High Degree Of Coherence Research Articles

African Sovereign Risk Premia and International Market Assets: A Relook Under The COVID-19 Outbreak

Using the wavelet multiscale coherence technique, the paper examines the interdependences between global market assets, sovereign credit default swap (CDS) and yield-to-maturity on bond spread for African economies from January 2019 to March 2023. The empirical results primarily reveal a high level of coherence between global market assets and Africa’s sovereign CDS and yield-to-maturity, although varying across countries and time-frequency domain. Notably, the high degree of coherence and the positive co-movement between sovereign CDS and global market assets are more concentrated at the medium and upper frequency bands. The observed intensity of co-movements between global market assets and sovereign CDS/yield-to-maturity (YTM) of bond spread, with global market assets broadly serving as leading variables, suggests that an increased global investor’s risk aversion positively affects the yields on Africa market bonds. Among the global market assets, we identified that VIX (which is implied volatility of S&P500) has the dominant influence on Africa sovereign CDS/YTM compared to that emanating from Bitcoin and Godman Sachs Commodity Index. This is highly conceivable as VIX gauges bubbling global risks and uncertainties which considerably influences investor’s risk aversion. The heterogeneous lead/lag dynamics also provide useful information to global investors, including by utilizing African markets to rebalance their portfolios for risk management purposes. The empirical findings thus provide further critical information to investors for hedging purposes, and to policymakers in formulating sovereign risk management policies oriented towards minimizing sovereign default risks.

A revision of the dorsal origin of the frontal aslant tract (FAT) in the superior frontal gyrus: a DWI-tractographic study.

The frontal aslant tract (FAT) is a white matter tract connecting the superior frontal gyrus (SFG) to the inferior frontal gyrus (IFG). Its dorsal origin is identified in humans in the medial wall of the SFG, in the supplementary motor complex (SM-complex). However, empirical observation shows that many FAT fibres appear to originate from the dorsal, rather than medial, portion of the SFG. We quantitatively investigated the actual origin of FAT fibres in the SFG, specifically discriminating between terminations in the medial wall and in the convexity of the SFG. We analysed data from 105 subjects obtained from the Human Connectome Project (HCP) database. We parcelled the cortex of the IFG, dorsal SFG and medial SFG in several regions of interest (ROIs) ordered in a caudal-rostral direction, which served as seed locations for the generation of streamlines. Diffusion imaging data (DWI) was processed using a multi-shell multi-tissue CSD-based algorithm. Results showed that the number of streamlines originating from the dorsal wall of the SFG significantly exceeds those from the medial wall of the SFG. Connectivity patterns between ROIs indicated that FAT sub-bundles are segregated in parallel circuits ordered in a caudal-rostral direction. Such high degree of coherence in the streamline trajectory allows to establish pairs of homologous cortical parcels in the SFG and IFG. We conclude that the frontal origin of the FAT is found in both dorsal and medial surfaces of the superior frontal gyrus.

Quantum Dynamics of Oblique Vibrational States in the Hénon-Heiles System.

In this paper, we study the quantum time evolution of oblique nonstationary vibrational states in a Hénon-Heiles oscillator system with two dissociation channels, which models the stretching vibrational motions of triatomic molecules. The oblique nonstationary states we are interested in are the eigenfunctions of the anharmonic zero-order Hamiltonian operator resulting from the transformation to oblique coordinates, which are defined as those coming from nonorthogonal coordinate rotations that express the matrix representation of the second-order Hamiltonian in a block diagonal form characterized by the polyadic quantum number n = n1 + n2. The survival probabilities calculated show that the oblique nonstationary states evolve within their polyadic group with a high degree of coherence up to the dissociation limits on the short time scale. The degree of coherence is certainly much higher than that exhibited by the local nonstationary states extracted from the conventional orthogonal rotation of the original normal coordinates. We also show that energy exchange between the oblique vibrational modes occurs in a much more regular way than the exchange between the local modes.

Enhancing plantain epicarp active edible coating performance through investigation of optimal spray coating conditions

The current research presents a comprehensive investigation aimed at predicting and optimizing the adhesion characteristics of Nanoemulsion coatings sprayed onto plantains epicarps. To achieve this, a full factorial experimental design and an artificial neural network model were deployed. The process parameters, consisting of the height of the nozzle, pressure, and time, served as inputs for the artificial neural network model, while the coating amount and thickness were measured and treated as targets for both models. Through meticulous training, the artificial neural network model demonstrated remarkable efficiency and reliability, evident in the high degree of coherence between predicted and experimental results (R² = 0.99 and MSE = 1.98 %). The study identified a critical sequence of variables (height/pressure/time: 0.15 m / 0.6 MPa / 5 s) that yielded optimal coating characteristics, including a thickness of 38.5 µm, permeance of 1.388 × 10–05 kg s−1 m−1 Pa−1, and water vapor permeability of 2.7 × 10–09 kg s−1 m−1 Pa−1, along with a contact angle of 11.3° indicative of enhanced wettability. Significantly, the coated epicarps exhibited lower water vapor permeability, implying an extended shelf life. This promising technology of edible coatings not only contributes to preserving fruit quality and prolonging shelf life for plantainss but also holds potential for application in other food products and fortifying food packaging practices. The current findings shed light on the valuable role of active edible coatings in advancing food preservation methods and sustainability within the food industry.

Small-angle X-ray scattering in the era of fourth-generation light sources.

Recently, fourth-generation synchrotron sources with several orders of magnitude higher brightness and higher degree of coherence compared with third-generation sources have come into operation. These new X-ray sources offer exciting opportunities for the investigation of soft matter and biological specimens by small-angle X-ray scattering (SAXS) and related scattering methods. The improved beam properties together with the advanced pixel array detectors readily enhance the angular resolution of SAXS and ultra-small-angle X-ray scattering in the pinhole collimation. The high degree of coherence is a major boost for the X-ray photon correlation spectroscopy (XPCS) technique, enabling the equilibrium dynamics to be probed over broader time and length scales. This article presents some representative examples illustrating the performance of SAXS and XPCS with the Extremely Brilliant Source at the European Synchrotron Radiation Facility. The rapid onset of radiation damage is a significant challenge with the vast majority of samples, and appropriate protocols need to be adopted for circumventing this problem.

High Q and sub-wavelength THz electric field confinement in ultrastrongly coupled THz resonators

The control of light–matter coupling at the single electron level is currently a subject of growing interest for the development of novel quantum devices and for studies and applications of quantum electrodynamics. In the terahertz (THz) spectral range, this raises the particular and difficult challenge of building electromagnetic resonators that can conciliate low mode volume and high quality factor. Here, we report on hybrid THz cavities based on ultrastrong coupling between a Tamm cavity and an LC circuit metamaterial and show that they can combine high quality factors of up to Q=37 with a deep-subwavelength mode volume of V=3.2×10−4λ3. Our theoretical and experimental analysis of the coupled mode properties reveals that, in general, the ultrastrong coupling between a metamaterial and a Fabry–Perot cavity is an effective tool to almost completely suppress radiative losses and, thus, ultimately limit the total losses to the losses in the metallic layer. These Tamm cavity-LC metamaterial coupled resonators open a route toward the development of single photon THz emitters and detectors and to the exploration of ultrastrong THz light–matter coupling with a high degree of coherence in the few to single electron limit.

Highly Ordered Supramolecular Materials of Phase-Separated Block Molecules for Long-Range Exciton Transport.

Efficient energy transport over long distances is essential for optoelectronic and light-harvesting devices. Although self-assembled nanofibers of organic molecules have been shown to exhibit long exciton diffusion lengths, alignment of these nanofibers into films with large, organized domains with similar properties remains a challenge. Here, we show how the functionalization of C3 -symmetric carbonyl-bridged triarylamine trisamide (CBT) oligodimethylsiloxane (oDMS) sidechains with discrete length leads to fully covered surfaces with aligned domains up to 125 × 70 μm2 in which long-range exciton transport takes place. The nanoscale morphology within the domains consists of highly ordered nanofibers with discrete intercolumnar spacings within a soft amorphous oDMS matrix. The oDMS prevents bundling of the CBT fibers, reducing the number of defects within the CBT columns. As a result, the columns have a high degree of coherence, leading to exciton diffusion lengths of a few hundred nanometers with exciton diffusivities (∼0.05 cm2 s-1 ) that are comparable to those of a crystalline tetracene. These findings represent the next step towards fully covered surfaces of highly aligned nanofibers through functionalization with oDMS. This article is protected by copyright. All rights reserved.

How to avoid a local epidemic becoming a global pandemic

Here, we combine international air travel passenger data with a standard epidemiological model of the initial 3mo of the COVID-19 pandemic (January through March 2020; toward the end of which the entire world locked down). Using the information available during this initial phase of the pandemic, our model accurately describes the main features of the actual global development of the pandemic demonstrated by the high degree of coherence between the model and global data. The validated model allows for an exploration of alternative policy efficacies (reducing air travel and/or introducing different degrees of compulsory immigration quarantine upon arrival to a country) in delaying the global spread of SARS-CoV-2 and thus is suggestive of similar efficacy in anticipating the spread of future global disease outbreaks. We show that a lesson from the recent pandemic is that reducing air travel globally is more effective in reducing the global spread than adopting immigration quarantine. Reducing air travel out of a source country has the most important effect regarding the spreading of the disease to the rest of the world. Based upon our results, we propose a digital twin as a further developed tool to inform future pandemic decision-making to inform measures intended to control the spread of disease agents of potential future pandemics. We discuss the design criteria for such a digital twin model as well as the feasibility of obtaining access to the necessary online data on international air travel.

Optical frequency comb generation based on spectral broadening of a phase locked dual-wavelength microcavity laser

A highly coherent optical frequency comb (OFC) based on spectral broadening of a phase-locked dual-wavelength microcavity laser is presented. By directly modulating the microcavity laser to generate multiple sidebands, the cross-injection locking of the dual modes is achieved and the beat-signal linewidth is improved from 13.5 MHz to less than 100 Hz. Subsequently, 21 flat comb teeth in a ±3 dB power variation are achieved by combining a phase modulator. Finally, an OFC with a bandwidth of 16 nm is successfully realized by narrowing the optical pulse and spectral broadening in a commercial nonlinear optical fiber. The repetition rate has a low phase noise of −102 dBc Hz−1 at 10 kHz offset, demonstrating the generated OFC has a high degree of coherence.

An approach for the optical and mechanical design of an X-ray beamline: application to the plane-wave CDI station CATERETÊ/SIRIUS

Experiments involving nano-focusing or coherence applications require positional stability of a few nanometers and angular stability of tens of nanoradians for all critical optical components along the beamline (in the range of 1 Hz up to 2.5 kHz). Several optical components based on high-precision mechatronics principles with optimized dynamics to cope with those stability requirements have been recently designed and developed at LNLS. An approach combining optical and mechanical design methodologies and processes was applied to new beamline projects. The process starts with optical design using ray-tracing and wave propagation simulations aiming for the specified beam parameters. In a second step, alignment tolerances and stability issues are addressed in the mechanical design of each component. If those requirements cannot be reached in the predictive models based on the available technologies, size and shape of the optics itself or the optical scheme may be redefined restarting the optical simulation. This work applies this beamline design process to the CATERETÊ beamline, which allows for plane-wave CDI experiments. Using side-bounce deflecting cylindrical mirrors and a four-crystal monochromator, a focused beam size of ~ 40 x 30 μm2 (at 9 keV) with a depth-of-focus of 12 m (plane-wave) and high degree of coherence is obtained. We review key aspects of the optical and mechanical designs. In addition, we further extend the modelling process to enable systematic commissioning support by simulating beam parameters on diagnostic elements located downstream each optical element.

Harmonization of 2020 Round of National Census Programs Across the CIS. Towards the International Comparability of Results

This study draws on the findings of a survey conducted by the Interstate Statistical Committee of the Commonwealth of Independent States (CIS-Stat) in the framework of a joint project with the UNFPA – CISPop «Better Data for Better Policies».The paper aims to present the author’s assessment of the level of harmonization between the national census programs across the CIS and the inter-comparability of their results in terms of total population size and its composition. The study is based on the analysis of methodological documents, which include census forms, manuals for census enumerators (census takers) and technical materials for census personal, that describes the concepts, definitions, and classifications used in national censuses. For countries where no censuses were taken, the authors used materials from pilot censuses and drafts of census documents.The study established that among countries there is a high degree of coherence of national census programs in terms of the key topics, concepts, and classifications used, as well as the wordings of the questions and their prompts. Simultaneously, the analysis allowed us to determine that national statistical services of the region focus on the expectations of their respective populations and take into account national legislation, local conditions, and traditions. First of all, nation-specific features manifested themselves in the formulation of questions concerning the economic, educational, and ethno-cultural characteristics of the population.Analysis of the materials of the works performed on the implementation of the 2020 round of population census programs across the CIS indicates that, based on the data of population censuses conducted in the past few years, it is possible to obtain harmonized data on the size and main characteristics of the population of countries, to provide international comparisons both within the CIS region, and between countries of the region and other countries of the world. International statistical community should be well informed about national practices of the CIS countries so that region-specific features can be accounted for in the international recommendations for future censuses.

‘Walking the talk’: Exploring heterogeneity in gender diversity performance in mining

Although gender diversity has been an increasingly important criterion for investors screening for environmental, social and governance metrics, it has long been a challenge for the mining sector, given its strong legacy and reverence for masculine identity. Mining has consistently continued to significantly lag other industries and cutting across all levels of employment. Moreover, there is reported evidence of notable variations amongst different regions in the matter of gender diversity adoption. We investigate these issues through a qualitative empirical study of self-reported narratives of the 24 largest mining companies spread across eight regions. We find that stronger gender diversity performance is invariably evidenced in a higher degree of coherence between articulated diversity aspirations and specific diversity initiatives. While this interlinkage is more likely symptomatic than causal, we argue that a commitment to stated position drives strategic action and in turn stronger performance. On the contrary, lack of coherence between aspirations and action is likely reflective of a superficial approach to diversity management that in turn tends to derail the diversity agenda.

Single-shot measurement of overall degree of spectral coherence: Bulk-generated supercontinuum case

Spectral and temporal correlations determine the majority of pulse properties, and a high degree of coherence is needed for minimizing the pulse length. However, there is no simple way to quantify these correlations experimentally, and nonlinear methods are often required. In this paper, we confirm an earlier proposed experiment [Koivurova et al., Opt. Lett. 44, 522 (2019)] that can accurately estimate the spectral degree of coherence of arbitrary nonstationary fields. The method is entirely linear and can retrieve the quasicoherent contribution of the spectral correlation function. In particular, the method can be used to measure the overall degree of spectral coherence in a single-shot manner. We first establish the theoretical framework behind the method and experimentally test it for a bulk-generated supercontinuum. Our experimental results are in good agreement with the theory and confirm our earlier numerical findings [Halder et al., Photon. Res. 7, 1345 (2019)]. Moreover, the results yield insight into supercontinuum generation in bulk material.

Numerical and experimental study of partial coherence for near-field and far-field ptychography.

High degree of coherence is essential in coherent diffraction imaging (CDI). The coherence requirement on the light source varies with the experimental configuration. As a scanning variant of CDI, ptychography has shown great potential for extensive applications. To determine the influence of partially temporal and spatial coherence on near- and far-field ptychography, we have performed a series of numerical simulations and visible light optical experiments. We demonstrated that the near-field is more robust to spatial and temporal decoherence than the far-field. In addition, the far-field is found to be more sensitive to spatial decoherence than to temporal decoherence. Our experiments also show that a known probe estimate with good spatial coherence enables the retrieval qualities to be enhanced dramatically and helps prevent falling into the local minimums in the reconstruction process. Our work would provide a valuable reference for implementing ptychography with sources of limited coherence.

Local H I filaments driven by a small-scale dynamo

Context. H I filaments are closely related to dusty magnetized structures that are observable in the far infrared (FIR). Recently it was proposed that the coherence of oriented H I structures in velocity traces the line of sight magnetic field tangling. Aims. We study the velocity-dependent coherence between FIR emission at 857 GHz and H I on angular scales of 18′. Methods. We use HI4PI H I data and Planck FIR data and apply the Hessian operator to extract filaments. For coherence, we require that local orientation angles θ in the FIR at 857 GHz along the filaments be correlated with the H I. Results. We find some correlation for H I column densities at |vLSR| < 50 km s−1, but a tight agreement between FIR and H I orientation angles θ exists only in narrow velocity intervals of 1 km s−1. Accordingly, we assign velocities to FIR filaments. Along the line of sight these H I structures show a high degree of the local alignment with θ, as well as in velocity space. Interpreting these aligned structures in analogy to the polarization of dust emission defines an H I polarization. We observe polarization fractions of up to 80%, with averages of 30%. Orientation angles θ along the filaments, projected perpendicular to the line of sight, are fluctuating systematically and allow a characteristic distribution of filament curvatures to be determined. Conclusions. Local H I and FIR filaments identified by the Hessian analysis are coherent structures with well-defined radial velocities. H I structures are also organized along the line of sight with a high degree of coherence. The observed bending of these structures in the plane of the sky is consistent with models for magnetic field curvatures induced by a Galactic small-scale turbulent dynamo.

Studying the Relation Between Stakeholder Input and Higher Education Policy

This study describes a key feature of modern, democratic policy making, namely the relation between stakeholder input and policy output. In the Nordic countries, there are long traditions for and democratic values attached to the dialogue between the government and civil society when developing policies for the educational sector. The case presented here is the hearing process held by the Norwegian Ministry of Education and Research in 2017 prior to the launch of a white paper on quality culture in higher education. The potential coherence between input by stakeholder groups and the quality measures proposed in the white paper is investigated. The theoretical framework comprises the concept of ‘uploading’ borrowed from research on EU policy making and discursive institutionalism to analyse the representation of input by stakeholder groups when they attempt to ‘upload’ their priorities into the white paper. The methodological approach is content analysis of the hearing responses and the white paper. The findings show that stakeholders from the higher education sector and employer groups had a higher degree of coherence with the proposed measures in the white paper, and universities and colleges had a lower degree of input that was represented.

Shear-Induced Ordering of Nanopores and Instabilities in Concentrated Surfactant Mesh Phases.

Mixed surfactant systems with strongly bound counterions show many interesting phases such as the random mesh phase consisting of a disordered array of defects (water-filled nanopores in the bilayers). The present study addresses the non-equilibrium phase transition of the random mesh phase under shear to an ordered mesh phase with a high degree of coherence between nanopores in three dimensions. In situ small-angle synchrotron X-ray study under different shear stress conditions shows sharp Bragg peaks in the X-ray diffraction, successfully indexed to the rhombohedral lattice with R3̅m space group symmetry. The ordered mesh phase shows isomorphic twinning and buckling at higher shear stress. Our experimental studies bring out rich non-equilibrium phase transitions in concentrated cationic surfactant systems with strongly bound counterions hitherto not well explored and provide motivation for a quantitative understanding.

A Functional Contextualist Account of Behavioral Economics: Relational Frame Theory Applied to Decision-Making and Choice Behavior


 Behavioral economics is a discipline that is mainly rooted in cognitivism and that is concerned with the study of decision-making processes and choice behavior. These involve addressing the relations between cognition and overt behavior, which comprise one of the most challenging topics in the domain of behavioral sciences at large and have been approached by different epistemological viewpoints. Within the cognitivist tradition, private events have been often treated as causes of behaviors, adopting a mechanistic view. Conversely, a contextual functional behavioral perspective treats them with the same methodology that is adopted for overt behaviors. Relational frame theory, a post-Skinnerian theory of language and cognition, offers a behavioral perspective on cognition and overt behavior and how they influence human behavior, by keeping a high degree of coherence with basic principles and goals of behavior analysis (i.e., effective action). This conceptual paper represents an attempt to offer a perspective drawn from contextual behavioral science on some constructs described in behavioral economics. Furthermore, it provides a common ground for behavior analysts and researchers in other fields of psychology to further expand our knowledge and respective explanations of decision-making processes. Finally, it draws a line for connecting basic research to applied solutions.

Contribution of International Projects to the Development of Maritime Spatial Planning Structural Elements in the Northern Adriatic: The Experience of Slovenia

Maritime spatial planning (MSP) has been developing for years on the basis of international commitments, national legislations, and professional practices. Projects under European Territorial Cooperation have also made an important contribution to its development. They were designed to support EU countries in the implementation of MSP. The projects implemented in Slovenia always covered the entire national sea and coastal zone. In accordance with the MSP Directive, the countries of Northern Adriatic are currently preparing the first generation of maritime spatial plans, largely based on the experience and results gained from these projects. This article presents the results of research aimed at assessing the contribution of the projects to the preparation of the first plan in Slovenia. Using a descriptive research method, a detailed analysis of the results of seven projects was conducted and compared with the content of the draft plan. A comparison was made and the proportion of the results implementation in the draft plan was determined for the following structural elements: development baselines, objectives and guidelines; expert bases; stakeholders and public participation; sectoral interests; administrative competences; international dimension; and databases and analytical tools. A high degree of coherence was found, showing the obvious contribution of the projects at the methodological and structural levels.

Nano-scale structural evolution of quaternary AlCrFeNi based high entropy alloys by the addition of specific minor elements and its effect on mechanical characteristics

The AlCrFeNi eutectic high entropy alloys have been developed by adding specific minor elements such as 1, 3, 5 at% of Mo and Ti to analyze the mechanical behavior with double phase strengthening. The X-ray diffraction results illustrate that the crystal structure includes dual phases such as B2 and BCC. Regarding on the compositional variation, the formation of eutectic structure was observed by adding minor elements. The detailed investigation of nano structural evolution of the alloy identified that the morphology of nanoscale Al-Ni-rich B2 phase and Cr-Fe-rich A2 phase have a high degree of coherence in dendritic and lamellar regions. As the result of volume fraction changes and variation in grain size on the nanoscale with the addition of minor elements, the enhancement of mechanical properties confirmed the high-temperature hardness behavior of the alloys. In this study, nanoscale features of the AlCrFeNi based HEAs and mechanical characteristics were explored in detail.