skill and sizing skill. Methods aimed at measuring these skills are inspired by analogies to sports. In this article, the author presents an exact decomposition of the information ratio. The IR is the sum of a breadth-adjusted stock selection skill and a sizing skill. The definition of breadth relies on an intuitive measure of concentration—the Herfindahl Index—rather than on the “square root of <italic>n</italic>” measure. These quantities can be compared so that the portfolio manager can determine the percentage of their realized performance originating from each term. In addition, the decomposition empowers the manager to improve their risk-adjusted performance by choosing optimal position sizing, determined by the observed performance of their portfolio. Finally, the decomposition can be further extended to long–short analysis, and provides a natural explanation of an empirical phenomenon: The idiosyncratic performance of the long side of a strategy is often larger than that of the short side.

Inevitable manifestation of wiggles in the expansion of the late Universe

Using the fact that the comoving angular diameter distance to the last scattering surface is strictly constrained almost model independently, we show that, for any model agreeing with the standard $\mathrm{\ensuremath{\Lambda}}$CDM model on its background dynamics at $z\ensuremath{\sim}0$ and size of the comoving sound horizon at last scattering, the deviations of the Hubble radius from the one of the standard $\mathrm{\ensuremath{\Lambda}}$CDM model must be a member of the set of admissible wavelets. The family of models characterized by this framework also offers nontrivial oscillatory behaviors in various functions that define the kinematics of the Universe, even when the wavelets themselves are very simple. We also discuss the consequences of attributing these kinematics to, first, dark energy, and second, varying gravitational coupling strength. Utilizing some simplest wavelets, we demonstrate the competence of this framework in describing the baryon acoustic oscillation (BAO) data without any modifications to the agreement with cosmic microwave background measurements. This framework also provides a natural explanation for the bumps found in nonparametric observational reconstructions of the Hubble parameter and dark energy density as compensations of the dips suggested by some BAO data, and questions the physical reality of their existence. We note that utilizing this framework on top of the models that agree with both the cosmic microwave background and local ${H}_{0}$ measurements but are held back by BAO data, one may resurrect these models through the wiggly nature of wavelets that can naturally accommodate the BAO data. Finally, we also suggest narrowing the plausible set of admissible wavelets to further improve our framework by imposing conditions from expected kinematics of a viable cosmological model or first principle fundamental physics such as energy conditions.

Something Called the ‘False Dilemma Fallacy’ (FDF): A Return to Formalization Just This Time

This work is a revision of the False Dilemma Fallacy (FDF). The formalized model (FM)of this fallacy has as its centerpiece a valid disjunctive syllogism, but the disjunctive premise is presumed to be false, thus making the argument unsound. Our revised model (FM2.0) focuses on the formal structure by comparing the given vs. the real argument, which is unsound because of its invalidity. This approach we believe is more pedagogically useful and a better explanation of the fallacious nature of the FDF. It extends the identity of “formal fallacy” to the FDF. The abstract is formatted in two columns. The English abstract goes on this side.

3D evolution of neutron star magnetic fields from a realistic core-collapse turbulent topology

ABSTRACT We perform the first 3D fully coupled magneto-thermal simulations of neutron stars (including the most realistic background structure and microphysical ingredients so far) applied to a very complex initial magnetic field topology in the crust, similar to what was recently obtained by proto-neutron stars dynamo simulations. In such configurations, most of the energy is stored in the toroidal field, while the dipolar component is a few per cent of the mean magnetic field. This initial feature is maintained during the long-term evolution (∼106 yr), since the Hall term favours a direct cascade (compensating for Ohmic dissipation) rather than a strong inverse cascade, for such an initial field topology. The surface dipolar component, responsible for the dominant electromagnetic spin-down torque, does not show any increase in time, when starting from this complex initial topology. This is in contrast to the timing properties of young pulsars and magnetars which point to higher values of the surface dipolar fields. A possibility is that the deep-seated magnetic field (currents in the core) is able to self-organize in large scales (during the collapse or in the early life of a neutron star). Alternatively, the dipolar field might be lower than is usually thought, with magnetosphere substantially contributing to the observed high spin-down, via e.g. strong winds or strong coronal magnetic loops, which can also provide a natural explanation to the tiny surface hotspots inferred from X-ray data.

Natural Explanation of Recent Results on {{e}^{ + }}{{e}^{ - }} to Lambda bar {Lambda }

We show that the recent experimental data on the cross section of the process {{e}^{ + }}{{e}^{ - }} to Lambda bar {Lambda } near the threshold can be perfectly explained by the final-state interaction of Lambda and bar {Lambda }. The enhancement of the cross section is related to the existence of low-energy real or virtual state in the corresponding potential. We present a simple analytical formula that fits the experimental data very well.

Wide-binary Stars Formed in the Turbulent Interstellar Medium

The ubiquitous interstellar turbulence regulates star formation and the scaling relations between the initial velocity differences and the initial separations of stars. We propose that the formation of wide binaries with initial separations r in the range ∼103 au ≲ r ≲ 105 au is a natural consequence of star formation in the turbulent interstellar medium. With the decrease of r, the mean turbulent relative velocity v tur between a pair of stars decreases, while the largest velocity v bon at which they still may be gravitationally bound increases. When v tur < v bon, a wide binary can form. In this formation scenario, we derive the eccentricity distribution p(e) of wide binaries for an arbitrary relative velocity distribution. By adopting a turbulent velocity distribution, we find that wide binaries at a given initial separation generally exhibit a superthermal p(e), irrespective of the exact turbulent velocity scaling. This provides a natural explanation for the observed superthermal p(e) of the wide binaries in the solar neighborhood.