bluuebunny/crossref_metadata_2025 huggingface dataset:
Beyond Accuracy: Refining Brain-Age Models for Enhanced Disease Detection
Authors: Schulz Marc-Andre , Siegel Nys Tjade , Ritter Kerstin
Published: March 2024

This study critically reevaluates the utility of brain-age models within the context of detecting neurological and psychiatric disorders, challenging the conventional emphasis on maximizing chronological age prediction accuracy. Our analysis of T1 MRI data from 46,381 UK Biobank participants reveals a paradox: simpler machine learning models, and notably those with excessive regularization, demonstrate superior sensitivity to disease-relevant changes compared to their more complex counterparts. This counterintuitive discovery suggests that models traditionally deemed less accurate in predicting chronological age might, in fact, offer a more meaningful biomarker for brain health by capturing variations pertinent to disease states. Our findings challenge the traditional understanding of brain-age prediction as normative modeling, emphasizing the inadvertent identification of non-normative pathological markers over precise age prediction.
Rampant transcription replication conflict creates therapeutic vulnerability in extrachromosomal DNA containing cancers
Authors: Tang Jun , Weiser Natasha E. , Wang Guiping , Chowdhry Sudhir , Curtis Ellis J. , Zhao Yanding , Wong Ivy Tsz-Lo , Marinov Georgi K. , Li Rui , Hanoian Philip , Tse Edison , Hansen Ryan , Plum Joshua , Steffy Auzon , Milutinovic Snezana , Meyer S. Todd , Curtis Christina , Greenleaf William J. , Bafna Vineet , Benkovic Stephen J. , Pinkerton Anthony B. , Kasibhatla Shailaja , Hassig Christian A. , Mischel Paul S. , Chang Howard Y.
Published: March 2024

Extrachromosomal DNA (ecDNA) presents a major challenge for precision medicine, contributing to poor survival for patients with oncogene-amplified tumours. EcDNA renders tumours resistant to targeted treatments by facilitating massive transcription of oncogenes and rapid genome evolution. At present, there are no ecDNA- specific treatments. Here we show that enhancing transcription replication conflict enables targeted elimination of ecDNA-containing cancers, exposing an actionable vulnerability. Stepwise analyses of ecDNA transcription reveal landscapes of pervasive RNA transcription and associated single-stranded DNA, leading to excessive transcription replication conflicts and replication stress (RS) compared to chromosomal loci. Nucleotide incorporation onto growing DNA strands is markedly slower on ecDNA, and RS is significantly higher in ecDNA-containing tumours regardless of cancer type or oncogene cargo. Replication Protein A2 phosphorylated on serine 33, a mediator of DNA damage repair that binds single-stranded DNA, shows elevated localization on ecDNA in a transcription dependent manner, along with increased DNA double strand breaks, and activation of the S-phase checkpoint kinase, CHK1. Genetic or pharmacological CHK1 inhibition abrogates the DNA replication check point, causing extensive and preferential tumour cell death in ecDNA-containing tumours as they enter S-phase. To exploit this vulnerability, we develop a highly selective, potent, and bioavailable oral CHK1 inhibitor, BBI-2779, and demonstrate that it preferentially kills ecDNA-containing tumour cells. In a gastric cancer model containingFGFR2on ecDNA, BBI-2779, suppresses tumour growth and prevents ecDNA-mediated acquired resistance to the pan-FGFR inhibitor infigratinib, resulting in potent and sustained tumour regression in mice. These results reveal transcription-replication conflict as an ecDNA-generated vulnerability that can be targeted as an ecDNA-directed therapy and suggest that synthetic lethality of excess can be exploited as a strategy for treating cancer.
Loss ofLkb1cooperates withBrafV600Eand UV radiation increasing melanoma multiplicity and neural-like dedifferentiation
Authors: McGrail Kimberley , González-Sánchez Elena , Granado-Martínez Paula , Orsenigo Roberto , Ding Yuxin , Ferrer Berta , Hernández-Losa Javier , Ortega Iván , Caballero Juan M. , Muñoz-Couselo Eva , García-Patos Vicenç , Recio Juan A.
Published: March 2024

The mechanisms cooperating withBRAFV600Eoncogene in addition to ultraviolet (UV) radiation in melanoma development are of great interest. Analysis of human melanoma tumors (TCGA) indicates that 50% or more of the samples express no or low amounts of LKB1 protein. Here, we report that the concomitant neonatalBrafV600Eactivation andLkb1tumor suppressor ablation in melanocytes led to full melanoma development. A postnatal single-dose of UVB radiation had no effect on melanoma onset inLkb1-depleted mice in respect toBrafV600E-irradiated mice, but increased tumor multiplicity. In agreement to this and previous reports,Lkb1null irradiated mice showed a deficient DNA damage repair (DDR). Histologically, tumors lackingLkb1were enriched in neural-like tumor morphology. Genetic profiling and gene set enrichment analyses of tumor samples-mutated genes indicated that loss ofLkb1promoted the selection of altered genes associated to neural differentiation processes. Thus, these results suggest that loss ofLkb1cooperates withBrafV600Eand UVR impairing DDR and increasing melanoma multiplicity and neural-like dedifferentiation.
Twisting Urea- to Imide-Based Mass Spectrometry-Cleavable Cross-Linkers Enables Affinity Tagging
Authors: Di Ianni Alessio , Ihling Christian H. , Vranka Tomáš , Matoušek Václav , Sinz Andrea , Iacobucci Claudio
Published: March 2024

Disuccinimidyl dibutyric urea (DSBU) is a mass spectrometry (MS)-cleavable cross-linker that has multiple applications in structural biology, ranging from isolated protein complexes to comprehensive system-wide interactomics. DSBU facilitates a rapid and reliable identification of cross-links through the dissociation of its urea group in the gas-phase. In this study, we further advance the structural capabilities of DSBU by twisting the urea group into an imide, thus introducing a novel class of cross-linkers. This modification preserves the MS-cleavability of the amide bond, granted by the two acyl groups of the imide function. The central nitrogen atom enables the introduction of affinity purification tags. Here, we introduce disuccinimidyl disuccinic imide (DSSI) as prototype of this class of cross-linkers. It features a phosphonate handle for immobilized metal ion affinity chromatography (IMAC) enrichment. We detail DSSI synthesis and describe its behavior in solution and in the gas-phase while cross-linking isolated proteins and human cell lysates. DSSI and DSBU cross-links are compared at the same enrichment depths to bridge these two cross-linker classes. We validate DSSI cross-links by mapping them in high-resolution structures of large protein assemblies. The cross-links observed yield insights into the morphology of intrinsically disordered proteins (IDPs) and their complexes. The DSSI linker might spearhead a novel class of MS-cleavable and enrichable cross-linkers.
msqrob2TMT: robust linear mixed models for inferring differential abundant proteins in labelled experiments with arbitrarily complex design
Authors: Vandenbulcke Stijn , Vanderaa Christophe , Crook Oliver , Martens Lennart , Clement Lieven
Published: March 2024

Labelling strategies in mass spectrometry (MS)-based proteomics enable increased sample throughput by acquiring multiplexed samples in a single run. However, contemporary designs often require the acquisition of multiple runs, leading to a complex correlation structure. Addressing this correlation is key for correct statistical inference and reliable biomarker discovery. Therefore, we present msqrob2TMT, a set of mixed model-based workflows tailored toward differential abundance analysis for labelled MS-based proteomics data. Thanks to its increased flexibility, msqrob2TMT can model both sample-specific and feature-specific (e.g. peptide or protein) covariates, which unlocks the inference to experiments with arbitrarily complex designs as well as to correct explicitly for feature-specific properties. We benchmark our novel workflows against the state-of-the-art tools MSstatsTMT and DeqMS in a spike-in study. We show that our workflows are modular, more flexible and have improved performance by adopting robust ridge regression. We also found that reference channel normalization and imputation can have a deleterious impact on the statistical outcome. Finally, we demonstrate the significance of msqrob2TMT on a real-life mice study, showcasing the importance of effectively accounting for the hierarchical correlation structure in the data.
RNA folding kinetics control riboswitch sensitivity in vivo
Authors: Bushhouse David Z. , Fu Jiayu , Lucks Julius B.
Published: March 2024

Riboswitches are ligand-responsive gene-regulatory RNA elements that perform key roles in maintaining cellular homeostasis. Understanding how riboswitch sensitivity is controlled is critical to understanding how highly conserved aptamer domains are deployed in a variety of contexts with different sensitivity demands. Here we uncover new roles by which RNA folding dynamics control riboswitch sensitivity in cells. By investigating theClostridium beijerinckii pflZTP riboswitch, we identify multiple mechanistic routes of altering expression platform sequence and structure to slow RNA folding, all of which enhance riboswitch sensitivity. Applying these methods to riboswitches with diverse aptamer architectures that regulate transcription and translation with ON and OFF logic demonstrates the generality of our findings, indicating that any riboswitch that operates in a kinetic regime can be sensitized by slowing expression platform folding. Comparison of the most sensitized versions of these switches to equilibrium aptamer:ligand dissociation constants suggests a limit to the sensitivities achievable by kinetic RNA switches. Our results add to the growing suite of knowledge and approaches that can be used to rationally program cotranscriptional RNA folding for biotechnology applications, and suggest general RNA folding principles for understanding dynamic RNA systems in other areas of biology.
Strain-resolved de-novo metagenomic assembly of viral genomes and microbial 16S rRNAs
Authors: Jochheim Annika , Jochheim Florian A. , Kolodyazhnaya Alexandra , Morice Étienne , Steinegger Martin , Söding Johannes
Published: March 2024

Background

Metagenomics is a powerful approach to study environmental and human-associated microbial communities and, in particular, the role of viruses in shaping them. Viral genomes are challenging to assemble from metagenomic samples due to their genomic diversity caused by high mutation rates. In the standard de Bruijn graph assemblers, this genomic diversity leads to complexk-mer assembly graphs with a plethora of loops and bulges that are challenging to resolve into strains or haplotypes because variants more than thek-mer size apart cannot be phased. In contrast, overlap assemblers can phase variants as long as they are covered by a single read.

Results

Here, we present PenguiN, a software for strain resolved assembly of viral DNA and RNA genomes and bacterial 16S rRNA from shotgun metagenomics. Its exhaustive detection of all read overlaps in linear time combined with a Bayesian model to select strain-resolved extensions allow it to assemble longer viral contigs, less fragmented genomes, and more strains than existing assembly tools, on both real and simulated datasets. We show a 3-40-fold increase in complete viral genomes and a 6-fold increase in bacterial 16S rRNA genes.

Conclusion

PenguiN is the first overlap-based assembler for viral genome and 16S rRNA assembly from large and complex metagenomic datasets, which we hope will facilitate studying the key roles of viruses in microbial communities.
Extracellular vesicle-mediated secretion of chlorophyll biosynthetic intermediates in the cyanobacteriumLeptolyngbya boryana
Authors: Usui Kentaro , Yamamoto Haruki , Mori Hitoshi , Fujita Yuichi
Published: March 2024

Extracellular vesicles (EVs) are derived from the outer membrane (OM) in Gram-negative bacteria and have diverse physiological functions such as toxin transport, extracellular signal transduction, nutrient acquisition, and horizontal gene transfer. EV-mediated secretion of monovinyl protochlorophyllide (MV-Pchlide), the chlorophylla(Chl) biosynthetic intermediate, was previously reported in a mutant lacking dark-operative Pchlide reductase in the cyanobacteriumLeptolyngbya boryana. This study showed a detailed characterization of EVs from the wild-type (WT) ofL. boryanagrown under photoautotrophic and dark heterotrophic conditions, focusing on the accumulation of Chl intermediates. WTL. boryanacells produce two types of EVs, low-density EVs (L-EVs) and high-density EVs (H-EVs), both under light and dark conditions. L-EVs and H-EVs showed distinct morphological features and protein compositions. L-EVs from cells grown under both light and dark conditions commonly contained carotenoids, myxol glycoside, and zeaxanthin, as major pigments. Based on the protein compositions of EVs and other cellular membrane fractions, L-EVs and H-EVs are probably derived from low-density OM and high-density OM interacting with cell walls, respectively. Fluorescence detection of pigments was applied to EVs, and the three Chl intermediates, protoporphyrin IX, demetallated Mg-protoporphyrin IX monomethyl ester, pheophorbide, and were commonly detected both L-EVs from light- and dark-grown cells, whereas L-EVs from dark-grown cells contained additional MV-Pchlide and MV-protopheophorbide. These Chl intermediates appear to transfer from the thylakoid membrane to L-EVs via an unknown transport system. Cyanobacterial EVs may play a novel function in alleviating the accumulation of Chl intermediates in cells.
Predicting gene expression from histone marks using chromatin deep learning models depends on histone mark function, regulatory distance and cellular states
Authors: Murphy Alan E , Askarova Aydan , Lenhard Boris , Skene Nathan G , Marzi Sarah J
Published: March 2024

To understand the complex relationship between histone mark activity and gene expression, recent advances have usedin silicopredictions based on large-scale machine learning models. However, these approaches have omitted key contributing factors like cell state, histone mark function or distal effects, that impact the relationship, limiting their findings. Moreover, downstream use of these models for new biological insight is lacking. Here, we present the most comprehensive study of this relationship to date - investigating seven histone marks, in eleven cell types, across a diverse range of cell states. We used convolutional and attention-based models to predict transcription from histone mark activity at promoters and distal regulatory elements. Our work shows that histone mark function, genomic distance and cellular states collectively influence a histone mark’s relationship with transcription. We found that no individual histone mark is consistently the strongest predictor of gene expression across all genomic and cellular contexts. This highlights the need to consider all three factors when determining the effect of histone mark activity on transcriptional state. Furthermore, we conductedin silicohistone mark perturbation assays, uncovering functional and disease related loci and highlighting frameworks for the use of chromatin deep learning models to uncover new biological insight.

Graphical abstract
Exonuclease action of replicative polymerase gamma drives damage-induced mitochondrial DNA clearance
Authors: Seshadri Akshaya , Badrinarayanan Anjana
Published: March 2024

Mitochondrial DNA (mtDNA) replication is essential for mitochondrial function. This is carried out by a dedicated DNA polymerase gamma, with 5’-3’ polymerase and 3’-5’ proofreading/ exonuclease activity. Perturbations to either properties can have pathological consequences. Predominant sources for replication stress are DNA lesions, such as those induced by oxidative damage. How mtDNA lesions affect the polymerase activity and mtDNA stabilityin vivois not fully understood. To address this, we induce mtDNA-specific damage inS. cerevisiae.We observe that mtDNA damage results in significant mtDNA loss. This loss occurs independent of cell cycle progression or cell division, suggesting an active mechanism for damaged mtDNA clearance. We implicate the 3’-5’ exonuclease activity of the mtDNA polymerase in this clearance, with rates of loss being affected by cellular dNTP levels. Overall, our findings reveal context-dependent, selective regulation of two critical but opposing functions of polymerase gamma to ensure mitochondrial genome integrity.
Nest construction and its effect on post-hatching family life in the burying beetleNicrophorus vespilloides
Authors: Bladon Eleanor Kate , Kilner Rebecca Mary
Published: March 2024

Through the effort required to construct them, the microenvironmental conditions they impose on the family and their indirect influence on post-hatching care, nests play a key role in influencing family life. We combined experimental evolution with cross-fostering experiments on laboratory populations ofNicrophorus vespilloidesto investigate three ways in which the nest can contribute more broadly to parental investment. We used replicate populations ofN. vespilloidesthat had evolved for 42 generations under contrasting regimes of care. Populations were either able to supply post-hatching care (“Full Care”) or prevented from supplying any post-hatching care (“No Care”). Research on these populations has previously shown that the No Care populations evolved to build rounder nests, more rapidly, by Generation 14. Here we found: 1) larvae raised by Full Care parents on nests prepared by parents from the No Care population did not attain a higher mass by the end of larval development than larvae in other treatments. However, we did discover that: 2) cross-fostering nests between families consistently reduced larval mass – and to a similar extent whether nests were cross-fostered between or within the populations. We suggest that cross-fostering disrupted the chemical environment on and around the nest since we found no evidence that 3) nests mediate interactions between males and females. The duration of paternal care was consistently shorter than the duration of maternal care, and even shorter for males from the No Care populations than males from the Full Care populations. Nevertheless, the duration of male care did not predict variation in duration of female care. In short, although the nest is the substrate for burying beetle family life, we found little evidence that it had evolved divergently in our experimental populations to influence parental investment.
VISION — an open-source software for automated multi-dimensional image analysis of cellular biophysics
Authors: Weber Florian , Iskrak Sofiia , Ragaller Franziska , Schlegel Jan , Plochberger Birgit , Sezgin Erdinc , Andronico Luca A.
Published: March 2024

Environment-sensitive probes are frequently used in spectral/multi-channel microscopy to study alterations in cell homeostasis. However, the few open-source packages available for processing of spectral images are limited in scope. Here, we present VISION, a stand-alone software based on Phyton for spectral analysis with improved applicability. In addition to classical intensity-based analysis, our software can batch-process multidimensional images with an advanced single-cell segmentation capability and apply user-defined mathematical operations on spectra to calculate biophysical and metabolic parameters of single cells. VISION allows for 3D and temporal mapping of properties such as membrane fluidity and mitochondrial potential. We demonstrate the broad applicability of VISION by applying it to study the effect of various drugs on cellular biophysical properties; the correlation between membrane fluidity and mitochondrial potential; protein distribution in cell-cell contacts; and properties of nanodomains in cell-derived vesicles. Together with the code, we provide a graphical user interface for facile adoption. We anticipate that VISION will find a broad range of applications in different fields of biology, spanning from molecular and tissue biology to immunology and biophysics.

Summary statement

VISION, an open-source software, enables high throughput and correlative analysis of cellular biophysical properties.
Correlation between the exchange bias effect and antisite disorder in
Sr2−xLaxCoNbO6

(x=0, 0.2)
Authors: Kumar Ajay , Schwarz B. , Dhaka R. S.
Published: March 2024

We unravel the effect of La substitution and hence antisite disorders on the exchange bias (EB) mechanism in Sr2−xLaxCoNbO6 (x=0, 0.2) double-perovskite samples using the detailed analysis of the field cooled magnetization isotherms (M−H) and training effect. The field dependence of the freezing temperature deviates from both Gabay-Toulouse and de Almeida-Thouless lines and the analysis suggests that the x=0 sample follows a different universality class with moderate anisotropy in the frozen spins. Interestingly, we find that the EB effect is significantly suppressed in the x=0.2 sample due to increase [decrease] in the size of ferromagnetic (FM) [cluster glass (CG)] domain, which reduces the effective disordered interface responsible for the EB. The changes in fraction of FM, antiferromagnetic, and CG-like interactions with the La substitution and applied magnetic field are found to be crucial in governing the EB effect in these samples. Furthermore, the training effect measurements show the unequal shift in the left and right branches of the M−H loops and their different evolution with the field cycles (n). The analysis reveals that the rotatable spins relax approximately one order of magnitude faster than the frozen spins at the disordered interface. We find a possible correlation between the observed EB effect and the antisite disorders in these samples.

Published by the American Physical Society
2024
Propagation of focused scalar and vector vortex beams in anisotropic media: A semianalytical approach
Authors: Aita Vittorio , Shevchenko Mykyta , Rodríguez-Fortuño Francisco J. , Zayats Anatoly V.
Published: March 2024

In the field of structured light, the study of optical vortices and their vectorial extension—vectorial vortex beams—has garnered substantial interest due to their unique phase and polarization properties, which make them appealing for many potential applications. Combining the advantages of vortex beams and anisotropic materials, unique possibilities for electromagnetic field tailoring and manipulation can be achieved in nonlinear optics, quantum and topological photonics. These applications call for a comprehensive modeling framework that accounts for properties of both anisotropic materials and vector vortex beams. In this paper, we describe a semianalytical model that extends the vectorial diffraction theory to the case of focused vortex beams propagating through a uniaxial slab, considering both the cases of scalar and vectorial vortices in the common framework of a Laguerre-Gaussian mode basis. The model aims to provide a comprehensive description of the methodology, enabling the implementation of complex beam transmission through, reflection from, and propagation in uniaxial anisotropic materials for specific applications. As a demonstration of its versatility, we apply the developed approach to describe propagation of high-order vortex beams in uniaxial materials with various dispersion characteristics, exploring the elliptic, hyperbolic and epsilon-near-zero regimes. We show how variations of the medium anisotropy modify the beam structure due to the vectorial nature of their interaction, which results from the different permittivities of the medium for transverse and longitudinal field components. The applicability of the approach can be extended to artificially structured media if they can be described by effective medium parameters. The developed formalism will be useful for modeling interaction of complex beams with uniaxial materials, allowing a common framework for a large variety of situations, which can also be extended beyond the electromagnetic waves.

Published by the American Physical Society
2024
Maximally local two-nucleon interactions at
N3LO
in
Δ
-less chiral effective field theory
Authors: Somasundaram R. , Lynn J. E. , Huth L. , Schwenk A. , Tews I.
Published: March 2024

We present new maximally local two-nucleon interactions derived in Δ-less chiral effective field theory up to next-to-next-to-next-to-leading order (N3LO), which include all contact and pion-exchange contributions to the nuclear Hamiltonian up to this order. Our interactions are fit to nucleon-nucleon phase shifts using a Bayesian statistical approach, and explore a wide cutoff range from 0.6–0.9 fm (≈660–440MeV). These interactions can be straightforwardly employed in quantum Monte Carlo methods, such as the auxiliary field diffusion Monte Carlo method. Together with local three-nucleon forces, calculations with these new interactions will provide improved benchmarks for the structure of atomic nuclei and serve as crucial input to analyses of astrophysical phenomena of neutron stars, such as binary neutron-star mergers.

Published by the American Physical Society
2024
Sensitivity of polarizations and spin correlations of
Z
boson to anomalous neutral triple gauge couplings at lepton collider with polarized beams
Authors: Subba Amir , Singh Ritesh K.
Published: March 2024

We investigate the effects of anomalous neutral triple gauge couplings in ZZ and Zγ production processes, followed by the leptonic decay of the Z boson, at a lepton collider with center-of-mass energy s=250  GeV and polarized beams. We use an effective Lagrangian formalism to parametrize the anomalous couplings in terms of dimension-8 operators cB˜W, cBW, cWW, and cBB, and study the sensitivity of observables such as cross section, polarization, and spin correlation as functions of these couplings. We perform a Bayesian statistical analysis using Markov Chain Monte Carlo methods to determine simultaneous limits on the anomalous couplings, taking into account various luminosities L∈{0.1  ab−1,0.3  ab−1,1  ab−1,3  ab−1,10  ab−1} and systematic uncertainties. We find that polarization and spin correlation observables significantly enhance the sensitivity to anomalous couplings, providing stringent constraints on these couplings.

Published by the American Physical Society
2024
Cosmological domain walls from the breaking of
S4
flavor symmetry
Authors: Jueid Adil , Loualidi Mohamed Amin , Nasri Salah , Ouahid Mohamed Amine
Published: March 2024

In this work, we delve into the often overlooked cosmological implications of the spontaneous breaking of the non-Abelian discrete groups, specifically focusing on the formation of domain walls in the case of S4 flavor symmetry. In particular, we investigate three interesting breaking patterns of the S4 group and study the structure of the domain walls in the broken phase for three possible residual symmetries. The presentation of domain walls in the case of multiple vacua is usually complicated, which therefore implies that most of the analyses only approximate their presentation. Here, we propose a subtle way to represent the S4 domain wall networks by presenting the vacua in each breaking pattern as vectors with their components corresponding to their coordinates in the flavon space. Then, through the properties of the obtained vectors, we find that the domain wall networks can be represented by Platonic or Archimedean solids where the vertices represent the degenerate vacua while the edges correspond to the domain walls that separate them. As an illustration, we propose a type-II seesaw model that is based on the S4 flavor symmetry, and study its phenomenological implications on the neutrino sector. To solve the domain wall problem within this toy model, we consider an approach based on high-dimensional effective operators induced by gravity that explicitly break the structure of the induced vacua favoring one vacuum over the others.

Published by the American Physical Society
2024
Higher twist corrections to
B
-meson decays into a proton and dark antibaryon from QCD light-cone sum rules
Authors: Boushmelev Anastasia , Wald Marcel
Published: March 2024

The B-mesogenesis framework anticipates decays of B mesons into a dark antibaryon Ψ and various Standard Model baryons. Here, we focus on the exclusive decay process B→pΨ observed as a proton and missing energy in the final state and determine the decay width by employing the QCD light-cone sum rule framework. We include all contributions up to twist six to the nucleon distribution amplitudes in order to parametrize the nonperturbative effects in the operator product expansion. We obtain the decay width and branching fraction with respect to the mass mΨ of the dark antibaryon Ψ.

Published by the American Physical Society
2024
Postinflationary production of particle dark matter: Hilltop and Coleman-Weinberg inflation
Authors: Ghoshal Anish , Khlopov Maxim Yu. , Lalak Zygmunt , Porey Shiladitya
Published: March 2024

We investigate the production of nonthermal dark matter (DM), χ, during the postinflationary reheating era. For inflation, we consider two slow roll single field inflationary scenarios—generalized version of Hilltop (GH) inflation, and Coleman-Weinberg (CW) inflation. Using a set of benchmark values that comply with the current constraints from cosmic microwave background radiation (CMBR) data for each inflationary model, we explored the parameter space involving mass of dark matter particles, mχ, and coupling between inflaton and χ, yχ. For these benchmarks, we find that tensor-to-scalar ratio r can be as small as 2.69×10−6 for GH and 1.91×10−3 for CW inflation, both well inside 1−σ contour on scalar spectral index versus r plane from 2018+BICEP3+2018 dataset, and testable by future cosmic microwave background (CMB) observations, e.g., Simons Observatory. For the production of χ from the inflaton decay satisfying CMB and other cosmological bounds and successfully explaining total cold dark matter density of the present universe, we find that yχ should be within this range O(10−4)≳yχ≳O(10−20) for both inflationary scenarios. We also show that, even for the same inflationary scenario, the allowed parameter space on reheating temperature versus mχ plane alters with inflationary parameters including scalar spectral index, r, and energy scale of inflation.

Published by the American Physical Society
2024
Gravitational neutrino reheating
Authors: Haque Md Riajul , Maity Debaprasad , Mondal Rajesh
Published: March 2024

Despite having important cosmological implications, the reheating phase is believed to play a crucial role in both cosmology and particle physics model building. Conventional reheating models primarily rely on arbitrary coupling between the inflaton and massless fields, which lacks robust predictions. In this article, we propose a novel reheating mechanism where the particle physics model, namely, the type-I seesaw model, is shown to play a major role in the entire reheating process, and the inflaton is assumed to be free from arbitrary coupling. To the best of our knowledge, this is the first reheating model of its kind that, besides being successful in resolving the well-known neutrino mass and baryon asymmetry problems, constrains a large class of inflation models, offers successful reheating, and predicts a distinct primordial gravitational-wave spectrum and nonvanishing lowest active neutrino mass. Our novel mechanism opens up a new avenue of integrating particle physics and cosmology in the context of reheating.

Published by the American Physical Society
2024
Origin of higher Schwarzians
Authors: Krivonos S.
Published: March 2024

In this paper we analyze higher Schwarzians and show that they are closely related to the nonlinear realization of the Virasoro algebra. The Goldstone fields of such a realization provide a new set of SL(2,R) invariant higher Schwarzians that are deeply related to those of Aharonov [], Tamanoi [], and Bonora-Matone [; ; ]. A minor change of the coset space parametrization leads to a new set of SL(2,R) noninvariant higher Schwarzians now related to the Schippers [] and Bertilsson [] Schwarzians.

Published by the American Physical Society
2024
Decoherence from horizons: General formulation and rotating black holes
Authors: Gralla Samuel E. , Wei Hongji
Published: March 2024

Recent work by Danielson, Satishchandran, and Wald (DSW) has shown that black holes—and, in fact, Killing horizons more generally—impart a fundamental rate of decoherence on all nearby quantum superpositions. The effect can be understood from measurement and causality: An observer (Bob) in the black hole should be able to disturb outside quantum superpositions by measuring their superposed gravitational fields, but since his actions cannot (by causality) have this effect, the superpositions must automatically disturb themselves. DSW calculated the rate of decoherence up to an unknown numerical factor for distant observers in Schwarzschild spacetime, Rindler observers in flat spacetime, and static observers in de Sitter spacetime. Working in electromagnetic and Klein-Gordon analogs, we flesh out and generalize their calculation to derive a general formula for the precise decoherence rate for Killing observers near bifurcate Killing horizons. We evaluate the rate in closed form for an observer at an arbitrary location on the symmetry axis of a Kerr black hole. This fixes the numerical factor in the distant-observer Schwarzschild result, while allowing new exploration of near-horizon and/or near-extremal behavior. In the electromagnetic case we find that the decoherence vanishes entirely in the extremal limit, due to the “black hole Meissner effect” screening the Coulomb field from entering the black hole. This supports the causality picture: Since Bob is unable to measure the field of the outside superposition, no decoherence is necessary—and indeed none occurs.

Published by the American Physical Society
2024
Polyakov blocks for the 1D conformal field theory mixed-correlator bootstrap
Authors: Ghosh Kausik , Kaviraj Apratim , Paulos Miguel F.
Published: March 2024

We introduce manifestly crossing-symmetric expansions for arbitrary systems of 1D CFT correlators. These expansions are given in terms of certain Polyakov blocks which we define and show how to compute efficiently. Equality of operator product expansion and Polyakov block expansions leads to sets of sum rules that any mixed correlator system must satisfy. The sum rules are diagonalized by correlators in tensor product theories of generalized free fields. We show that it is possible to do a change of a basis that diagonalizes instead mixed correlator systems involving elementary and composite operators in a single field theory. As an application, we find the first nontrivial examples of optimal bounds, saturated by the mixed correlator system ϕ,ϕ2 in the theory of a single generalized free field.

Published by the American Physical Society
2024
Theory of Nonlinear Diffusion with a Physical Gapped Mode
Authors: Abbasi Navid , Kaminski Matthias , Tavakol Omid
Published: March 2024

In a system with one conserved charge the charge diffusion is modified by nonlinear self-interactions within an effective field theory (EFT) of diffusive fluctuations. We include the slowest ultraviolet (UV) mode, constructing a UV-regulated EFT. The relaxation time of this UV mode is protected from renormalization, as supported by experimental data in a bad metal system. Furthermore, the retarded density-density Green’s function acquires four branch points, eventually increasing the range of applicability. We discuss the fate of long time tails as well as implications for the quark gluon plasma.

Published by the American Physical Society
2024
An analytical solution and stability analysis of asymmetric non-actuator guided projectiles
Authors: Taban Mahmoud , Novinzadeh Alireza Basohbat
Published: March 2024

Purpose

One of the challenges encountered in the design of guided projectiles is their prohibitive cost. To diminish it, an appropriate avenue many researchers have explored is the use of the non-actuator method for guiding the projectile to the target. In this method, biologically inspired by the flying concept of the single-winged seed, for instance, that of maple and ash trees, the projectile undergoes a helical motion to scan the region and meet the target in the descent phase. Indeed, the projectile is a decelerator device based on the autorotation flight while it attempts to resemble the seed’s motion using two wings of different spans. There exists a wealth of studies on the stability of the decelerators (e.g. the mono-wing, samara and pararotor), but all of them have assumed the body (exclusive of the wing) to be symmetric and paid no particular attention to the scanning quality of the region. In practice, however, the non-actuator-guided projectiles are asymmetric owing to the presence of detection sensors. This paper aims to present an analytical solution for stability analysis of asymmetric decelerators and apprise the effects of design parameters to improve the scanning quality.

Design/methodology/approach

The approach of this study is to develop a theoretical model consisting of Euler equations and apply a set of non-dimensionalized equations to reduce the number of involved parameters. The obtained governing equations are readily applicable to other decelerator devices, such as the mono-wing, samara and pararotor.

Findings

The results show that the stability of the body can be preserved under certain conditions. Moreover, pertinent conclusions are outlined on the sensitivity of flight behavior to the variation of design parameters.

Originality/value

The analytical solution and sensitivity analysis presented here can efficiently reduce the design cost of the asymmetric decelerator.
Multidimensional poverty analysis of women, children and households in Nigeria: the first order dominance approach
Authors: Okogun Oluwanishola , Hiwatari Masato
Published: March 2024

Purpose

This study examines the dynamics of multidimensional poverty in Nigeria from 2003 to 2018, focusing on women and children, to understand the reality of poverty in Nigeria, where poverty reduction has been stagnant.

Design/methodology/approach

This study employed the first-order dominance (FOD) methodology to conduct a multidimensional analysis of poverty among households, women and children in Nigeria, using data from the Demographic and Health Surveys (DHS) conducted in 2003, 2008, 2013 and 2018. We examined how the relative position of multidimensional poverty in each zone has changed for approximately 20 years.

Findings

The results indicated that the north-south poverty gap in Nigeria persisted as of 2018 and, regarding within the north and south, changes in the relative pecking order of poverty between the zones have occurred considerably over the past two decades. Different trends were also observed for child and female poverty, suggesting the influence of the unique dimensions of poverty and cultural differences.

Originality/value

This study is the first poverty analysis to apply the FOD approach to children and women in Nigeria, the country with the highest poverty, over a relatively long period of 2003–2018.
The Zomato dilemma: a realistic growth trajectory and share price fair valuation?
Authors: Tuyon Jasman , Huang Chia-Hsing , Swanepoel Danielle
Published: March 2024

Learning outcomes

This case study is related to start-up post-listing investment analysis. Through this case study, students will be able to perform the business analysis guided by the Venture Evaluation Metric tool, perform financial analysis using the discounted cash flow methods and perform investment analysis recommendation with justifications from the business and financial analysis performed above.

Case overview/synopsis

This case study sets out the study of a scalable start-up, Zomato, which is a successfully listed start-up firm in India. Despite the start-up development success in the pre-listing, the firm has exhibited a continuous unprofitable finance performance in the post-listing and has further experienced a volatile share price performance, both of which have puzzled existing and potential investors. In addition, some analysts are in the opinions that the firm share price valuation have been inflated with overvaluation since in the initial public offering stage and remain traded with overvaluation in the market. Notably, considering the negative indicators mentioned above, investors are concerned about long-term sustainability of the firm business and financial performance. In the context of post-listing investment, the following questions are material to investors: What is the realistic growth trajectory for Zomato in the medium term? What is Zomato’s share fair value in the medium term? Can one see opportunities or risks ahead of investing in Zomato’s shares? What will be the investment strategy for new investors?

Complexity academic level

This case study is suited to bachelor’s and master’s level in business schools studying entrepreneurial finance analysis.

Supplementary material

Teaching notes are available for educators only.

Subject code

CSS 1: Accounting and finance.
Food insecurity: addressing a challenging social problem with supply chains and service ecosystems
Authors: García-Dastugue Sebastián Javier , García-Contreras Rogelio , Stauss Kimberly , Milford Thomas , Leuschner Rudolf
Published: March 2024

Purpose

Extant literature in supply chain management tends to address a portion of the product flow to make food accessible to clients in need. The authors present a broader view of food insecurity and present nuances relevant to appreciate the complexities of dealing with this social problem.

Design/methodology/approach

The authors conducted an inductive study to reveal the deep meaning of the context as managers of nonprofit organizations (NPO) define and address food insecurity. The focus was on a delimited geographic area for capturing interactions among NPOs which have not been described previously.

Findings

This study describes the role of supply chains collaborating in unexpected ways in the not-for-profit context, leading to interesting insights for the conceptual development of service ecosystems. This is relevant because the solution for the food insecure stems from the orchestration of assistance provided by the many supply chains for social assistance.

Research limitations/implications

The authors introduce two concepts: customer sharing and customer release. Customer sharing enables these supply chains behave like an ecosystem with no focal organization. Customer release is the opposite to customer retention, when the food insecure stops needing assistance.

Social implications

The authors describe the use of customer-centric measures of success such improved health measured. The solution to food insecurity for an individual is likely to be the result of the orchestration of assistance provided by several supply chains.

Originality/value

The authors started asking who the client is and how the NPOs define food insecurity, leading to discussing contrasts between food access and utilization, between hunger relief and nourishment, between assistance and solution of the problem, and between supply chains and ecosystems.
The psychometric properties of teacher leadership scale: the study of adaptation and validation based on the MLQ-5X in higher education
Authors: Assefa Yalalem , Moges Bekalu Tadesse , Tilwani Shouket Ahmad
Published: March 2024

Purpose

Given the importance of teacher leadership in influencing, motivating and inspiring student learning engagement and associated learning outcomes, a robust instrument to assess this construct is critical. Although there are some teacher leadership instruments available in existing literature, efforts to adapt robust psychometric instruments to measure teachers' leadership practices in Ethiopian higher education institutions have been limited. Therefore, this study attempted to address this gap by adapting the Teacher Leadership Scale (TLS) based on the Multifactor Leadership Questionnaire (MLQ-5X) and validating its psychometric properties for use in higher education settings.

Design/methodology/approach

Using a cross-sectional design, the study involved 409 undergraduate university students who were randomly selected from public universities. Factor analytic methodologies, including exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), were used to analyze the data collected.

Findings

The result confirmed a set of 36 items arranged in nine factors, which have a theoretically supported factor structure, excellent model fit and robust evidence for validity, and reliability and measurement invariance. These results demonstrate that the scale is a strong psychometric tool for measuring the leadership profile and practice of higher education teachers.

Originality/value

It can be concluded that the TLS can assist stakeholders in several ways. Researchers can benefit from the scale to measure teachers' leadership practices and predict their influence on student learning outcomes. In addition, the scale can help practitioners and policymakers collect relevant data to rethink teacher professional development initiatives, leadership training programs and other practices aimed at improving teacher leadership effectiveness.
Liquidity and dynamic leverage: the moderating impacts of leverage deviation and target instability
Authors: Ho Ly
Published: March 2024

Purpose

We explore the impact of equity liquidity on a firm’s dynamic leverage adjustments and the moderating impacts of leverage deviation and target instability on the link between equity liquidity and dynamic leverage in the UK market.

Design/methodology/approach

In applying the two-step system GMM, we estimate our model by exploring suitable instruments for the dynamic variable(s), i.e. lagged values of the dynamic term(s).

Findings

Our analyses document that a firm’s equity liquidity has a positive impact on the speed of adjustment (SOA) of its leverage ratio back to the target ratio in the UK market. We also demonstrate that the positive relationship between liquidity and SOA is more pronounced for firms whose current position is relatively close to their target leverage ratio and whose target ratio is relatively stable.

Practical implications

This study provides important implications for both firms’ managers and investors. Particularly, firms’ managers who wish to increase the leverage SOA to enhance firms’ value need to give great attention to their equity liquidity. Investors who want to evaluate firms’ performance could also consider their equity liquidity and leverage SOA.

Originality/value

We are the first to enrich the literature on leverage adjustments by identifying equity liquidity as a new determinant of SOA in a single developed country with many differences in the structure and development of capital markets, ownership concentration and institutional characteristics. We also provide new empirical evidence of the joint effect of equity liquidity, leverage deviation and target instability on leverage SOA.