Variability Constraints Research Articles

GaitKeeper: An AI-Enabled Mobile Technology to Standardize and Measure Gait Speed.

Gait speed is increasingly recognized as an important health indicator. However, gait analysis in clinical settings often encounters inconsistencies due to methodological variability and resource constraints. To address these challenges, GaitKeeper uses artificial intelligence (AI) and augmented reality (AR) to standardize gait speed assessments. In laboratory conditions, GaitKeeper demonstrates close alignment with the Vicon system and, in clinical environments, it strongly correlates with the Gaitrite system. The integration of a cloud-based processing platform and robust data security positions GaitKeeper as an accurate, cost-effective, and user-friendly tool for gait assessment in diverse clinical settings.

Conserved and divergent signals in 5' splice site sequences across fungi, metazoa and plants.

In eukaryotic organisms the ensemble of 5' splice site sequences reflects the balance between natural nucleotide variability and minimal molecular constraints necessary to ensure splicing fidelity. This compromise shapes the underlying statistical patterns in the composition of donor splice site sequences. The scope of this study was to mine conserved and divergent signals in the composition of 5' splice site sequences. Because 5' donor sequences are a major cue for proper recognition of splice sites, we reasoned that statistical regularities in their composition could reflect the biological functionality and evolutionary history associated with splicing mechanisms. Results: We considered a regularized maximum entropy modeling framework to mine for non-trivial two-site correlations in donor sequence datasets corresponding to 30 different eukaryotes. For each analyzed species, we identified minimal sets of two-site coupling patterns that were able to replicate, at a given regularization level, the observed one-site and two-site frequencies in donor sequences. By performing a systematic and comparative analysis of 5'splice sites we showed that lineage information could be traced from joint di-nucleotide probabilities. We were able to identify characteristic two-site coupling patterns for plants and animals, and propose that they may echo differences in splicing regulation previously reported between these groups.

Uncertainty of Standardized Track Insulation Measurement Methods for Stray Current Assessment

Stray current is a relevant phenomenon in particular for DC electrified transportation systems, affecting track and infrastructure within the right of way and other structures and installations nearby. It worsens with time and the level of protection depends on timely maintenance, as well as correct design choices. The assessment of track insulation is the starting point for both stray current monitoring systems and at commissioning or upon major changes. Standardized methods (ref. EN 50122-2 or IEC 62128-2) have been almost unchanged in the last 20 years but suffer from accuracy issues and variability due to parameters and conditions not under the operator’s control. The uncertainty of test methods is increasingly important now that contractual specifications require a high level of insulation for new systems. A critical discussion and analysis of the sources of variability and practical constraints is proposed, followed by an evaluation of uncertainty, with the objective not only to assess the accuracy of the provided results, but also to foster research on innovative, more flexible and accurate methods.

A Novel Self-Assessment Method for Training Access Cavity on 3D Printed Endodontic Models.

New technologies can facilitate the transition from pre-clinical to clinical settings. We investigate students' satisfaction with a novel learning method adopted in access cavity exercises. Students performed their access cavity on inexpensive, in-house 3D printed teeth. Their performances were evaluated by scanning the prepared teeth with an intraoral scanner and visualized using a mesh processing software. Then, the same software was used to align the tooth prepared by the student and the teacher's one for self-assessment purposes. Students were asked to answer a questionnaire about their experiences with this new learning method. From the teacher's perspective, this novel learning approach was easy, straightforward and affordable. Overall, student feedback was positive: 73% found that access cavity assessment by scanning was more useful compared to a visual inspection under magnification and 57% reported that they had a better understanding of errors and mishaps. On the other hand, students pointed out that the material used to print teeth was too soft. The use of in-house 3D printed teeth in pre-clinical training is a simple way to overcome some of the drawbacks associated with extracted teeth, such as limited availability, variability, cross-infection control, and ethical constraints. The use of intraoral scanners and mesh processing software could improve student self-assessment.

Evidence of a lepto-hadronic two-zone emission in flare states

The BL Lac Markarian 501 exhibited two flaring activities in the very-high-energy (VHE) band in May 2009. The lack of correlation between X-rays and TeV gamma-rays without increasing in other bands suggested that more than one emission zone could be involved. Moreover, fast variability in the flaring state was observed, indicating that the emission zones responsible must have small sizes. We use a lepto-hadronic model with two-zone emission to explain the spectral energy distribution during quiescent and these flaring states. In the proposed scenario, the photopion processes explain the VHE flaring activities successfully, and variability constraints place the activity in a zone located near the jet’s base or named inner blob, while synchrotron self-Compton emission describing the X-ray signature during that flaring state occurs in the zone situated far the central engine or named outer blob.

Javelin use among Ethiopia’s last indigenous hunters: Variability and further constraints on tip cross-sectional geometry

Ethnographically known weapon systems are crucial for the functional interpretation of pertinent archaeological materials. The tip cross-sectional geometries of North American ethnographic projectiles are particularly widely used as standards against which the probable functions of archaeological stone points are assessed. While their known weapon-delivery mechanisms make these North American samples ideal references for archaeological investigations, their applicability to Afro-Eurasian assemblages is contestable. Using metric and contextual data from contemporary hunting javelins in southwestern Ethiopia, we expand on recent efforts to recalibrate such reference datasets. We find that overall javelin size and tip geometry are governed by factors ranging from the hunter’s age and physical competence to prey type and the intended hunting (e.g., startling, diverting, wounding, killing), and even symbolic/ceremonial, tasks. We argue that such dynamics may explain the great variation in the tip cross-sectional geometries of stone points in the archaeological record. Comparisons of our tip cross-sectional values with relevant published data provide further metric constraints and highlight the need for cautious interpretations of prehistoric weapon-delivery mechanisms where the role of symbolism and of children in the making of the archaeological record should also be considered.

Power sector decarbonization planning considering renewable resource variability and system operational constraints

Bottom-up long-term planning models generally consider low levels of spatial, temporal, and technical details to reduce associated computation. However, these details are required to capture spatial and temporal variability of Renewable Energy Sources (RESs) and perform harmonized dispatch of conventional generating units. In their absence, models may overestimate RESs uptake and underestimate the quantum of required flexible resources. This may create a false impression of sector decarbonization and the obtained capacity mix may result in frequent RES or load curtailment during real-time system operations. In this context, this study aims to improve upon the shortcomings of conventional planning approaches and develop a TIMES based planning model for the Indian power sector. The model adopts high spatial and temporal definitions of 5 regions and 288 sub-annual timeslices. RESs are categorized into sub-classes based on annual capacity factors to capture their intra-regional variations without further increasing the spatial resolution. Each month is represented by a day of chronological hourly resolution that facilitates the capture of RES temporal variations and incorporation of operational aspects of generating units such as minimum stable generation, ramp limits and partial load operation. The impact of these operational parameters on system planning is analysed to identify a trade-off between planning accuracy and computational complexity. The study is relevant for countries that are rigorously following their decarbonization plans with high penetration of variable RESs and have a similar trajectory as that of India. The results indicate that decarbonization levels can be better assessed if capacity mix and flexible resources are adequately valued by considering operational parameters at the planning stage for a power system dominated by low flexible generation.

What sets aeolian dune height?

Wherever a loose bed of sand is subject to sufficiently strong winds, aeolian dunes form at predictable wavelengths and growth rates. As dunes mature and coarsen, however, their growth trajectories become more idiosyncratic; nonlinear effects, sediment supply, wind variability and geologic constraints become increasingly relevant, resulting in complex and history-dependent dune amalgamations. Here we examine a fundamental question: do aeolian dunes stop growing and, if so, what determines their ultimate size? Earth’s major sand seas are populated by giant sand dunes, evolved over tens of thousands of years. We perform a global analysis of the topography of these giant dunes, and their associated atmospheric forcings and geologic constraints, and we perform numerical experiments to gain insight on temporal evolution of dune growth. We find no evidence of a previously proposed limit to dune size by atmospheric boundary layer height. Rather, our findings indicate that dunes may grow indefinitely in principle; but growth depends on morphology, slows with increasing size, and may ultimately be limited by sand supply.

First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole

In this paper we provide a first physical interpretation for the Event Horizon Telescope's (EHT) 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics simulations, including aligned, tilted, and stellar-wind-fed simulations; radiative transfer is performed assuming both thermal and nonthermal electron distribution functions. We test the models against 11 constraints drawn from EHT 230 GHz data and observations at 86 GHz, 2.2 μm, and in the X-ray. All models fail at least one constraint. Light-curve variability provides a particularly severe constraint, failing nearly all strongly magnetized (magnetically arrested disk (MAD)) models and a large fraction of weakly magnetized models. A number of models fail only the variability constraints. We identify a promising cluster of these models, which are MAD and have inclination i ≤ 30°. They have accretion rate (5.2–9.5) × 10−9 M ⊙ yr−1, bolometric luminosity (6.8–9.2) × 1035 erg s−1, and outflow power (1.3–4.8) × 1038 erg s−1. We also find that all models with i ≥ 70° fail at least two constraints, as do all models with equal ion and electron temperature; exploratory, nonthermal model sets tend to have higher 2.2 μm flux density; and the population of cold electrons is limited by X-ray constraints due to the risk of bremsstrahlung overproduction. Finally, we discuss physical and numerical limitations of the models, highlighting the possible importance of kinetic effects and duration of the simulations.

Australian Fire Emissions of Carbon Monoxide Estimated by Global Biomass Burning Inventories: Variability and Observational Constraints

AbstractAustralian fires are a primary driver of variability in Australian atmospheric composition and contribute significantly to regional and global carbon budgets. However, biomass burning emissions from Australia remain highly uncertain. In this work, we use surface in situ, ground‐based total column and satellite total column observations to evaluate the ability of two global models (GEOS‐Chem and ACCESS‐UKCA) and three global biomass burning emission inventories (FINN1.5, GFED4s, and QFED2.4) to simulate carbon monoxide (CO) in the Australian atmosphere. We find that emissions from northern Australia savanna fires are substantially lower in FINN1.5 than in the other inventories. Model simulations driven by FINN1.5 are unable to reproduce either the magnitude or the variability of observed CO in northern Australia. The remaining two inventories perform similarly in reproducing the observed variability, although the larger emissions in QFED2.4 combined with an existing high bias in the southern hemisphere background lead to large CO biases. We therefore recommend GFED4s as the best option of the three for global modeling studies with focus on Australia or the Southern Hemisphere. Near fresh fire emissions, the higher resolution ACCESS‐UKCA model is better able to simulate surface CO than GEOS‐Chem, while GEOS‐Chem captures more of the observed variability in the total column and remote surface air measurements. We also show that existing observations in Australia can only partially constrain global model estimates of biomass burning. Continuous measurements in fire‐prone parts of Australia are needed, along with updates to global biomass burning inventories that are validated with Australian data.

Berth and quay crane allocation and scheduling with worker performance variability and yard truck deployment in container terminals

In a container terminal, the quay cranes (QCs) are the main equipment involved in the core activities. According to a bottleneck principle, the productivity rate of QCs is related to both worker productivity and deployed yard trucks. Yet, in the literature, the berth and quay cranes allocation and scheduling problems were addressed separately from these two parameters. In contrast, practitioners confirm their important impact on cranes productivity and efficiency. This paper proposes a new extension of the berth and quay cranes allocation and scheduling problems considering worker performance variability and yard truck deployment constraints. First, we formulate the problem as a mixed-integer linear program to minimize the vessels departure time under many practical regulations involving the work roster constraints specific to container terminals and the trucks utilization congestion targets. Additionally, the study provides a computationally efficient method to find a lower bound. We also show that integrative planning minimizes the vessels departure time compared to the separated decision-making process. Second, to build good solutions in a reasonable time, we propose a heuristic and a Variable Neighborhood Search (VNS) with a new architecture and settings designed to suit the novel issues of the tackled problem. The algorithm is tested on real time data sets and outperforms a commercial solver. This study originates from our experience with a multinational company managing a container terminal. Thus, we have embedded the proposed resolving methods in a decision-support system for our industrial partner.

Tourmaline and quartz in the igneous and metamorphic rocks of the Tashisayi granitic batholith, Altyn Tagh, northwestern China: Geochemical variability constraints on metallogenesis

This study examines five rock units related to the Tashisayi chrysoberyl-bearing granitic batholith, Altyn Tagh, NW China: biotite granite, two-mica granite, muscovite granite, granitic pegmatite, and the surrounding biotite plagiogneiss. Three types of tourmalines and quartz are described, occur in the biotite plagiogneiss (Tur-1, Qtz-1), granitic rocks (two-mica granite [Tur-2a, Qtz-2a] and muscovite granite [Tur-2b, Qtz-2b]), and granitic pegmatite (Tur-3 and Qtz-3; tourmaline and quartz coexisting with chrysoberyl). Zircon UPb dating of the muscovite granite and granitic pegmatite yielded ages of 490–486 Ma for the Tashisayi batholith.The major-(by EPMA) and trace-element contents (by LA-ICP-MS) of the tourmaline and trace-elements (by LA-ICP-MS) and O-isotope (SIMS) of quartz indicates that: 1) The tourmalines are alkali schorl (Fe-rich tourmaline) and foitite; 2) tourmalines and quartz from the pegmatite have similar elemental concentrations and substitution mechanisms as tourmalines and quartz in granitic units of the Tashisayi batholith, but different from those of tourmalines and quartz in the biotite plagiogneiss, especially for Li, Be; 3) LA-ICP-MS analyses show that Qtz-1 in the biotite plagiogneiss has lower Ge/Ti values, lower Li, Be, Rb concentrations than Qtz-2a, Qtz-2b, and Qtz-3. Moreover, Qtz-2a, Qtz-2b, and Qtz-3 have a good positive correlation, consistent with whole-rock compositions, indicating crystal fractionation process in the formation of pegmatite, the chrysoberyl-bearing pegmatite is derived from a more evolved fluid than granitic rocks, thus, Li, Be are enriched by magmatism; 4) The O-isotopic compositions of Qtz-1 (+0.03 to +1.90‰) are consistent with a metamorphic water source, whereas the quartz in the two-mica granite (Qtz-2a; +8.85 to +9.58‰), in the muscovite granite (Qtz-2b; +9.27 to +9.93‰), and in the granitic pegmatite (Qtz-3; +14.8 to +17.8‰) are derived from the magmatic water or fluids from granite.

An empirical approach of past and present mobility management in the desert societies of camel breeders in South Eastern Morocco

Nomad, semi-nomad and transhumant used to be the most frequent mobility types of pastoral society. Nowadays, these categories become questionable in regard to the evolution of the pattern life of families in southern Morocco. How do we link past and present mobility? What have been the changes? In this article, we question the relevance of the aforementioned categories of mobility, as defined by the actors of scientific research and development, to analyze and classify pastoral mobility management that condition the way of life and the adaptive capacities of Saharan societies, by mobilizing different corpus such as ‘récit de vie’ and typology. This study was conducted downstream in the Drâa Valley (Morocco). If the majority of breeders claim to be nomads as soon as they practice a pattern of living in a tent over the course of a year, the typology of mobility pattern reveals intra- and inter-annual fluctuations of its management embedded in their adaptive strategies to climate variability or economic constraints which makes difficult to classify breeders according to the mobility only. In this context, developing climate change mitigation interventions for pastoral societies need to understand and integrate the permanent changing pattern of mobility management in these pastoral societies.

Conservation agriculture enhances the rice-wheat system of the Eastern Gangetic Plains in some environments, but not in others

• Intensification of the rice-wheat system increased system productivity. • CA further enhanced the baseline system though CA benefits are environment-specific. • In fine-textured soil (silt-loam), CA enhanced system productivity and resource use efficiency. • In course-textured soil (sandy-loam), the system benefit (productivity and resource use efficiency) of full CA seems limited. Increasing productivity of the rice-wheat system (RW) in the Eastern Gangetic Plains (EGP) is a major challenge in the context of the various economic (increasing cost of labour, irrigation water, and energy) and bio-physical (water scarcity, depletion of soil fertility, and climatic variability) constraints. We evaluated the performance of three RW system intensification options with different management interventions over two years, comparing a conventional RW rotation (CS 1 ), with two stages of conservation agriculture (CA) interventions, (i) the simple inclusion of mungbean (CS 2 ), and (ii) the inclusion of mungbean together with full CA implementation (CS 3 ) at two sites in the EGP that differed with respect to soil type, water table dynamics, and agro-climatic conditions. Our evaluation focussed on improving system productivity and resource use efficiency. The addition of mungbean into the conventional RW rotation produced significantly higher system productivity (rice equivalent yield, REY) compared with the existing double-crop rotation across sites. The baseline system was enhanced further when CA-based management practices were adopted, however, the magnitude of system benefit from CA was site and situation-specific. At the fine-textured soil site, gains were observed in system production (by 5.4 %), irrigation water productivity (WP I , by 40 %), and N use efficiency (NUE, by 5%) for the CA-based intensified system (CS 3 ) in comparison with the CT-based intensified system (CS 2 ). The average wheat yield and WP I in the zero-till (ZT) system (CS 3 ) was always higher than in the conventional (CT) systems (CS 1 and CS 2 ), mainly due to enhanced wheat rooting after unpuddled rice across the sites. At the fine-textured soil site, the cessation of puddling in rice cropping maintained rice grain yield, while increasing WP I . However, in the coarse-textured soil site, the cessation of puddling resulted in lower rice grain production (by 14 %), coupled with much higher (1.3 times) irrigation water requirement than the conventional puddled rice systems (CS 1 and CS 2 ) in the second year due to increased percolation rate, which negatively impacted the overall performance of the CA-based system (CS 3 ). Therefore, the modification of the traditional CT-based system to an intensified CA-based approach can improve the productivity of the RW system in terms of yield of the component crops as well as better NUE and WP I in fine-textured soil, while the feasibility of the full CA system in coarse-textured soil seems limited due to poor performance of rice, and requires further research focusing on the best rice establishment option.

Rainfall variability and socio-economic constraints on livestock production in the Ngorongoro Conservation Area, Tanzania

Rainfall variability is of great importance in East Africa, where small-scale farmers and pastoralists dominate. Their livestock production activities are heavily dependent on rainfall. We assessed pastoralist perceptions on climate change, particularly rainfall variability, its impact on livestock production, and the adaptive capacity of pastoralists in the Ngorongoro Conservation Area (NCA), Tanzania. We combined 241 household interviews and information from 52 participants of Participatory Rural Appraisal (PRA) with archived data from the Ngorongoro Conservation Area Authority (NCAA). We found that most (71%) pastoralists were aware of general climate change impacts, rainfall variability, and impacts of extreme events on their livestock. Most (> 75%) respondents perceived erratic and reduced amounts of rainfall, prolonged and frequent periods of drought as the main climate change challenges. Mean annual rainfall accounted for only 46% (R2), (p = 0.076) and 32% (R2), (p = 0.22) of cattle, and sheep and goat population variability, respectively. Unexpectedly, cattle losses intensified by 10% when herd size increased (p < 0.001) and by 98% (p = 0.049) when mobility increased, implying that increasing herd sizes and mobility do not cushion households against climate change shocks. Our study highlights the need to enhance adaptive capacity of the pastoralist communities through interventions that proactively reduce vulnerability. We recommend that future research should address the profitability of pastoral cattle production under changing environmental conditions.

A review on the benefits of yoga in children

In Malaysia, the number of youngsters suffering from stress and anxiety is increasing. Mind-body treatments such as mindfulness therapy, meditation, and yoga have been used to decrease and/or manage the psychological consequences of stress and anxiety in many different nations, according to evidence. The intervention of yoga as a meditative movement practice in helping schoolchildren manage stress and anxiety is examined in this review study. A variety of databases, including PubMed/MEDLINE and PsycINFO, were used to find articles. This review includes both peer-reviewed and non-peer-reviewed papers published in English. All of the research looked at included some kind of contemplative movement practice. The yoga pathways of asanas (postures), pranayama (expansion of life force), dharana (concentration), and dhyana (meditation) were all included in the intervention. A total of eight papers were evaluated after meeting the inclusion criteria. The results of this study show that yoga may help with stress management and anxiety reduction, among other things. Despite the variability and sample size constraints in most, if not all, of the research examined, yoga seems to be an effective technique for helping children deal with stress and anxiety. It seems that including yoga into the physical education curriculum in Malaysian schools will be beneficial to pupils.

ЗАСТОСУВАННЯ ІНСТРУМЕНТІВ МАРКЕТИНГОВИХ КОМУНІКАЦІЙ В УМОВАХ КРИЗИ

The world is experiencing an unprecedented crisis. As the situation with COVID-19 continues to unfold, and governments are taking swift action and decisive action to combat this global pandemic, businesses need to constantly rethink their choices and priorities. It is rare to see the whole world come together to overcome a common problem. It’s global, it’s open, and it can affect every business and every person. During the crisis, people turn to institutions for advice, reassurance and information. Increasingly, they are also looking at trading companies. In today’s environment of high uncertainty, rapid environmental variability and tight budget constraints, all market participants are forced to look for non-standard solutions for effective promotion strategies. The priority measures of anti-crisis marketing activities are marketing communications. They play an important role in shaping consumer choices. This choice applies not only to the product or service, but also to the management of messages and goals. Given the role of information in modern retail, it is advisable to analyze the features and essence of modern tools of marketing communications, the impact of the global crisis on the field of marketing communications. The urgency of the study is caused by the high degree of uncertainty in the market situation due to the global pandemic around the world. The Ukrainian market, contrary to foreign countries, is not adapted to such conditions. The article identifies the feasibility of using marketing communication tools to ensure consumer awareness of retail businesses. The regional structure of retail trade turnover, the change of real income volume of the population, as well as the change in consumer prices in Ukraine are analyzed. The expediency of maximizing attention to the choice of tools for marketing communications policy is explained. The difficulties of traditional tools implementation in marketing communications during crisis are investigated. The necessity of redistribution of the marketing budget with receiving the maximum result is defined. In the future, the results of this study can be used in the theory of marketing communication policy of enterprises in order to develop measures to improve its effectiveness in times of crisis.

Transfer learning from adult to children for speech recognition: Evaluation, analysis and recommendations

Children speech recognition is challenging mainly due to the inherent high variability in children’s physical and articulatory characteristics and expressions. This variability manifests in both acoustic constructs and linguistic usage due to the rapidly changing developmental stage in children’s life. Part of the challenge is due to the lack of large amounts of available children speech data for efficient modeling. This work attempts to address the key challenges using transfer learning from adult’s models to children’s models in a Deep Neural Network (DNN) framework for children’s Automatic Speech Recognition (ASR) task evaluating on multiple children’s speech corpora with a large vocabulary. The paper presents a systematic and an extensive analysis of the proposed transfer learning technique considering the key factors affecting children’s speech recognition from prior literature. Evaluations are presented on (i) comparisons of earlier GMM-HMM and the newer DNN Models, (ii) effectiveness of standard adaptation techniques versus transfer learning, (iii) various adaptation configurations in tackling the variabilities present in children speech, in terms of (a) acoustic spectral variability, and (b) pronunciation variability and linguistic constraints. Our Analysis spans over (i) number of DNN model parameters (for adaptation), (ii) amount of adaptation data, (iii) ages of children, (iv) age dependent-independent adaptation. Finally, we provide Recommendations on (i) the favorable strategies over various aforementioned - analyzed parameters, and (ii) potential future research directions and relevant challenges/problems persisting in DNN based ASR for children’s speech.

Controller synthesis of service contracts with variability

Abstract Service contracts characterise the desired behavioural compliance of a composition of services. Compliance is typically defined by the fulfilment of all service requests through service offers, as dictated by a given Service-Level Agreement (SLA). Contract automata are a recently introduced formalism for specifying and composing service contracts. Based on the notion of synthesis of the most permissive controller from Supervisory Control Theory, a safe orchestration of contract automata can be computed that refines a composition into a compliant one. To model more fine-grained SLA and more adaptive service orchestrations, in this paper we endow contract automata with two orthogonal layers of variability: (i) at the structural level, constraints over service requests and offers define different configurations of a contract automaton, depending on which requests and offers are selected or discarded, and (ii) at the behavioural level, service requests of different levels of criticality can be declared, which induces the novel notion of semi-controllability. The synthesis of orchestrations is thus extended to respect both the structural and the behavioural variability constraints. Finally, we show how to efficiently compute the orchestration of all configurations from only a subset of these configurations. A prototypical tool supports the developed theory.

TCT-515 Marked Variability and Regional Constraints: Observations From a Population-Based and Telemedicine-Guided STEMI Program

TCT-515 Marked Variability and Regional Constraints: Observations From a Population-Based and Telemedicine-Guided STEMI Program