scholarly journals A Novel Dynamic Model of a Reaction Wheel Assembly for High Accuracy Pointing Space Missions

2018 ◽  
Author(s):  
Francesco Sanfedino ◽  
Daniel Alazard ◽  
Valérie Pommier-Budinger ◽  
Fabrice Boquet ◽  
Alexandre Falcoz
Keyword(s):  
Dynamic Model ◽  
Structural Design ◽  
Control Strategies ◽  
High Accuracy ◽  
Line Of Sight ◽  
Reaction Wheel ◽  
Micro Vibration ◽  
The Impact ◽  
Structured Approach

This paper proposes a novel dynamic model of a Reaction Wheel Assembly (RWA) based on the Two-Input Two-Output Port framework, already presented by the authors. This method allows the user to study a complex system with a sub-structured approach: each sub-element transfers its dynamic content to the other sub-elements through local attachment points with any set of boundary conditions. An RWA is modelled with this approach and it is then used to study the impact of typical reaction wheel perturbations on a flexible satellite in order to analyze the micro-vibration content for a high accuracy pointing mission. This formulation reveals the impact of any structural design parameter and highlights the need of passive isolators to reduce the micro-vibration issues. The frequency analysis of the transfer between the disturbance sources and the line-of-sight (LOS) jitter highlights the role of the reaction wheel speed on the flexible modes migration and suggests which control strategies can be considered to mitigate the residual micro-vibration content in order to fulfil the mission performances.

scholarly journals Out of sight, out of mind? The impact of correlated clustering in substructure lensing

2021 ◽  
Author(s):  
Alexandres Lazar ◽  
James S Bullock ◽  
Michael Boylan-Kolchin ◽  
Robert Feldmann ◽  
Onur Çatmabacak ◽  
...  
Keyword(s):  
Dark Matter ◽  
Principal Axis ◽  
Major Axis ◽  
Line Of Sight ◽  
Gravitational Lenses ◽  
Local Clustering ◽  
Analytic Expression ◽  
Halo Masses ◽  
The Impact

Abstract A promising route for revealing the existence of dark matter structures on mass scales smaller than the faintest galaxies is through their effect on strong gravitational lenses. We examine the role of local, lens-proximate clustering in boosting the lensing probability relative to contributions from substructure and unclustered line-of-sight (LOS) haloes. Using two cosmological simulations that can resolve halo masses of Mhalo ≃ 109 M⊙ (in a simulation box of length Lbox ∼ 100 Mpc) and 107 M⊙ (Lbox ∼ 20 Mpc), we demonstrate that clustering in the vicinity of the lens host produces a clear enhancement relative to an assumption of unclustered haloes that persists to >20 Rvir. This enhancement exceeds estimates that use a two-halo term to account for clustering, particularly within 2 − 5 Rvir. We provide an analytic expression for this excess, clustered contribution. We find that local clustering boosts the expected count of 109 M⊙ perturbing haloes by ${\sim }35{{\ \rm per\ cent}}$ compared to substructure alone, a result that will significantly enhance expected signals for low-redshift (zl ≃ 0.2) lenses, where substructure contributes substantially compared to LOS haloes. We also find that the orientation of the lens with respect to the line of sight (e.g. whether the line of sight passes through the major axis of the lens) can also have a significant effect on the lensing signal, boosting counts by an additional $\sim 50{{\ \rm per\ cent}}$ compared to a random orientations. This could be important if discovered lenses are biased to be oriented along their principal axis.

scholarly journals Assessing the role of inter-facility patient transfer in the spread of carbapenemase-producing Enterobacteriaceae: the case of France between 2012 and 2015

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Narimane Nekkab ◽  
Pascal Crépey ◽  
Pascal Astagneau ◽  
Lulla Opatowski ◽  
Laura Temime
Keyword(s):  
Control Strategies ◽  
Patient Transfer ◽  
Spatial Distance ◽  
Patient Transfers ◽  
Healthcare Facilities ◽  
Healthcare Settings ◽  
The Impact ◽  
Local Transmission

Abstract The spread of carbapenemase-producing Enterobacteriaceae (CPE) in healthcare settings is a major public health threat that has been associated with cross-border and local patient transfers between healthcare facilities. Since the impact of transfers on spread may vary, our study aimed to assess the contribution of a patient transfer network on CPE incidence and spread at a countrywide level, with a case study of France from 2012 to 2015. Our results suggest a transition in 2013 from a CPE epidemic sustained by internationally imported episodes to an epidemic sustained by local transmission events through patient transfers. Incident episodes tend to occur within close spatial distance of their potential infector. We also observe an increasing frequency of multiple spreading events, originating from a limited number of regional hubs. Consequently, coordinated prevention and infection control strategies should focus on transfers of carriers of CPE to reduce regional and inter-regional transmission.

Surviving from garbage: the role of informal waste-pickers in a dynamic model of solid-waste management in developing countries

2006 ◽  
Vol 11 (3) ◽  
pp. 371-391 ◽  
Author(s):  
ROCÍO DEL PILAR MORENO-SÁNCHEZ ◽  
JORGE HIGINIO MALDONADO
Keyword(s):  
Developing Countries ◽  
Waste Management ◽  
Solid Waste ◽  
Dynamic Model ◽  
Solid Waste Management ◽  
Waste Collection ◽  
Management Policies ◽  
The Impact ◽  
Waste Pickers

In developing countries, informal waste-pickers (known as scavengers) play an important role in solid waste management systems, acting in a parallel way to formal waste collection and disposal agents. Scavengers collect, from the streets, dumpsites, or landfills, re-usable and recyclable material that can be reincorporated into the economy's production process. Despite the benefits that they generate to society, waste-pickers are ignored when waste management policies are formulated. The purpose of this paper is to integrate the role of scavengers in a dynamic model of production, consumption, and recovery, and to show that, in an economy producing solid waste, efficiency can be reached using a set of specific and complementary policies: a tax on virgin materials use, a tax on consumption and disposal, and a subsidy to the recovery of material. A numerical simulation is performed to evaluate the impact of these policies on landfill lifetime and natural resource stocks. A discussion on the implementation of these instruments is also included.

scholarly journals Mathematical modelling and phylodynamics for the study of dog rabies dynamics and control: A scoping review

2021 ◽  
Vol 15 (5) ◽  
pp. e0009449
Author(s):  
Maylis Layan ◽  
Simon Dellicour ◽  
Guy Baele ◽  
Simon Cauchemez ◽  
Hervé Bourhy
Keyword(s):  
Mathematical Modelling ◽  
Mathematical Models ◽  
Scoping Review ◽  
Control Strategies ◽  
Domestic Dog ◽  
Interdisciplinary Approaches ◽  
Dynamics And Control ◽  
And Control ◽  
The Impact

Background Rabies is a fatal yet vaccine-preventable disease. In the last two decades, domestic dog populations have been shown to constitute the predominant reservoir of rabies in developing countries, causing 99% of human rabies cases. Despite substantial control efforts, dog rabies is still widely endemic and is spreading across previously rabies-free areas. Developing a detailed understanding of dog rabies dynamics and the impact of vaccination is essential to optimize existing control strategies and developing new ones. In this scoping review, we aimed at disentangling the respective contributions of mathematical models and phylodynamic approaches to advancing the understanding of rabies dynamics and control in domestic dog populations. We also addressed the methodological limitations of both approaches and the remaining issues related to studying rabies spread and how this could be applied to rabies control. Methodology/principal findings We reviewed how mathematical modelling of disease dynamics and phylodynamics have been developed and used to characterize dog rabies dynamics and control. Through a detailed search of the PubMed, Web of Science, and Scopus databases, we identified a total of n = 59 relevant studies using mathematical models (n = 30), phylodynamic inference (n = 22) and interdisciplinary approaches (n = 7). We found that despite often relying on scarce rabies epidemiological data, mathematical models investigated multiple aspects of rabies dynamics and control. These models confirmed the overwhelming efficacy of massive dog vaccination campaigns in all settings and unraveled the role of dog population structure and frequent introductions in dog rabies maintenance. Phylodynamic approaches successfully disentangled the evolutionary and environmental determinants of rabies dispersal and consistently reported support for the role of reintroduction events and human-mediated transportation over long distances in the maintenance of rabies in endemic areas. Potential biases in data collection still need to be properly accounted for in most of these analyses. Finally, interdisciplinary studies were determined to provide the most comprehensive assessments through hypothesis generation and testing. They also represent new avenues, especially concerning the reconstruction of local transmission chains or clusters through data integration. Conclusions/significance Despite advances in rabies knowledge, substantial uncertainty remains regarding the mechanisms of local spread, the role of wildlife in dog rabies maintenance, and the impact of community behavior on the efficacy of control strategies including vaccination of dogs. Future integrative approaches that use phylodynamic analyses and mechanistic models within a single framework could take full advantage of not only viral sequences but also additional epidemiological information as well as dog ecology data to refine our understanding of rabies spread and control. This would represent a significant improvement on past studies and a promising opportunity for canine rabies research in the frame of the One Health concept that aims to achieve better public health outcomes through cross-sector collaboration.

The Vital Role of Proteomics in Characterizing Novel Protein Degraders

2021 ◽  
pp. 247255522098577
Author(s):  
Andrew X. Zhang ◽  
Katelyn Cassidy ◽  
Göran Dahl ◽  
Kevin Moreau ◽  
Fiona Pachl ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Mechanisms Of Action ◽  
Vital Role ◽  
Line Of Sight ◽  
Efficacy And Safety ◽  
E3 Ligases ◽  
Drug Candidates ◽  
The Impact ◽  
Novel Protein

Mass spectrometry-based proteomics profiling is a discovery tool that enables researchers to understand the mechanisms of action of drug candidates. When applied to proteolysis targeting chimeras (PROTACs) such approaches provide unbiased perspectives of the binding, degradation selectivity, and mechanism related to efficacy and safety. Specifically, global profiling experiments can identify direct degradation events and assess downstream pathway modulation that may result from degradation or off-target inhibition. Targeted proteomics approaches can be used to quantify the levels of relevant E3 ligases and the protein of interest in cell lines and tissues of interest, which can inform the line of sight and provide insights on possible safety liabilities early in the project. Furthermore, proteomics approaches can be applied to understand protein turnover and resynthesis rates and inform on target tractability, as well as pharmacokinetics/pharmacodynamics understanding. In this perspective, we survey the literature around the impact of mass spectrometry-based proteomics in the development of PROTACs and present our envisioned proteomics cascade for supporting targeted protein degradation projects.

scholarly journals Role of Time Scales in the Coupled Epidemic-Opinion Dynamics on Multiplex Networks

Entropy ◽  
2022 ◽  
Vol 24 (1) ◽  
pp. 105
Author(s):  
Robert Jankowski ◽  
Anna Chmiel
Keyword(s):  
Dynamic Model ◽  
Crucial Role ◽  
Opinion Dynamics ◽  
Point Of View ◽  
Entire System ◽  
Epidemic Spreading ◽  
Multiplex Networks ◽  
The Impact ◽  
Opinion Dynamic

Modelling the epidemic’s spread on multiplex networks, considering complex human behaviours, has recently gained the attention of many scientists. In this work, we study the interplay between epidemic spreading and opinion dynamics on multiplex networks. An agent in the epidemic layer could remain in one of five distinct states, resulting in the SIRQD model. The agent’s attitude towards respecting the restrictions of the pandemic plays a crucial role in its prevalence. In our model, the agent’s point of view could be altered by either conformism mechanism, social pressure, or independent actions. As the underlying opinion model, we leverage the q-voter model. The entire system constitutes a coupled opinion–dynamic model where two distinct processes occur. The question arises of how to properly align these dynamics, i.e., whether they should possess equal or disparate timescales. This paper highlights the impact of different timescales of opinion dynamics on epidemic spreading, focusing on the time and the infection’s peak.

scholarly journals Analysis of COVID-19 Prevention and Control Effects Based on the SEITRD Dynamic Model and Wuhan Epidemic Statistics

2020 ◽  
Vol 17 (24) ◽  
pp. 9309
Author(s):  
Yusheng Zhang ◽  
Liang Li ◽  
Yuewen Jiang ◽  
Biqing Huang
Keyword(s):  
Dynamic Model ◽  
Control Method ◽  
Control Strategies ◽  
Dynamical Behavior ◽  
Model Parameters ◽  
Time Control ◽  
Intervention Measures ◽  
Travel Restrictions ◽  
And Control ◽  
The Impact

Since December 2019, millions of people worldwide have been diagnosed with COVID-19, which has caused enormous losses. Given that there are currently no effective treatment or prevention drugs, most countries and regions mainly rely on quarantine and travel restrictions to prevent the spread of the epidemic. How to find proper prevention and treatment methods has been a hot topic of discussion. The key to the problem is to understand when these intervention measures are the best strategies for disease control and how they might affect disease dynamics. In this paper, we build a transmission dynamic model in combination with the transmission characteristics of COVID-19. We thoroughly study the dynamical behavior of the model and analyze how to determine the relevant parameters, and how the parameters influence the transmission process. Furthermore, we subsequently compare the impact of different control strategies on the epidemic, the variables include intervention time, control duration, control intensity, and other model parameters. Finally, we can find a better control method by comparing the results under different schemes and choose the proper preventive control strategy according to the actual epidemic stage and control objectives.

INVESTIGATING THE ROLE OF WITHIN- AND BETWEEN-PATCH MOVEMENT IN A DYNAMIC MODEL OF DISEASE SPREAD

2020 ◽  
Vol 28 (04) ◽  
pp. 815-837
Author(s):  
KLOT PATANARAPEELERT
Keyword(s):  
Dynamic Model ◽  
Gravity Model ◽  
Transmission Rate ◽  
Human Mobility ◽  
Disease Spread ◽  
The Difference ◽  
Invasion Threshold ◽  
The Impact ◽  
Local Transmission

The impact of human mobility on the spreading of disease in a metapopulation is emphasized on interconnecting between patches, whereas the current volume of movement within the local population is usually neglected. Here, the role of internal commuters is taken into account by two means, a local transmission rate and the volume of internal commuters. Dynamic model of human mobility in the metapopulation with gravity coupling is presented. In conjunction with the disease spreading, the impact on invasion threshold and epidemic final size are analyzed. For two-patch model, we show that under fixing parameters in gravity model, the existence of invasion threshold depends on the difference of local transmission rates and the proportion of internal commuters between two patches. For a fully connected network with an identical transmission rate, the difference in patch final sizes is driven by patch distribution of internal commuters. By neglecting the effect of spatial variation in a simple core–satellite model, we show that the heterogeneity of internal commuters and gravity coupling induce a complex pattern of threshold, which depend mostly on the exponent in gravity model, and are responsible for the differences among local epidemic sizes.

Atrial Fibrillation and Cognitive Impairment: An Associated Burden or Burden by Association?

Angiology ◽  
2020 ◽  
Vol 71 (6) ◽  
pp. 498-519
Author(s):  
Theodora A. Manolis ◽  
Antonis A. Manolis ◽  
Evdoxia J. Apostolopoulos ◽  
Helen Melita ◽  
Antonis S. Manolis
Keyword(s):  
Risk Factors ◽  
Atrial Fibrillation ◽  
Cognitive Impairment ◽  
Control Strategies ◽  
Brain Magnetic Resonance Imaging ◽  
Cerebral Hypoperfusion ◽  
The Impact ◽  
Vascular Oxidative Stress ◽  
Prior Stroke

Growing evidence suggests that atrial fibrillation (AF), in addition to its thromboembolic risk, is a risk factor for cognitive impairment (CI) via several pathways and mechanisms, further contributing to morbidity/mortality. Prior stroke is a contributor to CI, but AF is also associated with CI independently from prior stroke. Silent brain infarctions, microemboli and microbleeds, brain atrophy, cerebral hypoperfusion from widely fluctuating ventricular rates, altered hemostatic function, vascular oxidative stress, and inflammation may all exacerbate CI, particularly in patients with persistent/permanent rather than paroxysmal AF and with increased duration/burden of the arrhythmia. Brain magnetic resonance imaging is an important screening tool in eliciting and monitoring vascular and nonvascular lesions contributing to CI. Evidence is also emerging about the role of genetics in CI development. Anticoagulation and rhythm/rate control strategies may protect against CI preventing or slowing its progression or conversion to dementia, particularly at the early stages when CI may still be a treatable condition. Importantly, AF and CI share many common risk factors. Thus, screening for these 2 conditions and searching for and managing modifiable risk factors and potentially reversible causes for both AF and CI remains an important step toward prevention or amelioration of the impact incurred by these 2 conditions.

Cognitive Control Processes in Paranoia: The Impact of Threat Induction on Strategic Cognition and Self-Focused Attention

2013 ◽  
Vol 43 (1) ◽  
pp. 108-118 ◽  
Author(s):  
Laura Flower ◽  
Katherine Newman-Taylor ◽  
Lusia Stopa
Keyword(s):  
Experimental Design ◽  
Social Control ◽  
Cognitive Processes ◽  
Control Strategies ◽  
Cognitive Strategies ◽  
Focused Attention ◽  
Strategic Cognition ◽  
Clinical Models ◽  
The Impact

Background:Current clinical models emphasize certain cognitive processes in the maintenance of distressing paranoia. While a number of these processes have been examined in detail, the role of strategic cognition and self-focused attention remain under-researched.Aims:This study examined the deployment of cognitive strategies and self-focused attention in people with non-clinical paranoia.Method:An experimental design was used to examine the impact of a threat activation task on these processes, in participants with high and low non-clinical paranoia. Twenty-eight people were recruited to each group, and completed measures of anxiety, paranoid cognition, strategic cognition and self-focused attention.Results:The threat activation task was effective in increasing anxiety in people with high and low non-clinical paranoia. The high paranoia group experienced more paranoid cognitions following threat activation. This group also reported greater use of thought suppression, punishment and worry, and less use of social control strategies when under threat. No differences were found between the groups on measures of self-focused attention.Conclusions:This study shows that the threat activation task increased anxiety in people with high non-clinical paranoia, leading to increased paranoid thinking. The use of strategic cognition following threat activation varied dependent on level of non-clinical paranoia. If these differences are replicated in clinical groups, the strategies may be implicated in the maintenance of distressing psychosis, and may therefore be a valuable target for therapeutic intervention.

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