End State Research Articles

Topological magnetic line defects in Fe(Te, Se) high-temperature superconductors

The realization of Majorana zero modes in condensed matter have been attracting enormous interests from fundamental science such as topological quantum computation. Recently iron based superconductors were identified as a high-temperature platform for realizing topological superconductivity and Majorana modes. As unconventional superconductors, one of the most important characteristics of them is that they are in the vicinity of magnetic states due to the strong Hund’s coupling in iron atoms. Here we propose that the line defects with missing Te/Se anions in Fe(Se, Te) superconductors provide the realization of intrinsic antiferromagnetic (AFM) chains with Rashba spin-orbit coupling. Against conventional wisdom, Majorana zero modes (MZMs) can be robustly generated at these AFM chain ends. These results can consistently explain the recent experimental observation of zero-energy end states in line defects of monolayer Fe(Te, Se)/SrTiO3 by scanning tunneling microscopy (STM) measurements. Our research not only demonstrates an unprecedented interplay among native line defect, emergent magnetism and topological superconductivity but also explores a high-temperature platform for Majorana fermions.

Mars' atmosphere, volatiles, and climate as the sun heats up over the next 6 billion years

As the solar luminosity continues to increase over the next 6 billion years, the Martian surface will heat up to above the melting temperature of water ice. Water ice currently in the polar caps and ground ice will melt, potentially repopulating crater lakes or a very small ocean, with the abundance possibly enhanced due to diffusion upward of water currently locked in the deep crust. CO2 adsorbed in the regolith and locked up in the south-polar ice cap will diffuse into the atmosphere, providing up to 50 mbar total pressure; this will further increase the temperature via greenhouse warming. There are two end-member scenarios for the climate under these conditions: (i) Surface water could drive an atmospheric water cycle somewhat analogous to present-day Earth's, which would create a global clement climate conducive to the existence of widespread surface life. (ii) The widespread presence of liquid water could cause CO2 to form carbonate minerals and H2O to hydrate surface/subsurface minerals (or allow H released from water to escape to space), and CO2 and H2O could be lost to space, leaving Mars with a dry environment. The climate could end up between these end-members and also could vary with time. This uncertain climate end state informs our view that exoplanet evolution and habitability can be driven by endogenous processes associated with a terrestrial planet as well as by the ability of EUV and a stellar wind from the host star to strip away atmosphere.

Neuro‐PINN: A hybrid framework for efficient nonlinear projection equation solutions

AbstractNonlinear projection equations (NPEs) provide a unified framework for solving various constrained nonlinear optimization and engineering problems. This paper presents a deep learning approach for solving NPEs by incorporating neurodynamic optimization and physics‐informed neural networks (PINNs). First, we model the NPE as a system of ordinary differential equations (ODEs) using neurodynamic optimization, and the objective becomes solving this ODE system. Second, we use a modified PINN to serve as the solution for the ODE system. Third, the neural network is trained using a dedicated algorithm to optimize both the ODE system and the NPE. Unlike conventional numerical integration methods, the proposed approach predicts the end state without computing all the intermediate states, resulting in a more efficient solution. The effectiveness of the proposed framework is demonstrated on a collection of classical problems, such as variational inequalities and complementarity problems.

Teaching and Evaluating an Occupational Perspective in Canada: A Descriptive Qualitative Study.

Background. Occupation is the core domain of occupational therapy, and an occupational perspective is foundational for practice. Research has explored how an occupational perspective is taught. Yet, little has explored the Canadian occupational therapy educational context. There are national differences in core competencies and accreditation standards and nuances in how occupation is defined and what conceptual models are used. As such, a Canadian perspective may offer new understandings of value both within and outside of Canada. Purpose. To understand how, in Canada, educators teach and evaluate student occupational perspectives in entry-level master of occupational therapy programs. Method. This study used a descriptive qualitative design with an interpretive approach. Semi-structured interviews were used to gather data from 12 educators from Canadian entry-level occupational therapy programs. Reflexive thematic analysis was used for data analysis. Findings. Five themes were identified: (1) occupational perspectives as pedagogy (2) it's a process, not an end state; (3) "everybody is involved": a community of educators; (4) thinking critically; and (5) "hard to evaluate." Conclusion. The complex, dynamic, and contextualized nature of an occupational perspective calls for critical, reflexive, communal, and innovative pedagogical and assessment approaches.

Edge state behavior in a Su–Schrieffer–Heeger like model with periodically modulated hopping

Su–Schrieffer–Heeger (SSH) model is one of the simplest models to show topological end/edge states and the existence of Majorana fermions. Here we consider a SSH like model both in one and two dimensions where a nearest neighbor hopping features spatially periodic modulations. In the 1D chain, we witness appearance of new in-gap end states apart from a pair of Majorana zero modes (MZMs) when the hopping periodicity go beyond two lattice spacings. The pair of MZMs, that appear in the topological regime, characterize the end modes each existing in either end of the chain. These, however, crossover to both-end end modes for small hopping modulation strength in a finite chain. Contrarily in a 2D SSH model with symmetric hopping that we consider, both non-zero and zero energy topological states appear in a finite square lattice even with a simple staggered hopping, though the zero energy modes disappear in a ribbon configuration. Apart from edge modes, the 2D system also features corner modes as well as modes with satellite peaks distributed non-randomly within the lattice. In both the dimensions, an increase in the periodicity of hopping modulation causes the zero energy Majorana modes to become available for either sign of the modulation. But interestingly with different periodicity for hopping modulations in the two directions, the zero energy modes in a 2D model become rarer and does not appear for all strength and sign of the modulation.

The Need forArtificial Intelligence Curriculum inMilitary Medical Education.

The success of deep-learning algorithms in analyzing complex structured and unstructured multidimensional data has caused an exponential increase in the amount of research devoted to the applications of artificial intelligence (AI) in medicine in the past decade. Public release of large language models like ChatGPT the past year has generated an unprecedented storm of excitement and rumors of machine intelligence finally reaching or even surpassing human capability in detecting meaningful signals in complex multivariate data. Such enthusiasm, however, is met with an equal degree of both skepticism and fear over the social, legal, and moral implications of such powerful technology with relatively little safeguards or regulations on its development. The question remains in medicine of how to harness the power of AI to improve patient outcomes by increasing the diagnostic accuracy and treatment precision provided by medical professionals. Military medicine, given its unique mission and resource constraints,can benefit immensely from such technology. However, reaping such benefits hinges on the ability of the rising generations of military medical professionals to understand AI algorithms and their applications. Additionally, they should strongly consider working with them as an adjunct decision-maker and view them as a colleague to access and harness relevant information as opposed to something to be feared. Ideas expressed in this commentary were formulated by a military medical student during a two-month research elective working on a multidisciplinary team of computer scientists and clinicians at the National Library of Medicine advancing the state of the art of AI in medicine. A motivation to incorporate AI in the Military Health System is provided, including examples of applications in military medicine. Rationale is then given for inclusion of AI in education starting in medical school as well as a prudent implementation of these algorithms in a clinical workflow during graduate medical education. Finally, barriers to implementation are addressed along with potential solutions. The end state is not that rising military physicians are technical experts in AI; but rather that they understand how they can leverage its rapidly evolving capabilities to prepare for a future where AI will have a significant role in clinical care. The overall goal is to develop trained clinicians that can leverage these technologies to improve the Military Health System.

Gravitational study of escape routes and residence regions of Ceres and Vesta fragments

Aims. Ceres and Vesta are the two largest bodies in the main asteroid belt (MB) and have been extensively studied, particularly since the DAWN mission. Vesta is known to have an associated asteroid family, while the existence of a Ceres family is uncertain. This study investigates the fate of multi-kilometre fragments ejected from Ceres and Vesta due to impacts over a timescale of several hundred million years. Methods. We performed purely gravitational N-body simulations to investigate the dynamical evolution of multi-kilometre-sized fragments ejected from Ceres and Vesta. We tracked the trajectories of these fragments and identified their residence regions within the MB. We analysed the escape routes and end states of the fragments that manage to leave the MB, including the delivery to the near-Earth asteroids (NEAs). We also estimated the number of collisions with Earth that could be attributed to large fragments ejected from Ceres and Vesta. Results. Our simulations show that the Ceres fragments are dispersed over a larger region in the MB compared to Vesta fragments due to their higher ejection velocities. We identified the escape routes of the fragments that leave the MB, which for the Ceres fragments are the 5:2 and 8:3 mean-motion resonances (MMR), and for the Vesta fragments are the 3:1 MMR and ν6 secular resonance, where they can be delivered to the NEA region. We also find that the Pristine region, located between the 5:2 and 7:3 MMR, is the most likely place to find any surviving member of a Ceres family. There were no collisions of large Ceres or Vesta fragments with Earth over the age of the Solar System, suggesting that, under the model considered here, the howardite–eucrite–diogenite meteorites originate from smaller NEAs from Vesta.

Structure of the equivalent Newtonian systems in MONDN-body simulations

Aims.We investigate the core-cusp problem of the Λ cold dark matter (ΛCDM) scenario in the context of the modified Newtonian dynamics (MOND) paradigm while exploiting the concept of an equivalent Newtonian system (ENS).Methods.By means of particle-meshN-body simulations in MOND, we explored the processes of galaxy formation via cold dissipationless collapse and the merging of smaller substructures. From the end states of our simulations, we recovered the associated ENS and studied the properties of their dark matter halos. We compared the simulation results with simple analytical estimates with a family ofγ-models.Results.We find that the dark matter density of ENSs of most spherical cold collapses have a markedly cored structure, particularly for the lowest values of the initial virial ratios. End states of some simulations with initially clumpy conditions have more complex profiles, and some of their ENSs exhibit a moderate cusp, with the logarithmic density slope always shallower than one.Conclusions.In contrast to what one would expect from theoretical and numerical arguments in ΛCDM, these results seem to point towards the fact that the absence of a central DM cusp in most observed galaxies would be totally consistent in a MONDian description.

'Everything Changes in Nature': Kropotkin's Process Philosophy

A frequent misunderstanding about Peter Kropotkin, and anarchism more generally, is that by emphasising mutual aid as a factor of evolution and history, he advocates a view of human nature as essentially benign. This essay aims to disprove that claim by showing that Kropotkin explicitly rejects any notion of a fixed human essence and insists that we are composed of a multitude of autonomous but interacting faculties with no authentic or essential centre. This view of the human psyche reflects his view of the world in general: for Kropotkin, philosophy and science were not about finding universal mechanisms and eternal substances. Instead, he advances a view of the world that can only be described as process-thinking: a philosophical tendency that prioritises difference over identity and change over stability. Kropotkin's process ontology also informs his view of politics, which rejects the idea of a harmonious social end state free of conflict and embraces diversity as a factor that promotes progress and movement. Kropotkin's process philosophy has relevance to debates in such diverse fields as philosophy and metaphysics, political and social theory, and biology and ecology.

Who Do We Turn to and What Do We Get? Cultural Differences in Attachment Structure and Function Among East Asian and Western Individuals.

To whom do we turn for support in times of need, and what does the support from close others convey? The present research investigated how the structure and function of attachment differ for individuals in East Asian and Western cultures. In three studies, using survey and daily diary data, we examined the role of the romantic partner as an attachment figure, and the consequences of receiving responsive support in close relationships among individuals in Korea and the United States. As expected, the role of the romantic partner as an attachment figure was less emphasized for Koreans compared with U.S. participants. Also, responsive support from close others was more strongly linked to affiliation-related end states (i.e., in-group agency) for Koreans than U.S. individuals. The present research demonstrates the need to consider nuanced cultural influences in the attachment literature for the broader application of the theory.

Correlation effects on topological end-states in finite-size graphene nanoribbons in the GW approximation

Finite size armchair graphene nanoribbons (GNRs) of different families are theoretically studied using the Hubbard model in both mean-field and GW approximations, including spin correlation effects. It is shown that correlation primarily affect the properties of topological end states of the nanoribbons. A representative structure of each of the three GNR families is considered but the seven-atom width nanoribbon is studied in detail and compared to previously published experimental results, showing a clear improvement when correlations are included. Using isolated spin contributions to scanning tunneling microscopy (STM) simulations, spin-polarized measurements in STM are also suggested to help distinguish and highlight correlation effects.

Revealing the developmental origin and lineage predilection of neural progenitors within human bone marrow via single-cell analysis: implications for regenerative medicine

BackgroundHuman bone marrow stromal cells (BMSCs) are an easily accessible and expandable progenitor population with the capacity to generate neural cell types in addition to mesoderm. Lineage tracing studies in transgenic animals have indicated Nestin + BMSCs to be descended from the truncal neural crest. Single-cell analysis provides a means to identify the developmental origin and identity of human BMSC-derived neural progenitors when lineage tracing remains infeasible. This is a prerequisite towards translational application.MethodsWe attained transcriptomic profiles of embryonic long bone, adult human bone marrow, cultured BMSCs and BMSC-derived neurospheres. Integrated scRNAseq analysis was supplemented by characterization of cells during culture expansion and following provision of growth factors and signalling agonists to bias lineage.ResultsReconstructed pseudotime upon the integrated dataset indicated distinct neural and osteogenic differentiation trajectories. The starting state towards the neural differentiation trajectory consisted of Nestin + /MKI67 + BMSCs, which could also be diverted towards the osteogenic trajectory via a branch point. Nestin + /PDGFRA + BMSCs responded to neurosphere culture conditions to generate a subpopulation of cells with a neuronal phenotype according to marker expression and gene ontogeny analysis that occupied the end state along the neural differentiation trajectory. Reconstructed pseudotime also revealed an upregulation of BMP4 expression during culture of BMSC-neurospheres. This provided the rationale for culture supplementation with the BMP signalling agonist SB4, which directed progenitors to upregulate Pax6 and downregulate Nestin.ConclusionsThis study suggested BMSCs originating from truncal neural crest to be the source of cells within long bone marrow possessing neural differentiation potential. Unravelling the transcriptomic dynamics of BMSC-derived neural progenitors promises to enhance differentiation efficiency and safety towards clinical application in cell therapy and disease modelling.

Abundance Analysis of Stars at Large Radius in the Sextans Dwarf Spheroidal Galaxy* *This paper includes data gathered at the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Other observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. This paper is also based on archival observations

We present the stellar parameters and chemical abundances of 30 elements for five stars located at large radii (3.5–10.7 times the half-light radius) in the Sextans dwarf spheroidal galaxy. We selected these stars using proper motions, radial velocities, and metallicities, and we confirm them as metal-poor members of Sextans with −3.34 ≤ [Fe/H] ≤ −2.64 using high-resolution optical spectra collected with the Magellan Inamori Kyocera Echelle spectrograph. Four of the five stars exhibit normal abundances of C (−0.34 ≤ [C/Fe] ≤ + 0.36), mild enhancement of the α elements Mg, Si, Ca, and Ti ([α/Fe] = +0.12 ± 0.03), and unremarkable abundances of Na, Al, K, Sc, V, Cr, Mn, Co, Ni, and Zn. We identify three chemical signatures previously unknown among stars in Sextans. One star exhibits large overabundances ([X/Fe] > +1.2) of C, N, O, Na, Mg, Si, and K, and large deficiencies of heavy elements ([Sr/Fe] = −2.37 ± 0.25, [Ba/Fe] = −1.45 ± 0.20, [Eu/Fe] < + 0.05), establishing it as a member of the class of carbon-enhanced metal-poor stars with no enhancement of neutron-capture elements. Three stars exhibit moderate enhancements of Eu (+0.17 ≤ [Eu/Fe] ≤ + 0.70), and the abundance ratios among 12 neutron-capture elements are indicative of r-process nucleosynthesis. Another star is highly enhanced in Sr relative to heavier elements ([Sr/Ba] = +1.21 ± 0.25). These chemical signatures can all be attributed to massive, low-metallicity stars or their end states. Our results, the first for stars at large radius in Sextans, demonstrate that these stars were formed in chemically inhomogeneous regions, such as those found in ultra-faint dwarf galaxies.

Thoughts on Strategy Formulation

This article attempts to clarify and contribute to the formulation of strategy by highlighting its essential components and processes. Strategy is a bridge between political and tactical levels and should not be considered a plan. A classic strategy may consist of ends, ways, means, and risks. A five-stage process consisting of strategic analysis, definition of an end state, identifying means, designing the ways, and assessing the costs and risks can be used in strategy formulation. Yet, the addition of another two phases, which are assessment and management of strategy, is a must for contemporary strategy formulation. Nevertheless, it would be a mistake to take strategy as a rigid formula. The context of a strategy will be changing based on the aim and the field in question. Other than the military and starting with business, many fields continue to use strategy formulation effectively.

A Wealth Distribution Agent Model Based on a Few Universal Assumptions.

We propose a new agent-based model for studying wealth distribution. We show that a model that links wealth to information (interaction and trade among agents) and to trade advantage is able to qualitatively reproduce real wealth distributions, as well as their evolution over time and equilibrium distributions. These distributions are shown in four scenarios, with two different taxation schemes where, in each scenario, only one of the taxation schemes is applied. In general, the evolving end state is one of extreme wealth concentration, which can be counteracted with an appropriate wealth-based tax. Taxation on annual income alone cannot prevent the evolution towards extreme wealth concentration.

Navigating phase space transport with the origin-fate map.

We introduce and demonstrate the usage of the origin-fate map (OFM) as a tool for the detailed investigation of phase space transport in reactant-product-type systems. For these systems, which exhibit clearly defined start and end states, it is possible to build a comprehensive picture of the lobe dynamics by considering backward and forward integration of sets of initial conditions to index their origin and fate. We illustrate the method and its utility in the study of a two degrees of freedom caldera potential with four exits, demonstrating that the OFM not only recapitulates results from classical manifold theory but even provides more detailed information about complex lobe structures. The OFM allows the detection of dynamically significant transitions caused by the creation of new lobes and is also able to guide the prediction of the position of unstable periodic orbits (UPOs). Further, we compute the OFM on the periodic orbit dividing surface (PODS) associated with the transition state of a caldera entrance, which allows for a powerful analysis of reactive trajectories. The intersection of the manifolds corresponding to this UPO with other manifolds in the phase space results in the appearance of lobes on the PODS, which are directly classified by the OFM. This allows computations of branching ratios and the exploration of a fractal cascade of lobes as the caldera is stretched, which results in fluctuations in the branching ratio and chaotic selectivity. The OFM is found to be a simple and very useful tool with a vast range of descriptive and quantitative applications.

Resumption of water capsule reactivity-initiated accident testing at TREAT

A series of integral reactivity-initiated accident commissioning experiments were completed in a new static water capsule in the Transient Reactor Test Facility (i.e., TREAT), marking the first such tests in the United States in more than 40 years. The test campaign included a verification test followed by five tests in the Static Environment Rodlet Transient Test Apparatus capsule. The capsule’s initial conditions varied from room temperature and pressure up to 200 °C and 2.5 MPa, with energy depositions varying between ∼ 500–1,100 J/gUO2. The series of tests allowed for a number of instrumentation qualifications and demonstrations, including cladding thermometry, rodlet plenum pressure, cladding elongation, and an electro-impedance boiling detector. Post-transient examinations such as gamma emission spectroscopy, profilometry, and microscopy were performed to document the end state of the fuel rods. The results from the experiments show that the fuel rodlets behaved very similar to historical tests under similar energy depositions. This paper documents the design of the capsule and highlights some results from the commissioning tests and post-transient examination.

Engineering topologically protected zero-dimensional interface end states in antiferromagnetic heterojunction graphene nanoflakes

Engineering topologically protected zero-dimensional interface end states in antiferromagnetic heterojunction graphene nanoflakes

Interacting Networks in Social Landscapes: A Devo-Evo Approach to Socialcultural Dynamics

Can the study of epigenetics, physiology, and cognitive science contribute to the investigation and understanding of social-cultural systems while respecting the autonomy of social research? I present a developmental system theory (DST) approach, which takes the unit of analysis to be the system of self-sustaining interactions among multiple biological, psychological, and social resources. On this view, the cybernetic architecture of the networks that constitute the system channels development so that different trajectories lead to convergent end states, accounting for the system’s developmental stability as well as shedding light on the conditions that lead to departures from typical outcomes. Based on previous work, which is extended here, I suggest that Waddington’s epigenetic landscape metaphor, which was built to illustrate the relationship between genetic networks and embryological development, is a useful tool for thinking about the temporal dynamics of social systems, capturing some important features of social stability and change at different scales and levels of social organization. I discuss five social systems using the landscape metaphor and explore the implications of this DST approach for investigating the relations between sociocultural development and evolution.

Gravitational wave hints black hole remnants as dark matter

The end state of Hawking evaporation of a black hole is uncertain. Some candidate quantum gravity theories, such as loop quantum gravity and asymptotic safe gravity, hint towards Planck sized remnants. If so, the Universe might be filled with remnants of tiny primordial black holes, which formed with mass g. A unique scenario is the case of g, where tiny primordial black holes reheat the Universe by Hawking evaporation and their remnants dominate the dark matter (DM). Here, we point out that this scenario leads to a cosmological gravitational wave signal at frequencies ∼100 Hz. Finding such a particular gravitational wave signature with, e.g. the Einstein telescope, would suggest black hole remnants as DM.